Inhibition of ACSL4 attenuates ferroptotic damage after pulmonary ischemia-reperfusion

Hypoxia and ferroptosis

Ferroptosis is a novel, iron-dependent cell death characterized by the excessive accumulation of ferroptosis lipid peroxides ultimately leading to oxidative damage to the cell membrane. Iron, lipid, amino acid metabolism, and other signaling pathways all control ferroptosis. Numerous bodily tissues experience hypoxia under normal and pathological circumstances. Tissue cells can adjust to these changes by activating the hypoxia-inducible factor (HIF) signaling pathway and other mechanisms in response to the hypoxic environment. In recent years, there has been increasing evidence that hypoxia and ferroptosis are closely linked, and that hypoxia can regulate ferroptosis in specific cells and conditions through different pathways. In this paper, we review the possible positive and negative regulatory mechanisms of ferroptosis by hypoxia-inducible factors, as well as ferroptosis-associated ischemic diseases, with the intention of delivering novel therapeutic avenues for the defense and management of hypoxic illnesses linked to ferroptosis.

Peroxiredoxin 6 suppresses ferroptosis in lung endothelial cells

Peroxiredoxin 6 (Prdx6) repairs peroxidized membranes by reducing oxidized phospholipids, and by replacing oxidized sn-2 fatty acyl groups through hydrolysis/reacylation by its phospholipase A2 (aiPLA2) and lysophosphatidylcholine acyltransferase activities. Prdx6 is highly expressed in the lung, and intact lungs and cells null for Prdx6 or with single-point mutations that inactivate either Prdx6-peroxidase or aiPLA2 activity alone exhibit decreased viability, increased lipid peroxidation, and incomplete repair when exposed to paraquat, hyperoxia, or organic peroxides. Ferroptosis is form of cell death driven by the accumulation of phospholipid hydroperoxides. We studied the role of Prdx6 as a ferroptosis suppressor in the lung. We first compared the expression Prdx6 and glutathione peroxidase 4 (GPx4) and visualized Prdx6 and GPx4 within the lung. Lung Prdx6 mRNA levels were five times higher than GPx4 levels. Both Prdx6 and GPx4 localized to epithelial and endothelial cells. Prdx6 knockout or knockdown sensitized lung endothelial cells to erastin-induced ferroptosis. Cells with genetic inactivation of either aiPLA2 or Prdx6-peroxidase were more sensitive to ferroptosis than WT cells, but less sensitive than KO cells. We then conducted RNA-seq analyses in Prdx6-depleted cells to further explore how the loss of Prdx6 sensitizes lung endothelial cells to ferroptosis. Prdx6 KD upregulated transcriptional signatures associated with selenoamino acid metabolism and mitochondrial function. Accordingly, Prdx6 deficiency blunted mitochondrial function and increased GPx4 abundance whereas GPx4 KD had the opposite effect on Prdx6. Moreover, we detected Prdx6 and GPx4 interactions in intact cells, suggesting that both enzymes cooperate to suppress lipid peroxidation. Notably, Prdx6-depleted cells remained sensitive to erastin-induced ferroptosis despite the compensatory increase in GPx4. These results show that Prdx6 suppresses ferroptosis in lung endothelial cells and that both aiPLA2 and Prdx6-peroxidase contribute to this effect. These results also show that Prdx6 supports mitochondrial function and modulates several coordinated cytoprotective pathways in the pulmonary endothelium.

The cell biology of ferroptosis

Ferroptosis is a non-apoptotic cell death mechanism characterized by iron-dependent membrane lipid peroxidation. Here, we review what is known about the cellular mechanisms mediating the execution and regulation of ferroptosis. We first consider how the accumulation of membrane lipid peroxides leads to the execution of ferroptosis by altering ion transport across the plasma membrane. We then discuss how metabolites and enzymes that are distributed in different compartments and organelles throughout the cell can regulate sensitivity to ferroptosis by impinging upon iron, lipid and redox metabolism. Indeed, metabolic pathways that reside in the mitochondria, endoplasmic reticulum, lipid droplets, peroxisomes and other organelles all contribute to the regulation of ferroptosis sensitivity. We note how the regulation of ferroptosis sensitivity by these different organelles and pathways seems to vary between different cells and death-inducing conditions. We also highlight transcriptional master regulators that integrate the functions of different pathways and organelles to modulate ferroptosis sensitivity globally. Throughout this Review, we highlight open questions and areas in which progress is needed to better understand the cell biology of ferroptosis.

Unraveling the Molecular Regulation of Ferroptosis in Respiratory Diseases

Ferroptosis, a type of programmed cell death that relies on iron, is distinct in terms of its morphological, biochemical and genetic features. Unlike other forms of cell death, such as autophagy, apoptosis, necrosis, and pyroptosis, ferroptosis is primarily caused by lipid peroxidation. Cells that die due to iron can potentially trigger an immune response which intensifies inflammation and causes severe inflammatory reactions that eventually lead to multiple organ failure. In recent years, ferroptosis has been identified in an increasing number of medical fields, including neurological pathologies, chronic liver diseases and sepsis. Ferroptosis has the potential to cause an inflammatory tempest, with many of the catalysts and pathological indications of respiratory ailments being linked to inflammatory reactions. The growing investigation into ferroptosis in respiratory disorders has also garnered significant interest to better understand the mechanism of ferroptosis in these diseases. In this review, the recent progress in understanding the molecular control of ferroptosis and its mechanism in different respiratory disorders is examined. In addition, this review discusses current challenges and prospects for understanding the link between respiratory diseases and ferroptosis.

Ferroptosis in organ ischemia-reperfusion injuries: recent advancements and strategies

Ferroptosis is a newly discovered type of regulated cell death participated in multiple diseases. Different from other classical cell death programs such as necrosis and apoptosis, ferroptosis involving iron-catalyzed lipid peroxidation is characterized by Fe2+ accumulation and mitochondria alterations. The phenomenon of oxidative stress following organ ischemia-reperfusion (I/R) has recently garnered attention for its connection to the onset of ferroptosis and subsequent reperfusion injuries. This article provides a comprehensive overview underlying the mechanisms of ferroptosis, with a further focus on the latest research progress regarding interference with ferroptotic pathways in organ I/R injuries, such as intestine, lung, heart, kidney, liver, and brain. Understanding the links between ferroptosis and I/R injury may inform potential therapeutic strategies and targeted agents.

Suppressing Endoplasmic Reticulum Stress Alleviates LPS-Induced Acute Lung Injury via Inhibiting Inflammation and Ferroptosis

Acute lung injury (ALI) is a life-threatening clinical disorder with high mortality rate. Ferroptosis is a new type of programmed cell death with lipid peroxidation and iron ion overloading as the main characteristics. Endoplasmic reticulum (ER) stress and ferroptosis play pivotal roles in the pathogenesis of ALI. The study aimed to investigate the underlying relationship between ER stress and ferroptosis in ALI. The ER stress inhibitor 4-phenylbutyric acid (4-PBA) alleviated LPS-induced inflammation, and decreased IL-1β, IL-6, and TNF-α levels in BALF and lungs. The increased MDA and decreased GSH induced by LPS were partially reversed by 4-PBA, which also inhibited the expressions of ferroptosis-related protein ACSL4, COX-2, and FTH1. TEM further confirmed the ferroptosis within airway epithelia cells was ameliorated by 4-PBA. Moreover, 4-PBA reduced the production of ROS and lipid ROS in LPS-exposed BEAS-2B cells in a concentration-dependent way. Meanwhile, 4-PBA mitigated LPS-induced cell apoptosis in vivo and in vitro. Mechanistically, the MAPK signaling pathway activated by LPS was downregulated by 4-PBA. Collectively, these findings suggested that 4-PBA protected against ALI by inhibiting inflammation and ferroptosis through downregulating ER stress, thus providing a potential intervention for ALI and revealing the possible interaction between ER stress and ferroptosis in ALI.

