Autoimmune Pancreatitis

Complex MONDO:0015175 Pathograph 48 Show in embeddings browser Pancreatitis Immune-Mediated Inflammatory Disease

Autoimmune pancreatitis is an immune-mediated fibroinflammatory pancreatic disorder with two established subtypes. Type 1 is the pancreatic manifestation of IgG4-related disease, with lymphoplasmacytic infiltration, storiform fibrosis and obliterative phlebitis. Type 2 is characterized by neutrophilic duct epithelial injury and granulocytic epithelial lesions and is associated with inflammatory bowel disease. Both can cause pancreatic enlargement, duct abnormalities, obstructive jaundice or acute pancreatitis and often respond to glucocorticoids. Diagnosis requires integration of imaging, serology, histology and clinical context because pancreatic malignancy can resemble AIP. Immune-checkpoint-inhibitor-associated pancreatic injury is a related drug-induced condition; its proposed designation as type 3 AIP remains provisional.

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Classifications

Harrison's Part

◆

Subtypes

Type 1 (lymphoplasmacytic sclerosing pancreatitis, IgG4-related) MONDO:0017227

IgG4-related lymphoplasmacytic sclerosing pancreatitis, usually presenting in older adults. Characteristic tissue findings include IgG4-rich lymphoplasmacytic infiltration, storiform fibrosis and obliterative phlebitis. Serum IgG4 may be elevated but is neither universally abnormal nor independently diagnostic. Other IgG4-related organs can be involved, and relapse is more common than in type 2.

Show evidence (1 reference)

PMID:29512140 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Type 1 AIP (also called LPSP) is characterized by dense lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis. This is accompanied by massive accumulation of IgG4-expressing plasma cells and, in some patients with elevated levels of serum IgG4 and involvement of other..."

Review synthesis of type 1 histology and systemic involvement.

Type 2 (idiopathic duct-centric pancreatitis, IDCP) MONDO:0017228

Idiopathic duct-centric pancreatitis with granulocytic epithelial lesions and few or no IgG4-positive plasma cells. It more often presents with acute pancreatitis in younger patients and can accompany inflammatory bowel disease, particularly ulcerative colitis. It is not the pancreatic manifestation of systemic IgG4-related disease; rare extrapancreatic granulocytic epithelial lesions have been reported.

Show evidence (1 reference)

PMID:34670874 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Type 2 AIP is unrelated to IgG4 and is a completely distinct entity from type 1 AIP. One confusing factor is that the two types of AIP share patterns of clinical presentation (e.g., acute pancreatitis and painless jaundice) and imaging abnormalities (e.g., diffuse or segmental enlargement)...."

Type 2 is a distinct histological and clinical entity.

Discussions and Knowledge Gaps

Does smoking independently modify endocrine outcomes in established type 1 AIP?

KNOWLEDGE GAP OPEN aip_smoking_endocrine_association

Attached to

phenotypes#Diabetes mellitus

A retrospective cohort of 59 patients with established type 1 AIP associated smoking with prevalent diabetes at AIP diagnosis. It had no non-AIP comparison group and does not estimate smoking-related risk of developing AIP. The follow-up association was borderline, and occupation lost its baseline diabetes association after adjustment for smoking. These observations do not establish a pancreatic causal mechanism or a benefit from a tested smoking-cessation intervention.

Show evidence (2 references)

PMID:35807009 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"At multivariable analysis, smoking (OR = 4.92; 95% CI 1.22–19.9) and obstructive jaundice (OR = 9.47; 95% CI 2.06–43.5) were strongly associated with the presence of DM at diagnosis of AIP"

The outcome is diabetes within an AIP cohort, not AIP occurrence.

PMID:35807009 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"After an adjustment for smoking, the association between blue-collar professions and DM at diagnosis lost statistical significance."

Smoking and occupation are not demonstrated independent causal pathways.

How should established AIP subtypes be distinguished from checkpoint-inhibitor pancreatic injury?

CONTROVERSY aip_subtype_boundary

Attached to

has_subtypes#Type 1 has_subtypes#Type 2

Type 1 and type 2 share some imaging appearances and glucocorticoid responsiveness but differ in histology, systemic associations and relapse. Immune-checkpoint-inhibitor pancreatic injury has been proposed as type 3, but it is a drug-associated spectrum with variable biochemical and clinical definitions, limited tissue series and uncertain steroid benefit. It is kept as a diagnostic boundary rather than assumed to share the established type 1 or type 2 pathways.

Show evidence (2 references)

PMID:34670874 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Although type 2 AIP shares some features with type 1 AIP, these two conditions are distinct without any overlaps.5 Table 1 summarizes the features of two types of AIP."

Review of established subtype distinctions.

PMID:41922528 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"The advent of ICI therapy has introduced a distinct form of immune-mediated pancreatic injury, which some investigators have proposed designating as type 3 autoimmune pancreatitis [7–9]."

Recent review discusses a proposed drug-associated category.

Which immunoglobulin functions contribute to human pancreatic injury?

KNOWLEDGE GAP aip_igg4_marker_or_mediator

Attached to

pathophysiology#Increased IgG4 Secretion pathophysiology#Acinar Tissue Injury

IgG4 enrichment is neither proof of a single pathogenic effector nor proof of a harmless marker. Published neonatal-mouse transfer experiments found injury with both patient IgG1 and IgG4, greater injury with IgG1 and attenuation when IgG4 accompanied IgG1. Antigen, tissue context, subclass composition and chronic human immune initiation remain unresolved. B-cell depletion efficacy does not identify which antibody or antigen-presentation function mediates benefit.

Show evidence (1 reference)

PMID:26964842 SUPPORT DIRECT PRIMARY RESULT Model Organism

"RESULTS: Subcutaneous injection of patient IgG, but not control IgG, resulted in pancreatic and salivary gland injuries. Pancreatic injury was also induced by injecting patient IgG1 or IgG4, with more destructive changes induced by IgG1 than by IgG4. The potent pathogenic activity of patient..."

Human IgG passive transfer into neonatal mice; abstract-supported scope.

Which experimental immune pathways are necessary in human type 1 AIP?

KNOWLEDGE GAP aip_human_causal_scope

Attached to

pathophysiology#Plasmacytoid Dendritic Cell Activation pathophysiology#CD4+SLAMF7+ Cytotoxic T Lymphocyte Expansion

Preventive mouse pDC/IFNAR interventions, human coculture perturbations and systemic IgG4-RD T-cell assays support candidate mechanisms at different scales. The small human CTL study included ten pancreatic cases among 18 systemic cases; bulk tissue TCR overlap in two patients cannot prove the identity of every pancreatic infiltrating cell. Cytokine secretion and nonpancreatic target killing do not establish the entire CTL-to-pancreatic-fibrosis route. IgG4 output does not resolve class switching, BAFF necessity or the initiating human NET stimulus.

Show evidence (3 references)

url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf SUPPORT INDIRECT PRIMARY RESULT In Vitro

"In addition, inhibition of NET formation by DNase or blockade of IFN- a–mediated signaling pathways by anti-IFNAR Ab signiﬁcantly reduced IgG4 production in a coculture system comprised of control B cells, patient-derived neutrophils, and patient-derived pDCs (Fig. 7C)."

DNase and IFNAR blockade reduced IgG4 secretion in a defined human coculture; intervening signals remain unresolved.

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

"These CD4+ SLAMF7+ T cells cells have potent cytolytic function; upon in vitro stimulation with anti-CD3, these cells undergo degranulation as inferred from the surface expression of CD107a (Fig 2, D) and exhibit cytotoxic activity against allogeneic EBV-transformed B cell targets (Fig 2, E and Fig E6)."

The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.

PMID:29499100 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Eighteen patients (11 male, 7 female) with a mean age of 64 years (range, 47-83 years) were included in the study (Table 1)."

Small systemic cohort scope.

How do treatment and disease activity affect long-term pancreatic function and cancer risk?

KNOWLEDGE GAP aip_long_term_risk

Attached to

phenotypes#Exocrine pancreatic insufficiency phenotypes#Diabetes mellitus

Published cohorts differ in selection, testing completeness, therapy and follow-up. Associations of maintenance steroids with relapse or survival are not randomized estimates, while steroids can improve or worsen glucose control. A selected decade-long cohort had only two pancreatic cancers and broad confidence intervals; neither a proven excess risk nor a universal cancer-surveillance interval follows. Shorter type 2 series and biopsy-dependent ascertainment further limit cross-subtype prognosis comparisons.

Show evidence (2 references)

PMID:42185503 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Overall malignancy risk was not increased (SIR 1.00; 95%CI 0.59-1.42), while pancreatic cancer (PC) showed a numerically higher SIR (1.98 overall; 2.96 ≥ 5 years postdiagnosis)."

Imprecise pancreatic-cancer estimate.

PMID:35807009 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"No strong association was found between pharmacological treatment and occurrence of PEI and DM."

Observational treatment comparisons do not show absence of any benefit.

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Pathophysiology

Neutrophil Extracellular Trap Formation

Extracellular neutrophil DNA structures occur in experimental and human type 1 AIP lesions. NET-containing cultures activate pDC-associated responses, but neither a universal human initiating antigen nor an obligatory temporal sequence has been established.

neutrophil CL:0000775

Downstream

Plasmacytoid Dendritic Cell Activation NET-containing preparations stimulate pDC responses in culture; translation to the initiating human lesion is inferred.

Show evidence (1 reference)

PMID:26297761 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"In addition, the inflamed pancreas of these patients but not controls also contained NETs that were shown to be capable of pDC activation."

NETs were observed in mouse and human lesions; the human initiating stimulus was not established.

Plasmacytoid Dendritic Cell Activation

Pancreatic pDC accumulation and activation accompany type 1 AIP. Human tissue and coculture findings complement preventive pDC-depletion experiments in induced murine pancreatitis.

plasmacytoid dendritic cell CL:0000784

Animal models

MRL/Mp with induced autoimmune pancreatitis Mouse Mouse partially recapitulates Depletion reduces pancreatic pDC-associated inflammation.

Downstream

Type I Interferon Production Activated patient pDCs produce IFN-alpha in the experimental coculture.

Show evidence (2 references)

PMID:26297761 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Consistent with these findings, we found that patients with IgG4-related AIP also exhibited pancreatic tissue localization of IFN-α-expressing pDCs and had significantly higher serum IFN-α levels than healthy controls."

Pancreatic localization and circulating IFN-alpha were human observations, not a human intervention.

PMID:26297761 SUPPORT INDIRECT PRIMARY RESULT Model Organism

"We found that the development of AIP in treated MRL/Mp mice occurred in parallel with pancreatic accumulation of pDCs producing IFN-α, and with pDC depletion and IFN-α-blocking studies, we showed that such accumulation was necessary for AIP induction."

pDC depletion and type-I-IFN receptor blockade preceded induction in MRL/Mp mice; this does not demonstrate reversal of established human fibrosis.

Type I Interferon Production

Activated pDC-associated IFN-alpha production is elevated in the examined human AIP specimens and cultures. Mouse and culture receptor-blockade studies concern IFN-alpha/beta signaling, rather than demonstrating an alpha-specific necessary mechanism in patients.

type I interferon production GO:0032606 ↑ INCREASED

Experimental models

Human NET, pDC and B-cell coculture PRIMARY CELL CULTURE Patient-pDC cultures show enhanced IFN-alpha output.

Animal models

MRL/Mp with induced autoimmune pancreatitis Mouse Mouse partially recapitulates IFNAR blockade attenuates inflammatory disease during induction.

Downstream

Increased IgG4 Secretion Type-I-IFN-dependent coculture signals contribute to IgG4 output. BAFF is also produced, but its necessity was not separately tested.

Pancreatic Lymphoplasmacytic Infiltration Preventive IFNAR blockade attenuates induced mouse pancreatitis; its relevance to sustained human type 1 inflammation is an extrapolation.

Show evidence (2 references)

PMID:26297761 SUPPORT DIRECT PRIMARY RESULT Human Clinical

Pancreatic localization and circulating IFN-alpha were human observations, not a human intervention.

PMID:26297761 SUPPORT INDIRECT PRIMARY RESULT In Vitro

"More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs."

Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.

Increased IgG4 Secretion

NET-containing patient-pDC/healthy-B-cell cultures produce increased IgG4. The experiment measures secretion and does not resolve class-switch recombination versus expansion of previously switched cells. Increased serum IgG4 is a useful but nonuniversal clinical correlate of type 1 disease.

Experimental models

Human NET, pDC and B-cell coculture PRIMARY CELL CULTURE NET-containing patient-pDC cultures increase IgG4 secretion, which falls with DNase or IFNAR blockade.

Show evidence (2 references)

PMID:26297761 SUPPORT INDIRECT PRIMARY RESULT In Vitro

"More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs."

Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.

url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf SUPPORT INDIRECT PRIMARY RESULT In Vitro

DNase and IFNAR blockade reduced IgG4 secretion in a defined human coculture; intervening signals remain unresolved.

Plasmablast Expansion

Circulating plasmablasts expand in active IgG4-related disease, including some patients with AIP and normal serum IgG4. Oligoclonality supports antigen-driven selection but does not identify the antigen or prove that plasmablasts initiate pancreatic injury.

plasmablast CL:0000980

Downstream

CD4+SLAMF7+ Cytotoxic T Lymphocyte Expansion B-lineage antigen presentation or growth factors may sustain these T cells. Rituximab-associated contraction is compatible with this hypothesis but does not establish the mediator.

Pancreatic Lymphoplasmacytic Infiltration The expanded B-lineage response plausibly contributes to the plasma-cell-rich lesion; migration and differentiation are not established by circulating counts alone.

Extrapancreatic Fibroinflammation The systemic B-lineage response may contribute to plasma-cell-rich lesions in other organs; blood counts alone do not establish trafficking or the responsible mediator.

Show evidence (2 references)

PMID:24817416 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"All 37 patients with active, untreated IgG4-RD had elevated plasmablast counts despite the fact that thirteen (36%) had normal serum IgG4 concentrations."

This selected active untreated IgG4-RD cohort included eight pancreatic cases; plasmablast expansion was not pancreas-specific.

PMID:30558726 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"The B-cell response is characterized by an oligoclonal expansion of plasmablasts, with dominant clones that vary among patients and distinct clones that emerge at the time of relapse."

The review summarizes oligoclonal plasmablast findings.

CD4+SLAMF7+ Cytotoxic T Lymphocyte Expansion

Expanded CD4+SLAMF7+ effector populations occur in IgG4-related disease. A later 18-person study identified selective expansion of the CD8alpha-negative subset, with pancreas involved in ten patients. Clonal overlap and contraction during treatment support disease association; they do not establish a pancreatic autoantigen or selective causal necessity.

CD4-positive SLAMF7-positive cytotoxic T lymphocyte CL:0000934

Downstream

CD4 T Cell Cytolytic Activity The isolated expanded population exhibits this function after experimental stimulation.

TGF-Beta1 Secretion by CD4 T Cells The isolated expanded population exhibits this function after experimental stimulation.

Interleukin-1-Beta Secretion by CD4 T Cells The isolated expanded population exhibits this function after experimental stimulation.

Show evidence (2 references)

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"CD4(+) effector/memory T cells with a cytolytic phenotype were expanded in patients with IgG4-RD."

Expansion was observed in systemic IgG4-RD; 18.8% of the 101-person cohort had pancreatic involvement.

PMID:29499100 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Clonally expanded CD8α- but not CD8αlow CD4+SLAMF7+ TEM cells decreased following glucocorticoid-induced disease remission."

The uncontrolled before/after association does not demonstrate that selective CTL depletion mediates remission.

CD4 T Cell Cytolytic Activity

Patient-derived expanded CD4+SLAMF7+ cells degranulate and kill allogeneic EBV-transformed B-cell targets under stimulation. This establishes cytolytic capacity in culture, not pancreatic-target specificity.

Experimental models

Patient-derived CD4 cytotoxic T-cell assays PRIMARY CELL CULTURE Expanded cells exhibit cytolytic function against allogeneic B-cell targets.

Downstream

Acinar Tissue Injury Cytolytic capacity may contribute to pancreatic injury, but the culture assay used B-cell targets and did not demonstrate pancreatic specificity.

Show evidence (1 reference)

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.

TGF-Beta1 Secretion by CD4 T Cells

Sorted patient-derived cytotoxic CD4 cells secrete TGF-beta1 after in-vitro activation, and relevant tissue lesions contain TGF-beta1-positive T cells. Direct necessity for pancreatic fibrosis has not been tested in this study.

Experimental models

Patient-derived CD4 cytotoxic T-cell assays PRIMARY CELL CULTURE Stimulated patient cells secrete TGF-beta1.

Downstream

Storiform Fibrosis The measured cytokine provides a plausible profibrotic contribution; no pancreatic fibrosis rescue or necessity experiment was performed in these patients.

Show evidence (1 reference)

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

"Upon in vitro stimulation, flow sorted CD4+ CTLs secreted large amounts of TGF-β1 compared to the naïve CD4+ cells from the same patients (Fig 5, E)."

TGF-beta1 secretion was measured after stimulation of sorted patient cells.

Interleukin-1-Beta Secretion by CD4 T Cells

Expanded patient-derived CD4 cells release processed IL-1beta after stimulation. This provides a candidate inflammatory signal, with its contribution to human pancreatic fibrosis inferred from broader fibrotic biology.

Experimental models

Patient-derived CD4 cytotoxic T-cell assays PRIMARY CELL CULTURE Stimulated expanded cells release processed IL-1beta.

Downstream

Storiform Fibrosis The measured cytokine provides a plausible profibrotic contribution; no pancreatic fibrosis rescue or necessity experiment was performed in these patients.

Show evidence (1 reference)

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

"The expanded CD4+ CTLs retained their SLAMF7 expression and cytotoxic markers and were found to secrete the processed form (17 kDa) of IL-1β upon re-stimulation with either anti-CD3 or LPS as determined by Western blot analysis of culture supernatants (Fig 5, D)."

Processed IL-1beta was measured in stimulated culture supernatants.

Pancreatic Lymphoplasmacytic Infiltration

Type 1 AIP contains a dense lymphocyte and plasma-cell infiltrate, often rich in IgG4-positive plasma cells. Tissue IgG4-positive cells alone are not disease-specific, and neither their abundance nor serum IgG4 proves that IgG4 is the sole damaging effector.

pancreas UBERON:0001264

Downstream

Storiform Fibrosis Chronic immune infiltration is associated with the characteristic fibrotic response; individual profibrotic mediators are incompletely resolved.

Obliterative Phlebitis The inflammatory lesion extends into venous walls and lumina, producing the characteristic phlebitis.

Acinar Tissue Injury Pancreatic inflammation is associated with parenchymal injury and atrophy.

Pancreatic Enlargement Inflammation and fibrosis contribute to the mass-like tissue lesion.

Pancreatic Duct Narrowing Periductal inflammation and fibrosis contribute to duct narrowing.

Pancreatic Islet Injury Inflammation and fibrosis can contribute to endocrine islet injury, with intermediate vascular and tissue effects inferred.

Show evidence (1 reference)

PMID:29512140 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

Clinical pathological synthesis of type 1 AIP.

Storiform Fibrosis

A patterned fibrotic reaction is characteristic of type 1 AIP. Cellular cytokine findings provide possible contributors, but human causal ordering and the relative roles of fibroblasts, immune cells and antibodies remain incompletely resolved.

pancreas UBERON:0001264

Animal models

MRL/Mp with induced autoimmune pancreatitis Mouse Mouse partially recapitulates The model develops pancreatic fibrosis, without establishing the specifically storiform architecture.

Downstream

Acinar Tissue Injury Fibrotic remodeling can accompany loss of pancreatic acini.

Pancreatic Enlargement Inflammation and fibrosis contribute to the mass-like tissue lesion.

Pancreatic Duct Narrowing Periductal inflammation and fibrosis contribute to duct narrowing.

Pancreatic Islet Injury Inflammation and fibrosis can contribute to endocrine islet injury, with intermediate vascular and tissue effects inferred.

Show evidence (1 reference)

PMID:29512140 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

Clinical pathological synthesis of type 1 AIP.

Obliterative Phlebitis

Inflammatory involvement and obliteration of small veins form a characteristic type 1 pathological lesion. This finding is evaluated alongside the infiltrate and fibrosis, rather than being a universal feature of every small biopsy.

pancreas UBERON:0001264

Show evidence (1 reference)

PMID:29512140 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

Clinical pathological synthesis of type 1 AIP.

Acinar Tissue Injury

Inflammatory injury and fibrotic remodeling damage the exocrine pancreatic parenchyma. Cytotoxic cells and tissue-binding antibodies are candidate contributors; their relative importance in patients is unresolved.

pancreas UBERON:0001264

Animal models

Neonatal male BALB/c recipients of human immunoglobulin Mouse Mouse partially recapitulates Patient immunoglobulin fractions induce pancreatic tissue injury in neonatal recipients.

MRL/Mp and MRL/Mp-Fas induced pancreatitis; NOD comparison models Mouse Mouse partially recapitulates C18 treatment reduces pancreatic injury and partially restores measured acinar calcium responses.

Downstream

Exocrine pancreatic insufficiency Loss or dysfunction of pancreatic exocrine tissue contributes to impaired digestion.

Weight loss Pancreatic disease can contribute to weight loss through several routes; malabsorption is not established in every symptomatic patient.

Show evidence (1 reference)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK560769/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Fibrosis may resemble chronic obstructive pancreatitis, characterized by interlobular and intralobular fibrosis and acinar atrophy."

Clinical review describes fibrosis and acinar loss.

Pancreatic Enlargement

Diffuse or focal inflammatory enlargement can create a mass-like pancreatic appearance in either established subtype. It is suggestive but cannot independently distinguish AIP from malignancy.

pancreas UBERON:0001264

Downstream

Pancreatic mass Inflammatory enlargement can produce the mass-like clinical imaging finding.

Show evidence (1 reference)

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"The classical imaging features of AIP are paren- chymal enlargement, ‘sausage-like’ shape, peripancre- atic edematous rim, and main pancreatic duct narrowing without upstream dilatation. These features may be diffuse or focal but can also be highly variable. (GRADE 2C; strong agreement)"

Guideline synthesis of variable pancreatic morphology.

Pancreatic Duct Narrowing

Inflammatory duct involvement produces irregular narrowing, often without marked upstream dilation at presentation. Later duct dilation or stones can occur in chronic disease.

pancreas UBERON:0001264

Show evidence (1 reference)

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

Guideline synthesis of variable pancreatic morphology.

Increased Ductal Interleukin-8 Expression

Type 2 AIP specimens show increased IL-8 expression in ductal epithelium and infiltrating cells compared with type 1. The relationship to neutrophil recruitment is biologically plausible but not proven necessary by these tissue observations.

Downstream

Neutrophilic Duct Infiltration IL-8 expression is consistent with recruitment of neutrophils, but necessity and temporal ordering were not tested.

Show evidence (1 reference)

PMID:28614208 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"In quantitative polymerase chain reaction for multiple cytokines using tissue-derived mRNA, the expression level of interleukin (IL)-8 was markedly higher in type 2 AIP than in type 1 AIP (P<0.001)."

Tissue-derived expression was compared between subtypes; this was not a chemotaxis or IL-8 blockade experiment.

Neutrophilic Duct Infiltration

In type 2 AIP, neutrophils infiltrate ductal epithelium and can extend into acinar tissue. Tissue sampling affects detection, and comparable nonspecific inflammatory changes must be distinguished from diagnostic granulocytic epithelial lesions.

neutrophil CL:0000775

Downstream

Duct Epithelial Injury Neutrophils within the epithelium are associated with local epithelial damage in the defining lesion.

Show evidence (1 reference)

PMID:34670874 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"The neutrophil-rich nature of inflammation discriminates type 2 from type 1 AIP.1,2,17 Characteristically, many neutrophils infiltrate the epithelial layer of the pancreatic ducts, a finding designated as GEL (Fig. 1C).2 Intraductal clusters of neutrophils resembling crypt abscesses in IBD often..."

Review description of the defining neutrophilic duct lesion.

Duct Epithelial Injury

Neutrophil-associated duct epithelial damage and destruction produce granulocytic epithelial lesions in type 2 AIP.

pancreas UBERON:0001264

Downstream

Pancreatic Duct Narrowing Duct-centric inflammation can contribute to the shared imaging abnormality.

Acinar Tissue Injury Duct-centric inflammation can extend into pancreatic parenchyma; the complete sequence is inferred.

Acute pancreatitis Type 2 duct-centric inflammatory injury can contribute to this clinical presentation; the individual intermediate sequence is not directly tested.

Recurrent acute pancreatitis Type 2 duct-centric inflammatory injury can contribute to this clinical presentation; the individual intermediate sequence is not directly tested.

Abdominal pain Type 2 duct-centric inflammatory injury can contribute to this clinical presentation; the individual intermediate sequence is not directly tested.

Show evidence (1 reference)

PMID:34670874 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

Review description of the defining neutrophilic duct lesion.

Extrapancreatic Fibroinflammation

Type 1 AIP may coexist with IgG4-related inflammatory lesions in bile ducts, salivary glands and other organs. These are manifestations of the systemic disorder, rather than obligatory downstream effects of pancreatic injury.

Downstream

IgG4-related sclerosing cholangitis Site-specific IgG4-related inflammation produces this associated manifestation.

IgG4-related sialadenitis Site-specific IgG4-related inflammation produces this associated manifestation.

Obstructive jaundice Associated biliary inflammation and obstruction can cause jaundice; pancreatic compression is an alternative route.

Retroperitoneal fibrosis Systemic fibroinflammatory disease can involve retroperitoneal tissue.

Show evidence (1 reference)

PMID:26672716 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"The organs most frequently involved are the pancreas (autoimmune pancreatitis (AIP), salivary and lacrimal glands (Mickulicz disease and sclerosing sialadenitis), biliary tree (sclerosing cholangitis or cholecystitis), retroperitoneum (retroperitoneal fibrosis), aorta (periaortic fibrosis),..."

Type 1 AIP participates in systemic IgG4-related organ inflammation.

Pancreatic Islet Injury

Inflammation, edema and fibrotic remodeling can impair or damage endocrine islets. Some AIP specimens have preserved islets, and diabetes can also predate AIP or be aggravated by glucocorticoids. Pancreatic endocrine dysfunction is therefore not inferred from acinar injury alone.

islet of Langerhans UBERON:0000006

Downstream

Diabetes mellitus Loss or dysfunction of islet cells can contribute to pancreatic diabetes; this does not account for every diabetic patient with AIP.

Show evidence (1 reference)

PMID:35807009 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Histological analysis revealed that islet cells of AIP patients were either intact or destroyed due to edema and ischemia because of fibrosis and lymphoplasmatic cell infiltration [25]."

The paper summarizes prior human histology; islet injury varies between patients.

⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

Digestive 7

Obstructive jaundice Biliary tract obstruction HP:0005230

Show evidence (1 reference)

PMID:32809604 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"The most common clinical presentation of type 1 AIP is painless jaundice with laboratory studies suggesting biliary obstruction and hyperglycemia."

Review describes the presentation without a source-specific numerator.

Acute pancreatitis FREQUENT HP:0001735

Show evidence (1 reference)

PMID:34670874 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"The majority of patients with type 2 AIP present with features of acute pancreatitis (60%) or painless jaundice (30%).6,7 Episodes of acute pancreatitis in patients with type 2 AIP are clinically mild without the need for intensive care unit admission, the development of organ failure, or..."

Subtype-specific review estimate.

Recurrent acute pancreatitis Recurrent pancreatitis HP:0100027

Show evidence (1 reference)

PMID:28365915 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Idiopathic duct-centric pancreatitis (IDCP) is a closely related but distinct disease that mimics AIP radiologically but manifests clinically most commonly as recurrent acute pancreatitis in young individuals with concurrent inflammatory bowel disease."

Clinical review supports recurrent presentation without a reliable pooled denominator.

Pancreatic mass HP:6000409

Show evidence (1 reference)

PMID:32809604 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Other cases present with abdominal pain or are discovered in asymptomatic individuals with a pancreatic mass, pancreatic duct stricturing, or an enlarged pancreas."

Review identifies mass-like and ductal presentations.

Exocrine pancreatic insufficiency HP:0001738

Show evidence (2 references)

url:https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Similarly, pancreatic exocrine insufficiency was observed in 409 of 2813 patients (14.5%) before treatment and increased to 476 (16.9%) after therapy (P = 0.014)."

Survey numerator and denominator; not a treatment-effect estimate.

PMID:35807009 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"PEI prevalence at diagnosis was 72.7% and was 63.5% at follow-up."

Specialist cohort with different testing ascertainment.

Retroperitoneal fibrosis OCCASIONAL HP:0005200

Show evidence (1 reference)

url:https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Table 1 Distribution of OOI observed in patients with AIP OOI other organ involvement, SD standard deviation a Among 2819 cases b Overlap observed in 177 cases c Overlap observed in 128 cases d OOI listed in this table e OOI defined in the JPS2018 criteria Type of OOI n (%)a IgG4-related..."

Organ-involvement table with assessed denominator.

Endocrine 1

Diabetes mellitus FREQUENT HP:0000819

Show evidence (1 reference)

url:https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Diabetes mellitus was present in 1250 of 2790 patients (44.8%) before initial GC therapy and increased signifi- cantly to 1428 (51.2%) after therapy (P < 0.001)."

Pre-treatment survey estimate.

Head and Neck 1

Constitutional 1

Abdominal pain HP:0002027

Show evidence (1 reference)

PMID:32809604 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Unlike patients with type 1 AIP, about half of those with type 2 AIP present with abdominal pain or acute pancreatitis."

The source groups two presentations, so no individual frequency is assigned.

Growth 1

Weight loss HP:0001824

Show evidence (1 reference)

PMID:36293522 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"In both cases, the clinical presentation is non-specific and is characterized by overlapping features with more sinister pathologies, such as pancreatic cancer, including jaundice, weight loss, and abdominal pain in some cases; for this reason, major efforts are required to find more specific..."

Clinical review lists overlapping presentations.

🧬

Genetic Associations

CTLA4 (Exploratory common-variant associations in 59 Japanese AIP cases and 102 controls; the +6230 comparison had nominal P=0.011 but corrected P=0.055. Small relapse-genotype analyses require independent replication.)

Gene: CTLA4 hgnc:2505 relationship_type: SUSCEPTIBILITY

Show evidence (2 references)

PMID:18341485 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Our findings suggest that AIP is associated with a genetic polymorphism in CTLA4 and is positively correlated with serum sCTLA4 levels."

Exploratory association statement; the full paper has corrected P=0.055 for the +6230 case-control comparison and does not show genotype-mediated soluble-protein elevation.

PMID:18341485 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The +49A/A and +6230A/A genotypes were associated with an enhanced risk of relapse (OR 5.45, P= 0.038 and OR 12.66, P= 0.022)."

Human association result; this study does not establish a causal pancreatic signaling mechanism.

HLA-DRB1 (HLA-DRB1 region and imputed amino-acid associations in a Japanese IgG4-related disease GWAS of 835 cases and 1,789 controls. The cohort was not restricted to pancreatic disease.)

Gene: HLA-DRB1 hgnc:4948 relationship_type: SUSCEPTIBILITY

Show evidence (2 references)

PMID:38229354 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"We identified the HLA-DRB1 (p=1·1×10-11) and FCGR2B (p=2·0×10-8) regions as susceptibility loci for IgG4-related disease."

Human association result; this study does not establish a causal pancreatic signaling mechanism.

PMID:38229354 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"We also identified crucial aminoacid residues in the β domain of the peptide-binding groove of HLA-DRB1, in which the seventh aminoacid residue showed the strongest association signal with IgG4-related disease"

Human association result; this study does not establish a causal pancreatic signaling mechanism.

FCGR2B (FCGR2B-region association in the same Japanese IgG4-related disease GWAS; associated expression and clinical correlates are not direct functional perturbation evidence.)

Gene: FCGR2B hgnc:3618 relationship_type: SUSCEPTIBILITY

Show evidence (2 references)

PMID:38229354 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"rs1340976 in FCGR2B showed an association with increased FCGR2B expression (p=2·7×10-10) and was in weak linkage disequilibrium with rs1050501, a missense variant of FCGR2B previously associated with systemic lupus erythematosus."

Human association result; this study does not establish a causal pancreatic signaling mechanism.

PMID:38229354 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Furthermore, rs1340976 was associated with the number of swollen organs at diagnosis (p=0.011) and IgG4 concentration at diagnosis (p=0.035)."

Human association result; this study does not establish a causal pancreatic signaling mechanism.

P2RX3 (Exploratory sequence-variant association in a small Japanese candidate-gene study of 27 cases and 30 controls.)

Gene: P2RX3 hgnc:8534 relationship_type: SUSCEPTIBILITY

Show evidence (2 references)

PMID:28955865 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Polymorphisms of CACNA1S (c.4642C>T), rs41554316, rs2231119, rs1042131, rs2838171, P2RX3 (c.195delG), rs75639061, SMAD7 (c.624delC) and TOP1 (c.2007delG), were identified as candidate genetic variants in patients with type 1 AIP."

Candidate sequence-variant association, not proof of a pathogenic molecular mechanism.

PMID:28955865 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"A total of 27 type 1 AIP patients and 30 healthy blood donors were recruited, and DNA samples were isolated from their mononuclear cells."

Small Japanese candidate-gene cohort.

TOP1 (Exploratory sequence-variant association in a small Japanese candidate-gene study of 27 cases and 30 controls.)

Gene: TOP1 hgnc:11986 relationship_type: SUSCEPTIBILITY

Show evidence (2 references)

PMID:28955865 SUPPORT DIRECT PRIMARY RESULT Human Clinical

Candidate sequence-variant association, not proof of a pathogenic molecular mechanism.

PMID:28955865 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"A total of 27 type 1 AIP patients and 30 healthy blood donors were recruited, and DNA samples were isolated from their mononuclear cells."

Small Japanese candidate-gene cohort.

FCRL3 (Exploratory FCRL3 promoter -110 A/A genotype association in 59 Japanese AIP cases, 62 chronic calcifying pancreatitis controls and 97 healthy controls. The A/A comparison with healthy controls was nominally significant, whereas the comparison with chronic pancreatitis was not.)

Gene: FCRL3 hgnc:18506 relationship_type: SUSCEPTIBILITY

Show evidence (3 references)

PMID:16905709 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The test group consisted of 59 patients with autoimmune pancreatitis, 62 patients with chronic calcifying pancrea- titis, and 97 unrelated Japanese controls."

Primary study denominator; the generated two-page PDF also contains unrelated adjacent letters, which are not used.

PMID:16905709 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"There are two possible explanations for these findings: FCRL32110 may be functionally linked with susceptibility to autoimmune pancreatitis, or this allele may be a linkage marker for a neighbouring unidentified susceptibility gene on chromo- some 1q 21. No other alleles were found to be..."

The authors distinguish direct functional susceptibility from linkage and do not perform a functional assay.

PMID:16905709 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Positivity for the 2110G allele was signifi- cantly decreased in autoimmune pancreatitis patients (p = 0.012, odds ratio 0.13; table 1), indicating a significant association of the 2110A/A genotype with autoimmune pan- creatitis. The frequency of 2110A/A alleles was significantly increased in..."

The reported susceptibility association concerns A/A genotype; Table 1 distinguishes this from the nonsignificant overall A-allele frequency and chronic-pancreatitis comparison.

💊

Medical Actions

Glucocorticoid induction for active type 1 disease

Action: Pharmacotherapy NCIT:C15986

Agent: glucocorticoid CHEBI:24261

Platform: Small molecule

Glucocorticoids are first-line induction for symptomatic active type 1 AIP and selected patients with persistent mass, cholestasis or threatened organ function. Assess clinical, biochemical and imaging response after two to four weeks and taper individually. Glucose control, infection risk and bone health require attention. Treating every asymptomatic patient solely to prevent later pancreatic insufficiency is not supported; nonresponse requires reassessment of the diagnosis.

Mechanism Target:

INHIBITS Pancreatic Lymphoplasmacytic Infiltration — Glucocorticoids suppress the active inflammatory lesion; the responsible cellular mediators are not resolved by clinical response.

Show evidence (1 reference)

PMID:28365915 SUPPORT INDIRECT REVIEW SYNTHESIS Human Clinical

"Initial treatment of both AIP and IDCP is with oral corticosteroids for duration of 4 weeks followed by a gradual taper."

