Bacterial extracellular vesicles as multifaceted regulators of human diseases and emerging therapeutic platforms.

Outer membrane vesicles (OMVs) are nanoscale vesicles actively released by Gram-negative bacteria, and have become key mediators in bacterial physiology, host-pathogen interactions, and disease pathogenesis. The biogenesis of OMVs is a dynamic process, which results from membrane homeostasis imbalance, peptidoglycan remodeling, and stress responses. These mechanisms enable virulence factors, immune-regulatory molecules, and nucleic acids to be selectively or randomly loaded into vesicles. With their ability to penetrate barriers and spread throughout the body, OMVs are widely involved in the occurrence and development of a variety of human diseases. It is worth noting that the inherent characteristics of OMVs have made them a promising platform in the fields of vaccine development, cancer immunotherapy, antibacterial regulation, and disease diagnosis. This review systematically integrates the current mechanistic research and translational research results, aiming to construct a unified framework, clarify the internal relationship between the biogenesis, functional heterogeneity, and biomedical applications of OMVs, and explore the key challenges and future development directions for promoting the clinical translation of OMV-based diagnostic and therapeutic systems.