The emerging role of ferroptosis in inflammation

RXRγ attenuates cerebral ischemia-reperfusion induced ferroptosis in neurons in mice through transcriptionally promoting the expression of GPX4

Cerebral ischemia is a common cerebrovascular disease with high mortality and disability rate. Exploring its mechanism is essential for developing effective treatment for cerebral ischemia. Therefore, this study aims to explore the regulatory effect and mechanism of retinoid X receptor γ (RXRγ) on cerebral ischemia-reperfusion (I/R) injury. A mouse intraluminal middle cerebral artery occlusion model was established, and PC12 cells were exposed to anaerobic/reoxygenation (A/R) as an in vitro model in this study. Cerebral I/R surgery or A/R treatment induced ferroptosis, downregulated RXRγ and GPX4 (glutathione peroxidase 4) levels, upregulated cyclooxygenase-2 (COX-2) level and increased ROS (reactive oxygen species) level in A/R induced cells or I/R brain tissues in vivo or PC12 cells in vitro. Knockdown of RXRγ downregulated GPX4 and increased COX-2 and ROS levels in A/R induced cells. RXRγ overexpression has the opposite effect. GPX4 knockdown reversed the improvement of RXRγ overexpression on COX-2 downregulation, GPX4 upregulation and ferroptosis in PC12 cells. Furthermore, chromatin immunoprecipitation (ChIP) and luciferase reporter gene assays revealed that RXRγ bound to GPX4 promoter region and activated its transcription. Overexpression of RXRγ or GPX4 alleviated brain damage and inhibited ferroptosis in I/R mice. In conclusion, RXRγ-mediated transcriptional activation of GPX4 might inhibit ferroptosis during I/R-induced brain injury.

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

Asthma is a disease characterized by airway epithelial barrier destruction, chronic airway inflammation, and airway remodeling. Repeated damage to airway epithelial cells by allergens in the environment plays an important role in the pathophysiology of asthma. Ferroptosis is a novel form of regulated cell death mediated by lipid peroxidation in association with free iron-mediated Fenton reactions. In this study, we explored the contribution of ferroptosis to house dust mite (HDM)-induced asthma models. Our in vivo and in vitro models showed labile iron accumulation and enhanced lipid peroxidation with concomitant nonapoptotic cell death upon HDM exposure. Treatment with ferroptosis inhibitors deferoxamine (DFO) and ferrostatin-1 (Fer-1) illuminated the role of ferroptosis and related damage-associated molecular patterns in HDM-treated airway epithelial cells. Furthermore, DFO and Fer-1 reduced HDM-induced airway inflammation in model mice. Mechanistically, NCOA4-mediated ferritin-selective autophagy (ferritinophagy) was initiated during ferritin degradation in response to HDM exposure. Together, these data suggest that ferroptosis plays an important role in HDM-induced asthma and that ferroptosis may be a potential treatment target for HDM-induced asthma.

Catechin Mediates Ferroptosis to Exert an Anti-Inflammatory Effect on RAW 264.7 Cells

Catechin possesses a potential anti-inflammatory activity, but its anti-inflammatory mechanism is still unclear. Herein, the analysis of network pharmacology showed that catechin might mediate ferroptosis on macrophages to exhibit a significant anti-inflammatory effect on RAW264.7. The metabolomics further indicated that catechin might influence ferroptosis by activating two pathways of cysteine and methionine metabolism and glutathione metabolism, and inhibiting the pathway of ferroptosis to promote the reduction of l-methionine-s-oxide and s-glutathionyl-l-cysteine, and the reduction and synthesis of γ-glutamylcysteine. Furthermore, related proteins (MSRA, CDR, GSR and GCL) in three metabolic pathways and ferroptosis-related proteins (GPX4 and SLC7A11) might be relevant to catechin through molecular docking. Thus, we speculate that catechin plays an anti-inflammatory effect through mediating ferroptosis on RAW264.7, which still needs further focus on the detailed molecular mechanism.

Ferroptosis Related Immunomodulatory Effect of a Novel Extracellular Polysaccharides from Marine Fungus Aureobasidium melanogenum

Marine fungi represent an important and sustainable resource, from which the search for novel biological substances for application in the pharmacy or food industry offers great potential. In our research, novel polysaccharide (AUM-1) was obtained from marine Aureobasidium melanogenum SCAU-266 were obtained and the molecular weight of AUM-1 was determined to be 8000 Da with 97.30% of glucose, 1.9% of mannose, and 0.08% galactose, owing to a potential backbone of α-D-Glcp-(1→2)-α-D-Manp-(1→4)-α-D-Glcp-(1→6)-(SO₃⁻)-4-α-D-Glcp-(1→6)-1-β-D-Glcp-1→2)-α-D-Glcp-(1→6)-β-D-Glcp-1→6)-α-D-Glcp-1→4)-α-D-Glcp-6→1)-[α-D-Glcp-4]₂₆→1)-α-D-Glcp and two side chains that consisted of α-D-Glcp-1 and α-D-Glcp-(1→6)-α-D-Glcp residues. The immunomodulatory effect of AUM-1 was identified. Then, the potential molecular mechanism by which AUM-1 may be connected to ferroptosis was indicated by metabonomics, and the expression of COX2, SLC7A11, GPX4, ACSL4, FTH1, and ROS were further verified. Thus, we first speculated that AUM-1 has a potential effect on the ferroptosis-related immunomodulatory property in RAW 264.7 cells by adjusting the expression of GPX4, regulated glutathione (oxidative), directly causing lipid peroxidation owing to the higher ROS level through the glutamate metabolism and TCA cycle. Thus, the ferroptosis related immunomodulatory effect of AUM-1 was obtained.

Novel Insights in the Regulatory Mechanisms of Ferroptosis in Hepatocellular Carcinoma

Ferroptosis is a newly defined programmed cell death, which by its mechanism differs from other programmed cell death processes such as apoptosis, necrosis, and autophagy. It has a unique morphology and biological properties that antioxidants and iron-chelating agents can regulate. Ferroptosis has the characteristics of iron ion deposition and dependence on lipid peroxidation. It can affect the progression of many cancers, including liver cancer, by inducing an intracellular iron-dependent accumulation of reactive oxygen species, providing new possibilities for cancer treatment. At present, great progress has been made in exploring the molecular mechanism of ferroptosis. In this review, we summarize the characteristics, mechanisms, and regulatory factors of ferroptosis in detail, discuss the progress of ferroptosis research in liver cancer, and provide directions and new ideas for the treatment of hepatocellular carcinoma.

Programmed cell death in atherosclerosis and vascular calcification

The concept of cell death has been expanded beyond apoptosis and necrosis to additional forms, including necroptosis, pyroptosis, autophagy, and ferroptosis. These cell death modalities play a critical role in all aspects of life, which are noteworthy for their diverse roles in diseases. Atherosclerosis (AS) and vascular calcification (VC) are major causes for the high morbidity and mortality of cardiovascular disease. Despite considerable advances in understanding the signaling pathways associated with AS and VC, the exact molecular basis remains obscure. In the article, we review the molecular mechanisms that mediate cell death and its implications for AS and VC. A better understanding of the mechanisms underlying cell death in AS and VC may drive the development of promising therapeutic strategies.

Role of Histone Post-Translational Modifications in Inflammatory Diseases

Inflammation is a defensive reaction for external stimuli to the human body and generally accompanied by immune responses, which is associated with multiple diseases such as atherosclerosis, type 2 diabetes, Alzheimer’s disease, psoriasis, asthma, chronic lung diseases, inflammatory bowel disease, and multiple virus-associated diseases. Epigenetic mechanisms have been demonstrated to play a key role in the regulation of inflammation. Common epigenetic regulations are DNA methylation, histone modifications, and non-coding RNA expression; among these, histone modifications embrace various post-modifications including acetylation, methylation, phosphorylation, ubiquitination, and ADP ribosylation. This review focuses on the significant role of histone modifications in the progression of inflammatory diseases, providing the potential target for clinical therapy of inflammation-associated diseases.

