Berberine inhibits dendritic cells differentiation in DSS-induced colitis by promoting Bacteroides fragilis

Berberine (BBR), a compound long used in traditional Chinese medicine, has been reported to have therapeutic effects in treating ulcerative colitis (UC), attributed to its anti-inflammatory properties and restorative potential of tight junctions (TJs). However, the mechanism by which BBR affects intestinal bacteria and immunity is still unclear.This study investigated the effects of BBR on intestinal bacteria and the inflammatory response in dextran sulfate sodium (DSS)-induced colitis mice. Immunohistochemistry (IHC) and electron microscopy were used to detect intestinal TJs. Microflora analysis was used to screen for bacteria regulated by BBR.The results showed that BBR had increased colonic epithelium zonula occludens proteins-1 (ZO-1) and occludin expression and reduced T-helper 17/T regulatory ratio in DSS-induced mice. Mechanically, BBR eliminated DSS-induced intestinal flora disturbances in mice, particularly increased Bacteroides fragilis (B. fragilis) in vivo and in vitro. B. fragilis decreased the interleukin-6 induced by dendritic cells through some heat-resistant component rather than nucleic acids or proteins.Overall, these data suggest that BBR had a moderating effect on DSS-induced colitis. This compound may regulate intestinal immune cell differentiation by affecting the growth of B. fragilis, providing new insights into the potential application of BBR in UC.