Alterations in soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in hemodialysis patients

Relationship between vascular cell adhesion molecule-1 (VCAM-1), soluble receptor for advanced glycation end products (sRAGE) and functional hemodynamic parameters of arteriovenous fistula

BACKGROUND

The preferred vascular access for hemodialysis is represented by arteriovenous fistula (AVF) due to fewer complications and more prolonged survival. Considerable efforts have been made to identify biomarkers associated with AVF dysfunction, but results are conflicting. Vascular cell adhesion molecule (VCAM-1) and advanced glycation end products are involved in atherogenesis, vascular calcification, peripheral artery disease, and neointimal hyperplasia in renal and non-renal patients. The objective of this study was to evaluate whether there is an association between VCAM-1, soluble receptor for advanced glycation end products (sRAGE), NcarboxymethylLysine (CML), and arteriovenous fistula dysfunction (AVF).

METHODS

VCAM-1, sRAGE, and CML were performed using the ELISA technique in 88 HD patients. Ultrasound assessment of AVF reports brachial artery blood flow (Qa), brachial resistivity index (RI), presence of calcification, and the diameter. AVF dysfunction was defined as a brachial artery Qa ⩽ 500 ml/min or RI ⩾ 0.5.

RESULTS

The median level of VCAM-1 [2676.5(2206.8-4203.9) versus 2613.2(1885.7-3161.8), p 0.026] was significantly higher in patients with AVF dysfunction compared to the rest of the patients. sRAGE and CML were higher in this group but without statistical significance. In patients with AVF dysfunction, significant positive correlations were found between VCAM-1and sRAGE (r = 0.417, p = 0.001), RI (r = 0.313, p = 0.046), dialysis vintage (r = 0.540, p < 0.001), AVF vintage (r = 0.336, p = 0.032), intima-media thickness (r = 0.423, p = 0.006) and C-reactive protein (r = 0.315, p = 0.045). VCAM-1 correlated inversely with cholesterol (r = -0.312, p = 0.047), triglycerides (r = -0.358, p = 0.021), body mass index (r = -0.388, p = 0.012). In multivariate regression analysis, VCAM-1 (p = 0.013) and sRAGE (p = 0.01) remained significant predictors of RI and Qa. Logistic regression disclosed calcification, VCAM-1, as risks factors for AVF dysfunction.

CONCLUSION

The results we obtained showed that patients with AVF dysfunction had a significantly higher level of VCAM-l. A positive correlation between VCAM-1 and sRAGE was identified in this group.

Effect of Synbiotic and Probiotic Supplementation on Serum Levels of Endothelial Cell Adhesion Molecules in Hemodialysis Patients: a Randomized Control Study

The aim of this study was to investigate the effect of synbiotic and probiotic supplementation on serum vascular dysfunction and necrosis markers in hemodialysis (HD) patients. In this randomized, double-blind, placebo-controlled trial, 75 HD patients were randomly assigned to either the synbiotic or probiotic or placebo group. The patients in the synbiotic group received 15 g of prebiotics and 5 g probiotic powder containing Lactobacillus acidophilus strain T16 (IBRC-M10785), Bifidobacterium bifidum strain BIA-6, Bifidobacterium lactis strain BIA-6, Bifidobacterium longum strain LAF-5 (2.7 × 10⁷ CFU/g each) in sachets (n = 25), whereas the probiotic group received 5 g probiotics same to the first group with 15 g of maltodextrin powder in sachets (n = 25) and the placebo group received 20 g of maltodextrin powder in sachets (n = 25) for 12 weeks. At baseline and the end of the study, serum concentrations of soluble intercellular adhesion molecule type 1 (sICAM-1), soluble vascular cell adhesion molecule type 1 (sVCAM-1), cytokeratin 18 (CK-18) as the necrosis marker, uric acid, and phosphate levels were measured. Feces also were collected for microbiota colony counting. Serum ICAM-1 level reduced significantly in the synbiotic group after the intervention period (P = 0.02), and this reduction was significantly different in the synbiotic group in comparison to the placebo group (P = 0.03). Serum levels of VCAM-1 and CK-18 were not significantly different between the groups. However, the reduction in serum levels of VCAM-1 in the synbiotic group was significantly higher in comparison to the placebo group (P = 0.01). Multivariate linear regression analysis revealed that ∆ phosphate was the sole independent determinant of ∆ICAM-1 (P = 0 < 001). The study indicated that synbiotic supplementation reduced serum ICAM-1 level, which is a risk factor for cardiovascular diseases in HD patients, but has no effect on the necrosis marker. Trial registration: www.irct.ir (IRCT2017041233393N1).

