title: Sustained nitric oxide synthesis contributes to immunopathology in ongoing myocarditis attributable to interleukin-10 disorders.
abstract: Ongoing coxsackievirus B3 (CVB3) myocarditis is characterized by persistence of viral RNA and chronic inflammation primarily mediated by macrophages and T cells. Activated macrophages produce anti-viral effector molecules comprising reactive nitrogen intermediates; however, reactive nitrogen intermediates also contribute to host tissue damage. Controlled activation of macrophages depends on interferon (IFN)-gamma and interleukin (IL)-10. To evaluate mechanisms involved in CVB3-induced pathogenesis of myocarditis, we determined the relationship of inducible nitric-oxide synthase (iNOS) mRNA expression with IFN-gamma and IL-10 secretion during CVB3 infection in different mouse strains. We found in susceptible A.BY/SnJ mice that develop ongoing myocarditis, a low and delayed IFN-gamma secretion and highly diminished IL-10 production compared with resistant C57BL/6 mice. Consequently, iNOS mRNA synthesis was delayed but clearly prolonged in susceptible mice. IL-10 gene-deficient mice confirmed the regulatory role of IL-10 in the outcome of CVB3 myocarditis. These mice did not establish a persistent cardiac infection and revealed IFN-gamma secretion kinetics similar to resistant mice but showed a slightly elongated cardiac iNOS mRNA expression resulting in extended myocarditis. We conclude that coordinated secretion of IFN-gamma and IL-10 is crucial for the effective resolution of CVB3 myocarditis. Moreover, lack of regulatory IL-10 leads to uncontrolled iNOS mRNA production, thus contributing to ongoing myocardial injury.
authors.affiliation: Dept. of Molecular Pathology, Institute for Pathology, University Hospital Tübingen, Liebermeisterstr. 8, D-72076 Tübingen, Germany.
authors.forename: Gudrun
authors.initials: G
authors.lastname: Szalay
authors.forename: Martina
authors.initials: M
authors.lastname: Sauter
authors.forename: Joachim
authors.initials: J
authors.lastname: Hald
authors.forename: Andreas
authors.initials: A
authors.lastname: Weinzierl
authors.forename: Reinhard
authors.initials: R
authors.lastname: Kandolf
authors.forename: Karin
authors.initials: K
authors.lastname: Klingel
mesh_terms: D000818:Animals; D000917:Antibody Formation; D003384:Coxsackievirus Infections / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D007371:Interferon-gamma / Q000378:metabolism; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009205:Myocarditis / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000502:physiology*; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis
chemical_list: D016753:Interleukin-10; D009569:Nitric Oxide; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse