Angiotensin II-driven coronary vasculopathy and pressure-overload myocardial remodeling represent distinct vascular...

Chronic activation of the renin-angiotensin-aldosterone system (RAAS) promotes pathological remodeling of both myocardium and coronary arteries, yet the mechanisms that distinguish myocardial from vascular remodeling remain poorly defined. This study dissected the relative contributions of hemodynamic versus neurohumoral stress to cardiac remodeling, with emphasis on coronary vasculopathy and vascular smooth muscle cell (VSMC) plasticity.

Three murine models were used: transverse aortic constriction (TAC), angiotensin II (AngII) plus phenylephrine (AngII/PE), and high-dose angiotensin II (HD-AngII). Hemodynamics were assessed by catheterization at early and late time points. Histological and immunostaining analyses quantified interstitial and perivascular remodeling including cardiomyocyte hypertrophy, interstitial and perivascular fibrosis, VSMC phenotype transitions, proliferation and quiescence markers, and neointimal and elastic lamina remodeling.

After 28 days, all models exhibited diastolic dysfunction and myocardial fibrosis. Systolic pressure averaged ∼130 mmHg in both AngII models versus ∼200 mmHg in TAC. Despite lower pressure, myocardial fibrosis was greater in AngII/PE and HD AngII models. While TAC induced uniform cardiomyocyte hypertrophy, hypertrophy in AngII models localized near fibrotic and perivascular regions. Increasing AngII dosage shifted remodeling from predominantly myocardial to predominantly vascular phenotypes, accompanied by VSMC dedifferentiation, proliferation, centripetal migration across the internal elastic lamina, neointima formation, elastic lamina disruption, and increased circulating desmosine, consistent with elastin degradation. AKT signaling was selectively increased in coronary VSMCs during this vasculopathic remodeling. Lineage-tracing analyses showed that Ang II-driven coronary neointima formation occurs beneath an intact endothelial monolayer and is composed predominantly of VSMC-derived cells, highlighting a VSMC-centric vasculopathy distinct from classic endothelium-initiated vascular remodeling.

Hemodynamic pressure overload and AngII-dominant neurohumoral stress drive distinct cardiac remodeling phenotypes: TAC primarily elicits uniform myocardial hypertrophy and interstitial fibrosis, whereas chronic AngII exposure preferentially promotes a VSMC-centric coronary vasculopathy with perivascular fibrosis and elastic lamina injury at lower pressure load. These complementary models help distinguish pressure-dependent versus AngII-mediated vascular mechanisms and provide a platform to develop targeted therapies for coronary vasculopathy and AngII-driven vascular disease.