title: Helicobacter pylori-induced inhibition of vascular endothelial cell functions: a role for VacA-dependent nitric oxide reduction.
abstract: Epidemiological and clinical studies provide compelling support for a causal relationship between Helicobacter pylori infection and endothelial dysfunction, leading to vascular diseases. However, clear biochemical evidence for this association is limited. In the present study, we have conducted a comprehensive investigation of endothelial injury in bovine aortic endothelial cells (BAECs) induced by H. pylori-conditioned medium (HPCM) prepared from H. pylori 60190 [vacuolating cytotoxin A (Vac(+))]. BAECs were treated with either unconditioned media, HPCM (0-25% vol/vol), or Escherichia coli-conditioned media for 24 h, and cell functions were monitored. Vac(+) HPCM significantly decreased BAEC proliferation, tube formation, and migration (by up to 44%, 65%, and 28%, respectively). Posttreatment, we also observed sporadic zonnula occludens-1 immunolocalization along the cell-cell border, and increased BAEC permeability to FD40 Dextran, indicating barrier reduction. These effects were blocked by 5-nitro-2-(3-phenylpropylamino)benzoic acid (VacA inhibitor) and were not observed with conditioned media prepared from either VacA-deleted H. pylori or E. coli. The cellular mechanism mediating these events was also considered. Vac(+) HPCM (but not Vac(-)) reduced nitric oxide (NO) by >50%, whereas S-nitroso-N-acetylpenicillamine, an NO donor, recovered all Vac(+) HPCM-dependent effects on cell functions. We further demonstrated that laminar shear stress, an endothelial NO synthase/NO stimulus in vivo, could also recover the Vac(+) HPCM-induced decreases in BAEC functions. This study shows, for the first time, a significant proatherogenic effect of H. pylori-secreted factors on a range of vascular endothelial dysfunction markers. Specifically, the VacA-dependent reduction in endothelial NO is indicated in these events. The atheroprotective impact of laminar shear stress in this context is also evident.
authors.affiliation: School of Biotechnology, Dublin City University, Dublin, Ireland.
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Tobin
authors.forename: Gary T
authors.initials: GT
authors.lastname: Henehan
authors.forename: Ronan P
authors.initials: RP
authors.lastname: Murphy
authors.forename: John C
authors.initials: JC
authors.lastname: Atherton
authors.forename: Anthony F
authors.initials: AF
authors.lastname: Guinan
authors.forename: Steven W
authors.initials: SW
authors.lastname: Kerrigan
authors.forename: Dermot
authors.initials: D
authors.lastname: Cox
authors.forename: Paul A
authors.initials: PA
authors.lastname: Cahill
authors.forename: Philip M
authors.initials: PM
authors.lastname: Cummins
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D002463:Cell Membrane Permeability; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000378:metabolism; D015536:Down-Regulation; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016480:Helicobacter pylori / Q000378:metabolism* / Q000472:pathogenicity; D008565:Membrane Proteins / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D018919:Neovascularization, Physiologic / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009579:Nitrobenzoates / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D013314:Stress, Mechanical; D062826:Zonula Occludens-1 Protein
chemical_list: D001426:Bacterial Proteins; D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D020030:Nitric Oxide Donors; D009579:Nitrobenzoates; D010750:Phosphoproteins; C074689:VacA protein, Helicobacter pylori; D062826:Zonula Occludens-1 Protein; D009569:Nitric Oxide; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D026423:S-Nitroso-N-Acetylpenicillamine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester