OBJECTIVE  To investigate the regulatory effects of Wumei Wan(WMW) on the expression of inflammatory factors and gut microflora in mice with dextran sodium sulfate(DSS)-induced ulcerative colitis(UC) model.

METHODS Forty C57BL/6J mice were randomly divided into control group, model group, mesalazine(5-ASA) group, Wumei Wan low-dose(WMW-L) group, and Wumei Wan high-dose(WMW-H) group, with 8 mice in each group. The UC model was induced in mice by freely drinking 2% DSS solution, and at the same time, the treatment group received daily oral administration, while the control group and model group received an equal volume of normal saline, over 7 days. The general conditions of mice, body weight, blood in stool, and fecal traits were recorded, then the disease activity index(DAI) score was calculated. After the above experiments, the mice were sacrificed. The serum levels of interleukin(IL)-6, IL-10, and tumor necrosis factor(TNF)-α were detected by ELISA. The intact colon were collected to observe the damage of colonic mucosa, and to observe the pathological injury of colon by HE staining. Alcian blue-periodic acid-Schiff(AB-Pas) staining was performed to observe goblet cells. The mRNA expression of IL-6, IL-10, TNF-α in colon was detected by Real-time PCR. HE staining was performed to observe pathological injury of liver and kidney. The protein expression of P65, p-P65 was detected by Western blotting. The differences in intestinal flora among the groups were analyzed using 16S rRNA sequencing technology.

RESULTS Compared with the control group, the mice in the model group showed hematochezia, weight loss, colon shortening, and obvious damage to the colon surface. Significant inflammatory cell infiltration and goblet cell loss in histopathologic staining of the colon, significantly elevated colon mucosa damage index(CMDI), histological score(HS) scores, elevated levels of TNF-α, IL-6, and decreased IL-10. The phosphorylation level of P65 protein was significantly increased. The abundance of intestinal flora in mice was decreased, and the composition of intestinal flora was changed. Compared with model group, WMW delayed weight loss in mice, alleviated blood in stool, decreased DAI scores, inhibited colon shortening, alleviated colon surface injury, reduced goblet cell loss, and significantly decreased CMDI and HS scores. The levels of IL-6 and TNF-α in serum and colon tissue were significantly decreased, and the phosphorylation of P65 in colon tissue was significantly inhibited. In addition, the expression of IL-10 in serum and colon tissue of UC mice in WMW-H group was increased. There was no liver and kidney injury in any group. At the phylum level, the abundance of Firmicutes and Actinobacteria decreased, Proteobacteria and Bacteroidetes increased. At the genus level, the abundance of Clostridium decreased and that of Muribaculacea increased.

CONCLUSION Wumei Wan can alleviate colonic inflammation in DSS-induced UC mice. And its mechanism of action is related to regulating the expression of inflammatory factors and the composition of intestinal flora.