Protective Effects of Lacticaseibacillus paracasei 63 on DSS-Induced Colitis in Mice.

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon characterized by mucosal damage and immune dysregulation. This study aimed to evaluate the protective effects of Lacticaseibacillus paracasei 63 on ulcerative colitis. A dextran sulfate sodium (DSS)-induced male ICR mouse model of colitis was employed to assess the effects of oral administration of L. paracasei 63 on intestinal inflammation, barrier integrity, gut microbiota composition, short-chain fatty acid (SCFA) production, systemic inflammatory markers, and primary immune organ indices. Results showed that L. paracasei 63 significantly alleviated colitis and improved intestinal barrier function, accompanied by reduced TLR4 expression, decreased NF-κB p65 phosphorylation, and decreased MLCK-related markers. In addition, L. paracasei 63 administration modulated gut microbiota composition and increased SCFA levels, particularly acetate. These local intestinal changes were accompanied by reduced systemic inflammation, as evidenced by decreased serum IL-1β and TNF-α levels, along with an increased thymus index. Overall, L. paracasei 63 exerted significant ameliorative effects on DSS-induced ulcerative colitis, and these effects were associated with improvements in intestinal barrier integrity, inflammatory status, gut microbiota composition, SCFA production, and systemic immune-related indicators.