Retinoic Acid Neutralizes the Effects of Herpes Simplex Virus Type 1-Infected Cell Protein 0 (ICP0) in Retinal Pigment Epithelial Cells

Abstract

Background: Herpes simplex virus (HSV) infection of the cornea, uvea, and retina is the leading infectious cause of blindness worldwide. This study examined the effects of retinoic acid (RA) on the protein levels of interleukin (IL)-17A and IL-23 cytokines with known proinflammatory effects and toll-like receptor 3 (TLR3) messenger RNA (mRNA) expression in retinal pigment epithelial (ARPE-19) cells treated with HSV-1infected cell protein 0 (ICP0). Methodology: We used 3-[4.5-dimethylthiazol-2-yl]-2.5-diphenyl tetrazolium bromide assay to calculate the half maximal inhibitory concentration (IC50) doses of RA and ICP0 in ARPE-19 cells. At the end of 24 hours, protein levels of IL-17A and IL-23 were analyzed using enzyme-linked immunosorbent assay. TLR3 mRNA expression levels were also calculated using reverse transcription-polymerase chain reaction (RT-PCR). Results: RA administration decreased IL-17A levels, which were elevated by ICP0. The IL-23 levels were similar between the ICP0-treated and control groups, but the difference was significant between the ICP0treated group and RA+ICP0 combination. These results showed that RA can significantly increase IL-23 levels in the presence of ICP0. Although ICP0 dramatically increased TLR3 mRNA expression compared with that in the control group, the RA+ICP0 combination returned TLR3 mRNA expression to a level similar to that in the control group ( P = 0.419). Conclusions: RA may potentially neutralize HSV-1 ICP0 negative effects in ARPE-19 cells.