Current overview of the role of neuropeptides in ILC2s and future directions.

The neural and immune systems are closely connected, and recently, their molecular mechanisms and relationships with diseases have attracted substantial attention. Particularly, it has been increasingly reported that ILC2s, which produce type 2 cytokines independent of acquired immunity, are regulated by neuropeptides such as catecholamines, acetylcholine, vasoactive intestinal peptide, neuromedins, and calcitonin gene-related peptide. However, the regulatory mechanisms in this regard are only partially understood, implying that further studies are still needed to clarify the complete mechanisms and processes. In this review, we summarize current reports on the regulatory effect of neuropeptides on ILC2s, some of which have conflicting results, possibly owing to the complexity of G-protein coupled receptors. By summarizing the current evidence, we hope to be able to identify what is currently unknown as well as what needs to be clarified in the future.