Induction of ferroptosis-like cell death of eosinophils exerts synergistic effects with glucocorticoids in allergic airway inflammation

Advances in the study of ferroptosis and its relationship to autoimmune diseases

Ferroptosis represents a novel mode of programmed cell death characterized by the intracellular accumulation of iron and lipid peroxidation, culminating in oxidative stress and subsequent cell demise. Mounting evidence demonstrates that ferroptosis contributes significantly to the onset and progression of diverse pathological conditions and diseases, including infections, neurodegenerative disorders, tissue ischemia-reperfusion injury, and immune dysregulation. Recent investigations have underscored the pivotal role of ferroptosis in the pathogenesis of rheumatoid arthritis, ulcerative colitis, systemic lupus erythematosus, and asthma. This review provides a comprehensive overview of the current understanding of the regulatory mechanisms governing ferroptosis, particularly its interplay with iron, lipid, and amino acid metabolism. Furthermore, we explore the implications of ferroptosis in autoimmune diseases and deliberate on its potential as a promising therapeutic target for diverse autoimmune disorders.

NLRP3 regulates ferroptosis via the JAK2/STAT3 pathway in asthma inflammation: Insights from in vivo and in vitro studies

BACKGROUND

Ferroptosis, an iron-dependent form of cell death, plays a pivotal role in the pathologic progression of asthma. Electroacupuncture (EA) has demonstrated considerable efficacy in mitigating asthma airway inflammation, although its underlying mechanisms remain partially elucidated.

METHODS

We investigated the regulatory effect of NLRP3 on ferroptosis using a lipopolysaccharide (LPS)-induced inflammation model in BEAS-2B cells, where NLRP3 expression was modulated with si-RNA and overexpression plasmids. The levels of inflammatory cytokines TNF-α, IL-1β, and IL-6 were quantified. We also assessed NLRP3 and JAK2/STAT3 pathway-related proteins, and evaluated lipid peroxidation, mitochondrial membrane potential (ΔΨm), and antioxidant system functionality. In vivo, we examined the impact of EA on ferroptosis and airway inflammation by modulating NLRP3 activation. Asthma inflammation severity was evaluated using H&E, Masson, and PAS staining, alongside ELISA. NLRP3 and JAK2/STAT3 pathway-related proteins, as well as ferroptosis indicators, were also analyzed. The mechanism by which NLRP3 activates ferroptosis was investigated through in vitro assays.

RESULTS

LPS exposure resulted in increased intracellular inflammatory cytokines, and activation of the NLRP3 and JAK2/STAT3 pathways, leading to enhanced lipid peroxidation, decreased ΔΨm, and disruption of antioxidant system balance, ultimately inducing ferroptosis. Si-NLRP3 countered the effects of LPS, whereas oe-NLRP3 exacerbated symptoms. In vivo studies revealed that EA reduced airway inflammation, inhibited NLRP3 activation, and decreased phosphorylation of JAK2/STAT3, effectively lowering ferroptosis-related indicators. Utilizing JAK2/STAT3 activators and inhibitors, we confirmed that NLRP3 mediates ferroptosis via the JAK2/STAT3 pathway.

CONCLUSIONS

EA alleviates HDM-induced asthma, primarily through the inhibition of NLRP3 activation, which modulates the JAK2/STAT3 pathway and mediates ferroptosis.

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.

Emerging insights: miRNA modulation of ferroptosis pathways in lung cancer

The newly discovered programmed iron-dependent necrosis, ferroptosis, is a novel pathway that is controlled by iron-dependent lipid peroxidation and cellular redox changes. It can be triggered intrinsically by low antioxidant enzyme activity or extrinsically by blocking amino acid transporters or activating iron transporters. The induction of ferroptosis involves the activation of specific proteins, suppression of transporters, and increased endoplasmic reticulum (ER) stress (a condition in which the ER, a crucial organelle involved in protein folding and processing, becomes overwhelmed by an accumulation of misfolded or unfolded proteins. This situation disrupts the normal functioning of the ER, leading to a cellular stress response known as the unfolded protein response), leading to lipid peroxidation byproduct accumulation and toxic reactive oxygen species (ROS), which are highly reactive molecules derived from diatomic oxygen and include various forms such as superoxide (O₂⁻), hydroxyl radicals (•OH), and hydrogen peroxide (H₂O₂). Ferroptosis is closely associated with signaling molecules in lung cancer, including epidermal growth factor receptor (EGFR), mitogen-activated protein kinase (MAPK), hypoxia-inducible factor 1-alpha (HIF-1α), and P53, and is regulated by epigenetic factors such as microRNAs (miRNAs). miRNAs are small non-coding RNA molecules that regulate gene expression by binding to target messenger RNAs (mRNAs), leading to translational repression or degradation. Several miRNAs have been found to modulate ferroptosis by targeting key genes involved in iron metabolism, lipid peroxidation, and antioxidant defense pathways. The research on ferroptosis has expanded to target its role in lung cancer treatment and resistance prevention. This review encapsulates the significance of ferroptosis in lung cancer. Understanding the mechanisms and implications of ferroptosis in lung cancer cells may lead to targeted therapies exploiting cancer cell vulnerabilities to ferroptosis Also, improving treatment outcomes, and overcoming resistance.

Ferroptosis in health and disease

Ferroptosis is a pervasive non-apoptotic form of cell death highly relevant in various degenerative diseases and malignancies. The hallmark of ferroptosis is uncontrolled and overwhelming peroxidation of polyunsaturated fatty acids contained in membrane phospholipids, which eventually leads to rupture of the plasma membrane. Ferroptosis is unique in that it is essentially a spontaneous, uncatalyzed chemical process based on perturbed iron and redox homeostasis contributing to the cell death process, but that it is nonetheless modulated by many metabolic nodes that impinge on the cells' susceptibility to ferroptosis. Among the various nodes affecting ferroptosis sensitivity, several have emerged as promising candidates for pharmacological intervention, rendering ferroptosis-related proteins attractive targets for the treatment of numerous currently incurable diseases. Herein, the current members of a Germany-wide research consortium focusing on ferroptosis research, as well as key external experts in ferroptosis who have made seminal contributions to this rapidly growing and exciting field of research, have gathered to provide a comprehensive, state-of-the-art review on ferroptosis. Specific topics include: basic mechanisms, in vivo relevance, specialized methodologies, chemical and pharmacological tools, and the potential contribution of ferroptosis to disease etiopathology and progression. We hope that this article will not only provide established scientists and newcomers to the field with an overview of the multiple facets of ferroptosis, but also encourage additional efforts to characterize further molecular pathways modulating ferroptosis, with the ultimate goal to develop novel pharmacotherapies to tackle the various diseases associated with - or caused by - ferroptosis.

