Total TFPI Research Articles

Total tissue factor pathway inhibitor is an independent risk factor for symptomatic paediatric venous thromboembolism and stroke.

Tissue factor pathway inhibitor (TFPI) plays an important role in inhibiting tissue factor-induced coagulation by a factor Xadependent pathway of the activated tissue-factor VIIa complex. Decreased values of the latter inhibitor have been recently reported in adult patients with venous thrombosis (VT) or ischaemic stroke (IS). The present case-control study was therefore performed to evaluate whether a decreased TFPI concentration is also involved in paediatric symptomatic thromboembolism (ST). Total TFPI concentrations were measured along with established prothrombotic risk factors six to twelve months after the acute thrombotic onset in 144 Caucasian children aged 0.6 to 18 years (VT: n=80; IS: n=64). The cut-off values defined as age-dependent 10(th) percentiles were obtained from 244 healthy controls. Median (range) values of TFPI were significantly lower in patients compared with control subjects [50.0(20.0-132.3) ng/ml vs. 59.5(25.4-117.4) ng/ml; p-value < 0.0001]. In addition, 42 of the 144 patients (29.2%) compared with 25 of the 244 controls (10.2%) showed TFPI concentrations below the 10(th) age-dependent percentiles. Compared to baseline values 78.6% of children with total TFPI Ag < 10(th) percentiles showed a low response to enoxaparin administration, whereas in children with normal baseline TFPI values 30% show a low TFPI release (p = 0.007). Multivariate analysis adjusted for the presence of established prothrombotic risk factors showed a significantly increased odds ratio (OR) and 95% confidence interval (CI) for patients with ST [OR/CI: 3.8/2.2-6.6; p < 0.0001]. Data shown here give evidence that total TFPI concentrations below the 10(th) age-dependent percentiles independently increase the risk of ST in Caucasian children 3.8-fold.

The −33T → C Polymorphism in Intron 7 of the TFPI Gene Influences the Risk of Venous Thromboembolism, Independently of the Factor V Leiden and Prothrombin Mutations

We have previously identified, in intron 7 of the TFPI gene, a T to C single-base polymorphism (-33T-->C) which is strongly associated with total circulating TFPI antigen levels. Here we examined the influence of this polymorphism on the risk of venous thromboembolism. The polymorphism was identified in the PATHROS study population (330 cases with venous thromboembolism and 826 controls). The CC genotype was found in 6.4% of cases and 10.2% of controls (age-adjusted odds ratio 0.6; 95% CI 0.3-0.9; p = 0.03). This protective effect persisted after adjustment for oral contraception and the factor V Leiden and prothrombin gene polymorphisms. In 171 controls and 49 cases in whom blood was taken at least three months after the thrombotic event, the CC genotype was associated with significantly higher total TFPI levels than the TT genotype. These results suggest that the CC genotype of the TFPI intron 7 polymorphism is an independent protective factor for venous thromboembolism, an effect probably mediated by increased TFPI levels.

Plasma Levels of Free and Total TFPI, Relationship with Cardiovascular Risk Factors and Endothelial Cell Markers

Free-TFPI (f-TFPI) presents high anticoagulant activity and its plasma level correlates with unfavorable outcomes in unstable angina. Total TFPI (t-TFPI) represents mainly the lipid-bound form which seems to have a poor anticoagulant activity. Until now, it is not known whether the variations of f-TFPI plasma levels are determined by environmental factors. The aim of our study was to evaluate the influence of cardiovascular risk factors on plasma levels of f-TFPI and relations with other endothelial derived molecules in a population of 626 patients (277 men and 349 women) attending a metabolic ward for primary prevention of coronary disease. Free and total TFPI plasma levels were poorly correlated. f-TFPI levels increased with age in both sexes, t-TFPI in women only. Age-adjusted correlations of TFPI levels with conventional cardiovascular risk factors and endothelial cell markers showed different patterns for f-TFPI and t-TFPI. f-TFPI correlated with parameters associated with insulin resistance, particularly in females. f-TFPI was also positively associated in both genders with fibrinogen and endothelial cell markers: t-PA, thrombomodulin (TM) and von Willebrand factor (vWF). t-TFPI correlated strongly with LDL-C in both sexes. It also correlated negatively with parameters of the insulin resistance syndrome. t-TFPI also correlated with TM but not with other endothelial cell markers. The results of the multivariate step by step analysis showed that cardiovascular risk factors poorly explained the f-TFPI variability (7% and 4% in men and women, respectively), whereas they explained 16 and 20% of t-TFPI variability in men and women respectively (mostly related to LDL-C). In conclusion, this study showed that free- and total-TFPI are regulated differently. f-TFPI strongly correlates with endothelial cell markers and t-TFPI is more related to conventional cardiovascular risk factors. The strong gender effect on f-TFPI levels remains to be explained.

