Effects of 5-aza-2'-deoxycytidine and trichostatin A on high glucose- and interleukin-1β-induced secretory mediators from human retinal endothelial cells and retinal pigment epithelial cells

PURPOSE We aimed to elucidate the effects of two epigenetic inhibitors, 5-aza-2'-deoxycytidine (5-aza-dC) and trichostatin A (TSA), on several key secretory mediators of diabetic retinopathy (DR) in human retinal endothelial cells (HRECs) and human retinal pigment epithelial (HRPE) cells treated with high glucose or interleukin-1β (IL-1β). METHODS HRECs and HRPE cells were incubated in 30 mM D-glucose or 10 ng/ml IL-1β with or without the presence of various concentrations of 5-aza-dC or TSA. The production of pigment epithelium derived factor (PEDF), vascular endothelial cell growth factor (VEGF), intercellular cell adhesion molecule-1 (ICAM-1), IL-1β, and matrix metalloproteinase 2 (MMP2) was evaluated at the mRNA and protein levels using real-time PCR and enzyme-linked immunosorbent assay (ELISA), respectively. RESULTS In the 30 mM D-glucose and the 10 ng/ml IL-1β condition, the expression of VEGF, ICAM-1, IL-1β, and MMP2 was induced in the HRECs and the HRPE cells. PEDF was downregulated in the HRPE cells but upregulated in the HRECs. However, the PEDF-to-VEGF ratio, which is thought to be critical in DR, was downregulated in both cell types. 5-aza-dC dose-dependently alleviated VEGF, ICAM-1, IL-1β, and MMP2 and reversed PEDF or the PEDF/VEGF ratio in both cell types. TSA had similar effects as 5-aza-dC on the target mediators. However, ICAM-1 production was aggravated in the HRECs while remaining unchanged in the HRPE cells after TSA was administered. CONCLUSIONS Our results demonstrated that 5-aza-dC and TSA enhance the protective PEDF and the PEDF/VEGF ratio and ameliorate the adverse effects of diabetic stimuli in vitro, suggesting that these two drugs may be of potential therapeutic value in DR.