Knockdown of JMJD3 ameliorates cigarette smoke extract-triggered bronchial epithelial cell injury via ACSL4-dependent ferroptosis

Chronic obstructive pulmonary disease (COPD), a heterogeneity of chronic respiratory disease pattern, presents considerable prevalence and mortality. We aimed to explore the role and mechanisms of Jumonji domain-containing protein-3 (JMJD3) in COPD. The viability and JMJD3 expression in human bronchial epithelial cell line BEAS-2B were respectively assayed by CCK-8 assay and Western blot following stepwise exposure to increasing concentrations of cigarette smoke extract (CSE). After JMJD3 was silenced and acyl-CoA synthetase long-chain family member 4 (ACSL4) was overexpressed in CSE-treated BEAS-2B cells, cell viability, cytotoxicity, oxidative stress and total iron level were estimated using kits. ELISA estimated inflammatory levels. DCFH-DA probe and BODIPY 581/591 C11 probe were exposed to assess ROS production and lipid peroxidation. Western blot tested the expressions of ferroptosis-associated proteins. Besides, H3K27me3 and ACSL4 expressions were tested by Western blot and immunofluorescence staining. In CSE-induced BEAS-2B cells, JMJD3 expression was increased and deletion of JMJD3 improved cell viability, reduced LDH release, mitigated inflammation, oxidative stress and inhibited ferroptosis. Moreover, JMJD3 interference raised H3K27me3 expression whereas lessened ACSL4 expression in CSE-treated BEAS-2B cells. CSE exposure reduced the abundance of ACSL4 in H3K27me3 antibody. Further ACSL4 elevation reversed the impacts of JMJD3 silencing on the damage of CSE-induced BEAS-2B cells. Collectively, JMJD3 depletion might suppress ferroptosis mediated by ACSL4 to alleviate CSE-triggered inflammation and oxidative stress in BEAS-2B cells.

Crosstalk between ferroptosis and cuproptosis: From mechanism to potential clinical application

Ferroptosis and cuproptosis, regulated forms of cell death resulting from metal ion accumulation, are closely related in terms of occurrence, cell metabolism, signaling pathways, and drug resistance. Notably, it is now understood that these processes play crucial roles in regulating physiological and pathological processes, especially in tumor development. Consequently, ferroptosis and cuproptosis have gained increasing significance as potential targets for anti-cancer drug development. This article systematically outlines the molecular mechanisms and cross-talk components of both ferroptosis and cuproptosis, elucidating their impacts on cancer. Furthermore, it investigates the clinical perspective of targeted ferroptosis and cuproptosis in cancer chemotherapy, immunotherapy, and radiotherapy. Our discussion extends to a comparative analysis of nanoparticles developed based on the mechanisms of ferroptosis and cuproptosis in cancer, contrasting them with current conventional therapies. Opportunities and challenges in cancer treatment are explored, emphasizing the potential therapeutic direction of co-targeting ferroptosis and cuproptosis. The article also attempts to analyze the clinical applications of this co-targeting approach for cancer treatment while summarizing the existing barriers that require overcoming.

Ferroptosis and its modulators: A raising target for cancer and Alzheimer's disease

The process of ferroptosis, a recently identified form of regulated cell death (RCD) is associated with the overloading of iron species and lipid-derived ROS accumulation. Ferroptosis is induced by various mechanisms such as inhibiting system Xc, glutathione depletion, targeting excess iron, and directly inhibiting GPX4 enzyme. Also, ferroptosis inhibition is achieved by blocking excessive lipid peroxidation by targeting different pathways. These mechanisms are often related to the pathophysiology and pathogenesis of diseases like cancer and Alzheimer's. Fundamentally distinct from other forms of cell death, such as necrosis and apoptosis, ferroptosis differs in terms of biochemistry, functions, and morphology. The mechanism by which ferroptosis acts as a regulatory factor in many diseases remains elusive. Studying the activation and inhibition of ferroptosis as a means to mitigate the progression of various diseases is a highly intriguing and actively researched topic. It has emerged as a focal point in etiological research and treatment strategies. This review systematically summarizes the different mechanisms involved in the inhibition and induction of ferroptosis. We have extensively explored different agents that can induce or inhibit ferroptosis. This review offers current perspectives on recent developments in ferroptosis research, highlighting the disease's etiology and presenting references to enhance its understanding. It also explores new targets for the treatment of cancer and Alzheimer's disease.

LPCAT3/LPLAT12 deficiency in the liver ameliorates acetaminophen-induced acute liver injury

Acetaminophen (APAP) is a double-edged sword, mainly depending on the dosage. A moderate dose of APAP is effective for fever and pain relief; however, an overdose induces acute liver injury. The mechanism underlying APAP-induced acute liver failure is unclear, and its treatment is limited. A recent report has shown that several oxidized phospholipids are associated with APAP-induced acute liver failure. Lysophosphatidylcholine acyltransferase 3 (Lpcat3, Lplat12), which is highly expressed in the liver, preferentially catalyzes the incorporation of arachidonate into lysophospholipids (PLs). In the present study, we investigated the roles of Lpcat3 on APAP-induced acute liver injury using liver-specific Lpcat3-knockout mice. Hepatic Lpcat3 deficiency reduced the degree of APAP-induced necrosis of hepatocytes around Zone 3 and ameliorated the elevation of hepatic injury serum marker levels, and prolonged survival. Lipidomic analysis showed that the accumulation of oxidized and hydroperoxidized phospholipids was suppressed in Lpcat3-knockout mice. The amelioration of APAP-induced acute liver injury was due not only to the reduction in the lipid synthesis of arachidonic acid PLs because of Lpcat3 deficiency, but also to the promotion of the APAP detoxification pathway by facilitating the conjugation of glutathione and N-acetyl-p-benzoquinone imine. Our findings suggest that Lpcat3 is a potential therapeutic target for treating APAP-induced acute liver injury.

Ferroptosis in acute kidney injury following crush syndrome: A novel target for treatment

BACKGROUND

Crush syndrome (CS) is a kind of traumatic and ischemic injury that seriously threatens life after prolonged compression. It is characterized by systemic inflammatory reaction, myoglobinuria, hyperkalemia and acute kidney injury (AKI). Especially AKI, it is the leading cause of death from CS. There are various cell death forms in AKI, among which ferroptosis is a typical form of cell death. However, the role of ferroptosis has not been fully revealed in CS-AKI.

AIM OF REVIEW

This review aimed to summarize the evidence of ferroptosis in CS-AKI and its related molecular mechanism, discuss the therapeutic significance of ferroptosis in CS-AKI, and open up new ideas for the treatment of CS-AKI.

KEY SCIENTIFIC CONCEPTS OF REVIEW

One of the main pathological manifestations of CS-AKI is renal tubular epithelial cell dysfunction and cell death, which has been attributed to massive deposition of myoglobin. Large amounts of myoglobin released from damaged muscle deposited in the renal tubules, impeding the normal renal tubules function and directly damaging the tubules with oxidative stress and elevated iron levels. Lipid peroxidation damage and iron overload are the distinguishing features of ferroptosis. Moreover, high levels of pro-inflammatory cytokines and damage-associated molecule pattern molecules (HMGB1, double-strand DNA, and macrophage extracellular trap) in renal tissue have been shown to promote ferroptosis. However, how ferroptosis occurs in CS-AKI and whether it can be a therapeutic target remains unclear. In our current work, we systematically reviewed the occurrence and underlying mechanism of ferroptosis in CS-AKI.

Rosiglitazone inhibits acyl-CoA synthetase long-chain family number 4 and improves secondary brain injury in a rat model of surgical brain injury

Ferroptosis is a recently discovered non-apoptotic form of cellular death. Acyl-CoA synthetase long-chain family number 4 (ACSL4) is necessary for iron-dependent cellular death, and reactive oxygen species (ROS) produced by ACSL4 are the executioners of ferroptosis. Rosiglitazone improves ferroptosis by inhibiting ACSL4. There is no research indicating whether ACSL4 plays a role in cell death after surgical brain injury (SBI). This study aimed to investigate the role of ACSL4 in SBI via the ferroptosis pathway. Ninety male Sprague-Dawley rats were examined using a model of SBI. Subsequently, the inhibitory effect of rosiglitazone on ACSL4 was assessed via western blot, real-time polymerase chain reaction (PCR), immunofluorescence, fluoro-jade C staining, Perl's staining, ROS assay, and neurological scoring. The results showed that compared with the Sham group, the protein levels of ACSL4 and transferrin were significantly increased after SBI. Administration of rosiglitazone significantly reduced neuronal necrosis, iron deposition, brain water content and ROS in brain tissue and ameliorated neurological deficits at 48 h after SBI, which was concomitant with decreased transferrin expression. These findings demonstrate that SBI-induced upregulation of ACSL4 may be partly mediated by the ferroptosis pathway, which can be reversed by rosiglitazone administration.

