IL4 and asthma: Two major endotypes are T‐helper type 2 (TH2)‐high asthma, characterized by eosinophilic inflammation and elevated cytokines (IL‐4, IL‐5, IL‐13, IgE), and TH2‐low asthma with neutrophilic or pauci‐granulocytic profiles and corticosteroid‐resistance (Stokes and Casale 2016).