HIF-1α depletion regulates autophagy to improve arteriosclerosis obliterans of the lower extremities via the TSP-1/CD47 axis.

AIMS: Hypoxia-inducible factor 1α (HIF-1α) is overexpressed in vascular smooth muscle cells (VSMCs) and Arteriosclerosis obliterans (ASO) of the lower extremities, one of the peripheral arterial diseases (PAD), but its role in ASO autophagy remains unclear. This study aims to explore the effects of HIF-1α and autophagy on ASO.

MATERIALS AND METHODS: Hypoxic VSMCs and VSMC-macrophage co-culture models were treated with lificiguat (YC-1) or small Interfering RNA (siRNA) to deplete HIF-1α. Observing cell proliferation, apoptosis, migration, and invasion was used cell counting kit-8, flow cytometry, 5-Ethynyl-2'-deoxyuridine staining, wound-healing and Transwell assays. Observing autophagy was used Transmission electron microscopy and western blot (WB). ASO rats treated with YC-1, autophagy activator rapamycin (RAPA), or autophagy inhibitor 3-Methyladenine (3-MA) were underwent Oil red O, Hematoxylin and Eosin staining, immunohistochemistry, enzyme-linked immunosorbent assay and WB.

KEY FINDINGS: HIF-1α depletion decreased cell viability, proliferation, and autophagic flux. Silencing HIF-1α inhibited migration and invasion, the thrombospodin-1 (TSP-1)/cluster of differentiation (CD) 47 pathway, Beclin-1 and microtubule-associated proteins 1 A/1B light chain 3-II levels and increased apoptosis and sequestosome 1. RAPA or overexpressing TSP-1/CD47 antagonized these effects. Silencing HIF-1α also promoted mTOR phosphorylation, macrophage-induced apoptosis, suppressing the TSP-1/CD47 pathway and overexpressing TSP-1/CD47 reversed these effects. In ASO rat femoral arteries, HIF-1α depletion attenuated lipid deposition and autophagy-related protein expression, while increasing the TSP-1/CD47 pathway activity, apoptosis-related protein levels, serum inflammation markers, and cell adhesion molecule concentration.

SIGNIFICANCE: HIF-1α/TSP-1/CD47 axis is critical for VSMC activation and ASO progression. This research highlighted HIF-1α and autophagy as potential therapeutic targets for ASO.