title: PAR2 promotes vaccine-induced protection against Helicobacter infection in mice.
abstract: OBJECTIVE
  Protective immunization limits Helicobacter infection of mice by undetermined mechanisms. Protease-activated receptor 2 (PAR2) signaling is believed to regulate immune and inflammatory responses. We investigated the role of PAR2 in vaccine-induced immunity against Helicobacter infection.
  
  
  METHODS
  Immune responses against Helicobacter infection were compared between vaccinated PAR2-/- and wild-type (WT) mice. Bacterial persistence, gastric pathology, and inflammatory and cellular responses were assessed using the rapid urease test (RUT), histologic analyses, quantitative polymerase chain reaction, and flow cytometry, respectively.
  
  
  RESULTS
  Following vaccination, PAR2-/- mice did not have reductions in Helicobacter felis infection (RUT values were 0.01±0.01 for WT mice and 0.11±0.13 for PAR2-/- mice; P<.05). The vaccinated PAR2-/- mice had reduced inflammation-induced stomach tissue damage (tissue damage scores were 8.83±1.47 for WT mice and 4.86±1.35 for PAR2-/- mice; P<.002) and reduced T-helper (Th)17 responses, based on reduced urease-induced interleukin (IL)-17 secretion by stomach mononuclear cells (5182 ± 1265 pg/mL for WT mice and 350±436 pg/mL for PAR2-/- mice; P<.03) and reduced recruitment of CD4+ IL-17+ T cells into the gastric mucosa of PAR2-/- mice following bacterial challenge (3.7%±1.5% for WT mice and 2.6%±1.1% for PAR2-/- mice; P<.05). In vitro, H felis-stimulated dendritic cells (DCs) from WT mice induced greater secretion of IL-17 by ovalbumin-stimulated OT-II transgenic CD4+ T cells compared with DCs from PAR2-/- mice (4298±347 and 3230±779; P<.04), indicating that PAR2-/- DCs are impaired in priming of Th17 cells. Adoptive transfer of PAR2+/+ DCs into vaccinated PAR2-/- mice increased vaccine-induced protection (RUT values were 0.11±0.10 and 0.26±0.15 for injected and noninjected mice, respectively; P<.03).
  
  
  CONCLUSIONS
  PAR2 activates DCs to mediate vaccine-induced protection against Helicobacter infection in mice.
authors.affiliation: Service of Gastroenterology and Hepatology, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland. dominique.velin@chuv.ch
authors.forename: Dominique
authors.initials: D
authors.lastname: Velin
authors.forename: Sharmal
authors.initials: S
authors.lastname: Narayan
authors.forename: Eric
authors.initials: E
authors.lastname: Bernasconi
authors.forename: Nathalie
authors.initials: N
authors.lastname: Busso
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Ramelli
authors.forename: Michel H
authors.initials: MH
authors.lastname: Maillard
authors.forename: Daniel
authors.initials: D
authors.lastname: Bachmann
authors.forename: Catherine
authors.initials: C
authors.lastname: Pythoud
authors.forename: Hanifa
authors.initials: H
authors.lastname: Bouzourene
authors.forename: Pierre
authors.initials: P
authors.lastname: Michetti
authors.forename: Alexander
authors.initials: A
authors.lastname: So
mesh_terms: D000281:Administration, Intranasal; D019264:Adoptive Transfer; D000818:Animals; D001428:Bacterial Vaccines / Q000008:administration & dosage*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology / Q000382:microbiology / Q000637:transplantation; D004195:Disease Models, Animal; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism; D016481:Helicobacter Infections / Q000276:immunology / Q000378:metabolism / Q000382:microbiology / Q000473:pathology / Q000517:prevention & control*; D044922:Helicobacter felis / Q000276:immunology*; D016480:Helicobacter pylori / Q000201:enzymology / Q000276:immunology*; D018836:Inflammation Mediators / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D044464:Receptor, PAR-2 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013154:Spleen / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D013270:Stomach / Q000187:drug effects* / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D014510:Urease / Q000008:administration & dosage*; D014614:Vaccines, Synthetic / Q000008:administration & dosage
chemical_list: D001428:Bacterial Vaccines; D018836:Inflammation Mediators; D044464:Receptor, PAR-2; D014614:Vaccines, Synthetic; D014510:Urease