10.10 - Adenovirus increases arrhythmia susceptibility during acute cardiac infection

Rachel Padget (Virginia Tech, Virginia Tech), Grace Blair (Fralin Biomedical Research Institute, Fralin Biomedical Research Institute), Michael North (Virginia Tech Carilion School of Medicine), D. Ryan King (Virginia Tech, Virginia Tech, Virginia Tech), Michael Zeitz (Fralin Biomedical Research Institute), Mira Tanenbaum (Virginia Tech Carilion School of Medicine), Gregory Hoeker (Fralin Biomedical Research Institute), Sharon Swanger (Fralin Biomedical Research Institute, Fralin Biomedical Research Institute), Steven Poelzing (Fralin Biomedical Research Institute, Fralin Biomedical Research Institute, Fralin Biomedical Research Institute), James Smyth (Fralin Biomedical Research Institute, Fralin Biomedical Research Institute, Fralin Biomedical Research Institute)

Myocarditis is responsible for 42% of sudden cardiac death in young adults, yet mechanisms underlying virally induced arrhythmia remain elusive. Adenovirus is a leading etiological agent of myocarditis but species-specificity has limited development of animal disease models. Normal electrical impulse propagation in the heart is achieved through intercellular coupling via gap junctions, composed primarily of connexin43 (Cx43). Changes in Cx43 expression, localization, and/or function underlie the arrhythmias of sudden cardiac death. Given that gap junctions also propagate innate and adaptive antiviral immune responses, we hypothesized that adenovirus would target Cx43 to facilitate replication. Our prior work has demonstrated that Cx43 expression and function are indeed reduced rapidly during adenoviral infection limiting gap junction communication in human epithelial and cardiac cells. We are now employing a recently described cardiotropic strain of mouse adenovirus, MAdV-3, to develop our work into whole animal studies and investigate virally-induced alterations in cardiac electrophysiology and the molecular mechanisms of the resulting arrhythmogenic substrate. Adult mice were inoculated with MAdV-3 and sampled after 7 days to model acute cardiac infection. We find MAdV-3 viral genomes are specifically enriched in heart tissue, confirming cardiotropism. No cardiomyopathy was apparent by echocardiography or histopathology, consistent with human acute myocarditis patients. We find reductions in cardiac ion channel and connexin mRNA transcript levels after infection, and at the protein level, Cx43 is phosphorylated at residues known to reduce function. Ex vivo optical mapping experiments illustrate decreased conduction velocity in infected hearts. Turning to primary adult mouse cardiomyocytes, we detect prolonged action potential duration and impaired K+ current in infected cells by patch clamping. Confocal and super-resolution localization microscopy of infected cardiac tissue and isolated cardiomyocytes reveals remodeling of gap junctions with alterations in complexing with scaffolding proteins and other ion channels at the cell-cell junction. Finally, employing human iPSC-derived cardiomyocytes and human adenovirus type-5, we find increased Cx43 phosphorylation and, using optical mapping, perturbation of intercellular coupling during infection, just as we see with MAdV-3. Our data demonstrate that reduced cellular coupling and ion channel function during adenoviral infection generates an arrhythmogenic substrate prior to an appreciable immune response or cardiomyopathy development. MAdV-3 infection therefore provides a novel model of cardiac infection and myocarditis and provides physiologically relevant insight into mechanisms of virally-induced arrhythmias.

F31HL152649 RLP
R01 HL132236 JWS