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

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

Could neutrophil-gelatinase-associated lipocalin and cystatin C predict the development of contrast-induced nephropathy after percutaneous coronary interventions in patients with stable angina and normal serum creatinine values?

The value of neutrophil-gelatinase-associated lipocalin (NGAL) was highlighted as a novel biomarker for the detection of acute renal failure. We tested the hypothesis whether NGAL could represent an early biomarker of contrast-induced nephropathy (CIN) in 100 patients with normal serum creatinine values undergoing percutaneous coronary interventions (PCI). In addition, we assessed serum and urinary NGAL in relation to cystatin C, estimated glomerular filtration rate, and serum and urinary creatinine in these patients. We measured urinary and serum NGAL values before and 2, 4, 8, 24, and 48 h after the PCI. We found a significant rise in serum NGAL levels 2, 4, and 8 h after the PCI and in urinary NGAL values 4, 8, and 24 h after a PCI procedure. Cystatin C rose significantly 24 h after the procedure. The prevalence of CIN was 11%. The NGAL levels were significantly higher 2 h after the PCI (serum NGAL) or 4 h after the PCI (urinary NGAL), whereas the cystatin C values were higher only 8 and 24 h after a PCI procedure in patients with CIN. In multivariate analysis, only serum creatinine was a predictor of serum NGAL before a PCI. NGAL may represent a sensitive early biomarker of renal impairment after PCI. Serum creatinine level, the presence of diabetes, and the duration of the PCI may affect serum NGAL values and kidney function following a PCI procedure.

Hepcidin, an acute-phase protein and a marker of inflammation in kidney transplant recipients with and without coronary artery disease

BACKGROUND

In kidney transplant recipients, endothelial dysfunction and atherosclerosis are almost universal, as are cardiovascular complications. Inflammatory markers have been shown to play a role in the pathogenesis and progression of atherosclerosis, regarded as a chronic inflammatory condition. Iron metabolism is disturbed in chronic inflammatory diseases such as atherosclerosis. Hepcidin, the liver-expressed antimicrobial peptide, LEAP-1, is an acute-phase reactant produced in the liver that displays intrinsic antimicrobial activity. Cross-sectional study was performed to assess possible relations between hepcidin and inflammatory markers in kidney transplant recipients with versus without coronary artery disease (CAD).

METHODS

Iron status, complete blood count, creatinine, albumin, and lipids were estimated using standard laboratory methods. Glomerular filtration rate (GFR) was calculated using the MDRD formula. Hepcidin, high-sensitivity C-reactive protein (CRP), IL-6, TNFalpha, and soluble receptor of transferrin were measured using commercially available kits.

RESULTS

Kidney transplant recipients with CAD were older, and showed higher hepcidin, hsCRP, IL-6, TNFalpha, sTFR, ferritin, and lower cholesterol levels than did patients without CAD. Univariate analysis of values in kidney transplant recipients showed hepcidin to correlate significantly with total protein, ferritin, time after transplantation, creatinine, eGFR (simplified MDRD), cholesterol, neutrophil count, hsCRP, and IL-6. There were tendencies to correlate with TNFalpha. Multiple regression analysis showed that hepcidin was independently related to GFR, cholesterol, and hsCRP.

CONCLUSIONS

Elevated hepcidin values in kidney allograft recipients may be due not only to impaired renal function, but also to a low-grade inflammatory state, as reflected by hepcidin correlations with hsCRP, IL-6, and ferritin.

Serum erythropoietin and angiogenetic factors in human colorectal cancer

AIMS AND BACKGROUND

Erythropoietin, VEGF, VE-cadherin are involved in angiogenesis. Besides that erythropoietin stimulates erythropoiesis and increases haemoglobin and hematocrit levels as well. Moreover, erythropoietin could directly stimulate colorectal cancer cell growth due to the presence of both erythropoietin receptor and erythropoietin production in malignant cells of this neoplasm. Therefore we aimed at measurement and comparison of serum erythropoietin with VEGF, VE-cadherin levels, blood haemoglobin and hematocrit in colorectal cancer patients of different clinicopathological profiles.

METHODS

We applied ELISA kits to evaluate preoperative serum levels of endogenous erythropoietin, VEGF and VE-cadherin in samples from 92 colorectal cancer patients and control group of 16 healthy volunteers.

