Endothelial dysfunction marker von Willebrand factor antigen in haemodialysis patients: associations with pre-dialysis blood pressure and the acute phase response

NETs-Induced Thrombosis Impacts on Cardiovascular and Chronic Kidney Disease

Arterial and venous thrombosis constitute a major source of morbidity and mortality worldwide. Association between thrombotic complications and cardiovascular and other chronic inflammatory diseases are well described. Inflammation and subsequent initiation of thrombotic events, termed immunothrombosis, also receive growing attention but are still incompletely understood. Nevertheless, the clinical relevance of aberrant immunothrombosis, referred to as thromboinflammation, is evident by an increased risk of thrombosis and cardiovascular events in patients with inflammatory or infectious diseases. Proinflammatory mediators released from platelets, complement activation, and the formation of NETs (neutrophil extracellular traps) initiate and foster immunothrombosis. In this review, we highlight and discuss prominent and emerging interrelationships and functions between NETs and other mediators in immunothrombosis in cardiovascular disease. Also, with patients with chronic kidney disease suffering from increased cardiovascular and thrombotic risk, we summarize current knowledge on neutrophil phenotype, function, and NET formation in chronic kidney disease. In addition, we elaborate on therapeutic targeting of NETs-induced immunothrombosis. A better understanding of the functional relevance of antithrombotic mediators which do not increase bleeding risk may provide opportunities for successful therapeutic interventions to reduce thrombotic risk beyond current treatment options.

Calcium sensing receptor initiating cystathionine-gamma-lyase/hydrogen sulfide pathway to inhibit platelet activation in hyperhomocysteinemia rat

Hyperhomocysteinemia (HHcy, high homocysteine) induces the injury of endothelial cells (ECs). Hydrogen sulfide (H₂S) protects ECs and inhibits the activation of platelets. Calcium-sensing receptor (CaSR) regulates the production of endogenous H₂S. However, whether CaSR inhibits the injury of ECs and the activation of platelets by regulating the endogenous cystathionine-gamma-lyase (CSE, a major enzyme that produces H₂S)/H₂S pathway in hyperhomocysteinemia has not been previously investigated. Here, we tested the ultrastructure alterations of ECs and platelets, the changes in the concentration of serum homocysteine and the parameters of blood of hyperhomocysteinemia rats were measured. The aggregation rate and expression of P-selectin of platelets were assessed. Additionally, the expression levels of CaSR and CSE in the aorta of rats were examined by western blotting. The mitochondrial membrane potential and the production of reactive oxygen species (ROS) were measured; the expression of phospho-calmodulin kinases II (p-CaMK II) and Von Willebrand Factor (vWF) of cultured ECs from rat thoracic aortas were measured. We found that the aggregation rate and the expression of P-selectin of platelets increased, and the expression of CaSR and CSE decreased in HHcy rats. In the ECs of HHcy group, the ROS production increased and the mitochondrial membrane potential decreased markedly, the expression of CSE and the p-CaMK II increased after treatment with CaSR agonist while decreased upon administration of U73122 (PLC-specific inhibitor) and 2-APB (IP₃ Receptor inhibitor). CaSR agonist or NaHS significantly reversed the ECs injured and platelet aggregation caused by hyperhomocysteinemia. Our results demonstrate that CaSR regulates the endogenous CSE/H₂S pathway to inhibit the activation of platelets which concerts the protection of ECs in hyperhomocysteinemia.

Quantitative and qualitative changes of von Willebrand factor and their impact on mortality in patients with end-stage kidney disease

von Willebrand factor (vWF) antigen levels are elevated in patients with end-stage kidney disease (ESKD). We determined the quantitative and qualitative abnormalities of vWF and factors influencing vWF proteolysis in participants with ESKD compared with age-matched controls and determined the association between abnormalities in vWF and mortality over 4 years of follow-up. vWF : Ag and von Willebrand factor propeptide (vWFpp) levels, vWF functional activity (vWF :RCo), vWF multimer profiles, ADAMTS-13, thrombospondin 1 (TSP-1), and interleukin 6 (IL-6) were evaluated before and after a single hemodialysis treatment in 55 individuals with vascular disease and an age-matched group of controls (n = 21). vWF : Ag and vWF activity were significantly higher in the ESKD patients and levels increased further following the dialysis procedure. The percentage of high molecular weight multimers (%HMWMs) was significantly elevated in the ESKD patients compared with controls. TSP-1 was lower and IL-6 was higher providing possible explanation for the increase in %HMWM in ESKD. The %HMWM dropped significantly in the postdialysis sample. Mortality at 4 years was significantly associated with vWF : Ag. There are higher plasma vWF : Ag levels and a small increase in HMWMs in the ESKD milieu. The acute drop in the %HMWM of vWF postdialysis appears to be due to shear forces encountered during the dialysis procedure. The contribution of these abnormalities to either a pro-thrombotic and/or pro-bleeding phenotype in this population requires further study.

von Willebrand factor in iris vasculature of glaucoma patients

Background

Previous reports have indicated the role of endothelium disturbances, as expressed by von Willebrand factor (vWF) release, in pathophysiology of glaucoma. The objective of this study was to investigate the vWF expression in iris vasculature of patients with primary open-angle glaucoma (POAG).

Material/Methods

Immunohistochemistry of vWF expression was performed on cryostat sections of samples collected at the time of peripheral iridectomy and controls collected from dead donors.

