Purchase this article with an account.
H. Cho, S. Kim, Y.H. Yoon; Toxic Effects of Chloroquine on Human Retinal Pigment Epithelial Cells in Culture . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1644.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Chloroquine is a therapeutic agent used for systemic lupus erythematosus and rheumatoid arthritis. However, prolonged chloroquine therapy may lead to toxic maculopathy. Since the cellular and molecular mechanisms of chloroquine maculopathy are not well understood, here we sought to find the mechanism of chloroquine-induced cell death in human cultured RPE cells. Methods: Cultured RPE cells were exposed for 24 h to 10, 50, 100, or 150 µM of chloroquine, without or with the addition of antioxidant trolox (100 µM), protein synthesis inhibitor cycloheximide (2 µg/ml), and caspase inhibitor zVAD (100-200 µM). Cathepsin-D activity (by the method of Boulton) was measured to asess lysosomal enzyme activity, and LDH release into the media was measured to quantify cell death. In addition, TUNEL staining and transmission electron microscopy were performed. Results: RPE cells exhibited severe cytoplasmic vacuolar changes and destruction of cell membrane following exposure to 50 µM chloroquine. Addition of cycloheximide prevented the cell membrane changes, but did not alter the vacuolar degeneration. The activity of a lysosomal enzyme cathepsin-D decreased, as concentration of chloroquine increased. Eventually, in a concentration-dependent manner, chloroquine exspoure induced cell death and LDH release. A protein synthesis inhibitor, cycloheximide, and a caspase inhibitor zVAD-fmk, attenuated chloroquine-induced RPE cell death. On the other hand, an antioxidant trolox did not attenuate the cell death. TUNEL staining revealed DNA fragmentation, and transmission electron microscopy showed chromatin condensation and nuclear fragmentation, suggesting that the death occurs mainly by apoptosis. Conclusions: The main finding of the present study is that chloroquine induced RPE cell death, which exhibited morphological and biochemical features of apoptosis. Consistently, a protein synthesis inhibitor and a caspase inhibitor blocked the cell death. However, the vacuolar changes in cytoplasm were not attenuated by inhibition of protein synthesis or caspases, indicating that this cytopathic event may occur independent of the apoptosis mechanism.
This PDF is available to Subscribers Only