The Role of Gasdermin-D/Interleukin-1 Nexus in Atrial Arrhythmogenesis

PROJECT SUMMARY Atrial fibrillation (AF) is the most frequent arrhythmia. Enhanced activation of ‘NACHT, LRR and PYD domains- containing protein 3’ (NLRP3) inflammasome plays a causal role in promoting proarrhythmic events associated with AF development. Activation of NLRP3 inflammasome produces two major effectors: interleukin (IL)-1b and cleaved (active) N-terminal gasdermin-D (GSDMDNT). The precise functions of IL-1b and GSDMDNT in cardiomyocytes and atrial arrhythmogenesis are largely unknown. Our preliminary data revealed that cardiomyocyte-specific knockdown of IL-1b receptor type-1 (IL-1R1) attenuates susceptibility to AF of mice with cardiomyocyte NLRP3 gain-of-function. Meanwhile, atrial specific overexpression of GSDMDNT in mice (aGSDMDNT) also creates an arrhythmic substrate for AF development. Because the main function of GSDMDNT is to form plasma membrane pores allowing the cell release of IL-1b and IL-1b protein is upregulated in aGSDMDNT mice, we hypothesized that this GSDMDNT/IL-1b nexus creates a substrate for AF by promoting a feedforward loop of NLRP3-inflammasome activation. Using mouse and human atrial systems we propose to 1) elucidate the role of IL-1b signaling in cardiomyocytes and atrial arrhythmogenesis, 2) establish the causative role and the functions of cardiomyocyte GSDMDNT in atrial arrhythmogenesis, and 3) establish and validate GSDMDNT/IL-1b nexus as the driver of a feedforward loop of NLRP3-inflammasome activation in atrial arrhythmogenesis. The outcome of these studies will provide a proof-of-concept for atrial specific targeting of IL- 1b signaling in AF patients and uncover novel and unique functions of IL-1b and GSDMDNT in atrial cardiomyocytes and their specific contributions to AF development.