Results

Twenty-seven Caucasians age 66.6±3.7 with 5.8±3.7-year history of treated PAOG and 10 controls age 62.2±1.92 with no history of glaucoma. The percentage of patients who presented normal and up-regulation of vWF phenotype expression differed statistically between examined and control groups: 48% versus 100% (p=0.035, chi-square test with Yates’ correction). Sex, age, glaucoma duration, and visual field quantitative indices had no impact on vWF expression. A significant correlation between mean pre-surgery intraocular pressure and vWF expression was found (Spearman r=0.42, p=0.03).

Conclusions

Considering the results, it may be suggested that vWF is actively involved in the pathophysiology of glaucoma.

Thrombin-anti-thrombin levels and patency of arterio-venous fistula in patients undergoing haemodialysis compared to healthy volunteers: a prospective analysis

Background

Patients on haemodialysis (HD) are at an increased risk of sustaining thrombotic events especially to their vascular access which is essential for maintenance of HD.

Objectives

To assess whether 1) markers of coagulation, fibrinolysis or endothelial activation are increased in patients on HD compared to controls and 2) if measurement of any of these factors could help to identify patients at increased risk of arteriovenous (AVF) access occlusion.

Patients/Methods

Venous blood samples were taken from 70 patients immediately before a session of HD and from 78 resting healthy volunteers. Thrombin-antithrombin (TAT), D-dimer, von Willebrand factor (vWF), plasminogen activator inhibitor-1 antigen (PAI-1) and soluble p-selectin were measured by ELISA. C-reactive protein (hsCRP) was measured by an immunonephelometric kinetic assay. Determination of the patency of the AVF was based upon international standards and was prospectively followed up for a minimum of four years or until the AVF was non-functioning.

Results

A total of 70 patients were studied with a median follow-up of 740 days (range 72-1788 days). TAT, D-dimer, vWF, p-selectin and hsCRP were elevated in patients on HD compared with controls. At one year follow-up, primary patency was 66% (46 patients). In multivariate analysis TAT was inversely associated with primary assisted patency (r= -0.250, p= 0.044) and secondary patency (r = -0.267, p= 0.031).

Conclusions

The novel finding of this study is that in patients on haemodialysis, TAT levels were increased and inversely correlated with primary assisted patency and secondary patency. Further evaluation is required into the possible role of TAT as a biomarker of AVF occlusion.

Effect of Unfractionated and Low-Molecular-Weight Heparin on OPG, sRANKL, and von Willebrand Factor Concentrations During Hemodialysis

Background: Endothelial dysfunction marker, von Willebrand factor (vWF), is physically connected with osteoprotegerin (OPG) in the Weibel-Palade bodies. We aimed to compare the effect of unfractionated (UFH) and low-molecular-weight (LMWH enoxaparin) heparin used as anticoagulants during hemodialysis (HD) on plasma levels and relationships of OPG, soluble receptor activator of nuclear factor κB Ligand (sRANKL), and vWF. Methods: Totally 21 clinically stable chronic HD patients were randomly assigned to either enoxaparin (n = 10) or UFH (n = 11) anticoagulation and followed prospectively for 12 weeks before crossing over to the alternate therapy for further 12 weeks. The OPG, RANKL, and vWF levels were measured at T0, T10, and T180 of HD session after each period of evaluation. Results: The baseline sRANKL level was higher under UFH treatment. Its over-HD level does not behave significantly different under enoxaparin and UFH treatment. Plasma OPG levels expressly changed during both enoxaparin (χ2 analysis of variance [ANOVA] = 31.13, P < .016) and UFH (χ2 ANOVA = 8.26, P = .016) anticoagulation, and its increment at T10 and T180 was significantly different between both the heparins. The main negative predictor of OPG concentration was the total cholesterol level (β = −.51, P = .025). von Willebrand factor concentration remained stable during UFH anticoagulation, whereas constant, no significant increments were noticed, under enoxaparin treatment. After 10 minutes of HD, especially under enoxaparin use, a positive correlation between OPG and vWF increase was noticed ( P = .03, R = .45). Conclusions: Impact of heparin on endothelial cells and simultaneously on OPG/RANK/RANKL axis reinforces the presumption of the pathophysiological linkage between bone mineralization and endothelial dysfunction in end-stage renal disease.

Comparison of serum albumin, serum C-reactive protein, and pulse wave velocity as predictors of the 4-year mortality of chronic hemodialysis patients

AIM

Although serum albumin and C-reactive protein (CRP) levels and pulse wave velocity (PWV) are known to be associated with the clinical outcome of hemodialysis (HD) patients, it is unknown which of these parameters are more predictive of the long-term mortality of such patients.

METHODS

We measured biochemical parameters, including serum albumin and CRP, and the PWV of 202 patients on maintenance HD therapy and followed their course for 4 years, and 186 of the patients were enrolled in the current study analyses. We divided the 186 patients into three tertiles according to their serum albumin and CRP levels and PWV values, and conducted multivariate analyses to examine the impact of the tertiles on 4-year mortality.

RESULTS

Twenty-three (12.4%) patients died during the follow-up period, and the serum albumin of the group that died was significantly lower than in the group that survived, but the CRP levels and PWV were significantly higher in the group that died. The results of Kaplan-Meier analyses revealed a significantly higher risk of all-cause mortality in HD patients with higher CRP based on the results of Cox proportional hazards analyses; however, the serum albumin and PWV values were not associated with all-cause mortality.

