AHR and asthma: The strong association between the co‐expression of IL‐13 and IL‐5 with asthma or wheeze reflects the functionality of the two cytokines, which has been demonstrated in mouse aeroallergen challenge models, where airway remodelling, airway inflammation, and AHR were dramatically reduced after the knockout of either IL‐13 or IL‐5 41, 42.