Characterizing the Host Immunologic Response to a Pouchitis-Associated Strain of\u3cem\u3e Bacteroides fragilis \u3c/em\u3e

Ulcerative colitis (UC) is an inflammatory bowel disease that affects the colonic mucosa. One of the treatments for UC is a surgical procedure that involves creating an ileal pouch from the large intestine that is called ileal pouch anal-anastomosis (IPAA). In some cases this ileal pouch becomes inflamed: a condition called pouchitis. Pouchitis is hypothesized to occur in genetically susceptible individuals from an abnormal immune response to mucosal microbiota. In a longitudinal study of pouch microbial communities from 22 IPAA patients, bacteria in the genus Bacteroides were found in greater abundance during episodes of pouchitis. We isolatedr Bacteoides fragilis from pouchitis patients and evaluated the contribution of these bacteria to development of colitis in two gnotobiotic mouse models, the IL10 knockout and dextran sodium sulfate (DSS) models. It was found that monoassociation with pouchitisassociated B. fragilis does not promote colitis in the IL10 gnotobiotic mouse in comparison to a reference strain of B. fragilis and that pouchitis-associated B. fragilis attenuates DSS colitis in the gnotobiotic mouse