title: Helicobacter pylori virulence factors affecting gastric proton pump expression and acid secretion.
abstract: Acute Helicobacter pylori infection of gastric epithelial cells and human gastric biopsies represses H,K-ATPase α subunit (HKα) gene expression and inhibits acid secretion, causing transient hypochlorhydria and supporting gastric H. pylori colonization. Infection by H. pylori strains deficient in the cag pathogenicity island (cag PAI) genes cagL, cagE, or cagM, which do not transfer CagA into host cells or induce interleukin-8 secretion, does not inhibit HKα expression, nor does a cagA-deficient strain that induces IL-8. To test the hypothesis that virulence factors other than those mediating CagA translocation or IL-8 induction participate in HKα repression by activating NF-κB, AGS cells transfected with HKα promoter-Luc reporter constructs containing an intact or mutated NF-κB binding site were infected with wild-type H. pylori strain 7.13, isogenic mutants lacking cag PAI genes responsible for CagA translocation and/or IL-8 induction (cagA, cagζ, cagε, cagZ, and cagβ), or deficient in genes encoding two peptidoglycan hydrolases (slt and cagγ). H. pylori-induced AGS cell HKα promoter activities, translocated CagA, and IL-8 secretion were measured by luminometry, immunoblotting, and ELISA, respectively. Human gastric biopsy acid secretion was measured by microphysiometry. Taken together, the data showed that HKα repression is independent of IL-8 expression, and that CagA translocation together with H. pylori transglycosylases encoded by slt and cagγ participate in NF-κB-dependent HKα repression and acid inhibition. The findings are significant because H. pylori factors other than CagA and IL-8 secretion are now implicated in transient hypochlorhydria which facilitates gastric colonization and potential triggering of epithelial progression to neoplasia.
authors.affiliation: Department of Medicine, Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Charles E
authors.initials: CE
authors.lastname: Hammond
authors.affiliation: Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina;
authors.forename: Craig
authors.initials: C
authors.lastname: Beeson
authors.affiliation: Vanderbilt University School of Medicine, Nashville, Tennessee; and.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Suarez
authors.affiliation: Vanderbilt University School of Medicine, Nashville, Tennessee; and.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Peek
authors.affiliation: Friedrich-Alexander Universität, Erlangen, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Backert
authors.affiliation: Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, smolkaaj@musc.edu.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Smolka
mesh_terms: D000126:Achlorhydria / Q000209:etiology / Q000378:metabolism; D000942:Antigens, Bacterial / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism; D005744:Gastric Acid / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism* / Q000382:microbiology; D016481:Helicobacter Infections / Q000150:complications / Q000378:metabolism; D016480:Helicobacter pylori / Q000472:pathogenicity / Q000502:physiology; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017494:Proton Pumps / Q000378:metabolism*; D015398:Signal Transduction; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D016209:Interleukin-8; D016328:NF-kappa B; D017494:Proton Pumps; D037521:Virulence Factors; C080866:cagA protein, Helicobacter pylori; C499076:ATP1A1 protein, human; D000254:Sodium-Potassium-Exchanging ATPase
keywords: Helicobacter pylori; acid secretion; proton pump; type 4 secretory system; virulence factors