A novel inhibitor of plasminogen activator inhibitor-1 production, T-686: direct effects on the fibrinolytic system

Abstract

Objective: This study evaluates the efficacy of a novel inhibitor of plasminogen activator inhibitor-1 (PAI-1), (3E, 4E)-3-benzylidene-4-(3,4,5-trimethoxy-benzylidene)-pyrrolidine-2,5-dione (T-686), on PAI-1 production in human umbilical vein endothelial cells (HUVEC) in vitro and in an experimental hypofibrinolytic rat model induced by lipopolysaccharide (LPS) in vivo. Methods: PAI-1 and tissue-type plasminogen activator (t-PA) antigens in the conditioned medium from cultured human endothelial cells were determined by enzyme-linked immunosorbent assays. A hypofibrinolytic model was made by intravenous injection of LPS to rats. T-686 was orally administered to rats for 8 consecutive days prior to LPS injection. The activities of PAI-1 and t-PA in plasma were assessed spectrophotometrically using a chromogenic substrate. Results: T-686 inhibited the LPS-induced increase in PAI-1 production time- and concentration-dependently without affecting elaboration of t-PA in cultured HUVEC. Injection of LPS to rats induced an increase in plasma PAI-1 activity, while the plasma activity of t-PA was decreased. Treatment with T-686 dose-dependently attenuated the augmented PAI-1 activity and partially prevented the reduction of t-PA activity in the LPS-treated rats. Conclusion: T-686 is an orally-active inhibitor of PAI-1 production and can thus potentiate the fibrinolytic system.