Abstract
Abstract: :
Purpose: Oxidative stress in the retinal pigment epithelium (RPE) has been implicated in the pathogenesis of age–related macular degeneration (AMD). Smoking is a major risk factor for the development of AMD and nicotine, the addictive component, has been shown to have both oxidative and anti–oxidant properties. This study examines the direct effects of nicotine on RPE cells in the acute and chronic setting. Methods: ARPE–19 cells were exposed to nicotine in complete medium, at concentrations of 0.01uM to 1.0uM. For acute exposure, cells were incubated with nicotine for 12 hours. For chronic exposure, cells were incubated for 14 days, the medium being changed every 3 days. Supernatents were collected and IL–8 quantified using ELISA. Oxidative stress was measured using two methods: 1) Flow cytometry, measuring intra–cellular reactive oxygen species 2) TBARS assay, measuring lipid peroxidation products. Results: Acute and chronic exposure to nicotine at 0.1uM significantly increased the release of IL–8. Intra–cellular reactive oxygen species and lipid peroxidation products were correspondingly increased. IL–8 Release (pg/ml)
* ANOVA P < 0.05 Conclusions: We have demonstrated that nicotine induces oxidative stress in RPE cells, at concentrations found in the plasma of smokers. The resultant increase in IL–8 release may attract a chronic inflammatory infiltrate to the blood retinal barrier, promoting angiogenesis, or contributing to the breakdown of Bruch's membrane.
Keywords: retinal pigment epithelium • oxidation/oxidative or free radical damage • neovascularization