A novel Sagittaria sagittifolia L. polysaccharides mitigate DSS-induced colitis via modulation of gut microbiota and MAPK/NF-κB signaling pathways

Sagittaria sagittifolia L. polysaccharides possess anti-inflammatory, antioxidant, and immune-modulatory properties. In this study, we identified a novel S. sagittifolia L. polysaccharide, named PSSP-1, and evaluated its potential in alleviating dextran sulfate sodium (DSS)-induced colitis in a mouse model. The results demonstrated that administration of PSSP-1 at doses of 100, 200, and 400 mg/kg·bw significantly reduced the disease activity index (DAI) and suppressed the expression of inflammatory cytokines in UC mice. Furthermore, PSSP-1 treatment upregulated the expression levels of claudin-1, occludin, and ZO-1, and promoted the diversity and abundance of beneficial gut microbiota, including Lactobacillus and Candidatus_Saccharimonas, while reducing the levels of Bacteroidetes and Verrucomicrobiota. Particularly, the Lactobacillus_johnsonii species may play a potentially significant role in modulating colitis. Subsequently, there was a significant increase in the levels of short-chain fatty acids (SCFAs). Additionally, the correlation analyses revealed positive associations between PSSP-1 supplementation and Nitrosospira and Dialister, which are implicated in gut inflammation. Mechanistically, PSSP-1 intervention inhibited the protein phosphorylation of key molecules in the MAPK and NF-κB signaling pathways. Collectively, these findings suggest that PSSP-1 mitigates colitis symptoms by repairing the intestinal barrier, promoting microbial metabolism, and regulating the gut microbiota-MAPK/NF-κB signaling pathways.