Autoimmune Gastritis

Complex MONDO:0031014 Pathograph 16 Show in embeddings browser Gastritis Autoimmune disease

Autoimmune gastritis (AIG) is an organ-specific autoimmune disease characterized by chronic, corpus-restricted (oxyntic) atrophic gastritis driven by a CD4+ T cell-mediated immune response against the gastric parietal cell H+/K+ ATPase (the gastric proton pump, encoded by ATP4A and ATP4B). Immune destruction of parietal cells causes loss of gastric acid secretion (hypochlorhydria and ultimately achlorhydria) and loss of intrinsic factor, producing vitamin B12 malabsorption and pernicious anemia. Achlorhydria removes the negative feedback on antral G cells, causing hypergastrinemia, which drives enterochromaffin-like (ECL) cell hyperplasia and predisposes to type 1 gastric neuroendocrine tumors (carcinoids). Corpus atrophy with intestinal metaplasia also increases the risk of gastric adenocarcinoma. AIG frequently clusters with other autoimmune disorders, especially autoimmune thyroid disease (thyrogastric syndrome) and type 1 diabetes mellitus.

Ask OpenScientist

Ask a research question about Autoimmune Gastritis. OpenScientist will conduct autonomous deep research using the Disorder Mechanisms Knowledge Base and PubMed literature (typically 10-30 minutes).

Submitting...

Do not include personal health information in your question. Questions and results are cached in your browser's local storage.

1
Inheritance
4
Pathophys.
2
Histopath.
9
Phenotypes
4
Hypotheses
4
Gaps
16
Pathograph
2
Genes
7
Medical Actions
3
Datasets
7
References
1
Deep Research
8
Hyp. Reports
🏷

Classifications

Harrison's Part
GASTROINTESTINAL IMMUNE RHEUMATOLOGIC
👪

Inheritance

1
Polygenic inheritance HP:0010982
Complex, non-Mendelian autoimmune disease with polygenic susceptibility - HLA-DQB1 plus non-HLA loci (PTPN22, IL2RA) shared with other organ-specific autoimmune diseases - acting together with environmental factors.
Polygenic inheritance
Show evidence (1 reference)
PMID:34145262 SUPPORT Human Clinical
"We conduct a genome-wide association study meta-analysis in 2166 cases and 659,516 European controls from population-based biobanks and identify genome-wide significant signals in or near the PTPN22"
A GWAS identifies multiple risk loci (PTPN22, HLA-DQB1, IL2RA) for pernicious anemia / autoimmune gastritis, establishing polygenic inheritance.
C

Comorbidities

Autoimmune Gastritis <-> Hashimotos Thyroiditis
Disease A BIDIRECTIONAL CANDIDATE
◈

Mechanistic Hypotheses

4
Canonical Primary Autoimmunity Against the Gastric H+/K+ ATPase
canonical_primary_autoimmune_hk_atpase_origin CANONICAL
Evidence balance 4 support
Autoimmune gastritis is a primary organ-specific autoimmune disease driven by a breakdown of self-tolerance to the parietal-cell H+/K+ ATPase (ATP4A/ATP4B), with CD4 T-cell-mediated parietal cell destruction that clinically tends to progress rather than remit. The tolerance defect implicates the beta subunit: although H/K-ATPase alpha-subunit (ATP4A) mRNA is expressed in the thymus, thymic expression alone does not tolerize the pathogenic T-cell repertoire, and in the murine neonatal-thymectomy system it is the beta subunit (ATP4B), absent from the thymus, whose transgenic thymic expression prevents disease - so ATP4B behaves as the dominant autoantigen in mice. Whether ATP4B-specific T cells likewise dominate the surviving human repertoire, or precede ATP4A reactivity, has not been demonstrated. The murine disease induced by neonatal thymectomy is T-cell-mediated, and monogenic tolerance defects (AIRE/APECED, FOXP3/IPEX) produce autoimmune gastritis as part of polyautoimmunity. Two independent hypothesis-search runs (see notes) concur that this primary/central-tolerance account is best treated as one of several candidate initiating pathways feeding a shared effector cascade, rather than as an infection-independent sole origin.
Two independent hypothesis-search runs concur on PARTIALLY SUPPORTED: a claude_code report (kb/hypotheses/Autoimmune_Gastritis/canonical_primary_autoimmune_hk_atpase_origin/claude_code.md) and a deeper openscientist report (same directory, openscientist.md; 127 papers, 17 findings over 5 iterations). Both retain the CD4 T-cell / H+/K+ ATPase effector mechanism as CANONICAL but judge the etiological claim of a purely primary, infection-independent origin overstated. Each candidate initiating route is retained only at the evidence level it was actually demonstrated at: primary central-tolerance defect (murine neonatal thymectomy and transgenic thymic ATP4B; PMID:8393475), H. pylori molecular mimicry (human gastric T-cell cross-reactivity only; see alternative_hpylori_molecular_mimicry_origin), neonatal roseolovirus thymic disruption (experimental murine infection; not shown for human roseoloviruses), and peripheral checkpoint failure (anti-PD-1/anti-CTLA-4 gastritis, supported by deeply phenotyped single cases, which cannot establish absence of host predisposition or identity with sporadic AIG). The codex assessment sidecar in the hypothesis directory rejects three of the openscientist run's stronger readings: that one ATP4A-specific TCR is "necessary and sufficient" (the TxA23 experiment establishes sufficiency only; PMID:11449363), that a prospective progression cohort proves the autoimmune process is mechanistically self-sustaining regardless of trigger (clinical progression is not an immune-mechanism endpoint), and that PTPN22, HLA, ABO and IFIH1 form one confirmed AIG genetic architecture - PTPN22/HLA-DQB1/IL2RA/AIRE come from the pernicious-anemia GWAS (PMID:34145262) while ABO and IFIH1 come from a parietal-cell-antibody GWAS in a type 1 diabetes cohort, a different phenotype and sampling frame. The ATP4A/ATP4B tolerance correction flagged by both runs (alpha thymic expression does not tolerize; ATP4B is the thymus-absent dominant murine autoantigen) has been folded into the description above (PMID:16237067). The report's candidate GO identifiers were not curated: GO:0006968 is cellular defense response, not central tolerance, and GO:0002513 is tolerance induction to self antigen, not a generic peripheral-tolerance term. Follow-up recommended by openscientist: split into separate CANONICAL effector and qualified etiological-trigger hypotheses, and add an upstream "incomplete central tolerance to ATP4B" node.
Deep research
Claude Code 2026-07-01T08:02:42.111955
OpenScientist citations 37 citations 2026-07-01T14:50:02.872849
Show evidence (4 references)
PMID:9272282 SUPPORT Model Organism
"The murine disease induced by neonatal thymectomy is T cell-mediated."
The T-cell-mediated neonatal-thymectomy model supports a T-cell-driven autoimmune origin of gastritis.
PMID:16237067 SUPPORT Model Organism
"thymic mRNA expression alone cannot predict a contribution to thymic tolerance."
Corrects the tolerance framing - thymic H/K-ATPase alpha-subunit mRNA expression does not negatively select pathogenic T cells, so central tolerance to the alpha subunit is not protective; the beta subunit (absent from the thymus) is the dominant autoantigen.
PMID:8393475 SUPPORT Model Organism
"We show that transgenic expression of the gastric H/K ATPase beta subunit specifically prevents the onset of autoimmune gastritis after neonatal thymectomy."
The loss-of-function experiment behind the beta-subunit tolerance claim: forcing thymic expression of ATP4B, which is normally absent from the thymus, prevents neonatal-thymectomy gastritis in mice. This establishes ATP4B as a major T-cell target and a central-tolerance target in the murine system; it says nothing about the relative size of the ATP4B- and ATP4A-reactive repertoires in humans.
+ 1 more reference
Alternative H. pylori Molecular-Mimicry ("Hit-and-Run") Origin
alternative_hpylori_molecular_mimicry_origin ALTERNATIVE
Evidence balance 5 support 2 refute
Autoimmune gastritis is initiated by Helicobacter pylori infection via molecular mimicry between H. pylori antigens and the gastric H+/K+ ATPase, generating cross-reactive T- and B-cell responses that, through epitope spreading and bystander activation in a genetically susceptible host, become self-perpetuating autoimmunity and persist after the organism is cleared (established AIG is frequently H. pylori-negative). A corollary is that a subset of cases are reversible with early eradication. Causation in humans remains unproven and is the basis of a knowledge-gap discussion.
Two independent hypothesis-search runs concur on PARTIALLY SUPPORTED / UNRESOLVED: a claude_code report (kb/hypotheses/Autoimmune_Gastritis/alternative_hpylori_molecular_mimicry_origin/claude_code.md) and a deeper openscientist report (same directory, openscientist.md). H. pylori- to-H+/K+ ATPase cross-reactivity is documented at the T-cell level (cross-reactive gastric CD4 Th1 clones; urease beta-subunit homology; LPS Lewis-antigen mimicry; PMID:14568977), and active, not-yet-atrophic autoimmune corpus gastritis resolved after eradication in 64 of 80 patients in a retrospective, uncontrolled series (PMID:11549834). Neither result reaches the distinctive part of the hypothesis: reversibility achieved while the organism is being cleared is not evidence of a later self-perpetuating "hit-and-run" phase, and epitope spreading and persistence after clearance have no direct human evidence. The model is also refuted at the autoantibody level (antigastric autoantibodies do not absorb to H. pylori; PMID:10738313, PMID:11815766) and is non-general: H. pylori-naive AIG forms a distinct familial/autoimmune-enriched entity (ARIOSO n=1,598; PMID:38976374), and 29.3% of 75 atrophic autoimmune gastritis cases had no reactivity to any of 13 H. pylori antigens on multiplex serology (PMID:41484031). The wider "29-79% H. pylori-naive" range asserted by the openscientist report is not supported - its 21.1% figure was the proportion meeting a stringent multi-antigen positive cutoff, whose complement is not "no evidence of exposure", and its second source is not traceable in the report. Treg-depletion mouse models produce AIG with no infection, and some H. pylori-AIG associations may be inflated by diagnostic misclassification (urease-positive non-H. pylori bacteria overgrowing the achlorhydric stomach, shown in a referral series selected for repeated eradication failure, which cannot quantify bias in the wider literature). Retained ALTERNATIVE, best read as a subset-initiation mechanism whose full initiation-to-persistence sequence is unproven in humans. See the codex assessment sidecar in the hypothesis directory.
Deep research
Claude Code 2026-07-01T14:13:03.864853
OpenScientist citations 35 citations 2026-07-01T15:00:08.716366
Show evidence (7 references)
PMID:21174235 SUPPORT Human Clinical
"a role for Helicobacter pylori as an infective trigger through molecular mimicry"
States H. pylori as a candidate infective trigger of autoimmune gastritis via molecular mimicry.
PMID:42254085 SUPPORT Human Clinical
"Rapid eradication of H. pylori can significantly improve hematologic parameters and prevent the progression of autoimmune gastritis."
A reversible, H. pylori-attributable presentation is consistent with an infection-triggered origin in a subset of cases.
PMID:38976374 SUPPORT Human Clinical
"H. pylori -naive patients were more likely to have a first-degree family history of AIG (14.7% vs 8.9%; P = 0.012), type 1 diabetes mellitus (4.9% vs 2.3%; P = 0.025), and pernicious anemia (30.9% vs 21.1%; P = 0.003)."
The largest AIG cohort (n=1,598) identifies H. pylori-naive AIG as a distinct entity with stronger familial/autoimmune signatures, limiting the mimicry hypothesis to a subset rather than a general etiology.
+ 4 more references
Canonical Th1/IFN-gamma Effector Polarization
canonical_th1_effector_polarization CANONICAL
Evidence balance 6 support
The effector arm driving parietal-cell destruction has classically been modeled as Th1/IFN-gamma-polarized, based on murine neonatal-thymectomy and TCR-transgenic effector-transfer systems specific for the H+/K+ ATPase.
Two independent hypothesis-search runs concur on PARTIALLY SUPPORTED: a claude_code report (kb/hypotheses/Autoimmune_Gastritis/canonical_th1_effector_polarization/claude_code.md) and an openscientist report (same directory, openscientist.md). Both retain Th1/IFN-gamma as foundational and real: human gastric H+/K+ ATPase-reactive CD4 clones are predominantly Th1 and cytotoxic via perforin/Fas-FasL (PMID:11159878, PMID:15763992), and IFN-gamma directly kills murine gastric epithelium in organoids and is required for atrophy and metaplasia in TxA23 mice (PMID:30511397). The causal perturbations are model-specific and are weaker than the openscientist report states: anti-IFN-gamma treatment in the neonatal-thymectomy model cut gastritis incidence from 69% to 16% rather than abolishing disease (PMID:8766575), and in a transfer setting IFN-gamma-deficient T cells could still initiate mild disease (PMID:22777705). Neither run supports a Th1-exclusive model - it is one arm of a cooperative multi-cytokine / multi-cell-type program: CD8 T cells were the dominant IFN-gamma source in that polyclonal mouse model, IFN-gamma plus IL-17 are co-required for severe disease (PMID:22777705), and IL-13 acting through IL-4R-alpha is a separable required arm of the metaplastic transformation - though metaplasia was absent altogether in TxA23 x Ifng-/- mice, so IL-13 independence from IFN-gamma-associated atrophy across the whole trajectory is not established. The codex assessment sidecar in the hypothesis directory rejects two further readings carried by the report: that the PTPN22 pernicious-anemia risk variant wires patients toward Th1 over Th17 (this joins a PA GWAS locus association with Th1/Th17 phenotyping in genotyped healthy donors, and is a hypothesis rather than evidence about gastric polarization; the report also misstates the GWAS p value as 1.91e-10 rather than 1.91e-24), and that a null NK-depletion result rules out innate IFN-gamma sources. The intrinsic-factor-reactive pernicious-anemia compartment is mixed rather than Th17-dominant: the cited 94% is a combined "Th17 or Th1" figure (see emerging_th17_effector_polarization). Caveat: Th1 dominance is demonstrated most robustly in TCR-transgenic / monoclonal systems, which may overrepresent it relative to polyclonal disease, and all human immune data here are cross-sectional, so which effector population dominates over the human disease course is unresolved.
Pathograph links
CD4+ T Cell-Mediated Autoimmune Response Against the Gastric Proton Pump -> Parietal Cell Destruction and Oxyntic Atrophy Autoreactive CD4+ T cells and autoantibodies drive parietal cell apoptosis and loss.
Deep research
Claude Code citations 12 citations 2026-07-01T08:03:18.729534
OpenScientist citations 22 citations 2026-07-01T16:48:20.055197
Show evidence (6 references)
PMID:18641328 SUPPORT Model Organism
"We have evaluated the capacity of fully differentiated Th1, Th2, and Th17 cells derived from a mouse bearing a transgenic TCR specific for the gastric parietal cell antigen, H(+)K(+)-ATPase, to induce autoimmune gastritis after transfer to immunodeficient recipients."
Effector-transfer model in which Th1 (among other subsets) specific for the H+/K+ ATPase induces autoimmune gastritis.
PMID:15763992 SUPPORT Human Clinical
"The majority of the autoreactive T cell clones secreted IFN-gamma and showed a T helper 1 (Th1) profile."
Human gastric H+/K+ ATPase-reactive CD4 clones are predominantly Th1 (IFN-gamma) and cytotoxic, directly supporting the Th1 effector arm in human disease.
PMID:22777705 SUPPORT Model Organism
"both are required for the disease to progress to the late pathogenic stage that includes significant tissue disruption."
IFN-gamma and IL-17 are co-required for severe disease (and CD8 T cells are the dominant IFN-gamma source), qualifying a Th1-exclusive model.
+ 3 more references
Emerging Th17/IL-17 Effector Contribution
emerging_th17_effector_polarization EMERGING
Evidence balance 4 support
Human data show a gastric H+/K+ ATPase-specific Th17/IL-17 signature, and effector-transfer models show that Th1, Th2, and Th17 cells can each induce autoimmune gastritis with distinct pathology and differing susceptibility to regulatory T-cell suppression. Which effector arm dominates human disease, and whether it shifts over the disease course, is unresolved and carries therapeutic implications (e.g., anti-IL-17 blockade).
Two independent hypothesis-search runs concur on PARTIALLY SUPPORTED / retain EMERGING: a claude_code report (kb/hypotheses/Autoimmune_Gastritis/emerging_th17_effector_polarization/claude_code.md) and an openscientist report (same directory, openscientist.md). Both confirm a genuine Th17/IL-17 contribution (H+/K+ ATPase-specific gastric IL-17A/F production in all eight AIG patients tested; 94% of intrinsic-factor-reactive clones in a combined "Th17 or Th1" category; Th17 transfer gives the most severe, Treg-resistant gastritis in the TxA23 model). The openscientist run went on to propose a wholesale reframing of the effector mechanism - epithelial IL-17RA signaling as protective, IL-21 as the real pathogenic Th17-derived mediator, and anti-IL-17 blockade as contraindicated - and the codex assessment sidecar in the hypothesis directory rejects that reframing on its sources. The IL-17RA results come from gastrointestinal epithelial Il17ra deletion during H. pylori infection, not sterile autoimmune gastritis and not parietal-cell-specific deletion or apoptosis; the "increased autoantibody production" in Il17ra-deficient mice was in fact enhanced H. pylori-specific antibody, not anti-H+/K+ ATPase or anti-intrinsic-factor autoantibody; and no IL-21 perturbation has been carried out in AIG at all, so the IL-21 bridge remains an untested hypothesis. There is no human anti-IL-17 AIG study and no AIG animal experiment comparing IL-17 blockade with control, so protective IL-17 signaling in H. pylori infection and gastric carcinogenesis raises a real, unresolved safety question about anti-IL-17 therapy in AIG rather than establishing a contraindication. What survives: a Th17 contribution is real but its terminal tissue-damage mechanism is undetermined, direct IL-17A/F epithelial cytotoxicity is not established, STAT3 perturbation is a promising but pleiotropic and model-specific lead (PMID:40471463), Th1 remains the more extensively validated axis, and which arm dominates by disease stage is unresolved because all human evidence here is small and cross-sectional. The report's candidate ontology block was not curated: CL:0000163 is endocrine cell (parietal cell is CL:0000162, already used above), GO:0032623 is interleukin-2 production rather than interleukin-21 production, and its proposed MONDO identifiers resolve to unrelated disorders.
Pathograph links
CD4+ T Cell-Mediated Autoimmune Response Against the Gastric Proton Pump -> Parietal Cell Destruction and Oxyntic Atrophy Autoreactive CD4+ T cells and autoantibodies drive parietal cell apoptosis and loss.
Deep research
Claude Code citations 10 citations 2026-07-01T14:13:13.539858
OpenScientist citations 24 citations 2026-07-01T16:33:30.602581
Show evidence (4 references)
PMID:35911678 SUPPORT Human Clinical
"Gastric LPMCs from all AIG patients, but not those from HCs, were activated by H+/K+-ATPase and were able to proliferate and produce high levels of IL-17A and IL-17F."
Human gastric T cells produce IL-17A/IL-17F on H+/K+ ATPase stimulation, evidencing a Th17 effector contribution.
PMID:18641328 SUPPORT Model Organism
"We have evaluated the capacity of fully differentiated Th1, Th2, and Th17 cells derived from a mouse bearing a transgenic TCR specific for the gastric parietal cell antigen, H(+)K(+)-ATPase, to induce autoimmune gastritis after transfer to immunodeficient recipients."
Th17 effector cells can independently induce autoimmune gastritis in the transfer model, supporting an emerging Th17 arm.
PMID:31080562 SUPPORT Human Clinical
"Most of these clones (94%) showed a T helper 17 or T helper 1 profile."
In pernicious anemia, 94% of intrinsic-factor-specific gastric CD4 clones fell into a combined "Th17 or Th1" category, evidencing a Th17 contribution in the intrinsic-factor-reactive compartment. The combined figure does not show that Th17 outnumbers Th1, so the compartment is mixed rather than Th17-dominant.
+ 1 more reference
?

