SARS-CoV-2 binds platelet ACE2 to enhance thrombosis in COVID-19

J Hematol Oncol. 2020 Sep 4;13(1):120. doi: 10.1186/s13045-020-00954-7.

Abstract

Background: Critically ill patients diagnosed with COVID-19 may develop a pro-thrombotic state that places them at a dramatically increased lethal risk. Although platelet activation is critical for thrombosis and is responsible for the thrombotic events and cardiovascular complications, the role of platelets in the pathogenesis of COVID-19 remains unclear.

Methods: Using platelets from healthy volunteers, non-COVID-19 and COVID-19 patients, as well as wild-type and hACE2 transgenic mice, we evaluated the changes in platelet and coagulation parameters in COVID-19 patients. We investigated ACE2 expression and direct effect of SARS-CoV-2 virus on platelets by RT-PCR, flow cytometry, Western blot, immunofluorescence, and platelet functional studies in vitro, FeCl3-induced thrombus formation in vivo, and thrombus formation under flow conditions ex vivo.

Results: We demonstrated that COVID-19 patients present with increased mean platelet volume (MPV) and platelet hyperactivity, which correlated with a decrease in overall platelet count. Detectable SARS-CoV-2 RNA in the blood stream was associated with platelet hyperactivity in critically ill patients. Platelets expressed ACE2, a host cell receptor for SARS-CoV-2, and TMPRSS2, a serine protease for Spike protein priming. SARS-CoV-2 and its Spike protein directly enhanced platelet activation such as platelet aggregation, PAC-1 binding, CD62P expression, α granule secretion, dense granule release, platelet spreading, and clot retraction in vitro, and thereby Spike protein enhanced thrombosis formation in wild-type mice transfused with hACE2 transgenic platelets, but this was not observed in animals transfused with wild-type platelets in vivo. Further, we provided evidence suggesting that the MAPK pathway, downstream of ACE2, mediates the potentiating role of SARS-CoV-2 on platelet activation, and that platelet ACE2 expression decreases following SARS-COV-2 stimulation. SARS-CoV-2 and its Spike protein directly stimulated platelets to facilitate the release of coagulation factors, the secretion of inflammatory factors, and the formation of leukocyte-platelet aggregates. Recombinant human ACE2 protein and anti-Spike monoclonal antibody could inhibit SARS-CoV-2 Spike protein-induced platelet activation.

Conclusions: Our findings uncovered a novel function of SARS-CoV-2 on platelet activation via binding of Spike to ACE2. SARS-CoV-2-induced platelet activation may participate in thrombus formation and inflammatory responses in COVID-19 patients.

Keywords: ACE2; COVID-19; Platelet activation; TMPRSS2; Thrombosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Angiotensin-Converting Enzyme 2
  • Animals
  • Betacoronavirus / genetics
  • Betacoronavirus / metabolism*
  • Blood Platelets / metabolism*
  • COVID-19
  • Caco-2 Cells
  • Coronavirus Infections / metabolism*
  • Coronavirus Infections / virology
  • Female
  • HeLa Cells
  • Humans
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Middle Aged
  • PC-3 Cells
  • Pandemics
  • Peptidyl-Dipeptidase A / genetics
  • Peptidyl-Dipeptidase A / metabolism*
  • Platelet Aggregation / immunology
  • Platelet Count
  • Pneumonia, Viral / metabolism*
  • Pneumonia, Viral / virology
  • RNA, Viral / blood
  • SARS-CoV-2
  • Serine Endopeptidases / metabolism
  • Spike Glycoprotein, Coronavirus / metabolism
  • Thrombosis / metabolism*
  • Thrombosis / virology

Substances

  • RNA, Viral
  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2
  • Peptidyl-Dipeptidase A
  • ACE2 protein, human
  • Ace2 protein, mouse
  • Angiotensin-Converting Enzyme 2
  • Serine Endopeptidases
  • TMPRSS2 protein, human