Effect of non-lethal H2O2-induced persistent oxidative injury on retinal pigment epithelial barrier

Abstract

Background Reactive oxygen intermediate products lead to the oxidative injury of cells.Retinal pigment epithelial(RPE) cells produce lots of reactive oxygen intermediate products during the swallow of out disc,but how this procedure cause the persistent oxidative injury of RPE cells is poorly understood. Objective The present study was to evaluate the effect of non-lethal H2 O2 -induced persistent oxidative injury on RPE barrier in vitro.Methods ARPE-19 cell links were inoculated on 96 well plate at the density of 8×104 cells/L and the cell climbing slice of 24 well at the density of 4× 104 cells/L.The cells were cultured in DMEM/F12 medium,and the cells cultured for 24 hours in free-serum medium were used in the experiment.0-0.6 mmol/L of H2O2 were added into the medium.Cellular viability was assessed using 3- ( 4,5-dimethylthiazol-2-yl ) -5- ( 3-carboxymethoxyphenyl ) -2- ( 4-sulfophenyl ) 2H-tetrazolium(MTS) assays.Transepithelial electrical resistance (TER) was used to detect cell monolayer forming time after culture in Trsnswell chamber.The permeability of cell monolayer was examined by rhodamine isothiocyanate-dextran transepithelial flux,and immunofluorescence was used to investigate the distribution of the junction protein zonula occludens (ZO-1). Results The total difference was found in the cell vitality(A490) among the different concentrations of H2 O2 ( F =991.501,P =0.000 ).Compared with 0 mmoL/L H2 O2 group,the A490 values was gradually lowed from 0.20 mmol/L H2O2 group to 0.60 mmol/L H2O2 group (P ＜ 0.05 ).H2O2 at the concentrations of ＞0.20 mmol/L lowed the viability of RPE cells.The TER value was ( 24.9 ± 1.3 ) Ω · cm2 in 11 days,( 17.8± 1.4)Ω · cm2 in 7 days after inoculation on transwell chamber,showing a significant difference between them (t=5.228,P=0.014).RPE formed the stable tight junction on day 15 with the TER value (25.9±0.9 ) Ω · cm2.The leakage amount ( relative fluorescence intensity ) of the dextran was 255.39 ± 16.44 in non-H2 O2 control group,exhibiting a significant lowing in comparison with free-cell blank group (433.08±51.53)( t =12.515,P =0.006 ),and that of H2 O2 group was significant increased in comparison with non-H2 O2 control group ( t =14.412,P=0.005).Immunofluyorescence assay showed intact intercellular ZO-1 junction in non-H2O2 control group,but the breakage of ZO-1 junction was seen in H2O2 group. Conclusions The results indicate that non-lethal H2O2 can destroy RPE barrier and further lead to the persistent oxidative injury of RPE cells. Key words: H2O2; Retinal pigment epithelium; Oxidative stress; Tight junction