IL4 and asthma: Mast cells play a key role in asthma pathophysiology and airway remodelling through the release of a plethora of cytokines (e.g. TSLP, IL-33, IL-25, IL-4, IL-13 and TGF-β) and angiogenic factors (e.g. VEGF-A), as well as other inflammatory mediators and bronchoconstrictors [64, 65].