CONCLUSION

The results of this study suggest that serum CRP levels are a better mortality predictor than serum albumin or PWV values of chronic HD patients.

Relationship between serum albumin and pulse wave velocity in patients on continuous ambulatory peritoneal dialysis

Background:

Hypoalbuminemia is a risk factor for cardiovascular events and mortality in dialysis patients, but the underlying mechanism remains unclear. Meanwhile, increased pulse wave velocity (PWV), the marker of arterial stiffness, has been proved to be an independent predictor of cardiovascular disease. The relationship between serum albumin and PWV in continuous ambulatory peritoneal dialysis patients (CAPD) was studied.

Methods:

Sixty-two CAPD patients were studied. The average age was 63 ± 12 years and dialysis duration was 23 ± 22 months. Serum albumin, C-reactive protein (CRP), and carotid-femoral PWV were measured.

Results:

Among these patients, 43.5% were men. The mean serum albumin concentration was 37 ± 4 g/L and PWV was 11.9 ± 2.3 m/s. PWV positively correlated with age (r = 0.35, P < 0.01), diabetes (yes = 1, no = 0; r = 0.292, P < 0.05), systolic blood pressure (SBP; r = 0.493, P < 0.001) and CRP (r = 0.295, P < 0.05), but negatively correlated with serum albumin (r = –0.357, P < 0.01). In multiple regression analysis, SBP (β = 0.615, P < 0.001), age (β = 0.414, P < 0.01), albumin (β = –0.315, P < 0.05) and total cholesterol (β = 0.275, P < 0.05) were independent determinants of PWV. In a non-inflamed subgroup (CRP < 3 mg/L, n = 30), albumin still negatively correlated with PWV (r = −0.66, P < 0.001).

Conclusion:

Serum albumin inversely correlated with increased PWV in CAPD patients, suggesting that increased arterial stiffness might be the link between hypoalbuminemia and increased cardiovascular mortality in dialysis patients.

Preservation of peritubular capillary endothelial integrity and increasing pericytes may be critical to recovery from postischemic acute kidney injury

Decreased renal blood flow following an ischemic insult contributes to a reduction in glomerular filtration. However, little is known about the underlying cellular or subcellular mechanisms mediating reduced renal blood flow in human ischemic acute kidney injury (AKI) or acute renal failure (ARF). To examine renal vascular injury following ischemia, intraoperative graft biopsies were performed after reperfusion in 21 cadaveric renal allografts. Confocal fluorescence microscopy was utilized to examine vascular smooth muscle and endothelial cell integrity as well as peritubular interstitial pericytes in the biopsies. The reperfused, transplanted kidneys exhibited postischemic injury to the renal vasculature, as demonstrated by disorganization/disarray of the actin cytoskeleton in vascular smooth muscle cells and disappearance of von Willebrand factor from vascular endothelial cells. Damage to peritubular capillary endothelial cells was more severe in subjects destined to have sustained ARF than in those with rapid recovery of their graft function. In addition, peritubular pericytes/myofibroblasts were more pronounced in recipients destined to recover than those with sustained ARF. Taken together, these data suggest damage to the renal vasculature occurs after ischemia-reperfusion in human kidneys. Preservation of peritubular capillary endothelial integrity and increasing pericytes may be critical to recovery from postischemic AKI.

Patient characteristics rather than the type of dialyser predict the variability of endothelial derived surface molecules in chronic haemodialysis patients

BACKGROUND

Cardiovascular disease (CVD) is a frequent complication in chronic haemodialysis (HD) patients. Endothelial dysfunction, as measured by soluble cellular adhesion molecules (sCAM) and von Willebrand factor (vWf) in plasma, is an early manifestation of CVD. Today, it is unknown if, and to what extent, their levels are influenced by the type of dialyser.

METHODS

Four dialysers, low-flux cuprammonium (CU); high-flux and low-flux polysulfone and super-flux polyethersulfone, were compared in 15 chronic HD patients in a randomized cross-over fashion. sCAM and vWf were measured at baseline as well as after 4 weeks, and both intra-dialytical and after 24 h (t24 h). Twenty healthy subjects served as controls.

RESULTS

Baseline levels were considerably higher in chronic HD patients than in controls (soluble intercellular adhesion molecule-1: sICAM-1 732+/-216 vs 572+/-259 ng/ml, P = 0.06; soluble vascular cell adhesion molecule-1: sVCAM-1 1917+/-492 vs 1126+/-338 ng/ml, P<0.001; vWF: 205+/-55% vs 98+/-52%, P<0.001). After 4 weeks, no changes were observed. During and after HD, sCAM did not change, except in the case of CU (sICAM-1: 719+/-259 to 772+/-261 ng/ml, P = 0.04). CU induced a rise in vWF directly after HD (t4 h; from 188+/-48% to 255+/-92%, P<0.01), whereas all modalities induced a significant increase at t24 h (mean 228+/-54%, P = 0.02). The levels of sCAM and vWf appeared to be dependent on the individual patients rather than on the type of dialyser (explained variance by different patients: 66%-91%, P<0.001; by type of dialyser 0.4-1.2%).

