Triamcinolone acetonide suppresses interleukin-1 beta-mediated increase in vascular endothelial growth factor expression in cultured rat Müller cells.
OBJECTIVE
Intravitreal injection of triamcinolone acetonide (TA) is used for the treatment of diabetic macular edema and other vitreoretinal diseases. Vascular endothelial growth factor (VEGF) plays a key role in regulating vascular permeability associated with macular edema. We investigated the effect of TA on the expression of VEGF mRNA and protein induced by interleukin-1 beta (IL-1b) and hypoxia in cultured rat Müller cells.


METHODS
Müller cells were isolated from removed eyeballs of 40 rats. Total RNA was prepared from Müller cells stimulated by IL-1b or hypoxia, in the absence or presence of TA, and then was subjected to Northern blot analyses. The amount of VEGF protein in the culture medium was measured by enzyme-linked immunosorbent assay (ELISA). The stability of RNA was determined by actinomycin D decay assay. Reporter construct, consisting of the VEGF promoter-luciferase gene, was transiently transfected into Müller cells for luciferase assays.


RESULTS
Stimulation of Müller cells by either IL-1b or hypoxia induced VEGF mRNA expression. Pretreatment of cells with TA efficiently suppressed VEGF induction by IL-1b but not by hypoxia. ELISA showed that TA significantly reduced the production of VEGF protein from IL-1b-stimulated cells. RNA decay assays and promoter analysis of the VEGF gene indicated that TA inhibited the IL-1b-mediated increase in VEGF gene expression at the transcriptional level.


CONCLUSIONS
TA suppressed VEGF expression induced by IL-1b in Müller cells at the transcriptional level. Our data sustained the clinical effect of TA for diabetic macular edema and suggested an important role of TA for the suppression of the VEGF gene expression in ocular tissues.
Itakura
Hirotaka
H
Department of Ophthalmology, Gunma University Graduate School of Medicine, 3-39-15 Showa-machi, Maebashi, Gunma, 371-8511, Japan. itakurah@med.gunma-u.ac.jp
Akiyama
Hideo
H
Hagimura
Norikazu
N
Doi
Hiroshi
H
Tanaka
Toru
T
Kishi
Shoji
S
Kurabayashi
Masahiko
M
D000818:Animals; D015152:Blotting, Northern; D002478:Cells, Cultured; D015342:DNA Probes; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation / Q000187:drug effects*; D005938:Glucocorticoids / Q000494:pharmacology*; D000860:Hypoxia / Q000378:metabolism; D053583:Interleukin-1beta / Q000494:pharmacology*; D009457:Neuroglia / Q000187:drug effects* / Q000378:metabolism; D010957:Plasmids; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection; D014222:Triamcinolone Acetonide / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000378:metabolism
D015342:DNA Probes; D005938:Glucocorticoids; D053583:Interleukin-1beta; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; D014222:Triamcinolone Acetonide