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.

A Comprehensive Study on Hemostasis in CAPD Patients Treated with Erythropoietin

Objective

Bleeding diathesis and simultaneous thrombotic complications may be seen in dialyzed patients. Erythropoietin (EPO) may shift the precarious balance of the hemostatic system toward thrombosis. Platelets and tissue factor (TF) play a major role in plug formation. Tissue factor pathway inhibitor (TFPI) appears to play a primary role in regulating TF-induced coagulation. Thrombin activatable fibrinolysis inhibitor (TAFI) is a key protein linking coagulation and fibrinolysis. The aim of the study was to assess whether 6 months of EPO therapy affects platelet function, that is, platelet aggregation and P-selectin level; moieties of the extrinsic coagulation pathway: TF, TFPI, and TFPI/Xa complexes, and factors VII and X; markers of ongoing coagulation: thrombin–antithrombin complexes (TAT) and prothrombin fragments 1+2; a marker of ongoing fibrinolysis: plasmin–antiplasmin complexes (PAP); fibrinolytic activity: euglobulin clot lysis time (ECLT); and markers of endothelial cell injury: von Willebrand factor, thrombomodulin, E-selectin, and TAFI, in continuous ambulatory peritoneal dialysis (CAPD) patients.

Patients and Methods

22 patients on CAPD were given EPO 6000 U/week. 12 patients with chronic renal failure and 12 healthy volunteers served as control groups. All parameters were studied before, and after 1, 3, and 6 months of EPO therapy.

Setting

Department of Nephrology and Internal Medicine, Medical Academy of Bialystok, Poland.

Results

Platelet aggregation in whole blood did not change significantly during EPO treatment. A significant rise in arachidonic acid-induced platelet aggregation in platelet-rich plasma was observed after 3 and 6 months, and in collagen-induced platelet aggregation after 6 months of EPO therapy, compared to the baseline values. The TFPI concentration decreased significantly after 6 months of EPO therapy. The activity of factor VII increased transiently after 1 month of EPO therapy, compared to the baseline values. The TAFI concentration and activity in the CAPD group were significantly higher than in the control group. Erythropoietin therapy resulted in a significant decrease in TAFI concentration and activity after 6 months of EPO treatment. The ECLT was shortened significantly as early as after 1 month of EPO therapy. Thrombomodulin, von Willebrand factor concentration and activity, PAP, TAT, TFPI/Xa complexes, prothrombin fragments 1+2, factor X activity, P-selectin, E-selectin, and lipoprotein(a) did not change significantly during EPO treatment.

Conclusion

Erythropoietin treatment has a minimal effect on hemostasis in CAPD patients. A tendency toward a decline in TAFI is of unknown clinical relevance so far, and awaits further research.

Changes in Peritoneal Coagulation and Fibrinolysis after Discontinuation of Chronic Peritoneal Dialysis

♦ Objectives

To study changes in peritoneal function after transfer from chronic peritoneal dialysis (CPD) to hemodialysis (HD), especially the effects on peritoneal coagulation, fibrinolytic markers, and mesothelium.

♦ Design

Prospective observational study.

♦ Setting

A tertiary-care university hospital.

♦ Patients

Nine patients who transferred from CPD to HD were enrolled in the study after giving fully informed consent.

♦ Methods

After transfer to HD, the peritoneal cavity was lavaged with low glucose PD solution once per day through PD catheters left in place. Thrombin–antithrombin III complex (TAT) was measured serially as a marker of peritoneal coagulation. As fibrinolytic markers, fibrinogen/fibrin degradation products (FDP) and plasmin–α2-antiplasmin complex (PIC) were assessed. Cancer antigen 125 (CA125) was measured as a marker of mesothelial cell mass.

♦ Results

Levels of peritoneal TAT and FDP were much higher than plasma levels, indicating high local fibrin turnover. Transfer to HD induced a significant fall in mean peritoneal TAT, from 115.8 ± 52.1 to 60.7 ± 21.8 ng/mL, p < 0.05. Except for 1 patient with a 20-fold increase, mean peritoneal FDP decreased significantly, from 43.6 ± 11.1 to 19.6 ± 3.5 μg/mL, p < 0.05. Mean peritoneal PIC increased significantly, from 1.9 ± 0.4 to 3.9 ± 0.6 μg/mL, p < 0.05. Peritoneal CA125 increased from 156.4 ± 57.3 to 1426.2 ± 389.4 U/mL, p < 0.05.

♦ Conclusions

Peritoneal fibrin turnover was accelerated on CPD and stabilized after transfer to HD. Transfer to HD also induced mesothelial regeneration.

Influence of Simvastatin on Aspects of Thrombogenesis in CAPD Patients

← Background

Patients on continuous ambulatory peritoneal dialysis (CAPD) are prone to dyslipidemia and have a high risk of cardiovascular death. Statins show beneficial effects on serum lipids and thrombogenesis in various groups of patients, but prospective studies have so far not been performed on CAPD patients.

← Aim

To determine the effects of 6 month's treatment with simvastatin on platelet function and some hemostatic parameters, markers of endothelial cell injury, in 14 CAPD patients with hypercholesterolemia.

← Methods

Simvastatin was given in a dose of 10 mg at bedtime. Commercially available kits were used for all determinations.

← Results

Cholesterol and low density lipoprotein fell significantly as early as after 1 month of the therapy ( p < 0.001). Platelet aggregation in whole blood and plateletrich plasma was transiently decreased by simvastatin therapy. The fibrinolytic activity index increased significantly after 6 months of simvastatin administration ( p < 0.05), reaching values observed in the control group, whereas euglobulin clot lysis time, which was also significantly shortened after 6 months ( p < 0.05), did not reach values obtained in healthy volunteers. Vascular cell adhesion molecule, thrombomodulin, and protein Z decreased significantly after 3 months of the therapy ( p < 0.05, p < 0.05, and p < 0.01, respectively), whereas intercellular adhesion molecule decreased after 6 months ( p < 0.05). Vascular endothelial growth factor and its receptor, protein Z, total tissue factor pathway inhibitor (TFPI), TFPI/Xa complexes, and thrombin activatable fibrinolysis inhibitor concentration and activity fell significantly after 6 months of treatment with simvastatin (all p < 0.05). Tissue plasminogen activator concentration increased after 1 month ( p < 0.01 after 1 month, p < 0.05 after 3 and 6 months), whereas total homocysteine fell after 6 months of simvastatin therapy ( p < 0.05). Truncated TFPI decreased significantly as early as after 1 month of therapy ( p < 0.05 after 1 month, p < 0.01 after 3 and 6 months).

