LKB1 prevents ILC2 exhaustion and lung cancer metastasis

Group 2 innate lymphoid cells (ILC2s) mediate type 2 immune responses involved in anti-helminth immunity, allergic inflammation, and metabolic homeostasis. Recently, they have emerged as key players in regulating tumor immunity. The tumor suppressor liver kinase B1 (LKB1) inactivating mutations is associated with a variety of human cancers, but the role of LKB1 in ILC2 function and ILC2-mediated tumor immunity remains unknown. Here, we show that LKB1 is required for mature ILC2 survival. Ablation of LKB1 in ILC2s results in impaired proliferation and a marked decrease in type 2 cytokine production upon activation, accompanied with the expression of exhaustion signature genes and reduced cellular metabolism, which promote the development of lung melanoma metastasis. In addition, LKB1 deficiency leads to a marked increase of programmed cell death protein-1 (PD-1) expression in ILC2s through activation of nuclear factor of activated T cells (NFAT) pathway. Blockade of PD-1 can restore type 2 cytokine production in LKB1-deficient ILC2 and reverse its exhaustion state, leading to enhanced antitumor immune responses in vivo. Together, our results reveal that LKB1 retrains ILC2 exhaustion state to maintain immune homeostasis and their antitumor immunity.