YKL-40 mediates airway remodeling in asthma via activating FAK and MAPK signaling pathway.

YKL-40 is a chitinase-like protein which was significantly elevated in asthma patients and related closely to asthma severity and airway remodeling. Airway remodeling in asthma involves complicated physical and pathological processes, including increased airway smooth muscle mass due to proliferation, migration of airway smooth muscle cells, epithelial-mesenchymal transition (EMT) and sub-epithelial fibrosis. However, the precise effect and underlying mechanism of YKL-40 in this pathological alteration remained unelucidated. In this study, we demonstrated that YKL-40 could promote asthma airway remodeling by increasing airway smooth muscle mass, inducing EMT and sub-epithelial fibrosis. Furthermore, we identified that FAK and MAPK signaling pathways are activated in the process. Inhibiting FAK or MAPK pathway could significantly ameliorate airway remodeling induced by excessive secretion of YKL-40 in vitro. and in vivo. In conclusion, this study shed light upon the effects of YKL-40 in asthma airway remodeling and provided potential novel targets in asthma patients with high YKL-40 level.