RESULTS

Endogenous erythropoietin was significantly elevated in preoperative sera in colorectal cancer patients (p = 0.013) compared with healthy volunteers, however, erythropoietin levels were not significantly higher with the advancement of colorectal cancer. There were significantly higher levels of erythropoietin in the group of anaemic men in comparison to men with normal haemoglobin levels (p < 0.0001). VEGF and VE-cadherin did not correlate with erythropoietin. Erythropoietin levels negatively correlated with haemoglobin and hematocrit levels in all cancer patients; particularly in node positive cancers (N+), moderately differentiated tumours (G2) and deeply invading neoplasms (pT3+pT4).

CONCLUSIONS

Erythropoietin levels increase in colorectal cancer but circulating erythropoietin does not associate with progression of the disease. Thus, the use of recombinant erythropoietin seems to be safe. Our results suggest that negative feedback regulation persists between haemoglobin and erythropoietin in colorectal cancer. Production of erythropoietin remains therefore anaemia-associated, hypoxia-dependent and doesn't seem to be autonomic despite abundant expression of erythropoietin by colorectal cancers.

The t(4;8) is mediated by homologous recombination between olfactory receptor gene clusters, but other 4p16 translocations occur at random

The t(4;8)(p16;p23) is the second most common constitutional chromosomal translocation and is caused by an ectopic meiotic recombination between the olfactory receptor gene clusters (ORGC), located on chromosome 4p and 8p. Given that ORGCs are scattered across the genome and make-up about 0.1% of the human genome we reasoned that translocations between 4p16 and other chromosomes might be mediated by ectopic recombination between different ORGC. In 13 patients, we mapped the breakpoints of either a balanced or unbalanced translocation between chromosome 4p16 and different chromosomes. For all four t(4;8) cases, the breakpoints fall within the 4p and 8pter ORGC, confirming that non-allelic homologous recombination (NAHR) between the ORGC is the main mechanism of the t(4;8) formation. For the nine other translocations, the breakpoints on chromosome 4 mapped to different loci, one of them within the ORGC and in two flanking the ORGC. In these three cases, the translocation breakpoint at the reciprocal chromosome did not contain ORGC sequences. We conclude that only the t(4;8) is mediated by NAHR between ORGC.

Possible Relations Between Thyroid Function, Endothelium, and Kidney and Liver Function in Kidney Allograft Recipients

BACKGROUND

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

AIM AND METHODS

This cross-sectional study examined thyroid hormones in relation to markers of endothelial damage and inflammation among 80 kidney allograft recipients and 29 healthy volunteers. Thyroid hormones, markers of endothelial damage (vWF, thrombomodulin, intracellular adhesion molecule [ICAM] vascular adhesion molecule [VCAM], CD146), markers of inflammation (hsCRP), other hemostatic parameters (thrombin-antithrombin complexes [TAT], prothrombin fragments 1 + 2 [F1 + 2], plasmin-antiplasmin complexes, tissue plasminogen activator and its inhibitor, platelet glycoprotein [V-GPV]) as well as P-selectin were measured using commercially available kits.

RESULTS

Total T3 was significantly lower among kidney allograft recipients, whereas markers of endothelial dysfunction and inflammation were significantly elevated over controls. In kidney allograft recipients total T3 was independently related to PAI-1, ICAM, and eGFR, whereas free T3 was independently related to thrombomodulin, aspartate, and alanine aminotransferases, hemoglobin, urea, eGFR, dose of cyclosporine and treatment with mycophenolate mofetil/azathioprine. Total T4 was related to aspartate and alanine aminotransferases, dose of cyclosporine, PAI-1, and ICAM. In multiple regression analysis the only correlates of T3 were PAI-1 and ICAM, whereas the only correlates of free T3 were thrombomodulin, aspartate aminotransferase, eGFR, and cyclosporine dose. In healthy volunteers GPV was related only to TSH.

CONCLUSIONS

We described novel relations between thyroid hormones and markers of endothelial dysfunction in kidney transplant recipients. In kidney transplant recipients thyroid function metrics were associated with endothelial damage, immunosuppressive treatment, liver and kidney function. Therefore, the relations between thyroid axis and endothelium in kidney allograft recipients merit additional studies.

