IL17A and inflammation: Activated IL-17 also activates epithelial cells, fibroblasts, and macrophages, releasing granulocyte-macrophage colony-stimulating factor (GM-CSF), TNF-α, PGE2, IL-1, IL-6, and IL-8, which are not only involved in airway remodeling but also promote further exacerbation of airway inflammation [23].