Plasma Thrombin-activatable Fibrinolysis Inhibitor Research Articles

Thrombin activatable fibrinolysis inhibitor plasma levels and TAFI Thr325Ile genetic polymorphism in a cohort of Egyptian sickle cell disease patients and impact on disease severity.

Thrombin is a critical protease modulating thrombosis as well as inflammation, which are one of the main pathophysiological mechanisms in sickle vasculopathy, and its levels were reported to be high in sickle cell disease (SCD). The thrombin-thrombomodulin complex activates the TAFI inhibitor of fibrinolysis, which acts by reducing plasmin affinity for its substrate thus hindering fibrinolysis. We aimed to determine the influence of the Thr325Ile single nucleotide polymorphism (SNP) on TAFI antigen levels and potential effects on the severity of SCD in a cohort of Egyptian patients. Genotyping of Thr325lle polymorphism using Taq-Man SNP genotyping assay and TAFI level measurement using an enzyme-linked immunosorbent assay were performed for 80 SCD patients (45 homozygous HbSS, 16 S/β0 and 19 Sβ+) as well as 80 age- and gender-matched healthy control subjects. Plasma TAFI levels were higher in SCD patients with Thr325Ile polymorphism, yet the difference was not statistically significant (p=.204). SCD patients with polymorphic genotypes had a greater number of hospital admissions (p=.03). Ten patients with acute chest syndrome had the homozygous polymorphic genotype (GG), and all patients with pulmonary hypertension had the polymorphic genotype (six were homozygous [GG] and five were heterozygous [GA]). Patients with SCD complicated with pulmonary hypertension showed significantly higher plasma TAFI levels (p=.044). The analysis of Thr325Ile polymorphisms combined with plasma TAFI levels suggests that the analyzed SNP could influence plasma TAFL levels and SCD disease severity and hospitalization rates, which could be predictors for complex disease.

Plasma thrombin-activatable fibrinolysis inhibitor and the 1040C/T polymorphism are risk factors for diabetic kidney disease in Chinese patients with type 2 diabetes.

Inflammatory and hemostatic disorders in diabetic microangiopathy (DMA) can be linked to thrombin-activatable fibrinolysis inhibitor (TAFI) and its own gene polymorphisms. Thus, the study aimed to investigate the associations of plasma TAFI and gene polymorphisms with DMA in Chinese patients with type 2 diabetes (T2D). Plasma TAFI of 223 patients with T2D was measured, and the genotypes and alleles of the 1040C/T, 438G/A, and 505G/A polymorphisms of the TAFI gene were analyzed. A ROC curve was constructed to evaluate the identifying power of TAFI between patients with T2D and DMA, and logistic regression analysis was used to observe the correlation of plasma TAFI and gene polymorphisms with the risk for DMA. Plasma TAFI was higher in patients with DMA than in patients with only T2D (p < 0.05). TAFI exhibited the largest area under ROC in identifying diabetic kidney disease (DKD) from only T2D (0.763, 95% CI [0.674-0.853], p < 0.01), and adjusted multivariate analysis showed a high odds ratio (OR: 15.72, 95% CI [4.573-53.987], p < 0.001) for DKD. Higher frequencies of the CT genotype and T allele of the 1040C/T polymorphism were found in DKD compared with only T2D (respectively p < 0.05), and the CT genotype exhibited a high OR (1.623, 95% CI [1.173-2.710], p < 0.05) for DKD. DKD patients with the CT genotype had higher plasma TAFI levels, while T2D and DKD patients with CC/TT genotypes had lower plasma TAFI levels. Plasma TAFI and the CT genotype and T allele of the 1040C/T polymorphism are independent risk factors for DKD in Chinese T2D patients.