Review supports corticosteroid induction in both established subtypes.

Show evidence (3 references)

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"There is no relevant data to support that a treatment should be proposed in patients with AIP without symptoms, just to limit the risk of exo- crine or endocrine insufﬁciencies. (GRADE 1C)"

GRADE 1C explicitly limits preventive treatment claims in asymptomatic disease.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Treatment with glucocorticoids should be initiated in a weight-based manner at a dose of 0.6–0.8 mg/kg body weight/day orally (typical starting dose 30–40 mg/day prednisone equivalent) for 1 month to induce remission. Response to initial treat- ment should be assessed at week 2–4 with clinical,..."

GRADE 1C adult induction and response-monitoring recommendation; the statement specifies a three-to-six-month taper in the main body.

PMID:28027896 SUPPORT DIRECT REVIEW SYNTHESIS Other

"CONCLUSION: The recommendations are based on the available evidence, and eastern and western experts' opinions to find standard treatment of AIP worldwide."

Canonical identity and consensus nature of the 2017 treatment guideline.

Glucocorticoids for symptomatic type 2 disease

Action: Pharmacotherapy NCIT:C15986

Agent: glucocorticoid CHEBI:24261

Platform: Small molecule

Type 2 AIP usually responds to a short induction course followed by taper. Many patients do not require maintenance because relapse is uncommon in published series; associated IBD treatment and recurrence require individual assessment. Spontaneous improvement has also been reported.

Mechanism Target:

INHIBITS Neutrophilic Duct Infiltration — Treatment reduces type 2 pancreatic inflammation; clinical response does not establish a specific neutrophil mediator.

Show evidence (1 reference)

PMID:34670874 SUPPORT INDIRECT REVIEW SYNTHESIS Human Clinical

"Type 2 AIP is a steroid-responsive disorder, and rapid improvements in symptoms and imaging abnormalities are expected within 2 or 3 weeks of the commencement of corticosteroids.6,7 Spontaneous regression without immunosuppression has also been documented. In contrast to type 1 AIP, in which..."

Review summarizes rapid response and lower relapse frequency.

Show evidence (1 reference)

PMID:34670874 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

Review summarizes rapid response and lower relapse frequency.

Selective maintenance and relapse treatment

Action: Pharmacotherapy NCIT:C15986

Platform: Other

Maintenance is selected according to relapse, organ involvement, response and toxicity, rather than being mandatory for every subtype. Re-induction with glucocorticoids may be appropriate. High-risk or relapsing type 1 disease may justify steroid-sparing therapy; optimal agent and duration are not established for every patient.

Show evidence (2 references)

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Adding immunosuppressive agents should be considered in case of disease relapse as main- tenance of remission strategy, and in patients with a high risk of disease relapse, particularly in the case of multi-organ involvement. If there is no change in dis- ease activity or the disease relapsed..."

GRADE 2C selective maintenance recommendation; lack of response also requires diagnostic reassessment.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Rituximab should be considered if patients are resistant or intol- erant to high-dose glucocorticoids to maintain remis- sion or have failed to respond to immunosuppressive therapies. Dosing protocol (375 mg/m 2 body surface area) is used weekly for 4 weeks, followed by infusions every 2–3..."

GRADE 2A conditional rituximab recommendation, distinct from a randomized type 1 AIP-specific efficacy estimate.

Azathioprine maintenance

Action: Pharmacotherapy NCIT:C15986

Agent: azathioprine CHEBI:2948

Platform: Small molecule

Azathioprine is used as a steroid-sparing maintenance option in selected relapsing type 1 disease. Evidence is principally observational and does not establish effective acute induction monotherapy or superiority over other agents. Myelosuppression, liver injury and drug-induced pancreatitis limit use.

Mechanism Target:

INHIBITS Pancreatic Lymphoplasmacytic Infiltration — Nonspecific immunosuppression supports maintenance of inflammatory remission.

Show evidence (1 reference)

PMID:36293522 SUPPORT INDIRECT REVIEW SYNTHESIS Other

"The efficacy of AZA and other immunomodulators depends on their ability to nonspecifically decrease B and T cell proliferation, which may be less effective than a therapeutic approach targeting Th2 cell response or regulatory T cell (Treg) activation [79]."

Proposed pharmacological route; no AIP-specific pathway assay.

Show evidence (2 references)

PMID:36293522 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Although there are no clinical trials on the use of AZA in AIP, its efficacy was investigated by Masaki et al. in a systematic review and meta-analysis; they found no AZA-treated patients naïve to corticosteroid treatment, but suggested the efficacy of AZA as maintenance therapy in patients with..."

Review summarizes limitations of the maintenance evidence.

PMID:36293522 SUPPORT DIRECT REVIEW SYNTHESIS Other

"It also examined which side effects occurred after AZA treatment; among them, pancreatitis, gastrointestinal symptoms, liver damage, severe leukopenia, and hair loss were the most common."

Reported toxicity in the reviewed literature.

Mycophenolate mofetil as a steroid-sparing option

Action: Pharmacotherapy NCIT:C15986

Agent: mycophenolate mofetil CHEBI:8764

Platform: Small molecule

Mycophenolate has been used in selected patients requiring maintenance or alternatives to other immunosuppression. Comparative AIP evidence is limited, and it is not an established superior first-line induction treatment.

Mechanism Target:

INHIBITS Pancreatic Lymphoplasmacytic Infiltration — Steroid-sparing immunosuppression can help maintain inflammatory control.

Show evidence (2 references)

PMID:36293522 SUPPORT INDIRECT REVIEW SYNTHESIS Other

"To avoid long-term side effects of glucocorticoid therapy, conventional glucocorticoid-sparing agents, including azathioprine, 6-mercaptopurine, mycophenolate mofetil, cyclosporine A, tacrolimus, methotrexate, cyclophosphamide, may be considered"

Review identifies the option and the limited comparative evidence.

PMID:36293522 SUPPORT INDIRECT REVIEW SYNTHESIS Other

"Available data supporting the use of one agent over another are limited, but the use of azathioprine (2–2.5 mg/kg body weight) is generally recommended."

Comparative maintenance evidence is limited.

Show evidence (2 references)

PMID:36293522 SUPPORT INDIRECT REVIEW SYNTHESIS Other

Review identifies the option and the limited comparative evidence.

PMID:36293522 SUPPORT INDIRECT REVIEW SYNTHESIS Other

"Available data supporting the use of one agent over another are limited, but the use of azathioprine (2–2.5 mg/kg body weight) is generally recommended."

Comparative maintenance evidence is limited.

Rituximab for relapsing or treatment-intolerant type 1 disease

Action: Pharmacotherapy NCIT:C15986

Agent: Rituximab NCIT:C1702

Platform: Monoclonal antibody

CD20-directed B-cell depletion is an option for resistant, relapsing or glucocorticoid-intolerant type 1 disease, or after failure of other immunosuppression. Most AIP-specific response estimates are from uncontrolled series. CD20-negative plasmablasts are not directly targeted; their decline is consistent with depletion of precursors. This is not a proven selective CTL therapy.

Mechanism Target:

INHIBITS Plasmablast Expansion — Plasmablast counts can fall after precursor B-cell depletion; the effect on CD20-negative cells is indirect.

Show evidence (1 reference)

PMID:24817416 SUPPORT INDIRECT PRIMARY RESULT Human Clinical

"The steep decline in plasmablast counts after anti-CD20 treatment likely stems from the depletion of CD20+ precursors."

Mechanistic interpretation of an uncontrolled treatment association.

Show evidence (2 references)

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

GRADE 2A conditional rituximab recommendation, distinct from a randomized type 1 AIP-specific efficacy estimate.

PMID:24817416 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"plasmablasts lack surface expression ofCD20 and are therefore resistant to direct depletion by anti-CD20 treatment approaches"

The authors distinguish mature B-cell depletion from indirect plasmablast effects.

Inebilizumab for adult IgG4-related disease

Action: Pharmacotherapy NCIT:C15986

Agent: Inebilizumab NCIT:C88283

Platform: Monoclonal antibody

The anti-CD19 antibody is approved in the United States for adult IgG4-related disease. In MITIGATE, 135 adults with active disease and a history of at least two involved organs received inebilizumab or placebo with the same eight-week glucocorticoid taper. Treated adjudicated flares occurred in 7/68 versus 40/67 over 52 weeks (hazard ratio 0.13, 95% CI 0.06–0.28). The trial was not a comparison with rituximab, did not establish pancreas-only efficacy, and does not apply to type 2 or checkpoint-inhibitor pancreatic injury. Serious adverse events occurred in 12 versus six participants and serious or opportunistic infections in six versus two. Screen for hepatitis B and tuberculosis, review vaccinations and immunoglobulins, and monitor infections and hypogammaglobulinemia according to the label.

Mechanism Target:

INHIBITS Plasmablast Expansion — CD19-directed depletion addresses a broader B-lineage compartment than CD20 targeting; clinical benefit does not identify a unique pathogenic B-cell function.

Show evidence (1 reference)

PMID:40745228 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Using CD19 as the therapeutic target addresses a broad spectrum of B cell differentiation including plasmablasts."

Review describes the differentiation-stage scope; primary trial supports clinical efficacy.

Show evidence (5 references)

PMID:39541094 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Treatment with inebilizumab reduced flare risk; 7 participants (10%) in the inebilizumab group had at least one flare, as compared with 40 participants (60%) in the placebo group (hazard ratio, 0.13; 95% confidence interval [CI], 0.06 to 0.28; P<0.001)."

Primary randomized result.

url:https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Journal_Club/2025/08_14.05.2025_N_Engl_J_Med_Stone_2025_Inebilizumab_for_Treatment_of_IgG4-Related_Disease_1168-77.pdf SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Serious adverse events occurred during the treatment pe- riod in 12 of the participants (18%) who received inebilizumab and 6 of the par - ticipants (9%) who received placebo."

Primary 52-week safety results.

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/761142s004lbl.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action The mechanism by which inebilizumab-cdon exerts its therapeutic effects in NMOSD, IgG4-RD, and gMG is presumed to involve binding to CD19, a cell surface antigen presents on pre-B and mature B lymphocytes. Following cell surface binding to B..."

Regulatory pharmacology describes CD19 binding and cytolysis.

+ 2 more references

Anti-TNF therapy in selected relapsing type 2 disease

Action: Pharmacotherapy NCIT:C15986

Agent: Infliximab NCIT:C1789 Adalimumab NCIT:C65216

Platform: Monoclonal antibody

Infliximab or adalimumab has been reported in a few relapsing or steroid-dependent type 2 cases, often with active IBD. This remains limited case-level evidence and does not establish routine use, a population response rate, or TNF as the proven driver of type 2 duct injury.

Mechanism Target:

INHIBITS Neutrophilic Duct Infiltration — Reported clinical remission is linked indirectly to reduction of the type 2 inflammatory lesion; a TNF-dependent duct mechanism was not tested.

Show evidence (1 reference)

PMID:36293522 SUPPORT INDIRECT REVIEW SYNTHESIS Human Clinical

"The same study also described three cases of patients with active IBD and recurrent AIP treated with anti-TNF therapy. Two patients were treated with adalimumab and one with infliximab. Pancreatic symptoms were controlled by induction treatment with anti-TNF therapy only, and no maintenance..."

Three cases with active IBD, in addition to an isolated case discussed in the source.

Show evidence (1 reference)

PMID:36293522 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

Three cases with active IBD, in addition to an isolated case discussed in the source.

Selective biliary drainage

Action: Biliary Stenting NCIT:C62741

Platform: Device

Biliary drainage can relieve clinically significant obstruction, help prevent infection and permit cytology or brushing when malignancy is a concern. Mild jaundice without infection may improve with glucocorticoids alone; stenting is not mandatory for every patient.

Mechanism Target:

BYPASSES Obstructive jaundice — Drainage relieves biliary obstruction while the underlying inflammatory disease is treated.

Show evidence (2 references)

url:https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Consensus statements /C15 “Biliary drainage is useful to prevent biliary infection and use of brushing and cytology can differentiate IgG4-SC from biliary malignancy."

International consensus level B recommendation.

"/C15 “In some cases of mild jaundice without signs of infection, ste- roid treatment alone can be performed safely without biliary stenting."

Consensus identifies a selected no-stent option.

Show evidence (2 references)

"Consensus statements /C15 “Biliary drainage is useful to prevent biliary infection and use of brushing and cytology can differentiate IgG4-SC from biliary malignancy."

International consensus level B recommendation.

"/C15 “In some cases of mild jaundice without signs of infection, ste- roid treatment alone can be performed safely without biliary stenting."

Consensus identifies a selected no-stent option.

Diabetes management during pancreatic treatment

Action: Supportive Care NCIT:C15747

Platform: Other

Assess and optimize glucose control before induction and during follow-up. Glucocorticoids can improve pancreatitis-associated dysfunction in some patients while causing or worsening hyperglycemia in others; pancreatic diabetes and pre-existing metabolic diabetes require individualized management.

Mechanism Target:

MODULATES Diabetes mellitus — Individualized diabetes care addresses hyperglycemia; it is not evidence that all pancreatic endocrine injury is reversible.

Show evidence (2 references)

"Description The Japanese clinical guidelines recommend biliary drainage with biopsy or cytology in patients with obstructive jaundice, and control of blood glucose levels in patients with diabetes mellitus before steroid induction therapy [13]."

Consensus recommends glucose control before steroid induction.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"However, there is a subset of patients exhibiting diabe- tes mellitus before AIP type 1 onset (33%) and a subset of patients developing or exacerbating diabetes mellitus as a complication of glucocorticoid treatment."

Guideline identifies glucocorticoid-associated worsening.

Show evidence (2 references)

Consensus recommends glucose control before steroid induction.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

Guideline identifies glucocorticoid-associated worsening.

Long-term pancreatic and systemic follow-up

Category: Monitoring

Platform: Other

Follow type 1 disease for pancreatic or extrapancreatic relapse, exocrine and endocrine dysfunction, nutrition, bone health and treatment toxicity. Lifelong follow-up is advised by the European guideline, with frequency individualized to disease and treatment. Conflicting cancer-risk cohorts do not establish a proven AIP-specific cancer-imaging interval.

Show evidence (3 references)

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Life-long follow-up of patients with AIP type 1 is advisable. (GRADE 2C; strong agreement)"

GRADE 2C lifelong follow-up recommendation.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Screening for a deﬁciency of fat- soluble vitamins (A, D, E, and K), zinc, calcium, and magnesium should be considered in line with UEG evidence-based guidelines for the diagnosis and therapy of chronic pancreatitis (HaPanEU). 54 (GRADE 2A; strong agreement)"

GRADE 2A nutritional screening guidance refers to chronic-pancreatitis recommendations.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"However, these data might be inﬂu- enced by a bias due to a more careful surveillance of patients with IgG4-related disease or AIP. Thus, future prospective studies are required to analyse the inci- dence of cancer in patients with IgG4-related disease compared to age-, sex-, and risk..."

The guideline explicitly qualifies the observational cancer-risk evidence.

Surgery for selected unresolved lesions or complications

Action: Surgical Procedure NCIT:C15329

Platform: Surgery

Pancreatic surgery is not routine treatment for a medically responsive inflammatory lesion. It may be considered for persistent diagnostic uncertainty about malignancy or selected refractory complications after multidisciplinary assessment; resection carries pancreatic functional consequences.

Show evidence (2 references)

"Although medical treatment should be more preferable to surgical intervention, surgical intervention may be an option in cases of poor response to medical treatment, in which long-term biliary stenting is necessary due to continuous obstructive jaundice."

Pancreas-specific consensus discussion of refractory obstruction.

PMID:39169289 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"8917 pancreatic resections were performed because of a clinical suspicion of pancreatic cancer. AIP accounted for 140 cases (1.6%)."

Selected surgical series illustrate the cancer-mimic problem, not a general misdiagnosis rate.

Pancreatic enzyme replacement for exocrine insufficiency

Action: Pharmacotherapy NCIT:C15986

Agent: Pancrelipase NCIT:C29345

Platform: Protein replacement

Use pancreatic enzyme replacement when exocrine insufficiency is established, with administration during meals and adjustment to meal content, symptoms and nutritional response. This supplements digestion and does not treat the pancreatic immune lesion. The AGA advice is general EPI guidance, not an AIP-specific randomized efficacy estimate. A response to empiric enzymes alone is not a reliable diagnostic test.

Mechanism Target:

BYPASSES Exocrine pancreatic insufficiency — Exogenous enzymes compensate for inadequate delivery of pancreatic digestive enzymes.

Show evidence (2 references)

PMID:37737818 SUPPORT DIRECT REVIEW SYNTHESIS Other

"BEST PRACTICE ADVICE 10: Once EPI is diagnosed, treatment with pancreatic enzyme replacement therapy (PERT) is required. If EPI is left untreated, it will result in complications related to fat malabsorption and malnutrition, having a negative impact on quality of life."

Expert best-practice advice for established EPI.

url:https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"PERT treats the meal, not the pancreas. Thus, it must be taken during the meal to maximize mixing and digestion of nutrients.72,73 Humans have other mechanisms for protein and carbohydrate digestion, but not fats, 1 so the focus of PERT is on lipase dose and meal fat content."

The full guideline explains replacement at the digestive level.

Show evidence (2 references)

PMID:37737818 SUPPORT DIRECT REVIEW SYNTHESIS Other

Expert best-practice advice for established EPI.

url:https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

The full guideline explains replacement at the digestive level.

Nutrition and deficiency management

Action: Dietary Intervention NCIT:C15447

Platform: Behavioral / lifestyle

For patients with exocrine insufficiency, assess weight, muscle status and fat-soluble vitamins, provide dietitian-guided support and replace documented or expected deficiencies. Avoid unnecessarily severe fat restriction. Monitor bone health and treatment toxicity according to the individual risk profile; this is supportive EPI care rather than proof that AIP inflammation has remitted.

Mechanism Target:

MODULATES Weight loss — Nutritional support addresses inadequate intake or maldigestion-associated weight loss.

Show evidence (1 reference)

url:https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"1,66 This includes a dietary assessment from a certi ﬁed dietitian, if available, to determine nutri- tional needs and speci ﬁcd eﬁcits (eg, vitamins A, D, E, K, and B12, selenium, unintentional weight loss, protein balance, and caloric needs) plus dietary adjustments based on needs and..."

General EPI dietary assessment explicitly includes unintentional weight loss and caloric needs.

Show evidence (2 references)

PMID:37737818 SUPPORT DIRECT REVIEW SYNTHESIS Other

"BEST PRACTICE ADVICE 13: Routine supplementation and monitoring of fat-soluble vitamin levels are appropriate. Dietary modifications include a low-moderate fat diet with frequent smaller meals and avoiding very-low-fat diets."

General EPI nutrition advice.

url:https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Once EPI is diagnosed, a multidisciplinary evaluation is helpful to establish the state of the patient ’s digestive and endocrine systems."

Full guideline describes nutritional and endocrine assessment.

🌍

Environmental Factors

Occupational history involving industrial dusts, vapors, gases and fumes

The 101 cases were compared with 303 age-, sex- and hospital-matched digestive-disease controls. Selection, recall, correlated exposures and residual confounding limit causal interpretation. Composite matrix estimates cannot be assigned specifically to asbestos. No antigenic or cellular mediator, prevention effect or type 2 association was measured; no mechanistic target is inferred.

Blue-collar work and job-exposure-matrix estimates were associated with IgG4-related cholangitis and/or type 1 AIP in a Dutch hospital-based case-control study. The exposure classification was derived from recalled work history rather than measured personal toxin concentrations. It does not establish a specific occupational cause of AIP.

Show evidence (1 reference)

PMID:34816110 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Of cases with IgG4-RD, 68% (n = 69) ever performed a blue-collar job, compared to 39% of controls (n = 117, Fig. 2), corresponding to an OR of 3.66 (95% CI 2.18–6.13)."

Occupational-history association in 101 combined biliary/pancreatic IgG4-RD cases and 303 matched tertiary disease controls, not a pancreas-only or type 2 analysis.

🔬

Biochemical Markers

Circulating plasmablasts (Increased)

Context: Research biomarker measured in 37 selected active untreated systemic IgG4-RD cases, including eight with pancreatic involvement, versus 14 healthy and 21 disease controls. Thirteen of 36 with available serum IgG4 had normal values. These data do not validate a pancreatic-cancer differential test or a universal relapse predictor.

Pathograph Readouts

Readout Of Plasmablast Expansion Positive

Circulating cell counts directly measure the expanded plasmablast compartment; they do not establish pancreatic trafficking or clinical diagnostic specificity.

Show evidence (2 references)

PMID:24817416 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The IgG4-RD patients had substantially elevated total plasmablast counts (median 4698/mL, range 610-79524/mL) compared to both untreated disease controls (median 592/mL, range 19-4294/mL; p < 0.001) and healthy controls (median 94/mL, range 1-653/mL; p < 0.001)."

Selected systemic IgG4-related disease cohort with assay-specific denominators.

PMID:24817416 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Among IgG4-RD patients, thirteen (36%) had normal serum IgG4 concentrations"

Selected systemic IgG4-related disease cohort with assay-specific denominators.

Serum IgG4 (Often increased in type 1; may be normal)

Context: An adjunct to integrated diagnosis. Elevated values occur in other conditions, and type 2 generally has normal or mildly elevated IgG4. The 43% sensitivity reported in a surgical meta-analysis came from 21/49 tested resected type 1 cases and must not be used as general diagnostic sensitivity.

Show evidence (2 references)

PMID:34670874 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"In contrast to type 1 AIP, which is a pancreatic manifestation of IgG4-related disease, serum IgG4 concentrations are normal or only mildly elevated in type 2 AIP.5 Serum IgG4 elevations >300 mg/dL (or >2-fold higher than the normal range) are highly suggestive of type 1 AIP.6-8 Since the ratio..."

Subtype-specific serological distinction.

PMID:39169289 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The sensitivity of IgG4 levels in type 1 AIP was low (43%, 21/49 patients)."

Highly selected resected cohort with incomplete testing.

Candidate autoantibodies against galectin-3 and prohibitin 1 (Detected in subsets of IgG4-related cholangitis)

Context: In a 52-person IgG4-related cholangitis cohort, antibodies to galectin-3 and prohibitin 1 were also seen in some comparator groups. This is not a germline genetic finding or an AIP-specific diagnostic assay. Cholangiocyte perturbation and antibody experiments did not establish a consistent bile-acid-injury mechanism.

Show evidence (2 references)

PMID:38332916 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"RESULTS: Anti-galectin-3 autoantibodies were detected in 13.5% of individuals with IRC but not in PSC."

Cholangitis cohort, not an AIP-only series.

PMID:38332916 SUPPORT DIRECT PRIMARY RESULT In Vitro

"Gene-specific knockdown, pharmacological inhibition, and recombinant protein substitution did not clearly disclose a protective role of these autoantigens in human cholangiocytes against toxic bile acids."

The functional findings do not establish the proposed protective mechanism.

🔬

Diagnosis

Comprehensive type 1 AIP assessment and exclusion of malignancy

Assess pancreatic morphology, histology, serum IgG4, other-organ involvement and carefully interpreted treatment response together. Neither serum IgG4 nor CA19-9 alone establishes AIP or excludes pancreatic cancer. A focal mass requires an appropriate malignancy work-up; steroid response is one contextual criterion, not independent proof of benign disease. This guideline addresses type 1 AIP unless stated otherwise.

Show evidence (4 references)

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"For these guidelines, AIP is referring to AIP type 1, i.e. IgG4-related autoimmune pancreatitis, unless speciﬁed otherwise."

Defines the type 1 scope of this guideline.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"IgG4 serum level alone lacks sensitivity and speciﬁcity, but can be helpful to estab- lish the diagnosis, and therefore should be measured if IgG4-related gastrointestinal disease is suspected. (GRADE 2C; strong agreement)"

GRADE 2C recommendation: IgG4 is an adjunct, not a stand-alone diagnostic test.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"There are no speciﬁc clinical features or blood tests that can differentiate between IgG4-related disease and cancer. (GRADE 2B; strong agreement)"

Clinical or laboratory findings alone cannot distinguish IgG4 disease from cancer; interpret within the full work-up.

+ 1 more reference

Pancreatic imaging and endoscopic tissue acquisition

CT or MRI can identify diffuse or focal enlargement, a peripancreatic rim and duct narrowing, but imaging may overlap with malignancy. EUS supplies detailed imaging and tissue acquisition. Core histology helps assess architectural features and distinguish focal AIP from cancer; sampling error limits a negative biopsy, and IgG4-positive cells alone are insufficient. The pediatric exception to routine pretreatment biopsy is not generalized to adult masses.

Show evidence (3 references)

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

GRADE 2C describes suggestive, variable imaging features.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Endoscopic ultrasound (EUS) provides pancreatic imaging ﬁndings suggestive of AIP and is used for obtaining tissue samples for the histo- logical diagnosis of the disease. (GRADE 2B; strong agreement)"

GRADE 2B supports EUS for imaging and histological sampling.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"In biopsy specimens, distinguishing IgG4-related disease and cancer is more challenging. Risk of sampling error should be considered in a neg- ative biopsy. Non-speciﬁc inﬂammation, with increased IgG4-positive cells can occur in both cancer and IgG4- related disease. (GRADE 2C; strong agreement)"

Sampling error and nonspecific IgG4 infiltration limit biopsy interpretation.

Histological subtype assessment

Assess the distribution of inflammation, storiform fibrosis, obliterative phlebitis and IgG4-positive plasma cells for type 1. For type 2, assess granulocytic epithelial lesions, with scant IgG4-positive cells and the clinical IBD context. Peritumoral or ordinary acute pancreatitis can also contain neutrophils, so a few cells do not independently establish type 2. Some IBD-associated cases meet probable criteria without diagnostic histology; this does not apply to every patient with a steroid-responsive mass.

Histopathologic Examination NCIT:C18190

Show evidence (3 references)

PMID:29512140 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

Clinical pathological synthesis of type 1 AIP.

PMID:34670874 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"In contrast to type 1 AIP, the diagnosis of which may be established without biopsy, type 2 AIP generally requires the tissue confirmation of neutrophilic infiltration into the ducts or acini.15 Without histology, type 2 AIP cannot be diagnosed in patients without history of IBD, even if they..."

Histology and IBD jointly determine the diagnostic pathway.

PMID:34670874 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Another caveat is that neutrophilic infiltration in the duct epithelium or lobules can be focally detected in peritumoral pancreatitis."

Nonspecific or peritumoral neutrophils limit interpretation.

CA19-9 and serum IgG4 as adjuncts

Neither marker independently distinguishes AIP from pancreatic ductal adenocarcinoma. Interpret CA19-9 with cholestasis, imaging and tissue findings; use IgG4 as one component of the diagnostic framework. A meta-analysis of resected suspected cancers found IgG4 positivity in 21/49 tested type 1 cases, a highly selected subgroup rather than a general sensitivity estimate.

Show evidence (2 references)

PMID:39169289 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The sensitivity of IgG4 levels in type 1 AIP was low (43%, 21/49 patients)."

The denominator is tested, resected cases.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Statement 8.2.1: There are no speciﬁc clinical features or blood tests that can differentiate between IgG4-related disease and cancer."

Guideline emphasizes overlap with cancer.

Contextual assessment of glucocorticoid response

An appropriately supervised response assessment may contribute to a composite diagnosis after a malignancy work-up. Improvement is not independent proof that a lesion is benign; steroid treatment can obscure histology and some peritumoral inflammation also responds. Persistent or recurrent nonresponse warrants diagnostic reassessment.

Show evidence (1 reference)

PMID:34670874 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"However, a steroid trial needs to be considered with caution because various conditions, including peritumoral pancreatitis, potentially respond to immunosuppression. Pancreatic biopsy needs to be considered before a steroid trial, which veils pathognomonic histological changes."

Response has diagnostic limitations.

Pancreatic exocrine and endocrine function assessment

Assess glucose control and symptoms or laboratory evidence of exocrine insufficiency at diagnosis and follow-up. Fecal elastase is a practical initial exocrine test, interpreted with stool consistency and the clinical context. These functional tests assess complications and do not distinguish AIP from cancer.

Show evidence (2 references)

PMID:37737818 SUPPORT DIRECT REVIEW SYNTHESIS Other

"BEST PRACTICE ADVICE 4: Fecal elastase test is the most appropriate initial test and must be performed on a semi-solid or solid stool specimen."

General PEI expert advice, applicable to established pancreatic dysfunction rather than an AIP-specific diagnostic validation.

url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Life-long follow-up of patients with AIP type 1 is advisable. (GRADE 2C; strong agreement)"

GRADE 2C lifelong follow-up recommendation.

📈

Progression

Relapse of type 1 disease

Type 1

Relapse can occur in the pancreas, other IgG4-related organs, or both. The 2021 Japanese hospital survey estimated cumulative relapse of 12.5% at three years, 20.7% at five and 36.0% at ten. A separate 83-person corticosteroid-treated cohort selected for at least ten years of observation or death estimated 56.9% at ten years. Different selection, treatment and follow-up preclude pooling these rates or treating either as a universal prognosis. Corticosteroid discontinuation and IgG4 normalization were observational correlates, not randomized evidence for lifelong treatment or a deterministic biomarker rule.

Show evidence (3 references)

PMID:42154026 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Kaplan-Meier analysis demonstrated a cumulative relapse incidence of 12.5%, 20.7%, 36.0%, 44.0%, 53.3%, and 68.9% at 3, 5, 10, 15, 20, and 25 years, respectively."

Survey-specific relapse estimates.

PMID:42185503 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"RESULTS: Cumulative relapse rates at 1, 3, 5, 7, and 10 years were 11.0%, 26.9%, 38.3%, 50.0%, and 56.9%."

Selected long-follow-up cohort.

PMID:42185503 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"CS discontinuation independently predicted relapse, whereas serum IgG4 normal at diagnosis or normalized after CS was protective."

Retrospective associations do not establish treatment causation.

Relapse of type 2 disease

Type 2

Relapse is less common in published type 2 series, and maintenance is unnecessary in many patients. Limited cohorts and histological ascertainment leave long-term estimates uncertain; probable diagnoses associated with IBD do not invariably require a diagnostic pancreatic biopsy.

Show evidence (1 reference)

PMID:34670874 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"In contrast to type 1 AIP, in which relapse is relatively common (30% to 50%), disease relapse is uncommon in type 2 AIP (10%);6,7 therefore, maintenance therapy is unnecessary in most patients."

Review summarizes a roughly 10% relapse estimate from selected series, without establishing lifetime risk.

Pancreatic functional impairment

Exocrine insufficiency and diabetes may already be present at diagnosis and can persist or develop later. In one 59-person type 1 cohort, exocrine testing was available in 44 at baseline and 52 at follow-up; 32 and 33, respectively, had insufficiency. These changing denominators do not establish a treatment response. The 2021 survey found diabetes in 1,250/2,790 and exocrine insufficiency in 409/2,813 before initial glucocorticoids, illustrating substantial ascertainment differences between studies. Treatment effects cannot be separated reliably from disease severity and duration in these observational comparisons.

Show evidence (2 references)

PMID:35807009 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"PEI prevalence at diagnosis was 72.7% and was 63.5% at follow-up."

The source abstract reports percentages; full Table 1 supplies the differing denominators.

url:https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Diabetes mellitus was present in 1250 of 2790 patients (44.8%) before initial GC therapy and increased signifi- cantly to 1428 (51.2%) after therapy (P < 0.001). Similarly, pancreatic exocrine insufficiency was observed in 409 of 2813 patients (14.5%) before treatment and increased to 476..."

Contemporary survey reports measured denominators before and after therapy.

Long-term survival and complications

Type 1

Long-term follow-up includes nutritional status, diabetes, pancreatic function and treatment toxicity. In a selected 83-person cohort, ten-year survival was 85.5%. Overall malignancy incidence was not elevated against the reference population; the two pancreatic cancers yielded imprecise estimates compatible with no increase. An association between steroid maintenance and survival cannot establish a causal survival benefit. Serum albumin change is a nonspecific nutritional marker, not a direct measure of pancreatic exocrine function.

Show evidence (2 references)

PMID:42185503 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Ten-year survival was 85.5%, and CS maintenance was associated with better OS."

Selected retrospective cohort; not a randomized maintenance comparison.

PMID:42185503 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Overall malignancy risk was not increased (SIR 1.00; 95%CI 0.59-1.42), while pancreatic cancer (PC) showed a numerically higher SIR (1.98 overall; 2.96 ≥ 5 years postdiagnosis)."

The numerically higher pancreatic-cancer estimate is not proof of an excess risk.

📊

Prevalence

Worldwide

Unknown Rare

Qualitative rarity statement; worldwide prevalence and the relative ascertainment of the two subtypes remain uncertain.

Show evidence (1 reference)

PMID:32809604 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Autoimmune pancreatitis (AIP), also referred to as nonalcoholic destructive pancreatitis and sclerosing pancreatitis, is a rare condition characterized histologically by chronic inflammation of the pancreas"

Qualitative rarity statement without a worldwide population estimate.

Japan, 2007 nationwide two-stage survey

Point Prevalence 2.2 per 100,000 1–9 per 100,000

Hospital-based nationwide survey estimate under the diagnostic criteria in use during the stated year. Changes in recognition, ascertainment and criteria limit causal interpretation of comparisons across surveys.

Show evidence (1 reference)

PMID:22466167 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The estimated total number of AIP patients in 2007 was 2790 (95% confidence interval, 2540-3040), with an overall prevalence rate of 2.2 per 100,000 populations."

Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.

Japan, 2007 nationwide two-stage survey

Annual Incidence 0.9 per 100,000 per year 1–9 per 1,000,000 per year

Show evidence (1 reference)

PMID:22466167 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The number of patients, who were newly diagnosed as AIP, was estimated to be 1120 (95% confidence interval, 1000-1240), with an annual incidence rate of 0.9 per 100,000 populations."

Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.

Japan, 2011 nationwide two-stage survey

Point Prevalence 4.6 per 100,000 1–9 per 100,000

Show evidence (1 reference)

PMID:25815647 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The estimated total number of AIP patients in 2011 was 5745 (95% confidence interval, 5325-6164), with an overall prevalence rate of 4.6 per 100,000 population."

Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.

Japan, 2016 nationwide two-stage survey

Point Prevalence 10.1 per 100,000 1–9 per 10,000

Show evidence (2 references)

PMID:31872350 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The estimated number of AIP patients in 2016 was 13,436, with an overall prevalence rate of 10.1 per 100,000 persons."

Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.

PMID:31872350 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Compared to the 2011 survey, both numbers more than doubled."

Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.

Japan, 2016 nationwide two-stage survey

Annual Incidence 3.1 per 100,000 per year 1–9 per 100,000 per year

Show evidence (1 reference)

PMID:31872350 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The estimated number of newly diagnosed patients was 3984, with an annual incidence rate of 3.1 per 100,000 persons."

Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.

Japan, 2021 nationwide two-stage survey

Point Prevalence 13.3 per 100,000 1–9 per 10,000

The hospital questionnaire survey estimated 16,750 patients and 4,210 newly diagnosed patients using the Japanese 2018 criteria, which principally identify type 1 AIP. The first-stage response was 877/2,398 departments. These estimates do not establish a worldwide rate or a biological increase independent of ascertainment.

Show evidence (1 reference)

PMID:42154026 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The estimated number of patients with AIP in 2021 was 16,750 (prevalence, 13.3 per 100,000 persons), representing a 25% increase from 2016. The number of newly diagnosed cases was 4210 (annual incidence, 3.4 per 100,000 persons)."

The contemporary survey reports prevalence and annual incidence separately.

Japan, 2021 nationwide two-stage survey

Annual Incidence 3.4 per 100,000 per year 1–9 per 100,000 per year

Show evidence (1 reference)

PMID:42154026 SUPPORT DIRECT PRIMARY RESULT Human Clinical

The contemporary survey reports prevalence and annual incidence separately.

🔬

Clinical Trials

NCT04540497 PHASE_III ACTIVE_NOT_RECRUITING

MITIGATE: phase 3 randomized, double-blind inebilizumab versus placebo in 135 adults with active IgG4-related disease, with matched glucocorticoid taper. The 52-week randomized comparison has been published; the registry remains active, not recruiting for extended follow-up. The population had multiorgan disease history and was not an AIP-only cohort.

