Bear Bile Powder Improves Ulcerative Colitis by Protecting the Intestinal Mechanical Barrier and Regulating Intestinal Flora

Background: Bear Bile Powder (BBP) is a traditional Chinese medicine. It has been widely used in clinical practices and has shown a good anti-inflammatory effect. However, its effectiveness in treating Ulcerative Colitis (UC) has not yet been studied. Objective: To explore the therapeutic effect of BBP on ulcerative colitis and its potential mechanism by combining acute ulcerative colitis mouse models and comprehensively observing various physiological and biochemical indexes of mice. Methods: The acute ulcerative colitis model was induced by drinking water containing dextran sulfate sodium salt (DSS) for 7 days. Studies were divided into Control, DSS, DSS+ Sulfasalazine (SASP, 450 mg/kg), and DSS + bear bile powder group (BBP, 320 mg/kg). The Disease Activity Index (DAI) and colonic tissue damage of mice were evaluated. Tissue immunofluorescence and western blot were used to determine related tight Junction Proteins (TJs), and 16S V34 amplicon was used to analyze intestinal microorganisms. The therapeutic effect of BBP on ulcerative colitis model mice was studied comprehensively. Results: After treatment, BBP can significantly improve the physiological condition of acute UC mice and reduce DAI fraction. Compared with the DSS group, the BBP group significantly increased the colon length and significantly decreased the injury fraction of acute UC mice. Regarding the intestinal mechanical barrier, BBP significantly increased the expression of ZO-1, Occludin, and Claudin 1 protein in colon tissue. In terms of microbial community, the intestinal microbial diversity of mice decreased after the administration of BBP, but there was no significant difference in structural composition between the BBP group and the Control group. By comparing the four groups of species with significant differences, it was found that the BBP group significantly reduced the abundance of specific harmful microorganisms at the order, family, genus, and species levels. Conclusion: Oral administration of a certain dose of BBP can significantly improve the symptoms of ulcerative colitis in mice. Part of the reason may be that it increases the expression of tight junction proteins, regulates specific flora in the intestine of mice, and maintains intestinal barrier homeostasis. In the future, the clinical application value of BBP will be explored, and BBP will be developed as a drug with the potential to treat UC and alleviate the pain of UC patients other: not