← Conclusion

Simvastatin is an effective hypolipemic agent in CAPD patients. It favorably affects platelet aggregation and the extrinsic coagulation pathway, improves fibrinolysis, and ameliorates endothelial dysfunction. Simvastatin might reduce the risk of thrombotic complications in CAPD patients.

The comparison of risk of stroke in patients with peritoneal dialysis and hemodialysis: A systematic review and meta-analysis

OBJECTIVE

Several studies have demonstrated that end-stage renal disease (ESRD) patients on dialysis are at higher risk for cerebrovascular events, especially those on hemodialysis. However, the risk of stroke in patients on peritoneal dialysis (PD) compared to those on hemodialysis (HD) remains unclear. We performed this meta-analysis to assess the risks of stroke in ESRD patients on PD compared to HD.

METHODS

A systematic review was conducted using MEDLINE, EMBASE, Cochrane databases from inception through January 2018 to identify studies that evaluated the risks of stroke (all types of stroke, ischemic stroke or hemorrhagic stroke) in ESRD patients on different dialysis modalities. Effect estimates from the individual study were extracted and combined using random-effect, generic inverse variance method of DerSimonian and Laird.

RESULTS

Fifteen cohort studies with a total of 1 289 572 ESRD patients (over 1 140 942 on HD and 122 534 on PD) were enrolled. Compared with HD, PD was associated with a significantly decreased risk of hemorrhagic stroke with pooled OR of 0.84 (95% CI: 0.76-0.92). However, there were no differences in risks of all types of stroke or ischemic stroke in those on PD compared to HD with pooled ORs of 1.06 (95% CI: 0.91-1.22) and 1.01 (95% CI: 0.80-1.18,), respectively.

CONCLUSIONS

PD status is associated with 16% lower risk of hemorrhagic stroke compared to HD, but the risks of all types of stroke and hemorrhagic stroke are not statistically different in PD patients when compared to HD patients.

Elevation of Platelet and Monocyte Activity Markers of Atherosclerosis in Haemodialysis Patients Compared to Peritoneal Dialysis Patients

Purpose

The predominant cause of mortality in dialysis patients are cardiovascular events. Platelet and monocyte activity markers play an important role in cardiovascular mortality and were assessed and related to dialysis quality criteria in haemodialysis (HD) and peritoneal dialysis (PD) patients.

Methods

For this prospective comparative study, HD patients (n = 41) and PD patients (n = 10) were included. In whole blood samples, surface expression of CD62P and CD40L on platelets, tissue factor binding on monocytes, and platelet-monocyte aggregates were measured by flow cytometry. Plasma levels of MCP-1, IL-6, TNFα, and soluble CD40L were analysed by enzyme-linked immunosorbent assay.

Results

Haemodialysis patients showed a significantly higher CD62P expression on platelets (p = 0.017), significantly higher amount of platelet-monocyte aggregates (p < 0.0001), and significantly more tissue factor binding on monocytes (p < 0.0001) compared to PD patients. In PD patients, a significant correlation between Kt/V and platelet CD40L expression (r = 0.867; 0.001) and between Kt/V and platelet CD62P expression (r = 0.686; p = 0.028) was observed, while there was no significant correlation between Kt/V and tissue factor binding on monocytes and platelet-monocyte aggregates, respectively.

Conclusion

Platelet and monocyte activity markers are higher in HD patients in comparison with those in PD patients, possibly suggesting a higher risk of cardiovascular morbidity and mortality.

Fasudil inhibits tissue factor and plasminogen activator Inhibitor-1 secretion by peripheral blood mononuclear cells in CAPD patients

Disturbances in hemostasis are common complications of kidney diseases and correlate well with cardiovascular mortality. Little is known about the effects of fasudil on tissue factor (TF) and plasminogen activator inhibitor-1 (PAI-1) expression in peripheral blood mononuclear cells (PBMCs) in CAPD patients. PBMCs were isolated from 13 individuals with CAPD and 13 healthy subjects. After 4 h of incubation with or without LPS (10 ng/mL), TF and PAI-1 mRNA of PBMCs were detected by RT-PCR. The levels of TF and PAI-1 in culture supernatants of PBMCs were determined by ELISA. Compared with healthy controls, CAPD patients had increased TF, PAI-1 protein and mRNA expression by PBMCs at baseline and after stimulated by LPS (10 ng/mL) [p < 0.001]. The fasudil treatment resulted in a significant effect in decreasing TF and PAI-1 [p < 0.05] synthesis in PBMCs. TF and PAI-1 mRNA expression and activities in PBMCs were increased in CAPD patients. Fasudil reduced LPS-mediated TF and PAI-1 expression and activity in PBMCs. These effects may partially be relevant to the clinical benefits of fasudil in the treatment of CAPD patients.

