Factor VIIa-antithrombin complexes in patients with non-neoplastic portal vein thrombosis with and without cirrhosis

Gut dysbiosis, endotoxemia and clotting activation: A dangerous trio for portal vein thrombosis in cirrhosis

Liver cirrhosis (LC) is associated with portal venous thrombosis (PVT) in roughly 20% of cirrhotic patients but the underlying mechanism is still unclear. Low-grade endotoxemia by lipopolysaccharides (LPS), a component of outer gut microbiota membrane, is detectable in the portal circulation of LC and could predispose to PVT. LPS may translocate into systemic circulation upon microbiota dysbiosis-induced gut barrier dysfunction, that is a prerequisite for enhanced gut permeability and ensuing endotoxemia. Experimental and clinical studies provided evidence that LPS behaves a pro-thrombotic molecule so promoting clotting and platelet activation. Experiments conducted in the portal circulation of cirrhotic patients showed the existence of LPS-related enhanced thrombin generation as well as endothelial dysfunction, venous stasis, and platelet activation. The review will analyze 1) the pro-thrombotic role of endotoxemia in the context of LC 2) the biological plausibility linking endotoxemia with PVT and 3) the potentially interventional tools to lower endotoxemia and eventually hypercoagulation.

Aptamer-modified FXa generation assays to investigate hypercoagulability in plasma from patients with ischemic heart disease

BACKGROUND

High plasma levels of activated Factor VII-Antithrombin complex (FVIIa-AT) have been associated with an increased risk of cardiovascular mortality in patients with stable coronary artery disease (CAD).

OBJECTIVES

To investigate if FVIIa-AT levels are associated with activated factor X generation (FXaG) in modified assays.

PATIENTS/METHODS

Forty CAD patients were characterized for FVIIa-AT levels by ELISA and for FXaG in plasma. Novel fluorogenic FXaG assays, based on aptamers inhibiting thrombin and/or tissue factor pathway inhibitor (TFPI), were set up.

RESULTS

FXaG correlated with FVIIa-AT levels (R_AUC = 0.393, P = 0.012). The combination of thrombin inhibition and FXaG potentiation by using anti-thrombin and anti-TFPI aptamers, respectively, favors the study of time parameters. The progressive decrease in lag time from the lowest to the highest FVIIa-AT quartile was magnified by combining TFPI and thrombin inhibitory aptamers, thus supporting increased FXaG activity in the coagulation initiation phase. By exploring FXaG rates across FVIIa-AT quartiles, the largest relative differences were detectable at the early times (the highest versus the lowest quartile; 5.0-fold, P = 0.005 at 45 s; 3.5-fold, P = 0.001 at 55 s), and progressively decreased over time (2.3-fold, P = 0.002 at 75 s; 1.8-fold, P = 0.008 at 95 s; 1.6-fold, P = 0.022 at 115 s). Association between high FVIIa-AT levels and increased FXaG was independent of F7 -323 A1/A2 polymorphism influencing FVIIa-AT levels.

CONCLUSIONS

High FVIIa-AT plasma levels were associated with increased FXaG. Hypercoagulability features were specifically detectable in the coagulation initiation phase, which may have implications for cardiovascular risk prediction by either FVIIa-AT complex measurement or modified FXaG assays.

Portal vein thrombosis in cirrhotic patients - it is always the small pieces that make the big picture

Portal vein thrombosis (PVT) is a frequent and serious complication in patients with liver cirrhosis (LC). Recently, a new classification of PVT was proposed, although the functional component was not completed included. The status of liver disease (compensated/decompensated) should be added to this classification. Reduced portal flow velocity and the acquired hypercoagulable status associated with LC are the main risk factors for PVT development, although endothelial dysfunction may play an important role that needs to be further evaluated. The European Association for the Study of the Liver and the American Association for the Study of Liver Disease recommend that the anticoagulant treatment should be consider in cirrhotic patients with PVT. Low molecular weight heparin and vitamin K antagonists proved their efficacy and relatively safety in PVT treatment, although in addition to recanalization rates, more complex end-points such as mortality and decompensation rate should be evaluated. The new oral anticoagulant therapies offers the advantage of oral administration in the absence of laboratory monitoring, however, there are a few reports regarding their use in cirrhotic patients, most of them referring to compensated isolated cases. Transjugular intrahepatic portosystemic shunt could be an alternative if thrombosis progresses despite anticoagulatant therapy and/or when PVT is associated with portal hypertension complications. The aim of this editorial is to discuss the different aspects of pathophysiology, clinical relevance, diagnosis and management of PVT in patients with LC.

