title: The neutrophil-activating protein (HP-NAP) of Helicobacter pylori is a protective antigen and a major virulence factor.
abstract: Helicobacter pylori infection induces the appearance of inflammatory infiltrates, consisting mainly of neutrophils and monocytes, in the human gastric mucosa. A bacterial protein with neutrophil activating activity (HP-NAP) has been previously identified, but its role in infection and immune response is still largely unknown. Here, we show that vaccination of mice with HP-NAP induces protection against H. pylori challenge, and that the majority of infected patients produce antibodies specific for HP-NAP, suggesting an important role of this factor in immunity. We also show that HP-NAP is chemotactic for human leukocytes and that it activates their NADPH oxidase to produce reactive oxygen intermediates, as demonstrated by the translocation of its cytosolic subunits to the plasma membrane, and by the lack of activity on chronic granulomatous disease leukocytes. This stimulating effect is strongly potentiated by tumor necrosis factor alpha and interferon gamma and is mediated by a rapid increase of the cytosolic calcium concentration. The activation of leukocytes induced by HP-NAP is completely inhibited by pertussis toxin, wortmannin, and PP1. On the basis of these results, we conclude that HP-NAP is a virulence factor important for the H. pylori pathogenic effects at the site of infection and a candidate antigen for vaccine development.
authors.affiliation: Centro Consiglio Nazionale Ricerche Biomembrane and Dipartimento di Scienze Biomediche, Università di Padova, 35121 Padova, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Satin
authors.forename: G
authors.initials: G
authors.lastname: Del Giudice
authors.forename: V
authors.initials: V
authors.lastname: Della Bianca
authors.forename: S
authors.initials: S
authors.lastname: Dusi
authors.forename: C
authors.initials: C
authors.lastname: Laudanna
authors.forename: F
authors.initials: F
authors.lastname: Tonello
authors.forename: D
authors.initials: D
authors.lastname: Kelleher
authors.forename: R
authors.initials: R
authors.lastname: Rappuoli
authors.forename: C
authors.initials: C
authors.lastname: Montecucco
authors.forename: F
authors.initials: F
authors.lastname: Rossi
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D020013:Calcium Signaling; D002634:Chemotaxis, Leukocyte; D003600:Cytosol / Q000378:metabolism; D016481:Helicobacter Infections / Q000517:prevention & control*; D016480:Helicobacter pylori / Q000276:immunology / Q000472:pathogenicity*; D006801:Humans; D016023:Integrins / Q000096:biosynthesis; D051379:Mice; D009000:Monocytes / Q000276:immunology; D019255:NADPH Oxidases / Q000378:metabolism; D009504:Neutrophils / Q000276:immunology*; D037342:Pertussis Toxin; D011506:Proteins / Q000494:pharmacology; D017382:Reactive Oxygen Species; D014611:Vaccination; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D016023:Integrins; D011506:Proteins; D017382:Reactive Oxygen Species; D010566:Virulence Factors, Bordetella; C092412:neutrophil-activating protein A, Helicobacter pylori; C073882:phosphoprotein phosphatase inhibitor 1; D019255:NADPH Oxidases; D037342:Pertussis Toxin; D000077191:Wortmannin