Insulin resistance is associated with increased circulating level of thrombin-activatable fibrinolysis inhibitor in type 2 diabetic patients

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

Background

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).

Methods

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.

Results

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.

Conclusion

Plasma TAFI and the CT genotype and T allele of the 1040C/T polymorphism are independent risk factors for DKD in Chinese T2D patients.

The Cellular and Protein Arms of Coagulation in Diabetes: Established and Potential Targets for the Reduction of Thrombotic Risk

Diabetes is a metabolic condition with a rising global prevalence and is characterised by abnormally high blood glucose levels. Cardiovascular disease (CVD) accounts for the majority of deaths in diabetes and, despite improvements in therapy, mortality and hospitalisations in this cohort remain disproportionally higher compared to individuals with normal glucose metabolism. One mechanism for increased CVD risk is enhanced thrombosis potential, due to altered function of the cellular and acellular arms of coagulation. Different mechanisms have been identified that mediate disordered blood clot formation and breakdown in diabetes, including dysglycaemia, insulin resistance, and metabolic co-morbidities. Collectively, these induce platelet/endothelial dysfunction and impair the fibrinolytic process, thus creating a prothrombotic milieu. Despite these abnormalities, current antithrombotic therapies are largely similar in diabetes compared to those without this condition, which explains the high proportion of patients experiencing treatment failure while also displaying an increased risk of bleeding events. In this narrative review, we aimed to summarise the physiological functioning of haemostasis followed by the pathological effects of diabetes mellitus on platelets and the fibrin network. Moreover, we carefully reviewed the literature to describe the current and future therapeutic targets to lower the thrombosis risk and improve vascular outcomes in diabetes.

Elevated plasma factor XI predicts cardiovascular events in patients with type 2 diabetes: a long-term observational study

BACKGROUND

Type 2 diabetes mellitus (T2DM) patients are at high risk of cardiovascular (CV) events. Factor XI (FXI) is associated with arterial thromboembolism, including myocardial infarction (MI), stroke, and CV mortality. The role of FXI in T2DM is unknown. We investigated whether plasma FXI is associated with CV events in T2DM patients in long-term observation.

METHODS

In 133 T2DM patients (aged 66 ± 8 years, 40.6% women, median T2DM duration 5 [2-10] years) we assessed plasma FXI levels, along with fibrin clot properties, thrombin generation, and fibrinolysis proteins. A composite endpoint of MI, stroke, or CV death, as well as CV mortality alone were assessed during a median follow-up of 72 months.

RESULTS

Plasma FXI above the 120% upper normal limit was detected in 25 (18.8%) patients and showed positive association with LDL cholesterol and thrombin activatable fibrinolysis inhibitor, but not glycated hemoglobin, inflammatory markers or thrombin generation. The composite endpoint (n = 21, 15.8%) and CV death alone (n = 16, 12%) were more common in patients with elevated FXI (hazard ratio [HR] 10.94, 95% confidence interval [CI] 4.46-26.87, p < 0.001 and HR 7.11, 95% CI 2.61-19.31, p < 0.001, respectively). On multivariable analysis, FXI remained an independent predictor of the composite endpoint and CV death, regardless of concomitant coronary artery disease.

CONCLUSIONS

To our knowledge, this study is the first to show that in T2DM patients, elevated FXI could predict major CV events, including mortality, which suggest that anti-FXI agents might be a potential novel antithrombotic option in this disease.

ProCPU Is Expressed by (Primary) Human Monocytes and Macrophages and Expression Differs between States of Differentiation and Activation

Carboxypeptidase U (CPU, TAFIa, CPB2) is a potent attenuator of fibrinolysis that is mainly synthesized by the liver as its inactive precursor proCPU. Aside from its antifibrinolytic properties, evidence exists that CPU can modulate inflammation, thereby regulating communication between coagulation and inflammation. Monocytes and macrophages play a central role in inflammation and interact with coagulation mechanisms resulting in thrombus formation. The involvement of CPU and monocytes/macrophages in inflammation and thrombus formation, and a recent hypothesis that proCPU is expressed in monocytes/macrophages, prompted us to investigate human monocytes and macrophages as a potential source of proCPU. CPB2 mRNA expression and the presence of proCPU/CPU protein were studied in THP-1, PMA-stimulated THP-1 cells and primary human monocytes, M-CSF-, IFN-γ/LPS-, and IL-4-stimulated-macrophages by RT-qPCR, Western blotting, enzyme activity measurements, and immunocytochemistry. CPB2 mRNA and proCPU protein were detected in THP-1 and PMA-stimulated THP-1 cells as well as in primary monocytes and macrophages. Moreover, CPU was detected in the cell medium of all investigated cell types and it was demonstrated that proCPU can be activated into functionally active CPU in the in vitro cell culture environment. Comparison of CPB2 mRNA expression and proCPU concentrations in the cell medium between the different cell types provided evidence that CPB2 mRNA expression and proCPU secretion in monocytes and macrophages is related to the degree to which these cells are differentiated. Our results indicate that primary monocytes and macrophages express proCPU. This sheds new light on monocytes and macrophages as local proCPU sources.

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.

Neuroprotective Panel of Olive Polyphenols: Mechanisms of Action, Anti-Demyelination, and Anti-Stroke Properties

Neurological diseases such as stroke and multiple sclerosis are associated with high morbidity and mortality, long-term disability, and social and economic burden. Therefore, they represent a major challenge for medical treatment. Numerous evidences support the beneficial effects of polyphenols from olive trees, which can alleviate or even prevent demyelination, neurodegeneration, cerebrovascular diseases, and stroke. Polyphenols from olive oils, especially extra virgin olive oil, olive leaves, olive leaf extract, and from other olive tree derivatives, alleviate inflammation and oxidative stress, two major factors in demyelination. In addition, they reduce the risk of stroke due to their multiple anti-stroke effects, such as anti-atherosclerotic, antihypertensive, antioxidant, anti-inflammatory, hypocholesterolemic, hypoglycemic, and anti-thrombotic effects. In addition, olive polyphenols have beneficial effects on the plasma lipid profiles and insulin sensitivity in obese individuals. This review provides an updated version of the beneficial properties and mechanisms of action of olive polyphenols against demyelination in the prevention/mitigation of multiple sclerosis, the most common non-traumatic neurological cause of impairment in younger adults, and against cerebral insult with increasing incidence, that has already reached epidemic proportions.

Mathematical Modeling of Severe Acute Respiratory Syndrome Coronavirus 2 Infection Network with Cytokine Storm, Oxidative Stress, Thrombosis, Insulin Resistance, and Nitric Oxide Pathways

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a systemic disease affecting not only the lungs but also multiple organ systems. Clinical studies implicate that SARS-CoV-2 infection causes imbalance of cellular homeostasis and immune response that trigger cytokine storm, oxidative stress, thrombosis, and insulin resistance. Mathematical modeling can offer in-depth understanding of the SARS-CoV-2 infection and illuminate how subcellular mechanisms and feedback loops underpin disease progression and multiorgan failure. We report here a mathematical model of SARS-CoV-2 infection pathway network with cytokine storm, oxidative stress, thrombosis, insulin resistance, and nitric oxide (NO) pathways. The biochemical systems theory model shows autocrine loops with positive feedback enabling excessive immune response, cytokines, transcription factors, and interferons, which can imbalance homeostasis of the system. The simulations suggest that changes in immune response led to uncontrolled release of cytokines and chemokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor α (TNFα), and affect insulin, coagulation, and NO signaling pathways. Increased production of NETs (neutrophil extracellular traps), thrombin, PAI-1 (plasminogen activator inhibitor-1), and other procoagulant factors led to thrombosis. By analyzing complex biochemical reactions, this model forecasts the key intermediates, potential biomarkers, and risk factors at different stages of COVID-19. These insights can be useful for drug discovery and development, as well as precision treatment of multiorgan implications of COVID-19 as seen in systems medicine.

