The Significance of TFPI in Clotting Assays – Gomparison and Combination with other Anticoagulants

1993 ◽  
Vol 70 (03) ◽  
pp. 448-453 ◽  
Author(s):  
Ole Nordfang ◽  
Hanne I Kristensen ◽  
Sanne Valentin ◽  
Per Østergaard ◽  
Johnny Wadt
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Antithrombin Iii ◽  
Anticoagulant Activity ◽  
Assay System ◽  
Thrombin Inhibitor ◽  
Clotting Time ◽  
Normal Plasma ◽  
Tissue Factor Pathway ◽  
Plasma Heparin

SummaryThe anticoagulant activities of Tissue Factor Pathway Inhibitor (TFPI), heparin and hirudin were compared in intrinsic (APTT) and extrinsic (PT) activated clotting assays. In contrast to the thrombin inhibitor hirudin, heparin was 10 fold more potent in the APTT assay than in the PT assay, indicating that inhibition of intrinsic activation is important for the anticoagulant activity of heparin as measured in an APTT assay. TFPI was most potent in the PT assay and the effect of TFPI was most pronounced in the presence of other anticoagulants (heparin and hirudin). The activities of the two natural anticoagulants antithrombin III (ATIII) and TFPI were compared in a PT assay with very dilute tissue factor. In this assay system TFPI in normal plasma affected the clotting time more than ATIII in the plasma. However, when heparin was added ATIII was the major anticoagulant, but profound Prolongation of the clotting time was only seen when TFPI was also added. In an ATIII deficient plasma heparin did not augment the effect of TFPI, showing that the increased effect of TFPI in the presence of heparin is dependent on the anticoagulant activity of ATIII/heparin. The effect of TFPI at prolonged clotting times was also illustrated by the significant effect of blocking TFPI in the plasma from warfarin-treated patients. Thus TFPI is a major anticoagulant in normal plasma and the effect of TFPI is especially seen at prolonged clotting times.

Effect of Tissue Factor Pathway Inhibitor (TFPI) in the HEPTEST® Assay and in an Amidolytic Anti Factor Xa Assay for LMW Heparin

1992 ◽  
Vol 68 (03) ◽  
pp. 310-314 ◽  
Author(s):  
Hanne I Kristensen ◽  
Per B Østergaard ◽  
Ole Nordfang ◽  
Ulrich Abildgaard ◽  
Anne Karin Lindahl
Keyword(s):  
Tissue Factor ◽  
Low Molecular Weight Heparin ◽  
Tissue Factor Pathway Inhibitor ◽  
Antithrombin Iii ◽  
Factor Xa ◽  
Low Molecular Weight ◽  
Activity Detection ◽  
Clotting Time ◽  
Heparin Activity ◽  
Tissue Factor Pathway

SummaryBoth the HEPTEST® and amidolytic anti factor Xa assays are currently being used for heparin activity detection in plasma from patients receiving standard heparin or low molecular weight heparin (LMWH). In this study we have investigated the influence of recombinant and endogenous Tissue Factor Pathway Inhibitor (TFPI) on these assays. The HEPTEST® determinations were performed on an ACL 300 R Clottimer using the APTT program which resulted in a longer incubation time with factor Xa than recommended by the manufacturer. rTFPI added to plasma prolonged the HEPTEST® clotting time markedly, but had only a little effect in the amidolytic assay. Antibodies against TFPI (anti-TFPI) abolished these effects. The effect of adding rTFPI and Logiparin® was additive. When anti-TFPI IgG was added to samples of normal plasma, a statistically significant shortening of the HEPTEST® clotting time was seen. When anti-TFPI was added to plasma samples from volunteers who had received Logiparin® by subcutaneous or intravenous injection, then the HEPTEST® clotting time was shortened considerably. For some samples the clotting time was halved. These experiments show that the HEPTEST® clotting time is prolonged not only by heparin-antithrombin III, but also by TFPI released by heparin injection.

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.

Abstract 43: Prothrombinase Assembled with Factor V Leiden is Resistant to Inhibition by Tissue Factor Pathway Inhibitor α Lowering the Procoagulant Threshold for Initiation of Coagulation

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Jeremy P Wood ◽  
Lisa M Baumann Kreuziger ◽  
Susan A Maroney ◽  
Rodney M Camire ◽  
Alan E Mast
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Tissue Factor Pathway Inhibitor ◽  
Platelet Rich Plasma ◽  
Anticoagulant Activity ◽  
Factor V Leiden ◽  
Factor Xa ◽  
Factor V ◽  
Activation Threshold ◽  
Tissue Factor Pathway