Pre-transplant dialysis modality does not influence short- or long-term outcome in kidney transplant recipients: analysis of paired kidneys from the same deceased donor

Previous studies have reported contradictory results regarding the effect of pre-transplant dialysis modality on the outcomes after kidney transplantation (KT). To minimize the confounding effect of donor-related variables, we performed a donor-matched retrospective comparison of 160 patients that received only one modality of pre-transplant dialysis (peritoneal dialysis [PD] and hemodialysis [HD] in 80 patients each) and that subsequently underwent KT at our center between January 1990 and December 2007. Cox regression models were used to evaluate the association between pre-transplant dialysis modality and primary study outcomes (death-censored graft survival and patient survival). To control for imbalances in recipient-related baseline characteristics, we performed additional adjustments for the propensity score (PS) for receiving pre-transplant PD (versus HD). There were no significant differences according to pre-transplant dialysis modality in death-censored graft survival (PS-adjusted hazard ratio [aHR]: 0.65; 95% confidence interval [95% CI]: 0.25-1.68) or patient survival (aHR: 0.58; 95% CI: 0.13-2.68). There were no differences in 10-year graft function or in the incidence of post-transplant complications either, except for a higher risk of lymphocele in patients undergoing PD (odds ratio: 4.31; 95% CI: 1.15-16.21). In conclusion, pre-transplant dialysis modality in KT recipients does not impact short- or long-term graft outcomes or patient survival.

oxLDL - the molecule linking hypercoagulability with the presence of cardiovascular disease in hemodialyzed uraemic patients

INTRODUCTION

Patients with end-stage renal disease (ESRD) exhibit features of a hypercoagulable state, which may contribute to cardiovascular complications. Data from "in vitro" studies suggest that cell-free plasma lipids and lipoproteins may be capable to support thrombin generation. The aim of this study has been to establish the role of plasma oxidized LDL (oxLDL) in the coagulation activation in hemodialyzed (HD) patients with and without cardiovascular disease (CVD).

MATERIALS AND METHODS

We examined relationship between a marker of coagulation activation - prothrombin fragments 1+2 (F1+2), and plasma oxLDL levels in 60 HD patients with and without CVD and in 20 healthy controls.

RESULTS

F1+2 levels were significantly higher in HD patients than in controls, and they were higher in HD patients with CVD compared to those without CVD (p<0.001). Conversely, oxLDL levels were similar in HD patients with CVD and healthy controls, whereas this parameter was lower in HD patients without CVD when compared to controls and patients with CVD (both p<0.01). Close positive and independent association was between F1+2 and oxLDL levels in HD patients. Nitrates treatment and the presence of pyelonephritis were associated with reduced oxLDL as well as hypercoagulability in HD patients with cardiovascular complications.

CONCLUSION

This study demonstrates the independent association between oxLDL and the marker of coagulation activation - F1+2 in HD patients. This new observation may offer a better understanding of the complex mechanism leading to hypercoagulability, which is markedly intensified in these patients, particularly in those with CVD.

Stent thrombosis distal to the segment showing early in-stent restenosis with everolimus-eluting stent

Stent thrombosis remains a severe complication after deployment owing to its high mortality. In the current report, we present a case of stent thrombosis distal to the segment showing flow-limiting early in-stent restenosis with an everolimus-eluting stent. <Learning objective: Cardiologists should be aware of the potential risk of stent thrombosis in patients undergoing stent deployment distal to the segment where early restenosis is likely to occur.>.

ADAMTS13 and Von Willebrand factor in patients undergoing hemodialysis

Hemodialysis (HD) is associated with increasing thrombotic trend. Vascular access thrombosis (VAT) increases morbidity in HD patients. The aim of this study was to evaluate ADAMTS13 and VWF plasma levels from patients undergoing HD as putative biomarkers of the hypercoagulability state, as well the association between these markers and VAT occurrence. This study included 195 patients on HD for more than 6 months. HD patients were allocated into two groups according to the occurrence or not of previous episode of VAT; HD with VAT (N = 46) and HD without VAT (N = 149). ADAMTS13 and VWF were performed by ELISA. There was no significant difference between HD patients with and without VAT for ADAMTS13 and VWF levels. However, VWF levels were higher (P < 0.001) and ADAMTS13 were lower (P < 0.001) in HD patients, comparing to the control group composed by healthy subjects without kidney disease, age and sex-matched (N = 80). Taken together our data suggest a potential role of the kidneys function compromised on ADAMTS13 synthesis or metabolism, regardless other known sources of ADAMTS13. The imbalance between ADAMTS13 and VWF levels does not explain the development of VAT in HD patients by itself, although it should contribute for the hypercoagulability state. Therefore, additional studies to identify other risk factors are warranted and essential for better management of HD patients.

Plasma concentration of von Willebrand factor predicts mortality in patients on chronic renal replacement therapy

BACKGROUND

Traditional cardiovascular risk factors do not explain the high incidence of cardiovascular mortality and morbidity in patients with end-stage renal disease. A prothrombotic state could accelerate the process of vascular disease in these patients.

METHODS

In this study, four platelet activation markers (NAP-2, P-selectin, GP1b and RANTES) and two endothelial cell activation markers (von Willebrand factor and its propeptide) were measured in 671 haemodialysis patients and 275 patients on continuous ambulatory peritoneal dialysis (PD). All were long-term dialysis patients. The risk of all-cause and cardiovascular mortality was assessed in relation to these markers after a mean follow-up time of 2.5 years.

RESULTS

The von Willebrand factor showed a positive correlation with total mortality in the haemodialysis patients. In an unadjusted model, the hazard rate (HR) of total mortality was 2.4 [95% confidence interval (95% CI) 1.7-3.4] in the upper quartile of von Willebrand factor compared with the lowest quartile. It remained statistically significant (HR 1.8; 95% CI 1.2-2.6) after adjustment for traditional risk factors. In contrast, no significant correlation was found between von Willebrand factor levels and total mortality in PD patients. Finally, no relationship between platelet activation markers and total mortality was found in either the haemodialysis or the PD patients.

CONCLUSION

It can be concluded that chronic endothelial cell activation, but not platelet activation, is related to all-cause mortality in end-stage renal disease patients on long-term dialysis.