Integrative analysis of network pharmacology and proteomics reveal the protective effect of Xiaoqinglong Decotion on neutrophilic asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoqinglong Decotion (XQLD) is a commonly used Chinese herbal formula in clinical practice, especially for allergic diseases such as asthma. However, its intrinsic mechanism for the treatment of neutrophilic asthma (NA) remains unclear.

AIM OF THE STUDY

The aim of this study was to evaluate the efficacy and potential mechanisms of XQLD on NA using network pharmacology and in vivo experiments.

MATERIALS AND METHODS

First, the active compounds, potential targets and mechanisms of XQLD against NA were initially elucidated by network pharmacology. Then, OVA/CFA-induced NA mice were treated with XQLD to assess its efficacy. Proteins were then analyzed and quantified using a Tandem Mass Tags approach for differentially expressed proteins (DEPs) to further reveal the mechanisms of NA treatment by XQLD. Finally, the hub genes, critical DEPs and potential pathways were validated.

RESULTS

176 active compounds and 180 targets against NA were identified in XQLD. Protein-protein interaction (PPI) network revealed CXCL10, CX3CR1, TLR7, NCF1 and FABP4 as hub genes. In vivo experiments showed that XQLD attenuated inflammatory infiltrates, airway mucus secretion and remodeling in the lungs of NA mice. Moreover, XQLD significantly alleviated airway neutrophil inflammation in NA mice by decreasing the expression of IL-8, MPO and NE. XQLD also reduced the levels of CXCL10, CX3CR1, TLR7, NCF1 and FABP4, which are closely associated with neutrophil inflammation. Proteomics analysis identified 28 overlapping DEPs in the control, NA and XQLD groups, and we found that XQLD inhibited ferroptosis signal pathway (elevated GPX4 and decreased ASCL3) as well as the expression of ARG1, MMP12 and SPP1, while activating the Rap1 signaling pathway.

CONCLUSION

This study revealed that inhibition of ARG1, MMP12 and SPP1 expression as well as ferroptosis pathways, and activation of the Rap1 signaling pathway contribute to the therapeutic effect of XQLD on NA.

Identification of mitochondria-related biomarkers in childhood allergic asthma

BACKGROUND

The mechanism of mitochondria-related genes (MRGs) in childhood allergic asthma (CAS) was unclear. The aim of this study was to find new biomarkers related to MRGs in CAS.

METHODS

This research utilized two CAS-related datasets (GSE40888 and GSE40732) and extracted 40 MRGs from the MitoCarta3.0 Database. Initially, differential expression analysis was performed on CAS and control samples in the GSE40888 dataset to obtain the differentially expressed genes (DEGs). Differentially expressed MRGs (DE-MRGs) were obtained by overlapping the DEGs and MRGs. Protein protein interactions (PPI) network of DE-MRGs was created and the top 10 genes in the degree ranking of Maximal Clique Centrality (MCC) algorithm were defined as feature genes. Hub genes were obtained from the intersection genes from the Least absolute shrinkage and selection operator (LASSO) and EXtreme Gradient Boosting (XGBoost) algorithms. Additionally, the expression validation was conducted, functional enrichment analysis, immune infiltration analysis were finished, and transcription factors (TFs)-miRNA-mRNA regulatory network was constructed.

RESULTS

A total of 1505 DEGs were obtained from the GSE40888, and 44 DE-MRGs were obtained. A PPI network based on these 44 DE-MRGs was created and revealed strong interactions between ADCK5 and MFN1, BNIP3 and NBR1. Four hub genes (NDUFAF7, MTIF3, MRPS26, and NDUFAF1) were obtained by taking the intersection of genes from the LASSO and XGBoost algorithms based on 10 signature genes which obtained from PPI. In addition, hub genes-based alignment diagram showed good diagnostic performance. The results of Gene Set Enrichment Analysis (GSEA) suggested that hub genes were closely related to mismatch repair. The B cells naive cells were significantly expressed between CAS and control groups, and MTIF3 was most strongly negatively correlated with B cells naive. In addition, the expression of MTIF3 and MRPS26 may have influenced the inflammatory response in CAS patients by affecting mitochondria-related functions. The quantitative real-time polymerase chain reaction (qRT‒PCR) results showed that four hub genes were all down-regulated in the CAS samples.

CONCLUSION

NDUFAF7, MTIF3, MRPS26, and NDUFAF1 were identified as an MRGs-related biomarkers in CAS, which provides some reference for further research on CAS.

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: Iron-mediated cell death linked to disease pathogenesis

Ferroptosis is an iron-mediated regulatory cell death pattern characterized by oxidative damage. The molecular regulating mechanisms are related to iron metabolism, lipid peroxidation, and glutathione metabolism. Additionally, some immunological signaling pathways, such as the cyclic GMP-AMP synthase-stimulator ofinterferon genes axis, Janus kinase-signal transducer and activator of transcription 1 axis, and transforming growth factor beta 1-Smad3 axis may also participate in the regulation of ferroptosis. Studies have shown that ferroptosis is closely related to many diseases such as cancer, neurodegenerative diseases, inflammatory diseases, and autoimmune diseases. Considering the pivotal role of ferroptosis-regulating signaling in the pathogenesis of diverse diseases, the development of ferroptosis inducers or inhibitors may have significant clinical potential for the treatment of the aforementioned conditions.

Jiangqi Pingxiao formula regulates dendritic cell apoptosis in an autophagy-dependent manner through the AMPK/mTOR pathway in a murine model of OVA-induced asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Allergic asthma is a recurring respiratory condition that typically manifests during childhood or adolescence. It is characterized by a dominant type II immune response triggered by the identification and capturing of inhaled allergens by dendritic cells (DCs). Jiangqi Pingxiao Formula (JQPXF), a prescription medicine used for the treatment of pediatric asthma, has been clinically proven to be both safe and effective. However, its mechanism of action in the treatment of asthma has not been fully been fully elucidated. Recent research suggests that several natural compounds have the potential to target dendritic cells (DCs) and alleviate ovalbumin (OVA)-induced asthma, which may also be found within JQPXF.

AIM OF THE STUDY

This study aimed to elucidate the effect of JQPXF on OVA-induced asthma model and its molecular mechanism targeting DCs.

MATERIALS AND METHODS

The main constituents of JQPXF were analyzed by ultra performance liquid chromatography (UPLC). An asthma model was established by OVA. Hematoxylin-eosin staining and measurement of respiratory function was used to evaluate the treatment effect of JQPXF on asthmatic mice. Cytokine (IL-5, IL-13 and IgE) concentrations were determined by enzyme-linked immunosorbent assay (ELISA). Flow cytometry was employed to evaluate inflammatory cell infiltration (T helper 2 cells and DCs) in vivo and DC survival in vivo and vitro. Western blot and immunofluorescence were used to verify the molecular mechanisms.

