Baitouweng Tang ameliorates DSS-induced ulcerative colitis through the regulation of the gut microbiota and bile acids via pathways involving FXR and TGR5.

Abstract In China, Baitouweng Tang (BTWT) is a commonly prescribed remedy for the treatment of ulcerative colitis (UC). Herein, the present study aims to assess the anti-colitis activity of BTWT and its underlying mechanisms in UC BALB/c mice. Induction of UC in BALB/c mice was carried out by adding 3.5% DSS in the drinking water of underlined mice. After UC induction, the mice were administrated with BTWT for 7 days. Clinical symptoms were assessed, followed by analyzing the bile acids (BAs) in serum, liver, colon, bile, and feces of UC mice through UPLC-MS/MS. The modified 16S rDNA high-throughput sequencing was carried out to examine the gut microbiota of feces. BTWT significantly improved the clinical symptoms such as and histological injury and colon shortening in UC induced mice. Furthermore, BTWT remarkably ameliorated colonic inflammatory response. After BTWT treatment, the increased concentrations of UDCA, HDCA, αMCA, βMCA, CA, and GLCA in UC were decreased, and the levels of some BAs, especially CA, αMCA, and βMCA were normalized. Moreover, the relative species abundance and gut microbiota diversity in the BTWT-exposed groups were found to be considerably elevated than those in the DSS-treated group. BTWT increased the relative abundance of Firmicutes, Proteobacteria, Actinobacteria, Tenericutes, and TM7, which were statistically lower in the fecal microbiota of UC mice. The relative abundance of Bacteroidetes was found to be elevated in the DSS group and normalized after BTWT treatment. BTWT increased the expression of FXR and TGR5 in the liver. BTWT administration improved DSS-induced mice signs by increasing the TGR5 and FXR expression levels. This result was achieved by the regulation of the BAs and gut microbiota.