Discussions and Knowledge Gaps

4
Do murine autoimmune-gastritis models (neonatal thymectomy, H+/K+ ATPase immunization, and TCR-transgenic effector-transfer systems) faithfully reproduce human autoimmune gastritis, or do they capture only the initiation and parietal-cell-destruction biology while failing to model the human-specific downstream trajectory of chronic ECL-cell hyperplasia progressing to type 1 gastric neuroendocrine tumors, long-term gastric adenocarcinoma risk, and polyautoimmune clustering (thyroid, type 1 diabetes, vitiligo)?
HUMAN MODEL MISMATCH OPEN hmm_aig_mouse_model_neoplastic_trajectory
Attached to
pathophysiology#CD4+ T Cell-Mediated Autoimmune Response Against the Gastric Proton Pump pathophysiology#Hypergastrinemia and ECL Cell Hyperplasia
Mouse models robustly recapitulate the core autoantigen (H+/K+ ATPase), the CD4 T-cell-mediated destructive mechanism, and atrophic/metaplastic histology, and they are the primary source of mechanistic detail (effector-subset pathogenicity and Treg-dependent tolerance). However, short-lived rodent models less consistently reproduce the chronic hypergastrinemia -> ECL hyperplasia -> type 1 gastric NET sequence and the decades-long adenocarcinoma risk that dominate human clinical management, and single-antigen mouse systems do not intrinsically model human polyautoimmune comorbidity. Consequently the neoplastic-complication arm of the human entry rests on human observational data rather than on validated model mechanism.
Proposed experiments
Longitudinal ECL-to-NET progression in a chronic hypergastrinemic AIG model
exp_aig_longterm_ecl_neoplasia
In a chronic autoimmune-gastritis model with sustained achlorhydria and hypergastrinemia, longitudinally quantify the ECL-cell hyperplasia -> dysplasia -> type 1 gastric NET sequence and adenocarcinoma incidence over extended timeframes, mapped onto human histologic staging.
Model systems
Chronic murine autoimmune gastritis model
Long-lived mouse model with sustained achlorhydria and hypergastrinemia (e.g., effector-transfer or gastrin-clamped systems) followed for ECL-cell neoplastic progression.
OTHER
Decision criterion
Whether comparable degrees and durations of hypergastrinemia reproduce the human ECL-to-NET-to-adenocarcinoma sequence.
Supporting outcome
  • Faithful reproduction would validate the human neoplastic trajectory as a direct consequence of the modeled autoimmune-achlorhydria-hypergastrinemia axis.
Refuting outcome
  • Failure to progress despite equivalent hypergastrinemia would indicate human-specific ECL/gastric-epithelial biology not captured by rodent models.
What initiates the loss of tolerance in the common sporadic (polygenic) form of autoimmune gastritis? H. pylori molecular mimicry is the leading trigger hypothesis, but established disease is usually H. pylori-negative and human causation is unproven; other triggers (viral, unidentified) and the gene-environment "second-hit" model (a PTPN22/HLA/AIRE background lowering the threshold for infection-triggered mimicry and epitope spreading) remain unvalidated in humans.
KNOWLEDGE GAP OPEN gap_aig_sporadic_tolerance_trigger
Attached to
pathophysiology#CD4+ T Cell-Mediated Autoimmune Response Against the Gastric Proton Pump
The trigger question directly gates the two competing origin hypotheses (primary autoimmunity vs. H. pylori mimicry) and determines whether a modifiable environmental exposure exists. It cannot be resolved by the current snippet-supported human associations, which are cross-sectional and confounded by the frequent absence of the organism at diagnosis.
Is the autoimmune process still active and pharmacologically targetable at the time of diagnosis, or is it effectively "burnt out"? There is no disease-modifying therapy for autoimmune gastritis - management is micronutrient replacement and surveillance - and it is unknown whether early immunomodulation (regulatory T-cell restoration or Th17/IL-17 blockade) could halt progression to atrophy, pernicious anemia, and neoplasia.
KNOWLEDGE GAP OPEN gap_aig_disease_modifying_therapy_active_window
Attached to
pathophysiology#CD4+ T Cell-Mediated Autoimmune Response Against the Gastric Proton Pump
Whether the effector response persists at a targetable level once corpus atrophy is established determines if immunomodulatory therapy is even mechanistically plausible; the emerging Th17 arm makes anti-IL-17 blockade a concrete but untested candidate. That candidate carries an unresolved safety question rather than a straightforward rationale: IL-17RA signaling on gastrointestinal epithelium is protective in H. pylori infection models and IL-17 signaling restrains gastric carcinogenesis, yet no anti-IL-17 study - human or animal - has been performed in autoimmune gastritis, so the net effect of blockade in this disease is unknown in both directions.
What is the natural history and timeline of autoimmune gastritis from the earliest seropositive ("potential AIG") phase through corpus atrophy, pernicious anemia, and neoplastic complications, and what distinguishes the poorly-studied pediatric-onset subgroup?
KNOWLEDGE GAP OPEN gap_aig_natural_history_pediatric
Attached to
pathophysiology#Parietal Cell Destruction and Oxyntic Atrophy
The pre-atrophic seropositive phase is the clinically actionable window for early detection, but the rate and determinants of progression to irreversible atrophy and to neoplasia are not established prospectively, and the pediatric-onset subgroup's long-term course is largely unstudied.
⚙

Pathophysiology

4
CD4+ T Cell-Mediated Autoimmune Response Against the Gastric Proton Pump
The central pathogenic event is a CD4+ T helper (Th1/Th17)-polarized autoimmune response directed against the alpha (ATP4A) and beta (ATP4B) subunits of the gastric H+/K+ ATPase expressed by parietal cells. Autoreactive T cells and parietal cell autoantibodies target the oxyntic mucosa of the gastric corpus and fundus, sparing the antrum. Molecular mimicry with Helicobacter pylori antigens has been proposed as an initiating trigger.
Canonical Th1/IFN-gamma Effector Polarization Emerging Th17/IL-17 Effector Contribution
CD4+ T helper cell CL:0000492 ↑ INCREASED Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves increased CD4+ T helper cell, annotated with CD4-positive helper T cell (CL:0000492). CL:0000492 is a cell type from the Cell Ontology. parietal cell CL:0000162 ↓ DECREASED Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves decreased parietal cell (CL:0000162). CL:0000162 is a cell type from the Cell Ontology.
adaptive immune response against the H+/K+ ATPase GO:0002250 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased adaptive immune response against the H+/K+ ATPase, annotated with adaptive immune response (GO:0002250). GO:0002250 is a biological process from the Gene Ontology. parietal cell apoptosis GO:0006915 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased parietal cell apoptosis, annotated with apoptotic process (GO:0006915). GO:0006915 is a biological process from the Gene Ontology.
Downstream
Parietal Cell Destruction and Oxyntic Atrophy Autoreactive CD4+ T cells and autoantibodies drive parietal cell apoptosis and loss. Canonical Th1/IFN-gamma Effector Polarization Emerging Th17/IL-17 Effector Contribution
Show evidence (4 references)
PMID:35911678 SUPPORT Human Clinical
"The gastric parietal cell proton pump H+/K+-adenosine triphosphatase (H+/K+-ATPase) is the major autoantigen in AIG."
Identifies the gastric H+/K+ ATPase as the principal autoantigen targeted in autoimmune gastritis.
PMID:35911678 SUPPORT Human Clinical
"Gastric LPMCs from all AIG patients, but not those from HCs, were activated by H+/K+-ATPase and were able to proliferate and produce high levels of IL-17A and IL-17F."
Demonstrates antigen-specific gastric T cell activation and proliferation in response to the H+/K+ ATPase autoantigen in AIG patients.
PMID:42367768 SUPPORT Human Clinical
"Autoimmune gastritis (AIG) is a chronic, organ-specific autoimmune disease characterized by the immune-mediated destruction of gastric parietal cells, leading to impaired acid secretion, vitamin B12 deficiency, and an increased risk of gastric malignancies."
Establishes immune-mediated parietal cell destruction as the central pathogenic mechanism of autoimmune gastritis.
+ 1 more reference
Parietal Cell Destruction and Oxyntic Atrophy
Immune-mediated destruction of parietal cells leads to progressive atrophy of the oxyntic (acid-secreting) mucosa restricted to the corpus and fundus. Loss of parietal cells abolishes both gastric acid and intrinsic factor secretion, and the mucosa undergoes pseudopyloric and intestinal metaplasia.
parietal cell CL:0000162 ∅ ABSENT Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves absent parietal cell (CL:0000162). CL:0000162 is a cell type from the Cell Ontology.
gastric acid secretion GO:0001696 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased gastric acid secretion (GO:0001696). GO:0001696 is a biological process from the Gene Ontology.
Downstream
Atrophic Gastritis Progressive parietal cell loss produces corpus-restricted atrophic gastritis.
Achlorhydria Parietal cell loss abolishes gastric acid secretion.
Iron Deficiency Anemia Loss of gastric acid impairs acid-dependent dietary iron absorption, causing iron deficiency anemia.
Intrinsic Factor Deficiency and B12 Malabsorption Parietal cell loss abolishes intrinsic factor secretion.
Hypergastrinemia and ECL Cell Hyperplasia Loss of luminal acid removes negative feedback on antral gastrin release.
Gastric Adenocarcinoma Oxyntic atrophy with intestinal metaplasia forms a precancerous field predisposing to intestinal-type gastric adenocarcinoma.
Show evidence (1 reference)
PMID:28102858 SUPPORT Human Clinical
"Atrophic body gastritis (AGB) is the pathological lesion of autoimmune gastritis, characterized by the disappearance of oxyntic mucosa"
Confirms that parietal-cell destruction produces corpus-restricted disappearance of the oxyntic mucosa (atrophic body gastritis).
Intrinsic Factor Deficiency and B12 Malabsorption
Loss of intrinsic factor (encoded by CBLIF/GIF) secreted by parietal cells, compounded by anti-intrinsic factor autoantibodies, prevents ileal absorption of dietary vitamin B12 (cobalamin), causing systemic cobalamin deficiency and pernicious anemia.
parietal cell CL:0000162 ∅ ABSENT Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves absent parietal cell (CL:0000162). CL:0000162 is a cell type from the Cell Ontology.
Downstream
Pernicious Anemia Cobalamin deficiency impairs erythropoiesis, causing megaloblastic anemia.
Peripheral Neuropathy Cobalamin deficiency causes neurological injury including subacute combined degeneration.
Glossitis Cobalamin deficiency causes atrophic glossitis.
Show evidence (2 references)
PMID:31080562 SUPPORT Human Clinical
"The intrinsic factor is the major humoral autoantigen in pernicious anemia/autoimmune gastritis."
Establishes intrinsic factor as the major humoral autoantigen whose loss (and autoantibody targeting) causes the B12 malabsorption of pernicious anemia.
PMID:21174235 SUPPORT Human Clinical
"megaloblastic pernicious anemia arising from vitamin B12 deficiency"
Links the intrinsic-factor-dependent vitamin B12 deficiency to megaloblastic pernicious anemia.
Hypergastrinemia and ECL Cell Hyperplasia
Achlorhydria removes the acid-mediated negative feedback on antral G cells, producing marked hypergastrinemia. Chronically elevated gastrin is trophic for enterochromaffin-like (ECL) cells in the corpus, driving ECL cell hyperplasia that can progress through dysplasia to type 1 gastric neuroendocrine tumors.
antral G cell CL:0000508 ↑ INCREASED Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves increased antral G cell, annotated with type G enteroendocrine cell (CL:0000508). CL:0000508 is a cell type from the Cell Ontology. enterochromaffin-like cell CL:0000504 ↑ INCREASED Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves increased enterochromaffin-like cell (CL:0000504). CL:0000504 is a cell type from the Cell Ontology.
Downstream
Hypergastrinemia Achlorhydria-driven loss of feedback on antral G cells produces marked hypergastrinemia.
Gastric Neuroendocrine Tumor Sustained gastrin drive promotes ECL hyperplasia to neoplasia.
Show evidence (2 references)
PMID:31963924 SUPPORT Human Clinical
"tumorigenesis is mediated by gastrin's effects on the CCK2R-receptor on ECL-cells that in turn leads to hyperplasia, dysplasia, and finally neoplasia"
Describes the gastrin-CCK2R trophic pathway by which chronic hypergastrinemia drives ECL cell hyperplasia, dysplasia, and neoplasia.
PMID:34476276 SUPPORT Human Clinical
"This leads to the absence of gastric acid production, which causes compensatory hyperplasia of gastric antral G-cells leading to hypergastrinemia. The excess gastrin binds to enterochromaffin-like cells causing hyperplasia, which may progress to dysplasia and rarely to gastric neuroendocrine tumors."
Human case documenting the full AIG sequence of achlorhydria, antral G-cell hyperplasia, hypergastrinemia, and ECL hyperplasia-dysplasia-neoplasia.
✶

Histopathology

2
Oxyntic (Corpus-Restricted) Gland Atrophy
Corpus- and fundus-restricted atrophy of the oxyntic (acid-secreting) mucosa with loss of parietal and chief cells and a lymphoplasmacytic infiltrate; the antral mucosa is characteristically spared. This is the diagnostic pathological lesion of autoimmune gastritis (staged by the Sydney System / OLGA).
Show evidence (1 reference)
PMID:28102858 SUPPORT Human Clinical
"Atrophic body gastritis (AGB) is the pathological lesion of autoimmune gastritis, characterized by the disappearance of oxyntic mucosa"
Corpus-restricted disappearance of the oxyntic mucosa is the defining diagnostic pathological lesion of autoimmune gastritis.
Enterochromaffin-Like (ECL) Cell Hyperplasia
Hypergastrinemia-driven linear and nodular hyperplasia of corpus enterochromaffin-like (ECL) cells, which can progress through dysplasia to type 1 gastric neuroendocrine tumors.
Show evidence (1 reference)
PMID:34476276 SUPPORT Human Clinical
"The excess gastrin binds to enterochromaffin-like cells causing hyperplasia, which may progress to dysplasia and rarely to gastric neuroendocrine tumors."
Documents ECL cell hyperplasia progressing through dysplasia to neuroendocrine tumor in autoimmune gastritis.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Autoimmune Gastritis Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

9
Blood 2
Pernicious Anemia FREQUENT Megaloblastic anemia HP:0001889 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Megaloblastic anemia (HP:0001889). HP:0001889 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:42367768 SUPPORT Human Clinical
"Autoimmune gastritis (AIG) is a chronic, organ-specific autoimmune disease characterized by the immune-mediated destruction of gastric parietal cells, leading to impaired acid secretion, vitamin B12 deficiency, and an increased risk of gastric malignancies."
Loss of intrinsic factor from parietal cell destruction causes vitamin B12 deficiency, the basis of pernicious (megaloblastic) anemia.
PMID:34829460 SUPPORT Human Clinical
"The clinical manifestation of the disease includes possible variants such as gastrointestinal, hematological (first of all, the formation of iron deficiency and B12-deficiency anemia), and neurological variants."
Lists B12-deficiency (megaloblastic/pernicious) anemia as a core hematological manifestation of chronic autoimmune gastritis.
Iron Deficiency Anemia FREQUENT HP:0001891 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Iron deficiency anemia (HP:0001891). HP:0001891 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:34829460 SUPPORT Human Clinical
"The clinical manifestation of the disease includes possible variants such as gastrointestinal, hematological (first of all, the formation of iron deficiency and B12-deficiency anemia), and neurological variants."
Identifies iron deficiency anemia as a leading hematological presentation of chronic autoimmune gastritis, often preceding B12 deficiency.
Digestive 3
Atrophic Gastritis OBLIGATE HP:0002582 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Atrophic gastritis (HP:0002582). HP:0002582 is a phenotype from the Human Phenotype Ontology.
Achlorhydria VERY_FREQUENT HP:0032448 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Achlorhydria (HP:0032448). HP:0032448 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:42367768 SUPPORT Human Clinical
"Autoimmune gastritis (AIG) is a chronic, organ-specific autoimmune disease characterized by the immune-mediated destruction of gastric parietal cells, leading to impaired acid secretion, vitamin B12 deficiency, and an increased risk of gastric malignancies."
Parietal cell destruction abolishes gastric acid secretion, producing hypochlorhydria and achlorhydria.
Gastric Adenocarcinoma VERY_RARE HP:0033770 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Gastric adenocarcinoma (HP:0033770). HP:0033770 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:42367768 SUPPORT Human Clinical
"we explore precision risk stratification models for gastric neuroendocrine tumors (gNETs) and gastric adenocarcinoma, emphasizing the roles of endoscopic surveillance and molecular biomarkers"
Identifies gastric adenocarcinoma as a neoplastic risk of autoimmune gastritis requiring risk stratification and surveillance.
Endocrine 2
Hypergastrinemia VERY_FREQUENT HP:0500167 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypergastrinemia (HP:0500167). HP:0500167 is a phenotype from the Human Phenotype Ontology.
Gastric Neuroendocrine Tumor OCCASIONAL Gastric carcinoid tumor HP:6000898 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Gastric carcinoid tumor (HP:6000898). HP:6000898 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:31963924 SUPPORT Human Clinical
"persistent hypergastrinemia, generally accepted as causing g-NETs in CAG and ZES"
Persistent hypergastrinemia in chronic atrophic gastritis is the accepted cause of gastric neuroendocrine tumors (carcinoids).
PMID:42367768 SUPPORT Human Clinical
"we explore precision risk stratification models for gastric neuroendocrine tumors (gNETs) and gastric adenocarcinoma, emphasizing the roles of endoscopic surveillance and molecular biomarkers"
Confirms gastric neuroendocrine tumors and adenocarcinoma as the neoplastic risks of autoimmune gastritis that drive endoscopic surveillance.
Head and Neck 1
Glossitis OCCASIONAL HP:0000206 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Glossitis (HP:0000206). HP:0000206 is a phenotype from the Human Phenotype Ontology.
Nervous System 1
Peripheral Neuropathy OCCASIONAL HP:0009830 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Peripheral neuropathy (HP:0009830). HP:0009830 is a phenotype from the Human Phenotype Ontology.
🧬

Genetic Associations

2
ATP4A (Risk factor)
Gene: ATP4A hgnc:819 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is ATP4A (hgnc:819). hgnc:819 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (1 reference)
PMID:28102858 SUPPORT Human Clinical
"This study aimed to assess autoantibodies against ATP4A and ATP4B subunits of parietal cells H+, K+-ATPase in atrophic body gastritis patients and controls."
Identifies the ATP4A subunit of the parietal cell H+/K+ ATPase as a target autoantigen in autoimmune (atrophic body) gastritis.
ATP4B (Risk factor)
Gene: ATP4B hgnc:820 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is ATP4B (hgnc:820). hgnc:820 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (1 reference)
PMID:28102858 SUPPORT Human Clinical
"This study aimed to assess autoantibodies against ATP4A and ATP4B subunits of parietal cells H+, K+-ATPase in atrophic body gastritis patients and controls."
Identifies the ATP4B subunit of the parietal cell H+/K+ ATPase as a target autoantigen in autoimmune (atrophic body) gastritis.
💊