Molecular modeling of lactoferrin for food and nutraceutical applications: insights from in silico techniques

Lactoferrin is a protein, primarily found in milk that has attracted the interest of the food industries due to its health properties. Nevertheless, the instability of lactoferrin has limited its commercial application. Recent studies have focused on encapsulation to enhance the stability of lactoferrin. However, the molecular insights underlying the changes of structural properties of lactoferrin and the interaction with protectants remain poorly understood. Computational approaches have proven useful in understanding the structural properties of molecules and the key binding with other constituents. In this review, comprehensive information on the structure and function of lactoferrin and the binding with various molecules for food purposes are reviewed, with a special emphasis on the use of molecular dynamics simulations. The results demonstrate the application of modeling and simulations to determine key residues of lactoferrin responsible for its stability and interactions with other biomolecular components under various conditions, which are also associated with its functional benefits. These have also been extended into the potential creation of enhanced lactoferrin for commercial purposes. This review provides valuable strategies in designing novel nutraceuticals for food science practitioners and those who have interests in acquiring familiarity with the application of computational modeling for food and health purposes.

Types of necroinflammation, the effect of cell death modalities on sterile inflammation

Distinct types of immune responses are activated by infections, which cause the development of type I, II, or III inflammation, regulated by Th1, Th2, Th17 helper T cells and ILC1, ILC2 and ILC3 cells, respectively. While the classification of immune responses to different groups of pathogens is widely accepted, subtypes of the immune response elicited by sterile inflammation have not yet been detailed. Necroinflammation is associated with the release of damage-associated molecular patterns (DAMP) from dying cells. In this review, we present that the distinct molecular mechanisms activated during apoptosis, necroptosis, pyroptosis, and ferroptosis lead to the release of different patterns of DAMPs and their suppressors, SAMPs. We summarize the currently available data on how regulated cell death pathways and released DAMPs and SAMPs direct the differentiation of T helper and ILC cells. Understanding the subtypes of necroinflammation can be crucial in developing strategies for the treatment of sterile inflammatory diseases caused by cell death processes.

Immunogenic Cell Death, DAMPs and Prothymosin α as a Putative Anticancer Immune Response Biomarker

The new and increasingly studied concept of immunogenic cell death (ICD) revealed a previously unknown perspective of the various regulated cell death (RCD) modalities, elucidating their immunogenic properties and rendering obsolete the notion that immune stimulation is solely the outcome of necrosis. A distinct characteristic of ICD is the release of danger-associated molecular patterns (DAMPs) by dying and/or dead cells. Thus, several members of the DAMP family, such as the well-characterized heat shock proteins (HSPs) HSP70 and HSP90, the high-mobility group box 1 protein and calreticulin, and the thymic polypeptide prothymosin α (proTα) and its immunoreactive fragment proTα(100–109), are being studied as potential diagnostic tools and/or possible therapeutic agents. Here, we present the basic aspects and mechanisms of both ICD and other immunogenic RCD forms; denote the role of DAMPs in ICD; and further exploit the relevance of human proTα and proTα(100–109) in ICD, highlighting their possible clinical applications. Furthermore, we present the preliminary results of our in vitro studies, which show a direct correlation between the concentration of proTα/proTα(100–109) and the levels of cancer cell apoptosis, induced by anticancer agents and γ-radiation.

The Potential Role of Ferroptosis in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that is accompanied with autoantibody production and inflammation. Other features of SLE pathogenesis include iron accumulation, oxidative stress, and lipid peroxidation, which are also major biochemical characteristics of ferroptosis, a novel non-apoptotic regulated form of cell death. To date, ferroptosis has been demonstrated to be an important driver of lupus progression, and several ferroptosis inhibitors have therapeutic effect in lupus-prone mice. Given the emerging link between ferroptosis and SLE, it can be postulated that ferroptosis is an integral component in the vicious cycle of immune dysfunction, inflammation, and tissue damage in SLE pathogenesis. In this review, we summarize the potential links between ferroptosis and SLE, with the aim of elucidating the underlying pathogenic mechanism of ferroptosis in lupus, and providing a new promising therapeutic strategy for SLE.

PPARδ Activation Mitigates 6-OHDA-Induced Neuronal Damage by Regulating Intracellular Iron Levels

Intracellular iron accumulation in dopaminergic neurons contributes to neuronal cell death in progressive neurodegenerative disorders such as Parkinson’s disease. However, the mechanisms of iron homeostasis in this context remain incompletely understood. In the present study, we assessed the role of the nuclear receptor peroxisome proliferator-activated receptor δ (PPARδ) in cellular iron homeostasis. We identified that PPARδ inhibited 6-hydroxydopamine (6-OHDA)-triggered neurotoxicity in SH-SY5Y neuroblastoma cells. PPARδ activation with GW501516, a specific PPARδ agonist, mitigated 6-OHDA-induced neuronal damage. Further, PPARδ activation also suppressed iron accumulation, which contributes to 6-OHDA-induced neuronal damage. PPARδ activation attenuated 6-OHDA-induced neuronal damage in a similar manner to that of the iron chelator deferoxamine. We further elucidated that PPARδ modulated cellular iron homeostasis by regulating expression of divalent metal transporter 1, ferroportin 1, and ferritin, but not transferrin receptor 1, through iron regulatory protein 1 in 6-OHDA-treated cells. Interestingly, PPARδ activation suppressed 6-OHDA-triggered generation of reactive oxygen species and lipid peroxides. The effects of GW501516 were abrogated by shRNA knockdown of PPARδ, indicating that the effects of GW501516 were PPARδ-dependent. Taken together, these findings suggest that PPARδ attenuates 6-OHDA-induced neurotoxicity by preventing intracellular iron accumulation, thereby suppressing iron overload-associated generation of reactive oxygen species and lipid peroxides, key mediators of ferroptotic cell death.

Nrf2-Mediated Ferroptosis Inhibition Exerts a Protective Effect on Acute-on-Chronic Liver Failure

Although massive hepatocyte cell death and oxidative stress constitute major events of acute-on-chronic liver failure (ACLF), the relationship of ferroptosis with ACLF has yet to be explored. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key regulator of ferroptosis. However, if Nrf2 modulates ACLF through ferroptosis remains unknown. Here, the liver tissues of ACLF patients were collected and murine models of ACLF using carbon tetrachloride, D-galactosamine, and lipopolysaccharide as well as an H2O2-induced hepatocyte injury model were established. Upon ACLF, livers exhibited key features of ferroptosis, including lipid peroxidation (increase in malondialdehyde whereas a decrease in glutathione and nicotinamide adenine dinucleotide phosphate), and increased mRNA expression of prostaglandin-endoperoxide synthase-2 (PTGS2). Ferroptosis inducer RSL-3 treatment aggravated liver damage, while ferroptosis inhibitor Ferrostatin-1 administration alleviated ACLF severity, manifesting with improved liver histopathological lesions and reduced serum ALT and AST. Compared with normal liver tissue, Nrf2 was upregulated in ACLF patients and murine models. Pharmacological activation of Nrf2 (Bardoxolone Methyl) attenuated liver damage, prevented lipid peroxidation, upregulated PTGS2 mRNA expression, and improved ferroptosis-specific mitochondrial morphology in vivo. In contrast, Nrf2 inhibitor ML385 exacerbated lipid peroxidation and liver injury. Collectively, Nrf2 plays a protective role in ACLF progression through repressing ferroptosis, which provides promising therapeutic cues for ACLF.

