Dihydroquercetin Suppresses Cigarette Smoke Induced Ferroptosis In The Pathogenesis Of Chronic Obstructive Pulmonary Disease By Activating Nrf2-Mediated Pathway

Objective:Chronic obstructive pulmonary disease(COPD)is a treatable and preventable disease characterized by persistent respiratory symptoms and airflow limitation.The occurrence and development of COPD is mediated by a variety of factors,including inflammation,oxidative stress,apoptosis and ferroptosis.Dihydroquercetin(DHQ)is a kind of flavonoid with strong anti-inflammatory and anti-oxidant effects.However,its protective activity against cigarette smoke extract(CSE)induced ferroptosis and its underlying mechanisms still remain unclear.The present study was conducted to investigate the protective role of DHQ in the pathogenesis of COPD.Methods:COPD mice model was established by cigarette smoke exposure combined with intraperitoneal injection of CSE.During the modeling process,the mice were intraperitoneally injected with DHQ daily.HBECs were cultured with CSE with or without the pretreatment of DHQ(40,80 μM)or ML385(10 μM).The cell viability was accessed by cell count kit 8(CCK-8)kit.The content of malondialdehyde(MDA)and superoxide dismutase(SOD)were determined by MDA and SOD assay kits respectively and reactive oxygen species(ROS)generation was detected by DCFH-DA assay.Protein expression levels of glutathione peroxidase 4(GPx4),solute carrier family 7 member 11(SLC7A11),and nuclear factor erythroid 2-related factor 2(Nrf2)were measured by western bolt.The lipid peroxidation was determined by C11-BODIPY staining.Transmission electron microscopy was used to observe the morphological features of mitochondria.Results:Treatment of DHQ significantly elevated ferroptosis related protein(SLC7A11 and GPx4)expression in vivo and in vitro.The excessive MDA and ROS production and depleted SOD activity induced by CSE could reverse by DHQ.DHQ could notably reduce the increased lipid peroxidation induced by CSE in HBECs.Besides,treatment of DHQ could attenuate morphological changes of mitochondria caused by CSE.Moreover,we also found that DHQ can increase the levels of Nrf2 in a concentration-dependent manner in COPD mice model and CSE treated HBECs.Additionally,after administering a Nrf2 specific inhibitor,ML385 in HBECs,the protective effect of DHQ has been significantly blocked.Conclusion:Our results show that DHQ could significantly reverse the ferroptosis induced by CS or CSE both in vivo and in vitro via Nrf2 depended signaling pathway.