Inflammation and oxidation: do they improve after kidney transplantation? Relationship with mortality after transplantation.

Patients with chronic kidney disease (CKD) are characterized by a state of inflammation and oxidative stress that seems to improve after kidney transplantation (KT). Nevertheless, there is controversy regarding what is the best marker that better define inflammation and specially oxidative stress. OBJECTIVE: To evaluate the biomarkers which are associated with improvements in inflammation and lipid peroxidation in patients who have undergone KT. To evaluate the relationship between inflammation, lipid peroxidation and mortality in KT. PATIENTS: 196 KT (between 2003 and 2008). 67.9% men; median age: 51.9 years. Inflammation markers analyzed previous KT and 3 months after KT: c-reactive protein(CRP), interleukin 6(IL-6), tumor necrosis factor alpha(TNFα), soluble tumor necrosis factor receptor alpha(sTNFRα), soluble interleukin-2 receptor (sIL-2R). Lipid peroxidation markers analyzed: oxidized low-density lipoprotein (oxLDL) and anti-oxLDL antibodies. Calculation of glomerular filtration rate after KT: MDRD equation. RESULTS: Following KT, there is a significant decrease in CRP (p = 0.006), IL-6 (p = 0.0037), TNFα (p < 0.0001), sTNFRα (p < 0.0001) and sIL-2R (p < 0.0001), while levels of oxLDL increase after KT (p < 0.0001) and there is not a significantly difference in anti-oxLDL. 12.8% of the patients had died in 2012. These patients had higher levels of IL-6 (p = 0.011) and sTNFRα (p < 0.006) after KT and a lower MDRD (p < 0.0001), hemoglobin (p = 0.012) and albumin (p = 0.007). We observed no statistically differences in the levels of markers previous KT. Of the patients who died, the 43.5% of them had anti-oxLDL antibody levels greater than 75th percentile (P75: 3781 UI/ml, p = 0.028). In the multivariate analysis, age (OR:1.12; p = 0.0129), MDRD (OR:0.92; p = 0.013) and P75 of anti-oxLDL(OR: 5.19; p = 0.026) were independent risk factors for mortality. Independent risk factors for survival were: P75 of IL-6 (HR: 2.45; p = 0.027), oxLDL (HR:19.85; p = 0.002) and anti-oxLDL (HR: 9.55; p = 0.003). CONCLUSIONS: KT improved inflammation but not lipid oxidative state. KT patients who died had a higher inflammatory state (with higher levels of IL-6 and sTNFRα), a worse lipid oxidative state and a worse renal function 3 months after KT. Age, anti-oxLDL and renal function at 3 months after KT were independent risk factors for mortality.

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 manufacturer's 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.

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.

Magnetic bead-based proteomic technology to study paricalcitol effect in kidney transplant recipients.

Secondary hyperparathyroidism is a common complication in patients with chronic kidney disease and frequently persists after kidney transplantation. Paricalcitol, a selective vitamin D receptor activator, is indicated in the management of this disorder and recent evidences have suggested that this drug has other beneficial effects. Aiming to elucidate these effects, our study included 52 stable kidney transplant recipients randomized 2:1 to treatment with paricalcitol or to no treatment. Bone mineral parameters, kidney function and inflammatory status were assessed at baseline, at 3 and at 12 months. Moreover, a proteomic approach, based on magnetic beads technology coupled to MALDI-TOF mass spectrometry readout, was used to determine changes in patients' plasma peptidome. Patients treated with paricalcitol showed a significant decrease in parathyroid hormone and alkaline phosphatase levels, and an increase of bone mineral density and glomerular filtration rate. The proteomic analysis revealed a decrease in bradykinin after paricalcitol treatment, whereas 2 peptides identified as fragments of the complement factor C4 decreased only in those patients not treated with paricalcitol. These findings suggest that paricalcitol may offer additional benefits due to immunomodulatory effects via the kallikrein-kinin and complement systems.