The Effect of Vitamin D Administration on Intracellular Adhesion Molecule-1 and Vascular Cell Adhesion Molecule-1 Levels in Hemodialysis Patients: A Placebo-controlled, Double-blinded Clinical Trial

Objective:

Vitamin D deficiency is quite common among end-stage renal disease (ESRD) patients, and Vitamin D administration could reduce morbidity and mortality in these patients through different mechanisms. Cardiovascular diseases are the most common cause of mortality in these patients that are caused by vascular injuries. Intracellular adhesion molecule (ICAM) and vascular cell adhesion molecule (VCAM) are vascular inflammation indicators. The goal of this study is to find the effect of Vitamin D administration on ICAM-1 and VCAM-1 serum levels in ESRD patients on hemodialysis.

Methods:

The current study is a double-blind, randomized, placebo-controlled clinical trial on 64 patients in two groups of control and treatment. Serum levels of Vitamin D, ICAM-1, and VCAM-1 were measured before and after the study. Treatment group was treated with Vitamin D pearls while control group underwent treatment with placebo pearls. Average serum levels of Vitamin D, ICAM, and VCAM were measured in both groups before and after the study and were analyzed by ANOVA, paired t-test, and Chi-square test using SPSS software.

Findings:

Sixty-four ESRD patients were recruited for this study consisting of 32 male and 32 female subjects within the ages of 18 and 76 years. The change in serum level of Vitamin D was significant in treatment group (P = 0.001) but not in control group (P > 0.05). Serum levels of ICAM and VCAM also changed significantly in treatment group (P = 0.001) but not in control group (P > 0.05)

Conclusion:

Based on the findings of this study, it could be said that Vitamin D administration in ESRD patients may increase serum level of Vitamin D up to four times. It also reduces serum levels of ICAM and VCAM which might improve the vascular condition of these patients.

High cut-off dialysis in chronic haemodialysis patients reduces serum procalcific activity

BACKGROUND

Vascular calcification is enhanced in chronic dialysis patients, possibly due to the insufficient removal of various intermediate molecular weight uraemic toxins such as interleukins with conventional membranes. In this study, we assessed the modulation of in vitro vascular calcification with the use of high cut-off (HCO) membranes in chronic dialysis patients.

METHODS

In a PERCI trial, 43 chronic dialysis patients were treated with conventional high-flux and HCO filters for 3 weeks in a randomized order following a 2-period crossover design. After each phase, serum predialysis samples were drawn. Calcifying human coronary vascular smooth muscle cells (VSMCs) were incubated with the patient's serum samples. Calcification was assessed with alkaline phosphatase (ALP) and alizarin red staining. In the clinical trial, HCO dialysis reduced the serum levels of the soluble tumour necrosis factor receptor (sTNFR) 1 and 2, vascular cell adhesion molecule 1 (VCAM-1) and soluble interleukin-2 receptor (sIL2R). We therefore investigated the in vitro effects of these mediators on vascular calcification.

RESULTS

VSMCs incubated with HCO dialysis serum showed a 26% reduction of ALP with HCO serum compared with high-flux serum. Alizarin was 43% lower after incubation with the HCO serum compared with the high-flux serum. While sIL2R and sTNFR 1 and 2 showed no effects on VSMC calcification, VCAM-1 caused a dose-dependent enhancement of calcification.

CONCLUSIONS

The use of HCO dialysis membranes in chronic dialysis patients reduces the procalcific effects of serum on VSMC in vitro. The mechanisms of the strong effect of HCO on in vitro calcification are not completely understood. One factor may be lower levels of VCAM-1 in HCO serum samples, since VCAM-1 was able to induce vascular calcification in our experiments. Neither sTNFR 1, sTNFR 2 nor sIL2R enhance vascular calcification in vitro. Regardless of the mechanisms, our results encourage further studies of highly permeable filters in chronic dialysis patients.

Changes in serum asymmetric dimethylarginine and endothelial markers levels with varying periods of hemodialysis

Asymmetric dimethylarginine (ADMA) as a uremia toxin is accumulated in end-stage renal disease (ESRD) patients. Elevated ADMA level has been shown to be predictive of cardiovascular diseases (CVDs) and all-cause mortality in ESRD. Therefore, we investigated the effect of prolonged hemodialysis (HD) treatment on the levels of serum ADMA, arginine, nitric oxide (NO), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1). Seventy-five patients (M/F = 40/35) with chronic renal failure (CRF) and who were on HD were divided into five groups with differing treatment periods of HD; from 6 to 24 months to 97-120 months. Fifteen apparently healthy subjects acted as controls. The serum levels of ADMA, sICAM-1 and sVCAM-1 were increased in all patient groups compared to the control group. No significant difference was observed when the patient groups were compared in terms of HD treatment periods. Nitric oxide levels were lower in the three groups who were treated for periods of 49-72, 73-96, 97-120 months compared to the control group. The L-arginine to ADMA ratio was decreased in all patient groups compared to controls. Consequently, our investigations have shown that in HD continued for more than 4 years NO levels began to decrease significantly and the levels of serum ADMA, sICAM-1 and sVCAM-1 levels increased although this increase was not affected by the period in which hemodialysis treatment was applied.

