Inflammatory bowel disease (IBD) is a chronic relapsing colitis, associated with risk for obstruction, fistula and colorectal cancer. It is probaly caused by immunologically dysregulated host and microbial interactions. Effective anti-inflammatory medications are associated with toxicities, so new treatment strategies for IBD are needed. Dietary glucosamine, widely used for arthritis, cardiovascular disease, and cancer prevention, is suggested as a therapy for IBD. We and others have shown that colonic inflammation in mice is suppressed by oral administration of chitin, a natural glucosamine polymer derivative. The efficacy depends on the specific form of chitin, available as soluble chitin, chitin microparticles at 1 - 10 ?m (CMPs), large chitin beads at 40 - 100 ?m (LCBs), chitosan microparticles at 1 - 10 ?m (CsMPs) and soluble chitosan. We propose to determine which chitin preparation is the most effective in suppressing colitis activities. Oral chitin may induce responses by intestinal epithelial cells and/or colonic macrophages through their chitin binding proteins (CBPs), including toll-like receptor 2 (TLR2) and CD44. These two CBPs are reasonable targets for chitin treatment since they are known to be anti- and pro-inflammatory in mouse colitis, and seem to functionally down-regulate each other. Based on our preliminary results, we hypothesize that chitin preparations optimal for anti-colitis effects will up-regulate TLR2 and down-regulate CD44 activities, and protect intestinal epithelia. To test the hypothesis, we will determine the chitin form(s) that ameliorate colitis in mice infected with Citrobacter rodentium as a model of human IBD caused by enteropathogenic Escherichia coli. We will measure TLR2 and CD44 levels in the colon epithelial cells and colon macrophages to assess whether these CBP activities are associated with a shift in normal gut microbiota. Next, using mice deficient of TLR2 and CD44, we will determine whether TLR2 and CD44 are responsible for amelioration of colitis by the optimal chitin form selected above. The knowledge gained from this work will apply to the establishment of defined anti-colitis therapeutic protocol translating o clinical studies of IBD and possibly extended to other diseases where CBPs have been predicted to play key inflammatory roles. Furthermore, it will engage graduate and undergraduate students in clinically-relevant immunology research, encouraging their scientific development and giving them a deeper appreciation of complementary and alternative medicines.
This research project will examine oral administration of natural chitin as a possible efficacious therapy to regulate host and microbial interactions in inflammatory bowel disease and determine the role of specific chitin binding receptors in establishing anti-colitis responses to chitin treatment. We hypothesize that effective chitin preparations activate colon cells in a manner that increases anti- inflammatory toll-like receptor 2 and decreases pro-inflammatory CD44 activities.