SARS-CoV-2 spike protein potentiates platelet aggregation via upregulating integrin αIIbβ3 outside-in signaling pathway

Platelet hyperreactivity is one of the crucial causes of coagulative disorders in patients with COVID-19. Few studies have indicated that integrin αIIbβ3 may be a potential target for spike protein binding to platelets. This study aims to investigate whether spike protein interacts with platelet integrin αIIbβ3 and upregulates outside-in signaling to potentiate platelet aggregation. In this study, we found that spike protein significantly potentiated platelet aggregation induced by different agonists and platelet spreading in vitro . Mechanism studies revealed that spike protein upregulated the outside-in signaling, such as increased thrombin-induced phosphorylation of β3, c-Src. Moreover, using tirofiban to inhibit spike protein binding to αIIbβ3 or using PP2 to block outside-in signaling, we found that the potentiating effect of spike protein on platelet aggregation was abolished. These results demonstrate that SARS-CoV-2 spike protein directly enhances platelet aggregation via integrin αIIbβ3 outside-in signaling, and suggest a potential target for platelet hyperreactivity in patients with COVID-19. Graphical abstract SARS-CoV-2 spike protein interacts with platelet integrin αIIbβ3, upregulating the outside-in signaling pathway and subsequently potentiating platelet aggregation. Highlights • Spike protein potentiates platelet aggregation and upregulates αIIbβ3 outside-in signaling. • Spike protein interacts with integrin αIIbβ3 to potentiate platelet aggregation. • Blocking outside-in signaling abolishes the effect of spike protein on platelets.