Show evidence (2 references)

clinicaltrials:NCT04540497 SUPPORT DIRECT BACKGROUND Other

"This study aims to evaluate the efficacy and safety of inebilizumab for the prevention of flare of Immunoglobulin G4-related disease (IgG4-RD)."

The registration record establishing the trial's identity and objective. Graded OTHER because a registry entry is a registration document rather than study evidence.

PMID:39541094 SUPPORT DIRECT PRIMARY RESULT Human Clinical

Published primary result is distinct from registry status.

🧫

Experimental Models

Human NET, pDC and B-cell coculture PRIMARY_CELL_CULTURE

Defined cultures compare patient and control cell sources and use induced NET-containing preparations. Patient pDCs promote IFN-alpha and IgG4 output; DNase and IFNAR blockade reduce output. The human study enrolled 20 patients, but tissue, serum and culture subsets differ. Tissue controls included tumor-free cancer-resection sections. The experiments do not prove that MSU or patient anti-lactoferrin IgG4 initiates disease, and no BAFF-neutralization experiment isolates that mediator.

Cell source

Patient or control blood pDCs and neutrophils combined with healthy-control B cells

Publication

url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf

Pathograph links

Type I Interferon Production partially recapitulates fidelity: moderate observes: molecular Patient-pDC cultures show enhanced IFN-alpha output.

Limitations: The B cells are healthy-control cells; extracellular DNA and receptor-blockade effects do not identify a universal human initiating antigen.

Readouts

Culture IFN-alpha

Direction: INCREASED

Interpretation: Patient-pDC cultures show enhanced IFN-alpha output.

Show evidence (1 reference)

PMID:26297761 SUPPORT INDIRECT PRIMARY RESULT In Vitro

"More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs."

Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.

Show evidence (1 reference)

PMID:26297761 SUPPORT INDIRECT PRIMARY RESULT In Vitro

"More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs."

Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.

Increased IgG4 Secretion partially recapitulates fidelity: moderate observes: molecular NET-containing patient-pDC cultures increase IgG4 secretion, which falls with DNase or IFNAR blockade.

Limitations: Secretion cannot distinguish de novo class switching from expansion of a pre-existing IgG4 B-cell subset. BAFF necessity is untested.

Readouts

Culture IgG4 secretion

Direction: INCREASED

Interpretation: NET-containing patient-pDC cultures increase IgG4 secretion, which falls with DNase or IFNAR blockade.

Show evidence (2 references)

PMID:26297761 SUPPORT INDIRECT PRIMARY RESULT In Vitro

"More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs."

Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.

+ 1 more reference

Show evidence (2 references)

PMID:26297761 SUPPORT INDIRECT PRIMARY RESULT In Vitro

"More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs."

Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.

+ 1 more reference

Show evidence (2 references)

PMID:26297761 SUPPORT INDIRECT PRIMARY RESULT In Vitro

"More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs."

Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.

url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf SUPPORT INDIRECT PRIMARY RESULT In Vitro

DNase and IFNAR blockade reduced IgG4 secretion in a defined human coculture; intervening signals remain unresolved.

Patient-derived CD4 cytotoxic T-cell assays PRIMARY_CELL_CULTURE

Expanded patient cells degranulate and kill allogeneic EBV-transformed B-cell targets after stimulation, and secrete processed IL-1beta and TGF-beta1. The overall clinical cohort had 101 IgG4-RD patients, with 18.8% pancreatic involvement; individual culture assays use smaller subsets. No pancreatic epithelial-target killing, selective pathway rescue or fibroblast-collagen assay establishes a complete human pancreatic fibrosis sequence.

Cell source

Sorted and expanded blood CD4-positive SLAMF7-positive cells from systemic IgG4-related disease patients

Publication

PMID:26971690

Pathograph links

CD4 T Cell Cytolytic Activity partially recapitulates fidelity: moderate observes: cellular Expanded cells exhibit cytolytic function against allogeneic B-cell targets.

Limitations: Target-cell and stimulation context differ from a pancreatic lesion; antigen specificity and pancreatic necessity remain unresolved.

Readouts

Target-cell killing

Direction: INCREASED

Interpretation: Expanded cells exhibit cytolytic function against allogeneic B-cell targets.

Show evidence (1 reference)

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.

Show evidence (1 reference)

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.

TGF-Beta1 Secretion by CD4 T Cells partially recapitulates fidelity: moderate observes: molecular Stimulated patient cells secrete TGF-beta1.

Limitations: Cytokine output is measured; pancreatic fibrosis mediation is not.

Readouts

Supernatant TGF-beta1

Direction: INCREASED

Interpretation: Stimulated patient cells secrete TGF-beta1.

Show evidence (1 reference)

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

"Upon in vitro stimulation, flow sorted CD4+ CTLs secreted large amounts of TGF-β1 compared to the naïve CD4+ cells from the same patients (Fig 5, E)."

TGF-beta1 secretion was measured after stimulation of sorted patient cells.

Show evidence (1 reference)

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

"Upon in vitro stimulation, flow sorted CD4+ CTLs secreted large amounts of TGF-β1 compared to the naïve CD4+ cells from the same patients (Fig 5, E)."

TGF-beta1 secretion was measured after stimulation of sorted patient cells.

Interleukin-1-Beta Secretion by CD4 T Cells partially recapitulates fidelity: moderate observes: molecular Stimulated expanded cells release processed IL-1beta.

Limitations: The processed cytokine was detected in culture; selective in-vivo necessity is untested.

Readouts

Processed IL-1beta in supernatant

Direction: INCREASED

Interpretation: Stimulated expanded cells release processed IL-1beta.

Show evidence (1 reference)

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

Processed IL-1beta was measured in stimulated culture supernatants.

Show evidence (1 reference)

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

Processed IL-1beta was measured in stimulated culture supernatants.

Show evidence (3 references)

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

"Upon in vitro stimulation, flow sorted CD4+ CTLs secreted large amounts of TGF-β1 compared to the naïve CD4+ cells from the same patients (Fig 5, E)."

TGF-beta1 secretion was measured after stimulation of sorted patient cells.

PMID:26971690 SUPPORT DIRECT PRIMARY RESULT In Vitro

Processed IL-1beta was measured in stimulated culture supernatants.

H69 cholangiocyte autoantigen perturbation CELL_LINE

Parallel galectin-3 and prohibitin perturbations measured intracellular pH, bile-acid permeation and apoptosis. Results were discordant across interventions and did not establish a consistent protective autoantigen mechanism. The final IgG comparison used one IgG4-related cholangitis donor and one healthy donor and did not increase bile-acid uptake. This is a biliary epithelial experiment, not a pancreatic model or a germline variant assay.

Cell source

Human H69 cholangiocytes with gene knockdown, inhibitors, recombinant proteins or donor immunoglobulin

Publication

PMID:38332916

Show evidence (2 references)

PMID:38332916 SUPPORT DIRECT PRIMARY RESULT In Vitro

"These parallel approaches did not demonstrate clear-cut protective effects in three assays that touch on the functionality of the biliary bicarbonate umbrella (23, 24), including intracellular pH measurements, toxic bile acid permeation studies, and experiments determining GCDC-induced..."

The paper limits its own functional interpretation.

PMID:38332916 SUPPORT DIRECT PRIMARY RESULT In Vitro

"In line with these findings, pretreatment with IgGs isolated from an IRC patient with anti-galectin-3 and anti-prohibitin 1 autoantibodies did not lead to increased GCDC permeation into cholangiocytes."

One patient-donor antibody preparation did not increase toxic bile-acid entry.

🐁

Animal Models

MRL/Mp with induced autoimmune pancreatitis Mouse

The induced model develops pancreatic infiltrates, acinar architectural damage and fibrosis. Depletion of pDCs or IFNAR blockade before induction exposures reduces inflammatory pathology. A later study reported increased SLAMF7-positive CD8 cells and dexamethasone-associated improvement; these are mouse CD8 cells, not the human CD4 population. The model does not reproduce endogenous human IgG4 production, and reported fibrosis is not necessarily the diagnostic storiform pattern.

Species

Mouse

Genotype

MRL/Mp with induced autoimmune pancreatitis

Pathograph links

Plasmacytoid Dendritic Cell Activation partially recapitulates fidelity: moderate observes: cellular Depletion reduces pancreatic pDC-associated inflammation.

Limitations: Disease is induced by a synthetic innate stimulus in an autoimmune-prone strain. Preventive depletion/blockade does not identify the initiating human antigen or establish treatment of established human disease. Mice lack endogenous IgG4; shared inflammatory findings remain informative, but human IgG4 production is not reproduced.

Readouts

Pancreatic inflammation after pDC depletion

Direction: DECREASED

Interpretation: Depletion reduces pancreatic pDC-associated inflammation.

Show evidence (1 reference)

url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf SUPPORT DIRECT PRIMARY RESULT Model Organism

"In addition, such depletion of pDCs prevented AIP development as assessed by pathological analysis (Fig. 2B) and reductions in the numbers of inﬁltrating T cells, B cells, and CD11b + macrophages in the pancreas (Fig. 2C)."

Preventive pDC depletion reduced experimental pancreatic inflammatory pathology.

Show evidence (1 reference)

url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf SUPPORT DIRECT PRIMARY RESULT Model Organism

Preventive pDC depletion reduced experimental pancreatic inflammatory pathology.

Type I Interferon Production partially recapitulates fidelity: moderate observes: cellular IFNAR blockade attenuates inflammatory disease during induction.

Readouts

Pancreatic pathology with IFNAR blockade

Direction: DECREASED

Interpretation: IFNAR blockade attenuates inflammatory disease during induction.

Show evidence (1 reference)

url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf SUPPORT DIRECT PRIMARY RESULT Model Organism

"We found that such treatment of MRL/Mp mice inhibited AIP development to about the same extent as pDC depletion (Fig. 3A) and coincided with the fact that the number of pDCs in the pan- creas was also signiﬁcantly reduced, indicating that type I IFN production is involved in the pancreatic..."

Type-I-IFN receptor blockade attenuated disease during induction; it was not a treatment trial after established fibrosis.

Show evidence (1 reference)

url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf SUPPORT DIRECT PRIMARY RESULT Model Organism

Type-I-IFN receptor blockade attenuated disease during induction; it was not a treatment trial after established fibrosis.

Storiform Fibrosis partially recapitulates fidelity: low observes: tissue The model develops pancreatic fibrosis, without establishing the specifically storiform architecture.

Readouts

Pancreatic fibrosis

Direction: INCREASED

Interpretation: The model develops pancreatic fibrosis, without establishing the specifically storiform architecture.

Show evidence (1 reference)

PMID:29512140 SUPPORT DIRECT REVIEW SYNTHESIS Model Organism

"Although mice lack the IgG4 Ab subtype, autoimmune-prone MRL/Mp mice treated with repeated injection with polyinosinic-polycytidylic acid (poly (I:C)) provide an experimental model of AIP. These mice exhibit massive destruction of pancreatic architecture associated with pancreatic immune cell..."

Protocol synthesis describes the model and the absent mouse IgG4 subclass.

Show evidence (1 reference)

PMID:29512140 SUPPORT DIRECT REVIEW SYNTHESIS Model Organism

Protocol synthesis describes the model and the absent mouse IgG4 subclass.

Show evidence (4 references)

PMID:29512140 SUPPORT DIRECT REVIEW SYNTHESIS Model Organism

Protocol synthesis describes the model and the absent mouse IgG4 subclass.

url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf SUPPORT DIRECT PRIMARY RESULT Model Organism

Preventive pDC depletion reduced experimental pancreatic inflammatory pathology.

url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf SUPPORT DIRECT PRIMARY RESULT Model Organism

Type-I-IFN receptor blockade attenuated disease during induction; it was not a treatment trial after established fibrosis.

+ 1 more reference

Neonatal male BALB/c recipients of human immunoglobulin Mouse

Passive transfer of patient IgG caused pancreatic and salivary injury. Both IgG1 and IgG4 fractions caused injury, with greater destruction from IgG1; simultaneous IgG4 reduced IgG1-associated injury. This published experiment replaces the former proposal that subclass-resolved testing had not been done. The accessible abstract does not establish a universal human mechanism, identify every antigen, or show that selective IgG4 removal would be beneficial.

Species

Mouse

Genotype

Neonatal male BALB/c recipients of human immunoglobulin

Pathograph links

Acinar Tissue Injury partially recapitulates fidelity: moderate observes: tissue Patient immunoglobulin fractions induce pancreatic tissue injury in neonatal recipients.

Limitations: Passive transfer bypasses immune initiation and does not reproduce the chronic human systemic syndrome. The full methods were not retrievable; no unsupported dose, denominator or mechanistic mediator is inferred.

Readouts

Pancreatic injury after patient immunoglobulin

Direction: INCREASED

Interpretation: Patient immunoglobulin fractions induce pancreatic tissue injury in neonatal recipients.

Show evidence (1 reference)

PMID:26964842 SUPPORT DIRECT PRIMARY RESULT Model Organism

Human IgG passive transfer into neonatal mice; abstract-supported scope.

Show evidence (1 reference)

PMID:26964842 SUPPORT DIRECT PRIMARY RESULT Model Organism

Human IgG passive transfer into neonatal mice; abstract-supported scope.

Show evidence (1 reference)

PMID:26964842 SUPPORT DIRECT PRIMARY RESULT Model Organism

Human IgG passive transfer into neonatal mice; abstract-supported scope.

MRL/Mp and MRL/Mp-Fas induced pancreatitis; NOD comparison models Mouse

CFTR corrector C18 reduced pancreatic inflammatory injury in MRL/Mp mice and partially restored calcium influx in isolated pancreatic acini. Responses varied in the more severe MRL/Mp-Fas model. Broader salivary-gland experiments used VX770 and ductal CFTR gene transfer; the gene-transfer rescue was salivary, not pancreatic. These results nominate a preclinical duct-function strategy, not established AIP treatment.

Species

Mouse

Genotype

MRL/Mp and MRL/Mp-Fas induced pancreatitis; NOD comparison models

Pathograph links

Acinar Tissue Injury partially recapitulates fidelity: moderate observes: tissue C18 treatment reduces pancreatic injury and partially restores measured acinar calcium responses.

Limitations: Small mouse experiments, variable strain responses and post-treatment isolated-cell assays. No human AIP trial or pancreatic gene-transfer rescue was performed; accelerated CFTR degradation was proposed rather than directly measured.

Readouts

Pancreatic injury after C18

Direction: DECREASED

Interpretation: C18 treatment reduces pancreatic injury and partially restores measured acinar calcium responses.

Show evidence (1 reference)

PMID:28634110 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Figure 4e shows that treatment with C18 reduced the pancreatic damage and infiltration of T cells and neutrophils in MRL/Mp mice."

C18 effect in the MRL/Mp pancreatic experiment.

Show evidence (1 reference)

PMID:28634110 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Figure 4e shows that treatment with C18 reduced the pancreatic damage and infiltration of T cells and neutrophils in MRL/Mp mice."

C18 effect in the MRL/Mp pancreatic experiment.

Show evidence (2 references)

PMID:28634110 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Figure 4e shows that treatment with C18 reduced the pancreatic damage and infiltration of T cells and neutrophils in MRL/Mp mice."

C18 effect in the MRL/Mp pancreatic experiment.

PMID:28634110 SUPPORT DIRECT PRIMARY RESULT In Vitro

"Significantly, treatment with C18 partially restored Ca2+ influx in NOD and MRL/Mp acinar cells (Figure 6d) and Ca2+ oscillations in NOD pancreatic acini (Fig."

Restoration was measured in isolated pancreatic acini after mouse treatment.

