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K. Sun, H. Cai, T.H. Tezel, D. Paik, E.R. Gaillard, L.V. Del Priore; Nitration of Extracellular Matrix Decreases Photoreceptor Phagocytosis by Human RPE . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1378.
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© ARVO (1962-2015); The Authors (2016-present)
There is increasing evidence to suggest that age–related damage in human Bruch's membrane (BM) a can negatively impact RPE cell function. However, the processes that result in the accumulation of such age–related damage to BM are not well understood. Last year we demonstrated that aging of human Bruch’s membrane decreases RPE phagocytosis of outer segments. Nitrite modification of BM ECM may be important in the pathogenesis of AMD since human nitrite exposure can result from inflammation and cigarette smoking, both of which are strongly associated with AMD. Here we determine the effect of extracellular matrix (ECM) nitrite modification on the phagocytic function of RPE.
ARPE19 were seeded onto RPE–derived, unmodified ECM and nitrite–modified ECM–coated wells (50,000 cells/ well). Adult bovine rod outer segments (ROS) purified by sucrose gradient centrifugation were labeled with 10ug/ml fluorescein isothiocyanate and fed to the RPE. RPE were examined by fluorescence microscopy and flow cytometry to quantify ROS phagocytosis.
After 2 weeks, the confluence of RPE cultured on nitrite modified ECM was 40% less than on native ECM. The mean area of RPE cells on native ECM (1019 ± 47 arbitrary Unit) and nitrite modified ECM (932 ± 32 arbitrary Unit; p > 0.05) were similar. Nitrite modification of ECM reduced RPE cell ROS phagocytosis by about 50% (126.7 ± 12.8 vs. 60.8 ± 8.2 arbitrary units; unmodified versus nitrite modified ECM, respectively; p<0.01).
Nitrite modification of ECM significantly decreases ROS uptake by RPE in culture. The ECM may play a significant role in controlling phagocytosis of ROS and our data suggest that age related damage to the ECM may significantly and deleteriously alter the ability of RPE to phagocytose ROS. These results may have implications for the effects of Bruch’s membrane aging on RPE function in AMD.
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