Effects of superoxide dismutase and catalase on growth of retinal pigment epithelial cells in vitro following addition of linoleic acid or linoleic acid hydroperoxide

The rod outer segments of the retina that are phagocytized by retinal pigment epithelial (RPE) cells are susceptible to lipid peroxidation because of their high content of polyunsaturated fatty acids. Linoleic hydroperoxides (LHP), synthesized by peroxidation of linoleic acids (LA), produce greater damage to retinal function than does LA. We compared the effects of LHP and LA on the growth of cultured chick embryonic RPE cells and analyzed a model of data sets using multiple linear regression for the number of cells as a function of time. The spectrum of LA had a sharp peak at 205 nm and a broad spectrum at 235 nm, while LHP had only a broad spectrum at 235 nm. Exposure to LA and LHP caused dose-dependent damage of chick embryonic RPE cells: they were significantly more affected by the addition of LHP than LA. The antioxidative enzymes catalase and superoxide dismutase minimized damage to the RPE cells caused by LHP in proportion to the enzyme concentration. However, RPE cells incubated with LA were more affected by the enzymes than when no enzymes were added.