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Source YAML

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name: Autoimmune Pancreatitis
creation_date: '2026-09-06T08:15:00Z'
category: Complex
classifications:
  harrisons_chapter:
  - classification_value: GASTROINTESTINAL
    notes: Pancreatic inflammation and pancreaticobiliary dysfunction define the clinical presentation.
    evidence:
    - reference: PMID:32809604
      reference_title: Autoimmune Pancreatitis.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Autoimmune pancreatitis (AIP), also referred to as nonalcoholic destructive pancreatitis and sclerosing pancreatitis, is a rare condition characterized histologically by chronic inflammation of the pancreas and clinically by various symptoms related to biliary and pancreatic pathologies.
      explanation: Pancreatic inflammation and pancreaticobiliary dysfunction define the clinical presentation.
      quote_role: REVIEW_SYNTHESIS
      directness: DIRECT
  - classification_value: IMMUNE_RHEUMATOLOGIC
    notes: Type 1 AIP is part of systemic IgG4-related fibroinflammatory disease.
    evidence:
    - reference: PMID:32809604
      reference_title: Autoimmune Pancreatitis.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: AIP can be a primary pancreatic disorder or a systemic autoimmune disease associated with other autoimmune conditions, such as immunoglobulin G subclass 4 (IgG4)-related diseases.
      explanation: Type 1 AIP is part of systemic IgG4-related fibroinflammatory disease.
      quote_role: REVIEW_SYNTHESIS
      directness: DIRECT
disease_term:
  preferred_term: autoimmune pancreatitis
  term:
    id: MONDO:0015175
    label: autoimmune pancreatitis
synonyms:
- AIP
- sclerosing pancreatitis
- nonalcoholic destructive pancreatitis
description: Autoimmune pancreatitis is an immune-mediated fibroinflammatory pancreatic disorder with two established subtypes. Type 1 is the pancreatic manifestation of IgG4-related disease, with lymphoplasmacytic infiltration, storiform fibrosis and obliterative phlebitis. Type 2 is characterized by neutrophilic duct epithelial injury and granulocytic epithelial lesions and is associated with inflammatory bowel disease. Both can cause pancreatic enlargement, duct abnormalities, obstructive jaundice or acute pancreatitis and often respond to glucocorticoids. Diagnosis requires integration of imaging, serology, histology and clinical context because pancreatic malignancy can resemble AIP. Immune-checkpoint-inhibitor-associated pancreatic injury is a related drug-induced condition; its proposed designation as type 3 AIP remains provisional.
parents:
- Pancreatitis
- Immune-Mediated Inflammatory Disease
has_subtypes:
- name: Type 1
  display_name: Type 1 (lymphoplasmacytic sclerosing pancreatitis, IgG4-related)
  subtype_term:
    preferred_term: autoimmune pancreatitis type 1
    term:
      id: MONDO:0017227
      label: autoimmune pancreatitis type 1
  description: IgG4-related lymphoplasmacytic sclerosing pancreatitis, usually presenting in older adults. Characteristic tissue findings include IgG4-rich lymphoplasmacytic infiltration, storiform fibrosis and obliterative phlebitis. Serum IgG4 may be elevated but is neither universally abnormal nor independently diagnostic. Other IgG4-related organs can be involved, and relapse is more common than in type 2.
  evidence:
  - reference: PMID:29512140
    reference_title: Autoimmune Pancreatitis Mouse Model.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Type 1 AIP (also called LPSP) is characterized by dense lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis. This is accompanied by massive accumulation of IgG4-expressing plasma cells and, in some patients with elevated levels of serum IgG4 and involvement of other organs, including bile ducts, salivary glands, and kidney.
    explanation: Review synthesis of type 1 histology and systemic involvement.
- name: Type 2
  display_name: Type 2 (idiopathic duct-centric pancreatitis, IDCP)
  subtype_term:
    preferred_term: autoimmune pancreatitis type 2
    term:
      id: MONDO:0017228
      label: autoimmune pancreatitis type 2
  description: Idiopathic duct-centric pancreatitis with granulocytic epithelial lesions and few or no IgG4-positive plasma cells. It more often presents with acute pancreatitis in younger patients and can accompany inflammatory bowel disease, particularly ulcerative colitis. It is not the pancreatic manifestation of systemic IgG4-related disease; rare extrapancreatic granulocytic epithelial lesions have been reported.
  evidence:
  - reference: PMID:34670874
    reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Type 2 AIP is unrelated to IgG4 and is a completely distinct entity from type 1 AIP. One confusing factor is that the two types of AIP share patterns of clinical presentation (e.g., acute pancreatitis and painless jaundice) and imaging abnormalities (e.g., diffuse or segmental enlargement). Since there are currently no established serum markers, the diagnosis of type 2 AIP is highly challenging and requires the tissue confirmation of neutrophilic injury to the pancreatic ducts, a finding designated as a granulocytic epithelial lesion.
    explanation: Type 2 is a distinct histological and clinical entity.
prevalence:
- population: Worldwide
  measure_type: UNKNOWN
  prevalence_class: RARE
  notes: Qualitative rarity statement; worldwide prevalence and the relative ascertainment of the two subtypes remain uncertain.
  evidence:
  - reference: PMID:32809604
    reference_title: Autoimmune Pancreatitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Autoimmune pancreatitis (AIP), also referred to as nonalcoholic destructive pancreatitis and sclerosing pancreatitis, is a rare condition characterized histologically by chronic inflammation of the pancreas
    explanation: Qualitative rarity statement without a worldwide population estimate.
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- population: Japan, 2007 nationwide two-stage survey
  measure_type: POINT_PREVALENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 2.2
  rate_denominator: POPULATION
  notes: Hospital-based nationwide survey estimate under the diagnostic criteria in use during the stated year. Changes in recognition, ascertainment and criteria limit causal interpretation of comparisons across surveys.
  evidence:
  - reference: PMID:22466167
    reference_title: Nationwide epidemiological survey of autoimmune pancreatitis in Japan.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The estimated total number of AIP patients in 2007 was 2790 (95% confidence interval, 2540-3040), with an overall prevalence rate of 2.2 per 100,000 populations.
    explanation: Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- population: Japan, 2007 nationwide two-stage survey
  measure_type: ANNUAL_INCIDENCE
  prevalence_class: BAND_1_9_PER_1000000
  rate_per_100000: 0.9
  rate_denominator: POPULATION_PER_YEAR
  notes: Hospital-based nationwide survey estimate under the diagnostic criteria in use during the stated year. Changes in recognition, ascertainment and criteria limit causal interpretation of comparisons across surveys.
  evidence:
  - reference: PMID:22466167
    reference_title: Nationwide epidemiological survey of autoimmune pancreatitis in Japan.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The number of patients, who were newly diagnosed as AIP, was estimated to be 1120 (95% confidence interval, 1000-1240), with an annual incidence rate of 0.9 per 100,000 populations.
    explanation: Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- population: Japan, 2011 nationwide two-stage survey
  measure_type: POINT_PREVALENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 4.6
  rate_denominator: POPULATION
  notes: Hospital-based nationwide survey estimate under the diagnostic criteria in use during the stated year. Changes in recognition, ascertainment and criteria limit causal interpretation of comparisons across surveys.
  evidence:
  - reference: PMID:25815647
    reference_title: Nationwide epidemiological survey of autoimmune pancreatitis in Japan in 2011.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The estimated total number of AIP patients in 2011 was 5745 (95% confidence interval, 5325-6164), with an overall prevalence rate of 4.6 per 100,000 population.
    explanation: Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- population: Japan, 2016 nationwide two-stage survey
  measure_type: POINT_PREVALENCE
  prevalence_class: BAND_1_5_PER_10000
  rate_per_100000: 10.1
  rate_denominator: POPULATION
  notes: Hospital-based nationwide survey estimate under the diagnostic criteria in use during the stated year. Changes in recognition, ascertainment and criteria limit causal interpretation of comparisons across surveys.
  evidence:
  - reference: PMID:31872350
    reference_title: Nationwide epidemiological survey of autoimmune pancreatitis in Japan in 2016.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The estimated number of AIP patients in 2016 was 13,436, with an overall prevalence rate of 10.1 per 100,000 persons.
    explanation: Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:31872350
    reference_title: Nationwide epidemiological survey of autoimmune pancreatitis in Japan in 2016.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Compared to the 2011 survey, both numbers more than doubled.
    explanation: Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- population: Japan, 2016 nationwide two-stage survey
  measure_type: ANNUAL_INCIDENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 3.1
  rate_denominator: POPULATION_PER_YEAR
  notes: Hospital-based nationwide survey estimate under the diagnostic criteria in use during the stated year. Changes in recognition, ascertainment and criteria limit causal interpretation of comparisons across surveys.
  evidence:
  - reference: PMID:31872350
    reference_title: Nationwide epidemiological survey of autoimmune pancreatitis in Japan in 2016.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The estimated number of newly diagnosed patients was 3984, with an annual incidence rate of 3.1 per 100,000 persons.
    explanation: Source-specific population estimate; the survey year and measure distinguish prevalence from incidence.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- population: Japan, 2021 nationwide two-stage survey
  measure_type: POINT_PREVALENCE
  prevalence_class: BAND_1_5_PER_10000
  rate_per_100000: 13.3
  rate_denominator: POPULATION
  notes: The hospital questionnaire survey estimated 16,750 patients and 4,210 newly diagnosed patients using the Japanese 2018 criteria, which principally identify type 1 AIP. The first-stage response was 877/2,398 departments. These estimates do not establish a worldwide rate or a biological increase independent of ascertainment.
  evidence:
  - reference: PMID:42154026
    reference_title: Nationwide epidemiological survey of autoimmune pancreatitis in Japan in 2021.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: The estimated number of patients with AIP in 2021 was 16,750 (prevalence, 13.3 per 100,000 persons), representing a 25% increase from 2016. The number of newly diagnosed cases was 4210 (annual incidence, 3.4 per 100,000 persons).
    explanation: The contemporary survey reports prevalence and annual incidence separately.
- population: Japan, 2021 nationwide two-stage survey
  measure_type: ANNUAL_INCIDENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 3.4
  rate_denominator: POPULATION_PER_YEAR
  notes: The hospital questionnaire survey estimated 16,750 patients and 4,210 newly diagnosed patients using the Japanese 2018 criteria, which principally identify type 1 AIP. The first-stage response was 877/2,398 departments. These estimates do not establish a worldwide rate or a biological increase independent of ascertainment.
  evidence:
  - reference: PMID:42154026
    reference_title: Nationwide epidemiological survey of autoimmune pancreatitis in Japan in 2021.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: The estimated number of patients with AIP in 2021 was 16,750 (prevalence, 13.3 per 100,000 persons), representing a 25% increase from 2016. The number of newly diagnosed cases was 4210 (annual incidence, 3.4 per 100,000 persons).
    explanation: The contemporary survey reports prevalence and annual incidence separately.
progression:
- phase: Relapse of type 1 disease
  subtype: Type 1
  notes: Relapse can occur in the pancreas, other IgG4-related organs, or both. The 2021 Japanese hospital survey estimated cumulative relapse of 12.5% at three years, 20.7% at five and 36.0% at ten. A separate 83-person corticosteroid-treated cohort selected for at least ten years of observation or death estimated 56.9% at ten years. Different selection, treatment and follow-up preclude pooling these rates or treating either as a universal prognosis. Corticosteroid discontinuation and IgG4 normalization were observational correlates, not randomized evidence for lifelong treatment or a deterministic biomarker rule.
  evidence:
  - reference: PMID:42154026
    reference_title: Nationwide epidemiological survey of autoimmune pancreatitis in Japan in 2021.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Kaplan-Meier analysis demonstrated a cumulative relapse incidence of 12.5%, 20.7%, 36.0%, 44.0%, 53.3%, and 68.9% at 3, 5, 10, 15, 20, and 25 years, respectively.
    explanation: Survey-specific relapse estimates.
  - reference: PMID:42185503
    reference_title: 'A decade of clinical course and prognostic determinants in type 1 autoimmune pancreatitis: insights from a 10-year longitudinal multicenter retrospective study.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: 'RESULTS: Cumulative relapse rates at 1, 3, 5, 7, and 10 years were 11.0%, 26.9%, 38.3%, 50.0%, and 56.9%.'
    explanation: Selected long-follow-up cohort.
  - reference: PMID:42185503
    reference_title: 'A decade of clinical course and prognostic determinants in type 1 autoimmune pancreatitis: insights from a 10-year longitudinal multicenter retrospective study.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: CS discontinuation independently predicted relapse, whereas serum IgG4 normal at diagnosis or normalized after CS was protective.
    explanation: Retrospective associations do not establish treatment causation.
- phase: Relapse of type 2 disease
  subtype: Type 2
  notes: Relapse is less common in published type 2 series, and maintenance is unnecessary in many patients. Limited cohorts and histological ascertainment leave long-term estimates uncertain; probable diagnoses associated with IBD do not invariably require a diagnostic pancreatic biopsy.
  evidence:
  - reference: PMID:34670874
    reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: In contrast to type 1 AIP, in which relapse is relatively common (30% to 50%), disease relapse is uncommon in type 2 AIP (10%);6,7 therefore, maintenance therapy is unnecessary in most patients.
    explanation: Review summarizes a roughly 10% relapse estimate from selected series, without establishing lifetime risk.
- phase: Pancreatic functional impairment
  notes: Exocrine insufficiency and diabetes may already be present at diagnosis and can persist or develop later. In one 59-person type 1 cohort, exocrine testing was available in 44 at baseline and 52 at follow-up; 32 and 33, respectively, had insufficiency. These changing denominators do not establish a treatment response. The 2021 survey found diabetes in 1,250/2,790 and exocrine insufficiency in 409/2,813 before initial glucocorticoids, illustrating substantial ascertainment differences between studies. Treatment effects cannot be separated reliably from disease severity and duration in these observational comparisons.
  evidence:
  - reference: PMID:35807009
    reference_title: 'Exocrine and Endocrine Insufficiency in Autoimmune Pancreatitis: A Matter of Treatment or Time?'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: PEI prevalence at diagnosis was 72.7% and was 63.5% at follow-up.
    explanation: The source abstract reports percentages; full Table 1 supplies the differing denominators.
  - reference: url:https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    reference_title: https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Diabetes mellitus was present in 1250 of 2790 patients (44.8%) before initial GC therapy and increased signifi- cantly to 1428 (51.2%) after therapy (P < 0.001). Similarly, pancreatic exocrine insufficiency was observed in 409 of 2813 patients (14.5%) before treatment and increased to 476 (16.9%) after therapy (P = 0.014).
    explanation: Contemporary survey reports measured denominators before and after therapy.
- phase: Long-term survival and complications
  subtype: Type 1
  notes: Long-term follow-up includes nutritional status, diabetes, pancreatic function and treatment toxicity. In a selected 83-person cohort, ten-year survival was 85.5%. Overall malignancy incidence was not elevated against the reference population; the two pancreatic cancers yielded imprecise estimates compatible with no increase. An association between steroid maintenance and survival cannot establish a causal survival benefit. Serum albumin change is a nonspecific nutritional marker, not a direct measure of pancreatic exocrine function.
  evidence:
  - reference: PMID:42185503
    reference_title: 'A decade of clinical course and prognostic determinants in type 1 autoimmune pancreatitis: insights from a 10-year longitudinal multicenter retrospective study.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Ten-year survival was 85.5%, and CS maintenance was associated with better OS.
    explanation: Selected retrospective cohort; not a randomized maintenance comparison.
  - reference: PMID:42185503
    reference_title: 'A decade of clinical course and prognostic determinants in type 1 autoimmune pancreatitis: insights from a 10-year longitudinal multicenter retrospective study.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Overall malignancy risk was not increased (SIR 1.00; 95%CI 0.59-1.42), while pancreatic cancer (PC) showed a numerically higher SIR (1.98 overall; 2.96 ≥ 5 years postdiagnosis).
    explanation: The numerically higher pancreatic-cancer estimate is not proof of an excess risk.
pathophysiology:
- name: Neutrophil Extracellular Trap Formation
  biological_scale: CELLULAR
  description: Extracellular neutrophil DNA structures occur in experimental and human type 1 AIP lesions. NET-containing cultures activate pDC-associated responses, but neither a universal human initiating antigen nor an obligatory temporal sequence has been established.
  evidence:
  - reference: PMID:26297761
    reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: In addition, the inflamed pancreas of these patients but not controls also contained NETs that were shown to be capable of pDC activation.
    explanation: NETs were observed in mouse and human lesions; the human initiating stimulus was not established.
  cell_types:
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  downstream:
  - target: Plasmacytoid Dendritic Cell Activation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: NET-containing preparations stimulate pDC responses in culture; translation to the initiating human lesion is inferred.
    evidence:
    - reference: PMID:26297761
      reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs.
      explanation: Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.
- name: Plasmacytoid Dendritic Cell Activation
  biological_scale: CELLULAR
  description: Pancreatic pDC accumulation and activation accompany type 1 AIP. Human tissue and coculture findings complement preventive pDC-depletion experiments in induced murine pancreatitis.
  evidence:
  - reference: PMID:26297761
    reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Consistent with these findings, we found that patients with IgG4-related AIP also exhibited pancreatic tissue localization of IFN-α-expressing pDCs and had significantly higher serum IFN-α levels than healthy controls.
    explanation: Pancreatic localization and circulating IFN-alpha were human observations, not a human intervention.
  - reference: PMID:26297761
    reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    snippet: We found that the development of AIP in treated MRL/Mp mice occurred in parallel with pancreatic accumulation of pDCs producing IFN-α, and with pDC depletion and IFN-α-blocking studies, we showed that such accumulation was necessary for AIP induction.
    explanation: pDC depletion and type-I-IFN receptor blockade preceded induction in MRL/Mp mice; this does not demonstrate reversal of established human fibrosis.
  cell_types:
  - preferred_term: plasmacytoid dendritic cell
    term:
      id: CL:0000784
      label: plasmacytoid dendritic cell
  downstream:
  - target: Type I Interferon Production
    causal_link_type: DIRECT
    description: Activated patient pDCs produce IFN-alpha in the experimental coculture.
    evidence:
    - reference: PMID:26297761
      reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs.
      explanation: Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.
- name: Type I Interferon Production
  biological_scale: MOLECULAR
  description: Activated pDC-associated IFN-alpha production is elevated in the examined human AIP specimens and cultures. Mouse and culture receptor-blockade studies concern IFN-alpha/beta signaling, rather than demonstrating an alpha-specific necessary mechanism in patients.
  evidence:
  - reference: PMID:26297761
    reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Consistent with these findings, we found that patients with IgG4-related AIP also exhibited pancreatic tissue localization of IFN-α-expressing pDCs and had significantly higher serum IFN-α levels than healthy controls.
    explanation: Pancreatic localization and circulating IFN-alpha were human observations, not a human intervention.
  - reference: PMID:26297761
    reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs.
    explanation: Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.
  biological_processes:
  - preferred_term: type I interferon production
    term:
      id: GO:0032606
      label: type I interferon production
    modifier: INCREASED
  downstream:
  - target: Increased IgG4 Secretion
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Type-I-IFN-dependent coculture signals contribute to IgG4 output. BAFF is also produced, but its necessity was not separately tested.
    evidence:
    - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
      reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: In addition, inhibition of NET formation by DNase or blockade of IFN- a–mediated signaling pathways by anti-IFNAR Ab signiﬁcantly reduced IgG4 production in a coculture system comprised of control B cells, patient-derived neutrophils, and patient-derived pDCs (Fig. 7C).
      explanation: DNase and IFNAR blockade reduced IgG4 secretion in a defined human coculture; intervening signals remain unresolved.
  - target: Pancreatic Lymphoplasmacytic Infiltration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Preventive IFNAR blockade attenuates induced mouse pancreatitis; its relevance to sustained human type 1 inflammation is an extrapolation.
    evidence:
    - reference: PMID:26297761
      reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      snippet: We found that the development of AIP in treated MRL/Mp mice occurred in parallel with pancreatic accumulation of pDCs producing IFN-α, and with pDC depletion and IFN-α-blocking studies, we showed that such accumulation was necessary for AIP induction.
      explanation: pDC depletion and type-I-IFN receptor blockade preceded induction in MRL/Mp mice; this does not demonstrate reversal of established human fibrosis.
- name: Increased IgG4 Secretion
  biological_scale: MOLECULAR
  description: NET-containing patient-pDC/healthy-B-cell cultures produce increased IgG4. The experiment measures secretion and does not resolve class-switch recombination versus expansion of previously switched cells. Increased serum IgG4 is a useful but nonuniversal clinical correlate of type 1 disease.
  evidence:
  - reference: PMID:26297761
    reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs.
    explanation: Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.
  - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
    reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: In addition, inhibition of NET formation by DNase or blockade of IFN- a–mediated signaling pathways by anti-IFNAR Ab signiﬁcantly reduced IgG4 production in a coculture system comprised of control B cells, patient-derived neutrophils, and patient-derived pDCs (Fig. 7C).
    explanation: DNase and IFNAR blockade reduced IgG4 secretion in a defined human coculture; intervening signals remain unresolved.
- name: Plasmablast Expansion
  biological_scale: CELLULAR
  description: Circulating plasmablasts expand in active IgG4-related disease, including some patients with AIP and normal serum IgG4. Oligoclonality supports antigen-driven selection but does not identify the antigen or prove that plasmablasts initiate pancreatic injury.
  evidence:
  - reference: PMID:24817416
    reference_title: Plasmablasts as a biomarker for IgG4-related disease, independent of serum IgG4 concentrations.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: All 37 patients with active, untreated IgG4-RD had elevated plasmablast counts despite the fact that thirteen (36%) had normal serum IgG4 concentrations.
    explanation: This selected active untreated IgG4-RD cohort included eight pancreatic cases; plasmablast expansion was not pancreas-specific.
  - reference: PMID:30558726
    reference_title: Tumefactive Inflammatory Diseases of the Pancreas.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The B-cell response is characterized by an oligoclonal expansion of plasmablasts, with dominant clones that vary among patients and distinct clones that emerge at the time of relapse.
    explanation: The review summarizes oligoclonal plasmablast findings.
  cell_types:
  - preferred_term: plasmablast
    term:
      id: CL:0000980
      label: plasmablast
  downstream:
  - target: CD4+SLAMF7+ Cytotoxic T Lymphocyte Expansion
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: B-lineage antigen presentation or growth factors may sustain these T cells. Rituximab-associated contraction is compatible with this hypothesis but does not establish the mediator.
    evidence:
    - reference: PMID:27667138
      reference_title: '"How I manage" IgG4-Related Disease.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: A key driver of IgG4-RD is believed to be a novel CD4+ cytotoxic T lymphocyte that bears SLAM-F7 on its surface. This cell is presumed to be sustained by continuous antigen presentation by cells of the B cell lineage, particularly plasmablasts.
      explanation: Expert hypothesis, without direct antigen-presentation perturbation.
  - target: Pancreatic Lymphoplasmacytic Infiltration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: The expanded B-lineage response plausibly contributes to the plasma-cell-rich lesion; migration and differentiation are not established by circulating counts alone.
    evidence:
    - reference: PMID:30558726
      reference_title: Tumefactive Inflammatory Diseases of the Pancreas.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The B-cell response is characterized by an oligoclonal expansion of plasmablasts, with dominant clones that vary among patients and distinct clones that emerge at the time of relapse.
      explanation: The systemic response is extrapolated to the pancreatic infiltrate.
  - target: Extrapancreatic Fibroinflammation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: The systemic B-lineage response may contribute to plasma-cell-rich lesions in other organs; blood counts alone do not establish trafficking or the responsible mediator.
    evidence:
    - reference: PMID:26672716
      reference_title: 'IgG4-related disease: The utility of (18)F-FDG PET/CT in diagnosis and treatment.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The organs most frequently involved are the pancreas (autoimmune pancreatitis (AIP), salivary and lacrimal glands (Mickulicz disease and sclerosing sialadenitis), biliary tree (sclerosing cholangitis or cholecystitis), retroperitoneum (retroperitoneal fibrosis), aorta (periaortic fibrosis), kidneys (interstitial nephritis) and thyroid (Riedel thyroiditis).
      explanation: Type 1 AIP participates in systemic IgG4-related organ inflammation.
- name: CD4+SLAMF7+ Cytotoxic T Lymphocyte Expansion
  biological_scale: CELLULAR
  description: Expanded CD4+SLAMF7+ effector populations occur in IgG4-related disease. A later 18-person study identified selective expansion of the CD8alpha-negative subset, with pancreas involved in ten patients. Clonal overlap and contraction during treatment support disease association; they do not establish a pancreatic autoantigen or selective causal necessity.
  evidence:
  - reference: PMID:26971690
    reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: CD4(+) effector/memory T cells with a cytolytic phenotype were expanded in patients with IgG4-RD.
    explanation: Expansion was observed in systemic IgG4-RD; 18.8% of the 101-person cohort had pancreatic involvement.
  - reference: PMID:29499100
    reference_title: A CD8α- Subset of CD4+SLAMF7+ Cytotoxic T Cells Is Expanded in Patients With IgG4-Related Disease and Decreases Following Glucocorticoid Treatment.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Clonally expanded CD8α- but not CD8αlow CD4+SLAMF7+ TEM cells decreased following glucocorticoid-induced disease remission.
    explanation: The uncontrolled before/after association does not demonstrate that selective CTL depletion mediates remission.
  cell_types:
  - preferred_term: CD4-positive SLAMF7-positive cytotoxic T lymphocyte
    term:
      id: CL:0000934
      label: CD4-positive, alpha-beta cytotoxic T cell
  downstream:
  - target: CD4 T Cell Cytolytic Activity
    causal_link_type: DIRECT
    description: The isolated expanded population exhibits this function after experimental stimulation.
    evidence:
    - reference: PMID:26971690
      reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: These CD4+ SLAMF7+ T cells cells have potent cytolytic function; upon in vitro stimulation with anti-CD3, these cells undergo degranulation as inferred from the surface expression of CD107a (Fig 2, D) and exhibit cytotoxic activity against allogeneic EBV-transformed B cell targets (Fig 2, E and Fig E6).
      explanation: The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.
  - target: TGF-Beta1 Secretion by CD4 T Cells
    causal_link_type: DIRECT
    description: The isolated expanded population exhibits this function after experimental stimulation.
    evidence:
    - reference: PMID:26971690
      reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: Upon in vitro stimulation, flow sorted CD4+ CTLs secreted large amounts of TGF-β1 compared to the naïve CD4+ cells from the same patients (Fig 5, E).
      explanation: TGF-beta1 secretion was measured after stimulation of sorted patient cells.
  - target: Interleukin-1-Beta Secretion by CD4 T Cells
    causal_link_type: DIRECT
    description: The isolated expanded population exhibits this function after experimental stimulation.
    evidence:
    - reference: PMID:26971690
      reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: The expanded CD4+ CTLs retained their SLAMF7 expression and cytotoxic markers and were found to secrete the processed form (17 kDa) of IL-1β upon re-stimulation with either anti-CD3 or LPS as determined by Western blot analysis of culture supernatants (Fig 5, D).
      explanation: Processed IL-1beta was measured in stimulated culture supernatants.
- name: CD4 T Cell Cytolytic Activity
  biological_scale: CELLULAR
  description: Patient-derived expanded CD4+SLAMF7+ cells degranulate and kill allogeneic EBV-transformed B-cell targets under stimulation. This establishes cytolytic capacity in culture, not pancreatic-target specificity.
  evidence:
  - reference: PMID:26971690
    reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: These CD4+ SLAMF7+ T cells cells have potent cytolytic function; upon in vitro stimulation with anti-CD3, these cells undergo degranulation as inferred from the surface expression of CD107a (Fig 2, D) and exhibit cytotoxic activity against allogeneic EBV-transformed B cell targets (Fig 2, E and Fig E6).
    explanation: The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.
  downstream:
  - target: Acinar Tissue Injury
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Cytolytic capacity may contribute to pancreatic injury, but the culture assay used B-cell targets and did not demonstrate pancreatic specificity.
    evidence:
    - reference: PMID:26971690
      reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: These CD4+ SLAMF7+ T cells cells have potent cytolytic function; upon in vitro stimulation with anti-CD3, these cells undergo degranulation as inferred from the surface expression of CD107a (Fig 2, D) and exhibit cytotoxic activity against allogeneic EBV-transformed B cell targets (Fig 2, E and Fig E6).
      explanation: The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.
- name: TGF-Beta1 Secretion by CD4 T Cells
  biological_scale: MOLECULAR
  description: Sorted patient-derived cytotoxic CD4 cells secrete TGF-beta1 after in-vitro activation, and relevant tissue lesions contain TGF-beta1-positive T cells. Direct necessity for pancreatic fibrosis has not been tested in this study.
  evidence:
  - reference: PMID:26971690
    reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: Upon in vitro stimulation, flow sorted CD4+ CTLs secreted large amounts of TGF-β1 compared to the naïve CD4+ cells from the same patients (Fig 5, E).
    explanation: TGF-beta1 secretion was measured after stimulation of sorted patient cells.
  downstream:
  - target: Storiform Fibrosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: The measured cytokine provides a plausible profibrotic contribution; no pancreatic fibrosis rescue or necessity experiment was performed in these patients.
    evidence:
    - reference: PMID:26971690
      reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: Upon in vitro stimulation, flow sorted CD4+ CTLs secreted large amounts of TGF-β1 compared to the naïve CD4+ cells from the same patients (Fig 5, E).
      explanation: TGF-beta1 secretion was measured after stimulation of sorted patient cells.
- name: Interleukin-1-Beta Secretion by CD4 T Cells
  biological_scale: MOLECULAR
  description: Expanded patient-derived CD4 cells release processed IL-1beta after stimulation. This provides a candidate inflammatory signal, with its contribution to human pancreatic fibrosis inferred from broader fibrotic biology.
  evidence:
  - reference: PMID:26971690
    reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: The expanded CD4+ CTLs retained their SLAMF7 expression and cytotoxic markers and were found to secrete the processed form (17 kDa) of IL-1β upon re-stimulation with either anti-CD3 or LPS as determined by Western blot analysis of culture supernatants (Fig 5, D).
    explanation: Processed IL-1beta was measured in stimulated culture supernatants.
  downstream:
  - target: Storiform Fibrosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: The measured cytokine provides a plausible profibrotic contribution; no pancreatic fibrosis rescue or necessity experiment was performed in these patients.
    evidence:
    - reference: PMID:26971690
      reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: The expanded CD4+ CTLs retained their SLAMF7 expression and cytotoxic markers and were found to secrete the processed form (17 kDa) of IL-1β upon re-stimulation with either anti-CD3 or LPS as determined by Western blot analysis of culture supernatants (Fig 5, D).
      explanation: Processed IL-1beta was measured in stimulated culture supernatants.
- name: Pancreatic Lymphoplasmacytic Infiltration
  biological_scale: TISSUE
  description: Type 1 AIP contains a dense lymphocyte and plasma-cell infiltrate, often rich in IgG4-positive plasma cells. Tissue IgG4-positive cells alone are not disease-specific, and neither their abundance nor serum IgG4 proves that IgG4 is the sole damaging effector.
  evidence:
  - reference: PMID:29512140
    reference_title: Autoimmune Pancreatitis Mouse Model.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Type 1 AIP (also called LPSP) is characterized by dense lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis. This is accompanied by massive accumulation of IgG4-expressing plasma cells and, in some patients with elevated levels of serum IgG4 and involvement of other organs, including bile ducts, salivary glands, and kidney.
    explanation: Clinical pathological synthesis of type 1 AIP.
  locations:
  - preferred_term: pancreas
    term:
      id: UBERON:0001264
      label: pancreas
  downstream:
  - target: Storiform Fibrosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Chronic immune infiltration is associated with the characteristic fibrotic response; individual profibrotic mediators are incompletely resolved.
    evidence:
    - reference: PMID:29512140
      reference_title: Autoimmune Pancreatitis Mouse Model.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Type 1 AIP (also called LPSP) is characterized by dense lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis. This is accompanied by massive accumulation of IgG4-expressing plasma cells and, in some patients with elevated levels of serum IgG4 and involvement of other organs, including bile ducts, salivary glands, and kidney.
      explanation: Clinical pathological synthesis of type 1 AIP.
  - target: Obliterative Phlebitis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: The inflammatory lesion extends into venous walls and lumina, producing the characteristic phlebitis.
    evidence:
    - reference: PMID:29512140
      reference_title: Autoimmune Pancreatitis Mouse Model.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Type 1 AIP (also called LPSP) is characterized by dense lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis. This is accompanied by massive accumulation of IgG4-expressing plasma cells and, in some patients with elevated levels of serum IgG4 and involvement of other organs, including bile ducts, salivary glands, and kidney.
      explanation: Clinical pathological synthesis of type 1 AIP.
  - target: Acinar Tissue Injury
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Pancreatic inflammation is associated with parenchymal injury and atrophy.
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK560769/
      reference_title: Autoimmune Pancreatitis - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Fibrosis may resemble chronic obstructive pancreatitis, characterized by interlobular and intralobular fibrosis and acinar atrophy.
      explanation: Clinical review describes fibrosis and acinar loss.
  - target: Pancreatic Enlargement
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Inflammation and fibrosis contribute to the mass-like tissue lesion.
    evidence:
    - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: The classical imaging features of AIP are paren- chymal enlargement, ‘sausage-like’ shape, peripancre- atic edematous rim, and main pancreatic duct narrowing without upstream dilatation. These features may be diffuse or focal but can also be highly variable. (GRADE 2C; strong agreement)
      explanation: Guideline synthesis of variable pancreatic morphology.
  - target: Pancreatic Duct Narrowing
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Periductal inflammation and fibrosis contribute to duct narrowing.
    evidence:
    - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: The classical imaging features of AIP are paren- chymal enlargement, ‘sausage-like’ shape, peripancre- atic edematous rim, and main pancreatic duct narrowing without upstream dilatation. These features may be diffuse or focal but can also be highly variable. (GRADE 2C; strong agreement)
      explanation: Guideline synthesis of variable pancreatic morphology.
  - target: Pancreatic Islet Injury
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Inflammation and fibrosis can contribute to endocrine islet injury, with intermediate vascular and tissue effects inferred.
    evidence:
    - reference: PMID:35807009
      reference_title: 'Exocrine and Endocrine Insufficiency in Autoimmune Pancreatitis: A Matter of Treatment or Time?'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Histological analysis revealed that islet cells of AIP patients were either intact or destroyed due to edema and ischemia because of fibrosis and lymphoplasmatic cell infiltration [25].
      explanation: The paper summarizes prior human histology; islet injury varies between patients.
- name: Storiform Fibrosis
  biological_scale: TISSUE
  description: A patterned fibrotic reaction is characteristic of type 1 AIP. Cellular cytokine findings provide possible contributors, but human causal ordering and the relative roles of fibroblasts, immune cells and antibodies remain incompletely resolved.
  evidence:
  - reference: PMID:29512140
    reference_title: Autoimmune Pancreatitis Mouse Model.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Type 1 AIP (also called LPSP) is characterized by dense lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis. This is accompanied by massive accumulation of IgG4-expressing plasma cells and, in some patients with elevated levels of serum IgG4 and involvement of other organs, including bile ducts, salivary glands, and kidney.
    explanation: Clinical pathological synthesis of type 1 AIP.
  locations:
  - preferred_term: pancreas
    term:
      id: UBERON:0001264
      label: pancreas
  downstream:
  - target: Acinar Tissue Injury
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Fibrotic remodeling can accompany loss of pancreatic acini.
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK560769/
      reference_title: Autoimmune Pancreatitis - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Fibrosis may resemble chronic obstructive pancreatitis, characterized by interlobular and intralobular fibrosis and acinar atrophy.
      explanation: Clinical review describes fibrosis and acinar loss.
  - target: Pancreatic Enlargement
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Inflammation and fibrosis contribute to the mass-like tissue lesion.
    evidence:
    - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: The classical imaging features of AIP are paren- chymal enlargement, ‘sausage-like’ shape, peripancre- atic edematous rim, and main pancreatic duct narrowing without upstream dilatation. These features may be diffuse or focal but can also be highly variable. (GRADE 2C; strong agreement)
      explanation: Guideline synthesis of variable pancreatic morphology.
  - target: Pancreatic Duct Narrowing
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Periductal inflammation and fibrosis contribute to duct narrowing.
    evidence:
    - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: The classical imaging features of AIP are paren- chymal enlargement, ‘sausage-like’ shape, peripancre- atic edematous rim, and main pancreatic duct narrowing without upstream dilatation. These features may be diffuse or focal but can also be highly variable. (GRADE 2C; strong agreement)
      explanation: Guideline synthesis of variable pancreatic morphology.
  - target: Pancreatic Islet Injury
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Inflammation and fibrosis can contribute to endocrine islet injury, with intermediate vascular and tissue effects inferred.
    evidence:
    - reference: PMID:35807009
      reference_title: 'Exocrine and Endocrine Insufficiency in Autoimmune Pancreatitis: A Matter of Treatment or Time?'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Histological analysis revealed that islet cells of AIP patients were either intact or destroyed due to edema and ischemia because of fibrosis and lymphoplasmatic cell infiltration [25].
      explanation: The paper summarizes prior human histology; islet injury varies between patients.
- name: Obliterative Phlebitis
  biological_scale: TISSUE
  description: Inflammatory involvement and obliteration of small veins form a characteristic type 1 pathological lesion. This finding is evaluated alongside the infiltrate and fibrosis, rather than being a universal feature of every small biopsy.
  evidence:
  - reference: PMID:29512140
    reference_title: Autoimmune Pancreatitis Mouse Model.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Type 1 AIP (also called LPSP) is characterized by dense lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis. This is accompanied by massive accumulation of IgG4-expressing plasma cells and, in some patients with elevated levels of serum IgG4 and involvement of other organs, including bile ducts, salivary glands, and kidney.
    explanation: Clinical pathological synthesis of type 1 AIP.
  locations:
  - preferred_term: pancreas
    term:
      id: UBERON:0001264
      label: pancreas
- name: Acinar Tissue Injury
  biological_scale: TISSUE
  description: Inflammatory injury and fibrotic remodeling damage the exocrine pancreatic parenchyma. Cytotoxic cells and tissue-binding antibodies are candidate contributors; their relative importance in patients is unresolved.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK560769/
    reference_title: Autoimmune Pancreatitis - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Fibrosis may resemble chronic obstructive pancreatitis, characterized by interlobular and intralobular fibrosis and acinar atrophy.
    explanation: Clinical review describes fibrosis and acinar loss.
  locations:
  - preferred_term: pancreas
    term:
      id: UBERON:0001264
      label: pancreas
  downstream:
  - target: Exocrine pancreatic insufficiency
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Loss or dysfunction of pancreatic exocrine tissue contributes to impaired digestion.
    evidence:
    - reference: PMID:35807009
      reference_title: 'Exocrine and Endocrine Insufficiency in Autoimmune Pancreatitis: A Matter of Treatment or Time?'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: PRIMARY_RESULT
      snippet: 'CONCLUSIONS: Our results suggest that the prevalence of endocrine and exocrine insufficiency in AIP is high at diagnosis with an additional risk of PEI and DM during follow-up despite pharmacological treatment.'
      explanation: Human clinical dysfunction is linked indirectly to tissue injury.
  - target: Weight loss
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Pancreatic disease can contribute to weight loss through several routes; malabsorption is not established in every symptomatic patient.
    evidence:
    - reference: PMID:36293522
      reference_title: 'Autoimmune Pancreatitis: From Pathogenesis to Treatment.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: In both cases, the clinical presentation is non-specific and is characterized by overlapping features with more sinister pathologies, such as pancreatic cancer, including jaundice, weight loss, and abdominal pain in some cases; for this reason, major efforts are required to find more specific tools to make differential diagnosis possible even without biopsy [101].
      explanation: Clinical association with AIP, with intermediates inferred.
- name: Pancreatic Enlargement
  biological_scale: TISSUE
  description: Diffuse or focal inflammatory enlargement can create a mass-like pancreatic appearance in either established subtype. It is suggestive but cannot independently distinguish AIP from malignancy.
  evidence:
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: The classical imaging features of AIP are paren- chymal enlargement, ‘sausage-like’ shape, peripancre- atic edematous rim, and main pancreatic duct narrowing without upstream dilatation. These features may be diffuse or focal but can also be highly variable. (GRADE 2C; strong agreement)
    explanation: Guideline synthesis of variable pancreatic morphology.
  locations:
  - preferred_term: pancreas
    term:
      id: UBERON:0001264
      label: pancreas
  downstream:
  - target: Pancreatic mass
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Inflammatory enlargement can produce the mass-like clinical imaging finding.
    evidence:
    - reference: PMID:32809604
      reference_title: Autoimmune Pancreatitis.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Other cases present with abdominal pain or are discovered in asymptomatic individuals with a pancreatic mass, pancreatic duct stricturing, or an enlarged pancreas.
      explanation: The review lists enlargement and a mass-like presentation.
- name: Pancreatic Duct Narrowing
  biological_scale: TISSUE
  description: Inflammatory duct involvement produces irregular narrowing, often without marked upstream dilation at presentation. Later duct dilation or stones can occur in chronic disease.
  evidence:
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: The classical imaging features of AIP are paren- chymal enlargement, ‘sausage-like’ shape, peripancre- atic edematous rim, and main pancreatic duct narrowing without upstream dilatation. These features may be diffuse or focal but can also be highly variable. (GRADE 2C; strong agreement)
    explanation: Guideline synthesis of variable pancreatic morphology.
  locations:
  - preferred_term: pancreas
    term:
      id: UBERON:0001264
      label: pancreas
- name: Increased Ductal Interleukin-8 Expression
  biological_scale: MOLECULAR
  description: Type 2 AIP specimens show increased IL-8 expression in ductal epithelium and infiltrating cells compared with type 1. The relationship to neutrophil recruitment is biologically plausible but not proven necessary by these tissue observations.
  evidence:
  - reference: PMID:28614208
    reference_title: IL-8 Expression in Granulocytic Epithelial Lesions of Idiopathic Duct-centric Pancreatitis (Type 2 Autoimmune Pancreatitis).
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: In quantitative polymerase chain reaction for multiple cytokines using tissue-derived mRNA, the expression level of interleukin (IL)-8 was markedly higher in type 2 AIP than in type 1 AIP (P<0.001).
    explanation: Tissue-derived expression was compared between subtypes; this was not a chemotaxis or IL-8 blockade experiment.
  downstream:
  - target: Neutrophilic Duct Infiltration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: IL-8 expression is consistent with recruitment of neutrophils, but necessity and temporal ordering were not tested.
    evidence:
    - reference: PMID:28614208
      reference_title: IL-8 Expression in Granulocytic Epithelial Lesions of Idiopathic Duct-centric Pancreatitis (Type 2 Autoimmune Pancreatitis).
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: PRIMARY_RESULT
      snippet: In quantitative polymerase chain reaction for multiple cytokines using tissue-derived mRNA, the expression level of interleukin (IL)-8 was markedly higher in type 2 AIP than in type 1 AIP (P<0.001).
      explanation: Tissue-derived expression was compared between subtypes; this was not a chemotaxis or IL-8 blockade experiment.
- name: Neutrophilic Duct Infiltration
  biological_scale: CELLULAR
  description: In type 2 AIP, neutrophils infiltrate ductal epithelium and can extend into acinar tissue. Tissue sampling affects detection, and comparable nonspecific inflammatory changes must be distinguished from diagnostic granulocytic epithelial lesions.
  evidence:
  - reference: PMID:34670874
    reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The neutrophil-rich nature of inflammation discriminates type 2 from type 1 AIP.1,2,17 Characteristically, many neutrophils infiltrate the epithelial layer of the pancreatic ducts, a finding designated as GEL (Fig. 1C).2 Intraductal clusters of neutrophils resembling crypt abscesses in IBD often co-exist (Fig. 1D). Neutrophilic infiltration is also present in acini or around small ductules, but is less specific for the diagnosis of type 2 AIP.
    explanation: Review description of the defining neutrophilic duct lesion.
  cell_types:
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  downstream:
  - target: Duct Epithelial Injury
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Neutrophils within the epithelium are associated with local epithelial damage in the defining lesion.
    evidence:
    - reference: PMID:34670874
      reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The neutrophil-rich nature of inflammation discriminates type 2 from type 1 AIP.1,2,17 Characteristically, many neutrophils infiltrate the epithelial layer of the pancreatic ducts, a finding designated as GEL (Fig. 1C).2 Intraductal clusters of neutrophils resembling crypt abscesses in IBD often co-exist (Fig. 1D). Neutrophilic infiltration is also present in acini or around small ductules, but is less specific for the diagnosis of type 2 AIP.
      explanation: Review description of the defining neutrophilic duct lesion.
- name: Duct Epithelial Injury
  biological_scale: TISSUE
  description: Neutrophil-associated duct epithelial damage and destruction produce granulocytic epithelial lesions in type 2 AIP.
  evidence:
  - reference: PMID:34670874
    reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The neutrophil-rich nature of inflammation discriminates type 2 from type 1 AIP.1,2,17 Characteristically, many neutrophils infiltrate the epithelial layer of the pancreatic ducts, a finding designated as GEL (Fig. 1C).2 Intraductal clusters of neutrophils resembling crypt abscesses in IBD often co-exist (Fig. 1D). Neutrophilic infiltration is also present in acini or around small ductules, but is less specific for the diagnosis of type 2 AIP.
    explanation: Review description of the defining neutrophilic duct lesion.
  locations:
  - preferred_term: pancreas
    term:
      id: UBERON:0001264
      label: pancreas
  downstream:
  - target: Pancreatic Duct Narrowing
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Duct-centric inflammation can contribute to the shared imaging abnormality.
    evidence:
    - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: The classical imaging features of AIP are paren- chymal enlargement, ‘sausage-like’ shape, peripancre- atic edematous rim, and main pancreatic duct narrowing without upstream dilatation. These features may be diffuse or focal but can also be highly variable. (GRADE 2C; strong agreement)
      explanation: Guideline synthesis of variable pancreatic morphology.
  - target: Acinar Tissue Injury
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Duct-centric inflammation can extend into pancreatic parenchyma; the complete sequence is inferred.
    evidence:
    - reference: PMID:34670874
      reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The neutrophil-rich nature of inflammation discriminates type 2 from type 1 AIP.1,2,17 Characteristically, many neutrophils infiltrate the epithelial layer of the pancreatic ducts, a finding designated as GEL (Fig. 1C).2 Intraductal clusters of neutrophils resembling crypt abscesses in IBD often co-exist (Fig. 1D). Neutrophilic infiltration is also present in acini or around small ductules, but is less specific for the diagnosis of type 2 AIP.
      explanation: Review description of the defining neutrophilic duct lesion.
  - target: Acute pancreatitis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Type 2 duct-centric inflammatory injury can contribute to this clinical presentation; the individual intermediate sequence is not directly tested.
    evidence:
    - reference: PMID:34670874
      reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The majority of patients with type 2 AIP present with features of acute pancreatitis (60%) or painless jaundice (30%).6,7 Episodes of acute pancreatitis in patients with type 2 AIP are clinically mild without the need for intensive care unit admission, the development of organ failure, or peripancreatic fluid collection.6 Other less common patterns of presentation include liver dysfunction, non-specific abdominal symptoms, and the incidental detection of a pancreatic mass on images taken for other purposes.
      explanation: Subtype-specific clinical synthesis.
  - target: Recurrent acute pancreatitis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Type 2 duct-centric inflammatory injury can contribute to this clinical presentation; the individual intermediate sequence is not directly tested.
    evidence:
    - reference: PMID:34670874
      reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The majority of patients with type 2 AIP present with features of acute pancreatitis (60%) or painless jaundice (30%).6,7 Episodes of acute pancreatitis in patients with type 2 AIP are clinically mild without the need for intensive care unit admission, the development of organ failure, or peripancreatic fluid collection.6 Other less common patterns of presentation include liver dysfunction, non-specific abdominal symptoms, and the incidental detection of a pancreatic mass on images taken for other purposes.
      explanation: Subtype-specific clinical synthesis.
  - target: Abdominal pain
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Type 2 duct-centric inflammatory injury can contribute to this clinical presentation; the individual intermediate sequence is not directly tested.
    evidence:
    - reference: PMID:34670874
      reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The majority of patients with type 2 AIP present with features of acute pancreatitis (60%) or painless jaundice (30%).6,7 Episodes of acute pancreatitis in patients with type 2 AIP are clinically mild without the need for intensive care unit admission, the development of organ failure, or peripancreatic fluid collection.6 Other less common patterns of presentation include liver dysfunction, non-specific abdominal symptoms, and the incidental detection of a pancreatic mass on images taken for other purposes.
      explanation: Subtype-specific clinical synthesis.
- name: Extrapancreatic Fibroinflammation
  biological_scale: TISSUE
  description: Type 1 AIP may coexist with IgG4-related inflammatory lesions in bile ducts, salivary glands and other organs. These are manifestations of the systemic disorder, rather than obligatory downstream effects of pancreatic injury.
  evidence:
  - reference: PMID:26672716
