Structure-Based Cyclic Glycoprotein Ibα-Derived Peptides Interfering with von Willebrand Factor-Binding, Affecting...

Area of Science:

• Biochemistry
• Cardiovascular Biology
• Drug Design

Background:

• Von Willebrand factor (VWF) circulates in an inactive state, but shear stress exposes its A1 domain, enabling platelet binding via glycoprotein Ib-V-IX (GPIbα).
• This VWF-GPIbα interaction is critical in platelet adhesion and thrombus formation, particularly under high shear conditions relevant to cardiovascular disease.
• Targeting this interaction specifically is essential for developing new therapeutic strategies against thrombotic disorders.

Purpose of the Study:

• To design and synthesize novel cyclic peptides that specifically inhibit the interaction between the VWF A1 domain and GPIbα.
• To evaluate the efficacy of these designed peptides in blocking VWF-platelet binding and preventing thrombus formation in vitro and under flow conditions.

Main Methods:

• In silico structure-based design of cyclic peptides targeting the VWF A1 domain and GPIbα binding site.
• Chemical synthesis of selected peptides, including monocyclic (ORbIT) and bicyclic (bi-ORbIT) variants.
• In vitro assays using flow cytometry to assess peptide interference with VWF-GPIbα binding and whole-blood assays to evaluate thrombus formation under high shear stress.

Main Results:

• Two cyclic peptides, ORbIT and bi-ORbIT, were successfully designed and synthesized, showing the lowest binding free energy.
• These peptides demonstrated interference with VWF-GPIbα binding, mimicking the effects of an anti-VWF A1 antibody (CLB-RAg35).
• In flow assays, the peptides inhibited VWF-dependent platelet adhesion and thrombus formation, with an optimized peptide (opt-mono-ORbIT) showing enhanced inhibitory activity.

Conclusions:

• Structure-based peptide design can yield effective inhibitors for complex protein-protein interactions like VWF-GPIbα.
• The developed cyclic peptides represent a promising new class of therapeutic agents for preventing thrombosis by targeting VWF-mediated platelet activation.
• These findings offer a foundation for further development of peptide-based therapeutics for cardiovascular diseases driven by VWF-platelet interactions.