Cyanate is a novel inducer of endothelial icam-1 expression

AIM

Recent work has shown that humans are significantly exposed to isocyanic acid/cyanate, which is generated when coal, biomass, or tobacco is burned. In vivo, cyanate is formed by the phagocyte protein myeloperoxidase and by breakdown of urea. Carbamylation of proteins through cyanate has been demonstrated to predict cardiovascular risk and is thought to promote vascular dysfunction; however, the underlying mechanisms remain unclear.

RESULTS

Here, we show that cyanate induces intercellular cell adhesion molecule-1 (ICAM-1) expression with subsequently enhanced neutrophil adhesion in human coronary artery endothelial cells. Cyanate triggers ICAM-1 expression through a mechanism depending on activation of the mitogen-activated protein kinase p38 and nuclear factor-kappaB. Endothelial ICAM-1 expression was not induced when low-molecular-weight substances were removed from cell culture medium, thus ruling out a role of carbamylated (lipo)proteins in ICAM-1 induction. In mice, oral administration of cyanate induced marked endothelial ICAM-1 expression in the aorta. Moreover, in patients with end-stage renal disease, the extent of plasma protein carbamylation (a marker for cyanate exposure) significantly correlated with plasma levels of soluble ICAM-1.

INNOVATION

Here, we demonstrate for the first time that cyanate, rather than carbamylated lipoproteins, induces vascular ICAM-1 expression in vivo.

CONCLUSION

Collectively, our data raise the possibility that cyanate amplifies vascular inflammation, linking inflammation, smoking, and uremia.

Elevated soluble cellular adhesion molecules are associated with increased mortality in a prospective cohort of renal transplant recipients

Background

Increased plasma levels of cellular adhesion molecules (CAMs) have been shown to be predictors of all cause mortality in individuals with chronic renal failure [1,2] and patients with end-stage renal disease receiving haemodialysis [3]. In renal transplant recipients the predictive value of CAMs has not been well characterised. The aim of this study was to assess the relationship between CAMs and all-cause mortality during prospective follow-up of a renal transplant cohort.

Methods

A total of 378 renal transplant recipients were recruited between June 2000 and December 2002. Soluble vascular CAM-1 (VCAM) and soluble intercellular CAM-1 (ICAM) were measured at baseline and prospective follow-up data was collected at a median of 2441 days after enrolment.

Results

In univariate survival analysis the renal transplant recipients with a VCAM or ICAM concentration in the lowest third were significantly more likely to have survived at follow-up (p < 0.001 and p = 0.009 respectively). In multivariate survival analysis VCAM and ICAM remained significant independent predictors of mortality following adjustment for traditional cardiovascular risk factors, hsCRP and estimated GFR (p = 0.030 and p = 0.037 respectively).

Conclusions

The results of this prospective study are the first to show that the CAMs, ICAM and particularly VCAM, are significant independent predictors of mortality in patients with a renal transplant.

Carotid atherosclerosis and endothelial cell adhesion molecules as predictors of long-term outcome in chronic hemodialysis patients

BACKGROUND/AIMS

Cardiovascular disease (CVD) remains the leading cause of increased morbidity and mortality for hemodialysis (HD) patients. The aim of this study was to investigate the predictive values of carotid artery atherosclerotic lesions and endothelial adhesion molecule levels for long-term outcome in non-diabetic HD patients.

METHODS

112 HD patients (60 male, mean age 59 years) consecutively entered the study. Atherosclerotic disease was assessed by measuring the mean and maximum intima-media thickness (IMT and IMTmax respectively) of the common carotid arteries using an ultrasound scanner. Circulating intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) levels were measured by ELISA. Patients were followed for the next 5 years and primary end points on follow-up were all-cause death, death from CVD causes and incidence of a CVD event.

RESULTS

Kaplan-Meier analysis showed that survival curves for all-cause mortality, CVD mortality and morbidity differed significantly between the upper and lower tertiles of baseline IMT (p = 0.002, p = 0.01 and p = 0.001 respectively) and IMTmax values (p = 0.0007, p = 0.006 and p = 0.0003 respectively), as well as ICAM-1 (p = 0.008, p = 0.003 and p = 0.02 respectively) and VCAM-1 levels (p = 0.004, p = 0.012 and p = 0.025 respectively). In non-adjusted analysis all-cause mortality and CVD mortality and morbidity were significantly associated with IMT (p = 0.003, p = 0.01 and p = 0.001 respectively) and IMTmax values (p = 0.001, p = 0.007 and p = 0.0007 respectively). After adjusting for other significant covariates, IMT values remained associated only with CVD morbidity (p = 0.03), while IMTmax were associated with both CVD mortality and morbidity (p = 0.03 and p = 0.01 respectively). All-cause mortality and CVD mortality and morbidity were also significantly associated with serum ICAM-1 (p = 0.004, p = 0.005 and p = 0.01 respectively) and VCAM-1 levels (p = 0.008, p = 0.02 and p = 0.03 respectively). After adjusting for the same covariates, the associations between ICAM-1 and all-cause mortality and CVD mortality and morbidity remained significant (p = 0.02, p = 0.01 and p = 0.02 respectively), while serum VCAM-1 levels were independently associated only with all-cause mortality (p = 0.02).