Increased nitric oxide production in platelets from severe chronic renal failure patients

Nitric oxide (NO) production occurs through oxidation of the amino acid L-arginine by NO synthase (NOS). NO inhibits platelet activation by increasing the levels of cyclic guanosine monophosphate (cGMP), thus maintaining vascular homeostasis. Our group previously demonstrated (da Silva et al. 2005) an enhancement of the L-arginine-NO-cGMP pathway in platelets taken from chronic renal failure (CRF) patients on haemodialysis associated with reduced platelet aggregation. We investigate the platelet L-arginine-NO-cGMP pathway, platelet function, and inflammation from patients in CRF on conservative treatment. A total of 42 CRF patients and 42 controls (creatinine clearance = 27 ± 3 vs. 93 ± 1 mL per min per 1.73 m2, respectively) participated in this study. NOS activity and expression and cGMP concentration were measured in platelets. Platelet aggregation induced by collagen or ADP was evaluated and plasma levels of fibrinogen were determined by the Clauss method. A marked increase in basal NOS activity was seen in undialysed CRF patients compared with controls, accompanied by an elevation of fibrinogen plasma levels. There were no differences in expression of NOS and in cGMP levels. In this context, platelet aggregation was not affected. We provide the first evidence of increased intraplatelet NO biosynthesis in undialysed CRF patients, which can be an early marker of future haemostatic abnormalities during dialysis treatment.

Visfatin and endothelial function in dialyzed patients

AIM

Visfatin is an adipocytokine that has recently generated much interest. The aim of the study was to assess visfatin in correlation with markers of endothelial damage and inflammation in haemodialyzed and peritoneally dialyzed patients.

METHODS

Visfatin, leptin, apelin and adiponectin, markers of coagulation (thrombin-antithrombin complexes (TAT), prothrombin fragments 1+2 (F1+2)), fibrinolysis (tissue plasminogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1)), endothelial function/injury (Von Willebrand factor (vWF), thrombomodulin, intracellular adhesion molecule (ICAM), vascular cell adhesion molecule (VCAM), CD146) and inflammation (high-sensitivity C-reactive protein (hsCRP), tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6) were assessed.

RESULTS

Triglycerides, hsCRP, creatinine, IL-6, TNF-alpha, vWF, F1+2, TAT, thrombomodulin, ICAM, VCAM, CD146, PAI-1, leptin, adiponectin and visfatin were elevated in dialyzed patients over controls. Visfatin correlated significantly, in univariate analysis, in haemodialyzed patients with markers of endothelial damage/inflammation (CD146, ICAM, IL-6), other adipocytokines, Kt/V and dialysis vintage, and tended to correlate with hsCRP. In peritoneally dialyzed patients, visfatin correlated significantly with haemoglobin, and markers of endothelial damage. In the healthy volunteers visfatin correlated significantly with ICAM, creatinine and IL-6. In multiple regression analysis in HD patients visfatin was only independently related to Kt/V, dialysis vintage and IL-6.

CONCLUSION

Elevated visfatin related to markers of inflammation might represent a novel link between inflammation and adipocytokines in dialyzed patients. Time on dialyses and dialysis adequacy may influence visfatin in dialyzed patients due to the decreased clearance of visfatin.

Mechanism of endothelial dysfunction in chronic kidney disease

Endothelium is the largest organ in the body strategically located between the wall of blood vessels and the blood stream. The human body contains approximately 10(13) endothelial cells weighing approximately 1kg, and covering a surface area of 4000 to 7000m(2) equivalent to the soccer playground. Hypertension and shear stress, inflammation, diabetes-associated factors such as advanced glycated end products, and uremic toxins are some of the prevalent risk factors of endothelial dysfunction in chronic kidney disease. In renal failure endothelial dysfunction and atherosclerosis are almost universal, as well as cardiovascular complications. Endothelial cell damage or injury is invariably associated with such clinical conditions as thrombosis, hypertension, renal failure and atherosclerosis and may be also responsible for accelerated atherosclerosis in patients with chronic renal failure. Traditional risk factor cannot explain the high prevalence and incidence of cardiovascular disease in chronic kidney disease, therefore other non-traditional risk factors such as endothelial dysfunction, oxidative stress or insulin resistance have increasingly been studied. In this review paper mechanism of endothelial dysfunction, including the role of nitric oxide pathway, adipocytokines and hemodialysis-induced endothelial dysfunction is discussed.

The Role of Intrinsic Fibrinolytic System Activation in Pathogenesis of Hemostasis Disturbances in Hemodialized Patients with Chronic Renal Failure

In the hemodialysis patient, hemostasis changes may occur. The contribution of fibrinolysis in pathogenesis of these disorders is unclear. The aim of the study was to estimate intrinsic fibrinolysis pathway in patients treated with hemodialysis (HD) because of chronic renal failure caused by chronic glomerulonephritis. The study was performed with 43 patients; the control group consisted of 51 healthy volunteers chosen by sex and age. The following parameters were determined: concentration of the urokinase plasminogen activator antigen (uPA:Ag), plasmin--antiplasmin complexes (PAP), fibrin and fibrinogen degradation products (FDP), activity of prekallikrein (PK) and C1-inhibitor (C1-INH) and also euglobulin clot lysis time (ELT). The above parameters were assessed in the patients before and after HD and were compared with the control group. In the HD patients, in comparison with the control group, prolonged statistically ELT [153 (125;215) vs. 105 (75;142) min.; p<0.001], with increase of PAP (508.6 +/- 274.7 vs. 184.7 +/- 69.4 microg/L; p<0.001) and FDP concentrations [5 (5;15) vs. 2.5 (0;0.3) microg/mL; p<0.05] before the procedure were determined. It suggests increased plasmin production and fibrin digestion despite determination of decreased general fibrinolytic activity. The C1-INH activity before HD was also significantly increased as compared with the control group [157 (136;171) vs. 107 (100;124)%; p<0.001], and its significant decreased after the HD is 157.7 +/- 23.9 vs. 122.3 +/- 20.3%; p<0.001, as it seems to be a nondirect proof of intrinsic pathway contribution in fibrinolysis activation in the HD patients. The remaining examined parameters did not change significantly after the dialysis procedure.

