Tissue factor and thrombomodulin in hemodialysis patients: associations with endothelial injury, liver disease, and erythropoietin therapy

Clotting of the Extracorporeal Circuit in Hemodialysis: Beyond Contact-Activated Coagulation

Thrombotic complications in patients with end-stage kidney disease are frequent. While being a lifesaving treatment for these patients, hemodialysis introduces a thromboinflammatory environment. Additionally, the extracorporeal hemodialysis circuit itself is prone to clotting because of an interaction between different activation mechanisms of the coagulation system, platelets, and the immune system. Anticoagulation of the patient and the machine is frequently complicated by bleeding. We discuss the factors important in this balancing act and touch on potential strategies that are on the horizon to target thromboinflammation.

Thrombolome and Its Emerging Role in Chronic Kidney Diseases

Patients with chronic kidney disease (CKD) are at an increased risk of thromboembolic complications, including myocardial infarction, stroke, deep vein thrombosis, and pulmonary embolism. These complications lead to increased mortality. Evidence points to the key role of CKD-associated dysbiosis and its effect via the generation of gut microbial metabolites in inducing the prothrombotic phenotype. This phenomenon is known as thrombolome, a panel of intestinal bacteria-derived uremic toxins that enhance thrombosis via increased tissue factor expression, platelet hyperactivity, microparticles release, and endothelial dysfunction. This review discusses the role of uremic toxins derived from gut-microbiota metabolism of dietary tryptophan (indoxyl sulfate (IS), indole-3-acetic acid (IAA), kynurenine (KYN)), phenylalanine/tyrosine (p-cresol sulfate (PCS), p-cresol glucuronide (PCG), phenylacetylglutamine (PAGln)) and choline/phosphatidylcholine (trimethylamine N-oxide (TMAO)) in spontaneously induced thrombosis. The increase in the generation of gut microbial uremic toxins, the activation of aryl hydrocarbon (AhRs) and platelet adrenergic (ARs) receptors, and the nuclear factor kappa B (NF-κB) signaling pathway can serve as potential targets during the prevention of thromboembolic events. They can also help create a new therapeutic approach in the CKD population.

The effects of citrate dialysate in hemodialysis on polymorphonuclear elastase interaction with tissue factor and its inhibitor

BACKGROUND

This study aimed to investigate whether hemodialysis (HD) affects tissue factor (TF), tissue factor pathway inhibitor (TFPI), and polymorphonuclear elastase (PMNE) in endstage renal disease (ESRD) patients when eliminating the effects of heparin. Also, to explore the interaction of TF, TFPI, and PMNE throughout a single HD session.

METHODS

We enrolled 57 ESRD patients who had undergone hemodialysis for >3 months as an experimental group. Plasma levels of TF, TFPI and PMNE were measured by ELISA in 24 ERSD patients on intermittent HD using low-molecular-weight heparin (LMWH) as anticoagulation (LMWH group) and 33 ESRD patients using citrate as anticoagulation (citrate group) at the start and at 1, 2 and 5 h of the HD session. Meanwhile,28 ESRD patients not on dialysis were enrolled as a control group and fasting venous blood samples were taken in the morning.

RESULTS

Compared with the control group, the plasma TFPI levels of the LMWH group and the citrate group were significantly higher (P=0.000, P=0.002, respectively) under baseline conditions as well as the plasma PMNE levels (P=0.001, P=0.02, respectively), whereas TF showed no difference (P=0.186). During HD with citrate, plasma TFPI decreased slightly (P=0.012) and PMNE increased significantly (P=0.008) at 1 h. The plasma TFPI levels of the citrate group correlate with PMNE at 2 and 5 h (P=0.001, P=0.008, respectively).

CONCLUSIONS

ESRD patients on HD have significantly higher TFPI and PMNE levels compared to patients not on HD under baseline conditions, while TF levels were similar between the three groups. TFPI and PMNE are differently regulated, but the plasma levels correlated during HD in the citrate group. It might be possible that PMNE plays a role in anticoagulative activity through TFPI.

Decreased Expression of Thrombomodulin in Endothelial Cells by Fibroblast Growth Factor-23/α-Klotho

Chronic kidney disease (CKD) has been known to be a state of excessive fibroblast growth factor-23 (FGF23) and α-Klotho deficiency. Patients undergoing hemodialysis have an increased mortality risk associated with cardiovascular disease and endothelial dysfunction. The mechanism responsible for the relationship of FGF23 to endothelial damage in these patients has been unclear. On the other hands, increasing evidences have demonstrated that thrombomodulin (TM) plays an important role in the endothelial barrier. Here, we report the suppression of membrane TM, in a dose-dependent manner, in human umbilical vein endothelial cells after FGF23 and FGF23/α-Klotho stimulation. In addition, the levels of soluble TM, which reflect endothelial cell injury, were much higher in cell supernatants after FGF23 and FGF23/α-Klotho stimulation than in the control supernatant. This study indicates a possible mechanism by which excessive levels of FGF23 are involved in endothelial TM disruption, which has been implicated as a potential cardiovascular risk factor in patients with CKD, especially in HD patients.

