Previous studies found that IL-8 level contributes to the pathogenesis of severe asthma by directly facilitating airway remodeling, increasing the migration and proliferation of bronchial smooth muscle cells (26), and inducing airway hyperresponsiveness (27), angiogenesis (28), epithelial-mesenchymal transition in the airway (29), and neutrophil recruitment. Here, CXCL8 is linked to airway hyperresponsiveness.