Hypofibrinolysis in type 2 diabetes and its clinical implications: from mechanisms to pharmacological modulation

A prothrombotic state is a typical feature of type 2 diabetes mellitus (T2DM). Apart from increased platelet reactivity, endothelial dysfunction, hyperfibrinogenemia, and hypofibrinolysis are observed in T2DM. A variety of poorly elucidated mechanisms behind impaired fibrinolysis in this disease have been reported, indicating complex associations between platelet activation, fibrin formation and clot structure, and fibrinolysis inhibitors, in particular, elevated plasminogen antigen inhibitor-1 levels which are closely associated with obesity. Abnormal fibrin clot structure is of paramount importance for relative resistance to plasmin-mediated lysis in T2DM. Enhanced thrombin generation, a proinflammatory state, increased release of neutrophil extracellular traps, elevated complement C3, along with posttranslational modifications of fibrinogen and plasminogen have been regarded to contribute to altered clot structure and impaired fibrinolysis in T2DM. Antidiabetic agents such as metformin and insulin, as well as antithrombotic agents, including anticoagulants, have been reported to improve fibrin properties and accelerate fibrinolysis in T2DM. Notably, recent evidence shows that hypofibrinolysis, assessed in plasma-based assays, has a predictive value in terms of cardiovascular events and cardiovascular mortality in T2DM patients. This review presents the current data on the mechanisms underlying arterial and venous thrombotic complications in T2DM patients, with an emphasis on hypofibrinolysis and its impact on clinical outcomes. We also discuss potential modulators of fibrinolysis in the search for optimal therapy in diabetic patients.

The relationship between insulin sensitivity and serum antithrombin 3 activity in patients with type 2 diabetes

BACKGROUND

Antithrombin 3 (AT3) is a physiological inhibitor of thrombin, and serum AT3 activity was found to decrease at the status of type 2 diabetes (T2D). T2D was presented with an increased risk of thrombotic complications at the background of impaired insulin sensitivity. The aim of this study was to investigate the relationship between insulin sensitivity indices and serum AT3 activity in patients with T2D.

METHODS

We conducted a cross-sectional study in patients with T2D who consented to participate in the study at the Endocrinology Department of Affiliated 2 Hospital of Nantong University from January 2015 to June 2018. All patients received serum AT3 activity test and 75 g oral glucose tolerance test (OGTT). Basal and systemic insulin sensitivity were assessed by homeostasis model assessment of insulin resistance (HOMA-IR) and Matsuda index (ISIMatsuda), respectively, from the OGTT. And other relevant clinical data were also collected.

RESULTS

Total of 1612 patients with T2D were enrolled in the study, with a mean age of 58.67 ± 13.09 years and a median diabetes duration of 6 years (interquartile range, 1-10 years). Across ascending quartiles of serum AT3 activity, HOMA-IR progressively decreased, while ISIMatsuda progressively increased (all P for trend < 0.001). Moreover, serum AT3 activity was negatively correlated with HOMA-IR (r = -0.189, P < 0.001) and positively correlated with ISIMatsuda (r = 0.221, P < 0.001). After adjusting for other metabolic risk factors, hemostatic parameters and glucose-lowering therapies by multivariate linear regression analysis, HOMA-IR (β = -0.185, t = -5.960, P < 0.001) and ISIMatsuda (β = 0.197, t = 6.632, P < 0.001) remained independently associated with the serum AT3 activity in patients with T2D, respectively.

CONCLUSIONS

Reduced basal and systemic insulin sensitivity are associated with decreased serum AT3 activity in patients with T2D.

Plasma fibrin clot properties and cardiovascular mortality in patients with type 2 diabetes: a long-term follow-up study

Background

Patients with type 2 diabetes mellitus (T2DM) are at high risk of cardiovascular mortality, but the mechanisms behind this remain unclear. Prothrombotic fibrin clot properties have been shown in T2DM and cardiovascular disease. We hypothesized that formation of denser clots, which are resistant to fibrinolysis, has a negative impact on cardiovascular mortality in T2DM.

Methods

We studied 133 T2DM patients aged 43–83 years. Plasma fibrin clot turbidity, permeation, compaction, and efficiency of clot lysis using 3 assays including the determination of maximum concentration (D-D_max) and rate of increase in D-dimer concentration (D-D_rate) released during tissue plasminogen activator-induced degradation, were evaluated at the time of enrollment, along with thrombin generation and fibrinolytic proteins. During a median follow-up period of 72 months, cardiovascular mortality was recorded.

Results

Cardiovascular deaths (n = 16, 12%) occurred more frequently in patients with increased D-D_max (> 4.26 mg/l, hazard ratio [HR] 5.43, 95% confidence interval [CI] 1.99–14.79), or decreased D-D_rate (< 0.07 mg/l/min, HR 2.97, 95% CI 1.07–8.23), or increased peak thrombin (> 283.5 nM, HR 5.65, 95% CI 2.07–15.51). These predictors had an even more potent impact on cardiovascular mortality in patients with prior cardiovascular disease (64.7%) and with corresponding risks as follows: HR 6.18, 95% CI 2.02–18.96; HR 8.98, 95% CI 2.99–26.96; and HR 5.35, 95% CI 1.62–17.72, respectively. Other investigated fibrin variables and fibrinolytic proteins did not associate with cardiovascular mortality. In multivariable analysis, cardiovascular mortality was predicted by D-D_max > 4.26 mg/l, age > 65 years, prior cardiovascular disease, and C-reactive protein > 3 mg/l.

Conclusions

This study is the first to show that formation of denser fibrin clots resistant to fibrinolysis could be a risk factor for long-term cardiovascular mortality in T2DM.

Carboxypeptidase U (CPU, TAFIa, CPB2) in Thromboembolic Disease: What Do We Know Three Decades after Its Discovery?

Procarboxypeptidase U (proCPU, TAFI, proCPB2) is a basic carboxypeptidase zymogen that is converted by thrombin(-thrombomodulin) or plasmin into the active carboxypeptidase U (CPU, TAFIa, CPB2), a potent attenuator of fibrinolysis. As CPU forms a molecular link between coagulation and fibrinolysis, the development of CPU inhibitors as profibrinolytic agents constitutes an attractive new concept to improve endogenous fibrinolysis or to increase the efficacy of thrombolytic therapy in thromboembolic diseases. Furthermore, extensive research has been conducted on the in vivo role of CPU in (the acute phase of) thromboembolic disease, as well as on the hypothesis that high proCPU levels and the Thr/Ile325 polymorphism may cause a thrombotic predisposition. In this paper, an overview is given of the methods available for measuring proCPU, CPU, and inactivated CPU (CPUi), together with a summary of the clinical data generated so far, ranging from the current knowledge on proCPU concentrations and polymorphisms as potential thromboembolic risk factors to the positioning of different CPU forms (proCPU, CPU, and CPUi) as diagnostic markers for thromboembolic disease, and the potential benefit of pharmacological inhibition of the CPU pathway.

