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T.A. Bailey, N. Kanuga, J. Greenwood, M.E. Cheetham, P.J. Luthert; Oxidative Stress Disrupts Tight Junctions in RPE Cells . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1635.
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Purpose: Oxidative stress is speculated to be a contributory factor in the pathogenesis of Age-related Macular Degeneration (AMD). Culture of the cell line ARPE-19 results in the development of some characteristics typical of those for RPE in vivo, namely localization of tight junction proteins to the cell periphery, and formation of a monolayer that resists transepithelial flux of large molecules. Our aim was to examine the effect of oxidative stress on stress protein production and the function of tight junctions. Methods: ARPE-19 cells were exposed to different concentrations of hydrogen peroxide. These cells were assessed for a response to oxidative stress by examining heme oxygenase-1 (HO-1), Hsp70 and Hsp27 by immunocytochemistry and western blotting. Immunocytochemistry was also used to investigate the localization of tight junction proteins such as Zonula Occludens-1 (ZO-1) and occludin in both treated and untreated cells. The functionality of tight junctions was examined by measurement of flux of fluorescein conjugated dextrans from the apical to basal aspect of cells cultured on semi permeable polycarbonate membranes. Results: APRE-19 cells showed differential sensitivity to oxidative stress dependent on their state of differentiation. Increased HO-1, Hsp70 and Hsp27 expression reflected these differences in sensitivity. Stress proteins did not relocalize within the cell on oxidative stress, unlike under heat stress conditions. Exposure to hydrogen peroxide did, however, result in the disorganization of the peripheral expression of ZO-1 and occludin. This disruption of tight junctional proteins was mirrored by an increase in trans-epithelial flux of conjugated dextrans in peroxide treated cells. Conclusions: Hydrogen peroxide treatment induces stress protein production in ARPE-19 cells in direct relation to their differentiation status. Oxidative stress also leads to the disruption of tight junctions in RPE cells, a process that may contribute to the pathogenesis of AMD and other diseases related to RPE permeability and viability.
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