IL-1β–driven osteoclastogenic Tregs accelerate bone erosion in arthritis
Anaïs Levescot, Margaret H. Chang, Julia T. Schnell, Nathan Nelson-Maney, Jing Yan, Marta Martínez‐Bonet, Ricardo Grieshaber‐Bouyer, Pui Y. Lee, Kevin Wei, Rachel B. Blaustein, Allyn Morris, Alexandra Wactor, Yoichiro Iwakura, James A. Lederer, Deepak A. Rao, Julia F. Charles, Peter A. Nigrović
Abstract
IL-1β is a proinflammatory mediator with roles in innate and adaptive immunity. Here we show that IL-1β contributes to autoimmune arthritis by inducing osteoclastogenic capacity in Tregs. Using mice with joint inflammation arising through deficiency of the IL-1 receptor antagonist (Il1rn-/-), we observed that IL-1β blockade attenuated disease more effectively in early arthritis than in established arthritis, especially with respect to bone erosion. Protection was accompanied by a reduction in synovial CD4+Foxp3+ Tregs that displayed preserved suppressive capacity and aerobic metabolism but aberrant expression of RANKL and a striking capacity to drive RANKL-dependent osteoclast differentiation. Both Il1rn-/- Tregs and wild-type Tregs differentiated with IL-1β accelerated bone erosion upon adoptive transfer. Human Tregs exhibited analogous differentiation, and corresponding RANKLhiFoxp3+ T cells could be identified in rheumatoid arthritis synovial tissue. Together, these findings identify IL-1β-induced osteoclastogenic Tregs as a contributor to bone erosion in arthritis.