The crosslinks between ferroptosis and autophagy in asthma

CEACAM5 exacerbates asthma by inducing ferroptosis and autophagy in airway epithelial cells through the JAK/STAT6-dependent pathway

OBJECTIVES

Asthma, a prevalent chronic disease, poses significant health threats and burdens healthcare systems. This study focused on the role of bronchial epithelial cells in asthma pathophysiology.

METHODS

Bioinformatics was used to identify key asthmarelated genes. An ovalbumin-sensitized mouse model and an IL-13-stimulated Beas-2B cell model were established for further investigation.

RESULTS

Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) was identified as a crucial gene in asthma. CEACAM5 expression was elevated in asthmatic mouse lung tissues and IL-13-stimulated Beas-2B cells, primarily in bronchial epithelial cells. CEACAM5 induced reactive oxygen species (ROS), lipid peroxidation, and ferroptosis. Interfering with CEACAM5 reduced ROS, malondialdehyde levels, and enhanced antioxidant capacity, while inhibiting iron accumulation and autophagy. Overexpression of CEACAM5 in IL-13-stimulated cells activated the JAK/STAT6 pathway, which was necessary for CEACAM5-induced autophagy, ROS accumulation, lipid peroxidation, and ferroptosis.

CONCLUSION

CEACAM5 promotes ferroptosis and autophagy in airway epithelial cells via the JAK/STAT6 pathway, exacerbating asthma symptoms. It represents a potential target for clinical treatment.

Crosstalk between autophagy and other forms of programmed cell death

Cell death occurs continuously throughout individual development. By removing damaged or senescent cells, cell death not only facilitates morphogenesis during the developmental process, but also contributes to maintaining homeostasis after birth. In addition, cell death reduces the spread of pathogens by eliminating infected cells. Cell death is categorized into two main forms: necrosis and programmed cell death. Programmed cell death encompasses several types, including autophagy, pyroptosis, apoptosis, necroptosis, ferroptosis, and PANoptosis. Autophagy, a mechanism of cell death that maintains cellular equilibrium via the breakdown and reutilization of proteins and organelles, is implicated in regulating almost all forms of cell death in pathological contexts. Notably, necroptosis, ferroptosis, and PANoptosis are directly classified as autophagy-mediated cell death. Therefore, regulating autophagy presents a therapeutic approach for treating diseases such as inflammation and tumors that arise from abnormalities in other forms of programmed cell death. This review focuses on the crosstalk between autophagy and other programmed cell death modalities, providing new perspectives for clinical interventions in inflammatory and neoplastic diseases.

Duck House Inhalable Particulate Matter Induces Lung Injury by Activating Ferroptosis

The particulate matter (PM) generated during poultry farming is characterized by its complex composition and substantial emission levels. However, researches on the respiratory damage caused by poultry house PM and the underlying mechanisms remain limited. In this study, inhalable PM collected from duck houses was administered to experimental mice through inhalation exposure. After 10 days of short-term exposure and 30 days of long-term exposure, mice samples were collected for lung histopathological analysis and inflammatory cytokines detection. The results showed that inhalation of duck house PM induced pulmonary and systemic inflammatory responses in both groups of mice, with significant upregulation of IL-6 and CXCL2. Compared to short-term exposure, long-term exposure resulted in more severe microscopic lesions in the lungs. In addition, the concentrations of malondialdehyde (MDA) and glutathione (GSH) increased in mice, indicating that duck house PM could trigger oxidative stress in lungs, we also found duck house PM induced ferroptosis in mice. Furthermore, it was confirmed that duck house PM caused cell damage and increased intracellular iron levels in MLE-12 cells, and PM reduced GSH in a dose-dependent manner. Notably, ferroptosis inhibitor treatment effectively alleviated PM-induced cell damage. These findings indicated that duck house PM can induce ferroptosis in both mice and cells, and ferroptosis plays a critical role in duck house PM-induced lung damage. These results laid a solid foundation for further exploring the mechanism of PM-induced lung injury, and providing a new insight for targeting ferroptosis to treat such damage.