Non-neoplastic Portal Vein Thrombosis in HCV Cirrhosis Patients: Is it an Immuno-Inflammatory Disorder?

BACKGROUND AND AIMS

Portal vein thrombosis (PVT) is a critical complication in cirrhotic patients. We explored the role of the activated factor VII-antithrombin (FVIIa-AT) complex and enhanced monocytic tissue factor (TF) expression in the development and prediction of non-neoplastic PVT in cirrhotic patients.

MATERIAL AND METHODS

A total of 30 HCV-cirrhosis patients were included in our study. They were compared to 35 cirrhotic patients without PVT, 15 non-cirrhotic patients with PVT, and 15 healthy controls. The plasma level of the FVIIa-AT complexes was analyzed by ELISA. MIF CD142, CD86, and HLA-DR on monocytes (CD14) were determined by flow cytometry.

RESULTS

Compared with cirrhotic patients without PVT, cirrhotic patients with PVT had comparable plasma values of FVIIa, AT, and the FVIIa-AT complex. However, they had significantly lower values compared to non-cirrhotic patients with PVT and healthy controls. Cirrhotic patients with PVT had increased monocytic TF expression (MIF CD142) compared to non-PVT cirrhotic patients and healthy controls [86.5 (93.5) vs. 18 (32.0) and 11.0 (6.0), respectively; p < 0.001 for each]. However, cirrhosis PVT could not be distinguished from non-cirrhosis PVT. The area under the ROC curve of MIF CD142 was 0.759 (0.641- 0.876; p = 0.000) at an optimal cut-off value of 45, which yielded a sensitivity of 60% and a specificity of 77.1%, as well as a PPV and NPV of 69.2% for each.

CONCLUSION

Enhanced expression of monocytic TF may have a role in the development and prediction of non-neoplastic PVT in HCV-cirrhosis patients. Large multicenter studies are necessary to validate our results.

FVIIa-antithrombin levels in early and late preeclampsia

BACKGROUND

Preeclampsia (PE) is associated with a hypercoagulability state. According to the gestational age (GA) at the onset of the disease, PE has been classified as early (GA<34weeks) and late (GA≥34weeks). It has been admitted that early PE is associated with ischemic placental lesions, while in late PE an adequate or slightly impaired placentation occurs, which suggests that the two clinical forms have distinct etiology. Tissue factor (TF) binds and activates plasma factor VII triggering the coagulation. The inhibitor antithrombin (AT), along with tissue factor pathway inhibitor, acts as an inhibitor of the FVIIa-TF pathway. Once the TF-FVIIa complex is formed, the binding and transfer of FVIIa to AT is facilitated and FVIIa activity is inhibited.

OBJECTIVE

We evaluated the FVIIa-AT complex levels in pregnant women with early and late severe PE (sPE), in order to verify if this biomarker can be useful for discriminating the two forms of the disease.

METHODS

We evaluated 26 pregnant with severe early PE and 19 pregnant with severe late PE. FVIIa-AT levels were measured by STACLOT® (Diagnostica Stago). Statistical analysis was done by Mann-Whitney test.

RESULTS

Increased FVIIa-AT levels were found in early sPE [148.4pM (137.1)] compared to late sPE [95.9pM (66.5)] (P=0.046), which suggests a higher pro-coagulant state when PE onset occurs before 34weeks of gestation.

CONCLUSION

These pioneer data allow inferring the relevance of FVIIa-AT as a device for early sPE diagnosis. However, the clinical relevance of FVIIa-AT complex surely needs to be fully clarified.

Risk factors for portal vein thrombosis in cirrhotic patients: A meta-analysis

AIM

To identify the risk factors for portal vein thrombosis (PVT) in cirrhotic patients.

