HDM induce airway epithelial cell ferroptosis and promote inflammation by activating ferritinophagy in asthma

MMP12 deficiency attenuates menthol e-cigarette plus house dust-mite effects on pulmonary iron homeostasis and oxidative stress

BACKGROUND

Little is known regarding the pulmonary effects induced by the inhalation of menthol-flavored e-cigarette aerosols on asthma exacerbation, despite the popularity of these devices and flavors among youth and young adults. In the lungs, matrix metalloproteinase 12 (MMP12) expressed and secreted by both alveolar macrophages and bronchial epithelial cells plays an essential role in airway remodeling, a key feature of severe asthma. In this study, we investigated the role of MMP12 in menthol-flavored e-cigarette aerosol exposures plus house-dust mite (HDM)-induced asthmatic responses.

METHODS

We exposed wild-type (WT) and MMP12 knockout (KO) juvenile female mice to well-characterized menthol-flavored e-cigarette aerosols followed by either PBS or HDM treatment, and evaluated pulmonary outcomes in terms of iron metabolism, oxidative stress responses and pulmonary inflammation.

RESULTS

We found high levels of iron in the menthol-flavored e-cigarette aerosol. This correlated with e-cigarette + HDM WT mice exhibiting disruption of pulmonary iron metabolism, suggesting a defense mechanism against iron-mediated toxicity. This was evidenced by altered lung protein concentrations of ferroportin, ferritin, lactoferrin, and transferrin, activation of the antioxidant response element (ARE) pathway and up-regulated expression of NQO1 in e-cigarette + HDM WT mice. Further, despite decreased neutrophilic inflammation, MUC5AC, an oxidative stress inducible mucin, was increased in the e-cigarette + HDM WT mice. In contrast, MMP12 KO mice were protected against iron-induced oxidative stress responses, highlighting a crucial role of MMP12 in this model.

CONCLUSION

These findings revealed in vivo evidence supporting a crucial role for iron metabolism in nicotine salt iron-rich ENDS aerosol toxicity.

Eosinophil-airway epithelial cell crosstalk reveals the eosinophil-mediated DUOX1 upregulation in a murine allergic inflammation setting

Blood and airway eosinophilia represent markers for the endotype-driven treatment of allergic asthma. Little is known on mechanisms that link eosinophils and airway epithelial cells before and after these cells are infiltrated by eosinophils during allergic response. Given that innate immune mechanisms, mainly mediated by epithelial-derived cytokines (interleukin [IL]-33, IL-25, TSLP [thymic stromal lymphopoietin]), induce eosinophil-maturing/attractive substances, we thought to evaluate the crosstalk between eosinophils and airway epithelial cells in the context of IL-33-mediated allergic inflammation. DUOX1 was previously described in clinically relevant aspects of allergic inflammation in a HDM -induced allergic asthma mice model, and in patients with chronic sinusitis or allergic asthma. Thus, we evaluated the involvement of HDM and eosinophils in the regulation of DUOX1 in airway epithelial cells. To recapitulate the lung environment present at the allergen challenge time in acute asthma, we set up an in vitro model based on murine bone marrow-derived eosinophils differentiated with IL-5 and then activated with IL-33 (EOs33) and TC1 or C57 airway epithelial cells. We found that treatment of epithelial cells with HDM induced an eosinophil-attractive environment and increased DUOX1 expression. Importantly, we found that the coculture of airway epithelial cells with EOs33 or with conditioned medium from EOs33 enhanced the expression of DUOX1, which was further increased by combined stimulation (HDM plus EOs33). Our results suggest that lung recruited eosinophils once activated by IL-33 could be involved in a crosstalk loop with airway epithelial cells by DUOX1-mediated IL-33 secretion.

Effects of azithromycin on alleviating airway inflammation in asthmatic mice by regulating airway microbiota and metabolites

Asthma is a chronic respiratory disease with increasing global prevalence, often linked to disrupted airway microbiota. Azithromycin has shown promise in asthma treatment, but whether its effect is owing to its antimicrobial capacity remains largely unknown. A house dust mite (HDM)-induced asthmatic mouse model was used to evaluate the effects of azithromycin on airway inflammation and microbiota. Mice were divided into control, HDM-induced asthma, HDM + azithromycin, and azithromycin-alone groups. Airway microbiota was analyzed using 16S rRNA sequencing, and metabolomic profiles were assessed via liquid chromatography-tandem mass spectrometry. Azithromycin alleviated type 2 airway inflammation in HDM-induced asthma, restoring microbiota diversity by modulating specific genera, including Streptococcus, Staphylococcus, Ruminococcus, Coprococcus, Bifidobacterium, etc. Combination analysis with metabolomics revealed that azithromycin significantly regulated airway microbiota-associated sphingomyelin metabolism. Azithromycin's therapeutic effects in asthma are associated with its ability to regulate airway microbiota and its associated sphingomyelin metabolism, highlighting the potential for microbiota-targeted therapies in asthma.IMPORTANCEAsthma, a prevalent chronic respiratory condition, poses a significant global health challenge due to its increasing prevalence and associated morbidity. The role of airway microbiota in asthma pathogenesis is gaining attention, with evidence suggesting that disruptions in this microbial community contribute to disease severity. Our study investigates the impact of azithromycin, a macrolide antibiotic, on airway inflammation and microbiota in a mouse model of asthma. The findings reveal that azithromycin not only alleviates airway inflammation but also restores microbiota diversity and modulates microbiota-associated sphingomyelin metabolism. This research underscores the potential of microbiota-targeted therapies in asthma management, offering a novel therapeutic strategy that could improve patient outcomes and reduce the healthcare burden associated with asthma.

The role of ferritinophagy and ferroptosis in Alzheimer's disease

Iron is a crucial mineral element within human cells, serving as a pivotal cofactor for diverse biological enzymes. Ferritin plays a crucial role in maintaining iron homeostasis within the body through its ability to sequester and release iron. Ferritinophagy is a selective autophagic process in cells that specifically facilitates the degradation of ferritin and subsequent release of free iron, thereby regulating intracellular iron homeostasis. The nuclear receptor coactivator 4 (NCOA4) serves as a pivotal regulator in the entire process of ferritinophagy, facilitating its binding to ferritin and subsequent delivering to lysosomes for degradation, thereby enabling the release of free iron. The free iron ions within the cell undergo catalysis through the Fenton reaction, resulting in a substantial generation of reactive oxygen species (ROS). This process induces lipid peroxidation, thereby stimulating a cascade leading to cellular tissue damage and subsequent initiation of ferroptosis. Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive deterioration of emotional memory and cognitive function, accompanied by mental and behavioral aberrations. The pathology of the disease is characterized by aberrant deposition of amyloid β-protein (Aβ) and hyperphosphorylated tau protein. It has been observed that evident iron metabolism disorders and accumulation of lipid peroxides occur in AD, indicating a significant impact of ferritinophagy and ferroptosis on the pathogenesis and progression of AD. This article elucidates the process and mechanism of ferritinophagy and ferroptosis, investigating their implications in AD to identify novel targets for therapeutic intervention.

Cell death crosstalk in respiratory diseases: unveiling the relationship between pyroptosis and ferroptosis in asthma and COPD

Asthma and chronic obstructive pulmonary disease (COPD) are heterogeneous obstructive diseases characterized by airflow limitations and are recognized as significant contributors to fatality all over the globe. Asthma accounts for about 4, 55,000 deaths, and COPD is the 3rd leading contributor of mortality worldwide. The pathogenesis of these two obstructive disorders is complex and involves numerous mechanistic pathways, including inflammation-mediated and non-inflammation-mediated pathways. Among all the pathological categorizations, programmed cell deaths (PCDs) play a dominating role in the progression of these obstructive diseases. The two major PCDs that are involved in structural and functional remodeling in the progression of asthma and COPD are Pyroptosis and Ferroptosis. Pyroptosis is a PCD mechanism mediated by the activation of the Nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome, leading to the maturation and release of Interleukin-1β and Interleukin-18, whereas ferroptosis is a lipid peroxidation-associated cell death. In this review, the major molecular pathways contributing to these multifaceted cell deaths have been discussed, and crosstalk among them regarding the pathogenesis of asthma and COPD has been highlighted. Further, the possible therapeutic approaches that can be utilized to mitigate both cell deaths at once have also been illustrated.