Factor V (FV) assembles with factor Xa (FXa) into prothrombinase, the enzymatic complex that converts prothrombin to thrombin. Tissue factor pathway inhibitor α (TFPIα) inhibits prothrombinase by high affinity interactions with FXa-activated FV and the FXa active site, thereby blocking the initiation of coagulation. FV Leiden (FVL) is strongly linked to venous thrombosis through its resistance to degradation by activated protein C (aPC), which enhances the propagation of coagulation. FVL combined with a 50% reduction in TFPI causes severe thrombosis and perinatal lethality in mice, suggesting that FVL also promotes the initiation of coagulation. To examine this possibility, thrombin generation assays initiated with limiting FXa were performed with control or FVL plasma and platelet-rich plasma (PRP). The activation threshold for thrombin generation was 10 to 20 pM FXa in 10 control plasmas, but was 5 pM in 4 of 10 homozygous FVL plasmas. FVL PRP had a similar decrease in the activation threshold. The differences in activation threshold were totally normalized by an anti-TFPI antibody, while exogenous TFPIα and a FV-binding peptide that mimics TFPIα had reduced anticoagulant activity in FVL plasma, revealing that the procoagulant effects of FVL in these assays rely on TFPIα. Next, FVL plasmas were studied in fibrin clot formation assays, as they are sensitive to small amounts of thrombin. In reactions activated with 0.5 pM FXa, 1 of 8 control plasmas, compared to 7 of 8 homozygous FVL plasmas, clotted within 60 minutes, with differences again normalized by the anti-TFPI antibody. In prothrombinase activity assays using purified proteins, TFPIα was a 1.7-fold weaker inhibitor of prothrombinase assembled with FVL compared to FV. Thus, in addition to its aPC-mediated effect on the propagation of coagulation, FVL is resistant to TFPIα inhibition, exerting a procoagulant effect on coagulation initiation. This is evident in responses to small stimuli, where TFPIα blocks clotting in plasmas with FV but not FVL. The TFPIα-mediated modulation of the procoagulant threshold may explain the severe perinatal thrombosis in FVL mice with decreased TFPI and be clinically relevant in the clotting associated with oral contraceptives, which cause acquired TFPI deficiency.

scholarly journals A Novel Degradation Pathway of Tissue Factor Pathway Inhibitor: Incorporation Into Fibrin Clot and Degradation by Thrombin

Blood ◽  
1997 ◽  
Vol 90 (5) ◽  
pp. 1883-1892 ◽  
Author(s):  
Naoki Ohkura ◽  
Kei-ichi Enjyoji ◽  
Yu-ichi Kamikubo ◽  
Hisao Kato
Keyword(s):  
Tissue Factor ◽  
Calcium Ion ◽  
Tissue Factor Pathway Inhibitor ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Fibrin Clot ◽  
Degradation Pathway ◽  
Normal Plasma ◽  
Tissue Factor Pathway ◽  
Basic Region

Abstract Tissue factor pathway inhibitor (TFPI) is a Kunitz-type protease inhibitor with three tandem inhibitory domains (K1, K2, and K3) that regulates the initial reactions of the extrinsic blood coagulation pathway through K1 and K2. In the present study, the effect of thrombin on TFPI in a purified system was first examined using recombinant TFPI from Chinese hamster ovary (CHO) cells. TFPI was inactivated by thrombin with cleavage of three peptide bonds, Lys 254-Thr 255 in the C-terminal basic region, Arg 107-Gly 108 (reactive site toward factor Xa in K2), and Lys 86-Thr 87 between K1 and K2. Then, degradation of radiolabeled TFPI by thrombin was examined in two systems: (1) mixed with plasma and then tissue factor (TF ) and calcium ion, and (2) mixed with fibrinogen and then thrombin. TFPI degradation was detected in serum from normal plasma and more extensively from antithrombin (AT)-depleted plasma by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Significant radioactivity was found in the clot after coagulation of the plasma, which decreased after 20 hours' incubation. These changes were more prominent in AT-depleted plasma than in normal plasma. When TFPI lacking the C-terminal basic region was used instead of full-length TFPI, most of the radioactivity was found in serum rather than in fibrin clots. Incorporation of TFPI into the fibrin clot was prevented by a synthetic C-terminal peptide of TFPI. Similar results were obtained after mixing radiolabeled TFPI with fibrinogen and then thrombin in the presence of calcium ion or EDTA. These results demonstrate a novel degradation pathway of TFPI, ie, incorporation into fibrin via the C-terminal basic region and degradation by thrombin (possibly fibrin-bound thrombin).

scholarly journals Small Peptides Blocking Inhibition of Factor Xa and Tissue Factor-Factor VIIa by Tissue Factor Pathway Inhibitor (TFPI)