Resistin, a New Adipokine, Is Related to Inflammation and Renal Function in Kidney Allograft Recipients

BACKGROUND

Among patients without chronic kidney disease, resistin, an adipocytokine, has been related to inflammatory markers, coronary artery disease, and cardiovascular disease in the metabolic syndrome. Moreover, resistin up-regulates adhesion molecules. Since inflammation and endothelial cell damage or injury are invariably associated with thrombosis, atherosclerosis, and their major clinical consequences, resistin may play a role to link inflammation and CVD. The aim of this study was to correlate resistin with markers of inflammation and endothelial cell injury in 96 kidney allograft recipients.

METHODS

We measured resistin and the following markers of endothelial function/injury: vWF, thrombomodulin, VCAM, hsCRP, tumor necrosis factor alpha (TNFalpha), and interleukin-6 (IL-6).

RESULTS

Triglycerides, CRP (assessed by high-sensitivity method), phosphate, creatinine, IL-6, TNFalpha, vWF, prothrombin fragments 1 + 2, and resistin were elevated among kidney transplant recipients compared with the control group. Kidney allograft recipients with coronary artery disease displayed significantly higher resistin levels than those in patients without this complication. Upon univariate analysis resistin levels in kidney allograft recipients were related to hsCRP, IL-6, thrombomodulin, red blood cell count, white blood cell count, platelet count, creatinine, urea, VCAM, CSA, dose and eGFR. Upon multiple regression analysis, resistin was independently related only to creatinine, hsCRP, and white blood cell count in kidney allograft recipients.

CONCLUSIONS

The relation of elevated resistin levels to markers of inflammation may represent a novel link between these conditions and adipocytokines. Renal function was a major determinant of elevated resistin in kidney allograft recipients.

Modulation of hematopoiesis by ketanserin in erythropoietin-treated uremic patients: evidence from platelet studies

Recombinant human erythropoietin (EPO) not only ameliorates the anemia of renal failure but also modulates platelet function and corrects uremic platelet serotonin (5-hydroxytryptamine, 5-HT) storage pool deficiency. We studied if ketanserin, a blocker of platelet and vascular smooth muscle receptors for 5-HT, could reverse any EPO-induced changes in hemostasis. A complete blood count, immunoreactive serum EPO concentration, skin bleeding time (BT) and whole blood platelet aggregation (electric impedance method) induced by ristocetin and ADP, and intraplatelet and whole blood 5-HT, were determined in seven chronic hemodialysis (HD) patients before and after 1, 2, 4 and 8 weeks of EPO therapy, and repeated after a 4-week co-treatment with oral ketanserin. Stimulation of erythropoiesis was accompanied by a rise in the platelet count ( P < 0.05), shortening of the BT ( P < 0.02), an increase in platelet aggregability, and by replenished intraplatelet 5-HT store. Ketanserin co-treatment produced an unexpected 33% fall in serum EPO level ( P < 0.02), a decrease in the platelet count ( P < 0.05), prolongation of the BT ( P < 0.05) and depressed platelet aggregation in response to both agonists. There was no change in the amount of intraplatelet 5-HT while whole blood 5-HT concentration decreased significantly ( P < 0.02). Strong positive correlations between the decrease in whole blood 5-HT and the prolongation of the BT ( r = 0.786, P < 0.05), and between the former parameter and the fall in the platelet count ( r = 0.820, P < 0.05) were found. In conclusion, we report dual erythro- and thrombocytopoietic effects of EPO combined with correction of a platelet defect in the storage of 5-HT and enhanced platelet aggregability. The ketanserin-induced falls in serum EPO concentration and the platelet count provide new evidence of the dependency of thrombocytopoiesis on EPO in the initial weeks of the therapy. The 'antiplatelet' effects of ketanserin observed in this study seem to be due to reduction in circulating thrombocyte number rather than from any inhibitory effect on their aggregation.