Iron Drives Eosinophil Differentiation in Allergic Airway Inflammation Through Mitochondrial Metabolic Adaptation

Eosinophils play a crucial role as effector cells in asthma pathogenesis, with their differentiation being tightly regulated by metabolic mechanisms. While the involvement of iron in various cellular processes is well known, its specific role in eosinophil differentiation has largely remained unexplored. This study demonstrates that iron levels are increased during the differentiation process from eosinophil progenitors to mature and activated eosinophils in the context of allergic airway inflammation. Through experiments involving iron chelators, supplements, and iron-deficient or iron-enriched diets, the indispensable role of iron in eosinophil lineage commitment both in vitro and in vivo is demonstrated. Remarkably, iron chelation effectively suppresses eosinophil differentiation and alleviates airway inflammation in a house dust mite(HDM)-induced mouse model of allergic asthma. Mechanistically, iron promotes the expression of transcription factors that enforce eosinophil differentiation, and maintains mitochondrial metabolic activities, leading to specific metabolic shifts within the tricarboxylic acid (TCA) cycle, with succinate promoting eosinophil differentiation. Overall, this study highlights the function of iron and underlying metabolic mechanisms in eosinophil differentiation, providing potential therapeutic strategies for asthma control.

The extract from Quzhou Aurantii Fructus attenuates cough variant asthma through inhibiting the TRPV1/Ca2+/NFAT/TSLP pathway and ferroptosis via TRPV1 mediation in ovalbumin-induced mice

ETHNOPHARMACOLOGICAL RELEVANCE

Cough variant asthma (CVA), a prevalent chronic inflammatory disease, is the most common cause of chronic cough. Over the years, the aqueous extract of Quzhou Aurantii Fructus (QAFA) has been widely used to treat respiratory diseases, particularly cough.

AIM OF THE STUDY

This study aimed to elucidate the therapeutic effect of QAFA on allergen-induced CVA, providing deep insights into the underlying mechanisms.

MATERIALS AND METHODS

Ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was employed to characterize the compositions, while UPLC was used to quantify the contents of its major components in QAFA. CVA model was established via sensitization and atomization with ovalbumin (OVA), and received 600 and 1200 mg/kg of QAFA via intragastric gavage. Cough response was assessed by stimulation with capsaicin (CAP). Then, airway hyperresponsiveness (AHR), ELISA, western blotting, RT-qPCR, and histological analyses, were applied to assess pulmonary function, pathological changes, and investigate mechanisms in CVA mice following QAFA treatment through the TRPV1/Ca2+-dependent NFAT-induced expression of TSLP and ferroptosis. Additionally, the effects and mechanisms of QAFA were validated using IL-4, CAP for stimulation, capsazepine (CPZ) for inhibition, and TRPV1 siRNA transfection in cells.

RESULTS

Chemical analysis revealed that QAFA primarily contained sixteen compounds, with four main components including narirutin, naringin, hesperidin, and neohesperidin. In vivo, QAFA treatment alleviated cough and AHR, while concurrently reducing airway inflammation and mucus secretion in CVA mice. These effects were achieved by suppressing the TRPV1/NFAT/TSLP pathway and modulating the expression of ferroptosis-related proteins. In vitro, siTRPV1-transfected BEAS-2B cells demonstrated the involvement of the TRPV1 channel in IL-4-mediated Ca2+ influxes, ferroptosis, and regulation of TSLP production. QAFA and CPZ suppressed IL-4-induced TSLP production via the TRPV1/NFAT pathway and regulated the levels of ferroptosis-related proteins, while CAP counteracted the effect of QAFA on TSLP production in BEAS-2B cells. Furthermore, QAFA reduced IL-4 or CAP induced Ca2+ influx and IL-4 induced ferroptosis through TRPV1 mediation.

CONCLUSIONS

This study demonstrated that QAFA improved pulmonary function and alleviated asthmatic inflammatory response in treating CVA probably through suppressing the TRPV1/Ca2+/NFAT/TSLP pathway and ferroptosis via TRPV1 mediation.

Iron-related Genes and Proteins Involved in Iron Homeostasis in Animal Models of Allergic Asthma: A Systematic Review

The involvement of the immune oxidative stress response in the pathophysiology and pathogenesis of allergic asthma is well documented. However, reports on the role of iron homeostasis in allergic asthma is scarce. Therefore, this study aims to identify iron-related genes and proteins in mouse models of allergic asthma. Related articles were identified from SCOPUS and Web of Science databases. The article search was limited to publications in English, within a 10-year period (2014 - 2023, up to 16 August 2023) and original/research papers. All identified articles were screened for eligibility using the inclusion and exclusion criteria. All eligible articles were quality appraised prior to data extraction. Five studies were selected for data extraction. Based on the extracted data, three themes and seven subthemes related to iron homeostasis were identified. The type of samples and analytical methods used were also identified. In conclusion, our study elucidates that iron-related proteins are regulated in animal models of allergic asthma. However, the currently available data do not allow us to conclude whether the disease model resulted in iron accumulation or depletion. Therefore, further studies with other related markers should be conducted.

Poly-l-arginine promotes ferroptosis in asthmatic airway epithelial cells by modulating PBX1/GABARAPL1 axis

Eosinophils play a featured role among inflammatory cells participating in the onset and development of asthma. Activated eosinophils release several cytotoxic granular proteins, such as major basic protein (MBP), posing a significant threat to airway epithelium. Ferroptosis, a novel form of cell death, is gaining recognition for its involvement in asthma pathogenesis, though the specific mechanisms remain largely unknown. Herein, we revealed that poly-l-arginine (PLA), an MBP mimic, induced ferroptosis in airway epithelium by downregulating γ-aminobutyric acid receptor-associated protein-like 1 (GABARAPL1). Reduced GABARAPL1 expression was further confirmed in ovalbumin (OVA)-induced asthma mice and PLA-treated human airway organoids (hAOs). Mechanistically, PLA activated mechanistic target of rapamycin complex 1 (mTORC1) signaling, inhibiting pre-B-cell leukemia transcription factor 1 (PBX1), which in turn leads to transcriptional downregulation of GABARAPL1. Furthermore, MBP extracted from eosinophils, similar to PLA, induced ferroptosis in airway epithelial cells, as well as modulating mTORC1/PBX1/GABARAPL1 pathway. Finally, Ferrostatin-1 treatment or GABARAPL1 overexpression alleviated ferroptosis and airway inflammation in asthmatic mice. Overall, our findings highlight the cell communication between eosinophils and airway epithelial cells. MBP modulates the mTORC1/PBX1/GABARAPL1 axis, thereby serving as a significant contributor to ferroptosis in airway epithelium and airway inflammation. This suggests that suppressing ferroptosis in airway epithelium or targeting eosinophils and MBP could lead to novel therapeutic strategies for asthma management.

Silencing SMAD4 inhibits inflammation and ferroptosis in asthma by blocking the IL-17A signaling pathway

BACKGROUND

The TGF-β/SMAD signaling pathway is crucial in the pathogenesis of asthma. However, SMAD family member 4 (SMAD4), a key mediator of TGF-β, its roles and underlying mechanisms in asthma remain unclear.

METHODS

The in vivo and in vitro roles of SMAD4 in asthma were investigated through an ovalbumin (OVA)-induced mouse model and an interleukin-13 (IL-13)-induced cell model. The molecular mechanism of SMAD4 influenced asthma was examined using transcriptome sequencing, followed by feedback experiments involving recombinant human interleukin 17 A (rhIL-17 A), an IL-17 A signaling pathway activator.

RESULTS

SMAD4 was highly expressed in the asthma models. SMAD4 silencing alleviated damage to lung tissue and decreased inflammatory infiltration. Expression levels of Caspase-3, IgG, and inflammatory factors were reduced after silencing SMAD4. Silencing SMAD4 suppressed ferroptosis. Silencing SMAD4 also enhanced IL-13-induced BEAS-2B cell proliferation and suppressed apoptosis. Furthermore. IL-17 A signaling pathway was promoted in the asthma models, as evidenced by elevated IL-17RA, IL-17 A, and Act1 protein levels. SMAD4 silencing inhibited the expression levels of these IL-17 A pathway-associated proteins. Moreover, rhIL-17 A treatment notably reversed the impacts of SMAD4 silencing on asthma in the IL-13-induced cell model and OVA-induced mouse model, indicating that silencing SMAD4 inhibited inflammation and ferroptosis in asthma by blocking the IL-17 A signaling pathway.

CONCLUSION

Silencing SMAD4 prevents inflammation and ferroptosis in asthma by inhibiting the IL-17 pathway, which provides a novel potential approach for asthma therapy.