2013 ◽  
Vol 289 (3) ◽  
pp. 1732-1741 ◽  
Author(s):  
Michael Dockal ◽  
Rudolf Hartmann ◽  
Markus Fries ◽  
M. Christella L. G. D. Thomassen ◽  
Alexandra Heinzmann ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Factor Viia ◽  
Anticoagulant Activity ◽  
Tight Binding ◽  
Factor Xa ◽  
Factor X ◽  
Intermediate Segment ◽  
Tissue Factor Pathway ◽  
Α Helix

Tissue factor pathway inhibitor (TFPI) is a Kunitz-type protease inhibitor that inhibits activated factor X (FXa) via a slow-tight binding mechanism and tissue factor-activated FVII (TF-FVIIa) via formation of a quaternary FXa-TFPI-TF-FVIIa complex. Inhibition of TFPI enhances coagulation in hemophilia models. Using a library approach, we selected and subsequently optimized peptides that bind TFPI and block its anticoagulant activity. One peptide (termed compound 3), bound with high affinity to the Kunitz-1 (K1) domain of TFPI (Kd ∼1 nm). We solved the crystal structure of this peptide in complex with the K1 of TFPI at 2.55-Å resolution. The structure of compound 3 can be segmented into a N-terminal anchor; an Ω-shaped loop; an intermediate segment; a tight glycine-loop; and a C-terminal α-helix that is anchored to K1 at its reactive center loop and two-stranded β-sheet. The contact surface has an overall hydrophobic character with some charged hot spots. In a model system, compound 3 blocked FXa inhibition by TFPI (EC50 = 11 nm) and inhibition of TF-FVIIa-catalyzed FX activation by TFPI (EC50 = 2 nm). The peptide prevented transition from the loose to the tight FXa-TFPI complex, but did not affect formation of the loose FXa-TFPI complex. The K1 domain of TFPI binds and inhibits FVIIa and the K2 domain similarly inhibits FXa. Because compound 3 binds to K1, our data show that K1 is not only important for FVIIa inhibition but also for FXa inhibition, i.e. for the transition of the loose to the tight FXa-TFPI complex. This mode of action translates into normalization of coagulation of hemophilia plasmas. Compound 3 thus bears potential to prevent bleeding in hemophilia patients.

Imbalance of Plasminogen Activator Inhibitor-I/ Tissue Plasminogen Activator and Tissue Factor/Tissue Factor Pathway Inhibitor in Young Japanese Men with Myocardial Infarction

2001 ◽  
Vol 86 (11) ◽  
pp. 1197-1203 ◽  
Author(s):  
Masahiko Saigo ◽  
Masakazu Ogawa ◽  
Tsuminori Yamashita ◽  
Sadatoshi Biro ◽  
Shinichi Minagoe ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Plasminogen Activator ◽  
Protein C ◽  
Tissue Factor Pathway Inhibitor ◽  
Antithrombin Iii ◽  
Plasminogen Activator Inhibitor ◽  
Lipoprotein A ◽  
Tissue Plasminogen ◽  
Tissue Factor Pathway ◽  
Activator Inhibitor

SummaryTo evaluate the association between haemostatic parameters and increased risk of myocardial infarction (MI) at a young age, we measured fibrinogen, factor VII, antithrombin III, protein C, protein S, tissue factor (TF), free form tissue factor pathway inhibitor (TFPI), plasminogen, 2-antiplasmin, tissue plasminogen activator (tPA), plasminogen activator inhibitor-I (PAI-I), and lipoprotein (a) in 140 young men with MI before age 45 and 150 age-matched healthy men. TF, TF/TFPI ratio, PAI-I, PAI-I/tPA ratio, plasminogen, and lipoprotein (a) in young MI patients were all significantly higher than controls, while TFPI, antithrombin III, and tPA were significantly lower (P <0.001 of each). Significant determinants of MI risk were PAI-I/tPA ratio (R2 = 0.300, P <0.001), TF/TFPI ratio (R2 = 0.049, P <0.001), antithrombin III (R2 = 0.034, P <0.001), hyperlipidaemia (R2 = 0.019, P = 0.004), diabetes (R2 = 0.014, P = 0.015), lipoprotein (a) (R2 = 0.012, P = 0.023), 2-antiplasmin (R2 = 0.014, P = 0.012), and protein C (R2 = 0.012, P = 0.018). We conclude that the imbalances of PAI-I/tPA and TF/TFPI are significantly associated with MI at a young age, perhaps mediated via impaired fibrinolytic activity.

