Pulsatilla decoction improves DSS-induced colitis via modulation of fecal-bacteria-related short-chain fatty acids and intestinal barrier integrity

Pulsatilla decoction (PD), is an herbal formula commonly used for the treatment of ulcerative colitis (UC) in clinical practice, but the mechanism of PD alters the colitis remains elusive.To evaluate the intervention effect of PD on Dextran Sodium Sulfate (DSS)-induced UC based on gut microbiota and intestinal short-chain fatty acid (SCFAs) metabolism, and to investigate the mechanism of action of PD in treating UC.A 3% (wt/vol) DSS-induced ulcerative colitis model in C57BL/6 male mice was used to evaluate the effect of oral PD in treating UC. The changes in gut microbiota in mice were analyzed by 16SrDNA gene sequencing, and the content of SCFAs in the intestinal contents of mice was determined by gas chromatography-mass spectrometry (GC-MS). Enzyme-linked immunosorbent assay (ELISA) was applied to analyze the expression of inflammatory cytokines in serum and colonic tissues, and western blotting (WB) was applied to analyze the expression of tight junction proteins in colonic tissues.PD can alleviate the symptoms of UC mice, Pulsatilla Decoction high dose treatment group (PDHT) shows the best effect. Compared with the DSS group, the PDHT had significantly lower body mass, disease activity index (DAI) score, colonic macroscopic damage index (CMDI) score, and pathological damage score, at the phylum level, the relative abundance of Bacteroidetes increased while that of Firmicutes and Proteobacteria decreased, at the Genus level, the abundance of Bacteroides and Lachnospiraceae.NK4A136.group increased while that of Clostridium. sensu.stricto。, Escherichia. shigella and Turicibacter decreased. Compared with the DSS group, acetate, propionate, and total SCFAs in the PDHT with significantly higher levels. The concentrations of interleukin-1β (L-1β), tumor necrosis factor-alpha (TNF-α), and interleukin-17 (IL-17) decreased whereby the concentration of interleukin-10 (IL-10) increased in the PDHT group. The expression levels of Occludin, zonula occludens-1 (ZO-1), Claudin1, Claudin5, G protein-coupled receptor43 (GPR43) protein, and the relative expression of ZO-1 and Occludin mRNA were significantly increased PDHT group.PD has a good therapeutic effect on UC mice. The pharmacological mechanism is probably maintaining the homeostasis and diversity of gut microbiota, increasing the content of SCFAs, and repairing the colonic mucosal barrier.