CONCLUSIONS

Baseline levels of sCAM and vWf were markedly higher in chronic HD patients than in controls and did not change after 4 weeks with any dialyser. All membranes induced a marked rise in vWf at t24 h, whereas sICAM-1 increased only in the case of CU at t4 h. As sCAM showed no marked changes during HD with any other modality, our study suggests activation of blood cells rather than endothelial cells. As pre-dialysis levels of sCAM and vWf varied noticeably between individual patients, endothelial dysfunction seems to be far more dependent on patient-related factors than on the HD treatment itself.

In uremia, plasma levels of anti-protein C and anti-protein S antibodies are associated with thrombosis

BACKGROUND

Vascular access thrombosis is an important cause of morbidity in patients with end-stage renal failure on maintenance hemodialysis (MHD). However, little is known about its risk factors. The present study was undertaken to evaluate the role of coagulation factors, fibrinolytic factors, and anti-phospholipid antibodies (aPL). In particular, we have evaluated the role of anti-protein C and anti-protein S antibodies in patients on MHD with and without thrombosis because no data are available in the literature.

METHODS

The study group comprised 30 patients with thrombotic complications (TC), 40 patients matched for age, sex, and dialytic age with no thrombotic complications (NTC) and 400 controls. We have measured: anti-protein C antibodies, anti-protein S antibodies, anticardiolipin antibodies (ACA), anti-beta2-glycoprotein antibodies (beta2-GPI), and anti-prothrombin antibodies (aPT), along with prothrombin time, fibrinogen, plasminogen, protein C, protein S, anti-thrombin III, APC-resistance test, D-dimer, tissue-type plasminogen's activator, plasminogen activator inhibitor-1 (PAI-1), prothrombin fragment 1+2, factors of the intrinsic and extrinsic pathway, C-reactive protein, and homocysteine.

RESULTS

There were no significant differences between groups for prothrombin time, fibrinogen, plasminogen, protein C, protein S, anti-thrombin III, activated protein C (APC) resistance, D-dimer, tPA, C-reactive protein, Factors II, X, and VII. The anti-beta2-GP1 and aPT were elevated in both TC and NTC patients, compared to the control group. Significant differences between TC and NTC groups were found for anti-protein C and anti-protein S antibodies, ACA-IgM, PAI-1, Factor VIII, prothrombin fragments 1+2, and homocysteine.

CONCLUSION

The most novel finding was a significant elevation of anti-protein C antibodies and anti-protein S antibodies in the TC group (i.e., in patients on MHD with thrombosis of vascular access). It indicates that other pathogenetic mechanisms in addition to endothelial damage may cause hypercoagulability in uremia.

Impaired vascular function during short-term poor glycaemic control in Type 1 diabetic patients

AIM

To study the effects of short-term poor glycaemic control on vascular function in Type 1 diabetic patients.

METHODS

Ten Type 1 diabetic patients, with diabetes duration of less than 10 years and normal urinary albumin excretion and ophthalmoscopy, were studied. All patients were examined after 48 h of good vs. poor glycaemic control within a 3-week period. Blood glucose was measured seven times daily for 2 days before each examination. External ultrasound was used to measure the dilatory response of the brachial artery to post-ischaemic increased blood flow (endothelium-dependent dilation) and to nitroglycerin (endothelium-independent dilation). Plasma concentration of von Willebrand factor antigen, adhesion molecules, vascular endothelial growth factor, homocystein and cholesterol were also measured.

RESULTS

The median blood glucose levels in the 48 h before the examinations were [median (range), good vs. poor control]: 6.3 (5.0-7.6) vs. 15.9 (11.3-17.8) (mmol/l). The flow-associated vasodilation (% of baseline) was reduced during poor control: 102.7 (94.7-110.8) vs. 104.0 (99.6-118.5) (P < 0.05) as were the nitroglycerin-induced dilation (% of baseline): 114.5 (103.3-127.9) vs. 120.2 (106.8-148.0) (P < 0.05). P-von Willebrand factor antigen was high during poor control (kIU/l): 1.14 (0.73-1.84) vs. 0.86 (0.72-1.39) (P < 0.05) and so was P-vascular endothelial growth factor (ng/l): 288 (133-773) vs. 254 (90-383) (P < 0.05).

CONCLUSIONS

Short-term (48 h) hyperglycaemia in Type 1 diabetic patients may disturb vascular function, possibly mediated through smooth muscle cell dysfunction as well as endothelial dysfunction. We suggest that prolonged and repeated episodes of hyperglycaemia could possibly lead to permanent vascular dysfunction and thereby development and progression of vascular complications in diabetes.

Cell-derived microparticles contain caspase 3 in vitro and in vivo

BACKGROUND

Microparticles (MP) from endothelial cells (endothelial microparticles; EMP) circulate in disease states, but the processes such as apoptosis or cell activation underlying their release are unclear.

OBJECTIVES

We investigated whether adherent (viable) or detached (apoptotic) endothelial cells are the possible source of EMP in vitro, i.e. under control and interleukin (IL)-1alpha activation conditions, and in vivo.

METHODS

Adherent and detached endothelial cells, and EMP, were isolated from human umbilical vein endothelial cell cultures (n = 6), treated without or with IL-1alpha (5 ng mL(-1); 24 h). Cell fractions were analyzed by flow cytometry for annexin V binding, propidium iodide (PI) and caspase 3 staining (n = 3). Caspase 3 in EMP was studied using Western blot (n = 6) and flow cytometry (n = 6). Plasma from healthy subjects and systemic lupus erythematosus patients (both n = 3) were analyzed for caspase 3-containing (E)MP.