Quality of glycemic control in type 2 diabetes mellitus (T2DM) and its association with markers of coagulation and inhibitors of fibrinolysis: A case–control study in the Upper West Region, Ghana

AbstractBackground and AimsType 2 diabetes mellitus (T2DM) individuals are at a higher risk of developing diabetes complications, with approximately 80% complication‐related mortality. The increased morbidity and mortality among T2DM patients are partly due to dysregulated hemostasis. This study determined the quality of glycemic control in T2DM and its association with markers of coagulation and inhibitors of fibrinolysis.MethodsThis case–control study recruited 90 participants involving: 30 T2DM patients with good glycemic control, 30 with poor glycemic control, and 30 nondiabetic subjects as controls at a Municipal Hospital in Ghana. Fasting blood glucose, glycated hemoglobin, activated partial thromboplastin time (APTT), prothrombin time (PT), calculated international normalized ratio (INR), and full blood count (FBC) were determined for each respondent. Plasma levels of plasminogen activator inhibitor‐1 (PAI‐1) and thrombin activatable fibrinolysis inhibitor (TAFI) were determined using the solid‐phase sandwich enzyme‐linked immunosorbent assay method. Data were analyzed using R language software.ResultsPlasma PAI‐1 antigen levels were significantly higher in the participants with poor glycemic control as compared to participants with good glycemic control (p &lt; 0.0001). There was no significant difference in plasma TAFI levels between the participants with poor glycemic control as compared to participants with good glycemic control (p = 0.900). T2DM patients had significantly shorter APTT, PT, and INR than controls (p &lt; 0.05). At a cut‐off of ≥161.70 pg/μL, PAI was independently associated with increasing odds (adjusted odds ratio = 13.71, 95% confidence interval: 3.67–51.26, p &lt; 0.0001) of poor glycemic control and showed the best diagnostic accuracy for poor glycemic control (area under the curve = 0.85, p &lt; 0.0001).ConclusionPAI‐1 levels were significantly increased in T2DM with poor glycemic control and emerged as the best predictor for poor glycemic control. Good glycemic management to control the plasma levels of PAI‐1 is required to prevent hypercoagulability and thrombotic disorders.

Serum thrombin-activatable fibrinolysis inhibitor levels and its relation with pathogenesis and bleeding and prognosis in patients with Crimean Congo hemorrhagic fever.

Crimean-Congo hemorrhagic fever (CCHF) is a viral hemorrhagic fever, which is common in Turkey and globally. The pathogenesis of coagulation disorders, which is seen in viral hemorrhagic fevers remains to be elucidated. Thrombin-activatable fibrinolysis inhibitor (TAFI) has a key role in this process In this study, we aimed to evaluate whether TAFI levels contributed to bleeding and whether it is related to prognosis in CCHF patients.Eighty-four patients older than 15 years of age, who were admitted to our hospital who had positive immunoglobulin M (enzyme-linked immunosorbent assay [ELISA]) and/or polymerase chain reaction test results for CCHF between 2009 and 2010, were included in the study. The control group included 30 healthy adults. The plasma TAFI levels were compared between patients and controls, and also between patients with bleeding and no bleeding, and between patients with mild-moderate and severe disease. The mean TAFI levels were lower in patients (mean: 87.82 ng/ml, median: 61.69 ng/ml (interquartile range [IQR] 30.49-537.95) than controls (mean: 313.5 ng/ml with a median: 338.5 ng/ml (IQR 182-418). However, median TAFI levels were significantly higher in patients with bleeding compared to those without bleeding (78.99 and 50.28 ng/ml, respectively; p = 0.032). Median IQR TAFI levels were similar between patients with mild-moderate and severe disease (64.72 (41.37-113.85), and, 58.66 (42.44-118.93) ng/ml, respectively; p = 0.09) and survivors and nonsurvivors (86.14 ± 77.98 and 103.48 ± 69.92, respectively; p = 0.3). Although TAFI levels were lower in the patients with CCHF compared to healthy controls, it does not seem to be a major player in the prognosis.

The G505A Nonsynonymous Single-Nucleotide Polymorphism (SNP) in TAFI, the Gene Encoding Thrombin-Activatable Fibrinolysis Inhibitor (TAFI) Is Pleiotropically Associated with TAFI Antigen Levels and Coronary Heart Disease (CHD) in Mexican Americans of South Texas

