Oxidative damage, lipid peroxidation and inhibition of NADPH oxidase activity by transition metals (Fe and Ni) in human polimorphonuclear leukocyte cells.

FERRAROTTI, N.; MUSACCO SEBIO, R.; REPETTO, M.

Santiago, Chile

Congreso; VI Meeting of Society for Free Radical Biology and Medicine South American Group; 2009

Society for Free Radical Biology and Medicine South American Group

The cellular toxicity of transition metal ions in biological systems is a complex process that involves reactive oxygen species and redox reactions with cellular components. The aim of this study was to evaluate the participation of Iron (Fe) and Nickel (Ni) on the cellular mechanisms of oxidative damage in human polymorphonuclear leukocyte (PMN) cells, by measuring the NADPH oxidase activity, superoxide anion (O2-) and hydrogen peroxide (H2O2) generation, total cellular glutathione (GSH), superoxide dismutase (SOD) and catalase activities, and thiobarbituric acid reactive substances (TBARS). Cells were studied in the absence (- PMA) and in the presence (+ PMA) of Phorbol 12-myristate acetate (PMA, 0.1µg/ml) and 200 µM apocynin, and were divided in three groups: control, incubated with 25 µM Fe (III) and with 25 µM Ni (II) solutions, for 1 hour at 25 ºC. In ?PMA cells, Fe promotes lipid peroxidation by Fenton reaction by increasing the reactive oxygen species production (O2-:1.7 times, half percent concentration,C50%=50 µM; H2O2: 13.3 times, C50%=10 µM); and by redox equivalent consumption: increased NADPH oxidation by 9.1 times (C50%>=50 µM) and total GSH PMN content decreased by 17% compared with the control PMN. Ni increased H2O2 production (10.8 times, C50%=10 µM) and SOD activity (5.0 times), but does not promote lipid peroxidation. In +PMA cells, Fe and Ni inhibited the NADPH oxidase activity (C50%=10 µM), decreased O2-(CI50%:10 µM Fe, 40 µM Ni), and H2O2 production (CI50%:30 µM). Fe induced PMN toxicity by an oxidative mechanism. The effects of Ni on cellular homeostasis may be better explained by the structural and biological effects of H2O2 proteins and antioxidant enzymes.