TRIM7 knockdown protects against LPS-induced autophagy, ferroptosis, and inflammatory responses in human bronchial epithelial cells

Asthma is one of the most common respiratory diseases in pediatric department. Several asthma-associated events including inflammatory responses, autophagy, and ferroptosis have been identified as typical pathological processes. TRIM7 is a member of TRIM proteins family associated with several types of diseases. Nevertheless, its role in asthma is still elusive. The current research showed that TRIM7 was involved in the pathogenesis of asthma mainly by regulating the Akt signaling pathway. In detail, we found that TRIM7 was highly expressed in patients with asthma and in an in vitro model of asthma. The following analysis indicated that TRIM7 knockdown attenuated the expression and secretion of inflammatory cytokines including TNF-α, IL-1β and IL-6 in lipopolysaccharide (LPS)-exposed human bronchial epithelial cells (HBECs). Meanwhile, knockdown of TRIM7 exerted inhibitory effects on LPS-induced autophagy and ferroptosis. Further mechanistic studies showed that TRIM7 knockdown inhibited LPS-induced activation of Akt pathway, while overexpression of Akt attenuated the inhibitory effects of TRIM7 knockdown on LPS-exposed HBECs. Collectively, we reported here that TRIM7 knockdown inhibited LPS-induced autophagy, ferroptosis, and inflammatory cytokine secretion in HBECs via regulating the Akt pathway, providing a new insight into the strategies for improving asthma treatments.

Targeted sonodynamic therapy induces tumor cell quasi-immunogenic ferroptosis and macrophage immunostimulatory autophagy in glioblastoma

In this study, we demonstrated the mechanism of a glioblastoma (GBM)-targeted sonodynamic therapy (SDT) strategy employing platelets loaded with a sonosensitizer based on functionalized boron nitride nanoparticles carrying chlorin e6 (BNPD-Ce6). In the in vitro study, we first found that the BNPD-Ce6-mediated sonodynamic action (SDA) induced remarkable viability loss, DNA damage, and cell death in the GBM cells (GBCs) but not macrophages. Surprisingly, the SDA-exposed GBCs displayed a ferroptotic phenotype while the SDA-exposed macrophages underwent immuno-stimulatory autophagy and potently potentiated the SDA's toxicity to the GBCs. The ferroptotic GBCs induced by the SDA were found to be quasi-immunogenic, characterized by the emission of some alarmins such as ATP, HSP90, and CRT, but absent HMGB1, a potent endogenous adjuvant. As such, the SDA-stressed GBCs were unable to stimulate the BMDMs. This defect, interestingly, could be rescued by platelets as a donor of HMGB1 which markedly enhanced the BNPD-Ce6's sonotoxicity to the GBCs. In the in vivo study, we first employed BNPD-Ce6-loaded platelets to achieve ultrasound-triggered, targeted delivery of BNPD-Ce6 in grafted intra-cranial GBMs and subsequent sonodynamic tumor damage. An SDT regimen designed based on these results slowed the growth of grafted intra-cranial GBMs and significantly increased the survival of the host animals. Pathological examination of the SDT-treated GBMs revealed tissue necrosis and destruction and validated the in vitro observations. Finally, the depletion of macrophages was found to abrogate the efficacy of the SDT in subcutaneous GBC grafts. In conclusion, the BNPD-Ce6@Plt-mediated SDT is a practicable and efficacious anti-GBM therapy. Its therapeutic mechanism critically involves a synergy of tumor cell ferroptosis, macrophage stimulation, and platelet activation induced by the SDA.

Hydrogen Sulfide Sustained Release Donor Alleviates Spinal Cord Ischemia-Reperfusion-Induced Neuron Death by Inhibiting Ferritinophagy-Mediated Ferroptosis

AIMS

Spinal cord ischemia-reperfusion injury (SCIRI) is a disastrous complication that cannot be completely prevented in thoracoabdominal aneurysm surgery, leading to sensory and motor dysfunction and even paraparesis, causing tremendous socioeconomic burden. Ferritinophagy is a form of autophagic ferroptosis, which is a contributor to SCIRI. Hydrogen sulfide (H2S) has been reported to be neuroprotective in various diseases. However, it remains unclear whether H2S alleviates SCIRI-induced neural death via regulating ferritinophagy-mediated ferroptosis. The aim of this study was to explore their relationship and interaction in SCIRI.

RESULTS

The results demonstrate that Nissl bodies and motor function were obviously lost in SCIRI rats. Meanwhile, SCIRI led to a significant increase in DHE-positive neurons, TUNEL-positive neurons, LC3-positive neurons, and ferritin-positive neurons, downregulation of GPx4, Slc7a11, p62, and ferritin expression, and upregulation of LC3 II/I and NCOA4 expression. Additionally, there was upregulation of the level of MDA, GSH, and Fe2+. Finally, we found that H2S could significantly relieve neuronal death and loss of motor function in SCIRI rats by inhibiting ferritinophagy and ferroptosis.

CONCLUSION

Ferroptosis and ferritinophagy play a crucial role in the etiopathogenesis of SCIRI, and H2S exerts neuroprotection by inhibiting ferritinophagy-mediated ferroptosis.

