From Inflammation to Innovation: Harnessing Neutrophil Pathways to Combat Arrhythmogenic Cardiomyopathy - PROJECT SUMMARY Arrhythmogenic cardiomyopathy (ACM) is an inherited heart disease and a leading cause of sudden cardiac death. ACM is plagued by arrhythmias, cardiac dysfunction, and myocardial inflammation; phenotypes recently shown to be driven, in part, by chronic immune signaling. Our lab utilizes a mouse model of ACM (Dsg2mut/mut), that recapitulates key phenotypes observed in patients with ACM. Importantly, cardiac dysfunction and arrhythmias precedes overt myocardial injury. Recently, our lab demonstrated ACM cardiomyocytes release numerous cytokines, chemokines and DAMPs (Chelko et al., JCI [2024] & STM [2021]), which act to recruit pro-inflammatory CCR2+ macrophages; resulting in extensive myocardial cell death, inflammation, and fibrosis. This remodeling leads to cardiac dysfunction, arrhythmias, and increased mortality. Almost certainly, immune signaling occurs prior to disease onset and overt cardiac remodeling in ACM. Neutrophils are among the first cells to participate in the immune response, such as the formation of neutrophil extracellular traps (NETs) and neutrophil degranulation. In this proposal, we aim to investigate the role of two neutrophil-specific inflammatory proteins: peptidyl arginine deiminase-4 (PAD4) and myeloperoxidase (MPO). Specifically, PAD4- dependent NET formation and neutrophil-mediated MPO release prior to disease onset and throughout disease progression in Dsg2mut/mut mice. Our prior published works and preliminary data presented here demonstrate MPO and PAD4 are both upregulated in adolescent Dsg2mut/mut mice before phenotypes are present. We hypothesize both PAD4 and MPO contribute to a cardiac inflammatory environment, triggering immune cell chemotaxis, myocyte cell death, fibrotic remodeling, and cardiac dysfunction. To directly test this hypothesis, (Aim 1) we will test the efficacy of the MPO inhibitor, PF1355, in Dsg2mut/mut mice; and (Aim 2) genetically ablate Pad4 in Dsg2mut/mut mice. Both approaches will elucidate whether neutrophil-mediated immune signaling drives ACM pathogenesis. Outcomes from our work will determine if targeting neutrophil-mediated pathways could mitigate disease progression, providing a new therapeutic strategy in combating immune-mediated myocardial injury in affected individuals. This project will be completed at Florida State University College of Medicine (FSUCOM) under the guidance of Drs. Stephen Chelko (Mentor) and Yi Ren (Co-mentor). The training plan has been formulated to facilitate the development of both technical and conceptual proficiencies to successfully execute the proposed aims. Additionally, the training plan incorporates essential elements to transition the applicant into an independent scientific investigator. The Chelko and Ren Laboratories, the Department of Biomedical Sciences at FSUCOM, and the FSU campus – writ large – provides a rich scientific environment and outstanding graduate training for the applicant.