Therapeutic Approaches Targeting Ferroptosis in Cardiomyopathy

The term cardiomyopathy refers to a group of heart diseases that cause severe heart failure over time. Cardiomyopathies have been proven to be associated with ferroptosis, a non-apoptotic form of cell death. It has been shown that some small molecule drugs and active ingredients of herbal medicine can regulate ferroptosis, thereby alleviating the development of cardiomyopathy. This article reviews recent discoveries about ferroptosis, its role in the pathogenesis of cardiomyopathy, and the therapeutic options for treating ferroptosis-associated cardiomyopathy. The article aims to provide insights into the basic mechanisms of ferroptosis and its treatment to prevent cardiomyopathy and related diseases.

Acyl-CoA synthase ACSL4: an essential target in ferroptosis and fatty acid metabolism

ABSTRACT

Long-chain acyl-coenzyme A (CoA) synthase 4 (ACSL4) is an enzyme that esterifies CoA into specific polyunsaturated fatty acids, such as arachidonic acid and adrenic acid. Based on accumulated evidence, the ACSL4-catalyzed biosynthesis of arachidonoyl-CoA contributes to the execution of ferroptosis by triggering phospholipid peroxidation. Ferroptosis is a type of programmed cell death caused by iron-dependent peroxidation of lipids; ACSL4 and glutathione peroxidase 4 positively and negatively regulate ferroptosis, respectively. In addition, ACSL4 is an essential regulator of fatty acid (FA) metabolism. ACSL4 remodels the phospholipid composition of cell membranes, regulates steroidogenesis, and balances eicosanoid biosynthesis. In addition, ACSL4-mediated metabolic reprogramming and antitumor immunity have attracted much attention in cancer biology. Because it facilitates the cross-talk between ferroptosis and FA metabolism, ACSL4 is also a research hotspot in metabolic diseases and ischemia/reperfusion injuries. In this review, we focus on the structure, biological function, and unique role of ASCL4 in various human diseases. Finally, we propose that ACSL4 might be a potential therapeutic target.

Ferroptosis in the post-transplantation inflammatory response

Transplantation is a life-saving therapy for patients with end-stage organ disease. Successful outcomes after transplantation require mitigation of the post-transplant inflammatory response, limiting alloreactivity, and prevention of organ rejection. Traditional immunosuppressive regimens aim to dampen the adaptive immune response; however, recent studies have shown the feasibility and efficacy of targeting the innate immune response. Necroinflammation initiated by donor organ cell death is implicated as a critical mediator of primary graft dysfunction, acute rejection, and chronic rejection. Ferroptosis is a form of regulated cell death that triggers post-transplantation inflammation and drives the activation of both innate and adaptive immune cells. There is a growing acceptance of the clinical relevance of ferroptosis to solid organ transplantation. Modulating ferroptosis may be a potentially promising strategy to reduce complications after organ transplantation.

The mechanism of ferroptosis and its related diseases

Ferroptosis, a regulated form of cellular death characterized by the iron-mediated accumulation of lipid peroxides, provides a novel avenue for delving into the intersection of cellular metabolism, oxidative stress, and disease pathology. We have witnessed a mounting fascination with ferroptosis, attributed to its pivotal roles across diverse physiological and pathological conditions including developmental processes, metabolic dynamics, oncogenic pathways, neurodegenerative cascades, and traumatic tissue injuries. By unraveling the intricate underpinnings of the molecular machinery, pivotal contributors, intricate signaling conduits, and regulatory networks governing ferroptosis, researchers aim to bridge the gap between the intricacies of this unique mode of cellular death and its multifaceted implications for health and disease. In light of the rapidly advancing landscape of ferroptosis research, we present a comprehensive review aiming at the extensive implications of ferroptosis in the origins and progress of human diseases. This review concludes with a careful analysis of potential treatment approaches carefully designed to either inhibit or promote ferroptosis. Additionally, we have succinctly summarized the potential therapeutic targets and compounds that hold promise in targeting ferroptosis within various diseases. This pivotal facet underscores the burgeoning possibilities for manipulating ferroptosis as a therapeutic strategy. In summary, this review enriched the insights of both investigators and practitioners, while fostering an elevated comprehension of ferroptosis and its latent translational utilities. By revealing the basic processes and investigating treatment possibilities, this review provides a crucial resource for scientists and medical practitioners, aiding in a deep understanding of ferroptosis and its effects in various disease situations.

STING/ACSL4 axis-dependent ferroptosis and inflammation promote hypertension-associated chronic kidney disease

Hypertension is a primary modifiable risk factor for cardiovascular diseases, which often induces renal end-organ damage and complicates chronic kidney disease (CKD). In the present study, histological analysis of human kidney samples revealed that hypertension induced mtDNA leakage and promoted the expression of stimulator of interferon genes (STING) in renal epithelial cells. We used angiotensin II (AngII)- and 2K1C-treated mouse kidneys to elucidate the underlying mechanisms. Abnormal renal mtDNA packing caused by AngII promoted STING-dependent production of inflammatory cytokines, macrophage infiltration, and a fibrogenic response. STING knockout significantly decreased nuclear factor-κB activation and immune cell infiltration, attenuating tubule atrophy and extracellular matrix accumulation in vivo and in vitro. These effects delayed CKD progression. Immunoprecipitation assays and liquid chromatography-tandem mass spectrometry showed that STING and ACSL4 were directly combined at the D53 and K412 amino acids of ACSL4. Furthermore, STING induced renal inflammatory response and fibrosis through ACSL4-dependent ferroptosis. Last, inhibition of ACSL4 using small interfering RNA, rosiglitazone, or Fer-1 downregulated AngII-induced mtDNA-STING-dependent renal inflammation. These results suggest that targeting the STING/ACSL4 axis might represent a potential strategy for treating hypertension-associated CKD.

Role and mechanism of ferroptosis in acute lung injury

Ferroptosis is a new non-apoptotic cell death caused by the accumulation of dysregulated metabolism of ferric iron, amino acids or lipid peroxidation. Increasing studies suggest that ferroptosis is involved in the acute lung injury (ALI). This article aims to review the role of ferroptosis in ALI. ALI is a common respiratory disease and presents a high mortality rate. Inhibiting cell ferroptosis of lung improves the ALI. In addition, several signaling pathways are related to ferroptosis in ALI, involving in iron homeostasis, lipid peroxidation, and amino acid metabolism. Moreover, there are various key factors to regulate the occurrence of ferroptosis in ALI, such as ACSL4, NRF2, and P53. The ACSL4 promotes the ferroptosis, while the NRF2 alleviates the ferroptosis in ALI. The main effect of P53 is to promote ferroptosis. Accordingly, ferroptosis is involved in ALI and may be an important therapeutic target for ALI.

Liproxstatin-1 Alleviates Lung Transplantation-induced Cold Ischemia-Reperfusion Injury by Inhibiting Ferroptosis

BACKGROUND

Primary graft dysfunction, which is directly related to cold ischemia-reperfusion (CI/R) injury, is a major obstacle in lung transplantation (LTx). Ferroptosis, a novel mode of cell death elicited by iron-dependent lipid peroxidation, has been implicated in ischemic events. This study aimed to investigate the role of ferroptosis in LTx-CI/R injury and the effectiveness of liproxstatin-1 (Lip-1), a ferroptosis inhibitor, in alleviating LTx-CI/R injury.

METHODS

LTx-CI/R-induced signal pathway alterations, tissue injury, cell death, inflammatory responses, and ferroptotic features were examined in human lung biopsies, the human bronchial epithelial (BEAS-2B) cells, and the mouse LTx-CI/R model (24-h CI/4-h R). The therapeutic efficacy of Lip-1 was explored and validated both in vitro and in vivo.

