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Background Hyperuricemia is common among kidney transplant recipients and has been associated with worse graft outcome. Since episodes of acute cellular rejection and chronic humoral rejection contribute to decreased graft survival, in this study the effect of uric acid on cellular and humoral alloimmunity was evaluated. Methods Cellular alloimmunity was assessed by cell proliferation in two-way mixed lymphocyte reaction (MLR) with human peripheral blood mononuclear cells (PBMC). For assessing humoral alloimmunity we developed a method in which humoral alloimmunity was induced in one-way MLR. Then the de novo production of alloantibodies was measured with an antibody-mediated complement-dependent cytotoxicity assay, in which supernatants from the above MRLs were used against resting PBMC similar to the stimulator cells of the above MLRs. Results Uric acid at a concentration above its crystallization threshold increased cellular proliferation in two-way MLRs. Supernatants from one-way MLRs performed in the presence of uric acid were more cytotoxic against PBMC from individuals that had conferred the stimulator cells for the above MLRs. Conclusions Uric acid increases both cellular and humoral alloimmunity in human PBMC. These results offer a possible pathogenetic mechanism for the observed relation between hyperuricemia and worse kidney allograft survival.

Considering the referred beneficial effects of protein restriction on diabetic nephropathy (DN) and the role of renal endothelium in its pathogenesis, we evaluated the effect of general control nonderepressible 2 (GCN2) kinase activation, a sensor of amino acid deprivation, on known detrimental molecular pathways in primary human glomerular endothelial cells (GEnC). GEnC were cultured under normal or high-glucose conditions in the presence or not of the GCN2 kinase activator, tryptophanol. Glucose transporter 1 (GLUT1) expression was assessed by western blotting and reactive oxygen species (ROS) using a fluorogenic probe. Activities of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and protein kinase C (PKC) were assessed by commercial activity assays, sorbitol colorimetrically, methylglyoxal by ELISA and O-linked β-N-acetyl glucosamine (O-GlcNAc)-modified proteins by western blotting. High glucose induced GLUT1 expression, increased ROS and inhibited GAPDH. Also it increased the polyol pathway product sorbitol, PKC activity, the level of the O-GlcNAc-modified proteins that produced by the hexosamine pathway and the advanced glycation endproducts’ precursor methylglyoxal. Co-treatment of GEnC with tryptophanol restored the above high-glucose-induced alterations. Activation of GCN2 kinase protects GEnC from high-glucose-induced harmful molecular pathways. By inhibiting concurrently many pathways involved in DN pathogenesis, GCN2 kinase may serve as a pharmaceutical target for the treatment of DN.

Mitochondrial reactive oxygen species (ROS) overproduction in capillary endothelial cells is a prerequisite for the development of diabetic nephropathy. Inhibition of xanthine oxidase, another ROS generator, ameliorates experimental diabetic nephropathy. To test the hypothesis that the initial high glucose-induced ROS production by the mitochondria activates xanthine oxidase, which afterward remains as the major source of ROS, we cultured primary human glomerular endothelial cells (GEnC) under normal or high-glucose conditions, with or without the xanthine oxidase inhibitor allopurinol. ROS generation and nitric oxide synthase (NOS) activity were assessed by chemiluminescence or colorimetrically. Levels of intercellular adhesion molecule 1 (ICAM-1), p53 and phosphorylated p53 (p-p53) were assessed by western blotting. Allopurinol prevented high glucose-induced ROS generation indicating that xanthine oxidase is the major source of ROS. Allopurinol protected GEnC from endothelial dysfunction since it prevented the high glucose-induced decrease in NOS activity and increase in ICAM-1 expression. Allopurinol reduced p53 and p-p53 levels induced by high glucose suggesting an axis of xanthine oxidase-derived ROS, DNA damage, p53 stabilization and endothelial dysfunction that may contribute to the pathogenesis of diabetic nephropathy. Allopurinol protects GEnC from high glucose-induced ROS generation, p53 overexpression and endothelial dysfunction. These data provide a pathogenetic mechanism that supports the results of experimental and clinical studies about the beneficial effect of xanthine oxidase inhibitors on the development of diabetic nephropathy.

Acute cellular rejection is the major cause of immune-mediated graft failure early in the course of kidney transplantation, whereas chronic antibody-mediated rejection is a major contributor to graft loss in the late post-transplant phase. Based mainly on the results of short-term studies, the calcineurin inhibitor tacrolimus prevails over the mammalian target of rapamycin (mTOR) inhibitors. However, the toxicity profile of the two drug categories differs, making the interchange between them appealing. In this study, the effect of tacrolimus and of the mTOR inhibitor everolimus on cellular and humoral alloimmunity was evaluated. Cellular alloimmunity was assessed by cell proliferation in two-way mixed lymphocyte reaction (MLR) with human peripheral blood mononuclear cells (PBMC). For assessing humoral alloimmunity, we developed a method in which humoral alloimmunity was induced in a one-way MLR. The de novo production of alloantibodies was measured with an antibody-mediated complement-dependent cytotoxicity assay, in which supernatants from the above MLRs were used against resting PBMC similar to the stimulator cells of the forementioned MLRs. Tacrolimus and everolimus were used at concentrations near their upper recommended trough levels. In two-way MLRs, tacrolimus inhibited cell proliferation more than everolimus. In one-way MLRs, tacrolimus and everolimus decreased alloantibody production to the same extent. In human cell cultures, everolimus is inferior to tacrolimus in inhibiting cellular alloimmunity, but equally effective as regards humoral alloimmunity. Thus, everolimus might be a safe alternative in case of tacrolimus toxicity, particularly after the early period of kidney transplantation.

Disturbed iron homeostasis contributes to resistance to recombinant human erythropoietin (rHuEpo) in hemodialysis (HD) patients. Although increased hepcidin, which downregulates the iron exporter ferroportin, had been incriminated, such an association has not been confirmed. Albeit not universally accepted, it has been supported that in case of copper deficiency, decreased activity of multicopper oxidases induces endocytosis and degradation of ferroportin. Ferroportin in monocytes, serum copper, ceruloplasmin and markers of iron status were measured, and associations with rHuEpo resistance index (ERI) were evaluated. After a 4-week washout period from iron treatment, 34 HD patients and 20 healthy volunteers enrolled in the study. Ferroportin was assessed by means of Western blotting, copper colorimetrically, whereas ceruloplasmin with enzyme-linked immunosorbent assay. Hemoglobin, serum iron, ferritin and transferrin saturation (TSAT) were also measured. Ferroportin in monocytes of HD patients was decreased. Serum copper, ceruloplasmin, iron and TSAT were decreased. No correlation between copper or ceruloplasmin and ferroportin was detected. ERI was negatively correlated with ferroportin and all the markers of iron adequacy, but not with copper or ceruloplasmin. Although copper deficiency and decreased ferroportin are common in HD patients, copper might not play role in ferroportin level in monocytes and in iron metabolism in this population.

