A Mouse Model of Retinal Vasculopathy with Cerebral Leukodystrophy

Abstract

Purpose : Retinal vasculopathy with cerebral leukodystrophy (RVCL) is a rare and devastating autosomal dominant microvascular disease. Patients with RVCL begin to develop retinal and cerebral ischemia in the fifth decade of life, ultimately leading to blindness, dementia, and premature death. Retinal findings include capillary obliteration, microaneurysms, branch retinal artery occlusions, ischemia and secondary proliferative retinopathy, similar to patients with other retinal vascular diseases including diabetic retinopathy. Here, we report the development of a mouse model of RVCL to better understand the role of endothelial dysfunction in RVCL.

Methods : We used CRISPR/Cas9 to generate knock-in mice with Trex1-T235fs, a mutation analogous to TREX1 V235fs in humans with RVCL. Heterozygous Trex1-T235fs knock-in mice and wild-type (WT) littermate control animals were exposed to the oxygen induced retinopathy model. On postnatal day 17, mice were humanely sacrificed and perfused with high molecular weight fluorescein dextran. The neuroretina was flatmounted for quantification of avascular area using ImageJ software. Phosphorylation of gH2AX, a marker of the DNA damage response, was assessed by Western blot in mouse embryonic fibroblasts from the T235fs mice and in lymphoblasts from RVCL patients.

Results : Twelve Trex1-T235fs mice and 11 WT littermates from 4 litters were included in the study. Mean avascular area of Trex1-T235fs homozygous mice was larger than mean avascular area of WT mice (12.43 v 10.05mm², p=0.0012). No statistically significant difference was found in weight. Phosphorylation of γH2AX was diminished in both RVCL patient lymphoblasts and in mouse embryonic fibroblasts from the T235fs mice, suggesting a potential role for an impaired DNA damage response in RVCL disease pathogenesis.

Conclusions : We generated the first mouse model of retinal microvascular disease that mimics retinal ischemia observed in RVCL. Further studies are underway to define the localization of Trex1 within the retina and to characterize a potential role for γH2AX and the DNA damage response in RVCL disease pathogenesis.

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