Copy Number Variation in Asthma: An Integrative Review

Asthma is a complex disease with varied clinical manifestations resulting from the interaction between environmental and genetic factors. While chronic airway inflammation and hyperresponsiveness are central features, the etiology of asthma is multifaceted, leading to a diversity of phenotypes and endotypes. Although most research into the genetics of asthma focused on the analysis of single nucleotide polymorphisms (SNPs), studies highlight the importance of structural variations, such as copy number variations (CNVs), in the inheritance of complex characteristics, but their role has not yet been fully elucidated in asthma. In this context, an integrative review was conducted to identify the genes and pathways involved, the location, size, and classes of CNVs, as well as their contribution to asthma risk, severity, control, and response to treatment. As a result of the review, 16 articles were analyzed, from different types of observational studies, such as case-control, cohort studies and genotyped-proband or trios design, that have been carried out in populations from different countries, ethnicities, and ages. Chromosomes 12 and 17 were the most studied in three publications each. CNVs located on 12 chromosomes were associated with asthma, the majority being found on chromosome 6p and 17q, of the deletion type, encompassing 30 different coding-protein genes and one pseudogene region. Six genes with CNVs were identified as significant expression quantitative locus (eQTLs) with mean expression in asthma-related tissues, such as the lung and whole blood. The phenotypic variability of asthma may hinder the clinical application of these findings, but the research shows the importance of investigating these genetic variations as possible biomarkers in asthma patients.

Coke oven emissions exacerbate allergic asthma by promoting ferroptosis in airway epithelial cells

Epidemiological studies have shown that coke oven emissions (COEs) affect the deterioration of asthma, but has not been proven by experimental results. In this study, we found for the first time that COEs exacerbate allergen house dust mite (HDM)-induced allergic asthma in the mouse model. The findings reveal that airway inflammation, airway remodeling and allergic reaction were aggravated in the COE + HDM combined exposure group compared with the individual exposure group. Mechanism studies indicated higher levels of iron and MDA in the COE + HDM combined exposure group, along with increased expression of Ptgs2 and reduced GPX4 expression. Iron chelator deferoxamine (DFO) effectively inhibited ferroptosis induced by COE synergistically with HDM in vitro. Further studies highlighted the role of ferritinophagy in the COE + HDM-induced ferroptosis. 3-methyladenine (3-MA) could inhibit ferroptosis in the COE + HDM exposure group. Interestingly, we injected DFO intraperitoneally into mice in the combined exposure group and found DFO could significantly inhibit the COE-exacerbated ferroptosis and allergic asthma. Our findings link ferroptosis with COE-exacerbated allergic asthma, implying that ferroptosis may have important therapeutic potential for asthma in patients with occupational exposure of COE.

Photobiomodulation Mitigates PM2.5-Exacerbated Pathologies in a Mouse Model of Allergic Asthma

Exposure to particulate matter (PM), especially PM2.5, is known to exacerbate asthma, posing a significant public health risk. This study investigated the asthma-reducing effects of photobiomodulation (PBM) in a mice model mimicking allergic airway inflammation exacerbated by PM2.5 exposure. The mice received sensitization with ovalbumin (OVA) and were subsequently treated with PM2.5 at a dose of 0.1 mg/kg every 3 days, for 9 times over 3 weeks during the challenge. PBM, using a 610 nm wavelength LED, was applied at 1.7 mW/cm2 to the respiratory tract via direct skin contact for 20 min daily for 19 days. Results showed that PBM significantly reduced airway hyperresponsiveness, plasma immunoglobulin E (IgE) and OVA-specific IgE, airway inflammation, T-helper type 2 cytokine, histamine and tryptase in bronchoalveolar lavage fluid (BALF), and goblet cell hyperplasia in PM2.5-exposed asthmatic mice. Moreover, PBM alleviated subepithelial fibrosis by reducing collagen deposition, airway smooth muscle mass, and expression of fibrosis-related genes. It mitigated reactive oxygen species generation, oxidative stress, endoplasmic reticulum stress, apoptotic cell death, ferroptosis, and modulated autophagic signals in the asthmatic mice exposed to PM2.5. These findings suggest that PBM could be a promising intervention for PM2.5-induced respiratory complications in patients with allergic asthma.

