Copper-induced oxidative damage on astrocytes: protective effect exerted by human high density lipoproteins

In the present study, we confirmed that copper ions induce oxidative damage in human astrocytes in culture, as demonstrated by the significant increase in the levels of hydroperoxides and in the fluorescence intensity of the fluorescent probe dichloro-dihydrofluorescein diacetate (H(2)DCFDA). The compositional changes were associated with a significant decrease in cell viability in astrocytes treated with 10 microM Cu(++) with respect to control cells. Astrocytes incubated with copper ions in the presence of high density lipoproteins (HDL) isolated from plasma of normolipemic subjects showed lower levels of hydroperoxides and a higher cell viability with respect to cells oxidized alone. Moreover, a significant decrease in the levels of hydroperoxides was observed in oxidized astrocytes treated with HDL. These results demonstrate that HDL exert a protective role against lipid peroxidation. The protective effect could be related to the ability of HDL to bind metal ions at the lipoprotein surface and/or to a stimulation of the efflux of lipid hydroperoxides from cell membranes as demonstrated in other cell types. Oxidative damage of astrocytes was induced at a copper concentration similar to that observed in cerebrospinal fluid (CSF) of patients affected by neurodegenerative diseases such as Alzheimer's (AD) and Parkinson's diseases (PD). Lipoprotein particles similar for density and chemical composition to plasma HDL were recently isolated in human CSF, therefore, the protective role exerted by HDL against Cu(++)-induced oxidative damage of astrocytes could be of physiological relevance.