Abstract 13924: Combined Gene Therapy Approach Targets Parasympathetic Signaling and Oxidative Stress to Reverse Pre-Existing Persistent Atrial Fibrillation in a Canine Model

Abstract

Introduction: Atrial fibrillation (AF) is a multifactorial disease, with oxidative stress (NADPH oxidase 2, NOX2) and autonomic remodeling (hyperinnervation and parasympathetic signaling) playing an important role. Disrupting both mechanisms simultaneously with gene-based therapy may allow for reversal of established remodeling in AF. Hypothesis: Gene therapy aimed at attenuation of parasympathetic signaling (Gαi/o inhibitory peptides, GiGo_ct) and prevention of nerve sprouting (nerve growth factor short hairpin RNA, NGF shRNA) combined with reduction of oxidative stress (NOX2 shRNA) can reverse AF in a large animal chronic AF model. Methods: Chronic AF model was created by rapid atrial pacing (RAP) at 600bpm in 5 dogs, followed by gene therapy treatment (Panel A). A combination of NOX2 shRNA and GiGo_ct plasmids with (n=2) or without (n=3) NGF shRNA was injected in both atria followed by electroporation to facilitate gene delivery. Control RAP dogs did not receive gene (n=5) or underwent scrambled gene injection (n=6). AF burden was assessed over time and residual AF was recorded at terminal EP study. NOX2 and NGF knockdown and GiGo_ct expression were evaluated by PCR. Results: After 3.3±1.3 weeks of RAP, all 11 animals reached >80% AF burden. Combined (NOX2+GiGo±NGF) gene therapy significantly reduced AF burden by 66% (p<0.05) compared to scramble controls and by 38% (p<0.05) compared to pre-treatment AF burden (Panel B). Residual AF after the treatment was slower and more organized than in controls (panel C). PCR analysis showed NOX2 and NGF downregulation and evidence of GiGo_ct expression. Conclusions: Gene-based attenuation of autonomic remodeling through inhibition of parasympathetic signaling and nerve sprouting, and reduction of oxidative stress by NOX2 downregulation may be effective at reversing AF. Development of optimized gene therapy to target multiple AF mechanisms simultaneously may lead to more effective treatments for persistent AF.