title: Dual oxidases control release of hydrogen peroxide by the gastric epithelium to prevent Helicobacter felis infection and inflammation in mice.
abstract: OBJECTIVE
  Dual oxidases (DUOX) are conserved reduced nicotinamide adenine dinucleotide phosphate oxidases that produce H2O2 at the epithelial cell surface. The DUOX enzyme comprises the DUOX and DUOX maturation factor (DUOXA) subunits. Mammalian genomes encode 2 DUOX isoenzymes (DUOX1/DUOXA1 and DUOX2/DUOXA2). Expression of these genes is up-regulated during bacterial infections and chronic inflammatory diseases of the luminal gastrointestinal tract. The roles of DUOX in cellular interactions with microbes have not been determined in higher vertebrates.
  
  
  METHODS
  Mice with disruptions of Duoxa1 and Duoxa2 genes (Duoxa(-/-) mice) and control mice were infected with Helicobacter felis to create a model of Helicobacter pylori infection--the most common human chronic infection.
  
  
  RESULTS
  Infection with H. felis induced expression of Duox2 and Duoxa2 in the stomachs of wild-type mice, and DUOX protein specifically localized to the apical surface of epithelial cells. H. felis colonized the mucus layer in the stomachs of Duoxa(-/-) mice to a greater extent than in control mice. The increased colonization persisted into the chronic phase of infection and correlated with an increased, yet ineffective, inflammatory response. H. felis colonization also was increased in Duoxa(+/-) mice, compared with controls. We observed reduced expression of the H2O2-inducible katA gene in H. felis that colonized Duoxa(-/-) mice, compared with that found in controls (P = .0002), indicating that Duox causes oxidative stress in these bacteria. In vitro, induction of oxidative defense by H. felis failed to prevent a direct bacteriostatic effect at sustained levels of H2O2 as low as 30 μmol/L.
  
  
  CONCLUSIONS
  Based on studies of Duoxa(-/-) mice, the DUOX enzyme complex prevents gastric colonization by H. felis and the inflammatory response. These findings indicate the nonredundant function of epithelial production of H2O2 in restricting microbial colonization.
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan. Electronic address: hgrasber@gmail.com.
authors.forename: Helmut
authors.initials: H
authors.lastname: Grasberger
authors.forename: Mohamad
authors.initials: M
authors.lastname: El-Zaatari
authors.forename: Duyen T
authors.initials: DT
authors.lastname: Dang
authors.forename: Juanita L
authors.initials: JL
authors.lastname: Merchant
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004848:Epithelium / Q000378:metabolism / Q000382:microbiology; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism* / Q000382:microbiology; D005756:Gastritis / Q000378:metabolism / Q000517:prevention & control*; D016481:Helicobacter Infections / Q000378:metabolism / Q000517:prevention & control*; D044922:Helicobacter felis / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013270:Stomach / Q000382:microbiology; D015854:Up-Regulation
chemical_list: C560186:DUOXA1 protein, mouse; C572869:DUOXA2 protein, mouse; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D006861:Hydrogen Peroxide
keywords: ATP; DUOX; DUOXA; Dual Oxidase; FBS; GI; GOX; Gastritis; HRP; KRH; Krebs–Ringer–HEPES buffer; Mouse Model; Mucosal Immunity; NADPH; PBS; adenosine triphosphate; dual oxidase maturation factor; dual oxidases; fetal bovine serum; gastrointestinal; glucose oxidase; horseradish peroxidase; mRNA; messenger RNA; phosphate-buffered saline; reduced nicotinamide adenine dinucleotide phosphate