Thrombin Activatable Fibrinolysis Inhibitor in Hypertensive Kidney Transplant Recipients

Kidney transplant recipients are prone to hypertension, dyslipidemia, and cardiovascular death. Hypertension is associated with hemostatic abnormalities. Thrombin activatable fibrinolysis inhibitor (TAFI) is a glycoprotein that links coagulation and fibrinolysis. The purpose of this study was to assess TAFI concentrations in renal transplant recipients in relation to blood pressure. Additionally, we evaluated thrombin activity (thrombin-antithrombin complex [TAT], prothrombin fragments 1+2 [F1+2]), thrombomodulin (TM), and the degree of plasmin generation (plasmin-antiplasmin complex [PAP]) using commercially available kits. The studies were performed on 86 renal allograft recipients (48 women, 38 men) at age range 26 to 73 years. The immunosuppressive regimen consisted of cyclosporine (CsA), prednisone, and azathioprine (n = 58) or mycophenolate mofetil (MMF; n = 28). All patients maintained sufficient and stable graft function, showing no clinical signs of rejection. In patients with hypertension (n = 68), we observed significantly higher concentrations of TAFI and of markers of thrombin generation (F1+2, TAT), and of thrombomodulin with significantly prolonged euglobulin clot lysis time (ECLT), which reflects overall fibrinolytic activity and lower fibrinolytic activity index (FAI). Both groups did not differ with respect to age, creatinine clearance, body mass index, time after transplantation, albumin, fibrinogen, and PAP. Diastolic blood pressure correlated significantly with TAFI concentrations, uric acid, and prednisone dose, whereas systolic blood pressure correlated with urea, uric acid, creatinine clearance, and MCV. Elevated TAFI concentrations and enhanced thrombin generation in hypertensive kidney transplant recipients may contribute to the hypofibrinolysis and progressive atherosclerosis in this population. Blood pressure was related to kidney function, maintenance prednisone dose, and TAFI concentration.

Correlations between leptin, body composition, bone mineral density, and bone metabolism in kidney transplant recipients

INTRODUCTION

In kidney transplant recipients leptin levels are often elevated and bone mineral density (BMD) decreased. However, to date there are no about correlations between leptin and BMD in this population. It has been suggested that leptin is a predictor of BMD in postmenopausal women. Moreover, leptin acts as a marker of fat stores. We examined the relationships between leptinemia, some markers of nutritional status, BMD, and bone metabolism in kidney transplant recipients. We also assessed whether leptin was a significant and independent predictor of BMD in this population.

METHODS

BMD and fat content (global, percentage, trunk) were measured using dual-energy X-ray absorptiometry in 27 kidney allograft recipients. Markers of bone turnover and leptin were studied using commercially available kits.

RESULTS

Leptin correlated with the percentage of body fat, trunk fat, lean body mass, serum creatinine, and urea. Insulin growth factor binding protein 1 was negatively related to waist-hip ratio and global and trunk fat, whereas BMD of the lumbar spine was correlated with the daily dose of prednisone, azathioprine, cyclosporine trough levels, serum calcium, as well as osteoprotegerin level.

CONCLUSIONS

Leptin levels are associated with graft function and body fat in kidney allograft recipients. Leptin is not related to nutritional status, BMD, or bone metabolism in kidney allograft recipients, but is associated with the current dosage of immunosuppressants and the serum calcium.

Intima media thickness of common carotid arteries is associated with traditional risk factors and presence of ischemic heart disease in hemodialysis patients

Patients with chronic renal failure are prone to cardiovascular complications. The mechanisms and the assessment of the risk of cardiovascular diseases (CVD) in this population are of interest. The purpose of this study was to investigate the traditional and potential risk factors for the development of CVD and their contribution to ischemic heart disease (IHD) and variation in carotid intima media thickness (IMT) in hemodialyzed patients (HD). Twenty-one chronically HD patients and nineteen healthy volunteers were recruited. Studied parameters were intima-media thickness, body mass index (BMI), mean arterial blood pressure (MAP), hemoglobin, fibrinogen (Fbg), serum lipids, lipoprotein (a) [Lp(a)], total homocysteine (tHcy). Mean carotid IMT, tHcy, Fbg and Lp(a) were higher in HD patients compared to the control group. There were no differences in cholesterol (tCh) and triglycerides between these groups. Patients with ischemic heart disease were older and they had higher values of carotid IMT, tCh, triglycerides, Fbg and Lp(a). There were no differences in MAP, time on dialysis and tHcy between the two subgroups (with vs without IHD). Carotid IMT correlated positively with age (r = 0.68, p = 0.001), BMI (r = 0.50, p = 0.02), tCh (r = 0.58, p < 0.01), LDL- cholesterol (r = 0.55, p = 0.01) and Fbg (r = 0.57, p < 0.01) but not with tHcy or Lp(a) in the patients group. Carotid intima media thickness thus reflects the risk for ischemic heart disease in hemodialyzed patients. Elevated fibrinogen concentration and dyslipidemia influence arterial remodelling.

