Coptidis Rhizoma processed with Evodia Rutaecarpa improves the effect on ulcerative colitis by increasing intestinal energy metabolites alpha-ketoglutarate and Lactobacillus reuteri.

BACKGROUND: Evodia Rutaecarpa-processed Coptidis Rhizoma (ECR) is a traditional Chinese medicine for the treatment of ulcerative colitis (UC) in China. However, the mechanisms underlying the ECR processing are not elucidated. PURPOSE: Coptidis Rhizoma (CR) regulates the gut microbiota in the treatment of gastrointestinal diseases. This study explored the mechanism of action of ECR before and after processing in UC in view of the regulation of gut microecology. STUDY DESIGN: A preclinical experimental investigation was performed using a mouse model of UC to examine the regulatory effect of ECR and its mechanisms through gut microbiota analysis and metabolomic assays. METHODS: Mice received 4% dextran sulfate sodium to establish a UC model and treated with ECR and CR. Colonic histopathology and inflammatory changes were observed. Gut microbiota was analyzed using 16 s rRNA sequencing. Transplants of Lactobacillus reuteri were used to explore the correlation between ECR processing and the gut microbiota. The expression of mucin-2, Lgr5, and PCNA in colonic epithelial cells was measured using immunofluorescence. Wnt3a and ß-catenin levels were detected by western blotting. The metabolites in the colon tissue were analyzed using a targeted energy metabolomic assay. The effect of energy metabolite α-ketoglutarate (α-KG) on L. reuteri growth and UC were verified in mice. RESULTS: ECR improved the effects on UC in mice compared to CR, including alleviating colonic injury and inflammation, and modulating gut microbiota by increasing L. reuteri level. L. reuteri dose-dependently alleviated colonic injury, increased mucin-2 level, and promoted colonic epithelial regeneration by increasing Lgr5 and PCNA expression. This was consistent with the results before and after ECR processing. L. reuteri promoted epithelial regeneration by upregulating Wnt/ß-catenin pathway. Moreover, ECR increased metabolites levels (especially α-KG) to promote energy metabolism in the colon tissue compared to CR. α-KG treatment increased L. reuteri level and alleviated mucosal damage in UC mice. It promoted L. reuteri growth by increasing the energy metabolic status by enhancing α-KG dehydrogenase activity. CONCLUSION: ECR processing improves the therapeutic effects of UC via the α-KG-L. reuteri-epithelial regeneration axis.

Xianglian pill modulates gut microbial production of succinate and induces regulatory T cells to alleviate ulcerative colitis in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Xianglian pill (XLP), a traditional Chinese formula, is widely used as treatment for ulcerative colitis (UC) in China. However, the mechanism of its therapeutic effect is still unclear. AIM OF THE STUDY: Our previous studies showed a low oral bioavailability and a predominant distribution of major XLP ingredients in the gut. In the present study, we aimed to explore the mechanism of action of XLP on UC with respect to the regulation of gut microecology. MATERIALS AND METHODS: UC model rats established using 5% dextran sulfate sodium were treated with XLP. After the treatment period, bodyweight, colon length, histopathology, and inflammatory changes were evaluated. Further, changes in gut microbiota structure were detected via 16S rRNA sequencing, and microbial metabolites in feces were analyzed via a metabolomic assay. Antibiotic intervention and fecal microbiota transplantation were also employed to explore the involvement of gut microbiota, while the level of regulatory T cells (Tregs) in mesenteric lymph nodes was determined via flow cytometry. Transcriptome sequencing was also performed to determine colonic gene changes. RESULTS: XLP alleviated colonic injury, inflammation, and gut microbial dysbiosis in UC model rats and also changed microbial metabolite levels. Particularly, it significantly decreased succinate level in the tyrosine pathway. We also observed that fecal microbiota derived from XLP-treated rats conferred resilience to UC model rats. However, this therapeutic effect of XLP on UC was inhibited by succinate. Moreover, XLP increased the level of anti-inflammatory cellular Tregs via gut microbiota. However, this beneficial effect was counteracted by succinate supplementation. Further, XLP induced the differentiation of Treg possibly by the regulation of the PHD2/HIF-1α pathway via decreasing microbial succinate production. CONCLUSIONS: Our findings indicated that XLP exerts its therapeutic effects on UC mainly via the gut microbiota-succinate-Treg differentiation axis.