TIGIT+ A2Ar-Dependent anti-uveitic Treg cells are a novel subset of Tregs associated with resolution of autoimmune uveitis.

Regulatory T cells (Tregs) are necessary to prevent autoimmune disease. As such, stable FoxP3 expression is required for the proper function of Tregs in the control of autoimmune disease. Different Treg subsets that utilize different mechanisms of suppression have been identified. The T-cell immunoglobulin immunoreceptor tyrosine-based inhibitory motif (TIGIT) is a relatively new Treg cell marker that has a suppressive function. We have previously identified the adenosine 2A receptor (A2Ar) as a requirement for the emergence of Tregs following resolution of autoimmune disease. Using a FoxP3-GFP-Cre reporter mouse, we identify FoxP3 and 'exFoxP3' cells, show FoxP3 and not exFoxP3 cells are suppressive. We further show FoxP3 cells express TIGIT, and are induced through A2Ar in healthy volunteers, but not patients with autoimmune disease. Furthermore, we show Tregs emerge in the target tissue at the onset of autoimmune disease in an A2Ar-dependent manner. In summary, we identify a novel subset of TIGIT⁺ Tregs that are induced through stimulation of the A2Ar.