Characterisation of Murine Cytomegalovirus Myocarditis: Cellular Infiltration of the Heart and Virus Persistence

The Journal of Immunology

Yusung²,

Frisancho³

et al. 2003

Self Cite

225

240

Th1-type immune responses, mediated by IL-12-induced IFN-γ, protect the host from most viral infections. To investigate the role of IL-12 and IFN-γ on the development of Coxsackievirus B3 (CB3)-induced myocarditis, we examined the level of inflammation, viral replication, and cytokine production in IL-12Rβ1- and IFN-γ-deficient mice following CB3 infection. We report that IL-12Rβ1 deficiency results in decreased viral replication and inflammation in the heart, while IFN-γ deficiency exacerbates CB3 replication. Importantly, decreased IL-1β and IL-18 levels in IL-12Rβ1-deficient hearts correlated directly with decreased myocardial inflammation. Because IL-1β and IL-18 were associated with myocardial inflammation, we examined the effect of TLR4 deficiency on CB3 infection and myocarditis. We found that TLR4-deficient mice also had significantly reduced levels of myocarditis, viral replication, and IL-1β/IL-18, just as we had observed in IL-12Rβ1-deficient mice. This is the first report that TLR4 influences CB3 replication. These results show that IL-12Rβ1 and TLR4 exacerbate CB3 infection and myocarditis while IFN-γ protects against viral replication. The remarkable similarities between the effects of IL-12Rβ1 and TLR4 suggest that these receptors share common downstream pathways that directly influence IL-1β and IL-18 production, and confirm that IL-1β and IL-18 play a significant role in the pathogenesis of CB3-induced myocarditis. These findings have important implications not only for the pathogenesis of myocarditis, but for other autoimmune diseases triggered by viral infections.

Section: Plaque Assaymentioning

confidence: 99%

IL-12 Receptor β1 and Toll-Like Receptor 4 Increase IL-1β- and IL-18-Associated Myocarditis and Coxsackievirus Replication

The Journal of Immunology

Yusung²,

Frisancho³

et al. 2003

Self Cite

225

240

“…The level of infectious virus was determined in individual homogenates by plaque assay according to standard procedures (5,28). Samples were processed in the same manner as for cytokine analysis.…”

Section: Plaque Assaymentioning

confidence: 99%

IL-12 Protects against Coxsackievirus B3-Induced Myocarditis by Increasing IFN-γ and Macrophage and Neutrophil Populations in the Heart

The Journal of Immunology

Frisancho-Kiss²,

Yusung³

et al. 2005

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127

122

Th1-type immune responses, mediated by IL-12-induced IFN-γ, are believed to exacerbate certain autoimmune diseases. We recently found that signaling via IL-12Rβ1 increases coxsackievirus B3 (CVB3)-induced myocarditis. In this study, we examined the role of IL-12 on the development of CVB3-induced myocarditis using mice deficient in IL-12p35 that lack IL-12p70. We found that IL-12 deficiency did not prevent myocarditis, but viral replication was significantly increased. Although there were no changes in the total percentage of inflammatory cells in IL-12-deficient hearts compared with wild-type BALB/c controls by FACS analysis, macrophage and neutrophil populations were decreased. This decrease corresponded to reduced TNF-α and IFN-γ levels in the heart, suggesting that macrophage and/or neutrophil populations may be a primary source of TNF-α and IFN-γ during acute CVB3 myocarditis. Increased viral replication in IL-12-deficient mice was not mediated by reduced TNFRp55 signaling, because viral replication was unaltered in TNFRp55-deficient mice. However, STAT4 or IFN-γ deficiency resulted in significantly increased viral replication and significantly reduced TNF-α and IFN-γ levels in the heart, similar to IL-12 deficiency, indicating that the IL-12/STAT4 pathway of IFN-γ production is important in limiting CVB3 replication. Furthermore, STAT4 or IFN-γ deficiency also increased chronic CVB3 myocarditis, indicating that therapeutic strategies aimed at reducing Th1-mediated autoimmune diseases may exacerbate common viral infections such as CVB3 and increase chronic inflammatory heart disease.

“…3D) [15]. Although viral genome can be detected in heart tissue during chronic myocarditis, persistent virus is found in both susceptible and resistant strains of mice [13,22].…”

Section: Introductionmentioning

confidence: 99%

Coxsackievirus-induced myocarditis in mice: A model of autoimmune disease for studying immunotoxicity

Rose²

2007

Methods

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176

185

Excellent animal models are available of virus-induced and autoimmune heart disease that are remarkably similar to human disease. Developing good animal models for heart disease is crucial because cardiovascular disease is now the leading cause of death in the United States and is estimated to be the leading cause of death in the world by the year 2020. A significant proportion of heart disease in Western populations is associated with inflammation. Myocarditis, or inflammation of the heart muscle, is the major cause of sudden death in young adults. Although most individuals recover from acute myocarditis, genetically susceptible individuals may go on to develop chronic myocarditis and dilated cardiomyopathy (DCM) resulting in congestive heart failure. In this article, we describe a model of autoimmune myocarditis and DCM induced by inoculation with heart-passaged coxsackievirus B3 (CVB3). Intraperitoneal inoculation of susceptible mice with CVB3 induces acute cardiac inflammation from days 7 to 14 post infection (pi) that progresses to chronic myocarditis and DCM from day 28 to at least 56 pi. The model of CVB3-induced myocarditis presented here allows dissection of the contribution of viral infection and xenobiotics on immune dysregulation and inflammation in the heart. An improved understanding of the interaction between environmental exposures and the development of heart disease represents a clear challenge for immunotoxicologists.