A 77-year-old man, 11 years under chronic hemodialysis treatment for chronic renal failure of unknown origin, presented with anterior chest pain, dyspnea with paradoxical breathing, and sternal instability after a simple fall from a standing height. Patient underwent three-vessel coronary artery bypass grafting 31 months ago. Computed tomography with three-dimensional volume rendering showed sternal nonunion with a great gap between the two halves of the sternum and at least one fracture in the left half of the sternum. A successful surgical repair followed. Patient suffered from severe secondary hyperparathyroidism for many years. Despite treatment with sevelamer, paricalcitol and cinacalcet, intact parathyroid hormone was 1682 pg/mL. During the last 5 years, serum intact parathyroid hormone remained steadily above 1000 pg/mL. Patient refused parathyroidectomy in the past. We assume that long-lasting severe hyperparathyroidism contributed to this rare and life-threatening complication of median sternotomy in our patient, due to the detrimental effect of hyperparathyroidism on bone metabolism and its association with increased incidence of bone fractures and defect in bone fracture healing.

We describe a case of a patient with a functional kidney transplant who was admitted to our department with clinically evident central vein stenosis (CVS) 7 years after the removal of a central venous catheter (CVC) from the right internal jugular vein. The catheter was used as a hemodialysis access for a 2-month period. In the interval before his last admission, the patient suffered two episodes of deep vein thrombosis. Investigation revealed heterozygosity for factor V Leiden, the most common inherited thrombophilia encountered in 5% of Caucasians, and anticoagulation treatment was started. Magnetic resonance angiography showed stenosis just after the convergence of the right subclavian vein with the internal jugular vein to the innominate vein. Transluminal angioplasty restored venous patency and right upper arm edema resolved. Coexistence of CVS, accompanied by hemodynamic changes and endothelial dysfunction, with thrombophilia fulfill all the elements of the Virchow's triad. Therefore, the patient was at great risk for central vein thrombosis, from which he was possibly protected by the early administration of anticoagulant treatment. This case indicates that CVS can be asymptomatic for several years after CVC removal and also raises the question if thrombophilia workup and investigation for CVS may be beneficial in every patient with CVC placement in order to avoid any harmful outcomes.

Studies detected an association between visfatin and markers of iron metabolism in patients with insulin resistance. In this study, such a relation was evaluated in hemodialysis (HD) patients. Also relations between visfatin and hepcidin, demands for recombinant human erythropoietin (rHuEpo), inflammation, and situations characterized by insulin resistance were evaluated.After a four-week washout period from iron treatment, 33 HD patients and 20 healthy volunteers enrolled in the study. Serum visfatin, hepcidin, and interleukin-6 (IL-6) were assessed by means of enzyme-linked immunosorbent assay. Hemoglobin, serum iron, ferritin, and transferrin saturation (TSAT) were also measured.Visfatin was markedly increased in HD patients. Visfatin levels did not differ between diabetics and non-diabetics. No relation was detected between visfatin and body mass index or IL-6 in HD patients. From the markers of iron metabolism, the hepcidin included, visfatin was related only to TSAT. A strong positive relation was revealed between visfatin and hemoglobin, whereas visfatin was inversely related to rHuEpo dose. Resistance to rHuEpo index was inversely and independently of TSAT related to visfatin.Visfatin is increased in HD patients and it is associated with decreased demands for rHuEpo.

Diabetic nephropathy is the leading cause of end-stage renal disease. Diabetes mellitus is characterized by generalized endothelial dysfunction. However, recent data also emphasizes the role of local renal endothelium dysfunction in the pathogenesis of diabetic nephropathy. Hyperglycemia triggers a complex network of signal-transduction molecules, transcription factors, and mediators that culminate in endothelial dysfunction. In the glomerulus, vascular endothelial growth factor-A (VEGF)-induced neoangiogenesis may contribute to the initial hyperfiltration and microalbuminuria due to increased filtration area and immaturity of the neovessels, respectively. However, subsequent decrease in podocytes number decreases VEGF production resulting in capillary rarefaction and decreased glomerular filtration rate (GFR). Decreased nitric oxide availability also plays a significant role in the development of advanced lesions of diabetic nephropathy through disruption of glomerular autoregulation, uncontrolled VEGF action, release of prothrombotic substances by endothelial cells and angiotensin-II-independent aldosterone production. In addition, disturbances in endothelial glycocalyx contribute to decreased permselectivity and microalbuminuria; whereas there are recent evidences that reduced glomerular fenestral endothelium leads to decreased GFR levels. Endothelial repair mechanisms are also impaired in diabetes, since circulating endothelial progenitor cells number is decreased in diabetic patients with microalbuminuria. Finally, in the context of elevated profibrotic cytokine transforming growth factor-β levels, endothelial cells also confer to the deteriorating process of fibrosis in advanced diabetic nephropathy through endothelial to mesenchymal transition.

Hemodialysis (HD) patients are characterized by impaired T-cell function at least in part because of T-cell zeta-chain downregulation due to inflammation. Angiogenin responds as an acute phase reactant, is increased in HD patients, suppresses T-cell function and increased angiogenin level is co-localized with T-cell zeta-chain downregulation in various pathologies. Angiogenin can inhibit translation of proteins, which lack internal ribosomal entry sites in the corresponding mRNAs. In this study, the possible effect of angiogenin on T-cell zeta-chain downregulation was evaluated. Thirty HD patients and 21 healthy volunteers participated. T-cell zeta-chain expression was assessed with flow cytometry, plasma angiogenin and serum IL-6 with ELISA and serum C-reactive protein with an immunoturbidimetric method. Two available software tools were used for predicting the presence or not of internal ribosomal entry sites in T-cell zeta-chain mRNA sequence. In silico analysis of T-cell zeta-chain mRNA sequence failed to reveal the presence of internal ribosomal entry sites. T-cell zeta-chain expression was lower in HD patients than in healthy volunteers (1.86 ± 0.63 vs. 4.73 ± 3.22). In HD patients, C-reactive protein as well as IL-6 were higher than in healthy volunteers (10.04 ± 15.13 mg/L vs. 3.43 ± 0.98 mg/L and 15.06 ± 13.08 pg/mL vs. 2.11 ± 2.10 pg/mL respectively). Angiogenin was higher in HD patients than in healthy volunteers (483.20 ± 154.07 ng/mL vs. 259.98 ± 64.15 ng/mL). Neither C-reactive protein, nor IL-6 was associated with angiogenin or T-cell zeta-chain expression. Angiogenin concentration was negatively related to the expression of T-cell zeta-chain (r = -0.410, P = 0.025). Increased angiogenin may contribute to decreased T-cell zeta-chain expression in HD patients.