Transcriptomic analysis and validation study of key genes and the HIF‑1α/HO‑1 pathway associated with ferroptosis in neutrophilic asthma

Ferroptosis, as a unique form of cell death caused by iron overload and lipid peroxidation, is involved in the pathogenesis of various inflammatory diseases of the airways. Inhibition of ferroptosis has become a novel strategy for reducing airway epithelial cell death and improving airway inflammation. The aim of the present study was to analyze and validate the key genes and signaling pathways associated with ferroptosis by bioinformatic methods combined with experimental analyzes in vitro and in vivo to aid the diagnosis and treatment of neutrophilic asthma. A total of 1,639 differentially expressed genes (DEGs) were identified in the transcriptome dataset. After overlapping with ferroptosis-related genes, 11 differentially expressed ferroptosis-related genes (DE-FRGs) were obtained. A new diagnostic model was constructed by these DE-FRGs from the transcriptome dataset with those from the GSE108417 dataset. The receiver operating characteristic curve analysis indicated that the area under the curve had good diagnostic performance (>0.8). As a result, four key DE-FRGs (CXCL2, HMOX1, IL-6 and SLC7A5) and biological pathway [hypoxia-inducible factor 1 (HIF-1) signaling pathway] associated with ferroptosis in neutrophilic asthma were identified by the bioinformatics analysis combined with experimental validation. The upstream regulatory network of key DE-FRGs and target drugs were predicted and the molecular docking results from screened 37 potential therapeutic drugs revealed that the 13 small-molecule drugs exhibited a higher stable binding to the primary proteins of key DE-FRGs. The results suggested that four key DE-FRGs and the HIF-1α/heme oxygenase 1 pathway associated with ferroptosis have potential as novel markers or targets for the diagnosis or treatment of neutrophilic asthma.

Occupational agents-mediated asthma: From the perspective of autophagy

Occupational asthma (OA) is a common occupational pulmonary disease that is frequently underdiagnosed and underreported. The complexity of diagnosing and treating OA creates a significant social and economic burden, making it an important public health issue. In addition to avoiding allergens, patients with OA require pharmacotherapy; however, new therapeutic targets and strategies need further investigation. Autophagy may be a promising intervention target, but there is a lack of relevant studies summarizing the role of autophagy in OA. In this review consolidates the current understanding of OA, detailing principal and novel agents responsible for its onset. Additionally, we summarize the mechanisms of autophagy in HMW and LMW agents induced OA, revealing that occupational allergens can induce autophagy disorders in lung epithelial cells, smooth muscle cells, and dendritic cells, ultimately leading to OA through involving inflammatory responses, oxidative stress, and cell death. Finally, we discuss the prospects of targeting autophagy as an effective strategy for managing OA and even steroid-resistant asthma, encompassing autophagy interventions focused on organoids, organ-on-a-chip systems, nanomaterials vehicle, and nanobubbles; developing combined exposure models, and the role of non-classical autophagy in occupational asthma. In briefly, this review summarizes the role of autophagy in occupational asthma, offers a theoretical foundation for OA interventions based on autophagy, and identifies directions and challenges for future research.

Huperzine A protected against ferroptosis via activating PI3K/Akt signaling in lipopolysaccharide induced acute lung injury

Huperzine A (Hup A), an extract from Huperzia serrata, exerted its anti-inflammation and anti-oxidation effect to protect against neurodegenerative disorders and organ injury. Ferroptosis was indicated to involve in the development of acute lung injury (ALI) accompanying by lipid reactive oxygen species (ROS) overexpressed. However, there is little research focused on the protective effect of Hup A on ALI, and the underlying molecular mechanism remains elusive. This study aims to determine the therapeutic effect of Hup A on ALI in vivo and in vitro. Hup A attenuated lung injury and cellular damage in lipopolysaccharide-induced ALI (LPS-ALI) models, both in vivo and in vitro, accompanied by the upregulation of ferroptosis-associated proteins (SLC7A11 and GPX4). Furthermore, the pretreatment with Hup A decreased the abundance of inflammation factors (IL-6, TNF-α), MDA, lipid ROS, and Fe2+ in the LPS-ALI model, while it also promoted the secretion of SOD and GSH to antagonize peroxidation. Mechanistically, RNA sequencing and network pharmacological analysis synergistically revealed the PI3K/Akt signaling pathway as a potential target of Hup A. In vitro experiments demonstrated that Hup A effectively activated GPX4 through the PI3K/Akt signaling pathway, which was subsequently reversed by LY294002, an inhibitor of the PI3K/Akt signaling pathway. Consequently, our results revealed that Hup A inhibited ferroptosis in LPS-ALI by activating the PI3K-Akt signaling pathway which indicated the potential therapeutical effect of Hup A and further emphasized the pivotal role of ferroptosis in ALI.

Mechanisms of exacerbation of Th2-mediated eosinophilic allergic asthma induced by plastic pollution derivatives (PPD): A molecular toxicological study involving lung cell ferroptosis and metabolomics

Polystyrene microplastics (PS-MP) and dibutyl phthalate (DBP) are plastic pollution derivatives (PPDs) commonly found in the natural environment. To investigate the effects of PPD exposure on the risk of allergic asthma, we established a PPD exposure group in a mouse model. The dose administered for PS-MP was 0.1 mg/d and for DBP was 30 mg/kg/d, with a 5-week oral administration period. The pathological changes of airway tissue and the increase of oxidative stress and inflammatory response confirmed that PPD aggravated eosinophilic allergic asthma in mice. The mitochondrial morphological changes and metabolomics of mice confirmed that ferrotosis and oxidative stress played key roles in this process. Treatment with 100 mg/Kg deferoxamine (DFO) provided significant relief, and metabolomic analysis of lung tissue supported the molecular toxicological. Our findings suggest that the increased levels of reactive oxygen species (ROS) in the lungs lead to Th2-mediated eosinophilic inflammation, characterized by elevated IL-4, IL-5, and eosinophils, and reduced INF-γ levels. This inflammatory response is mediated by the NFκB pathway and exacerbates type I hypersensitivity through increased IL-4 production. In this study, the molecular mechanism by which PPD aggravates asthma in mice was elucidated, which helps to improve the understanding of the health effects of PPD and lays a theoretical foundation for addressing the health risks posed by PPD.

Inflammation in a ferroptotic environment

Ferroptosis is an iron-dependent form of cell death, which finally culminates in lipid peroxidation and membrane damage. During the past decade, the interest in ferroptosis increased substantially and various regulatory components were discovered. The role of ferroptosis during inflammation and its impact on different immune cell populations is still under debate. Activation of inflammatory pathways such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and hypoxia inducible factors (HIFs) are known to alter the ability of cells to undergo ferroptosis and are closely connected to iron metabolism. During inflammation, iron regulatory systems fundamentally change and cells such as macrophages and neutrophils adapt their metabolism towards iron sequestering phenotypes. In this review, we discuss how ferroptosis alters inflammatory pathways and how iron metabolism under inflammatory conditions affects immune cell ferroptosis.

Indeno[1,2,3-cd]pyrene enhances the sensitivity of airway epithelial cells to ferroptosis and aggravates asthma

Particulate matter of aerodynamic diameter ≤2.5 μm (PM2.5) exposure induces oxidative stress in lung tissues. Ferroptosis is a form of regulated cell death based on oxidative damage and lipid peroxidation. Whether PM2.5 exposure-induced oxidative stress can promote ferroptosis to aggravate asthma is not known. To investigate if PM2.5 exposure induces oxidative stress to promote ferroptosis and influence asthma development, a cockroach extract-induced asthma model in mice was used for in vivo studies. Airway epithelial cell (AEC) ferroptosis was detected by assays (CCK8, malonaldehyde, and 4-hydroxynonenal). Molecular mechanisms were investigated by real-time reverse transcription-quantitative polymerase chain reaction, western blotting, flow cytometry, liquid chromatography-tandem mass spectrometry, and chromatin immunoprecipitation. We found that exposure to PM2.5 and Indeno[1,2,3-cd] pyrene (IP; one of the prominent absorbed polycyclic aromatic hydrocarbons in PM2.5) enhanced the sensitivity of AECs to ferroptosis to aggravate asthma, whereas ferroptosis inhibitors and cytosolic phospholipase A2 (cPLA2) inhibitors reversed this augmented inflammatory response in mice suffering from asthma. IP treatment enhanced cPLA2 expression/activation through aryl hydrocarbon receptor (AhR) genomic and non-genomic pathways, resulting in arachidonic-acid release to promote the sensitivity of AECs to ferroptosis. IP exposure enhanced the release of leukotriene-B4 from lung macrophages, resulting in enhanced expression of acyl-coA synthetase long chain family member4 (ACSL4) and the sensitivity of AECs to ferroptosis. This finding suggests that exposure to PM2.5 and IP promote ferroptosis sensitivity in AECs to aggravate asthma, which may provide new targets for the prevention and treatment of asthma.

