Oxidative damage induces MCP-1 secretion and macrophage aggregation in age-related macular degeneration (AMD)

Age-related macular degeneration (AMD) is a major cause of progressive and degenerative visual impairment. Although the exact pathogenic mechanism of AMD is still unknown, clinical observations such as the high accumulation of oxidative products and macrophages in retina suggest the importance of oxidative stress and inflammation in AMD. Mouse photoreceptor-derived 661 W cells and human ARPE-19 cells were treated with oxidized phospholipids (Ox-PC) or H2O2 to mimic oxidative damage. The effect of monocyte chemoattractant protein 1 (MCP-1) secreted by retina cells on the migration of monocyte macrophage RAW 264.7 cells was determined using transwell chambers and antibody neutralization assay. MCP-1, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and vascular endothelial growth factor (VEGF) that secreted into supernatant were measured by ELISA and their intracellular expression was detected by qRT-PCR and western blot. Intracellular Ox-PC level was detected by competitive ELISA. The amount of migrated RAW 264.7 cells was counted by flow cytometry. Oxidative damage by both H2O2 and Ox-PC induced the secretion of MCP-1 in human ARPE-19 and mouse 661 W cells. MCP-1 induced by oxidative damage enhanced the migration ability of macrophage RAW 264.7 cells and the secretion of TNF-alpha, IL-1 beta and VEGF, which could be reduced by anti-MCP-1 neutralizing antibodies. The results indicated that oxidative damage increases intracellular Ox-PC and the secretion of MCP-1 in retina cells. The increased MCP-1 induced by oxidative damage attracts macrophages to retinas, and macrophages release pro-inflammatory factor and promote the process of AMD.