Abstract
Purpose :
Leber congenital amaurosis (LCA) is a group of retinal diseases characterized by severe visual impairment. One form of LCA is caused by mutations in the RPE65 gene, which encodes the retinal pigment epithelium (RPE) isomerase. The aim of this study is to evaluate an impact of RPE65 deficiency on retinal glial cells response.
Methods :
Retinas of middle-aged normal and RPE65 mutant dogs were processed for morphologic evaluation and immunohistochemistry using cell-specific markers.
Results :
In RPE65 mutant dogs, active migration of IBA1+/CD18+ microglia and GFAP+/VIM- astrocytes toward the outer retinal layers was found in peripheral, mid-peripheral and to a lesser extent in central part of superior retina. We further observed disease associated changes in expression pattern of glutamine synthetase (GS) and excitatory amino acid transporter 1 (EAAT1), the key proteins in glial-neuronal transmitter recycling. In normal retina GS and EAAT1 are expressed in Müller cell bodies and processes. In RPE65 deficient retinas expression of GS and EAAT1 was significantly reduced in Müller cell processes in the ONL that extended toward the OLM. Furthermore, we observed in Müller glia induction of axon guidance receptor ROBO1 expression and upregulation of type III intermediate filament protein VIM, indicating an activation of gliotic responses. Interestingly, the disease associated changes in ROBO1 expression were accompanied by upregulation of its ligand SLIT2 in PAX6+ amacrine cells.
Conclusions :
The study data provides new insight into RPE65 disease pathology and can be applied to the interpretation of outcomes of retinal gene therapy in animal models and humans.
This is a 2021 ARVO Annual Meeting abstract.