ABSTRACT
Enhancement of fibrinolysis constitutes a promising approach to treat thrombotic diseases. Venous thrombosis and thromboembolism risks are associated with increased plasma levels of TAFI (Thrombin Activatable Fibrinolysis Inhibitor) as well as its active form TAFIa. A new TAFIa inhibitor, namely S62798 has been identified. Its ability to enhance fibrinolysis was investigated both in vitro and in vivo in a mouse model of pulmonary thromboembolism, as well as its effect on bleeding. S62798 is a highly selective human, mouse and rat TAFIa inhibitor (IC50 = 11; 270; 178 nmol/L, respectively). It accelerates lysis of a human clot in vitro, evaluated by thromboelastometry (EC50 = 27 nmol/L). In a rat tail bleeding model, no effect of S62798 treatment was observed up to 20 mg/kg. Enhancement of endogenous fibrinolysis by S62798 was investigated in a mouse model of Tissue Factor-induced pulmonary thromboembolism. Intravenous administration of S62798 decreased pulmonary fibrin clots with a minimal effective dose of 0.03 mg/kg. Finally, effect of S62798 in combination with heparin was evaluated. When treatment of heparin was done in a curative setting, no effect was observed whereas a significantly decreased pulmonary fibrin deposition was observed in response to S62798 alone or in combination with heparin. This study demonstrates that S62798 is a potent TAFIa inhibitor with minimal risk of bleeding. In vivo, curative S62798 intravenous treatment, alone or associated with heparin, accelerated clot lysis by potentiating endogenous fibrinolysis and thus decreased pulmonary fibrin clots. S62798 is expected to be a therapeutic option for pulmonary embolism patients on top of anticoagulants.
Subject(s)
Carboxypeptidase B2 , Enzyme Inhibitors/pharmacology , Pulmonary Embolism , Animals , Carboxypeptidase B2/antagonists & inhibitors , Disease Models, Animal , Fibrin Clot Lysis Time , Fibrinolysis , Humans , Mice , Pulmonary Embolism/drug therapy , RatsABSTRACT
Selective and potent inhibitors of activated thrombin activatable fibrinolysis inhibitor (TAFIa) have the potential to increase endogenous and therapeutic fibrinolysis and to behave like profibrinolytic agents without the risk of major hemorrhage, since they do not interfere either with platelet activation or with coagulation during blood hemostasis. Therefore, TAFIa inhibitors could be used in at-risk patients for the treatment, prevention, and secondary prevention of stroke, venous thrombosis, and pulmonary embolisms. In this paper, we describe the design, the structure-activity relationship (SAR), and the synthesis of novel, potent, and selective phosphinanes and azaphosphinanes as TAFIa inhibitors. Several highly active azaphosphinanes display attractive properties suitable for further in vivo efficacy studies in thrombosis models.
Subject(s)
Aza Compounds/pharmacology , Carboxypeptidase B2/antagonists & inhibitors , Cyclic P-Oxides/pharmacology , Fibrinolytic Agents/pharmacology , Phosphinic Acids/pharmacology , Protease Inhibitors/pharmacology , Animals , Aza Compounds/chemical synthesis , Aza Compounds/metabolism , Carboxypeptidase B2/metabolism , Catalytic Domain , Cyclic P-Oxides/chemical synthesis , Cyclic P-Oxides/metabolism , Fibrinolysis/drug effects , Fibrinolytic Agents/chemical synthesis , Fibrinolytic Agents/metabolism , Humans , Male , Molecular Docking Simulation , Molecular Structure , Phosphinic Acids/chemical synthesis , Phosphinic Acids/metabolism , Protease Inhibitors/chemical synthesis , Protease Inhibitors/metabolism , Protein Binding , Rats, Sprague-Dawley , Structure-Activity RelationshipABSTRACT
The role of von Willebrand factor (VWF) in thrombosis involves its binding to a number of ligands. To investigate the relative importance of these particular interactions in the thrombosis process, we have introduced mutations into murine VWF (mVWF) cDNA inhibiting VWF binding to glycoprotein (Gp) Ib, GPIIbIIIa, or to fibrillar collagen. These VWF mutants were expressed in VWF-deficient mice (VWF(-/-)) by using an hydrodynamic injection approach, and the mice were studied in the ferric chloride-induced injury model. Expression of the collagen and the GPIIbIIIa VWF-binding mutants in VWF(-/-) mice resulted in delayed thrombus growth and significantly increased vessel occlusion times compared with mice expressing wild-type (WT) mVWF (30 +/- 3 minutes and 38 +/- 4 minutes for the collagen and GPIIbIIIa mutants, respectively, vs 19 +/- 3 minutes for WT mVWF). Interestingly, these mutants were able to correct bleeding time as efficiently as WT mVWF. In contrast, VWF(-/-) mice expressing the GPIb binding mutant failed to restore thrombus formation and were bleeding for as long as they were observed, confirming the critical importance of the VWF-GPIb interaction. Our observations suggest that targeting the VWF-collagen or VWF-GPIIbIIIa interactions could be an interesting alternative for new antithrombotic strategies.
Subject(s)
Collagen/metabolism , Genetic Variation , Platelet Glycoprotein GPIIb-IIIa Complex/metabolism , Platelet Glycoprotein GPIb-IX Complex/metabolism , Thrombosis/etiology , von Willebrand Factor/genetics , Animals , Hemorrhage/etiology , Mice , Mice, Knockout , Mutagenesis, Site-Directed , Mutant Proteins/metabolism , Protein Binding/genetics , Protein Binding/physiology , von Willebrand Factor/metabolismABSTRACT
The synthesis and activity of novel benzothiophene derivatives are described. In the t-Pa-induced fibrin clot lysis assay, several compounds inhibit the formation of the tPa-PAI-1 complex with submicromolar IC(50). This class of compounds potentially represents a new generation of antithrombotic-fibrinolytic agents.
