title: Epithelial-mesenchymal transition-like phenotypic changes of retinal pigment epithelium induced by TGF-β are prevented by PPAR-γ agonists.
abstract: OBJECTIVE
  Proliferative eye diseases, such as proliferative vitreoretinopathy and proliferative diabetic retinopathy, are caused partly by fibrotic change of retinal pigment epithelial cells (RPECs). The purpose of our study was to examine the effect of the peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist on the fibrotic change of primate RPECs.
  
  
  METHODS
  Monkey RPECs (MRPECs) isolated from a cynomolgus monkey eye were subcultured. To induce fibrotic change, MRPECs were cultured with TGF-β2 (3 ng/mL), and also cultured in the coexistence of TGF-β2 and the PPAR-γ agonist pioglitazone (30 μM). The phenotype of the cultured MRPECs was evaluated by phase contrast microscopy and immunocytochemical analysis. The phosphorylation of Smad2/Smad3 proteins was examined by Western blot analysis.
  
  
  RESULTS
  Primary MRPECs were cultured as a monolayer with a hexagonal cell shape, and positive expression of ZO-1, Na(+)/K(+)-ATPase, and RPE65 was confirmed. Cell morphology and the expression of these markers were maintained in the presence of pioglitazone, whereas the cells were elongated and the expression of these markers was reduced in its absence. Conversely, the expression of phalloidin, α-smooth muscle actin, and fibronectin was reduced in the presence of pioglitazone, whereas it was increased in the absence. Western blot assay demonstrated that phosphorylation of Smad2/Smad3 proteins was suppressed by pioglitazone.
  
  
  CONCLUSIONS
  The PPAR-γ agonist pioglitazone inhibited the fibrotic change of primary MRPECs through the suppression of TGF-β signaling. Pioglitazone might prove to be a clinically applicable and effective pharmaceutic treatment for proliferative eye diseases.
authors.affiliation: Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Hatanaka
authors.forename: Noriko
authors.initials: N
authors.lastname: Koizumi
authors.forename: Naoki
authors.initials: N
authors.lastname: Okumura
authors.forename: EunDuck P
authors.initials: EP
authors.lastname: Kay
authors.forename: Eri
authors.initials: E
authors.lastname: Mizuhara
authors.forename: Junji
authors.initials: J
authors.lastname: Hamuro
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kinoshita
mesh_terms: D000818:Animals; D015153:Blotting, Western; D048430:Cell Shape; D002478:Cells, Cultured; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects*; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007150:Immunohistochemistry; D008252:Macaca fascicularis; D008858:Microscopy, Phase-Contrast; D047495:PPAR gamma / Q000819:agonists*; D010641:Phenotype; D010766:Phosphorylation; D000077205:Pioglitazone; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D045162:Thiazolidinediones / Q000494:pharmacology*; D053781:Transforming Growth Factor beta2 / Q000494:pharmacology*; D062826:Zonula Occludens-1 Protein / Q000378:metabolism; D019745:cis-trans-Isomerases / Q000378:metabolism; D000099178:Retinoid Isomerohydrolase
chemical_list: D007004:Hypoglycemic Agents; D047495:PPAR gamma; D000077205:Pioglitazone; D051899:Smad2 Protein; D051900:Smad3 Protein; D000254:Sodium-Potassium-Exchanging ATPase; D045162:Thiazolidinediones; D053781:Transforming Growth Factor beta2; D062826:Zonula Occludens-1 Protein; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase