2. Academic Validation
  3. Protease activated receptors and glycoprotein VI cooperatively drive the platelet component in thromboelastography

Protease activated receptors and glycoprotein VI cooperatively drive the platelet component in thromboelastography

  • J Thromb Haemost. 2023 Apr 15;S1538-7836(23)00322-7. doi: 10.1016/j.jtha.2023.04.008.
Tanvi Rudran 1,  Silvio Antoniak 2,  Matthew J Flick 2,  Mark H Ginsberg 3,  Alisa S Wolberg 2,  Wolfgang Bergmeier 4,  Robert H Lee 5
Affiliations

Affiliations

  • 1 Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC.
  • 2 UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC,; Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC.
  • 3 Department of Medicine, University of California, San Diego, La Jolla, CA.
  • 4 Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC,; UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC.
  • 5 Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC,; UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC,. Electronic address: robert_lee@med.unc.edu.
PMID: 37068592 DOI: 10.1016/j.jtha.2023.04.008
Abstract

Background: Thromboelastography (TEG) is used for real-time determination of hemostatic status in patients with acute risk of bleeding. Thrombin is thought to drive clotting in TEG through generation of polymerized fibrin and activation of platelets through PARs. However, the specific role of platelet agonist receptors and signaling in TEG has not been reported.

Objectives: Here we investigated the specific receptors and signaling pathways required for platelet function in TEG using genetic and pharmacological inhibition of platelet proteins in mouse and human blood samples.

Methods: Clotting parameters (R, α, MA) were determined in recalcified, kaolin-triggered citrated blood samples using a TEG 5000 analyzer.

Results: We confirmed the requirement of platelets, platelet contraction, and αIIbβ3 Integrin function for normal α-angle (α) and maximal amplitude (MA). Loss of the Integrin adaptor Talin1 in megakaryocytes/platelets (Talin1mKO) also reduced α and MA, but only minimal defects were observed in samples from mice lacking Rap1 GTPase signaling. PAR4mKO samples showed impaired α but normal MA. However, impaired TEG traces similar to platelet-depleted samples were observed with samples from PAR4mKO mice depleted of GPVI on platelets or with addition of a Syk Inhibitor. We reproduced these results in human blood with combined inhibition of PAR1, PAR4, and Syk.

Conclusions: Our results demonstrate that standard TEG is not sensitive to platelet signaling pathways critical for Integrin inside-out activation and platelet hemostatic function. Furthermore, we provide first evidence that PARs and GPVI play redundant roles in platelet-mediated clot contraction in TEG.

Keywords

Thromboelastography; bleeding; blood platelets; fibrin; protease-activated receptor.

Figures
Products