Regulatory T cells and IFN-γ-producing Th1 cells play a critical role in the pathogenesis of Sjögren’s Syndrome

Sjogren’s Disease (SjD) is an autoimmune disorder characterized by progressive inflammation and destruction of both salivary and lacrimal gland leading to dysfunction, as well as extra glandular manifestations. The etiology and pathophysiology of SjD are incompletely understood. Regulatory T (Treg) cells are critical for immunological tolerance. Although Treg abnormalities have been implicated in the pathogenesis of several autoimmune diseases, their role in SjD remains ambiguous. We had previously shown that the function and development of Treg cells depend on store-operated Ca2+ entry (SOCE), which is mediated by ORAI1 Ca2+ channels and stromal interaction molecules (STIM) 1 and 2 following T cell receptor (TCR) stimulation. The ablation of SOCE in Treg cells causes SjD-like disease with increased Th1 and interferon gene expression signatures in the inflamed salivary glands of mice. Here we show enhanced Th1 gene expression signatures and type I and II interferon responses in the peripheral blood mononuclear cells (PBMCs) of human patients with SjD compared to non-SjD controls. We also identified attenuated gene expression in memory Treg cells of patients with SjD. These data from mice and human patients provide new evidence for a critical role of Treg cells and IFNγ producing Th1 cells in the pathogenesis of SjD.