RESULTS

Detached but not adherent cells double-stained for annexin V and PI, confirming the apoptotic conditions of the detached cells and the viable nature of the adherent cells. Caspase 3 was solely present in the detached cells and procaspase 3 in the adherent cells. Caspase 3 was present in EMP from both control and IL-1alpha-treated cultures. Counts of EMP and detached cells, but not adherent cells, highly correlated (r = 0.959, P < 0.0001). In vivo circulating MP from nucleated (endothelial cells, monocytes) and anucleated cells (platelets, erythrocytes) contained caspase 3.

CONCLUSIONS

EMP contain caspase 3 and may be mainly derived from detached (apoptotic) endothelial cells in vitro. The presence of caspase 3 in MP from anucleated cell types, however, suggests that its presence may not necessarily be related to apoptosis in vivo but may be associated with caspase 3 activation unrelated to apoptosis.

Plasma levels of plasminogen activator inhibitor type 1, factor VIII, prothrombin activation fragment 1+2, anticardiolipin, and antiprothrombin antibodies are risk factors for thrombosis in hemodialysis patients

Patients with end-stage renal disease are prone to hemorrhagic complications and simultaneously are at risk for a variety of thrombotic complications such as thrombosis of dialysis blood access, the subclavian vein, coronary arteries, cerebral vessel, and retinal veins, as well as priapism. The study was devised for the following purposes: (1) to identify the markers of thrombophilia in hemodialyzed patients, (2) to establish a role for antiphospholipid antibodies in thrombosis of the vascular access, (3) to characterize phospholipid antibodies in hemodialysis patients, and (4) to study the effects of dialysis on coagulation cascade. A group of 20 hemodialysis patients with no thrombotic complications (NTC) and 20 hemodialysis patients with thrombotic complications (TC) were studied along with 400 volunteer blood donors. Patients with systemic lupus erythematosus and those with nephrotic syndrome were excluded. All patients underwent a screening prothrombin time, activated partial thromboplastin time, fibrinogen (Fg), coagulation factors of the intrinsic and extrinsic pathways, antithrombin III (AT-III), protein C (PC), protein S (PS), resistance to activated protein C, prothrombin activation fragment 1+2 (F1+2), plasminogen, tissue type plasminogen activator (t-PA), plasminogen tissue activator inhibitor type-1 (PAI-1), anticardiolipin antibodies type M and G (ACA-IgM and ACA-IgG), lupus anticoagulant antibodies, and antiprothrombin antibodies type M and G (aPT-IgM and aPT-IgG). The study showed that PAI-1, F 1+2, factor VIII, ACA-IgM, and aPT-IgM levels were increased significantly over controls both in TC and NTC, however, they could distinguish patients with thrombotic complications from those without, being increased maximally in the former group. The novelty of the study is represented by the significant aPT increase that was observed in non-systemic lupus erythematosus hemodialysis patients, and particularly in those with thrombotic events. In addition, there was a reduction of factor XII during the treatment. It is possible to assume in the TC group and, to a lesser extent, also in the NTC group that endothelial cells liberate PAI-1 in the vascular lumen, which causes hypofibrinolysis. In addition, an excess of factor VIII is activated by endothelial dysfunction with subsequent activation of the coagulation cascade as shown by increased F1+2 and fibrinogen. ACA-IgM, in turn, is capable of interfering with the system of protein C, a potent anticoagulant factor that inactivates cofactors Va and VIIIa. They also induce the expression of procoagulant factors on the surface of the endothelial cells. In conclusion, the hypercoagulable state caused by alterations of coagulation and fibrinolytic factors is a cause of vascular access dysfunction and thrombosis of other vessels.

Endothelin-1 levels and conduit artery mechanical properties in end-stage renal disease

BACKGROUND

Endothelial cell (EC) dysfunction markers are increased in end-stage renal disease (ESRD). The present study focused on the relationship between EC markers, conduit artery wall mechanics and hemodynamics in ESRD.

METHODS

In 29 ESRD patients and 16 controls, brachial artery diameter, distension, and wall thickness was measured and circumferential wall stress (CWS) calculated. Shear stress was determined with a shear rate-estimating system. Furthermore, von Willebrand factor antigen (vWF) and endothelin-1 (ET-1) levels were measured.

RESULTS

vWF (p = 0.002) and ET-1 (p < 0.001) were higher in ESRD patients and vWF was related to ET-1 (r = 0.70, p = 0.005). Peak (p = 0.001) and mean shear stress (p = 0.003) were significantly lower in ESRD patients, and ET-1 showed an inverse log linear relation with both (peak: r = -0.59, p = 0.016; mean: r = -0.64, p = 0.007). Also, ET-1 was log linearly related to CWS (r = 0.58, p = 0.014).

CONCLUSION

These results indicate that, in ESRD, conduit artery shear stress is lower, which might be secondary to an increased peripheral vascular resistance caused by higher ET-1 levels.

FB21, a monoclonal antibody that reacts with a sialic-acid-dependent carbohydrate epitope, is a marker for glomerular endothelial cell injury

BACKGROUND

FB21 is reactive with glomerular endothelial cells and distal tubules of the human kidney and is bound to a sialic-acid-dependent cell-surface antigen. We evaluated FB21 staining in fetal kidneys and kidneys of children and adults with normal kidneys and glomerulonephritis and investigated whether FB21 can be used as a marker for endothelial cell injury.