CONCLUSIONS

In non-diabetic HD patients, carotid atherosclerosis and adhesion molecule levels are independent predictors of long-term clinical outcomes and may be useful surrogate markers for risk stratification in these patients.

Circulating levels of adhesion molecules in chronic kidney disease correlate with the stage of renal disease and with C-reactive protein

BACKGROUND

Patients with chronic renal failure (CRF) suffer from a series of complications linked to the atherosclerotic process in which the endothelial dysfunction mediated by the activation of some adhesion molecules plays an important role. This study aims to evaluate circulating levels of intercellular adhesion molecules-1 (ICAM-1) and vascular cell adhesion molecules-1 (VCAM-1) in patients with predialysis CRF, on maintenance hemodialysis (HD) and after kidney transplantation (KTx) and to correlate them with some inflammation and nutritional indexes.

METHODS

Thirty two patients with predialysis CRF, 30 on maintenance HD, 36 after KTx and 28 subjects as a control group (C) were included in this study. Circulating levels of ICAM-1 and VCAM-1 were assayed using a specific sandwich ELISA kit. As inflammation indexes, TNFalpha and C-reactive protein (CRP) and, as nutritional indexes, body mass index (BMI), serum albumin, cholesterol, triglycerides, and fibrinogen (F) were evaluated.

RESULTS

Serum levels of ICAM-1 and VCAM-1 were progressively higher from C to KTx patients, to those with CRF and those on HD (ANOVA for both; p <0.001). TNFalpha values were lower in HD subjects than in CRF patients, even if in both groups TNFalpha levels were greater than in Tx and control subjects. F and CRP were higher in CRF and HD vs. Tx and control subjects (ANOVA for both p <0.001). No significant correlations were observed between soluble adhesion molecules, albumin and cholesterol, whereas significant correlations were found between CRP and ICAM-1 (r = 0.41; p <0.01), CRP and VCAM-1 (r = 0.39; p <0.01) and between CRP and TNFalpha (r = 0.42; p <0.01). These correlations remained statistically significant even after adjustment for age and blood pressure (all p <0.01). BMI did not differ in the three patient groups.

CONCLUSIONS

Circulating levels of adhesion molecules in our study correlated positively with the stage of disease and with one of the inflammatory indexes (CRP), but not with nutritional indexes such as BMI, cholesterol and albumin. The clinical significance of our findings warrants further investigation.

Association of mineral metabolism with an increase in cellular adhesion molecules: another link to cardiovascular risk in maintenance haemodialysis?

BACKGROUND

Abnormal mineral metabolism is associated with increased cardiovascular morbidity and mortality. The exact pathogenesis linking mineral metabolism to cardiovascular risk is unknown. This study was undertaken to investigate the association between serum phosphate and/or Ca x PO(4) product with serum levels of soluble E-selectin (sE-selectin), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 and the degree of carotid artery atherosclerosis in patients on haemodialysis.

METHODS

Seventy-three patients (46 male, 27 female; mean age 48+/-13 years, on haemodialysis for 82+/-80 months) were included in the study. All patients were stable, had no evidence of vascular disease and/or active infection. Consecutive 6 months clinical and laboratory data were obtained for each patient from their medical records and mean values were used for analysis. Serum levels of soluble adhesion molecules were assayed by ELISA. All subjects underwent a detailed evaluation of the carotid arteries.

RESULTS

The percentage of patients who met all three targets of NKF-K/DOQI for phosphate, calcium and Ca x PO(4) product was 27.1%, whereas those who did not achieve the target in one, two or three parameters was 28.1, 17.7 and 14.6%, respectively. The sICAM-1 levels were significantly higher in patients who had hyperphosphataemia (serum phosphate >5.5 mg/dl; P = 0.044) and hypercalcaemia (serum calcium >9.5 mg/dl; P = 0.014), both sE-selectin and sICAM-1 levels were significantly higher in patients with Ca x PO(4) product levels above 55 mg(2)/dl(2) (P = 0.002 and P = 0.000, respectively). Soluble E-selectin and sICAM levels demonstrated a near-linear increase in parallel to the degree of deviation from mineral metabolism targets. Soluble E-selectin and sICAM levels were correlated with serum phosphate and Ca x PO(4) product, but there were no correlations between adhesion molecules and carotid measurements.

CONCLUSION

These findings suggest that in stable haemodialysis patients abnormal bone mineral metabolism was associated with increased soluble adhesion molecules. These alterations in adhesion molecules may favour the development of cardiovascular changes and contribute to high cardiovascular morbidity and mortality in patients with abnormal mineral metabolism.

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.