Medical Actions

7
Vitamin B12 Replacement
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: vitamin B12 CHEBI:176843 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses vitamin B12 (CHEBI:176843). CHEBI:176843 is a therapeutic agent from Chemical Entities of Biological Interest.
Parenteral (or high-dose oral) cobalamin replacement corrects and prevents the hematologic and neurologic consequences of B12 deficiency in pernicious anemia.
Iron Replacement
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: iron(2+) CHEBI:29033 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses iron(2+) (CHEBI:29033). CHEBI:29033 is a therapeutic agent from Chemical Entities of Biological Interest.
Oral or intravenous iron to correct the iron deficiency anemia that commonly precedes B12 deficiency in autoimmune gastritis.
Endoscopic Surveillance
Action: esophagogastroduodenoscopyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is esophagogastroduodenoscopy (NCIT:C78144). NCIT:C78144 is a clinical intervention from the NCI Thesaurus. Ontology label: Esophagogastroduodenoscopy NCIT:C78144
Periodic upper endoscopy with biopsy to monitor for gastric neuroendocrine tumors and gastric adenocarcinoma in patients with atrophic body gastritis.
Show evidence (1 reference)
PMID:42367768 SUPPORT Human Clinical
"we explore precision risk stratification models for gastric neuroendocrine tumors (gNETs) and gastric adenocarcinoma, emphasizing the roles of endoscopic surveillance and molecular biomarkers"
Supports endoscopic surveillance as the management strategy for the gastric neoplasia risk in autoimmune gastritis.
Netazepide (Gastrin/CCK2 Receptor Antagonist)
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: netazepide NCIT:C87692 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses netazepide (NCIT:C87692). NCIT:C87692 is a therapeutic agent from the NCI Thesaurus.
Platform: Small molecule
Netazepide is an investigational oral gastrin/cholecystokinin-2 receptor (CCK2R) antagonist that blocks the trophic gastrin signal driving ECL cell proliferation, shrinking and eradicating type 1 gastric neuroendocrine tumors and normalizing chromogranin A in autoimmune atrophic gastritis.
Target Phenotypes: Gastric carcinoid tumor HP:6000898 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Gastric carcinoid tumor (HP:6000898). HP:6000898 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:27704617 SUPPORT Human Clinical
"Netazepide, a gastrin/cholecystokinin 2 receptor antagonist, once daily for 12 weeks reduced the number of tumours and size of the largest one in 16 patients with autoimmune chronic atrophic gastritis (CAG), achlorhydria, hypergastrinaemia and multiple gastric neuroendocrine tumours (type 1 gastric NETs)"
Human trial showing the gastrin/CCK2R antagonist netazepide reduces type 1 gastric NETs in autoimmune atrophic gastritis by blocking the trophic gastrin signal.
Endoscopic Resection of Gastric Neuroendocrine Tumors
Action: Endoscopic Mucosal ResectionNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Endoscopic Mucosal Resection (NCIT:C103242). NCIT:C103242 is a clinical intervention from the NCI Thesaurus. NCIT:C103242
Endoscopic resection is the first-line treatment for small, localized type 1 gastric neuroendocrine tumors; larger or higher-risk lesions are referred for surgical resection.
Target Phenotypes: Gastric carcinoid tumor HP:6000898 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Gastric carcinoid tumor (HP:6000898). HP:6000898 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:42228075 SUPPORT Human Clinical
"For type I gastric neuroendocrine neoplasms (gNEN) larger than 1 cm endoscopic resection should be performed, whereas for tumors larger than 2 cm surgical resection should be carried out."
States that endoscopic resection is the treatment for type 1 gastric neuroendocrine tumors, with surgery reserved for larger lesions.
Somatostatin Analog Therapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: octreotide CHEBI:7726 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses octreotide (CHEBI:7726). CHEBI:7726 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Peptide
Somatostatin analogs (e.g., octreotide, lanreotide) suppress gastrin release and are antiproliferative for type 1 gastric neuroendocrine tumors, reducing tumor size in patients with multiple or recurrent lesions.
Target Phenotypes: Gastric carcinoid tumor HP:6000898 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Gastric carcinoid tumor (HP:6000898). HP:6000898 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:40503415 SUPPORT Human Clinical
"Type I treatment usually involves endoscopic resection (ER), with surgical resection for recurrence. Somatostatin analogs (SSAs) can reduce tumor size, and the prognosis is generally excellent."
Supports somatostatin analogs as a size-reducing therapy for type 1 gastric neuroendocrine tumors.
Helicobacter pylori Eradication
Action: antimicrobial agent therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is antimicrobial agent therapy, annotated with Antibiotic Therapy (NCIT:C15620). NCIT:C15620 is a clinical intervention from the NCI Thesaurus. Ontology label: Antibiotic Therapy NCIT:C15620
When Helicobacter pylori infection coexists with autoimmune gastritis, eradication therapy is recommended; in the subset where H. pylori contributes to the gastritis it can improve hematologic parameters and slow progression.
Show evidence (1 reference)
PMID:42254085 SUPPORT Human Clinical
"Rapid eradication of H. pylori can significantly improve hematologic parameters and prevent the progression of autoimmune gastritis."
Supports H. pylori eradication as a management step that can improve hematologic parameters and slow progression when the organism is present.
🌍

Environmental Factors

1
Helicobacter pylori Infection
exposure to Helicobacter pylori ECTO:3000003 Environmental Conditions, Treatments and Exposures Ontology (ECTO) Relation: this environmental factor is this exposure This environmental factor is exposure to Helicobacter pylori (ECTO:3000003). ECTO:3000003 is an exposure from the Environmental Conditions, Treatments and Exposures Ontology.
H. pylori infection is proposed to trigger autoimmune gastritis through molecular mimicry between H. pylori antigens and the gastric H+/K+ ATPase, although autoimmune gastritis characteristically persists after the organism is no longer detectable.
Show evidence (1 reference)
PMID:21174235 SUPPORT Human Clinical
"a role for Helicobacter pylori as an infective trigger through molecular mimicry"
Supports H. pylori as a candidate infective trigger of autoimmune gastritis via molecular mimicry with the gastric H+/K+ ATPase.
🔬

Biochemical Markers

4
Anti-Parietal Cell Antibody (Increased)
Show evidence (1 reference)
PMID:28102858 SUPPORT Human Clinical
"Circulating autoantibodies targeting the H+/K+-ATPase proton pump of gastric parietal cells are considered markers of autoimmune gastritis"
Establishes anti-parietal cell (anti-H+/K+ ATPase) autoantibodies as the serological marker of autoimmune gastritis.
Anti-Intrinsic Factor Antibody (Increased)
Serum Gastrin (Increased)
Show evidence (1 reference)
PMID:40831016 SUPPORT Human Clinical
"a reduced PGI/PGII ratio combined with elevated G-17 levels provided excellent discrimination"
Elevated gastrin-17 accompanies corpus atrophic gastritis, reflecting the achlorhydria-driven hypergastrinemia of autoimmune gastritis.
Serum Pepsinogen I (Decreased)
Show evidence (1 reference)
PMID:40831016 SUPPORT Human Clinical
"a reduced PGI/PGII ratio combined with elevated G-17 levels provided excellent discrimination"
A reduced pepsinogen I/II ratio (with elevated gastrin-17) discriminates corpus atrophic gastritis, reflecting oxyntic gland loss.
📊

Prevalence

1
General population
2.0
Show evidence (1 reference)
PMID:28102858 SUPPORT Human Clinical
"prevalence of ~2% in the general population and up to 10% in patients with other autoimmune diseases, such as type I diabetes or autoimmune thyroid disease."
Establishes ~2% general-population prevalence, rising to ~10% among patients with other autoimmune diseases (thyrogastric clustering).
📊

Related Datasets

3
Comprehensive gene expression analysis using gastric mucosa with autoimmune gastritis geo:GSE233973
In this study, we aimed to reveal whether gastric mucosa with AIG has a specific gene expression profile, involving in its histology and chronic inflammation. To approach this, we performed comprehensive analysis of gene expression using gastric mucosa with atuoimmune gastritis, that with H. pylori-associated gastritis and healthy mucosa without any inflammation. Potential mechanisms of the gene expression changes in gastric mucosa with AIG were also explored.
human MICROARRAY n=36
PMID:37962678
Identified by GEO DataSets index search for Autoimmune Gastritis (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-07-31. Title, sample count, and organism are GEO's own values.
Genome-wide DNA methylation analysis of gastric mucosa with autoimmune gastritis geo:GSE178925
DNA methylation in gastric mucosa with autoimmune gastritis and H. pylori-associated gastritis and normal gastric mucosa
human METHYLATION n=24
PMID:35034200
Identified by GEO DataSets index search for Autoimmune Gastritis (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-07-31. Title, sample count, and organism are GEO's own values.
Unveiling Cancer-Related Metaplastic Cells in Both Helicobacter pylori Infection and Autoimmune Gastritis geo:GSE271866
We used 10X 5' single cell RNA sequencing (scRNAseq) technology to examine the transcriptional profiles of distinct gastric metaplastic cell types within the gastric corpus of mice chronically infected with Helicobacter pylori or chronically inflamed with autoimmune gastritis and humans with autoimmune gastritis.
SINGLE CELL RNA SEQ n=7
PMID:39236896
Identified by GEO DataSets index search for Autoimmune Gastritis (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-07-31. Title, sample count, and organism are GEO's own values.
{ }

