title: A novel antibody targeting the ligand binding domain of the thromboxane A₂ receptor exhibits antithrombotic properties in vivo.
abstract: In efforts to define new targets for antithrombotic purposes, there is interest in utilizing antibodies targeting ligand binding domains of platelet receptors. To this end, we have recently shown that an antibody (designated C-EL2Ab), which targets the C-terminus of the 2nd extracellular loop (C-EL2) of the thromboxane A(2) receptor (TPR), selectively blocks TPR-mediated platelet aggregation, under both in vitro and ex vivo experimental conditions. In the current studies we sought to determine whether C-EL2Ab exhibits in vivo antithrombotic activity, by employing a carotid artery injury thrombosis model. It was found that mice treated with C-EL2Ab, exhibited a significant increase in time for occlusion, when compared to controls such as normal rabbit IgG, or an antibody which targets a region separate from the ligand binding site (i.e., EL1). We next examined the effect of C-EL2Ab on hemostasis, and found no increase in tail bleeding times in C-EL2Ab treated mice, compared to the aforementioned controls. Collectively, these results clearly demonstrate that C-EL2Ab has anti-platelet/anti-thrombotic effects, and is devoid of increased bleeding risk. Moreover, the identification of a functionally active TPR sequence should significantly aid molecular modeling study predictions for organic derivatives which possess in vivo activity.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA 91766, USA.
authors.forename: John P
authors.initials: JP
authors.lastname: Murad
authors.forename: Enma Veronica Paez
authors.initials: EV
authors.lastname: Espinosa
authors.forename: Harold J
authors.initials: HJ
authors.lastname: Ting
authors.forename: Diane
authors.initials: D
authors.lastname: McClure
authors.forename: Fadi T
authors.initials: FT
authors.lastname: Khasawneh
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology* / Q000627:therapeutic use; D004195:Disease Models, Animal; D005343:Fibrinolytic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D008024:Ligands; D051379:Mice; D008810:Mice, Inbred C57BL; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D017434:Protein Structure, Tertiary; D044244:Receptors, Thromboxane A2, Prostaglandin H2 / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000276:immunology; D013927:Thrombosis / Q000188:drug therapy*
chemical_list: D000911:Antibodies, Monoclonal; D005343:Fibrinolytic Agents; D008024:Ligands; D010975:Platelet Aggregation Inhibitors; D044244:Receptors, Thromboxane A2, Prostaglandin H2