HSPB1 suppresses oxLDL-induced vascular smooth muscle cell ferroptosis by inhibiting DPP4

Atherosclerosis is the major pathological basis of cardiovascular diseases. Vascular smooth muscle cell (VSMC) dysfunction and death induced by oxidized low-density lipoprotein (oxLDL) play a key role in atherosclerosis. Ferroptosis is a novel iron-dependent lipid peroxidation regulated cell death, which is implicated in atherosclerosis. However, whether oxLDL induces VSMC ferroptosis and the specific mechanism is unclear.

To determine the effects of oxLDL on VSMC ferroptosis, LDH activity, MDA and Fe²⁺ content, glutathione peroxidase 4 (GPX4) expression and GPX enzyme activity were assayed. The level of lipid peroxidation was detected by C11 BODIPY fluorescence staining. RT-qPCR and Western blot were used to detect the mRNA and protein expressions of heat shock protein B1 (HSPB1), dipeptidyl peptidase 4 (DPP4) and nuclear factor kappa-B (NF-κB). The siRNAs, plasmids and Val-boropro were utilized to explore the roles of HSPB1/NF-κB/DPP4 in oxLDL-induced VSMC ferroptosis.

oxLDL increased LDH activity, Fe²⁺ content, lipid peroxidation and MDA content in VSMCs, which were inhibited by ferroptosis inhibitors Lip-1 and DFO. Moreover, oxLDL reduced GPX4 protein expression and GPX enzyme activity, indicating that oxLDL induces VSMC ferroptosis. Notably, HSPB1 inhibited oxLDL-induced VSMC ferroptosis by reducing the accumulation of Fe²⁺ and lipid peroxidation and increasing GPX4 expression and activity. In addition, HSPB1 suppressed oxLDL-induced VSMC ferroptosis by inhibiting DPP4 through NF-κB. Furthermore, Val-boropro could rescue oxLDL-induced ferroptosis in VSMCs with HSPB1 knockdown by inhibiting DPP4.

This study reveals for the first time that HSPB1 suppresses oxLDL-induced VSMC ferroptosis by inhibiting DPP4 through NF-κB, providing new strategies for the prevention and treatment of atherosclerosis.