Abstract
Abstract: :
Purpose:We previously demonstrated that the up-regulation of monocyte chemoattractant protein-1 (MCP-1) expression in de-differentiated retinal pigment epithelial (RPE) cells has an important role in the development of choroidal neovascularization (CNV) of age-related macular degeneration (AMD). Also, recent epidemiologic studies indicate that a high intake of fish oil, which contains abundant n-3 polyunsaturated fatty acids (PUFAs) reduces the risk of AMD. To explore the possible association of PUFAs with the development of CNV in AMD, the present study focused on the effects of PUFA on the expression of MCP-1 and vascular endothelial growth factor (VEGF), a potent angiogenic factor, in human RPE cells. Methods:Human RPE cells cultured on plastic were used as dedifferentiated cells. RPE cells seeded on laminin-coated flasks were used as differentiated controls. For the PUFA treatment, the RPE cells were incubated with 10% FBS-DMEM containing arachidonic acid (AA, 20:4, n-6), eicosapentaenoic acid (EPA, 22:5, n-3), docosapentaenoic acid (DPA, 22:5, n-3), and docosahexaenoic acid (DHA, 22:6, n-3) at a concentration of 3 µg/ml for 4 d. The medium was then changed to serum-free DMEM. The medium was collected after 24 h and was analyzed for the production of VEGF and MCP-1 using ELISA. Results:De-differentiated RPE cells expressed high levels of MCP-1 without any stimuli, and the MCP-1 level was unchanged after PUFA treatment. In differentiated cells, however, MCP-1 expression increased after stimulation with tumor necrosis factor-α(TNF-α), and the pretreatment with n-3 fatty acids inhibited MCP-1 production. Also, n-3 fatty acids markedly inhibited VEGF production in de-differentiated RPE cells whereas they had no effect in differentiated cells. Conclusions:N-3 fatty acids exert an anti-angiogenic effect by first inhibiting inflammatory cell recruitment via down-regulation of MCP-1 in differentiated RPE cells, and then by down-regulating VEGF after cells are dedifferentiated. These findings provide clues to the molecular mechanisms of the anti-angiogenic action of PUFAs in AMD. N-3 fatty acids might therefore be a useful drug or supplement for the prevention of AMD.
Keywords: choroid: neovascularization • age-related macular degeneration • retinal pigment epithelium