IL-1β-Mediated Signals Preferentially Drive Conversion of Regulatory T Cells but Not Conventional T Cells into IL-17-Producing Cells

Regulatory T cells (Tregs) are committed to suppressive functions. Recently, it was proposed that Tregs could produce IL-17 under proinflammatory, polarizing conditions. We studied the role of Tregs on IL-17 production in the absence of exogenous cytokines and insults. Using in vitro and in vivo approaches, we determined that under neutral conditions, simultaneous activation of Tregs and naive CD4(+) conventional T cells in the presence of APCs resulted in conversion of Tregs into IL-17-producing cells, and endogenous IL-1 beta was mandatory in this process. Mechanistic analysis revealed that the IL-1R1 was highly expressed on Tregs and that IL-1b induced marked activation of p38 and JNK, which were involved in IL-17 production. These observations could have important implications on therapeutic strategies using Tregs. The Journal of Immunology, 2010, 185: 4148-4153.