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

• DOI: 10.1161/atvbaha.120.314301
• Publication Date: 2020-07-23T09:01:01Z
• 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. Gard...; Robert K. Andrews; Mikhail Panteleev; Christian Gachet; Martine Jandrot-P...; Pierre H. Mangin
• Keywords: Blood Platelets; Microscopy, Video; Platelet Aggregation; [SDV]Life Sciences [q-bio]; Thrombin; 610; Fibrinogen; Thrombosis; Platelet Membrane Glycoproteins; Afibrinogenemia; Models, Biological; Immunoglobulin Fab Fragments; Kinetics; Fibrinolytic Agents; Humans; Computer Simulation; Stress, Mechanical; Platelet Aggregation Inhibitors; Signal Transduction

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.