Pediococcus pentosaceus DF29-derived extracellular vesicles ameliorate EPEC-induced intestinal injury via M2 macrophage polarization.

Enteropathogenic Escherichia coli (EPEC) infection remains a major cause of intestinal barrier dysfunction and diarrhea, necessitating the development of novel non-antibiotic therapies. While Pediococcus pentosaceus (P. pentosaceus) exhibits probiotic potential, the specific role of its postbiotic components, particularly extracellular vesicles (EVs), in host-pathogen interactions remains obscure. In this study, we systematically evaluated the protective efficacy and underlying mechanisms of P. pentosaceus DF29 (DF29) and its derived EVs (PpEVs) against EPEC-induced enteritis. Characterization revealed that PpEVs isolated via ultracentrifugation exhibited a typical vesicular morphology, high purity, and robust stability under simulated gastrointestinal conditions. In vitro, PpEVs were efficiently internalized by macrophages and significantly blunted EPEC-induced pro-inflammatory responses. In vivo, oral administration of PpEVs recapitulated the protective effects of live DF29, including alleviating body weight loss, reducing disease activity index, and restoring histological integrity. Crucially, PpEVs reinforced the intestinal barrier by upregulating tight junction proteins, mitigating oxidative stress, and rebalancing the dysbiotic gut microbiota. Mechanistically, we demonstrated that PpEVs exerted their anti-inflammatory effects by inhibiting the TLR4/MyD88/NF-κB signaling axis, thereby shifting macrophage polarization from an M1 proinflammatory to an M2 anti-inflammatory phenotype and rectifying the Th1/Th2 and Th17/Treg imbalances. Collectively, our findings suggest that PpEVs represent a potential intervention strategy to preserve intestinal homeostasis and counteract EPEC-associated inflammation.