Chinese Yam Polysaccharide Alleviates DSS-Induced Ulcerative Colitis After Antibiotic Pretreatment

This study investigated whether the therapeutic efficacy of Chinese yam polysaccharide (CYP) against ulcerative colitis (UC) depends on an intact gut microbiota. A dextran sulfate sodium (DSS)-induced colitis mouse model was established, and one treatment group received broad-spectrum antibiotics (ABXs) before CYP administration to deplete the intestinal microbiota. CYP markedly attenuated colonic injury, reduced disease activity, and suppressed inflammatory mediators under both microbiota-intact and microbiota-depleted conditions. CYP also enhanced intestinal barrier integrity, as evidenced by reduced serum endotoxin levels and increased expression of MUC-2, Claudin-1, Occludin, and ZO-1. In addition, CYP improved hepatic antioxidant status by increasing GSH-Px and catalase activities and decreasing malondialdehyde levels. Moreover, CYP reduced the activation of the NF-κB and MAPK signaling pathways, with similar trends observed under microbiota-depleted conditions. Microbiota profiling showed that CYP partially corrected DSS-induced dysbiosis, whereas the ABX + CYP group exhibited distinct microbial patterns with enrichment of carbohydrate-related metabolic pathways predicted by PICRUSt2. Collectively, these findings suggest that CYP retains protective efficacy after antibiotic pretreatment, indicating that its effects may not be exclusively dependent on gut microbiota modulation, possibly involving direct actions on immune and intestinal epithelial cells.