Abstract
Purpose:
Diabetic retinopathy is best known for its microvascular complications; however, there is mounting evidence that the retinal pigment epithelium (RPE) is also involved. Advanced glycation end products (AGE), which are elevated in diabetes, have recently been shown to contribute to RPE barrier dysfunction. Alterations in protein acetylation and histone deacetylase (HDAC) activity have been shown to influence the pathogenesis of several CNS disorders. Here, we provide new evidence that the administration of Trichostatin A (TSA), a pan-HDAC inhibitor, suppresses the RPE barrier dysfunction induced by AGE in vitro and in vivo.
Methods:
Monolayers of ARPE-19 or human fetal RPE (hfRPE) cells were treated (100µg/mL) with bovine albumin (BSA) or glycated bovine albumin (gBSA) in the presence of vehicle (DMSO, 0.001%) or TSA (100nM). Transepithelial resistance (TER) was measured at 0, 4, and 6h post administration. Dutch-belted rabbits were injected (20µL) intravitreally with albumin or gBSA (1mg) in the presence of vehicle (DMSO, 0.1%) or TSA (3.0µg). Subretinal blebs (5µL PBS) were injected 2 days post intravitreal injections and observed via optical coherence tomography. Volumes and rates of resorption were calculated from following blebs for 1h.
Results:
Baseline TER in ARPE-19 and hfRPE monolayers was 57±4.4 and 291±62 milliohms, respectively. Administration of gBSA resulted in a 13% (p<0.001) and 25% (p<0.001) reduction in ARPE19 and hfRPE TER, respectively. In ARPE-19 and hfRPE monolayers co-treated with gBSA and TSA, decrease in TER was blocked. The administration of BSA or TSA alone did not significantly alter TER in either preparation. Rabbit eyes treated with BSA had a resorption rate of 11.01±2.04 ul*cm-2*hr-1 which was reduced to 2.79±0.83 ul*cm-2*hr-1 with gBSA (p<0.05, n=4). The decrease in the rate of fluid resorption induced by gBSA was blocked by co-treatment with TSA (n=4).
Conclusions:
The administration of TSA prevented RPE dysfunction induced by advanced glycation end product- both in vitro and in vivo. These data provide evidence that HDAC activity is important in the development of AGE-induced RPE dysfunction. The suppression of AGE-induced changes in RPE function in vivo by TSA supports the idea that HDAC inhibitors may be efficacious in the treatment of diabetic macular edema.
Keywords: 499 diabetic retinopathy •
701 retinal pigment epithelium