title: Effects of myeloid differentiation primary response gene 88 (MyD88) activation on Helicobacter infection in vivo and induction of a Th17 response.
abstract: BACKGROUND
  Helicobacter pylori is a spiral-shaped Gram-negative microaerophilic bacterium associated with a number of gastrointestinal disorders, including gastritis, peptic ulcers, and gastric cancer. Several studies have implicated a Th17 response as a key to protective immunity against Helicobacter.
  
  
  METHODS
  Wild type (WT) and MyD88-deficient (MyD88(-/-)) mice in the C57BL/6 background were infected with H. felis for 6 and 25 weeks and colonization density and host response evaluated. Real-time PCR was used to determine the expression of cytokines and antimicrobial peptides in the gastric tissue of mice.
  
  
  RESULTS
  mRNA expression levels of the Th17 cytokines interleukin-17A (IL-17A) and IL-22 were markedly up-regulated in WT compared with MyD88(-/-) mice both at 6 and at 25 weeks in response to infection with H. felis, indicating that induction of Th17 responses depends on MyD88 signaling. Furthermore, reduction in the expression of Th17-dependent intestinal antimicrobial peptide lipocalin-2 was linked with increased bacterial burden in the absence of MyD88 signaling.
  
  
  CONCLUSIONS
  We provide evidence showing that MyD88-dependent signaling is required for the host to induce a Th17 response for the control of Helicobacter infection.
authors.affiliation: Department of Medicine, San Diego School of Medicine, University of California, La Jolla, 92093-0640, USA. mobonyo@ucsd.edu
authors.forename: Marygorret
authors.initials: M
authors.lastname: Obonyo
authors.forename: Barry
authors.initials: B
authors.lastname: Rickman
authors.forename: Donald G
authors.initials: DG
authors.lastname: Guiney
mesh_terms: D000209:Acute-Phase Proteins / Q000378:metabolism; D000818:Animals; D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D023082:Defensins / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism; D016481:Helicobacter Infections / Q000235:genetics / Q000276:immunology*; D044922:Helicobacter felis / Q000276:immunology*; D000071068:Lipocalin-2; D054834:Lipocalins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000502:physiology*; D015513:Oncogene Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D058504:Th17 Cells / Q000276:immunology*
chemical_list: D000209:Acute-Phase Proteins; D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins; D016207:Cytokines; D023082:Defensins; D000071068:Lipocalin-2; D054834:Lipocalins; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D015513:Oncogene Proteins; C071332:Lcn2 protein, mouse