Acquired immunity is impaired in hemodialysis (HD) patients, and decreased T-cell number may contribute. Indoleamine 2,3-dioxygenase (IDO) and arginase type I (ARG) catabolize tryptophane and arginine, respectively, and exert proapoptotic and antiproliferative effects on T-cells. Plasma levels of IDO and ARG and their relation to blood T-cell number were evaluated in HD patients.Thirty-two HD patients and 20 healthy controls participated in the study. Plasma IDO and ARG were measured by means of enzyme-linked immunosorbent assay. T-cell number was assessed by means of flow cytometry.IDO concentration was significantly higher in HD patients than in healthy volunteers (44.30 ± 31.83 ng/mL vs. 21.28 ± 26.21 ng/mL, p = 0.009). There was a trend for higher ARG concentration in HD patients (13.43 ± 11.91 ng/mL) than in healthy volunteers (9.56 ± 4.03 ng/mL), which, however, did not reach statistic significance (p = 0.099). Absolute T-cell count was significantly lower in HD patients than in healthy controls (1176.99 ± 567.71 cells/mm3 vs. 1519.85 ± 594.96 cells/mm3, p = 0.040). Absolute blood T-cell number was inversely related to plasma IDO (r = -0.490, p = 0.004) and to plasma ARG (r = -0.387, p = 0.029) concentrations.Plasma IDO and ARG may contribute to decreased blood T-cell count in HD patients.

Perilipin-1 surrounds lipid droplets in both adipocytes and in atheroma plaque foam cells and controls access of lipases to the lipid core. In hemodialysis (HD) patients, dyslipidemia, malnutrition, inflammation and atherosclerosis are common. Thirty-six HD patients and 28 healthy volunteers were enrolled into the study. Ten HD patients suffered from coronary heart disease (CHD). Perilipin-1, triglycerides, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), body mass index, albumin, geriatric nutritional risk index, normalized protein catabolic rate, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were measured. Perilipin-1 did not differ between HD patients and healthy volunteers. IL-6 and TNF-α were higher in HD patients. The evaluated nutritional markers and the markers of inflammation did not differ between HD patients with high perilipin-1 levels and HD patients with low perilipin-1 levels. Regarding the lipid profile, only HDL-C differed between HD patients with high perilipin-1 levels and HD patients with low perilipin-1 levels, and it was higher in the first subgroup. Perilipin-1 was significantly higher in HD patients without CHD. Perilipin-1 is detectable in the serum of HD patients and it is associated with increased HDL-C and decreased incidence of CHD.

Cardiovascular disease, and mainly coronary heart disease (CHD), is the leading cause of death in hemodialysis (HD) patients. Non-traditional risk factors may play an important role in this population. Arginase is known to contribute directly to atherosclerosis progression and to counteract the beneficial effects of nitric oxide. HD could be considered as an inflammatory condition. Inflammation contributes to atherosclerosis progression and influences both arginase and nitric oxide synthase expression. In the present study, serum arginase type I was evaluated as a marker of CHD in HD patients. The markers of inflammation interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were also assessed. Sixty-eight HD patients and 24 healthy volunteers were enrolled into the study. Twenty HD patients suffered from CHD confirmed with coronary angiography, while the remaining 48 HD patients were asymptomatic. Serum arginase type I, IL-6 and TNF-α were measured with ELISA. During 24 months follow-up, none of the asymptomatic subjects developed symptoms of CHD. IL-6 and TNF-α levels were increased in HD patients, but did not differ between HD patients with or without CHD. On the contrary, arginase levels did not differ between healthy subjects and HD patients, but were twice higher in HD patients with CHD than in HD patients without CHD (22.41 ± 15.47 ng/ml vs. 10.16 ± 8.13 ng/ml). Arginase type I may contribute to the pathogenesis of CHD in HD patients and its serum levels could be used as a marker of CHD in this population.

Vitamin D and its analogues proved to exert immunomodulatory effects. Paricalcitol is a vitamin D analogue that is safe. It has been used for years in the treatment of secondary hyperparathyroidism in hemodialysis patients and, importantly, it is less calcemic than vitamin D. In this study the immunomodulatory/anti-inflammatory properties of paricalcitol were evaluated in vitro.Ten healthy volunteers enrolled into the study. Peripheral blood mononuclear cells (PBMC) at a concentration of 10(6) cells per well were cultured for 48 h in the presence or not of lipopolysaccharide (LPS) (100 ng/ml) and in the presence or not of paricalcitol (10(-8) M). TNF-alpha and IL-8 were measured in the supernatants by ELISA.Basal TNF-alpha concentration (50.3 +/- 22 pg/ml) was reduced by paricalcitol (44.1 +/- 23.2 pg/ml). LPS increased TNF-alpha concentration (150.0 +/- 81.7 pg/ml), but paricalcitol reduced it (121.1 +/- 69.0 pg/ml). The effect of paricalcitol on IL-8 production was more profound. Basal IL-8 concentration (1926 +/- 455 pg/ml) was reduced by paricalcitol (1273 +/- 472 pg/ml). LPS increased IL-8 concentration (2361 +/- 385 pg/ml), but paricalcitol returned it to its basal level (1849 +/- 417 pg/ml).The in vitro inhibition of transforming growth factor alpha and interleukin 8 by paricalcitol confirms the immunomodulatory properties of this vitamin D analogue.

Anemia is a common complication in hemodialysis (HD) patients. Despite the great success of recombinant human erythropoietin in clinical practice, resistance to this therapy is common. Additionally, nephrologists frequently witness a rapid and significant drop in their patients' hematocrit during the course of various acute events that regularly take place in this sensitive population. Hepcidin, a recently identified peptide, may mediate this development in many instances. Hepcidin production is regulated by hypoxia/anemia, iron status, and importantly, inflammation. This peptide can block iron absorption by the duodenum, iron release from both the liver (the main iron storage pool) and, more significantly, the macrophages interrupting iron recycling between senescent red cells and the reticuloendothelial system. The decreased availability of iron for erythropoiesis leads to the anemia of chronic disease or, in HD patients, aggravate an already existing anemia HD is now widely considered an inflammatory state probably accounting for the increased serum hepcidin levels that have been associated with it. The physiology of hepcidin and its possible contribution to the pathogenesis of anemia in HD patients are the subject of this review.

