The Study On The Role And Mechanisms Of PM2.5 In Nasal Epithelium Injury

PM2.5 is one of the main harmful environmental pollutants,which can damage the nasal mucosal epithelial barrier and is closely related to the occurrence and development of allergic rhinitis,chronic sinusitis and other diseases.The nasal mucosal epithelial barrier is the first defense barrier between gases and the respiratory tract and is vulnerable to disruption by harmful stimuli,such as pathogenic microorganisms and PM2.5.Current studies have shown that cell death caused by PM2.5 includes autophagy,necrosis,apoptosis,pyroptosis and ferroptosis.Among them,ferroptosis is a newly found regulatory cell death mode through iron-dependent lipid peroxidation,which is involved in a variety of diseases such as nervous system diseases,intestinal diseases,kidney injury,and respiratory diseases.Studies have shown that ferroptosis plays an important role in PM2.5-induced endothelial cell and human bronchial epithelial cell injury.However,the role and mechanism of ferroptosis in PM2.5-induced nasal epithelial injury are still unclear.As a core molecular pathway to regulate cell and body homeostasis,autophagy plays an important role in PM2.5-induced airway injury and can regulate ferroptosis.However,whether autophagy is involved in PM2.5-induced nasal epithelial cell injury by regulating ferroptosis remains to be further studied.Methods:In order to verify the important role of ferroptosis in PM2.5-induced nasal mucosal epithelial injury and further explore its possible mechanism,this study mainly constructs in vitro and in vivo models.In vitro,CCK8 kit was used to investigate the cytotoxicity of PM2.5 organic extracts on human nasal epithelial cell line(HNEPCs).The intracellular iron content,ROS release and lipid peroxidation levels were detected by related detection kits.The expression levels of autophagy and ferroptosis proteins were detected by Western blot.In vitro,HE staining and PAS staining were used to detect the pathological changes and mucus secretion of the nasal mucosal epithelium.ELISA was used to detect the levels of inflammatory cytokines in nasal lavage fluid.Results:1.In vitro experimentsPM2.5 exposure caused oxidative stress,unstable iron accumulation,and lipid peroxidation in HNEPCs.In addition,PM2.5 significantly inhibited the expression levels of x CT,GPx4,FTH1 and FTL in HNEPCs.The ferroptosis inhibitors deferoxamine(DFO)and ferrostatin(Fer-1)significantly reversed the PM2.5 toxicity in human nasal epithelial cells(HNEPCs).Mechanistically,PM2.5 exposure initiated AMPK-mediated autophagy and resulted in ferroptosis in HNEPCs.Autophagy inhibitor 3-MA significantly ameliorated PM2.5-induced HNEPCs cell death,oxidative stress,labile iron accumulation and lipid peroxidation,and down-regulated the expression of x CT,GPx4,FTH1 and FTL.In addition,AMPK inhibitor Compound C(CC)and si RNA-AMPKα inhibited PM2.5-induced autophagy activation and ferroptosis.2.In vivo experimentsFer-1 can reduce nasal mucosal epithelial damage and mucus secretion in mice exposed to PM2.5.In addition,both 3-MA and CC significantly improved PM2.5-induced nasal mucosal epithelial damage and pro-inflammatory cytokines such as IL-6,IL-1β and TNF-α production.Moreover,CC significantly inhibited PM2.5-induced autophagy activation in mouse nasal epithelial cells and reversed PM2.5-induced downregulation of GPX4 and FTH1.Conclusions:In summary,the present study demonstrated that PM2.5 causes acute nasal epithelial injury by promoting ferroptosis of HNEPCs through activation of AMPK-mediated autophagy;therefore,AMPK may be a potential therapeutic target for PM2.5-induced nasal epithelial injury.