A high-fat diet delays plasmin generation in a thrombomodulin-dependent manner in mice

Obesity is a prevalent prothrombotic risk factor marked by enhanced fibrin formation and suppressed fibrinolysis. Fibrin both promotes thrombotic events and drives obesity pathophysiology, but a lack of essential analytical tools has left fibrinolytic mechanisms affected by obesity poorly defined. Using a plasmin-specific fluorogenic substrate, we developed a plasmin generation (PG) assay for mouse plasma that is sensitive to tissue plasminogen activator, α2-antiplasmin, active plasminogen activator inhibitor (PAI-1), and fibrin formation, but not fibrin crosslinking. Compared with plasmas from mice fed a control diet, plasmas from mice fed a high-fat diet (HFD) showed delayed PG and reduced PG velocity. Concurrent to impaired PG, HFD also enhanced thrombin generation (TG). The collective impact of abnormal TG and PG in HFD-fed mice produced normal fibrin formation kinetics but delayed fibrinolysis. Functional and proteomic analyses determined that delayed PG in HFD-fed mice was not due to altered levels of plasminogen, α2-antiplasmin, or fibrinogen. Changes in PG were also not explained by elevated PAI-1 because active PAI-1 concentrations required to inhibit the PG assay were 100-fold higher than circulating concentrations in mice. HFD-fed mice had increased circulating thrombomodulin, and inhibiting thrombomodulin or thrombin-activatable fibrinolysis inhibitor (TAFI) normalized PG, revealing a thrombomodulin- and TAFI-dependent antifibrinolytic mechanism. Integrating kinetic parameters to calculate the metric of TG/PG ratio revealed a quantifiable net shift toward a prothrombotic phenotype in HFD-fed mice. Integrating TG and PG measurements may define a prothrombotic risk factor in diet-induced obesity.

Poor glycaemic control contributes to a shift towards prothrombotic and antifibrinolytic state in pregnant women with type 1 diabetes mellitus

OJECTIVES

Thrombotic and antifibrinolytic influence of Diabetes mellitus type 1 (T1DM) on haemostasis have been well demonstrated. There has been no research assessing the influence of poor glycemic control on thrombus formation under flow conditions in vitro or in pregnant type 1 diabetic women to date.

PATIENTS/METHODS

This study compared singleton pregnant T1DM women (n = 21) and control pregnant subjects without any metabolic disease (n = 15). The T1DM group was divided into two subgroups of sufficient (SGC-DM; HbA1c ≤6,5%,n = 15) and poor glycaemic control (PGC-DM; HbA1c >6,5%,n = 6). Evaluation of the whole blood thrombogenicity we assessed using T-TAS® at a shear rate of 240 s-1 (Total-Thrombus Analysis System, Zacros, Japan).

RESULTS

Blood clot formation initiation time (T10) was significantly shortened in PGC-DM subgroup when compared to SGC-DM subgroup (p = 0,03). The area under the curve (AUC30) of blood clot time formation and the MPV (mean platelet volume) values were substantially higher in the PGC-DM subgroup in comparison to the SGC-DM group (p = 0,03). Negative correlations were noted between HbA1c and T10 values (p = 0,02) and between T10 and MPV values in the T1DM group (p = 0,04).

CONCLUSIONS

Poor glycaemic control in T1DM subjects triggers a shift towards a prothrombotic and antifibrinolytic state. This phenomenon can be detected using the novel system for quantitative assessment of the platelet thrombus formation process under flow conditions in vitro. The alteration of T-TAS values in PGC-DM subgroup proves that a poor glycemic control-related shift of the equilibrium toward thrombogenesis occurs in this group of patients. Our findings need a further elucidation in research on more massive data sets to be confirmed.

Coagulatory Defects in Type-1 and Type-2 Diabetes

Diabetes (both type-1 and type-2) affects millions of individuals worldwide. A major cause of death for individuals with diabetes is cardiovascular diseases, in part since both types of diabetes lead to physiological changes that affect haemostasis. Those changes include altered concentrations of coagulatory proteins, hyper-activation of platelets, changes in metal ion homeostasis, alterations in lipid metabolism (leading to lipotoxicity in the heart and atherosclerosis), the presence of pro-coagulatory microparticles and endothelial dysfunction. In this review, we explore the different mechanisms by which diabetes leads to an increased risk of developing coagulatory disorders and how this differs between type-1 and type-2 diabetes.

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

Background/aim

Acromegaly 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 methods

Plasma 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.

Results

Routine 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).

Conclusion

A 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.

Predictors of neutrophil extracellular traps markers in type 2 diabetes mellitus: associations with a prothrombotic state and hypofibrinolysis

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with a hypercoagulable state and increased neutrophil extracellular traps formation (NETosis). We investigated predictors of NETosis and cell death markers in circulating blood and their association with a prothrombotic state in T2DM.

METHODS

In a cross-sectional study involving 113 T2DM patients aged 63.7 ± 8.2 years, we investigated citrullinated histone H3 (H3Cit), cell-free deoxyribonucleic acid (cfDNA), myeloperoxidase, neutrophil elastase, and inflammation markers, along with thrombin generation (TG), plasma clot lysis time (CLT), clot permeability (Ks) and fibrinolysis inhibitors.

RESULTS

On multivariate logistic regression analysis adjusted for age and gender, predictors of high H3Cit (≥ 7.36 ng/mL, upper quartile) were: glycated hemoglobin (HbA1c) ≥ 7.0% and interleukin-6. Interleukin-6 was also found to be a predictor of high cfDNA (≥ 2.84 µg/mL, upper quartile) along with glucose. Citrullinated histone H3 and cfDNA correlated positively with CLT and inversely with Ks, while TG associated solely with cfDNA. These associations were not seen with myeloperoxidase and neutrophil elastase. Patients with previous myocardial infarction (n = 21, 18.6%) had higher H3Cit (+108%, p < 0.001) and cfDNA (+45%, p = 0.022). On multivariable analysis adjusted for potential confounders, H3Cit and cfDNA, along with plasminogen activator inhibitor-1 and concomitant cardiovascular disease, were predictors of CLT. Citrullinated histone H3 alone was a predictor of Ks and only cfDNA was a predictor of peak thrombin generated.

CONCLUSIONS

In T2DM, NETosis detectable in circulating blood is associated with inflammatory state and a prothrombotic state, especially hypofibrinolysis.

A conceptual framework for predicting and addressing the consequences of disease-related microvascular dysfunction

OBJECTIVE

A growing body of evidence indicates that impaired microvascular perfusion plays a pathological role in a number of diseases. This manuscript aims to better define which aspects of microvascular perfusion are important, what mass transport processes (eg, insulin action, tissue oxygenation) may be impacted, and what therapies might reverse these pathologies.

METHODS

We derive a theory of microvascular perfusion and solute flux drawing from established relationships in mass transport and anatomy. We then apply this theory to predict relationships between microvascular perfusion parameters and microvascular solute flux.

RESULTS

For convection-limited exchange processes (eg, pulmonary oxygen uptake), our model predicts that bulk blood flow is of primary importance. For diffusion-limited exchange processes (eg, insulin action), our model predicts that perfused capillary density is of primary importance. For convection/diffusion co-limited exchange processes (eg, tissue oxygenation), our model predicts that various microvascular perfusion parameters interact in a complex, context-specific manner. We further show that our model can predict established mass transport defects in disease (eg, insulin resistance in diabetes).

CONCLUSIONS

The contributions of microvascular perfusion parameters to tissue-level solute flux can be described using a minimal mathematical model. Our results hold promise for informing therapeutic interventions targeting microvascular perfusion.

Angiotensin-converting enzyme inhibitors attenuate propofol-induced pro-oxidative and antifibrinolytic effect in human endothelial cells

Introduction:

The aim of this study was to investigate the effects of plasma and tissue angiotensin-converting enzyme inhibitors (ACE-Is) against propofol-induced endothelial dysfunction and to elucidate the involved mechanisms in vitro.

Materials and methods:

We examined the effects of propofol (50 μM), quinaprilat and enalaprilat (10⁻⁵ M) on fibrinolysis (t-PA, PAI-1, TAFI antigen levels), oxidative stress parameters (H₂O₂ and MDA antigen levels and SOD and NADPH oxidase mRNA levels) and nitric oxide bioavailability (NO₂/NO₃ concentration and NOS expression at the level of mRNA) in human umbilical vein endothelial cells (HUVECs).