METHODS

This study was performed on 6 children, 10 adults, and 12 fetuses with normal kidneys and 113 patients diagnosed with primary and secondary glomerulonephritis. We evaluated renal staining for FB21 in children with normal kidneys and glomerulonephritis and measured serum E-selectin concentrations in patients with hemolytic uremic syndrome (HUS) and Henoch-Schönlein purpura nephritis (HSPN).

RESULTS

(1) FB21 was reactive with endothelial cells of normal kidneys and detected on the surface of endothelial cells by immunoelectron microscopy. (2) FB21 was reactive with endothelial cells in kidneys of fetuses older than 32 weeks. (3) Endothelial cell FB21 staining scores in the first renal biopsy specimens of patients with HUS and HSPN were lower than those in normal kidneys of children and correlated negatively with serum E-selectin concentrations. (4) Endothelial cell FB21 staining of crescentic and sclerotic glomerular lesions in patients with immunoglobulin A nephropathy, membranoproliferative glomerulonephritis, and focal glomerulosclerosis was weaker than that in normal kidneys.

CONCLUSION

These results suggest that FB21 can be used as a marker for glomerular endothelial cell injury in various types of glomerulonephritis.

Antigenic characterization of endothelial cell-derived microparticles and their detection ex vivo

BACKGROUND

Endothelial activation and dysfunction are associated with several diseases. However, hardly any specific markers are available. Microparticles (MP) from endothelial cells (EC; EMP) were reported in patient groups and healthy individuals. The antibodies used to detect EMP, however, were mainly directed against antigens without EC specificity.

OBJECTIVES

We evaluated the antigens on EC and EMP to establish proper markers for EMP detection.

METHODS

EMP were isolated from supernatants of resting and interleukin (IL)-1alpha activated human umbilical vein EC (HUVEC; n=3; 0-72 h), stained with annexin V and monoclonal antibodies, and analyzed by flow cytometry. Human platelet-MP (PMP), the main MP population in plasma, were prepared in vitro. EMP and PMP were studied in plasma from systemic lupus erythematosus (SLE) patients (n=11) and healthy individuals (n=10).

RESULTS

Platelet-endothelial cell adhesion molecule-1 (PECAM-1), alphanu and beta3 were constitutively exposed on HUVEC, but (almost) absent on EMP (<15% positive for alphanu and beta3), or only exposed on a subpopulation (PECAM-1; 30-60%). Activated HUVEC (>80%) and (subpopulations of) EMP exposed E-selectin and tissue factor. PMP strongly exposed PECAM-1, beta3, and glycoprotein (GP)Ib (CD42b), but not alphanu or E-selectin. GPIb and P-selectin (CD62P) were absent on EMP. Plasma samples contained 0.5% MP staining for E-selectin and/or alphanu. Plasma from one SLE patient contained E-selectin exposing MP (21%), but little alphanu-positive MP.

CONCLUSIONS

EC release EMP in vitro. The antigenic phenotype of EMP released from resting and IL-1alpha-stimulated EC differs among each other as well as from resting and stimulated EC, respectively. E-selectin exposed on IL-1alpha-stimulated EC is a valid marker for EMP detection ex vivo to establish endothelial cell activation.

Circulating endothelial cells as potential markers of the state of the endothelium in hemodialysis patients

BACKGROUND

Patients with chronic kidney disease (CKD) are at high risk for atherosclerotic cardiovascular disease (ACVD). In addition to the same epidemiological risk factors of the general population, factors unique or secondary to the uremic milieu may contribute to excess cardiovascular morbidity and mortality. Recent studies suggest the endothelium has a key role in the development of atherosclerosis. Circulating endothelial cells (CECs) may be a tool to study the state of the endothelium, with their number markedly increased in conditions associated with a high degree of endothelial cell activation and/or injury. Our hypothesis is that CEC number increases in diseases that commonly progress to stage 5 CKD, as well as in patients on hemodialysis (HD) therapy, reflecting ongoing endothelial cell activation and/or injury.

METHODS

The study population consisted of 22 healthy nonsmoking individuals, 29 individuals undergoing long-term HD treatment, 10 individuals with the diagnosis of diabetes mellitus and stage 1 or 2 CKD, and 7 individuals with hypertension and stage 1 or 2 CKD. The number of CECs was enumerated in all study groups.

RESULTS

We found that CEC number was increased in HD patients, hypertensive patients, and patients with diabetes compared with healthy individuals. In addition, although CEC number did not accurately reflect the presence of ACVD, the number was increased significantly in a group of HD patients with active ACVD, whereas it was decreased significantly in a group of HD patients with stable ACVD.

CONCLUSION

Our results suggest that CEC number may reflect ACVD activity in HD patients, independent of the presence of ACVD.

Fibrinogen, mortality and incident cardiovascular complications in end-stage renal failure

OBJECTIVE

Fibrinogen is an established predictor of cardiovascular events in the general population but the relationship between fibrinogen, mortality and incident cardiovascular complications has been very little investigated in patients with end-stage renal disease (ESRD).

DESIGN AND SUBJECTS

We investigated the relationship between fibrinogen and all cause mortality and cardiovascular outcomes in a prospective cohort study in 192 patients on chronic haemodialysis treatment (follow-up: 34 +/- 16 months).

