Abstract 15027: Senescence-Associated Pathway Activation in Cardiac Fibroblasts in Dilated Cardiomyopathy

Abstract

Introduction: Cardiac fibrosis is a pathologic driver in heart failure (HF) and aging is a major risk factor for HF. Persistence of activated myofibroblasts is a key feature of pathological fibrosis. In an aging model of lung fibrosis, senescent myofibroblasts exhibit apoptosis-resistance, which contributes to the sustained fibrotic response. Therapeutic targeting of NADPH oxidase-4 (NOX4), a primary source of reactive oxygen species (ROS) in myofibroblasts, can inhibit fibrosis development and reverse established lung fibrosis. We sought to understand the role of cellular senescence and NOX4 activation and persistence of cardiac fibroblasts with progression to HF. Methods and Results: Mice carrying a mutation in the phospholamban gene (PLNR9C) develop progressive dilated cardiomyopathy (DCM), extensive cardiac fibrosis and HF. Using the Langendorff hanging heart method and flow cytometry, cardiac fibroblasts were isolated and studied for markers of cellular senescence. Cardiac fibroblasts from PLNR9C mice with DCM display a senescent phenotype, with significantly elevated levels of the senescence markers p16 (2.1-fold, p<0.01, n=3, Figure) and beta-galactosidase (1.7-fold, p<0.01, n=3), along with significantly increased ROS production (Amplex Red assay 2.5-fold, p<0.01, n=3), as compared to fibroblasts from age-matched wild type (WT) mice. Nox4 is upregulated in cardiac fibroblasts from PLNR9C mice (mRNA 8.5-fold, n=4, p<0.01; protein 5.0-fold, p<0.01, n=4, Figure) with HF but not in young PLNR9C mice prior to development of DCM. Conclusions: These data reveal a premature aging phenotype in cardiac fibroblasts from mice with genetic DCM and identify NOX4 as a putative mediator of fibroblast activation and persistence.