Studies have reported that the G505A nonsynonymous (ns)-SNP encoding the Ala147Thr amino acid substitution in TAFI, is associated with a reduction in risk of venous thrombosis and myocardial infarction. Interestingly, homozygosity for the A-allele (AA) of G505A is associated with increased TAFI antigen (TAFI:Ag) levels in plasma. In our study of the genetic determinants of cardiovascular disease (CVD) in Mexican Americans of South Texas, we performed an exome-wide scan in relation to plasma TAFI antigen levels in 784 individuals. While accounting for age, sex, and their interactions as confounders in linear mixed model, we found a heritability of 59% for TAFI:Ag levels (p=1.4E-19), and that ns-SNP G505A was the only variant showing exome-wide significance (p=3.5E-14; Figure A). Figure B shows the quantile-quantile distribution of the p-values from all the exome-wide tests. Clearly, the p-value distribution reveals that there is no systematic bias that may act to skew the p-values, and that the lone exception¾in agreement between observed and expected quantiles¾is due to this TAFI SNP, which strongly suggests a truly significant effect. Consistent with previous reports, the regression coefficient for G505A as a predictor of TAFI:Ag levels showed them to be increasing from the homozygous for the major G-allele (GG), to the heterozygous individuals (GA), to the individuals homozygous for the minor A-allele (AA) (Figure B). We also investigated if G505A is associated with our CHD variable. Using a statistical genetic model for the liability to disease conditional on a threshold, which is equivalent to a probit mixed model, we found that the G505A ns-SNP in TAFI, encoding TAFI Ala147Thr, is significantly associated with a reduction in the risk of CHD (p=0.002). As observed in existing literature, potential limitations of this study include the ELISA assay used for the quantification of TAFI levels. Some ELISA assays measure proTAFI, TAFIa, and TAFIi. However, recent evidence suggests that there may be cross reactivity between TAFIa and TAFIi. This can result in measuring ongoing TAFI activation peptides and elevated levels of TAFIa which ultimately goes on to make resistant fibrin. This is likely the marker that results in the increased risk of venous thromboembolism. To mitigate this confounding factor, an ELISA assay specific to measuring TAFI antigen is needed. In conclusion, we found that TAFI G505A is pleiotropically associated with TAFI:Ag levels and risk of CHD. [Display omitted] DisclosuresDeFronzo: AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; Boehringer-Ingelheim: Membership on an entity's Board of Directors or advisory committees, Research Funding; Intarcia: Membership on an entity's Board of Directors or advisory committees; Merck: Research Funding.

Quantitation of thrombin-activatable fibrinolysis inhibitor in human plasma by isotope dilution mass spectrometry

Measurement of Thrombin-activatable fibrinolysis inhibitor (TAFI) in human plasma is dependent on reproducible assays. To date, standards for measuring TAFI are frequently calibrated relative to pooled normal human plasma and arbitrarily assigned a potency of 100% TAFI, despite variation in TAFI concentrations between plasma pools. Alternatively, TAFI calibrators can be assigned a value in SI units but the approach used for value assignment is not consistent and furthermore, if purified TAFI is used to determine TAFI concentration in plasma, may be adversely affected by matrix effects. A TAFI plasma standard in mass units with traceability to the SI unit of mass is desirable.We report here the establishment of a quantitative mass spectrometry method for TAFI in plasma. Traceability is obtained by reference to calibrators that consist of blank plasma spiked with a defined amount of purified TAFI, value assigned by amino acid analysis. The calibrators are run alongside the samples, using the same preparation steps and conditions; an acetonitrile assisted tryptic digestion and multi-dimensional liquid chromatography (LC) separation followed by MRM-MS analysis.We measured the TAFI quantitatively in human plasma with reproducibility, reliability and precision, and demonstrated the applicability of this approach for value assigning a common reference standard.

Thrombin-Activatable Fibrinolysis Inhibitor (TAFI) Antigen Levels and TAFI Gene Polymorphisms in Patients with Budd-Chiari Syndrome and Portal Vein Thrombosis.

