Stable and functional regulatory T cell attenuates fibrotic remodeling in heart failure.

Introduction: Heart failure involves myocardial fibrosis and impaired cardiac function. The transverse aortic constriction (TAC) model in mice replicates pressure overload-induced fibrosis. Immune-mediated inflammation, particularly through T lymphocytes and macrophages, plays a pivotal role in the progression of fibrosis. In vitro-induced regulatory T cells (Tregs) are limited by Foxp3 instability. To address this, stable and functional in vitro induced Tregs (S/F-iTregs) have been developed under CD28-deprived conditions, exhibiting sustained Foxp3 expression and epigenetic stability. We aimed to evaluate the therapeutic efficacy of intravenously administered S/F-iTregs in a murine TAC model of heart failure. Methods: S/F-iTregs were generated from CD4 Results: S/F-iTreg administration significantly improved left ventricular function and reduced myocardial fibrosis compared to those in controls. PKH26-labeled S/F-iTregs were detected within the cardiac tissue, confirming in vivo migration. RNA sequencing revealed downregulation of inflammation- and fibrosis-related pathways, including tumor necrosis factor-alpha/nuclear factor kappa-light-chain-enhancer of activated B cell, platelet-derived growth factor, transforming growth factor-beta signaling, and modulation of macrophage-related transcriptional programs. Conclusions: Systemic administration of S/F-iTregs attenuates cardiac fibrosis and preserves cardiac function in pressure overload-induced heart failure. These findings support S/F-iTreg-based immunomodulation as a potential approach to limit adverse fibrotic cardiac remodeling.