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Farrukh A. Shamsi, Mike Boulton; Inhibition of RPE Lysosomal and Antioxidant Activity by the Age Pigment Lipofuscin. Invest. Ophthalmol. Vis. Sci. 2001;42(12):3041-3046.
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purpose. To determine whether lipofuscin is detrimental to lysosomal and
antioxidant function in cultured human retinal pigment epithelial (RPE)
methods. Isolated lipofuscin granules were fed to confluent RPE cultures and the
cells maintained in basal medium for 7 days. Parallel cultures were
established that did not receive lipofuscin. Cultures were either
exposed to visible light (390–550 nm) at an irradiance of 2.8
mW/cm2 or maintained in the dark at 37°C for up to 24
hours. Cells were subsequently assessed for cell viability, lysosomal
enzyme activity, and antioxidant capacity.
results. There was no loss of cell viability during the first 3 hours of light
exposure, whereas a 10% loss of viability was observed in
lipofuscin-fed cultures after 6 hours’ exposure to light. Activities
of acid phosphatase, N-acetyl-β-glucuronidase, and
cathepsin D were decreased by up to 50% in lipofuscin-fed cells
exposed to light compared with either unfed cells or cells maintained
in the dark. There was also a decrease in the antioxidant potential of
RPE cells. Catalase and superoxide dismutase activities decreased by up
to 60% and glutathione levels by 28% in light-exposed lipofuscin-fed
cells compared with unfed cells or cells maintained in the dark.
conclusions. Lipofuscin has the capacity to reduce the efficacy of the lysosomal and
antioxidant systems in RPE cells that may play an important role in
retinal ageing and the development of age-related macular
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