Characterization of the pro-thrombotic state in CAPD patients

PURPOSE

To investigate whether a chronic pro-thrombotic tendency, which may contribute to a high rate of atherothrombotic disease, is present in patients treated for continuous peritoneal dialysis (CAPD), and, if so, what its pattern is. We investigated this issue by jointly exploring all the systems involved, the coagulation and fibrinolytic systems and platelets.

METHODS

Markers of coagulation activation, markers of fibrinolysis activation, and standard fibrinolytic parameters and platelet aggregation induced by different agents were measured in 15 patients treated by CAPD and in 15 matched, healthy controls. All CAPD patients received erythropoietin, were in the stable condition, and did not have acute disease or malignancy.

RESULTS

CAPD patients had substantially (p < 0.001) increased levels of prothrombin fragments F1+2, disclosing a low-grade activation of the coagulation system. D-dimer was also significantly (p < 0.05) increased, whereas the levels of t-PA antigen and activity, PAI antigen and activity, and plasminogen were comparable to controls, suggesting that slight secondary (and not primary) activation of fibrinolysis due to coagulation activation took place. Patients had significantly (p < 0.05) elevated levels of fibrinogen. A study of platelet aggregation (induced by adenosine diphosphate, collagen, and epinephrine) did not show platelet hyperactivity in patients.

CONCLUSIONS

We found that a pro-thrombotic tendency is present in the plasma of CAPD patients. The main reason for a pro-thrombotic state is chronic low-grade activation of the coagulation system and elevated levels of fibrinogen. The fibrinolytic system and platelets seemingly do not contribute to this pro-thrombotic tendency.

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.

Adipokines, linking adipocytes and vascular function in hemodialyzed patients, may also be possibly related to CD146, a novel adhesion molecule

Possible correlations between adiponectin, leptin, CD146, a novel adhesion molecule localized at the endothelial junction, and other markers of endothelial cell injury, von Willebrand factor, thrombomodulin, vascular cell adhesion molecule, and intracellular adhesion molecule, and markers of inflammation, tumor necrosis factor-alpha, interleukin-6, and high-sensitivity C-reactive protein in nondiabetic hemodialyzed patients with and without coronary artery disease were studied. Markers of endothelial dysfunction were elevated in hemodialyzed patients, predominantly with coronary artery disease. In multivariate analysis, kinetic urea modeling and plasminogen activator inhibitor-1 remained the only positive predictors of adiponectin. In multivariate analysis, predictors of leptin were triglycerides, tissue plasminogen activator, CD146, and coronary artery disease. In multivariate analysis, predictors of CD146 were age, hemoglobin, and adiponectin. Elevated adiponectin correlated to CD146 may be the expression of a counterregulatory response aimed at mitigating the consequences in endothelial damage and increased cardiovascular risk in renal failure. The data provide further support for a link between adipocytokines, endothelial dysfunction, cardiovascular risk, and renal failure.

Association between tissue factor, its pathway inhibitor and oxidative stress in peritoneal dialysis patients

The abnormalities of tissue factor and its inhibitor system, increased oxidative stress and the presence of diabetes may be involved in the mechanism of thrombotic complication in peritoneal dialysis patients. We compared the plasma levels of tissue factor, its inhibitor and markers of oxidative stress (malondialdehyde and Cu/Zn superoxide dismutase) in 16 diabetic peritoneal dialysis patients, 40 nondiabetic peritoneal dialysis patients, and 20 healthy control individuals. We tried to establish whether there is an association between tissue factor, its inhibitor and oxidative stress in these patients. Compared with the control individuals, the patients both with and without diabetes showed a significant increase in plasma concentrations of Cu/Zn superoxide dismutase (P < 0.01 and P < 0.001, respectively), malondialdehyde (both P < 0.05), tissue factor (both P < 0.001) and tissue factor pathway inhibitor (P < 0.01 and P < 0.001, respectively). The differences in oxidative status and coagulation parameters between patients with and without diabetes were not statistically significant. In all peritoneal dialysis patients, both tissue factor and its inhibitor were positively related to Cu/Zn superoxide dismutase (r = 0.310, P < 0.05 and r = 0.460, P < 0.001, respectively) and malondialdehyde levels (r = 0.337, P < 0.05 and r = 0.361, P < 0.01, respectively). Our data suggest a relationship between increased oxidative stress and elevated tissue factor and its inhibitor levels in peritoneal dialysis patients, particularly those with diabetes.

Protein Z and natural anticoagulants in children on peritoneal dialysis and hemodialysis

Hemostatic alterations due to abnormalities in the coagulation and fibrinolytic system may occur in dialysis patients. Protein Z (PZ) is a vitamin K-dependent coagulation protein promoting assembly of thrombin with phospholipid vesicles. The aim of this study was to investigate PZ and natural anticoagulants in children on hemodialysis (HD) and peritoneal dialysis (PD). Protein Z, protein C (PC), protein S (PS), antithrombin III (AT III), and fibrinogen levels were studied in 24 PD, 13 HD patients and 23 controls. Plasma PZ levels in patients on HD were significantly higher than those on PD and control group (p = 0.04, p = 0.03). We observed elevated PC, PS and AT III activities in children on PD when compared to controls (p = 0.011, p = 0.003, p < 0.001). In HD patients, only PS activity was increased compared to controls (p = 0.016). PC and PS activities did not differ between PD and HD patients whereas AT III activity was higher in PD patients compared to HD patients (p < 0.001). Normal/high levels of PC, PS and AT III suggest that children on PD or HD treatment do not seem to have an increased risk of thrombogenesis due to reduction of these proteins. Increased PZ levels, however, might contribute to the hemostatic alterations in children on HD treatment along with other well known abnormalities.

Thyroid Function, Endothelium, and Inflammation in Hemodialyzed Patients: Possible Relations?

OBJECTIVE

Renal function affects the thyroid gland in many ways. Disturbances in hemostasis and inflammation are common complications of kidney diseases. Endothelial dysfunction may link these two processes.