RESULTS

In human lung tissues, LTx-CI/R activated ferroptosis-related signaling pathway, increased the tissue iron content and lipid peroxidation accumulation, and altered key protein (GPX4, COX2, Nrf2, and SLC7A11) expression and mitochondrial morphology. In BEAS-2B cells, the hallmarks of ferroptosis were significantly evidenced at the setting of both CI and CI/R compared with the control, and the effect of adding Lip-1 only during CI was much better than that of only during reperfusion by Cell Counting Kit-8. Furthermore, Lip-1 administration during CI markedly relieved LTx-CI/R injury in mice, as indicated by significant improvement in lung pathological changes, pulmonary function, inflammation, and ferroptosis.

CONCLUSIONS

This study revealed the existence of ferroptosis in the pathophysiology of LTx-CI/R injury. Using Lip-1 to inhibit ferroptosis during CI could ameliorate LTx-CI/R injury, suggesting that Lip-1 administration might be proposed as a new strategy for organ preservation.

YAP/ACSL4 Pathway-Mediated Ferroptosis Promotes Renal Fibrosis in the Presence of Kidney Stones

The potential association between calcium oxalate stones and renal fibrosis has been extensively investigated; however, the underlying mechanisms remain unclear. Ferroptosis is a novel form of cell death characterized by iron-dependent lipid peroxidation and regulated by acyl coenzyme A synthase long-chain family member 4 (ACSL4). Yes-associated protein (YAP), a transcriptional co-activator in the Hippo pathway, promotes ferroptosis by modulating ACSL4 expression. Nevertheless, the involvement of YAP-ACSL4 axis-mediated ferroptosis in calcium oxalate crystal deposition-induced renal fibrosis and its molecular mechanisms have not been elucidated. In this study, we investigated ACSL4 expression and ferroptosis activation in the kidney tissues of patients with calcium oxalate stones and in mice using single-cell sequencing, transcriptome RNA sequencing, immunohistochemical analysis, and Western blot analysis. In vivo and in vitro experiments demonstrated that inhibiting ferroptosis or ACSL4 mitigated calcium oxalate crystal-induced renal fibrosis. Furthermore, YAP expression was elevated in the kidney tissues of patients with calcium oxalate stones and in calcium oxalate crystal-stimulated human renal tubular epithelial cell lines. Mechanistically, in calcium oxalate crystal-stimulated human renal tubular epithelial cell lines, activated YAP translocated to the nucleus and enhanced ACSL4 expression, consequently inducing cellular ferroptosis. Moreover, YAP silencing suppressed ferroptosis by downregulating ACSL4 expression, thereby attenuating calcium oxalate crystal-induced renal fibrosis. Conclusively, our findings suggest that YAP-ACSL4-mediated ferroptosis represents an important mechanism underlying the induction of renal fibrosis by calcium oxalate crystal deposition. Targeting the YAP-ACSL4 axis and ferroptosis may therefore hold promise as a potential therapeutic approach for preventing renal fibrosis in patients with kidney stones.

High driving pressure ventilation induces pulmonary hypertension in a rabbit model of acute lung injury

BACKGROUND

Mechanical ventilation may cause pulmonary hypertension in patients with acute lung injury (ALI), but the underlying mechanism remains elucidated.

METHODS

ALI was induced in rabbits by a two-hit injury, i.e., hydrochloric acid aspiration followed by mechanical ventilation for 1 h. Rabbits were then ventilated with driving pressure of 10, 15, 20, or 25 cmH2O for 7 h. Clinicopathological parameters were measured at baseline and different timepoints of ventilation. RNA sequencing was conducted to identify the differentially expressed genes in high driving pressure ventilated lung tissue.

RESULTS

The two-hit injury induced ALI in rabbits was evidenced by dramatically decreased PaO2/FiO2 in the ALI group compared with that in the control group (144.5 ± 23.8 mmHg vs. 391.6 ± 26.6 mmHg, P < 0.001). High driving pressure ventilation (20 and 25 cmH2O) significantly elevated the parameters of acute pulmonary hypertension at different timepoints compared with low driving pressure (10 and 15 cmH2O), along with significant increases in lung wet/dry ratios, total protein contents in bronchoalveolar lavage fluid, and lung injury scores. The high driving pressure groups showed more pronounced histopathological abnormalities in the lung compared with the low driving pressure groups, accompanied by significant increases in the cross-sectional areas of myocytes, right ventricular weight/body weight value, and Fulton's index. Furthermore, the expression of the genes related to ferroptosis induction was generally upregulated in high driving pressure groups compared with those in low driving pressure groups.

CONCLUSIONS

A rabbit model of ventilation-induced pulmonary hypertension in ALI was successfully established. Our results open a new research direction investigating the exact role of ferroptosis in ventilation-induced pulmonary hypertension in ALI.

The Emerging Roles of Ferroptosis in Pathophysiology and Treatment of Acute Lung Injury

Ferroptosis, a programmed cell death discovered in recent years, is an iron-dependent lipid peroxidation accumulation. Unlike other modes of cell death (autophagy, necroptosis, pyroptosis, cuproptosis, etc.), ferroptosis has unique morphological characteristics and plays an important role in a variety of diseases. In recent years, there has been great progress in the study of ferroptosis. Studies have found that ferroptosis is associated with acute lung injury (ALI), a condition with a high mortality rate and limited treatment options. This paper summarizes the mechanism of ferroptosis from the perspectives of iron metabolism, lipid metabolism, amino acid metabolism, and glutathione metabolism. It also discusses the research progress of ferroptosis in ALI in order to find new directions for the prevention and treatment of this condition.

Inhibition of ACSL4 ameliorates tubular ferroptotic cell death and protects against fibrotic kidney disease

Ferroptosis is a recently recognized form of regulated cell death, characterized by iron-dependent accumulation of lipid peroxidation. Ample evidence has depicted that ferroptosis plays an essential role in the cause or consequence of human diseases, including cancer, neurodegenerative disease and acute kidney injury. However, the exact role and underlying mechanism of ferroptosis in fibrotic kidney remain unknown. Acyl-CoA synthetase long-chain family member 4 (ACSL4) has been demonstrated as an essential component in ferroptosis execution by shaping lipid composition. In this study, we aim to discuss the potential role and underlying mechanism of ACSL4-mediated ferroptosis of tubular epithelial cells (TECs) during renal fibrosis. The unbiased gene expression studies showed that ACSL4 expression was tightly associated with decreased renal function and the progression of renal fibrosis. To explore the role of ACSL4 in fibrotic kidney, ACSL4 specific inhibitor rosiglitazone (ROSI) was used to disturb the high expression of ACSL4 in TECs induced by TGF-β, unilateral ureteral obstruction (UUO) and fatty acid (FA)-modeled mice in vivo, and ACSL4 siRNA was used to knockdown ACSL4 in TGF-β-induced HK2 cells in vitro. The results demonstrated that inhibition and knockdown of ACSL4 effectively attenuated the occurrence of ferroptosis in TECs and alleviated the interstitial fibrotic response. In addition, the expression of various profibrotic cytokines all decreased after ROSI-treated in vivo and in vitro. Further investigation showed that inhibition of ACSL4 obviously attenuates the progression of renal fibrosis by reducing the proferroptotic precursors arachidonic acid- and adrenic acid- containing phosphatidylethanolamine (AA-PE and AdA-PE). In conclusion, these results suggest ACSL4 is essential for tubular ferroptotic death during kidney fibrosis development and ACSL4 inhibition is a viable therapeutic approach to preventing fibrotic kidney diseases.

ACSL4 promotes ferroptosis and M1 macrophage polarization to regulate the tumorigenesis of nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a head and neck malignant tumor with a high incidence and recurrence rate. The crosstalk between ferroptosis and tumor-associated macrophages (TAMs) is thought to have major implications in interfering with cancers. We intended to explore the effect of acyl-CoA synthetase long-chain family member 4 (ACSL4) on the pathogenesis of NPC via ferroptosis and TAMs.

METHODS

Differential genes in NPC patients were analyzed using publicly available databases, and the ferroptosis-related gene ACSL4 was identified. Expression of ACSL4 in NPC cell lines and xenografted mice was examined. Colony formation, cell proliferation, migration, and invasion were assessed. The abundance of epithelial-mesenchymal transition (EMT) markers (E-cadherin, N-cadherin, and Vimentin) was confirmed. Lipid peroxidation levels and related markers were measured. Clophosome was administered to determine the role of TAMs in NPC mice.

