Exopolysaccharide from Bifidobacterium breve alleviate dextran sulfate sodium-induced colitis in mice via inhibiting oxidative stress and regulating intestinal flora

Exopolysaccharides are believed to alleviate colitis by maintaining intestinal homeostasis, but its specific action mechanism is worth exploring. Here, a type of exopolysaccharide (BBE) from Bifidobacterium breve composed with mannose, rhamnose, glucose, acetylglucosamine and galactose was isolated, along with sulfate groups and a steric helical structure. The protective effect and anti-inflammatory activity of BBE on intestine were evaluated in vitro and in vivo. Cell experiments indicated that BBE significantly increased the survival ability of intestinal epithelioid cell line 6 under action of hydrogen peroxide. Vivo experiments revealed that BBE restored the intestinal injury caused by dextran sulfate sodium (DSS) in mice by increasing the contents of mucin and the expression of occludin, claudin-1, ZO-1. BBE administration significantly inhibited the expression of oxidative protein and pyrin domain 3 inflammasome complex in colitis mice. The intervention of BBE also restored the production of abnormal inflammatory factors and the decrease of short-chain fatty acids (SCFAs) level caused by DSS. Besides, BBE also recovered the imbalanced intestinal flora by increasing the abundance of Muribaculaceae, and Lactobacillus as well as reducing the abundance of Escherichia-Shigella and Bacteroides. The aforementioned results confirmed that BBE could effectively repair intestinal damage, thereby laying a foundation for the application of BBE as a potential anti-inflammatory substance.