    reference_title: 'IgG4-related disease: The utility of (18)F-FDG PET/CT in diagnosis and treatment.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The organs most frequently involved are the pancreas (autoimmune pancreatitis (AIP), salivary and lacrimal glands (Mickulicz disease and sclerosing sialadenitis), biliary tree (sclerosing cholangitis or cholecystitis), retroperitoneum (retroperitoneal fibrosis), aorta (periaortic fibrosis), kidneys (interstitial nephritis) and thyroid (Riedel thyroiditis).
    explanation: Type 1 AIP participates in systemic IgG4-related organ inflammation.
  downstream:
  - target: IgG4-related sclerosing cholangitis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Site-specific IgG4-related inflammation produces this associated manifestation.
    evidence:
    - reference: PMID:26672716
      reference_title: 'IgG4-related disease: The utility of (18)F-FDG PET/CT in diagnosis and treatment.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The organs most frequently involved are the pancreas (autoimmune pancreatitis (AIP), salivary and lacrimal glands (Mickulicz disease and sclerosing sialadenitis), biliary tree (sclerosing cholangitis or cholecystitis), retroperitoneum (retroperitoneal fibrosis), aorta (periaortic fibrosis), kidneys (interstitial nephritis) and thyroid (Riedel thyroiditis).
      explanation: Type 1 AIP participates in systemic IgG4-related organ inflammation.
  - target: IgG4-related sialadenitis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Site-specific IgG4-related inflammation produces this associated manifestation.
    evidence:
    - reference: PMID:26672716
      reference_title: 'IgG4-related disease: The utility of (18)F-FDG PET/CT in diagnosis and treatment.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The organs most frequently involved are the pancreas (autoimmune pancreatitis (AIP), salivary and lacrimal glands (Mickulicz disease and sclerosing sialadenitis), biliary tree (sclerosing cholangitis or cholecystitis), retroperitoneum (retroperitoneal fibrosis), aorta (periaortic fibrosis), kidneys (interstitial nephritis) and thyroid (Riedel thyroiditis).
      explanation: Type 1 AIP participates in systemic IgG4-related organ inflammation.
  - target: Obstructive jaundice
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Associated biliary inflammation and obstruction can cause jaundice; pancreatic compression is an alternative route.
    evidence:
    - reference: PMID:32809604
      reference_title: Autoimmune Pancreatitis.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The most common clinical presentation of type 1 AIP is painless jaundice with laboratory studies suggesting biliary obstruction and hyperglycemia.
      explanation: Clinical biliary obstruction is linked indirectly to the inflammatory disease.
  - target: Retroperitoneal fibrosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Systemic fibroinflammatory disease can involve retroperitoneal tissue.
    evidence:
    - reference: PMID:26672716
      reference_title: 'IgG4-related disease: The utility of (18)F-FDG PET/CT in diagnosis and treatment.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The organs most frequently involved are the pancreas (autoimmune pancreatitis (AIP), salivary and lacrimal glands (Mickulicz disease and sclerosing sialadenitis), biliary tree (sclerosing cholangitis or cholecystitis), retroperitoneum (retroperitoneal fibrosis), aorta (periaortic fibrosis), kidneys (interstitial nephritis) and thyroid (Riedel thyroiditis).
      explanation: Type 1 AIP participates in systemic IgG4-related organ inflammation.
- name: Pancreatic Islet Injury
  biological_scale: TISSUE
  description: Inflammation, edema and fibrotic remodeling can impair or damage endocrine islets. Some AIP specimens have preserved islets, and diabetes can also predate AIP or be aggravated by glucocorticoids. Pancreatic endocrine dysfunction is therefore not inferred from acinar injury alone.
  evidence:
  - reference: PMID:35807009
    reference_title: 'Exocrine and Endocrine Insufficiency in Autoimmune Pancreatitis: A Matter of Treatment or Time?'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Histological analysis revealed that islet cells of AIP patients were either intact or destroyed due to edema and ischemia because of fibrosis and lymphoplasmatic cell infiltration [25].
    explanation: The paper summarizes prior human histology; islet injury varies between patients.
  locations:
  - preferred_term: islet of Langerhans
    term:
      id: UBERON:0000006
      label: islet of Langerhans
  downstream:
  - target: Diabetes mellitus
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Loss or dysfunction of islet cells can contribute to pancreatic diabetes; this does not account for every diabetic patient with AIP.
    evidence:
    - reference: PMID:35807009
      reference_title: 'Exocrine and Endocrine Insufficiency in Autoimmune Pancreatitis: A Matter of Treatment or Time?'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Histological analysis revealed that islet cells of AIP patients were either intact or destroyed due to edema and ischemia because of fibrosis and lymphoplasmatic cell infiltration [25].
      explanation: The paper summarizes prior human histology; islet injury varies between patients.
phenotypes:
- name: Obstructive jaundice
  category: Hepatobiliary
  description: Often painless; may reflect intrapancreatic biliary obstruction or associated IgG4-related cholangitis. It is not specific for AIP and warrants assessment for malignancy.
  phenotype_term:
    preferred_term: Biliary tract obstruction
    term:
      id: HP:0005230
      label: Biliary tract obstruction
  evidence:
  - reference: PMID:32809604
    reference_title: Autoimmune Pancreatitis.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The most common clinical presentation of type 1 AIP is painless jaundice with laboratory studies suggesting biliary obstruction and hyperglycemia.
    explanation: Review describes the presentation without a source-specific numerator.
- name: Acute pancreatitis
  category: Gastrointestinal
  description: A common type 2 presentation, generally mild in the series summarized by the review. This frequency does not mean that every episode is recurrent.
  phenotype_term:
    preferred_term: Acute pancreatitis
    term:
      id: HP:0001735
      label: Acute pancreatitis
  evidence:
  - reference: PMID:34670874
    reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The majority of patients with type 2 AIP present with features of acute pancreatitis (60%) or painless jaundice (30%).6,7 Episodes of acute pancreatitis in patients with type 2 AIP are clinically mild without the need for intensive care unit admission, the development of organ failure, or peripancreatic fluid collection.6 Other less common patterns of presentation include liver dysfunction, non-specific abdominal symptoms, and the incidental detection of a pancreatic mass on images taken for other purposes.
    explanation: Subtype-specific review estimate.
  subtype: Type 2
  frequency: FREQUENT
- name: Recurrent acute pancreatitis
  category: Gastrointestinal
  description: Recurrent episodes can lead to evaluation for type 2 AIP. Recurrence is distinct from the occurrence of a single acute presenting episode.
  phenotype_term:
    preferred_term: Recurrent pancreatitis
    term:
      id: HP:0100027
      label: Recurrent pancreatitis
  evidence:
  - reference: PMID:28365915
    reference_title: Autoimmune Pancreatitis.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Idiopathic duct-centric pancreatitis (IDCP) is a closely related but distinct disease that mimics AIP radiologically but manifests clinically most commonly as recurrent acute pancreatitis in young individuals with concurrent inflammatory bowel disease.
    explanation: Clinical review supports recurrent presentation without a reliable pooled denominator.
  subtype: Type 2
- name: Pancreatic mass
  category: Gastrointestinal
  description: Focal or diffuse inflammatory enlargement can mimic a pancreatic tumor. AIP can also present with isolated duct changes without a mass.
  phenotype_term:
    preferred_term: Pancreatic mass
    term:
      id: HP:6000409
      label: Pancreatic mass
  evidence:
  - reference: PMID:32809604
    reference_title: Autoimmune Pancreatitis.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Other cases present with abdominal pain or are discovered in asymptomatic individuals with a pancreatic mass, pancreatic duct stricturing, or an enlarged pancreas.
    explanation: Review identifies mass-like and ductal presentations.
- name: Exocrine pancreatic insufficiency
  category: Gastrointestinal
  description: Reported before initial glucocorticoids in 409/2,813 patients in the Japanese 2021 survey. A selected specialist cohort found 32/44 at diagnosis, so the frequency depends strongly on case selection and testing.
  phenotype_term:
    preferred_term: Exocrine pancreatic insufficiency
    term:
      id: HP:0001738
      label: Exocrine pancreatic insufficiency
  evidence:
  - reference: url:https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    reference_title: https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Similarly, pancreatic exocrine insufficiency was observed in 409 of 2813 patients (14.5%) before treatment and increased to 476 (16.9%) after therapy (P = 0.014).
    explanation: Survey numerator and denominator; not a treatment-effect estimate.
  - reference: PMID:35807009
    reference_title: 'Exocrine and Endocrine Insufficiency in Autoimmune Pancreatitis: A Matter of Treatment or Time?'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: PEI prevalence at diagnosis was 72.7% and was 63.5% at follow-up.
    explanation: Specialist cohort with different testing ascertainment.
  subtype: Type 1
- name: Diabetes mellitus
  category: Endocrine
  description: Diabetes was present before initial glucocorticoids in 1,250/2,790 (44.8%) in the 2021 survey. It may predate AIP, accompany pancreatic injury, or emerge during follow-up and treatment; these mechanisms cannot be separated by the prevalence estimate.
  phenotype_term:
    preferred_term: Diabetes mellitus
    term:
      id: HP:0000819
      label: Diabetes mellitus
  evidence:
  - reference: url:https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    reference_title: https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Diabetes mellitus was present in 1250 of 2790 patients (44.8%) before initial GC therapy and increased signifi- cantly to 1428 (51.2%) after therapy (P < 0.001).
    explanation: Pre-treatment survey estimate.
  subtype: Type 1
  frequency: FREQUENT
- name: IgG4-related sclerosing cholangitis
  category: Hepatobiliary
  description: The most common associated organ manifestation in the 2021 survey, recorded in 1,363/2,819 assessed patients (48.4%). It reflects systemic type 1 disease and is not a consequence of pancreatic fibrosis in every patient.
  phenotype_term:
    preferred_term: Sclerosing cholangitis
    term:
      id: HP:0030991
      label: Sclerosing cholangitis
  evidence:
  - reference: url:https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    reference_title: https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Table 1 Distribution of OOI observed in patients with AIP OOI other organ involvement, SD standard deviation a Among 2819 cases b Overlap observed in 177 cases c Overlap observed in 128 cases d OOI listed in this table e OOI defined in the JPS2018 criteria Type of OOI n (%)a IgG4-related sclerosing cholangitis 1363 (48.4) Proximal 306 (10.9)b Distal 1234 (43.8)b Sialadenitis/dacryoadenitis 566 (20.1) Sialadenitis 489 (17.3)c Dacryoadenitis 205 (7.3)c Retroperitoneal fibrosis 342 (12.1) IgG4-related kidney disease 235 (8.3)
    explanation: Table 1 reports the assessed organ-involvement denominator and cholangitis count.
  subtype: Type 1
  frequency: FREQUENT
- name: IgG4-related sialadenitis
  category: Head and neck
  description: Salivary-gland involvement was recorded in 489/2,819 assessed patients (17.3%) in the 2021 survey. Lacrimal involvement was recorded separately and is not included in this salivary-gland count.
  phenotype_term:
    preferred_term: Sialadenitis
    term:
      id: HP:0031281
      label: Sialadenitis
  evidence:
  - reference: url:https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    reference_title: https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Table 1 Distribution of OOI observed in patients with AIP OOI other organ involvement, SD standard deviation a Among 2819 cases b Overlap observed in 177 cases c Overlap observed in 128 cases d OOI listed in this table e OOI defined in the JPS2018 criteria Type of OOI n (%)a IgG4-related sclerosing cholangitis 1363 (48.4) Proximal 306 (10.9)b Distal 1234 (43.8)b Sialadenitis/dacryoadenitis 566 (20.1) Sialadenitis 489 (17.3)c Dacryoadenitis 205 (7.3)c Retroperitoneal fibrosis 342 (12.1) IgG4-related kidney disease 235 (8.3)
    explanation: Table 1 distinguishes salivary from lacrimal involvement.
  subtype: Type 1
  frequency: OCCASIONAL
- name: Weight loss
  category: Constitutional
  description: Weight loss is a nonspecific presentation and can also prompt a pancreatic malignancy work-up. It should not automatically be attributed to malabsorption.
  phenotype_term:
    preferred_term: Weight loss
    term:
      id: HP:0001824
      label: Weight loss
  evidence:
  - reference: PMID:36293522
    reference_title: 'Autoimmune Pancreatitis: From Pathogenesis to Treatment.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: In both cases, the clinical presentation is non-specific and is characterized by overlapping features with more sinister pathologies, such as pancreatic cancer, including jaundice, weight loss, and abdominal pain in some cases; for this reason, major efforts are required to find more specific tools to make differential diagnosis possible even without biopsy [101].
    explanation: Clinical review lists overlapping presentations.
- name: Abdominal pain
  category: Gastrointestinal
  description: Pain may accompany acute pancreatic inflammation or other pancreaticobiliary disease. Reports grouping pain with acute pancreatitis do not establish the frequency of pain alone.
  phenotype_term:
    preferred_term: Abdominal pain
    term:
      id: HP:0002027
      label: Abdominal pain
  evidence:
  - reference: PMID:32809604
    reference_title: Autoimmune Pancreatitis.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Unlike patients with type 1 AIP, about half of those with type 2 AIP present with abdominal pain or acute pancreatitis.
    explanation: The source groups two presentations, so no individual frequency is assigned.
- name: Retroperitoneal fibrosis
  category: Multisystem
  description: Associated systemic type 1 disease was recorded in 342/2,819 assessed patients (12.1%) in the 2021 Japanese survey.
  phenotype_term:
    preferred_term: Retroperitoneal fibrosis
    term:
      id: HP:0005200
      label: Retroperitoneal fibrosis
  evidence:
  - reference: url:https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    reference_title: https://link.springer.com/content/pdf/10.1007/s00535-026-02438-w.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Table 1 Distribution of OOI observed in patients with AIP OOI other organ involvement, SD standard deviation a Among 2819 cases b Overlap observed in 177 cases c Overlap observed in 128 cases d OOI listed in this table e OOI defined in the JPS2018 criteria Type of OOI n (%)a IgG4-related sclerosing cholangitis 1363 (48.4) Proximal 306 (10.9)b Distal 1234 (43.8)b Sialadenitis/dacryoadenitis 566 (20.1) Sialadenitis 489 (17.3)c Dacryoadenitis 205 (7.3)c Retroperitoneal fibrosis 342 (12.1) IgG4-related kidney disease 235 (8.3)
    explanation: Organ-involvement table with assessed denominator.
  subtype: Type 1
  frequency: OCCASIONAL
biochemical:
- name: Circulating plasmablasts
  presence: Increased
  context: Research biomarker measured in 37 selected active untreated systemic IgG4-RD cases, including eight with pancreatic involvement, versus 14 healthy and 21 disease controls. Thirteen of 36 with available serum IgG4 had normal values. These data do not validate a pancreatic-cancer differential test or a universal relapse predictor.
  biomarker_term:
    preferred_term: plasmablast
    term:
      id: CL:0000980
      label: plasmablast
  readouts:
  - target: Plasmablast Expansion
    relationship: READOUT_OF
    direction: POSITIVE
    interpretation: Circulating cell counts directly measure the expanded plasmablast compartment; they do not establish pancreatic trafficking or clinical diagnostic specificity.
    evidence:
    - reference: PMID:24817416
      reference_title: Plasmablasts as a biomarker for IgG4-related disease, independent of serum IgG4 concentrations.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: The IgG4-RD patients had substantially elevated total plasmablast counts (median 4698/mL, range 610-79524/mL) compared to both untreated disease controls (median 592/mL, range 19-4294/mL; p < 0.001) and healthy controls (median 94/mL, range 1-653/mL; p < 0.001).
      explanation: Selected systemic IgG4-related disease cohort with assay-specific denominators.
      quote_role: PRIMARY_RESULT
      directness: DIRECT
    - reference: PMID:24817416
      reference_title: Plasmablasts as a biomarker for IgG4-related disease, independent of serum IgG4 concentrations.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Among IgG4-RD patients, thirteen (36%) had normal serum IgG4 concentrations
      explanation: Selected systemic IgG4-related disease cohort with assay-specific denominators.
      quote_role: PRIMARY_RESULT
      directness: DIRECT
- name: Serum IgG4
  presence: Often increased in type 1; may be normal
  context: An adjunct to integrated diagnosis. Elevated values occur in other conditions, and type 2 generally has normal or mildly elevated IgG4. The 43% sensitivity reported in a surgical meta-analysis came from 21/49 tested resected type 1 cases and must not be used as general diagnostic sensitivity.
  evidence:
  - reference: PMID:34670874
    reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: In contrast to type 1 AIP, which is a pancreatic manifestation of IgG4-related disease, serum IgG4 concentrations are normal or only mildly elevated in type 2 AIP.5 Serum IgG4 elevations >300 mg/dL (or >2-fold higher than the normal range) are highly suggestive of type 1 AIP.6-8 Since the ratio of serum IgG4/IgG is typical >10% in type 1 AIP and ≤10% in other conditions, this calculation is useful for cases with only a mild IgG4 elevation.9 Although specific serological markers are not currently available for type 2 AIP, anti-neutrophil cytoplasmic antibodies can be detected in patients with type 2 AIP.10 The assessment of extrapancreatic diseases is useful for the typing of AIP.
    explanation: Subtype-specific serological distinction.
  - reference: PMID:39169289
    reference_title: 'Prevalence of autoimmune pancreatitis in pancreatic resection for suspected malignancy: a systematic review and meta-analysis.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: The sensitivity of IgG4 levels in type 1 AIP was low (43%, 21/49 patients).
    explanation: Highly selected resected cohort with incomplete testing.
- name: Candidate autoantibodies against galectin-3 and prohibitin 1  # codespell:ignore prohibitin
  presence: Detected in subsets of IgG4-related cholangitis
  context: In a 52-person IgG4-related cholangitis cohort, antibodies to galectin-3 and prohibitin 1 were also seen in some comparator groups. This is not a germline genetic finding or an AIP-specific diagnostic assay. Cholangiocyte perturbation and antibody experiments did not establish a consistent bile-acid-injury mechanism.  # codespell:ignore prohibitin
  evidence:
  - reference: PMID:38332916
    reference_title: Galectin-3 and prohibitin 1 are autoantigens in IgG4-related cholangitis without clear-cut protective effects against toxic bile acids.  # codespell:ignore prohibitin
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: 'RESULTS: Anti-galectin-3 autoantibodies were detected in 13.5% of individuals with IRC but not in PSC.'
    explanation: Cholangitis cohort, not an AIP-only series.
  - reference: PMID:38332916
    reference_title: Galectin-3 and prohibitin 1 are autoantigens in IgG4-related cholangitis without clear-cut protective effects against toxic bile acids.  # codespell:ignore prohibitin
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: Gene-specific knockdown, pharmacological inhibition, and recombinant protein substitution did not clearly disclose a protective role of these autoantigens in human cholangiocytes against toxic bile acids.
    explanation: The functional findings do not establish the proposed protective mechanism.
genetic:
- name: CTLA4
  gene_term:
    preferred_term: CTLA4
    term:
      id: hgnc:2505
      label: CTLA4
  relationship_type: SUSCEPTIBILITY
  subtype: Type 1
  association: Exploratory common-variant associations in 59 Japanese AIP cases and 102 controls; the +6230 comparison had nominal P=0.011 but corrected P=0.055. Small relapse-genotype analyses require independent replication.
  notes: The study did not show that the associated genotype caused the measured soluble CTLA4 elevation. Background HLA findings and an unrelated sequence-variant cohort are not evidence for CTLA4 function.
  evidence:
  - reference: PMID:18341485
    reference_title: Association of autoimmune pancreatitis with cytotoxic T-lymphocyte antigen 4 gene polymorphisms in Japanese patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Our findings suggest that AIP is associated with a genetic polymorphism in CTLA4 and is positively correlated with serum sCTLA4 levels.
    explanation: Exploratory association statement; the full paper has corrected P=0.055 for the +6230 case-control comparison and does not show genotype-mediated soluble-protein elevation.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:18341485
    reference_title: Association of autoimmune pancreatitis with cytotoxic T-lymphocyte antigen 4 gene polymorphisms in Japanese patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The +49A/A and +6230A/A genotypes were associated with an enhanced risk of relapse (OR 5.45, P= 0.038 and OR 12.66, P= 0.022).
    explanation: Human association result; this study does not establish a causal pancreatic signaling mechanism.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: HLA-DRB1
  gene_term:
    preferred_term: HLA-DRB1
    term:
      id: hgnc:4948
      label: HLA-DRB1
  relationship_type: SUSCEPTIBILITY
  subtype: Type 1
  association: HLA-DRB1 region and imputed amino-acid associations in a Japanese IgG4-related disease GWAS of 835 cases and 1,789 controls. The cohort was not restricted to pancreatic disease.
  notes: Association and HLA imputation do not establish a unique causal allele, autoantigen or pancreatic antigen-presentation mechanism.
  evidence:
  - reference: PMID:38229354
    reference_title: 'IgG4-related disease in the Japanese population: a genome-wide association study.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: We identified the HLA-DRB1 (p=1·1×10-11) and FCGR2B (p=2·0×10-8) regions as susceptibility loci for IgG4-related disease.
    explanation: Human association result; this study does not establish a causal pancreatic signaling mechanism.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:38229354
    reference_title: 'IgG4-related disease in the Japanese population: a genome-wide association study.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: We also identified crucial aminoacid residues in the β domain of the peptide-binding groove of HLA-DRB1, in which the seventh aminoacid residue showed the strongest association signal with IgG4-related disease
    explanation: Human association result; this study does not establish a causal pancreatic signaling mechanism.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: FCGR2B
  gene_term:
    preferred_term: FCGR2B
    term:
      id: hgnc:3618
      label: FCGR2B
  relationship_type: SUSCEPTIBILITY
  subtype: Type 1
  association: FCGR2B-region association in the same Japanese IgG4-related disease GWAS; associated expression and clinical correlates are not direct functional perturbation evidence.
  notes: Neither Mendelian inheritance nor an AIP-specific penetrance estimate follows from this systemic disease association.
  evidence:
  - reference: PMID:38229354
    reference_title: 'IgG4-related disease in the Japanese population: a genome-wide association study.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: rs1340976 in FCGR2B showed an association with increased FCGR2B expression (p=2·7×10-10) and was in weak linkage disequilibrium with rs1050501, a missense variant of FCGR2B previously associated with systemic lupus erythematosus.
    explanation: Human association result; this study does not establish a causal pancreatic signaling mechanism.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:38229354
    reference_title: 'IgG4-related disease in the Japanese population: a genome-wide association study.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Furthermore, rs1340976 was associated with the number of swollen organs at diagnosis (p=0.011) and IgG4 concentration at diagnosis (p=0.035).
    explanation: Human association result; this study does not establish a causal pancreatic signaling mechanism.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: P2RX3
  gene_term:
    preferred_term: P2RX3
    term:
      id: hgnc:8534
      label: P2RX3
  relationship_type: SUSCEPTIBILITY
  subtype: Type 1
  association: Exploratory sequence-variant association in a small Japanese candidate-gene study of 27 cases and 30 controls.
  notes: The controls were substantially younger; 1,031 candidate genes were screened. No independent replication or disease-specific functional assay establishes a causal pathway from this finding. The reported c.195delG is a single-base deletion (11/27 cases versus 0/30 controls), not a copy-number deletion of the gene.
  evidence:
  - reference: PMID:28955865
    reference_title: A high-throughput sequence analysis of Japanese patients revealed 11 candidate genes associated with type 1 autoimmune pancreatitis susceptibility.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Polymorphisms of CACNA1S (c.4642C>T), rs41554316, rs2231119, rs1042131, rs2838171, P2RX3 (c.195delG), rs75639061, SMAD7 (c.624delC) and TOP1 (c.2007delG), were identified as candidate genetic variants in patients with type 1 AIP.
    explanation: Candidate sequence-variant association, not proof of a pathogenic molecular mechanism.
  - reference: PMID:28955865
    reference_title: A high-throughput sequence analysis of Japanese patients revealed 11 candidate genes associated with type 1 autoimmune pancreatitis susceptibility.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: A total of 27 type 1 AIP patients and 30 healthy blood donors were recruited, and DNA samples were isolated from their mononuclear cells.
    explanation: Small Japanese candidate-gene cohort.
- name: TOP1
  gene_term:
    preferred_term: TOP1
    term:
      id: hgnc:11986
      label: TOP1
  relationship_type: SUSCEPTIBILITY
  subtype: Type 1
  association: Exploratory sequence-variant association in a small Japanese candidate-gene study of 27 cases and 30 controls.
  notes: The controls were substantially younger; 1,031 candidate genes were screened. No independent replication or disease-specific functional assay establishes a causal pathway from this finding. The reported c.2007delG is a single-base deletion (12/27 cases versus 0/30 controls), not a copy-number deletion of the gene.
  evidence:
  - reference: PMID:28955865
    reference_title: A high-throughput sequence analysis of Japanese patients revealed 11 candidate genes associated with type 1 autoimmune pancreatitis susceptibility.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Polymorphisms of CACNA1S (c.4642C>T), rs41554316, rs2231119, rs1042131, rs2838171, P2RX3 (c.195delG), rs75639061, SMAD7 (c.624delC) and TOP1 (c.2007delG), were identified as candidate genetic variants in patients with type 1 AIP.
    explanation: Candidate sequence-variant association, not proof of a pathogenic molecular mechanism.
  - reference: PMID:28955865
    reference_title: A high-throughput sequence analysis of Japanese patients revealed 11 candidate genes associated with type 1 autoimmune pancreatitis susceptibility.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: A total of 27 type 1 AIP patients and 30 healthy blood donors were recruited, and DNA samples were isolated from their mononuclear cells.
    explanation: Small Japanese candidate-gene cohort.
- name: FCRL3
  gene_term:
    preferred_term: FCRL3
    term:
      id: hgnc:18506
      label: FCRL3
  relationship_type: SUSCEPTIBILITY
  subtype: Type 1
  association: Exploratory FCRL3 promoter -110 A/A genotype association in 59 Japanese AIP cases, 62 chronic calcifying pancreatitis controls and 97 healthy controls. The A/A comparison with healthy controls was nominally significant, whereas the comparison with chronic pancreatitis was not.
  notes: This small candidate-gene study predates contemporary subtype criteria; 55 of 59 cases had high serum IgG4. Table 1 reports an A/A genotype association, not a significant overall A-allele-frequency association. The broad confidence interval, multiple tested polymorphisms and absence of an independent replication limit interpretation. Correlation with IgG4 concentration does not demonstrate altered FCRL3 function or causal mediation. The authors explicitly allow linkage to a neighboring gene. PMID18341485 mentions this earlier study as background; the direct primary report is PMID16905709.
  evidence:
  - reference: PMID:16905709
    reference_title: Genetic association of Fc receptor-like 3 polymorphisms with autoimmune pancreatitis in Japanese patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: The test group consisted of 59 patients with autoimmune pancreatitis, 62 patients with chronic calcifying pancrea- titis, and 97 unrelated Japanese controls.
    explanation: Primary study denominator; the generated two-page PDF also contains unrelated adjacent letters, which are not used.
  - reference: PMID:16905709
    reference_title: Genetic association of Fc receptor-like 3 polymorphisms with autoimmune pancreatitis in Japanese patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: 'There are two possible explanations for these findings: FCRL32110 may be functionally linked with susceptibility to autoimmune pancreatitis, or this allele may be a linkage marker for a neighbouring unidentified susceptibility gene on chromo- some 1q 21. No other alleles were found to be significantly associated with autoimmune pancreatitis.'
    explanation: The authors distinguish direct functional susceptibility from linkage and do not perform a functional assay.
  - reference: PMID:16905709
    reference_title: Genetic association of Fc receptor-like 3 polymorphisms with autoimmune pancreatitis in Japanese patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: 'Positivity for the 2110G allele was signifi- cantly decreased in autoimmune pancreatitis patients (p = 0.012, odds ratio 0.13; table 1), indicating a significant association of the 2110A/A genotype with autoimmune pan- creatitis. The frequency of 2110A/A alleles was significantly increased in patients with autoimmune pancreatitis compared with controls (p = 0.012, odds ratio = 7.45; table 1).'
    explanation: The reported susceptibility association concerns A/A genotype; Table 1 distinguishes this from the nonsignificant overall A-allele frequency and chronic-pancreatitis comparison.
environmental:
- name: Occupational history involving industrial dusts, vapors, gases and fumes
  description: Blue-collar work and job-exposure-matrix estimates were associated with IgG4-related cholangitis and/or type 1 AIP in a Dutch hospital-based case-control study. The exposure classification was derived from recalled work history rather than measured personal toxin concentrations. It does not establish a specific occupational cause of AIP.
  notes: The 101 cases were compared with 303 age-, sex- and hospital-matched digestive-disease controls. Selection, recall, correlated exposures and residual confounding limit causal interpretation. Composite matrix estimates cannot be assigned specifically to asbestos. No antigenic or cellular mediator, prevention effect or type 2 association was measured; no mechanistic target is inferred.
  evidence:
  - reference: PMID:34816110
    reference_title: Blue-collar work is a risk factor for developing IgG4-related disease of the biliary tract and pancreas.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Of cases with IgG4-RD, 68% (n = 69) ever performed a blue-collar job, compared to 39% of controls (n = 117, Fig. 2), corresponding to an OR of 3.66 (95% CI 2.18–6.13).
    explanation: Occupational-history association in 101 combined biliary/pancreatic IgG4-RD cases and 303 matched tertiary disease controls, not a pancreas-only or type 2 analysis.
treatments:
- name: Glucocorticoid induction for active type 1 disease
  description: Glucocorticoids are first-line induction for symptomatic active type 1 AIP and selected patients with persistent mass, cholestasis or threatened organ function. Assess clinical, biochemical and imaging response after two to four weeks and taper individually. Glucose control, infection risk and bone health require attention. Treating every asymptomatic patient solely to prevent later pancreatic insufficiency is not supported; nonresponse requires reassessment of the diagnosis.
  therapeutic_modality: SMALL_MOLECULE
  evidence:
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: There is no relevant data to support that a treatment should be proposed in patients with AIP without symptoms, just to limit the risk of exo- crine or endocrine insufﬁciencies. (GRADE 1C)
    explanation: GRADE 1C explicitly limits preventive treatment claims in asymptomatic disease.
    directness: DIRECT
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Treatment with glucocorticoids should be initiated in a weight-based manner at a dose of 0.6–0.8 mg/kg body weight/day orally (typical starting dose 30–40 mg/day prednisone equivalent) for 1 month to induce remission. Response to initial treat- ment should be assessed at week 2–4 with clinical, bio- chemical, and morphological markers. Glucocorticoid therapy should gradually be tapered by 5 mg every two weeks (tapering duration 3–6 months). (GRADE 1C)  # codespell:ignore ment
    explanation: GRADE 1C adult induction and response-monitoring recommendation; the statement specifies a three-to-six-month taper in the main body.
    directness: DIRECT
  - reference: PMID:28027896
    reference_title: International consensus for the treatment of autoimmune pancreatitis.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: 'CONCLUSION: The recommendations are based on the available evidence, and eastern and western experts'' opinions to find standard treatment of AIP worldwide.'
    explanation: Canonical identity and consensus nature of the 2017 treatment guideline.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: glucocorticoid
      term:
        id: CHEBI:24261
        label: glucocorticoid
  target_mechanisms:
  - target: Pancreatic Lymphoplasmacytic Infiltration
    treatment_effect: INHIBITS
    description: Glucocorticoids suppress the active inflammatory lesion; the responsible cellular mediators are not resolved by clinical response.
    evidence:
    - reference: PMID:28365915
      reference_title: Autoimmune Pancreatitis.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Initial treatment of both AIP and IDCP is with oral corticosteroids for duration of 4 weeks followed by a gradual taper.
      explanation: Review supports corticosteroid induction in both established subtypes.
- name: Glucocorticoids for symptomatic type 2 disease
  description: Type 2 AIP usually responds to a short induction course followed by taper. Many patients do not require maintenance because relapse is uncommon in published series; associated IBD treatment and recurrence require individual assessment. Spontaneous improvement has also been reported.
  therapeutic_modality: SMALL_MOLECULE
  evidence:
  - reference: PMID:34670874
    reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Type 2 AIP is a steroid-responsive disorder, and rapid improvements in symptoms and imaging abnormalities are expected within 2 or 3 weeks of the commencement of corticosteroids.6,7 Spontaneous regression without immunosuppression has also been documented. In contrast to type 1 AIP, in which relapse is relatively common (30% to 50%), disease relapse is uncommon in type 2 AIP (10%);6,7 therefore, maintenance therapy is unnecessary in most patients. The majority of patients with type 2 AIP present with features of acute pancreatitis (60%) or painless jaundice (30%).6,7 Episodes of acute pancreatitis in patients with type 2 AIP are clinically mild without the need for intensive care unit admission, the development of organ failure, or peripancreatic fluid collection.6 Other less common patterns of presentation include liver dysfunction, non-specific abdominal symptoms, and the incidental detection of a pancreatic mass on images taken for other purposes.
    explanation: Review summarizes rapid response and lower relapse frequency.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: glucocorticoid
      term:
        id: CHEBI:24261
        label: glucocorticoid
  target_mechanisms:
  - target: Neutrophilic Duct Infiltration
    treatment_effect: INHIBITS
    description: Treatment reduces type 2 pancreatic inflammation; clinical response does not establish a specific neutrophil mediator.
    evidence:
    - reference: PMID:34670874
      reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Type 2 AIP is a steroid-responsive disorder, and rapid improvements in symptoms and imaging abnormalities are expected within 2 or 3 weeks of the commencement of corticosteroids.6,7 Spontaneous regression without immunosuppression has also been documented. In contrast to type 1 AIP, in which relapse is relatively common (30% to 50%), disease relapse is uncommon in type 2 AIP (10%);6,7 therefore, maintenance therapy is unnecessary in most patients. The majority of patients with type 2 AIP present with features of acute pancreatitis (60%) or painless jaundice (30%).6,7 Episodes of acute pancreatitis in patients with type 2 AIP are clinically mild without the need for intensive care unit admission, the development of organ failure, or peripancreatic fluid collection.6 Other less common patterns of presentation include liver dysfunction, non-specific abdominal symptoms, and the incidental detection of a pancreatic mass on images taken for other purposes.
      explanation: Review summarizes rapid response and lower relapse frequency.
- name: Selective maintenance and relapse treatment
  description: Maintenance is selected according to relapse, organ involvement, response and toxicity, rather than being mandatory for every subtype. Re-induction with glucocorticoids may be appropriate. High-risk or relapsing type 1 disease may justify steroid-sparing therapy; optimal agent and duration are not established for every patient.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  evidence:
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Adding immunosuppressive agents should be considered in case of disease relapse as main- tenance of remission strategy, and in patients with a high risk of disease relapse, particularly in the case of multi-organ involvement. If there is no change in dis- ease activity or the disease relapsed during the 3 months of treatment (during glucocorticoid taper or discontinuation), then immunosuppressive drugs should be added. (GRADE 2C)
    explanation: GRADE 2C selective maintenance recommendation; lack of response also requires diagnostic reassessment.
    directness: DIRECT
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Rituximab should be considered if patients are resistant or intol- erant to high-dose glucocorticoids to maintain remis- sion or have failed to respond to immunosuppressive therapies. Dosing protocol (375 mg/m 2 body surface area) is used weekly for 4 weeks, followed by infusions every 2–3 months or at two 1000 mg infusions 15 days apart every 6 months. (GRADE 2A)
    explanation: GRADE 2A conditional rituximab recommendation, distinct from a randomized type 1 AIP-specific efficacy estimate.
    directness: DIRECT
- name: Azathioprine maintenance
  description: Azathioprine is used as a steroid-sparing maintenance option in selected relapsing type 1 disease. Evidence is principally observational and does not establish effective acute induction monotherapy or superiority over other agents. Myelosuppression, liver injury and drug-induced pancreatitis limit use.
  therapeutic_modality: SMALL_MOLECULE
  evidence:
  - reference: PMID:36293522
    reference_title: 'Autoimmune Pancreatitis: From Pathogenesis to Treatment.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Although there are no clinical trials on the use of AZA in AIP, its efficacy was investigated by Masaki et al. in a systematic review and meta-analysis; they found no AZA-treated patients naïve to corticosteroid treatment, but suggested the efficacy of AZA as maintenance therapy in patients with AIP who experience repeated relapses or are resistant to steroids.
    explanation: Review summarizes limitations of the maintenance evidence.
  - reference: PMID:36293522
    reference_title: 'Autoimmune Pancreatitis: From Pathogenesis to Treatment.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: It also examined which side effects occurred after AZA treatment; among them, pancreatitis, gastrointestinal symptoms, liver damage, severe leukopenia, and hair loss were the most common.
    explanation: Reported toxicity in the reviewed literature.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: azathioprine
      term:
        id: CHEBI:2948
        label: azathioprine
  target_mechanisms:
  - target: Pancreatic Lymphoplasmacytic Infiltration
    treatment_effect: INHIBITS
    description: Nonspecific immunosuppression supports maintenance of inflammatory remission.
    evidence:
    - reference: PMID:36293522
      reference_title: 'Autoimmune Pancreatitis: From Pathogenesis to Treatment.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: The efficacy of AZA and other immunomodulators depends on their ability to nonspecifically decrease B and T cell proliferation, which may be less effective than a therapeutic approach targeting Th2 cell response or regulatory T cell (Treg) activation [79].
      explanation: Proposed pharmacological route; no AIP-specific pathway assay.
- name: Mycophenolate mofetil as a steroid-sparing option
  description: Mycophenolate has been used in selected patients requiring maintenance or alternatives to other immunosuppression. Comparative AIP evidence is limited, and it is not an established superior first-line induction treatment.
  therapeutic_modality: SMALL_MOLECULE
  evidence:
  - reference: PMID:36293522
    reference_title: 'Autoimmune Pancreatitis: From Pathogenesis to Treatment.'
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: To avoid long-term side effects of glucocorticoid therapy, conventional glucocorticoid-sparing agents, including azathioprine, 6-mercaptopurine, mycophenolate mofetil, cyclosporine A, tacrolimus, methotrexate, cyclophosphamide, may be considered
    explanation: Review identifies the option and the limited comparative evidence.
  - reference: PMID:36293522
    reference_title: 'Autoimmune Pancreatitis: From Pathogenesis to Treatment.'
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Available data supporting the use of one agent over another are limited, but the use of azathioprine (2–2.5 mg/kg body weight) is generally recommended.
    explanation: Comparative maintenance evidence is limited.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: mycophenolate mofetil
      term:
        id: CHEBI:8764
        label: mycophenolate mofetil
  target_mechanisms:
  - target: Pancreatic Lymphoplasmacytic Infiltration
    treatment_effect: INHIBITS
    description: Steroid-sparing immunosuppression can help maintain inflammatory control.
    evidence:
    - reference: PMID:36293522
      reference_title: 'Autoimmune Pancreatitis: From Pathogenesis to Treatment.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: To avoid long-term side effects of glucocorticoid therapy, conventional glucocorticoid-sparing agents, including azathioprine, 6-mercaptopurine, mycophenolate mofetil, cyclosporine A, tacrolimus, methotrexate, cyclophosphamide, may be considered
      explanation: Review identifies the option and the limited comparative evidence.
    - reference: PMID:36293522
      reference_title: 'Autoimmune Pancreatitis: From Pathogenesis to Treatment.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: Available data supporting the use of one agent over another are limited, but the use of azathioprine (2–2.5 mg/kg body weight) is generally recommended.
      explanation: Comparative maintenance evidence is limited.
- name: Rituximab for relapsing or treatment-intolerant type 1 disease
  description: CD20-directed B-cell depletion is an option for resistant, relapsing or glucocorticoid-intolerant type 1 disease, or after failure of other immunosuppression. Most AIP-specific response estimates are from uncontrolled series. CD20-negative plasmablasts are not directly targeted; their decline is consistent with depletion of precursors. This is not a proven selective CTL therapy.
  therapeutic_modality: MONOCLONAL_ANTIBODY
  evidence:
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Rituximab should be considered if patients are resistant or intol- erant to high-dose glucocorticoids to maintain remis- sion or have failed to respond to immunosuppressive therapies. Dosing protocol (375 mg/m 2 body surface area) is used weekly for 4 weeks, followed by infusions every 2–3 months or at two 1000 mg infusions 15 days apart every 6 months. (GRADE 2A)
    explanation: GRADE 2A conditional rituximab recommendation, distinct from a randomized type 1 AIP-specific efficacy estimate.
    directness: DIRECT
  - reference: PMID:24817416
    reference_title: Plasmablasts as a biomarker for IgG4-related disease, independent of serum IgG4 concentrations.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: plasmablasts lack surface expression ofCD20 and are therefore resistant to direct depletion by anti-CD20 treatment approaches
    explanation: The authors distinguish mature B-cell depletion from indirect plasmablast effects.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Rituximab
      term:
        id: NCIT:C1702
        label: Rituximab
  target_mechanisms:
  - target: Plasmablast Expansion
    treatment_effect: INHIBITS
    description: Plasmablast counts can fall after precursor B-cell depletion; the effect on CD20-negative cells is indirect.
    evidence:
    - reference: PMID:24817416
      reference_title: Plasmablasts as a biomarker for IgG4-related disease, independent of serum IgG4 concentrations.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: PRIMARY_RESULT
      snippet: The steep decline in plasmablast counts after anti-CD20 treatment likely stems from the depletion of CD20+ precursors.
      explanation: Mechanistic interpretation of an uncontrolled treatment association.
- name: Inebilizumab for adult IgG4-related disease
  description: The anti-CD19 antibody is approved in the United States for adult IgG4-related disease. In MITIGATE, 135 adults with active disease and a history of at least two involved organs received inebilizumab or placebo with the same eight-week glucocorticoid taper. Treated adjudicated flares occurred in 7/68 versus 40/67 over 52 weeks (hazard ratio 0.13, 95% CI 0.06–0.28). The trial was not a comparison with rituximab, did not establish pancreas-only efficacy, and does not apply to type 2 or checkpoint-inhibitor pancreatic injury. Serious adverse events occurred in 12 versus six participants and serious or opportunistic infections in six versus two. Screen for hepatitis B and tuberculosis, review vaccinations and immunoglobulins, and monitor infections and hypogammaglobulinemia according to the label.
  therapeutic_modality: MONOCLONAL_ANTIBODY
  evidence:
  - reference: PMID:39541094
    reference_title: Inebilizumab for Treatment of IgG4-Related Disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Treatment with inebilizumab reduced flare risk; 7 participants (10%) in the inebilizumab group had at least one flare, as compared with 40 participants (60%) in the placebo group (hazard ratio, 0.13; 95% confidence interval [CI], 0.06 to 0.28; P<0.001).
    explanation: Primary randomized result.
  - reference: url:https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Journal_Club/2025/08_14.05.2025_N_Engl_J_Med_Stone_2025_Inebilizumab_for_Treatment_of_IgG4-Related_Disease_1168-77.pdf
    reference_title: https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Journal_Club/2025/08_14.05.2025_N_Engl_J_Med_Stone_2025_Inebilizumab_for_Treatment_of_IgG4-Related_Disease_1168-77.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Serious adverse events occurred during the treatment pe- riod in 12 of the participants (18%) who received inebilizumab and 6 of the par - ticipants (9%) who received placebo.
    explanation: Primary 52-week safety results.
  - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/761142s004lbl.pdf
    reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/761142s004lbl.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: 12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action The mechanism by which inebilizumab-cdon exerts its therapeutic effects in NMOSD, IgG4-RD, and gMG is presumed to involve binding to CD19, a cell surface antigen presents on pre-B and mature B lymphocytes. Following cell surface binding to B lymphocytes, inebilizumab-cdon results in antibody-dependent cellular cytolysis.
    explanation: Regulatory pharmacology describes CD19 binding and cytolysis.
  - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/761142s004lbl.pdf
    reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/761142s004lbl.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Monitor the levels of quantitative serum immunoglobulins during treatment with UPLIZNA, especially in patients with opportunistic or recurrent infections, and until B-cell repletion after discontinuation of therapy.
    explanation: Regulatory monitoring advice.
  - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/761142s004lbl.pdf
    reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/761142s004lbl.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: 1.2 Immunoglobulin G4-Related Disease (IgG4-RD) UPLIZNA is indicated for the treatment of Immunoglobulin G4-related disease (IgG4-RD) in adult patients.
    explanation: United States label indication.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Inebilizumab
      term:
        id: NCIT:C88283
        label: Inebilizumab
  target_mechanisms:
  - target: Plasmablast Expansion
    treatment_effect: INHIBITS
    description: CD19-directed depletion addresses a broader B-lineage compartment than CD20 targeting; clinical benefit does not identify a unique pathogenic B-cell function.
    evidence:
    - reference: PMID:40745228
      reference_title: '[Anti-CD19 treatment: the new gold standard for IgG4-related diseases].'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: Using CD19 as the therapeutic target addresses a broad spectrum of B cell differentiation including plasmablasts.
      explanation: Review describes the differentiation-stage scope; primary trial supports clinical efficacy.
- name: Anti-TNF therapy in selected relapsing type 2 disease
  description: Infliximab or adalimumab has been reported in a few relapsing or steroid-dependent type 2 cases, often with active IBD. This remains limited case-level evidence and does not establish routine use, a population response rate, or TNF as the proven driver of type 2 duct injury.
  therapeutic_modality: MONOCLONAL_ANTIBODY
  evidence:
  - reference: PMID:36293522
    reference_title: 'Autoimmune Pancreatitis: From Pathogenesis to Treatment.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The same study also described three cases of patients with active IBD and recurrent AIP treated with anti-TNF therapy. Two patients were treated with adalimumab and one with infliximab. Pancreatic symptoms were controlled by induction treatment with anti-TNF therapy only, and no maintenance treatment was required.
    explanation: Three cases with active IBD, in addition to an isolated case discussed in the source.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Infliximab
      term:
        id: NCIT:C1789
        label: Infliximab
    - preferred_term: Adalimumab
      term:
        id: NCIT:C65216
        label: Adalimumab
  target_mechanisms:
  - target: Neutrophilic Duct Infiltration
    treatment_effect: INHIBITS
    description: Reported clinical remission is linked indirectly to reduction of the type 2 inflammatory lesion; a TNF-dependent duct mechanism was not tested.
    evidence:
    - reference: PMID:36293522
      reference_title: 'Autoimmune Pancreatitis: From Pathogenesis to Treatment.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The same study also described three cases of patients with active IBD and recurrent AIP treated with anti-TNF therapy. Two patients were treated with adalimumab and one with infliximab. Pancreatic symptoms were controlled by induction treatment with anti-TNF therapy only, and no maintenance treatment was required.
      explanation: Three cases with active IBD, in addition to an isolated case discussed in the source.
- name: Selective biliary drainage
  description: Biliary drainage can relieve clinically significant obstruction, help prevent infection and permit cytology or brushing when malignancy is a concern. Mild jaundice without infection may improve with glucocorticoids alone; stenting is not mandatory for every patient.
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: Biliary Stenting
    term:
      id: NCIT:C62741
      label: Biliary Stenting
  evidence:
  - reference: url:https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
    reference_title: https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Consensus statements /C15 “Biliary drainage is useful to prevent biliary infection and use of brushing and cytology can differentiate IgG4-SC from biliary malignancy.
    explanation: International consensus level B recommendation.
  - reference: url:https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
    reference_title: https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: /C15 “In some cases of mild jaundice without signs of infection, ste- roid treatment alone can be performed safely without biliary stenting.
    explanation: Consensus identifies a selected no-stent option.
  target_mechanisms:
  - target: Obstructive jaundice
    treatment_effect: BYPASSES
    description: Drainage relieves biliary obstruction while the underlying inflammatory disease is treated.
    evidence:
    - reference: url:https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
      reference_title: https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: Consensus statements /C15 “Biliary drainage is useful to prevent biliary infection and use of brushing and cytology can differentiate IgG4-SC from biliary malignancy.
      explanation: International consensus level B recommendation.
    - reference: url:https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
      reference_title: https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: /C15 “In some cases of mild jaundice without signs of infection, ste- roid treatment alone can be performed safely without biliary stenting.
      explanation: Consensus identifies a selected no-stent option.
- name: Diabetes management during pancreatic treatment
  description: Assess and optimize glucose control before induction and during follow-up. Glucocorticoids can improve pancreatitis-associated dysfunction in some patients while causing or worsening hyperglycemia in others; pancreatic diabetes and pre-existing metabolic diabetes require individualized management.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: url:https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
    reference_title: https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Description The Japanese clinical guidelines recommend biliary drainage with biopsy or cytology in patients with obstructive jaundice, and control of blood glucose levels in patients with diabetes mellitus before steroid induction therapy [13].
    explanation: Consensus recommends glucose control before steroid induction.
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: However, there is a subset of patients exhibiting diabe- tes mellitus before AIP type 1 onset (33%) and a subset of patients developing or exacerbating diabetes mellitus as a complication of glucocorticoid treatment.
    explanation: Guideline identifies glucocorticoid-associated worsening.
  target_mechanisms:
  - target: Diabetes mellitus
    treatment_effect: MODULATES
    description: Individualized diabetes care addresses hyperglycemia; it is not evidence that all pancreatic endocrine injury is reversible.
    evidence:
    - reference: url:https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
      reference_title: https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: Description The Japanese clinical guidelines recommend biliary drainage with biopsy or cytology in patients with obstructive jaundice, and control of blood glucose levels in patients with diabetes mellitus before steroid induction therapy [13].
      explanation: Consensus recommends glucose control before steroid induction.
    - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: However, there is a subset of patients exhibiting diabe- tes mellitus before AIP type 1 onset (33%) and a subset of patients developing or exacerbating diabetes mellitus as a complication of glucocorticoid treatment.
      explanation: Guideline identifies glucocorticoid-associated worsening.
- name: Long-term pancreatic and systemic follow-up
  description: Follow type 1 disease for pancreatic or extrapancreatic relapse, exocrine and endocrine dysfunction, nutrition, bone health and treatment toxicity. Lifelong follow-up is advised by the European guideline, with frequency individualized to disease and treatment. Conflicting cancer-risk cohorts do not establish a proven AIP-specific cancer-imaging interval.
  therapeutic_modality: OTHER
  action_category: MONITORING
  evidence:
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Life-long follow-up of patients with AIP type 1 is advisable. (GRADE 2C; strong agreement)