RESULTS

Low levels of ACSL4 were observed in NPC patients and CNE-2 and 5-8F cells. Erastin (a ferroptosis inducer) and ACSL4 increased lipid peroxidation, decreased cell viability, colony formation, cell proliferation, migration and invasion, and inhibited EMT. Moreover, Erastin and ACSL4 promoted M2 to M1 macrophage polarization. The effects of erastin and ACSL4 were additive. Ferrostatin-1, an inhibitor of ferroptosis, exerted the opposite effect and reversed the beneficial effects of ACSL4 overexpression. In xenograft mice, ACSL4 and clophosome hindered the growth of NPC, and extra clophosome slightly enhanced the antitumor effect of ACSL4.

CONCLUSION

Our findings indicated that ACSL4 inhibited the pathogenesis of NPC, at least through crosstalk between ferroptosis and macrophages, providing potential direction for NPC therapy.

The emerging roles of MAPK-AMPK in ferroptosis regulatory network

Ferroptosis, a newform of programmed cell death, driven by peroxidative damages of polyunsaturated-fatty-acid-containing phospholipids in cellular membranes and is extremely dependent on iron ions, which is differs characteristics from traditional cell death has attracted greater attention. Based on the curiosity of this new form of regulated cell death, there has a tremendous progress in the field of mechanistic understanding of ferroptosis recent years. Ferroptosis is closely associated with the development of many diseases and involved in many diseases related signaling pathways. Not only a variety of oncoproteins and tumor suppressors can regulate ferroptosis, but multiple oncogenic signaling pathways can also have a regulatory effect on ferroptosis. Ferroptosis results in the accumulation of large amounts of lipid peroxides thus involving the onset of oxidative stress and energy stress responses. The MAPK pathway plays a critical role in oxidative stress and AMPK acts as a sensor of cellular energy and is involved in the regulation of the energy stress response. Moreover, activation of AMPK can induce the occurrence of autophagy-dependent ferroptosis and p53-activated ferroptosis. In recent years, there have been new advances in the study of molecular mechanisms related to the regulation of ferroptosis by both pathways. In this review, we will summarize the molecular mechanisms by which the MAPK-AMPK signaling pathway regulates ferroptosis. Meanwhile, we sorted out the mysterious relationship between MAPK and AMPK, described the crosstalk among ferroptosis and MAPK-AMPK signaling pathways, and summarized the relevant ferroptosis inducers targeting this regulatory network. This will provide a new field for future research on ferroptosis mechanisms and provide a new vision for cancer treatment strategies. Video Abstract.

FLRT2 suppresses bladder cancer progression through inducing ferroptosis

Bladder cancer is a common tumour worldwide and exhibits a poor prognosis. Fibronectin leucine rich transmembrane protein 2 (FLRT2) is associated with the regulation of multiple tumours; however, its function in human bladder cancer remain unclear. Herein, we found that FLRT2 level was reduced in human bladder cancer and that higher FLRT2 level predicted lower survival rate. FLRT2 overexpression inhibited, while FLRT2 silence facilitated tumour cell growth, migration and invasion. Mechanistic studies revealed that FLRT2 elevated acyl-CoA synthetase long-chain family member 4 (ACSL4) expression, increased lipid peroxidation and subsequently facilitated ferroptosis of human bladder cancer cells. In summary, we demonstrate that FLRT2 elevates ACSL4 expression to facilitate lipid peroxidation and subsequently triggers ferroptosis, thereby inhibiting the malignant phenotype of human bladder cancer cells. Overall, we identify FLRT2 as a tumour suppressor gene.

The Road from AKI to CKD: Molecular Mechanisms and Therapeutic Targets of Ferroptosis

Acute kidney injury (AKI) is a prevalent pathological condition that is characterized by a precipitous decline in renal function. In recent years, a growing body of studies have demonstrated that renal maladaptation following AKI results in chronic kidney disease (CKD). Therefore, targeting the transition of AKI to CKD displays excellent therapeutic potential. However, the mechanism of AKI to CKD is mediated by multifactor, and there is still a lack of effective treatments. Ferroptosis, a novel nonapoptotic form of cell death, is believed to have a role in the AKI to CKD progression. In this study, we retrospectively examined the history and characteristics of ferroptosis, summarized ferroptosis's research progress in AKI and CKD, and discussed how ferroptosis participates in regulating the pathological mechanism in the progression of AKI to CKD. Furthermore, we highlighted the limitations of present research and projected the future evolution of ferroptosis. We hope this work will provide clues for further studies of ferroptosis in AKI to CKD and contribute to the study of effective therapeutic targets to prevent the progression of kidney diseases.

Ferroptosis and multi-organ complications in COVID-19: mechanisms and potential therapies

COVID-19 is an infectious disease caused by SARS-CoV-2, with respiratory symptoms as primary manifestations. It can progress to severe illness, leading to respiratory failure and multiple organ dysfunction. Recovered patients may experience persistent neurological, respiratory, or cardiovascular symptoms. Mitigating the multi-organ complications of COVID-19 has been highlighted as a crucial part of fighting the epidemic. Ferroptosis is a type of cell death linked to altered iron metabolism, glutathione depletion, glutathione peroxidase 4 (GPX4) inactivation, and increased oxidative stress. Cell death can prevent virus replication, but uncontrolled cell death can also harm the body. COVID-19 patients with multi-organ complications often exhibit factors related to ferroptosis, suggesting a possible connection. Ferroptosis inhibitors can resist SARS-CoV-2 infection from damaging vital organs and potentially reduce COVID-19 complications. In this paper, we outline the molecular mechanisms of ferroptosis and, based on this, discuss multi-organ complications in COVID-19, then explore the potential of ferroptosis inhibitors as a supplementary intervention for COVID-19. This paper will provide a reference for the possible treatment of SARS-CoV-2 infected disease to reduce the severity of COVID-19 and its subsequent impact.

Ferroptosis as an emerging therapeutic target in liver diseases

Ferroptosis is an iron-dependently nonapoptotic cell death characterized by excessive accumulation of lipid peroxides and cellular iron metabolism disturbances. Impaired iron homeostasis and dysregulation of metabolic pathways are contributors to ferroptosis. As a major metabolic hub, the liver synthesizes and transports plasma proteins and endogenous fatty acids. Also, it acts as the primary location of iron storage for hepcidin generation and secretion. To date, although the intricate correlation between ferroptosis and liver disorders needs to be better defined, there is no doubt that ferroptosis participates in the pathogenesis of liver diseases. Accordingly, pharmacological induction and inhibition of ferroptosis show significant potential for the treatment of hepatic disorders involved in lipid peroxidation. In this review, we outline the prominent features, molecular mechanisms, and modulatory networks of ferroptosis and its physiopathologic functions in the progression of liver diseases. Further, this review summarizes the underlying mechanisms by which ferroptosis inducers and inhibitors ameliorate liver diseases. It is noteworthy that natural active ingredients show efficacy in preclinical liver disease models by regulating ferroptosis. Finally, we analyze crucial concepts and urgent issues concerning ferroptosis as a novel therapeutic target in the diagnosis and therapy of liver diseases.

Identification and validation of ferroptosis-related genes in lipopolysaccharide-induced acute lung injury

BACKGROUND

Emerging evidence reveals the important role of ferroptosis in the pathophysiological process of acute lung injury (ALI). We aimed to identify and validate the potential ferroptosis-related genes of ALI through bioinformatics analysis and experimental validation.

METHODS

Murine ALI model was established via intratracheal instillation with LPS and confirmed by H&E staining and transmission electronic microscopy (TEM). RNA sequencing (RNA-seq) was used to screen differentially expressed genes (DEGs) between control and ALI model mice. The potential differentially expressed ferroptosis-related genes of ALI were identified using the limma R package. Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, gene set enrichment analysis (GSEA), and protein-protein interactions (PPI) were applied for the differentially expressed ferroptosis-related genes. CIBERSORT tool was used to conduct immune cell infiltration analysis. Finally, protein expressions and RNA expression of ferroptosis DEGs were validated in vivo and in vitro by western blots and RT-qPCR.