Revealing the regulation of allergic asthma airway epithelial cell inflammation by STEAP4 targeting MIF through machine learning algorithms and single-cell sequencing analysis

Asthma comprises one of the most common chronic inflammatory conditions, yet still lacks effective diagnostic markers and treatment targets. To gain deeper insights, we comprehensively analyzed microarray datasets of airway epithelial samples from asthmatic patients and healthy subjects in the Gene Expression Omnibus database using three machine learning algorithms. Our investigation identified a pivotal gene, STEAP4. The expression of STEAP4 in patients with allergic asthma was found to be reduced. Furthermore, it was found to negatively correlate with the severity of the disease and was subsequently validated in asthmatic mice in this study. A ROC analysis of STEAP4 showed the AUC value was greater than 0.75. Functional enrichment analysis of STEAP4 indicated a strong correlation with IL-17, steroid hormone biosynthesis, and ferroptosis signaling pathways. Subsequently, intercellular communication analysis was performed using single-cell RNA sequencing data obtained from airway epithelial cells. The results revealed that samples exhibiting low levels of STEAP4 expression had a richer MIF signaling pathway in comparison to samples with high STEAP4 expression. Through both in vitro and in vivo experiments, we further confirmed the overexpression of STEAP4 in airway epithelial cells resulted in decreased expression of MIF, which in turn caused a decrease in the levels of the cytokines IL-33, IL-25, and IL-4; In contrast, when the STEAP4 was suppressed in airway epithelial cells, there was an upregulation of MIF expression, resulting in elevated levels of the cytokines IL-33, IL-25, and IL-4. These findings suggest that STEAP4 in the airway epithelium reduces allergic asthma Th2-type inflammatory reactions by inhibiting the MIF signaling pathway.

Progranulin: A promising biomarker and therapeutic target for fibrotic diseases

Progranulin (PGRN), a multifunctional growth factor-like protein expressed by a variety of cell types, serves an important function in the physiologic and pathologic processes of fibrotic diseases, including wound healing and the inflammatory response. PGRN was discovered to inhibit pro-inflammation effect by competing with tumor necrosis factor-alpha (TNF-α) binding to TNF receptors. Notably, excessive tissue repair in the development of inflammation causes tissue fibrosis. Previous investigations have indicated the significance of PGRN in regulating inflammatory responses. Recently, multiple studies have shown that PGRN was linked to fibrogenesis, and was considered to monitor the formation of fibrosis in multiple organs, including liver, cardiovascular, lung and skin. This paper is a comprehensive review summarizing our current knowledge of PGRN, from its discovery to the role in fibrosis. This is followed by an in-depth look at the characteristics of PGRN, consisting of its structure, basic function and intracellular signaling. Finally, we will discuss the potential of PGRN in the diagnosis and treatment of fibrosis.

Human umbilical cord mesenchymal stem cells alleviate chemotherapy-induced premature ovarian insufficiency mouse model by suppressing ferritinophagy-mediated ferroptosis in granulosa cells

Primary ovarian insufficiency (POI) in younger women (under 40) manifests as irregular periods, high follicle-stimulating hormone (FSH), and low estradiol (E2), often triggered by chemotherapy. Though mesenchymal stem cell (MSC) therapy shows promise in treating POI, its exact mechanism remains unclear. This study reveals that human umbilical cord-derived MSCs (hUC-MSCs) can protect ovarian granulosa cells (GCs) from cyclophosphamide (CTX)-induced ferroptosis, a form of cell death driven by iron accumulation. CTX, commonly used to induce POI animal model, triggered ferroptosis in GCs, while hUC-MSCs treatment mitigated this effect, both in vivo and in vitro. Further investigations using ferroptosis and autophagy inhibitors suggest that hUC-MSCs act by suppressing ferroptosis in GCs. Interestingly, hUC-MSCs activate a protective antioxidant pathway in GCs via NRF2, a stress-response regulator. Overall, our findings suggest that hUC-MSCs improve ovarian function in CTX-induced POI by reducing ferroptosis in GCs. This study not only clarifies the mechanism behind the benefits of hUC-MSCs but also strengthens the case for their clinical use in treating POI. Additionally, it opens up a new avenue for protecting ovaries from chemotherapy-induced damage by regulating ferroptosis.

Targeting ferroptosis using Chinese herbal compounds to treat respiratory diseases

BACKGROUND

Respiratory diseases pose a grave threat to human life. Therefore, understanding their pathogenesis and therapeutic strategy is important. Ferroptosis is a novel type of iron-dependent programmed cell death, distinct from apoptosis, necroptosis, and autophagy, characterised by iron, reactive oxygen species, and lipid peroxide accumulation, as well as glutathione (GSH) depletion and GSH peroxidase 4 (GPX4) inactivation. A close association between ferroptosis and the onset and progression of respiratory diseases, including chronic obstructive pulmonary disease, acute lung injury, bronchial asthma, pulmonary fibrosis, and lung cancer, has been reported. Recent studies have shown that traditional Chinese medicine (TCM) compounds exhibit unique advantages in the treatment of respiratory diseases owing to their natural properties and potential efficacy. These compounds can effectively regulate ferroptosis by modulating several key signalling pathways such as system Xc- -GSH-GPX4, NCOA4-mediated ferritinophagy, Nrf2-GPX4, and Nrf2/HO-1, thus playing a positive role in improving respiratory diseases.

PURPOSE

This comprehensive review systematically outlines the regulatory role of ferroptosis in the onset and progression of respiratory diseases and provides evidence for treating respiratory diseases by targeting ferroptosis with TCM compounds. These insights aim to offer potential remedies for the clinical prevention and treatment of respiratory diseases.

STUDY DESIGN AND METHODS

We searched scientific databases PubMed, Web of Science, Scopus, and CNKI using keywords such as "ferroptosis","respiratory diseases","chronic obstructive pulmonary disease","bronchial asthma","acute lung injury","pulmonary fibrosis","lung cancer","traditional Chinese medicine","traditional Chinese medicine compound","monomer", and "natural product" to retrieve studies on the therapeutic potential of TCM compounds in ameliorating respiratory diseases by targeting ferroptosis. The retrieved data followed PRISMA criteria (preferred reporting items for systematic review).

RESULTS

TCM compounds possess unique advantages in treating respiratory diseases, stemming from their natural origins and proven clinical effectiveness. TCM compounds can exert therapeutic effects on respiratory diseases by regulating ferroptosis, which mainly involves modulation of pathways such as system Xc- -GSH-GPX4,NCOA4-mediated ferritinophagy, Nrf2-GPX4, and Nrf2/HO-1.

CONCLUSION

TCM compounds have demonstrated promising potential in improving respiratory diseases through the regulation of ferroptosis. The identification of specific TCM-related inducers and inhibitors of ferroptosis holds great significance in developing more effective strategies. However, current research remains confined to animal and cellular studies, emphasizing the imperative for further verifications through high-quality clinical data.

The emerging role of nuclear receptor coactivator 4 in health and disease: a novel bridge between iron metabolism and immunity

Nuclear receptor coactivator 4 (NCOA4) has recently been recognized as a selective cargo receptor of ferritinophagy participating in ferroptosis. However, NCOA4 is also a coactivator that modulates the transcriptional activity of many vital nuclear receptors. Recent novel studies have documented the role of NCOA4 in healthy and pathogenic conditions via its modulation of iron- and non-iron-dependent metabolic pathways. NCOA4 exhibits non-ferritinophagic and iron-independent features such as promoting tumorigenesis and erythropoiesis, immunomodulation, regulating autophagy, and participating in DNA replication and mitosis. Full-length human-NCOA4 is composed of 614 amino acids, of which the N-terminal (1-237) contains nuclear-receptor-binding domains, while the C-terminal (238-614) principally contains a ferritin-binding domain. The exploration of the protein structure of NCOA4 suggests that NCOA4 possesses additional significant and complex functions based on its structural domains. Intriguingly, another three isoforms of NCOA4 that are produced by alternative splicing have been identified, which may also display disparate activities in physiological and pathological processes. Thus, NCOA4 has become an important bridge that encompasses interactions between immunity and metabolism. In this review, we outline the latest advances in the important regulating mechanisms underlying NCOA4 actions in health and disease conditions, providing insights into potential therapeutic interventions.

Effects of Panax species and their bioactive components on allergic airway diseases

Panax species include Panax ginseng Meyer, Panax quinquefolium L., Panax notoginseng, Panax japonicum, Panax trifolium, and Panax pseudoginseng, which contain bioactive components (BCs) such as ginsenosides and polysaccharides. Recently, growing evidence has revealed the pharmacological effects of Panax species and their BCs on allergic airway diseases (AADs), including allergic asthma (AA) and allergic rhinitis (AR). AADs are characterized by damaged epithelium, sustained acquired immune responses with enforced Th2 responses, allergen-specific IgE production, and enhanced production of histamine and leukotrienes by activated mast cells and basophils. In this review, we summarize how Panax species and their BCs modulate acquired immune responses involving interactions between dendritic cells and T cells, reduce the pro-inflammatory responses of epithelial cells, and reduce allergenic responses from basophils and mast cells in vitro. In addition, we highlight the current understanding of the alleviative effects of Panax species and their BCs against AA and AR in vivo. Moreover, we discuss the unmet needs of research and considerations for the treatment of patients to provide basic scientific knowledge for the treatment of AADs using Panax species and their BCs.

