The Protective Effects of Nitroxides Against Oxidative Damage to Human Keratin ocytes / 中华皮肤科杂志

ABSTRACT

Objective To study the protective effects of nitroxides against hu man keratinocytes oxidative damage induced by H2O2 and its possible mechanisms. Methods Normal human keratinocyte cultures obtained from foreskin were served as test-system. Human keratinocytes were cultured in human keratinocytes growth m edia (KGM) without serum and supplemented with 0.1 mmol/L Ca2+. Experiments wer e performed in culture when the cells grew to fuse. Oxidative damage was induced by adding H2O2 directly to the culture media at different concentrations in the present and absence of nitroxides [(2, 2, 6, 6-tetramethylpiperidine (TEMPO) a nd 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine (TEMPOL)]. The cell viability w as monitored and the intracellular level of reduced glutathione (GSH), the activ ities of glutathione-peroxidase(GSH-Px), superoxide dismutase (SOD), and catal ase were evaluated. Results ①H2O2 could cause damage to human keratinocytes dir ectly. There was a significantly negative correlation between H2O2 concentration and cell viability. ②The level of GSH in keratinocytes lowered with treatment of H2O2. The activities of GSH-Px, SOD and catalase decreased. ③Pretreatment o f the cells with TEMPO and TEMPOL inhibited the damaging effects of H2O2 on cell viability and on cell antioxidant enzymatic systems. Conclusion The results of the study suggest that nitroxides may provide protection for cultured human kera tinocytes against H2O2-induced oxidative injury. It is proposed that the effec ts of nitroxides against cell oxidative damage be related to their protection of cellular enzymatic activities and maintaining cellular antioxidant systems.