Innate immunity related pathogen recognition receptors and chronic hepatitis B infection

Innate immunity consists of several kinds of pathogen recognition receptors (PRRs), which participate in the recognition of pathogens and consequently activation of innate immune system against pathogens. Recently, several investigations reported that PRRs may also play key roles in the induction/stimulation of immune system related complications in microbial infections. Hepatitis B virus (HBV), as the main cause of viral hepatitis in human, can induce several clinical forms of hepatitis B and also might be associated with hepatic complications such as cirrhosis and hepatocellular carcinoma (HCC). Based on the important roles of PRRs in the eradication of microbial infections including viral infections and their related complications, it appears that the molecules may be a main part of immune responses against viral infections including HBV and participate in the HBV related complications. Thus, this review article has brought together information regarding the roles of PRRs in immunity against HBV and its complications.

Anemia and anemia correction: surrogate markers or causes of morbidity in chronic kidney disease?

Observational studies have shown a strong positive correlation between the severity of anemia and the risk of poor outcomes in patients with chronic kidney disease (CKD). This observation was initially taken to imply that adverse outcomes in CKD are caused by anemia. However, the assumption of causality ignores the possibility that anemia and adverse outcomes might be unrelated and that both are caused by underlying inflammation, oxidative stress and comorbid conditions. Randomized clinical trials of anemia correction have revealed an increased risk of adverse cardiovascular outcomes in patients assigned to normal, rather than subnormal, hemoglobin targets. As a result, correction of anemia is now considered potentially hazardous in patients with CKD. Notably, individuals who did not reach the target hemoglobin level in the clinical trials, despite receiving high doses of erythropoietin and iron, experienced a disproportionately large share of the adverse outcomes. These observations point to overdose of erythropoietin and iron, rather than anemia correction per se, as the likely culprit. This Review explores the reasons for the apparent contradiction between the findings of observational studies and randomized clinical trials of anemia treatment in CKD. I have focused on data from basic and translational studies, which are often overlooked in the design and interpretation of clinical studies and in the formulation of clinical guidelines.

Chronic viral hepatitis C, oxidative stress and the coagulation/fibrinolysis system in haemodialysis patients

INTRODUCTION

The aim of the present study was to establish whether the presence of chronic viral hepatitis (PVH) could be implicated in the elevation of oxidative stress (SOX) and haemostasis system in haemodialysis (HD) patients.

MATERIALS AND METHODS

In HD patients with and without PVH and in controls we compared the markers of: coagulation pathway- tissue factor (TF) and its inhibitor (TFPI), prothrombin fragment F (1+2) (F (1+2)); fibrinolysis: tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA) and its soluble receptor (suPAR), plasminogen activator inhibitor 1 (PAI-1), plasmin/antiplasmin complexes (PAP); and a marker of SOX-Cu/Zn superoxide dismutase (Cu/Zn SOD) levels.

RESULTS

Patients, particularly those with PVH, showed a significant increase in the markers of the coagulation, fibrinolysis and oxidative status as compared to controls. All parameters of coagulation/fibrinolysis system were directly associated with the PVH and Cu/Zn SOD levels, and there was a relationship between the PVH and Cu/Zn SOD levels. Multivariable analysis showed that PVH and increased SOX were identified as independent variables significantly associated with the disturbances of coagulation/fibrinolysis system in these patients.

CONCLUSIONS

We concluded that PVH is a novel determinant of the increased oxidative stress as well as the disturbances of coagulation/fibrinolysis system in haemodialysis patients.

Tissue factor and urokinase-type plasminogen activator system are related to the presence of cardiovascular disease in hemodialysis patients

INTRODUCTION

The disturbances of haemostasis and enhanced oxidative stress (SOX) appear to contribute to the cardiovascular disease (CVD) in hemodialysis (HD) patients. The aim of the present study was to investigate if the disorders of coagulation/fibrinolysis system are associated with the presence of CVD in these patients.

MATERIALS AND METHODS

We compared pre-dialysis levels of uPA, suPAR, tissue factor (TF) and its inhibitor (TFPI), prothrombin fragment F1+2 (F1+2); a marker of SOX-Cu/Zn superoxide dismutase (Cu/Zn SOD) and a surrogate of inflammation-high sensitivity C-reactive protein (hs CRP) in HD patients with and without CVD.

RESULTS

The uPA/suPAR system and hs CRP values were significantly greater in patients with CVD than in those without CVD; whereas TF, TFPI, F1+2 and Cu/Zn SOD levels were comparable in both patient groups. TF was positively correlated with both uPA (p<0.001) and suPAR levels (p<0.05). Logistic regression analysis showed that elevated levels of suPAR, TF and uPA were independently associated with the presence of CVD in HD patients.

CONCLUSIONS

The association between TF and uPA/suPAR system is significantly related to the presence of CVD in HD patients.