RESULTS

The results suggest that JQPXF can ameliorate pathological conditions and improve lung function in asthmatic mice, as well as the Th2 cells. Treatment with JQPXF significantly reduced the number of DCs and increased the number of Propidium iodide+ (PI) DCs. Furthermore, JQPXF upregulated protein levels of the pro-apoptotic factors Cleaved-caspase-3 and Bax, while downregulating the anti-apoptotic factor Bcl-2. Simultaneously, JQPXF increased autophagy levels by facilitating p62 degradation and promoting translation from LC3B I to LC3B II of DCs in vitro, as well as reducing the integrated optical density (IOD) of p62 within the CD11c-positive area in the lung. 3-Methyladenine (3-MA) was used to block autophagic flux and the apoptotic effect of JQPXF on DCs was abolished in vitro, with the number of DCs decreased by JQPXF being reversed in vivo. We further investigated the upstream key regulator of autophagy, the AMPK/mTOR pathway, and found that JQPXF increased AMPK phosphorylation while decreasing mTOR phosphorylation levels. Additionally, we employed Compound C (CC) as an AMPK inhibitor to inhibit this signaling pathway, and our findings revealed that both autophagic flux and apoptotic levels in DCs were abolished in vitro.

CONCLUSIONS

In summary, we have demonstrated that JQPXF could alleviate type II inflammation in an asthmatic model by promoting the apoptosis of DCs through an autophagy-dependent mechanism, achieved by regulating the AMPK/mTOR signaling pathway.

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.

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.

Neferine Attenuates HDM-Induced Allergic Inflammation by Inhibiting the Activation of Dendritic Cell

House dust mite (HDM) acts as an environmental antigen that might cause chronic allergic diseases. Neferine (NEF) shows anti-inflammation therapeutic effects. This study is to explore the protection role of NEF against HDM-induced allergic inflammation. HDM-induced allergic asthmatic C57BL/6J mice models were established. Differential histological staining was used to analyze lung tissue pathological scores. Flow cytometry was used to analyze subtypes and biomarker expression of immune cells. RT-PCR and ELISA were used to test cytokines-related gene and/or protein expression levels. Western blot was performed to investigate the signaling pathway that mediates allergic inflammation from mice lung tissue and bone marrow-derived dendritic cells (BMDCs). H&E and PAS staining results indicate NEF significantly attenuated inflammatory index and the percentage of goblet cells in the lung tissue induced by HDM. The HDM-elevated TH2 and TH17 cells were significantly decreased by NEF; inflammatory cytokines Il-4, Il-13 and Il-17 were dramatically downregulated in the NEF plus HDM group compared with HDM alone. CD40+ and CD86+ DCs, eosinophils and mast cells, and ILC2 cells were decreased by NEF which was elevated under HDM stimulation. In vivo and ex vivo investigations indicated NEF can attenuate the activated NF-κB signaling induced by HDM is involved in allergic inflammatory immune response and regulates cytokines-related gene expression. HDM-activated DCs promoted differentiation of TH2 and TH17 cells but were attenuated by NEF. This study suggests NEF interrupts the overexpression of some cytokines released by DCs, TH2, and TH17 cells; NEF attenuates HDM-induced allergic inflammation via inhibiting NF-κB signaling of DCs.

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.

Identification of Ferroptosis-related potential biomarkers and immunocyte characteristics in Chronic Thromboembolic Pulmonary Hypertension via bioinformatics analysis

BACKGROUND

Chronic Thromboembolic Pulmonary Hypertension (CTEPH) is a form of pulmonary hypertension with a high mortality rate. A new type of iron-mediated cell death is Ferroptosis, which is characterized by the accumulation of lethal iron ions and lipid peroxidation leading to mitochondrial atrophy and increased mitochondrial membrane density. Now, there is a lack of Ferroptosis-related biomarkers (FRBs) associated with pathogenic process of CTEPH.

METHODS

The differentially expressed genes (DEGs) of CTEPH were obtained by GEO2R. Genes related to Ferroptosis were obtained from FerrDb database. The intersection of Ferroptosis and DEGs results in FRBs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed in Database for Annotation, Visualization and Integrated Discovery (DAVID) database. The optimal potential biomarkers for CTEPH were analyzed by least absolute shrinkage and selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE) machine learning. The four hub genes were verified from the Gene Expression Omnibus (GEO) dataset GSE188938. Immune infiltration was analyzed by CIBERSORT. SPSS software was used to analyze the Spearman rank correlation between FRBs identified and infiltration-related immune cells, and p < 0.05 was considered as statistically significant.

RESULTS

In this study, potential genetic biomarkers associated with Ferroptosis in CTEPH were investigated and explored their role in immune infiltration. In total, we identified 17 differentially expressed Ferroptosis-associated genes by GEOquery package. The key FRBs including ARRDC3, HMOX1, BRD4, and YWHAE were screened using Lasso and SVM-RFE machine learning methods.Through gene set GSE188938 verification, only upregulation of gene ARRDC3 showed statistical difference. In addition, immune infiltration analysis using the CIBERSORT algorithm revealed the infiltration of Eosinophils and Neutrophils in CTEPH samples was less than that in the control group. And correlation analysis revealed that ARRDC3 was positively correlated with T cells follicular helper (r = 0.554, p = 0.017) and negatively correlated with Neutrophils (r = -0.47, p = 0.049).

CONCLUSIONS

In conclusion, ARRDC3 upregulation with different immune cell infiltration were involved in the development of CTEPH. ARRDC3 might a potential Ferroptosis-related biomarker for CTEPH treatment. This study provided a new insight into pathogenesis CTEPH.

Role of ferroptosis in effects of anesthetics on multiple organ diseases: A literature review

Anesthesiologists are often faced with patients combined with a series of organ injuries, such as acute lung injury, myocardial ischemia-reperfusion injury, and neurodegenerative diseases. With the in-depth study of these diseases, we are more aware of the choice and rational use of anesthetics for the prognosis of these patients. Ferroptosis is a new type of programmed cell death. This unique pattern of cell death, driven by an imbalance between oxides and antioxidants, is regulated by multiple cellular metabolic events, including redox homeostasis, iron handling, mitochondrial activity, and lipids peroxidation. Numerous studies confirmed that anesthetics modulate ferroptosis by interfering its machineries such as cystine-import-glutathione-glutathione peroxidase 4 axis, Heme oxygenase 1, nuclear factor erythroid 2-related factor 2, and iron homeostasis system. In this literature review, we systemically illustrated possible involvement of ferroptosis in effects of anesthetics and adjuvant drugs on multiple organ diseases, hoping our work may serve as a basis for further studies on regulating ferroptosis through anesthetics related pharmacological modulation and promoting the rational use of anesthetics.

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.

Inhibition of CREB promotes glucocorticoids action on airway inflammation in pediatric asthma by promoting ferroptosis of eosinophils

BACKGROUND

Pediatric asthma is a common chronic disease of childhood with airway inflammation. Cyclic adenosine monophosphate response element binding protein (CREB) plays a significant role in the transcription of proinflammatory genes, but its role in pediatric asthma has remained unclear. Herein, we investigated the functions of CREB in pediatric asthma.