RESULTS

Fibrinogen was significantly higher in patients who died during the follow-up than in those who survived. Similarly, fibrinogen was higher in patients who had fatal or nonfatal cardiovascular events than in event free patients. On multivariate Cox regression analysis fibrinogen was an independent predictor of survival [hazard ratio (1 g x L(-1) increase in plasma fibrinogen): 1.19, 95% confidence interval (CI): 1.05-1.35, P = 0.006] and a highly significant (P = 0.0008), independent predictor of fatal and nonfatal cardiovascular events [hazard ratio (1 g x L(-1) increase in plasma fibrinogen): 1.25, 95% CI: 1.10-1.43] in a model including traditional risk factors and serum C-reactive protein (CRP) and plasma homocysteine.

CONCLUSIONS

Fibrinogen is as an independent risk factor for overall and cardiovascular mortality in patients with ESRD. Intervention studies are required to see whether reducing plasma fibrinogen may help to curb the exceedingly high cardiovascular risk of the uremic population.

Serum alpha1-antitrypsin but not complement C3 and C4 predicts chronic inflammation in hemodialysis patients

BACKGROUND

We studied whether predialysis serum levels of positive acute phase markers such as alpha1-antitrypsin (AT), and complement components C3 and C4 could identify the presence of chronic inflammation in maintenance hemodialysis (HD) patients.

METHODS/RESULTS

In 103 stable HD patients, AT directly correlated with C-reactive protein (CRP) (P < 0.005), alpha1 acid-glycoprotein (P < 0.005), fibrinogen ( P < 0.05), lipoprotein (a) (P < 0.01) and von Willebrand factor antigen (P < 0.05), while C3 and C4 were not related to any of these inflammatory markers. In the patients with elevated CRP and hypoalbuminemia, the mean AT value of 1.74 +/- 0.50 g/L was higher (P = 0.008) than that of 1.38 +/- 0.27g/L in the subjects with normal CRP and albumin. Using the above cut-off levels, the positive and negative predictive values of AT on the presence of severe inflammation were 0.86 and 0.62, respectively, and the sensitivity and specificity were 86% and 73%, respectively.

CONCLUSION

Serum AT levels above 1.74 g/L and below 1.38 g/L may select the HD patients with severe inflammation from those without. Measurements of C3 and C4 are not helpful in this situation.

Circulating endothelial cells are a novel marker of cyclosporine-induced endothelial damage

Microvascular endothelial cells play a key role in transplant immunology. They are also important targets for calcineurin inhibitors. We recently demonstrated elevated numbers of circulating endothelial cells in renal transplant recipients with and without rejection in comparison with healthy controls. Because these patients received either cyclosporine or tacrolimus, we speculated that endothelial damage from calcineurin inhibitors might be responsible for these findings. In the present study, we tested the hypothesis that treatment with calcineurin inhibitors leads to an increase in circulating endothelial cells. We studied 57 renal transplant recipients: 19 on a calcineurin inhibitor-free immunosuppressive regimen and 38 patients on a standard immunosuppressive regimen, including cyclosporine, and matched them for age and serum creatinine. Endothelial cells were isolated from peripheral blood with anti-CD-146-coated immunomagnetic Dynabeads and were counted by fluorescence microscopy. Patients with cyclosporine therapy had elevated numbers of circulating endothelial cells (median 26, range 12 to 82 cells/mL) compared with healthy controls (median 6, range 0 to 82 cells/mL; P<0.001). Patients without calcineurin inhibitor treatment had significantly lower cell numbers (median 12, range 0 to 32 cells/mL; P<0.003) and were not significantly different from normal, untreated controls. In conclusion, renal transplant recipients who do not receive calcineurin inhibitors have significantly lower numbers of circulating endothelial cells than their age- and creatinine-matched counterparts who receive these drugs. We suggest that elevated numbers of circulating endothelial cells indicate damage from calcineurin inhibitors in renal transplant recipients and that circulating endothelial cells are a novel marker of endothelial damage.

Homocysteine, malondialdehyde and endothelial markers in dialysis patients during low-dose folinic acid therapy

OBJECTIVES

Haemodialysis patients have elevated levels of the atherogenic amino acid homocysteine. We wanted to assess the effects of small doses of intravenous folinic acid (the active form of folic acid) on some biochemical risk factors of cardiovascular disease.

DESIGN

Longitudinal and open intervention study.

SETTING

Two dialysis units in the County of Rogaland.

SUBJECTS

All patients on maintenance haemodialysis were invited, and 32 of 35 patients gave their informed consent.

INTERVENTIONS

After each dialysis session, the patients were given 1.0 mg of folinic acid intravenously thrice a week for a period of 3 months. Prior to and during the study, all patients were on maintenance supplementation with small doses of vitamins B1, B2, B3, B5, B6 and B12.

MAIN OUTCOME MEASURES

Changes in the levels of (i) plasma total homocysteine (p-tHcy) and folate, (ii) circulating endothelium related proteins--markers of endothelial activation and (iii) serum malondialdehyde (S-MDA)--a marker of oxidative stress and lipid peroxidation.

RESULTS

The p-tHcy levels were reduced by 37% (P < 0.0001), whilst the serum and erythrocyte folate levels increased by 95 and 104%, respectively (P < 0.0001 for both). The circulating levels of endothelium related cellular adhesion molecules and haemostatic factors remained high and unchanged, except the thrombomodulin (TM) levels increased (P = 0.0004). The high levels of S-MDA were reduced by 26% (P = 0.003).