Glycyrrhizin Attenuates Hypoxic-Ischemic Brain Damage by Inhibiting Ferroptosis and Neuroinflammation in Neonatal Rats via the HMGB1/GPX4 Pathway

With unknown etiology and limited treatment options, neonatal hypoxic-ischemic brain damage (HIBD) remains a major cause of mortality in newborns. Ferroptosis, a recently discovered type of cell death triggered by lipid peroxidation, is closely associated with HIBD. High-mobility group box 1 (HMGB1), a molecule associated with inflammation damage, can induce neuronal death in HIBD. However, it remains unknown whether HMGB1 contributes to neuronal ferroptosis in patients with HIBD. Herein, glycyrrhizin (GL), an HMGB1 inhibitor, was used to investigate the relationship between ferroptosis and HMGB1. RAS-selective lethal 3(RSL3), a ferroptosis agonist, was administered to further confirm the changes in the signaling pathway between HMGB1 and ferroptosis. Western blot analysis revealed that GL markedly suppressed the expression of HMGB1 and increased the level of GPX4 in the context of HIBD. We observed changes in neuronal ultrastructure via transmission electron microscopy to further confirm the occurrence of ferroptosis. Real-time PCR indicated that GL inhibited the expression of ferroptosis-related genes and inflammatory factors. Immunofluorescence and immunohistochemistry staining confirmed GL inhibition of neuronal damage and ferroptosis in HIBD associated with GPX4 and ROS. GL not only inhibited ferroptosis induced by RSL3 and oxygen-glucose deprivation in vitro but also inhibited ferroptosis induced by HIBD in vivo. More importantly, GL may improve oxidative stress imbalance and mitochondrial damage, alleviate the downstream production of inflammatory factors, and ultimately reduce ferroptosis and damage to cortical neurons following HIBD via the HMGB1/GPX4 pathway. In conclusion, we showed for the first time that GL could suppress the occurrence of neuronal ferroptosis and reduce neuronal loss in HIBD via the HMGB1/GPX4 pathway. These findings highlight the potential of HMGB1 signaling antagonists to treat neuronal damage by suppressing ferroptosis, provide new and unique insights into GL as a neuroprotective agent, and suggest new prevention and treatment strategies for HIBD.

The Biological Functions and Regulatory Mechanisms of Fatty Acid Binding Protein 5 in Various Diseases

In recent years, fatty acid binding protein 5 (FABP5), also known as fatty acid transporter, has been widely researched with the help of modern genetic technology. Emerging evidence suggests its critical role in regulating lipid transport, homeostasis, and metabolism. Its involvement in the pathogenesis of various diseases such as metabolic syndrome, skin diseases, cancer, and neurological diseases is the key to understanding the true nature of the protein. This makes FABP5 be a promising component for numerous clinical applications. This review has summarized the most recent advances in the research of FABP5 in modulating cellular processes, providing an in-depth analysis of the protein's biological properties, biological functions, and mechanisms involved in various diseases. In addition, we have discussed the possibility of using FABP5 as a new diagnostic biomarker and therapeutic target for human diseases, shedding light on challenges facing future research.

COVID-19-Related Brain Injury: The Potential Role of Ferroptosis

The COVID-19 pandemic has caused devastating loss of life and a healthcare crisis worldwide. SARS-CoV-2 is the causative pathogen of COVID-19 and is transmitted mainly through the respiratory tract, where the virus infects host cells by binding to the ACE2 receptor. SARS-CoV-2 infection is associated with acute pneumonia, but neuropsychiatric symptoms and different brain injuries are also present. The possible routes by which SARS-CoV-2 invades the brain are unclear, as are the mechanisms underlying brain injuries with the resultant neuropsychiatric symptoms in patients with COVID-19. Ferroptosis is a unique iron-dependent form of non-apoptotic cell death, characterized by lipid peroxidation with high levels of glutathione consumption. Ferroptosis plays a primary role in various acute and chronic brain diseases, but to date, ferroptosis in COVID-19-related brain injuries has not been explored. This review discusses the mechanisms of ferroptosis and recent evidence suggesting a potential pathogenic role for ferroptosis in COVID-19-related brain injury. Furthermore, the possible routes through which SARS-CoV-2 could invade the brain are also discussed. Discoveries in these areas will open possibilities for treatment strategies to prevent or reduce brain-related complications of COVID-19.

Specific changes of erythroid regulators and hepcidin in patients infected by SARS-COV-2

Iron metabolism is tightly linked to infectious and inflammatory signals through hepcidin synthesis. To date, iron homeostasis during SARS-CoV-2 infection has not yet been described. The aim of this study is to characterize the hepcidin and erythroid regulators (growth differentiation factor 15 (GDF-15) and erythroferrone (ERFE)) by measuring concentrations in plasma in context of COVID-19 disease.We performed a single-center observational study of patients with COVID-19 to evaluate concentrations of main regulatory proteins involved in iron homeostasis, namely: hepcidin, ERFE and GDF-15. SARS-CoV-2 infection (COVID-19+) was defined by a positive RT-PCR. Sixteen patients with COVID-19+ were gender-matched and age-matched to 16 patients with a sepsis unrelated to SARS-CoV-2 (COVID-19-) and were compared with non-parametric statistic test.Clinical and hematological parameters, plasma iron, transferrin, transferrin saturation, ferritin, soluble transferrin receptor and C reactive protein were not statistically different between both groups. Median plasma hepcidin concentrations were higher in the COVID-19+ group (44.1 (IQR 16.55-70.48) vs 14.2 (IQR 5.95-18.98) nmol/L, p=0.003), while median ERFE and GDF-15 concentrations were lower in the COVID-19+ group (0.16 (IQR 0.01-0.73) vs 0.89 (IQR 0.19-3.82) ng/mL, p=0.035; 2003 (IQR 1355-2447) vs 4713 (IQR 2082-7774) pg/mL, p=0015), respectively) compared with the COVID-19- group.This is the first study reporting lower ERFE and GDF-15 median concentrations in patients with COVID-19+ compared with patients with COVID-19-, associated with an increased median concentration of hepcidin in the COVID-19+ group compared with COVID19- group.

Necroptosis in Solid Organ Transplantation: A Literature Overview

Ischemia-reperfusion injury (IRI) is encountered in various stages during solid organ transplantation (SOT). IRI is known to be a multifactorial inflammatory condition involving hypoxia, metabolic stress, leukocyte extravasation, cellular death (including apoptosis, necrosis and necroptosis) and an activation of immune response. Although the cycle of sterile inflammation during IRI is consistent among different organs, the underlying mechanisms are poorly understood. Receptor-interacting protein kinase 3 (RIPK3) and mixed-lineage kinase domain-like pseudokinase (MLKL) are thought to be crucial in the implementation of necroptosis. Moreover, apart from “silent” apoptotic death, necrosis also causes sterile inflammation—necroinflammation, which is triggered by various damage-associated molecular patterns (DAMPs). Those DAMPs activate the innate immune system, causing local and systemic inflammatory responses, which can result in graft failure. In this overview we summarize knowledge on mechanisms of sterile inflammation processes during SOT with special focus on necroptosis and IRI and discuss protective strategies.

Nitrogen-doped graphene quantum dots induce ferroptosis through disrupting calcium homeostasis in microglia

Background

Along with the wild applications of nitrogen-doped graphene quantum dots (N-GQDs) in the fields of biomedicine and neuroscience, their increasing exposure to the public and potential biosafety problem has gained more and more attention. Unfortunately, the understanding of adverse effects of N-GQDs in the central nervous system (CNS), considered as an important target of nanomaterials, is still limited.

Results

After we found that N-GQDs caused cell death, neuroinflammation and microglial activation in the hippocampus of mice through the ferroptosis pathway, microglia was used to assess the molecular mechanisms of N-GQDs inducing ferroptosis because it could be the primary target damaged by N-GQDs in the CNS. The microarray data suggested the participation of calcium signaling pathway in the ferroptosis induced by N-GQDs. In microglial BV2 cells, when the calcium content above the homeostatic level caused by N-GQDs was reversed, the number of cell death, ferroptosis alternations and excessive inflammatory cytokines release were all alleviated. Two calcium channels of L-type voltage-gated calcium channels (L-VGCCs) in plasma membrane and ryanodine receptor (RyR) in endoplasmic reticulum (ER) took part in N-GQDs inducing cytosolic calcium overload. L-VGCCs and RyR calcium channels were also involved in promoting the excess iron influx and triggering ER stress response, respectively, which both exert excessive ROS generation and result in the ferroptosis and inflammation in BV2 cells.

Conclusion

N-GQDs exposure caused ferroptosis and inflammatory responses in hippocampus of mice and cultured microglia through activating two calcium channels to disrupt intracellular calcium homeostasis. The findings not only posted an alert for biomedical applications of N-GQDs, but also highlighted an insight into mechanism researches of GQDs inducing multiple types of cell death in brain tumor therapy in the future.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00464-z.

