Preventive Effect of Peptidoglycan Extracted from Lactobacillus casei ATCC 393 on Dextran Sulfate Sodium-Induced Inflammation in Mice Through Gut Microbiota Regulation

Peptidoglycan (PG) is a polymer that makes up the cell wall of most bacteria. In this study, the peptidoglycan of Lactobacillus casei ATCC 393 was extracted, and its prebiotic function as well as its effects on intestinal health and inflammation reduction in a colitis murine model were investigated. PG was extracted from L. casei ATCC 393 using the ultrasonic-assisted enzymatic method. A structural characterization and assessment of its antioxidant capacity were subsequently performed to evaluate its functional properties. In a dextran sulfate sodium (DSS)-induced colitis model, dietary supplementation with PG (100 mg/kg) demonstrated significant protective effects. Specifically, the PG intervention group exhibited reduced inflammatory symptoms, improved disease activity indices, suppressed weight loss, and colon shortening compared to the DSS-induced group. Intestinal barrier injury was reversed and the Firmicutes/Bacteroidetes ratio was increased. These clinical improvements were accompanied by decreased circulating levels of pro-inflammatory cytokines (IL-6, TNF-α, and IL-1β). These findings revealed that PG modulated gut microbial ecology by enhancing bacterial diversity and promoting the enrichment of beneficial taxa, particularly the Lachnospiraceae and Lactobacillus species. Additionally, PG intervention increased fecal short-chain fatty acid (SCFA) concentrations, especially the concentration of propionic acid and butyric acid, which increased by 13% and 42%, respectively, compared to the DSS-induced group, suggesting enhanced microbial metabolic activity. Furthermore, these findings emphasize the potential of peptidoglycan as a functional component for preventing colitis through microbial-mediated pathways. This study underscores the prebiotic promise of peptidoglycan in the development of interventions targeting intestinal inflammation and supports its further exploration as a functional agent for promoting human health.