Nicotine Increases the VEGF/PEDF Ratio in Retinal Pigment Epithelium: A Possible Mechanism for CNV in Passive Smokers with AMD

作者：Pons Marianne; Marin Castano Maria E^*

来源：Investigative Ophthalmology & Visual Science, 2011, 52(6): 3842-3853.

DOI：10.1167/iovs.10-6254

PURPOSE. Cigarette smoking is the strongest environmental risk factor for wet age-related macular degeneration (AMD). Inappropriate expression of proangiogenic vascular endothelial growth factor (VEGF) and antiangiogenic pigment epithelium derived factor (PEDF) may cause choroidal neovascularization (CNV), a key event in wet AMD, resulting in vision loss. Nicotine (NT), a potent angiogenic agent abundant in second-hand smoke, may play a major role in the pathogenesis of wet AMD. The purpose of this study was to evaluate the expression of nicotinic acetylcholine receptors (nAchR) in retinal pigment epithelium (RPE) and determine the effects of NT on RPE-derived VEGF and PEDF expression in the context of passive smoking.
METHODS. Human RPE cells were treated with NT (10(-8) M), with or without the nAchR-nonspecific antagonist hexamethonium (HXM) (10(-5) M) for 72 hours. RPE sheets were microdissected from rats exposed to NT in drinking water (100 mu g/mL), with or without HXM (40 mg/kg/d, intraperitoneally), for 72 hours. Cell death was determined by cell count and proliferation by Western blot for proliferating cell nuclear antigen (PCNA). nAchR expression was examined by real-time PCR and Western blot. ERK activation was evaluated by Western blot analysis. VEGF and PEDF expression was assessed by ELISA, Western blot, and real-time PCR.
RESULTS. Cultured RPE cells constitutively expressed the nAchR alpha 3, alpha 10, and beta 1 subunits, with beta 1 being the most prevalent. The nAchR alpha 4, alpha 5, alpha 7, and beta 2 subunits were detected in RPE sheets from rats, among which alpha 4 is the predominant subtype. NT, which did not result in either cell death or proliferation, induced beta 1 nAchR, upregulated VEGF, and downregulated PEDF expression through nAChR in ARPE-19 cells. Transcriptional activation of the nAchR alpha 4 subunit and nAChR-mediated upregulation of VEGF and PEDF were observed in RPE from rats exposed to NT.
CONCLUSIONS. NT increased the VEGF-to-PEDF ratio in the RPE through nAchR in vitro and in vivo. This alteration in the ratio may play a key role in the progression to wet AMD in passive smokers. (Invest Ophthalmol Vis Sci. 2011; 52: 3842-3853) DOI: 10.1167/iovs.10-6254

• 出版日期2011-5