Importantly, our unbiased proteomic analyses revealed that IL-9, a type 2 cytokine associated with allergic inflammation and asthma (Kaplan et al., 2015; Wilhelm et al., 2011, 2012), was the most induced protein in ILC2s costimulated with IL-33 and TL1A (Fig. 3, A and B; and Fig. S2 D). Here, IL33 is linked to asthma.