Abstract
Purpose :
Recently, we have been developing novel approaches to elucidate the early initiating factors that may underlie retinal degeneration in the pathology of dry age-related macular degeneration (AMD), and specifically its end-stage Geographic Atrophy (GA). We have discovered that altered expression of a key tight junction component, claudin-5, found at the inner blood-retinal barrier (iBRB) can lead to an atrophy-like appearance in the retinal pigment epithelium (RPE). Here, we sought to further develop novel animal models with varying claudin-5 expression levels, and iBRB integrity, to assess the damage observed and downstream changes that lead to RPE atrophy.
Methods :
We have developed three novel animal models that vary in the expression levels of claudin-5 and induce retinal degeneration within different time frames. These animal models are: 1) RNAi based inducible claudin-5 knockdown mice, 2) Cldn5+/- mice and 3) C57BL6/J mice sub-retinally injected with adeno-associated virus (AAV) vectors expressing shRNA targeting claudin-5. Each model has been characterised to determine the effect of constant claudin-5 suppression on retinal and RPE integrity at different time points in retinal degeneration. In-life imaging of mice was carried out by optical coherence tomography (OCT) to examine retinal and RPE integrity and fundus fluorescein angiography (FFA) to assess retinal blood vessel integrity. In addition, electroretinography (ERG) has been carried out to determine electrophysiological activity. Immunohistochemical, histopathological, protein and transcript analysis was undertaken following sacrifice to further characterise these models.
Results :
Assessment of these three mouse models shows that RPE atrophy progression varies depending on the level and length of time of claudin-5 expression at the iBRB and is exacerbated when addition of high cholesterol chow was provided.
Conclusions :
Each of the three models developed provide unique characteristics that enable us to determine changes that are arising at the varying stages of disease progression, which may aid us in understanding GA pathology in humans. Targeting the inner retinal vasculature by stabilising and regulating claudin-5 expression may have therapeutic potential for preventing GA onset and development.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.