Proteomic and functional characterization of the outer membrane vesicles from the gastric pathogen Helicobacter pylori

Abstract

The gastric pathogen Helicobacter pylori causes a spectrum of gastro-duodenal diseases, which may be mediated in part by the outer membrane vesicles (OMVs) constitutively shed by the pathogen. We aimed to determine the proteome of H. pylori OMV to help evaluate the mechanisms whereby these structures confer their known immuno-modulatory and cytotoxic activities to host cells, as such disease-associated activities are also conferred by the bacterium from which the vesicles are derived. We also evaluated the effect of the OMV on gastric/colonic epithelial cells, duodenal explants and neutrophils. A proteomic analysis of the OMV proteins separated by SDS-PAGE from two strains of H. pylori (J99 and NCTC 11637) was undertaken and 162 OMV-associated proteins were identified in J99 and 91 in NCTC 11637 by LC-MS/MS. The vesicles are rich in membrane proteins, porins, adhesins and several molecules known to modulate chemokine secretion, cell proliferation and other host cellular processes. Further, the OMVs are also vehicles for the carriage of the cytotoxin-associated gene A cytotoxin in addition to the previously documented toxin, vacuolating cytotoxin. Taken together, it is evident from the proteome of H. pylori OMV that these structures are equipped with the molecules required to interact with host cells in a manner not dissimilar from the intact pathogen.

Chlamydia trachomatis secretion of hypothetical protein CT622 into host cell cytoplasm via a secretion pathway that can be inhibited by the type III secretion system inhibitor compound 1

“…It has been hypothesized that the intra-inclusion luminal vesicles may represent outer membrane vesicles (OMVs) Giles et al, 2006). In other Gram-negative bacterial systems, the OMVs can engulf periplasmic and outer-membrane proteins and transport them out of bacterial organisms (Balsalobre et al, 2006;Ellis & Kuehn, 2010;Galka et al, 2008;Kim et al, 2008;Kouokam et al, 2006;Kuehn & Kesty, 2005;Mullaney et al, 2009). To be vesicalized by OMVs, CT622 and CT621 must be first translocated into the chlamydial periplasmic region or outer membrane.…”

Helicobacter pyloridefense against oxidative attack

“…The assertion that Hp-Tpx is involved in defense against exogenous oxidative attack is strengthened by the fact that Hp-Tpx has been reported as a potential membrane-associated protein (4, 108) and has been detected in H. pylori outer membrane vesicles (68). Although other studies have failed to detect Hp-Tpx extracellularly (89), this may reflect differences in growth conditions, as Tpx has been shown to have variable extracellular expression in other bacterial pathogens, depending on media composition and atmospheric oxygen concentration (38).…”

“…Our own immunogold electron-microscopic analysis found that cell surface Hp-SOD is heavily expressed on the flagella of H. pylori and that Hp-SOD is also present in secreted outer membrane vesicles (Fig. 2) (68). While the role of these outer membrane vesicles in the pathophysiology of H. pylori is incompletely understood, they are thought to represent extracellular release of bioactive compounds for interbacterial and host interactions and are known to be capable of binding to host epithelial cells (77).…”

Helicobacter pylori Membrane Vesicles Stimulate Innate Pro- and Anti-Inflammatory Responses and Induce Apoptosis in Jurkat T Cells

“…In addition to free soluble secretion, both VacA and GGT are packaged into MV (31,47) by H. pylori. MV are more likely to cross the epithelial barrier than whole bacteria and so might exert long-range effects on host immune cells.…”