    explanation: GRADE 2C lifelong follow-up recommendation.
    directness: DIRECT
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Screening for a deﬁciency of fat- soluble vitamins (A, D, E, and K), zinc, calcium, and magnesium should be considered in line with UEG evidence-based guidelines for the diagnosis and therapy of chronic pancreatitis (HaPanEU). 54 (GRADE 2A; strong agreement)
    explanation: GRADE 2A nutritional screening guidance refers to chronic-pancreatitis recommendations.
    directness: DIRECT
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: However, these data might be inﬂu- enced by a bias due to a more careful surveillance of patients with IgG4-related disease or AIP. Thus, future prospective studies are required to analyse the inci- dence of cancer in patients with IgG4-related disease compared to age-, sex-, and risk factor-matched con- trol subjects.
    explanation: The guideline explicitly qualifies the observational cancer-risk evidence.
    directness: DIRECT
- name: Surgery for selected unresolved lesions or complications
  description: Pancreatic surgery is not routine treatment for a medically responsive inflammatory lesion. It may be considered for persistent diagnostic uncertainty about malignancy or selected refractory complications after multidisciplinary assessment; resection carries pancreatic functional consequences.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: Surgical Procedure
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  evidence:
  - reference: url:https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
    reference_title: https://www.darmzentrum-bern.ch/fileadmin/darmzentrum/Education/Bible_Class/2020/Hereditary-autoimmune_pancreatitis/BC_2020-02-12_RW_International_consensus_paper_on__treatment_of_autoimmune_pancreatitis_2017.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Although medical treatment should be more preferable to surgical intervention, surgical intervention may be an option in cases of poor response to medical treatment, in which long-term biliary stenting is necessary due to continuous obstructive jaundice.
    explanation: Pancreas-specific consensus discussion of refractory obstruction.
  - reference: PMID:39169289
    reference_title: 'Prevalence of autoimmune pancreatitis in pancreatic resection for suspected malignancy: a systematic review and meta-analysis.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: 8917 pancreatic resections were performed because of a clinical suspicion of pancreatic cancer. AIP accounted for 140 cases (1.6%).
    explanation: Selected surgical series illustrate the cancer-mimic problem, not a general misdiagnosis rate.
- name: Pancreatic enzyme replacement for exocrine insufficiency
  description: Use pancreatic enzyme replacement when exocrine insufficiency is established, with administration during meals and adjustment to meal content, symptoms and nutritional response. This supplements digestion and does not treat the pancreatic immune lesion. The AGA advice is general EPI guidance, not an AIP-specific randomized efficacy estimate. A response to empiric enzymes alone is not a reliable diagnostic test.
  therapeutic_modality: PROTEIN_REPLACEMENT
  evidence:
  - reference: PMID:37737818
    reference_title: 'AGA Clinical Practice Update on the Epidemiology, Evaluation, and Management of Exocrine Pancreatic Insufficiency: Expert Review.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: 'BEST PRACTICE ADVICE 10: Once EPI is diagnosed, treatment with pancreatic enzyme replacement therapy (PERT) is required. If EPI is left untreated, it will result in complications related to fat malabsorption and malnutrition, having a negative impact on quality of life.'
    explanation: Expert best-practice advice for established EPI.
  - reference: url:https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf
    reference_title: https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: PERT treats the meal, not the pancreas. Thus, it must be taken during the meal to maximize mixing and digestion of nutrients.72,73 Humans have other mechanisms for protein and carbohydrate digestion, but not fats, 1 so the focus of PERT is on lipase dose and meal fat content.
    explanation: The full guideline explains replacement at the digestive level.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Pancrelipase
      term:
        id: NCIT:C29345
        label: Pancrelipase
  target_mechanisms:
  - target: Exocrine pancreatic insufficiency
    treatment_effect: BYPASSES
    description: Exogenous enzymes compensate for inadequate delivery of pancreatic digestive enzymes.
    evidence:
    - reference: PMID:37737818
      reference_title: 'AGA Clinical Practice Update on the Epidemiology, Evaluation, and Management of Exocrine Pancreatic Insufficiency: Expert Review.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: 'BEST PRACTICE ADVICE 10: Once EPI is diagnosed, treatment with pancreatic enzyme replacement therapy (PERT) is required. If EPI is left untreated, it will result in complications related to fat malabsorption and malnutrition, having a negative impact on quality of life.'
      explanation: Expert best-practice advice for established EPI.
    - reference: url:https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf
      reference_title: https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: PERT treats the meal, not the pancreas. Thus, it must be taken during the meal to maximize mixing and digestion of nutrients.72,73 Humans have other mechanisms for protein and carbohydrate digestion, but not fats, 1 so the focus of PERT is on lipase dose and meal fat content.
      explanation: The full guideline explains replacement at the digestive level.
- name: Nutrition and deficiency management
  description: For patients with exocrine insufficiency, assess weight, muscle status and fat-soluble vitamins, provide dietitian-guided support and replace documented or expected deficiencies. Avoid unnecessarily severe fat restriction. Monitor bone health and treatment toxicity according to the individual risk profile; this is supportive EPI care rather than proof that AIP inflammation has remitted.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Dietary Intervention
    term:
      id: NCIT:C15447
      label: Dietary Intervention
  evidence:
  - reference: PMID:37737818
    reference_title: 'AGA Clinical Practice Update on the Epidemiology, Evaluation, and Management of Exocrine Pancreatic Insufficiency: Expert Review.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: 'BEST PRACTICE ADVICE 13: Routine supplementation and monitoring of fat-soluble vitamin levels are appropriate. Dietary modifications include a low-moderate fat diet with frequent smaller meals and avoiding very-low-fat diets.'
    explanation: General EPI nutrition advice.
  - reference: url:https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf
    reference_title: https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Once EPI is diagnosed, a multidisciplinary evaluation is helpful to establish the state of the patient ’s digestive and endocrine systems.
    explanation: Full guideline describes nutritional and endocrine assessment.
  target_mechanisms:
  - target: Weight loss
    treatment_effect: MODULATES
    description: Nutritional support addresses inadequate intake or maldigestion-associated weight loss.
    evidence:
    - reference: url:https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf
      reference_title: https://bspghan.org.uk/wp-content/uploads/2023/11/aga-practice-guideline-exocrine-pancreatic-insufficiency.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: 1,66 This includes a dietary assessment from a certi ﬁed dietitian, if available, to determine nutri- tional needs and speci ﬁcd eﬁcits (eg, vitamins A, D, E, K, and B12, selenium, unintentional weight loss, protein balance, and caloric needs) plus dietary adjustments based on needs and comorbidities (eg, diabetes mellitus, dyslipidemia, celiac disease, CFTR-related disorder, prior surgery, and cancer therapy).  # codespell:ignore certi
      explanation: General EPI dietary assessment explicitly includes unintentional weight loss and caloric needs.
diagnosis:
- name: Comprehensive type 1 AIP assessment and exclusion of malignancy
  description: Assess pancreatic morphology, histology, serum IgG4, other-organ involvement and carefully interpreted treatment response together. Neither serum IgG4 nor CA19-9 alone establishes AIP or excludes pancreatic cancer. A focal mass requires an appropriate malignancy work-up; steroid response is one contextual criterion, not independent proof of benign disease. This guideline addresses type 1 AIP unless stated otherwise.
  evidence:
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: For these guidelines, AIP is referring to AIP type 1, i.e. IgG4-related autoimmune pancreatitis, unless speciﬁed otherwise.
    explanation: Defines the type 1 scope of this guideline.
    directness: DIRECT
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: IgG4 serum level alone lacks sensitivity and speciﬁcity, but can be helpful to estab- lish the diagnosis, and therefore should be measured if IgG4-related gastrointestinal disease is suspected. (GRADE 2C; strong agreement)
    explanation: 'GRADE 2C recommendation: IgG4 is an adjunct, not a stand-alone diagnostic test.'
    directness: DIRECT
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: There are no speciﬁc clinical features or blood tests that can differentiate between IgG4-related disease and cancer. (GRADE 2B; strong agreement)
    explanation: Clinical or laboratory findings alone cannot distinguish IgG4 disease from cancer; interpret within the full work-up.
    directness: DIRECT
  - reference: PMID:32552502
    reference_title: European Guideline on IgG4-related digestive disease - UEG and SGF evidence-based recommendations.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: IgG4-related digestive disease can be diagnosed only with a comprehensive work-up that includes histology, organ morphology at imaging, serology, search for other organ involvement, and response to glucocorticoid treatment.
    explanation: Canonical identity of the European guideline; full guideline details are cited above.
- name: Pancreatic imaging and endoscopic tissue acquisition
  description: CT or MRI can identify diffuse or focal enlargement, a peripancreatic rim and duct narrowing, but imaging may overlap with malignancy. EUS supplies detailed imaging and tissue acquisition. Core histology helps assess architectural features and distinguish focal AIP from cancer; sampling error limits a negative biopsy, and IgG4-positive cells alone are insufficient. The pediatric exception to routine pretreatment biopsy is not generalized to adult masses.
  evidence:
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: The classical imaging features of AIP are paren- chymal enlargement, ‘sausage-like’ shape, peripancre- atic edematous rim, and main pancreatic duct narrowing without upstream dilatation. These features may be diffuse or focal but can also be highly variable. (GRADE 2C; strong agreement)
    explanation: GRADE 2C describes suggestive, variable imaging features.
    directness: DIRECT
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Endoscopic ultrasound (EUS) provides pancreatic imaging ﬁndings suggestive of AIP and is used for obtaining tissue samples for the histo- logical diagnosis of the disease. (GRADE 2B; strong agreement)
    explanation: GRADE 2B supports EUS for imaging and histological sampling.
    directness: DIRECT
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: In biopsy specimens, distinguishing IgG4-related disease and cancer is more challenging. Risk of sampling error should be considered in a neg- ative biopsy. Non-speciﬁc inﬂammation, with increased IgG4-positive cells can occur in both cancer and IgG4- related disease. (GRADE 2C; strong agreement)  # codespell:ignore ative
    explanation: Sampling error and nonspecific IgG4 infiltration limit biopsy interpretation.
    directness: DIRECT
- name: Histological subtype assessment
  diagnosis_term:
    preferred_term: Histopathologic Examination
    term:
      id: NCIT:C18190
      label: Histopathologic Examination
  description: Assess the distribution of inflammation, storiform fibrosis, obliterative phlebitis and IgG4-positive plasma cells for type 1. For type 2, assess granulocytic epithelial lesions, with scant IgG4-positive cells and the clinical IBD context. Peritumoral or ordinary acute pancreatitis can also contain neutrophils, so a few cells do not independently establish type 2. Some IBD-associated cases meet probable criteria without diagnostic histology; this does not apply to every patient with a steroid-responsive mass.
  evidence:
  - reference: PMID:29512140
    reference_title: Autoimmune Pancreatitis Mouse Model.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Type 1 AIP (also called LPSP) is characterized by dense lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis. This is accompanied by massive accumulation of IgG4-expressing plasma cells and, in some patients with elevated levels of serum IgG4 and involvement of other organs, including bile ducts, salivary glands, and kidney.
    explanation: Clinical pathological synthesis of type 1 AIP.
  - reference: PMID:34670874
    reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: In contrast to type 1 AIP, the diagnosis of which may be established without biopsy, type 2 AIP generally requires the tissue confirmation of neutrophilic infiltration into the ducts or acini.15 Without histology, type 2 AIP cannot be diagnosed in patients without history of IBD, even if they show typical imaging features and good response to corticosteroids.
    explanation: Histology and IBD jointly determine the diagnostic pathway.
  - reference: PMID:34670874
    reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Another caveat is that neutrophilic infiltration in the duct epithelium or lobules can be focally detected in peritumoral pancreatitis.
    explanation: Nonspecific or peritumoral neutrophils limit interpretation.
- name: CA19-9 and serum IgG4 as adjuncts
  description: Neither marker independently distinguishes AIP from pancreatic ductal adenocarcinoma. Interpret CA19-9 with cholestasis, imaging and tissue findings; use IgG4 as one component of the diagnostic framework. A meta-analysis of resected suspected cancers found IgG4 positivity in 21/49 tested type 1 cases, a highly selected subgroup rather than a general sensitivity estimate.
  evidence:
  - reference: PMID:39169289
    reference_title: 'Prevalence of autoimmune pancreatitis in pancreatic resection for suspected malignancy: a systematic review and meta-analysis.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: The sensitivity of IgG4 levels in type 1 AIP was low (43%, 21/49 patients).
    explanation: The denominator is tested, resected cases.
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: 'Statement 8.2.1: There are no speciﬁc clinical features or blood tests that can differentiate between IgG4-related disease and cancer.'
    explanation: Guideline emphasizes overlap with cancer.
- name: Contextual assessment of glucocorticoid response
  description: An appropriately supervised response assessment may contribute to a composite diagnosis after a malignancy work-up. Improvement is not independent proof that a lesion is benign; steroid treatment can obscure histology and some peritumoral inflammation also responds. Persistent or recurrent nonresponse warrants diagnostic reassessment.
  evidence:
  - reference: PMID:34670874
    reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: However, a steroid trial needs to be considered with caution because various conditions, including peritumoral pancreatitis, potentially respond to immunosuppression. Pancreatic biopsy needs to be considered before a steroid trial, which veils pathognomonic histological changes.
    explanation: Response has diagnostic limitations.
- name: Pancreatic exocrine and endocrine function assessment
  description: Assess glucose control and symptoms or laboratory evidence of exocrine insufficiency at diagnosis and follow-up. Fecal elastase is a practical initial exocrine test, interpreted with stool consistency and the clinical context. These functional tests assess complications and do not distinguish AIP from cancer.
  evidence:
  - reference: PMID:37737818
    reference_title: 'AGA Clinical Practice Update on the Epidemiology, Evaluation, and Management of Exocrine Pancreatic Insufficiency: Expert Review.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: 'BEST PRACTICE ADVICE 4: Fecal elastase test is the most appropriate initial test and must be performed on a semi-solid or solid stool specimen.'
    explanation: General PEI expert advice, applicable to established pancreatic dysfunction rather than an AIP-specific diagnostic validation.
  - reference: url:https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    reference_title: https://www.europeanpancreaticclub.org/media/resources/IgG4_Related_Digestive_Disease.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Life-long follow-up of patients with AIP type 1 is advisable. (GRADE 2C; strong agreement)
    explanation: GRADE 2C lifelong follow-up recommendation.
    directness: DIRECT
animal_models:
- species: Mouse
  genotype: MRL/Mp with induced autoimmune pancreatitis
  description: The induced model develops pancreatic infiltrates, acinar architectural damage and fibrosis. Depletion of pDCs or IFNAR blockade before induction exposures reduces inflammatory pathology. A later study reported increased SLAMF7-positive CD8 cells and dexamethasone-associated improvement; these are mouse CD8 cells, not the human CD4 population. The model does not reproduce endogenous human IgG4 production, and reported fibrosis is not necessarily the diagnostic storiform pattern.
  evidence:
  - reference: PMID:29512140
    reference_title: Autoimmune Pancreatitis Mouse Model.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    quote_role: REVIEW_SYNTHESIS
    snippet: Although mice lack the IgG4 Ab subtype, autoimmune-prone MRL/Mp mice treated with repeated injection with polyinosinic-polycytidylic acid (poly (I:C)) provide an experimental model of AIP. These mice exhibit massive destruction of pancreatic architecture associated with pancreatic immune cell infiltration and fibrosis.
    explanation: Protocol synthesis describes the model and the absent mouse IgG4 subclass.
  - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
    reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    snippet: In addition, such depletion of pDCs prevented AIP development as assessed by pathological analysis (Fig. 2B) and reductions in the numbers of inﬁltrating T cells, B cells, and CD11b + macrophages in the pancreas (Fig. 2C).
    explanation: Preventive pDC depletion reduced experimental pancreatic inflammatory pathology.
  - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
    reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    snippet: We found that such treatment of MRL/Mp mice inhibited AIP development to about the same extent as pDC depletion (Fig. 3A) and coincided with the fact that the number of pDCs in the pan- creas was also signiﬁcantly reduced, indicating that type I IFN production is involved in the pancreatic accumulation of pDCs (Fig. 3B).
    explanation: Type-I-IFN receptor blockade attenuated disease during induction; it was not a treatment trial after established fibrosis.
  - reference: PMID:37661465
    reference_title: Increased SLAMF7(+)CD8(+) T cells are associated with the pathogenesis of experimental autoimmune pancreatitis in mice.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    snippet: SLAMF7+CD8+ T cells were elevated in the spleen and pancreas of AIP mice.
    explanation: Abstract-supported mouse subset observation.
  modeled_mechanisms:
  - target: Plasmacytoid Dendritic Cell Activation
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: CELLULAR
    description: Depletion reduces pancreatic pDC-associated inflammation.
    limitations: Disease is induced by a synthetic innate stimulus in an autoimmune-prone strain. Preventive depletion/blockade does not identify the initiating human antigen or establish treatment of established human disease. Mice lack endogenous IgG4; shared inflammatory findings remain informative, but human IgG4 production is not reproduced.
    evidence:
    - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
      reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      snippet: In addition, such depletion of pDCs prevented AIP development as assessed by pathological analysis (Fig. 2B) and reductions in the numbers of inﬁltrating T cells, B cells, and CD11b + macrophages in the pancreas (Fig. 2C).
      explanation: Preventive pDC depletion reduced experimental pancreatic inflammatory pathology.
    readouts:
    - name: Pancreatic inflammation after pDC depletion
      target: Plasmacytoid Dendritic Cell Activation
      direction: DECREASED
      interpretation: Depletion reduces pancreatic pDC-associated inflammation.
      evidence:
      - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
        reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
        supports: SUPPORT
        directness: DIRECT
        evidence_source: MODEL_ORGANISM
        quote_role: PRIMARY_RESULT
        snippet: In addition, such depletion of pDCs prevented AIP development as assessed by pathological analysis (Fig. 2B) and reductions in the numbers of inﬁltrating T cells, B cells, and CD11b + macrophages in the pancreas (Fig. 2C).
        explanation: Preventive pDC depletion reduced experimental pancreatic inflammatory pathology.
  - target: Type I Interferon Production
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: CELLULAR
    description: IFNAR blockade attenuates inflammatory disease during induction.
    limitations: Disease is induced by a synthetic innate stimulus in an autoimmune-prone strain. Preventive depletion/blockade does not identify the initiating human antigen or establish treatment of established human disease. Mice lack endogenous IgG4; shared inflammatory findings remain informative, but human IgG4 production is not reproduced.
    evidence:
    - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
      reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      snippet: We found that such treatment of MRL/Mp mice inhibited AIP development to about the same extent as pDC depletion (Fig. 3A) and coincided with the fact that the number of pDCs in the pan- creas was also signiﬁcantly reduced, indicating that type I IFN production is involved in the pancreatic accumulation of pDCs (Fig. 3B).
      explanation: Type-I-IFN receptor blockade attenuated disease during induction; it was not a treatment trial after established fibrosis.
    readouts:
    - name: Pancreatic pathology with IFNAR blockade
      target: Type I Interferon Production
      direction: DECREASED
      interpretation: IFNAR blockade attenuates inflammatory disease during induction.
      evidence:
      - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
        reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
        supports: SUPPORT
        directness: DIRECT
        evidence_source: MODEL_ORGANISM
        quote_role: PRIMARY_RESULT
        snippet: We found that such treatment of MRL/Mp mice inhibited AIP development to about the same extent as pDC depletion (Fig. 3A) and coincided with the fact that the number of pDCs in the pan- creas was also signiﬁcantly reduced, indicating that type I IFN production is involved in the pancreatic accumulation of pDCs (Fig. 3B).
        explanation: Type-I-IFN receptor blockade attenuated disease during induction; it was not a treatment trial after established fibrosis.
  - target: Storiform Fibrosis
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    model_scale: TISSUE
    description: The model develops pancreatic fibrosis, without establishing the specifically storiform architecture.
    limitations: Disease is induced by a synthetic innate stimulus in an autoimmune-prone strain. Preventive depletion/blockade does not identify the initiating human antigen or establish treatment of established human disease. Mice lack endogenous IgG4; shared inflammatory findings remain informative, but human IgG4 production is not reproduced.
    evidence:
    - reference: PMID:29512140
      reference_title: Autoimmune Pancreatitis Mouse Model.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      quote_role: REVIEW_SYNTHESIS
      snippet: Although mice lack the IgG4 Ab subtype, autoimmune-prone MRL/Mp mice treated with repeated injection with polyinosinic-polycytidylic acid (poly (I:C)) provide an experimental model of AIP. These mice exhibit massive destruction of pancreatic architecture associated with pancreatic immune cell infiltration and fibrosis.
      explanation: Protocol synthesis describes the model and the absent mouse IgG4 subclass.
    readouts:
    - name: Pancreatic fibrosis
      target: Storiform Fibrosis
      direction: INCREASED
      interpretation: The model develops pancreatic fibrosis, without establishing the specifically storiform architecture.
      evidence:
      - reference: PMID:29512140
        reference_title: Autoimmune Pancreatitis Mouse Model.
        supports: SUPPORT
        directness: DIRECT
        evidence_source: MODEL_ORGANISM
        quote_role: REVIEW_SYNTHESIS
        snippet: Although mice lack the IgG4 Ab subtype, autoimmune-prone MRL/Mp mice treated with repeated injection with polyinosinic-polycytidylic acid (poly (I:C)) provide an experimental model of AIP. These mice exhibit massive destruction of pancreatic architecture associated with pancreatic immune cell infiltration and fibrosis.
        explanation: Protocol synthesis describes the model and the absent mouse IgG4 subclass.
- species: Mouse
  genotype: Neonatal male BALB/c recipients of human immunoglobulin
  description: Passive transfer of patient IgG caused pancreatic and salivary injury. Both IgG1 and IgG4 fractions caused injury, with greater destruction from IgG1; simultaneous IgG4 reduced IgG1-associated injury. This published experiment replaces the former proposal that subclass-resolved testing had not been done. The accessible abstract does not establish a universal human mechanism, identify every antigen, or show that selective IgG4 removal would be beneficial.
  evidence:
  - reference: PMID:26964842
    reference_title: Pathogenicity of IgG in patients with IgG4-related disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    snippet: 'RESULTS: Subcutaneous injection of patient IgG, but not control IgG, resulted in pancreatic and salivary gland injuries. Pancreatic injury was also induced by injecting patient IgG1 or IgG4, with more destructive changes induced by IgG1 than by IgG4. The potent pathogenic activity of patient IgG1 was significantly inhibited by simultaneous injection of patient IgG4.'
    explanation: Human IgG passive transfer into neonatal mice; abstract-supported scope.
  modeled_mechanisms:
  - target: Acinar Tissue Injury
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: TISSUE
    description: Patient immunoglobulin fractions induce pancreatic tissue injury in neonatal recipients.
    limitations: Passive transfer bypasses immune initiation and does not reproduce the chronic human systemic syndrome. The full methods were not retrievable; no unsupported dose, denominator or mechanistic mediator is inferred.
    evidence:
    - reference: PMID:26964842
      reference_title: Pathogenicity of IgG in patients with IgG4-related disease.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      snippet: 'RESULTS: Subcutaneous injection of patient IgG, but not control IgG, resulted in pancreatic and salivary gland injuries. Pancreatic injury was also induced by injecting patient IgG1 or IgG4, with more destructive changes induced by IgG1 than by IgG4. The potent pathogenic activity of patient IgG1 was significantly inhibited by simultaneous injection of patient IgG4.'
      explanation: Human IgG passive transfer into neonatal mice; abstract-supported scope.
    readouts:
    - name: Pancreatic injury after patient immunoglobulin
      target: Acinar Tissue Injury
      direction: INCREASED
      interpretation: Patient immunoglobulin fractions induce pancreatic tissue injury in neonatal recipients.
      evidence:
      - reference: PMID:26964842
        reference_title: Pathogenicity of IgG in patients with IgG4-related disease.
        supports: SUPPORT
        directness: DIRECT
        evidence_source: MODEL_ORGANISM
        quote_role: PRIMARY_RESULT
        snippet: 'RESULTS: Subcutaneous injection of patient IgG, but not control IgG, resulted in pancreatic and salivary gland injuries. Pancreatic injury was also induced by injecting patient IgG1 or IgG4, with more destructive changes induced by IgG1 than by IgG4. The potent pathogenic activity of patient IgG1 was significantly inhibited by simultaneous injection of patient IgG4.'
        explanation: Human IgG passive transfer into neonatal mice; abstract-supported scope.
- species: Mouse
  genotype: MRL/Mp and MRL/Mp-Fas induced pancreatitis; NOD comparison models
  description: CFTR corrector C18 reduced pancreatic inflammatory injury in MRL/Mp mice and partially restored calcium influx in isolated pancreatic acini. Responses varied in the more severe MRL/Mp-Fas model. Broader salivary-gland experiments used VX770 and ductal CFTR gene transfer; the gene-transfer rescue was salivary, not pancreatic. These results nominate a preclinical duct-function strategy, not established AIP treatment.
  evidence:
  - reference: PMID:28634110
    reference_title: Restoration of CFTR Activity in Ducts Rescues Acinar Cell Function and Reduces Inflammation in Pancreatic and Salivary Glands of Mice.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    snippet: Figure 4e shows that treatment with C18 reduced the pancreatic damage and infiltration of T cells and neutrophils in MRL/Mp mice.
    explanation: C18 effect in the MRL/Mp pancreatic experiment.
  - reference: PMID:28634110
    reference_title: Restoration of CFTR Activity in Ducts Rescues Acinar Cell Function and Reduces Inflammation in Pancreatic and Salivary Glands of Mice.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: Significantly, treatment with C18 partially restored Ca2+ influx in NOD and MRL/Mp acinar cells (Figure 6d) and Ca2+ oscillations in NOD pancreatic acini (Fig.
    explanation: Restoration was measured in isolated pancreatic acini after mouse treatment.
  modeled_mechanisms:
  - target: Acinar Tissue Injury
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: TISSUE
    description: C18 treatment reduces pancreatic injury and partially restores measured acinar calcium responses.
    limitations: Small mouse experiments, variable strain responses and post-treatment isolated-cell assays. No human AIP trial or pancreatic gene-transfer rescue was performed; accelerated CFTR degradation was proposed rather than directly measured.
    evidence:
    - reference: PMID:28634110
      reference_title: Restoration of CFTR Activity in Ducts Rescues Acinar Cell Function and Reduces Inflammation in Pancreatic and Salivary Glands of Mice.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      snippet: Figure 4e shows that treatment with C18 reduced the pancreatic damage and infiltration of T cells and neutrophils in MRL/Mp mice.
      explanation: C18 effect in the MRL/Mp pancreatic experiment.
    readouts:
    - name: Pancreatic injury after C18
      target: Acinar Tissue Injury
      direction: DECREASED
      interpretation: C18 treatment reduces pancreatic injury and partially restores measured acinar calcium responses.
      evidence:
      - reference: PMID:28634110
        reference_title: Restoration of CFTR Activity in Ducts Rescues Acinar Cell Function and Reduces Inflammation in Pancreatic and Salivary Glands of Mice.
        supports: SUPPORT
        directness: DIRECT
        evidence_source: MODEL_ORGANISM
        quote_role: PRIMARY_RESULT
        snippet: Figure 4e shows that treatment with C18 reduced the pancreatic damage and infiltration of T cells and neutrophils in MRL/Mp mice.
        explanation: C18 effect in the MRL/Mp pancreatic experiment.
clinical_trials:
- name: NCT04540497
  phase: PHASE_III
  status: ACTIVE_NOT_RECRUITING
  description: 'MITIGATE: phase 3 randomized, double-blind inebilizumab versus placebo in 135 adults with active IgG4-related disease, with matched glucocorticoid taper. The 52-week randomized comparison has been published; the registry remains active, not recruiting for extended follow-up. The population had multiorgan disease history and was not an AIP-only cohort.'
  evidence:
  - reference: clinicaltrials:NCT04540497
    reference_title: A Phase 3, Randomized, Double-blind, Multicenter, Placebo Controlled Study of Inebilizumab Efficacy and Safety in IgG4-Related Disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: This study aims to evaluate the efficacy and safety of inebilizumab for the prevention of flare of Immunoglobulin G4-related disease (IgG4-RD).
    explanation: The registration record establishing the trial's identity and objective. Graded OTHER because a registry entry is a registration document rather than study evidence.
    quote_role: BACKGROUND
    directness: DIRECT
  - reference: PMID:39541094
    reference_title: Inebilizumab for Treatment of IgG4-Related Disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Treatment with inebilizumab reduced flare risk; 7 participants (10%) in the inebilizumab group had at least one flare, as compared with 40 participants (60%) in the placebo group (hazard ratio, 0.13; 95% confidence interval [CI], 0.06 to 0.28; P<0.001).
    explanation: Published primary result is distinct from registry status.
  notes: Registry status was checked against the live ClinicalTrials.gov record on 2026-09-21. No direct comparison with rituximab or demonstrated reversal of established pancreatic fibrosis was tested. The regulatory adult IgG4-related disease indication does not extend this trial result to type 2 AIP.
discussions:
- discussion_id: aip_smoking_endocrine_association
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: Does smoking independently modify endocrine outcomes in established type 1 AIP?
  attaches_to:
  - phenotypes#Diabetes mellitus
  rationale: A retrospective cohort of 59 patients with established type 1 AIP associated smoking with prevalent diabetes at AIP diagnosis. It had no non-AIP comparison group and does not estimate smoking-related risk of developing AIP. The follow-up association was borderline, and occupation lost its baseline diabetes association after adjustment for smoking. These observations do not establish a pancreatic causal mechanism or a benefit from a tested smoking-cessation intervention.
  evidence:
  - reference: PMID:35807009
    reference_title: 'Exocrine and Endocrine Insufficiency in Autoimmune Pancreatitis: A Matter of Treatment or Time?'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: At multivariable analysis, smoking (OR = 4.92; 95% CI 1.22–19.9) and obstructive jaundice (OR = 9.47; 95% CI 2.06–43.5) were strongly associated with the presence of DM at diagnosis of AIP
    explanation: The outcome is diabetes within an AIP cohort, not AIP occurrence.
  - reference: PMID:35807009
    reference_title: 'Exocrine and Endocrine Insufficiency in Autoimmune Pancreatitis: A Matter of Treatment or Time?'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: After an adjustment for smoking, the association between blue-collar professions and DM at diagnosis lost statistical significance.
    explanation: Smoking and occupation are not demonstrated independent causal pathways.
- discussion_id: aip_subtype_boundary
  kind: CONTROVERSY
  prompt: How should established AIP subtypes be distinguished from checkpoint-inhibitor pancreatic injury?
  attaches_to:
  - has_subtypes#Type 1
  - has_subtypes#Type 2
  rationale: Type 1 and type 2 share some imaging appearances and glucocorticoid responsiveness but differ in histology, systemic associations and relapse. Immune-checkpoint-inhibitor pancreatic injury has been proposed as type 3, but it is a drug-associated spectrum with variable biochemical and clinical definitions, limited tissue series and uncertain steroid benefit. It is kept as a diagnostic boundary rather than assumed to share the established type 1 or type 2 pathways.
  evidence:
  - reference: PMID:34670874
    reference_title: 'Type 2 Autoimmune Pancreatitis: Consensus and Controversies.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Although type 2 AIP shares some features with type 1 AIP, these two conditions are distinct without any overlaps.5 Table 1 summarizes the features of two types of AIP.
    explanation: Review of established subtype distinctions.
  - reference: PMID:41922528
    reference_title: 'Immune checkpoint inhibitor-related pancreatitis: a comprehensive review of epidemiology, pathophysiology, and management.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The advent of ICI therapy has introduced a distinct form of immune-mediated pancreatic injury, which some investigators have proposed designating as type 3 autoimmune pancreatitis [7–9].
    explanation: Recent review discusses a proposed drug-associated category.
- discussion_id: aip_igg4_marker_or_mediator
  kind: KNOWLEDGE_GAP
  prompt: Which immunoglobulin functions contribute to human pancreatic injury?
  attaches_to:
  - pathophysiology#Increased IgG4 Secretion
  - pathophysiology#Acinar Tissue Injury
  rationale: IgG4 enrichment is neither proof of a single pathogenic effector nor proof of a harmless marker. Published neonatal-mouse transfer experiments found injury with both patient IgG1 and IgG4, greater injury with IgG1 and attenuation when IgG4 accompanied IgG1. Antigen, tissue context, subclass composition and chronic human immune initiation remain unresolved. B-cell depletion efficacy does not identify which antibody or antigen-presentation function mediates benefit.
  evidence:
  - reference: PMID:26964842
    reference_title: Pathogenicity of IgG in patients with IgG4-related disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    snippet: 'RESULTS: Subcutaneous injection of patient IgG, but not control IgG, resulted in pancreatic and salivary gland injuries. Pancreatic injury was also induced by injecting patient IgG1 or IgG4, with more destructive changes induced by IgG1 than by IgG4. The potent pathogenic activity of patient IgG1 was significantly inhibited by simultaneous injection of patient IgG4.'
    explanation: Human IgG passive transfer into neonatal mice; abstract-supported scope.
- discussion_id: aip_human_causal_scope
  kind: KNOWLEDGE_GAP
  prompt: Which experimental immune pathways are necessary in human type 1 AIP?
  attaches_to:
  - pathophysiology#Plasmacytoid Dendritic Cell Activation
  - pathophysiology#CD4+SLAMF7+ Cytotoxic T Lymphocyte Expansion
  rationale: Preventive mouse pDC/IFNAR interventions, human coculture perturbations and systemic IgG4-RD T-cell assays support candidate mechanisms at different scales. The small human CTL study included ten pancreatic cases among 18 systemic cases; bulk tissue TCR overlap in two patients cannot prove the identity of every pancreatic infiltrating cell. Cytokine secretion and nonpancreatic target killing do not establish the entire CTL-to-pancreatic-fibrosis route. IgG4 output does not resolve class switching, BAFF necessity or the initiating human NET stimulus.
  evidence:
  - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
    reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: In addition, inhibition of NET formation by DNase or blockade of IFN- a–mediated signaling pathways by anti-IFNAR Ab signiﬁcantly reduced IgG4 production in a coculture system comprised of control B cells, patient-derived neutrophils, and patient-derived pDCs (Fig. 7C).
    explanation: DNase and IFNAR blockade reduced IgG4 secretion in a defined human coculture; intervening signals remain unresolved.
  - reference: PMID:26971690
    reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: These CD4+ SLAMF7+ T cells cells have potent cytolytic function; upon in vitro stimulation with anti-CD3, these cells undergo degranulation as inferred from the surface expression of CD107a (Fig 2, D) and exhibit cytotoxic activity against allogeneic EBV-transformed B cell targets (Fig 2, E and Fig E6).
    explanation: The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.
  - reference: PMID:29499100
    reference_title: A CD8α- Subset of CD4+SLAMF7+ Cytotoxic T Cells Is Expanded in Patients With IgG4-Related Disease and Decreases Following Glucocorticoid Treatment.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Eighteen patients (11 male, 7 female) with a mean age of 64 years (range, 47-83 years) were included in the study (Table 1).
    explanation: Small systemic cohort scope.
- discussion_id: aip_long_term_risk
  kind: KNOWLEDGE_GAP
  prompt: How do treatment and disease activity affect long-term pancreatic function and cancer risk?
  attaches_to:
  - phenotypes#Exocrine pancreatic insufficiency
  - phenotypes#Diabetes mellitus
  rationale: Published cohorts differ in selection, testing completeness, therapy and follow-up. Associations of maintenance steroids with relapse or survival are not randomized estimates, while steroids can improve or worsen glucose control. A selected decade-long cohort had only two pancreatic cancers and broad confidence intervals; neither a proven excess risk nor a universal cancer-surveillance interval follows. Shorter type 2 series and biopsy-dependent ascertainment further limit cross-subtype prognosis comparisons.
  evidence:
  - reference: PMID:42185503
    reference_title: 'A decade of clinical course and prognostic determinants in type 1 autoimmune pancreatitis: insights from a 10-year longitudinal multicenter retrospective study.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Overall malignancy risk was not increased (SIR 1.00; 95%CI 0.59-1.42), while pancreatic cancer (PC) showed a numerically higher SIR (1.98 overall; 2.96 ≥ 5 years postdiagnosis).
    explanation: Imprecise pancreatic-cancer estimate.
  - reference: PMID:35807009
    reference_title: 'Exocrine and Endocrine Insufficiency in Autoimmune Pancreatitis: A Matter of Treatment or Time?'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: No strong association was found between pharmacological treatment and occurrence of PEI and DM.
    explanation: Observational treatment comparisons do not show absence of any benefit.
notes: Type 1 AIP is the pancreatic manifestation of systemic IgG4-related disease; this entry also retains the distinct type 2 duct-centric disorder. Systemic IgG4-RD cohorts and treatment trials are identified explicitly, rather than treated as pancreas-only evidence. Hospital survey rates and feature frequencies depend on diagnostic criteria and assessed denominators. URL-cached primary papers are identified by their canonical PMID in the bibliography or accompanying evidence; the European guideline is PMID:32552502, the 2017 international treatment consensus PMID:28027896, the MITIGATE report PMID:39541094, the 2021 Japanese survey PMID:42154026 and the NET/pDC study PMID:26297761.
experimental_models:
- name: Human NET, pDC and B-cell coculture
  experimental_model_type: PRIMARY_CELL_CULTURE
  cell_source: Patient or control blood pDCs and neutrophils combined with healthy-control B cells
  publication: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
  description: Defined cultures compare patient and control cell sources and use induced NET-containing preparations. Patient pDCs promote IFN-alpha and IgG4 output; DNase and IFNAR blockade reduce output. The human study enrolled 20 patients, but tissue, serum and culture subsets differ. Tissue controls included tumor-free cancer-resection sections. The experiments do not prove that MSU or patient anti-lactoferrin IgG4 initiates disease, and no BAFF-neutralization experiment isolates that mediator.
  evidence:
  - reference: PMID:26297761
    reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs.
    explanation: Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.
  - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
    reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: In addition, inhibition of NET formation by DNase or blockade of IFN- a–mediated signaling pathways by anti-IFNAR Ab signiﬁcantly reduced IgG4 production in a coculture system comprised of control B cells, patient-derived neutrophils, and patient-derived pDCs (Fig. 7C).
    explanation: DNase and IFNAR blockade reduced IgG4 secretion in a defined human coculture; intervening signals remain unresolved.
  modeled_mechanisms:
  - target: Type I Interferon Production
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: MOLECULAR
    description: Patient-pDC cultures show enhanced IFN-alpha output.
    limitations: The B cells are healthy-control cells; extracellular DNA and receptor-blockade effects do not identify a universal human initiating antigen.
    evidence:
    - reference: PMID:26297761
      reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs.
      explanation: Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.
    readouts:
    - name: Culture IFN-alpha
      target: Type I Interferon Production
      direction: INCREASED
      interpretation: Patient-pDC cultures show enhanced IFN-alpha output.
      evidence:
      - reference: PMID:26297761
        reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
        supports: SUPPORT
        directness: INDIRECT
        evidence_source: IN_VITRO
        quote_role: PRIMARY_RESULT
        snippet: More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs.
        explanation: Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.
  - target: Increased IgG4 Secretion
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: MOLECULAR
    description: NET-containing patient-pDC cultures increase IgG4 secretion, which falls with DNase or IFNAR blockade.
    limitations: Secretion cannot distinguish de novo class switching from expansion of a pre-existing IgG4 B-cell subset. BAFF necessity is untested.
    evidence:
    - reference: PMID:26297761
      reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs.
      explanation: Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.
    - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
      reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: In addition, inhibition of NET formation by DNase or blockade of IFN- a–mediated signaling pathways by anti-IFNAR Ab signiﬁcantly reduced IgG4 production in a coculture system comprised of control B cells, patient-derived neutrophils, and patient-derived pDCs (Fig. 7C).
      explanation: DNase and IFNAR blockade reduced IgG4 secretion in a defined human coculture; intervening signals remain unresolved.
    readouts:
    - name: Culture IgG4 secretion
      target: Increased IgG4 Secretion
      direction: INCREASED
      interpretation: NET-containing patient-pDC cultures increase IgG4 secretion, which falls with DNase or IFNAR blockade.
      evidence:
      - reference: PMID:26297761
        reference_title: Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis.
        supports: SUPPORT
        directness: INDIRECT
        evidence_source: IN_VITRO
        quote_role: PRIMARY_RESULT
        snippet: More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs.
        explanation: Patient pDCs were studied with NETs and healthy-control B cells. This culture does not distinguish new class switching from expansion of pre-existing IgG4-secreting cells.
      - reference: url:https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
        reference_title: https://www.med.kindai.ac.jp/life/files/h27/kudou/018.pdf
        supports: SUPPORT
        directness: INDIRECT
        evidence_source: IN_VITRO
        quote_role: PRIMARY_RESULT
        snippet: In addition, inhibition of NET formation by DNase or blockade of IFN- a–mediated signaling pathways by anti-IFNAR Ab signiﬁcantly reduced IgG4 production in a coculture system comprised of control B cells, patient-derived neutrophils, and patient-derived pDCs (Fig. 7C).
        explanation: DNase and IFNAR blockade reduced IgG4 secretion in a defined human coculture; intervening signals remain unresolved.
- name: Patient-derived CD4 cytotoxic T-cell assays
  experimental_model_type: PRIMARY_CELL_CULTURE
  cell_source: Sorted and expanded blood CD4-positive SLAMF7-positive cells from systemic IgG4-related disease patients
  publication: PMID:26971690
  description: Expanded patient cells degranulate and kill allogeneic EBV-transformed B-cell targets after stimulation, and secrete processed IL-1beta and TGF-beta1. The overall clinical cohort had 101 IgG4-RD patients, with 18.8% pancreatic involvement; individual culture assays use smaller subsets. No pancreatic epithelial-target killing, selective pathway rescue or fibroblast-collagen assay establishes a complete human pancreatic fibrosis sequence.
  evidence:
  - reference: PMID:26971690
    reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: These CD4+ SLAMF7+ T cells cells have potent cytolytic function; upon in vitro stimulation with anti-CD3, these cells undergo degranulation as inferred from the surface expression of CD107a (Fig 2, D) and exhibit cytotoxic activity against allogeneic EBV-transformed B cell targets (Fig 2, E and Fig E6).
    explanation: The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.
  - reference: PMID:26971690
    reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: Upon in vitro stimulation, flow sorted CD4+ CTLs secreted large amounts of TGF-β1 compared to the naïve CD4+ cells from the same patients (Fig 5, E).
    explanation: TGF-beta1 secretion was measured after stimulation of sorted patient cells.
  - reference: PMID:26971690
    reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: The expanded CD4+ CTLs retained their SLAMF7 expression and cytotoxic markers and were found to secrete the processed form (17 kDa) of IL-1β upon re-stimulation with either anti-CD3 or LPS as determined by Western blot analysis of culture supernatants (Fig 5, D).
    explanation: Processed IL-1beta was measured in stimulated culture supernatants.
  modeled_mechanisms:
  - target: CD4 T Cell Cytolytic Activity
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: CELLULAR
    description: Expanded cells exhibit cytolytic function against allogeneic B-cell targets.
    limitations: Target-cell and stimulation context differ from a pancreatic lesion; antigen specificity and pancreatic necessity remain unresolved.
    evidence:
    - reference: PMID:26971690
      reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: These CD4+ SLAMF7+ T cells cells have potent cytolytic function; upon in vitro stimulation with anti-CD3, these cells undergo degranulation as inferred from the surface expression of CD107a (Fig 2, D) and exhibit cytotoxic activity against allogeneic EBV-transformed B cell targets (Fig 2, E and Fig E6).
      explanation: The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.
    readouts:
    - name: Target-cell killing
      target: CD4 T Cell Cytolytic Activity
      direction: INCREASED
      interpretation: Expanded cells exhibit cytolytic function against allogeneic B-cell targets.
      evidence:
      - reference: PMID:26971690
        reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
        supports: SUPPORT
        directness: DIRECT
        evidence_source: IN_VITRO
        quote_role: PRIMARY_RESULT
        snippet: These CD4+ SLAMF7+ T cells cells have potent cytolytic function; upon in vitro stimulation with anti-CD3, these cells undergo degranulation as inferred from the surface expression of CD107a (Fig 2, D) and exhibit cytotoxic activity against allogeneic EBV-transformed B cell targets (Fig 2, E and Fig E6).
        explanation: The targets were allogeneic EBV-transformed B cells; pancreatic epithelial killing was not tested.
  - target: TGF-Beta1 Secretion by CD4 T Cells
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: MOLECULAR
    description: Stimulated patient cells secrete TGF-beta1.
    limitations: Cytokine output is measured; pancreatic fibrosis mediation is not.
    evidence:
    - reference: PMID:26971690
      reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: Upon in vitro stimulation, flow sorted CD4+ CTLs secreted large amounts of TGF-β1 compared to the naïve CD4+ cells from the same patients (Fig 5, E).
      explanation: TGF-beta1 secretion was measured after stimulation of sorted patient cells.
    readouts:
    - name: Supernatant TGF-beta1
      target: TGF-Beta1 Secretion by CD4 T Cells
      direction: INCREASED
      interpretation: Stimulated patient cells secrete TGF-beta1.
      evidence:
      - reference: PMID:26971690
        reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
        supports: SUPPORT
        directness: DIRECT
        evidence_source: IN_VITRO
        quote_role: PRIMARY_RESULT
        snippet: Upon in vitro stimulation, flow sorted CD4+ CTLs secreted large amounts of TGF-β1 compared to the naïve CD4+ cells from the same patients (Fig 5, E).
        explanation: TGF-beta1 secretion was measured after stimulation of sorted patient cells.
  - target: Interleukin-1-Beta Secretion by CD4 T Cells
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: MOLECULAR
    description: Stimulated expanded cells release processed IL-1beta.
    limitations: The processed cytokine was detected in culture; selective in-vivo necessity is untested.
    evidence:
    - reference: PMID:26971690
      reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: The expanded CD4+ CTLs retained their SLAMF7 expression and cytotoxic markers and were found to secrete the processed form (17 kDa) of IL-1β upon re-stimulation with either anti-CD3 or LPS as determined by Western blot analysis of culture supernatants (Fig 5, D).
      explanation: Processed IL-1beta was measured in stimulated culture supernatants.
    readouts:
    - name: Processed IL-1beta in supernatant
      target: Interleukin-1-Beta Secretion by CD4 T Cells
      direction: INCREASED
      interpretation: Stimulated expanded cells release processed IL-1beta.
      evidence:
      - reference: PMID:26971690
        reference_title: Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease.
        supports: SUPPORT
        directness: DIRECT
        evidence_source: IN_VITRO
        quote_role: PRIMARY_RESULT
        snippet: The expanded CD4+ CTLs retained their SLAMF7 expression and cytotoxic markers and were found to secrete the processed form (17 kDa) of IL-1β upon re-stimulation with either anti-CD3 or LPS as determined by Western blot analysis of culture supernatants (Fig 5, D).
        explanation: Processed IL-1beta was measured in stimulated culture supernatants.
- name: H69 cholangiocyte autoantigen perturbation
  experimental_model_type: CELL_LINE
  cell_source: Human H69 cholangiocytes with gene knockdown, inhibitors, recombinant proteins or donor immunoglobulin
  publication: PMID:38332916
  description: Parallel galectin-3 and prohibitin perturbations measured intracellular pH, bile-acid permeation and apoptosis. Results were discordant across interventions and did not establish a consistent protective autoantigen mechanism. The final IgG comparison used one IgG4-related cholangitis donor and one healthy donor and did not increase bile-acid uptake. This is a biliary epithelial experiment, not a pancreatic model or a germline variant assay.  # codespell:ignore prohibitin
  evidence:
  - reference: PMID:38332916
    reference_title: Galectin-3 and prohibitin 1 are autoantigens in IgG4-related cholangitis without clear-cut protective effects against toxic bile acids.  # codespell:ignore prohibitin
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: These parallel approaches did not demonstrate clear-cut protective effects in three assays that touch on the functionality of the biliary bicarbonate umbrella (23, 24), including intracellular pH measurements, toxic bile acid permeation studies, and experiments determining GCDC-induced cholangiocyte apoptosis.
    explanation: The paper limits its own functional interpretation.
  - reference: PMID:38332916
    reference_title: Galectin-3 and prohibitin 1 are autoantigens in IgG4-related cholangitis without clear-cut protective effects against toxic bile acids.  # codespell:ignore prohibitin
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: In line with these findings, pretreatment with IgGs isolated from an IRC patient with anti-galectin-3 and anti-prohibitin 1 autoantibodies did not lead to increased GCDC permeation into cholangiocytes.  # codespell:ignore prohibitin
    explanation: One patient-donor antibody preparation did not increase toxic bile-acid entry.
review_notes: The review consumed every baseline reference at the fullest retrievable level, all available full scientific bodies and relevant deep-research leads. The 2016 survey cache had an incorrectly attached 2021 full paper and was regenerated through the sanctioned fetcher as the correct 2016 abstract; the 2021 paper is cited separately. Experimental evidence now distinguishes preventive murine interventions, patient-cell culture and human observations. Remaining primary abstracts, including the passive-transfer and 2023 SLAMF7 mouse reports, are not represented as full-methods audits. The decade-long cohort contains a diabetes numerator discrepancy and uses albumin as a nonspecific nutritional marker; neither is converted into a precise functional mechanism. The exocrine-insufficiency cohort has changing assessed denominators and an inconsistent summary-table cohort size. The 2021 survey organ counts use 2,819 assessed patients, and its maintenance proportion is among initial steroid recipients. Detailed evidence limitations are retained at the affected claims. The FCRL3 primary report is PMID16905709, not the later CTLA4 paper that cites it. CACNA1S and SMAD7 remain among the
  exploratory candidates named in the sequence-panel evidence, without inferred functional mechanisms or a claim that the genetic list exhausts that panel. Fibrotic-module conformance is not asserted because the current evidence measures T-cell TGF-beta1 secretion and a histological fibrotic pattern but does not establish the complete myofibroblast activation and matrix-turnover chain required by that module. Composite diagnostic strategies are not narrowed to a single imaging or laboratory procedure; the discrete histological assessment is specifically bound.
references:
- reference: PMID:32809604
  title: Autoimmune Pancreatitis.
  tags:
  - StatPearls

