The Receptor SIGIRR Suppresses Th17 Cell Proliferation via Inhibition of the Interleukin-1 Receptor Pathway and mTOR Kinase Activation

Interleukin-1 (IL-1)-mediated signaling in T cells is essential for T helper 17 (Th17) cell differentiation. We showed here that SIGIRR, a negative regulator of IL-1 receptor and Toll-like receptor signaling, was induced during Th17 cell lineage commitment and governed Th17 cell differentiation and expansion through its inhibitory effects on IL-1 signaling. The absence of SIGIRR in T cells resulted in increased Th17 cell polarization in vivo upon myelin oligodendrocyte glycoprotein (MOG 35-55) peptide immunization. Recombinant IL-1 promoted a marked increase in the proliferation of SIGIRR-deficient T cells under an in vitro Th17 cell-polarization condition. Importantly, we detected increased IL-1-induced phosphorylation of JNK and mTOR kinase in SIGIRR-deficient Th17 cells compared to wild-type Th17 cells. IL-1-induced proliferation was abolished in mTOR-deficient Th17 cells, indicating the essential role of mTOR activation. Our results demonstrate an important mechanism by which SIGIRR controls Th17 cell expansion and effector function through the IL-1-induced mTOR signaling pathway. ► SIGIRR is induced during Th17 cell lineage commitment ► SIGIRR suppresses Th17 cell effector function via inhibition of IL-1 signaling ► IL-1-induced proliferation is abolished in mTOR-deficient Th17 cells ► SIGIRR suppresses Th17 cell proliferation via inhibition of mTOR activation