TY - JOUR
T1 - Characterization of a Novel Function-Blocking Antibody Targeted Against the Platelet P2Y1 Receptor
AU - Karim, Zubair A.
AU - Vemana, Hari Priya
AU - Alshbool, Fatima Z.
AU - Lin, Olivia A.
AU - Alshehri, Abdullah M.
AU - Javaherizadeh, Payam
AU - Espinosa, Enma V.Paez
AU - Khasawneh, Fadi T.
N1 - Publisher Copyright:
© 2015 American Heart Association, Inc.
PY - 2015/3/1
Y1 - 2015/3/1
N2 - Objective-Platelet hyperactivity is associated with vascular disease and contributes to the genesis of thrombotic disorders. ADP plays an important role in platelet activation and activates platelets through 2 G-protein-coupled receptors, the Gq-coupled P2Y1 receptor (P2Y1R), and the Gi-coupled P2Y12 receptor. Although the involvement of the P2Y1R in thrombogenesis is well established, there are no antagonists that are currently available for clinical use. Approach and Results-Our goal is to determine whether a novel antibody targeting the ligand-binding domain, ie, second extracellular loop (EL2) of the P2Y1R (EL2Ab) could inhibit platelet function and protect against thrombogenesis. Our results revealed that the EL2Ab does indeed inhibit ADP-induced platelet aggregation, in a dose-dependent manner. Furthermore, EL2Ab was found to inhibit integrin GPIIb-IIIa activation, dense and α granule secretion, and phosphatidylserine exposure. These inhibitory effects translated into protection against thrombus formation, as evident by a prolonged time for occlusion in a FeCl3-induced thrombosis model, but this was accompanied by a prolonged tail bleeding time. We also observed a dose-dependent displacement of the radiolabeled P2Y1R antagonist [3H]MRS2500 from its ligand-binding site by EL2Ab. Conclusions-Collectively, our findings demonstrate that EL2Ab binds to and exhibits P2Y1R-dependent function-blocking activity in the context of platelets. These results add further evidence for a role of the P2Y1R in thrombosis and validate the concept that targeting it is a relevant alternative or complement to current antiplatelet strategies.
AB - Objective-Platelet hyperactivity is associated with vascular disease and contributes to the genesis of thrombotic disorders. ADP plays an important role in platelet activation and activates platelets through 2 G-protein-coupled receptors, the Gq-coupled P2Y1 receptor (P2Y1R), and the Gi-coupled P2Y12 receptor. Although the involvement of the P2Y1R in thrombogenesis is well established, there are no antagonists that are currently available for clinical use. Approach and Results-Our goal is to determine whether a novel antibody targeting the ligand-binding domain, ie, second extracellular loop (EL2) of the P2Y1R (EL2Ab) could inhibit platelet function and protect against thrombogenesis. Our results revealed that the EL2Ab does indeed inhibit ADP-induced platelet aggregation, in a dose-dependent manner. Furthermore, EL2Ab was found to inhibit integrin GPIIb-IIIa activation, dense and α granule secretion, and phosphatidylserine exposure. These inhibitory effects translated into protection against thrombus formation, as evident by a prolonged time for occlusion in a FeCl3-induced thrombosis model, but this was accompanied by a prolonged tail bleeding time. We also observed a dose-dependent displacement of the radiolabeled P2Y1R antagonist [3H]MRS2500 from its ligand-binding site by EL2Ab. Conclusions-Collectively, our findings demonstrate that EL2Ab binds to and exhibits P2Y1R-dependent function-blocking activity in the context of platelets. These results add further evidence for a role of the P2Y1R in thrombosis and validate the concept that targeting it is a relevant alternative or complement to current antiplatelet strategies.
KW - P2Y receptor antagonists
KW - antiplatelet agents
KW - antithrombotic agents
KW - blood platelets
KW - platelet inhibitors
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U2 - 10.1161/ATVBAHA.114.304509
DO - 10.1161/ATVBAHA.114.304509
M3 - Article
C2 - 25593131
AN - SCOPUS:84920885098
SN - 1079-5642
VL - 35
SP - 637
EP - 644
JO - Arteriosclerosis, thrombosis, and vascular biology
JF - Arteriosclerosis, thrombosis, and vascular biology
IS - 3
ER -