METHODS

Eosinophils were purified from the peripheral blood of interleukin 5 (IL5) transgenic (IL5T) neonatal mice. The contents of CREB, long-chain fatty-acid-CoA ligase 4, transferrin receptor protein 1, ferritin heavy chain 1, and glutathione peroxidase 4 in eosinophils were examined by Western blot analysis. The viability of eosinophils, and the mean fluorescence intensity of Siglec F, C-C motif chemokine receptor 3 (CCR3), and reactive oxygen species were examined by flow cytometry. The concentration of iron in eosinophils was assessed by a commercial kit. The contents of malondialdehyde, glutathione, glutathione peroxidase, IL-5, and IL-4 were discovered by enzyme-linked-immunosorbent serologic assay. The C57BL/6 mice were randomly divided into four groups: sham, ovalbumin (OVA), OVA+Ad-shNC, and OVA+Ad-shCREB. The bronchial and alveolar structures were evaluated by hematoxylin and eosin staining. Leukocytes and eosinophils in the blood were measured using a HEMAVET 950.

RESULTS

The abundance of CREB in eosinophils was enhanced by CREB overexpression vector transfection, but reduced by short hairpin (sh)CREB transfection. Downregulation of CREB triggered the cell death of eosinophils. Knockdown of CREB could obviously contribute to ferroptosis of eosinophils. In addition, downregulation of CREB facilitated dexamethasone (DXMS, a type of glucocorticoid)-induced eosinophils death. Moreover, we established an asthma mouse model by OVA treatment. The CREB was upregulated in OVA group mice, but Ad-shCREB treatment obviously downregulated CREB level. Downregulation of CREB diminished OVA-induced asthmatic airway inflammation by reducing the number of inflammatory cells and the levels of proinflammatory factors. Downregulated CREB enhanced the anti-inflammatory effect of DXMS in OVA-induced mice.

CONCLUSION

Inhibition of CREB promoted the effect of glucocorticoids on airway inflammation in pediatric asthma through promoting ferroptosis of eosinophils.

Programmed Cell Death in Asthma: Apoptosis, Autophagy, Pyroptosis, Ferroptosis, and Necroptosis

Bronchial asthma is a complex heterogeneous airway disease, which has emerged as a global health issue. A comprehensive understanding of the different molecular mechanisms of bronchial asthma may be an efficient means to improve its clinical efficacy in the future. Increasing research evidence indicates that some types of programmed cell death (PCD), including apoptosis, autophagy, pyroptosis, ferroptosis, and necroptosis, contributed to asthma pathogenesis, and may become new targets for future asthma treatment. This review briefly discusses the molecular mechanism and signaling pathway of these forms of PCD focuses on summarizing their roles in the pathogenesis and treatment strategies of asthma and offers some efficient means to improve clinical efficacy of therapeutics for asthma in the near future.

The crosslinks between ferroptosis and autophagy in asthma

Autophagy is an evolutionarily conserved cellular process capable of degrading various biological molecules and organelles via the lysosomal pathway. Ferroptosis is a type of oxidative stress-dependent regulated cell death associated with the iron accumulation and lipid peroxidation. The crosslinks between ferroptosis and autophagy have been focused on since the dependence of ferroptosis on autophagy was discovered. Although the research and theories on the relationship between autophagy and ferroptosis remain scattered and fragmented, the crosslinks between these two forms of regulated cell death are closely related to the treatment of various diseases. Thereof, asthma as a chronic inflammatory disease has a tight connection with the occurrence of ferroptosis and autophagy since the crosslinked signal pathways may be the crucial regulators or exactly regulated by cells and secretion in the immune system. In addition, non-immune cells associated with asthma are also closely related to autophagy and ferroptosis. Further studies of cross-linking asthma inflammation with crosslinked signaling pathways may provide us with several key molecules that regulate asthma through specific regulators. The crosslinks between autophagy and ferroptosis provide us with a new perspective to interpret and understand the manifestations of asthma, potential drug discovery targets, and new therapeutic options to effectively intervene in the imbalance caused by abnormal inflammation in asthma. Herein, we introduce the main molecular mechanisms of ferroptosis, autophagy, and asthma, describe the role of crosslinks between ferroptosis and autophagy in asthma based on their common regulatory cells or molecules, and discuss potential drug discovery targets and therapeutic applications in the context of immunomodulatory and symptom alleviation.

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.

Regulation of ferroptosis and ACSL4-15LO1 pathway contributed to the anti-asthma effect of acupuncture

Acupuncture has been frequently used in China for the treatment asthma for thousands of years. Ferroptosis was recently revealed to be involved in several pathological conditions including asthma. However, the detailed links between ferroptosis and airway inflammation in asthma, as well as the detailed regulation of acupuncture on these disorders remains unclear. Our results demonstrated that the non-haem Fe²⁺ level increased markedly in the lung tissue of mouse asthma model, and positively correlated with R_L and IL-4 level in BALF. Furthermore, lipid peroxidation markers MDA and GSSG increased remarkably in OVA-induced experimental asthma mice. Up-regulation of lipid peroxidation associated proteins ACSL4 and15-LO1 was also observed in OVA-induced experimental asthma mice. To demonstrate the role of ferroptosis in asthma and the effect of acupuncture on these disorders, ferroptosis-induction agent erastin and ferroptosis-inhibition agent fer-1 were used, and our data demonstrated that erastin could augment lung inflammation and lipid peroxidation in OVA induced asthma model. Fer-1 was able to relieve AHR, lung inflammation, non-haem Fe²⁺ level, lipid peroxidation and ferroptosis related pathway ACSL4-15LO1 in OVA-induced experimental asthma mice. Acupuncture treatment alleviated R_L, lung inflammation as well as type 2 cytokines IL-4 and IL-13 levels induced by OVA inhalation. What's more, acupuncture significantly reduced the MDA and GSSG levels, the non-haem Fe²⁺ level and ACSL4-15-LO1 proteins expression. Acupuncture also relieved erastin-induced exacerbation in lung inflammation and lipid peroxidation in ferroptosis. Acupuncture treatment could relieve ferroptosis related exacerbation in airway inflammation. Our study provided insights into the underlying mechanisms for the protective effects of acupuncture and highlighted a therapeutic potential of acupuncture treatment in the attenuation of lipid peroxidation and ferroptosis in asthma.