Carboxymethylated pachyman induces ferroptosis in ovarian cancer by suppressing NRF1/HO‑1 signaling

Carboxymethylated pachyman (CMP) is characterized by immune regulatory, antitumor and antioxidant activities. However, whether CMP contributes to the treatment of ovarian cancer has yet to be explored. The role of CMP in ovarian cancer cell death was analyzed using CCK-8 and flow cytometry assays. The data showed that CMP induced ovarian cancer cell death in a dose-dependent manner. Furthermore, CMP-induced cell death could be largely reversed by preincubation with ferrostatin-1 (Fer-1) but not 3-methyladenine or necrostatin-1. Reverse transcription-quantitative PCR analysis indicated that CMP significantly increased prostaglandin-endoperoxide synthase 2 (PTGS2) and Chac glutathione specific γ-glutamylcyclotransferase 1 (CHAC1) mRNA levels, but preincubation with Fer-1 obviously reduced PTGS2 and CHAC1 mRNA levels in SKOV3 and Hey cells. The intracellular levels of superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA) and Fe²⁺ were then quantified The data showed that 100 and 200 µg/ml CMP enhanced the production of SOD, MDA and Fe²⁺ but decreased GSH levels in SKOV3 and HEY cells. These data indicated that CMP could induce ferroptosis in ovarian cancer cells. More importantly, in vitro and in vivo studies indicated that CMP significantly suppressed nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), cystine/glutamate antiporter system X(c)(−) (xCT) and glutathione peroxidase 4 (GPX4) expression in ovarian cancer cells and tumors. In conclusion, the present study showed novel data that CMP could induce ferroptotic death in ovarian cancer cells by suppressing Nrf2/HO-1/xCT/GPX4. All these findings indicate that CMP may have great potential in anti-ovarian cancer cell therapy by inducing ferroptosis.

The Iron-Inflammation Axis in Early-Stage Triple-Negative Breast Cancer

The iron-related homeostasis and inflammatory biomarker have been identified as prognostic factors for cancers. We aimed to explore the prognostic value of a novel comprehensive biomarker, the iron-monocyte-to-lymphocyte ratio (IronMLR) score, in patients with early-stage triple-negative breast cancer (TNBC) in this study. We retrospectively analysed a total of 257 early-stage TNBC patients treated at Sun Yat-sen University Cancer Center (SYSUCC) between March 2006 and October 2016. Their clinicopathological information and haematological data tested within 1 week of the diagnosis were collected. According to the IronMLR score cutoff value of 6.07 μmol/L determined by maximally selected rank statistics, patients were stratified into the low- and high-IronMLR groups, after a median follow-up of 92.3 months (95% confidence interval [CI] 76.0–119.3 months), significant differences in 5-years disease-free survival (DFS) rate (81.2%, 95% CI 76.2%–86.5% vs. 65.5%, 95% CI 50.3%–85.3%, p = 0.012) and 5-years overall survival (OS) rate (86.0%, 95% CI 81.6%–90.7% vs. 65.5%, 95% CI 50.3%–85.3%, p = 0.011) were seen between two groups. Further multivariate Cox regression analysis revealed the IronMLR score as an independent predictor for DFS and OS, respectively, we then established a prognostic nomogram integrating the IronMLR score, T stage and N stage for individualized survival predictions. The prognostic model showed good predictive performance with a C-index of DFS 0.725 (95% CI 0.662–0.788) and OS 0.758 (95% CI 0.689–0.826), respectively. Besides, calibration curves for 1-, 3-, 5-DFS, and OS represented satisfactory consistency between actual and nomogram predicted survival. In conclusion, the Iron-inflammation axis might be a potential prognostic biomarker of survival outcomes for patients with early-stage TNBC, prognostic nomograms based on it with good predictive performance might improve individualized survival predictions.

Ferroptosis plays an important role in promoting ionizing radiation-induced intestinal injuries

The intestinal tract is an essential component of the body's immune system, and is extremely sensitive to exposure of ionizing radiation. While ionizing radiation can effectively induce multiple forms of cell death, whether it can also promote ferroptosis in intestinal cells and the possible interrelationship between ferroptosis and intestinal immune function has not been reported so far. Here, we found that radiation-induced major ultrastructural changes in mitochondria of small intestinal epithelial cells and the changes induced in iron content and MDA levels in the small intestine were consistent with that observed during cellular ferroptosis, thus suggesting occurrence of ferroptosis in radiation-induced intestinal damage. Moreover, radiation caused a substantial increase in the expression of ferroptosis-related factors such as LPCAT3 and ALOX15 mRNA, augmented the levels of immune-related factors INF-γ and TGF-β mRNA, and decreased the levels of IL-17 mRNA thereby indicating that ionizing radiation induced ferroptosis and impairment of intestinal immune function. Liproxstatin-1 is a ferroptosis inhibitor that was found to ameliorate radiation-induced ferroptosis and promote the recovery from immune imbalances. These findings supported the role of ferroptosis in radiation-induced intestinal immune injury and provide novel strategies for protection against radiation injury through regulation of the ferroptosis pathway.

Postconditioning with Irisin Attenuates Lung Ischemia/Reperfusion Injury by Suppressing Ferroptosis via Induction of the Nrf2/HO-1 Signal Axis

Iron-dependent lipid peroxidation causes ferroptosis. This study was aimed at verifying that irisin postconditioning can inhibit ferroptosis and minimize lung ischemia/reperfusion (I/R) damage via activating the Nrf2/HO-1 signal axis. We constructed a murine model of I/R lung damage. At the onset of reperfusion, irisin, ferroptosis inhibitor ferrostatin-1, and ferroptosis inducer Fe-citrate were all administered. We discovered that irisin could reduce lung I/R injury, consistent with ferrostatin-1's action. Furthermore, irisin suppressed ferroptosis in lung I/R damage, as evidenced by lower ROS, MDA, and Fe²⁺, as well as alterations in critical protein expression (GPX4 and ACSL4). However, Fe-citrate abolished the protective effects of irisin. Transcriptome research found that irisin increased the mRNA levels of Nrf2 and HO-1. Thus, we used siRNA to investigate the role of the Nrf2/HO-1 axis in irisin-mediated protection against hypoxia/reoxygenation (H/R) damage in MLE-12 cells. Irisin consistently reduced ferroptosis and improved mitochondrial dysfunction caused by H/R. Irisin's cytoprotective function was eliminated when Nrf2 was silenced. As a result, irisin postconditioning may protect against lung I/R damage by suppressing ferroptosis via the Nrf2/HO-1 signaling axis.

Exosome-Derived lncRNA NEAT1 Exacerbates Sepsis-Associated Encephalopathy by Promoting Ferroptosis Through Regulating miR-9-5p/TFRC and GOT1 Axis

Sepsis can cause sepsis-associated encephalopathy (SAE), but whether SAE was induced or exacerbated by ferroptosis remains unknown. In this study, the rat sepsis model was constructed using the cecal ligation and puncture method. The blood-brain barrier (BBB) permeability was measured by Evans blue dye (EBD) in vivo. The levels of ROS, Fe ion, MDA, GSH, and GPX4 were assessed by enzyme-linked immunosorbent assay (ELISA). The exosomes isolated from serum were cultured with bEnd.3 cells for the in vitro analysis. Moreover, bEnd.3 cells cultured with 100 μM FeCl3 (iron-rich) were to simulate ferroptosis stress. The cell viability was evaluated by Cell Counting Kit-8 (CCK-8) assay. A dual-luciferase reporter gene assay was performed to confirm the relationship between miR-9-5p with NEAT1, TFRC, and GOT1. In vivo, it is found that BBB permeability was damaged in model rats. Level of ROS, Fe ion, and MDA was increased, and level of GSH and GPX4 was decreased, which means ferroptosis was induced by sepsis. Exosome-packaged NEAT1 in serum was significantly upregulated in model rats. In vitro, it is found that NEAT1 functions as a ceRNA for miR-9-5p to facilitate TFRC and GOT1 expression. Overexpression of NEAT1 enhanced ferroptosis stress in bEnd.3 cells. Increased miR-9-5p alleviated sepsis-induced ferroptosis by suppressing the expression of TFRC and GOT1 both in vivo and in vitro. In conclusion, these findings suggest that sepsis induced high expression of serous exosome-derived NEAT1, and it might exacerbate SAE by promoting ferroptosis through regulating miR-9-5p/TFRC and GOT1 axis.

