Glial Cell Responses and Gene Expression Dynamics in Retinas of Treated and Untreated RPE65 Mutant Dogs
Tatyana Appelbaum1, Evelyn Santana1, David A Smith1
1Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States.
Investigative Ophthalmology & Visual Science
|October 11, 2024
Summary
Gene therapy for RPE65 mutation in dogs shows varied efficacy. Advanced-stage retinas exhibit compensatory mechanisms, suggesting resilient cells may influence disease progression and treatment outcomes.
Area of Science:
- Ophthalmology
- Genetics
- Molecular Biology
Background:
- RPE65 gene mutations cause inherited retinal diseases.
- Previous RPE65 gene augmentation studies showed variable treatment outcomes.
- Understanding retinal status in mutant dogs is crucial for evaluating gene therapy.
Purpose of the Study:
- To investigate the molecular and cellular changes in RPE65 mutant dog retinas.
- To assess the long-term impact of RPE65 gene augmentation on retinal degeneration.
- To explore the mechanisms underlying treatment efficacy and variability.
Main Methods:
- Immunohistochemistry with cell-specific markers on retinal sections.
- Reverse transcription-quantitative PCR (RT-qPCR) for gene expression analysis.
- Comparison of treated and untreated RPE65 mutant dogs at different ages.
Main Results:
- Middle-aged mutant retinas showed gene downregulation, increased microglia, and glial responses.
- Advanced-aged treated eyes had less outer nuclear layer loss than untreated eyes.
- Both treated and untreated eyes showed persistent Müller glial stress and photoreceptor synapse loss; synaptic remodeling and inflammation were reduced in treated retinas.
Conclusions:
- A shift from pro-degenerative to compensatory mechanisms occurs in advanced-stage mutant retinas.
- Resilient surviving cells may contribute to this shift and influence disease patterns.
- These findings impact the understanding of RPE65 gene therapy efficacy and disease progression.