Pharmacological Induction of Granulocyte Cell Death as Therapeutic Strategy

Apoptosis is central for the maintenance of health. In the immune system, apoptosis guarantees proper development of immune cells and shutdown of immune reactions by the coordinated elimination of activated immune cells. Limitation of the life span of granulocytes is important, as overactivation of these cells is associated with chronic inflammation and collateral tissue damage. Consequently, targeted induction of granulocyte apoptosis may be beneficial in the course of respective immune disorders. Anti-inflammatory drugs such as glucocorticoids and monoclonal antibodies against IL-5Rα exert their function in part by triggering eosinophil apoptosis. Agonistic antibodies targeting Siglec-8 or death receptors are tested (pre)clinically. Moreover, a new class of inhibitors targeting antiapoptotic BCL-2 proteins shows great promise for anticancer treatments. Because of their specificity and tolerable side effects, these so-called BH3 mimetics may be worthwhile to evaluate in inflammatory disorders. Here, we review past and recent data on pharmacological apoptosis induction of granulocytes and highlight respective therapeutic potential.

Alarmins and MicroRNAs, a New Axis in the Genesis of Respiratory Diseases: Possible Therapeutic Implications

It is well ascertained that airway inflammation has a key role in the genesis of numerous respiratory pathologies, including asthma, chronic obstructive pulmonary disease, and acute respiratory distress syndrome. Pulmonary tissue inflammation and anti-inflammatory responses implicate an intricate relationship between local and infiltrating immune cells and structural pulmonary cells. Alarmins are endogenic proteins discharged after cell injury in the extracellular microenvironment. The purpose of our review is to highlight the alterations in respiratory diseases involving some alarmins, such as high mobility group box 1 (HMGB1) and interleukin (IL)-33, and their inter-relationships and relationships with genetic non-coding material, such as microRNAs. The role played by these alarmins in some pathophysiological processes confirms the existence of an axis composed of HMGB1 and IL-33. These alarmins have been implicated in ferroptosis, the onset of type 2 inflammation and airway alterations. Moreover, both factors can act on non-coding genetic material capable of modifying respiratory function. Finally, we present an outline of alarmins and RNA-based therapeutics that have been proposed to treat respiratory pathologies.

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.

Quercetin alleviates ferroptosis accompanied by reducing M1 macrophage polarization during neutrophilic airway inflammation

Ferroptosis is a kind of regulated cell death, supporting the pathological process of lung inflammation, including asthma. Quercetin (QCT), a kind of natural dietary flavonoid, exerts anti-inflammatory and anti-ferroptosis effects in various diseases. However, the role of QCT in ferroptosis-associated airway inflammation of neutrophilic asthma remains to be described. Our study aimed to investigate the therapeutic effects of QCT on neutrophilic airway inflammation of asthma. Ferrostatin-1 (Fer-1), as a kind of ferroptosis inhibitor, was used to demonstrate whether neutrophilic airway inflammation of asthma relied on ferroptosis. In our study, the alleviation effect of QCT on neutrophilic airway inflammation was similar to Fer-1. Moreover, the significantly decreased levels of ferroptosis anti-oxidant protein (GPX4 and SLC7A11), increased malondialdehyde (MDA) levels, upregulated levels of 4-hydroxynonenal (4-HNE) expression by immunohistochemistry, and distorted mitochondria morphological changes in the lung tissues suggested lung ferroptosis in neutrophilic airway inflammation, which could be reversed by QCT treatment. In vitro experiments showed that QCT reduced LPS-induced ferroptosis through upregulating cell viability and levels of ferroptosis anti-oxidant protein (SLC7A11 and GPX4), reducing inflammatory cytokines, and decreasing the levels of MDA. Furthermore, ferroptosis was accompanied by enhancing M1 phenotype in neutrophilic airway inflammation, and QCT suppressed ferroptosis by inhibiting the pro-inflammatory M1 profile in vitro and in vivo, just as Fer-1 did. In conclusion, our study found that QCT ameliorated ferroptosis-associated neutrophilic airway inflammation accompanied by inhibiting M1 macrophage polarization. QCT may be a promising ferroptosis inhibitor for neutrophilic airway inflammation.

Ferroptosis contribute to hepatic stellate cell activation and liver fibrogenesis

Ferroptosis is a widely known regulator of cell death in connection with the redox state as a consequence of the depletion of glutathione or accumulation of lipid peroxidation. Hepatic stellate cells (HSCs) play a pivotal role in the progression of hepatic fibrosis by increasing the production and secretion of the extracellular matrix. However, the role of ferroptosis in HSC activation and liver fibrogenesis has not been clearly elucidated. The ferroptosis inducer RAS-selective lethal 3 (RSL3) or erastin treatment in HSCs caused cell death. This effect was suppressed only after exposure to ferroptosis inhibitors. We observed induction of ferroptosis by RSL3 treatment in HSCs supported by decreased glutathione peroxidase 4, glutathione deficiency, reactive oxygen species generation, or lipid peroxidation. Interestingly, RSL3 treatment upregulated the expression of plasminogen activator inhibitor-1, a representative fibrogenic marker of HSCs. In addition, treatment with ferroptosis-inducing compounds increased c-JUN phosphorylation and activator protein 1 luciferase activity but did not alter Smad phosphorylation and Smad-binding element luciferase activity. Chronic administration of iron dextran to mice causes ferroptosis of liver in vivo. The expression of fibrosis markers, such as alpha-smooth muscle actin and plasminogen activator inhibitor-1, was increased in the livers of mice with iron accumulation. Hepatic injury accompanying liver fibrosis was observed based on the levels of alanine aminotransferase, aspartate aminotransferase, and hematoxylin and eosin staining. Furthermore, we found that both isolated primary hepatocyte and HSCs undergo ferroptosis. Consistently, cirrhotic liver tissue of patients indicated glutathione peroxidase 4 downregulation in fibrotic region. In conclusion, our results suggest that ferroptosis contribute to HSC activation and the progression of hepatic fibrosis.

Physiological Effects of Ferroptosis on Organ Fibrosis

Ferroptosis is a new type of programmed cell death with unique morphological, biochemical, and genetic features. From the initial study of histomorphology to the exploration of subcellular organelles and even molecular mechanisms, a net connecting ferroptosis and fibrosis is being woven and formed. Inflammation may be the bridge between both processes. In this review, we will discuss the ferroptosis theory and process and the physiological functions of ferroptosis, followed by a description of the pathological effects and the underlying mechanisms of ferroptosis in the pathogenesis of tumorigenesis, ischemic damage, degenerative lesions, autoimmune diseases, and necroinflammation. We then focus on the role of ferroptosis in the fibrosis process in the liver, lung, kidney, heart, and other organs. Although the molecular mechanism of ferroptosis has been explored extensively in the past few years, many challenges remain to be resolved to translate this information into antifibrotic practice, which is becoming a promising new direction in the field of fibrotic disease prevention and treatment.

Artesunate: A review of its therapeutic insights in respiratory diseases

BACKGROUND

Artesunate, as a semi-synthetic artemisinin derivative of sesquiterpene lactone, is widely used in clinical antimalarial treatment due to its endoperoxide group. Recent studies have found that artesunate may have multiple pharmacological effects, indicating its significant therapeutic potential in multiple respiratory diseases.