Oxidative stress is increased in hemodialysis (HD) patients and contributes to the increased morbidity and mortality in this population. Vitamin E is an antioxidant agent. In the present study the effect of prolonged oral alpha-tocopherol administration on the antioxidant defense system was evaluated. The antioxidant factors plasma total antioxidant status (TAS), red blood cell superoxide dismutase (SOD) activity and glutathione peroxidase (GPX) activity were evaluated with spectrometry in 27 HD patients. Measurements were performed before and after oral administration of alpha-tocopherol at a dose of 500 mg/d for a one-year period. Twenty HD patients received a placebo and 22 healthy volunteers served as controls. TAS was increased in HD patients. No difference was detected in SOD and GPX activity between HD patients and healthy volunteers. Tocopherol administration induced a significant decrease in TAS and SOD activity. Levels of GPX activity remained unaffected. All the evaluated factors remained stable in the HD patients receiving a placebo. Prolonged oral alpha-tocopherol administration in HD patients induces a decrease in some components of the antioxidant defense system, raising the possibility for a pro-oxidative role of vitamin E. Vitamin E is an antioxidant agent, but it is also known to have pro-oxidant action under special conditions that can be encountered in HD patients.

Renal osteodystrophy is very common in hemodialysis (HD) patients. HD is a chronic inflammatory state. Studies in other pathological entities have shown an impact of chronic inflammation on bone metabolism. In the present study, the impact of chronic inflammation on bone turnover in HD patients was evaluated.Thirty-three anuric HD patients free of other pathological conditions or medications that affect immune system or bone metabolism and 30 healthy volunteers enrolled into the study. Intact parathyroid hormone (iPTH), the markers of inflammation IL-6 and CRP, as well as the markers of bone turnover osteocalcin (OCN) and beta-isomerized C-terminal cross-linked peptide of collagen type I (beta-CTx) were measured in the serum.All evaluated factors were increased in HD patients. In the HD group, the serum marker of osteoblastic activity OCN was related inversely to patients' age (r = -0.469, p = 0.006), CRP (rho = -0.460, p = 0.007), and IL-6 (r = -0.485, p = 0.004) but positively to iPTH (r = 0.707, p0.001). Similarly, the serum marker of osteoclastic activity beta-CTx was related inversely to patients' age (r = -0.383, p = -0.028), CRP (rho = -0.466, p = 0.006), and IL-6 (r = -0.460, p = 0.007) but positively to iPTH (r = 0.657, p0.001). Multiple linear regression analysis revealed that IL-6 affects bone turnover independently of PTH and to the opposite direction.Chronic inflammation has a negative impact on bone turnover in HD patients. Certainly, further research and large clinical trials are needed for definite conclusions and for clarifying the exact molecular mechanisms implicated in the interaction between the immune system and bone metabolism in HD patients.

Background: Clinical and experimental data indicate a deficient immune response in hemodialysis (HD) patients. ζ-Chain phosphorylation is an early and central event in the process that follows antigen recognition by the T cell antigen receptor (TCR). T cell ζ-chain is downregulated in many chronic inflammatory states, such as cancer, autoimmune disease and chronic infection. HD is also characterized as a chronic inflammatory state. The aim of the present study was to evaluate T cell ζ-chain expression in HD patients. Patients and Methods: Thirty-three stable HD patients and 30 healthy volunteers were enrolled into the study. T cell count, the percentage of ζ-chain-positive T cells, as well as T cell ζ-chain mean fluorescence intensity (MFI) were evaluated with flow cytometry. The inflammatory markers C-reactive protein, interleukin-6 and tumor necrosis factor-α were measured in the serum by means of ELISA. Results: All the evaluated markers of inflammation were increased in HD patients. In these patients, T cell ζ-chain MFI was decreased. CD3-Ε MFI did not differ between the two groups indicating that among the TCR complex constituents, ζ-chain is selectively downregulated. Conclusions: HD is a state of chronic inflammation. Like in other pathological chronic inflammatory conditions, T cell ζ-chain is downregulated in HD patients. Since ζ-chain plays a key role in the transduction of the signal that follows antigen recognition by the TCR, its downregulation could be responsible for the deficient cellular immune response observed in HD patients.

Acquired immunity disturbances in hemodialysis (HD) patients are many and diverse. They are caused by uremia per se, the HD procedure, chronic renal failure complications, and therapeutic interventions for their treatment. Current data suggest that acquired immunity disturbances in HD patients concern mainly the T-lymphocyte and the antigen-presenting cell (APC). The T-lymphocyte-dependent immune response is deficient, predisposing to infections and inadequate response to vaccinations. In addition, APCs are preactivated, which seems to be responsible for the malnutrition-inflammation-atherosclerosis syndrome, and also affects T-lymphocyte function. At the molecular level it is assumed that the interaction between the APC and the T-lymphocyte is impaired. This disturbance is likely to concern the signal that results from the interaction between the major histocompatibility complex:peptide complex on APC surfaces and T-cell receptors on T-lymphocyte surfaces, or the signal that results from the interaction among the co-receptors of these two cells. The aim of the present review was to collect and classify the available clinical and experimental data in this area. Although many pieces are still missing from the puzzle, a better understanding of the responsible molecular mechanisms, will potentially lead to increased survival and a better quality of life in HD patients.

Cardiovascular disease is the leading cause of death in hemodialysis (HD) patients. Coronary artery calcification (CAC) is considered a marker of atherosclerosis and coronary artery disease (CAD). The CAC progression and factors that influence it were evaluated during a 30-month period.Forty HD patients without a history of CAD were enrolled into the study. CAC score was assessed with conventional CT repeated every six months. The circulating factors of phosphorous, calcium, calcium-phosphorous product, intact parathyroid hormone, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, lipoprotein-alpha, albumin, high sensitivity C-reactive protein, and fibrinogen were measured monthly. Hypertension and calcium intake during the study period were taken into account as well.At baseline, CAC score was correlated with age and duration of HD therapy. From all evaluated factors, CAC initiation was influenced only by older age and C-reactive protein. CAC, when it was started, was aggravated continuously and was influenced only by elevated serum phosphorous and calcium-phosphorous product. Hypertension, lipid profile, and calcium intake did not affect CAC initiation or progression.Once CAC progression starts, it is an uninterrupted process. The roles of inflammation and abnormal calcium-phosphorous metabolism in CAC differ. Inflammation is the major factor that contributes in CAC initiation. Elevated serum phosphorous and calcium-phosphorous product accelerates CAC progression.

