Effects of retinoid x receptors in the progression of herpes simplex virus type-1 infection in retinal pigment epithelium cells.

AYALA PEÑA, V.B.; ARMIENTO, N.; SCOLARO, L.A.; GERMAN, O.L.

Simposio; IV Simposio Internacional de Virología Clínica y Avances en Vacunas; 2016

Age-related macular degeneration (AMD) is the main pathology leading to blindness in adult humans and has no effective treatment. Retinal-pigment-epithelial (RPE) cells have immunomodulatory properties, and their degeneration contributes in AMD development. Oxidative stress is involved in the pathogenesis, and herpes simplex virus type-1 (HSV-1) infection is currently proposed as a probable risk factor. We demonstrated that Retinoid-X-receptors (RXRs) activation protects human RPE (D407) cells from H2O2-induced apoptosis, in which RXR/PPARγ might be the mainly heterodimer involved. Since it is known that HSV-1 blocks RXRα synthesis in the macrophage promoting the host antiviral response, we assessed whether RXRs might be regulated in HSV-1 infected RPE cells. For that purpose D407 cells were infected with HSV-1 or mock, and supplemented or not with RXR agonists: LG100754 (RXR/RXR antagonist and RXR/PPARγ activator), and LG100268 (mainly RXR/RXR agonist). We analyzed virus yield by a plaque forming units assay on Vero cells; the cytopathic effect by phase microscopy; apoptosis by DAPI staining; p65NFκB expression by immunocitochemistry; and targets mRNA levels by qRT-PCR. This work shows that HSV-1 infection of D407 cells compared to the mock infected cells promoted: the rounding of cells without increasing apoptosis; an increase of p65NFκB expression in the whole cell, although the nuclear/total p65NFκB fluorescence proportion was decreased; and a decrease in PPARγ mRNA level but not in RXRα. In mock infected cells LG100754 increased and LG100268 diminished PPARγ mRNA levels, which correlates with RPE cells survival. LG100268 decreased the viral titer and the percentage of rounding cells, and promoted apoptosis in comparison with HSV-1 infected cells, unlike LG100754 that did not affect these parameters. Both RXRs agonists did not alter the PPARγ mRNA levels decrement and the p65NFκB pathway modulation induced by HSV-1 infection. Our results indicate that HSV-1 infection of RPE cells did not alter RXRα mRNA levels. As a whole, LG100268, a RXR agonist that could not activate RXR/PPARγ in our system, which increase the number of apoptotic cells, decreased the viral titer which could be a consequence of the substrate reduction for viral replication. However, a direct antiviral effect of LG100268 cannot be excluded.