IL4 and asthma: Th2-asthma (i.e., eosinophilic asthma) is well established to play a leading role in asthma development as more than half of asthma cases have a Th2 phenotype, characterized by the secretion of high levels of IL-4, IL-5, and IL-13 by Th2 cells (Masuda et al., 2008; Hammad and Lambrecht, 2021).