M.C. Pastor

Posttransplant Inflammation Associated With Onset of Chronic Kidney Disease

BACKGROUND Chronic allograft nephropathy (CAN), a major complication in renal transplant patients, is an important cause of graft loss. Inflammation as measured in the pretransplant and posttransplant phases, using various markers, has been associated with worse renal function and a greater risk of cardiovascular disease and of long-term graft loss. OBJECTIVE The objective of our study was to evaluate whether worsening inflammation in the first 3 months postoperatively was a risk factor for developing CAN. PATIENTS AND METHODS We performed a cross-sectional study in 207 patients. The following markers of inflammation (MIF) were determined pretransplant and at 3 months after grafting: C-reactive protein (CRP) (mg/L), interleukin (IL)-6 (pg/mL), IL-10 (pg/mL), tumor necrosis factor (TNF)-α (pg/mL), and its soluble receptor (ng/mL), soluble-IL2R (UI/mL), pregnancy-associated plasma protein A (PAPP-A; mUI/L), and IL-4 (pg/mL). We also calculated the ratio at 3 months versus the pre value of MIF. RESULTS CAN was diagnosed after the first year in 23 patients (11.3%) always by renal biopsy performed for clinical indications. Patients with CAN showed worse inflammation, eg, MIF ratios over one, with statistically significant differences for the ratios of TNF-α and PAPP-A (P=.032 and P=.051 respectively). Upon multivariate logistic regression analysis, using CAN as the dependent variable and age, sex, donor age, months on dialysis, acute tubular necrosis, acute rejection, and MIF ratios as covariates, we observed that an acute rejection episode (OR=13.03; CI=2.8-60.9; P=.001), CRP ratio (OR=1.36; CI=1.07-1.73; P=.013), and PAPP-A ratio (OR=1.80; CI=0.92-3.53; P=.005) were independent markers of CAN. CONCLUSIONS Among other factors, inflammation may determine the onset of CAN as diagnosed by renal biopsy.

Urinary Peptide Profiling to Differentiate between Minimal Change Disease and Focal Segmental Glomerulosclerosis

Background Minimal change disease (MCD) and primary focal segmental glomerulosclerosis (FSGS) are the main causes of primary idiopathic nephrotic syndrome in children and adults, with diagnosis being essential for the appropriate choice of therapy and requiring renal biopsy. However, the presence of only normal glomeruli on renal biopsy of FSGS patients may lead to the misclassification of these patients as having MCD. The aim of this study was to (i) compare the peptide profile of MCD and FSGS patients with that of a group of healthy subjects, (ii) generate and validate a class prediction model to classify MCD and FSGS patients and (ii) identify candidate biomarkers of these glomerular entities by analysis of the urinary peptidome. Methods The urinary peptide profile was analyzed by magnetic bead-based technology combined with MALDI-TOF mass spectrometry in 44 patients diagnosed of MCD (n = 22) and FSGS (n = 22). The resulting spectra were compiled and analyzed using ClinProTools software. Results A class prediction model was developed to differentiate MCD and FSGS patients. The validation of this model correctly classified 81.8% (9/11) of MCD patients and 72.7% (8/11) of FSGS patients. Moreover, the signal with m/z 1913.60, identified as a fragment of uromodulin, and the signal with m/z 2392.54, identified as a fragment of alpha-1-antitrypsin, showed higher and lower peak areas, respectively, in FSGS patients compared with MCD patients. Conclusions The simple, non-invasive technique described in the present study may be a useful tool to help clinicians by confirming diagnoses achieved by renal biopsy, thereby reducing misdiagnoses and avoiding the implementation of inappropriate therapies.

