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Published on: June 5, 2019
Minimal Collagen-Binding Epitope of Glycoprotein VI in Human and Mouse Platelets
Chao Han1,2, Pengxuan Ren3, Medina Mamtimin1,2
1Walther-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilian-University, 80336 Munich, Germany.
Abstract:
Glycoprotein VI (GPVI) is a platelet-specific receptor for collagen and fibrin, regulating important platelet functions such as platelet adhesion and thrombus growth. Although the blockade of GPVI function is widely recognized as a potent anti-thrombotic approach, there are limited studies focused on site-specific targeting of GPVI. Using computational modeling and bioinformatics, we analyzed collagen- and CRP-binding surfaces of GPVI monomers and dimers, and compared the interacting surfaces with other mammalian GPVI isoforms. We could predict a minimal collagen-binding epitope of GPVI dimer and designed an EA-20 antibody that recognizes a linear epitope of this surface. Using platelets and whole blood samples donated from wild-type and humanized GPVI transgenic mice and also humans, our experimental results show that the EA-20 antibody inhibits platelet adhesion and aggregation in response to collagen and CRP, but not to fibrin. The EA-20 antibody also prevents thrombus formation in whole blood, on the collagen-coated surface, in arterial flow conditions. We also show that EA-20 does not influence GPVI clustering or receptor shedding. Therefore, we propose that blockade of this minimal collagen-binding epitope of GPVI with the EA-20 antibody could represent a new anti-thrombotic approach by inhibiting specific interactions between GPVI and the collagen matrix.
Insights
A novel antibody, EA-20, targets a specific collagen-binding site on Glycoprotein VI (GPVI), a key platelet receptor. This targeted blockade effectively inhibits platelet adhesion and thrombus formation, offering a new anti-thrombotic strategy.
Area of Science:
- Biochemistry
- Immunology
- Hematology
Background:
- Glycoprotein VI (GPVI) is a critical platelet receptor involved in collagen and fibrin binding, regulating platelet adhesion and thrombus formation.
- Targeting GPVI is a promising anti-thrombotic strategy, but site-specific approaches are underexplored.
Purpose of the Study:
- To identify and target a minimal collagen-binding epitope on GPVI using computational and experimental methods.
- To develop a novel antibody for site-specific GPVI blockade and evaluate its anti-thrombotic potential.
Main Methods:
- Computational modeling and bioinformatics to analyze GPVI binding surfaces.
- Design and characterization of the EA-20 antibody targeting a linear GPVI epitope.
- In vitro and in vivo studies using human and animal platelet/blood samples under various conditions.
Main Results:
- Identified a minimal collagen-binding epitope on GPVI dimers and developed the EA-20 antibody against it.
- EA-20 antibody inhibited platelet adhesion and aggregation induced by collagen and CRP, but not fibrin.
- EA-20 prevented thrombus formation in whole blood under arterial flow conditions without affecting GPVI clustering or shedding.
Conclusions:
- Blockade of the minimal collagen-binding epitope of GPVI with the EA-20 antibody is a viable anti-thrombotic approach.
- EA-20 offers a specific mechanism to inhibit GPVI-collagen interactions, potentially reducing thrombosis.
- This site-specific targeting represents a novel therapeutic avenue for thrombotic disorders.
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