Regulation of the extrinsic pathway system in health and disease: The role of factor VIIa and tissue factor pathway inhibitor

1995 ◽  
Vol 79 (1) ◽  
pp. 1-47 ◽  
Author(s):  
Lars C. Petersen ◽  
Sanne Valentin ◽  
Ulla Hedner
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Factor Viia ◽  
Extrinsic Pathway ◽  
Health And Disease ◽  
Tissue Factor Pathway

scholarly journals Caveolin-1 Enhances Tissue Factor Pathway Inhibitor Exposure and Function on the Cell Surface

2005 ◽  
Vol 280 (23) ◽  
pp. 22308-22317 ◽  
Author(s):  
Cristina Lupu ◽  
Xiaohong Hu ◽  
Florea Lupu
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Factor Viia ◽  
Protease Production ◽  
Extrinsic Pathway ◽  
Caveolin 1 ◽  
Tissue Factor Pathway ◽  
Quaternary Complex ◽  
And Function

Tissue factor pathway inhibitor (TFPI) blocks tissue factor-factor VIIa (TF-FVIIa) activation of factors X and IX through the formation of the TF-FVIIa-FXa-TFPI complex. Most TFPI in vivo associates with caveolae in endothelial cells (EC). The mechanism of this association and the anticoagulant role of caveolar TFPI are not yet known. Here we show that expression of caveolin-1 (Cav-1) in 293 cells keeps TFPI exposed on the plasmalemma surface, decreases the membrane lateral mobility of TFPI, and increases the TFPI-dependent inhibition of TF-FVIIa. Caveolae-associated TFPI supports the co-localization of the quaternary complex with caveolae. To investigate the significance of these observations for EC we used RNA interference to deplete the cells of Cav-1. Functional assays and fluorescence microscopy revealed that the inhibitory properties of TFPI were diminished in EC lacking Cav-1, apparently through deficient assembly of the quaternary complex. These findings demonstrate that caveolae regulate the inhibition by cell-bound TFPI of the active protease production by the extrinsic pathway of coagulation.

Aptamer ARC19499 mediates a procoagulant hemostatic effect by inhibiting tissue factor pathway inhibitor

Blood ◽  
2011 ◽  
Vol 117 (20) ◽  
pp. 5514-5522 ◽  
Author(s):  
Emily K. Waters ◽  
Ryan M. Genga ◽  
Michael C. Schwartz ◽  
Jennifer A. Nelson ◽  
Robert G. Schaub ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Hemophilia A ◽  
Factor Viia ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Factor Ix ◽  
Intrinsic Pathway ◽  
Extrinsic Pathway ◽  
Tissue Factor Pathway

Abstract Hemophilia A and B are caused by deficiencies in coagulation factor VIII (FVIII) and factor IX, respectively, resulting in deficient blood coagulation via the intrinsic pathway. The extrinsic coagulation pathway, mediated by factor VIIa and tissue factor (TF), remains intact but is negatively regulated by tissue factor pathway inhibitor (TFPI), which inhibits both factor VIIa and its product, factor Xa. This inhibition limits clot initiation via the extrinsic pathway, whereas factor deficiency in hemophilia limits clot propagation via the intrinsic pathway. ARC19499 is an aptamer that inhibits TFPI, thereby enabling clot initiation and propagation via the extrinsic pathway. The core aptamer binds tightly and specifically to TFPI. ARC19499 blocks TFPI inhibition of both factor Xa and the TF/factor VIIa complex. ARC19499 corrects thrombin generation in hemophilia A and B plasma and restores clotting in FVIII-neutralized whole blood. In the present study, using a monkey model of hemophilia, FVIII neutralization resulted in prolonged clotting times as measured by thromboelastography and prolonged saphenous-vein bleeding times, which are consistent with FVIII deficiency. ARC19499 restored thromboelastography clotting times to baseline levels and corrected bleeding times. These results demonstrate that ARC19499 inhibition of TFPI may be an effective alternative to current treatments of bleeding associated with hemophilia.