RESULTS

Among 5009 DEGs, a total of 86 differentially expressed ferroptosis-related genes (45 up-regulated genes and 41 down-regulated genes) were identified in the lungs between control and ALI. GSEA analysis showed that the genes enriched were mainly involved in response to molecule of bacterial origin and fatty acid metabolic process. The GO and KEGG enrichment analysis indicated that the top 40 ferroptosis DEGs were mainly enriched in reactive oxygen species metabolic process, HIF-1signaling pathway, lipid and atherosclerosis, and ferroptosis. The PPI results and Spearman correlation analysis suggested that these ferroptosis-related genes interacted with each other. Immune infiltration analysis confirmed that ferroptosis DEGs were closely related to immune response. Consistent with the RNA-seq data, the western blot and RT-qPCR unveiled increased mRNA expressions of Cxcl2, Il-6, Il-1β, and Tnfα, and protein expressions of FTH1, TLR4 as well as decreased ACSL3 in LPS-induced ALI. In vitro, the upregulated mRNA levels of CXCL2, IL-6, SLC2A1, FTH1, TNFAIP3, and downregulated NQO1 and CAV1 in LPS-stimulated BEAS-2B and A549 cells were verified.

CONCLUSION

We identified 86 potential ferroptosis-related genes of LPS-induced ALI through RNA-seq. Several pivotal ferroptosis-related genes involved in lipid metabolism and iron metabolism were implicated in ALI. This study may be helpful to expand our understanding of ALI and provide some potential targets to counteract ferroptosis in ALI.

Zooming in and out of ferroptosis in human disease

Ferroptosis is defined as an iron-dependent regulated form of cell death driven by lipid peroxidation. In the past decade, it has been implicated in the pathogenesis of various diseases that together involve almost every organ of the body, including various cancers, neurodegenerative diseases, cardiovascular diseases, lung diseases, liver diseases, kidney diseases, endocrine metabolic diseases, iron-overload-related diseases, orthopedic diseases and autoimmune diseases. Understanding the underlying molecular mechanisms of ferroptosis and its regulatory pathways could provide additional strategies for the management of these disease conditions. Indeed, there are an expanding number of studies suggesting that ferroptosis serves as a bona-fide target for the prevention and treatment of these diseases in relevant pre-clinical models. In this review, we summarize the progress in the research into ferroptosis and its regulatory mechanisms in human disease, while providing evidence in support of ferroptosis as a target for the treatment of these diseases. We also discuss our perspectives on the future directions in the targeting of ferroptosis in human disease.

BMSC-Derived Exosomes Carrying lncRNA-ZFAS1 Alleviate Pulmonary Ischemia/Reperfusion Injury by UPF1-Mediated mRNA Decay of FOXD1

Bone marrow-derived mesenchymal stem cells (BMSCs) exert protective effects against pulmonary ischemia/reperfusion (I/R) injury; however, the potential mechanism involved in their protective ability remains unclear. Thus, this study aimed to explore the function and underlying mechanism of BMSC-derived exosomal lncRNA-ZFAS1 in pulmonary I/R injury. Pulmonary I/R injury models were established in mice and hypoxia/reoxygenation (H/R)-exposed primary mouse lung microvascular endothelial cells (LMECs). Exosomes were extracted from BMSCs. Target molecule expression was assessed by qRT-PCR and Western blotting. Pathological changes in the lungs, pulmonary edema, apoptosis, pro-inflammatory cytokine levels, SOD, MPO activities, and MDA level were measured. The proliferation, apoptosis, and migration of LMECs were detected by CCK-8, EdU staining, flow cytometry, and scratch assay. Dual-luciferase reporter assay, RNA pull-down, RIP, and ChIP assays were performed to validate the molecular interaction. In the mouse model of pulmonary I/R injury, BMSC-Exos treatment relieved lung pathological injury, reduced lung W/D weight ratio, and restrained apoptosis and inflammation, whereas exosomal ZFAS1 silencing abolished these beneficial effects. In addition, the proliferation, migration inhibition, apoptosis, and inflammation in H/R-exposed LMECs were repressed by BMSC-derived exosomal ZFAS1. Mechanistically, ZFAS1 contributed to FOXD1 mRNA decay via interaction with UPF1, thereby leading to Gal-3 inactivation. Furthermore, FOXD1 depletion strengthened the weakened protective effect of ZFAS1-silenced BMSC-Exos on pulmonary I/R injury. ZFAS1 delivered by BMSC-Exos results in FOXD1 mRNA decay and subsequent Gal-3 inactivation via direct interaction with UPF1, thereby attenuating pulmonary I/R injury.

The role of ferroptosis in metabolic diseases

The annual incidence of metabolic diseases such as diabetes, non-alcoholic fatty liver disease (NAFLD), osteoporosis, and atherosclerosis (AS) is increasing, resulting in a heavy burden on human health and the social economy. Ferroptosis is a novel form of programmed cell death driven by iron-dependent lipid peroxidation, which was discovered in recent years. Emerging evidence has suggested that ferroptosis contributes to the development of metabolic diseases. Here, we summarize the mechanisms and molecular signaling pathways involved in ferroptosis. Then we discuss the role of ferroptosis in metabolic diseases. Finally, we analyze the potential of targeting ferroptosis as a promising therapeutic approach for metabolic diseases.

Omega-3 polyunsaturated fatty acids alleviates lung injury mediated by post-hemorrhagic shock mesenteric lymph

Severe hemorrhage-induced acute lung injury (ALI) remains the major contributor to critical patient mortality and is associated with posthemorrhagic shock mesenteric lymph (PHSML) return. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) play overall protection on acute hemorrhage, but a reliable mechanism needs to be identified. The aims of this study were to investigate the role of ω-3 PUFAs in alleviating ALI and whether is related to the endotoxin contained in PHSML. Mesenteric lymph was harvested from rats subjected to hemorrhagic shock (hemorrhage-induced hypotension of 40 ± 2 mmHg for 90 min plus by resuscitation) or sham shock. The effect of ω-3 PUFAs on pulmonary function, water content, morphology, and LBP, CD14, TNF-α, and IL-6 levels were observed in rats subjected to hemorrhagic shock, while the effect of PHSML intravenous infusion on the beneficial effect of ω-3 PUFAs also was investigated. In addition, the effect of ω-3 PUFAs on the endotoxin contents in mesenteric lymph were detected. Hemorrhagic shock-induced ALI was characterized by increased functional residual capacity (FRC), lung resistance (RI), inspiratory capacity (IC), respiratory frequency, water contents and structural damage, along with increases in LBP, IL-6, and TNF-α. ω-3 PUFAs treatment reduced FRC, RI, IC, frequency, water contents, LBP, IL-6, TNF-α, and alleviated morphological damage. In contrast, PHSML infusion abolished the advantageous effects of ω-3 PUFAs on the above indices and CD14. Furthermore, the endotoxin level of PHSML was significantly enhanced, but declined following ω-3 PUFAs administration. These findings together suggested that treatment with ω-3 PUFAs ameliorates hemorrhagic shock-induced ALI, which is associated with reduced endotoxin contained in PHSML.

Ferroptosis Regulated by Hypoxia in Cells

Ferroptosis is an oxidative damage-related, iron-dependent regulated cell death with intracellular lipid peroxide accumulation, which is associated with many physiological and pathological processes. It exhibits unique features that are morphologically, biochemically, and immunologically distinct from other regulated cell death forms. Ferroptosis is regulated by iron metabolism, lipid metabolism, anti-oxidant defense systems, as well as various signal pathways. Hypoxia, which is found in a group of physiological and pathological conditions, can affect multiple cellular functions by activation of the hypoxia-inducible factor (HIF) signaling and other mechanisms. Emerging evidence demonstrated that hypoxia regulates ferroptosis in certain cell types and conditions. In this review, we summarize the basic mechanisms and regulations of ferroptosis and hypoxia, as well as the regulation of ferroptosis by hypoxia in physiological and pathological conditions, which may contribute to the numerous diseases therapies.