Background Budd-Chiari syndrome (BCS) and Portal Vein Thrombosis (PVT) have been associated with several hypercoagulable states. Thrombin-activatable fibrinolysis inhibitor (TAFI) potently attenuates fibrinolysis. Elevated TAFI antigen levels form a risk factor for deep venous thrombosis and are to a high extend genetically determined. To establish the pathogenetic role of TAFI in BCS and PVT, we studied TAFI antigen levels and gene polymorphisms in patients with BCS, PVT and matched controls.Methods In a multicenter case-control study, 39 patients with BCS, 85 patients with PVT and 118 population-based controls were identified. Plasma levels of TAFI antigen were determined by a commercially available ELISA and polymorphisms of the TAFI gene (TAFI 505A/G and TAFI 1040C/T) were analysed by PCR. Because TAFI antigen levels are decreased in patients with impaired liver synthesis, plasma levels were corrected for antithrombin activity levels. ANOVA techniques were used to correlate TAFI polymorphisms with TAFI antigen levels.Results Mean plasma TAFI antigen levels were significantly lower in BCS and/or PVT patients as compared to controls, even after adjusting for impaired liver function by antithrombin activity levels (all p<0.002). There was a strong correlation between the TAFI 505 A/G and TAFI 1040 C/T polymorphisms and plasma TAFI antigen levels in all groups (all p<0.001). The G-allele of the 505A/G polymorphism was associated with a low antigen level of TAFI. Carriers of the GG genotype had an increased risk for BCS and/or PVT (OR=4.4; 95% CI 1.5–12.6). Carriers of the G allele showed a risk of 4.1 (95% CI 1.5–11.5). For the 1040C/T polymorphism, the T allele was associated with lower levels of TAFI antigen, and carriers of at least one copy of the T allele showed an OR of 1.6 (95% CI 0.9–2.7).Conclusion We found lower TAFI levels in patients with BCS and/or PVT than in healthy controls. In addition two TAFI genotypes, associated with lower TAFI antigen levels were found more frequently in patients with BCS and/or PVT than in healthy controls. Therefore low TAFI levels appear to be a risk factor for the development of BCS and PVT. These results suggest a different pathogenetic mechanism of TAFI in BCS and PVT than in deep venous thrombosis.

Hypofibrinolysis is associated with the severity of Covid-19 infection: The role of obesity

Introduction: Obesity, by causing hypofibrinolysis and thrombotic complications, ought to be a risk factor in terms of disease severity and mortality in COVID-19 infection.We aim to investigate the effects of obesity on fibrinolytic system in coronavirus patients while studying the changes of major fibrinolytic inhibitors plasminogen activator inhibitor (PAI-1) and thrombin activatable fibrinolysis inhibitor (TAFI). Material and methods: Sixty-six patients and 21 healthy donors were investigated and observed until either their recovery or death. Body mass index (BMI) was calculated for each person and peripheral blood used for PAI-1 and TAFI measurements. PAI-1 antigen and TAFI activated/inactivated (TAFIa/i) were measured using ELISA kits. Results: PAI-1 antigen and TAFIa/i plasma levels are higher in patients than in control group (P<00001 for both).Patients needing ICU had higher TAFIa/i values than non-ICU patients. The 15 patients who died had higher TAFIa/i levels than those staying alive.Obese patients (BMI . 30) had higher PAI-1 levels than non-obese patients. TAFIa/i is associated with D-dimer, C-reactive protein (CRP), ferritin, creatinine and neutrophile count, whereas PAI-1 is associated only with the serum creatinine level. Conclusion: Our study shows that the levels of the major fibrinolytic inhibitors PAI 1 and TAFI increase in patients with COVID-19 infection, and proves for the first time that PAI 1 levels increase more in obese patients than in non-obese ones. It is also revealed that the plasma TAFI level is associated with the severity of COVID-19 infection, which suggests that the inhibitory treatments against TAFI should be effective in preventing thrombotic complications in the course of COVID-19 infection.

Activated platelet-based inhibition of fibrinolysis via thrombin-activatable fibrinolysis inhibitor activation system

AbstractOur previous real-time imaging studies directly demonstrated the spatiotemporal regulation of clot formation and lysis by activated platelets. In addition to their procoagulant functions, platelets enhanced profibrinolytic potential by augmenting the accumulation of tissue-type plasminogen activator (tPA) and plasminogen, in vivo in a murine microthrombus model, and in vitro in a platelet-containing plasma clot model. To clarify the role of thrombin-activatable fibrinolysis inhibitor (TAFI), which regulates coagulation-dependent anti-fibrinolytic potential, we analyzed tPA-induced clot lysis times in platelet-containing plasma. Platelets prolonged clot lysis times in a concentration-dependent manner, which were successfully abolished by a thrombomodulin-neutralizing antibody or an activated TAFI inhibitor (TAFIaI). The results obtained using TAFI- or factor XIII–deficient plasma suggested that TAFI in plasma, but not in platelets, was essential for this prolongation, though its cross-linkage with fibrin was not necessary. Confocal laser scanning microscopy revealed that fluorescence-labeled plasminogen accumulated on activated platelet surfaces and propagated to the periphery, similar to the propagation of fibrinolysis. Plasminogen accumulation and propagation were both enhanced by TAFIaI, but only accumulation was enhanced by thrombomodulin-neutralizing antibody. Labeled TAFI also accumulated on both fibrin fibers and activated platelet surfaces, which were Lys-binding-site-dependent and Lys-binding-site-independent, respectively. Finally, TAFIaI significantly prolonged the occlusion times of tPA-containing whole blood in a microchip-based flow chamber system, suggesting that TAFI attenuated the tPA-dependent prolongation of clot formation under flow. Thus, activated platelet surfaces are targeted by plasma TAFI, to attenuate plasminogen accumulation and fibrinolysis, which may contribute to thrombogenicity under flow.

