Abstract
Inappropriate immune activity is key in the pathogenesis of multiple diseases, and it is typically driven by excess inflammation and/or autoimmunity. IL-1 is often the effector owing to its powerful role in both innate and adaptive immunity, and, thus, it is tightly controlled at multiple levels. IL-1R2 antagonizes IL-1, but effects of losing this regulation are unknown. We found that IL-1R2 resolves inflammation by rapidly scavenging free IL-1. Specific IL-1R2 loss in germinal center (GC) T follicular regulatory (Tfr) cells increased the GC response after a first, but not booster, immunization, with an increase in T follicular helper (Tfh) cells, GC B cells, and antigen-specific antibodies, which was reversed upon IL-1 blockade. However, IL-1 signaling is not obligate for GC reactions, as WT and Il1r1–/– mice showed equivalent phenotypes, suggesting that GC IL-1 is normally restrained by IL-1R2. Fascinatingly, germline Il1r2–/– mice did not show this phenotype, but conditional Il1r2 deletion in adulthood recapitulated it, implying that compensation during development counteracts IL-1R2 loss. Finally, patients with ulcerative colitis or Crohn’s disease had lower serum IL-1R2. All together, we show that IL-1R2 controls important aspects of innate and adaptive immunity and that IL-1R2 level may contribute to human disease propensity and/or progression.
Authors
Katerina Pyrillou, Melanie Humphry, Lauren A. Kitt, Amanda Rodgers, Meritxell Nus, Martin R. Bennett, Kenneth G.C. Smith, Paul A. Lyons, Ziad Mallat, Murray C.H. Clarke
Figure 6
Conditional global loss of IL-1R2 in adulthood increases the GC response after immunization.
