Galactose-functionalized engineered outer membrane vesicles for targeted delivery of enterocin Gr17 ameliorate Salmonella Typhimurium-induced colitis.

Bacteriocins, antimicrobial peptides from lactic acid bacteria (LAB), represent promising agents against Salmonella Typhimurium-induced colitis. However, their proteinaceous nature leads to poor bioavailability and insufficient concentrations at infection sites, which significantly limits their application potential. Enterocin Gr17 exhibits potent antibacterial activity against S. typhimurium and effectively ameliorates pathogen-induced intestinal barrier damage. Herein, we innovatively developed a targeted oral delivery system termed OMV-Gr17/Gal, based on galactose (Gal)-modified engineered bacterial outer membrane vesicles (OMVs) that expressed and encapsulated enterocin Gr17 (14.2 kDa), with a yield of up to 159.2 μg per mg of OMVs protein, for effective alleviation of S. typhimurium-induced colitis. The lipid bilayer of OMVs protected enterocin Gr17 from gastrointestinal degradation, enhancing the antibacterial efficacy by over 3.4-fold. Moreover, galactose modification further enhanced its cellular uptake efficiency and enabled targeted delivery of enterocin Gr17 to intestinal inflammatory macrophages, thereby exerting superior antioxidant and anti-inflammatory effects. Following oral administration, OMV-Gr17/Gal showed great biocompatibility and prolonged intestinal retention, effectively alleviating the colitis symptoms. Mechanistically, OMV-Gr17/Gal conferred superior anti-colitis efficacy compared to enterocin Gr17 by enhancing the elimination of S. typhimurium from organs, strengthening intestinal barrier function through increased mucus secretion and tight junction expression, suppressing inflammatory responses via MAPK/NF-κB inhibition and T helper 17/regulatory T cells (Th17/Treg) balance restoration, and more effectively remodeling the gut microbiota with elevated short-chain fatty acids (SCFAs) production. This study highlights the significant potential of engineered OMVs to improve the oral bioavailability of bacteriocins and provides new insights into ameliorating S. typhimurium-induced colitis.