Cigarette tar mediates macrophage ferroptosis in atherosclerosis through the hepcidin/FPN/SLC7A11 signaling pathway

Despite the known promotional effects of cigarette smoking on progression of atherosclerosis (AS), tar as the most dominant toxic component in cigarette smoking has been little studied. Understanding the potential role and mechanisms of tar in AS may be a prerequisite for future reductions in cardiovascular morbidity and mortality. Male ApoE^-/- mice were fed with high-fat diet and injected intraperitoneally with cigarette tar (40 mg/kg/day) for 16 weeks. The results showed that cigarette tar significantly promoted the formation of lipid-rich plaques with larger necrotic cores and less fibrous, and caused severe iron overload and lipid peroxidation in AS lesions. Moreover, tar significantly upregulated the expression of hepcidin and downregulated FPN and SLC7A11 of macrophages in AS plaques. Ferroptosis inhibitor (FER-1 and DFO) treatment, hepcidin-knockdown or SLC7A11-overexpression reversed above changes, thereby delaying the progression of atherosclerosis. In vitro, the use of FER-1, DFO, si-hepcidin, and ov-SLC7A11 increased cell viability and inhibited iron accumulation, lipid peroxidation and GSH depletion in tar treated macrophages. These interventions also inhibited the tar induced upregulation of hepcidin, and increased the expression of FPN, SLC7A11, and GPX4. Furthermore, NF-κB inhibitor reversed the regulatory effect of tar on hepcidin/FPN/SLC7A11 axis, and then inhibiting macrophage ferroptosis. These findings indicated that cigarette tar promotes atherosclerosis progression by inducing macrophage ferroptosis via NF-κB-activated hepcidin/FPN/SLC7A11 pathway.