[Effects of pioglitazone on the transdifferentiation and CTGF expression of renal tubular epithelial-myofibroblast in vitro].
OBJECTIVE
To investigate whether pioglitazone can inhibit TGF-beta-induced phenotypic remodeling of renal tubular epithelial cell and the expression of CTGF, so to illuminate the anti-fibrotic mechanism of pioglitazone.


METHODS
Cultured NRK52E cells were divided into control group, TGF-beta-treated (3 ng/mL) group, TGF-beta (3 ng/mL)and DMSO-treated group, TGF-beta and pioglitazone-treated groups with different doses. The morphological change of cultured tubular cells was observed under phase-contrast microscopy. Immunohistochemistry were used to assess the alpha-SMA+ cells, and the expression of alpha-SMA mRNA, CTGF mRNA was measured by RT-PCR. The level of collagen type III in the culture supernatant was measured by ELISA.


RESULTS
1) Confluent NRK52E cells cultured in medium with 5% FCS showed a normal epithelial morphological state and cobblestone pattern. All cells almost had no expression of alpha-SMA and CTGF. After the NRK52E cells were cultured with TGF-beta 3 ng/mL for 5 days, many cells had strong cytoplasmic staining for alpha-SMA, and alpha-SMA+ cells showed marked hypertrophy and elongated shape. The levels of alpha-SMA mRNA and CTGF mRNA in TGF-beta-treated group cells were higher than those of normal control group (P < 0.05). Compared with control group, there were significant increases of collagen type III content in supernatant of TGF-beta-treated groups (P < 0.05). 2) The phenotypic changes induced by TGF-beta were prevented by incubation with pioglitazone. Pioglitazone inhibited the expression of alpha-SMA mRNA and CTGF mRNA of NRK52E cells, and the supernatant content of collagen type III in a dose-dependent manner (P < 0.05). 3) CTGF mRNA expression of NRK52E cells was significantly associated with alpha-SMA mRNA expression (r = 0.975, P< 0.01), and the content of collagen type III (r = 0.988, P<0. 01). The expression of rSMA mRNA was correlated with the content of collagen type IT (r 0. 952, P<0. 01).


CONCLUSIONS
Pioglitazone may negatively regulate TEMT through inhibiting the expression of CTGF.
Pu
Lei
L
Department of Nephrology, West China Hospital, Sichuan University, Chengdu, China.
Fan
Jun-Ming
JM
D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D054338:Cell Transdifferentiation; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000378:metabolism; D058628:Myofibroblasts / Q000166:cytology*; D000077205:Pioglitazone; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D045162:Thiazolidinediones / Q000494:pharmacology*; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000494:pharmacology
C526316:CCN2 protein, rat; D012333:RNA, Messenger; D045162:Thiazolidinediones; D016212:Transforming Growth Factor beta; D055513:Connective Tissue Growth Factor; D000077205:Pioglitazone