Osteoprotegerin modulates platelet adhesion to von Willebrand factor during release from endothelial cells

N. Wohner, S. Sebastian, V. Muczynski, D. Huskens, B. de Laat, P.G. de Groot*, P.J. Lenting

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

3 Citations (Web of Science)

Abstract

Background Platelet-binding Von Willebrand Factor (VWF) strings assemble upon stimulated secretion from endothelial cells. Objectives To investigate the efficiency of platelet binding to multi-molecular VWF bundles secreted from endothelial cells and to investigate the role of osteoprotegerin, a protein located in Weibel-Palade bodies that interacts with the VWF platelet binding domain. Methods The nanobody VWF/AU-a11 that specifically binds to VWF in its active platelet-binding conformation was used to investigate the conformation of VWF. Results Upon stimulated secretion from endothelial cells, VWF strings were only partially covered with platelets, while a VWD-type 2B mutation or ristocetin enhanced platelet binding by 2-3-fold. Osteoprotegrin, reduces platelet adhesion to VWF by 40% +/- 18% in perfusion assays. siRNA-mediated down-regulation of endothelial osteoprotegerin expression resulted in a 1.8-fold increase in platelet adhesion to VWF strings. Upon viral infection, there is a concordant rise in VWF and osteoprotegerin plasma levels. Unexpectedly, no such increase was observed in plasma of desmopressin-treated hemophilia A-patients. In a mouse model, osteoprotegerin expression was low in liver endothelial cells of vehicle-treated mice, and concanavalin A-treatment increased VWF and osteoprotegerin expression 4- and 40-fold, respectively. This increase was translated in a 30-fold increased osteoprotegerin/VWF ratio in plasma. Conclusions Release of VWF from endothelial cells opens the platelet-binding site, irrespective of the presence of flow. However, not all available platelet-binding sites are being occupied, suggesting some extent of regulation. Part of this regulation involves endothelial proteins that are co-secreted with VWF, like osteoprotegerin. This regulatory mechanism may be of more relevance under inflammatory conditions.
Original languageEnglish
Pages (from-to)755-766
Number of pages12
JournalJournal of Thrombosis and Haemostasis
Volume20
Issue number3
Early online date3 Dec 2021
DOIs
Publication statusPublished - Mar 2022

Keywords

  • blood platelets
  • endothelial cells
  • inflammation
  • osteoprotegerin
  • von Willebrand factor
  • WEIBEL-PALADE BODIES
  • THROMBOTIC THROMBOCYTOPENIC PURPURA
  • IN-VIVO SURVIVAL
  • SECRETION
  • MODEL

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