A new pedigree with thrombomodulin‐associated coagulopathy in which delayed fibrinolysis is partially attenuated by co‐inherited TAFI deficiency

BackgroundThrombomodulin‐associated coagulopathy (TM‐AC) is a rare bleeding disorder in which a single reported p.Cys537* variant in the thrombomodulin gene THBD causes high plasma thrombomodulin (TM) levels. High TM levels attenuate thrombin generation and delay fibrinolysis. ObjectivesTo report the characteristics of pedigree with a novel THBD variant causing TM‐AC, and co‐inherited deficiency of thrombin‐activatable fibrinolysis inhibitor (TAFI). Patients/methodsIdentification of pathogenic variants in hemostasis genes by next‐generation sequencing and case recall for deep phenotyping. ResultsPedigree members with a previously reported THBD variant predicting p.Pro496Argfs*10 and chain truncation in TM transmembrane domain had abnormal bleeding and greatly increased plasma TM levels. Affected cases had attenuated thrombin generation and delayed fibrinolysis similar to previous reported TM_AC cases with THBD p.Cys537*. Coincidentally, some pedigree members also harbored a stop‐gain variant in CPB2 encoding TAFI. This reduced plasma TAFI levels but was asymptomatic. Pedigree members with TM‐AC caused by the p.Pro496Argfs*10 THBD variant and also TAFI deficiency had a partially attenuated delay in fibrinolysis, but no change in the defective thrombin generation. ConclusionsThese data extend the reported genetic repertoire of TM‐AC and establish a common molecular pathogenesis arising from high plasma levels of TM extra‐cellular domain. The data further confirm that the delay in fibrinolysis associated with TM‐AC is directly linked to increased TAFI activation. The combination of the rare variants in the pedigree members provides a unique genetic model to develop understanding of the thrombin‐TM system and its regulation of TAFI.

Is there thrombin-activatable fibrinolysis inhibitor in saliva?

The purpose of this study was to identify thrombin-activatable fibrinolysis inhibitor (TAFI) in saliva and to investigate the correlation between TAFI levels in saliva and plasma. Subjects included were healthy adults without diseases or medication that could affect coagulation. Samples of stimulated saliva and blood samples were obtained from 33 subjects. Levels of TAFI in saliva and plasma were analysed. The association between levels of TAFI in saliva and plasma was calculated using linear regression. Low levels of TAFIa/TAFIai were found in most saliva samples but only one sample had levels that were above the lower limit of detection of the assay used. TAFI (proenzyme) was not found in saliva, so no correlations could be calculated. In this study there was no indication that there is TAFI present in secreted saliva. Either TAFIa/TAFIai in saliva were much lower than in plasma and under the detection limit of the assay used, or there was no TAFIa/TAFIai in the saliva tested.

Plasma thrombin-activatable fibrinolysis inhibitor (TAFI) antigen levels in acromegaly patients in remission

