Silver Bullet for Inflammatory Bowel Disease?

Evidence has accumulated that inflammatory bowel disease (IBD) might result from subtle imbalances in the ratio of two groups of gut bacteria: commensal gut bugs that have pathogenic potential but are not normally pathogenic (pathobionts) and those that have protective effects (symbionts).

U.S. researchers induced IBD in mice, using two established techniques: rectal administration of a chemical that causes IBD or introduction of a pathobiont bacterium (plus CD4⁺ effector cells) into the gut. They then showed that introducing the human symbiont, Bacillus fragilis, into the gut at the same time as an IBD-causing agent prevented IBD. This protective effect was due to a single polysaccharide in the B. fragilis capsule that stimulated production…