Effect of Paricalcitol on the Urinary Peptidome of Kidney Transplant Patients

BACKGROUND AND OBJECTIVE Disorders in bone mineral metabolism are common after kidney transplantation, covering, among other pathologic conditions, secondary hyperparathyroidism. Paricalcitol, a selective vitamin D receptor activator, is indicated in the prevention and treatment of secondary hyperparathyroidism. Recent evidence suggests that paricalcitol is also associated, by mechanisms not yet clarified, with improved patient survival. To clarify these unknown mechanisms, the aim of this study was to determine whether 3 months of treatment with paricalcitol modified the urinary peptidome of kidney transplant patients. METHODS This prospective study included 42 stable kidney transplant patients, randomized in 2 groups: a group treated with 1 μg/d paricalcitol (n=25) and a control group that did not receive paricalcitol (n=17). Urine samples of all patients were collected at baseline and after 3 months. The proteomic approach was based on magnetic bead technology coupled to MALDI-TOF mass spectrometry. RESULTS Paricalcitol treatment produced significant changes in urinary peptidome of kidney transplant patients. Variations in urinary peptides were independent of the degree of proteinuria and of the decrease in parathyroid hormone levels. CONCLUSIONS With this preliminary study, we obtained a profile of urinary peptides in which changes occurred due to treatment with paricalcitol. The identification of proteins to which these peptides belong may improve our knowledge about the possible pleiotropic effects of paricalcitol.

Greater posttransplant inflammation and oxidation are associated with worsening kidney function in patients with pretransplant diabetes mellitus.

OBJECTIVE Patients on dialysis display increased inflammation (IF) and oxidative stress (OS). Diabetes mellitus (DM) may increase both processes. The role of transplantation in this situation is unknown. Herein we have assessed the evolution of IF and OS following grafting and its relationship to a prior diagnoses of DM and to kidney function at 1 year. PATIENTS AND METHODS This prospective study included 131 dialysis patients who underwent transplantation of mean age 54 +/- 12 years, including 68% men with 19.5% showing prior DM. The following markers of IF and OS were determined prior to and at 3 months after grafting: C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor alpha (TNFalpha), soluble TNFalpha receptor (sTNFalpha-R), soluble IL-2 receptor (sIL-2R), oxidized LDL (oxLDL), and anti-oxLDL antibodies (oxLDLab). The evolution (ratio) of these markers was assessed by dividing the values at 3 months by the prior ones. Modification of Diet in Renal Disease (MDRD) was determined at 12 months. RESULTS Patients with prior DM were older (P = .034). There were no differences in the pregrafting phase between diabetics and nondiabetics in relation to IF or OS. IF and OS showed a worse evolution postgrafting among patients with prior DM. At 1 year postgrafting renal function was greater in patients without prior DM (P = .022). There was an inverse correlation between the ratios of markers and kidney function at 1 year postgrafting: TNFalpha: r = -.235 (P = .012); sIL-2R: r = .441 (P < .001); and sTNFalpha-R: r = .225 (P = .017). CONCLUSIONS In the pregrafting phase, there were no differences between patients with or without DM in terms of IF and OS. These differences appeared in the postgrafting phase: patients with DM showed greater IF and OS, an increase that may explain the poor kidney function observed at 1 year among patients with DM.

