Anti-oxidant status in relation to lipoproteins, leptin and pro-inflammatory cytokines in children with steroid-sensitive nephrotic syndrome

Background: Reactive oxygen species and cytokines are reported to play a role in the proteinuria of nephrotic syndrome. The aim of this study was to investigate indirect evidence of oxidant activity together with leptin, lipoproteins and pro-inflammatory cytokines in children with steroid-sensitive nephrotic syndrome. Methods: A total of 40 children with steroid-sensitive nephrotic syndrome (20 with newly onset or relapse comprised group I and 20 in remission while receiving steroids comprised group II) and 20 sex and age matched healthy control children were included. The following indirect parameters of oxidant activity were determined: serum malondialdehyde, erythrocyte superoxide dismutase, catalase and whole-blood-reduced glutathione. Serum leptin, lipids and lipoproteins were also determined. Results: Similar glutathione, increased malondialdehyde levels and decreased superoxide dismutase and catalase activity were observed in group I patients compared with controls. There was no significant difference in these variables between group I and group II (P > 0.05). Tumour necrosis factor-alpha and interleukin-6 concentrations were similar in patients and controls. Concentrations of interleukin-1beta and interleukin-8 were higher in the active phase of nephrotics compared with controls (P < 0.05). Significant positive correlations were found between malondialdehyde and interleukin-1beta, interleukin-6, leptin and lipoprotein (a) (P < 0.05). There were significant negative correlations between anti-oxidants and leptin, lipoprotein (a) and several cytokines (P < 0.05). Conclusions: Changes in the concentrations of malondialdehyde, superoxide dismutase, catalase and glutathione are compatible with increased amounts of oxidation in steroid-sensitive nephrotic syndrome. Leptin and pro-inflammatory cytokines may be related to excessive protein permeability in nephrotic syndrome.