Abstract Body: Introduction: Cardiac fibrosis is a central determinant of adverse outcomes in heart failure, yet therapies that directly target fibrogenic remodeling remain limited. We previously identified the Src family kinase (SFK) inhibitor PD as a candidate anti-fibrotic compound through a phenotypic screening approach; however, its therapeutic efficacy and mechanism in heart failure remain unknown. We hypothesized that PD exerts therapeutic benefit in pressure overload-induced heart failure.
Methods: Mice with transverse aortic constriction (TAC) were treated with PD or vehicle. We performed multimodal analyses, including single-nucleus RNA sequencing (snRNA-seq) of heart tissue. Complementary in vitro studies were conducted in primary mouse and human cardiac fibroblasts, and human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) under oxidative stress.
Results: PD attenuated cardiac remodeling and fibrosis after TAC. snRNA-seq indicated a transcriptional reprogramming of cardiac fibroblasts from activated states toward a quiescent-like phenotype. Mechanistically, PD reduced actin polymerization and suppressed nuclear accumulation of myocardin related transcription factor A (MRTF-A) and serum response factor (SRF)-associated regulatory programs, supporting inhibition of SFK-linked mechanotransduction pathways that sustain fibroblast activation. Consistently, PD promoted deactivation-associated responses in cardiac fibroblasts derived from patients with advanced heart failure. Concomitantly, cardiomyocyte snRNA-seq showed enrichment of mitochondrial metabolism-related gene programs with PD treatment. In hPSC-CMs under oxidative stress, PD increased AMPKα Thr172 phosphorylation and enhanced maximal mitochondrial respiratory capacity.
Conclusion: We demonstrate that PD attenuates cardiac remodeling and fibrosis through dual mechanisms: restraining fibroblast activation and enhancing mitochondrial metabolism in cardiomyocytes (Image 1). These findings nominate PD as a potential therapeutic candidate for heart failure.