Pharmacological Blockade of Glycoprotein VI Promotes Thrombus Disaggregation in the Absence of Thrombin.

Abstract

OBJECTIVE:

Atherothrombosis occurs upon rupture of an atherosclerotic plaque and leads to the formation of a mural thrombus. Computational fluid dynamics and numerical models indicated that the mechanical stress applied to a thrombus increases dramatically as a thrombus grows, and that strong inter-platelet interactions are essential to maintain its stability. We investigated whether GPVI (glycoprotein VI)-mediated platelet activation helps to maintain thrombus stability by using real-time video-microscopy. Approach and Results: We showed that GPVI blockade with 2 distinct Fab fragments promoted efficient disaggregation of human thrombi preformed on collagen or on human atherosclerotic plaque material in the absence of thrombin. ACT017-induced disaggregation was achieved under arterial blood flow conditions, and its effect increased with wall shear rate. GPVI regulated platelet activation within a growing thrombus as evidenced by the loss in thrombus contraction when GPVI was blocked, and the absence of the disaggregating effect of an anti-GPVI agent when the thrombi were fully activated with soluble agonists. The GPVI-dependent thrombus stabilizing effect was further supported by the fact that inhibition of any of the 4 key immunoreceptor tyrosine-based motif signalling molecules, src-kinases, Syk, PI3Kβ, or phospholipase C, resulted in kinetics of thrombus disaggregation similar to ACT017. The absence of ACT017-induced disaggregation of thrombi from 2 afibrinogenemic patients suggests that the role of GPVI requires interaction with fibrinogen. Finally, platelet disaggregation of fibrin-rich thrombi was also promoted by ACT017 in combination with r-tPA (recombinant tissue plasminogen activator).

CONCLUSIONS:

This work identifies an unrecognized role for GPVI in maintaining thrombus stability and suggests that targeting GPVI could dissolve platelet aggregates with a poor fibrin content.

• Authors: Muhammad Usman Ahmed, Valeria Kaneva, Stéphane Loyau, Dmitry Nechipurenko, Nicolas Receveur, Marion Le Bris, Emily Janus-Bell, Mélusine Didelot, Antoine Rauch, Sophie Susen, Nabil Chakfé, François Lanza, Elizabeth E Gardiner, Robert K Andrews, Mikhail Panteleev, Christian Gachet, Martine Jandrot-Perrus, Pierre H Mangin
• Journal: Arteriosclerosis, thrombosis, and vascular biology (Arterioscler Thromb Vasc Biol) Vol. 40 Issue 9 Pg. 2127-2142 (09 2020) ISSN: 1524-4636 [Electronic] United States
• PMID: 32698684 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Video-Audio Media)

Chemical References

• Fibrinolytic Agents
• Immunoglobulin Fab Fragments
• Platelet Aggregation Inhibitors
• Platelet Membrane Glycoproteins
• platelet membrane glycoprotein VI
• Fibrinogen
• Thrombin

Topics

• Afibrinogenemia (blood, diagnosis, genetics)
• Blood Platelets (drug effects, metabolism)
• Computer Simulation
• Fibrinogen (genetics, metabolism)
• Fibrinolytic Agents (pharmacology)
• Humans
• Immunoglobulin Fab Fragments (pharmacology)
• Kinetics
• Microscopy, Video
• Models, Biological
• Platelet Aggregation (drug effects)
• Platelet Aggregation Inhibitors (pharmacology)
• Platelet Membrane Glycoproteins (antagonists & inhibitors, metabolism)
• Signal Transduction
• Stress, Mechanical
• Thrombin (metabolism)
• Thrombosis (blood, diagnosis, drug therapy, genetics)