Conventional and Non-conventional Lymphocytes exhibit dysregulated IL-22 and GM-CSF production in Acute Anterior Uveitis and Ankylosing Spondylitis

Abstract

Purpose : Underlying immune mechanisms that drive the HLA-B*27-associated inflammatory diseases acute anterior uveitis (AAU) and Ankylosing Spondylitis (AS) are incompletely understood. Recent studies have implicated RORγt-dependent immune signatures in the pathogenesis of related inflammatory diseases. In this study we developed a novel multi-parametric flow cytometry panel to identify immune dysregulation of these signatures in AAU or AS.

Methods : Peripheral Blood Mononuclear cells (PBMC) were isolated from AAU patients, AAU patients with concomitant spondylitis or healthy controls(n=9-12/group). Cells were polyclonally stimulated and subjected to flow cytometry. Antibody panels analyzed cytokine production (IFNγ, IL-17A, IL-17F, IL-22 and GM-CSF) by conventional CD4/CD8 T cells; or Mucosal-Associated Invariant T (MAIT) cells and type 3 innate lymphoid cells (ILC3). Data were analyzed in FlowJo (Tree star Inc.). Kruskall-Wallis test with Dunn’s correction for multiple comparisons was used for statistical analysis.

Results : Unexpectedly, we observed a significantly increased frequency of GM-CSF+ve CD8 T cells in AAU patients vs healthy controls, and a similar trend in GM-CSF production amongst CD4 T cells. Amongst non-conventional lymphocytes, MAIT cells exhibited markedly increased GM-CSF and IL-17A production in AAU patients with concomitant spondylitis, although not in those with AAU alone. We observed equivalent production of RORγt-dependent cytokines within the infrequent ILC3 population and found increased IL-22 production in the ILC3 population in those with AAU + AS. A significantly increased frequency of IL-22+ve CD8+ T cells was also observed in those with AAU alone.

Conclusions : Our data reveal that dysregulated RORγt-dependent cytokines GM-CSF and IL-22 are highly dysregulated in multiple circulating immune cell subsets in AAU. This is the first study to implicate 2 mucosal populations, MAIT and ILC-3 cells, in AAU and is consistent with a gut-eye axis contributing to AAU.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.