No acute impact of haemodialysis treatment on free radical scavenging enzyme gene expression in white blood cells

Association Between Superoxide Dismutase Isoenzyme Gene Expression and Total Antioxidant Status in Patients with an End-Stage Renal Disease

Background:

Chronic renal failure, particularly end-stage renal disease, is a serious health problem associated with a high mortality rate. Uremic syndrome leads to increased oxidative stress, inflammation, and dyslipidemia.

Aims:

To examine superoxide dismutase isoenzyme gene expression in peripheral blood mononuclear cells of patients on hemodialysis and to determine the associations between superoxide dismutase isoenzyme gene expression, oxidative stress, and non-enzymatic antioxidative protection.

Study Design:

Case control study.

Methods:

This study included 33 patients on hemodialysis (age, 55.33±15.31 years old) and 33 apparently healthy controls (age, 45.37±8.92 years old). Superoxide dismutase isoenzyme messenger ribonucleic acid levels were determined by real-time polymerase chain reaction. General biochemical parameters, high sensitivity C-reactive protein, total antioxidant status, thiobarbituric acid-reactive substances, and the superoxide anion radical were also determined.

Results:

Normalized Cu/Zn superoxide dismutase and Mn superoxide dismutase messenger ribonucleic acid levels were significantly higher in patients than controls (p<0.001 and p=0.011). A significant negative correlation was detected between normalized Cu/Zn superoxide dismutase messenger ribonucleic acid levels and total protein, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total antioxidant status. Normalized Mn superoxide dismutase messenger ribonucleic acid levels were negatively correlated with total protein and total antioxidant status. A multiple regression analysis revealed independent associations between total antioxidant status and normalized Cu/Zn superoxide dismutase (p=0.038) and between total antioxidant status and normalized Mn superoxide dismutase messenger ribonucleic acid levels (p=0.038 and p=0.018, respectively).

Conclusion:

The superoxide dismutase isoenzyme gene is expressed at a higher rate in patients with end-stage renal failure, probably due to increased oxidative stress and attenuated antioxidative defense. The plasma total antioxidant status is an independent predictor of normalized superoxide dismutase isoenzyme messenger ribonucleic acid levels.

Serum antioxidant capacity is preserved in peritoneal dialysis contrary to its robust depletion after hemodialysis and hemodiafiltration sessions

Renal replacement therapy (RRT) may differentially affect systemic generation of reactive oxygen species and depletion of antioxidant pools of low molecular weight molecules and proteins. This study was designed to assess the magnitude of the impairment of serum total antioxidant capacity (TAC) in relation to different RRT modalities. The study included patients on continuous ambulatory peritoneal dialysis (CAPD, N = 21), hemodialysis (HD, N = 21), hemodiafiltration (HDF, N = 20), and healthy controls (N = 33). TAC was assessed by the ferric reducing ability of plasma (FRAP) and with the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay. In CAPD patients, predialysis FRAP and DPPH were increased: 1.46 mM and 10.5% vs. control 1.19 mM and 7.2%, respectively (P < 0.001 in each). In HD and HDF patients, the FRAP and DPPH were significantly increased before and lowered after the RRT session (P < 0.05) if compared with healthy controls. During an HD session, FRAP was decreased from pre-HD 1.71 +/- 0.29 mM to post-HD 0.85 +/- 0.20 mM (P = 0.0001). The decrease of FRAP was lower during HDF (P < 0.05 vs. HD), it decreased from pre-HDF 1.41 +/- 0.43 mM to post-HDF 0.87 +/- 0.23 mM (P = 0.0001 vs. pre-HDF). The HD session decreased DPPH from the pre-HD median 10.3%, interquartile range (IR) 9.3-12.0% to post-HD 2.6% IR 2.3-3.1% (P < 0.0001). The adjustment of either urate or bilirubin up to pre-HD levels did not restore lowered post-HD levels of TAC. TAC remains preserved in CAPD, whereas the robust depletion of TAC, lower after HDF than HD sessions, cannot be attributed solely to the washout of dialyzable compounds.

Phagocyte-derived oxidants and plasma antioxidants in haemodialysed patients

OBJECTIVE

Oxidative stress is one of the important complications occurring in haemodialysis. The aim of the study was to determine haemodialysis-induced changes in oxidative burst of phagocytes and the antioxidative properties of plasma.

METHODS

Twenty-seven patients and 50 healthy controls were examined. Oxidative burst of phagocytes and plasma antioxidative potential were measured luminometrically. Concentrations of major plasma antioxidants (vitamin E, bilirubin and uric acid) were also determined.

RESULTS

Phagocyte chemiluminescence was higher in patients before haemodialysis compared with that in controls and decreased after haemodialysis compared with predialysis status. A significant increase in plasma antioxidative potential and uric acid was found in patients before haemodialysis. These parameters decreased after haemodialysis compared with both predialysis and control values.

CONCLUSIONS

The higher generation of phagocyte-derived oxidants and the decline in plasma antioxidative properties after haemodialysis confirm insufficient antioxidant defence in patients with chronic renal failure.