Impact of rHuEPO therapy initiation on soluble adhesion molecule levels in haemodialysis patients

BACKGROUND

Increased levels of soluble adhesion molecules have been reported in haemodialysis (HD) patients. Recent studies have shown that recombinant human erythropoietin (rHuEPO) elicits proliferation and migration of endothelial cells and modifies endothelial function. The present study was design to explore the effects of rHuEPO on serum levels of soluble adhesion molecules in HD patients.

METHODS

Soluble serum levels of E-selectin (sE-selectin), intracellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (sVCAM-1) were measured by ELISA in 29 rHuEPO naïve HD patients (20 males, 9 females) and 10 control subjects at baseline and second month. The HD patients with a haemoglobin level lower than 10.0 mg/dL (n = 19) were administered rHuEPO therapy and other HD patients (n = 10) were followed as a placebo group.

RESULTS

Serum levels of soluble adhesion molecules were significantly higher in HD patients compared with the control group. A significant rise from the baseline in sE-selectin levels (77 +/- 70 vs 100 +/- 86 ng/mL, P < 0.05) was observed 2 months after rHuEPO initiation, while sICAM-1 and sVCAM-1 levels decreased (271 +/- 261 vs 197 +/- 89 and 1043 +/- 243 vs 990 +/- 236 ng/mL, respectively, P < 0.05).

CONCLUSIONS

The present data indicate that rHuEPO could have an important action on serum levels of soluble adhesion molecules in HD patients. rHuEPO might modify the expression of adhesion molecules from endothelial cells either. However, the exact mechanism responsible for the serum elevation of these molecules in HD patients is yet to be fully elucidated.

Inflammation markers, adhesion molecules, and all-cause and cardiovascular mortality in patients with ESRD: searching for the best risk marker by multivariate modeling

Inflammation is a major risk factor for mortality and cardiovascular (CV) complications in patients with ESRD. The predictive value of C-reactive protein (CRP) of the main proinflammatory cytokines (IL-1beta, IL-6, IL-18, and TNF-alpha) and of two adhesion molecules (intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) in 217 dialysis patients was compared. Serum IL-6 and CRP added significant prediction power to the multivariate Cox model of all-cause death, and the gain in the prediction power attributable to IL-6 was approximately two times higher than that of CRP. Patients in the third tertiles of serum IL-6 and CRP had a relative risk of all-cause mortality 2.5 and 1.8 times higher than those in the first corresponding tertiles, and there was no statistical difference between these two relative risks. The gain in prediction power associated with TNF-alpha, IL-beta, IL-18, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 was of small degree (P = NS). Similarly, serum IL-6 added the highest prediction power to the CV death model, and the IL-6 attributable gain was approximately two times higher than that of serum CRP. However, the risk estimate for CV mortality of patients with high serum IL-6 did not differ significantly from that of patients with high serum CRP. IL-6 adds significantly greater predictive power for all-cause and CV death to statistical models based on traditional and nontraditional risk factors in ESRD patients. However, the risk estimate by CRP being reasonably close to that of IL-6, CRP may be a cheap alternative to IL-6 in clinical practice.

Influence of hepatitis C virus infection on soluble cellular adhesion molecules in hemodialysis patients

BACKGROUND/AIMS

Higher levels of soluble cellular adhesion molecules have been found to be a strong indicator of endothelial dysfunction and atherosclerosis in the general population. In hemodialysis patients, soluble cellular adhesion molecules have been found at higher levels as well. Such an increase has been considered as a sign of chronic inflammation. Chronic viral hepatitis C (HCV) infection, highly prevalent in hemodialysis patients, is also a disease that can induce chronic inflammation. We conducted a cross-sectional association study of soluble cellular adhesion molecules and hepatitis C in maintenance hemodialysis patients.

METHODS

A total of 87 stable hemodialysis patients were included in this study, mean age was 60.0 +/- 13.7 years. Anti-HCV antibody and HCV RNA assay were done. Patients were divided into anti-HCV-positive and anti-HCV-negative groups. Predialytic serum soluble intercellular adhesion molecules-1 (sICAM-1), soluble vascular cellular adhesion molecules-1 (sVCAM-1), and soluble E-selectin were assayed by commercially available enzyme-linked immunosorbent assay (ELISA) kits. The results were correlated with other hematological and biochemical results.

RESULTS

In the anti-HCV-positive group, the time on hemodialysis was longer (105.5 +/- 65.7 vs. 49.2 +/- 44.0 months, p = 0.001). The sICAM-1, sVCAM-1 and E-selectin levels were higher in the anti-HCV-positive group. HCV infection was determined as an independent determinant of sICAM-1 and sVCAM-1 by multiple linear regression analysis.

CONCLUSION

Elevated serum soluble cellular adhesion molecules are multifactorial in hemodialysis patients. The role of HCV infection must be considered. The clinical significance and implications of soluble cellular adhesion molecules remains to be elucidated.

