The Relationship between Fusicatenibacter saccharivorans and Inflammatory Bowel Disease.

Recent studies indicate association between inflammatory bowel disease (IBD) and intestinal microbiota, and some specific bacteria prevent colitis of animal IBD models. In this study, we analyzed the bacterial composition of fecal samples from patients with ulcerative colitis (UC), Crohn's disease (CD), and healthy subjects by 16S rRNA gene sequence. The number of the total fecal bacteria in active UC was less than quiescent UC. The alteration of bacterial number was not observed in CD. Furthermore, we found that the prevalence of Fusicatenibacter saccharivorans (FS), which belong to clostrdium cluster XIVa, was lower in active UC than quiescent UC. Surprisingly, administration of FS derived from human healthy subject improved colitis in IBD mode mice. To explore the mechanism, we stimulated colitc lamina propria mononuclear cells (LPMC) from IBD model mice with heat-killed FS. LPMC incubated with FS produced higher amounts of IL-10 compared to those stimulated with Enterococcus faecalis (EF), which was used as a control of gram-positive bacteria. FS also induced IL-10 production from LPMC isolated from UC patients. The results suggest FS suppress intestinal inflammation, probably through IL-10 induction. Therefore FS can be a future strategy of IBD therapy.