Tianhua Hou’s research while affiliated with Jilin 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.

Background and Purpose Our previous research showed that ferroptosis plays a crucial role in the pathophysiology of PM2.5‐induced lung injury. The present study aimed to investigate the protective role of the Nrf2 signalling pathway and its bioactive molecule tectoridin in PM2.5‐induced lung injury by regulating ferroptosis. Experimental Approach We examined the regulatory effect of Nrf2 on ferroptosis in PM2.5‐induced lung injury and Beas‐2b cells using Nrf2‐knockout (KO) mice and Nrf2 siRNA transfection. The effects and underlying mechanisms of tectoridin on PM2.5‐induced lung injury were evaluated in vitro and in vivo. Key Results Nrf2 deletion increased iron accumulation and ferroptosis‐related protein expression in vivo and vitro, further exacerbating lung injury and cell death in response to PM2.5 exposure. Tectoridin activated Nrf2 target genes and ameliorated cell death caused by PM2.5. In addition, tectoridin prevented lipid peroxidation, iron accumulation and ferroptosis in vitro, but in siNrf2‐treated cells, these effects almost disappeared. In addition, tectoridin effectively mitigated PM2.5‐induced respiratory system damage, as evaluated by HE, PAS, and inflammatory factors. Tectoridin also augmented the antioxidative Nrf2 signalling pathway and prevented changes in ferroptosis‐related morphological and biochemical indicators, including MDA levels, GSH depletion and GPX4 and xCT downregulation, in PM2.5‐induced lung injury. However, the effects of tectoridin on ferroptosis and respiratory injury were almost abolished in Nrf2‐KO mice. Conclusion and Implications Our data proposed the protective effect of Nrf2 activation on PM2.5‐induced lung injury by inhibiting ferroptosis‐mediated lipid peroxidation and highlight the potential of tectoridin as a PM2.5‐induced lung injury treatment.

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.

Oxidative stress and inflammation play important roles in pleurisy. Leonurine (Leo) has been confirmed to exert antioxidative and antiinflammatory effects in many preclinical experiments, but these effects have not been studied in pleurisy. The aim of this study was to explore the therapeutic effect and mechanism of Leo in a carrageenan (CAR)‐induced pleurisy model. In this study, we found that the increase of reactive oxygen species (ROS), myeloperoxidase (MPO), and malondialdehyde (MDA) and decrease of glutathione (GSH) induced by CAR could be reversed by the treatment of Leo. Leo effectively reduced the levels of proinflammatory cytokines interleukin‐1β (IL‐1β), tumor necrosis factor‐α (TNF‐α), and the percentages of mature macrophages and increased the levels of antiinflammatory cytokines (IL‐10). Furthermore, Western blotting revealed that Leo significantly activated the Nrf2 pathway to restrain the thioredoxin‐interacting protein/NOD‐like receptor protein 3 (TXNIP/NLRP3) and nuclear factor kappa‐B (NF‐κB) pathways. However, the protective effect of Leo was significantly weakened in Nrf2‐deficient mice. These results indicate that Leo confers potent protection against CAR‐induced pleurisy by inhibiting the TXNIP/NLRP3 and NF‐κB pathways dependent on Nrf2, which may serve as a promising agent for attenuating pleurisy.

Many natural flavonoids can activate nuclear factor erythroid 2-related factor 2 (Nrf2), which is pivotal for alleviating various diseases related to inflammation and oxidative stress, including pleurisy. Amentoflavone (AMF), a biflavonoid extracted from many plants, has some beneficial bioactivities, especially anti-inflammatory and antioxidative activities. We aimed to investigate whether AMF protects against pleurisy and lung injury induced by carrageenan (Car) by activating Nrf2. Pleurisy was induced in wild-type (WT) and Nrf2-deficient (Nrf2-/-) mice. Then, pleural exudate and lung tissue were collected for biochemical analysis, H&E staining, immunocytochemistry and western blotting. Our results indicated that AMF protected against Car-induced pleurisy and lung injury. The Wright-Giemsa and H&E staining results showed that AMF alleviated inflammatory effusion and pathological injury. In addition, AMF decreased SOD and GSH depletion and MDA and MPO generation in the lung tissue of mice. AMF activated Nrf2 through keap-1 dissociation and subsequently increased heme oxygenase-1 (HO-1), NAD(P)H-quinone oxidoreductase 1 (NQO1), and γ-glutamylcysteine ligase (GCL) levels. Furthermore, AMF suppressed IL-1β and TNF-α levels and increased IL-10 levels in pleural exudate by blocking the proinflammatory NF-κB, signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase (ERK) pathways induced by Car. However, these antioxidative and anti-inflammatory effects were weakened in Nrf2-/- mice. Moreover, AMF failed to suppress the NF-κB and STAT3 pathways in Nrf2-/- mice. Our results demonstrated that AMF exerted anti-inflammatory and antioxidative effects in Car-induced lung injury and pleurisy in a Nrf2-dependent manner.