Alterations of glomerular and extracellular glutathione peroxidase levels in patients and rats with focal segmental glomerulosclerosis

Glutathione peroxidase (GPX) is an important antioxidant that effectively scavenges hydrogen peroxide. Recent studies have revealed that plasma GPX activity is decreased in patients with chronic kidney failure. However, there have been no reports on renal and urinary GPX levels in patients with kidney disorders. Therefore in this study we have measured the plasma and urinary GPX levels and glomerular GPX immunostaining in patients with focal segmental glomerulosclerosis (FSGS) and normal kidney function as compared with those in patients with minimal change disease (MCD) and those in normal control subjects. Rats with puromycin aminonucleoside-induced FSGS were also studied. The results showed that the plasma GPX level was significantly lower in FSGS patients than in either MCD patients or normal control subjects (both P<.01). The urinary GPX level was also significantly lower in FSGS patients than in either MCD patients (P <.05) or normal control subjects (P <.01), The immunostaining score of glomerular GPX was significantly lower in FSGS patients than in normal control subjects (both P <.05), Serial examinations of glomerular GPX immunostaining in FSGS rats also demonstrate a decrease in the score with the progression of disease. Our results indicate that all the plasma, urinary, and glomerular GPX levels are decreased in FSGS patients, indicating a decreased antioxidant defense in the early stages of chronic glomerular diseases.