Early Treatment of Coxsackievirus B3–Infected Animals With Soluble Coxsackievirus-Adenovirus Receptor Inhibits Development of Chronic Coxsackievirus B3 Cardiomyopathy

Abstract

Background: Coxsackie-B-viruses (CVB) are frequent causes of acute myocarditis and dilated cardiomyopathy, but an effective antiviral therapy is still not available. Previously, we and others have demonstrated that treatment with an engineered sCAR-Fc (soluble coxsackievirus-adenovirus receptor fused to the carboxyl-terminus of human IgG) efficiently neutralizes CVB3 and inhibits the development of cardiac dysfunction in mice with acute CVB3-induced myocarditis. In this study, we analyzed the potential of sCAR-Fc for treatment of chronic CVB3-induced myocarditis in an outbred NMRI mouse model. Methods: NMRI mice were infected with the CVB3 strain 31-1-93 and treated with a sCAR-Fc expressing adeno-associated virus 9 vector 1, 3, and 7 days after CVB3 infection. Chronic myocarditis was analyzed on day 28 after infection. Results: Initial investigations showed that NMRI mice develop pronounced chronic myocarditis between day 18 and day 28 after infection with the CVB3 strain 31-1-93. Chronic cardiac infection was characterized by inflammation and fibrosis as well as persistence of viral genomes in the heart tissue and by cardiac dysfunction. Treatment of NMRI mice resulted in a distinct reduction of cardiac inflammation and fibrosis and almost complete elimination of virus RNA from the heart by day 28 after infection. Moreover, hemodynamic measurement revealed improved cardiac contractility and diastolic relaxation in treated mice compared with mice treated with a control vector (mean±SD; maximal pressure, 81.9±9.2 versus 69.4±8.6 mm Hg, P =0.02; left ventricular ejection fraction, 68.9±8.5 versus 54.2±11.5%, P =0.02; dP/dt max , 7275.2±1674 versus 4432.6±1107 mm Hg/s, P =0.004; dP/dt min , −4046.9±776 versus −3146.3±642 mm Hg/s, P =0.046). The therapeutic potential of sCAR-Fc is limited, however, since postponed start of sCAR-Fc treatment either 3 or 7 days after infection could not attenuate myocardial injury. Conclusions: Early therapeutic employment of sCAR-Fc, initiated at the beginning of the primary viremia, inhibits the development of chronic CVB3-induced myocarditis and improves the cardiac function to a level equivalent to that of uninfected animals.

ONX 0914 Lacks Selectivity for the Cardiac Immunoproteasome in CoxsackievirusB3 Myocarditis of NMRI Mice and Promotes Virus-Mediated Tissue Damage

“…The genetic background associated with the immunological make up of NMRI mice, although not well-characterized, is thought to predispose these mice to the development of a chronic course of viral myocarditis [37]. Progression towards chronic heart tissue injury in this strain is a consequence of acute myocarditis, which in A/J mice, showing a severe systemic inflammatory response after infection with cardiotropic CVB3 [44], is principally reversible by ONX 0914 [38].…”

“…Our previous work demonstrated a protective effect of ONX 0914 on acute inflammatory tissue injury of the heart after infection of A/J mice with a cardiotropic CVB3 strain [38]. To investigate how ONX 0914 influences a late consequence of viral infection, we used a well-characterized and frequently used mouse model for chronic viral myocarditis, inoculating outbred NMRI mice with CVB3 strain 31-1-93 [37]. We applied a therapeutic approach, with the initiation of treatment on day 3 post-infection [46], once viral injury of the heart tissue has emerged.…”

“…Using the intraperitoneal inoculation route, the virus initially causes a pancreatitis, resulting in destruction of exocrine cells of the pancreas [34], and subsequently myocarditis, showing variable severity in different laboratory mouse strains [35]. Depending on the strain-specific susceptibility to the disease, mice develop a heterogeneous acute [8,36] and sometimes a chronic stage of the disease [37], providing an opportunity for research into the development of chronic sequela, such as inflammatory cardiomyopathy, which can manifest after acute myocarditis. The i-proteasome plays an important, yet not fully explained role in the process of CVB3-triggered cardiac inflammatory immune response, with both knockout and inhibition of the multi-catalytic protease exacerbating the disease in C57BL/6 mice [3,38].…”

“…In our hands, A/J mice are not ideally suited to investigate the chronic state. NMRI mice, however, while susceptible to acute CVB3-myocarditis, show much less impact on their general well-being and have consistently been shown to develop chronic viral myocarditis [37,45], making them a favored model for later stages of the disease. Regarding the positive effects, ONX 0914 treatment demonstrated in acute myocarditis in A/J mice, we asked the question whether i-proteasome inhibition by ONX 0914 might attenuate the development and severity of chronic myocarditis in NMRI mice as well.…”

An overview of the immune mechanisms of viral myocarditis

“…47 Likewise, attenuated myocarditis was noted in animals receiving soluble receptors/virus receptor traps for CAR and DAF. [48][49][50] Because the virus is cytolytic, it spreads by lysis of the infected cells, leading to the release of RNApackaged virions to infect other cells. 26,36 CVB3 causes myocardial injury via apoptosis and necrosis of cardiomyocytes within 3 to 4 days post-infection ( Figure 1B).…”