Th17 cell and IL-17A is proven to promote the secretion of neutrophil chemokines by epithelial cells, to exacerbate AHR by directly promoting airway smooth muscle contraction, and to enhance neutrophilic airway inflammation and Th2 cell-mediated eosinophilic airway inflammation in a murine asthma model [36–38]. The gene discussed is IL17A; the disease is inflammatory response.