International consensus guidelines for the definition, detection, and interpretation of autophagy-dependent ferroptosis

Macroautophagy/autophagy is a complex degradation process with a dual role in cell death that is influenced by the cell types that are involved and the stressors they are exposed to. Ferroptosis is an iron-dependent oxidative form of cell death characterized by unrestricted lipid peroxidation in the context of heterogeneous and plastic mechanisms. Recent studies have shed light on the involvement of specific types of autophagy (e.g. ferritinophagy, lipophagy, and clockophagy) in initiating or executing ferroptotic cell death through the selective degradation of anti-injury proteins or organelles. Conversely, other forms of selective autophagy (e.g. reticulophagy and lysophagy) enhance the cellular defense against ferroptotic damage. Dysregulated autophagy-dependent ferroptosis has implications for a diverse range of pathological conditions. This review aims to present an updated definition of autophagy-dependent ferroptosis, discuss influential substrates and receptors, outline experimental methods, and propose guidelines for interpreting the results.Abbreviation: 3-MA:3-methyladenine; 4HNE: 4-hydroxynonenal; ACD: accidentalcell death; ADF: autophagy-dependentferroptosis; ARE: antioxidant response element; BH2:dihydrobiopterin; BH4: tetrahydrobiopterin; BMDMs: bonemarrow-derived macrophages; CMA: chaperone-mediated autophagy; CQ:chloroquine; DAMPs: danger/damage-associated molecular patterns; EMT,epithelial-mesenchymal transition; EPR: electronparamagnetic resonance; ER, endoplasmic reticulum; FRET: Försterresonance energy transfer; GFP: green fluorescent protein;GSH: glutathione;IF: immunofluorescence; IHC: immunohistochemistry; IOP, intraocularpressure; IRI: ischemia-reperfusion injury; LAA: linoleamide alkyne;MDA: malondialdehyde; PGSK: Phen Green™ SK;RCD: regulatedcell death; PUFAs: polyunsaturated fatty acids; RFP: red fluorescentprotein;ROS: reactive oxygen species; TBA: thiobarbituricacid; TBARS: thiobarbituric acid reactive substances; TEM:transmission electron microscopy.

Identifying ALOX15-initiated lipid peroxidation increases susceptibility to ferroptosis in asthma epithelial cells

Ferroptosis is a programmed form of cell death regulated by iron and has been linked to the development of asthma. However, the precise mechanisms driving ferroptosis in asthma remain elusive. To gain deeper insights, we conducted an analysis of nasal epithelial and sputum samples from the GEO database using three machine learning methods. Our investigation identified a pivotal gene, Arachidonate 15-lipoxygenase (ALOX15), associated with ferroptosis in asthma. Through both in vitro and in vivo experiments, we further confirmed the significant role of ALOX15 in ferroptosis in asthma. Our results demonstrate that ferroptosis manifests in an HDM/LPS-induced allergic airway inflammation (AAI) mouse model, mimicking human asthma, and in HDM/LPS-stimulated 16HBE cells. Moreover, we observed an up-regulation of ALOX15 expression in HDM/LPS-induced mice and cells. Notably, silencing ALOX15 markedly decreased HDM/LPS-induced ferroptosis in 16HBE cells. These findings indicate that ferroptosis may be implicated in the onset and progression of asthma, with ALOX15-induced lipid peroxidation raising the susceptibility to ferroptosis in asthmatic epithelial cells.

Polystyrene microplastics induce pulmonary fibrosis by promoting alveolar epithelial cell ferroptosis through cGAS/STING signaling

Polystyrene microplastics (PS-MPs) are new types of environmental pollutant that have garnered significant attention in recent years since they were found to cause damage to the human respiratory system when they are inhaled. The pulmonary fibrosis is one of the serious consequences of PS-MPs inhalation. However, the impact and underlying mechanisms of PS-MPs on pulmonary fibrosis are not clear. In this study, we studied the potential lung toxicity and PS-MPs-developed pulmonary fibrosis by long-term intranasal inhalation of PS-MPs. The results showed that after exposing to the PS-MPs, the lungs of model mouse had different levels of damage and fibrosis. Meanwhile, exposing to the PS-MPs resulted in a markedly decrease in glutathione (GSH), an increase in malondialdehyde (MDA), and iron overload in the lung tissue of mice and alveolar epithelial cells (AECs). These findings suggested the occurrence of PS-MP-induced ferroptosis. Inhibitor of ferroptosis (Fer-1) had alleviated the PS-MPs-induced ferroptosis. Mechanically, PS-MPs triggered cell ferroptosis and promoted the development of pulmonary fibrosis via activating the cGAS/STING signaling pathway. Inhibition of cGAS/STING with G150/H151 attenuated pulmonary fibrosis after PS-MPs exposure. Together, these data provided novel mechanistic insights of PS-MPs-induced pulmonary fibrosis and a potential therapeutic paradigm.

IL-13 facilitates ferroptotic death in asthmatic epithelial cells via SOCS1-mediated ubiquitinated degradation of SLC7A11

Th2-high asthma is characterized by elevated levels of type 2 cytokines, such as interleukin 13 (IL-13), and its prevalence has been increasing worldwide. Ferroptosis, a recently discovered type of programmed cell death, is involved in the pathological process of Th2-high asthma; however, the underlying mechanisms remain incompletely understood. In this study, we demonstrated that the serum level of malondialdehyde (MDA), an index of lipid peroxidation, positively correlated with IL-13 level and negatively correlated with the predicted forced expiratory volume in 1 s (FEV1%) in asthmatics. Furthermore, we showed that IL-13 facilitates ferroptosis by upregulating of suppressor of cytokine signaling 1 (SOCS1) through analyzing immortalized airway epithelial cells, human airway organoids, and the ovalbumin (OVA)-challenged asthma model. We identified that signal transducer and activator of transcription 6 (STAT6) promotes the transcription of SOCS1 upon IL-13 stimulation. Moreover, SOCS1, an E3 ubiquitin ligase, was found to bind to solute carrier family 7 member 11 (SLC7A11) and catalyze its ubiquitinated degradation, thereby promoting ferroptosis in airway epithelial cells. Last, we found that inhibiting SOCS1 can decrease ferroptosis in airway epithelial cells and alleviate airway hyperresponsiveness (AHR) in OVA-challenged wide-type mice, while SOCS1 overexpression exacerbated the above in OVA-challenged IL-13-knockout mice. Our findings reveal that the IL-13/STAT6/SOCS1/SLC7A11 pathway is a novel molecular mechanism for ferroptosis in Th2-high asthma, confirming that targeting ferroptosis in airway epithelial cells is a potential therapeutic strategy for Th2-high asthma.

Ferroptosis contributes to airway epithelial E-cadherin disruption in a mixed granulocytic asthma mouse model

Aberrant expression of airway epithelial E-cadherin is a key feature of asthma, yet the underlying mechanisms are largely unknown. Ferroptosis is a novel form of regulated cell death involved in asthma pathogenesis. This study was aimed to evaluate the role of ferroptosis and to investigate whether ferroptosis mediates E-cadherin disruption in mixed granulocyte asthma (MGA). Two murine models of MGA were established using toluene diisocyanate (TDI) or ovalbumin with Complete Freund's Adjuvant (OVA/CFA). Specific antagonists of ferroptosis, including Liproxstatin-1 (Lip-1) and Ferrostatin-1 (Fer-1) were given to the mice. The allergen-exposed mice displayed markedly shrunk mitochondria in the airway epithelia, with decreased volume and denser staining accompanied by down-regulated GPX4 as well as up-regulated FTH1 and malondialdehyde, which are markers of ferroptosis. Decreased pulmonary expression of E-cadherin was also observed, with profound loss of membrane E-cadherin in the airway epithelia, as well as increased secretion of sE-cadherin. Treatment with Lip-1 not only showed potent protective effects against the allergen-induced airway hyperresponsiveness and inflammatory responses, but also rescued airway epithelial E-cadherin expression and inhibited the release of sE-cadherin. Taken together, our data demonstrated that ferroptosis mediates airway epithelial E-cadherin dysfunction in MGA.