Adhesion molecules and atherosclerosis

One early phase of atherosclerosis involves the recruitment of inflammatory cells from the circulation and their transendothelial migration. This process is predominantly mediated by cellular adhesion molecules, which are expressed on the vascular endothelium and on circulating leukocytes in response to several inflammatory stimuli. Selectins (P, E and L) and their ligands (mainly P-selectin ligand) are involved in the rolling and tethering of leukocytes on the vascular wall. Intercellular adhesion molecules (ICAMs) and vascular cell adhesion molecules (VCAM-1), as well as some of the integrins, induce firm adhesion of inflammatory cells at the vascular surface, whereas platelet endothelial cellular adhesion molecules (PECAM-1) are involved in extravasation of cells from the blood compartment into the vessel and underlying tissue. For most of the cellular adhesion molecules, except integrins, soluble forms have been identified in the circulation although their origins are not fully understood. Several lines of evidence support a crucial role of adhesion molecules in the development of atherosclerosis and plaque instability. Expression of VCAM-1, ICAM-1 and L-selectin has been consistently observed in atherosclerotic plaques. There is accumulating evidence from prospective studies for a predictive role of elevated circulating levels of sICAM-1 in initially healthy people, and of sVCAM-1 in patients at high risk or with overt CAD. A large number of common polymorphisms has been identified in the genes encoding the different adhesion molecules, but studies investigating their relationship either with soluble forms or with CAD are still sparse and often based on small samples. Further research is needed to firmly establish the potential clinical and therapeutic utilities of (soluble) adhesion molecules, but results in both fields hold the promise that in future, adhesion molecules might add information for clinical risk prediction and serve as therapeutic targets.

Soluble adhesion molecules in children and young adults on chronic hemodialysis

Children on chronic hemodialysis (HD) present with impaired immunity that may result from disturbances in leukocyte migration, caused by changes in expression of adhesion molecules on endothelium and immunocompetent cells. However, it is still not clear whether the type of dialyzer or a single dialysis session influences the concentrations of soluble adhesion molecules in these patients. We evaluated by ELISA serum levels of soluble (s) VCAM-1, ICAM-1, L-selectin, and P-selectin in 22 patients on cuprophane HD (CU), 8 on polysulfone HD (PS), 10 on vitamin E-modified cellulose HD (VE), and 15 controls. In all HD patients, sVCAM-1 levels were elevated compared with controls and were higher in CU than in VE. The sICAM-1 concentrations were increased in VE compared with controls, but remained unchanged in CU and PS. The sL-selectin levels were reduced in all HD patients. The mean values of sP-selectin were comparable in CU, PS, and controls. The lowest levels were observed in VE. In CU patients, sVCAM-1, sICAM-1, and sP-selectin concentrations rose after HD. A single PS session had no impact on adhesion molecules, whereas a VE session increased the level of sVCAM-1. The type of dialysis membrane may change the profile of adhesion molecule concentrations, thus influencing the immune system of a child on HD. The increase in levels of adhesion molecules in the course of a single HD session, which was pronounced in CU and VE patients, suggests poor biocompatibility of these dialyzers.

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.

Circulating levels of ICAM-1, VCAM-1, and MCP-1 are increased in haemodialysis patients: association with inflammation, dyslipidaemia, and vascular events

BACKGROUND

Increased levels of circulating adhesion molecules and chemokines have been reported in haemodialysis (HD) patients but the influence of the HD membranes on their secretion, as well as their pathophysiological implications, remains largely unknown.

METHODS

Circulating levels of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and monocyte chemoattractant protein-1 (MCP-1) were measured by immunosorbent assay (ELISA) in 81 HD patients (45 male, mean age 57+/-13 years) and 35 normal subjects. All patients had been stabilized on renal replacement therapy for >3 months and were free of active infection. Thirty-three patients (40.7%) were routinely dialysed with modified cellulose membranes and 48 patients (59.3%) were dialysed with polysulfone membranes. Blood samples were taken directly from the arteriovenous fistula immediately before and at the end of a routine HD session.

