Preliminary Study on the Effect of Bronchial Epithelial Cell-Released Autophagosome (BA)-Induced Neutrophils on Bronchial Epithelial Cells.

OBJECTIVE

To investigate the regulatory effects of bronchial epithelial cell-released autophagosome (BA)-induced neutrophils on bronchial epithelial cells and the underlying mechanisms.

METHODS

Transmission electron microscopy and western blotting were used to identify autophagosomes in 16HBE cells stimulated with house dust mite (HDM) antigen. The production of reactive oxygen species (ROS) and neutrophil extracellular traps (NETs) was detected after BA were cocultured with human peripheral blood neutrophils. Flow cytometry was used to detect the apoptosis rate of 16HBE cells incubated with cocultured supernatant, and BAX, Bcl-2, and cleaved caspase 3 expression was detected by western blotting. In mouse acute asthma, hematoxylin and eosin (HE) staining was used to detect lung tissue injury. Apoptosis was detected by TUNEL, and neutrophils, macrophages, LC3, BAX, and Bcl-2 were detected by immunohistochemistry.

RESULTS

HDM induced the release of autophagosomes by 16HBE cells. BA induced ROS production in neutrophils by activating NF-κB signaling pathway and further promotes the formation of NETs, which induced apoptosis of 16HBE cells and was mediated by the regulation of BAX, Bcl-2, and cleaved caspase 3. In the HDM-induced mouse acute asthma, the lung tissue structure was destroyed, the content of neutrophils and macrophages increased, the macrophages showed M1 polarization, and the expression of LC3, BAX, Bcl-2, and apoptosis increased.

CONCLUSION

HDM-stimulated 16HBE cells released autophagosomes, which induced ROS production in neutrophils via NF-κB pathway activation and further promoted NET formation, ultimately leading to 16HBE cell apoptosis and lung injury in mice.