Ischemic acute kidney injury is characterized by apoptosis of tubular epithelial cells. Proteasome plays a key role in cellular processes such as proliferation, apoptosis and inflammation. The results of animal studies about the effect of proteasome inhibitors on the course of ischemic acute kidney injury are controversial. Primary human renal tubular epithelial cells were cultured with or without the hypoxia mimetic CoCl2 and with or without the proteasome inhibitor CEP-18770 and/or the immunoproteasome inhibitor ONX-0914. The level of the proteasome subunit β5, the immunoproteasome subunits LMP7 and LMP2, the function of these proteolytic machines, HIF-1α and its transcriptional target lactate dehydrogenase-A, p53 and its transcriptional targets TP53-inducible glycolysis and apoptosis regulator and p21, and finally of activated cleaved caspase-3 were assessed by means of western blotting. CoCl2 decreased the expression of β5, LMP7 and LMP2, as well as the activity of proteasome and immunoproteasome. It increased HIF-1α and its function, along with p53 and its function and induced apoptosis. CEP-18770 and ONX-0914 induced the above alterations toward the same directions as CoCl2 does. In CoCl2-treated cells, pretreatment with CEP-18770 and/or ONX-0914 potentiates the changes induced by CoCl2 alone. CoCl2, CEP-18770 and ONX-0914 induce apoptosis in human renal tubular epithelial cells. Importantly, proteasome or immunoproteasome inhibitors are rather toxic than beneficial in human renal tubular epithelial cells treated with the hypoxia mimetic CoCl2.

Introduction: Prohepcidin is the precursor of hepcidin, a liver-derived peptide involved in iron metabolism by blocking its intestinal absorption and its release by the reticuloendothelial system. Iron overload and inflammation increase hepcidin expression, whereas anemia and hypoxia suppress it. In the present study prohepcidin levels were determined in the serum of hemodialysis (HD) patients and its correlations with iron metabolism markers, C-reactive protein (CRP) and hematocrit (Hct) were assessed. Patients and Methods: Forty-sixHD patients and 22 healthy volunteers were enrolled in the study. Hct, serum prohepcidin, CRP, iron, ferritin, transferrin saturation and transferrin receptors were measured. The weekly erythropoietin dose, last-month intravenous iron dose and the patients’ demographics were recorded. Results: In comparison to the healthy volunteers, the HD patients had higher serum ferritin, transferrin receptors and CRP, lower serum iron and similar transferrin saturation and prohepcidin levels. In the patient group prohepcidin levels were negatively correlated with Hct but not with any other of the examined parameters. Multiple linear regression analysis considering age, inflammation, iron adequacy, erythropoietin dose and prohepcidin levels revealed that prohepcidin was the predominant determinant of Hct. Conclusions: Taking into account the low Hct levels in the HD patients of our study, it seems plausible that the prohepcidin levels assessed in this group are inappropriately high. These functionally high prohepcidin levels may be associated with the factors that inhibit erythropoiesis in HD patients. On the other hand, the absence of other expected correlations indicates that further studies are needed in order to definitely clarify this aspect.

The risk for tuberculosis (TB) reactivation in hemodialysis (HD) patients is increased, and screening for latent TB is recommended. The tuberculin skin test (TST) is inaccurate because of the high incidence of anergy in skin testing in HD patients and its inability to differentiate latent from eradicated TB infection. In this study, use of serum antilipoarabinomannan (anti-LAM) antibody detection for the diagnosis of latent TB in a dialysis population was evaluated.Seventy-four HD patients never treated for TB composed the first group. Forty-eight healthy volunteers never treated for TB served as controls. Twenty-one TST-positive renal transplant candidates on dialysis therapy who had completed preventive anti-TB treatment formed a third group. The TST (using the Mantoux method) and anti-LAM test (using an immunochromatographic assay) were performed in all subjects participating in the study.In the first group, a strong association was detected between results of the TST and anti-LAM test (P0.0001, chi-square test). A similar association was found in the second group. In the group of HD patients treated for TB, a positive TST result and negative anti-LAM test result was a constant finding.The association between the TST and anti-LAM test in HD patients suggests that the anti-LAM test could be a useful tool for diagnosing latent TB. The absence of anti-LAM antibodies in anti-TB-treated HD patients suggests that immune response to lipoarabinomannan lacks long-lasting memory. A negative anti-LAM test result might reflect the absence of latent TB, even in patients with a positive TST result.

Background. Anticardiolipin antibodies (ACA) have been related to an increased incidence of thrombotic episodes and atherosclerosis progression. ACA levels are elevated in hemodialysis (HD) patients. Atheroembolic episodes are the major cause of morbidity and mortality in this population. Oxidative stress has been implicated in ACA formation, and it is increased in HD patients. Vitamin E is a known antioxidant factor. In this study, the effects of prolonged oral α-tocopherol administration on ACA levels were evaluated. Methods. Serum anticardiolipin IgG antibodies (ACA-IgG) and IgM antibodies (ACA-IgM) levels were evaluated in 27 stable HD patients and 22 healthy volunteers. Then measurements were performed in the patients' group after oral administration of α-tocopherol at a dose of 500 mg/d for a 1-year period. ACA levels were assessed by solid-phase enzyme immunoassay. Results. ACA-IgG levels were higher in HD patients compared with control (13.3 ± 6.64 GPL/mL vs. 7.727 ± 18.305 GPL/mL, p < .001). This...

We evaluated the value of coronary artery calcification (CAC) score in coronary artery disease (CAD) detection in asymptomatic hemodialysis (HD) patients by evaluating the association among CAC score, exercise electrocardiography (EECG), and Thallium-201 dipyridamole scintigraphy. Correlation between aortic pulse wave velocity (PWV) and CAC score was also evaluated.CAC score was assessed with conventional computed tomography in 40 patients. Thirty patients completed EECG and 25; those with a positive CAC score and/or a positive EECG performed Thallium dipyridamole scintigraphy. Carotid-femoral PWV was assessed in all patients.There was no association among CAC score and EECG or Thallium dipyridamole scintigraphy. In contrast, CAC score was correlated with aortic PWV.The previous results question the role of CAC score in the detection of CAD in asymptomatic HD patients. The correlation between CAC score and aortic PWV raises the possibility that CAC score represents more an indicator of coronary artery medial wall calcification than a marker of CAD.

