HDL from patients with type 2 diabetes impairs endothelial function by inducing ferroptosis via nuclear receptor...

Endothelial function is impaired in patients with diabetes. Normal high-density lipoprotein (nHDL) protects endothelial function; however, HDL from patients with diabetes becomes dysfunctional (dHDL) and impairs endothelial function. Ferroptosis is a novel iron-dependent form of cell death driven by the accumulation of lipid peroxidation. Nevertheless, it remains unclear whether dHDL impairs endothelial function by inducing ferroptosis. Human umbilical vein endothelial cells (HUVECs) were treated with nHDL or dHDL; consequently, intracellular levels of ferrous ion, lipid peroxidation, superoxide anions (O₂^•-), and nitric oxide (NO) were detected. The expressions of ferritin heavy polypeptide 1 (FTH1), glutathione peroxidase 4 (GPX4), nuclear receptor coactivator 4 (NCOA4), and sphingosine 1-phosphate receptor 1 (S1P1) were measured, while endothelial cell (EC) tube formation was studied. In addition, the mitochondrial membrane potential (MMP), mitophagy, and ferritinophagy were determined. Moreover, vasodilation in C57BL/6 and diabetic db/db mice was examined. dHDL increased ferrous ion levels, lipid peroxidation, O₂^•- production, mitophagy, ferritinophagy, and NCOA4 expression; however, it inhibited FTH1, GPX4, and S1P1 expression, NO generation, and EC tube formation. dHDL decreased MMP and impaired endothelium-dependent vasodilation. These effects of dHDL were reversed by ferrostatin-1 or S1P1 overexpression. The expressions of FTH1, GPX4, and S1P1 decreased, whereas NCOA4 expression increased in diabetic db/db mice compared to wild-type mice. Taken together, dHDL impairs endothelial function by inducing mitochondrial damage and EC ferroptosis through the S1P1-NCOA4 axis. Our findings provide a novel mechanism by which dHDL impairs endothelial function and offer a therapeutic target for diabetic vascular dysfunction.