Bacteroides vulgatus attenuates experimental mice colitis through modulating gut microbiota and immune responses

is one of the predominant species in the human gut and exerts a series of beneficial effects. The aim of this study was to investigate the protective role of Bv46 in a dextran sodium sulfate (DSS) induced colitis mouse model. Female C57BL/6J mice were given 3% DSS in drinking water to induce colitis and simultaneously treated with Bv46 by gavage for 7 days. Daily weight and disease activity index (DAI) of mice were recorded, and the colon length and histological changes were evaluated. The effects of Bv46 on gut microbiota composition, fecal short chain fatty acids (SCFAs) concentration, transcriptome of colon, colonic cytokine level and cytokine secretion of RAW 264 7 macrophage cell line activated by the lipopolysaccharide (LPS) were assessed. Bv46 significantly attenuated symptoms of DSS-induced colitis in mice, including reduced DAI, prevented colon shortening, and alleviated colon histopathological damage. Bv46 modified the gut microbiota community of colitis mice and observably increased the abundance of , , and at the genus level. In addition, Bv46 treatment decreased the expression of colonic TNF-α, IL-1β and IL-6 in DSS-induced mouse colitis , reduced the secretion of TNF-α, IL-1β and IL-6 in macrophages stimulated by LPS , and downregulated the expression of and genes in mice colon, which mainly participate in the regulation of B cell responses. Furthermore, oral administration of Bv46 notably increased the contents of fecal SCFAs, especially butyric acid and propionic acid, which may contribute to the anti-inflammatory effect of Bv46. Supplementation with Bv46 serves as a promising strategy for the prevention of colitis.