IL-23 drives uveitis by acting on a novel population of resident ocular T cells

Abstract

Purpose : Acute anterior uveitis is a frequent ocular co-morbidity strongly associated with the Spondyloarthropathies (SpA), a group of chronic inflammatory diseases affecting the joints, skin, and gut of patients. Pathology at these different anatomical sites is driven by local resident populations of interleukin (IL)-23 responsive lymphoid cells. We therefore sought evidence for a resident population of IL-23 responsive cells within the ocular entheseal tissues.

Methods : B6(Cg)-Tyrc-2J/J (albino) and C57BL/6J IL-23R-eGFP reporter mice were used to determine tissue localization and phenotype of resident CD3+ populations in normal mouse anterior uvea. Perfused eyes were optically cleared for whole tissue Ce3D Lightsheet imaging. Flow cytometry (FACS) and ImageStream®X MK II analysis was performed to immunophenotype cells. To evaluate IL-23 responsiveness, C57BL/6J or Rag2-/- mice received intravitreal (IVT) injection of ShH10 adeno-associated virus (AAV) encoding an IL-23 hyperkine. Clinical assessment (Fundus & OCT) was performed to determine onset of clinical inflammation. Dissected anterior and posterior uvea were processed for FACS enumeration of CD45+ infiltrate.

Results : Ex vivo tissue imaging of naïve eyes reveals CD3+IL-23R+ cells are located across multiple tissues of the anterior uvea, including the sclera, iris, and ciliary body. FACS identifies 50-100 cells/eye, and defines the naive phenotype as CD3+CD4-CD8-TCRγδ+RORγt+IL-23R+. In vivo, IL-23 over-expression elicits clinical inflammation in anterior and posterior segments of the eye by day 12. FACS confirms a significant increase in CD45+CD3+ cell number in anterior and posterior compared to eyes receiving control ShH10 vector. Ex vivo stimulation of anterior uvea shows increased IL-17A production by CD3+γδTCR+ from cells following IL-23 overexpression. ShH10-mediated IL-23 expression does not elicit clinical inflammation or infiltration of CD45+ cells in Rag2 deficient mice.

Conclusions : A novel population of ocular T cells defined by CD3+CD4-CD8-γδTCR+IL-23R+ expression resides within the anterior uvea of the mouse eye. Localised ocular cytokine expression demonstrates that resident IL-23R+ IL-17A producing cells are both necessary and sufficient to drive uveitis in response to IL-23. Further characterization of this population is warranted.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.