BS-452758-4 COMBINED GENE THERAPY APPROACH TARGETS PARASYMPATHETIC SIGNALING AND OXIDATIVE STRESS TO ATTENUATE PERSISTENT ATRIAL FIBRILLATION DEVELOPMENT IN A CANINE MODEL

Abstract

Atrial fibrillation (AF) is the most common arrhythmia, a major risk factor for stroke and is associated with substantial morbidity and mortality. Unfortunately, current pharmacological and interventional treatment approaches are suboptimal. Parasympathetic nervous system (PNS) activity upregulation and oxidative stress (OS), mainly generated by NADPH oxidase 2 (NOX2), have been shown as key players in AF induction and maintenance. A deeper understanding of these molecular mechanisms underlying AF and their interplay will be instrumental to the development of new, mechanism-targeted therapies for AF. To evaluate whether combined gene therapy can inhibit parasympathetic signaling (Gαi and Gαo - GiGo) and reactive oxygen species generation and attenuate AF development and maintenance in a large animal chronic AF model. Combination of plasmids expressing NOX2 (main source of OS in atrial cardiomyocytes) short hairpin RNA and GiGo inhibitory peptides (GiGo_ct) was injected in the canine (n=4) atria followed by electroporation to facilitate gene delivery. Rapid atrial pacing (RAP) was performed for up to 8 weeks. Residual AF was evaluated at terminal EP study. Plasmids expression was evaluated with polymerase chain reaction (PCR). Controls developed persistent AF (≥8 hours) after a median of 14 days. Combined (NOX2+GiGo) gene therapy attenuated development of persistent AF and significantly reduced AF burden by 32% (Panel A). AF at the terminal experiment displayed increased organization in gene therapy animals (panel B), with one animal spontaneously converting to sinus rhythm. PCR analysis showed NOX2 downregulation and evidence of GiGo_ct expression upon >2 months since gene injection. Targeting both parasympathetic nerve signaling and OS significantly attenuated AF development, which proves their important mechanistic role. Gene-based, selective parasympathetic signaling inhibition by GiGo_ct and oxidative stress attenuation by NADPH oxidase 2 downregulation prevents initiation and maintenance AF. Future optimization of gene therapy and developing combined approaches to target several mechanisms of AF pathophysiology simultaneously may lead to novel treatments for AF.