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A.M. Geller, L. Degn, W.C. Williams; Phagocytosis by Retinal Pigment Epithelial Cells in vitro Is Affected by Exposure to Pesticides . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1603.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Agricultural and occupational exposures to the fungicides benomyl and captan and the insecticide fenthion have been associated with retinal degeneration. Exposure to insecticides has also been associated with pigmentary changes of the retina. Because retinal degeneration and pigmentary changes may be due to dysfunction of the retinal pigment epithelium (RPE), we tested RPE cell function and viability with exposure to pesticides. Methods: Human–derived RPE cells, ARPE–19, were grown to confluence in 12 well plates, then co–incubated (2–24 hours) with pesticides and rod outer segments (ROS) labeled with fluorescein isothiocyanate or fluorescent microspheres. Cells were exposed to the insecticide fenthion (10–7 – 10–5 M) and the fungicide benomyl (3 x 10–6 – 3 x 10–4 M), concentrations that have been shown to affect cell viability and function in other neurally–derived cell lines. Another fungicide, captan (3 x 10–6 – 3 x 10–4 M), was also tested. Cell viability was assayed with a propidium iodide/calcein live/dead (L/D) assay. Phagocytosis was evaluated using flow cytometry or fluorescent phase microscopy. Phagocytosis was also evaluated under conditions previously reported to inhibit this function (incubation in cold or with colchicine). Results: ARPE–19 cell viability was reduced with exposure to increasing concentrations of the fungicides benomyl and captan. Viability was not affected by fenthion in the range tested. Phagocytosis by ARPE–19 cells was not affected by fenthion. Preliminary results show reduced phagocytosis with exposure to benomyl and captan. Phagocytosis was inhibited by cold and by incubation with colchicine. Conclusions: The reduction in phagocytosis in RPE cells by benomyl and captan suggests that this may be a candidate mechanism underlying their association with retinal degeneration. Conversely, fenthion did not affect the cells’ ability to phagocytize ROS, suggesting that toxicity due to this compound is not mediated by this mechanism. Further dose response experiments will better establish the relationship of functional deficits to cell viability. This abstract does not reflect US EPA policy.
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