PURPOSE

This review aims to summarize proven and potential therapeutic effects of artesunate in common respiratory disorders.

STUDY DESIGN

This review summarizes the pharmacological properties of artesunate and then interprets the function of artesunate in various respiratory diseases in detail, such as bronchial asthma, chronic obstructive pulmonary disease, lung injury, lung cancer, pulmonary fibrosis, coronavirus disease 2019, etc., on different target cells and receptors according to completed and ongoing in silico, in vitro, and in vivo studies (including clinical trials).

METHODS

Literature was searched in electronic databases, including Pubmed, Web of Science and CNKI with the primary keywords of 'artesunate', 'pharmacology', 'pharmacokinetics', 'respiratory disorders', 'lung', 'pulmonary', and secondary search terms of 'Artemisia annua L.', 'artemisinin', 'asthma', 'chronic obstructive lung disease', 'lung injury', 'lung cancer', 'pulmonary fibrosis', 'COVID-19' and 'virus' in English and Chinese. All experiments were included. Reviews and irrelevant studies to the therapeutic effects of artesunate on respiratory diseases were excluded. Information was sort out according to study design, subject, intervention, and outcome.

RESULTS

Artesunate is promising to treat multiple common respiratory disorders via various mechanisms, such as anti-inflammation, anti-oxidative stress, anti-hyperresponsiveness, anti-proliferation, airway remodeling reverse, induction of cell death, cell cycle arrest, etc. CONCLUSION: Artesunate has great potential to treat various respiratory diseases.

The link between ferroptosis and airway inflammatory diseases: A novel target for treatment

Ferroptosis is an iron-dependent mode of cell death characterized by intracellular lipid peroxide accumulation and a redox reaction imbalance. Compared with other modes of cell death, ferroptosis has specific biological and morphological features. The iron-dependent lipid peroxidation accumulation is manifested explicitly in the abnormal metabolism of intracellular lipid oxides catalyzed by excessive iron ions with the production of many reactive oxygen species and over-oxidization of polyunsaturated fatty acids. Recent studies have shown that various diseases, which include intestinal diseases and cancer, are associated with ferroptosis, but few studies are related to airway inflammatory diseases. This review provides a comprehensive analysis of the primary damage mechanisms of ferroptosis and summarizes the relationship between ferroptosis and airway inflammatory diseases. In addition to common acute and chronic airway inflammatory diseases, we also focus on the progress of research on COVID-19 in relation to ferroptosis. New therapeutic approaches and current issues to be addressed in the treatment of inflammatory airway diseases using ferroptosis are further proposed.

Liproxstatin-1 alleviates LPS/IL-13-induced bronchial epithelial cell injury and neutrophilic asthma in mice by inhibiting ferroptosis

BACKGROUND AND PURPOSE

Ferroptosis is closely associated with respiratory diseases; however, the relationship between ferroptosis and neutrophilic asthma remains unknown. This study investigated whether Liproxstatin-1 (Lip-1) affects the progression of neutrophilic asthma by inhibiting ferroptosis and inflammatory response, while dissecting the underlying molecular mechanisms.

METHODS

The bronchial epithelial cells (16HBE and BEAS-2B) were administered with lipopolysaccharide (LPS) and interleukin-13 (IL-13) to generate a cell injury model. This cell model was employed to examine the effect of Lip-1 on airway epithelial-associated inflammation and ferroptosis as well as the underlying molecular mechanism. Meanwhile, we evaluated the effects of Lip-1 on neutrophilic asthma and ferroptosis by using the ovalbumin (OVA)/LPS-induced mouse model.

RESULTS

Lip-1 reversed the altered expression of ferroptotic regulators (glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11 (SLC7A11) and prostaglandin-endoperoxide synthase 2 (PTGS2)), attenuated lipid reactive oxygen species (lipid ROS) and ameliorated cell viability in HBE and BEAS-2B cells administered with LPS and IL-13. Moreover, Lip-1 treatment led to a marked reduction in the expression of IL-33, TSLP, IL-8, IL-6, and HMGB1 in the HBE and BEAS-2B cells. In the meantime, administration with Lip-1 markedly relieved OVA/LPS-induced neutrophilic asthma, as indicated by significant improvement in lung pathological changes, airway mucus secretion, inflammation, and ferroptosis.

CONCLUSION

This study provides data suggesting that Lip-1 alleviates neutrophilic asthma in vivo and in vitro through inhibiting ferroptosis, perhaps providing a new strategy for neutrophilic asthma treatment.

Recent advances of eosinophils and its correlated diseases

Eosinophils are differentiated by bone marrow multipotent progenitor cells and are further released into peripheral blood after maturation. Human eosinophils can exhibit unique multi-leaf nuclear morphology, which are filled with cytoplasmic granules that contain cytotoxicity and immune regulatory proteins. In recent years, many studies focused on the origin, differentiation and development process of eosinophils. It has been discovered that the eosinophils have the regulatory functions of innate and adaptive immunity, and can also function in several diseases, including asthma, chronic obstructive pulmonary diseases, acute respiratory distress syndrome, malignant tumors and so on. Hence, the role and effects of eosinophils in various diseases are emphasized. In this review, we comprehensively summarized the development and differentiation process of eosinophils, the research progress of their related cytokines, diseases and current clinical treatment options, and discussed the potential drug target, aiming to provide a theoretical and practical basis for the clinical prevention and treatment of eosinophil-related diseases, especially respiratory diseases. To conclude, the guiding significance of future disease treatment is proposed based on the recent updated understandings into the cell functions of eosinophils.

Sipeimine ameliorates PM2.5-induced lung injury by inhibiting ferroptosis via the PI3K/Akt/Nrf2 pathway: A network pharmacology approach

Fine particulate matter (PM2.5) exposure can cause lung injury and a large number of respiratory diseases. Sipeimine is a steroidal alkaloid isolated from Fritillaria roylei which has been associated with anti-inflammatory, antitussive and antiasthmatic properties. In this study, we explored the potential effects of sipeimine against PM2.5-induced lung injury in Sprague Dawley rats. Sipeimine alleviated lung injury caused by PM2.5 and decreased pulmonary edema, inflammation and the levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the bronchoalveolar lavage fluid. In addition, sipeimine upregulated the glutathione (GSH) expression and downregulated the expression of 4-hydroxynonenal (4-HNE), tissue iron and malondialdehyde (MDA). The downregulation of proteins involved in ferroptosis, including nuclear factor E2-related factor 2 (Nrf2), glutathione peroxidase 4 (GPX4), heme oxygenase-1 (HO-1) and solute carrier family 7 member 11 (SLC7A11) was reversed by sipeimine. The administration of RSL3, a potent ferroptosis-triggering agent, blocked the effects of sipeimine. Using network pharmacology, we found that the effects of sipeimine were presumably mediated through the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway. A PI3K inhibitor (LY294002) blocked the PI3K/Akt signaling pathway and reversed the effects of sipeimine. Overall, this study suggested that the protective effect of sipeimine against PM2.5-induced lung injury was mainly mediated through the PI3K/Akt pathway, ultimately leading to a reduction in ferroptosis.