The role of hydrogen sulfide regulation of ferroptosis in different diseases

Ferroptosis is a programmed cell death that relies on iron and lipid peroxidation. It differs from other forms of programmed cell death such as necrosis, apoptosis and autophagy. More and more evidence indicates that ferroptosis participates in many types of diseases, such as neurodegenerative diseases, ischemia-reperfusion injury, cardiovascular diseases and so on. Hence, clarifying the role and mechanism of ferroptosis in diseases is of great significance for further understanding the pathogenesis and treatment of some diseases. Hydrogen sulfide (H2S) is a colorless and flammable gas with the smell of rotten eggs. Many years ago, H2S was considered as a toxic gas. however, in recent years, increasing evidence indicates that it is the third important gas signaling molecule after nitric oxide and carbon monoxide. H2S has various physiological and pathological functions such as antioxidant stress, anti-inflammatory, anti-apoptotic and anti-tumor, and can participate in various diseases. It has been reported that H2S regulation of ferroptosis plays an important role in many types of diseases, however, the related mechanisms are not fully clear. In this review, we reviewed the recent literature about the role of H2S regulation of ferroptosis in diseases, and analyzed the relevant mechanisms, hoping to provide references for future in-depth researches.

Rational design of a lysosome-targeted fluorescent probe for monitoring the generation of hydroxyl radicals in ferroptosis pathways

Ferroptosis is a newly discovered iron-dependent form of regulated cell death associated with high levels of hydroxyl radical (˙OH) production. Meanwhile, lysosome dysfunction has been shown to be one of the causes of ferroptosis. Although a variety of ˙OH-responsive fluorescent probes have been developed for detecting intracellular ˙OH in living cells, there are still only few lysosome-targeted probes to monitor the variation in lysosomal ˙OH levels during ferroptosis. Herein, we report a novel ˙OH-specific fluorescent probe HCy-Lyso, which is composed of the hydrocyanine and morpholine moiety. Upon treatment with ˙OH, its hydrocyanine unit was converted to the corresponding cyanine group, thus leading to a large π-conjugation extension of HCy-Lyso, accompanied by a significant fluorescence off-on response. Moreover, after reacting with ˙OH in an acidic environment, the protonation product of HCy-Lyso exhibits a higher fluorescence enhancement, which is suitable for detecting lysosomal ˙OH variation. HCy-Lyso has been utilized for imaging endogenous ˙OH in living cells under phorbol myristate acetate (PMA) stimuli and monitoring the changes in lysosomal ˙OH levels during ferroptosis. Thus, our study proposes a new strategy to design lysosome-targeted and ˙OH-responsive fluorescent probes to investigate the relationship between lysosomes and ferroptosis.

Cell-type-specific role of P2Y2 receptor in HDM-driven model of allergic airway inflammation

Allergic airway inflammation (AAI) is a chronic respiratory disease that is considered a severe restriction in daily life and is accompanied by a constant risk of acute aggravation. It is characterized by IgE-dependent activation of mast cells, infiltration of eosinophils, and activated T-helper cell type 2 (Th2) lymphocytes into airway mucosa. Purinergic receptor signaling is known to play a crucial role in inducing and maintaining allergic airway inflammation. Previous studies in an ovalbumin (OVA)-alum mouse model demonstrated a contribution of the P2Y2 purinergic receptor subtype (P2RY2) in allergic airway inflammation. However, conflicting data concerning the mechanism by which P2RY2 triggers AAI has been reported. Thus, we aimed at elucidating the cell-type-specific role of P2RY2 signaling in house dust mite (HDM)-driven model of allergic airway inflammation. Thereupon, HDM-driven AAI was induced in conditional knockout mice, deficient or intact for P2ry2 in either alveolar epithelial cells, hematopoietic cells, myeloid cells, helper T cells, or dendritic cells. To analyze the functional role of P2RY2 in these mice models, flow cytometry of bronchoalveolar lavage fluid (BALF), cytokine measurement of BALF, invasive lung function measurement, HDM re-stimulation of mediastinal lymph node (MLN) cells, and lung histology were performed. Mice that were subjected to an HDM-based model of allergic airway inflammation resulted in reduced signs of acute airway inflammation including eosinophilia in BALF, peribronchial inflammation, Th2 cytokine production, and bronchial hyperresponsiveness in mice deficient for P2ry2 in alveolar epithelial cells, hematopoietic cells, myeloid cells, or dendritic cells. Furthermore, the migration of bone-marrow-derived dendritic cells and bone-marrow-derived monocytes, both deficient in P2ry2, towards ATP was impaired. Additionally, we found reduced levels of MCP-1/CCL2 and IL-8 homologues in the BALF of mice deficient in P2ry2 in myeloid cells and lower concentrations of IL-33 in the lung tissue of mice deficient in P2ry2 in alveolar epithelial cells. In summary, our results show that P2RY2 contributes to HDM-induced airway inflammation by mediating proinflammatory cytokine production in airway epithelial cells, monocytes, and dendritic cells and drives the recruitment of lung dendritic cells and monocytes.