Group 2 innate lymphoid cells (ILC2s) are involved in type 2 immune responses in mucosal organs and are associated with various allergic diseases in humans. Studies are needed to understand the molecules and pathways that control ILC2s.
The aim of this study was to develop a mouse model that limits the innate type 2 immune response in the lung and to investigate the immunologic mechanisms involved in regulation of lung ILC2s.
Naïve BALB/c mice were administered various toll-like receptor (TLR) agonists and exposed intranasally (i.n.) to the fungal allergen Alternaria alternata. The mechanisms were investigated using gene knockout mice and cultures of lung cells and isolated lung ILC2s.
Polyinosinic-polycytidylic acid [poly (I:C)] effectively inhibited innate type 2 response to A. alternata. Poly (I:C) promoted production of interferon (IFN)-α, -β, and -γ, and its inhibitory effects were dependent on the IFN-α/β receptor pathway. IFN-β was 100-times more potent than IFN-α at inhibiting type 2 cytokine production by lung ILC2s. Signal transducer and activator of transcription 5 (STAT5)-activating cytokines, including interleukin-2 (IL-2), IL-7, and thymic stromal lymphopoietin (TSLP), but not IL-33, promoted survival and proliferation of lung ILC2s in vitro, while IFN-β blocked these effects. Expression of the transcription factor GATA3, which is critical for differentiation and maintenance of ILC2s, was inhibited by IFN-β.
IFN-β blocks the effects of STAT5-activating cytokines on lung ILC2s and inhibits their survival and effector functions. Administration of IFN-β may provide a new strategy to treat diseases involving ILC2s.

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