Background/aimAcromegaly is associated with increased morbidity and mortality, mostly due to cardiovascular complications. Plasma thrombin-activatable fibrinolysis inhibitor (TAFI) antigen levels are associated with coagulation/fibrinolysis and inflammation. Plasma TAFI may play a role in arterial thrombosis in cardiovascular diseases. In this study, it was aimed to evaluate the thrombin-activatable fibrinolysis inhibitor (TAFI) antigen and homocysteine levels in patients with acromegaly and healthy control subjects.Materials and methodsPlasma TAFI antigen and homocysteine levels in 29 consecutive patients with acromegaly and 26 age-matched healthy control subjects were measured. All patients included in the study were in remission. The TAFIa/ai antigen in the plasma samples was measured using a commercially available ELISA kit.ResultsRoutine biochemical parameters, fasting blood glucose, prolactin, thyroid stimulating hormone, total-cholesterol, low density lipoprotein cholesterol, triglyceride, and homocysteine levels were similar in the 2 groups (P > 0.05), whereas the plasma TAFI antigen levels were significantly elevated in the acromegalic patients (154.7 ± 94.0%) when compared with the control subjects (107.2 ± 61.6%) (P = 0.033). No significant correlation was identified by Pearson’s correlation test between the plasma TAFI antigen and homocysteine levels (r = 0.320, P = 0.250).ConclusionA significant alteration in the plasma TAFI antigen levels was detected in acromegaly. Increased plasma TAFI antigen levels might aggravate prothrombotic and thrombotic events in patients with acromegaly.

Recent Advances in the Understanding of Thrombosis.

Recent Advances in the Understanding of Thrombosis.

Thrombin activatable fibrinolysis inhibitor as an indicator of the severity of acute pancreatitis.

Thrombin Activatable Fibrinolysis Inhibitor (TAFI), in addition to suppressing fibrinolysis, can be involved as a natural anti-inflammatory molecule in the inflammatory process in acute pancreatitis (AP). The goal of this study was to discover the significance of early determination of the values of TAFI in the assessment of the severity of AP. The prospective study included 92 patients with AP. In accordance with the revised Atlanta classification, we divided all patients into 3 groups (I-mild AP, II- moderate AP and III-severe AP). All patients were further classified into group A (mild AP) and group B (moderate and severe AP) with the aim of separating the patients with complicated and potentially bad prognosis. Biochemical markers, inflammatory biomarkers, coagulation parameters and TAFI were analyzed in all patients. The level of TAFI were significantly higher among the patients with the complicated form (group B) of AP (p=0.002). The analysis of the ROC curve in regard to the inflammatory biomarkers (fibronectin and CRP) has shown that TAFI possesses the best discriminatory ability for complicated forms of AP (AUC=0.724, p=0.013), with the sensitivity of 83.30% and the specificity of 56.00%. The level of TAFI in plasma is higher in patients with moderate or severe AP. Determining the level of TAFI as a single parameter has a greater significance in the early estimation of the severity of AP than inflammatory biomarkers that we have analyzed.

Dose-Response Relationship Between Thrombin-Activatable Fibrinolysis Inhibitor (TAFI) and Stroke: A Chinese Case-Control Study.

BackgroundBecause TAFI (thrombin-activatable fibrinolysis inhibitor) antigen varies widely among different populations, we performed this case-control study to explore the relationship between TAFI levels and stroke in a Chinese population.Material/MethodsOur population-based case-control study included 217 stroke patients and 218 healthy controls. The plasma TAFI level was measured by immune turbidimetry. Univariate and multivariate logistic regression analyses were used to analyze the association between different TAFI levels and stroke and its subtypes. Restricted cubic spline (RCS) combined with logistic regression analysis were used to explore the dose-response relationship between TAFI levels and stroke.ResultsThe plasma TAFI levels of cases were much higher than in the control group (p=0.038) and this difference persisted even after adjustment (OR=2.2). In the elderly (aged over 60) and female subgroups, TAFI levels in stroke patients were higher than those in controls, and the results were also noted in ischemic stroke. The dose-response curve showed that, as a whole, with the increase of TAFI levels, the relative risk of stroke first increased and then decreased (p=0.0127). Similarly, in general, with the increase of TAFI levels, the curve showed that the relative risk of ischemic stroke first increased and then decreased (p=0.0110).ConclusionsThere was a definite correlation between TAFI levels and stroke in this Chinese population, and with the increase of TAFI levels, the relative risk of stroke or ischemic stroke first increased and then decreased.

Activated TAFI Promotes the Development of Chronic Thromboembolic Pulmonary Hypertension: A Possible Novel Therapeutic Target.

