Cytokine tumor necrosis factor alpha induces intestinal epithelial barrier dysfunction

Area of Science:

• Gastroenterology
• Immunology
• Cell Biology

Background:

• Epithelial barrier dysfunction is implicated in various diseases.
• The precise mechanisms underlying barrier dysfunction require further elucidation.
• Microbial products are potential triggers for intestinal epithelial damage.

Purpose of the Study:

• To investigate the role of flagellin (FGN), a microbial product, in inducing intestinal epithelial barrier dysfunction.
• To examine the expression of toll-like receptor 5 (TLR5) in inflammatory bowel disease (IBD) patients.
• To assess the involvement of tumor necrosis factor alpha (TNFα) in FGN-induced barrier compromise.

Main Methods:

• Colon epithelium specimens were collected from patients with ulcerative colitis (UC), Crohn's disease (CD), and healthy volunteers.
• Toll-like receptor 5 (TLR5) expression was quantified using RT-PCR and western blotting.
• A cell culture model using T84 intestinal epithelial cells was employed to study FGN and TNFα effects.

Main Results:

• TLR5 expression was detected in healthy colon epithelium, with significantly increased levels in UC and CD patients.
• Exposure of T84 cells to FGN elevated TNFα expression, leading to apoptosis and compromised monolayer barrier function.
• Inhibition of TNFα via gene knockdown prevented FGN-induced barrier dysfunction and apoptosis.

Conclusions:

• Human colon epithelial cells express TLR5, with elevated levels observed in CD and UC patients.
• Flagellin exposure enhances TNFα production, which critically impairs intestinal epithelial barrier integrity.
• Targeting the FGN-TLR5-TNFα pathway may offer therapeutic strategies for IBD-related barrier defects.