Nanoplastics Penetrate Human Bronchial Smooth Muscle and Small Airway Epithelial Cells and Affect Mitochondrial Metabolism

Micro- and nanoplastic particles, including common forms like polyethylene and polystyrene, have been identified as relevant pollutants, potentially causing health problems in living organisms. The mechanisms at the cellular level largely remain to be elucidated. This study aims to visualize nanoplastics in bronchial smooth muscle (BSMC) and small airway epithelial cells (SAEC), and to assess the impact on mitochondrial metabolism. Healthy and asthmatic human BSMC and SAEC in vitro cultures were stimulated with polystyrene nanoplastics (PS-NPs) of 25 or 50 nm size, for 1 or 24 h. Live cell, label-free imaging by holotomography microscopy and mitochondrial respiration and glycolysis assessment were performed. Furthermore, 25 and 50 nm NPs were shown to penetrate SAEC, along with healthy and diseased BSMC, and they impaired bioenergetics and induce mitochondrial dysfunction compared to cells not treated with NPs, including changes in oxygen consumption rate and extracellular acidification rate. NPs pose a serious threat to human health by penetrating airway tissues and cells, and affecting both oxidative and glycolytic metabolism.

Up-regulation of HSP90α in HDM-induced asthma causes pyroptosis of airway epithelial cells by activating the cGAS-STING-ER stress pathway

Heat Shock protein 90 α (HSP90α), an main subtype of chaperone protein HSP90, involves important biological functions such as DNA damage repair, protein modification, innate immunity. However, the potential role of HSP90α in asthma occurrence and development is still unclear. This study aimed to elucidate the underlying mechanism of HSP90α in asthma by focusing on the cGAS-STING-Endoplasmic Reticulum stress pathway in inflammatory airway epithelial cell death (i.e., pyroptosis; inflammatory cell death). To accomplish that, we modeled allergen exposure in C57/6BL mice and bronchial epithelial cells with house dust mite. Protein technologies and immunofluorescence utilized to study the expression of HSP90α, activation of cGAS-STING pathway and pyroptosis. The effect of inhibitors on HDM-exposed mice detected by histological techniques and examination of bronchoalveolar lavage fluid. Results showed that HSP90α promotes asthma inflammation via pyroptosis and activation of the cGAS-STING-ER stress pathway. Treatment with the HSP90 inhibitor tanespimycin (17-AAG) significantly relieved airway inflammation and abrogated the effect of HSP90α on pyroptosis and cGAS-STING-ER stress in vitro and in vivo models of HDM. Further data indicated that up-regulation of HSP90α stabilized STING through interaction, which increased localization of STING on the ER. Activation of STING triggered ER stress and leaded to pyroptosis-related airway inflammation. The finding showed the potential role of pyroptosis caused by dysregulation of HSP90α on airway epithelial cells in allergic inflammation, suggested that targeting HSP90α in airway epithelial cells might prove to be a potential additional treatment strategy for asthma.

Ferroptotic alveolar epithelial type II cells drive TH2 and TH17 mixed asthma triggered by birch pollen allergen Bet v 1

Asthma is a common allergic disease characterized by airway hypersensitivity and airway remodeling. Ferroptosis is a regulated death marked by iron accumulation and lipid peroxidation. Several environmental pollutants and allergens have been shown to cause ferroptosis in epithelial cells, but the relationship between birch pollinosis and ferroptosis in asthma is poorly defined. Here, for the first time, we have identified ferroptosis of type II alveolar epithelial cells in mice with Bet v 1-induced asthma. Further analysis revealed that treatment with ferrostatin-1 reduced TH2/TH17-related inflammation and alleviated epithelial damage in mice with Bet v 1-induced asthma. In addition, ACSL4-knocked-down A549 cells are more resistant to Bet v 1-induced ferroptosis. Analysis of clinical samples verified higher serum MDA and 4-HNE concentrations compared to healthy individuals. We demonstrate that birch pollen allergen Bet v 1 induces ferroptosis underlaid TH2 and TH17 hybrid asthma. Lipid peroxidation levels can be considered as a biomarker of asthma severity, and treatment with a specific ferroptosis inhibitor could be a novel therapeutic strategy.

Regulation of NCOA4-mediated iron recycling ameliorates paraquat-induced lung injury by inhibiting ferroptosis

Paraquat (PQ) is an irreplaceable insecticide in many countries for the advantage of fast-acting and broad-spectrum. However, PQ was classified as the most prevailing poisoning substance for suicide with no specific antidote. Therefore, it is imperative to develop more effective therapeutic agents for the treatment of PQ poisoning. In the present study, both the RNA-Seq and the application of various cell death inhibitors reflected that ferroptosis exerts a crucial regulatory role in PQ poisoning. Moreover, we found PQ strengthens lipid peroxidation as evidenced by different experimental approaches. Of note, pretreatment of iron chelation agent DFO could ameliorate the ferroptotic cell death and alleviate the ferroptosis-related events. Mechanistically, PQ treatment intensively impaired mitochondrial homeostasis, enhanced phosphorylation of AMPK, accelerated the autophagy flux and triggered the activation of Nuclear receptor coactivator 4-ferritin heavy chain (NCOA4-FTH) axis. Importantly, the activation of autophagy was observed prior to the degradation of ferritin, and inhibition of autophagy could inhibit the accumulation of iron caused by the ferritinophagy process. Genetic and pharmacological inhibition of ferritinophagy could alleviate the lethal oxidative events, and rescue the ferroptotic cell death. Excitingly, in the mouse models of PQ poisoning, both the administration of DFO and adeno-associated virus-mediated FTH overexpression significantly reduced PQ-induced ferroptosis and improved the pathological characteristics of pulmonary fibrosis. In summary, the current work provides an in-depth study on the mechanism of PQ intoxication, describes a framework for the further understanding of ferroptosis in PQ-associated biological processes, and demonstrates modulation of iron metabolism may act as a promising therapeutic agent for the management of PQ toxicity.

Ferroptosis Induced by Pollutants: An Emerging Mechanism in Environmental Toxicology

Environmental pollutants have been recognized for their ability to induce various adverse outcomes in both the environment and human health, including inflammation, apoptosis, necrosis, pyroptosis, and autophagy. Understanding these biological mechanisms has played a crucial role in risk assessment and management efforts. However, the recent identification of ferroptosis as a form of programmed cell death has emerged as a critical mechanism underlying pollutant-induced toxicity. Numerous studies have demonstrated that fine particulates, heavy metals, and organic substances can trigger ferroptosis, which is closely intertwined with lipid, iron, and amino acid metabolism. Given the growing evidence linking ferroptosis to severe diseases such as heart failure, chronic obstructive pulmonary disease, liver injury, Parkinson's disease, Alzheimer's disease, and cancer, it is imperative to investigate the role of pollutant-induced ferroptosis. In this review, we comprehensively analyze various pollutant-induced ferroptosis pathways and intricate signaling molecules and elucidate their integration into the driving and braking axes. Furthermore, we discuss the potential hazards associated with pollutant-induced ferroptosis in various organs and four representative animal models. Finally, we provide an outlook on future research directions and strategies aimed at preventing pollutant-induced ferroptosis. By enhancing our understanding of this novel form of cell death and developing effective preventive measures, we can mitigate the adverse effects of environmental pollutants and safeguard human and environmental health.

Delineation and authentication of ferroptosis genes in ventilator-induced lung injury

BACKGROUND

Mechanical ventilation, a critical support strategy for individuals enduring severe respiratory failure and general anesthesia, paradoxically engenders ventilator-induced lung injury (VILI). Ferrostatin-1 mitigates lung injury via ferroptosis inhibition, yet the specific ferroptosis genes contributing significantly to VILI remain obscure.

METHODS

Leveraging the Gene Expression Omnibus database, we acquired VILI-associated datasets and identified differentially expressed genes (DEGs). To identify the hub genes, we constructed a protein-protein interaction network and used three parameters from CytoHubba. Consequently, we identified hub genes and ferroptosis genes as ferroptosis hub genes for VILI (VFHGs). We conducted enrichment analysis and established receiver operating characteristic (ROC) curves for VFHGs. Subsequently, to confirm the correctness of the VFHGs, control group mice and VILI mouse models, as well as external dataset validation, were established. For further research, a gene-miRNA network was established. Finally, the CIBERSORT algorithm was used to fill the gap in the immune infiltration changes in the lung during VILI.

RESULTS

We identified 64 DEGs and 4 VFHGs (Il6,Ptgs2,Hmox1 and Atf3) closely related to ferroptosis. ROC curves demonstrated the excellent diagnostic performance of VFHGs in VILI. PCR and external dataset validation of the VILI model demonstrated the accuracy of VFHGs. Subsequently, the gene-miRNA network was successfully established. Ultimately, an Immune cell infiltration analysis associated with VILI was generated.

CONCLUSIONS

The results emphasize the importance of 4 VFHGs and their involvement in ferroptosis in VILI, confirming their potential as diagnostic biomarkers for VILI.

