Laiyu Zhu’s research while affiliated with First Affiliated Hospital of China Medical University and other places

Background Pyroptosis is an inflammatory form of regulated necrosis that has been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). However, the role of lipid peroxidation in pyroptosis and its underlying mechanisms in COPD remain unclear. Methods In vitro, human bronchial epithelial cells (Beas-2b cells) were exposed to cigarette smoke extract (CSE) for 24 h. In vivo, mice were exposed to cigarette smoke (CS) for 4 weeks. To investigate the role of xCT, we used siRNA and AAV6 to conditionally knock down xCT in vitro and in vivo, respectively. Results The administration of ferrostatin-1 (Fer-1), a ferroptosis inhibitor that inhibits lipid peroxidation, significantly reduced the cytotoxicity of CSE to Beas-2b cells and mitigated inflammatory exudation, lung injury and mucus hypersecretion in mice with CS-induced COPD. Fer-1 suppressed gasdermin D (GSDMD)-mediated pyroptosis caused by CS in vitro and in vivo. However, in Beas-2b cells and the lung epithelial cells of mice, conditional knockdown of xCT (a negative regulatory factor of lipid peroxidation) inhibited the xCT/GPx4 axis, leading to more severe lipid peroxidation and GSDMD-mediated pyroptosis during cigarette smoke exposure. Moreover, we found that CS promoted the degradation of xCT through the ubiquitin proteasome system (UPS) and that treatment with MG132 significantly inhibited the degradation of xCT and downregulated the expression of pyroptosis-related proteins. Conclusion The results of this study suggested that the ubiquitination-mediated degradation of xCT drives GSDMD-mediated pyroptosis in COPD and is a potential therapeutic target for COPD.

Objective: Acetaminophen (APAP) is one of the world's popular and safe painkillers, and overdose can cause severe liver damage and even acute liver failure. The effect and mechanism of the xanthohumol on acetaminophen-induced hepatotoxicity remains unclear. Methods: The hepatoprotective effects of xanthohumol were studied using APAP-induced HepG2 cells and acute liver injury of mouse, seperately. Results: In vitro, xanthohumol inhibited H2O2- and acetaminophen-induced cytotoxicity and oxidative stress. Xanthohumol up-regulated the expression of Nrf2. Further mechanistic studies showed that xanthohumol triggered Nrf2 activation via the AMPK/Akt/GSK3β pathway to exert a cytoprotective effect. In vivo, xanthohumol significantly ameliorated acetaminophen-induced mortality, the elevation of ALT and AST, GSH depletion, MDA formation and histopathological changes. Xanthohumol effectively suppressed the phosphorylation and mitochondrial translocation of JNK, mitochondrial translocation of Bax, the activation o cytochrome c, AIF secretion and Caspase-3. In vivo, xanthohumol increased Nrf2 nuclear transcription and AMPK, Akt and GSK3β phosphorylation in vivo. In addition, whether xanthohumol protected against acetaminophen-induced liver injury in Nrf2 knockout mice has not been illustated. Conclusion: Thus, xanthohumol exerted a hepatoprotective effect by inhibiting oxidative stress and mitochondrial dysfunction through the AMPK/Akt/GSK3β/Nrf2 antioxidant pathway.

PM2.5 is one of the main harmful environmental pollutants and can damage nasal epithelial carriers to worsen allergic rhinitis. Ferroptosis is a novel form of regulated cell death with iron-dependent lipid peroxidation. However, whether ferroptosis is involved in PM2.5-induced nasal epithelial injury has not been elucidated. To verify the vital role of ferroptosis in PM2.5-induced nasal epithelial injury and further explore the potential mechanism, we detected intracellular iron content, ROS release and lipid peroxidation and ferroptosis-related proteins in vitro as well as the pathological changes in the nasal epithelium and the levels of proinflammatory factors in nasal lavage fluid in vivo. Our results showed that PM2.5 exposure led to oxidative stress, labile iron accumulation and lipid peroxidation in HNEPCs. In addition, the expression levels of xCT, GPx4, FTH1 and FTL in HNEPCs were greatly inhibited by PM2.5. Treatment with the ferroptosis inhibitors deferoxamine (DFO) and ferrostatin-1 (Fer-1) significantly reversed the toxicity of PM2.5 to human nasal epithelial cells (HNEPCs). Mechanistically, AMPK-mediated autophagy was initiated during PM2.5 exposure, which drove ferroptosis of HNEPCs. Autophagy inhibitor remarkably improved cell death, oxidative stress, labile iron accumulation, lipid peroxidation, and the downregulated expression of xCT, GPx4, FTH1 and FTL in HNEPCs induced by PM2.5. Furthermore, an AMPK inhibitor (Compound C, CC) and siRNA-AMPKα suppressed autophagy activation and ferroptosis stimulated by PM2.5. In vivo, Fer-1 reduced nasal epithelial injury and mucus secretion in PM2.5-exposed mice. In addition, CC significantly improved nasal epithelial damage and proinflammatory factor production in mice caused by PM2.5 intranasal treatment. In addition, CC greatly inhibited autophagy activation but reversed the downregulation of GPX4 and FTH1 induced by PM2.5 in the nasal epithelium of mice. Together, these data suggest that AMPK-mediated autophagy plays an important role in PM2.5-induced ferroptosis and that AMPK might be a potential treatment target for PM2.5-induced nasal epithelial injury.

Urban airborne fine particulate matter (PM2.5) is a global pollution source that has been strongly related to multiple respiratory diseases involving various types of regulated cell death (RCD). However, the role of ferroptosis, a novel form of RCD, in PM2.5-induced acute lung injury (ALI), has not been elucidated. Herein, we define the role and mechanism of ferroptosis in a PM2.5-induced ALI model. First, we demonstrated that lipid peroxidation and iron accumulation were significantly enhanced in ALI models and were accompanied by activation of the AMP-activated protein kinase (AMPK)-Beclin1 signaling pathway and inhibition of the key subunit SLC7A11 of System Xc-. However, these abnormalities were partially reversed by ferroptosis inhibitors. We further revealed that Beclin1 knockdown or overexpression ameliorated or exacerbated PM2.5-induced ferroptosis, respectively. Mechanistically, we verified that Beclin1 blocks System Xc- activity to trigger ferroptosis by directly binding to SLC7A11. Finally, knockdown of Beclin1 by AAV-shRNA or inhibition of AMPK, an upstream activator of Beclin1, ameliorated PM2.5-induced ferroptosis and ALI. Taken together, our results revealed that ferroptosis plays a novel role in PM2.5-induced ALI and elucidated the specific mechanism involving the AMPK-Beclin1 pathway and System Xc-, which may provide new insight into the toxicological effects of PM2.5 on respiratory problems.