Exosomes from IL-33-Stimulated Macrophages Regulate Epithelial Barrier Function to Ameliorate TNBS-Induced Colitis in Mice.

Inflammatory bowel disease (IBD) represents a growing global health threat that markedly increases colorectal cancer risk, yet conventional immunosuppressive agents achieve mucosal healing in only a limited subset of patients. M2-polarized macrophages have been recognized as crucial regulators of mucosal repair through their ability to maintain intestinal microenvironment homeostasis. Here, we investigated the potential effects and mechanisms of macrophage-derived exosomes (Exos) on epithelial barrier function in a murine model of IBD. Murine colitis was induced by intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS), followed by treatment with Exos isolated from IL-33-treated macrophages (IL-33-Exos) or untreated macrophages (PBS-Exos). Our findings showed that IL-33-Exos markedly ameliorated inflammatory intestinal mucosal injury and improved intestinal barrier dysfunction. Concurrently, IL-33-Exos mitigated intestinal epithelial cell damage, thereby preserving intestinal mucosal integrity. Mechanistic studies revealed that the beneficial effects of IL-33-Exos were implicated in upregulation of Wnt/β-catenin signaling in intestinal epithelial cells. Translationally, these findings suggest that IL-33-Exos may promote epithelial repair in experimental colitis, offering a novel therapeutic avenue for clinical management of inflammatory bowel disease.