Prostones Attenuate the TNFα-Induced Breakdown of the Epithelial Barrier in Retinal Pigment Epithelial Cells

Abstract

Purpose: Tumor necrosis factor α (TNFα) is associated with eye diseases which in turn are associated with the breakdown of the blood-retinal barrier, such as diabetic retinopathy and age-related macular degeneration. TNFα causes redistribution of tight junction proteins, leading to loss of barrier function. The aim of the present study was to investigate whether the prostones, unoprostone isopropyl and its primary metabolite M1, have any effects on TNFα-induced breakdown of the blood-retinal barrier.

Methods: A human retinal pigment epithelial cell line (ARPE-19) with structural and functional characteristics of human RPE cells, was used. The effect of TNFα alone or in combination with unoprostone isopropyl or M1 was examined on transepithelial resistance (TER) and expression of tight junction proteins over a period of 96 h.

Results: TNFα (50 ng/ml) induced a time-dependent decrease in TER such that after 96 h, TER decreased to 22.2 ± 0.8% (P<0.0005) compared to the 96 h control (n=4). Unoprostone isopropyl (100 nM) and M1 (100 nM) significantly (P<0.0005) reduced the TNFα-induced decrease in TER to only 42.4 ± 0.7% and 47.8 ± 0.6% respectively (n=4). Trans-unoprostone (100 nM), an inactive isomer had no effect. Immunostaining analysis using confocal microscopy showed decreased occludin expression within the tight junctions after TNFα treatment. Unoprostone isopropyl or M1 with TNFα partially attenuated the decrease in occludin expression. Similar results were obtained for the tight junction-associated protein, zonula occludens protein 1 (ZO-1).

Conclusions: The prostones, unoprostone isopropyl and its metabolite M1, partially prevented the TNFα-induced breakdown of the outer blood-retinal barrier by reducing the loss of occludin and ZO-1 from the tight junction.

Keywords: 412 age-related macular degeneration • 695 retinal degenerations: cell biology • 701 retinal pigment epithelium