Satellite Glial Cell Activation and Sympathetic Imbalance in Cardiomyopathy and Arrhythmias

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PROJECT SUMMARY/ABSTRACT Cardiac injury predisposes patients to heart failure (HF), and ventricular tachycardia/fibrillation (VT/VF). Development of HF and VT/VF after cardiac injury is tightly linked to sympathetic neural remodeling. Although several medications targeting cardiac sympathetic excess reduce mortality following cardiac injury, significant shortcomings of these drugs include off-target effects, limited efficacy, and focus on downstream consequences of neural remodeling such as excess catecholamine release, rather than preventing it upstream. In this proposal, we build on strong preliminary data from humans, porcine, and murine models demonstrating that satellite glial cell (SGC) activation is a central feature of chronic cardiac injury. Activated glia release inflammatory cytokines, ATP, and other factors that modulate neuronal function. Chemogenetic upregulation of glial calcium signaling (as observed in activated glia) increase cardiac sympathetic neuronal excitability, synaptic efficacy, and tonic firing. Based on these novel findings, the goal of this proposal is to test the hypothesis that satellite glial activation and enhanced glial-neuronal signaling is a primary driver of cardiac sympathetic neuronal dysfunction, heart failure and VT/VF after cardiac injury. We will test our hypotheses using novel tools from a multidisciplinary team of investigators in 3 specific aims in two murine models of cardiac injury (ischemia-reperfusion and dilated cardiomyopathy). We will test whether following cardiac injury, satellite glial cell activation within stellate ganglia exacerbates neuronal and cardiac remodeling (structural and functional) to promote LV dysfunction and VT/VF (Aim 1). We will investigate the mechanisms by which cardiac injury activates SGCs in stellate ganglia after injury (Aim 2). Finally, we will determine whether targeting glial Gq-GPCR Ca2+ signaling or Cx43-mediated glia-neuron/glial- glial communication mitigates adverse remodeling and arrhythmogenesis following cardiac injury (Aim 3). The results of this proposal will 1) indicate whether and how satellite glial cell activation contributes to sympathetic imbalance after cardiac injury; and 2) determine whether targeting satellite glial cell activation offers therapeutic potential in chronic cardiac injury.