S100A4 triggeres the pyroptosis of vsmcs: association with mitochondrial damage, impaired mitophagy, and Ca2+ dysregulation.

BACKGROUND: Atherosclerotic occlusive disease of the lower extremities (ASO-LE) is associated with high rates of disability and mortality, and even after surgery, the rate of long-term lumen patency remains low. Vascular smooth muscle cells (VSMCs) are key players in atherosclerosis. The aim of this study was to investigate the action of S100 calcium-binding protein A4 (S100A4) in regulating VSMCs in ASO-LE. RESULTS: The overexpression of S100A4 in the vessel wall of ASO-LE is detected, and the expression of markers of pyroptosis is high. S100A4 causes mitochondrial damage in VSMCs, increases the intracellular ROS and MDA levels, and decreases the level of SOD, which result in oxidative stress. Moreover, S100A4 disrupts the mitophagy process, manifested by inhibited LC3-II conversion and reduced PE levels, suggesting that the lipidation step of LC3 may be disrupted. These promot the accumulation of a large amount of damaged mitochondria with insufficient clearance and activate intracellular AIM2 inflammatory vesicles, which mediate the occurrence of pyroptosis. We also find that the functions of S100A4 may be associated with disturbances in intracellular calcium ion (Ca2+) signaling, both S100A4 transcription inhibitor (niclosamide) and calcium channel blockers can inhibit the above damaging effects. CONCLUSIONS: S100A4 plays a crucial role in the progression of ASO-LE by driving mitochondrial damage and impairing mitophagy in vascular smooth muscle cells, and it is a potential existing strategies for blocking chronic inflammation that may be used to treat lower extremity atherosclerotic occlusion. CLINICAL TRIAL NUMBER: Not applicable.