IL-31–IL-31R interactions negatively regulate type 2 inflammation in the lung

Interleukin (IL) 31Rα (glycoprotein 130–like monocyte receptor and glycoprotein 130–like receptor) heterodimerizes with oncostatin M receptor β to bind IL-31, a cytokine expressed preferentially by CD4⁺ T helper type 2 (Th2) cells. However, the functions of IL-31–IL-31R signaling in immune regulation remain unknown. Here, we identify a novel role for IL-31R in limiting type 2 inflammation in the lung. After intravenous injection of Schistosoma mansoni eggs, IL-31Rα^−/− mice developed severe pulmonary inflammation, characterized by an increase in the area of granulomatous inflammation, increased numbers of resistin-like molecule α⁺ cells, and enhanced collagen deposition compared to WT counterparts. In vitro, macrophages generated from IL-31Rα^−/− mice promoted enhanced ovalbumin-specific CD4⁺ T cell proliferation and purified naive CD4⁺ T cells from IL-31Rα^−/− mice exhibited enhanced proliferation and expression of Th2 cytokines, identifying a T cell– and macrophage-intrinsic regulatory function for IL-31R signaling. In contrast, the generation of CD4⁺ T cell–mediated Th1 responses were normal in IL-31Rα^−/− mice, suggesting that the regulatory role of IL-31R signaling is limited to type 2 responses. Together, these data implicate IL-31R signaling as a novel negative regulatory pathway that specifically limits type 2 inflammation.