Multifaceted Roles of Ferroptosis in Lung Diseases

Ferroptosis is a distinct type of programmed cell death (PCD) that depends on iron and is characterized by the accumulation of intracellular iron, exhaustion of glutathione, deactivation of glutathione peroxidase, and promotion of lipid peroxidation. Recently, accumulated investigations have demonstrated that ferroptosis is strongly correlated with the initiation and development of many lung diseases. In this review, we summarized the contribution of ferroptosis to the pathologic process of lung diseases, namely, obstructive lung diseases (chronic obstructive pulmonary disease, asthma, and cystic fibrosis), interstitial lung diseases (pulmonary fibrosis of different causes), pulmonary diseases of vascular origin (ischemia-reperfusion injury and pulmonary hypertension), pulmonary infections (bacteria, viruses, and fungi), acute lung injury, acute respiratory distress syndrome, obstructive sleep apnea, pulmonary alveolar proteinosis, and lung cancer. We also discussed the therapeutic potential of targeting ferroptosis for these lung diseases.

Molecular mechanisms of ferroptosis and their role in inflammation

Ferroptosis is a type of non-apoptotic cell death, which demonstrates a definite iron-dependent expression pattern and is associated with lipid peroxidation. Glutathione peroxidase 4 (GPX4) is a key regulator of ferroptosis. Ferroptosis is involved in the development and progression of various diseases, such as cancer, tissue ischemia-reperfusion injury, neurological diseases, and respiratory diseases. It has been established previously that ferroptotic cells trigger the innate immune system by releasing inflammation-linked damage-related molecules, and immune cells stimulate the inflammatory response by recognizing the operational mechanism of ferroptosis. Some anti-inflammatory drugs have been shown to inhibit ferroptosis in certain cell models. Conversely, some ferroptosis inhibitors also exert anti-inflammatory effects in certain diseases. The present review evaluated the relationship between ferroptosis and inflammation, as well as the underlying internal mechanism, and provided valuable insights into developing novel treatment strategies for inflammatory diseases and cancer.

Research progress on the mechanism of ferroptosis and its clinical application

Ferroptosis is a mode of cell death dependent on iron ions, which is mainly induced by the decrease of the biological activity of glutathione peroxidase or the accumulation of lipid peroxidation and reactive oxygen species (ROS). It is significantly different from autophagy and other forms of cell death in terms of cell morphology and biochemistry. The exact mechanisms of ferroptosis are not clear. More and more studies have shown that various tumor diseases and nervous system diseases are closely related to ferroptosis. The occurrence and development of related diseases can be tolerated by stimulating or inhibiting the occurrence of ferroptosis. Therefore, ferroptosis has occupied a very important position in recent years. This article reviews the discovery process, characteristics, mechanisms, inducers, inhibitors of ferroptosis and its related clinical applications to lay a foundation for follow-up researchers to study ferroptosis and provide some reference value.

Pulmonary Eosinophils at the Center of the Allergic Space-Time Continuum

Eosinophils are typically a minority population of circulating granulocytes being released from the bone-marrow as terminally differentiated cells. Besides their function in the defense against parasites and in promoting allergic airway inflammation, regulatory functions have now been attributed to eosinophils in various organs. Although eosinophils are involved in the inflammatory response to allergens, it remains unclear whether they are drivers of the asthma pathology or merely recruited effector cells. Recent findings highlight the homeostatic and pro-resolving capacity of eosinophils and raise the question at what point in time their function is regulated. Similarly, eosinophils from different physical locations display phenotypic and functional diversity. However, it remains unclear whether eosinophil plasticity remains as they develop and travel from the bone marrow to the tissue, in homeostasis or during inflammation. In the tissue, eosinophils of different ages and origin along the inflammatory trajectory may exhibit functional diversity as circumstances change. Herein, we outline the inflammatory time line of allergic airway inflammation from acute, late, adaptive to chronic processes. We summarize the function of the eosinophils in regards to their resident localization and time of recruitment to the lung, in all stages of the inflammatory response. In all, we argue that immunological differences in eosinophils are a function of time and space as the allergic inflammatory response is initiated and resolved.

Recent Progress of Ferroptosis in Lung Diseases

Ferroptosis is a new form of programmed cell death due to iron-dependent excess accumulation of lipid peroxides and differs from other programmed cell deaths in morphological and biochemical characteristics. The process of ferroptosis is precisely regulated by iron metabolism, lipid metabolism, amino acid metabolism, and numerous signaling pathways, and plays a complex role in many pathophysiological processes. Recent studies have found that ferroptosis is closely associated with the development and progression of many lung diseases, including acute lung injury, pulmonary ischemia-reperfusion injury, lung cancer, chronic obstructive pulmonary disease, and pulmonary fibrosis. Here, we present a review of the main regulatory mechanisms of ferroptosis and its research progress in the pathogenesis and treatment of lung diseases, with the aim of providing new ideas for basic and clinical research of lung-related diseases.

Targeting Ferroptosis for Lung Diseases: Exploring Novel Strategies in Ferroptosis-Associated Mechanisms

Ferroptosis is an iron-dependent regulated necrosis characterized by the peroxidation damage of lipid molecular containing unsaturated fatty acid long chain on the cell membrane or organelle membrane after cellular deactivation restitution system, resulting in the cell membrane rupture. Ferroptosis is biochemically and morphologically distinct and disparate from other forms of regulated cell death. Recently, mounting studies have investigated the mechanism of ferroptosis, and numerous proteins play vital roles in regulating ferroptosis. With detailed studies, emerging evidence indicates that ferroptosis is found in multiple lung diseases, demonstrating that ferroptosis appears to be particularly important for lung diseases. The mounting interest in ferroptosis drugs specifically targeting the ferroptosis mechanism holds substantial therapeutic promise in lung diseases. The present review emphatically summarizes the functions and integrated molecular mechanisms of ferroptosis in various lung diseases, proposing that multiangle regulation of ferroptosis might be a promising strategy for the clinical treatment of lung diseases.

FIN56, a novel ferroptosis inducer, triggers lysosomal membrane permeabilization in a TFEB-dependent manner in glioblastoma

Objective: To explore the anti-tumor effect of FIN56, a novel ferroptosis inducer, on glioblastoma and its underlying mechanisms. Methods: Two human glioblastoma cell lines, LN229 and U118 were applied in this study. Anti-tumor effect was measured by CCK-8 assay, EdU assay and cell cycle analysis. Fluorescent probes, immunofluorescence, plasmid transfection, shRNA knocking out, reverse transcription PCR, western blot analysis, and transmission electron microscopy were used to study the underlying mechanisms. At last, a subcutaneous nude mice model was used to study the anti-tumor effect of FIN56 in vivo. The GraphPad Prism software program was applied for statistical analysis. Results: FIN56 decreased cell viability, inhibited cell proliferation and caused cell cycle arrest on LN229 and U118 cells. Further study showed that FIN56 induced ferroptosis and induced lysosomal membrane permeabilization in a ferroptosis and transfactor EB dependent manner. Animal study demonstrated that FIN56 inhibited glioma growth and caused ferroptosis in vivo. Conclusion: FIN56 is a promising anti-tumor compound.