Apolipoprotein E alleles, dyslipemia and kidney transplantation

ARDIOVASCULAR DISEASE is the main cause of morbidity and mortality in kidney transplant (KT) recipients. 1 Hyperlipidemia is a known risk factor for cardiovascular disease. Polymorphism of the apolipoprotein E (Apo E) gene may affect plasma lipoprotein levels and composition and the risk of kidney disease. The aim of the present study was to ascertain the influence of the Apo E genotype on renal function and lipid profile in KT patients and analyze the effect of cerivastatin in relation to different phenotypes. PATIENTS AND METHODS Forty-five KT recipients who had their transplants for more than 1 year, with stable renal function (serum creatinine 200 mol/L) and persistent hypercholesterolemia (total cholesterol 6 mmol/ L), were included. Dietary counseling was indicated and treatment started with cerivastatin at 0.3 mg/d. Duration of the study was 3 months. Lipids were determined with a DAX 48 analyzer (Bayer). Apo E polymorphism was determined by PCR. Results are expressed as mean SD. Statistical test results with a probability of .05 were considered statistically significant. RESULTS The Apo E genotype showed E3E3 in 31, E4E3 in 11, E4E4 in one, and E2E2 in two KT recipients. Allele frequency was: E2 4%, E3 81%, E4 14%, and was similar to that of the control group. Patients with the E4 allele had higher total cholesterol levels prior to treatment (total cholesterol in patients with the E3 allele 6.92 0.8 mmol/L vs E4 of 7.22 0.86 mmol/L; P .05). The remaining lipid profile parameters (cholesterol HDL, LDL, TG, Apo B, and atherogenic index) showed no statistically significant differences. Following cerivastatin administration, the decreases in total cholesterol and LDL cholesterol were 20% and 18.9%, respectively, in patients with allele E4, with no statistical difference. KT patients with allele E4 have better renal function (Cl creatinine E3 56.11 13.17 mL/min vs Cl creatinine E4 70.15 22.14 mL/min) (P .05). DISCUSSION Dyslipemia is a very frequent cardiovascular risk factor in KT patients. Previous researchers have reported that apolipoprotein E plays a role in lipoprotein metabolism, and studies exist that show that the Apo E genotype could be responsible for between 1% and 14% of the variability in plasma total cholesterol and LDL cholesterol levels. As described in the literature, 2 we found that patients with allele E4 presented higher cholesterol levels. The response to hypolipemiant treatment, both dietary and pharmacological, may be modulated by the genetic variability of the lipoprotein. A recent meta-analysis found the presence of allele 4 to be associated with a significantly better response

Hepcidin and Iron Deficiency in Pre-Kidney Transplant Patients

Hepcidin is a hormone that regulates the intestinal absorption of iron and its release from the reticuloendothelium. The objective of this study was to determine the use of hepcidin for kidney disease patients with a diagnosis of iron deficiency pretransplantation by evaluating the soluble transferrin receptor (sRTfR-F) index as a marker for iron deficiency. This transverse study of 164 pretransplant patients determined hematometry and conventional markers related to iron metabolism, as well as soluble transferrin receptor (sTfR), its index (sTfR-F), and serum hepcidin concentrations. The following markers of inflammation (MIF) were also assessed C-reactive protein (hs-CRP), interleukin-6 (IL-6), soluble IL-2 receptor (sIL-2R), tumor necrosis factor-alpha (TNF-alpha), and soluble TNF-alpha receptor (s-TNF-alphaR). Among the studied patients, 11.4% showed an absolute iron deficiency with ferritin concentrations < 100 ng/mL, a mean hepcidin value of 120.7 +/- 38.5 ng/mL, and a mean sTfR-F value of 1.03 +/- 0.3; 18.2% of patients displayed a ferritin > 800 ng/mL with mean hepcidin and sTfR-F values of 147.5 +/- 36.6 ng/mL and 0.54 +/- 0.2, respectively. Iron deficiency was not observed in the other patients when considering the conventional markers: ferritin > 100 ng/mL and transferrin saturation (ST) > 20%. However, this study showed that determination of hepcidin concentrations together with M/F improved the identification of iron deficiency in pretransplant patients by 21.6%.

Sodium interference in the determination of urinary aldosterone.

OBJECTIVES Primary hyperaldosteronism (PHA) is one of the most common endocrine forms of secondary hypertension. Among the most used confirmatory tests for PHA is urinary aldosterone determination after oral sodium loading test. The primary aim of our study was to investigate if sodium concentrations interfere with urinary aldosterone in an automated competitive immunoassay (Liaison®) as well as to verify the manufacturers specifications. DESIGN AND METHODS 24-hr urine samples were collected and stored frozen until assayed. Two pools at low and high aldosterone concentrations were prepared. Verification of performance for precision was tested according to Clinical and Laboratory Standards Institute (CLSI) document EP15-A2 and interference with increasing concentrations of NaCl according to CLSI EP7-A2. RESULTS The assay met the quality specifications according to optimal biological variation. Our results show that sodium concentrations up to 200mmol/L do not interfere on urinary aldosterone quantification, but sodium concentrations above 486mmol/L negatively interfere with the test. CONCLUSIONS The Liaison® automated method is useful for aldosterone determination in the PHA confirmatory test, but interferences with NaCl may occur. It is therefore recommended to determine urinary NaCl before measuring urinary aldosterone to avoid falsely low results.