| Outer membrane vesicles (OMV) are nanoplike particles secreted by Gram-negative(G-) bacteria. OMV are spherical, bilayer membrane-like structures, mostly 20 to 250 nm in diameter. They are mainly composed of the outer membrane components of bacteria. OMV secreted by pathogens include various components associated with pathogenesis, such as non-protein antigenic lipopolysaccharides, lipids, protein adhesins, invasins, toxins and other pathogenic factors. Pathogenic OMV also contain bacterial DNA, RNA, sRNA and plasmid nucleic acids from bacteria. OMV have been termed a new secretion system of Gram-negative bacteria, which is closely related to a series of functions such as pathogenicity, storage and transmission of drug resistance genes, interbacterial and bacteria-host communication crosstalk. Secretion of pathogenic OMV is associated with the stress response. OMV are considered carriers of virulence factors, drug resistance genes, plasmids, antigen molecules and other bioactive substances and delivered to the host cells. They can lead to the occurrence of epidemics directly or exacerbate the disease. In terms of mechanism, OMV transport toxins to host cells through dynamic-dependent endocytosis, mediate horizontal transfer of drug resistance genes, reduce phage invasion by increasing secretion or protect pathogens of source bacteria or surrounding bacteria from membrane active substances, affect and induce immune responses of cells related to bacterial infection sites or even distant tissues and so on. It can further activate inflammatory response pathways, mediate host cell death and metabolic remodeling. In virtue of the series of biological functions in bacterial pathogenesis, drug resistance, the host physiological barrier (intestinal mucosa barrier, intestinal vessel barrier and blood-brain barrier) damage, niche imbalance of OMV and so forth, it’s of great significance to understand their related biological roles and potential molecular mechanism for developing newly prevention and control strategies . In this review, we focus on the role of OMV and the molecular mechanisms, and discuss their applications. |
