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Ashish Tandon, Rangan Gupta, Ajay Sharma, Yasaman J. Hemmat, Rajiv R. Mohan; Inhibition of PRK-induced Corneal Haze By Trichostatin-A Involves Epigenetic Modification. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1988.
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© ARVO (1962-2015); The Authors (2016-present)
Recently we reported significant inhibition of photorefractive keratectomy (PRK)-induced haze in rabbit cornea by Trichostatin-A (TSA), a histone deacetylase inhibitor. This study investigated whether the anti-fibrotic effects of TSA on cornea are due to epigenetic modifications of TGFβ.
Human corneal fibroblasts (HSF) and New Zealand White rabbits (2.5-3.0kg) were used. Fibrosis in HSF was induced with TGFβ (1ng/ml) using serum-free conditions and rabbit cornea with -9.0 diopter PRK with an excimer laser. Doses of TSA showing significant inhibition of corneal fibrosis were used for in vivo and in vitro experiments. Slit lamp biomicroscopy, biochemical assays (TUNEL, trypan blue, histone acetyltransferase, histone deacetylase), real-time PCR, western blotting, and immunocytochemistry techniques were used to examine epigenetic modifications.
TGFβ1 induced phenotypic changes, increased extracellular matrix synthesis and assembly of actin filaments (αSMA, fibronectin and phalloidin; 8-10±2.1 fold; p<0.01-0.001), and TSA significantly inhibited the levels of tested proteins and mRNA in HSF (46-83%; p<0.001) and rabbit corneal sections (73%; p<0.001). HSF treated with TGFβ1 reduced histone H3 acetylation whereas TSA treatment to TGFβ1-stimulated HSF showed dose-dependent restoration of acetylated histone H3 levels. Quantification studies are underway.
This study suggests that epigenetic regulation plays an important role in corneal fibrosis. Understanding the molecular hierarchy of events with respect to reactivation of transcription and reversal of histone modification will be critical for understanding and developing mechanism-based anti-fibrotic treatments for corneal scarring.
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