Rhizoma Dioscoreae Nipponicae Relieves Asthma by Inducing the Ferroptosis of Eosinophils and Inhibiting the p38 MAPK Signaling Pathway

Rhizoma Dioscoreae Nipponicae (RDN) is a traditional Chinese medicine that widely applied in the treatment of human diseases. This study aims to explore the therapeutic potential of RDN in asthma and the underlying mechanisms. A mouse model of asthma was established by the stimulation of ovalbumin (OVA). HE staining was performed to detect the pathological injuries of tracheal tissues. The protein expression of collagen I, FN1, α-SMA (airway remodeling markers), and p-p38 (a marker of the p38 MAPK pathway) were detected by Western blot. Eosinophils were then isolated from the model mice. Cell viability and ROS level were measured by CCK-8 and Flow cytometry, respectively. The mRNA expression of GPX4 and ACSL4 (ferroptosis markers) in eosinophils were measured by qRT-PCR. RDN significantly reduced the numbers of total cells and eosnophils in bronchoalveolar lavage fluid (BALF), inhibited inflammatory cell infiltration, and down-regulated remodeling markers (Collagen I, FN1, and α-SMA) in OVA-induced mice. The p38 MAPK pathway was blocked by the intervention of RDN in the model mice, and its blocking weakens the poor manifestations of OVA-induced asthma. In addition, RDN induced the ferroptosis of eosnophils both in vitro and in vivo. Blocking of the p38 MAPK pathway also enhanced the ferroptosis of eosnophils in vitro, evidenced by the decreased cell viability and GPX4 expression, and increased ROS level and ACSL4 expression. RDN induced the ferroptosis of eosinophils through inhibiting the p38 MAPK pathway, contributing to the remission of asthma.

Comparison with gastric cancer-associated genes reveals the role of ferroptosis-related genes in eosinophils of asthma patients: A bioinformatic study

Ferroptosis-inducing agents (FIAs) induced lipid-peroxidation-independent ferroptosis in eosinophils, thus ameliorating airway inflammation in asthmatic mice. Differences in ferroptosis-related genes (FerrGs) between eosinophils and cells in which FIAs induce canonical ferroptosis are supposed to contribute to this noncanonical ferroptosis but remain unclear. This study aims to explore these differences. This study used gastric cancer cells (GCCs) in stomach adenocarcinoma as the representative of cells in which FIAs induce canonical ferroptosis. FerrGs in Ferroptosis Database V2 respectively intersected with differentially expressed genes (DEGs) of eosinophils (E-MTAB-4660 dataset) and GCCs (GEPIA2 Stomach adenocarcinoma dataset) to obtain original ferroptosis DEGs (FerrDEGs). Then, they were subjected to Venn analysis to identify FerrDEGs shared by them and FerrDEGs exclusively expressed in eosinophils or GCCs. Identified genes were subjected to functional enrichment analysis, protein-protein interactions analysis, Hub genes analysis, and construction of the LncRNA-mediated ceRNA network. Sixty-six original FerrDEGs in eosinophils and 110 original FerrDEGs in GCCs were obtained. Venn analysis identified that eosinophils and GCCs shared 19 FerrDEGs that presented opposite expression directions and were involved in the ferroptosis pathway. Four upregulated and 20 downregulated FerrDEGs were exclusively expressed in eosinophils and GCCs, respectively. The former were enriched only in glycerolipid metabolism, while the latter were not enriched in pathways. Forty downregulated and 68 upregulated FerrDEGs were solely expressed in eosinophils and GCCs, respectively. The former was associated with the FoxO signaling pathway; the latter was related to glutathione metabolism and they were all implicated in autophagy. PPI analysis shows that the top 10 Hub genes of 66 original FerrDEGs and 44 exclusive FerrDEGs in eosinophils shared 9 genes (STAT3, NFE2L2, MAPK8, PTEN, MAPK3, TLR4, SIRT1, BECN1, and PTGS2) and they were also involved in the FoxO signaling pathway and autophagy pathway. Among them, PTEN is involved in forming a ceRNA network containing 3 LncRNAs, 3 miRNAs and 3 mRNAs. In contrast to FerrGs in cells in which FIAs induce canonical ferroptosis, the FerrGs in eosinophils differ in expression and in the regulation of ferroptosis, FoxO signaling pathway, and autophagy. It lays the groundwork for targeted induction of eosinophils lipid-peroxidation-independent ferroptosis in asthma.

Beyond Macromolecules: Extracellular Vesicles as Regulators of Inflammatory Diseases

Inflammation is the defense mechanism of the immune system against harmful stimuli such as pathogens, toxic compounds, damaged cells, radiation, etc., and is characterized by tissue redness, swelling, heat generation, pain, and loss of tissue functions. Inflammation is essential in the recruitment of immune cells at the site of infection, which not only aids in the elimination of the cause, but also initiates the healing process. However, prolonged inflammation often brings about several chronic inflammatory disorders; hence, a balance between the pro- and anti-inflammatory responses is essential in order to eliminate the cause while producing the least damage to the host. A growing body of evidence indicates that extracellular vesicles (EVs) play a major role in cell-cell communication via the transfer of bioactive molecules in the form of proteins, lipids, DNA, RNAs, miRNAs, etc., between the cells. The present review provides a brief classification of the EVs followed by a detailed description of how EVs contribute to the pathogenesis of various inflammation-associated diseases and their implications as a therapeutic measure. The latter part of the review also highlights how EVs act as a bridging entity in blood coagulation disorders and associated inflammation. The findings illustrated in the present review may open a new therapeutic window to target EV-associated inflammatory responses, thereby minimizing the negative outcomes.

Exploration and Validation of Potential Biomarkers and Therapeutic Targets in Ferroptosis of Asthma

Purpose

Asthma is a chronic inflammatory airway disease involving multiple mechanisms, of which ferroptosis is a form of programmed cell death. Recent studies have shown that ferroptosis may play a crucial role in the pathogenesis of asthma, but no specific ferroptosis gene has been found in asthma, and the exact mechanism is still unclear. The present study aimed to screen ferroptosis genes associated with asthma and find therapeutic targets, in order to contribute a new clue for the diagnosis and therapy of asthma.

Methods

Ferroptosis-related differentially expressed genes (FR-DEGs) in asthma were selected by the GSE41861, GSE43696 and ferroptosis datasets. Next, the FR-DEGs were subjected by GO and KEGG enrichment, and the mRNA-miRNA network was constructed. Then, GSEA and GSVA enrichment analysis and Immune infiltration analysis were performed, followed by targeted drug prediction. Finally, the expression of FR-DEGs was confirmed using GSE63142 dataset and RT-PCR assay.

Results

We found 13 FR-DEGs by the GSE41861, GSE43696 and ferroptosis database. Functional enrichment analysis revealed that the 13 FR-DEGs were enriched in oxidative stress, immune response, ferroptosis, lysosome, necrosis, apoptosis etc. Moreover, our results revealed the mRNA-miRNA network of the FR-DEGs and identified candidate drugs. Also, immune infiltration revealed that ELAVL1, CREB5, CBR1 and NR1D2 are associated with the immune cells and may be potential targets in asthma. Finally, 10 FR-DEGs were validated by the GSE63142 database. It was verified that 7 FR-DEGs were differentially expressed by collecting asthma patients and healthy controls.

Conclusion

This study ultimately identified 7 FR-DEGs for the diagnosis and therapy of asthma. These 7 FR-DEGs contribute to oxidative stress and immune responses. This study provides potential therapeutic targets and biomarkers for asthma patients, shedding further light on the pathogenesis of asthma as well as providing new insights into the treatment of asthma.

Constructing ferroptosis-related competing endogenous RNA networks and exploring potential biomarkers correlated with immune infiltration cells in asthma using combinative bioinformatics strategy

BACKGROUND

Asthma is a common chronic respiratory disease worldwide. Recent studies have revealed the critical effects of the ceRNA network and ferroptosis on patients with asthma. Thus, this study aimed to explore the potential ferroptosis-related ceRNA network, investigate the immune cell infiltration level in asthma through integrated analysis of public asthma microarray datasets, and find suitable diagnostic biomarkers for asthma.

METHODS

First, three asthma-related datasets which were downloaded from the Gene Expression Omnibus (GEO) database were integrated into one pooled dataset after correcting for batch effects. Next, we screened differentially expressed lncRNAs (DElncRNAs) between patients and healthy subjects, constructed a ceRNA network using the StarBase database and screened ferroptosis-related genes from the predicted target mRNAs for Disease Ontology (DO), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. We also performed Gene Set Enrichment Analysis (GSEA) and Gene Set Variation Analysis (GSVA) on the batch effect-corrected mRNA expression profile. Then, Least Absolute Shrinkage and Selection Operator (LASSO) regression was used to screen potential diagnostic biomarkers, and the diagnostic efficacy was assessed using a receiver operating characteristic (ROC) curve. Finally, we determined the proportion of 22 immune cells in patients with asthma using CIBERSORT and investigated the correlation between key RNAs and immune cells.

