Increased Tissue Factor Pathway Inhibitor Levels Research Articles

Tissue Factor Pathway Inhibitor Levels During Veno-Arterial Extracorporeal Membrane Oxygenation in Adults.

Tissue factor pathway inhibitor (TFPI) has multiple anticoagulant properties. To our knowledge, no studies have measured TFPI levels in adult veno-arterial (VA) extracorporeal membrane oxygenation patients. We hypothesized that adult VA ECMO patients would have increased TFPI levels and slowed tissue factor triggered thrombin generation. Twenty VA ECMO patients had TFPI levels and thrombin generation lag time measured on ECMO day 1 or 2, day 3, and day 5. TFPI levels and thrombin generation lag time were compared against healthy control plasma samples. Mean TFPI levels were significantly higher in ECMO patients on ECMO day 1 or 2 = 81,877 ± 19,481 pg/mL, day 3 = 73,907 ± 26,690 pg/mL, and day 5 = 77,812 ± 23,484 pg/mL compared with control plasma = 38,958 ± 9,225 pg/mL (P < 0.001 for all comparisons). Median thrombin generation lag time was significantly longer in ECMO patients on ECMO day 1 or 2 = 10.0 minutes [7.5, 13.8], day 3 = 9.0 minutes [6.8, 12.1], and day 5 = 10.7 minutes [8.3, 15.2] compared with control plasma = 3.6 minutes [2.9, 4.2] (P < 0.001 for all comparisons). TFPI is increased in VA ECMO patients and tissue factor triggered thrombin generation is slowed. Increased TFPI levels could contribute to the multifactorial coagulopathy that occurs during ECMO.

Increased tissue factor activity promotes thrombin generation at type 1 diabetes onset in children

ObjectiveIn type 1 diabetes (T1D), a prothrombotic status due to elevated coagulation factors coincides with metabolic derailment. In a previous study, we discovered altered thrombin generation profiles in children with T1D. These alterations are potentially most pronounced at T1D onset and ameliorated after insulin treatment. We tested this hypothesis in a longitudinal study, measuring thrombin generation together with coagulation parameters in children at T1D onset and during follow‐up.Materials and methodsTwenty‐three children (12 female, age: 9.4 [2.7‐17.3] years; median [range]) were tested at T1D onset and after long‐term insulin treatment. Thrombin generation was measured using calibrated automated thrombography. Tissue factor (TF) activity and tissue factor pathway inhibitor (TFPI) activity were measured using enzyme‐linked immunosorbent assay (ELISA).ResultsA procoagulant shift was observed in thrombin generation traces at T1D onset compared to follow‐up (time to peak: 5.67 [4.11‐7.67] min vs 6.39 [4.89‐10.44] min, P < .001). These alterations at T1D onset coincided with increased TF activity (5.18 [0.01‐12.97] pmol/L vs 2.67 [0.04‐10.41] pmol/L, P < .05) and increased TFPI activity (0.051 [0.038‐0.074] U/mL vs 0.035 [0.026‐0.056] U/mL, P < .05).ConclusionThe procoagulant shift in thrombin generation at T1D onset is a result of increased TF activity, but this effect is partially counterbalanced by increased TFPI levels. Elevated TF and TFPI levels hint to a fragile hemostatic balance at the endothelial lining of blood vessels. Additional prothrombotic stimuli may tip over this balance explaining the increased thrombotic risk of children with T1D.

Tissue Factor Pathway Inhibitor (TFPI) May be Another Important Factor in the Coagulopathy in Acute Promyelocytic Leukemia (APL)

