Abstract
Purpose :
Neovascular age-related macular degeneration (nAMD), involves the progressive loss of vision due to choroidal neovascularisation (CNV). The choroid is known to harbor resident immune cell populations, which are thought to play a role in nAMD pathology. Recent evidence has suggested that unconventional T-cells such as the gamma delta (γδ) subsets are present in these tissues, although their specific involvement in CNV is unclear. Here, we evaluated the abundance and phenotypic profile of γδ T-cell subsets during laser-induced CNV in mice. We also investigated whether selective ablation the γδ T-cell receptor modulates the extent of pathology in CNV.
Methods :
CNV was induced in 10–12-week-old C57Bl6/J mice by laser photocoagulation, producing 4 lesions/eye (Micron III, 350mW, 532nm, 70ms). Choroidal tissue was collected and processed for flow cytometry at 2- and 7- days post-CNV, with unlasered mice serving as controls (n=7-9/ cohort). Spectral flow cytometry for 19 cell surface markers was then used to characterise T-cell subsets in the choroidal samples (Cytek Aurora), with an emphasis on γδ T-cells. To evaluate their role in CNV, lesion size was quantified between wildtype and gamma delta knockout (TCRδ-/-) mice using fluorescein angiography (FA), at 7-days post CNV (n=15).
Results :
Flow cytometry revealed the presence of T-lymphocytes in choroids of healthy mice, and their total proportions were increased 2-days post-CNV (p=0.006). A population of γδ T-cells was observed within the choroid of control and CNV groups, which did not vary significantly in proportion across the time course (p=0.051). However, while γδ T-cells in control mice were predominately of the Vγ1 subtype, both Vγ1 and Vγ4 subsets were detected in the CNV groups. Although there was no change in the proportion of Vγ1 γδ cells, there was a significant increase in Vγ4 cells 2 days post-laser treatment (p=0.042). In conjunction, FA analysis revealed an increase in CNV lesion size 7 days post laser among TCRδ-/- mice, compared to controls (p=0.005).
Conclusions :
The current study indicates that CNV induces a shift in the composition of γδ T-cell subsets of the choroid, and suggests a protective role for these cells in CNV pathology. As such, the potential augmentation of γδ T-cell function could construe a potential avenue for ameliorating pathology and vision loss in nAMD.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.