NVP-AUY922 alleviates radiation-induced lung injury via inhibition of autophagy-dependent ferroptosis

Radiation-induced lung injury (RILI) is a common complication of radiotherapy for which no effective interventions are available. NVP-AUY922, a resorcinylic isoxazole amide drug, exhibits anti-inflammatory, immunomodulatory, and therapeutic effects against various types of cancers. In this study, we explore the role and underlying mechanisms of NVP-AUY922 in the treatment of RILI. We established a model of BEAS-2B cell injury and a mouse model of RILI. Cell proliferation, death, gross weight, and survival rates of mice, and histological parameters were assessed. Additionally, inflammation-related indices and indicators related to ferroptosis were evaluated. Furthermore, immunofluorescence and co-immunoprecipitation were used to determine the interaction between GPX4, LAMP-2A, and HSC70. NVP-AUY922 significantly ameliorated radiation-induced lung tissue damage, inflammatory cell infiltration, proinflammatory cytokine release, and lung epithelial BEAS-2B cell damage. NVP-AUY922 markedly limited the activation of ferroptosis, which is involved in RILI. Mechanistically, NVP-AUY922 prevented chaperone-mediated autophagy of the GPX4 pathway in vitro and in vivo, and the autophagy inhibitor Baf-A1 significantly increased the level of GPX4 and alleviated lung inflammation. NVP-AUY922 can alleviate RILI by inhibiting chaperone-mediated lysosomal degradation of GPX4, demonstrating its potential as a novel protective agent against RILI.

Endothelial cell ferroptosis mediates monocrotaline-induced pulmonary hypertension in rats by modulating NLRP3 inflammasome activation

Inflammation triggers pulmonary vascular remodelling. Ferroptosis, a nonapoptotic form of cell death that is triggered by iron-dependent lipid peroxidation and contributes to the pathogenesis of several inflammation-related diseases, but its role in pulmonary hypertension (PH) has not been studied. We examined endothelial cell ferroptosis in PH and the potential mechanisms. Pulmonary artery endothelial cells (PAECs) and lung tissues from monocrotaline (MCT)-induced PH rats were analysed for ferroptosis markers, including lipid peroxidation, the labile iron pool (LIP) and the protein expression of glutathione peroxidase 4 (GPX4), ferritin heavy chain 1 (FTH1) and NADPH oxidase-4 (NOX4). The effects of the ferroptosis inhibitor ferrostatin-1 (Fer-1) on endothelial cell ferroptosis and pulmonary vascular remodelling in MCT-induced rats were studied in vitro and in vivo. Ferroptosis was observed in PAECs from MCT-induced PH rats in vitro and in vivo and was characterized by a decline in cell viability accompanied by increases in the LIP and lipid peroxidation, the downregulation of GPX4 and FTH1 expression and the upregulation of NOX4 expression. High-mobility group box 1 (HMGB1)/Toll-like receptor 4 (TLR4)/NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome signalling was measured by western blotting. These changes were significantly blocked by Fer-1 administration in vitro and in vivo. These results suggest that Fer-1 plays a role in inhibiting ferroptosis-mediated PAEC loss during the progression of PH. The ferroptosis-induced inflammatory response depended on the activation of HMGB1/TLR4 signalling, which activated the NLRP3 inflammasome in vivo. We are the first to suggest that pulmonary artery endothelial ferroptosis triggers inflammatory responses via the HMGB1/TLR4/NLRP3 inflammasome signalling pathway in MCT-induced rats. Treating PH with a ferroptosis inhibitor and exploring new treatments based on ferroptosis regulation might be promising therapeutic strategies for PH.

Ferroptosis Involvement in Glioblastoma Treatment

Glioblastoma multiforme (GBM) is one of the deadliest brain tumors. Current standard therapy includes tumor resection surgery followed by radiotherapy and chemotherapy. Due to the tumors invasive nature, recurrences are almost a certainty, giving the patients after diagnosis only a 12–15 months average survival time. Therefore, there is a dire need of finding new therapies that could potentially improve patient outcomes. Ferroptosis is a newly described form of cell death with several implications in cancer, among which GBM. Agents that target different molecules involved in ferroptosis and that stimulate this process have been described as potentially adjuvant anti-cancer treatment options. In GBM, ferroptosis stimulation inhibits tumor growth, improves patient survival, and increases the efficacy of radiation and chemotherapy. This review provides an overview of the current knowledge regarding ferroptosis modulation in GBM.

Ferroptosis Inhibitors as Potential New Therapeutic Targets for Cardiovascular Disease

Abstract:

Ferroptosis is a novel form of programmed cell death that arises as a result of an increase in iron levels. Ferroptosis is implicated in a number of cardiovascular diseases, including myocardial infarction (MI), reperfusion damage, and heart failure(HF). Because cardiomyocyte depletion is the leading cause of patient morbidity and mortality, it is critical to thoroughly comprehend the regulatory mechanisms of ferroptosis activation. In fact, inhibiting cardiac ferroptosis has the potential to be a useful therapeutic method for cardiovascular disorders. The iron, lipid, amino acid, and glutathione metabolism strictly governs the beginning and execution of ferroptosis. Therefore, ferroptosis can be inhibited by iron chelators, free radical-trapping antioxidants, GPX4 (Glutathione Peroxidase 4) activators, and lipid peroxidation (LPO) inhibitors. However, the search for new molecular targets for ferroptosis is becoming increasingly important in cardiovascular disease research. In this review, we address the importance of ferroptosis in various cardiovascular illnesses, provide an update on current information about the molecular mechanisms that drive ferroptosis, and discuss the role of ferroptosis inhibitors in cardiovascular disease.

CNS Redox Homeostasis and Dysfunction in Neurodegenerative Diseases

A single paragraph of about 200 words maximum. Neurodegenerative diseases (ND), such as Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis, pose a global challenge in the aging population due to the lack of treatments for their cure. Despite various disease-specific clinical symptoms, ND have some fundamental common pathological mechanisms involving oxidative stress and neuroinflammation. The present review focuses on the major causes of central nervous system (CNS) redox homeostasis imbalance comprising mitochondrial dysfunction and endoplasmic reticulum (ER) stress. Mitochondrial disturbances, leading to reduced mitochondrial function and elevated reactive oxygen species (ROS) production, are thought to be a major contributor to the pathogenesis of ND. ER dysfunction has been implicated in ND in which protein misfolding evidently causes ER stress. The consequences of ER stress ranges from an increase in ROS production to altered calcium efflux and proinflammatory signaling in glial cells. Both pathological pathways have links to ferroptotic cell death, which has been implicated to play an important role in ND. Pharmacological targeting of these pathological pathways may help alleviate or slow down neurodegeneration.

Ameliorating effects of probiotics on alterations in iron homeostasis and inflammation in COVID-19

Introduction

The coronavirus disease (COVID-19) is caused by the severe acute syndrome coronavirus-2 (SARS-COV-2) and still threatens human life. This pandemic is still causing increased mortality throughout the world. Many recent studies have been conducted to discover the pathophysiology of this virus.

Material and methods

However, in this narrative review, we attempted to summarize some of the alterations in physiological pathways that were evident in this viral invasion. Excessive inflammation that progresses to cytokine storm, changes in humoral and cell-mediated immunity, and observed alterations in iron metabolism are included in the pathogenesis of the virus. Iron homeostasis disturbances may persist for more than two months after the onset of COVID-19, which may lead to reduced iron bioavailability, hypoferremia, hyperferritinemia, impaired hemoglobin, and red blood cell synthesis. Furthermore, hypoferriemia may impair immune system function. Until now, the traditional treatments discovered are still being tried.

Results

However, using probiotics as an adjuvant was shown to have beneficial effects on both iron homeostasis and immunity in COVID-19. Herein, we discussed the possible mechanisms achieved by probiotics to ameliorate iron and immunity changes based on the available literature.

Conclusion

We concluded that supplementing probiotics with conventional therapy may improve COVID-19 symptoms and outcomes. Taking into consideration the use of good quality probiotics and appropriate dosage, undesirable effects can be avoided.

