SARS-CoV-2 infection promotes lung thrombosis by inducing integrinβ3 expression in vascular endothelial cells

Severe COVID-19 shows a high incidence of pulmonary thrombosis. However, the molecular mechanism underlying this phenomenon remains unclear. We have performed RNA sequencing of isolated endothelial cells (ECs) from infected mid-aged and young mice. Compared to young mice, Integrinβ3 (ITGB3) expression levels were higher in ECs of mid-aged mice which showed thrombosis in lungs. SARS-CoV-2 exposure increased the number of adhered platelets on the EC monolayer in vitro. Knockdown of ITGB3 in ECs decreased platelet adhesion to them. Among the molecules known as SARS-CoV-2 receptors, Kringle-containing transmembrane protein 1 contributed to ITGB3 upregulation in ECs by SARS-CoV-2. Histological analysis showed that ITGB3-positive blood vessels were frequently detected not only in infected-mid-aged mouse lungs but also in COVID-19-affected human autopsy lungs. This study suggests that the induction of ITGB3 expression in ECs is one of the mechanisms of thrombosis in severe COVID-19 pneumonia.