RESULTS

Pre-dialysis levels were significantly elevated in HD patients compared with controls (ICAM-1 515+/-177 vs 238+/-664 ng/ml, P<0.0001; VCAM-1 2107+/-648 vs 1012+/-115 ng/ml, P<0.0001; MCP-1 427+/-148 vs 125+/-42 pg/ml, P<0.0001). The HD session resulted in a significant increase in the levels of all three molecules measured (515+/-177 vs 679+/-187 ng/ml, P<0.0001; 2107+/-648 vs 2662+/-800 ng/ml, P<0.0001; 427+/-148 vs 567+/-153 pg/ml, P<0.0001, respectively). There was no difference in pre- or post-dialysis levels of the above molecules between patients routinely dialysed with either modified cellulose or polysulfone membranes. MCP-1 levels had a positive correlation with ICAM-1 levels (r=0.41, P<0.0005). VCAM-1 levels had a negative correlation with HDL levels (r=-0.30, P<0.01) and were significantly elevated in patients with HDL <35 mg/dl compared with patients with HDL > or = 35 mg/dl (2300+/-606 vs 1890+/-633 ng/ml, P<0.005). Log-transformed exact C-reactive protein (CRP) values were significantly correlated with ICAM-1 and VCAM-1 levels (r=0.41, P<0.005 and r=0.43, P<0.005, respectively). In addition, compared with patients with normal CRP values, patients with elevated CRP had significantly increased levels of ICAM-1 (466+/-166 vs 580+/-172 ng/ml, P<0.005). Patients with cardiovascular, cerebrovascular, or peripheral vascular diseases had significantly increased serum CRP and ICAM-1 levels compared with patients with no evidence of vascular disease (19.2+/-12.9 vs 7.9+/-11.8 mg/l, P<0.001 and 608+/-189 vs 474+/-155 ng/ml, P<0.005 respectively).

CONCLUSIONS

Serum levels of ICAM-1, VCAM-1, and MCP-1 are increased in HD patients and probably result from either inadequate clearance or enhanced synthesis and release. HD session resulted in a significant increase of the above molecule levels but the exact mechanism(s) responsible for these alterations are yet to be fully elucidated. Increased levels of adhesion molecules are associated with inflammation, dyslipidaemia, and cardiovascular events. However, the potential link between these processes and its clinical significance warrants further investigation.

Implications for the role of endogenous nitric oxide inhibitors in hemodialysis hypotension

Hypotensive episodes during hemodialysis in patients with end-stage renal disease in the absence of inadequate maintenance of the plasma volume, pre-existence of cardiovascular disease, or autonomic nervous system dysfunction is accompanied by increase in the plasma concentrations of the end-products of nitric oxide metabolism, above the levels expected based on the reduction of urea. Factors that can influence the synthesis of nitric oxide or the regulation of the effects of this free radical in patients with chronic renal failure are reviewed. Convergence of these factors and their interactions during the hemodialysis procedure are discussed as the basis for the generation of excessive amounts of nitric oxide that serves as an important contributing factor in the development of symptomatic hypotension.

Elevated serum levels of soluble adhesion molecules predict death in pre-dialysis patients: association with malnutrition, inflammation, and cardiovascular disease

BACKGROUND

Atherosclerotic cardiovascular disease, malnutrition, and increased levels of pro-inflammatory cytokines are common features in patients with chronic renal failure, and contribute to the high mortality rate observed in these patients. A diverse group of soluble cellular adhesion molecules (CAM) (sVCAM-1, sICAM-1 and sE-selectin) are expressed on the surface of vascular endothelial cells in response to pro-inflammatory cytokines and may play an important role in the atherogenic process.

METHODS

Serum levels of sVCAM-1, sICAM-1 (n=87) and sE-selectin (n=71) were analysed in a cohort of 88 patients (50+/-1 years) with chronic renal failure. The presence of malnutrition (subjective global assessment (SGA) and serum albumin), inflammation (C-reactive protein (CRP), tumour necrosis factor-alpha (TNF-alpha), and serum hyaluronan), and cardiovascular disease (CVD) were assessed at a time-point close to the start of dialysis treatment (GFR 7+/-1 ml/min). Blood lipid parameters were also assessed.

RESULTS

Significant correlations were observed between Log high-sensitivity CRP (hsCRP) and sVCAM-1 (R=0.39; P<0.01) and sICAM-1 (R=0.47; P:<0.001) levels but not between Log hsCRP and sE-selectin levels in 60 patients examined with a hsCRP assay. Also serum concentrations of Log hyaluronan correlated significantly to sVCAM-1 (R=0.34; P<0.01) and sICAM-1 (R=0.29; P<0.05) levels. Malnourished patients (SGA>1) had elevated serum concentrations of sVCAM-1 (1436+/-94 vs. 1105+/-53 ng/ml; P<0.01) compared to well-nourished patients (SGA 1). Patients with clinical signs of CVD (n=26) had elevated serum levels of sICAM-1 (282+/-18 vs. 242+/-9 ng/ml; P<0.05) compared to 61 patients without signs of CVD. Plasma Log lipoprotein (a) (Lp(a)) levels correlated significantly with sVCAM-1 (R=0.30; P<0.01). Survival analysis by the Cox regression model showed that elevated sICAM-1 was, independent of age, SGA, CVD, and Log CRP, significantly related to an increased mortality rate.

CONCLUSIONS

Elevated serum concentrations of soluble adhesion molecules are found in pre-dialysis patients who are malnourished, inflamed, and have signs of cardiovascular disease. These data also suggest that sICAM-1 is an independent predictor of mortality in pre-dialysis patients. Further studies are needed to determine if inflammation causes accelerated atherogenesis via effects on soluble adhesion molecules or if elevated serum levels of soluble adhesion molecules are merely markers of endothelial activation in patients with chronic renal failure.