Results:

We found that both ACE-Is promoted similar endothelial fibrinolytic properties and decreased oxidative stress in vitro. Propofol alone increased the release of antifibrinolytic and pro-oxidative factors from the endothelium and increased mRNA iNOS expression. We also found that the incubation of HUVECs in the presence of propofol following ACE-Is pre-incubation caused weakness of the antifibrinolytic and pro-oxidative potential of propofol and this effect was similar after both ACE-Is.

Conclusions:

This observation suggests that the studied ACE-Is exerted protective effects against endothelial cell dysfunction caused by propofol, independently of hemodynamics.

Hypofibrinolysis in diabetes: a therapeutic target for the reduction of cardiovascular risk

An enhanced thrombotic environment and premature atherosclerosis are key factors for the increased cardiovascular risk in diabetes. The occlusive vascular thrombus, formed secondary to interactions between platelets and coagulation proteins, is composed of a skeleton of fibrin fibres with cellular elements embedded in this network. Diabetes is characterised by quantitative and qualitative changes in coagulation proteins, which collectively increase resistance to fibrinolysis, consequently augmenting thrombosis risk. Current long-term therapies to prevent arterial occlusion in diabetes are focussed on anti-platelet agents, a strategy that fails to address the contribution of coagulation proteins to the enhanced thrombotic milieu. Moreover, antiplatelet treatment is associated with bleeding complications, particularly with newer agents and more aggressive combination therapies, questioning the safety of this approach. Therefore, to safely control thrombosis risk in diabetes, an alternative approach is required with the fibrin network representing a credible therapeutic target. In the current review, we address diabetes-specific mechanistic pathways responsible for hypofibrinolysis including the role of clot structure, defects in the fibrinolytic system and increased incorporation of anti-fibrinolytic proteins into the clot. Future anti-thrombotic therapeutic options are discussed with special emphasis on the potential advantages of modulating incorporation of the anti-fibrinolytic proteins into fibrin networks. This latter approach carries theoretical advantages, including specificity for diabetes, ability to target a particular protein with a possible favourable risk of bleeding. The development of alternative treatment strategies to better control residual thrombosis risk in diabetes will help to reduce vascular events, which remain the main cause of mortality in this condition.

PI3-Kinase Inhibitor LY294002 Repressed the Expression of Thrombin-Activatable Fibrinolysis Inhibitor in Human Hepatoma HepG2 Cells

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a carboxypeptidase B-like proenzyme biosynthesized in the liver and released into the blood circulation. Activated TAFI (TAFIa) has been implicated as an important player in maintaining the balance between blood coagulation and fibrinolysis. In the present study, regulation of TAFI (CPB2) gene expression was investigated using cultured human hepatoma HepG2 cells. HepG2 cells were treated with the phosphoinositide 3-kinase (PI3K) inhibitor LY294002, and the levels of TAFI antigen and CPB2 mRNA were measured. HepG2 cells treated with LY29400 decreased their release of TAFI antigen into the conditioned medium (CM). In parallel, there were decreased levels of CPB2 mRNA and TAFI antigen in the cells. However, CPB2 gene promoter activity was not influenced by treatment of the cells with LY294002. The half-life of the CPB2 transcript was shortened by treatment with LY294002 compared with control. The present results suggest that the PI3K inhibitor LY294002 suppresses expression of TAFI, a prothrombotic factor, by decreasing the stability of CPB2 transcripts.

Decrements in the Thrombin Activatable Fibrinolysis Inhibitor (TAFI) Levels in Association with Orlistat Treatment in Obesity

Obesity and its associated metabolic complications can impair the physiologic regulation of fibrinolysis, leading to a hyper coagulable state. We aimed to assess circulating thrombin activatable fibrinolysis inhibitor (TAFI) levels in obese female patients and to test the effects of orlistat-induced weight loss on basal TAFI concentrations. Obese female outpatients age 18 and older, with a body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters) of at least 30, were included into the study. Thirteen nonobese (median BMI, 22.60 kg/m2) age-matched females were taken as controls. Plasma TAFI levels were measured before orlistat administration and after 6 months of orlistat treatment in the obese group and only one measurement was done in the control group. Twenty-seven obese patients were recruited into the study. The median TAFI level of the control group was 124.00; this value was significantly lower than the basal TAFI level of the obese group (p < 0.001). TAFI levels after orlistat therapy were statistically significantly lower than basal TAFI levels (p < 0.001) in the obese group. Hemostatic abnormalities including TAFI alterations represent a link between obesity and vascular thrombosis. Effective interventions should be considered in improving the obesity-associated prothrombotic risk profile.

Structure-function relationships in thrombin-activatable fibrinolysis inhibitor

Thrombin-activatable fibrinolysis inhibitor (TAFI) is an important regulator in the balance of coagulation and fibrinolysis. TAFI is a metallocarboxypeptidase that circulates in plasma as zymogen. Activated TAFI (TAFIa) cleaves C-terminal lysine or arginine residues from peptide substrates. The removal of C-terminal lysine residues from partially degraded fibrin leads to reduced plasmin formation and thus attenuation of fibrinolysis. TAFI also plays a role in inflammatory processes via the removal of C-terminal arginine or lysine residues from bradykinin, thrombin-cleaved osteopontin, C3a, C5a and chemerin. TAFI has been studied extensively over the past three decades and recent publications provide a wealth of information, including crystal structures, mutants and structural data obtained with antibodies and peptides. In this review, we combined and compared available data on structure/function relationships of TAFI.

Effect of single nucleotide polymorphism in thrombin-activatable fibrinolysis inhibitor on the risk of diabetic macrovascular disease

Hypofibrinolysis is commonly found in patients with diabetes mellitus and is associated with the increased risk for many diabetic complications. An important inhibitor of fibrinolysis, thrombin-activatable fibrinolysis inhibitor (TAFI), participates in hypofibrinolysis in diabetes mellitus and may be involved in diabetic macrovascular disease. The present study was designed to determine whether TAFI polymorphisms (505G/A and 1040C/T) and TAFI levels are correlated with the development of type 2 diabetes mellitus (T2DM) and macrovascular diseases (MVDs). A total of 249 clinical samples were collected, including 102 healthy individuals (H group), 44 T2DM patients without MVD (T group) and 103 T2DM patients with MVD (M group). The 505G/A polymorphism was equally represented in the three groups. In contrast, analysis of the 1040C/T polymorphism revealed a statistically lower percentage of the T allele in the M group than in the H group (P = 0.014). This difference was due to decreased T/T homozygotes in the M groups compared with the H group (P = 0.029). The antigen TAFI level was 31.72 ± 13.64% in the H group, 62.56 ± 18.77% in the T group (P < 0.05, compared with the H group) and 63.70 ± 15.76% in the M group (P < 0.05, compared with the H group). As high plasma TAFI level is associated with the increasing risk of T2DM, it may thus serve as a potential marker for the diagnosis of T2DM.

Type 2 diabetes as a modifier of fibrin clot properties in patients with coronary artery disease

Altered fibrin clot structure has been reported both in patients with coronary artery disease (CAD) and those with type 2 diabetes mellitus (DM2). The aim of the present study was to evaluate plasma fibrin clot permeability and susceptibility to lysis in patients with DM2 and CAD. We studied 132 consecutive CAD patients, including 67 subjects with DM2, scheduled for elective coronary artery bypass grafting surgery. Ex vivo plasma fibrin clot permeability (K(s)) and lysis time (t(50%)) induced by 1 μg/mL recombinant tissue plasminogen activator (tPA), along with plasma levels of plasminogen activator inhibitor-1 (PAI-1), thrombin activatable fibrinolysis inhibitor (TAFI), tPA, von Willebrand factor (vWF), P-selectin, soluble CD40 ligand (sCD40L), were measured. Diabetic and non-diabetic patients did not differ in regard to demographics and remaining cardiovascular risk factors. Concomitant DM2 was associated with higher glucose (+24.3%, p < 0.001), fibrinogen (+9.0%, p = 0.037), PAI-1 (+58.7%, p < 0.001), tPA (+24.0%, p < 0.001) and P-selectin (+12.2%, p < 0.001). Compared with the non-diabetic group, the CAD patients with DM2 had lower K(s) (-6.1%, p = 0.02) and prolonged t(50%) (+5.1%, p = 0.04). Multiple regression analysis of the whole study group showed that vWF, PAI-1, fibrinogen and DM2 were the independent predictors of t(50%) (R(2) = 0.58, p < 0.001), while only vWF was an independent predictor of K(s) (R(2) = 0.22, p < 0.001). This study indicates that DM2 is potent enough to unfavorably affect plasma fibrin clot characteristics despite abnormal clot phenotype typically observed in CAD. Of note, platelet and endothelial markers appear to contribute to fibrin clot properties in CAD concomitant with DM2.