Exosomes secreted from cardiomyocytes suppress the sensitivity of tumor ferroptosis in ischemic heart failure

Heart failure (HF) patients in general have a higher risk of developing cancer. Several animal studies have indicated that cardiac remodeling and HF remarkably accelerate tumor progression, highlighting a cause-and-effect relationship between these two disease entities. Targeting ferroptosis, a prevailing form of non-apoptotic cell death, has been considered a promising therapeutic strategy for human cancers. Exosomes critically contribute to proximal and distant organ-organ communications and play crucial roles in regulating diseases in a paracrine manner. However, whether exosomes control the sensitivity of cancer to ferroptosis via regulating the cardiomyocyte-tumor cell crosstalk in ischemic HF has not yet been explored. Here, we demonstrate that myocardial infarction (MI) decreased the sensitivity of cancer cells to the canonical ferroptosis activator erastin or imidazole ketone erastin in a mouse model of xenograft tumor. Post-MI plasma exosomes potently blunted the sensitivity of tumor cells to ferroptosis inducers both in vitro in mouse Lewis lung carcinoma cell line LLC and osteosarcoma cell line K7M2 and in vivo with xenograft tumorigenesis model. The expression of miR-22-3p in cardiomyocytes and plasma-exosomes was significantly upregulated in the failing hearts of mice with chronic MI and of HF patients as well. Incubation of tumor cells with the exosomes isolated from post-MI mouse plasma or overexpression of miR-22-3p alone abrogated erastin-induced ferroptotic cell death in vitro. Cardiomyocyte-enriched miR-22-3p was packaged in exosomes and transferred into tumor cells. Inhibition of cardiomyocyte-specific miR-22-3p by AAV9 sponge increased the sensitivity of cancer cells to ferroptosis. ACSL4, a pro-ferroptotic gene, was experimentally established as a target of miR-22-3p in tumor cells. Taken together, our findings uncovered for the first time that MI suppresses erastin-induced ferroptosis through releasing miR-22-3p-enriched exosomes derived from cardiomyocytes. Therefore, targeting exosome-mediated cardiomyocyte/tumor pathological communication may offer a novel approach for the ferroptosis-based antitumor therapy.

Urolithin A (UA) attenuates ferroptosis in LPS-induced acute lung injury in mice by upregulating Keap1-Nrf2/HO-1 signaling pathway

Acute lung injury (ALI) is a life-threatening disease with high incidence and mortality rates. Urolithin A (UA) is a pomegranate intestinal flora metabolite with anti-inflammatory, antioxidant, and anti-aging properties. Ferroptosis is a critical factor in lipopolysaccharide (LPS)-induced acute lung injury (ALI). However, the link between UA and ferroptosis is unknown. The purpose of this research was to look into the role of UA in regulating LPS-induced ferroptosis in ALI. The current study used LPS to injure two models, one BEAS-2B cell injury model and one ALI mouse model. UA effectively alleviated LPS-induced ALI compared to the LPS group by lowering in vivo lung wet/dry weight ratio, reactive oxygen species, and malondialdehyde production, as well as superoxide dismutase, catalase, and glutathione depletion. Furthermore, by increasing GPX4 and SLC7A11 expression and decreasing Fe2+ levels, lung histopathological damage, inflammatory cytokine secretion, and ferroptosis levels can be significantly reduced. The Keap1-Nrf2/HO-1 pathway was upregulated by UA, which inhibited LPS-induced ALI and ferroptosis. ML385 inhibited UA’s protective effect against LPS-induced ALI. These findings suggested that UA could be a novel potential therapeutic target for ALI.

Fighting age-related orthopedic diseases: focusing on ferroptosis

Ferroptosis, a unique type of cell death, is characterized by iron-dependent accumulation and lipid peroxidation. It is closely related to multiple biological processes, including iron metabolism, polyunsaturated fatty acid metabolism, and the biosynthesis of compounds with antioxidant activities, including glutathione. In the past 10 years, increasing evidence has indicated a potentially strong relationship between ferroptosis and the onset and progression of age-related orthopedic diseases, such as osteoporosis and osteoarthritis. Therefore, in-depth knowledge of the regulatory mechanisms of ferroptosis in age-related orthopedic diseases may help improve disease treatment and prevention. This review provides an overview of recent research on ferroptosis and its influences on bone and cartilage homeostasis. It begins with a brief overview of systemic iron metabolism and ferroptosis, particularly the potential mechanisms of ferroptosis. It presents a discussion on the role of ferroptosis in age-related orthopedic diseases, including promotion of bone loss and cartilage degradation and the inhibition of osteogenesis. Finally, it focuses on the future of targeting ferroptosis to treat age-related orthopedic diseases with the intention of inspiring further clinical research and the development of therapeutic strategies.

GPX4: The hub of lipid oxidation, ferroptosis, disease and treatment

Glutathione peroxidase 4 (GPx4) moonlights as structural protein and antioxidase that powerfully inhibits lipid oxidation. In the past years, it is considered as a key regulator of ferroptosis, which takes role in the lipid and amine acid metabolism and influences the cell aging, oncogenesis, and cell death. More and more evidences show that targeting GPX4-induced ferroptosis is a promising strategy for disease therapy, especially cancer treatment. In view of these, we generalize the function of GPX4 and regulatory mechanism between GPX4 and ferroptosis, discuss its roles in the disease pathology, and focus on the recent advances of disease therapeutic potential.

Relationship Between ACSL4-Mediated Ferroptosis and Chronic Obstructive Pulmonary Disease

Purpose

Although cigarette smoke exposure is the major risk factor for chronic obstructive pulmonary disease (COPD), the mechanism is not completely understood. The aim of the present study was to investigate whether ACSL4-mediated ferroptosis in lung epithelial cells plays a part in the COPD development process and its association.

Patients and Methods

In this study, animal and cell models of COPD were modelled using cigarette smoke extracts (CSEs), and cell viability, lipid ROS, iron ion deposition, and ferroptosis-related markers were measured in lung tissue and lung epithelial cells following CSE exposure. Morphological changes in mitochondria were observed in lung tissue and epithelial cells of the lung by transmission electron microscope. The expression levels of ACSL4 mRNA and protein in lung tissue and epithelial cells were measured by real-time PCR and Western blotting. In addition, animal-interfering lentivirus and cell-interfering RNA against ACSL4 were constructed in this study, ferroptosis in lung tissue and lung epithelial cells after ACSL4 interference was detected, and ACSL4 mRNA and protein expression levels were detected.

Results

CSE induced ferroptosis in lung tissues and lung epithelial cells, and the expression levels of ACSL4 were elevated in CSE-treated lung tissues and lung epithelial cells. After ACSL4 interference, the expression of ACSL4 decreased, mitochondrial morphology was restored, and ferroptosis in lung tissues and lung epithelial cells was alleviated. Both respiratory frequency and enhanced pause of COPD mice models decreased after ACSL4 interference.

Conclusion

ACSL4-mediated ferroptosis in lung epithelial cells is associated with COPD and positively correlated with ferroptosis in epithelial cells.

Evaluation of genetic variants in ferroptosis-related genes and house dust mite-induced allergic rhinitis risk

BACKGROUND

Ferroptosis-related genes disrupt iron homeostasis and enhance lipid peroxidation to initiate respiratory system diseases. However, the association between genetic variants in the ferroptosis-related genes with house dust mite (HDM)-induced allergic rhinitis (AR) susceptibility remains unclear.

METHODS

A case-control study, involving 222 cases and 237 healthy controls from a Chinese population, was conducted to evaluate the relationship between single nucleotide polymorphisms (SNPs) in ferroptosis-related genes and HDM-induced AR risk. A gene-based analysis was performed by multi-marker analysis of genomic annotation (MAGMA) to identify candidate associated ferroptosis-related genes. A logistic regression model and joint analysis were used to assess the effect of SNPs on HDM-induced AR susceptibility.

RESULTS

Two independent SNPs (rs2305128 in ENPP2 and rs1868088 in EPAS1) were significantly associated with HDM-induced AR risk (OR = 1.82, 95% CI = 1.19-2.79, P = 5.98 × 10-3, PFDR = 4.88 × 10-2; OR = 2.14, 95% CI = 1.23-3.72, P = 6.95 × 10-3, PFDR = 4.87 × 10-2, respectively). Moreover, combined analysis of these two SNPs revealed that an increased risk of HDM-induced AR was positively associated with an increasing number of risk genotypes (Ptrend = 8.48 × 10-5). The stratification analysis showed that the cumulative effect of two SNPs on HDM-induced AR risk was more pronounced among patients presenting more serious symptoms and harboring one or two risk genotypes.