A New T-287C Polymorphism in the 5’ Regulatory Region of the Tissue Factor Pathway Inhibitor Gene

Tissue factor pathway inhibitor (TFPI) is an important regulator of the extrinsic blood coagulation pathway. We screened the untranslated 5' region of the TFPI gene for polymorphisms and investigated their possible involvement in arterial thrombosis. The allele frequencies of a new polymorphism, located 287 base pairs upstream of the transcription start site (T-287C), and that of the previously described C-399T polymorphism, were similar in cases and controls. In controls, the -287C allele was associated with significantly higher levels of total TFPI antigen, arguing for an effect of this polymorphism on TFPI gene expression. In controls, the C-399T polymorphism did not alter TFPI levels. In the cases, however, decreased total and post-heparin free TFPI levels and increased F1+2 levels were significantly associated with the -399T allele. These findings suggest that the T-287C and C-399T polymorphisms are not associated with an increased risk of coronary heart disease, a result which should be confirmed by a larger study. However, their influence on outcome, or a link with subtypes of acute coronary syndromes, cannot be excluded.

Elevated TFPI in malignant disease: relation to cancer type and hypercoagulation.

We have previously reported high levels of the coagulation inhibitor TFPI in the blood of patients with gastrointestinal cancer. TFPI is not an acute-phase reactant, but high levels have also been reported in patients with septicaemia and disseminated intravascular coagulation (DIC). To study its relationship with other types of malignancy, TFPI activity was first determined in plasma samples from 214 patients with various malignancies. In a second cohort of 83 patients, total and free TFPI antigen, protein C, antithrombin, fibrin monomer and D-dimer were also measured. Elevated TFPI activity and antigens were found in about half of the patients with solid tumours. In contrast, elevated TFPI was rare in haematological malignancies (12%). In the 18 patients with acute nonlymphocytic leukaemia (ANLL), elevated free TFPI was found only in patients who also had DIC. No correlation was found between TFPI levels and fibrin monomer or D-dimer levels. Only four out of 20 patients with solid tumours had normal levels of fibrin monomer and D-dimer, yet three out of these four had elevated TFPI. In conclusion, elevated TFPI in ANLL is related to the coexistence of DIC. In solid tumour disease increased TFPI may reduce protective fibrin formation, but the pathogenic mechanism is as yet unknown.

Increased Plasma Levels of Free Tissue Factor Pathway Inhibitor in Patients with Graves’ Disease

Tissue factor pathway inhibitor (TFPI) is present in a free-form and in lipoprotein-associated forms in plasma. In this study, the plasma concentrations of total TFPI (tTFPI) and free-form TFPI (fTFPI) were measured in 25 patients with Graves' disease and 25 age-matched healthy subjects, and the relationship between thyroid state and plasma TFPI was examined. Plasma concentrations (median) of tTFPI and fTFPI in Graves' patients who were hyperthyroid were significantly increased compared with Graves' patients who were euthyroid (152 ng/ml versus 124 ng/ml, p < 0.01 and 41.3 ng/ml versus 20.2 ng/ml, p < 0.0001, respectively), and control subjects (152 ng/ml versus 96 ng/ml, p < 0.0001 and 41.3 ng/ml versus 18.7 ng/ml, p < 0.0001, respectively). There was no significant difference in plasma fTFPI concentrations between the euthyroid group and the control group. Plasma fTFPI concentrations correlated closely with thyroid hormone (T3) levels in the patients (r = 0.559, p < 0.005). Serial measurement of individual patients revealed that plasma concentrations of fTFPI and tTFPI were significantly decreased, reaching normal control values upon attainment of euthyroidism. In conclusion, the close correlation between plasma fTFPI and serum thyroid hormone levels suggests that thyroid hormones might influence the synthesis or metabolism of TFPI on the surface of endothelial cells in patients with Graves' disease. This is the first report concerning high concentrations of plasma tTFPI in patients with hyperthyroidism.

Increased tissue factor pathway inhibitor in patients with acute myocardial infarction.

We examined hemostatic abnormalities in 23 patients with acute myocardial infarction (AMI), 10 with pulmonary embolism (PE), and 10 with deep vein thrombosis (DVT). At the onset of AMI, plasma levels of tissue-type plasminogen activator (t-PA), PA inhibitor-I (PAI-I), fibrin-D-dimer, thrombin-antithrombin complex (TAT), and plasmin-plasmin inhibitor complex (PPIC) were significantly increased. Both the plasma total TFPI and free-TFPI levels in the AMI patients were significantly higher than those in the healthy volunteers, PE patients, and DVT patients. There was no significant difference in total TFPI or free-TFPI among patients with PE, those with DVT, and healthy volunteers. One hour after percutaneous transluminal coronary angioplasty (PTCA) in the AMI group, the total TFPI level was further increased, and it was significantly reduced 24 hr after PTCA, to a level similar to that in healthy volunteers. Free-TFPI showed a pattern similar to that of total TFPI. The ratio of free-TFPI/total TFPI was highest 1 hr after PTCA. Increased TFPI in AMI patients might be released from ischemic tissues.