Intima media thickness of common carotid arteries is associated with traditional risk factors and presence of ischaemic heart disease in hemodialysis patients

Patients with chronic renal failure are prone to cardiovascular complications. The mechanisms and the assessment of the risk of cardiovascular diseases (CVD) in this population are of interest. The purpose of this study was to investigate the traditional and potential risk factors for the development of CVD and their contribution to ischemic heart disease (IHD) and variation in carotid intima media thickness (IMT) in hemodialyzed patients (HD). Twenty-one chronically HD patients and nineteen healthy volunteers were recruited. Studied parameters were intima-media thickness, body mass index (BMI), mean arterial blood pressure (MAP), hemoglobin, fibrinogen (Fbg), serum lipids, lipoprotein (a) [Lp(a)], total homocysteine (tHcy). Mean carotid IMT, tHcy, Fbg and Lp(a) were higher in HD patients compared to the control group. There were no differences in cholesterol (tCh) and triglycerides between these groups. Patients with ischemic heart disease were older and they had higher values of carotid IMT, tCh, triglycerides, Fbg and Lp(a). There were no differences in MAP, time on dialysis and tHcy between the two subgroups (with vs without IHD). Carotid IMT correlated positively with age (r = 0.68, p = 0.001), BMI (r = 0.50, p = 0.02), tCh (r = 0.58, p < 0.01), LDL- cholesterol (r = 0.55, p = 0.01) and Fbg (r = 0.57, p < 0.01) but not with tHcy or Lp(a) in the patients group. Carotid intima media thickness thus reflects the risk for ischemic heart disease in hemodialyzed patients. Elevated fibrinogen concentration and dyslipidemia influence arterial remodelling.

Thrombin-activatable fibrinolysis inhibitor in kidney transplant recipient with dyslipidemia

Kidney transplant recipients are not only prone to dyslipidemia but also have a high risk of cardiovascular death. Impairment of the fibrinolytic system is thought to be one factor playing a role in development of thrombotic complications. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a glycoprotein, linking coagulation and fibrinolysis. The purpose of this study was to assess TAFI concentrations and activities in renal transplant recipients stratified based upon serum cholesterol values above 220 mg/dL or below 200 mg/dL. The groups did not differ regarding age, creatinine clearance, BMI, time after transplantation, albumin, fibrinogen, thrombomodulin, or PAP. Additionally, we evaluated thrombin activity (thrombin-antithrombin complex TAT, prothrombin fragments 1 + 2); TAFI activator; thrombomodulin (TM), catalyzer of TAFI activation; and the degree of plasmin generation (plasmin-antiplasmin complex PAP) using commercially available kits. In patients with hyperlipidemia significantly higher TAFI concentrations and activities may contribute to prolonged ECLT and lowered fibrinolytic activity index (FAI). Increased levels of F1 + 2 and TAT were observed in hypercholesterolemic patients, indicating enhanced thrombin generation. Elevated TAFI concentration, and activities and enhanced thrombin generation observed in hypercholesterolemic kidney transplant recipients may contribute to hypofibrinolysis and progression of atherosclerosis in this group of patients.

Some aspects of hemostasis in kidney transplant recipients maintained on cyclosporine, azathioprine, and prednisone in comparison to patients treated with cyclosporine and prednisone

Cyclosporine (CyA) has been implicated to increase cardiovascular morbidity and mortality after renal transplantation. Impairment of the fibrinolytic system is one factor involved in the development of thrombotic complications. The aim of this study was to compare hematological and hemostatic parameters among patients on CyA, azathioprine, and prednisone (n = 31) versus CyA and steroids (n = 14). Using commercially available kits we evaluated thrombin activity as thrombin-antithrombin complexes (TAT), prothrombin fragments (1 + 2), thrombin activatable fibrinolysis inhibitor-(TAFI), TAFI activator, thrombomodulin (TM)-a marker for endothelial cell injury,-plasmin generation (plasmin-antiplasmin complex PAP), a glycoprotein linking coagulation and fibrinolysis. We observed that patients not treated with azathioprine displayed longer prothrombin times and activated partial thromboplastin times; higher fibrinogen, platelet counts and fibrinolytic activity index (FAI); shorter euglobulin clot lysis time; as well as lower thrombin generation markers namely, prothrombin fragments 1 + 2 and thrombin-antithrombin complexes. Although patients in the non-AZA group tended to have been engrafted for a longer time (P =.086), the groups did not differ with regard to age, BMI, erythrocyte count, hematocrit, leukocyte count, creatinine clearance, alanine and asparagine aminotransferase activities mean arterial blood pressure, fibrinogen, TAFI, thrombomodulin, or plasmin-antiplasmin complexes. These findings suggest that kidney transplant recipients on triple therapy are at greater risk of cardiovascular disease than those without azathioprine treatment, despite the lower fibrinolytic activity.