The Role of Catalytic Cleft and Exosite Residues of Factor VIIa for Complex Formation with Tissue Factor Pathway Inhibitor

2001 ◽  
Vol 85 (03) ◽  
pp. 458-463 ◽  
Author(s):  
Alexei Iakhiaev ◽  
Wolfram Ruf ◽  
Vijaya Mohan Rao
Keyword(s):  
Complex Formation ◽  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Factor Viia ◽  
Cell Surface Receptor ◽  
Tissue Factor Pathway ◽  
Gla Domain ◽  
Catalytic Cleft ◽  
S2 Subsite

SummaryThe extrinsic coagulation pathway is initiated by the binding of plasma factor VIIa (VIIa) to the cell surface receptor tissue factor (TF). Formation of the TF-VIIa complex results in allosteric activation of VIIa as well as the creation of an extended macromolecular substrate binding exosite that greatly enhances proteolytic activation of substrate factor X. The catalytic function of the TF-VIIa complex is regulated by a specific Kunitz-type inhibitor, tissue factor pathway inhibitor (TFPI). TFPI inhibition of the TF-VIIa complex was enhanced by the presence of Xa. This study investigates the relative contribution of catalytic cleft and exosite residues in VIIa for inhibitory complex formation with TFPI. VIIa protease domain residues Q176, T239 and E296 are involved in the formation of stable inhibitor complex with free TFPI. Kinetic analysis further demonstrated a predominant role of the S2’ subsite residue Q176 for the initial complex formation with TFPI. In contrast, no significant reductions in inhibition by TFPI-Xa were found for each of the mutants in complex with phospholipid reconstituted TF. However, reduced rates of inhibition of the VIIa Gla-domain (R36) and Q176 mutant by TFPI-Xa were evident when TF was solubilized by detergent micelles. These data demonstrate docking of the TFPI-Xa complex with the macromolecular substrate exosite and the catalytic cleft, in particular the S2’ subsite. The masking of the mutational effect by the presence of phospholipid shows a critical importance of Xa Gla-domain interactions in stabilizing the quaternary TF-VIIa-Xa-TFPI complex.

State-of-the-Art Review : Role of Antithrombin and Tissue Factor Pathway Inhibitor in the Control of Thrombosis and Mediation of Heparin Action

1996 ◽  
Vol 2 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Nina Iverson ◽  
Ulrich Abildgaard
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
State Of The Art ◽  
Factor Viia ◽  
Heparin Therapy ◽  
Factor X ◽  
Factor Ixa ◽  
Tissue Factor Pathway ◽  
Blocking Antibodies

Deficiency of any of the two coagulation in hibitors antithrombin (AT) and tissue factor pathway in hibitor (TFPI) lowers the resistance to thrombosis. He reditary deficiency of AT leads to a high risk of throm bosis, which occasionally responds poorly to heparin therapy. Experimental deficiency of TFPI lowers the re sistance to infusion of both tissue factor and endotoxin, both regarding microvascular thrombosis and fatality. Administration of either AT or TFPI protects against mi cro- and macrovascular thrombosis. Injection of heparin and some other glycosaminoglycans releases intima bound TFPI to the blood. Heparin accelerates the inhib itory effects of both inhibitors, in particular the effect of AT. The influence of the two inhibitors on the various anticoagulant reactions have been studied using blocking antibodies. It is suggested that the anticoagulant and an tithrombotic effects of heparin are mainly mediated by the accelerated inactivation of thrombin, factor IXa and factor X by AT, and augmented inactivation of tissue factor-factor VIIa by TFPI released to the blood.

scholarly journals Studies on Tissue Factor Pathway Inhibitor Antigen Release by Bovine, Ovine and Porcine Heparins Following Intravenous Administration to Non-Human Primates

