The Effect of A2E On The Levels of ROS and The Distribution of A2E in RPE Cells Exposed to Blue Light
Abstract AimsTo establish the N-retinylidene-N-retinylethanolamine(A2E) and blue light induced RPE cells damage model to explore the regularity of distribution of A2E and the levels of reactive oxygen species(ROS).MethodsThe fourth to sixth generation of human RPE cells in vitro were divided into five groups randomly: control group, blue light group, A2E-loaded group, A2E-loaed+blue light group and A2E-loaded+blue light +nifedipine group. The levels of ROS in cytoplasm by DCFH-DA staining was assayed by flow cytometry. The concentration of A2E in cytoplasm and lysosomes were assayed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). The fluorescence intensity of A2E in lysosomes by Lysotracker redDND-99 staining was assayed by confocal laser scanning microscope. ResultsExposure to blue light and/or A2E could increase the levels of ROS in RPE cells, and nifedipine could inhibit oxidative stress response and reduce ROS levels. By HPLC-MS, it was found that A2E was not detected in the groups without load A2E, and A2E levels in cytoplasm and lysosomes decreased after light exposure. The green fluorescence produced by A2E loaded on RPE cells was mostly coincident with the red fluorescence labeled by lysosomes.ConclusionBlue light and A2E can increase the ROS levels of RPE cells and both have a synergistic effect. A2E is mainly concentrated in lysosomes, which is reduced by oxidation under blue light irradiation, damages lysosomal membrane with oxidized species of A2E, and leaks out from lysosomes.