Sir, Both clinical and experimental evidence, like impaired response to vaccination with T-celldependent antigens [1] or T-cell proliferation after stimulation with staphylococcal enterotoxin B (SEB) [2], suggest a defective T-cell immune response in hemodialysis patients. The contribution of parathyroid hormone (PTH) levels in this situation is not fully clarified. Some investigators showed that in patients with high serum intact PTH (iPTH), T-cell proliferation after stimulation with the T-cell receptor (TCR) dependent phytohemagglutinin (PHA) is increased in comparison with T-cells derived from patients with low iPTH levels [3]. Others proposed that chronic T-cell exposure to PTH could be responsible for altered T-cell proliferation after stimulation with mitogens [4] due to interference with cellular calcium kinetics. In order to evaluate the role of serum PTH level on T-cell reactivity in hemodialysis patients we used SEB as stimulator, since it provokes Tcell stimulation not only in a TCR-dependent, but also in an antigen presenting cell-dependent manner by cross-linking the major histocompatibility complex class II (MHCII) molecules with the TCR [5]. Consequently, SEB imitates conventional peptide antigens better than PHA and other mitogens. Moreover, in contrast with conventional peptide antigens, SEB stimulates a large proportion of T-cells [6, 7], a crucial feature for obtaining reliable results from the usual cell cultures. A total of 25 hemodialysis patients were enrolled into the study. Besides end-stage renal disease, none of them suffered by conditions like active infection, cancer, autoimmune disease or diabetes mellitus, or received medications like corticosteroids, non-steroid antinflammatory drugs, cytotoxic drugs, statins, vitamin D or calcium channel blockers that are known to alter the immune response. In total, 20 age and sex matched healthy individuals served as a control group. An informed consent was obtained from all subjects enrolled into the study. In hemodialysis patients, blood samples were drawn just before the onset of the second dialysis T. Eleftheriadis (&) AE V. Liakopoulos AE G. Antoniadi AE A. Poultsidi AE I. Stefanidis Department of Nephrology, University Hospital of Larissa, Papakiriazi 22, PC 41222 Larissa, Greece e-mail: elefthe@otenet.gr

Purpose Experimental data confirmed that erythropoietin (EPO) administration alters the course of various pathological situations such as heart failure and tumor growth by inducing vascular endothelial growth factor-A (VEGF-A) expression. The effect of EPO dose on plasma VEGF-A level in hemodialysis (HD) patients was evaluated. The effect of EPO dose on plasma angiogenin level in HD patients was also evaluated, since angiogenin is necessary for angiogenesis induced by VEGF-A. Methods Thirty two HD patients (10 diabetics) enrolled into the study. Patients were iron replete and did not suffer from infections, autoimmune diseases or malignancies. Plasma VEGF-A and angiogenin, as well as serum interleukin-6 and tumor necrosis factor-α were measured by means of ELISA. Results Weekly EPO dose per kg of dry body weight was positively related to both VEGF-A and angiogenin, whereas no relation was detected among VEGF-A or angiogenin and hemoglobin, inflammation or presence of diabetes mellitus. These relations among EPO dose and VEGF-A or angiogenin remained after adjustment for hemoglobin concentration or inflammation or presence of diabetes mellitus. Conclusions EPO dose may affect plasma VEGF-A and angiogenin concentrations in HD patients.

Disturbed iron homeostasis contributes to resistance to recombinant human erythropoietin (rHuEpo) in hemodialysis (HD) patients. Increased hepcidin, which downregulates the iron exporter ferroportin, has been incriminated. However, other factors also control ferroportin expression in mononuclear phagocyte system. Ferroportin in monocytes, as well as serum hepcidin, interleukin-6 (IL-6) and common markers of iron status were measured and correlations with rHuEpo resistance index (ERI) were evaluated. After a 4-week washout period from iron treatment, 34 HD patients and 20 healthy volunteers enrolled in the study. Ferroportin was assessed by means of western blotting, whereas hepcidin and IL-6 with enzyme-linked immunosorbent assay. Hemoglobin, serum iron, ferritin and transferrin saturation (TSAT) were also measured. Ferroportin in monocytes of HD patients was decreased. Serum hepcidin and IL-6 were increased, whereas serum iron and TSAT were decreased. ERI was negatively correlated with ferroportin and all the markers of iron adequacy, but not with hepcidin. Decreased ferroportin in monocytes of HD patients accompanies increased hepcidin, inflammation, decreased iron availability and is correlated with resistance to rHuEpo treatment.

Inflammation is common in hemodialysis (HD) patients. Mitochondrial damage-associated molecular patterns (DAMPs) are released during cell necrosis or apoptosis and induce inflammation. Cell apoptosis is increased in HD patients. The mitochondrial protein cytochrome c, as a marker of released mitochondrial DAMPs, and interleukin-6 (IL-6), as a marker of inflammation, were evaluated in HD patients. Thirty-four HD patients and 20 controls were enrolled in the study. Serum cytochrome c and IL-6 were measured by means of enzyme-linked immunosorbent assay. Compared to controls, cytochrome c was markedly increased in HD patients (1392.88 ± 905.24 pg/mL vs. 212.95 ± 91.71 pg/mL). IL-6 was also significantly increased in HD patients (50.32 ± 35.89 pg/mL vs. 14.27 ± 6.83 pg/mL). In HD patients serum IL-6 was positively related to serum cytochrome c (r = 0.458). Both circulating cytochrome c and IL-6 are markedly increased in HD patients. Cytochrome c is positively related to IL-6.

Calciphylaxis or calcific uremic arteriolopathy is a relatively uncommon condition with poor prognosis. Although it is predominantly observed in patients with end stage renal disease, a few cases of patients without kidney failure have been reported. Calciphylaxis is characterized by calcification of the arteriolar intima media and eventually by vascular thrombosis, tissue ischemia and painful skin necrosis. Septicemia is the main cause of death. According to published literature concerning the pathology of calciphylaxis, prevention and treatment are principally based on interventions in calcium and phosphorus metabolism. Although novel therapies have emerged, due to the rarity of this condition, there is no sufficient data in favor of a certain treatment.

Acquired immunity is impaired in hemodialysis (HD) patients, and decreased T cell number may contribute. Receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG) are expressed in cells of the immune system and affect T cell development, homeostasis and proliferation. Serum levels of RANKL and OPG and their relation to blood T cell number were evaluated in HD patients. Thirty-four HD patients and 20 healthy controls participated in the study. Serum RANKL and OPG were measured by ELISA and T cell number was assessed by flow cytometry. Median RANKL concentration did not differ between HD patients and healthy volunteers (300.00 pmol/L; range, 3,340.00 vs. 330.00 pmol/L; range, 440.00 pmol/L; p = 0.528). Median OPG was markedly higher in HD patients than in healthy volunteers (13.12 ± 4.71 vs. 4.71 ± 0.93 pmol/L, p

Coronary heart disease (CHD) is the leading cause of death in hemodialysis (HD) patients. Inflammation contributes to the pathogenesis of atherosclerosis in this population. Indoleamine 2,3-dioxygenase (IDO), an enzyme with immunomodulatory properties, was evaluated in HD patients with or without CHD.Of the total of 66 HD patients, 22 of them with CHD were confirmed by coronary angiography and 24 healthy volunteers were enrolled in the study. Plasma IDO was assessed by means of enzyme-linked immunosorbent assay. Serum interleukin-6 (IL-6) and C-reactive protein (CRP) were also measured.Compared with healthy volunteers, plasma IDO concentration was markedly increased in HD patients (median 8.04 ng/mL vs. 48.9 ng/mL). Serum IL-6 and CRP were also significantly increased in HD patients. Compared with HD patients without CHD, plasma IDO concentration was significantly increased in HD patients with CHD (median 38.6 ng/mL vs. 74.5 ng/mL). Neither IL-6 nor CRP differed between the last two groups. IDO was negatively correlated with IL-6 and CRP.IDO concentration is increased in HD patients and is increased further in HD patients with CHD. It remains to be elucidated if increased IDO plays a direct role in the pathogenesis of atherosclerosis or if it affects atherosclerosis indirectly by curtailing chronic inflammation or both.

