title: TLR3 deficiency induces chronic inflammatory cardiomyopathy in resistant mice following coxsackievirus B3 infection: role for IL-4.
abstract: Recent findings indicate that TLR3 polymorphisms increase susceptibility to enteroviral myocarditis and inflammatory dilated cardiomyopathy (iDCM) in patients. TLR3 signaling has been found to inhibit coxsackievirus B3 (CVB3) replication and acute myocarditis in mouse models, but its role in the progression from myocarditis to iDCM has not been previously investigated. In this study we found that TLR3 deficiency increased acute (P = 5.9 × 10(-9)) and chronic (P = 6.0 × 10(-7)) myocarditis compared with WT B6.129, a mouse strain that is resistant to chronic myocarditis and iDCM. Using left ventricular in vivo hemodynamic assessment, we found that TLR3-deficient mice developed progressively worse chronic cardiomyopathy. TLR3 deficiency significantly increased viral replication in the heart during acute myocarditis from day 3 through day 12 after infection, but infectious virus was not detected in the heart during chronic disease. TLR3 deficiency increased cytokines associated with a T helper (Th)2 response, including IL-4 (P = 0.03), IL-10 (P = 0.008), IL-13 (P = 0.002), and TGF-β(1) (P = 0.005), and induced a shift to an immunoregulatory phenotype in the heart. However, IL-4-deficient mice had improved heart function during acute CVB3 myocarditis by echocardiography and in vivo hemodynamic assessment compared with wild-type mice, indicating that IL-4 impairs cardiac function during myocarditis. IL-4 deficiency increased regulatory T-cell and macrophage populations, including FoxP3(+) T cells (P = 0.005) and Tim-3(+) macrophages (P = 0.004). Thus, TLR3 prevents the progression from myocarditis to iDCM following CVB3 infection by reducing acute viral replication and IL-4 levels in the heart.
authors.affiliation: Department of Environmental Health Sciences, Johns Hopkins University, Bloomberg School of Public Health and School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Abston
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Coronado
authors.forename: Adriana
authors.initials: A
authors.lastname: Bucek
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Onyimba
authors.forename: Jessica E
authors.initials: JE
authors.lastname: Brandt
authors.forename: J Augusto
authors.initials: JA
authors.lastname: Frisancho
authors.forename: Eunyong
authors.initials: E
authors.lastname: Kim
authors.forename: Djahida
authors.initials: D
authors.lastname: Bedja
authors.forename: Yoon-kyu
authors.initials: YK
authors.lastname: Sung
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Radtke
authors.forename: Kathleen L
authors.initials: KL
authors.lastname: Gabrielson
authors.forename: Wayne
authors.initials: W
authors.lastname: Mitzner
authors.forename: DeLisa
authors.initials: D
authors.lastname: Fairweather
mesh_terms: D000208:Acute Disease; D000818:Animals; D002311:Cardiomyopathy, Dilated / Q000235:genetics / Q000276:immunology / Q000821:virology*; D002908:Chronic Disease; D003384:Coxsackievirus Infections / Q000235:genetics / Q000276:immunology*; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D004195:Disease Models, Animal; D029822:Enterovirus B, Human / Q000502:physiology*; D006801:Humans; D015847:Interleukin-4 / Q000032:analysis / Q000276:immunology*; D008264:Macrophages / Q000276:immunology / Q000821:virology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009205:Myocarditis / Q000235:genetics / Q000276:immunology / Q000821:virology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000821:virology; D051196:Toll-Like Receptor 3 / Q000235:genetics / Q000276:immunology*; D014779:Virus Replication / Q000276:immunology
chemical_list: D016207:Cytokines; C519703:TLR3 protein, mouse; D051196:Toll-Like Receptor 3; D015847:Interleukin-4