Group 2 innate lymphoid cells (ILC2s), which produce large amounts of type 2 cytokines, such as IL-5 and IL-13, in response to stimulation by IL-33 and TSLP, play an important role in asthma. ILC2s have potential as a biomarker and therapeutic target in asthma; however, the molecular characteristics of ILC2s in the patients are not yet fully understood.

Here, we developed a new single-cell analyzer incorporating live imaging technology (Live cell imaging of secretion activity, LCI-S) and applied it to the evaluation of ILC2s in patients with asthma and healthy individuals. Our analysis revealed that ILC2s derived from peripheral blood were not uniformly activated by cytokine stimulation, and we observed a diversity of ILC2s that either produced or did not produce type 2 cytokines. Notably, the percentage of type 2 cytokine-producing ILC2s was significantly higher in patients with asthma than in healthy individuals.

To further investigate the molecular characteristics of ILC2s, we performed RNA sequencing separately on type 2 cytokine-producing and non-producing ILC2s. This analysis showed that the expression of MT2A (metallothionein 2A) was significantly enhanced in type 2 cytokine-producing ILC2s. Given the crucial role of metallothionein in zinc homeostasis, we examined the zinc dynamics of ILC2s through immunostaining and found that the intracellular zinc concentration was increased in type 2 cytokine-producing ILC2s. In addition, chelation of zinc inhibited type 2 cytokine production from ILC2s.

In conclusion, patients with asthma have a higher percentage of type 2 cytokine-producing ILC2s, and zinc represent a promising new therapeutic target for the activation of ILC2s in asthma.