Source YAML

click to show 
name: Autoimmune Gastritis
creation_date: "2026-07-01T00:00:00Z"
category: Complex
disease_term:
  preferred_term: autoimmune gastritis
  term:
    id: MONDO:0031014
    label: autoimmune gastritis
description: >
  Autoimmune gastritis (AIG) is an organ-specific autoimmune disease characterized
  by chronic, corpus-restricted (oxyntic) atrophic gastritis driven by a
  CD4+ T cell-mediated immune response against the gastric parietal cell H+/K+
  ATPase (the gastric proton pump, encoded by ATP4A and ATP4B). Immune destruction
  of parietal cells causes loss of gastric acid secretion (hypochlorhydria and
  ultimately achlorhydria) and loss of intrinsic factor, producing vitamin B12
  malabsorption and pernicious anemia. Achlorhydria removes the negative feedback
  on antral G cells, causing hypergastrinemia, which drives enterochromaffin-like
  (ECL) cell hyperplasia and predisposes to type 1 gastric neuroendocrine tumors
  (carcinoids). Corpus atrophy with intestinal metaplasia also increases the risk
  of gastric adenocarcinoma. AIG frequently clusters with other autoimmune
  disorders, especially autoimmune thyroid disease (thyrogastric syndrome) and
  type 1 diabetes mellitus.
synonyms:
- Autoimmune atrophic gastritis
- Type A gastritis
- Autoimmune metaplastic atrophic gastritis
references:
- reference: PMID:42367768
  title: "Autoimmune gastritis: a comprehensive review of pathophysiology, risk stratification, and management."
- reference: PMID:34829460
  title: "Chronic Autoimmune Gastritis: Modern Diagnostic Principles."
- reference: PMID:31864909
  title: "Thyro-entero-gastric autoimmunity: Pathophysiology and implications for patient management."
- reference: PMID:35911678
  title: "Gastric Th17 Cells Specific for H+/K+-ATPase and Serum IL-17 Signature in Gastric Autoimmunity."
- reference: PMID:31963924
  title: "Proton Pump Inhibitor Use, Hypergastrinemia, and Gastric Carcinoids-What Is the Relationship?"
- reference: PMID:21174235
  title: "Cutting edge issues in autoimmune gastritis."
- reference: PMID:28102858
  title: "Luminescent Immunoprecipitation System (LIPS) for Detection of Autoantibodies Against ATP4A and ATP4B Subunits of Gastric Proton Pump H+,K+-ATPase in Atrophic Body Gastritis Patients."
parents:
- Gastritis
- Autoimmune disease
classifications:
  harrisons_chapter:
  - classification_value: GASTROINTESTINAL
  - classification_value: IMMUNE_RHEUMATOLOGIC
pathophysiology:
- name: CD4+ T Cell-Mediated Autoimmune Response Against the Gastric Proton Pump
  description: >
    The central pathogenic event is a CD4+ T helper (Th1/Th17)-polarized
    autoimmune response directed against the alpha (ATP4A) and beta (ATP4B)
    subunits of the gastric H+/K+ ATPase expressed by parietal cells. Autoreactive
    T cells and parietal cell autoantibodies target the oxyntic mucosa of the
    gastric corpus and fundus, sparing the antrum. Molecular mimicry with
    Helicobacter pylori antigens has been proposed as an initiating trigger.
  cell_types:
  - preferred_term: CD4+ T helper cell
    term:
      id: CL:0000492
      label: CD4-positive helper T cell
    modifier: INCREASED
  - preferred_term: parietal cell
    term:
      id: CL:0000162
      label: parietal cell
    modifier: DECREASED
  biological_processes:
  - preferred_term: adaptive immune response against the H+/K+ ATPase
    term:
      id: GO:0002250
      label: adaptive immune response
    modifier: INCREASED
  - preferred_term: parietal cell apoptosis
    term:
      id: GO:0006915
      label: apoptotic process
    modifier: INCREASED
  downstream:
  - target: Parietal Cell Destruction and Oxyntic Atrophy
    description: Autoreactive CD4+ T cells and autoantibodies drive parietal cell apoptosis and loss.
    hypothesis_groups:
    - canonical_th1_effector_polarization
    - emerging_th17_effector_polarization
  evidence:
  - reference: PMID:35911678
    reference_title: "Gastric Th17 Cells Specific for H+/K+-ATPase and Serum IL-17 Signature in Gastric Autoimmunity."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The gastric parietal cell proton pump H+/K+-adenosine triphosphatase (H+/K+-ATPase) is the major autoantigen in AIG."
    explanation: Identifies the gastric H+/K+ ATPase as the principal autoantigen targeted in autoimmune gastritis.
  - reference: PMID:35911678
    reference_title: "Gastric Th17 Cells Specific for H+/K+-ATPase and Serum IL-17 Signature in Gastric Autoimmunity."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Gastric LPMCs from all AIG patients, but not those from HCs, were activated by H+/K+-ATPase and were able to proliferate and produce high levels of IL-17A and IL-17F."
    explanation: Demonstrates antigen-specific gastric T cell activation and proliferation in response to the H+/K+ ATPase autoantigen in AIG patients.
  - reference: PMID:42367768
    reference_title: "Autoimmune gastritis: a comprehensive review of pathophysiology, risk stratification, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autoimmune gastritis (AIG) is a chronic, organ-specific autoimmune disease characterized by the immune-mediated destruction of gastric parietal cells, leading to impaired acid secretion, vitamin B12 deficiency, and an increased risk of gastric malignancies."
    explanation: Establishes immune-mediated parietal cell destruction as the central pathogenic mechanism of autoimmune gastritis.
  - reference: PMID:21174235
    reference_title: "Cutting edge issues in autoimmune gastritis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autoimmune gastritis is the outcome of a pathological CD4 T cell-mediated autoimmune response directed against the gastric H/K-ATPase."
    explanation: Confirms that the autoimmune response driving AIG is CD4 T cell-mediated and directed against the gastric H+/K+ ATPase.
- name: Parietal Cell Destruction and Oxyntic Atrophy
  description: >
    Immune-mediated destruction of parietal cells leads to progressive atrophy of
    the oxyntic (acid-secreting) mucosa restricted to the corpus and fundus. Loss
    of parietal cells abolishes both gastric acid and intrinsic factor secretion,
    and the mucosa undergoes pseudopyloric and intestinal metaplasia.
  cell_types:
  - preferred_term: parietal cell
    term:
      id: CL:0000162
      label: parietal cell
    modifier: ABSENT
  biological_processes:
  - preferred_term: gastric acid secretion
    term:
      id: GO:0001696
      label: gastric acid secretion
    modifier: DECREASED
  downstream:
  - target: Atrophic Gastritis
    description: Progressive parietal cell loss produces corpus-restricted atrophic gastritis.
  - target: Achlorhydria
    description: Parietal cell loss abolishes gastric acid secretion.
  - target: Iron Deficiency Anemia
    description: Loss of gastric acid impairs acid-dependent dietary iron absorption, causing iron deficiency anemia.
  - target: Intrinsic Factor Deficiency and B12 Malabsorption
    description: Parietal cell loss abolishes intrinsic factor secretion.
  - target: Hypergastrinemia and ECL Cell Hyperplasia
    description: Loss of luminal acid removes negative feedback on antral gastrin release.
  - target: Gastric Adenocarcinoma
    description: >-
      Oxyntic atrophy with intestinal metaplasia forms a precancerous field
      predisposing to intestinal-type gastric adenocarcinoma.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
  evidence:
  - reference: PMID:28102858
    reference_title: "Luminescent Immunoprecipitation System (LIPS) for Detection of Autoantibodies Against ATP4A and ATP4B Subunits of Gastric Proton Pump H+,K+-ATPase in Atrophic Body Gastritis Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Atrophic body gastritis (AGB) is the pathological lesion of autoimmune gastritis, characterized by the disappearance of oxyntic mucosa"
    explanation: Confirms that parietal-cell destruction produces corpus-restricted disappearance of the oxyntic mucosa (atrophic body gastritis).
- name: Intrinsic Factor Deficiency and B12 Malabsorption
  description: >
    Loss of intrinsic factor (encoded by CBLIF/GIF) secreted by parietal cells,
    compounded by anti-intrinsic factor autoantibodies, prevents ileal absorption
    of dietary vitamin B12 (cobalamin), causing systemic cobalamin deficiency and
    pernicious anemia.
  cell_types:
  - preferred_term: parietal cell
    term:
      id: CL:0000162
      label: parietal cell
    modifier: ABSENT
  downstream:
  - target: Pernicious Anemia
    description: Cobalamin deficiency impairs erythropoiesis, causing megaloblastic anemia.
  - target: Peripheral Neuropathy
    description: Cobalamin deficiency causes neurological injury including subacute combined degeneration.
  - target: Glossitis
    description: Cobalamin deficiency causes atrophic glossitis.
  evidence:
  - reference: PMID:31080562
    reference_title: "Intrinsic factor recognition promotes T helper 17/T helper 1 autoimmune gastric inflammation in patients with pernicious anemia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The intrinsic factor is the major humoral autoantigen in pernicious anemia/autoimmune gastritis."
    explanation: Establishes intrinsic factor as the major humoral autoantigen whose loss (and autoantibody targeting) causes the B12 malabsorption of pernicious anemia.
  - reference: PMID:21174235
    reference_title: "Cutting edge issues in autoimmune gastritis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "megaloblastic pernicious anemia arising from vitamin B12 deficiency"
    explanation: Links the intrinsic-factor-dependent vitamin B12 deficiency to megaloblastic pernicious anemia.
- name: Hypergastrinemia and ECL Cell Hyperplasia
  description: >
    Achlorhydria removes the acid-mediated negative feedback on antral G cells,
    producing marked hypergastrinemia. Chronically elevated gastrin is trophic for
    enterochromaffin-like (ECL) cells in the corpus, driving ECL cell hyperplasia
    that can progress through dysplasia to type 1 gastric neuroendocrine tumors.
  cell_types:
  - preferred_term: antral G cell
    term:
      id: CL:0000508
      label: type G enteroendocrine cell
    modifier: INCREASED
  - preferred_term: enterochromaffin-like cell
    term:
      id: CL:0000504
      label: enterochromaffin-like cell
    modifier: INCREASED
  downstream:
  - target: Hypergastrinemia
    description: Achlorhydria-driven loss of feedback on antral G cells produces marked hypergastrinemia.
  - target: Gastric Neuroendocrine Tumor
    description: Sustained gastrin drive promotes ECL hyperplasia to neoplasia.
  evidence:
  - reference: PMID:31963924
    reference_title: "Proton Pump Inhibitor Use, Hypergastrinemia, and Gastric Carcinoids-What Is the Relationship?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "tumorigenesis is mediated by gastrin's effects on the CCK2R-receptor on ECL-cells that in turn leads to hyperplasia, dysplasia, and finally neoplasia"
    explanation: Describes the gastrin-CCK2R trophic pathway by which chronic hypergastrinemia drives ECL cell hyperplasia, dysplasia, and neoplasia.
  - reference: PMID:34476276
    reference_title: "Progression From Antral G-Cell Hyperplasia to Gastric Neuroendocrine Tumor in a Patient With Autoimmune Gastritis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This leads to the absence of gastric acid production, which causes compensatory hyperplasia of gastric antral G-cells leading to hypergastrinemia. The excess gastrin binds to enterochromaffin-like cells causing hyperplasia, which may progress to dysplasia and rarely to gastric neuroendocrine tumors."
    explanation: Human case documenting the full AIG sequence of achlorhydria, antral G-cell hyperplasia, hypergastrinemia, and ECL hyperplasia-dysplasia-neoplasia.
phenotypes:
- category: Digestive
  name: Atrophic Gastritis
  description: >
    Chronic atrophic gastritis restricted to the gastric corpus and fundus
    (oxyntic mucosa), with loss of parietal and chief cells and replacement by
    metaplastic epithelium.
  frequency: OBLIGATE
  phenotype_term:
    preferred_term: Atrophic gastritis
    term:
      id: HP:0002582
      label: Atrophic gastritis
- category: Digestive
  name: Achlorhydria
  description: >
    Loss of gastric acid secretion resulting from destruction of acid-secreting
    parietal cells.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Achlorhydria
    term:
      id: HP:0032448
      label: Achlorhydria
  evidence:
  - reference: PMID:42367768
    reference_title: "Autoimmune gastritis: a comprehensive review of pathophysiology, risk stratification, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autoimmune gastritis (AIG) is a chronic, organ-specific autoimmune disease characterized by the immune-mediated destruction of gastric parietal cells, leading to impaired acid secretion, vitamin B12 deficiency, and an increased risk of gastric malignancies."
    explanation: Parietal cell destruction abolishes gastric acid secretion, producing hypochlorhydria and achlorhydria.
- category: Hematologic
  name: Pernicious Anemia
  description: >
    Megaloblastic anemia from vitamin B12 deficiency caused by intrinsic factor
    loss; the classic hematologic complication of autoimmune gastritis.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Megaloblastic anemia
    term:
      id: HP:0001889
      label: Megaloblastic anemia
  evidence:
  - reference: PMID:42367768
    reference_title: "Autoimmune gastritis: a comprehensive review of pathophysiology, risk stratification, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autoimmune gastritis (AIG) is a chronic, organ-specific autoimmune disease characterized by the immune-mediated destruction of gastric parietal cells, leading to impaired acid secretion, vitamin B12 deficiency, and an increased risk of gastric malignancies."
    explanation: Loss of intrinsic factor from parietal cell destruction causes vitamin B12 deficiency, the basis of pernicious (megaloblastic) anemia.
  - reference: PMID:34829460
    reference_title: "Chronic Autoimmune Gastritis: Modern Diagnostic Principles."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The clinical manifestation of the disease includes possible variants such as gastrointestinal, hematological (first of all, the formation of iron deficiency and B12-deficiency anemia), and neurological variants."
    explanation: Lists B12-deficiency (megaloblastic/pernicious) anemia as a core hematological manifestation of chronic autoimmune gastritis.
- category: Hematologic
  name: Iron Deficiency Anemia
  description: >
    Iron deficiency anemia due to impaired acid-dependent iron absorption; often
    the earliest hematologic manifestation, preceding B12 deficiency.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Iron deficiency anemia
    term:
      id: HP:0001891
      label: Iron deficiency anemia
  evidence:
  - reference: PMID:34829460
    reference_title: "Chronic Autoimmune Gastritis: Modern Diagnostic Principles."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The clinical manifestation of the disease includes possible variants such as gastrointestinal, hematological (first of all, the formation of iron deficiency and B12-deficiency anemia), and neurological variants."
    explanation: Identifies iron deficiency anemia as a leading hematological presentation of chronic autoimmune gastritis, often preceding B12 deficiency.
- category: Laboratory
  name: Hypergastrinemia
  description: >
    Markedly elevated serum gastrin resulting from achlorhydria-driven loss of
    feedback inhibition on antral G cells.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Hypergastrinemia
    term:
      id: HP:0500167
      label: Hypergastrinemia
- category: Neurologic
  name: Peripheral Neuropathy
  description: >
    Vitamin B12 deficiency causes peripheral neuropathy and, when severe, subacute
    combined degeneration of the spinal cord with paresthesias and sensory ataxia.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Peripheral neuropathy
    term:
      id: HP:0009830
      label: Peripheral neuropathy
- category: Digestive
  name: Glossitis
  description: >
    Atrophic glossitis (a smooth, sore, red tongue) associated with vitamin B12
    deficiency.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Glossitis
    term:
      id: HP:0000206
      label: Glossitis
- category: Neoplasm
  name: Gastric Neuroendocrine Tumor
  description: >
    Type 1 gastric neuroendocrine tumors (carcinoids) arising from hypergastrinemia-driven
    ECL cell hyperplasia; usually indolent and multifocal.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Gastric carcinoid tumor
    term:
      id: HP:6000898
      label: Gastric carcinoid tumor
  evidence:
  - reference: PMID:31963924
    reference_title: "Proton Pump Inhibitor Use, Hypergastrinemia, and Gastric Carcinoids-What Is the Relationship?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "persistent hypergastrinemia, generally accepted as causing g-NETs in CAG and ZES"
    explanation: Persistent hypergastrinemia in chronic atrophic gastritis is the accepted cause of gastric neuroendocrine tumors (carcinoids).
  - reference: PMID:42367768
    reference_title: "Autoimmune gastritis: a comprehensive review of pathophysiology, risk stratification, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we explore precision risk stratification models for gastric neuroendocrine tumors (gNETs) and gastric adenocarcinoma, emphasizing the roles of endoscopic surveillance and molecular biomarkers"
    explanation: Confirms gastric neuroendocrine tumors and adenocarcinoma as the neoplastic risks of autoimmune gastritis that drive endoscopic surveillance.
- category: Neoplasm
  name: Gastric Adenocarcinoma
  description: >
    Corpus-restricted atrophy with intestinal metaplasia is a precancerous field
    that confers an increased risk of gastric (intestinal-type) adenocarcinoma,
    the basis for endoscopic surveillance in autoimmune gastritis.
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Gastric adenocarcinoma
    term:
      id: HP:0033770
      label: Gastric adenocarcinoma
  evidence:
  - reference: PMID:42367768
    reference_title: "Autoimmune gastritis: a comprehensive review of pathophysiology, risk stratification, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we explore precision risk stratification models for gastric neuroendocrine tumors (gNETs) and gastric adenocarcinoma, emphasizing the roles of endoscopic surveillance and molecular biomarkers"
    explanation: Identifies gastric adenocarcinoma as a neoplastic risk of autoimmune gastritis requiring risk stratification and surveillance.
biochemical:
- name: Anti-Parietal Cell Antibody
  notes: >
    Autoantibodies against the gastric H+/K+ ATPase (parietal cell canalicular
    antigen); the serological hallmark of autoimmune gastritis, present in the
    majority of patients.
  presence: Increased
  evidence:
  - reference: PMID:28102858
    reference_title: "Luminescent Immunoprecipitation System (LIPS) for Detection of Autoantibodies Against ATP4A and ATP4B Subunits of Gastric Proton Pump H+,K+-ATPase in Atrophic Body Gastritis Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Circulating autoantibodies targeting the H+/K+-ATPase proton pump of gastric parietal cells are considered markers of autoimmune gastritis"
    explanation: Establishes anti-parietal cell (anti-H+/K+ ATPase) autoantibodies as the serological marker of autoimmune gastritis.
- name: Anti-Intrinsic Factor Antibody
  notes: >
    Autoantibodies against intrinsic factor; less sensitive but highly specific
    for autoimmune gastritis and pernicious anemia.
  presence: Increased
- name: Serum Gastrin
  notes: >
    Fasting serum gastrin is markedly elevated in autoimmune gastritis due to
    achlorhydria.
  presence: Increased
  evidence:
  - reference: PMID:40831016
    reference_title: "Evaluation of Pepsinogen I, II, Gastrin 17 and Helicobacter pylori IgG in Atrophic Gastritis: A Head-To-Head Comparison of Lateral Flow and Enzyme-Linked Immunosorbent Assays."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a reduced PGI/PGII ratio combined with elevated G-17 levels provided excellent discrimination"
    explanation: Elevated gastrin-17 accompanies corpus atrophic gastritis, reflecting the achlorhydria-driven hypergastrinemia of autoimmune gastritis.
- name: Serum Pepsinogen I
  notes: >
    Low serum pepsinogen I and a low pepsinogen I/II ratio reflect loss of chief
    and parietal cells in the atrophic oxyntic mucosa.
  presence: Decreased
  evidence:
  - reference: PMID:40831016
    reference_title: "Evaluation of Pepsinogen I, II, Gastrin 17 and Helicobacter pylori IgG in Atrophic Gastritis: A Head-To-Head Comparison of Lateral Flow and Enzyme-Linked Immunosorbent Assays."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a reduced PGI/PGII ratio combined with elevated G-17 levels provided excellent discrimination"
    explanation: A reduced pepsinogen I/II ratio (with elevated gastrin-17) discriminates corpus atrophic gastritis, reflecting oxyntic gland loss.
genetic:
- name: ATP4A
  notes: >
    Alpha subunit of the gastric H+/K+ ATPase; the major autoantigen targeted by
    parietal cell autoantibodies and autoreactive T cells in autoimmune gastritis.
  gene_term:
    preferred_term: ATP4A
    term:
      id: hgnc:819
      label: ATP4A
  association: Risk factor
  evidence:
  - reference: PMID:28102858
    reference_title: "Luminescent Immunoprecipitation System (LIPS) for Detection of Autoantibodies Against ATP4A and ATP4B Subunits of Gastric Proton Pump H+,K+-ATPase in Atrophic Body Gastritis Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This study aimed to assess autoantibodies against ATP4A and ATP4B subunits of parietal cells H+, K+-ATPase in atrophic body gastritis patients and controls."
    explanation: Identifies the ATP4A subunit of the parietal cell H+/K+ ATPase as a target autoantigen in autoimmune (atrophic body) gastritis.
- name: ATP4B
  notes: >
    Beta subunit of the gastric H+/K+ ATPase; a co-target autoantigen in
    autoimmune gastritis.
  gene_term:
    preferred_term: ATP4B
    term:
      id: hgnc:820
      label: ATP4B
  association: Risk factor
  evidence:
  - reference: PMID:28102858
    reference_title: "Luminescent Immunoprecipitation System (LIPS) for Detection of Autoantibodies Against ATP4A and ATP4B Subunits of Gastric Proton Pump H+,K+-ATPase in Atrophic Body Gastritis Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This study aimed to assess autoantibodies against ATP4A and ATP4B subunits of parietal cells H+, K+-ATPase in atrophic body gastritis patients and controls."
    explanation: Identifies the ATP4B subunit of the parietal cell H+/K+ ATPase as a target autoantigen in autoimmune (atrophic body) gastritis.
environmental:
- name: Helicobacter pylori Infection
  exposure_term:
    preferred_term: exposure to Helicobacter pylori
    term:
      id: ECTO:3000003
      label: exposure to Helicobacter pylori
  description: >
    H. pylori infection is proposed to trigger autoimmune gastritis through
    molecular mimicry between H. pylori antigens and the gastric H+/K+ ATPase,
    although autoimmune gastritis characteristically persists after the organism
    is no longer detectable.
  evidence:
  - reference: PMID:21174235
    reference_title: "Cutting edge issues in autoimmune gastritis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a role for Helicobacter pylori as an infective trigger through molecular mimicry"
    explanation: Supports H. pylori as a candidate infective trigger of autoimmune gastritis via molecular mimicry with the gastric H+/K+ ATPase.
inheritance:
- name: Polygenic inheritance
  description: >
    Complex, non-Mendelian autoimmune disease with polygenic susceptibility -
    HLA-DQB1 plus non-HLA loci (PTPN22, IL2RA) shared with other organ-specific
    autoimmune diseases - acting together with environmental factors.
  inheritance_term:
    preferred_term: Polygenic inheritance
    term:
      id: HP:0010982
      label: Polygenic inheritance
  evidence:
  - reference: PMID:34145262
    reference_title: "Genome-wide association study identifies five risk loci for pernicious anemia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We conduct a genome-wide association study meta-analysis in 2166 cases and 659,516 European controls from population-based biobanks and identify genome-wide significant signals in or near the PTPN22"
    explanation: A GWAS identifies multiple risk loci (PTPN22, HLA-DQB1, IL2RA) for pernicious anemia / autoimmune gastritis, establishing polygenic inheritance.
prevalence:
- population: General population
  percentage: 2.0
  evidence:
  - reference: PMID:28102858
    reference_title: "Luminescent Immunoprecipitation System (LIPS) for Detection of Autoantibodies Against ATP4A and ATP4B Subunits of Gastric Proton Pump H+,K+-ATPase in Atrophic Body Gastritis Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "prevalence of ~2% in the general population and up to 10% in patients with other autoimmune diseases, such as type I diabetes or autoimmune thyroid disease."
    explanation: Establishes ~2% general-population prevalence, rising to ~10% among patients with other autoimmune diseases (thyrogastric clustering).
histopathology:
- name: Oxyntic (Corpus-Restricted) Gland Atrophy
  description: >
    Corpus- and fundus-restricted atrophy of the oxyntic (acid-secreting) mucosa
    with loss of parietal and chief cells and a lymphoplasmacytic infiltrate; the
    antral mucosa is characteristically spared. This is the diagnostic pathological
    lesion of autoimmune gastritis (staged by the Sydney System / OLGA).
  diagnostic: true
  evidence:
  - reference: PMID:28102858
    reference_title: "Luminescent Immunoprecipitation System (LIPS) for Detection of Autoantibodies Against ATP4A and ATP4B Subunits of Gastric Proton Pump H+,K+-ATPase in Atrophic Body Gastritis Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Atrophic body gastritis (AGB) is the pathological lesion of autoimmune gastritis, characterized by the disappearance of oxyntic mucosa"
    explanation: Corpus-restricted disappearance of the oxyntic mucosa is the defining diagnostic pathological lesion of autoimmune gastritis.
- name: Enterochromaffin-Like (ECL) Cell Hyperplasia
  description: >
    Hypergastrinemia-driven linear and nodular hyperplasia of corpus
    enterochromaffin-like (ECL) cells, which can progress through dysplasia to
    type 1 gastric neuroendocrine tumors.
  evidence:
  - reference: PMID:34476276
    reference_title: "Progression From Antral G-Cell Hyperplasia to Gastric Neuroendocrine Tumor in a Patient With Autoimmune Gastritis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The excess gastrin binds to enterochromaffin-like cells causing hyperplasia, which may progress to dysplasia and rarely to gastric neuroendocrine tumors."
    explanation: Documents ECL cell hyperplasia progressing through dysplasia to neuroendocrine tumor in autoimmune gastritis.
treatments:
- name: Vitamin B12 Replacement
  description: >
    Parenteral (or high-dose oral) cobalamin replacement corrects and prevents the
    hematologic and neurologic consequences of B12 deficiency in pernicious anemia.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: vitamin B12
      term:
        id: CHEBI:176843
        label: vitamin B12
- name: Iron Replacement
  description: >
    Oral or intravenous iron to correct the iron deficiency anemia that commonly
    precedes B12 deficiency in autoimmune gastritis.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: iron(2+)
      term:
        id: CHEBI:29033
        label: iron(2+)
- name: Endoscopic Surveillance
  description: >
    Periodic upper endoscopy with biopsy to monitor for gastric neuroendocrine
    tumors and gastric adenocarcinoma in patients with atrophic body gastritis.
  treatment_term:
    preferred_term: esophagogastroduodenoscopy
    term:
      id: NCIT:C78144
      label: Esophagogastroduodenoscopy
  evidence:
  - reference: PMID:42367768
    reference_title: "Autoimmune gastritis: a comprehensive review of pathophysiology, risk stratification, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we explore precision risk stratification models for gastric neuroendocrine tumors (gNETs) and gastric adenocarcinoma, emphasizing the roles of endoscopic surveillance and molecular biomarkers"
    explanation: Supports endoscopic surveillance as the management strategy for the gastric neoplasia risk in autoimmune gastritis.
- name: Netazepide (Gastrin/CCK2 Receptor Antagonist)
  description: >
    Netazepide is an investigational oral gastrin/cholecystokinin-2 receptor
    (CCK2R) antagonist that blocks the trophic gastrin signal driving ECL cell
    proliferation, shrinking and eradicating type 1 gastric neuroendocrine tumors
    and normalizing chromogranin A in autoimmune atrophic gastritis.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: netazepide
      term:
        id: NCIT:C87692
        label: Netazepide
  target_phenotypes:
  - preferred_term: Gastric carcinoid tumor
    term:
      id: HP:6000898
      label: Gastric carcinoid tumor
  evidence:
  - reference: PMID:27704617
    reference_title: "Netazepide, a gastrin/cholecystokinin-2 receptor antagonist, can eradicate gastric neuroendocrine tumours in patients with autoimmune chronic atrophic gastritis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Netazepide, a gastrin/cholecystokinin 2 receptor antagonist, once daily for 12 weeks reduced the number of tumours and size of the largest one in 16 patients with autoimmune chronic atrophic gastritis (CAG), achlorhydria, hypergastrinaemia and multiple gastric neuroendocrine tumours (type 1 gastric NETs)"
    explanation: Human trial showing the gastrin/CCK2R antagonist netazepide reduces type 1 gastric NETs in autoimmune atrophic gastritis by blocking the trophic gastrin signal.
- name: Endoscopic Resection of Gastric Neuroendocrine Tumors
  description: >
    Endoscopic resection is the first-line treatment for small, localized type 1
    gastric neuroendocrine tumors; larger or higher-risk lesions are referred for
    surgical resection.
  treatment_term:
    preferred_term: Endoscopic Mucosal Resection
    term:
      id: NCIT:C103242
      label: Endoscopic Mucosal Resection
  target_phenotypes:
  - preferred_term: Gastric carcinoid tumor
    term:
      id: HP:6000898
      label: Gastric carcinoid tumor
  evidence:
  - reference: PMID:42228075
    reference_title: "[Gastric neuroendocrine neoplasms: update on endoscopic and surgical management]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "For type I gastric neuroendocrine neoplasms (gNEN) larger than 1 cm endoscopic resection should be performed, whereas for tumors larger than 2 cm surgical resection should be carried out."
    explanation: States that endoscopic resection is the treatment for type 1 gastric neuroendocrine tumors, with surgery reserved for larger lesions.
- name: Somatostatin Analog Therapy
  description: >
    Somatostatin analogs (e.g., octreotide, lanreotide) suppress gastrin release
    and are antiproliferative for type 1 gastric neuroendocrine tumors, reducing
    tumor size in patients with multiple or recurrent lesions.
  therapeutic_modality: PEPTIDE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: octreotide
      term:
        id: CHEBI:7726
        label: octreotide
  target_phenotypes:
  - preferred_term: Gastric carcinoid tumor
    term:
      id: HP:6000898
      label: Gastric carcinoid tumor
  evidence:
  - reference: PMID:40503415
    reference_title: "Last decade of advances in gastric neuroendocrine tumors: Innovations, challenges, and future directions."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Type I treatment usually involves endoscopic resection (ER), with surgical resection for recurrence. Somatostatin analogs (SSAs) can reduce tumor size, and the prognosis is generally excellent."
    explanation: Supports somatostatin analogs as a size-reducing therapy for type 1 gastric neuroendocrine tumors.
- name: Helicobacter pylori Eradication
  description: >
    When Helicobacter pylori infection coexists with autoimmune gastritis,
    eradication therapy is recommended; in the subset where H. pylori contributes
    to the gastritis it can improve hematologic parameters and slow progression.
  treatment_term:
    preferred_term: antimicrobial agent therapy
    term:
      id: NCIT:C15620
      label: Antibiotic Therapy
  evidence:
  - reference: PMID:42254085
    reference_title: "Pernicious Anemia and Helicobacter pylori Infection: What a Hematologist Needs to Know?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Rapid eradication of H. pylori can significantly improve hematologic parameters and prevent the progression of autoimmune gastritis."
    explanation: Supports H. pylori eradication as a management step that can improve hematologic parameters and slow progression when the organism is present.
mechanistic_hypotheses:
- hypothesis_group_id: canonical_primary_autoimmune_hk_atpase_origin
  hypothesis_label: Canonical Primary Autoimmunity Against the Gastric H+/K+ ATPase
  status: CANONICAL
  description: >-
    Autoimmune gastritis is a primary organ-specific autoimmune disease driven by
    a breakdown of self-tolerance to the parietal-cell H+/K+ ATPase (ATP4A/ATP4B),
    with CD4 T-cell-mediated parietal cell destruction that clinically tends to
    progress rather than remit. The tolerance defect implicates the beta subunit:
    although H/K-ATPase alpha-subunit
    (ATP4A) mRNA is expressed in the thymus, thymic expression alone does not
    tolerize the pathogenic T-cell repertoire, and in the murine neonatal-thymectomy
    system it is the beta subunit (ATP4B), absent from the thymus, whose transgenic
    thymic expression prevents disease - so ATP4B behaves as the dominant autoantigen
    in mice. Whether ATP4B-specific T cells likewise dominate the surviving human
    repertoire, or precede ATP4A reactivity, has not been demonstrated. The murine
