Calycosin Alleviates Injury in Airway Epithelial Cells Caused by PM 2.5 Exposure via Activation of AMPK Signalling

METHODS: Phospho-AMP-activated protein kinase (p-AMPK) and AMP-activated protein kinase (AMPK) were detected by western blot. Immunofluorescence staining was used to validate changes in the levels of nuclear factor kappa B (NF-кB) p65 nuclear translocation. Mice were administered intraperitoneally with calycosin one hour before anaesthesia and endotracheal instillation of PM 2.5. The extent of lung injury was evaluated in the H&E-stained lung sections. Apoptotic cells were detected by TUNEL staining. RESULTS: Administration of calycosin was increased in PM 2.5-treated B2B cells in a dose-dependent manner in vitro. Fluorescence signals from anti-NF-кB p65 were increased in nuclei of cells pretreated with calycosin. The level of p-AMPK was increased by calycosin in vitro and in vivo. After pretreatment with compound C, the inhibitory effects of calycosin on cytotoxicity, levels of inflammatory cytokines and p-AMPK, and levels of NF-кB p65 nuclear translocation were not significantly decreased in vitro or in vivo. CONCLUSIONS: Calycosin effectively decreased the release of inflammatory cytokines and alleviated injury caused by PM 2.5. These effects were mediated through activation of AMPK to suppress NF-κB signalling.