The kinetics of αIIbβ3 activation determines the size and stability of thrombi in mice: Implications for antiplatelet therapy

Moritz Stolla, Lucia Stefanini, R. Claire Roden, Massiel Chavez, Jessica Hirsch, Teshell Greene, Timothy D. Ouellette, Sean F. Maloney, Scott L. Diamond, Mortimer Poncz, Donna S. Woulfe, Wolfgang Bergmeier

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Abstract

Two major pathways contribute to Rasproximate-1-mediated integrin activation in stimulated platelets. Calcium and dia-cyglycerol-regulated guanine nucleotide exchange factor I (CalDAG-GEFI, Ras-GRP2) mediates the rapid but reversible activation of integrin αIIbβ3, while the adenosine diphosphate receptor P2Y12, the target for antiplatelet drugs like clopidogrel, facilitates delayed but sustained integrin activation. To establish CalDAG-GEFI as a target for antiplatelet therapy, we compared how each pathway contributes to thrombosis and hemostasis in mice. Ex vivo, thrombus formation at arterial or venous shear rates was markedly reduced in CalDAG-GEFI-/- blood, even in the presence of exogenous adenosine diphosphate and thromboxaneA 2. In vivo, thrombosis was virtually abolished in arterioles and arteries of CalDAG-GEFI-/- mice, while small, hemostatically active thrombi formed in venules. Specific deletion of the C1-like domain of CalDAG-GEFI in circulating platelets also led to protection from thrombus formation at arterial flow conditions, while it only marginally increased blood loss in mice. In comparison, thrombi in the micro- and macrovasculature of clopidogrel-treated wild-type mice grew rapidly and frequently embolized but were hemostatically inactive. Together, these data suggest that inhibition of the catalytic or the C1 regulatory domain in CalDAG-GEFI will provide strong protection from atherothrombotic complications while maintaining a better safety profile than P2Y12 inhibitors like clopidogrel.

Original languageEnglish (US)
Pages (from-to)1005-1013
Number of pages9
JournalBlood
Volume117
Issue number3
DOIs
StatePublished - Jan 20 2011

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All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology

Cite this

Stolla, M., Stefanini, L., Roden, R. C., Chavez, M., Hirsch, J., Greene, T., Ouellette, T. D., Maloney, S. F., Diamond, S. L., Poncz, M., Woulfe, D. S., & Bergmeier, W. (2011). The kinetics of αIIbβ3 activation determines the size and stability of thrombi in mice: Implications for antiplatelet therapy. Blood, 117(3), 1005-1013. https://doi.org/10.1182/blood-2010-07-297713