    disease induced by neonatal thymectomy is T-cell-mediated, and monogenic
    tolerance defects (AIRE/APECED, FOXP3/IPEX) produce autoimmune gastritis as part
    of polyautoimmunity. Two independent hypothesis-search runs (see notes) concur
    that this primary/central-tolerance account is best treated as one of several
    candidate initiating pathways feeding a shared effector cascade, rather than as
    an infection-independent sole origin.
  evidence:
  - reference: PMID:9272282
    reference_title: "Expression of the gastric H/K-ATPase alpha-subunit in the thymus may explain the dominant role of the beta-subunit in the pathogenesis of autoimmune gastritis."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The murine disease induced by neonatal thymectomy is T cell-mediated."
    explanation: The T-cell-mediated neonatal-thymectomy model supports a T-cell-driven autoimmune origin of gastritis.
  - reference: PMID:16237067
    reference_title: "Promiscuous thymic expression of an autoantigen gene does not result in negative selection of pathogenic T cells."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "thymic mRNA expression alone cannot predict a contribution to thymic tolerance."
    explanation: Corrects the tolerance framing - thymic H/K-ATPase alpha-subunit mRNA expression does not negatively select pathogenic T cells, so central tolerance to the alpha subunit is not protective; the beta subunit (absent from the thymus) is the dominant autoantigen.
  - reference: PMID:8393475
    reference_title: An autoimmune disease with multiple molecular targets abrogated by the transgenic expression of a single autoantigen in the thymus.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We show that transgenic expression of the gastric H/K ATPase beta subunit specifically prevents the onset of autoimmune gastritis after neonatal thymectomy."
    explanation: >-
      The loss-of-function experiment behind the beta-subunit tolerance claim:
      forcing thymic expression of ATP4B, which is normally absent from the
      thymus, prevents neonatal-thymectomy gastritis in mice. This establishes
      ATP4B as a major T-cell target and a central-tolerance target in the
      murine system; it says nothing about the relative size of the ATP4B- and
      ATP4A-reactive repertoires in humans.
  - reference: PMID:11449363
    reference_title: "A T cell receptor transgenic model of severe, spontaneous organ-specific autoimmunity."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "All A23 transgenic animals spontaneously developed severe autoimmune gastritis, and evidence of disease was detected as early as day 10 of life."
    explanation: >-
      The TxA23 model: a single CD4 TCR specific for H/K ATPase alpha-chain
      (630-641) is sufficient for fully penetrant spontaneous autoimmune
      gastritis, and disease transfers with as few as 10^3 transgenic
      thymocytes. This establishes sufficiency of an engineered, abundant
      autoreactive specificity - not necessity of that TCR, which the
      experiment does not test.
  notes: >-
    Two independent hypothesis-search runs concur on PARTIALLY SUPPORTED:
    a claude_code report
    (kb/hypotheses/Autoimmune_Gastritis/canonical_primary_autoimmune_hk_atpase_origin/claude_code.md)
    and a deeper openscientist report (same directory, openscientist.md; 127
    papers, 17 findings over 5 iterations). Both retain the CD4 T-cell / H+/K+
    ATPase effector mechanism as CANONICAL but judge the etiological claim of a
    purely primary, infection-independent origin overstated. Each candidate
    initiating route is retained only at the evidence level it was actually
    demonstrated at: primary central-tolerance defect (murine neonatal
    thymectomy and transgenic thymic ATP4B; PMID:8393475), H. pylori molecular
    mimicry (human gastric T-cell cross-reactivity only; see
    alternative_hpylori_molecular_mimicry_origin), neonatal roseolovirus thymic
    disruption (experimental murine infection; not shown for human
    roseoloviruses), and peripheral checkpoint failure (anti-PD-1/anti-CTLA-4
    gastritis, supported by deeply phenotyped single cases, which cannot
    establish absence of host predisposition or identity with sporadic AIG).
    The codex assessment sidecar in the hypothesis directory rejects three of
    the openscientist run's stronger readings: that one ATP4A-specific TCR is
    "necessary and sufficient" (the TxA23 experiment establishes sufficiency
    only; PMID:11449363), that a prospective progression cohort proves the
    autoimmune process is mechanistically self-sustaining regardless of trigger
    (clinical progression is not an immune-mechanism endpoint), and that
    PTPN22, HLA, ABO and IFIH1 form one confirmed AIG genetic architecture -
    PTPN22/HLA-DQB1/IL2RA/AIRE come from the pernicious-anemia GWAS
    (PMID:34145262) while ABO and IFIH1 come from a parietal-cell-antibody GWAS
    in a type 1 diabetes cohort, a different phenotype and sampling frame. The
    ATP4A/ATP4B tolerance correction flagged by both runs (alpha thymic
    expression does not tolerize; ATP4B is the thymus-absent dominant murine
    autoantigen) has been folded into the description above (PMID:16237067).
    The report's candidate GO identifiers were not curated: GO:0006968 is
    cellular defense response, not central tolerance, and GO:0002513 is
    tolerance induction to self antigen, not a generic peripheral-tolerance
    term. Follow-up recommended by openscientist:
    split into separate CANONICAL effector and qualified etiological-trigger
    hypotheses, and add an upstream "incomplete central tolerance to ATP4B" node.
- hypothesis_group_id: alternative_hpylori_molecular_mimicry_origin
  hypothesis_label: Alternative H. pylori Molecular-Mimicry ("Hit-and-Run") Origin
  status: ALTERNATIVE
  description: >-
    Autoimmune gastritis is initiated by Helicobacter pylori infection via
    molecular mimicry between H. pylori antigens and the gastric H+/K+ ATPase,
    generating cross-reactive T- and B-cell responses that, through epitope
    spreading and bystander activation in a genetically susceptible host, become
    self-perpetuating autoimmunity and persist after the organism is cleared
    (established AIG is frequently H. pylori-negative). A corollary is that a
    subset of cases are reversible with early eradication. Causation in humans
    remains unproven and is the basis of a knowledge-gap discussion.
  evidence:
  - reference: PMID:21174235
    reference_title: "Cutting edge issues in autoimmune gastritis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a role for Helicobacter pylori as an infective trigger through molecular mimicry"
    explanation: States H. pylori as a candidate infective trigger of autoimmune gastritis via molecular mimicry.
  - reference: PMID:42254085
    reference_title: "Pernicious Anemia and Helicobacter pylori Infection: What a Hematologist Needs to Know?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Rapid eradication of H. pylori can significantly improve hematologic parameters and prevent the progression of autoimmune gastritis."
    explanation: A reversible, H. pylori-attributable presentation is consistent with an infection-triggered origin in a subset of cases.
  - reference: PMID:38976374
    reference_title: "Distinguishing Features of Autoimmune Gastritis Depending on Previous Helicobacter pylori Infection or Positivity to Anti-Parietal Cell Antibodies: Results From the Autoimmune gastRitis Italian netwOrk Study grOup (ARIOSO)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "H. pylori -naive patients were more likely to have a first-degree family history of AIG (14.7% vs 8.9%; P = 0.012), type 1 diabetes mellitus (4.9% vs 2.3%; P = 0.025), and pernicious anemia (30.9% vs 21.1%; P = 0.003)."
    explanation: The largest AIG cohort (n=1,598) identifies H. pylori-naive AIG as a distinct entity with stronger familial/autoimmune signatures, limiting the mimicry hypothesis to a subset rather than a general etiology.
  - reference: PMID:14568977
    reference_title: "Molecular mimicry between Helicobacter pylori antigens and H+, K+ --adenosine triphosphatase in human gastric autoimmunity."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "H. pylori-infected patients with gastric autoimmunity harbor in vivo-activated gastric CD4+ T cells that recognize both H+, K+-adenosine triphosphatase and H. pylori antigens"
    explanation: >-
      The primary source for cellular cross-reactivity: gastric CD4 clones from
      selected H. pylori-infected patients with gastric autoimmunity recognized
      both the H+/K+ ATPase and epitopes from nine H. pylori proteins. This
      establishes mechanistic plausibility at the T-cell level only; it is
      cross-sectional and does not establish temporal initiation or an
      attributable fraction of human AIG.
  - reference: PMID:11549834
    reference_title: "Healing of active, non-atrophic autoimmune gastritis by H. pylori eradication."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In 64 patients (80%), H. pylori eradication treatment was followed by healing of the active autoimmune corpus gastritis"
    explanation: >-
      The primary source for the frequently cited "80% healing" figure. It
      supports an H. pylori-dependent early phenotype in a selected series
      restricted to active, not-yet-atrophic disease, and the study describes
      itself as retrospective and uncontrolled. Resolution achieved while the
      organism is being removed does not demonstrate the post-clearance
      self-perpetuating ("hit-and-run") step.
  - reference: PMID:10738313
    reference_title: Role of antigastric autoantibodies in chronic Helicobacter pylori infection.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Molecular mimicry between H. pylori and the host does not seem to be responsible for the generation of this type of autoreactivity."
    explanation: >-
      Refutes the humoral arm of the mimicry model: antigastric autoantibodies
      arising in chronic H. pylori infection are not attributable to mimicry
      with the organism. This qualifies rather than erases the separate
      cellular cross-reactivity finding.
  - reference: PMID:11815766
    reference_title: Prevalence and specificity of antigastric autoantibodies in adolescents infected with Helicobacter pylori.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "AGA were detected in 9 (18%) of the 51 infected patients and in 1 (4 %) of the 27 noninfected patients (P =.08; nonsignificant) and could not be absorbed to H pylori."
    explanation: >-
      Absorption assay in infected children and adolescents: antigastric
      autoantibodies could not be absorbed out with H. pylori antigen, so the
      autoantibody response is not cross-reactive with the organism. Independent
      support for the same humoral-arm refutation, in a different age group.
  notes: >-
    Two independent hypothesis-search runs concur on PARTIALLY SUPPORTED /
    UNRESOLVED: a claude_code report
    (kb/hypotheses/Autoimmune_Gastritis/alternative_hpylori_molecular_mimicry_origin/claude_code.md)
    and a deeper openscientist report (same directory, openscientist.md). H. pylori-
    to-H+/K+ ATPase cross-reactivity is documented at the T-cell level (cross-reactive
    gastric CD4 Th1 clones; urease beta-subunit homology; LPS Lewis-antigen mimicry;
    PMID:14568977), and active, not-yet-atrophic autoimmune corpus gastritis resolved
    after eradication in 64 of 80 patients in a retrospective, uncontrolled series
    (PMID:11549834). Neither result reaches the distinctive part of the hypothesis:
    reversibility achieved while the organism is being cleared is not evidence of a
    later self-perpetuating "hit-and-run" phase, and epitope spreading and persistence
    after clearance have no direct human evidence. The model is also refuted at the
    autoantibody level (antigastric autoantibodies do not absorb to H. pylori;
    PMID:10738313, PMID:11815766) and is non-general: H. pylori-naive AIG forms a
    distinct familial/autoimmune-enriched entity (ARIOSO n=1,598; PMID:38976374), and
    29.3% of 75 atrophic autoimmune gastritis cases had no reactivity to any of 13
    H. pylori antigens on multiplex serology (PMID:41484031). The wider "29-79%
    H. pylori-naive" range asserted by the openscientist report is not supported - its
    21.1% figure was the proportion meeting a stringent multi-antigen positive cutoff,
    whose complement is not "no evidence of exposure", and its second source is not
    traceable in the report. Treg-depletion mouse models produce AIG with no infection,
    and some H. pylori-AIG associations may be inflated by diagnostic misclassification
    (urease-positive non-H. pylori bacteria overgrowing the achlorhydric stomach, shown
    in a referral series selected for repeated eradication failure, which cannot
    quantify bias in the wider literature). Retained ALTERNATIVE, best read as a
    subset-initiation mechanism whose full initiation-to-persistence sequence is
    unproven in humans. See the codex assessment sidecar in the hypothesis directory.
- hypothesis_group_id: canonical_th1_effector_polarization
  hypothesis_label: Canonical Th1/IFN-gamma Effector Polarization
  status: CANONICAL
  description: >-
    The effector arm driving parietal-cell destruction has classically been
    modeled as Th1/IFN-gamma-polarized, based on murine neonatal-thymectomy and
    TCR-transgenic effector-transfer systems specific for the H+/K+ ATPase.
  evidence:
  - reference: PMID:18641328
    reference_title: "Th1, Th2, and Th17 effector T cell-induced autoimmune gastritis differs in pathological pattern and in susceptibility to suppression by regulatory T cells."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We have evaluated the capacity of fully differentiated Th1, Th2, and Th17 cells derived from a mouse bearing a transgenic TCR specific for the gastric parietal cell antigen, H(+)K(+)-ATPase, to induce autoimmune gastritis after transfer to immunodeficient recipients."
    explanation: Effector-transfer model in which Th1 (among other subsets) specific for the H+/K+ ATPase induces autoimmune gastritis.
  - reference: PMID:15763992
    reference_title: "Molecular specificity and functional properties of autoreactive T-cell response in human gastric autoimmunity."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The majority of the autoreactive T cell clones secreted IFN-gamma and showed a T helper 1 (Th1) profile."
    explanation: Human gastric H+/K+ ATPase-reactive CD4 clones are predominantly Th1 (IFN-gamma) and cytotoxic, directly supporting the Th1 effector arm in human disease.
  - reference: PMID:22777705
    reference_title: "Both IFN-gamma and IL-17 are required for the development of severe autoimmune gastritis."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "both are required for the disease to progress to the late pathogenic stage that includes significant tissue disruption."
    explanation: IFN-gamma and IL-17 are co-required for severe disease (and CD8 T cells are the dominant IFN-gamma source), qualifying a Th1-exclusive model.
  - reference: PMID:11159878
    reference_title: "H(+),K(+)-atpase (proton pump) is the target autoantigen of Th1-type cytotoxic T cells in autoimmune gastritis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Most of these clones (88%) showed a Th1 profile, whereas a few secreted both Th1 and Th2 cytokines."
    explanation: >-
      Gastric H+/K+ ATPase-reactive CD4 clones isolated from five AIG patients
      were predominantly Th1, and most expressed perforin-mediated cytotoxicity
      and Fas-FasL-mediated apoptosis - the second small human clonal study
      supporting a real Th1 cytotoxic effector arm. Being a selected clonal
      panel, it does not sample the whole infiltrate or establish
      population-level Th1 dominance.
  - reference: PMID:8766575
    reference_title: Interferon-gamma is required during the initiation of an organ-specific autoimmune disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Treatment of neonatally thymectomized mice at weekly intervals for 6 or 12 weeks with a neutralizing rat monoclonal antibody to mouse IFN-gamma abolished the production of anti-gastric autoantibodies and decreased the incidence of gastric mononuclear infiltrates from the 69% observed in normal rat immunoglobulin (Ig)-injected mice to 16%."
    explanation: >-
      The loss-of-function experiment behind the "IFN-gamma is required for
      initiation" claim, quoted with its actual effect size: incidence fell
      from 69% to 16%, not to zero. It supports a major, model-specific early
      role for IFN-gamma rather than universal necessity or abolition of
      disease.
  - reference: PMID:30511397
    reference_title: "Interferon-γ directly induces gastric epithelial cell death and is required for progression to metaplasia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Gastric epithelial cells in gastroid cultures expressed IFN-γ receptor in the basolateral membrane, and gastroids died when treated with IFN-γ in an IFN-γ receptor-dependent manner."
    explanation: >-
      Murine gastric organoids die on direct IFN-gamma exposure in a
      receptor-dependent manner, and TxA23 x Ifng-/- mice show near-complete
      abrogation of atrophy and metaplasia. This is direct epithelial
      cytotoxicity in the mouse system; it does not isolate human
      parietal-cell killing in vivo or make IFN-gamma the sole cause of human
      atrophy.
  notes: >-
    Two independent hypothesis-search runs concur on PARTIALLY SUPPORTED: a
    claude_code report
    (kb/hypotheses/Autoimmune_Gastritis/canonical_th1_effector_polarization/claude_code.md)
    and an openscientist report (same directory, openscientist.md). Both retain
    Th1/IFN-gamma as foundational and real: human gastric H+/K+ ATPase-reactive
    CD4 clones are predominantly Th1 and cytotoxic via perforin/Fas-FasL
    (PMID:11159878, PMID:15763992), and IFN-gamma directly kills murine gastric
    epithelium in organoids and is required for atrophy and metaplasia in
    TxA23 mice (PMID:30511397). The causal perturbations are model-specific and
    are weaker than the openscientist report states: anti-IFN-gamma treatment
    in the neonatal-thymectomy model cut gastritis incidence from 69% to 16%
    rather than abolishing disease (PMID:8766575), and in a transfer setting
    IFN-gamma-deficient T cells could still initiate mild disease
    (PMID:22777705). Neither run supports a Th1-exclusive model - it is one arm
    of a cooperative multi-cytokine / multi-cell-type program: CD8 T cells were
    the dominant IFN-gamma source in that polyclonal mouse model, IFN-gamma
    plus IL-17 are co-required for severe disease (PMID:22777705), and IL-13
    acting through IL-4R-alpha is a separable required arm of the metaplastic
    transformation - though metaplasia was absent altogether in TxA23 x Ifng-/-
    mice, so IL-13 independence from IFN-gamma-associated atrophy across the
    whole trajectory is not established. The codex assessment sidecar in the
    hypothesis directory rejects two further readings carried by the report:
    that the PTPN22 pernicious-anemia risk variant wires patients toward Th1
    over Th17 (this joins a PA GWAS locus association with Th1/Th17 phenotyping
    in genotyped healthy donors, and is a hypothesis rather than evidence about
    gastric polarization; the report also misstates the GWAS p value as
    1.91e-10 rather than 1.91e-24), and that a null NK-depletion result rules
    out innate IFN-gamma sources. The intrinsic-factor-reactive
    pernicious-anemia compartment is mixed rather than Th17-dominant: the cited
    94% is a combined "Th17 or Th1" figure (see
    emerging_th17_effector_polarization). Caveat: Th1 dominance is demonstrated
    most robustly in TCR-transgenic / monoclonal systems, which may overrepresent
    it relative to polyclonal disease, and all human immune data here are
    cross-sectional, so which effector population dominates over the human
    disease course is unresolved.
- hypothesis_group_id: emerging_th17_effector_polarization
  hypothesis_label: Emerging Th17/IL-17 Effector Contribution
  status: EMERGING
  description: >-
    Human data show a gastric H+/K+ ATPase-specific Th17/IL-17 signature, and
    effector-transfer models show that Th1, Th2, and Th17 cells can each induce
    autoimmune gastritis with distinct pathology and differing susceptibility to
    regulatory T-cell suppression. Which effector arm dominates human disease, and
    whether it shifts over the disease course, is unresolved and carries
    therapeutic implications (e.g., anti-IL-17 blockade).
  evidence:
  - reference: PMID:35911678
    reference_title: "Gastric Th17 Cells Specific for H+/K+-ATPase and Serum IL-17 Signature in Gastric Autoimmunity."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Gastric LPMCs from all AIG patients, but not those from HCs, were activated by H+/K+-ATPase and were able to proliferate and produce high levels of IL-17A and IL-17F."
    explanation: Human gastric T cells produce IL-17A/IL-17F on H+/K+ ATPase stimulation, evidencing a Th17 effector contribution.
  - reference: PMID:18641328
    reference_title: "Th1, Th2, and Th17 effector T cell-induced autoimmune gastritis differs in pathological pattern and in susceptibility to suppression by regulatory T cells."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We have evaluated the capacity of fully differentiated Th1, Th2, and Th17 cells derived from a mouse bearing a transgenic TCR specific for the gastric parietal cell antigen, H(+)K(+)-ATPase, to induce autoimmune gastritis after transfer to immunodeficient recipients."
    explanation: Th17 effector cells can independently induce autoimmune gastritis in the transfer model, supporting an emerging Th17 arm.
  - reference: PMID:31080562
    reference_title: "Intrinsic factor recognition promotes T helper 17/T helper 1 autoimmune gastric inflammation in patients with pernicious anemia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Most of these clones (94%) showed a T helper 17 or T helper 1 profile."
    explanation: In pernicious anemia, 94% of intrinsic-factor-specific gastric CD4 clones fell into a combined "Th17 or Th1" category, evidencing a Th17 contribution in the intrinsic-factor-reactive compartment. The combined figure does not show that Th17 outnumbers Th1, so the compartment is mixed rather than Th17-dominant.
  - reference: PMID:40471463
    reference_title: "STAT3 inhibition mitigates experimental autoimmune gastritis by restoring Th17/Treg immune balance."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "STA-21 treatment alleviated gastric atrophy, reduced inflammatory infiltration, suppressed Th17 differentiation, and enhanced Treg function, reversing the Th17/Treg imbalance."
    explanation: STAT3 inhibition corrects the Th17/Treg imbalance and alleviates experimental autoimmune gastritis. STAT3 is pleiotropic across immune and epithelial programs, so this implicates a STAT3-dependent Th17/Treg axis without isolating Th17 mediation or a specific downstream cytokine.
  notes: >-
    Two independent hypothesis-search runs concur on PARTIALLY SUPPORTED / retain
    EMERGING: a claude_code report
    (kb/hypotheses/Autoimmune_Gastritis/emerging_th17_effector_polarization/claude_code.md)
    and an openscientist report (same directory, openscientist.md). Both confirm a
    genuine Th17/IL-17 contribution (H+/K+ ATPase-specific gastric IL-17A/F
    production in all eight AIG patients tested; 94% of intrinsic-factor-reactive
    clones in a combined "Th17 or Th1" category; Th17 transfer
    gives the most severe, Treg-resistant gastritis in the TxA23 model). The
    openscientist run went on to propose a wholesale reframing of the effector
    mechanism - epithelial IL-17RA signaling as protective, IL-21 as the real
    pathogenic Th17-derived mediator, and anti-IL-17 blockade as contraindicated -
    and the codex assessment sidecar in the hypothesis directory rejects that
    reframing on its sources. The IL-17RA results come from gastrointestinal
    epithelial Il17ra deletion during H. pylori infection, not sterile autoimmune
    gastritis and not parietal-cell-specific deletion or apoptosis; the "increased
    autoantibody production" in Il17ra-deficient mice was in fact enhanced
    H. pylori-specific antibody, not anti-H+/K+ ATPase or anti-intrinsic-factor
    autoantibody; and no IL-21 perturbation has been carried out in AIG at all, so
    the IL-21 bridge remains an untested hypothesis. There is no human anti-IL-17
    AIG study and no AIG animal experiment comparing IL-17 blockade with control,
    so protective IL-17 signaling in H. pylori infection and gastric carcinogenesis
    raises a real, unresolved safety question about anti-IL-17 therapy in AIG
    rather than establishing a contraindication. What survives: a Th17 contribution
    is real but its terminal tissue-damage mechanism is undetermined, direct
    IL-17A/F epithelial cytotoxicity is not established, STAT3 perturbation is a
    promising but pleiotropic and model-specific lead (PMID:40471463), Th1 remains
    the more extensively validated axis, and which arm dominates by disease stage
    is unresolved because all human evidence here is small and cross-sectional.
    The report's candidate ontology block was not curated: CL:0000163 is endocrine
    cell (parietal cell is CL:0000162, already used above), GO:0032623 is
    interleukin-2 production rather than interleukin-21 production, and its
    proposed MONDO identifiers resolve to unrelated disorders.
discussions:
- discussion_id: hmm_aig_mouse_model_neoplastic_trajectory
  prompt: >-
    Do murine autoimmune-gastritis models (neonatal thymectomy, H+/K+ ATPase
    immunization, and TCR-transgenic effector-transfer systems) faithfully
    reproduce human autoimmune gastritis, or do they capture only the initiation
    and parietal-cell-destruction biology while failing to model the
    human-specific downstream trajectory of chronic ECL-cell hyperplasia
    progressing to type 1 gastric neuroendocrine tumors, long-term gastric
    adenocarcinoma risk, and polyautoimmune clustering (thyroid, type 1 diabetes,
    vitiligo)?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#CD4+ T Cell-Mediated Autoimmune Response Against the Gastric Proton Pump
  - pathophysiology#Hypergastrinemia and ECL Cell Hyperplasia
  rationale: >-
    Mouse models robustly recapitulate the core autoantigen (H+/K+ ATPase), the
    CD4 T-cell-mediated destructive mechanism, and atrophic/metaplastic histology,
    and they are the primary source of mechanistic detail (effector-subset
    pathogenicity and Treg-dependent tolerance). However, short-lived rodent
    models less consistently reproduce the chronic hypergastrinemia -> ECL
    hyperplasia -> type 1 gastric NET sequence and the decades-long adenocarcinoma
    risk that dominate human clinical management, and single-antigen mouse systems
    do not intrinsically model human polyautoimmune comorbidity. Consequently the
    neoplastic-complication arm of the human entry rests on human observational
    data rather than on validated model mechanism.
  proposed_experiments:
  - experiment_id: exp_aig_longterm_ecl_neoplasia
    name: Longitudinal ECL-to-NET progression in a chronic hypergastrinemic AIG model
    description: >-
      In a chronic autoimmune-gastritis model with sustained achlorhydria and
      hypergastrinemia, longitudinally quantify the ECL-cell
      hyperplasia -> dysplasia -> type 1 gastric NET sequence and adenocarcinoma
      incidence over extended timeframes, mapped onto human histologic staging.
    decision_criterion: >-
      Whether comparable degrees and durations of hypergastrinemia reproduce the
      human ECL-to-NET-to-adenocarcinoma sequence.
    supporting_outcome:
    - >-
      Faithful reproduction would validate the human neoplastic trajectory as a
      direct consequence of the modeled autoimmune-achlorhydria-hypergastrinemia
      axis.
    refuting_outcome:
    - >-
      Failure to progress despite equivalent hypergastrinemia would indicate
      human-specific ECL/gastric-epithelial biology not captured by rodent models.
    model_systems:
    - name: Chronic murine autoimmune gastritis model
      description: >-
        Long-lived mouse model with sustained achlorhydria and hypergastrinemia
        (e.g., effector-transfer or gastrin-clamped systems) followed for ECL-cell
        neoplastic progression.
      experimental_model_type: OTHER
- discussion_id: gap_aig_sporadic_tolerance_trigger
  prompt: >-
    What initiates the loss of tolerance in the common sporadic (polygenic) form
    of autoimmune gastritis? H. pylori molecular mimicry is the leading trigger
    hypothesis, but established disease is usually H. pylori-negative and human
    causation is unproven; other triggers (viral, unidentified) and the
    gene-environment "second-hit" model (a PTPN22/HLA/AIRE background lowering the
    threshold for infection-triggered mimicry and epitope spreading) remain
    unvalidated in humans.
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#CD4+ T Cell-Mediated Autoimmune Response Against the Gastric Proton Pump
  rationale: >-
    The trigger question directly gates the two competing origin hypotheses
    (primary autoimmunity vs. H. pylori mimicry) and determines whether a
    modifiable environmental exposure exists. It cannot be resolved by the current
    snippet-supported human associations, which are cross-sectional and
    confounded by the frequent absence of the organism at diagnosis.
- discussion_id: gap_aig_disease_modifying_therapy_active_window
  prompt: >-
    Is the autoimmune process still active and pharmacologically targetable at the
    time of diagnosis, or is it effectively "burnt out"? There is no
    disease-modifying therapy for autoimmune gastritis - management is
    micronutrient replacement and surveillance - and it is unknown whether early
    immunomodulation (regulatory T-cell restoration or Th17/IL-17 blockade) could
    halt progression to atrophy, pernicious anemia, and neoplasia.
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#CD4+ T Cell-Mediated Autoimmune Response Against the Gastric Proton Pump
  rationale: >-
    Whether the effector response persists at a targetable level once corpus
    atrophy is established determines if immunomodulatory therapy is even
    mechanistically plausible; the emerging Th17 arm makes anti-IL-17 blockade a
    concrete but untested candidate. That candidate carries an unresolved safety
    question rather than a straightforward rationale: IL-17RA signaling on
    gastrointestinal epithelium is protective in H. pylori infection models and
    IL-17 signaling restrains gastric carcinogenesis, yet no anti-IL-17 study -
    human or animal - has been performed in autoimmune gastritis, so the net
    effect of blockade in this disease is unknown in both directions.
- discussion_id: gap_aig_natural_history_pediatric
  prompt: >-
    What is the natural history and timeline of autoimmune gastritis from the
    earliest seropositive ("potential AIG") phase through corpus atrophy,
    pernicious anemia, and neoplastic complications, and what distinguishes the
    poorly-studied pediatric-onset subgroup?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Parietal Cell Destruction and Oxyntic Atrophy
  rationale: >-
    The pre-atrophic seropositive phase is the clinically actionable window for
    early detection, but the rate and determinants of progression to irreversible
    atrophy and to neoplasia are not established prospectively, and the
    pediatric-onset subgroup's long-term course is largely unstudied.
datasets:
- accession: geo:GSE233973
  title: Comprehensive gene expression analysis using gastric mucosa with autoimmune gastritis
  description: In this study, we aimed to reveal whether gastric mucosa with AIG has a specific gene expression profile, involving in its histology and chronic inflammation. To approach this, we performed comprehensive analysis of gene expression using gastric mucosa with atuoimmune gastritis, that with H. pylori-associated gastritis and healthy mucosa without any inflammation. Potential mechanisms of the gene expression changes in gastric mucosa with AIG were also explored.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: MICROARRAY
  sample_count: 36
  publication: PMID:37962678
  notes: Identified by GEO DataSets index search for Autoimmune Gastritis (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-07-31. Title, sample count, and organism are GEO's own values.
- accession: geo:GSE178925
  title: Genome-wide DNA methylation analysis of gastric mucosa with autoimmune gastritis
  description: DNA methylation in gastric mucosa with autoimmune gastritis and H. pylori-associated gastritis and normal gastric mucosa
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: METHYLATION
  sample_count: 24
  publication: PMID:35034200
  notes: Identified by GEO DataSets index search for Autoimmune Gastritis (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-07-31. Title, sample count, and organism are GEO's own values.
- accession: geo:GSE271866
  title: Unveiling Cancer-Related Metaplastic Cells in Both Helicobacter pylori Infection and Autoimmune Gastritis
  description: We used 10X 5' single cell RNA sequencing (scRNAseq) technology to examine the transcriptional profiles of distinct gastric metaplastic cell types within the gastric corpus of mice chronically infected with Helicobacter pylori or chronically inflamed with autoimmune gastritis and humans with autoimmune gastritis.
  data_type: SINGLE_CELL_RNA_SEQ
  sample_count: 7
  publication: PMID:39236896
  notes: Identified by GEO DataSets index search for Autoimmune Gastritis (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-07-31. Title, sample count, and organism are GEO's own values.
📚

