title: Protease-activated receptor-2 regulates the innate immune response to viral infection in a coxsackievirus B3-induced myocarditis.
abstract: OBJECTIVE
  This study sought to evaluate the role of protease-activated receptor-2 (PAR2) in coxsackievirus B3 (CVB3)-induced myocarditis.
  
  
  BACKGROUND
  An infection with CVB3 leads to myocarditis. PAR2 modulates the innate immune response. Toll-like receptor-3 (TLR3) is crucial for the innate immune response by inducing the expression of the antiviral cytokine interferon-beta (IFNβ).
  
  
  METHODS
  To induce myocarditis, wild-type (wt) and PAR2 knockout (ko) mice were infected with 10(5) plaque-forming units CVB3. Mice underwent hemodynamic measurements with a 1.2-F microconductance catheter. Wt and PAR2ko hearts and cardiac cells were analyzed for viral replication and immune response with plaque assay, quantitative polymerase chain reaction, Western blot, and immunohistochemistry.
  
  
  RESULTS
  Compared with wt mice, PAR2ko mice and cardiomyocytes exhibited a reduced viral load and developed no myocarditis after infection with CVB3. Hearts and cardiac fibroblasts from PAR2ko mice expressed higher basal levels of IFNβ than wt mice did. Treatment with CVB3 and polyinosinic:polycytidylic acid led to higher IFNβ expression in PAR2ko than in wt fibroblasts and reduced virus replication in PAR2ko fibroblasts was abrogated by neutralizing IFNβ antibody. Overexpression of PAR2 reduced the basal IFNβ expression. Moreover, a direct interaction between PAR2 and Toll-like receptor 3 was observed. PAR2 expression in endomyocardial biopsies of patients with nonischemic cardiomyopathy was positively correlated with myocardial inflammation and negatively with IFNβ expression and left ventricular ejection fraction.
  
  
  CONCLUSIONS
  PAR2 negatively regulates the innate immune response to CVB3 infection and contributes to myocardial dysfunction. The antagonism of PAR2 is of therapeutic interest to strengthen the antiviral response after an infection with a cardiotropic virus.
authors.affiliation: Department of Cardiology and Pneumology, Charité-Universitätsmedizin Berlin, Berlin, Germany; Institute for Chemistry-Biochemistry, Freie Universität Berlin, Berlin, Germany.
authors.forename: Alice
authors.initials: A
authors.lastname: Weithauser
authors.forename: Peter
authors.initials: P
authors.lastname: Bobbert
authors.forename: Silvio
authors.initials: S
authors.lastname: Antoniak
authors.forename: Andreas
authors.initials: A
authors.lastname: Böhm
authors.forename: Bernhard H
authors.initials: BH
authors.lastname: Rauch
authors.forename: Karin
authors.initials: K
authors.lastname: Klingel
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Savvatis
authors.forename: Heyo K
authors.initials: HK
authors.lastname: Kroemer
authors.forename: Carsten
authors.initials: C
authors.lastname: Tschope
authors.forename: Andrea
authors.initials: A
authors.lastname: Stroux
authors.forename: Heinz
authors.initials: H
authors.lastname: Zeichhardt
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Poller
authors.forename: Nigel
authors.initials: N
authors.lastname: Mackman
authors.forename: Heinz-Peter
authors.initials: HP
authors.lastname: Schultheiss
authors.forename: Ursula
authors.initials: U
authors.lastname: Rauch
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis; D001706:Biopsy; D015153:Blotting, Western; D004195:Disease Models, Animal; D029822:Enterovirus B, Human / Q000276:immunology*; D004769:Enterovirus Infections / Q000276:immunology* / Q000821:virology; D005786:Gene Expression Regulation; D007113:Immunity, Innate; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009205:Myocarditis / Q000276:immunology* / Q000378:metabolism / Q000821:virology; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D012313:RNA / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D044464:Receptor, PAR-2 / Q000096:biosynthesis* / Q000235:genetics; D051196:Toll-Like Receptor 3 / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000914:Antibodies, Viral; D044464:Receptor, PAR-2; D051196:Toll-Like Receptor 3; D012313:RNA
keywords: AP; CAR; CCL; CD; CVB3; DAF; DMEM; Dulbecco modified Eagle medium; FBS; HL; IFNβ; IFNγ; IL; LVEF; P-Stat1; PAR2; PBS; PCR; TLR; TNFα; Toll-like receptor; Toll-like receptor 3; activating peptide; chemokine ligand; cluster of differentiation; coxsackievirus B3; coxsackievirus-adenovirus receptor; decay-accelerating receptor; double-stranded ribonucleic acid; dsRNA; fetal bovine serum; human leukocyte; interferon beta; interferon gamma; interferon-beta; interleukin; knockout; ko; left ventricular ejection fraction; mRNA; messenger ribonucleic acid; mock plasmid; myocarditis; p.i.; pVitro; phosphate-buffered saline; phospho-signal transducer and activator of transcription-1; poly(I:C); polyinosinic: polycytidylic acid; polymerase chain reaction; post-infection; protease-activated receptor 2; protease-activated receptor-2; tumor necrosis factor-alpha; wild type; wt