Abstract: Objective: This study aims to investigate the therapeutic effect of Lactobacillus rhamnosus GG-loaded lemon pectin microspheres (LGG@LPM) on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice. Methods: LGG@LPM was characterized, and the therapeutic potential of gavage administration of LGG@LPM against UC in mice was explored. Results: LGG@LPM microspheres exhibited good stability. The administration of LGG@LPM significantly alleviated the pathological process of DSS-induced UC in mice, restoring normal body mass and colon length and decreasing histological activity index (HAI) and disease activity index (DAI). Additionally, LGG@LPM administration reversed the increase in inflammatory cytokine levels and the decrease in antioxidant enzyme activities in the colon, the increase in serum lipopolysaccharide (LPS) levels and the alterations in short-chain fatty acids (SCFAs) levels induced by DSS in mice. 16S rRNA sequencing revealed that LGG@LPM restored the gut microbiota in UC mice through enhancing the abundance of Lactobacillus and Mucispirillum, and the alteration of the microbiota was significantly correlated with some environmental factors. Conclusion: LGG@LPM could alleviate the pathological progression of UC by improving the gut microbiota, the effect being more pronounced than that of either lemon pectin or LGG alone.

Key words: lemon pectin; Lactobacillus rhamnosus GG; ulcerative colitis; intestinal flora