📚

References & Deep Research

References

PMID:32809604

Autoimmune Pancreatitis.

No top-level findings curated for this source.

Deep Research

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Evaluations and curation notes (3)

Record review notes

The review consumed every baseline reference at the fullest retrievable level, all available full scientific bodies and relevant deep-research leads. The 2016 survey cache had an incorrectly attached 2021 full paper and was regenerated through the sanctioned fetcher as the correct 2016 abstract; the 2021 paper is cited separately. Experimental evidence now distinguishes preventive murine interventions, patient-cell culture and human observations. Remaining primary abstracts, including the passive-transfer and 2023 SLAMF7 mouse reports, are not represented as full-methods audits. The decade-long cohort contains a diabetes numerator discrepancy and uses albumin as a nonspecific nutritional marker; neither is converted into a precise functional mechanism. The exocrine-insufficiency cohort has changing assessed denominators and an inconsistent summary-table cohort size. The 2021 survey organ counts use 2,819 assessed patients, and its maintenance proportion is among initial steroid recipients. Detailed evidence limitations are retained at the affected claims. The FCRL3 primary report is PMID16905709, not the later CTLA4 paper that cites it. CACNA1S and SMAD7 remain among the exploratory candidates named in the sequence-panel evidence, without inferred functional mechanisms or a claim that the genetic list exhausts that panel. Fibrotic-module conformance is not asserted because the current evidence measures T-cell TGF-beta1 secretion and a histological fibrotic pattern but does not establish the complete myofibroblast activation and matrix-turnover chain required by that module. Composite diagnostic strategies are not narrowed to a single imaging or laboratory procedure; the discrete histological assessment is specifically bound.

Review autoimmune pancreatitis mechanisms, subtype scope, diagnosis and treatment evidence · 2026-09-21T14:11:53Z · View source

Comprehensive review of the complete entry, every inherited cited source, the matching deep-research report and citation set, and the full clinical baseline in StatPearls and the European and international consensus guidelines. Actual full scientific bodies, available tables, methods and figure captions were consumed, including the immune-cell studies, mouse interventions, candidate-gene studies, pancreatic-function cohorts, Japanese surveys, MITIGATE trial, 2025 FDA label and general exocrine-insufficiency guidance. Independent readers audited the cytotoxic-T-cell and NET/pDC studies and the integrated mechanism and clinical-care sections. Rebuilt twenty atomic mechanisms separating systemic type 1 IgG4-related disease from type 2 duct-centric neutrophilic disease, measured cell and antibody observations from inferred mediators, and acinar from endocrine-islet injury. Human immune-cell cohorts are not automatically pancreatic cohorts. Preventive mouse interventions, neonatal antibody transfer, isolated-cell results and salivary gene transfer retain their actual species, timing, tissue and readout limits. IgG4 secretion does not establish de novo class switching, peripheral cytotoxic markers do not prove pancreatic killing, and IFNAR blockade does not isolate interferon-alpha from beta. The already published antibody-transfer experiment replaces an inherited proposal to perform it. Expanded eleven clinical findings, six diagnostic records, fourteen care entries, three animal and three experimental models, one trial and four interpretive discussions. Added contemporary Japanese population estimates with response and denominator limits, selected-cohort relapse and functional-outcome data, and distinct extrapancreatic involvement. Corrected candidate single-base indels previously described as gene copy-number associations; retained the corrected CTLA4 significance and untested functional mediation. Autoantibody targets are biochemical observations rather than germline disease genes. Neither a proposed checkpoint-inhibitor subtype nor uncertain pancreatic cancer risk is promoted to an established causal pathway. Care now distinguishes induction, selective maintenance, limited steroid-sparing evidence, type 2 anti-TNF case reports, cancer exclusion, selective drainage, pancreatic enzyme replacement and nutritional follow-up. The randomized inebilizumab result is systemic IgG4-related disease with matched glucocorticoid taper, not a pancreas-only or type 2 trial, a rituximab comparison or proof of fibrosis reversal. The current US indication and safety restrictions are retained. Guideline recommendations and clinical response do not directly measure histological depletion; their corresponding treatment-target evidence is graded indirect. A regenerated PMID31872350 cache had incorrectly attached the different 2021 survey to the 2016 publication. Sanctioned abstract-only regeneration restored the correct bibliographic identity, while the actual 2021 full paper is separately cited. All cache changes were produced by fetch-reference; no cache was hand-edited and the frozen dataset-accession blob was neither read nor modified. Authoritative schema, live ontology, cached-quote validation and repository guards accompany the review.

Create: Autoimmune Pancreatitis · 2026-09-06T09:49:08Z · View source

New Disease entry for MONDO:0006122, curated from an OpenScientist deep-research report plus primary literature. 61/61 evidence snippets verified against the committed reference cache, drawn from 16 sources. Architecture. Three has_subtypes (Type 1 IgG4-related, Type 2 idiopathic duct-centric, Type 3 immune-checkpoint-inhibitor-associated) over two parallel pathophysiology arms that meet only at the shared Tumefactive Pancreatic Mass node: the type 1 arm runs through oligoclonal plasmablast expansion, IgG4-positive lymphoplasmacytic infiltration and storiform fibrosis, the type 2 arm through granulocytic epithelial lesions and duct-centric neutrophilic destruction. That shared endpoint is why the two present alike and are separated on histology rather than imaging. Evidence base. A first draft of this entry was sourced entirely from four narrative reviews, with one review supplying 14 of 29 snippets. That was corrected before opening the PR by adding eight primary studies: - Three Japanese nationwide surveys (PMID:22466167, PMID:25815647, PMID:31872350) replacing a qualitative RARE record with numeric point prevalence and annual incidence. The measured prevalence rises from 2.2 to 4.6 to 10.1 per 100,000 across nine years; the entry records that rise but explicitly declines to read it as rising incidence, because the diagnostic criteria changed between surveys and EUS-FNA became routine over the same period. - A new progression section with two phases, covering the relapse trajectory from three cohorts that agree on shape and disagree on level (PMID:42185503, PMID:31872350, PMID:41223493), and long-term functional decline (PMID:35807009). The notes state why all three relapse estimates probably overstate population risk: each design excludes a different set of non-relapsing patients. - A new genetic section typing CTLA4 (hgnc:2505) as SUSCEPTIBILITY rather than causative, with the sample size, the absence of replication, and the imprecision of the relapse odds ratios stated in notes. Eleven further candidate genes from a 27-versus-30 NGS study are described in notes and deliberately not curated as entries. - A new animal_models section for the poly(I:C)/MRL-Mp model, with two ModelMechanismLinks and typed divergences. The SPECIES_MISMATCH divergence is marked INVALIDATING because mice have no IgG4 subclass at all, so the defining feature of the human lesion is structurally impossible in the model rather than merely unmeasured. - Diagnosis entries for serum CA 19-9 (a negative finding that is clinically load-bearing) and for the scale of misdiagnosis (PMID:39169289: AIP is 1.6% of resections for suspected cancer and 26% of resections that turn out unnecessary), plus the measured 43% sensitivity of serum IgG4 in that population. Curation changes. The bundled phenotype "Pancreatic exocrine and endocrine insufficiency" was split into two separately bound and separately quantified phenotypes (HP:0001738, HP:0000819) and the causal edge feeding it was retargeted to both. A truncated evidence quote on the extrapancreatic phenotype that ended mid-sentence at "including" was supplemented with a source that actually names the organ set. One discussion is recorded rather than resolved: aip_one_disease_or_two (CONTROVERSY) on whether type 1 and type 2 are subtypes of one disease or two diseases sharing a radiological presentation. Validated with just validate-disorders (61/61), just validate-terms, and the ungated whole-KB gates: snippet length, title snippets, snippet grading, folded hyphens, enum values, duplicate keys, entity refs, causal targets, qualifier terms, model-scale-audit --strict, check-not4curation.

OpenScientist ▸

Autoimmune Pancreatitis (MONDO:0015175): A Comprehensive Disease Characterization

openscientist-autonomous 42 citations 2026-09-06T09:21:35.958965

Autoimmune Pancreatitis (MONDO:0015175): A Comprehensive Disease Characterization

Summary

Autoimmune pancreatitis (AIP) is a rare, corticosteroid-responsive fibroinflammatory form of chronic pancreatitis that is now understood to comprise three immunologically distinct subtypes. Type 1 AIP — lymphoplasmacytic sclerosing pancreatitis (LPSP) — is the pancreatic manifestation of the systemic IgG4-related disease (IgG4-RD) and accounts for the large majority of cases (~94% of surgically confirmed AIP). It is defined by elevated serum IgG4, storiform fibrosis, obliterative phlebitis, dense IgG4+ plasma-cell infiltration, and frequent multi-organ (biliary, salivary/lacrimal, renal, retroperitoneal, aortic) involvement. Type 2 AIP — idiopathic duct-centric pancreatitis (IDCP) — is IgG4-negative, pancreas-restricted, histologically defined by the neutrophilic granulocytic epithelial lesion (GEL), and associated in ~one-third of cases with inflammatory bowel disease, especially ulcerative colitis. Type 3 AIP is a newly recognized, drug-induced entity triggered by immune-checkpoint-inhibitor (ICI) cancer immunotherapy.

Mechanistically, Type 1 AIP is driven by a self-sustaining loop between oligoclonally expanded CD4+SLAMF7+ cytotoxic T lymphocytes (CTLs) — which possess both direct cytotoxic and profibrotic properties — and B-lineage cells/plasmablasts that present antigen and differentiate into IgG4-secreting plasma cells. An upstream innate-immunity axis (neutrophil extracellular traps → plasmacytoid dendritic cells → IFN-α) drives IgG4-class switching and is necessary for disease in the principal MRL/Mp poly(I:C) mouse model. Type 2 AIP is instead neutrophil-centric, and Type 3 (ICI-related) is characterized by acinar-centric T-cell infiltration evolving from CD4+ to CD8+ predominance. Genetic susceptibility is polygenic/multifactorial (HLA-DRB1, FCGR2B, CTLA4, FCRL3) rather than Mendelian, and etiology combines genetic predisposition, environmental/occupational triggers (industrial fumes, asbestos), lifestyle factors (smoking), and — for Type 3 — drug exposure.

Clinically, AIP typically presents in older men (male:female ≈ 3:1; mean age ~65–68 in Japanese surveys) with painless obstructive jaundice and weight loss that mimic pancreatic cancer, making the distinction from malignancy the central diagnostic challenge. Diagnosis follows the ICDC or HISORt frameworks integrating histology, imaging, serology, other-organ involvement, and steroid response. Prognosis is favorable (~85% 10-year survival) but Type 1 relapses in ~40% (rising to ~57% cumulatively at 10 years), whereas Type 2 rarely relapses. First-line therapy is corticosteroids; rituximab and immunomodulators manage refractory/relapsing disease, and the anti-CD19 antibody inebilizumab became the first FDA-approved therapy for IgG4-RD in 2025 (MITIGATE phase 3). This report synthesizes 20 confirmed findings from 52 reviewed papers into a comprehensive knowledge-base entry.

Section 1 — Disease Information

Overview. AIP is a rare, distinct form of chronic pancreatitis characterized by pancreatic inflammation with a fibroinflammatory basis and, in most cases, an autoimmune/immune-mediated pathogenesis and dramatic response to corticosteroids. It represents approximately 2% of chronic pancreatitis cases (PMID: 25099388). The disease is now formally divided into three subtypes (PMID: 40364113):

AIP-1 / Type 1 — lymphoplasmacytic sclerosing pancreatitis (LPSP); pancreatic manifestation of IgG4-RD
AIP-2 / Type 2 — idiopathic duct-centric pancreatitis (IDCP)
AIP-3 / Type 3 — immune-checkpoint-inhibitor (ICI)-induced

Key identifiers. - Mondo: MONDO:0015175 - MeSH: Autoimmune Pancreatitis (D000081012) - ICD-11: DC31 (chronic pancreatitis grouping); commonly coded under K86.1 (ICD-10, other chronic pancreatitis) / K85–K86 pancreatic disease - Orphanet: Autoimmune pancreatitis (classified within IgG4-related disease / AIP) - OMIM: No single Mendelian OMIM entry — AIP is a complex/polygenic disease, not a monogenic disorder

Synonyms and alternative names. Lymphoplasmacytic sclerosing pancreatitis (LPSP; Type 1); idiopathic duct-centric pancreatitis (IDCP; Type 2); IgG4-related pancreatitis; sclerosing pancreatitis; non-alcoholic duct-destructive chronic pancreatitis.

Source of information. The information in this report is derived predominantly from aggregated disease-level resources — nationwide epidemiological surveys (Japan), multicenter cohorts, systematic reviews/meta-analyses, GWAS, mechanistic immunology studies, and a phase 3 randomized trial — supplemented by individual case reports. It is not primarily EHR-derived.

Section 2 — Etiology

Disease causal factors. AIP etiology is multifactorial, involving a complex interplay of genetic predisposition, environmental triggers, and dysregulated adaptive immunity (PMID: 41728618). No single Mendelian cause exists. Type 3 is uniquely drug-induced (ICIs) (PMID: 42467391).

"The pathogenesis of IgG4-SC involves a complex interplay of genetic predisposition, environmental triggers (e.g., industrial vapors, dust, gases, fumes, and asbestos), and dysregulated adaptive immunity." (PMID: 41728618)

Genetic risk factors. A Japanese GWAS of 835 IgG4-RD patients vs 1,789 controls identified two genome-wide-significant susceptibility loci: HLA-DRB1 and FCGR2B (PMID: 38229354). Earlier associations include the HLA DRB1*0405–DQB1*0401 haplotype and FCRL3 (Fc-receptor-like 3) polymorphisms (PMID: 18341485). CTLA4 +6230 G/G increased AIP risk (OR 2.48, p=0.011), and the +49A/A and +6230A/A genotypes increased relapse risk (OR 5.45 and 12.66) with elevated serum soluble CTLA4 (8.9 vs 2.9 ng/mL, p<0.001) (PMID: 18341485). Targeted high-throughput sequencing implicated P2RX3 and TOP1 (surviving Bonferroni correction) among 11 candidate genes for Type 1 AIP susceptibility (PMID: 28955865).

Environmental risk factors. Occupational/industrial exposures — industrial vapors, dust, gases, fumes, and asbestos — are implicated triggers (PMID: 41728618). In an AIP cohort, blue-collar profession and smoking were potential risk factors for adverse metabolic outcomes (PMID: 35807009). Older age and male sex are strong demographic risk factors (see Section 9).

Protective factors. No well-established genetic protective variants have been defined for AIP. Environmental protective factors are not established. Notably, serum IgG4 normal at diagnosis or normalized after steroids is protective against relapse (PMID: 42185503), and corticosteroid maintenance reduces relapse.

Gene–environment interactions. The proposed model is that environmental/innate triggers (e.g., NET-inducing stimuli, industrial exposures) act on a genetically primed immune background (HLA-DRB1, FCGR2B, CTLA4, FCRL3) to unleash the pathogenic CD4+ CTL/plasmablast axis. Molecular mimicry (e.g., Helicobacter pylori plasminogen-binding protein homology with human carbonic anhydrase) has been hypothesized but not proven.

Section 3 — Phenotypes

Cardinal presenting phenotypes. The most common presentation overall is painless obstructive jaundice with weight loss, closely mimicking pancreatic cancer (PMID: 38516247, PMID: 32234378).

"The clinical manifestations of AIP mainly include painless jaundice and weight loss." (PMID: 38516247)

In the 2016 Japan survey, 63% of patients were symptomatic, roughly half of whom had jaundice (PMID: 31872350).