Pulmonary hypertension is a fatal disease; however, its pathogenesis still remains to be elucidated. Thrombin-activatable fibrinolysis inhibitor (TAFI) is synthesized by the liver and inhibits fibrinolysis. Plasma TAFI levels are significantly increased in chronic thromboembolic pulmonary hypertension (CTEPH) patients. To determine the role of activated TAFI (TAFIa) in the development of CTEPH. Immunostaining showed that TAFI and its binding partner thrombomodulin (TM) were highly expressed in the pulmonary arteries (PAs) and thrombus in patients with CTEPH. Moreover, plasma levels of TAFIa were increased 10-fold in CTEPH patients compared with controls. In mice, chronic hypoxia caused a 25-fold increase in plasma levels of TAFIa with increased plasma levels of thrombin and TM, which led to thrombus formation in PA, vascular remodeling, and pulmonary hypertension. Consistently, plasma clot lysis time was positively correlated with plasma TAFIa levels in mice. Additionally, overexpression of TAFIa caused organized thrombus with multiple obstruction of PA flow and reduced survival rate under hypoxia in mice. Bone marrow transplantation showed that circulating plasma TAFI from the liver, not in the bone marrow, was activated locally in PA endothelial cells through interactions with thrombin and TM. Mechanistic experiments demonstrated that TAFIa increased PA endothelial permeability, smooth muscle cell proliferation, and monocyte/macrophage activation. Importantly, TAFIa inhibitor and peroxisome proliferator-activated receptor-α agonists significantly reduced TAFIa and ameliorated animal models of pulmonary hypertension in mice and rats. These results indicate that TAFIa could be a novel biomarker and realistic therapeutic target of CTEPH.

Plasma Thrombin-activatable Fibrinolysis Inhibitor Levels Correlate with the Disease Activity of Ulcerative Colitis.

Objective Patients with ulcerative colitis (UC) are at an increased risk for thromboembolic events, particularly in patients with extensive and active disease. To date, a few studies have been published on the role of thrombin-activatable fibrinolysis inhibitor (TAFI) in UC. However, there are no reports in the literature investigating the effect of UC treatment on plasma TAFI levels. Methods The plasma TAFI antigen levels were quantitatively determined using ELISA kits for 20 UC patients at activation and remission, along with 17 healthy controls. The association between the TAFI levels and inflammatory markers was assessed to determine UC activation. To predict and determine the activation of UC, the Truelove-Witts index and the endoscopic activation index (EAI) were used for each subject. Results The plasma TAFI levels were higher in UC patients at activation of the disease compared with the remission state and in healthy controls. Spearman's correlation analyses revealed that the WBC (r: 0.586, p<0.001), hsCRP (r: 0.593, p<0.001) and EAI (r: 0.721, p<0.001) were significantly correlated with the TAFI levels. The overall accuracy of TAFI in determining UC activation was 82.5% with a sensitivity, specificity, NPV and PPV of 80%, 85%, 81% and 84.2%, respectively (cut-off value: 156.2% and AUC: 0.879). Conclusion The present study demonstrates that the TAFI levels are elevated in the active state of UC. The assessment of TAFI levels in patients with UC in conjunction with other markers of inflammation may provide additional information for estimating UC activation and severity.

Signs of Hypofibrinolysis in Patients with Unprovoked Idiopathic Venous Thromboembolism

Background: The causes for venous thromboembolism (VTE) remain undetermined in at least 30% of patients with unprovoked VTE. Hypofibrinolysis may be associated to VTE, however the occurrence of hypofibrinolysis in patients with unprovoked, idiopathic, VTE is not well stablished.Aims: To evaluate whether hypofibrinolysis would be associated with unprovoked idiopathic VTE.Methods: Patients with a history of unprovoked VTE without acquired or inherited thrombophilia were included. Global tests of fibrinolysis, such as euglobolin lysis time (ELT) and lysis area on fibrin plate (LAFP), and specific tests of fibrinolysis, such as plasma activity plasminogen, a-2 antiplasmin (a2AP), plasminogen activatorinhibitor-1 (PAI-1), and thrombin activatable fibrinolysis inhibitor (TAFI), were performed in patients and healthy controls. We also analyzed the plasma activity of factor (F) XIII.Results: Thirty-one patients and fifty healthy controls were included. ELT results were higher in patients than in controls (median= 295 and IQ= 205-355 minutes vs. median=250 and IQ= 167-295 minutes, respectively, p = 0.006) and LAFP values were lower in patients compared to controls (median=81 and IQ= 56-110 vs. median= 95 and IQ 72-132 respectively, p = 0.0014), suggesting that they were experiencing a hypofibrinolytic state. Plasma activity of plasminogen (median= 131 and IQ= 119-141 vs. median=120 and IQ=111-137, respectively, p = 0.045) and FXIII (median= 103 and IQ 89-127 vs. median= 96 and IQ=80-105, respectively, p = 0.050), were higher in patients than in controls, whereas plasma activity of α-2AP was lower in patients (median= 124 and IQ 114-128 vs. median= 127 and IQ=121-133, p≤0.001). Interestingly, patient's median TAFI activity was lower than in controls (median=16 and IQ 13-18μg/mL vs. median= 19 and IQ= 17-21g/mL, p≤0.001). However, PAI-1 activity did not differ between groups.Conclusions: Hypofibrinolysis may occur in patients with unprovoked idiopathic VTE and may be detected by global tests of fibrinolysis. It is possible that hypofibrinolysis contribute to the pathogenesis of thrombosis in these selected cases. DisclosuresNo relevant conflicts of interest to declare.

