The development of a therapy for retinitis pigmentosa based on the combined administration of the two products encoded by the nucleoredoxin like-1 gene

Abstract

Purpose : Retinitis pigmentosa is an inherited retinal degeneration that processes from the death of rods followed by dysfunction and degeneration of cones. The nucleoredoxin-like 1 (NXNL1) gene encodes for two different proteins by alternative splicing: the trophic factor Rod-derived cone viability factor (RdCVF) and the long form, the thioredoxin (RdCVFL). RdCVF acts by stimulating aerobic glycolysis to sustain cone outer segment renewal and RdCVFL protects the cones against hyperoxia. In order to translate this promising therapy towards the clinic independently of the causative gene, we have evaluated the therapeutic benefit of delivering both products of the NXNL1 gene by subretinal injection with an AAV vector targeting retinal pigmented epithelial cells and cones in a mouse model of the disease.

Methods : Unilateral subretinal delivery of AAV-RdCVF/RdCVFL as compared to AAV-GFP and sham were performed in rd10 mice (7-9 animals per group) at 15 days post-natal. The visual acuity test was carried out from 30 days to 55 days post-natal. Eye fundus pictures are collected to control the GFP expression. Following the sacrifice of rd10 animals, eyes were collected and used for automated counting after the labelling of cones with peanut agglutinin using e-conome. The quality control of AAV particles was made by transmission electron microscopy and completed by silver staining gel electrophoretic analysis.

Results : The kinetics of the loss of visual acuity was statistically significantly retarded after injection of AAV-RdCVF-RdCVFL in 3 independent experiments. The results were validated by the increase of cone density. We have validated the quality of the viral productions by measuring the percentage full to empty particles using electron microscopy (90%). Poly-unsaturated fatty acids lipids of the external segment of photoreceptors are essential for phototransduction, prone to oxidation. We show a reduced amount of malondialdehyde (MDA), a marker of lipid peroxidation, in animals after the injection of AAV-RdCVF-RdCVFL compared to AAV-RdCVF demonstrating the additional protective effect of RdCVFL on cones, strengthening the interest to combine RdCVF and RdCVFL.

Conclusions : Our results demonstrate that this treatment will likely be successful in preserving central vision in patients suffering of retinitis pigmentosa in the near future.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.