Effects of Vitamin D3 on Intestinal Flora in a Mouse Model of Inflammatory Bowel Disease Treated with Rifaximin.

BACKGROUND Rifaximin is an antimicrobial agent used to treat inflammatory bowel disease (IBD). Vitamin D3 can control IBD due to its effects on inflammatory cytokines. The purpose of this study was to assess the effect of vitamin D3 on the intestinal flora of a dextran sulfate sodium (DSS)-induced mouse model treated with rifaximin. MATERIAL AND METHODS The mouse model of IBD was developed using DSS (4%) administered via the drinking water. Twenty-four male C57BL6 mice were divided into the control group with a normal diet (N=6), the DSS group with a normal diet (N=6), the DSS group with a normal diet treated with rifaximin (N=6), and the DSS group with a normal diet treated with rifaximin and vitamin D3 (N=6). After 14 days, the colonic tissue was studied histologically. Serum levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1s (IL-1s) and enzyme-linked immunosorbent assay (ELISA) were used to measure the level of IL-6 and P65, and phospho-p65 was measured by western blot. 16S rRNA gene sequencing was used to analyze fecal samples. RESULTS In the DSS mouse model of IBD, rifaximin reduced the inflammation severity of the colon and reduced the expression of phospho-p65, p65, TNF-alpha, and IL-6. In the DSS+rifaximin+vitamin D3 group, the therapeutic influences of rifaximin, in terms of weight loss and colonic disease activity, were significantly reduced, and the gut microbiota of the mice were completely changed in composition and diversity. CONCLUSIONS In a mouse model of IBD, treatment with vitamin D3 significantly increased the metabolism of rifaximin and reduced its therapeutic effects.