Modes of Brain Cell Death Following Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a devastating form of stroke with high rates of mortality and morbidity. It induces cell death that is responsible for neurological deficits postinjury. There are no therapies that effectively mitigate cell death to treat ICH. This review aims to summarize our knowledge of ICH-induced cell death with a focus on apoptosis and necrosis. We also discuss the involvement of ICH in recently described modes of cell death including necroptosis, pyroptosis, ferroptosis, autophagy, and parthanatos. We summarize treatment strategies to mitigate brain injury based on particular cell death pathways after ICH.

Interplay Between Iron Overload and Osteoarthritis: Clinical Significance and Cellular Mechanisms

There are multiple diseases or conditions such as hereditary hemochromatosis, hemophilia, thalassemia, sickle cell disease, aging, and estrogen deficiency that can cause iron overload in the human body. These diseases or conditions are frequently associated with osteoarthritic phenotypes, such as progressive cartilage degradation, alterations in the microarchitecture and biomechanics of the subchondral bone, persistent joint inflammation, proliferative synovitis, and synovial pannus. Growing evidences suggest that the conditions of pathological iron overload are associated with these osteoarthritic phenotypes. Osteoarthritis (OA) is an important complication in patients suffering from iron overload-related diseases and conditions. This review aims to summarize the findings and observations made in the field of iron overload-related OA while conducting clinical and basic research works. OA is a whole-joint disease that affects the articular cartilage lining surfaces of bones, subchondral bones, and synovial tissues in the joint cavity. Chondrocytes, osteoclasts, osteoblasts, and synovial-derived cells are involved in the disease. In this review, we will elucidate the cellular and molecular mechanisms associated with iron overload and the negative influence that iron overload has on joint homeostasis. The promising value of interrupting the pathologic effects of iron overload is also well discussed for the development of improved therapeutics that can be used in the field of OA.

SENP1 inhibition suppresses the growth of lung cancer cells through activation of A20-mediated ferroptosis

Background

Ferroptosis is a type of cell death driven by iron accumulation and lipid peroxidation, which is involved in the pathogenesis of various tumors. Small ubiquitin-like modifier (SUMO)-specific protease 1 (SENP1) is a critical SUMO-specific protease, which controls multiple cellular signaling processes. However, the roles and mechanisms of SENP1-mediated protein SUMOylation in the regulation of cell death and ferroptosis remain unexplored.

Methods

The gene expression of SENP1 and ferroptosis-related genes in samples of lung cancer patient and cells were determined by immunohistochemical staining, real-time polymerase chain reaction (RT-qPCR) and Western blot. The association of gene expression with the survival rate of lung cancer patients was analyzed from public database. The erastin and cisplatin was used to induce ferroptosis, and cell ferroptosis were determined by evaluated lipid-reactive oxygen species (ROS), cell viability and electron microscopy. The protein interaction was determined by immunoprecipitation (IP) and shotgun proteomics analysis. An in vivo tumor transplantation model of immunodeficient mice was used to evaluate the effect of SENP1 on tumor growth in vivo.

Results

SENP1 is aberrantly overexpressed in lung cancer cells and is associated with the low survival rate of patients. SENP1 inhibition by short hairpin RNA transduction or a specific inhibitor suppressed the proliferation and growth of lung cancer cells both in vitro and in vivo. SENP1 overexpression protected lung cancer cells from ferroptosis induced by erastin or cisplatin. Transcriptome and proteomics profiles revealed the involvement of SUMOylation regulation of the inflammation signal A20 in SENP1 inhibition-induced ferroptosis. Functional studies proved that A20 functions as a positive inducer and enhances the ferroptosis of A549 cells. A20 was shown to interact with ACSL4 and SLC7A11 to regulate the ferroptosis of lung cancer cells.

Conclusions

SENP1 was identified as a suppressor of ferroptosis through a novel network of A20 SUMOylation links ACSL4 and SLC7A11 in lung cancer cells. SENP1 inhibition promotes ferroptosis and apoptosis and represents a novel therapeutic target for lung cancer therapy.

Targeting ferroptosis in acute kidney injury

Acute kidney injury (AKI) is a major public health problem with high incidence and mortality. As a form of programmed cell death (PCD), ferroptosis could be considered as a process of iron accumulation and enhanced lipid peroxidation. Recently, the fundamental roles of ferroptosis in AKI have attracted much attention. The network mechanism of ferroptosis in AKI and its roles in the AKI to chronic kidney disease (CKD) transition is complicated and multifactorial. Strategies targeting ferroptosis show great potential. Here, we review the research progress on ferroptosis and its participation in AKI. We hope that this work will provide clues for further studies of ferroptosis in AKI.

Causes of and Molecular Targets for the Treatment of Intervertebral Disc Degeneration: A Review

Intervertebral disc degeneration (IVDD) is a pathological condition that can lead to intractable back pain or secondary neurological deficits. There is no fundamental cure for this condition, and current treatments focus on alleviating symptoms indirectly. Numerous studies have been performed to date, and the major strategy for all treatments of IVDD is to prevent cell loss due to programmed or regulated cell death. Accumulating evidence suggests that several types of cell death other than apoptosis, including necroptosis, pyroptosis, and ferroptosis, are also involved in IVDD. In this study, we discuss the molecular pathway of each type of cell death and review the literature that has identified their role in IVDD. We also summarize the recent advances in targeted therapy at the RNA level, including RNA modulations through RNA interference and regulation of non-coding RNAs, for preventing cell death and subsequent IVDD. Therefore, we review the causes and possible therapeutic targets for RNA intervention and discuss the future direction of this research field.

[Role of interaction between reactive oxygen species and ferroptosis pathway in methylglyoxal-induced injury in mouse embryonic osteoblasts]

OBJECTIVE

To explore the interaction between reactive oxygen species (ROS) and ferroptosis in methylglyoxalinduced injury of mouse embryonic osteoblasts (MC3T3-E1 cells).

METHODS

MC3T3-E1 cells were treated with methylglyoxal to establish a cell model of diabetic osteoporosis. CCK-8 assay was used to detect the viability of MC3T3-E1 cells. Rhodamine 123 staining followed by photofluorography was used to examine mitochondrial membrane potential (MMP). The intracellular ROS level was detected by 2', 7'-dichlorodihydrofluorescein diacetate staining with photofluorograph. Alkaline phosphatase (ALP) activity in the cells was detected using an ALP kit, the number of mineralized nodules was determined with alizarin red S staining, and the level of iron ions was detected using a detection kit. The expression level of glutathione peroxidase 4 (GPX4, a marker protein that inhibits ferroptosis) in the osteoblasts was determined using Western blotting.

RESULTS

Treatment of MC3T3-E1 cells with 0.6 mmol/L methylglyoxal for 24 h significantly inhibited the expression level of GPX4 (P < 0.001), increased intracellular iron ion concentration, decreased the cell viability, increased the loss of MMP and intracellular ROS level, decreased both ALP activity and the number of mineralized nodules in the cells (P < 0.001). Co-treatment of MC3T3-E1 cells with 2 mmol/L N-acetylcysteine (NAC, a ROS scavenger) and methylglyoxal significantly increased the expression level of GPX4 (P < 0.01); co-treatment with 4 mmo/L FER-1 (a ferroptosis inhibitor) and methylglyoxal obviously decreased the intracellular ROS level (P < 0.001). Co-treatment of the cells either with NAC and methylglyoxal or with FER-1 and methylglyoxal attenuated methylglyoxal-induced injuries in the osteoblasts (P < 0.001).

CONCLUSION

The interaction between ROS and ferroptosis pathway plays an important role in methylglyoxal-induced injury of mouse embryonic osteoblasts.

The ionophore thiomaltol induces rapid lysosomal accumulation of copper and apoptosis in melanoma

In this report, we investigate the toxicity of the ionophore thiomaltol (Htma) and Cu salts to melanoma. Divalent metal complexes of thiomaltol display toxicity against A375 melanoma cell culture resulting in a distinct apoptotic response at submicromolar concentrations, with toxicity of Cu(tma)2 > Zn(tma)2 >> Ni(tma)2. In metal-chelated media, Htma treatment shows little toxicity, but the combination with supplemental CuCl2, termed Cu/Htma treatment, results in toxicity that increases with suprastoichiometric concentrations of CuCl2 and correlates with the accumulation of intracellular copper. Electron microscopy and confocal laser scanning microscopy of Cu/Htma treated cells shows a rapid accumulation of copper within lysosomes over the course of hours, concurrent with the onset of apoptosis. A buildup of ubiquitinated proteins due to proteasome inhibition is seen on the same timescale and correlates with increases of copper without additional Htma.

