Spondyloarthropathies are a group of diseases, including acute anterior uveitis (AAU), in which tissue resident T cells are proposed as critical to disease pathogenesis. However, this view challenges the classical view of the eye as an immune privileged environment. Identification of resident T cells within and surrounding the anterior uvea would support their involvement in AAU pathogenesis.
To identify T cells, uveas were separated from post-mortem human eyes with no history of eye disease (n=3), dissected into iris, ciliary body and choroid, digested and assessed by scRNAseq and flow cytometry. Spatial location was assessed on formalin-fixed paraffin-embedded eye sections by multiplexed immune-fluorescent imaging on the Cell DIVE platform.
scRNAseq identified discrete T cell clusters within the ciliary body and choroid. These clusters were further characterised by flow cytometry. CD3+, CD69+ and CD45RO+ populations were identified, consistent with a resident memory phenotype. Immune-fluorescent imaging further confirmed the presence of CD3+ cells with a resident phenotype and their localisation outside of CD31+ blood vessels.
In this study, we demonstrate that resident T cells populate the healthy human eye. This challenges the dogma that the eye is devoid of lymphocytes and supports involvement of T cells in the pathogenesis of auto-inflammatory AAU. Further work is planned to investigate what sub-populations of T cells expand in AAU.