Levels of thrombin activatable fibrinolysis inhibitor in gestational diabetes mellitus

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a procarboxypeptidase, which is synthesised in liver and activated by thrombin and the thrombin-thrombomodulin complex. TAFI suppresses fibrinolysis by removing carboxy-terminal lysine residues from partially degraded fibrin. In this study we aimed to assess the circulating levels of TAFI antigen, 'a fibrinolytic parameter' in women with gestational diabetes (GDM). Thirty-four pregnant women with GDM and 50 pregnant women with normal glucose tolerance were included in the study. Plasma TAFI antigen levels were significantly higher in pregnant women with GDM when compared with controls. Increased TAFI levels may contribute to the decreased fibrinolytic potency, causing a thrombophilic state. GDM is regarded as a specific form of diabetes, and it could in addition be a predictor of type 2 diabetes mellitus in the future and the risk of complications due to hypercoagulability increases in this disease. Increased TAFI levels may also have a role in increased risk of hypercoagulability.

Conditioned media from (pre)adipocytes stimulate fibrinogen and PAI-1 production by HepG2 hepatoma cells

Background:

Obesity is associated with a prothrombotic state, which may contribute to the increased risk of thrombotic events.

Objective:

To assess the effects of (pre)adipocyte-derived adipokines on fibrinogen, plasminogen activator inhibitor-1 (PAI-1) and tissue factor (TF) production by hepatocytes.

Methods:

HepG2 hepatocytes were incubated with conditioned media (CM) derived from preadipocytes and adipocytes, which had been untreated or prestimulated with tumor necrosis factor (TNF)-α, interleukin (IL)-1β or IL-6. After 24 h, supernatants and cell lysates were harvested for measurement of fibrinogen, PAI-1 and TF.

Results:

(Pre)adipocyte CM significantly enhanced the production of PAI-1 by HepG2 cells 2.5- to 4.4-fold. CM from cytokine-stimulated (pre)adipocytes significantly induced fibrinogen secretion 1.5- to 4.2-fold. TF production was not affected by the CM. After specific depletion of TNF-α, IL-1β or IL-6 from the CM, IL-6 was shown to be the most prominent stimulus of fibrinogen secretion and IL-1β of PAI-1 secretion. In addition, fibrinogen, PAI-1 and tissue factor production was evaluated by direct stimulation of HepG2 cells with TNF-α, IL-1β or IL-6. IL-6 enhanced fibrinogen synthesis 4.3-fold (P<0.01), whereas IL-1β induced PAI-1 production 5.0-fold (P<0.01). Gene expression analyses showed that TNF-α and IL-1β stimulate the adipocyte expression of TNF-α, IL-1β and IL-6. Cytokine stimulation of adipocytes may thus have induced an inflammatory response, which may have stimulated fibrinogen and PAI-1 production by HepG2 cells more potently.

Conclusions:

SGBS (pre)adipocytes release cytokines that increase the production of fibrinogen and PAI-1 by HepG2 cells. IL-6 and IL-1β produced by (pre)adipocytes were the strongest inducers of fibrinogen and PAI-1 secretion, respectively.

Is there any role of thrombin activatable fibrinolysis inhibitor in the development of a hypercoagulable state in gastric cancer

Background

The purpose of this study was to investigate plasma levels of thrombin activatable fibrinolysis inhibitor (TAFI) and TAFI’s relationship with coagulation markers (prothrombin fragment 1 + 2) in gastric cancer patients.

Methods

Thirty-three patients with gastric adenocarcinoma and 29 healthy control subjects were prospectively enrolled in the study. Patients who had a history of secondary malignancy, thrombosis related disease, oral contraceptive use, diabetes mellitus, chronic renal failure or similar chronic metabolic disease were excluded from the study. A fasting blood sample was drawn from patients to determine the plasma levels of TAFI and Prothrombin Fragment 1 + 2 (F 1 + 2). In addition, data on patient age, sex, body mass index (BMI) and stage of disease were recorded. The same parameters, except stage of disease, were also recorded for the control group. Subsequently, we assessed the difference in the levels of TAFI and F 1 + 2 between the patient and control groups. Moreover, we investigated the relation of TAFI and F 1 + 2 levels with age, sex, BMI and stage of disease in the gastric cancer group.

Results

There were no statistical differences in any demographic variables (age, gender and BMI) between the groups (Table 1). The mean plasma TAFI levels of the gastric cancer group (69.4 ± 33.1) and control group (73.3 ± 27.5) were statistically similar (P = 0.62). The mean plasma F 1 + 2 level in the gastric cancer group was significantly higher than for those in the control group (549.7 ± 325.3 vs 151.9 ± 67.1, respectively; P < 0.001). In the gastric cancer group, none of the demographic variables (age, gender and BMI) were correlated with either TAFI or F 1 + 2 levels. Also, no significant associations were found between the stage of the cancer and either TAFI or F 1 + 2 levels.

Conclusion

In our study, TAFI levels of gastric cancer patients were similar to healthy subjects. The results of our study suggest that TAFI does not play a role in pathogenesis of the hypercoagulable state in gastric cancer patients.

Genetic variation in thrombin-activatable fibrinolysis inhibitor is associated with the risk of diabetic nephropathy

Diabetic nephropathy is a kidney disease or damage that results as a complication of diabetes, especially Type 2 diabetes, while albuminuria is an early marker for diabetic nephropathy as it can predict cardiovascular events and mortality in diabetic patients. A potent inhibitor of fibrinolysis, the thrombin-activatable fibrinolysis inhibitor (TAFI) has been isolated and characterized from human plasma. We investigated the associations of the activity-related variants in the TAFI coding gene (505A/G,1040C/T) with the risk of diabetic nephropathy by examining 297samples including 140 health controls and 157 confirmed diabetic nephropathy patients. Diabetic nephropathy grades were further categorized by the urine albumin excretion (UAE)-to-creatinine ratios (ACR). We found little difference that was statistically significant in terms of 505A/G among patients and controls. While at 1040C/T, the detected frequency for the T allele in the group of diabetic nephropathy patients was significantly smaller than that of the control group (15.6% vs 25.7%, respectively; p<0.05). This was due to the relative decrease of T/T homozygotes in the patients (p<0.05, 95% odds ratio 0.28, confidence interval 0.11-0.70). Surprisingly, the difference was only observed with initial diabetic nephropathy stages. This study clearly indicates that, at 1040C/T, the frequency for the T allele is strongly associated with increased risk for diabetic nephropathy in a subset of the general population, implying that the T allele confers protection against the onset of diabetic nephropathy only in homozygosity and may function as a recessive trait.