Background Acquired immunity is impaired in hemodialysis (HD) patients. Indoleamine 2,3-dioxygenase (IDO) is inducible by inflammation and through tryptophan depletion and generation of kynurenine pathway products suppresses adaptive immune response. In the present study plasma IDO levels were assessed in HD patients. Its effect on response to HBV vaccination program was evaluated. Patients and methods Sixty-six HD patients and twenty-four healthy volunteers enrolled into the study. All the HD patients were initially vaccinated with four double doses of recombinant HBV vaccine. All doses were repeated in patients who had not responded after complete first vaccination series. Only one boost dose was being administered in patients with initial adequate antibody levels against the HBV surface antigen (anti-HBs > 10 IU/L) who then presented with reduced anti-HBs levels. IDO, CRP, IL-6 and TNF-α were measured by means of ELISA. Results Compared to healthy volunteers, IDO levels were twice higher in HD patients. CRP, IL-6 and TNF-α were also much higher in HD patients. IDO levels were almost twice higher in HD patients with inadequate response to HBV vaccination, than in those with adequate immune response. CRP, IL-6 and TNF-α did not differ between the two patients’ groups. IDO was negatively correlated with all markers of inflammation in HD patients. Conclusion IDO is increased in HD patients. It is possible that after its initial upregulation due to chronic inflammation, IDO curtails its own provoking agent, i.e., inflammation. Increased IDO suppresses adaptive immunity in HD patients, as it is assessed by the response to HBV vaccination.

Transferrin saturation (TSAT) is a reliable marker of iron status. According to National Kidney Foundation – Dialysis Outcomes Quality Initiative (NKF-DOQI) guidelines, a TSAT < 20% indicates iron ...

SUMMARY Aim: Clinical and experimental data indicate a deficient immune response in haemodialysis (HD) patients. Natural killer-like (NKL) T cells express on their surface both the T-cell antigen receptor (TCR) and a diverse set of NK-cell receptors (NKR) and share properties of both T cells and NK cells. ζ-Chain phosphorylation is an early event that follows TCR activation or some NKR activation. The ζ-chain of both T cell and NK cells is downregulated in many chronic inflammatory states, HD included. In the present study, NKL T-cell percentage and ζ-chain expression in HD patients were evaluated. Methods: Thirty-three stable HD patients and 30 healthy volunteers were enrolled into the study. NKL T-cell percentage and NKL T-cell ζ-chain mean fluorescence intensity (MFI) were evaluated with flow cytometry. The inflammatory markers C-reactive protein, interleukin-6 and tumour necrosis factor-α were measured in the serum by means of enzyme-linked immunosorbent assay. Results: All the evaluated markers of inflammation were increased in HD patients. In these patients, NKL T-cell percentage (1.71 ± 1.69% vs 3.94 ± 3.86%) and ζ-chain MFI (3.66 ± 2.79 vs 7.03 ± 7.91) were decreased. Conclusions: NKL T-cell percentage and ζ-chain expression is decreased in HD patients. Taking into consideration the continuously increasing age of the HD patients and that normally NKL T-cell numbers increase with age counteracting the impaired T-cell and NK-cell function accompanying advancing age, the above NKL T-cell disturbances could contribute to the impaired immune response in this population. Measures towards alleviating chronic inflammation could partially restore NKL T-cell impairment.

Vascular access thrombosis represents a serious and unfortunately common problem in hemodialysis patients. Usually, but not always, this complication can be attributed to low access blood flow. However, there are some patients who experience thrombosis despite a well functioning vascular access. We describe the case of a 31-year-old Caucasian male, who was hemodialyzed via an arteriovenous fistula for two years due to Alport's syndrome. During this time period he had two episodes of vascular access thrombosis that destroyed two arteriovenous fistulas. Both fistulas were functioning well and the thrombosis events took place in days between the hemodialysis sessions. Thrombophilia was suspected and the relative investigation revealed high levels of factor VIII procoagulant, which is frequent in hemodialysis patients, and resistance to activated protein C. Polymerase chain reaction detected that the patient was heterozygous for factor V Leiden, which is quite common in general population. Thereafter, a new arteriovenous fistula was formed and the patient started oral anticoagulation therapy with warfarin. Now, three years after the last arteriovenous fistula formation, the patient is hemodialyzed without vascular access problems. In conclusion, evaluation of the coagulation cascade in hemodialysis patients with recurrent vascular access thrombosis is necessary.

Aortic stiffness is increased in patients undergoing hemodialysis (HD), and it is associated with an increased cardiovascular mortality. Among others, aortic stiffness has been correlated with serum markers of inflammation, indicating a role of the immune system in its pathogenesis. The aim of this study was to evaluate the impact of antigen-presenting cell-dependent T-lymphocyte reactivity on aortic stiffness in HD patients.Twenty patients were enrolled in the study. Exclusion criteria were medications or conditions, other than HD, that are known to influence the immune response or aortic stiffness. Antigen-presenting cell-dependent T-lymphocyte reactivity was assessed by cell proliferation of peripheral blood mononuclear cells cultured with or without stimulation with Staphylococcal enterotoxin B (SEB). Cell proliferation was estimated by immunoenzymatic measurement of bromodeoxyuridine uptake. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (PWV) measurement.Linear regression analysis revealed a strong positive relation between carotid-femoral PWV and antigen-presenting cell-dependent T-lymphocyte reactivity, when SEB at concentrations of 1 ng/mL or 10 ng/mL was used as stimulant.The present study confirms that aortic stiffness in HD patients is positively related to antigen-presenting cell-dependent T-lymphocyte reactivity. The greater the ability of the immune system to react to a monocyte-dependent stimulant and, consequently, to provoke an inflammatory response, the greater the stiffness of the aorta. This is in agreement with the observation that aortic stiffness in HD patients is positively related to various serum inflammation markers.