2020 ◽  
Vol 26 ◽  
pp. 107602962095185
Author(s):  
Ahmed Kouta ◽  
Debra Hoppensteadt ◽  
Emily Bontekoe ◽  
Walter Jeske ◽  
Richard Duff ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Factor Viia ◽  
Factor Xa ◽  
Extrinsic Pathway ◽  
Tissue Factor Pathway ◽  
Alternative Sources ◽  
Religious Reasons ◽  
Different Origins ◽  
Antigen Release

Unfractionated heparin (UFH) is a sulfated glycosaminoglycan that consists of repeating disaccharides, containing iduronic acid (or glucuronic acid) and glucosamine, exhibiting variable degrees of sulfation. UFHs release tissue factor pathway inhibitor (TFPI) which inhibits the extrinsic pathway of coagulation by inactivating factor Xa and the factor VIIa/TF complex. Most heparins used clinically are derived from porcine intestinal mucosa however, heparins can also be derived from tissues of bovine and ovine origin. Currently there are some concerns about the shortage of the porcine heparins as they are widely used in the manufacturing of the low molecular weight heparins (LMWHs). Moreover, due to cultural and religious reasons in some countries, alternative sources of heparins are needed. Bovine mucosal heparins (BMH) are currently being developed for re-introduction to the US market for both medical and surgical indications. Compared to porcine mucosal heparin (PMH), BMH exhibits a somewhat weaker anti-coagulant activity. In this study, we determined the TFPI antigen level following administration of various dosages of UFHs from different origins. These studies demonstrated that IV administration of equigravemetric dosages of PMH and ovine mucosal heparin (OMH) to non-human primates resulted in comparable TFPI antigen release from endothelial cells. In addition, the levels of TFPI were significantly higher than TFPI antigen levels observed after BMH administration. Potency adjusted dosing resulted in comparable TFPI release profiles for all 3 heparins. Therefore, such dosing may provide uniform levels of anticoagulation for the parenteral indications for UFHs. These observations warrant further clinical validation in specific indications.

Pharmacokinetics of Full Length and Two-Domain Tissue Factor Pathway Inhibitor in Combination with Heparin in Rabbits

1993 ◽  
Vol 70 (03) ◽  
pp. 454-457 ◽  
Author(s):  
Claus Bregengaard ◽  
Ole Nordfang ◽  
Per Østergaard ◽  
Jens G L Petersen ◽  
Giorgio Meyn ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Anticoagulant Activity ◽  
Fold Increase ◽  
Volume Of Distribution ◽  
Full Length ◽  
Heparin Binding ◽  
Extrinsic Pathway ◽  
C Terminus ◽  
Tissue Factor Pathway

SummaryTissue factor pathway inhibitor (TFPI) is a feed back inhibitor of the initial activation of the extrinsic pathway of coagulation. In humans, injection of heparin results in a 2-6 fold increase in plasma TFPI and recent studies suggest that TFPI may be important for the anticoagulant activity of heparin. Full length (FL) TFPI, but not recombinant two-domain (2D) TFPI, has a poly cationic C-terminus showing very strong heparin binding. Therefore, we have investigated if heparin affects the pharmacokinetics of TFPI with and without this C-terminus.FL-TFPI (608 U/kg) and 2D-TFPI (337 U/kg) were injected intravenously in rabbits with and without simultaneous intravenous injections of low molecular weight heparin (450 anti-XaU/kg).Heparin decreased the volume of distribution and the clearance of FL-TFPI by a factor 10-15, whereas the pharmacokinetics of 2D-TFPI were unaffected by heparin. When heparin was administered 2 h following TFPI the recovery of FL-TFPI was similar to that found in the group receiving the two compounds simultaneously, suggesting that the releasable pool of FL-TFPI is removed very slowly in the absence of circulating heparin.

