Dose-response efficacy and mechanisms of orally administered CLA-producing Bifidobacterium breve CCFM683 on DSS-induced colitis in mice

This study designed to explore the dose-effect relationship of CCFM683 in relieving colitis and investigate the mechanisms involved. Specifically, the concentration of mucin2, goblet cells and tight junction proteins were significantly up-regulated by 1010 and 109 cfu/day CCFM683. Moreover, interleukin (IL)-1β and IL-6 were significantly down-regulated by 1010 and 109 cfu/day CCFM683. Furthermore, gut microbiota in mice treated with 1010 and 109 cfu/day CCFM683 were rebalanced via improving the unbalanced interaction, regulating the diversity, increasing Bifidobacterium and decreasing Bacteroides and Sutterella. Moreover, the colonic conjugated linoleic acid (CLA) concentration was significantly positive correlated with the effectiveness of the strain in relieving colitis. The gavage dose of CCFM683 should be more than 108.65 cfu/day in mice for improving colitis according to dose-effect curve. In conclusion, CCFM683 supplementation alleviated colitis in a dose-dependent manner by improving intestinal epithelial barriers, protecting the intestinal mucus layer, restoring gut microbiota, and down-regulating the inflammatory cytokines.