Plasma tissue-type plasminogen activator, fibrinogen, and time on dialysis prior to transplantation are related to carotid intima media thickness in renal transplant recipients

The majority of deaths among patients after renal transplantation is attributed to cardiovascular disease (CVD). Intima media thickness (IMT) of the common carotid artery is related to coronary and cerebrovascular arterial disease. One of the major causes of death due to CVD is acute coronary syndrome, which is precipitated by coronary plaque rupture and subsequent thrombosis. The aim of the study was to evaluate associations between some fibrinolytic factors: antigens of tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor (PAI-1), and thrombin-activatable fibrinolysis inhibitor (TAFI), and IMT in a population of renal transplant recipients. The study was performed on 33 Caucasian, clinically stable kidney transplant recipients (11 women, mean age 43 years, range 26 to 62 years). All the patients were on triple immunosuppressive regimen (cyclosporine, prednisone, and azathioprine) and had stable graft function (serum creatinine 1.7 +/- 0.7 mg/dL). The mean time since transplantation was 49.9 months (range 4.1 to 131.8 months). In univariate analysis IMT correlated significantly with age (r =.5; P =.001), pulse pressure (PP) (r =.4; P =.05), time on dialysis prior to transplantation (r =.6; P =.001), fibrinogen (r =.4; P =.02), and t-PA (r =.6; P =.001). Multiple regression analysis showed that t-PA antigen concentration (P =.001), fibrinogen (P <.05), and time on dialysis prior to transplantation (P <.05) were positive independent predictors of IMT. These data support the concept of the coincidence of disturbances in fibrinolysis and arterial remodelling in patients after kidney transplantation. On the other hand the study shows that the duration of dialysis therapy before transplantation is detrimental to the arterial vasculature.

Osteoprotegerin and its correlations with new markers of bone formation and bone resorption in kidney transplant recipients

Osteoprotegerin (OPG), a natural decoy receptor for osteoclast differentiation factor, is produced by osteoblasts in response to PTH. OPG and its ligand RANKL constitute a complex mediator system involved in the regulation of bone resorption, probably playing an important role in the homeostasis of bone turnover. At present, little is known about the effects of OPG on uremic bone. Successful kidney transplantation reverses many abnormalities of bone metabolism; however, the improvement is often incomplete. The aim of the study was to assess OPG and RANKL concentrations in long-term kidney allograft recipients and their correlations with biochemical markers of bone resorption and formation. The present studies on 48 kidney transplant recipients and 25 healthy volunteers included concentrations of parathormone, osteocalcin, bone-specific alkaline phosphatase, serum CrossLaps, calcidiol, calcitriol, ICTP, PICP, tartrate-resistant acid phosphatase, beta2 microglobulin, IGF-1, IFGBP-1, IGFBP-3, OPG, and RANKL using commercially available kits for measurements. Among kidney transplant recipients OPG and RANKL did not differ between transplant patients and healthy volunteers, whereas other markers of bone formation and resorption were significantly higher in the former group. OPD was related to age, time on dialysis prior transplantation, urea, platelet count, CSA dose, azathioprine dose, 25(OH)D(3), TRAP, IGF-1, IGFBP-3, whereas RANKL was related to leukocyte count, CSA concentration and dose, urine DPD, and beta2 microglobulin content. In healthy volunteers OPG correlated only with CrossLaps, whereas RANKL correlated only with osteocalcin and TRAP. Correlations between OPG, IGF system components, and some markers of bone metabolism may indicate the role of OPG/RANKL system in the pathogenesis of bone metabolism disturbances following renal transplantation.