Inhibition of coronary thrombosis and local inflammation by a noncarbohydrate selectin inhibitor

Wafic Said Molecular and Gene Therapy Research Laboratory and Cullen Cardiovascular Research Laboratory, Texas Heart Institute, St. Luke's Episcopal Hospital; Texas Biotechnology Corporation; Institute of Molecular Medicine; and Department of Internal Medicine, University of Texas-Houston Medical School, Houston, Texas 77030 We tested the hypothesis that selectin inhibition with blocking antibodies or a small-molecular-weight inhibitor of L-, P-, and E-selectin, methoxybenzoylpropionic acid (MBPA), prevents thrombus formation in a canine coronary Folts' model. Cyclic flow variations (CFVs) were induced by crush injury and constriction of the left anterior descending coronary artery in dogs. Systemic infusion of antibodies to P- and L-selectin abolished CFVs, respectively, in 50% and 17% of treated dogs [ P = not significant (NS)]. The combination of P- and L-selectin antibodies suppressed CFVs in 60% of treated dogs ( P = NS). In contrast, systemic selectin blockade by intravenous infusion or local adventitial application of MBPA markedly reduced CFVs and, in addition, reduced myocardial myeloperoxidase (MPO) activity. We conclude that inhibition of L-, P-, and E-selectin binding by a small-molecular-weight, noncarbohydrate compound markedly reduces arterial thrombosis, whereas systemic administration of antibodies to L- and P-selectin fail to reproduce this antithrombotic effect. These results underscore the role of selectins in the pathogenesis of arterial thrombosis under high shear stress and suggest that inhibition of P- and L- selectin may not suffice to prevent thrombus formation in this model. The role of E-selectin in thrombus formation in this model awaits further testing. selectins; platelet inhibition; P-selectin; antithrombotics