Zoledronic acid promotes osteoclasts ferroptosis by inhibiting FBXO9-mediated p53 ubiquitination and degradation

Bisphosphonates (BPs)-related osteonecrosis of jaw (BRONJ) is a severe complication of the long-term administration of BPs. The development of BRONJ is associated with the cell death of osteoclasts, but the underlying mechanism remains unclear. In the current study, the role of Zoledronic acid (ZA), a kind of bisphosphonates, in suppressing the growth of osteoclasts was investigated and its underlying mechanism was explored. The role of ZA in regulating osteoclasts function was evaluated in the RANKL-induced cell model. Cell viability was assessed by cell counting kit-8 (CCK-8) assay and fluorescein diacetate (FDA)-staining. We confirmed that ZA treatment suppressed cell viability of osteoclasts. Furthermore, ZA treatment led to osteoclasts death by facilitating osteoclasts ferroptosis, as evidenced by increased Fe²⁺, ROS, and malonyldialdehyde (MDA) level, and decreased glutathione peroxidase 4 (GPX4) and glutathione (GSH) level. Next, the gene expression profiles of alendronate- and risedronate-treated osteoclasts were obtained from Gene Expression Omnibus (GEO) dataset, and 18 differentially expressed genes were identified using venn diagram analysis. Among these 18 genes, the expression of F-box protein 9 (FBXO9) was inhibited by ZA treatment. Knockdown of FBXO9 resulted in osteoclasts ferroptosis. More important, FBXO9 overexpression repressed the effect of ZA on regulating osteoclasts ferroptosis. Mechanistically, FBXO9 interacted with p53 and decreased the protein stability of p53. Collectively, our study showed that ZA induced osteoclast cells ferroptosis by triggering FBXO9-mediated p53 ubiquitination and degradation.

Ferroptosis in Intracerebral Hemorrhage: A Panoramic Perspective of the Metabolism, Mechanism and Theranostics

Iron is one of the most crucial elements in the human body. In recent years, a kind of programmed, non-apoptotic cell death closely related to iron metabolism-called ferroptosis- has aroused much interest among many scientists. Ferroptosis also interacts with other pathways involved in cell death including iron abnormality, the cystine/glutamate antiporter and lipid peroxidation. Together these pathological pathways exert great impacts on intracerebral hemorrhage (ICH), a lethal cerebrovascular disease with a high incidence rate and mortality rate. Furthermore, the ferroptosis also affects different brain cells (neurons and neuroglial cells) and different organelles (mitochondria and endoplasmic reticulum). Clinical treatments for ferroptosis in ICH have been closely investigated recently. This perspective provides a comprehensive summary of ferroptosis mechanisms after ICH and its interaction with other cell death patterns. Understanding the role of ferroptosis in ICH will open new windows for the future treatments and preventions for ICH and other intracerebral diseases.

Research progress on ferroptosis in diabetic kidney disease

Ferroptosis is a newly discovered form of cell death that differs from other forms of regulated cell death at morphological, biochemical, and genetic levels, and is characterized by iron-dependent accumulation of lipid peroxides. Ferroptosis is closely related to intracellular metabolism of amino acids, lipids, and iron. Hence, its regulation may facilitate disease intervention and treatment. Diabetic kidney disease is one of the most serious complications of diabetes, which leads to serious psychological and economic burdens to patients and society when it progresses to end-stage renal disease. At present, there is no effective treatment for diabetic kidney disease. Ferroptosis has been recently identified in animal models of diabetic kidney disease. Herein, we systematically reviewed the regulatory mechanism of ferroptosis, its association with different forms of cell death, summarized its relationship with diabetic kidney disease, and explored its regulation to intervene with the progression of diabetic kidney disease or as a treatment.

Lipocalin-2 silencing suppresses inflammation and oxidative stress of acute respiratory distress syndrome by ferroptosis via inhibition of MAPK/ERK pathway in neonatal mice

Neonatal acute respiratory distress syndrome (ARDS) has high morbidity and mortality rates worldwide, but there is a lack of pharmacologic treatment and clinical targeted therapies. In this study, we aimed to explore the effects of Lipocalin-2 (LCN2) on ferroptosis-mediated inflammation and oxidative stress in neonatal ARDS and the potential mechanism. In this study, we established an in vivo ARDS mouse model and an in vitro ARDS cell model by LPS (Lipopolysaccharide) stimulation. Lung tissue injury was evaluated by wet/dry ratios and histopathological examination. LCN2 expression was detected by qRT-PCR and Western blot. Inflammatory factors, oxidative stress and apoptosis were also detected. Ferroptosis was identified by detection of Fe²⁺ level and ferroptosis-associated protein expressions. Mitogen-activated protein kinases (MAPK)/extracellular signal-regulated kinase (ERK) pathway signaling was examined by Western blot analysis. The data revealed that LCN2 expression was significantly upregulated in neonatal mice with ARDS. Interference with LCN2 protected LPS-induced lung in neonatal mouse by reducing the radio of wet/dry and alleviating pathological damages. In addition, LCN2 silencing repressed LPS-induced inflammation, oxidative stress in vivo and in vitro, as well as apoptosis. Meanwhile, decreased level of Fe²⁺ and transferrin while increased levels of ferritin heavy chain 1 (FTH1) and glutathione peroxidase 4 (GPX4) were observed. The expression MAPK/ERK pathway was inhibited by depletion of LCN2. The present results suggest that LCN2 knockdown protected LPS-induced ARDS model via inhibition of ferroptosis-related inflammation and oxidative stress by inhibiting the MAPK/ERK pathway, thereby presenting a novel target for the treatment of ARDS.

Hypermethylation of the Nrf2 Promoter Induces Ferroptosis by Inhibiting the Nrf2-GPX4 Axis in COPD

Background

Nuclear factor E2-related factor 2 (Nrf2) is involved in oxidative stress and lung inflammation and regulates the etiology of chronic obstructive pulmonary disease (COPD). Ferroptosis is characterized by the accumulation of lipid reactive oxygen species (ROS) via ferrous ion-dependent Fenton reactions and is involved in COPD. However, the role of Nrf2 in ferroptosis and its epigenetic regulation in the pathogenesis of COPD remain unclear.

Methods

Ferroptosis was detected by 4-HNE, MDA, C11BODIPY, DCFH-DA, Peals’ staining and CCK-8 assays. qPCR and Western blotting were performed to examine the Nrf2 levels in peripheral lung tissues, primary epithelial cells collected from patients with COPD and subjects with normal pulmonary function (never-smoker [control-NS]; smoker [control-S]), and cigarette smoke extract (CSE)-treated human bronchial epithelial (HBE) cells. ELISA was used to quantify IL-8 and IL-1β levels. Methylation of the Nrf2 promoter was analyzed by bisulfite sequencing and pyrosequencing.

Results

Ferroptosis was involved in COPD and glutathione peroxidase 4 (GPX4) expression was downregulated in the COPD group. Reactive oxygen species (ROS), lipid peroxides and MDA were increased, but GPX4 and SOD were exhausted in CSE-treated HBE cells. The production of IL-1β and IL-8 was promoted in HBE cells in response to CSE but could be reversed by the ferroptosis inhibitor fer-1. The Nrf2 level was significantly decreased in the COPD group compared with the control-S and control-NS groups. Increased Nrf2 expression enhanced GPX4 and SOD levels and inhibited ferroptosis and proinflammatory cytokines in the supernatant. Inhibition of GPX4 reversed the effect of Nrf2 overexpression and promoted ferroptosis. Two specific CpG sites within the Nrf2 promoter were hypermethylated in the COPD group. Similarly, CSE-treated HBE cells exhibited hypermethylation of the Nrf2 gene.

