Of the proteins identified in P. aeruginosa OMVs using
LC–MS/MS, those with known functions include outer
membrane proteins involved in antibiotic resistance, proteases,
and proteins involved in host–bacteria interaction
(Choi et al. 2011). In addition, Ellis et al. characterized
the inflammatory responses caused by P. aeruginosa
OMVs. They found that P. aeruginosa OMVs induce
increased expression of MIP-2, TNF-α, IL-β, and IL-6 in
RAW 264.7 macrophages compared with purified P. aeruginosa
LPS. Both TLR ligands LPS and flagellin contributed
to specific vesicle cytokine responses, whereas
the CpG DNA content of vesicles did not. It is possible
that a potent and distinct inflammatory response to vesicles
is the cumulative effect of sensing vesicle-associated
heterogeneous protein and LPS ligands by macrophages