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Hiroki Hatanaka, Naoki Okumura, Noriko Koizumi, Eri Mizuhara, Junji Hamuro, Shigeru Kinoshita; Effect Of The PPAR Agonist On The Fibrotic Change In Primate Retinal Pigment Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5313.
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© ARVO (1962-2015); The Authors (2016-present)
Proliferative eye diseases such as proliferative vitreoretinopathy and proliferative diabetic retinopathy are a major cause of blindness. These diseases are mainly caused by the fibrotic change of retinal pigment epithelial cells (RPEs). The purpose of this present study was to examine the effect of the peroxisome proliferator-activated receptor γ (PPARγ) agonist on the anti-fibrotic effect of primary cultured primate RPEs.
Monkey RPEs (MRPEs) were isolated from the eyes of 10 cynomolgus monkeys and then subcultured with culture medium containing 2% fetal bovine serum. As a fibrotic group, MRPEs were cultured with medium containing TGF-β2 (3ng/ml) for 48 hours. As a PPARγ agonist-treated group, MRPEs were cultured with medium containing TGF-β2 and PPARγ agonist (30 μM). Culture medium without TGF-β2 was used as a control. The phenotype of MRPEs was evaluated by phase contrast microscopy and by immunohistochemical analysis of function-related markers ZO-1, Na+/K+-ATPase, and RPE65. The production of extracellular matrix was determined by quantitative real-time polymerase chain reaction (PCR) for collagen type-1 mRNA. The phosphorylation of Smad2 protein was examined by Western blot analysis.
MRPEs were cultured as a monolayer and with a hexagonal cell shape, and positive expression of ZO-1, Na+/K+-ATPase, and RPE65 was confirmed. Cell morphology and the expression of those markers were maintained in the PPARγ agonist-treated group. In the fibrotic group, the cells were elongated with evident stress fibers and the expression of markers was found to be decreased. The level of collagen type-1 mRNA was found to be decreased in the PPARγ agonist-treated group, however, it was increased in the fibrotic group (94.3% and 151.5% vs control, respectively). Western blot assay demonstrated that phosphorylation of Smad2 protein induced by TGFβ2 was suppressed by the PPARγ agonist.
The findings of this study demonstrate that the PPARγ agonist inhibits the fibrotic change of RPE through the suppression of TGFβ signaling. We speculate that the PPARγ agonist might be an applicable and effective pharmaceutical treatment for proliferative eye diseases.
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