Le système fibrinolytique: Activation et inhibition. Ses modifications en cas de CIVD

Abstract

The blood fibrinolytic system comprises an inactive proenzyme, plasminogen, that can be converted to the active enzyme, plasmin. Plasmin degrades fibrin and participates in the extracellular matrix remodelling. This conversion implies two physiological plasminogen activators (PA), the tissue type (t-PA) and the urinary type (u-PA). t-PA mediated plasminogen activation is mainly involved in the dissolution of fibrin in the circulation. u-PA binds to a specific cellular receptor (u-PAR), resulting in enhanced activation of cell bound plasminogen. Inhibition of the fibrinolytic system may occur by specific plasminogen activator inhibitors (PAI), or at the level of plasmin, mainly by α2-antiplasmin. Recently a thrombin activatable fibrinolysis inhibitor (TAFI) has been described. By eliminating carboxyterminal lysine residues from partially degraded fibrin, it could participate to the control of in vivo fibrinolysis. During DIC, fibrinolysis is induced and septic DIC is characterized by a sustained increase in PAI-1 synthesis due to the presence of proinflammatory cytokines, mainly TNFα. © 2002 Éditions scientifiques et médicales Elsevier SAS.