Polarized primary human small-intestinal epithelial monolayers grown on a permeable scaffold to study epithelial injury, permeability, and luminal to basolateral flux.
epithelial injury
intestinal barrier dysfunction
paracellular permeability
intestinal epithelial cell
CL:0002563
Cell Ontology (CL)
Relation: this experimental model uses this cell type
This experimental model uses intestinal epithelial cell (CL:0002563). CL:0002563 is a cell type from the Cell Ontology.
Organism
human
NCBITaxon:9606
NCBI Taxonomy (NCBITaxon)
Relation: this experimental model is built in this organism
This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Tissue
small intestine
UBERON:0002108
Uberon multi-species anatomy ontology (UBERON)
Relation: this experimental model uses this anatomical location
This experimental model uses small intestine (UBERON:0002108). UBERON:0002108 is an anatomical location from the Uberon multi-species anatomy ontology.
Cell source
Primary human small-intestinal epithelial cells
Culture
Polarized two-dimensional monolayer on a permeable support
Findings
Primary human small-intestinal monolayers support direct measurement of epithelial injury and paracellular barrier permeability
Evidence: 1
Evidence: 1
Celiac monocyte-epithelial coculture barrier model
CO_CULTURE
Human CD14-positive monocytes from patients or controls cocultured with intestinal epithelial cells to study cytokine-driven changes in barrier resistance and tight-junction composition.
intestinal barrier dysfunction
cytokine-driven tight-junction alteration
immune-epithelial crosstalk
intestinal epithelial cell
CL:0002563
Cell Ontology (CL)
Relation: this experimental model uses this cell type
This experimental model uses intestinal epithelial cell (CL:0002563). CL:0002563 is a cell type from the Cell Ontology.
monocyte
CL:0000576
Cell Ontology (CL)
Relation: this experimental model uses this cell type
This experimental model uses monocyte (CL:0000576). CL:0000576 is a cell type from the Cell Ontology.
Organism
human
NCBITaxon:9606
NCBI Taxonomy (NCBITaxon)
Relation: this experimental model is built in this organism
This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Cell source
Human CD14-positive peripheral monocytes cocultured with Caco2BBe intestinal epithelial cells
Culture
Two-dimensional epithelial-monocyte coculture
Pathograph links
Paracellular Barrier Leak
Represents reduced transepithelial resistance and tight-junction alteration under inflammatory coculture conditions.
Findings
Disease-associated monocytes can induce barrier resistance loss and tight-junction alteration in intestinal epithelial cells
Evidence: 1
Evidence: 1
Epithelial Stress and Injury
trigger
Immune-mediated, toxic, microbial, or treatment-related insults injure the intestinal mucosa and epithelial compartment. Across diseases, this includes crypt injury, enterocyte apoptosis, and failed epithelial renewal that destabilize the epithelial surface before overt barrier leak or malabsorptive failure becomes clinically evident.
Downstream
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MLCK/Actomyosin-Mediated Tight Junction Remodeling
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Villus Blunting and Surface Loss
Show evidence (2 references)
"Chemotherapy kills fast-growing cells including gut stem cells. This affects all components of the physical and functional intestinal barrier, i.e., the mucus layer, epithelium, and immune system."
Review evidence shows that treatment-related intestinal injury begins with epithelial and stem-cell damage that perturbs the barrier as a whole, illustrating a generic trigger state for this module.
"Moreover, the underlying mechanisms are discussed, including apoptosis of intestinal epithelial cells, biology of intestinal stem cells, alterations in the apical junctional complex, transcytotic uptake of gluten peptides, and possible implications of a defective epithelial polarity."
Review of celiac disease identifies epithelial apoptosis and stem-cell/junctional perturbation as core injury mechanisms that generalize beyond celiac disease.
Paracellular Barrier Leak
amplifier
Junctional remodeling and tight-junction protein loss reduce epithelial resistance and increase paracellular permeability. The result is a leak-prone surface that permits flux of solutes and luminal contents across the epithelial barrier and can directly contribute to leak-flux diarrhea.
