Table 2.

Varieties of OMV secreted by pathogenic and beneficial bacteria.

Bacteria	Functions of OMVs	References
ETEC	ETEC OMVs can deliver ClyA, a pore-forming cytotoxin expressed by E. coli and some other enterobacteria.	[85]
Pseudomonas aeruginosa	OMVs from Pseudomonas aeruginosa contain multiple virulence factors, resulting a significant increase in the levels of inflammatory factors, triggering inflammation.	[81,82]
H. pylori	H. pylori-derived OMVs exert immunomodulatory effects by inducing the production of pro-inflammatory cytokines and promoting apoptosis of gastric epithelial and immune cells. They also induce apoptosis in human umbilical vein endothelial cells, which may promote atherosclerotic plaque formation.	[85]
V. cholerae	Cholera toxin (CT) is the main virulence factor of Vibrio cholerae, and OMVs may be the important carrier for transporting CT to epithelial cells.	[86]
Bacteroides fragilis	Bacteroides fragilis releases PSA by OMVs, inducing immunomodulatory effects, and prevents experimental colitis.	[87]