Modulation of retinal inflammation delays degeneration in a mouse model of geographic atrophy

Abstract

Geographic atrophy, the advanced form of age-related macular degeneration (AMD), is associated with increased oxidative stress and chronic inflammation. Pro-inflammatory genes, like TNF-α and IL-1β, are under the regulation of the transcription factor p65/RelA. We have previously shown that adeno-associated virus (AAV) delivery of the RelA inhibitory gene M013 blocks retinal inflammation in uveitis models. In this study, we evaluated the effects of RelA inhibition in an oxidative stress-driven geographic atrophy mouse model. We injected Sod2RPEcKO mice with rAAV, delivering either secreted GFP (sGFP control) or sGFP fused to a cell-penetrating version of the tagged M013 (sGFP-TatM013v5). Over nine months, we measured retinal function, structure, and morphological changes using electroretinography, optical coherence tomography, and fundoscopy. We quantified changes in inflammatory markers using multiplex ELISA, RT-qPCR, and immunofluorescence staining of the retinal tissue. Finally, we generated an NF-kB-luciferase reporter microglia cell line to study the impact of immune signaling changes on microglia. Mice injected with the rAAV delivering M013 had transient protection of their retinal function at 3 months. Based on ERG evaluations, the intravitreal injection of rAAV delivering sGFP-TatM013v5 significantly delayed the loss of retinal function. Furthermore, the rAAV-mediated expression of the sGFP-TatM013v5 protected photoreceptors’ outer and inner segments based on OCT and immunofluorescence analysis. Analysis of postmortem tissues showed decreased migration of immune cells towards the RPE. Retinas injected with the sGFP-M013v5 vector showed increased levels of IL-9, IL10 and LIF. Finally, adding LIF to our NF-kB reporter cell line showed decreased TNF-induced reporter expression and modulation of microglia-specific genes. Our results indicate that modulating retinal inflammation could significantly slow the degeneration associated with geographic atrophy. Specifically, inhibiting the RelA protein in the retina may offer protective effects against retinal degeneration. Additionally, we demonstrated that LIF can counteract the influence of TNF on microglial gene expression. Future research will explore the dynamic interactions between RelA and other transcription factors and the NF-kB signaling pathway in the retina as they relate to retinal diseases.