METHODS

We searched the PubMed, CNKI and Wanfang Databases up to Aug 2015 to retrieve case-controlled studies about the risk factors for PVT in cirrhotic patients for meta-analysis. The odds ratio or weighted mean difference (WMD) of each risk factor was estimated and the 95% confidence interval (95%CI) was calculated. RevMan 5.0 software provided by the Library of Cochrane was used for meta-analysis.

RESULTS

Nine case-controlled studies were included. The risk factors for PVT included D-dimer (WMD = 0.34, 95%CI: 0.21-0.46), portal vein diameter (WMD = 1.67, 95%CI: 1.36-1.97), portal venous flow [WMD = -2.32, 95%CI: -3.63-(-1.01)], and splenic thickness (WMD = 8.57, 95%CI: 4.14-12.99). There were no significant differences between patients with and without PVT in terms of sex, age, platelet, prothrombin time, activated partial thromboplastin time, and fibrinogen.

CONCLUSION

The risk factors for PVT in cirrhotic patients include D-dimer, portal vein diameter, portal venous flow, and splenic thickness.

Factor VIIa-antithrombin complex: a possible new biomarker for activated coagulation

The activation of the extrinsic coagulation pathway occurs after endothelial injury when the tissue factor (TF), a transmembrane protein located outside the vasculature, binds factor VII (FVII) or activated FVII (FVIIa). Once formed, the TF-VIIa complex activates both factor IX and X and initiates the coagulation process. The TF-VIIa complex is inhibited by both TF pathway inhibitor (TFPI) and antithrombin (AT). The interaction between TF-VIIa and AT induces FVIIa-AT complex formation, which is released into the plasma. Because AT reacts with FVIIa only when it is bound to TF, the circulating levels of FVIIa-AT reflect the degree of exposure of TF to blood. Preliminary clinical studies have shown higher plasma levels of FVIIa-AT complex both in patients with a prior arterial or venous thrombotic event. Increased plasma levels of FVIIa-AT have also been reported in a number of other prothrombotic conditions – antiphospholipid antibodies, solid and hematological malignancies, pre-eclampsia (PE), obesity and cardiac surgery. However, most of the studies published so far are retrospective and with a limited sample size. Larger prospective clinical studies are needed to confirm these findings and to assess the prognostic role of this possible new biomarker for activated coagulation.

Does decreased fibrinolysis have a role to play in the development of non-neoplastic portal vein thrombosis in patients with hepatic cirrhosis?

Hepatic cirrhosis is characterized by complex abnormalities of the fibrinolytic system. Little is known about the possible association between these alterations and thrombosis. The aim of this study was to evaluate the fibrinolytic profile in cirrhotic individuals with and without portal vein thrombosis (PVT). We measured thrombin activatable fibrinolysis inhibitor (TAFI), total amount of activated TAFI (TAFIa/ai), plasminogen activator inhibitor (PAI-1), plasminogen and fibrinogen plasma levels in 66 cirrhotic patients (33 with and 33 without PVT) and in 66 healthy volunteers. TAFI plasma levels (median [range]) were significantly lower in cirrhotic individuals (5.6 μg/ml [1.7-11.7]) than in controls (10.1 μg/ml [6.6-14.2], p < 0.0001), while TAFIa/ai levels were significantly higher in cases (18.3 ng/ml [0.3-35.4]) than in controls (15.9 ng/ml [7.4-41], p = 0.02). Cirrhotic patients with PVT had higher TAFI (6.6 μg/ml [2.9-10.1]), TAFIa/ai (19.2 ng/ml [11.6-35.4]) and PAI-1 (33.1 ng/ml [27.6-56.3]) plasma levels than those without PVT (3.9 μg/ml [1.7-11.7], p = 0.001; 15.6 ng/ml [10.3-33.9], p = 0.037; 15.9 ng/ml [2.5-29.1], p = 0.004. The fibrinolytic profile in cirrhotic individuals with PVT is characterized by higher levels of TAFI, TAFIa/ai and PAI-1 than in those without PVT. These alterations identify a hypofibrinolytic condition that may increase the risk of developing a thrombotic event.