Factor Xa Enhances the Binding of Tissue Factor Pathway Inhibitor to Acidic Phospholipids

1996 ◽  
Vol 75 (05) ◽  
pp. 796-800 ◽  
Author(s):  
Sanne Valentin ◽  
Inger Schousboe
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Factor Xa ◽  
Microtitre Plate ◽  
C Terminus ◽  
Microtitre Plate Assay ◽  
Kunitz Domain ◽  
Tissue Factor Pathway ◽  
Acidic Phospholipids

SummaryIn the present study, the interaction between tissue factor pathway inhibitor (TFPI) and phospholipids has been characterized using a microtitre plate assay. TFPI was shown to bind calcium-independently to an acidic phospholipid surface composed of phosphatidylserine, but not a surface composed of the neutral phosphatidylcholine. The interaction was demonstrated to be dependent on the presence of the TFPI C-terminus. The presence of heparin (1 U/ml, unfractionated) was able to significantly reduce the binding of TFPI to phospholipid. The interaction of TFPI with phosphatidylserine was significantly decreased in the presence of calcium, but this was counteracted, and even enhanced, following complex formation of TFPI with factor Xa prior to incubation with the phospholipid surface. Moreover, a TFPI variant, not containing the third Kunitz domain and the C-terminus, was unable to bind to phospholipid. However, following the formation of a TFPI/factor Xa-complex this TFPI variant was capable of interacting with the phospholipid surface. This indicates that the role of factor Xa as a TFPI cofactor, at least in part, is to mediate the binding of TFPI to the phospholipid surface.

Effect of Depolymerized Holothurian Glycosaminoglycan (DHG) on Tissue Factor Pathway Inhibitor: In Vitro and In Vivo Studies

1997 ◽  
Vol 78 (02) ◽  
pp. 864-870 ◽  
Author(s):  
Hideki Nagase ◽  
Kei-ichi Enjyoji ◽  
Yu-ichi Kamikubo ◽  
Keiko T Kitazato ◽  
Kenji Kitazato ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Factor Xa ◽  
Free Form ◽  
Initial Reaction ◽  
Extrinsic Pathway ◽  
Factor Xa Inhibition ◽  
Tissue Factor Pathway

SummaryDepolymerized holothurian glycosaminoglycan (DHG) is a glycosaminoglycan extracted from the sea cucumber Stichopus japonicusSelenka. In previous studies, we demonstrated that DHG has antithrombotic and anticoagulant activities that are distinguishable from those of heparin and dermatan sulfate. In the present study, we examined the effect of DHG on the tissue factor pathway inhibitor (TFPI), which inhibits the initial reaction of the tissue factor (TF)-mediated coagulation pathway. We first examined the effect of DHG on factor Xa inhibition by TFPI and the inhibition of TF-factor Vila by TFPI-factor Xa in in vitro experiments using human purified proteins. DHG increased the rate of factor Xa inhibition by TFPI, which was abolished either with a synthetic C-terminal peptide or with a synthetic K3 domain peptide of TFPI. In contrast, DHG reduced the rate of TF-factor Vila inhibition by TFPI-factor Xa. Therefore, the effect of DHG on in vitroactivity of TFPI appears to be contradictory. We then examined the effect of DHG on TFPI in cynomolgus monkeys and compared it with that of unfractionated heparin. DHG induced an increase in the circulating level of free-form TFPI in plasma about 20-fold when administered i.v. at 1 mg/kg. The prothrombin time (PT) in monkey plasma after DHG administration was longer than that estimated from the plasma concentrations of DHG. Therefore, free-form TFPI released by DHG seems to play an additive role in the anticoagulant mechanisms of DHG through the extrinsic pathway in vivo. From the results shown in the present work and in previous studies, we conclude that DHG shows anticoagulant activity at various stages of coagulation reactions, i.e., by inhibiting the initial reaction of the extrinsic pathway, by inhibiting the intrinsic Xase, and by inhibiting thrombin.

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