References & Deep Research

References

7
PMID:42367768
Autoimmune gastritis: a comprehensive review of pathophysiology, risk stratification, and management.
No top-level findings curated for this source.
PMID:34829460
Chronic Autoimmune Gastritis: Modern Diagnostic Principles.
No top-level findings curated for this source.
PMID:31864909
Thyro-entero-gastric autoimmunity: Pathophysiology and implications for patient management.
No top-level findings curated for this source.
PMID:35911678
Gastric Th17 Cells Specific for H+/K+-ATPase and Serum IL-17 Signature in Gastric Autoimmunity.
No top-level findings curated for this source.
PMID:31963924
Proton Pump Inhibitor Use, Hypergastrinemia, and Gastric Carcinoids-What Is the Relationship?
No top-level findings curated for this source.
PMID:21174235
Cutting edge issues in autoimmune gastritis.
No top-level findings curated for this source.
PMID:28102858
Luminescent Immunoprecipitation System (LIPS) for Detection of Autoantibodies Against ATP4A and ATP4B Subunits of Gastric Proton Pump H+,K+-ATPase in Atrophic Body Gastritis Patients.
No top-level findings curated for this source.

Deep Research

1

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.

Claude Code ▸
Autoimmune Gastritis (AIG) — Comprehensive Research Report
claude-haiku-4-5-20251001, claude-sonnet-5 27 citations 2026-07-01T02:12:36.578553

Autoimmune Gastritis (AIG) — Comprehensive Research Report

1. Disease Information

Overview. Autoimmune gastritis (AIG) — also termed Type A gastritis, autoimmune metaplastic atrophic gastritis (AMAG), or chronic autoimmune atrophic gastritis — is a chronic, organ-specific autoimmune disease of the stomach in which autoreactive CD4+ T cells and autoantibodies destroy the acid-secreting parietal cells and intrinsic-factor-producing cells of the oxyntic (corpus/fundic) mucosa, sparing the antrum (Lenti et al., 2019, PMC; Ku PMC10378041). Progressive parietal cell loss produces achlorhydria, hypergastrinemia, oxyntic atrophy, intestinal/pseudopyloric metaplasia, and — via loss of intrinsic factor — vitamin B12 malabsorption culminating in pernicious anemia. Compensatory hypergastrinemia drives enterochromaffin-like (ECL) cell hyperplasia and predisposes to type 1 gastric neuroendocrine tumors (gNETs) as well as gastric adenocarcinoma (Frontiers 2026; Naples review, PMC12563516).

Identifiers. - No single dedicated MONDO/OMIM/Orphanet term captures "autoimmune gastritis" as its own top-level rare-disease entity; instead the entity is most often indexed through its end-organ consequence, pernicious anemia: Orphanet ORPHA:120 — "Pernicious anemia," explicitly flagged by Orphanet as "NON RARE IN EUROPE" and listed with synonyms "Addison-Biermer anemia," "Biermer disease," "acquired pernicious anemia," "juvenile onset pernicious anemia" (Orphanet, ORPHA:120). - Juvenile/early-onset pernicious anemia forms are catalogued in OMIM under the 261xxx congenital vitamin-B12-malabsorption/pernicious-anemia series (e.g., an entry around OMIM:261100); because these OMIM entries emphasize monogenic juvenile pernicious anemia rather than the adult autoimmune-mediated form, they should be treated as adjacent/partially-overlapping identifiers rather than a direct MONDO-equivalent for adult AIG — this should be independently verified against the live OMIM/MONDO record before being used as a KB mappings value. - MeSH: "Gastritis, Atrophic" (D005704) is the closest controlled MeSH heading; "Anemia, Pernicious" (D000752) covers the hematologic sequela. - ICD-10/11: ICD-10 K29.4 "Chronic atrophic gastritis"; ICD-11 DA42.2/related autoimmune-gastritis coding under digestive-system chronic gastritis; pernicious anemia is coded separately (ICD-10 D51.0). - Synonyms: Type A gastritis, autoimmune metaplastic atrophic gastritis (AMAG), autoimmune corpus-restricted (chronic) atrophic gastritis, autoimmune atrophic gastritis (AAG).

Data source type. Most of the literature synthesized below is aggregated disease-level evidence (cohort studies, systematic/position-paper reviews, GWAS meta-analyses of population biobanks — Estonian Biobank, UK Biobank, FinnGen) rather than individual EHR-level curation; a few large single/multi-institution retrospective cohorts (e.g., Italian, Japanese, Chinese series) are cited explicitly below.

2. Etiology

Primary causal mechanism. AIG is caused by a breakdown of self-tolerance to the gastric H⁺/K⁺-ATPase proton pump (the α- and β-subunits) on parietal cells and, in a subset, to intrinsic factor. Autoreactive CD4+ T cells (Th1, and Th17) recognize H⁺/K⁺-ATPase-derived peptides, secrete IFN-γ/IL-17, and mediate parietal cell apoptosis via Fas-FasL and perforin/granzyme B pathways; B cells produce complement-fixing anti-parietal-cell antibodies (PCA) and anti-intrinsic-factor antibodies (IFA) (Unraveling the Mysteries of AIG, PMC11899966; Immunological mechanisms of AIG, PMC12909420).

Genetic risk factors. - A 2021 genome-wide association meta-analysis (2,166 pernicious-anemia cases vs. 659,516 European controls pooled from the Estonian Biobank, UK Biobank, and FinnGen) identified five genome-wide-significant risk loci (Lahtela et al. 2021, Nature Communications, PMC8213695; PMID not directly retrieved but paper is Nat Commun 2021;12:3811): | Locus | Lead SNP | Gene | P-value | OR (95% CI) | |---|---|---|---|---| | 1p13.2 | rs6679677 | PTPN22 | 1.91×10⁻²⁴ | 1.63 (1.48–1.79) | | 2p16.1 | rs12616502 | PNPT1 | 3.14×10⁻⁸ | 1.70 (1.41–2.05) | | 6p21.32 | rs28414666 | HLA-DQB1 | 1.40×10⁻¹⁶ | 1.38 (1.28–1.49) | | 10p15.1 | rs2476491 | IL2RA | 1.90×10⁻⁸ | 1.22 (1.14–1.30) | | 21q22.3 | rs74203920 | AIRE (missense) | 2.33×10⁻⁹ | 1.83 (1.50–2.29) |

Direct quote: "We conduct a genome-wide association study meta-analysis in 2166 cases and 659,516 European controls from population-based biobanks and identify genome-wide significant signals." The PTPN22 lead SNP (rs6679677) is in strong LD with the well-known autoimmunity nonsynonymous variant rs2476601 in exon 12 of PTPN22, also implicated in rheumatoid arthritis, SLE, type 1 diabetes, vitiligo, and autoimmune thyroid disease. - HLA class II susceptibility alleles HLA-DRB1*03 and HLA-DRB1*04 are consistently reported as increasing risk, and the HLA-DR15 haplotype has been implicated by GWAS as well (Frontiers 2026; medRxiv preprint on HLA-DR15). - AIRE missense variants link AIG/pernicious anemia to the broader monogenic autoimmune polyendocrine syndrome type 1 (APS-1/APECED) spectrum, where recurrent AIRE loss-of-function alleles (R139X, R257X, W78R, C322fsX372, T16M, R203X, A21V in an Italian APS-1 cohort, n=158) predispose to AIG among other organ-specific autoimmunities. - Candidate/proton-pump genes: ATP4A, ATP4B (the antigen itself), plus SLC26A7, SLC26A9, SLC4A2 (acid-base transporters) and BACH2 (a broad autoimmunity susceptibility transcription factor) have emerging GWAS/candidate-gene support (Kalkan et al. 2023, PMC10378041; PMID: 37504250).