Phenotype	Type	HPO suggestion	Frequency / Notes
Obstructive jaundice	Clinical sign	HP:0000952 (Jaundice)	~50% of symptomatic; independent risk factor for diabetes (PMID: 35807009)
Weight loss	Symptom	HP:0001824	Common presenting feature (PMID: 38516247)
Abdominal pain	Symptom	HP:0002027	Variable; usually mild (contrast with acute pancreatitis)
Pancreatic exocrine insufficiency (PEI)	Lab/functional	HP:0001738	72.7% at diagnosis, 63.5% at follow-up (PMID: 35807009)
Diabetes mellitus (endocrine insufficiency)	Lab abnormality	HP:0000819	Prevalence 32.8% at diagnosis; cumulative incidence 17.9% (PMID: 35807009)
Elevated serum IgG4	Lab abnormality	HP:0030355 (Increased circulating IgG level)	86–88% in Type 1 (Japan surveys)
Diffuse pancreatic enlargement ("sausage" pancreas)	Imaging sign	HP:0012093-related	Type 1 typical imaging
Sialadenitis / lacrimal gland swelling	Physical manifestation	HP:0000163 / HP:0000509-related	IgG4-RD systemic feature (Type 1)
Eosinophilia	Lab abnormality	HP:0001880	Reported in subset of IgG4-RD (PMID: 38407323)

Phenotype characteristics. Onset is adult/geriatric (see Section 8). Progression is typically insidious/chronic with an episodic/relapsing course in Type 1. Severity is variable; most cases respond dramatically to steroids.

"PEI prevalence at diagnosis was 72.7% and was 63.5% at follow-up. The cumulative incidence of DM was 17.9%, with a prevalence of DM at diagnosis of 32.8%." (PMID: 35807009)

Quality-of-life impact. Formal EQ-5D/SF-36/PROMIS data specific to AIP were not identified. Functional impact is driven largely by exocrine insufficiency (malabsorption, weight loss), new-onset diabetes, and, in relapsing disease, repeated hospitalizations and cumulative organ damage.

Section 4 — Genetic / Molecular Information

Causal genes. AIP is not monogenic; there are no causal Mendelian genes. Instead, susceptibility loci confer polygenic risk:

Gene / locus	HGNC	Evidence	Effect
HLA-DRB1 (esp. DRB10405–DQB10401 haplotype)	HGNC:4948	GWAS genome-wide significant (PMID: 38229354); haplotype association (PMID: 18341485)	Antigen presentation susceptibility
FCGR2B	HGNC:3618	GWAS genome-wide significant (PMID: 38229354)	Inhibitory Fc receptor; B-cell regulation
CTLA4	HGNC:2505	+6230 G/G OR 2.48 for risk; relapse OR up to 12.66 (PMID: 18341485)	T-cell checkpoint
FCRL3	HGNC:18506	Polymorphism association (PMID: 18341485)	B-cell regulation
P2RX3, TOP1	HGNC:8535 / HGNC:11986	Candidate (Bonferroni-significant) (PMID: 28955865)	Susceptibility markers

"Two susceptibility loci for IgG4-related disease were identified. Both FCGR2B and HLA loci might have important roles in IgG4-related disease development." (PMID: 38229354)

Pathogenic variants. Because AIP is polygenic, ACMG/AMP pathogenicity classification does not apply in the Mendelian sense. Associated variants are common susceptibility polymorphisms/haplotypes (e.g., HLA class II alleles, CTLA4 SNPs rs231775 [+49A/G], +6230 A/G) rather than rare pathogenic mutations. These are germline in origin. Functional consequence is immune dysregulation (altered antigen presentation, impaired T-cell checkpoint/inhibitory-receptor signaling) rather than classic loss/gain of function in a structural protein.

Autoantigens (molecular targets). Four candidate autoantigens have been described in IgG4-RD: annexin A11, galectin-3 (LGALS3), laminin 511-E8, and prohibitin 1 (PMID: 38332916). Anti-galectin-3 autoantibodies were detected in 13.5% of IgG4-related cholangitis patients but not in primary sclerosing cholangitis controls.

"Four autoantigens have recently been described in IgG4-RD: annexin A11, galectin-3, laminin 511-E8, and prohibitin 1." (PMID: 38332916)

Modifier genes. CTLA4 genotypes modify relapse risk (+49A/A OR 5.45; +6230A/A OR 12.66) (PMID: 18341485). Candidate relapse-modifying variants (HLA-C, CXCR3, CACNA1C) were reported by targeted sequencing (PMID: 28955865).

Epigenetic information & chromosomal abnormalities. No established disease-specific DNA methylation, histone-modification, or chromosomal-abnormality signatures for AIP were identified. This is a knowledge gap.

Section 5 — Environmental Information

Environmental factors. Industrial/occupational exposures — industrial vapors, dust, gases, fumes, and asbestos — are implicated as triggers of IgG4-RD/AIP (PMID: 41728618). Blue-collar occupation was associated with adverse metabolic outcomes (PMID: 35807009).

Lifestyle factors. Smoking is the best-supported lifestyle risk factor, identified as a potential contributor to diabetes/exocrine-insufficiency outcomes in AIP (PMID: 35807009) and a recognized risk factor for chronic pancreatitis more broadly.

Infectious agents. No single infectious agent has been established as causal. Molecular mimicry involving Helicobacter pylori plasminogen-binding protein (homology with human carbonic anhydrase II / ubiquitin-protein ligase) has been hypothesized but not proven. AIP is not a transmissible/zoonotic disease.

Section 6 — Mechanism / Pathophysiology

Ordered causal chain (Type 1 AIP / IgG4-RD)

1. Genetic priming (HLA-DRB1, FCGR2B, CTLA4, FCRL3 risk alleles)
+ environmental/innate trigger
   → leads to →
2. Innate activation: tissue stimulus induces NEUTROPHIL EXTRACELLULAR TRAPS (NETs)
   → NETs stimulate →
3. PLASMACYTOID DENDRITIC CELLS (pDCs) accumulate in pancreas and produce IFN-α
   [NECESSARY step: pDC depletion / IFN-α blockade prevents AIP in mouse model]
   → IFN-α (with BAFF) drives →
4. B-CELL activation & IgG4-CLASS SWITCHING → oligoclonal expansion of IgG4+ PLASMABLASTS/plasma cells
   → plasmablasts present antigen to →
5. CD4+SLAMF7+ CYTOTOXIC T LYMPHOCYTES (CTLs) — oligoclonally expanded — infiltrate lesions
   [self-sustaining loop: CTLs ↔ plasmablasts via continuous antigen presentation]
   → CD4+ CTLs exert DUAL effects →
(a) direct cytotoxicity → acinar/epithelial cell death (TISSUE DAMAGE)
(b) secretion of profibrotic factors (e.g., TGF-β) → activate fibroblasts
   → results in →
6. STORIFORM FIBROSIS + OBLITERATIVE PHLEBITIS + dense lymphoplasmacytic infiltrate
   → produces →
7. Mass-forming pancreatic enlargement, ductal narrowing → OBSTRUCTIVE JAUNDICE,
   exocrine & endocrine insufficiency (CLINICAL MANIFESTATION)

Branch — Type 2 AIP (IDCP): IgG4-independent; neutrophil-mediated granulocytic epithelial lesions (GEL) destroy duct epithelium → pancreas-restricted duct-centric inflammation (frequently co-occurring with IBD).

Branch — Type 3 AIP (ICI-related): ICI blockade of PD-1/PD-L1/CTLA-4 removes T-cell checkpoint restraint → acinar-centric T-cell infiltration evolving from CD4+ to CD8+ predominance → often asymptomatic hyperlipasemia, with pancreatic atrophy/diabetes as sequelae (PMID: 41922528).

Detail by category

Immune system involvement — the core mechanism. The traditional Th2 (IL-4/IL-10) paradigm is now considered insufficient to explain tissue destruction and fibrosis. Instead, oligoclonally expanded CD4+ cytotoxic T lymphocytes (CTLs) bearing SLAMF7 are the central effectors, with dual cytotoxic and profibrotic properties (PMID: 41766862):

"Emerging data highlight the extensive, oligoclonally expanded infiltration of CD4+ cytotoxic T lymphocytes (CTLs) deep within lesions. These cells possess dual cytotoxic and profibrotic properties." (PMID: 41766862)

These CTLs are sustained by continuous antigen presentation by B-lineage cells, particularly plasmablasts (PMID: 27667138), explaining why B-cell depletion (rituximab, inebilizumab) is effective. The CD4+SLAMF7+ population expands in patients and decreases after glucocorticoid treatment (PMID: 29499100). A distinctive CD4+ response dominated by Th2, T-follicular-helper (Tfh), and regulatory T cells (Tregs) drives B-cell activation and IgG4+ plasmablast expansion (PMID: 41728618). M2 macrophages also contribute (PMID: 35737955).

"A distinctive CD4+ T-cell response, dominated by T-helper 2 (Th2), follicular helper T (Tfh) cells, and regulatory T cells (Tregs), drives B-cell activation, oligoclonal expansion of IgG4+ plasmablasts, and progressive fibrosis." (PMID: 41728618)

Innate immunity (upstream trigger). In the MRL/Mp mouse, disease develops in parallel with pancreatic accumulation of IFN-α-producing plasmacytoid dendritic cells (pDCs); pDC depletion and IFN-α blockade prevent AIP, proving necessity (PMID: 26297761). Neutrophil extracellular traps (NETs) stimulate pDCs to make IFN-α; human patient pDCs cultured with NETs produced greatly increased IFN-α and induced B cells to make IgG4 (but not IgG1) (PMID: 26297761). SLAMF7 on CD8+ T cells is also increased in AIP (PMID: 37661465).

"patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1)" (PMID: 26297761)

Cellular processes. Chronic inflammation, epithelial/acinar apoptosis and cytotoxic killing, fibroblast activation, and progressive fibrosis.

Tissue-damage mechanisms. Fibrosis (storiform pattern), obliterative phlebitis, lymphoplasmacytic destruction. In Type 2, neutrophilic duct destruction (GEL). Reduced ductal CFTR expression contributes to acinar dysfunction; CFTR correctors (C18) rescued function and reduced inflammation in mice (PMID: 28634110).

Molecular profiling. Circulating plasmablast expansion is a robust cellular biomarker (see Section 10). Cytokine signatures (IFN-γ, IL-10, IL-13, IL-5, IL-21) correlate with disease activity (PMID: 42277154).

Suggested ontology terms. GO:0002250 (adaptive immune response), GO:0001909 (leukocyte-mediated cytotoxicity), GO:0030198 (extracellular matrix organization / fibrosis), GO:0006954 (inflammatory response), GO:0032606 (type I interferon production). Cell types: CL:0000625 (CD8-positive cytotoxic T cell), CL:0000624 (CD4-positive T cell), CL:0000980 (plasmablast), CL:0000784 (plasmacytoid dendritic cell), CL:0000775 (neutrophil), CL:0000890 (M2 macrophage).

Section 7 — Anatomical Structures Affected

Primary organ. The pancreas (UBERON:0001264) is the primary affected organ in all subtypes.

Secondary/systemic involvement (Type 1 / IgG4-RD). IgG4-RD is a systemic mass-forming fibroinflammatory condition affecting nearly every organ (PMID: 26672716):

"The organs most frequently involved are the pancreas (autoimmune pancreatitis (AIP), salivary and lacrimal glands (Mickulicz disease and sclerosing sialadenitis), biliary tree (sclerosing cholangitis or cholecystitis), retroperitoneum (retroperitoneal fibrosis), aorta (periaortic fibrosis), kidneys (interstitial nephritis) and thyroid (Riedel thyroiditis)." (PMID: 26672716)

Structure	UBERON	Manifestation
Pancreas	UBERON:0001264	AIP (primary)
Bile ducts / biliary tree	UBERON:0002394	IgG4-related sclerosing cholangitis
Salivary glands	UBERON:0001044	Sclerosing sialadenitis (Mikulicz)
Lacrimal glands	UBERON:0001817	Dacryoadenitis
Kidney	UBERON:0002113	Tubulointerstitial nephritis
Retroperitoneum	UBERON:0003693	Retroperitoneal fibrosis
Aorta	UBERON:0000947	Periaortitis
Thyroid	UBERON:0002046	Riedel thyroiditis

Extrapancreatic lesions were detected in 60% of AIP patients in the 2016 Japan survey (PMID: 31872350). Type 2 AIP is pancreas-restricted (except rare IBD/sialadenitis) (PMID: 34670874, PMID: 32825945).

Tissue/cell level. Pancreatic ductal and acinar epithelium (targets), with infiltration by plasma cells, plasmablasts, CD4+/CD8+ T cells, pDCs, neutrophils (Type 2), and M2 macrophages. Subcellular: ER (secretory pathway of plasma cells) and ductal apical membrane (CFTR). Body system: digestive/endocrine.

Localization / lateralization. The pancreas can be diffusely enlarged ("sausage" pancreas, Type 1) or focally involved (mimicking cancer). Not a lateralized organ; involvement is described as diffuse vs focal/segmental.

Section 8 — Temporal Development

Onset. Adult to geriatric. Mean age at diagnosis ~64.8 years (2016 Japan survey; mean age 68.1) (PMID: 31872350); ~59–66 in other cohorts. Onset pattern is insidious/chronic/subacute, frequently presenting as painless jaundice. Type 2 tends to occur in somewhat younger patients than Type 1.

Progression. Type 1 follows a relapsing-remitting course. Cumulative relapse rates in a 10-year Type 1 cohort were 11.0% / 26.9% / 38.3% / 50.0% / 56.9% at 1/3/5/7/10 years (PMID: 42185503):

"Cumulative relapse rates at 1, 3, 5, 7, and 10 years were 11.0%, 26.9%, 38.3%, 50.0%, and 56.9%." (PMID: 42185503)

Progression is generally slow; end-stage disease features pancreatic atrophy, exocrine insufficiency, and diabetes.

Patterns. Remission is typically treatment-induced (corticosteroids). Type 2 AIP relapse is uncommon (favorable). Corticosteroid discontinuation independently predicts relapse, while normal/normalized serum IgG4 is protective (PMID: 42185503). Critical intervention window: early steroid therapy induces remission and prevents irreversible fibrotic damage.

Section 9 — Inheritance and Population

Epidemiology (Japan nationwide surveys — the best-characterized data):

Year	Prevalence /100,000	Incidence /100,000/yr	M:F	Mean age	High serum IgG4
2007 (PMID: 22466167)	2.2	0.9	3.7	63.0	87.6%
2011 (PMID: 25815647)	4.6	1.4	3.2	66.3	86.4%
2016 (PMID: 31872350)	10.1	3.1	2.94	68.1	—

"The estimated number of AIP patients in 2016 was 13,436, with an overall prevalence rate of 10.1 per 100,000 persons. The estimated number of newly diagnosed patients was 3984, with an annual incidence rate of 3.1 per 100,000 persons." (PMID: 31872350)

Prevalence more than doubled from 2011 to 2016, reflecting rising recognition. AIP accounts for ~2% of chronic pancreatitis (PMID: 25099388).

Inheritance pattern. Multifactorial / polygenic — NOT Mendelian. No AD/AR/X-linked/mitochondrial inheritance. Penetrance, expressivity, anticipation, mosaicism, founder effects, consanguinity, and carrier frequency are not applicable in the classical genetic sense.

Demographics. Strong male predominance (M:F ~3:1), elderly onset (Type 1). Subtype distribution among surgically confirmed AIP: Type 1 ~94%, Type 2 ~6% (PMID: 39169289) — though Type 2 is relatively more common in Western/younger/IBD populations. Type 1 is more prevalent in East Asia; Type 2 is proportionally more common in Europe/North America.

"The male-to-female sex ratio was 2.94, the mean age was 68.1, and mean age at diagnosis was 64.8." (PMID: 31872350)

Section 10 — Diagnostics

Diagnostic frameworks. Diagnosis is established by the International Consensus Diagnostic Criteria (ICDC) or HISORt (Histology, Imaging, Serology, Other organ involvement, Response to therapy) (PMID: 25099388), and the Japan Pancreas Society (JPS) criteria (PMID: 40996454).

"Diagnosis of AIP is established according to the international consensus diagnostic criteria (ICDC) or HISORt (mnemonic standing for histology, imaging, serology, other organ involvement and response to therapy) criteria." (PMID: 25099388)

In Type 1, typical imaging changes can suffice even with negative histology; in Type 2, histologic evidence (GEL) is required (PMID: 37947862).

"In type 1 AIP, typical imaging changes are sufficient to establish the diagnosis even with negative histology, whereas for type 2 AIP, histologic evidence is required." (PMID: 37947862)

Serology / biomarkers. - Serum IgG4: >2× ULN suggestive, >4× ULN highly specific; IgG4/IgG1 ratio >0.24 is discriminatory (PMID: 41728618). However, sensitivity is limited — ~13–16% of patients have normal serum IgG4, and in surgical series Type 1 sensitivity can be ~43% (PMID: 24817416, PMID: 39169289). - Circulating plasmablasts: a robust IgG4-independent biomarker — markedly elevated (median 4,698/mL vs 592/mL untreated disease controls, 94/mL healthy; p<0.001); 36% of IgG4-RD patients with NORMAL serum IgG4 still had elevated plasmablasts; levels fall with rituximab and rise at flare (PMID: 24817416).

"The IgG4-RD patients had substantially elevated total plasmablast counts (median 4698/mL, range 610-79524/mL) compared to both untreated disease controls (median 592/mL, range 19-4294/mL; p < 0.001) and healthy controls (median 94/mL, range 1-653/mL; p < 0.001)." (PMID: 24817416)

Type 2 has no established serum marker — diagnosis requires histologic GEL (PMID: 34670874).

"Since there are currently no established serum markers, the diagnosis of type 2 AIP is highly challenging and requires the tissue confirmation of neutrophilic injury to the pancreatic ducts, a finding designated as a granulocytic epithelial lesion." (PMID: 34670874)

Imaging. Diffuse pancreatic enlargement ("sausage" pancreas) with delayed/rim enhancement and narrowed main pancreatic duct (Type 1). 18F-FDG PET/CT aids diagnosis, staging of systemic involvement, and treatment monitoring (PMID: 26672716). Endoscopic ultrasound (EUS) with EUS-guided core biopsy is the main modality for tissue sampling and for differentiating AIP from cancer (PMID: 40996454).

Histopathology. Type 1: storiform fibrosis, obliterative phlebitis, dense lymphoplasmacytic infiltrate rich in IgG4+ plasma cells (PMID: 28747608). Type 2: granulocytic epithelial lesion (GEL) — neutrophilic duct epithelial injury (PMID: 34670874).

Differential diagnosis. The critical differential is pancreatic ductal adenocarcinoma; also cholangiocarcinoma, primary sclerosing cholangitis, and other chronic pancreatitis (PMID: 40996454, PMID: 40191403).

Genetic testing. Not part of routine diagnosis (polygenic disease). HLA/CTLA4 genotyping is research-only.

Section 11 — Outcome / Prognosis

Survival. Favorable. 10-year overall survival 85.5% in a corticosteroid-treated Type 1 cohort; corticosteroid maintenance associated with better survival (PMID: 42185503).

Relapse (key prognostic issue). Type 1 relapses in ~40–42% (PMID: 40773035, PMID: 41223493); cumulative ~57% at 10 years (PMID: 42185503). Type 2 relapse is uncommon (PMID: 37826920).

"AIP primarily consists of type 1 and type 2, with relapse being a significant problem mainly associated with type 1 AIP, which has a high relapse rate of approximately 40%, whereas type 2 AIP has significantly lower relapse rates." (PMID: 40773035)

Prognostic factors for relapse: younger age (<60 y; OR 1.7, 95% CI 1.1–2.7, p=0.022) (PMID: 41223493); persistent/insufficiently declining serum IgG4, diffuse pancreatic swelling, proximal biliary/renal involvement (PMID: 40773035); corticosteroid discontinuation (PMID: 42185503).

"The overall relapse rate was 41.9 %, being higher in the <60 years group (46.2 %) than in the ≥60 years group (37.0 %). Age <60 years was significantly associated with increased relapse risk (OR = 1.7; 95 % CI: 1.1-2.7, P = 0.022)." (PMID: 41223493)

Morbidity/complications. Exocrine insufficiency (up to 72.7%), diabetes (~33% prevalence), biliary strictures, and progressive fibrosis. HbA1c worsened and serum albumin declined (mean −0.27 g/dL) by 10 years (PMID: 42185503).

Malignancy risk. Overall malignancy risk not increased (SIR 1.00, 95% CI 0.59–1.42), but pancreatic cancer SIR numerically higher (1.98 overall; 2.96 at ≥5 years) (PMID: 42185503). A nationwide Swedish study found autoimmune diseases collectively raise pancreatic-cancer risk (SIR 1.24 men, 1.19 women) (PMID: 41795138).

"Overall malignancy risk was not increased (SIR 1.00; 95%CI 0.59-1.42), while pancreatic cancer (PC) showed a numerically higher SIR (1.98 overall; 2.96 ≥ 5 years postdiagnosis)." (PMID: 42185503)

Section 12 — Treatment

First-line: corticosteroids. Oral corticosteroids are the standard first-line therapy, effective in the majority (NCIT: Corticosteroid Therapy) (PMID: 36293522, PMID: 38516247). Prolonged maintenance glucocorticoid reduces relapse (PMID: 40773035).

"The standard therapy for AIP is oral administration of corticosteroids. Rituximab (RTX) has also been proposed for induction of remission and maintenance therapy in relapsing AIP-1." (PMID: 36293522)

B-cell-targeted / immunomodulatory (relapsing/refractory disease). - Rituximab (anti-CD20; NCIT:C1702) — induction and maintenance in relapsing AIP-1 (PMID: 36293522). - Steroid-sparing immunomodulators: azathioprine, methotrexate, mycophenolate mofetil (off-label) (PMID: 40745228).

Inebilizumab (anti-CD19) — first FDA-approved therapy for IgG4-RD (2025). The phase 3 MITIGATE trial (n=135) showed inebilizumab significantly reduced recurrence (10% vs 60% placebo), annual exacerbation rate, and glucocorticoid need; serum IgG4 fell ~50% with persistent B-cell depletion over 52 weeks; more infections/lymphopenia but no treatment-associated deaths (PMID: 40745228).

"The treatment significantly reduced the risk of recurrence (10% vs. 60% under placebo), the annual exacerbation rate and the necessity for renewed administration of glucocorticoids." (PMID: 40745228)

"Following approval of inebilizumab by the U.S. Food and Drug Administration (FDA) for IgG4-RD in 2025" (PMID: 40745228)

Type 2 AIP. Responds well to glucocorticoids; anti-TNF-α antibodies are a promising alternative (PMID: 37826920).

"Patients with AIP-2 respond well to glucocorticoids, with anti-tumor necrosis factor-alpha antibodies as a promising alternative therapy." (PMID: 37826920)

Type 3 (ICI-related). Corticosteroid role controversial; management guidelines not established; ICI cessation and supportive care are used (PMID: 41922528).

Experimental targeted agents (under evaluation). Anti-SLAMF7 (elotuzumab), obexelimab (CD19), BTK inhibitors, JAK/STAT inhibitors, and T2-inflammation biologics (PMID: 37858433). Targeting the plasmablast–B-cell lineage and CD4+SLAMF7+ CTL axis is the most promising future direction (PMID: 35737955).

Supportive care. Pancreatic enzyme replacement (exocrine insufficiency), insulin/oral agents (diabetes), biliary stenting (obstructive jaundice).

Pharmacogenomics. CTLA4 genotypes modulate relapse risk (PMID: 18341485); no validated genotype-guided dosing protocol exists yet.

Section 13 — Prevention

Primary prevention. No established primary prevention (etiology is multifactorial/idiopathic). Modifiable risk-factor reduction (smoking cessation; avoiding industrial exposures) is reasonable but unproven. For Type 3, awareness of ICI risk allows monitoring but not avoidance without foregoing cancer therapy.

Secondary prevention (early detection). Vigilant differentiation of AIP from pancreatic cancer to avoid unnecessary resection (PMID: 40191403); serial serum IgG4 and imaging for early relapse detection.

Tertiary prevention (complication prevention). Corticosteroid maintenance to prevent relapse and irreversible fibrotic organ damage (PMID: 40773035, PMID: 42185503); long-term surveillance with labs, imaging (MRCP/EUS), and endoscopy for biliary strictures (PMID: 40191403); monitoring for exocrine/endocrine insufficiency and pancreatic cancer.

Immunization, genetic screening, counseling. Not applicable (non-infectious, polygenic disease). No carrier/prenatal screening.

Section 14 — Other Species / Natural Disease

Taxonomy: Human (NCBI:txid9606) is the disease context. Experimental disease is induced in mouse (NCBI:txid10090).
Naturally occurring animal disease: No well-established naturally occurring analog of human AIP in companion animals or wildlife was identified in the reviewed literature. (Lymphoplasmacytic/immune-mediated pancreatitis exists in dogs but is not established as an AIP ortholog.) — Knowledge gap.
Orthologous genes: CTLA4, FCGR2B, and HLA (H2 in mouse) have murine orthologs used in models.
Zoonotic potential: None — AIP is non-transmissible.

Section 15 — Model Organisms

Principal model: MRL/Mp mouse + poly(I:C). Autoimmune-prone MRL/Mp mice given repeated intraperitoneal polyinosinic–polycytidylic acid [poly(I:C)] develop experimental AIP with massive pancreatic architecture destruction, immune infiltration, fibrosis, multi-organ involvement, and elevated autoantibodies resembling human IgG4-RD (PMID: 29512140).

"autoimmune-prone MRL/Mp mice treated with repeated injection with polyinosinic-polycytidylic acid (poly (I:C)) provide an experimental model of AIP. These mice exhibit massive destruction of pancreatic architecture associated with pancreatic immune cell infiltration and fibrosis." (PMID: 29512140)

Key limitation. "Although mice lack the IgG4 Ab subtype" (PMID: 29512140) — mice cannot recapitulate the defining IgG4 serology/plasma-cell feature, limiting translational fidelity for the IgG4 axis.

Other models. NOD/ShiLTJ mice and BMP6-transduced mice model Sjögren's/chronic pancreatitis; MRL/Mp models AIP with markedly reduced ductal CFTR expression — CFTR correctors (C18) rescued function and reduced inflammation (PMID: 28634110).

Applications. These models established the NET → pDC → IFN-α → IgG4 innate axis (PMID: 26297761), the role of SLAMF7+ CD8 T cells (PMID: 37661465), and the therapeutic potential of CFTR correction and steroid response.

Resources: MGI (mouse); model strains MRL/MpJ, NOD/ShiLTJ.

Mechanistic Model / Interpretation

The synthesized model positions Type 1 AIP as a two-compartment autoimmune loop ignited by innate immunity:

 INNATE IGNITION                ADAPTIVE AMPLIFICATION            EFFECTOR / DAMAGE
 ┌────────────────┐            ┌───────────────────────┐         ┌────────────────────┐
 │ Trigger + NETs │──IFN-α──▶  │ pDC → B-cell IgG4      │◀──────▶ │ CD4+SLAMF7+ CTL     │
 │ (genetic prime)│            │ class switch →         │  antigen│  • cytotoxicity     │
 └────────────────┘            │ IgG4+ plasmablasts     │ present │  • profibrotic TGF-β│
               └───────────────────────┘         └─────────┬──────────┘
                        ▲   B-cell depletion                │
                        │   (rituximab / inebilizumab)      ▼
                        └───────────────────────────  STORIFORM FIBROSIS +
                                                       OBLITERATIVE PHLEBITIS
                                                       → jaundice, PEI, DM

Two therapeutic insights follow directly from this architecture. First, because CD4+ CTLs are sustained by plasmablast antigen presentation, depleting the B-cell/plasmablast compartment collapses the entire loop — explaining why rituximab and now inebilizumab (anti-CD19, which reaches later B-lineage stages including plasmablasts) are effective. Second, the innate IFN-α axis offers an upstream target not yet exploited clinically. Type 2 and Type 3 are mechanistically distinct — neutrophil-driven and checkpoint-release T-cell-driven, respectively — and therefore require different management, underscoring why accurate subtyping is clinically essential.

Evidence Base

Domain	Key PMIDs	Contribution
Subtype definition & frequency	39169289, 38516247, 40364113	Established Type 1/2/3 taxonomy and 94%/6% split
Core immune mechanism	41766862, 27667138, 29499100, 28747608	CD4+SLAMF7+ CTL / plasmablast loop; histopathology
Innate trigger	26297761, 29512140	NET→pDC→IFN-α axis; mouse model
Genetics	38229354, 18341485, 28955865	HLA-DRB1, FCGR2B, CTLA4, FCRL3
Autoantigens	38332916	Annexin A11, galectin-3, laminin 511-E8, prohibitin 1
Epidemiology	31872350, 25815647, 22466167	Prevalence/incidence trends (Japan)
Diagnosis / biomarkers	25099388, 37947862, 24817416, 41728618, 40996454	ICDC/HISORt; IgG4 thresholds; plasmablasts
Prognosis / relapse	40773035, 41223493, 42185503	40% relapse; 85.5% 10-yr survival; PC risk
Treatment	36293522, 40745228, 37826920	Steroids, rituximab, inebilizumab (MITIGATE), anti-TNF
Type 2	34670874, 37826920, 32825945	GEL, IBD association, favorable prognosis
Type 3 (ICI)	42467391, 41922528	Definition, incidence 0.5–5.7%, CD4→CD8 histology
Systemic / anatomy	26672716, 32234378, 40191403	Multi-organ IgG4-RD; biliary involvement
Clinical phenotype	35807009	Exocrine (72.7%)/endocrine (32.8%) insufficiency

The evidence base is internally consistent: mechanistic (mouse/in-vitro), genetic (GWAS), epidemiological (nationwide surveys), and therapeutic (phase 3 RCT) lines converge on a B-cell/plasmablast–CD4+ CTL model of Type 1 AIP, validated therapeutically by the success of B-cell depletion.

Limitations and Knowledge Gaps

Epidemiology is Japan-centric. The best prevalence/incidence data derive from Japanese nationwide surveys; Western/global incidence, and true Type 2 proportion outside Asia, are less precisely quantified.
No monogenic cause / no ClinVar pathogenic variants. AIP is polygenic; standard ACMG variant classification, penetrance, and carrier-frequency concepts do not apply. Epigenetic and chromosomal data are essentially absent.
Autoantigen causality unproven. The four candidate autoantigens (annexin A11, galectin-3, laminin 511-E8, prohibitin 1) are associations; a single dominant, disease-driving autoantigen has not been definitively established.
Serum IgG4 imperfect. ~13–16% of patients are seronegative; specificity is limited, and it correlates inconsistently with activity in fibrotic/localized subsets (PMID: 42277154).
Mouse model lacks IgG4. The MRL/Mp poly(I:C) model cannot recapitulate the defining IgG4 serology.
Type 3 evidence is thin. AIP-3 rests on small retrospective series with no consensus diagnostic/management guidelines.
QoL data absent. No AIP-specific EQ-5D/SF-36/PROMIS data were identified.
Inebilizumab is new. Long-term (>52-week) safety/efficacy and comparative data vs rituximab are not yet available.

Proposed Follow-up Experiments / Actions

Validate circulating plasmablasts + IgG4/IgG1 ratio as a combined diagnostic/monitoring panel in a prospective multi-ethnic cohort, particularly to capture IgG4-seronegative patients.
Single-cell / spatial transcriptomics of AIP pancreatic tissue to map the CD4+SLAMF7+ CTL–plasmablast niche and identify upstream antigen-presenting cell states (fills the "which autoantigen" gap).
Test upstream innate blockade (anti-IFN-α / anti-type-I-IFN receptor, or NET inhibitors) in the MRL/Mp model as a steroid-sparing strategy, given the demonstrated necessity of the pDC/IFN-α axis.
Head-to-head or registry comparison of inebilizumab vs rituximab for relapse prevention, with cost, infection risk, and durability endpoints.
Establish international Type 2 and Type 3 registries with standardized histologic/GEL and ICI-exposure criteria to define incidence, natural history, and management.
Prospective pancreatic-cancer surveillance study in Type 1 AIP (≥5-year follow-up) to confirm/quantify the numerically elevated pancreatic-cancer SIR and define screening value.
Epigenomic profiling (methylation/ATAC-seq) of AIP tissue to fill the current absence of epigenetic data.

Consensus Answer

Autoimmune pancreatitis (AIP; MONDO:0015175) is a rare, corticosteroid-responsive fibroinflammatory chronic pancreatitis comprising three immunologically distinct subtypes — Type 1 (lymphoplasmacytic sclerosing pancreatitis, the pancreatic manifestation of IgG4-related disease, driven by a self-sustaining CD4+SLAMF7+ cytotoxic-T-lymphocyte/plasmablast loop with an upstream NET→plasmacytoid-dendritic-cell→IFN-α innate axis producing storiform fibrosis and obliterative phlebitis), Type 2 (idiopathic duct-centric pancreatitis, IgG4-negative, neutrophil/granulocytic-epithelial-lesion-mediated, associated with inflammatory bowel disease), and Type 3 (immune-checkpoint-inhibitor-induced). It is polygenic/multifactorial (HLA-DRB1, FCGR2B, CTLA4, FCRL3), typically presents in older men with painless obstructive jaundice mimicking pancreatic cancer, is diagnosed via ICDC/HISORt criteria, and carries a favorable prognosis (~85% 10-year survival) despite ~40% relapse in Type 1, managed with corticosteroids, rituximab, and the newly FDA-approved anti-CD19 agent inebilizumab.

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome	Count
References checked	42
Resolved	42
Unresolved (possible confabulation)	0
Unverifiable	0
References weighed for topical relevance	42
On topic	29
Off topic	0

All extracted references resolved successfully.

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Outcome	Count
Terms checked	37
Resolved	31
Unresolved (possible confabulation)	0
Obsolete	0
Unverifiable	6
Terms whose name was checked	26
Terms named correctly	15
Terms named as a different term	6
Terms whose name is worth a second look	5

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

HP:0001824 (1 mention) - the report calls it "Symptom"; HP calls it Weight loss
HP:0002027 (1 mention) - the report calls it "Symptom"; HP calls it Abdominal pain
HP:0001738 (1 mention) - the report calls it "Lab/functional"; HP calls it Exocrine pancreatic insufficiency
HP:0000819 (1 mention) - the report calls it "Lab abnormality"; HP calls it Diabetes mellitus
HP:0030355 (1 mention) - the report calls it "Increased circulating IgG level"; HP calls it Abnormal circulating interferon-gamma concentration
HP:0001880 (1 mention) - the report calls it "Lab abnormality"; HP calls it Increased total eosinophil count

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

GO:0030198 (1 mention) - the report calls it "extracellular matrix organization / fibrosis"; GO calls it extracellular matrix organization
CL:0000625 (1 mention) - the report calls it "CD8-positive cytotoxic T cell"; CL calls it CD8-positive, alpha-beta T cell
CL:0000624 (1 mention) - the report calls it "CD4-positive T cell"; CL calls it CD4-positive, alpha-beta T cell
UBERON:0002394 (1 mention) - the report calls it "Bile ducts / biliary tree"; UBERON calls it bile duct
UBERON:0002046 (1 mention) - the report calls it "Thyroid"; UBERON calls it thyroid gland, and lists "thyroid" among its other names

Terms named inconsistently

The report gives these identifiers more than one name of its own:

UBERON:0001264 - called "pancreas", "Pancreas"

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Deep Research

Autoimmune Pancreatitis (MONDO:0015175): A Comprehensive Disease Characterization

Summary

Section 1 — Disease Information

Section 2 — Etiology

Section 3 — Phenotypes

Section 4 — Genetic / Molecular Information

Section 5 — Environmental Information

Section 6 — Mechanism / Pathophysiology

Ordered causal chain (Type 1 AIP / IgG4-RD)

Detail by category

Section 7 — Anatomical Structures Affected

Section 8 — Temporal Development

Section 9 — Inheritance and Population

Section 10 — Diagnostics

Section 11 — Outcome / Prognosis

Section 12 — Treatment

Section 13 — Prevention

Section 14 — Other Species / Natural Disease

Section 15 — Model Organisms

Mechanistic Model / Interpretation

Evidence Base

Limitations and Knowledge Gaps

Proposed Follow-up Experiments / Actions

Consensus Answer

Artifacts

Reference Validation

Term Validation

Terms the report names something else

Terms whose name is worth a second look

Terms named inconsistently