DESIGN AND PATIENTS

A cross-sectional study on thyroid hormones in relation to markers of endothelial damage and inflammation in 96 hemodialyzed (HD) patients and 39 healthy volunteers was performed.

SETTING

The study took place in the dialysis unit at a university hospital.

INTERVENTION

Thyroid hormones, markers of endothelial damage (von Willebrand factor, thrombomodulin, intracellular adhesion molecule, and CD146), markers of inflammation (high-sensitivity C-reactive protein, tumor necrosis factor alpha), other hemostatic parameters (thrombin-antithrombin complexes, prothrombin fragments 1 + 2 - F1 + 2, plasmin-antiplasmin complexes, tissue plasminogen activator and its inhibitor, tissue factor pathway inhibitor, and platelet glycoprotein V) were measured using commercially available kits.

RESULTS

Free T3 and total T3 were lower in HD patients compared with controls. Markers of endothelial dysfunction and inflammation were significantly elevated in HD patients compared with controls. In multiple regression analysis T3 was independently related to time on dialyses, albumin, iron, ferritin, C-reactive protein (CRP), and F1 + 2 in HD patients. Free T3 was also independently related to total protein, total calcium, and triglycerides. In patients with CRP less than 6 mg/L in multiple regression analysis the only correlates of T3 were albumin and ferritin, whereas the only correlates of free T3 were albumin and time on dialyses. Multiple regression analysis showed that in HD patients with CRP greater than equal to 6 mg/L predictors of free T3 were CRP, F1 + 2, and dose of erythropoietin. In healthy volunteers T3 was related to tissue factor pathway inhibitor and platelet glycoprotein V was related to thyroid-stimulating hormone.

CONCLUSIONS

We described novel relations between thyroid hormones and markers of endothelial dysfunction and inflammation in HD patients. Thyroid dysfunction is related to time on dialyses, endothelial damage, and inflammatory state, frequently encountered in uremia. Therefore, the relations between thyroid axis and endothelium in HD subjects merit additional studies.

Predictors of Vascular Access Thrombosis Among Patients on the Cadaveric Renal Transplantation Waiting List

Acute thrombotic complications remain a constant, proportionally increasing complication before and after renal transplantation. We sought to investigate predictors for a prothrombotic state that increased the risk of vascular access thrombosis, among chronic renal failure patients during the waiting period prior to cadaveric renal transplantation. Chronic renal failure patients awaiting cadaveric renal transplantation and followed between January 2002 and January 2005 were included in this study. The 109 subjects including, 61 females and 48 males of mean age: 47.4 +/- 12.9 years; There were 36 continuous ambulatory peritoneal dialysis and 73 hemodialysis patients. Serum albumin, prealbumin, CRP, d-dimer, fibrinogen, antithrombin III, anticardiolipin antibodies (immunoglobulins G and M), homocystein, vitamin B12, folic acid, total cholesterol, triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total platelet count were measured in each patient. Factor V Leiden, prothrombin 20210, ACE and MTHFR gene mutations were studied in all patients. Vascular Access thrombosis was detected in 62 patients. During follow-up 31 of 109 patients died. Vascular access thrombosis occurred in 78 patients who survived and 31 who died. The patients who died showed a significantly higher rate of thrombosis than those who survived (P = .003, OR: 4.61, CI: 1.70 to 12.50). Among the above biochemical risk factors, multiple regression analysis and backward logistic analysis revealed that d-dimer was the strongest biochemical predictor of thrombosis (P = .013, RR: 17.8). Upon evaluation of genetic risk factors, only factor V Leiden mutation was related to vascular access thrombosis (P = .001). In conclusion, the presence of vascular access thrombosis is a risk factor for mortality during the waiting period for cadaveric renal transplantation. As patients with factor V Leiden mutation or high serum d-dimer levels are at high risk for vascular access thrombosis, we recommend close monitorizing of these patients and use of anticoagulant therapy during the waiting period prior to renal transplantation.

Propyl gallate-induced platelet aggregation in patients with end-stage renal disease: The influence of the haemodialysis procedure

BACKGROUND

Platelet dysfunction is a well-established disturbance in haemodialysis (HD) patients. Propyl gallate is a synthetic platelet activator with the property to stimulate platelet aggregation. The aim of the present study was to evaluate the influence of a single haemodialysis session on propyl gallate-induced platelet aggregation.

METHODS

Thirty-nine HD patients were enrolled in the study and 20 healthy volunteers were studied as controls. Cellulose diacetate (CD) dialysers were used in 20 patients and polysulphone dialysers in 19. HD was performed via an A-V fistula in 27 patients and via an i.v. catheter in 12. Erythropoietin was administered in 37 patients (epoietin-alpha in 24 and darbepoietin in 13). Thirty-four were receiving the low-molecular-weight heparin tinzaparin. Propyl gallate slide aggregometry was used for evaluating platelet aggregation.

RESULTS

In HD patients, platelet aggregation was impaired before as well as after the HD session. No effect of the HD procedure, type of vascular access, adequacy of HD or type of erythropoietin on the propyl gallate-induced platelet aggregation was detected. Platelet aggregation was higher when CD dialyser was used. A negative correlation between the time needed for platelet aggregation to occur and tinzaparin dose was found.

CONCLUSION

Propyl gallate-induced platelet aggregation in HD patients is impaired. Platelet aggregation was higher in patients dialysed with CD membrane than in those dialysed with polysulphone membrane. The higher the dose of tinzaparin, the higher the platelet aggregation. The clinical significance of the above results needs further evaluation.

Oxidative stress effects fibrinolytic system in dialysis uraemic patients

INTRODUCTION

Enhanced oxidative stress (SOX) and changes in the fibrinolytic system are common in end-stage renal failure patients undergoing maintenance dialysis. This study attempted to verify the existence of a relationship between SOX documented by Cu/Zn superoxide dismutase (Cu/Zn SOD) and fibrinolysis analyzed by tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor 1 (PAI-1) and plasmin/antiplasmin (PAP) complexes in dialysis patients.

