Ulcerative colitis (UC) has become a global epidemic, and the lack of an effective cure highlights the necessity and urgency to explore novel therapies. Sijunzi Decoction (SJZD), a classical Chinese herbal formula, has been comprehensively applied and clinically proven effective in treating UC; however, the pharmacological mechanism behind its therapeutic benefits is largely obscure. Here, we find that SJZD can restore microbiota homeostasis and intestinal barrier integrity in DSS-induced colitis. SJZD significantly alleviated the colonic tissue damage and improved the goblet cell count, MUC2 secretion, and tight junction protein expressions, which indicated enhanced intestinal barrier integrity. SJZD remarkedly suppressed the abundance of phylum Proteobacteria and genus Escherichia-Shigella, which are typical features of microbial dysbiosis. Escherichia-Shigella was negatively correlated with body weight and colon length, and positively correlated with disease activity index and IL-1[Formula: see text]. Furthermore, through gut microbiota depletion, we confirmed that SJZD exerted anti-inflammatory activities in a gut microbiota-dependent manner, and fecal microbiota transplantation (FMT) validated the mediating role of gut microbiota in the SJZD treatment of UC. Through gut microbiota, SJZD modulates the biosynthesis of bile acids (BAs), especially tauroursodeoxycholic acid (TUDCA), which has been identified as the signature BA during SJZD treatment. Cumulatively, our findings disclose that SJZD attenuates UC via orchestrating gut homeostasis in microbial modulation and intestinal barrier integrity, thus offering a promising alternative approach to the clinical management of UC.
Keywords: Bile Acid; Gut Microbiota; Inflammation; Intestinal Barrier; Sijunzi Decoction; Ulcerative Colitis.