SARS-CoV-2 spike protein activates NOX2-p66SHC axis via inhibiting SLAMF8 to promote thrombogenesis

COVID-19 associated coagulation abnormalities and thrombosis are life-threatening complications after SARS-CoV-2 infection. However, the underlying mechanisms are unclear. Here, we found that SARS-CoV-2 spike (S) protein induced excessive reactive oxygen species (ROS) production, disrupting mitochondrial dynamics and causing endothelial cells damage, thereby promoting thrombogenesis. Mechanistically, the S protein inhibited the expression of signaling lymphocytic activation molecule family 8 (SLAMF8) to induce an upregulation of NADPH oxidase 2 (NOX2) expression and p66SHC phosphorylation. This activation of NOX2-p66SHC axis resulted in a persistent elevation of ROS and mitochondrial dynamics disorder, ultimately leading to endothelial cells injury. SARS-CoV-2 infection also promoted the transformation of endothelial cells into a prothrombotic phenotype by inhibiting the expression of SLAMF8. Furthermore, the single-cell sequencing analysis revealed a negative correlation between SLAMF8 expression and thrombotic activity of endothelial cells in COVID-19 patients. Notably, the overexpression of SLAMF8 reversed the S protein-mediated increase in blood flow obstruction and platelet aggregation observed in mice with ferric chloride-induced thrombosis. These findings suggest a distinct mechanism of the S protein in the pathogenesis of SARS-CoV-2-associated thrombosis, providing novel perspectives and strategies for the prevention, management and treatment of thrombotic complications in individuals with COVID-19 or long COVID.