Downstream
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Luminal Access and Inflammatory Amplification
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Diarrhea
Show evidence (2 references)
"Transepithelial resistance was found to be decreased only in IECs that had been exposed to celiac monocytes."
Human coculture data directly demonstrate reduced epithelial barrier resistance under disease-relevant inflammatory conditions.
"Barrier dysfunction as a result of epithelial tight junction changes plays a role in IBS-D as a pathomechanism inducing a leak flux type of diarrhea."
Human biopsy-based data establish a direct link between tight-junction perturbation, paracellular leak, and leak-flux diarrhea.
Luminal Access and Inflammatory Amplification
amplifier
Increased permeability permits microbial products, dietary antigens, toxins, and other luminal contents to access the mucosa more readily. This amplifies local cytokine responses and sustains the inflammatory state, reinforcing epithelial damage and creating a self-perpetuating barrier-failure loop.
Downstream
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Absorptive Failure and Transport Dysregulation
Show evidence (2 references)
"This results in an altered intestinal permeability of toxic compounds (e.g., endotoxins) as well as luminal bacterial translocation into the mucosa and central circulation."
Supports the transition from barrier leak to mucosal exposure and inflammatory amplification.
"The pathogenesis of IBD-associated diarrhea is multifactorial and is essentially an outcome of mucosal damage caused by persistent inflammation resulting in dysregulated intestinal ion transport, impaired epithelial barrier function and increased accessibility of the pathogens to the intestinal mucosa."
Broad IBD review ties persistent inflammation, barrier impairment, and enhanced pathogen access into a single pathogenic loop.
Villus Blunting and Surface Loss
effector
Enterocyte apoptosis and impaired epithelial renewal shorten villi, reduce epithelial surface area, and diminish the absorptive interface available for nutrient and fluid uptake.
Downstream
-
Absorptive Failure and Transport Dysregulation
Show evidence (2 references)
"In celiac disease (CD) a T-cell-mediated response to gluten is mounted in genetically predisposed individuals, resulting in a malabsorptive enteropathy histologically highlighted by villous atrophy and crypt hyperplasia."
Representative disease evidence shows that villous loss and crypt injury reduce the absorptive epithelial surface.
"Continuous administration of 5-FU to mice caused severe intestinal mucositis, which was histologically characterized by the shortening of villi and destruction of intestinal crypts, accompanied by body weight loss and diarrhoea."
Experimental mucositis shows that villus shortening and crypt destruction accompany diarrheal intestinal injury.
Absorptive Failure and Transport Dysregulation
effector
Reduced absorptive surface area together with inflammatory reprogramming of epithelial transport lowers effective fluid and electrolyte absorption. In parallel, altered transporter activity promotes water retention within the intestinal lumen, coupling malabsorptive failure to diarrheal output.
Show evidence (2 references)
"However, in conditions of secretory diarrhea, this balance becomes dysregulated, so that fluid secretion, driven primarily by Cl- secretion, overwhelms absorptive capacity, leading to increased loss of water in the stool."
Review evidence directly frames diarrhea as a state in which absorptive capacity is no longer sufficient to conserve intestinal fluid.
"Altered expression and/or function of epithelial ion transporters and channels is the principle cause of electrolyte retention and water accumulation in the intestinal lumen leading to diarrhea in IBD."
Directly connects transport dysfunction to luminal fluid accumulation and diarrheal physiology.
Diarrhea
consequence
The combined effects of paracellular leak, inflammatory exudation, and reduced absorptive capacity increase stool water content and frequency. The phenotype may be driven predominantly by leak-flux or malabsorptive mechanisms, but the convergent outcome is diarrheal fluid loss.
Show evidence (2 references)
"Barrier dysfunction as a result of epithelial tight junction changes plays a role in IBS-D as a pathomechanism inducing a leak flux type of diarrhea."
Provides direct human evidence that barrier dysfunction can itself define a diarrheal mechanism.
"Aberrant barrier function further contributes to diarrhea via leak-flux mechanism."
Concise review statement linking barrier failure to the downstream diarrheal phenotype.