THBS1 Promotes Vascular Smooth Muscle Cells Proliferation and Inhibits Phenotypic Transformation to Reduce Intracranial Aneurysm Rupture

Abstract

Background: Intracranial aneurysm (IA) rupture poses a significant threat to health. Thrombospondin 1 (THBS1) has been implicated in the prevention of IA rupture. This study aimed to elucidate the mechanistic role of THBS1 in IA rupture. Methods: An IA model was induced in Sprague-Dawley (SD) rats by ligating the right common carotid artery, left external carotid artery, and left pterygopalatine artery. Vascular smooth muscle cells (VSMCs) were isolated from SD rats and stimulated with tumor necrosis factor-alpha (TNF-α; 20 ng/μL) to induce a proinflammatory phenotype. Cerebral vessel morphology was assessed using hematoxylin-eosin (HE) staining. Levels of alpha-smooth muscle actin (α-SMA), smooth muscle 22 alpha (SM22α), matrix metalloproteinase 2 (MMP2), THBS1, thrombospondin receptor CD36, and transforming growth factor-beta 1 (TGF-β1) were evaluated via western blot. The transfection efficiency of THBS1 plasmid and short hairpin CD36 (ShCD36) was determined using quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability, proliferation, and apoptosis were assessed using the cell counting kit-8 (CCK-8), 5-ethynyl-2′-deoxyuridine (EdU) assay, and Hoechst assay, respectively. Results: IA model rats exhibited reduced levels of α-SMA, SM22α, THBS1, and CD36, accompanied by increased MMP2 levels (p < 0.01). THBS1 overexpression reversed the effects of TNF-α on VSMCs viability, proliferation, apoptosis, and the expression levels of TGF-β1, α-SMA, SM22α, MMP2, CD36, and THBS1 (p < 0.05). Silencing CD36 reversed the effects of THBS1 overexpression on TNF-α-treated VSMCs (p < 0.05). Conclusions: Our findings demonstrate that THBS1 promotes VSMC proliferation and inhibits phenotypic transformation to reduce IA rupture.