Platelet dysfunction is a well-established disturbance in haemodialysis (HD) patients. Propyl gallate is a synthetic platelet activator with the property to stimulate platelet aggregation. The aim of the present study was to evaluate the influence of a single haemodialysis session on propyl gallate-induced platelet aggregation.Thirty-nine HD patients were enrolled in the study and 20 healthy volunteers were studied as controls. Cellulose diacetate (CD) dialysers were used in 20 patients and polysulphone dialysers in 19. HD was performed via an A-V fistula in 27 patients and via an i.v. catheter in 12. Erythropoietin was administered in 37 patients (epoietin-alpha in 24 and darbepoietin in 13). Thirty-four were receiving the low-molecular-weight heparin tinzaparin. Propyl gallate slide aggregometry was used for evaluating platelet aggregation.In HD patients, platelet aggregation was impaired before as well as after the HD session. No effect of the HD procedure, type of vascular access, adequacy of HD or type of erythropoietin on the propyl gallate-induced platelet aggregation was detected. Platelet aggregation was higher when CD dialyser was used. A negative correlation between the time needed for platelet aggregation to occur and tinzaparin dose was found.Propyl gallate-induced platelet aggregation in HD patients is impaired. Platelet aggregation was higher in patients dialysed with CD membrane than in those dialysed with polysulphone membrane. The higher the dose of tinzaparin, the higher the platelet aggregation. The clinical significance of the above results needs further evaluation.

Hepatitis B virus (HBV) is a major global health problem. Despite the success of the general measures against blood transmitted infections in hemodialysis (HD) units, the prevalence of HBV infection among the HD patients is still high. Thus vaccination against HBV is indicating in this population. However, compared with the general population the seroprotection achieved in HD patients remains relatively low, at about 70%. In this review patient, HD procedure and vaccine-associated factors that affect the efficacy of HBV vaccination are analyzed. Also alternative routes of HBV vaccine administration as well as new and more immunogenic vaccine formulations are discussed. However, besides scientific progress, vigilance of HD physicians and staff regarding the general measures against the transmission of blood borne infections and the vaccination against HBV is also required for reducing the prevalence of this viral infection.

HD patients, or its accumulation due to renal failure, logically inhibits the iron release by macrophages, limiting its availability for erythropoiesis [4] . In accordance with the negative correlation between prohepcidin and hematocrit are the findings of Dallalio et al. [5] , who in a recent in vitro study detected that hepcidin can contribute to anemia not only through an effect on iron metabolism, but also through inhibition of erythroid progenitor proliferation and survival. What then is the explanation for the discrepancy among the three studies regarding the correlation of prohepcidin with hematocrit? Why was no relation detected between prohepcidin and markers of iron metabolism? The same kit was used for accessing prohepcidin levels in HD patients and its mean value was similar in all three studies (200–250 ng/ml). Is prohepcidin measurement useless for understanding better the anemia in HD and consequently as a marker of erythropoietin resistance in the future? In our opinion, at the present time we are not able to answer the above question due to the complex interrelations among the various factors involved in the regulation of hepcidin expression. For example, serum iron and transferrin saturation are markers of iron metabolism but are also influenced by inflammation, which decreases their levels. Ferritin is a marker of iron stores and an acute phase reactant. Inflammation increases CRP as well as hepSir, We read the article by Hsu et al. [1] that was recently published in your journal. The authors evaluated the effect of plasma prohepcidin on iron metabolism and erythropoiesis – in relation to inflammation as well – in hemodialysis (HD) patients. Their results were unexpected, since they detected a positive correlation between prohepcidin and hematocrit, no correlation with iron metabolism markers and CRP, and a negative correlation with IL-6. These results are very disappointing regarding the role of hepcidin in anemia of chronic disease and the resistance in recombinant erythropoietin therapy in HD patients. Our team performed a similar study, which is going to be published in a future issue of Acta Haematologica [2] . It has already been presented in abstrcat from in the XLIII ERA–EDTA Congress. We also failed to detect a correlation of serum prohepcidin with various serum iron metabolism markers and CRP. However, multiple linear regression analysis considering age, inflammation, iron adequacy, erythropoietin dose and prohepcidin levels revealed that prohepcidin was the major determinant of hematocrit, but in a negative way. Malyszco et al. [3] also showed, in a univariate analysis, that prohepcidin correlated negatively with hematocrit. The negative correlation of prohepcidin with hematocrit seems reasonable, since the prohepcidin hyperproduction due to microinflammation usually encountered in Published online: November 16, 2006

actions. 2 We assessed acylated ghrelin (A-Ghr) in 20 healthy volunteers (57.00±8.62 years) and 68 HD patients (61.24±12.51 years, 22 diabetics). Samples were drawn before 2 years, and at the end of this period 22 HD patients suffered from coronary heart disease (CHD). Plasma A-Ghr was measured using enzyme-linked immunosorbent assay (SPI Bio, Montigny, France). White blood cell count (WBC), C-reactive protein (CRP), and albumin were also assessed. A-Ghr did not differ between HD patients and healthy volunteers (106.40±27.53 versus 120.50±45.04 pg/ml, P ¼ 0.424, Mann–Whitney unpaired test). A-Ghr was lower in HD patients suffering from CHD (95.00±22.04 versus 111.85±28.42 pg/ml, P ¼ 0.023) and was positively correlated with WBC (Spearman’s r ¼ 0.426, Po0.001), CRP (r ¼ 0.261, P ¼ 0.023), that is, with inflammation, and age (r ¼ 0.323, P ¼ 0.007). A-Ghr was negatively correlated with the marker of nutrition albumin (r ¼� 0.368, P ¼ 0.002). Thus, similar to total ghrelin, A-Ghr is also lower in HD patients with cardiovascular disease. This could be simply an epiphenomenon, as in the case of cachexia that accompanies inflammation, A-Ghr increases to counteract weight-loss mechanisms, and it is well known that inflammation also induces atherosclerosis. 2,3 Alternatively, higher A-Ghr could offer protection from atherosclerosis through its direct action on the endothelium or indirectly by attenuating inflammation. 2,4 The second case, if proved true, is promising for pharmaceutical intervention in the near future.

It has been known for years that the ratio of receptor activator of nuclear factor-κB ligand (RANKL) relative to its decoy receptor, osteoprotegerin (OPG), controls osteoclastogenesis. Under normal conditions the main source of RANKL and OPG is the osteoblast. Osteoblasts express on their surface RANKL that induces the formation of osteclasts from their precursors as well as their survival and activation. OPG is also produced and then secreted by the osteblasts, but it inhibits osteoclast formation by binding to RANKL and preventing binding to its receptor RANK on the surface of the osteoclasts’ precursors1. However, a recent study suggests that both B and T lymphocytes also play a significant role in basal bone turnover, since T cells help B cells to produce 65% of total OPG in bone marrow in mice2. In inflammatory diseases the participation of activated lymphocytes in pathological bone erosion is established3. Vitamin D promotes … Address reprint requests to Dr. T. Eleftheriadis, Department of Nephrology, General Hospital of Serres, 3rd km Serres-Drama, 62100 Serres, Greece. E-mail: teleftheriadis{at}yahoo.com