MATERIALS AND METHODS

Twenty-seven patients on maintenance haemodialysis (HD) and 16 on maintenance peritoneal dialysis (CAPD) were examined together with 18 healthy controls. Pre-dialysis blood levels of all the parameters were determined using commercially ELISA kits.

RESULTS

Cu/Zn SOD, uPA and PAP levels were increased in both groups of dialyzed patients compared to the controls. PAI-1 was significantly lower in CAPD subjects compared to HD subjects and control group. PAI-1/uPA ratio and PAI-1/tPA ratio were significantly decreased in CAPD and HD compared to controls, being significantly lower in CAPD patients relative to HD patients. In the patients, increased Cu/Zn SOD levels directly correlated with those of uPA (r=0.565, p<0.0001) and PAP (r=0.335, p<0.05); the fibrinolytic markers were also positively associated with each other (r=0.377, p<0.05).

CONCLUSIONS

The positive association between Cu/Zn SOD and both uPA as well as PAP levels suggests a link between SOX and the fibrinolytic activity in dialysis patients. We hypothesize that increased SOX-mediated fibrinolytic activity may be a part of the counter-system against activation of blood coagulation in these patients.

Platelet surface receptor activation in patients with chronic renal failure on hemodialysis, peritoneal dialysis and those with successful kidney transplantation

Hemostatic disorders associated with chronic renal failure (CRF) include hemorrhagic and/or thrombotic manifestations, which were ascribed, in part, to uremic platelet dysfunction including abnormalities of expression of platelet glycoprotein receptors. There is, however, still no general agreement on the exact characterization of these platelet abnormalities. This study aims at characterizing the platelet glycoprotein abnormalities associated with CRF, by recording the effect of the three renal replacement therapies, hemodialysis (HD), chronic ambulatory peritoneal dialysis (CAPD), and renal transplantation, on these receptors. The study, which was mainly cross-sectional, included two groups: (i) Patient groups (n = 50): HD patients (n = 20), CAPD patients (n = 10) and successful renal transplant patients (n = 20); (ii) Healthy Controls (n = 34): 23 were men and 11 were women who were age- and sex-matched with the patients. Flow cytometric quantitation of CD41, CD42a, CD42b and CD61 was carried out using a Becton-Dickinson FACScan. The expression of CD41 levels showed a highly significant increase in HD and CAPD patients when compared with the normal control levels. However, levels in transplant patients were comparable to the normal control levels. On the other hand, the expression of CD42a, CD42b, and CD61 showed no significant change in HD and CAPD patients when compared with normal control levels, but there was a significant decrease in transplant patients when compared to the normal control levels. In conclusion, there was evidence of increased expression of one glycoprotein receptor (GpIIb-IIIa) pre-dialysis whether HD or CAPD. In transplant patients, no evidence of platelet activation could be demonstrated.

Is there a link between CD146, a novel adhesion molecule and other markers of endothelial dysfunction in nephrotic syndrome and continuous ambulatory peritoneal dialysis?

BACKGROUND

CD146 is a novel cell adhesion molecule localized at the endothelial junction. Its increased plasma levels in chronic renal failure are linked to endothelial dysfunction. Endothelial dysfunction and hemostatic disturbances, a common feature of nephrotic syndrome (NS), mimics a state of protein loosing by peritoneal membrane in patients on chronic ambulatory peritoneal dialyses (CAPD). The aim of the study was to assess CD146 in relation to other markers of endothelial cell injury in patients with NS in comparison to patients on CAPD.

MATERIALS AND METHODS

We studied 45 CAPD patients, 43 patients with nephrotic syndrome and 25 healthy volunteers. Markers of endothelial cell injury: TFPI total, full length, truncated, von Willebrand factor, trombomodulin, P-selectin, E-selectin, ICAM, VCAM and CD146 were assessed using commercially available kits.

RESULTS

All these markers studied except selectins were significantly elevated in patients with NS and CAPD when compared to the healthy volunteers. In CAPD, VCAM, thrombomodulin and CD146 were significantly elevated over NS patients. CD146 correlated significantly with ICAM as well as total and truncated TFPI in CAPD patients. Moreover, total TFPI was positively related to VCAM. CD146 correlated with ICAM in NS, whereas in healthy volunteers CD146 correlated only with TFPI concentration.

CONCLUSIONS

Our studies indicate that in nephrotic patients, as well as in CAPD, there is an evidence of endothelial cell injury. Correlations between CD146 and adhesion molecules and TFPI might further support its use as a endothelial cell function marker.

Red blood cells may contribute to hypercoagulability in uraemia via enhanced surface exposure of phosphatidylserine

BACKGROUND

The exposure of phosphatidylserine (PS) on the outer leaflet of the erythrocyte membrane may have several pathophysiological consequences, including the development of a procoagulant phenotype, a finding that seems relevant to the thrombotic risk seen in many disorders.

METHODS

Because PS externalization increases in erythrocytes from patients suffering from chronic uraemia, which is frequently associated with a prothrombotic state, the possible relationship between erythrocyte PS exposure, erythrocyte procoagulant activity and plasma levels of several haemostatic markers was studied in a group of haemodialysed patients.

RESULTS

Uraemic erythrocytes displayed increased procoagulant activity, which proved to be correlated directly with erythrocyte PS exposure. Pre-incubation of uraemic erythrocytes with annexin V, a protein with high affinity and specificity for PS, strongly inhibited in vitro thrombin generation induced by erythrocytes as compared with untreated red cells. Thrombin generation and activation of fibrinolysis were found to occur in uraemic patients, as substantiated by increased plasma levels of markers for thrombin generation (prothrombin fragment F1.2 and thrombin-antithrombin complex) and fibrinolysis (D-dimer and plasmin-antiplasmin complex), respectively. Significant correlations between prothrombin fragment F1.2 and D-dimer suggested that hyperfibrinolysis was secondary to thrombin generation. Correlations were also found between erythrocyte PS levels and plasma levels of haemostatic markers, including prothrombin fragment F1.2 (P = 0.007), thrombin-antithrombin complex (P = 0.00009), plasmin-antiplasmin complex (P = 0.0009) and D-dimer (P = 0.005).