Conclusion

Nrf2 expression was downregulated in the lungs of COPD patients due to hypermethylation of the Nrf2 promoter, inhibiting Nrf2/GPX4 and ferroptosis, which is related to the initiation and progression of COPD. Targeting Nrf2/GPX4 may inhibit ferroptosis, which could provide strategies to delay or treat COPD.

A Ferroptosis-Related lncRNAs Signature Predicts Prognosis and Therapeutic Response of Gastric Cancer

Background: Accumulating literature demonstrates that long noncoding RNAs (lncRNAs) are involved in ferroptosis and gastric cancer progression. However, the predictive value of ferroptosis-related lncRNAs for prognosis and therapeutic response is yet to be elucidated in gastric cancer (GC). Method: The transcriptomic data and corresponding clinical information of GC patients were obtained from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) database. The association between ferroptosis-related lncRNAs and ferroptosis regulators was analyzed by Spearman correlation analysis. Then, we established a risk predictive model based on the ferroptosis-related lncRNAs using multivariate Cox regression analysis. Furthermore, we performed correlation analysis for the risk score and characteristics of biological processes, immune landscape, stromal activity, genomic integrity, drug response, and immunotherapy efficacy. Results: We constructed a 17-ferroptosis-related-lncRNA signature via multivariate Cox analysis to divide patients into two groups: low- and high-risk groups. The low-risk group was linked to prolonged overall survival and relapse-free survival. The risk score had good predictive ability to predict the prognosis of GC patients compared with other clinical biomarkers. We found that the high-risk group was associated with activation of carcinogenetic signaling pathways, including stromal activation, epithelial-mesenchymal-transition (EMT) activation, and immune escape through integrated bioinformatics analysis. In contrast, the low-risk group was associated with DNA replication, immune-flamed state, and genomic instability. Additionally, through Spearman correlation analysis, we found that patients in the high-risk group may respond well to drugs targeting cytoskeleton, WNT signaling, and PI3K/mTOR signaling, and drugs targeting chromatin histone acetylation, cell cycle, and apoptosis regulation could bring more benefits for the low-risk group. The high-risk group was associated with poor immunotherapy efficacy. Conclusion: Our study systematically evaluated the role of ferroptosis-related lncRNAs in t tumor microenvironment, therapeutic response, and prognosis of GC. Risk score-based stratification could reflect the characteristic of biological processes, immune landscape, stromal activity, genomic stability, and pharmaceutical profile in GC patients. The ferroptosis-related lncRNA signature could serve as a reliable biomarker to predict prognosis and therapeutic response of patients with GC.

Ferroptosis-related gene signature predicts the prognosis of papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer (TC), accounting for more than 80% of all cases. Ferroptosis is a novel iron-dependent and Reactive oxygen species (ROS) reliant type of cell death which is distinct from the apoptosis, necroptosis and pyroptosis. Considerable studies have demonstrated that ferroptosis is involved in the biological process of various cancers. However, the role of ferroptosis in PTC remains unclear. This study aims at exploring the expression of ferroptosis-related genes (FRG) and their prognostic values in PTC.

METHODS

A ferroptosis-related gene signature was constructed using lasso regression analysis through the PTC datasets of the Cancer Genome Atlas (TCGA). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to investigate the bioinformatics functions of significantly different genes (SDG) of ferroptosis. Additionally, the correlations of ferroptosis and immune cells were assessed through the single-sample gene set enrichment analysis (ssGSEA) and CIBERSORT database. Finally, SDG were test in clinical PTC specimens and normal thyroid tissues.

RESULTS

LASSO regression model was utilized to establish a novel FRG signature with 10 genes (ANGPTL7, CDKN2A, DPP4, DRD4, ISCU, PGD, SRXN1, TF, TFRC, TXNRD1) to predicts the prognosis of PTC, and the patients were separated into high-risk and low-risk groups by the risk score. The high-risk group had poorer survival than the low-risk group (p < 0.001). Receiver operating characteristic (ROC) curve analysis confirmed the signature's predictive capacity. Multivariate regression analysis identified the prognostic signature-based risk score was an independent prognostic indicator for PTC. The functional roles of the DEGs in the TGCA PTC cohort were explored using GO enrichment and KEGG pathway analyses. Immune related analysis demonstrated that the most types of immune cells and immunological function in the high-risk group were significant different with those in the low-risk group. Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) verified the SDG have differences in expression between tumor tissue and normal thyroid tissue. In addition, cell experiments were conducted to observe the changes in cell morphology and expression of signature's genes with the influence of ferroptosis induced by sorafenib.

CONCLUSIONS

We identified differently expressed FRG that may involve in PTC. A ferroptosis-related gene signature has significant values in predicting the patients' prognoses and targeting ferroptosis may be an alternative for PTC's therapy.

Sesamin attenuates PM2.5-induced cardiovascular injury by inhibiting ferroptosis in rats

Objective: This study aimed to elucidate the pharmacological effects of sesamin (Ses) and its mechanism of action towards PM_2.5-induced cardiovascular injuries. Method: Forty Sprague Dawley (SD) rats were randomly divided into five groups: a saline control group; a PM_2.5 exposure group; and low-, middle-, and high-dose Ses pretreatment groups. The SD rats were pretreated with different concentrations of Ses for 21 days. Afterward, the rats were exposed to ambient PM_2.5 by intratracheal instillation every other day for a total of three times. The levels of inflammatory markers, including tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), and interleukin-6 (IL-6), and indicators related to oxidative responses, such as total superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA), were measured in the blood and heart. The expression of ferroptosis-related proteins in heart tissues was determined via western blot and immunohistochemistry. Results: Ses pretreatment substantially ameliorated cardiovascular injuries in rats as evidenced by the decrease in the pathological score and collagen area. The decreased levels of SOD, GSH, and GSH-Px in the heart and serum were inhibited by Ses. In addition, Ses not only notably increased the activity of antioxidant enzymes but also reduced the levels of MDA, CK, LDH, CK-MB, IL-6, TNF-α, IL-1β, and IL-6. Furthermore, Ses pretreatment upregulated the expression levels of GPX4, SLC7A11, TFRC, and FPN1 and inhibited the expression levels of FTH1 and FTL. Conclusion: Ses pretreatment could ameliorate PM_2.5-induced cardiovascular injuries perhaps by inhibiting ferroptosis. Therefore, Ses pretreatment may be a novel strategy for the prevention and treatment of PM_2.5-induced cardiovascular injury.

Old and New Players of Inflammation and Their Relationship With Cancer Development

Pathogens or genotoxic agents continuously affect the human body. Acute inflammatory reaction induced by a non-sterile or sterile environment is triggered for the efficient elimination of insults that caused the damage. According to the insult, pathogen-associated molecular patterns, damage-associated molecular patterns, and homeostasis-altering molecular processes are released to facilitate the arrival of tissue resident and circulating cells to the injured zone to promote harmful agent elimination and tissue regeneration. However, when inflammation is maintained, a chronic phenomenon is induced, in which phagocytic cells release toxic molecules damaging the harmful agent and the surrounding healthy tissues, thereby inducing DNA lesions. In this regard, chronic inflammation has been recognized as a risk factor of cancer development by increasing the genomic instability of transformed cells and by creating an environment containing proliferation signals. Based on the cancer immunoediting concept, a rigorous and regulated inflammation process triggers participation of innate and adaptive immune responses for efficient elimination of transformed cells. When immune response does not eliminate all transformed cells, an equilibrium phase is induced. Therefore, excessive inflammation amplifies local damage caused by the continuous arrival of inflammatory/immune cells. To regulate the overstimulation of inflammatory/immune cells, a network of mechanisms that inhibit or block the cell overactivity must be activated. Transformed cells may take advantage of this process to proliferate and gradually grow until they become preponderant over the immune cells, preserving, increasing, or creating a microenvironment to evade the host immune response. In this microenvironment, tumor cells resist the attack of the effector immune cells or instruct them to sustain tumor growth and development until its clinical consequences. With tumor development, evolving, complex, and overlapping microenvironments are arising. Therefore, a deeper knowledge of cytokine, immune, and tumor cell interactions and their role in the intricated process will impact the combination of current or forthcoming therapies.