Loss of Claudin-3 Impairs Intestinal Barrier Function and Gut Microbiota to Promote Colitis

Objective: Inflammatory Bowel Disease (IBD) is multifactorial autoimmune disorder where dysregulation of the gut barrier and gut microbiota (Dysbiosis) play critical role in disease onset and progression. A leaky gut often coexists with the dysbiotic gut microbiota, however a pathobiological integration is not well understood. Intestinal claudin-3 expression is robust, and we have reported that its loss promotes gut permeability and colon cancer. Increased gut permeability and colon cancer risk characterize Inflammatory Bowel Disease (IBD). The current study was undertaken to delineate the status and role of claudin-3 expression in IBD. Methods: Multiple murine models of colitis and IBD patient biopsy were used. Claudin-3KO mice were used to determine causal role. Multiplex ELISA, RNAseq and 16S DNA sequencing helped determine inflammatory cytokines, transcriptomic changes, and gut microbiota diversity, respectively. Fecal microbiota transplantation (FMT) and antibiotic treatment studies were done to test the role of claudin-3/gut dysbiosis axis in promoting IBD. Results: A significant decrease in claudin-3 expression was observed in IBD patient samples or the colon of mice subjected to DSS- (2.5% w/v) or C. rodentium-colitis (5 x108 CFU/oral). colitis (p<0.001). To test the causal role, claudin-3KO mice were subjected to DSS-colitis (acute and chronic), and infectious colitis. A significant change in the body weight, colon thickness, and mucosal injury score (p<0.001) characterized the colitis challenged claudin-3KO versus WT mice. P-Stat3 expression was highly upregulated in colitis challenged claudin-3KO mice. Interestingly, administration of an antibiotic cocktail rescued the colitis severity in claudin-3KO mice. The 16s metagenomics further revealed that the gut microbiota of claudin-3KO mice is diverse and clustered distinctly from the WT mice. To determine if gut dysbiosis in claudin-3KO mice promotes susceptibility to colitis, we performed FMT from naïve Claudin-3KO mice to germ-free WT mice. When subjected to DSS-colitis, germ-free mice transplanted with Claudin3-KO gut microbiota showed significantly higher colitis severity versus WT (p<0.05). Conclusion: We summarize that the loss of colonic Cldn3 deregulates mucosal barrier integrity to induce gut dysbiosis and susceptibility to IBD. We propose that claudin-3 can be a novel therapeutic target in strengthening the gut barrier integrity to diminish IBD susceptibility. National Institute of Health, Veterans Administration This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.