CONCLUSIONS

Our study suggests that increased PS exposure may cause a pathological erythrocyte procoagulant phenotype, which may be a factor inducing a hypercoagulable state in uraemia.

Effect of dialysis modality on plasma fibrinogen concentration: A meta-analysis

BACKGROUND

Concentrations of plasma fibrinogen, a vascular risk factor, tend to be greater in patients on peritoneal dialysis (PD) than hemodialysis (HD) therapy, like concentrations of serum cholesterol, lipoprotein(a), and transthyretin, despite the substantial loss of protein during PD. Worse vascular outcome has been noted in PD patients compared with HD patients in several studies.

METHODS

In this study, the mean difference in plasma fibrinogen levels (PD-HD) was quantified by means of meta-analysis of mean differences found in 12 cohorts with both PD and HD patients (set 1; N = 630) by using a fixed-effects model and meta-analysis of mean fibrinogen values reported in 30 cohorts of patients on a single dialysis modality (set 2; 8 PD cohorts, 22 HD cohorts; N = 2,096) by using a mixed model.

RESULTS

On meta-analysis, the weighted mean difference (PD-HD) was 105 mg/dL (95% confidence interval [CI], 86 to 124 [3.1 micromol/L; 95% CI, 2.5 to 3.6]) in set 1 and 103 mg/dL (95% CI, 53 to 153 [3.0 micromol/L; 95% CI, 1.6 to 4.5) in set 2.

CONCLUSION

Like other vascular risk factors, such as cholesterol and lipoprotein(a), plasma fibrinogen level is markedly greater in PD than HD patients, with an approximate difference of 100 mg/dL [2.9 mumol/L]. Different plasma reference ranges for fibrinogen need to be defined for PD and HD patients. The mechanism for the difference and the possible role of hyperfibrinogenemia in worsening vascular disease in PD patients deserve study.

Increased soluble CD40L levels are reduced by long-term simvastatin treatment in peritoneally dialyzed patients

BACKGROUND

Dyslipidemia and increased mortality due to cardiovascular events are common in peritoneally dialyzed patients [continuous ambulatory peritoneal dialysis (CAPD)]. Statins show beneficial effects on serum lipids and reduce cardiovascular mortality. The CD40-CD40 ligand (CD40L) system has proved critical for the activation of tissue structural cells that include endothelial cells, epithelial cells and fibroblasts. It has been reported that enhanced CD40L-CD40 interaction in familial hypercholesterolemia may be downregulated by statins, but prospective studies on CAPD patients are lacking.

AIM

To determine the effects of 6 months treatment with simvastatin on platelet aggregation, markers of endothelial cell injury, and sCD40L in 15 hyperlipidemic CAPD patients.

METHODS

Simvastatin (Zocor, Merck Sharp & Dohme) was given in a dose of 10 mg at bedtime.

RESULTS

CD40L decreased significantly after 6 months of the therapy. Thrombomodulin decreased significantly after 3 months of the therapy, whereas von Willebrand factor, E-selectin and P-selectin did not change significantly during the study.

CONCLUSION

Simvastatin reduced enhanced sCD40L levels together with amelioration of endothelial dysfunction. Treatment with simvastatin might downregulate enhanced CD40L-CD40 interactions in CAPD patients.

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

Patients receiving maintenance hemodialysis (HD) present with hemostatic abnormalities, which may be aggravated by comorbid conditions, especially liver disease. The factors that influence plasma levels of thrombomodulin (TM), an initiator of the anticoagulant protein C pathway, and those of tissue factor (TF), which triggers the extrinsic coagulation pathway, were assessed. In 63 HD patients, TM and TF levels were higher than those in healthy controls. In bivariate analysis, TF positively correlated with TM, and both were directly associated with the presence of viral hepatitis B or C marker, serum liver enzymes, use of erythropoietin therapy, hemoglobin levels, and duration of HD therapy, and inversely correlated with body mass index. TF was also positively associated with plasma von Willebrand factor (vWF) antigen, and inversely associated with activated partial thromboplastin time. In multivariate analysis, increased vWF, alanine aminotransferase, and use of erythropoietin independently predicted both TF and TM levels. HD patients with vWF and ALT levels lower than middle, and not treated with erythropoietin had normal TF but increased TM concentrations compared with levels in healthy controls. Increased plasma levels of TM and TF in patients on maintenance HD are surrogates of vascular endothelial injury. Liver disease and use of erythropoietin treatment are also important determinants of these markers, and should be considered in further studies.

Statins and renal function

Renal disease is often associated with an increased risk of vascular events. Moreover, an accelerated form of atherosclerosis commonly occurs in these patients. The reasons for these associations are not clearly defined but include the widespread presence of several established risk factors (eg, dyslipidemia, hypertension, and diabetes). Other predictors of atherosclerotic disease may also be abnormally elevated (eg, homocysteine, fibrinogen, and lipoprotein a). In addition, there is evidence that impaired renal function per se predicts vascular risk. Despite this high-risk background, the potential benefit of treatment with statins has not been widely investigated in these patients. The present review considers the evidence (experimental and clinical) that statins exert beneficial effects in patients with different types of renal disease. This includes improved renal function, decreased microalbuminuria, and a fall in blood pressure. Statins may also improve renal allograft survival. The potential mechanisms mediating these effects are considered. The interactions between statins and several risk factors that may be present in patients with impaired renal function are also considered. There is an urgent need to define the role of statins in these high-risk patients. Which is the statin of choice? This question is relevant because impaired renal function can interfere with statin pharmacokinetics. Furthermore, other drugs administered to these patients may cause serious interactions with statins.