The relationship among TAFI, t-PA, PAI-1 and F1 + 2 in type 2 diabetic patients with normoalbuminuria and microalbuminuria

Disturbances of coagulation and fibrinolysis in type 2 diabetes mellitus (DM2) contribute to increased rates of macrovascular complications such as myocardial infarction and ischemic stroke. The aim of the study was to investigate the relationship among plasminogen activator inhibitor 1 (PAI-1), thrombin-activable fibrinolysis inhibitor (TAFI), tissue plasminogen activator (t-PA), prothrombin fragments 1+2 (F1+2), glycemic control, hypertension, sex and body mass index (BMI) in DM2 patients with normoalbuminuria and microalbuminuria. Forty-two normoalbuminuric (NAU), 42 microalbuminuric (MAU) patients with DM2 and 42 blood donors as control group were enrolled. TAFI, PAI-1, t-PA and F1+2 were assessed by enzyme-linked immunosorbent assay (ELISA) in all patients. TAFI was significantly increased in the MAU group, PAI-1 and F1+2 were increased in both groups and t-PA was not elevated in either group compared to controls. We found positive correlations in the NAU: TAFI and fibrinogen (r=0.65, P=0.02), PAI-1 and triglycerides (r=0.67, P=0.01), in the MAU: TAFI and F1+2 (r=0.48, P=0.02), TAFI and systolic blood pressure (r=0.53, P=0.01), PAI-1 and BMI (r=0.43, P<0.05). We found decreased fibrinolysis in DM2 patients presented with increased PAI-1 in both NAU and MAU. Hypofibrinolysis in MAU is further accented by the elevation of TAFI. TAFI-mediated inhibition of fibrinolysis in DM2 is regulated independently from PAI-1. Patient[Combining Acute Accent]s sex does not affect diabetes-related changes in hemostasis and fibrinolysis.

Plasma thrombin-activatable fibrinolysis inhibitor levels are not associated with glucose intolerance and subclinical atherosclerosis in women with previous gestational diabetes

We aimed to determine plasma thrombin-activatable fibrinolysis inhibitor (TAFI) antigen levels in women with previous gestational diabetes mellitus (GDM) and to evaluate the possible association of plasma TAFI with glucose intolerance and markers of subclinical atherosclerosis. This cross-sectional study was performed in 111 women with previous GDM and 60 controls. Glucose intolerance was evaluated. Homeostasis model assessment score was calculated. Circulating lipids, interleukin-6, matrix metalloproteinase-1, fibrinogen, plasminogen activator inhibitor-1, and TAFI antigen levels were assayed. Carotid intima media thickness (IMT) was measured. Women with previous GDM had increased levels of atherosclerosis markers and carotid IMT. On the other hand, plasma TAFI antigen levels were similar (P = .395). Thrombin-activatable fibrinolysis inhibitor was not associated with the indices of insulin resistance, glucose intolerance, markers of atherosclerosis, and carotid IMT. Our data demonstrated that plasma TAFI was not altered in women with previous GDM. TAFI was not associated with glucose intolerance and subclinical atherosclerosis.

Plasma thrombin-activatable fibrinolysis inhibitor (TAFI) antigen levels in diabetic foot ulcers

Plasma TAFI may participate in arterial thrombosis in cardiovascular diseases (CVD) and may be involved in the mechanism of vascular endothelial damage in diabetic patients. The aim of this study was to investigate the association of plasma TAFI antigen level in the development of diabetic foot ulcer in Type 2 diabetes. The TAFI antigen levels were determined in 50 patients with diabetic foot ulcers and 34 patients without diabetic foot ulcers and 25 healthy individuals. We measured TAFIa/ai antigen in plasma samples with a commercially available ELISA Kit. Diabetic foot ulcer group and diabetic group were similar in terms of mean age and sex distribution. Diabetes duration, retinopathy, neuropathy, macrovascular disease and infection were related to diabetic foot ulcers. HbA1c, HDL-cholesterol and Folic Acid levels were decreased in the diabetic foot ulcer group. TAFI levels were 99.44 ± 55.94% in control group, 135.21 ± 61.05% in diabetic foot ulcer group, 136.75 ± 59.38% in diabetic group and was statistically different (P < 0.05). But no difference was seen in TAFI levels between the diabetic foot ulcer group and diabetic group (P > 0.05). No significant difference in plasma TAFI levels were seen between diabetic foot ulcer stages. TAFI antigen levels are increased in Type 2 diabetic patients, but are not related to diabetic foot ulcer development.

Role of adipose tissue in haemostasis, coagulation and fibrinolysis

Obesity is associated with an increased incidence of insulin resistance (IR), type 2 diabetes mellitus and cardiovascular diseases. The increased risk for cardiovascular diseases could partly be caused by a prothrombotic state that exists because of abdominal obesity. Adipose tissue induces thrombocyte activation by the production of adipose tissue-derived hormones, often called adipokines, of which some such as leptin and adiponectin have been shown to directly interfere with platelet function. Increased adipose tissue mass induces IR and systemic low-grade inflammation, also affecting platelet function. It has been demonstrated that adipose tissue directly impairs fibrinolysis by the production of plasminogen activator inhibitor-1 and possibly thrombin-activatable fibrinolysis inhibitor. Adipose tissue may contribute to enhanced coagulation by direct tissue factor production, but hypercoagulability is likely to be primarily caused by affecting hepatic synthesis of the coagulation factors fibrinogen, factor VII, factor VIII and tissue factor, by releasing free fatty acids and pro-inflammatory cytokines (tumour necrosis factor-alpha, interleukin-1beta and interleukin-6) into the portal circulation and by inducing hepatic IR. Adipose tissue dysfunction could thus play a causal role in the prothrombotic state observed in obesity, by directly and indirectly affecting haemostasis, coagulation and fibrinolysis.

Biochemical characterization of bovine plasma thrombin-activatable fibrinolysis inhibitor (TAFI)

Background

TAFI is a plasma protein assumed to be an important link between coagulation and fibrinolysis. The three-dimensional crystal structures of authentic mature bovine TAFI (TAFIa) in complex with tick carboxypeptidase inhibitor, authentic full lenght bovine plasma thrombin-activatable fibrinolysis inhibitor (TAFI), and recombinant human TAFI have recently been solved. In light of these recent advances, we have characterized authentic bovine TAFI biochemically and compared it to human TAFI.

Results

The four N-linked glycosylation sequons within the activation peptide were all occupied in bovine TAFI, similar to human TAFI, while the sequon located within the enzyme moiety of the bovine protein was non-glycosylated. The enzymatic stability and the kinetic constants of TAFIa differed somewhat between the two proteins, as did the isoelectric point of TAFI, but not TAFIa. Equivalent to human TAFI, bovine TAFI was a substrate for transglutaminases and could be proteolytically cleaved by trypsin or thrombin/solulin complex, although small differences in the fragmentation patterns were observed. Furthermore, bovine TAFI exhibited intrinsic activity and TAFIa attenuated tPA-mediated fibrinolysis similar to the human protein.

Conclusion

The findings presented here suggest that the properties of these two orthologous proteins are similar and that conclusions reached using the bovine TAFI may be extrapolated to the human protein.

Thrombin activatable fibrinolysis inhibitor and other hemostatic parameters in patients with polycystic ovary syndrome

OBJECTIVES

To investigate the plasma levels of thrombin-activatable fibrinolysis inhibitor (TAFI) in women with polycystic ovary syndrome (PCOS) and its correlation with various metabolic, hormonal and hemostatic parameters.

METHODS

Forty-eight women with PCOS and 43 age- and BMI-matched ovulatory controls were recruited during a 20-month study period. Blood samples were drawn for all tests, which included plasma lipids and lipoproteins, reproductive hormones, glucose, insulin, TAFI antigen concentration, plasminogen activator inhibitor-1 (PAI-1) activity, fibrinogen concentration, thrombomodulin, thrombin-antithrombin (TAT) complexes, D-dimer, Protein C Antigen, Protein S Antigen, Antithrombin III (AT III) and activated protein C (APC) resistance.

