SARS-CoV-2 spike protein potentiates platelet aggregation via upregulating integrin αIIbβ3 outside-in signaling pathway, 2024, Wang et al.

SARS-CoV-2 spike protein potentiates platelet aggregation via upregulating integrin αIIbβ3 outside-in signaling pathway
Wang, Ruijie; Tian, Zezhong; Zhu, Meiyan; Zhang, Bingying; Li, Yanzhang; Zheng, Yiqi; Mao, Yuheng; Zhao, Yimin; Yang, Yan

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.

Link | PDF (Journal of Thrombosis and Thrombolysis)

 

See also —

Nonredundant Roles of Platelet Glycoprotein VI and Integrin αIIbβ3 in Fibrin-Mediated Microthrombus Formation (2021)
Gina Perrella; Jingnan Huang; Isabella Provenzale; Frauke Swieringa; Floor C.J.I. Heubel-Moenen; Richard W. Farndale; Mark Roest; Paola E.J. van der Meijden; Mark Thomas; Robert A.S. Ariëns; Martine Jandrot-Perrus; Steve P. Watson; Johan W.M. Heemskerk

OBJECTIVES
Fibrin is considered to strengthen thrombus formation via integrin αIIbβ3, but recent findings indicate that fibrin can also act as ligand for platelet glycoprotein VI.

APPROACH AND RESULTS
To investigate the thrombus-forming potential of fibrin and the roles of platelet receptors herein, we generated a range of immobilized fibrin surfaces, some of which were cross-linked with factor XIIIa and contained VWF-BP (von Willebrand factor-binding peptide). Multicolor microfluidics assays with whole-blood flowed at high shear rate (1000 s−1) indicated that the fibrin surfaces, regardless of the presence of factor XIIIa or VWF-BP, supported platelet adhesion and activation (P-selectin expression), but only microthrombi were formed consisting of bilayers of platelets. Fibrinogen surfaces produced similar microthrombi.

Markedly, tiggering of coagulation with tissue factor or blocking of thrombin no more than moderately affected the fibrin-induced microthrombus formation. Absence of αIIbβ3 in Glanzmann thrombasthenia annulled platelet adhesion. Blocking of glycoprotein VI with Fab 9O12 substantially, but incompletely reduced platelet secretion, Ca2+ signaling and aggregation, while inhibition of Syk further reduced these responses. In platelet suspension, glycoprotein VI blockage or Syk inhibition prevented fibrin-induced platelet aggregation. Microthrombi on fibrin surfaces triggered only minimal thrombin generation, in spite of thrombin binding to the fibrin fibers.

CONCLUSIONS
Together, these results indicate that fibrin fibers, regardless of their way of formation, act as a consolidating surface in microthrombus formation via nonredundant roles of platelet glycoprotein VI and integrin αIIbβ3 through signaling via Syk and low-level Ca2+ rises.

Link | PDF (Arteriosclerosis, Thrombosis, and Vascular Biology) [Open Access]