Abstract
Purpose :
Retinal gliosis, characterized by increased numbers and morphology change of glial cells in the retina has been associated with retinal degeneration. As inherited retinal degeneration, RPE65 gene mutation associated Leber Congenital Amaurosis (LCA) leads to early onset blindness. Nevertheless, the role of gliosis has not been clearly elucidated in this disease. We seek to determine the development of reactive gliosis during the retinal degeneration in RPE65 mutant LCA disease model. In addition, the potential role of gene replacement therapy on the retinal gliosis in this retinal degenerative model was also evaluated.
Methods :
The rd12 mice, the naturally occurring animal model of LCA with the homozygous point mutation (C>T) in the RPE65 gene served as the disease model. Rd12 mice were treated by delivering the wild type copy of hRPE65 cDNA vectorized by AAV2 into subretinal space at 14 days of age. The untreated control group of rd12 mice was injected with formulation buffer. One month post injection, the retina tissue from treated rd12 mice, untreated rd12 mice and the wild type of C57BL/6 mice at the same age were harvested and immune-stained with antibodies against Glial fibrillary acidic protein (GFAP) to assess the activation of astrocytes and Müller cells.
Results :
The GFAP-positive Müller cell end-feet were observed at the ganglion cell layer in untreated rd12 mouse from 1.5 months of age and gradually increased along with age until 5 months. In contrast, density of Müller cell end-feet in the AAV2.hRPE65 treated rd12 mouse showed significantly less by quantification. In addition, astrocyte activation was also evaluated by the number of astrocyte quantitation, exhibiting a significant higher density in untreated rd12 mice than treated counterpart. To be noted, the density of both astrocytes and Müller cell end-feet are significantly higher in treated rd12 than that in wild type C57BL/6 mice.
Conclusions :
In the rd12 mouse, the degenerated photoreceptors and RPE cells elicits activation of astrocytes and Müller cell, associated with reactive gliosis. The therapy of gene replacement alleviates gliosis observed in rd12 mice. Here, we present an evaluation of reactive gliosis in LCA model. An expanded understanding of the features of gliosis in other inherited retinal degeneration or retinal injury will advance the therapeutic strategies to prevent the formation of the glial scar during the development of retinal degeneration.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.