Antimicrobial Peptide Cathelicidin-BF Inhibits Platelet Aggregation by Blocking Protease-Activated Receptor 4

Cathelicidin-BF (BF-30), a peptide isolated from the snake venom of Bungarus fasciatus , exhibits multiple biological functions, including antimicrobial, anticancer and anti-inflammatory. However, the effect of BF-30 on platelet and thrombus formation was reported rarely. In this study, we investigated the antiplatelet and antithrombotic effects of BF-30 and its underlying mechanism. Our results showed that BF-30 potently inhibited thrombin-induced platelet aggregation, and further specifically blocked protease-activated receptor 4 (PAR4). It also reduced P-selectin expression, Akt Ser473 phosphorylation and platelet spreading on fibrinogen. Furthermore, BF-30 exhibited potent inhibitory activity on thrombus formation in vivo: it decreased death of mice with acute pulmonary thrombosis and attenuated thrombosis weight in arterio-venous shunt model. Additionally, a tail cutting bleeding time assay revealed that BF-30 did not prolong bleeding time in mice at efficient dosage. Taken together, BF-30 is a PAR4 antagonist, and inhibits thrombus formation without obvious bleeding risk in vivo. We believe that this study may provide a source for the development of PAR4 antagonist for the treatment of thrombotic disorders.