Assessment of oxidative stress in patients with sickle cell disease: The glutathione system and the oxidant-antioxidant status

Abstract

Continuous reactive oxygen species (ROS) production in individuals with sickle cell disease (SCD) may alter their overall redox status and cause tissue damage. The aim of this study was to evaluate oxidative stress in patients with SCD using two new assays, FORT (free oxygen radical test) and FORD (free oxygen radical defense) along with assessment of glutathione system including superoxide dismutase (SOD), glutathione reductase (GR) and glutathione peroxidase (GPx) activities, vitamins A, C and E, malondialdehyde (MDA), non-transferrin bound iron (NTBI) and nitric oxide (NO) concentrations. A total of 40 patients with SCD and 25 apparently healthy volunteers (control group) were enrolled in the study. Components of glutathione system, vitamins A, C, and E, and malondialdehyde were determined with reverse-phase HPLC, non-transferrin bound iron (NTBI) was assessed with atomic absorption spectroscopy using graphite furnace, superoxide dismutase (SOD), glutathione reductase (GR) and glutathione peroxidase (GPx) activities were determined spectrophotometrically in red cell lysates, nitric oxide (NO) was detected colorimetrically, while FORT and FORD using colorimetric assays, as two point-of-care tests. The findings revealed significant impairment of the glutathione system indicated by reduced GSH(total) (p<0.00001), GSH(reduced) (p<0.00001) and GSSG (p>0.056) values of SCD patients compared to the control group. ROS expressed as FORT were significantly increased (p<0.00001), while antioxidant defense expressed as FORD was significantly reduced (p<0.02) in SCD group compared to the control group. Age and genotype of the patients as well as therapy of their disease appeared to play no role in their oxidative status.