Interleukin-6 promotes ferroptosis in bronchial epithelial cells by inducing reactive oxygen species-dependent lipid peroxidation and disrupting iron homeostasis

Asthma occurs accompanied by the ferroptosis in bronchial epithelial cells, during which Interleukin-6 (IL-6) plays a key role. However, the associations between IL-6, ferroptosis and asthma have not been reported. Bronchial epithelial cells BEAS-2B cells were induced by different concentrations of IL-6 and cell viability was detected by MTT assay. The TBARS production rate was detected by corresponding kit. The expression of oxidative stress-related indexes was detected by ELISA. The Iron Assay Kits detected total iron levels and ferrous ion (Fe²⁺) levels. Labile iron pool assay was used to detect the cell unstable iron pool. The expression of ferroptosis-related proteins was detected by Western blot. To further examine the mechanism of action, ferroptosis inhibitor Ferrostatin 1 (Fer-1), antioxidant NAC, and the iron supplement Fe were added. We found that IL-6 decreased the activity, promoted lipid peroxidation, disrupted iron homeostasis of BEAS-2B cells, and induced iron death in bronchial epithelial BEAS-2B cells. However, pretreatment with Ferrostatin-1 (Fer-1) and antioxidant NAC partially reversed the effect of IL-6 on lipid peroxidation and ferroptosis in BEAS-2B cells, while Fe augmented the effect. Overall, IL-6 promotes ferroptosis in bronchial epithelial cells by inducing reactive oxygen species (ROS)-dependent lipid peroxidation and disrupting iron homeostasis.

Role of Ferroptosis in Lung Diseases

Ferroptosis is a new type of programmed cell death characterized by intracellular iron accumulation and lipid peroxidation that leads to oxidative stress and cell death. The metabolism of iron, lipids, and amino acids and multiple signalling pathways precisely regulate the process of ferroptosis. Emerging evidence has demonstrated that ferroptosis participates in the occurrence and progression of various pathological conditions and diseases, such as infections, neurodegeneration, tissue ischaemia-reperfusion injury and immune diseases. Recent studies have also indicated that ferroptosis plays a critical role in the pathogenesis of acute lung injury, chronic obstructive pulmonary disease, pulmonary fibrosis, pulmonary infection and asthma. Herein, we summarize the latest knowledge on the regulatory mechanism of ferroptosis and its association with iron, lipid and amino acid metabolism as well as several signalling pathways. Furthermore, we review the contribution of ferroptosis to the pathogenesis of lung diseases and discuss ferroptosis as a novel therapeutic target for various lung diseases.

TMT-based quantitative proteomics reveals suppression of SLC3A2 and ATP1A3 expression contributes to the inhibitory role of acupuncture on airway inflammation in an OVA-induced mouse asthma model

Asthma is a chronic airway inflammatory disease and acupuncture is frequently used in patients suffering from asthma in clinic. However, the regulatory mechanism of acupuncture treatment in asthma is not fully elucidated. We sought to investigate the effectiveness of acupuncture on asthma and the associated regulatory mechanism. An ovalbumin (OVA)-induced mouse asthma model was established and the effect of acupuncture on airway hyperresponsiveness (AHR), mucus hypersecretion and inflammation was assessed. Tandem mass tag (TMT)-based quantitative proteomics analysis of lung tissue and bioinformatics analysis were performed. Our results revealed that the OVA-induced mouse asthma model was successfully established with the significantly elevated AHR to methacholine (Mch), and acupuncture was effective in attenuation of AHR to Mch, peribronchial and perivascular inflammation and mucus production. The inflammatory cells around the airways, mucous secretion as well as levels of IgE, CCL5, CCL11, IL-17A in bronchoalveolar lavage fluid (BALF) and IL-4, IL-5 and IL-13 levels in serum were siginificantly inhibited by acupuncture. TMT-based quantitative proteomics analysis found that a total of 6078 quantifiable proteins were identified, and 564 (334 up-regulated and 230 down regulated) differentially expressed proteins (DEPs) were identified in OVA-induced asthma model group (A) versus normal control group (NC). Acupuncture treatment resulted in 667 DEPs (416 up-regulated and 251 down regulated) compared with A group, and 86 overlapping DEPs were identified in NC, A and AA groups. Among the 86 overlapping DEPs, we identified 41 DEPs regulated by acupuncture. Based on the above data, we performed a systematic bioinformatics analysis of the 41 DEPs, and results showed that these 41 DEPs were predominantly related to 4 KEGG pathways including SNARE interactions in vesicular transport, ferroptosis, endocrine and other factor-regulated calcium reabsorption, and protein digestion and absorption. DEPs of SLC3A2 and ATP1A3 expression levels were verified by immumohistochemical staining. Mice in OVA-induced asthma model group had elevated SLC3A2 and ATP1A3 expression and acupuncture had the ability to downregulate SLC3A2 and ATP1A3 protein expression. Furthermore, acupuncture reduced the MDA level and increased the GSH and SOD levels in the lung tissue. Taken together, our data suggested that acupuncture was effective in treating asthma by attenuation of AHR, mucus secretion and airway inflammation, and the mechanism was associated with regulation of ferroptosis, SLC3A2 and ATP1A3 protein expression as well as oxidative stress. Results from our experiments revealed the anti-inflammatory effect of acupuncture in OVA-induced mouse asthma model, leading to a more effective approach to be chosen by patients in clinic.

Ferroptosis as a novel form of regulated cell death: Implications in the pathogenesis, oncometabolism and treatment of human cancer

The treatment of cancer mainly involves surgical excision supplemented by radiotherapy and chemotherapy. Chemotherapy drugs act by interfering with tumor growth and inducing the death of cancer cells. Anti-tumor drugs were developed to induce apoptosis, but some patient’s show apoptosis escape and chemotherapy resistance. Therefore, other forms of cell death that can overcome the resistance of tumor cells are important in the context of cancer treatment. Ferroptosis is a newly discovered iron-dependent, non-apoptotic type of cell death that is highly negatively correlated with cancer development. Ferroptosis is mainly caused by the abnormal increase in iron-dependent lipid reactive oxygen species and the imbalance of redox homeostasis. This review summarizes the progression and regulatory mechanism of ferroptosis in cancer and discusses its possible clinical applications in cancer diagnosis and treatment.