Montmorillonite loaded with zinc oxide alleviates colonic inflammation in mice by modifying gut microbiota and their metabolites

Inflammatory bowel disease (IBD) is a condition of complex pathogenesis, increasingly characterized by gut microbiota dysbiosis and associated metabolic disturbances. This study investigated the alleviative potential and mechanism of a montmorillonite loaded with zinc oxide composite (ZnO-MMT) in a dextran sulfate sodium (DSS) induced murine model of colitis. Our results demonstrated that low- and medium-dose ZnO-MMT (L-ZnO-MMT and M-ZnO-MMT) were superior to free montmorillonite alone in alleviating colonic inflammation, as evidenced by significantly reduced disease activity index scores, mitigated colonic tissue damage, suppressed production of pro-inflammatory cytokines ( TNF-α , IL-6 , IL-1β ), and enhanced expression of tight junction proteins (ZO-1, Occludin and Claudin-1). 16S rDNA sequencing further revealed that L-ZnO-MMT robustly restored gut microbial homeostasis, characterized by an increased Bacillota/Bacteroidota (F/B) ratio, promoted growth of beneficial genera such as Bacteroides and Ligilactobacillus , and inhibited pathogenic taxa including Escherichia-Shigella , Enterococcus , Romboutsia , Parabacteroides , and Turicimonas . Furthermore, non-targeted metabolomics analysis of colon contents identified significant shifts in the metabolic landscape, with L-ZnO-MMT notably increasing the levels of key microbially derived metabolites, including kynurenic acid, indole-3-acetaldehyde, 4-(2-Aminophenyl)-2.4-dioxobutanoic acid, cholic acid, and chenodeoxycholic acid. These metabolites are known to contribute to intestinal barrier integrity and immune regulation. Correlation analysis established a strong link between the specific microbiota alterations and the observed metabolic changes, suggesting a microbiota-metabolite regulatory axis. In conclusion, our findings demonstrate that the montmorillonite-based delivery of zinc oxide effectively ameliorates experimental colitis by reshaping the gut microbiota and modulating microbial metabolite profiles, positioning ZnO-MMT as a promising novel nano-agent for IBD intervention.