Novel Protein Encoded by C6orf105 Regulates Tissue Factor Pathway Inhibitor Expression and Function In Human Endothelial Cells In Normal Conditions and During Androgen Stimulation

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 348-348
Author(s):  
Cristina Lupu ◽  
Hua Zhu ◽  
Jonathan Wren ◽  
Florea Lupu
Keyword(s):  
Endothelial Cells ◽  
Cell Surface ◽  
Western Blot ◽  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Anticoagulant Activity ◽  
Uncharacterized Protein ◽  
Tissue Factor Pathway ◽  
Anticoagulant Function ◽  
And Function

Abstract Abstract 348 Cardiovascular disease (CVD) and thrombotic complications (deep vein thrombosis/venous thromboembolism, DVT/VTE) represent major health problems, with men having higher rates of clinical events than women. Tissue Factor Pathway Inhibitor (TFPI) is the key natural inhibitor of coagulation: it neutralizes factor Xa (FXa) and inhibits tissue factor-factor VIIa (TF-FVIIa) in the presence of FXa. In vivo most of TFPI is in endothelial cells (EC), reversibly bound to yet unidentified receptors, and glycosyl phosphatidylinositol-floated in caveolae and/or lipid raft microdomains. Intravascular thrombosis occurs frequently in older people, especially associated with cancer, diabetes, or CVD. TF is directly involved in tumor hypercoagulability, angiogenesis and metastasis. Cell-associated TFPI is the most physiologically significant inhibitor of the TF-FVIIa- triggered coagulation pathway; nevertheless, very few mechanisms/factors that could regulate the natural expression of TFPI have been identified so far. Here we describe androgen treatment of EC as a novel way to preserve and/or enhance a healthy vascular function, particularly related to the regulation of TFPI-dependent anticoagulant function of the endothelium. Our hypothesis is that a yet uncharacterized protein encoded by C6orf105 is a novel regulator of TFPI expression and function in EC, both in native conditions and during androgen stimulation. “In silico” data mining using global meta-analysis of publicly available NCBI's Gene Expression Omnibus 2-channel human microarray datasets identified C6orf105 as highly co-expressed with TFPI and following a parallel co-regulation. The uncharacterized protein has 230-aa, Mr ∼27 kDa, 5–6 predicted transmembrane domains and has sequence similarities with members of the androgen-inducible genes family. We tentatively named it TFPI-Regulating Factor (TFPI-RF). Real-time qPCR and western blot confirmed robust expression of TFPI-RF in EC in culture (HUVEC and EA.hy926 hybrid cell line). By immunofluorescence (IMF) TFPI-RF appears both on the cell surface and intracellularly co-localizing with TFPI and caveolin-1 (cav-1). Post-transcriptional (siRNA) down-regulation of TFPI-RF decreased TFPI, both as protein (∼2-times) and as anticoagulant activity (∼3-fold), apparently by reducing the co-localization of the TF-FVIIa-FXa-TFPI complex with cav-1. Over-expression of TFPI-RF in HUVEC and EA.hy926 led to enhanced co-localization of TFPI-RF with TFPI, and increased TFPI mRNA and anticoagulant activity (∼2-times). Western blot of cellular fractions after extraction with Triton X-114 and temperature-induced phase separation revealed the presence of TFPI and TFPI-RF in detergent-insoluble fractions, which suggests predominant lipid raft association. IMF illustrates TFPI-RF co-clustering with TFPI and cav-1 or GM1 (raft marker) in live EC incubated with anti-TFPI antibody or Cholera Toxin-B, respectively. The effect of androgens was studied by incubating EC with 30 nM dehydrotestosterone (DHT) or equivalent testosterone-BSA (cell-impermeable). 1-h incubation led to 2-times enhanced TFPI activity, increased co-localization of the quaternary complex with cav-1 and TFPI-RF, and enhanced exposure of TFPI and TFPI-RF on the cell surface. 24-h treatment with DHT up-regulates the expression of both TFPI (2-fold) and TFPI-RF (3-fold), as well as the TFPI inhibitory activity against FXa. DHT failed to enhance TFPI activity in TFPI-RF siRNA EC. Our results reveal a novel mechanism of up-regulation of the anticoagulant activity of endogenous TFPI in response to physiological levels of androgen. While the precise role of androgens in the ageing process is unclear, it is believed that androgen replacement could have beneficial influence on the declining functions in the elderly. Our data could expand on the effects of androgens on the haemostatic function of the endothelium and discover new roles for novel proteins like C6orf105/TFPI-RF in enhancing the endothelial anticoagulant function. These may open possibilities to manipulate the cellular endogenous TFPI and/or other intrinsic factors to counteract pro-thrombotic states associated with CVD, DVT/VTE, sepsis and cancer. Disclosures: No relevant conflicts of interest to declare.

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