RESULTS

We obtained 19 DElncRNAs, of which only LUCAT1 and MIR222HG had corresponding target miRNAs. The differentially expressed ferroptosis-related genes were involved in multiple programmed cell death-related pathways. We also found that the mRNA expression profile was primarily enriched in innate immune system responses. We screened seven candidate diagnostic biomarkers for asthma using LASSO regression (namely, BCL10, CD300E, IER2, MMP13, OAF, TBC1D3, and TMEM151A), among which the area under the curve (AUC) value for CD300E and IER2 were 0.722 and 0.856, respectively. Finally, we revealed the infiltration ratio of different immune cells in asthma and found a correlation between LUCAT1, MIR222HG, CD300E, and IER2 with some immune cells.

CONCLUSION

This study explored a potential lncRNA-miRNA-mRNA regulatory network and its underlying diagnostic biomarkers (CD300E and IER2) in asthma and identified the immune cells most associated with them, providing possible diagnostic markers and immunotherapeutic targets for asthma.

Ferritinophagy in the etiopathogenic mechanism of related diseases

Iron is an essential trace element that is involved in a variety of physiological processes. Ferritinophagy is selective autophagy mediated by nuclear receptor coactivator 4 (NCOA4), which regulates iron homeostasis in the body. Upon iron depletion or starvation, ferritinophagy is activated, releasing large amounts of Fe²⁺ and increasing reactive oxygen species (ROS), leading to ferroptosis. This plays a significant role in the etiopathogenesis of many diseases, such as metabolic diseases, neurodegenerative diseases, infectious diseases, tumors, cardiomyopathy, and ischemia-reperfusion ischemia-reperfusion injury. Here, we first review the regulation and functions of ferritinophagy and then describe its involvement in different diseases, with hopes of providing new understanding and insights into iron metabolism and iron disorder-related diseases and the therapeutic opportunity for targeting ferritinophagy.

The role of ferroptosis-related genes in airway epithelial cells of asthmatic patients based on bioinformatics

It has been reported that airway epithelial cells and ferroptosis have certain effect on asthma. However, the action mechanism of ferroptosis-related genes in airway epithelial cells of asthmatic patients is still unclear. Firstly, the study downloaded the GSE43696 training set, GSE63142 validation set and GSE164119 (miRNA) dataset from the gene expression omnibus database. 342 ferroptosis-related genes were downloaded from the ferroptosis database. Moreover, differentially expressed genes (DEGs) between asthma and control samples in the GSE43696 dataset were screened by differential analysis. Consensus clustering analysis was performed on asthma patients to classify clusters, and differential analysis was performed on clusters to obtain inter-cluster DEGs. Asthma-related module was screened by weighted gene co-expression network analysis. Then, DEGs between asthma and control samples, inter-cluster DEGs and asthma-related module were subjected to venn analysis for obtaining candidate genes. The last absolute shrinkage and selection operator and support vector machines were respectively applied to the candidate genes to screen for feature genes, and functional enrichment analysis was performed. Finally, a competition endogenetic RNA network was constructed and drug sensitivity analysis was conducted. There were 438 DEGs (183 up-regulated and 255 down-regulated) between asthma and control samples. 359 inter-cluster DEGs (158 up-regulated and 201 down-regulated) were obtained by screening. Then, the black module was significantly and strongly correlated with asthma. The venn analysis yielded 88 candidate genes. 9 feature genes (NAV3, ITGA10, SYT4, NOX1, SNTG2, RNF182, UPK1B, POSTN, SHISA2) were screened and they were involved in proteasome, dopaminergic synapse etc. Besides, 4 mRNAs, 5 miRNAs, and 2 lncRNAs collectively formed competition endogenetic RNA regulatory network, which included RNF182-hsa-miR-455-3p-LINC00319 and so on. The predicted therapeutic drug network map contained NAV3-bisphenol A and other relationship pairs. The study investigated the potential molecular mechanisms of NAV3, ITGA10, SYT4, NOX1, SNTG2, RNF182, UPK1B, POSTN, SHISA2 in airway epithelial cells of asthmatic patients through bioinformatics analysis, providing a reference for the research of asthma and ferroptosis.

Ferroptosis-related genes are involved in asthma and regulate the immune microenvironment

Background: Asthma was a chronic inflammatory illness driven by complicated genetic regulation and environmental exposure. The complex pathophysiology of asthma has not been fully understood. Ferroptosis was involved in inflammation and infection. However, the effect of ferroptosis on asthma was still unclear. The study was designed to identify ferroptosis-related genes in asthma, providing potential therapeutic targets. Methods: We conducted a comprehensive analysis combined with WGCNA, PPI, GO, KEGG, and CIBERSORT methods to identify ferroptosis-related genes that were associated with asthma and regulated the immune microenvironment in GSE147878 from the GEO. The results of this study were validated in GSE143303 and GSE27066, and the hub genes related to ferroptosis were further verified by immunofluorescence and RT-qPCR in the OVA asthma model. Results: 60 asthmatics and 13 healthy controls were extracted for WGCNA. We found that genes in the black module (r = -0.47, p < 0.05) and magenta module (r = 0.51, p < 0.05) were associated with asthma. CAMKK2 and CISD1 were discovered to be ferroptosis-related hub genes in the black and magenta module, separately. We found that CAMKK2 and CISD1 were mainly involved in the CAMKK-AMPK signaling cascade, the adipocytokine signaling pathway, the metal cluster binding, iron-sulfur cluster binding, and 2 iron, 2 sulfur cluster binding in the enrichment analysis, which was strongly correlated with the development of ferroptosis. We found more infiltration of M2 macrophages and less Tregs infiltration in the asthma group compared to healthy controls. In addition, the expression levels of CISD1 and Tregs were negatively correlated. Through validation, we found that CAMKK2 and CISD1 expression were upregulated in the asthma group compared to the control group and would inhibit the occurrence of ferroptosis. Conclusion: CAMKK2 and CISD1 might inhibit ferroptosis and specifically regulate asthma. Moreover, CISD1 might be tied to the immunological microenvironment. Our results could be useful to provide potential immunotherapy targets and prognostic markers for asthma.

The Emerging Role of Autophagy as a Target of Environmental Pollutants: An Update on Mechanisms

Autophagy is an evolutionarily conserved cellular system crucial for cellular homeostasis that protects cells from a broad range of internal and extracellular stresses. Autophagy decreases metabolic load and toxicity by removing damaged cellular components. Environmental contaminants, particularly industrial substances, can influence autophagic flux by enhancing it as a protective response, preventing it, or converting its protective function into a pro-cell death mechanism. Environmental toxic materials are also notorious for their tendency to bioaccumulate and induce pathophysiological vulnerability. Many environmental pollutants have been found to influence stress which increases autophagy. Increasing autophagy was recently shown to improve stress resistance and reduce genetic damage. Moreover, suppressing autophagy or depleting its resources either increases or decreases toxicity, depending on the circumstances. The essential process of selective autophagy is utilized by mammalian cells in order to eliminate particulate matter, nanoparticles, toxic metals, and smoke exposure without inflicting damage on cytosolic components. Moreover, cigarette smoke and aging are the chief causes of chronic obstructive pulmonary disease (COPD)-emphysema; however, the disease's molecular mechanism is poorly known. Therefore, understanding the impacts of environmental exposure via autophagy offers new approaches for risk assessment, protection, and preventative actions which will counter the harmful effects of environmental contaminants on human and animal health.

Ferroptosis triggers airway inflammation in asthma

Ferroptosis is a regulatory cell death characterized by intracellular iron accumulation and lipid peroxidation that leads to oxidative stress. Many signaling pathways such as iron metabolism, lipid metabolism, and amino acid metabolism precisely regulate the process of ferroptosis. Ferroptosis is involved in a variety of lung diseases, such as acute lung injury, chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis. Increasing studies suggest that ferroptosis is involved in the development of asthma. Ferroptosis plays an important role in asthma. Iron metabolism disorders, lipid peroxidation, amino acid metabolism disorders lead to the occurrence of ferroptosis in airway epithelial cells, and then aggravate clinical symptoms in asthmatic patients. Moreover, several regulators of ferroptosis are involved in the pathogenesis of asthma, such as Nrf2, heme oxygenase-1, mevalonate pathway, and ferroptosis inhibitor protein 1. Importantly, ferroptosis inhibitors improve asthma. Thus, the pathogenesis of ferroptosis and its contribution to the pathogenesis of asthma help us better understand the occurrence and development of asthma, and provide new directions in asthma treatment. This article aimed to review the role and mechanism of ferroptosis in asthma, describing the relationship between ferroptosis and asthma based on signaling pathways and related regulatory factors. At the same time, we summarized current observations of ferroptosis in eosinophils, airway epithelial cells, and airway smooth muscle cells in asthmatic patients.