Abstract Number: PB0879
Meeting: ISTH 2021 Congress
Background: Plasma von Willebrand factor (VWF) circulates in a compact form unable to bind platelets. At high arterial shear stress or when immobilized to collagen, VWF undergoes a conformational change to expose the VWF A1 domain, which allows binding to platelet glycoprotein (GP)Ibα present in the GPIb-V-IX complex resulting in shear-dependent thrombus formation. Interference with the VWF A1 domain-GPIbα interaction is of therapeutic interest for many cardiovascular diseases, e.g. in immune thrombotic thrombocytopenia purpura (iTTP).
Aims: For this purpose, we aimed to design and test novel peptide-based drugs.
Methods: Cyclic peptides were designed in silico, mimicking the region in GPIbα that binds to the exposed VWF A1 domain or to the A1 domain complexed with botrocetin. Peptides with lowest binding free energy (BFE) were chemically synthesized: a monocyclic mono-ORbIT peptide and a bicyclic bi-ORbIT peptide. Flow cytometry and citrated whole blood high shear stress microfluidic assays were used to assess the peptides inhibitory effect.
Results: Both peptides interfere with ristocetin- and botrocetin-induced VWF binding to GPIb-V-IX as assessed by flow cytometry. Anti-VWF A1 domain antibody, CLB-RAg35, was used as a positive control. In whole-blood microfluidics assays at high shear stress, CLB-RAg35 suppressed stable platelet adhesion and markedly abrogated the formation of thrombi. Both peptides mimicked these phenotypic changes, albeit to a lesser extent than CLB-RAg35. Using mono-ORbIT as a template for an improved generation of peptides resulted in design and development of opt-mono-ORbIT, which showed higher inhibitory activity than the previous peptides.
Conclusions: Our data prove that a structure-based design of peptides can result in physiologically relevant peptide-based inhibitors, even for convoluted complexes such as GPIbα-VWF A1. To counteract bleeding side effects observed in iTTP treatment with caplacizumab, controlled interference of VWF-GPIb complex formation may provide an alternative way of suppression of pathological thrombus formation at high shear stress.
To cite this abstract in AMA style:Hrdinova J, Fernández DI, Ercig B, Tullemans BM, Suylen DP, Agten SM, Jurk K, Hackeng TM, Vanhoorelbeke K, Voorberg J, Reutelingsperger CP, Wichapong K, Heemskerk JWM, Nicolaes GAF. Structure-based Design of Cyclic Glycoprotein Ibα-derived Peptides Affecting Platelet Interaction with von Willebrand Factor under Shear Conditions [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/structure-based-design-of-cyclic-glycoprotein-ib%ce%b1-derived-peptides-affecting-platelet-interaction-with-von-willebrand-factor-under-shear-conditions/. Accessed December 7, 2021.
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