Environmental/infectious risk factors. - Helicobacter pylori is the leading environmental trigger hypothesis via molecular mimicry: the β-subunit of H. pylori urease shares high sequence homology with the β-subunit of gastric H⁺/K⁺-ATPase, generating cross-reactive T- and B-cell responses in genetically susceptible hosts (MDPI review PMID unlisted). Paradoxically, the relationship between active H. pylori infection and established AIG is complex/inverse in some cohorts — chronic H. pylori infection may itself trigger AIG onset, but established AIG is often H. pylori-negative at diagnosis, and some evidence suggests H. pylori-driven Th2 responses may suppress ongoing AIG in certain contexts. - Murine roseolovirus neonatal infection triggers CD4+ T-cell-dependent gastritis in mouse models, suggesting viral triggers merit further study in humans. - Smoking: not established as a direct AIG-specific trigger but is a well-documented independent and interactive risk factor for gastric atrophy, intestinal metaplasia, dysplasia, and gastric cancer, relevant to AIG's malignant-transformation risk. - Age and sex: female sex and age >50–60 are strong epidemiological risk correlates (see Section 9). - Family history / other autoimmunity: family clustering with autoimmune thyroid disease, type 1 diabetes, vitiligo strongly increases risk (see Section 9).

Protective factors. No validated protective genetic variant is established specifically for AIG; broadly, non-risk HLA haplotypes and, per emerging microbiome data, an intact butyrate-producing gut microbiota (e.g., Faecalibacterium prausnitzii) that sustains regulatory T cell (Treg) differentiation via short-chain fatty acids is hypothesized to be protective against Th17-driven progression (Frontiers 2026).

Gene-environment interaction. The PTPN22/HLA-DQB1/AIRE genetic background is proposed to lower the threshold for H. pylori-triggered molecular mimicry and epitope spreading to become self-perpetuating autoimmunity — i.e., infection acts as an environmental "second hit" in a genetically primed host, though this remains a mechanistic hypothesis rather than a proven causal chain in humans (a KNOWLEDGE_GAP/HUMAN_MODEL_MISMATCH candidate for KB curation).

3. Phenotypes

Most AIG is asymptomatic/subclinical for years; phenotypes span GI, hematologic, neurologic, and — indirectly — endocrine/dermatologic domains via associated autoimmunity.

Phenotype Type Onset/course Frequency Suggested HPO term
Dyspepsia / early satiety / postprandial fullness Symptom Adult, chronic/fluctuating ~47–60% (more common in young women, non-smokers) HP:0002018 (Dyspepsia)
Iron-deficiency anemia Laboratory abnormality Often precedes B12 deficiency by years ~20–50% HP:0011870 (Iron deficiency anemia)
Vitamin B12 deficiency / megaloblastic (pernicious) anemia Laboratory/clinical sign Insidious, adult (often 60s), progressive if untreated Defining late feature HP:0008163 (Decreased vitamin B12), HP:0001887 (Megaloblastic anemia)
Achlorhydria / hypochlorhydria Laboratory abnormality Progressive with atrophy Near-universal in advanced disease HP:0003204 (Achlorhydria, if modeled)
Hypergastrinemia Laboratory abnormality Compensatory, progressive Near-universal in advanced disease HP:0500152 (Abnormal circulating gastrin concentration) or similar
Gastric mucosal atrophy (oxyntic) Histopathologic sign Chronic, progressive (early→florid→end-stage over ~3 years per prospective cohorts) Defining lesion HP:0002608 (Atrophic gastritis, if present) / MONDO cross-ref
Glossitis Physical sign Secondary to B12/iron deficiency Variable HP:0000216 (Glossitis)
Peripheral neuropathy / paresthesia Symptom/sign Subacute, progressive if untreated Occurs with B12 deficiency HP:0003676 (Progressive; use with HP:0003390 Paresthesia)
Subacute combined degeneration of the spinal cord Clinical sign Late, progressive, potentially irreversible Uncommon but serious HP:0002314 (Subacute combined degeneration)
Ataxia Sign Progressive, B12-deficiency-related Uncommon HP:0001251 (Ataxia)
Type 1 gastric neuroendocrine tumor (ECL-cell carcinoid) Neoplastic complication Late, indolent ~2.8–11% cumulative (up to ~37% in some Chinese cohorts using sensitive detection) HP:0100633 (Neuroendocrine neoplasm)
Gastric adenocarcinoma Neoplastic complication Late, age >60 highest risk ~0.1–0.5%/year incidence; 3–5x general population risk HP:0012126 (Gastric adenocarcinoma, if available) / MONDO
Infertility / recurrent miscarriage Reproductive phenotype Adult women Reported in case series (n=168) HP:0000789 (Infertility)
Weight loss Symptom Variable Minority HP:0001824 (Weight loss)
Diarrhea Symptom Variable Minority, malabsorption-related HP:0002014 (Diarrhea)

Age of onset: Classically adult-onset (median age at diagnosis 61–67 years, range 18–94), but pediatric AIG is increasingly recognized — pediatric prevalence ~0.15% among children undergoing gastric biopsy, mean diagnosis age 10.9 years, with striking 68.2% female predominance and 59.1% presenting with a concurrent extragastric autoimmune disorder (Kalkan et al., PMC10378041).

Severity/progression: A prospective cohort of 270 patients found histopathology in all patients progressed over time (generally within 3 years) from mild to severe/end-stage, with no observed spontaneous regression — supporting a monotonically progressive natural history once autoimmunity is established (PMC8414617). A separate prospective study reported an annual progression rate of 10.9% from "potential" (seropositive, histologically normal) to "overt" AAG (PMID: 38050966).

Quality of life: Neurological B12-deficiency sequelae, if diagnosis is delayed, are described as "inexorably progressive," while early diagnosis and lifelong B12 replacement largely normalizes hematologic and neurologic function; dyspeptic symptoms in early disease modestly affect quality of life but are frequently under-recognized because most patients are asymptomatic.

4. Genetic/Molecular Information

AIG is a complex/polygenic autoimmune disease, not a single-gene Mendelian disorder (contrast with monogenic APS-1/AIRE, which is a Mendelian cause of syndromic AIG).

  • Causal antigen genes (autoantigen targets, not classically "causal mutations"): ATP4A (HGNC:816, H⁺/K⁺-ATPase α-subunit) and ATP4B (HGNC:817, β-subunit) encode the gastric proton pump targeted by PCA; intrinsic factor is encoded by GIF (HGNC:4256).
  • Susceptibility loci (GWAS-confirmed, see Section 2): PTPN22 (HGNC:9646), PNPT1 (HGNC:23349), HLA-DQB1 (HGNC:4944), IL2RA (HGNC:6008), AIRE (HGNC:360).
  • Variant classification: The PTPN22 signal tags the well-characterized rs2476601 (R620W) gain-of-function/loss-of-inhibitory-function missense variant recurrent across autoimmune disease (not AIG-specific, pleiotropic risk allele — not a Mendelian pathogenic variant in the ACMG sense). The AIRE signal (rs74203920) is annotated as missense in the GWAS meta-analysis; distinct, more severe AIRE loss-of-function alleles (R139X, W78R, R257X, C322fsX372, etc.) cause monogenic APS-1/APECED, of which AIG is one of several organ-specific autoimmune components.
  • Allele frequency: The PTPN22 rs2476601 minor allele frequency is well characterized in European populations (~10–12% in gnomAD/1000 Genomes; enriched across multiple autoimmune GWAS) — population-level data should be pulled from gnomAD directly for KB curation rather than assumed here.
  • Somatic vs. germline: All described genetic risk variants (PTPN22, HLA-DQB1, IL2RA, AIRE, PNPT1) are germline susceptibility alleles; there is no described somatic-mutation mechanism for AIG itself (somatic events become relevant only in the neoplastic complications — gNETs and gastric adenocarcinoma — as separate downstream processes).
  • Functional consequences: PTPN22 R620W disrupts a phosphatase involved in T-cell receptor signaling attenuation, lowering the threshold for autoreactive T-cell activation (loss of inhibitory function); AIRE variants impair thymic promiscuous gene expression and central tolerance induction, permitting escape of autoreactive T-cell clones (loss of function).
  • Modifier genes: BACH2 (broad Treg/Th differentiation modifier across autoimmune diseases) and SLC26A7/SLC26A9/SLC4A2 (ion transporters co-expressed with the H⁺/K⁺-ATPase, potentially modifying antigen exposure/epithelial stress) are proposed modifiers rather than primary drivers.
  • Epigenetics: Emerging but sparse data — aberrant DNA methylation patterns and altered microRNA profiles (miR-21 elevated, miR-223 reduced in gastric mucosa) are reported in AIG and associated with progression toward dysplasia/carcinoma, but comprehensive methylome/histone studies specific to AIG are lacking (a documented knowledge gap).
  • Chromosomal abnormalities: None described as causal for typical AIG; trisomy 21 (Down syndrome) carries a recognized comorbid association with autoimmune (including gastric) disease and pernicious anemia (case reports), reflecting broader autoimmune susceptibility rather than a specific gastric mechanism.

5. Environmental Information

  • Infectious trigger: Helicobacter pylori — proposed via molecular mimicry between its urease β-subunit and the gastric H⁺/K⁺-ATPase β-subunit; also implicated via chronic inflammation, polyclonal lymphocyte activation, epitope spreading, and bystander activation (MDPI 2025). Murine roseolovirus neonatal infection is a model-organism-demonstrated viral trigger (mouse), of uncertain human relevance.
  • Lifestyle: Smoking is an established independent/synergistic risk factor for gastric mucosal atrophy, intestinal metaplasia, and gastric cancer generally, relevant to AIG's malignant potential, though not shown to specifically initiate the autoimmune process. Diet/alcohol have not been robustly linked to AIG initiation specifically (as opposed to gastric cancer risk broadly).
  • Microbiome: Hypochlorhydria from parietal cell loss reshapes the gastric niche, permitting overgrowth of non-Helicobacter taxa (Streptococcus, Lactobacillus, Veillonella); dysbiosis-associated loss of short-chain-fatty-acid-producing species (e.g., Faecalibacterium prausnitzii) is hypothesized to impair Treg differentiation and worsen Th17-driven inflammation, and Bacillus cereus has been reported enriched specifically in AIG-related gastric cancer.
  • Occupational/toxin exposures: No specific validated occupational or toxin exposure is established for AIG.

6. Mechanism / Pathophysiology

Causal chain (upstream → downstream):

  1. Genetic susceptibility (HLA-DRB1*03/*04, HLA-DQB1, PTPN22 R620W, AIRE variants, IL2RA, PNPT1) lowers central/peripheral tolerance thresholds →
  2. Antigen exposure/trigger — possible H. pylori molecular mimicry of gastric H⁺/K⁺-ATPase β-subunit, or other unidentified triggers →
  3. Autoreactive CD4+ T-cell activation: dendritic cells process H⁺/K⁺-ATPase peptides and, via IL-12/IL-23, drive differentiation into Th1 (IFN-γ, TNF-α) and Th17 (IL-17A/E/F, IL-21, IL-22) effector subsets; innate lymphoid cells (ILC3) reinforce IL-17/IL-22 output →
  4. Cytotoxic effector mechanisms against parietal cells: (a) Fas upregulation on parietal cells + FasL-expressing T/NK cells assembling the death-inducing signaling complex (DISC) → caspase-8 activation; (b) perforin/granzyme B cytotoxicity from NK cells (~20% of gastric mucosal lymphocytes) and cytotoxic T cells; (c) B-cell-derived anti-parietal cell antibodies (PCA) targeting H⁺/K⁺-ATPase α/β-subunits and anti-intrinsic factor antibodies (IFA), mediating complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity →
  5. Epithelial stress amplification: inflammatory cytokines (IL-1β, TNF-α) trigger ER stress/unfolded protein response via the PERK–eIF2α–ATF4–CHOP axis, downregulating Bcl-2 and activating Bax, driving mitochondrial-pathway apoptosis; impaired autophagic flux further sensitizes parietal cells to apoptosis (PMC12563516) →
  6. Parietal cell loss → oxyntic (corpus/fundic) mucosal atrophy, with tissue remodeling sustained by gastric myofibroblasts and eosinophil infiltration; pseudopyloric and intestinal metaplasia develop as replacement phenotypes →
  7. Loss of gastric acid (achlorhydria) removes the normal negative-feedback on antral G cells → chronic hypergastrinemia →
  8. Gastrin–CCK2R signaling on ECL cells: activates ERK/MAPK (Ras-Raf-MEK-ERK → cyclin D1, c-Myc), PI3K/Akt (→ Bad inactivation, mTOR survival signaling), and STAT3 (→ Bcl-xL, VEGF) cascades, driving ECL cell hyperplasia, which can progress to dysplasia and type 1 gastric neuroendocrine tumors →
  9. Loss of intrinsic factor (from parietal/IF-producing cell destruction, compounded by anti-IF antibodies blocking IF-B12 binding or the IF-B12-cubilin receptor interaction in the terminal ileum) → vitamin B12 malabsorption → megaloblastic pernicious anemia and, if prolonged, subacute combined degeneration of the spinal cord and peripheral neuropathy →
  10. Chronic atrophic/metaplastic mucosa is an independent field of increased gastric adenocarcinoma risk (3–5× general population), compounding the ECL/gNET pathway.

Cell types involved (Cell Ontology candidates): parietal cell (CL:0000160), chief/zymogenic cell (CL:0000155), enterochromaffin-like cell (CL:0000502 or closest ECL-cell term), gastric mucous neck/foveolar cell, gastric G cell (gastrin-producing enteroendocrine cell), Th1 CD4+ T cell (CL:0000545-derived Th1 subset), Th17 CD4+ T cell, cytotoxic CD8+ T cell (CL:0000625), NK cell (CL:0000623), plasma/B cell (CL:0000786), dendritic cell (CL:0000451), ILC3 (CL:0001071), gastric myofibroblast, eosinophil (CL:0000771).

Biological processes (GO candidates): T-cell mediated cytotoxicity (GO:0001913), Fas signaling pathway (GO:0036337/apoptotic signaling via death domain receptors, GO:0008625), complement-dependent cytotoxicity, endoplasmic reticulum unfolded protein response (GO:0030968), regulation of apoptotic process (GO:0042981), autophagy (GO:0006914), positive regulation of interleukin-17 production (GO:0032740), cellular response to interferon-gamma (GO:0071346), response to gastrin (if modeled), MAPK cascade (GO:0000165), PI3K signaling (GO:0014065), regulation of vitamin B12 transport/intrinsic factor binding.

Molecular profiling: microRNA dysregulation (miR-21↑, miR-223↓) is reported in gastric mucosa; transcriptomic/proteomic/metabolomic single-cell or spatial datasets specific to AIG are not yet well established in public repositories (GEO/HCA) — an area flagged as an evidence gap in recent reviews.

Single-cell/advanced technologies: No mature single-cell atlas of human AIG gastric mucosa was identified in this search; this is an emerging-technology gap consistent with the "Human studies validating ER stress and autophagy dysfunction remain limited" caveat explicitly raised in the cellular-crosstalk review (PMC12563516).

7. Anatomical Structures Affected

  • Primary organ: Stomach, specifically the oxyntic mucosa of the corpus/fundus (UBERON:0001162 body of stomach / UBERON:0001156 gastric fundus), sparing the antrum (contrast with H. pylori-associated multifocal/antral-predominant gastritis).
  • Secondary organ involvement:
  • Hematologic system (bone marrow megaloblastic changes from B12 deficiency)
  • Nervous system (peripheral nerves, dorsal columns/lateral corticospinal tracts of the spinal cord — subacute combined degeneration)
  • Small intestine (terminal ileum, site of intrinsic-factor-mediated B12 absorption, secondarily affected functionally though not structurally)
  • Reproductive system (infertility/miscarriage reported)
  • Thyroid, pancreatic islets, skin/melanocytes (via associated autoimmune comorbidities, not direct AIG pathology)
  • Body systems: digestive, hematologic/immune, nervous, and (via comorbidity) endocrine and integumentary systems.
  • Tissue/cell level: gastric oxyntic (fundic) glands — parietal cells, chief cells, ECL cells, mucous neck cells; lamina propria immune infiltrate (T cells, B/plasma cells, eosinophils, mast cells); antral G cells (indirectly, via hypergastrinemia feedback, though G-cell hyperplasia itself can occur).
  • Subcellular level: mitochondria (apoptosis via Bax/Bcl-2, cytochrome c release), endoplasmic reticulum (UPR/PERK-eIF2α-ATF4-CHOP stress pathway), apical canalicular membrane of parietal cells (H⁺/K⁺-ATPase proton pump localization — GO Cellular Component: apical plasma membrane, GO:0016324).
  • Localization/laterality: Gastric involvement is typically diffuse within the corpus/fundus (not lateralized); neurological B12-deficiency manifestations can be bilateral and symmetric (peripheral neuropathy, subacute combined degeneration).

8. Temporal Development

  • Onset: Predominantly adult-onset, insidious; median diagnosis age 61–67 years (range 18–94). A distinct pediatric-onset phenotype exists (mean age 10.9 years, prevalence ~0.15% among biopsied children), often with strong concurrent extragastric autoimmunity.
  • Onset pattern: Chronic/insidious rather than acute; disease may be "silent" for years before serologic (PCA/IFA) positivity converts to histologic and clinical disease.
  • Progression/staging (histopathologic 3–5 stage models):
  • Stage 0 / "potential" AIG: seropositive (PCA/IFA+) but histologically normal or minimally abnormal.
  • Early phase: mild-to-moderate oxyntic atrophy, CD4+ lymphocytic infiltration, pseudopyloric metaplasia; parietal cells may show compensatory hypertrophy.
  • Florid phase: moderate-to-severe oxyntic gland atrophy, dense lymphoplasmacytic inflammation, ECL cell hyperplasia, intestinal metaplasia.
  • End-stage: severe gland loss, extensive intestinal metaplasia/dysplasia, ECL hyperplasia, paradoxically reduced active inflammation.
  • Progression rate: A prospective study of "potential" to "overt" AAG reported an annual progression rate of 10.9%; a separate 270-patient prospective cohort found histology progressed in essentially all patients within ~3 years with no spontaneous regression observed.
  • Disease course pattern: Monotonically progressive (not relapsing-remitting) at the histologic/immunologic level, though symptom burden can fluctuate.
  • Duration: Chronic, lifelong once established; the underlying autoimmune/atrophic process does not resolve spontaneously, though its hematologic and neurologic consequences (B12/iron deficiency) are effectively controlled with lifelong replacement therapy.
  • Critical periods: The seropositive "potential" phase represents a clinically important window for early detection before irreversible gland atrophy and before neurologic B12-deficiency sequelae become established; the pediatric-onset subgroup's long-term natural history remains largely unstudied (explicit knowledge gap).

9. Inheritance and Population

Epidemiology. - Prevalence: Estimated ~0.1–2% in the general population, rising to 2–3% in adults over 60. Endoscopic-biopsy cohort studies: USA (1988–2008, n=41,245 biopsies) ~1.1%; Japan (asymptomatic screening) ~0.49%; European multicenter gastritis cohorts ~2% among biopsied gastritis cases; lower prevalence reported in a large Chinese cohort (n=97,341) (Lenti et al., PMC8414617). - Ethnic/geographic variation: Non-white Hispanic populations show higher prevalence (~2.7%) versus ~1% in white, Asian, and African-American populations in some U.S. cohort data; earlier age of onset reported in non-white groups in some studies. - Sex ratio: Consistent female predominance, roughly 2–3:1 (F:M) across adult cohorts; the pediatric cohort shows an even more pronounced 68.2% female skew. - Age distribution: Bimodal-ish — a small pediatric-onset group (mean ~10.9 years) and the dominant adult/elderly-onset group (median 61–67 years).

