Cardiomyocyte-derived ACE2/Ang-(1–7) axis mediates DIZE-induced inhibition of TGF-β signaling to attenuate cardiac fibrosis following myocardial infarction

Cardiac fibrosis represents a critical pathological determinant of poor prognosis in coronary artery disease (CAD). Pharmacological activation of the angiotensin-Converting enzyme 2/angiotensin-(1-7) (ACE2/Ang-(1-7)) axis is a promising anti-fibrotic approach for cardiac fibrosis, a condition that currently lacks effective therapies. Diminazene aceturate (DIZE) is recognized as an ACE2 agonist with anti‑fibrotic activity, the molecular mechanism of which has not been fully elucidated. This study demonstrates that the anti-fibrotic effects of DIZE are exerted via a cardiomyocyte-mediated paracrine mechanism, rather than through direct action on fibroblasts. Using a cardiomyocyte-fibroblast co-culture system and transcriptomic analysis, we found that ACE2 activated by DIZE on cardiomyocytes enhances the conversion of Ang II to Ang-(1-7), which subsequently suppresses the pro-fibrotic transforming growth factor beta (TGF-β) signaling in adjacent fibroblasts. This effect was partially abrogated by the Ang-(1-7) antagonist A779, confirming Ang-(1-7) as a key paracrine mediator. To exploit this mechanism in vivo, a collagen-binding, low-intensity focused ultrasound (LIFU)-responsive nanoplatform (CNA35-GDP) was developed for specific DIZE delivery. In a rat model of myocardial infarction, LIFU-triggered DIZE release from CNA35-GDP was found to significantly improve cardiac function and attenuate fibrosis. These therapeutic benefits were accompanied by restoration of the ACE2/Ang-(1-7) axis and suppression of TGF-β signaling, thereby validating the proposed mechanism. Collectively, activation of cardiomyocyte-derived ACE2 by DIZE inhibits collagen production in fibroblasts through paracrine Ang-(1-7) and downstream suppression of TGF‑β signaling.