Inhibition of HO-1 alleviates cardiac fibrosis by improving ferroptosis-mediated aberrant autophagy.

Cardiac fibrosis is a major pathological feature of cardiovascular diseases and a key driver of ventricular remodeling and heart failure, yet effective therapeutic strategies remain limited due to incomplete mechanistic understanding. Heme oxygenase-1 (HO-1), a key redox-regulating enzyme, has recently been implicated in cardiac injury. However, its role in cardiac fibrosis, particularly through the regulation of ferroptosis, remains poorly understood. This study systematically investigated the effects of HO-1-mediated ferroptosis on the progression of cardiac fibrosis. Myocardial infarction was induced by ligation of the left anterior descending coronary artery, and cardiac fibroblasts were stimulated with transforming growth factor-β1 (TGF-β1) to induce fibrosis. Ferroptosis was markedly activated, accompanied by increased ferrous iron (Fe2+) accumulation, enhanced reactive oxygen species (ROS) generation, and elevated levels of lipid peroxidation. Inhibition of ferroptosis significantly alleviated fibrotic responses and improved cardiac function. Mechanistically, ferroptosis suppression restored autophagic flux by correcting lysosomal abnormalities and normalizing LC3B and p62 accumulation. Furthermore, HO-1 was markedly upregulated in fibrotic conditions, promoting ferroptosis and myocardial fibrosis. Activation of HO-1 induced myocardial fibrosis by triggering ferroptosis-associated autophagic dysfunction, whereas HO-1 inhibition mitigated ferroptotic injury, restored autophagic homeostasis, and attenuated fibrosis. Blocking autophagy abolished the protective effects of HO-1 suppression, demonstrating that the antifibrotic role of HO-1-mediated ferroptosis is dependent on autophagic activity. These findings reveal a novel mechanism by which HO-1-mediated ferroptosis impairs autophagic homeostasis to drive cardiac fibrosis, highlighting HO-1 inhibition as a potential therapeutic strategy for attenuating cardiac fibrosis.