CONCLUSIONS

Low doses of folinic acid given intravenously to dialysis patients reduced their levels of p-tHcy and S-MDA and thus improved their cardiovascular risk profile. The concurrent increment in TM levels was unexpected and of unknown clinical significance.

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.

Effect of hemodialysis on plasma levels of vascular endothelial markers

Vascular endothelial cell dysfunction is linked to hemostatic abnormalities and accelerated atherosclerosis in patients receiving maintenance hemodialysis (HD). The relationships between pre-dialysis plasma levels of immunoreactive thrombomodulin, von Willebrand factor, tissue factor and its inhibitor were studied, and the effects of HD procedure on these endothelial markers were observed. All the markers were higher in 39 HD patients than in 15 healthy controls (p<0.0001). HD treatment resulted in a 50% increase in tissue factor pathway inhibitor (p<0.0001), but did not influence the other markers. This increment directly correlated with the post-dialysis decrease in diastolic (p=0.011) and mean arterial blood pressure (p=0.039), and the surface area of the dialysis membrane (p=0.007). There were no associations between the increase in tissue factor pathway inhibitor and the amount of fluid removed, dose of enoxaparin, or other HD-specific factors. In conclusion, HD is responsible for an increase in plasma tissue pathway factor inhibitor level. The release of tissue factor pathway inhibitor during HD is not only due to heparin injection but also to the contact between blood and artificial dialysis membrane, and to HD-activated hemodynamic forces.

Serum hepatocyte growth factor is associated with viral hepatitis, cardiovascular disease, erythropoietin treatment, and type of heparin in haemodialysis patients

BACKGROUND

Increased serum hepatocyte growth factor (HGF) level is a part of the counter-system against tissue damage and predicts mortality in maintenance haemodialysis (HD) patients. We studied which of the common co-morbid and clinical conditions, and surrogates of metabolic disorders or specific organ damage determine HGF levels in these subjects.

METHODS

In 86 patients, pre-dialysis serum HGF, soluble endothelial markers--such as thrombomodulin (TM), von Willebrand factor and plasminogen activator inhibitor-1--and hepatitis B and C markers were measured by ELISAs. Inflammatory reactants such as C-reactive protein (CRP), alpha(1)-antitrypsin, alpha(1) acid-glycoprotein, and immunoglobulin M and G were assayed by nephelometry, and lipoprotein(a) was determined by ELISA. Cardiovascular disease (CVD) was identified on a clinical basis.

RESULTS

Serum HGF was directly associated with the presence of viral hepatitis, alanine aminotransferase and TM levels, time on HD, the presence of CVD, CRP and alpha(1)-antitrypsin levels, use of unfractionated heparin (UFH) (vs enoxaparin) during HD, dose of UFH, use of recombinant erythropoietin (rHuEpo) treatment, and Kt/V. In 36 patients not treated with rHuEpo, HGF directly correlated with haemoglobin, but not with endogenous Epo levels. There was no association between HGF and the other endothelial and inflammatory markers, gender, age, smoking, cause of renal failure, body mass index, normalized protein catabolic rate, dialysate buffers, dialysers, blood pressure, antihypertensive treatment, leukocyte and platelet counts, albumin, fibrinogen, lipoprotein(a), markers of iron and calcium-phosphorus metabolism, or metabolic acidosis. Positive viral hepatitis markers, prevalent CVD and rHuEpo treatment (in descending order of significance) were independent predictors of high HGF level. In another 20 HD patients, a 4-week course of rHuEpo treatment resulted in a significant 17% increase in circulating HGF levels.

CONCLUSION

Serum HGF levels in HD patients are determined by inflammatory conditions such as viral hepatitis and CVD, increase in response to rHuEpo treatment, and may be influenced by type and dose of heparin used during HD procedures.

Effects of recombinant erythropoietin therapy on circulating endothelial markers in hemodialysis patients

Effects of a 4-week course of recombinant human erythropoietin (rHuEpo) therapy on four circulating endothelium-derived cardiovascular risk markers were studied in 20 patients receiving maintenance hemodialysis in relation to surrogates of chronic inflammation, liver function, and arterial blood pressure. Soluble intercellular adhesion molecule-1 (sICAM-1), antigens of plasminogen activator inhibitor-1 (PAI-1:Ag) and von Willebrand factor (vWF:Ag), and soluble thrombomodulin (sTM) were determined by immunoenzymatic assays. C-reactive protein; alpha1 acid-glycoprotein; alpha1-antitrypsin; immunoglobulin M, A, and G; interleukin-6; lipoprotein(a); fibrinogen; total protein; albumin; total cholesterol; hepatitis B and C markers; liver enzymes; prothrombin time; and phosphorus were measured by routine methods. The rHuEpo treatment resulted in a 25% increase in sICAM-1 (Wilcoxon's p = 0.001), a 50% increase in PAI-1:Ag (p = 0.004), a 15% increase in sTM (p = 0.002), and did not change vWF:Ag levels. The increase in sICAM-1 concentration directly correlated with that of PAI-1:Ag (Spearman's rho = 0.483, p = 0.031). The rHuEpo-induced increases in hemoglobin, platelets, and pre-dialysis diastolic blood pressure levels did not correlate with the increments in the endothelial markers studied. In conclusion, short-term rHuEpo therapy activates vascular endothelium in patients receiving maintenance hemodialysis. This specific effect may influence cardiovascular risk.