Prevention of photoreceptor cell degeneration in P23H rats after allele-specific knockdown of mutant Rhodopsin RNA expression using antisense oligonucleotide (ASO) treatment

Abstract

Purpose: Reducing mutant mRNAs using antisense technology can be a potentially effective therapeutic approach for dominantly inherited diseases. To preserve the photoreceptor cell function and structure in a rodent model of retinitis pigmentosa, P23H-1 transgenic rat, using a potent and selective allele-specific antisense oligonucleotide (ASO) inhibitor targeting the mutant rhodopsin RNA.

Methods: Transgenic rats expressing the murine P23H gene (Line 1) were administered either a mouse specific P23H ASO or non-specific Control ASO in one eye on Day 10 and Day 22 by intravitreal injection (VIT). The contralateral eye was injected with PBS and used as a comparator control. On Day 45, ERG measurements were taken followed by eye enucleation. Half of the rats were designated for retinal outer nuclear layer analysis and the other half for mRNA analysis.

Results: Using an ASO targeting the mouse mutant rhodopsin mRNA, we demonstrated a slower progression of photoreceptor degeneration and improved ERG measurements 30 days after treatment. Eyes injected with P23H ASO had a 128 ± 22% improved amplitude response (scotopic a-wave) as compared to the PBS, while the control ASO, had a 37% ± 9 difference. In addition, morphometric analysis of the outer nuclear layer showed an 18 ± 8% or 5.7 ± 7% greater thickness following treatment with P23H ASO or Control ASO, respectively. Eyes injected with the P23H ASO had greater rat rhodopsin expression, 176 ± 17% as compared to contralateral eye, consistent with the preservation of the photoreceptor cells. In the control ASO group, the rat rhodopsin expression showed very little difference from PBS eye (-2.6± 6%).

Conclusions: Allele-specific ASO mediated knockdown of mutant rhodopsin expression slowed the rate of photoreceptor degeneration and preserved the function of the photoreceptor cells of the P23H transgenic rat. Our data indicate that ASO treatment is a potentially effective therapy for autosomal dominant retinitis pigmentosa.

Keywords: 649 photoreceptors: visual performance • 696 retinal degenerations: hereditary • 702 retinitis