Elevated thrombin activatable fibrinolysis inhibitor levels in women with polycystic ovary syndrome

Objective: The aim of the present study was to evaluate plasma concentrations of thrombin activatable fibrinolysis inhibitor (TAFI) in relation with hormonal, metabolic, and hemostatic profile in patients with and without polycystic ovary syndrome (PCOS).Study design: A total of 38 women with PCOS and 37 age and body mass index (BMI) matched controls were eligible for the study. Hirsutism scores, hormonal, metabolic, and hemostatic profile as well as TAFI levels were evaluated in each subject.Results: Women with PCOS exhibited higher plasma concentrations of TAFI levels than controls (107.42 ± 34.77% versus 91.86 ± 23.88%, p = 0.027). TAFI levels were significantly correlated positively with BMI, fasting insulin levels, modified Ferriman Gallwey scores and Homeostasis Model Assessment (HOMA) index, systolic blood pressure, and waist and hip circumferences, whereas negatively correlated with activated partial thromboplastin time (p < 0.05). However, after adjustment for all possible confounding factors, none of the parameters was significantly deterministic on TAFI levels.Conclusion: The data of the present study suggested that plasma TAFI levels were higher in women with PCOS as compared with healthy age and BMI-matched controls, indicating impaired fibrinolysis. This hypofibrinolytic state may be responsible for the increased cardiovascular disease risk in women with PCOS.

Thrombin-activatable fibrinolysis inhibitor Thr325Ile polymorphism and plasma level in breast cancer: A pilot study

This study aimed to investigate thrombin-activatable fibrinolysis inhibitor (TAFI) Thr325Ile polymorphism and TAFI antigen (Ag) levels in breast cancer (BC) in the Egyptian population to clarify their role in relation to BC. A group of 300 females was recruited in this study; of these 150 unrelated patients with different stages of BC and 150 age-matched healthy controls. Plasma TAFI Ag was measured by ELISA and TAFI Thr325Ile (rs1926447) polymorphism was genotyped using TaqMan single nucleotide polymorphism (SNP) genotyping assay. The results showed the genotypes of the minor allele; Thr/Ile (CT) and Ile/Ile (TT) were significantly more frequent in patients compared to control group (50.0% and 22.0% vs. 42.0% and 13.3%, respectively) and were also associated with BC susceptibility [OR=1.9 and 2.6; 95% CI: (1.1–3.3) and (1.3–5.5), respectively P=0.01]. Ile325 allele carriers were more frequent in cases than in controls (47.0% vs. 34.0%) [OR=1.7, (95% CI=1.2–2.4), P=0.001]. However, TAFI Thr325Ile polymorphism was not associated with BC stage or other clincopathological characteristics. TAFI Ag levels were correlated with advanced stages of BC, poor prognosis and risk of recurrence (P=0.02, P=0.04 and P <0.001, respectively) and Thr325Ile SNP was significantly correlated with TAFI antigen levels with the C/C genotype corresponding to the highest and the T/T genotype to the lowest TAFI antigen levels (P<0.001) in the study groups. In conclusion, this study showed for the first time that TAFI Thr325Ile polymorphism could have a contribution to BC susceptibility in our population. Furthermore, high TAFI plasma levels may serve as a predictor of poor prognosis in patients with BC.