Three monocyte-related determinants of atherosclerosis in haemodialysis

BACKGROUND

It has been suggested that monocyte-related inflammatory mediators play a role in atherosclerosis. Haemodialysis induces phenotypic changes in adhesion molecule expression on monocytes. Soluble vascular cell adhesion molecule-1 (sVCAM-1), an adhesion molecule involved in monocyte recruitment, has been proposed to correlate with the extent of atherosclerosis in humans. Monocyte chemotactic protein-1 (MCP-1) functions as a monocyte-specific chemoattractant.

METHODS

We studied monocyte count, CD11b/CD18 expression on monocytes, MCP-1, and sVCAM-1 in nine patients on either cuprophane or polysulphone haemodialysis (n=18 treatments) at times 0 (before haemodialysis), 3 h (end of haemodialysis), 4, 6, 8 and 24 h after start of treatment, as well as in 18 healthy subjects.

RESULTS

Monocyte CD11b/CD18 expression increased with both membranes (P:<0.001) during and after dialysis compared to before treatment. The concentrations of sVCAM-1 and MCP-1 were higher in patients compared to those in controls both before, during and after haemodialysis (P:<0.001 at all time points). There were correlations between the expression of CD11b/CD18 on monocytes and the interdialytic concentrations of sVCAM-1 (r=0.76, P:<0.001) and MCP-1 (r=0.54, P:<0.05) and between MCP-1 and sVCAM-1 before and after haemodialysis (P:<0.05).

CONCLUSION

Patients on haemodialysis have an increased systemic chemotactic activity for monocytes, unphysiological phenotypic alterations in CD11b/ CD18 expression during and after dialysis, and increased sVCAM-1 and MCP-1 concentrations. Prospective studies are needed to establish the role of these abnormalities in the pathogenesis of atherosclerosis in haemodialysis patients.

In vivo visualization of hemodialysis-induced alterations in leukocyte-endothelial interactions

BACKGROUND

The aim of this study was to develop a model for hemodialysis (HD) in small animals using conventional dialysis equipment that would allow the intravital microscopic observation of leukocyte-endothelial interactions in vivo.

METHODS

Cuprophan dialyzers were adapted to obtain a similar ratio of membrane area to blood volume as in clinical HD. A silicone ring was inserted into the dialyzer's inlet to limit the number of blood-perfused capillaries. Rabbits were dialyzed for one hour without a dialysate flow.

RESULTS

Extracorporeal circulation with the cuprophan dialyzer resulted in a transient leukopenia and complement activation. At the nadir of leukopenia, leukocytes that rolled along the venular wall were scarcely observed, whereas rolling was abundant (54 +/- 9 per min) prior to extracorporeal circulation. The adhesion of leukocytes to the vascular endothelium was not induced. After 60 minutes, rolling of leukocytes was still reduced by 73 +/- 5.5%, despite the full recovery of circulating leukocyte counts. Extracorporeal circulation without a dialyzer also tended to reduce leukocyte rolling, although systemic leukocyte counts were not affected.

CONCLUSIONS

The use of adapted conventional cuprophan hemodialyzers in rabbits yielded a transient leukopenia similar to that in clinical HD. Using intravital microscopy, we demonstrated impairment of leukocyte-endothelial interactions. In addition, our data indicate that tissues, in which leukocytes can roll and adhere, are not automatically sites of leukocyte sequestration during HD-induced leukopenia.

The leukointegrin alpha d/beta 2 (alpha d/CD18): specific changes in surface expression in patients on hemodialysis

Alpha d/CD18 is a newly discovered leukocyte adhesion molecule with sequence homology to CD11a, b and c of the beta 2 integrin family. Little is known about alpha d expression in vivo, particularly how it compares with the other beta 2 integrins. Previous studies have demonstrated that beta 2 integrin expression, particularly CD11b, is upregulated in vivo during hemodialysis (HD) with complement activating membranes. These changes may contribute to the immunologic abnormalities seen in HD patients. Given the well described changes of beta 2 integrins in these patients, we hypothesized that alpha d expression could also be altered by HD. Using flow cytometry with two specific antibodies to alpha d, alpha d expression in healthy adults (n = 16) was compared on macrophages (MO) > polymorphonuclear cells (PMNs) > lymphocytes (LY). Phorbol ester treatment of leukocytes in vitro significantly increased expression on MO and PMN, but not LY. Chronic HD patients at baseline (n = 15) had elevated (P < 0.05) alpha d mean channel fluorescence (MCF) on MOs, PMNs and LYs compared to normals. PMN alpha d MCF increased at 15 min into HD, but then returned to baseline levels at 180 min. Alpha d MCF for LYs decreased at 180 min, while MOs levels were unchanged. Alpha d expression is increased in chronic renal failure and further regulated by hemodialysis, but with unique characteristics compared to the other beta 2 integrins. Alpha d may be important in abnormal cell-cell contacts in renal failure.