Effect of brilliant Blue-G on cellular stress response in retinal pigment epithelial cells: In vitro

Abstract

To assess the cellular stress evoked by exposure of Brilliant Blue-G (BBG), adult retinal pigment epithelial (ARPE-19) cells were treated with various dilutions of BBG in balanced salt solution plus (BSS-PLUS) with and without endoillumination (Alcon Constellation Vision System). The treatments lasted for acute periods of 2 and 5 min. MTT and presto blue assays were performed to assess the changes in cell viability; reactive oxygen species (ROS) production was quantified by DCFDA (dichlorofluorescin diacetate) assay, and the expression of inflammatory stress and endoplasmic reticulum (ER) genes were quantified by qPCR. We observed no reduction in cell viability at 2 min of dye treatment with and without endoillumination while at 5 min exposure, a reduction in cell viability at all concentrations of the dye was observed compared to control. Though there was an increase in ROS with endoillumination, it was insignificant. There was no change in the mRNA expression of TNF-α while that of GRP78, and inflammatory genes viz. IL-8, IL-1β showed a significant increase at 0.5 mg/ml dye with endoillumination. BBG reduced cell viability with increasing concentration and time. The undiluted concentration of the dye results in inflammatory stress compared to the diluted formulations.Interestingly, increased GRP78 at undiluted concentration indicates a protective response in cells exposed to light. However, further studies are needed to evaluate the effect of cellular stress on the visual outcome. We infer that the commercially available formulation of BBG is safe for the RPE, at the recommended dose for a short duration however its toxicity to other cell types need to be addressed.