Thrombospondin 1 Aggravates the Progression of Heart Failure with Preserved Ejection Fraction by Inhibiting Mitophagy

Heart failure with preserved ejection fraction (HFpEF) accounts for over half of all heart failure cases, yet its underlying mechanisms remain poorly understood. Recent evidence suggests that mitochondrial dysfunction and impaired mitophagy play pivotal roles in HFpEF pathogenesis. Thrombospondin 1 (Thbs1), a matricellular protein, is implicated in cardiovascular remodeling, but its role in HFpEF has not been elucidated. Here, we demonstrate that Thbs1 expression is significantly elevated in the myocardium of HFpEF mice and that Thbs1 exacerbates cardiac dysfunction by suppressing mitophagy. Using a well-established "two-hit" mouse model (high-fat diet and L-NAME), we show that AAV9-mediated knockdown of Thbs1 alleviates diastolic dysfunction, cardiac fibrosis, and myocardial inflammation. RNA sequencing and proteomics analyses revealed enrichment of the PI3K/Akt/mTOR pathway in HFpEF hearts, which was attenuated by Thbs1 silencing. Mechanistically, Thbs1 knockdown restored autophagic flux, promoted mitochondrial clearance, and improved mitochondrial homeostasis in cardiomyocytes. These findings establish Thbs1 as a key regulator of impaired mitophagy in HFpEF and suggest that targeting Thbs1 may provide a therapeutic avenue for treating this complex syndrome. Overall design: Male C57BL/6 mice were fed a high-fat diet (HFD; 60% kcal from fat, D12492, Research Diets) and received L-NAME (0.5 g/L, Sigma-Aldrich) in drinking water (pH 7.4) for 12 consecutive weeks. Control mice were fed standard chow and given regular drinking water. After 12 weeks, cardiac function, body weight, and blood pressure were assessed.