Researches also showed that the stimulation of bronchial epithelial cells and fibroblast by IL-17A and IL-17F caused the recruitment and activation of neutrophils which could increase the secretion of multiple cytokines, extracellular matrix proteases and elastases to trigger inflammation, airway hyperresponsiveness, and mucus squamous differentiation [15, 16]. This evidence concerns the gene IL17A and airway hyperresponsiveness.