The characteristic coagulopathy in Acute Promyelocytic Leukemia (APL) is unique among the leukemias and thrombotic and bleeding complications remain the major causes of early deaths. APL promyelocytes express tissue factor (TF) which, after activation by phospholipids, forms a complex with factor VII and converts factor X to activated factor X. TF plays a central role in the pathogenesis of APL coagulopathy, for the procoagulant activity of lysates from freshly isolated APL cells is mainly attributed to TF. During periods of increased apoptosis of promyelocytes, the procoagulant activity is correspondingly intensified. In addition, APL cells may also induce TF procoagulant activity of endothelial cells through their secretion of IL-1b. The activity of the complex FVIIa-TF can be inhibited by the tissue factor pathway inhibitor (TFPI), but its role in the APL-associated coagulopathy remains unknown. This study aimed to determine the time-course of TFPI levels in patients with APL at diagnosis and during the first two-weeks of treatment with ATRA and anthracyclines. Twenty patients with de novo APL (12 males, age ranging from 17 to 72 years) and 20 healthy blood donors (age and sex matched) were included in this study. Peripheral blood (PB) samples were collected at diagnosis, and at D3, D7 and D15 of the induction therapy with ATRA and daunorubicin. The following plasma concentrations were determined: Thrombin-Antithrombin complex (TAT) (Enzygnost¨ TAT micro, Dade Behring/Siemens, IL, EUA), total TFPI (Asserachrom¨ total TFPI, Diagnostica Stago, Frana) and free TFPI (Asserachrom¨ free TFPI, Diagnostica Stago, Frana). The plasma concentrations of TAT were significantly higher in APL patients at presentation, D3 and D7 compared to controls, suggesting that the pathologic activation of coagulation was reversed by D15 of treatment Figure 1). The concentrations of free-TFPI were significantly higher in APL samples compared to controls in all time-points (Figure 2). In contrast, the concentrations of the truncated form of TFPI (estimated by subtracting the free-TFPI values from total-TFPI concentration) did not vary significantly between the groups. Since, free-TFPI (intact form) has been proven to present higher capacity to inhibit the activated factor X and VIIa-TF proteases than truncated-TFPI (bound to lipoprotein), we hypothesized that our findings confirm the relevance of free-TFPI in APL coagulopathy. To test whether the administration of rh-TFPI may revert aberrant activation of coagulation in APL patients, we developed a murine model using the IV infusion of NB4 cells. Similarly to the reported in APL patients, we observed an increase on TAT levels in mice injected with 5x106 NB4 cells [(60.7 ng/ml (24 - 116 ng/ml) vs 11.5 ng/ml (2.2 - 27.8 ng/ml), p<0.05)]. In contrast, murine TFPI levels decreased 30 minutes after the infusion of NB4 cells [30 ng/ml (5.8 - 217 ng/ml) vs 202 ng/ml (46 - 354 ng/ml)], suggesting that it was rapidly consumed. Unfortunately, it was not possible to distinguish between truncated and intact TFPI forms in mice. Intravenous infusion of recombinant human (rh) TFPI at the dose of 10mg/Kg significantly decreased the TAT levels (Figure 3) and increased TFPI levels in the murine model. In conclusion, our data on clinical samples and pre-clinical data using a murine model suggest that treatment with rh-TFPI may be a strategy to counteract APL-associated coagulopathy. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

A novel mutation in the F5 gene (factor V Amsterdam) associated with bleeding independent of factor V procoagulant function

AbstractWe investigated a small Dutch family with a bleeding diathesis, prolonged prothrombin, and activated partial thromboplastin times, in whom no classifying diagnosis was made. The 2 affected relatives had severely decreased in vitro thrombin generation, and levels of tissue factor pathway inhibitor (TFPI) were strongly increased. To identify the genetic cause of the bleeding diathesis, we performed whole exome sequencing analysis of all living relatives. We found a novel gain-of-function mutation in the F5 gene (c.C2588G), which leads to an aberrant splicing of F5 and ultimately to a short factor V protein (missing 623 amino acids from the B domain), which we called factor V Amsterdam. Factor V Amsterdam binds to TFPI, prolonging its half-life and concentration. This is the second report of an association between a shorter form of factor V and increased TFPI levels, resulting in severely reduced thrombin generation and a bleeding tendency.

The role of tissue factor pathway inhibitor in atherosclerosis and arterial thrombosis

Tissue factor pathway inhibitor (TFPI) is the main inhibitor of tissue factor (TF)-mediated coagulation. In atherosclerotic plaques TFPI co-localizes with TF, where it is believed to play an important role in attenuating TF activity. Findings in animal models such as TFPI knockout models and gene transfer models are consistent on the role of TFPI in arterial thrombosis as they reveal an active role for TFPI in attenuating arterial thrombus formation. In addition, ample experimental evidence exists indicating that TFPI has inhibitory effects on both smooth muscle cell migration and proliferation, both which are recognized as important pathological features in atherosclerosis development. Nonetheless, the clinical relevance of these antithrombotic and atheroprotective effects remains unclear. Paradoxically, the majority of clinical studies find increased instead of decreased TFPI antigen and activity levels in atherothrombotic disease, particularly in atherosclerosis and coronary artery disease (CAD). Increased TFPI levels in cardiovascular disease might result from complex interactions with established cardiovascular risk factors, such as hypercholesterolemia, diabetes and smoking. Moreover, it is postulated that increased TFPI levels reflect either the amount of endothelial perturbation and platelet activation, or a compensatory mechanism for the increased procoagulant state observed in cardiovascular disease. In all, the prognostic value of plasma TFPI in cardiovascular disease remains to be established. The current review focuses on TFPI in clinical studies of asymptomatic and symptomatic atherosclerosis, coronary artery disease and ischemic stroke, and discusses potential atheroprotective actions of TFPI.

Increased tissue factor pathway inhibitor activity is associated with myocardial infarction in young women: results from the RATIO study.