RESULTS

Plasma TAFI levels of PCOS patients were found to be significantly higher than in healthy controls (93.8%+/-30.6%vs. 79.8% +/- 22.4%, p < 0.05). Plasma levels of D-dimer, AT III, PAI-1 and thrombomodulin were also significantly higher in women with PCOS compared with healthy controls. All the other hemostatic parameters (including TAT complexes; Protein C; APC; and Protein S) were comparable between the two study groups.

CONCLUSION

This study showed that plasma levels of TAFI, PAI-1, D-dimer, AT III and thrombomodulin were significantly increased in women with PCOS compared with age- and BMI-matched controls.

Fenofibrate improves endothelial function and decreases thrombin-activatable fibrinolysis inhibitor concentration in metabolic syndrome

Procoagulant state, inflammation, and endothelial dysfunction have been documented in metabolic syndrome. Endothelial dysfunction is a strong predictor of cardiovascular events. Studies on the association of thrombin-activatable fibrinolysis inhibitor and thrombosis are still controversial, but substantial evidence suggests that increased thrombin-activatable fibrinolysis inhibitor or thrombin-activatable fibrinolysis inhibits or protects against arterial thrombosis. This study aimed to assess concomitantly the effects of fenofibrate therapy on thrombin-activatable fibrinolysis inhibitor concentrations and endothelial functions in patients with metabolic syndrome. Twenty-five patients (16 women; mean age 50.4 +/- 7.0) were enrolled in the study. Plasma thrombin-activatable fibrinolysis inhibitor, C-reactive protein, and fibrinogen levels were measured before fenofibrate administration and after 8 weeks of fenofibrate treatment. Endothelial function was assessed by endothelial-dependent flow-mediated dilatation from brachial artery. Pretreatment (baseline) thrombin-activatable fibrinolysis inhibitor level was 52.3 (1.2-119.7) decreasing to 7.7 (0.9-51.2; P < 0.001) after 8 weeks of fibrate treatment. Endothelial functions, which were measured with flow-mediated dilatation, were significantly improved after treatment (mean flow-mediated dilatation was 6.76 +/- 2.21 at baseline and 10.66 +/- 1.17% after 8 week of fenofibrate treatment, P < 0.001). Fenofibrate decreases thrombin-activatable fibrinolysis inhibitor levels and improves endothelial function in metabolic syndrome and, thus, suggests a potential for protection against cardiovascular effects. Further studies are warranted to confirm the effects of fibrates on thrombin-activatable fibrinolysis inhibitor and for conclusive evidence on the association between thrombin-activatable fibrinolysis inhibitor and thrombosis.

Thrombin activatable fibrinolysis inhibitor activity, thrombin-antithrombin complex and D-dimer levels in preterm neonates with early respiratory distress syndrome

Intraalveolar fibrin deposition found in neonates with respiratory distress syndrome (RDS) is explained by the activation of the coagulation system and inefficient fibrinolysis. However, thrombin activatable fibrinolysis inhibitor activity (TAFIa), an inhibitor of fibrinolysis, and the ratio of D-dimer to thrombin-antithrombin complex (D-dimer/TAT), an index of fibrinolytic activity, have not been reported previously in neonatal RDS. Aim of this study is to evaluate the influence of plasma TAFIa levels on the fibrinolytic state in neonatal RDS. The RDS group (Group 1) consisted of 29 neonates, and 18 neonates served as the control group (Group 2). Plasma TAFIa levels and D-dimer/TAT ratios were evaluated in all neonates in the first 6 hr of life. Neonates in the RDS group were further divided into two subgroups; Group 1a consisted of 12 neonates with evidence of mild asphyxia (Apgar score at 5 min <7 and cord pH <7.26), and Group 1b consisted of 17 nonasphyxiated neonates. No significant difference was found in TAFIa levels and D-dimer/TAT ratios between Groups 1 and 2 [214% (56.2-361%) and 124.3 (4.4-3,921) in Group 1 and 201% (60.3-381%) and 147 (5.9-1,426) in Group 2]. There were negative correlations between cord pH and TAFIa levels in both groups. Increased TAFIa levels and decreased D-dimer/TAT ratios and platelet counts were detected in mildly asphyxiated neonates when compared with nonasphyxiated ones. TAFIa is not responsible for the hypofibrinolytic state reported in RDS. However, asphyxia influences TAFIa levels and increased TAFIa levels depress fibrinolysis.

Plasminogen activator inhibitor-1 and thrombin activatable fibrinolysis inhibitor levels in non-alcoholic steatohepatitis

AIM

This study was conducted to demonstrate the plasminogen activator inhibitor- 1 (PAI-1) and thrombin activatable fibrinolysis inhibitor antigen (TAFI-Ag) levels in non-alcoholic steatohepatitis (NASH).

MATERIALS AND METHODS

Twenty-seven patients with biopsy-proven NASH and 18 healthy controls (HC) were recruited for the study. Anthropometric data, liver histology (no.=20) and laboratory parameters including PAI-1 and TAFI-Ag assessments were recorded.

RESULTS

When compared with HC, patients with NASH had higher body weight, higher waist circumference, elevated blood pressure, higher fasting plasma glucose (FPG) levels and higher homeostasis model assessment (HOMA) scores. The mean plasma PAI-1 levels of patients was found to be higher than HC (87.60 ng/ml vs 30.84 ng/ml p=0.000) and mean plasma TAFI-Ag levels of patients was found to be significantly lower (8.69 microg/ml vs 12.19 microg/ml p=0.000). PAI-1 levels were correlated with systolic blood pressure, age, body weight, transaminases, waist circumference, FPG, body mass index, and HOMA score. TAFI-Ag levels were found to be negatively correlated with transaminases, waist circumference, and body weight. In multiple regression analysis, BMI was the independent variable effecting PAI-1 levels. We did not show any association between PAI-1, TAFI-Ag, disease activity score and fibrosis score. HOMA was the independent variable effecting liver fibrosis in our patients.

CONCLUSION

In this study we demonstrated that patients with biopsy-proven NASH had higher PAI-1 and lower TAFI-Ag expression than HC. Elevated levels of PAI-1 in NASH is the consequence of insulin resistance state. Lower TAFI-Ag levels may be related to the overactivation of TAFI pathway resulting in TAFI-Ag depletion. Furthermore, liver function disturbances may impair TAFI production in NASH. We also showed that NASH patients even with slight elevations of transaminases feature marked insulin resistance and components of metabolic syndrome.

Molecular analysis of the human thrombin-activatable fibrinolysis inhibitor gene promoter

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a carboxypeptidase B-like pro-enzyme that, once activated, attenuates fibrinolysis. Little is presently known of the factors that regulate expression of CPB2, the gene encoding TAFI. This study identified 10 potential transcription factor binding sites (denoted A-J) within the proximal promoter region of CPB2, spanning nucleotides -425 to +21; two of these represent previously-described binding sites for CCAAT/enhancer binding protein and glucocorticoid receptor. We identified additional transcription factors that bind within the proximal CPB2 promoter, namely, nuclear factor-Y (NF-Y) and hepatocyte nuclear factor-1alpha (HNF-1alpha). Binding of NF-Y to the region between nucleotides -76 to -59 (Site B) is important for basal CPB2 promoter activity; NF-Y may be a key factor for the recruitment of the transcriptional machinery to the TAFI gene promoter. HNF-1alpha binds at the interface between Sites C and B. Transient transfections of CPB2 promoter-reporter constructs showed that HNF-1alpha binding is essential for the activity of this promoter in HepG2 cells, indicating that HNF-1alpha is involved in the liver-specific expression of CPB2.

Comparison of the effects of pioglitazone and voglibose on circulating total and high-molecular-weight adiponectin, and on two fibrinolysis inhibitors, in patients with Type 2 diabetes

BACKGROUND

To investigate short-term effects of pioglitazone and voglibose on serum concentrations of both total and high-molecular-weight (HMW) adiponectin measured with a novel sandwich enzyme-linked immunosorbent assay (ELISA) ,and on plasma fibrinolysis indicators, in Type 2 diabetic patients with inadequate glycaemic control on sulphonylureas.

