Amplified anticoagulant activity of tissue factor-targeted thrombomodulin
| Autor: | Yi-Xin Wang, Baby Martin-McNulty, Brent Larsen, Serene Alexander, Kirk Mclean, Jon Vincelette, David R. Light, Chenliang Wu |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Male
Time Factors Recombinant Fusion Proteins Thrombomodulin Thromboplastin Rats Sprague-Dawley Tissue factor In vivo Thromboembolism medicine Animals Humans Potency Blood Coagulation Prothrombin time Dose-Response Relationship Drug medicine.diagnostic_test Chemistry Anticoagulants Biological activity Hematology Molecular biology Rats Coagulation Immunology Dimerization |
| Zdroj: | Thrombosis and Haemostasis. 96:317-324 |
| ISSN: | 2567-689X 0340-6245 |
| Popis: | SummaryTissue factor (TF) exposure isa potent pro-thrombotic trigger that initiates activation of the coagulation cascade, while thrombomodulin (TM) is a potent anticoagulant protein that limits the extent of activation. Both TF neutralizing antibodies and soluble TM (sTM) are effective anticoagulants. We have developed a novel anticoagulant fusion protein, Ab(TF)-TM, by fusing a TF-neutralizing single-chain antibody, Ab(TF), to an active fragment of TM. Ab(TF)-TM is a novel anticoagulant targeting to sites of TF exposure with a dual mechanism of action. The Ab(TF) portion of the molecule inhibits TF/factor VIIa mediated activation of FIX and FX, and the TM portion of the molecule acts as a cofactor for activation of protein C. In-vitro coagulation assays show that Ab(TF)-TM more potently inhibits TF-initiated coagulation (prothrombin time) than can its individual components, Ab(TF) (20-fold) and sTM (80-fold) alone, or in combination (10-fold). In contrast, the potency of Ab(TF)-TM in the activated partial thromboplastin and thrombin clotting time assays was similar to sTM alone. Ina rat model of disseminated intravascular coagulation (DIC), intravenous injection of a human TF-containing thromboplastin reagent (0.5 ml/kg) resulted in an immediate death in ∼60% of the animals and a clinical score of ∼2.5. Pre-injection of Ab(TF)-TM or Ab(TF) and sTM, given alone or in combination, showed dose-dependent efficacy. At a dose of 0.7 nmol/kg, Ab(TF)-TM completely prevented death and reduced clinical scores by 79%, while neither Ab(TF) nor sTM, given alone or in combination, showed significant therapeutic effects. Calculated effective doses that reduced mortality by 50% relative to that in the control group (ED50, nmol/kg) were 0.21 for Ab(TF)-TM, 3.2 for an equimolar mixture of Ab(TF) and sTM, 4.3 for sTM and 20 for Ab(TF). Thus, Ab(TF)-TM presented 10– to 100-fold enhancement of the anticoagulant potency, relative to the ED50 in Ab(TF) and sTM given either alone or in combination, in a rat DIC model. |
| Databáze: | OpenAIRE |
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