The tissue factor pathway inhibitor (TFPI)/protein S anticoagulant system is a potent inhibitor of blood coagulation. TFPI and protein S are major determinants of thrombin generation (TG) tests determined at low tissue factor (TF) and at high TF concentrations in the presence of activated protein C (APC). Both TFPI and protein S protect against venous thrombosis, but the importance of the TFPI/protein S system in arterial thrombosis remains unclear. To investigate the influence of the TFPI/protein S anticoagulant system on the risk of myocardial infarction (MI) in young women. The RATIO study is a case-control study in women under 50 years of age, including 205 patients and 638 controls. TFPI and protein S were quantified using ELISA. The TFPI/protein S activity (nTFPIr) and the APC sensitivity ratio (nAPCsr) were determined using TG tests. Odds ratios (ORs) adjusted for putative confounders and corresponding 95% confidence intervals (95% CI) were determined. Women with MI had higher TFPI levels than controls (135.9 ± 40% vs. 124.2 ± 41%), resulting in increased TFPI/protein S activities and increased APC sensitivity. Furthermore, an increased TFPI activity was associated with MI [nTFPIr: adjusted OR Q1 vs. Q4 = 2.1 (95%CI 1.1-4.1)]. Additionally, an increased APC sensitivity was associated with MI [nAPCsr: adjusted OR Q1 vs. Q4 = 1.7 (95% CI 0.9-3.2)] Women with MI had increased TFPI levels compared with controls. Consequently, the TFPI/protein S activity and APC sensitivity are increased in women with MI. Whether this increase in TFPI activity acts as a compensating mechanism for an increased procoagulant state or is a marker of endothelial damage remains to be investigated.

Molecular weight dependent tissue factor pathway inhibitor release by heparin and heparin oligosaccharides

Heparin and low molecular weight heparins exert their vascular effects by mobilizing tissue factor pathway inhibitor (TFPI) from the vascular endothelium into the blood circulation. We compared the influence of molecular weight on the TFPI release by heparin and its fractions in a non-human primate model. Primates were treated with unfractionated heparin, a low molecular weight heparin (gammaparin), or a heparin-derived oligosaccharide mixture (C3). Endothelial TFPI release was determined using both immunologic and functional assays. After intravenous administration, all agents significantly increased TFPI levels ( p < 0.05) in a dose dependent manner. The increase produced by unfractionated heparin and gammaparin was greater than that by C3 at an equal dosage ( p < 0.05). With subcutaneous injection, all agents produced less TFPI release. Repeated administration of heparin-derived oligosaccharides gradually increased TFPI release. A 1.89 fold increase in TFPI levels was observed 4 days after C3 treatment (2.5 mg/kg). Our findings indicated that TFPI release is dependent on the molecular weight of heparin and its derivatives. Heparin oligosaccharides exert their vascular effects through increased TFPI release after long-term repeated administration.

The present status of tissue factor pathway inhibitor

Tissue factor pathway inhibitor (TFPI) is the factor Xa-dependent inhibitor of the factor VIIa/tissue factor complex. The plasma concentration of this 276 amino acid, 40 kDa glycoprotein is normally about 100 ng/ml. There are three intravascular pools of TFPI: 50-90% is on the endothelium, 10-50% is in plasma and less than 2.5% is in platelets. The TFPI in plasma is mainly associated with lipoproteins-only about 5% is free TFPI. The lipoprotein-associated TFPI seems to be of less anticoagulant effect than the free TFPI. Both unfractionated heparin, low-molecular-weight heparins and pentosan polysulphate induce release of TFPI after intravenous injection, whereas dermatan sulphate does not. The interactions with TFPI account for a considerable amount of the anticoagulant effect of heparin. Studies have shown increased TFPI levels in plasma from patients with advanced malignancy and in subjects with fatal DIC or septicaemia. The reason for this is unknown. For measuring the anticoagulant activity of TFPI in plasma, end-point or antigen assays may be less useful than the clotting assay with dilute tissue factor. Animal studies indicate that the main physiological role of TFPI is the inhibition of small amounts of tissue factor. TFPI is probably essential for a normal haemostatic balance.

The present status of tissue factor pathway inhibitor

Tissue factor pathway inhibitor (TFPI) is the factor Xa-dependent inhibitor of the factor VIIa/tissue factor complex. The plasma concentration of this 276 amino acid, 40 kDa glycoprotein is normally about 100 ng/ml. There are three intravascular pools of TFPI: 50-90% is on the endothelium, 10-50% is in plasma and less than 2.5% is in platelets. The TFPI in plasma is mainly associated with lipoproteins— only about 5% is free TFPI. The lipoprotein-associated TFPI seems to be of less anticoagulant effect than the free TFPI. Both unfractionated heparin, low-molecular-weight heparins and pentosan polysulphate induce release of TFPI after intravenous injection, whereas dermatan sulphate does not. The interactions with TFPI account for a considerable amount of the anticoagulant effect of heparin. Studies have shown increased TFPI levels in plasma from patients with advanced malignancy and in subjects with fatal DIC or septicaemia. The reason for this is unknown. For measuring the anticoagulant activity of TFPI in plasma, end-point or antigen assays may be less useful than the clotting assay with dilute tissue factor. Animal studies indicate that the main physiological role of TFPI is the inhibition of small amounts of tissue factor. TFPI is probably essential for a normal haemostatic balance.