METHODS

Thirty-four diabetic patients were randomized to receive pioglitazone or voglibose treatment for 12 weeks, after which serum HMW adiponectin was measured. Plasma plasminogen activator inhibitor (PAI) 1 and thrombin-activatable fibrinolysis inhibitor (TAFI), a recently identified inhibitor of fibrinolysis, were measured as fibrinolysis inhibitors.

RESULTS

At baseline, serum HMW adiponectin correlated negatively with plasma TAFI in all patients with Type 2 diabetes (r = -0.367, P = 0.0423). Both groups showed similar improvements in glycaemic control. Serum total and HMW adiponectin increased in patients treated with pioglitazone, but did not change in patients treated with voglibose. The HMW : total adiponectin ratio increased significantly after treatment with pioglitazone (P = 0.0004). The change in HbA(1c) correlated negatively with changes in serum HMW adiponectin in patients treated with pioglitazone (r = -0.694, P = 0.0034). Plasma PAI-1 and TAFI did not change with pioglitazone treatment.

CONCLUSION

Increased serum HMW adiponectin may contribute to the improvement in glycaemic control after pioglitazone treatment. Plasma PAI-1 and TAFI were unchanged by either drug.

D-dimer identifies stages in the progression of diabetes mellitus from family history of diabetes to cardiovascular complications

AIM

The aim of the study was to ascertain whether there is variation in the fibrinolytic/coagulation component of diabetes associated with disease progression to macrovascular complications and whether D-dimer can discriminate such variation.

METHODS

A total of 343 participants were selected based on clinical status and divided into 7 groups: control, family history of diabetes, pre-diabetes with/without CVD, diabetes with/without CVD and CVD only. Plasma D-dimer was tested. Statistical analysis was performed on log normalised data by ANOVA, Fisher's LSD post hoc test. After the initial analysis, data were classified and re-analysed by quartiles, interquartile range and 95(th) percentile.

RESULTS

An overall significant difference between groups (p<0.002) and a steady rise in D-dimer levels that became increasingly higher than control as the disease progressed from pre-diabetes to cardiovascular complications was observed. A statistically significant difference was observed between control versus diabetes (p<0.0005). Analysis of data by quartiles and percentiles gave qualitatively similar results, but a greater significant difference between control versus pre-diabetes at 3rd quartile and interquartile range (p<0.014).

CONCLUSION

We report changes in D-dimer levels that may indicate diabetes disease progression to macrovascular complications. Using D-dimer in conjunction with other biomarkers to identify stages of disease progression, commencing from pre-diabetes and continuing to development of asymptomatic and clinical cardiovascular disease in diabetes mellitus, is worthy of consideration.

Elevated thrombin activatable fibrinolysis inhibitor (TAFI) antigen levels in overt and subclinical hypothyroid patients were reduced by levothyroxine replacement

The influence of hypothyroidism on haemostasis is an active research area. Not only bleeding tendency but also hypercoagulable states have been reported in hypothyroid patients. Decreased and increased fibrinolytic activity in hypothyroid patients has been shown in several studies. Thrombin activatable fibrinolysis inhibitor (TAFI) is an inhibitor of fibrinolysis, which has been recently isolated from human plasma. The aim of our study was to determine plasma TAFI antigen levels in overt and subclinical hypothyroidism, and to investigate the effect of levothyroxine treatment on TAFI levels. The study was performed in age- and sex-matched 30 overt hypothyroid, 30 subclinical hypothyroid patients, and 30 healthy controls. Blood samples were obtained from patients with overt and subclinical hypothyroidism before levothyroxine replacement, and one month after achieving a euthyroid state with levothyroxine. TAFI antigen levels were measured using Enzyme-Linked ImmunoSorbent Assay kits (Affinity Biologicals; Ontario, Canada). In baseline evaluation both the overt and subclinical hypothyroid groups had higher TAFI antigen levels than control group (p<0.05). High levels of TAFI antigen were correlated with the degree of thyroid failure. After achieving euthyroid state with levothyroxine replacement, TAFI antigen levels decreased significantly in patients with overt and subclinical hypothyroidism (p<0.05). Our data suggest that there are elevated plasma levels of TAFI antigen both in overt and subclinical hypothyroidism, which may be associated with hypofibrinolysis and elevated risk of thrombosis. Normalization of thyroid state by levothyroxine replacement seems to be effective in lowering of TAFI antigen levels in hypothyroidism.

Fine mapping of quantitative trait nucleotides underlying thrombin-activatable fibrinolysis inhibitor antigen levels by a transethnic study

Recent studies revisiting the association between plasma thrombin-activatable fibrinolysis inhibitor (TAFI) Ag levels and polymorphisms of the CPB2 gene (coding for TAFI) suggested that TAFI Ag levels were influenced by 2 major quantitative trait nucleotides (QTNs) in European whites. However, the strong linkage disequilibrium (LD) between CPB2 polymorphisms in European whites did not allow one to distinguish which polymorphisms could be the putative QTNs. To get a better insight into the identification of QTNs, a transethnic haplotype analysis contrasting 2 populations of African and European subjects was performed using 13 CPB2 polymorphisms. Results of the haplotype analyses suggested that 3 QTNs had independent effects and explained about 15% of the TAFI variability, consistently in the 2 populations. The lower LD observed in the African population enabled us to identify the 1583T>A SNP located in 3'UTR as one of these QTNs, whereas the -2599C>G and -2345--2344insG SNPs located in the 5' region might be the 2 other QTNs. A phylogenetic study suggested that these 3 polymorphisms occurred before the period of migration "out of Africa." Although this transethnic comparison contributed to better map the putative CPB2 QTNs, further studies are required to clarify the role of the promoter region.

Metabolic syndrome accompanied by hypercholesterolemia is strongly associated with proinflammatory state and impairment of fibrinolysis in patients with type 2 diabetes: synergistic effects of plasminogen activator inhibitor-1 and thrombin-activatable fibrinolysis inhibitor

OBJECTIVE

To determine whether plasma concentrations of thrombin-activatable fibrinolysis inhibitor (TAFI) in patients with type 2 diabetes were associated with components of metabolic syndrome (MS), including high-sensitivity C-reactive protein (hs-CRP), plasminogen activator inhibitor (PAI)-1, and LDL cholesterol.

RESEARCH DESIGN AND METHODS

We studied 136 consecutive patients with type 2 diabetes. Diagnosis of MS was diagnosed by current criteria. Hypercholesterolemia (HC) was defined as serum LDL cholesterol >140 mg/dl (3.6 mmol/l) or treatment with a statin. For comparisons, diabetic patients were divided into four groups: those with no MS and no HC (n = 38), with MS but not HC (n = 39), with no MS but with HC (n = 26), and with both MS and HC (n = 33).

RESULTS

Considering all patients with type 2 diabetes, plasma PAI-1 was strongly associated with MS components such as BMI, triglyceride, alanine aminotransferase, a homeostasis model assessment of insulin resistance, and hs-CRP. Plasma TAFI only correlated positively and independently with LDL cholesterol. Plasma concentrations of plasmin-alpha2-antiplasmin complex (PAP), a measure of fibrinolytic activity in blood, showed a significant negative correlation with plasma PAI-1 but not TAFI. Diabetic patients with both MS and HC had the highest serum hs-CRP concentrations and the lowest plasma PAP concentrations.

CONCLUSIONS

LDL cholesterol is a main determinant of plasma TAFI in patients with type 2 diabetes. Coexistence of MS and HC synergistically accelerates inflammation and impairment of fibrinolysis via elevated concentrations of both TAFI and PAI-1, which inhibit fibrinolysis.