LAUSR

Group-2 innate lymphoid cells (ILC2s) are a critical innate source of type-2 cytokines in allergic inflammation. Although ILC2s are recognized as a critical cell population in the allergic inflammation, the regulatory mechanism(s) of ILC2s are less well understood. Here, we show that Regnase-1, an immune-regulatory RNase that degrades inflammatory mRNAs, negatively regulates ILC2 function, and that IkB kinase (IKK) complex-mediated Regnase-1 degradation is essential for IL-33- and IL-25-induced ILC2 activation. ILC2s from Regnase-1AA/AA mice expressing a Regnase-1 S435A/S439A mutant resistant to IKK complex-mediated degradation, accumulated Regnase-1 protein in response to IL-33 and IL-25. IL-33- and IL-25-stimulated Regnase-1AA/AA ILC2s showed reduced cell proliferation and type-2 cytokine (IL-5, IL-9, and IL-13) production and increased cell death. In addition, Il2ra and Il1rl1, but not Il5, Il9, or Il13, mRNAs were destabilized in IL-33-stimulated Regnase-1AA/AA ILC2s. In vivo, Regnase-1AA/AA mice showed attenuated acute type-2 pulmonary inflammation induced by the instillation of IL-33, IL-25, or papain. Furthermore, the expulsion of Nippostrongylus brasiliensis was significantly delayed in Regnase-1AA/AA mice. These results demonstrate that IKK complex-mediated Regnase-1 degradation is essential for ILC2s-mediated type-2 responses both in vitro and in vivo. Therefore, controlling Regnase-1 degradation is a potential therapeutic target for ILC2-contributed allergic disorders.