Inheritance pattern: AIG is a complex/polygenic (multifactorial) trait, not Mendelian, driven by additive/interacting common variants (PTPN22, HLA-DQB1, IL2RA, PNPT1) plus environmental triggers. The exception is syndromic AIG occurring as one manifestation of monogenic autosomal recessive APS-1/APECED (biallelic AIRE loss-of-function), which follows classic Mendelian AR inheritance with high penetrance for the syndrome overall but variable penetrance/expressivity for the gastric component specifically.

Penetrance/expressivity: For the common polygenic form, individual risk-allele penetrance is low (as expected for GWAS-identified common variants, ORs 1.2–1.8); for AIRE-driven APS-1, the AIRE genotype has high penetrance for autoimmune polyendocrinopathy overall, but expressivity across specific component diseases (including AIG) is variable between AIRE-mutation carriers.

Genetic anticipation / mosaicism / founder effects: Not described for AIG's common polygenic form. AIRE founder mutations are known in specific populations (e.g., Finnish, Iranian Jewish, Sardinian founder alleles for APS-1), relevant to any AIG occurring in that syndromic context, but this is a population feature of APS-1 rather than of idiopathic AIG.

Consanguinity: Relevant only to the rare AR-AIRE/APS-1 syndromic route, not to typical polygenic AIG.

Carrier frequency: Not meaningfully defined for a polygenic trait; APS-1/AIRE carrier frequencies are population-specific and available via GeneReviews/GTR for that distinct monogenic condition.

Associated autoimmune comorbidity (polyautoimmunity): - Autoimmune thyroid disease: reported concurrently in 36–44% of AIG patients in some series (other sources cite ~2.8% in specific cohorts — figures vary substantially by study design/population, underscoring heterogeneity). - Type 1 diabetes: AIG/pernicious anemia risk in T1D patients is ~3–5× the general population; conversely, among T1D patients, 5–10% have AIG/pernicious anemia, 15–30% have autoimmune thyroid disease, 2–10% have vitiligo, and up to one-third develop a broader autoimmune polyglandular syndrome. - Vitiligo, rheumatoid arthritis, psoriasis, autoimmune hepatitis, myasthenia gravis, Sjögren syndrome, autoimmune hemolytic anemia are also reported comorbid associations, consistent with a "multiple autoimmune syndrome" (MAS) pattern (Autoimmune Institute review; PMC6146093 editorial). - Case reports also document AIG co-occurring with primary biliary cholangitis, non-nodal mantle cell lymphoma progression, and Down syndrome-associated pernicious anemia.

10. Diagnostics

Serologic tests (first-line, "serological biopsy" panel): - Anti-parietal cell antibodies (PCA): sensitivity ~81–90%, specificity ~88–90% (varies by assay/cohort). - Anti-intrinsic factor antibodies (IFA): lower sensitivity (~27–32%) but very high specificity (95–100%). - Newer ATP4A/ATP4B luciferase immunoprecipitation assays: ATP4A sensitivity ~75%/specificity ~88%; ATP4B sensitivity ~77%/specificity ~88% — proposed as improved, more standardized alternatives to conventional immunofluorescence PCA testing (Lenti/Massironi review, PMC11354099). - Serum pepsinogen I (PGI) and PGI/PGII ratio: low PGI (<70 µg/L, cutoffs vary by study) or low ratio (<2.1, <1.8, <3 depending on study/population) indicates oxyntic atrophy; sensitivity/specificity in the 67–100% range depending on cutoff and cohort. - Serum gastrin-17: elevated (>355 pg/mL in one study; various pmol/L cutoffs elsewhere) reflects loss of acid-mediated negative feedback and is a reliable marker of oxyntic atrophy; combined PGI/II + gastrin-17 panels reach ~88.9% accuracy for identifying NET-bearing patients. - Commercial panel: GastroPanel® (PGI, PGII, gastrin-17, H. pylori IgG) used for non-invasive screening. - Chromogranin A: elevated with ECL hyperplasia/NET development; used to monitor NET burden and treatment response (e.g., to netazepide/somatostatin analogs). - Novel immune marker: antral CD8+/CD4+ T-lymphocyte ratio >4.0 (sensitivity 71.4%, specificity 93.3%) proposed to distinguish AIG from H. pylori-associated gastritis histologically.

Endoscopy/histology (gold standard): - Endoscopic findings: sticky adherent mucus, scattered whitish protrusions, remnant oxyntic mucosal islands, patchy redness, hyperplastic polyps (in a 245-patient Japanese cohort). - Biopsy protocol: Updated Sydney System — minimum 5 biopsies (2 antrum, 1 incisura, 2 corpus) to allow topographic (corpus vs. antrum) comparison, essential to distinguish corpus-restricted AIG atrophy from antral-predominant H. pylori gastritis. - OLGA/OLGIM staging: combines topography with atrophy (OLGA) or intestinal metaplasia (OLGIM) severity into stages 0–IV; stage 0–II = lower cancer risk (surveillance every 3–5 years), stage III–IV = higher risk (surveillance every 1–2 years). - Histologic 3–5 stage model of disease progression as described in Section 8.

Differential diagnosis: H. pylori-associated (multifocal/antral-predominant) chronic gastritis; NSAID/chemical (reactive) gastropathy; other causes of iron/B12 deficiency (celiac disease, dietary deficiency, small intestinal bacterial overgrowth, pancreatic exocrine insufficiency, terminal ileal disease/resection); lymphocytic gastritis; Zollinger-Ellison syndrome (also causes hypergastrinemia, but via a gastrinoma rather than achlorhydria-driven feedback loss — distinguished by gastric pH/secretin stimulation testing).

Genetic testing: No first-line clinical genetic test is used for typical polygenic AIG (unlike Mendelian disorders); AIRE sequencing is indicated only when syndromic APS-1/APECED is clinically suspected (mucocutaneous candidiasis, hypoparathyroidism, adrenal insufficiency plus AIG).

Screening: No population-wide screening program exists for sporadic AIG; targeted serologic screening (PCA/IFA, pepsinogens) is reasonable in patients with unexplained iron or B12 deficiency, first-degree relatives of AIG patients, or patients with another organ-specific autoimmune disease (thyroid, T1D, vitiligo) given comorbidity rates.

11. Outcome/Prognosis

  • Mortality/survival: AIG itself is not directly fatal; prognosis is driven by (a) adequacy of B12/iron replacement and (b) surveillance for malignant complications. With appropriate lifelong vitamin replacement, hematologic and most neurologic manifestations are controlled or reversed if caught early.
  • Neurologic morbidity: Untreated/delayed B12 deficiency produces "inexorably progressive" neurologic injury (peripheral neuropathy → subacute combined degeneration → ataxia/weakness), which can become irreversible if replacement is delayed — underscoring the importance of early diagnosis.
  • Neoplastic risk/complications:
  • Type 1 gastric neuroendocrine tumors (gNETs): cumulative incidence ~2.8%/person-year in some cohorts, ~4.7% at 2 years in others; up to 10–37% prevalence in various case series depending on detection sensitivity and population; generally indolent — tumors <1 cm and Ki-67 ≤2% managed with surveillance; favorable prognosis overall, with <10% metastasis rate for lesions <2 cm.
  • Gastric adenocarcinoma: risk estimated at 3–5× (some sources: 7×) the general population; annual incidence ~0.1–0.5%/person-year; risk factors within the AIG population include age >60 (HR ~4.7), intestinal metaplasia without pseudopyloric metaplasia (HR ~4.3), and pernicious anemia (HR ~4.3). Notably, recent prospective cohorts restricted to H. pylori-negative AAG patients reported no gastric adenocarcinoma cases, suggesting that much of the historically reported cancer risk in AIG populations may be attributable to prior/concurrent H. pylori infection rather than the autoimmune process alone — an important nuance for risk stratification and a candidate HUMAN_MODEL_MISMATCH/knowledge-gap note.
  • Prognostic factors: age at diagnosis, degree of atrophy/OLGA-OLGIM stage, H. pylori status (past or present), presence of dysplasia, and B12-deficiency neurologic involvement at diagnosis.
  • Quality of life: Largely normalized with treatment in early-detected disease; unaddressed B12 deficiency and neuroendocrine tumor development are the main drivers of long-term morbidity.

12. Treatment

Pharmacotherapy (replacement/supportive): - Vitamin B12: lifelong intramuscular (or high-dose sublingual/oral) cyanocobalamin/hydroxocobalamin supplementation — first-line, definitive management of the pernicious-anemia component. MAXO candidate: pharmacotherapy generically, or a dietary/vitamin-supplementation MAXO term if available; NCIT:C15986 (Pharmacotherapy) with a CHEBI therapeutic_agent (e.g., CHEBI cyanocobalamin) is the dismech-pattern annotation. - Iron: oral iron (often with vitamin C to enhance absorption in the achlorhydric stomach) or, if oral therapy fails (due to hypochlorhydria-impaired absorption), intravenous iron infusion. Iron status should be checked in all AIG patients regardless of overt anemia, given corpus-predominant atrophy's impact on non-heme iron absorption. - Acid-suppressive therapy caution: PPIs are generally NOT recommended in AIG, since patients already have hypochlorhydria/achlorhydria and PPIs would exacerbate hypergastrinemia and ECL hyperplasia risk; H2-receptor antagonists (e.g., famotidine) are preferred if short-term acid-related symptom control is needed, and PPIs are reserved for short-term severe reflux esophagitis only.

Management of neoplastic complications: - Type 1 gNETs: small (<1 cm, Ki-67 ≤2%) lesions managed by endoscopic surveillance; larger (>1 cm) or higher-grade lesions undergo endoscopic resection (surveillance every 6–12 months post-resection per ESGE guidelines); refractory/recurrent cases may proceed to antrectomy (removes the gastrin-secreting antral mucosa, normalizing gastrin levels) or medical gastrin-pathway blockade. - Netazepide (a gastrin/CCK2-receptor antagonist): reduces chromogranin A and can shrink/eradicate type 1 gNETs in patients with autoimmune chronic atrophic gastritis, though continuous treatment is needed to prevent recurrence (PMC5306499). - Somatostatin analogs (e.g., octreotide, lanreotide): reported response rates ~25–100% for type 1 NETs across small studies. - Gastric adenocarcinoma: managed per standard gastric cancer oncologic pathways (endoscopic resection for early lesions, surgery/chemotherapy for advanced disease) — not AIG-specific.

Endoscopic surveillance: Regular high-definition upper endoscopy with systematic biopsy (per Sydney System protocol), frequency tailored to OLGA/OLGIM risk stage — every 3–5 years for low-risk (stage 0–II) and every 1–2 years for high-risk (stage III–IV) or NET-bearing patients.

Emerging/experimental: - Immunomodulatory therapy: limited evidence suggests corticosteroids or other immunosuppressants might help in early, highly inflammatory disease stages, though no targeted immunotherapy is currently approved. - Th17/IL-17-axis-targeted biologics (e.g., anti-IL-17 monoclonal antibodies like secukinumab/ixekizumab, approved in psoriasis/spondyloarthropathy) are mechanistically plausible given the Th17 contribution to AIG pathogenesis, but are not yet studied/approved specifically for AIG (an explicit translational gap). - Microbiota-targeted approaches: probiotic supplementation (e.g., Faecalibacterium prausnitzii) or fecal microbiota transplantation are proposed research directions to restore Treg-supportive short-chain-fatty-acid production, but remain preclinical/conceptual for AIG. - AI-assisted endoscopy: deep-learning-based image analysis reported to achieve diagnostic accuracy for atrophic changes comparable to or exceeding experienced endoscopists — an emerging diagnostic-support tool rather than a treatment.

Treatment algorithm summary: (1) confirm diagnosis serologically + histologically → (2) lifelong B12 replacement (parenteral) + iron repletion as needed → (3) OLGA/OLGIM-stratified endoscopic surveillance → (4) targeted intervention (endoscopic resection, antrectomy, netazepide/somatostatin analog) if type 1 gNET or dysplasia/adenocarcinoma develops → (5) screen for/monitor associated autoimmune comorbidities (thyroid, T1D, vitiligo).

13. Prevention

  • Primary prevention: No established primary prevention exists for the autoimmune initiation of AIG itself (unlike infectious or vaccine-preventable disease); H. pylori eradication in infected individuals is standard gastritis/gastric-cancer prevention practice generally, though its specific effect on preventing AIG onset is unproven and the relationship is complex (see Section 5).
  • Secondary prevention (early detection): Targeted serologic screening (PCA/IFA, pepsinogen, gastrin-17) in high-risk groups — first-degree relatives of AIG patients, patients with unexplained iron/B12 deficiency, and patients with another organ-specific autoimmune disease (autoimmune thyroiditis, type 1 diabetes, vitiligo) — enables detection at the "potential"/seropositive stage before irreversible atrophy or neurologic injury.
  • Tertiary prevention: Structured endoscopic surveillance (OLGA/OLGIM-stratified) prevents progression from dysplasia to invasive gastric adenocarcinoma and enables early resection of type 1 gNETs before they enlarge or (rarely) metastasize; lifelong B12/iron replacement prevents irreversible hematologic and neurologic complications.
  • Genetic counseling: Relevant primarily in the rare monogenic APS-1/AIRE-driven syndromic context (recurrence risk counseling for autosomal recessive AIRE variants), not for typical sporadic polygenic AIG.
  • Public health: No population-level public health intervention (vaccination, sanitation) is applicable; the closest public-health-relevant lever is H. pylori screening/eradication programs in high-gastric-cancer-incidence regions, which have ancillary relevance to the atrophic-gastritis-to-cancer pathway generally.

14. Other Species / Natural Disease

  • Taxonomy: Naturally occurring/experimentally induced autoimmune gastritis has been most extensively studied in mouse (Mus musculus, NCBITaxon:10090).
  • Natural/spontaneous disease in animals: C3H/He mice develop spontaneous autoimmune gastritis without experimental manipulation, serving as a natural-disease model for gastric autoimmunity (PMID: 9777963).
  • Veterinary relevance: No major companion-animal or livestock natural-disease correlate of human AIG was identified in this search; the mouse models above are laboratory rather than veterinary-clinical observations.
  • Orthologous genes: Mouse Atp4a/Atp4b (orthologs of human ATP4A/ATP4B) are the principal autoantigens in murine models, directly paralleling the human disease target.
  • Comparative pathology: Murine neonatal-thymectomy-induced gastritis is histologically and immunologically similar to human pernicious-anemia-associated atrophic gastritis — chronic mononuclear infiltrate, destruction of parietal and zymogenic (chief) cells, and autoantibodies to H⁺/K⁺-ATPase α- and β-subunits (PMID: 1648525; PMID: 9272282).
  • Zoonotic potential: Not applicable — AIG is a non-infectious autoimmune process, not a transmissible disease.

15. Model Organisms

  • Neonatal thymectomy mouse model: ~60% of neonatally thymectomized BALB/c mice spontaneously develop autoimmune gastritis, driven by depletion of CD4+CD25+ regulatory T cells; histologically and serologically similar to human pernicious-anemia-associated gastritis, with autoantibodies against H⁺/K⁺-ATPase α- and β-subunits (Clinical and Experimental Immunology; PMID: 1648525, PMID: 9272282). The thymic (rather than purely gastric) expression pattern of the α-subunit in BALB/c thymus is proposed to explain the dominant pathogenic role of the β-subunit.
  • Spontaneous C3H/He mouse model: A genetically distinct strain (C3H/He) develops autoimmune gastritis spontaneously without thymectomy, offering a complementary "new mouse model for gastric autoimmunity" (PMID: 9777963).
  • Immunization-induced model: Immunization of mice with purified gastric H⁺/K⁺-ATPase induces a reversible autoimmune gastritis, useful for dissecting antigen-specific initiation and potential resolution/tolerance mechanisms (PMC1363986).
  • TxA23 TCR-transgenic / polyclonal effector T-cell transfer models: Adoptive transfer of H⁺/K⁺-ATPase-specific effector T cells (including Th1, Th2, and Th17 subsets) produces autoimmune gastritis with distinct histopathologic patterns and differential susceptibility to suppression by regulatory T cells depending on the transferred effector subset (PMC2561289) — this system has been particularly informative for dissecting how Th1 vs. Th17-driven disease differs mechanistically and in Treg-responsiveness, directly informing the Th17/Treg-axis therapeutic hypotheses discussed in Section 12.
  • Model characteristics/limitations: Mouse models robustly recapitulate the core autoantigen (H⁺/K⁺-ATPase), the T-cell-mediated destructive mechanism, and downstream atrophic/metaplastic histology, but do not fully model the human-specific downstream consequences — chronic ECL hyperplasia progressing to type 1 gastric NETs and long-term gastric adenocarcinoma risk are less consistently reproduced in short-lived rodent models, and human-specific comorbid polyautoimmunity (thyroid, T1D, vitiligo clustering) is not intrinsically modeled by single-antigen mouse systems. This human-model translational gap (mouse captures initiation/parietal-cell-destruction biology well, but not the full human neoplastic-complication trajectory) is a strong candidate for a HUMAN_MODEL_MISMATCH discussion in a dismech KB entry.
  • Research applications: These models have been used to define the H⁺/K⁺-ATPase α/β-subunit antigenic hierarchy, the CD4+CD25+ Treg-dependent tolerance mechanism, and differential Th1/Th2/Th17 pathogenicity and Treg-suppressibility — directly supporting current human therapeutic hypotheses around Treg restoration and Th17-cytokine blockade.
  • Resources: MGI (Mouse Genome Informatics) for Atp4a/Atp4b strain and allele records; no dedicated ZFIN/FlyBase/WormBase model of autoimmune gastritis was identified (unsurprising, as gastric parietal cell autoimmunity is a mammalian-immune-system-dependent phenomenon without a clear invertebrate correlate).

Summary of Key Ontology Term Suggestions for KB Curation

  • Genes (HGNC): ATP4A (hgnc:816), ATP4B (hgnc:817), GIF (hgnc:4256), PTPN22 (hgnc:9646), PNPT1 (hgnc:23349), HLA-DQB1 (hgnc:4944), IL2RA (hgnc:6008), AIRE (hgnc:360), BACH2 (hgnc:939)
  • Cell types (CL): parietal cell, chief cell, enterochromaffin-like cell, gastric G cell, Th1/Th17 CD4+ T cell, NK cell, plasma cell, dendritic cell
  • Biological processes (GO): T-cell mediated cytotoxicity, Fas-mediated apoptosis, ER stress/UPR, autophagy, IL-17 production, MAPK cascade, PI3K-Akt signaling
  • Phenotypes (HP): megaloblastic anemia, iron deficiency anemia, subacute combined degeneration, ataxia, glossitis, dyspepsia, neuroendocrine neoplasm
  • Anatomy (UBERON): body of stomach/gastric fundus (oxyntic mucosa), antrum, spinal cord dorsal columns
  • Chemicals (CHEBI): cyanocobalamin/hydroxocobalamin, ferrous sulfate, netazepide
  • Treatments (MAXO/NCIT): NCIT:C15986 (Pharmacotherapy) + therapeutic_agent for B12/iron; endoscopic resection/surveillance (MAXO surgical/procedural terms)

Important caveat for curation: I was unable to definitively confirm a dedicated MONDO/OMIM identifier specifically for "autoimmune gastritis" as distinct from pernicious anemia (ORPHA:120) during this search — recommend an explicit OAK/MONDO-browser lookup (runoak -i sqlite:obo:mondo search "autoimmune gastritis") before committing any mappings: block to a disorder YAML, per the project's anti-hallucination ontology-verification SOP.

Sources