Biochemical Markers of Oxidative Stress in Predialytic Chronic Renal Failure Patients

Combined Clinical Phenotype and Lipidomic Analysis Reveals the Impact of Chronic Kidney Disease on Lipid Metabolism

Chronic kidney disease (CKD) results in significant dyslipidemia and profound changes in lipid and lipoprotein metabolism. The associated dyslipidemia, in turn, contributes to progression of CKD and its cardiovascular complications. To gain an in-depth insight into the disorders of lipid metabolism in advanced CKD, we applied UPLC-HDMS-based lipidomics to measure serum lipid metabolites in 180 patients with advanced CKD and 120 age-matched healthy controls. We found significant increases in the levels of total free fatty acids, glycerolipids, and glycerophospholipids in patients with CKD. The levels of free fatty acids, glycerolipids, and glycerophospholipids directly correlated with the level of serum triglyceride and inversely correlated with the levels of total cholesterol and eGFR. A total of 126 lipid species were identified from positive and negative ion modes. Out of 126, 113 identified lipid species were significantly altered in patients with CKD based on the adjusted FDR method. These results pointed to profound disturbance of fatty acid and triglyceride metabolisms in patients with CKD. Logistic regression analysis showed strong correlations between serum methyl hexadecanoic acid, LPC(24:1), 3-oxooctadecanoic acid, and PC(20:2/24:1) levels with eGFR and serum creatinine levels (R > 0.8758). In conclusion, application of UPLC-HDMS-based lipidomic technique revealed profound changes in lipid metabolites in patients with CKD. The observed increases in serum total fatty acids, glycerolipids, and glycerophospholipids levels directly correlated with increased serum triglyceride level and inversely correlated with the eGFR and triglyceride levels.

Gene and protein expressions and metabolomics exhibit activated redox signaling and wnt/β-catenin pathway are associated with metabolite dysfunction in patients with chronic kidney disease

Changes in plasma concentration of small organic metabolites could be due to their altered production or urinary excretion and changes in their urine concentration may be due to the changes in their filtered load, tubular reabsorption, and/or altered urine volume. Therefore, these factors should be considered in interpretation of the changes observed in plasma or urine of the target metabolite(s). Fasting plasma and urine samples from 180 CKD patients and 120 age-matched healthy controls were determined by UPLC-HDMS-metabolomics and quantitative real-time RT-PCR techniques. Compared with healthy controls, patients with CKD showed activation of NF-κB and up-regulation of pro-inflammatory and pro-oxidant mRNA and protein expression as well as down-regulation of Nrf2-associated anti-oxidant gene mRNA and protein expression, accompanied by activated canonical Wnt/β-catenin signaling. 124 plasma and 128 urine metabolites were identified and 40 metabolites were significantly altered in both plasma and urine. Plasma concentration and urine excretion of 25 metabolites were distinctly different between CKD and controls. They were related to amino acid, methylamine, purine and lipid metabolisms. Logistic regression identified four plasma and five urine metabolites. Parts of them were good correlated with eGFR or serum creatinine. 5-Methoxytryptophan and homocystine and citrulline were good correlated with both eGFR and creatinine. Clinical factors were incorporated to establish predictive models. The enhanced metabolite model showed 5-methoxytryptophan, homocystine and citrulline have satisfactory accuracy, sensitivity and specificity for predictive CKD. The dysregulation of CKD was related to amino acid, methylamine, purine and lipid metabolisms. 5-methoxytryptophan, homocystine and citrulline could be considered as additional GFR-associated biomarker candidates and for indicating advanced renal injury. CKD caused dysregulation of the plasma and urine metabolome, activation of inflammatory/oxidative pathway and Wnt/β-catenin signaling and suppression of antioxidant pathway.

The bacterial colonization in tunneled cuffed dialysis catheter and its effects on residual renal function in incident hemodialysis patients

BACKGROUND

The bacterial colonization of hemodialysis catheter occurs frequently and reaches to the catheter-related bloodstream infections (CRBSIs). We hypothesized bacterial colonization promotes inflammation and that might be associated with renal outcome. The aim of this study was to investigate the colonization status for tunneled cuffed dialysis catheter (TCC) and the factors for contributing to the catheter colonization and explore whether bacterial colonization would be related with declining of residual renal function (RRF).

METHODS

115 patients who received TCC removal operation and underwent catheter tip culture from January 2005 to June 2014 were enrolled. The follow-up data such as urine output (UO), time to anuria and patients' survival were collected from the patients or their family members by telephone in June, 2014.

RESULTS

There were nineteen patients (16.5 %, 19/115) with positive tip culture (colonization group). In the analysis of demographic and biochemical parameters, there were no significant differences between both groups. Fifty of all the subjects responded to the telephone survey and ten patients (20.0 %, 10/50) belonged to colonization group. The monthly decreasing rate of UO was significantly more rapid in colonization group (p = 0.001). The survival analysis showed that colonization group had worse estimated anuria-free survival than non-colonization group (p < 0.001). In multivariate cox regression, bacterial colonization of TCC was an independent factor influencing the loss of RRF (HR 4.29, 95 % CI: 1.905-9.683, p ≤ 0.001).

CONCLUSIONS

Bacterial colonization of TCC was associated with rapid loss of RRF.

Effect of different stages of chronic kidney disease and renal replacement therapies on oxidant-antioxidant balance in uremic patients

Oxidative stress seems to be involved in the path physiology of cardiovascular complications of chronic kidney disease (CKD). In this study, we determined the effect of different stages of CKD and substitutive therapies on oxidative stress. One hundred sixty-seven patients (age: 44 ± 06 years; male/female: 76/91) with CKD were divided into 6 groups according to the National Kidney Foundation classification. Prooxidant status was assessed by assaying thiobarbituric acid reactive substances, hydroperoxides, and protein carbonyls. Antioxidant defence was performed by analysis of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, vitamin E, Iron, and bilirubin. TBARS and LPO were higher in HD patients compared to other groups (P < 0.001), while protein carbonyls were more increased in PD patients. The antioxidant enzymes were declined already at severe stage of CKD and they were declined notably in HD patients (P < 0.001). Similar observation was found for vitamin E, Fe, and bilirubin where we observed a significant decrease in the majority of study groups, especially in HD patients (P < 0.001). The evolution of CKD was associated with elevated OS. HD accentuates lipid, while PD aggravates protein oxidation. However, the activity of antioxidant enzymes was altered by impaired renal function and by both dialysis treatments.