Description
Luxturna was the first approved adeno-associated virus (AAV)-based gene therapy, however, patients exhibit progressive retinal atrophy following treatment. One proposed cause is a transgene-specific cytotoxic CD8+ T cell response. Notably, this is not observed in mice suggesting they lack comparable CD8+ responses, limiting their ability to recapitulate clinical observations. This project therefore aims to understand cytotoxic T cell trafficking into the retina and effector function during AAV delivery.
B10.D2 mice received intravitreally injected AAV expressing enhanced Green Fluorescence Protein (eGFP). Activated eGFP-specific CD8+ T cells from Just EGFP Death Inducing (JEDI) mice were adoptively transferred into AAV2-recipients or Cx3Cr1GFPxB10.D2 mice. Post-mortem retinas were analysed using multiplexed immunohistochemistry and spatially analysed using Aivia.
Cx3cr1GFPxB10.D2 mice showed no loss of GFP+ microglia following transfer of GFP specific T cells. In contrast, AAV2 injected recipients exhibited significant loss of GFP+ retinal cells. 3D analysis confirmed entry of CD8+ T cells into AAV-treated retinas of adoptive transfer-recipients and direct interactions with GFP-expressing cells.
This demonstrates that transgene specific CD8+ T cells infiltrate the retina and target antigen presenting retinal cells after AAV delivery, but not when the same antigen is endogenously expressed under healthy conditions, highlighting the critical role of tissue inflammatory context in retinal cytotoxic immune responses.
Lay Abstract
Background:
Luxturna is a gene therapy treating a form of inherited retinal degeneration. It is injected into the eye to replace a missing gene to improve vision, however, some patients experience gradual damage to their retina after treatment. One explanation is that the immune system mistakenly attacks retinal cells that have received the gene therapy.
Methods:
We aimed to understand how these immune cells enter the retina and damage cells after gene therapy. Mice received gene therapy carrying a green marker into the eye, allowing retinal cells to be easily identified. We then introduced immune cells trained to recognise this green marker and tracked how they behaved.
Outcomes:
When mice are born with the green marker in their eyes, the introduced immune cells caused no damage. However, when it was delivered by gene therapy, immune cells entered the retina and destroyed the retina that had received the marker. Imaging confirmed that these immune cells directly interacted with and killed retinal cells after treatment.
This showed that gene therapy changes the retinal environment and allows detrimental immune responses. Understanding this process is important for improving long term safety of gene therapies for eye diseases.
| Lay Title | Gene therapy in the eye can trigger the immune system to damage treated retinal cells |
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| Role | PhD Student |