Fig. 5.
Nonspecific inflammatory stimuli induce immune responses that promote T helper 17 (TH17) cell differentiation and production/secretion of IL-17A within immune-infiltrated airways. IL-17A variably acts upon airway epithelium, airway smooth muscle, and lung fibroblast cells to promote elevated airway remodeling and development of severe asthma. Although each of these structural cells imparts a unique effect on airway remodeling following stimulation with IL-17A, there is significant cellular cross talk between tissues. This bears potential to further enhance TH17-mediated effects surrounding airway smooth muscle hyperplasia and hypertrophy, goblet cell mucus secretions, epithelial-mesenchymal transition (EMT), extracellular matrix (ECM) deposition, fibroblast-to-myofibroblast transition (FMT), and airway hyperresponsiveness. TGF-β1, transforming growth factor-β1.