Identification of a VWF peptide antagonist that blocks platelet adhesion under high shear conditions by selectively inhibiting the VWF-collagen interaction.

Background: Because the collagen-VWF-GPIb/IX/V axis plays an important role in thrombus formation, it represents a promising target for development of new antithrombotic agents.

Objectives: We used phage display to identify potential small peptides that interfere with the VWF-collagen binding and might serve as lead products for the development of possible oral antithrombotic compounds.

Methods: A random linear heptamer peptide library was used to select VWF-binding peptides.

Results: We identified a phage clone, displaying the YDPWTPS sequence, further referred to as L7-phage, that bound to VWF in a specific and a dose-dependent manner. This L7-phage specifically inhibited the VWF-collagen interaction under both static and flow conditions. Epitope mapping using deletion mutants of VWF revealed that the L7-phage does not bind to the known collagen-binding A3 domain within VWF, but to the more carboxyterminal situated C domain. This inhibition was not due to steric hindrance of the A3 domain-collagen interaction by the L7-phage. Indeed, a tetrabranched multi-antigen peptide (MAP) presenting four copies of the peptide, but not the scrambled MAP, also inhibited VWF-collagen interaction under conditions of high shear stress at a concentration of 148 nmol L(-1).

Conclusions: Based on these results, we conclude that we have identified the first peptide antagonist that binds to the VWF C domain and by this specifically inhibits the VWF binding to collagen, suppressing platelet adhesion and aggregation under high shear conditions. As a consequence, this peptide and its future derivates are potentially interesting antithrombotic agents.