CONCLUSIONS

These findings suggest that the genetic variants in ferroptosis-related genes ENPP2 and EPAS1 may increase HDM-induced AR risk and serve as potential predictors of HDM-induced AR susceptibility.

Knockdown of SHP2 attenuated LPS-induced ferroptosis via downregulating ACSL4 expression in acute lung injury

BACKGROUND

Acute lung injury (ALI) is a complex disease with a high mortality. Src homology 2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2) is a protein tyrosine phosphatase that participates in pathogenesis of multiple diseases. Nevertheless, the role of SHP2 in ALI remains unknown.

METHODS

The in vivo and in vitro lipopolysaccharide (LPS)-induced ALI models were successfully established. The histopathological changes were evaluated by hematoxylin and eosin staining. The vascular permeability of lungs was assessed by Evans blue assay. The expression of ACSL4 and SHP2 was detected by western blot and qRT-PCR assay. The lactate dehydrogenase (LDH) activity, malondialdehyde (MDA), iron, and glutathione (GSH) levels were measured by commercial kits.

RESULTS

The SHP2 was upregulated in LPS-induced ALI mice and LPS-stimulated MLE-12 cells. In loss-of function experiment, the knockdown of SHP2 attenuated LPS-induced lung injury, microvessels damage, pulmonary edema, and increase of lung vascular permeability in vivo. Mechanically, shSHP2-rescued LPS induced increase in LDH activity, MDA, and iron levels, and decrease in GSH levels, as well as the accumulation of reactive oxygen species in vivo and in vitro, leading to an alleviation of LPS-induced ferroptosis. Notably, shSHP2 reduced the expression of Acyl-CoA synthetase long-chain 4 (ACSL4). In the rescued experiments, overexpression of ACSL4 abolished the shSHP2-induced reduction of LDH activity, MDA, and iron levels, and increase in GSH levels, thereby aggravating the LPS-induced ferroptosis.

CONCLUSION

These findings concluded that the knockdown of SHP2 attenuated LPS-induced ferroptosis via downregulation of ACSL4 expression in ALI, providing a novel sight for ALI treatment.

Multi-Target Neuroprotection of Thiazolidinediones on Alzheimer's Disease via Neuroinflammation and Ferroptosis

Alzheimer's disease (AD) is the main cause of dementia in older age. The prevalence of AD is growing worldwide, causing a tremendous burden to societies and families. Due to the complexity of its pathogenesis, the current treatment of AD is not satisfactory, and drugs acting on a single target may not prevent AD progression. This review summarizes the multi-target pharmacological effects of thiazolidinediones (TZDs) on AD. TZDs act as peroxisome proliferator-activated receptor gamma (PPARγ) agonists and long-chain acyl-CoA synthetase family member 4 (ACSL4) inhibitors. TZDs ameliorated neuroinflammation and ferroptosis in preclinical models of AD. Here, we discussed recent findings from clinical trials of pioglitazone in the treatment of AD, ischemic stroke, and atherosclerosis. We also dissected the major limitations in the clinical application of pioglitazone and explained the potential benefit of pioglitazone in AD. We recommend the use of pioglitazone to prevent cognitive decline and lower AD risk in a specific group of patients.

Effects of Ferroptosis on Cardiovascular Diseases

Ferroptosis is a novel form of programmed cell death characterized by the accumulation of iron-dependent lipid peroxides, which causes membrane injury. Under the catalysis of iron ions, cells deficient in glutathione peroxidase (GPX4) cannot preserve the balance in lipid oxidative metabolism, and the buildup of reactive oxygen species on the membrane lipids leads to cell death. An increasing body of evidence suggests that ferroptosis plays a significant role in the development and occurrence of cardiovascular diseases. In this paper, we mainly elaborated on the molecular mechanisms regulating ferroptosis and its impact on cardiovascular disease to lay the groundwork for future studies on the prophylaxis and treatment of this patient population.

The multifunctional roles of autophagy in the innate immune response: Implications for regulation of transplantation rejection

Organ transplantation is the main treatment for end-stage organ failure, which has rescued tens of thousands of lives. Immune rejection is the main factor affecting the survival of transplanted organs. How to suppress immune rejection is an important goal of transplantation research. A graft first triggers innate immune responses, leading to graft inflammation, tissue injury and cell death, followed by adaptive immune activation. At present, the importance of innate immunity in graft rejection is poorly understood. Autophagy, an evolutionarily conserved intracellular degradation system, is proven to be involved in regulating innate immune response following graft transplants. Moreover, there is evidence indicating that autophagy can regulate graft dysfunction. Although the specific mechanism by which autophagy affects graft rejection remains unclear, autophagy is involved in innate immune signal transduction, inflammatory response, and various forms of cell death after organ transplantation. This review summarizes how autophagy regulates these processes and proposes potential targets for alleviating immune rejection.

Role of ferroptosis inhibitors in the management of diabetes

Ferroptosis, the iron-dependent, lipid peroxide-mediated cell death, has garnered attention due to its critical involvement in crucial physiological and pathological cellular processes. Indeed, several studies have attributed its role in developing a range of disorders, including diabetes. As accumulating evidence further the understanding of ferroptotic mechanisms, the impact this specialized mode of cell death has on diabetic pathogenesis is still unclear. Several in vivo and in vitro studies have highlighted the association of ferroptosis with beta-cell death and insulin resistance, supported by observations of marked alterations in ferroptotic markers in experimental diabetes models. The constant improvement in understanding ferroptosis in diabetes has demonstrated it as a potential therapeutic target in diabetic management. In this regard, ferroptosis inhibitors promise to rescue pancreatic beta-cell function and alleviate diabetes and its complications. This review article elucidates the key ferroptotic pathways that mediate beta-cell death in diabetes, and its complications. In particular, we share our insight into the cross talk between ferroptosis and other hallmark pathogenic mediators such as oxidative and endoplasmic reticulum stress regulators relevant to diabetes progression. Further, we extensively summarize the recent developments on the role of ferroptosis inhibitors and their therapeutic action in alleviating diabetes and its complications.

Ferroptosis-A New Dawn in the Treatment of Organ Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) is a common pathological phenomenon that occurs in numerous organs and diseases. It generally results from secondary damage caused by the recovery of blood flow and reoxygenation, followed by ischemia of organ tissues, which is often accompanied by severe cellular damage and death. Currently, effective treatments for I/R injury (IRI) are limited. Ferroptosis, a new type of regulated cell death (RCD), is characterized by iron overload and iron-dependent lipid peroxidation. Mounting evidence has indicated a close relationship between ferroptosis and IRI. Ferroptosis plays a significantly detrimental role in the progression of IRI, and targeting ferroptosis may be a promising approach for treatment of IRI. Considering the substantial progress made in the study of ferroptosis in IRI, in this review, we summarize the pathological mechanisms and therapeutic targets of ferroptosis in IRI.

Targeting Ferroptosis as a Promising Therapeutic Strategy for Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) injury is a major challenge in perioperative medicine that contributes to pathological damage in various conditions, including ischemic stroke, myocardial infarction, acute lung injury, liver transplantation, acute kidney injury and hemorrhagic shock. I/R damage is often irreversible, and current treatments for I/R injury are limited. Ferroptosis, a type of regulated cell death characterized by the iron-dependent accumulation of lipid hydroperoxides, has been implicated in multiple diseases, including I/R injury. Emerging evidence suggests that ferroptosis can serve as a therapeutic target to alleviate I/R injury, and pharmacological strategies targeting ferroptosis have been developed in I/R models. Here, we systematically summarize recent advances in research on ferroptosis in I/R injury and provide a comprehensive analysis of ferroptosis-regulated genes investigated in the context of I/R, as well as the therapeutic applications of ferroptosis regulators, to provide insights into developing therapeutic strategies for this devastating disease.

ALDA-1 TREATMENT ALLEVIATES LUNG INJURY AFTER CARDIAC ARREST AND RESUSCITATION IN SWINE

ABSTRACT

Introduction: Alda-1, an aldehyde dehydrogenase 2 (ALDH2) activator, has been shown to protect the lung against a variety of diseases including regional ischemia-reperfusion injury, severe hemorrhagic shock, hyperoxia, and so on. The present study was designed to investigate the effectiveness of Alda-1 treatment in alleviating lung injury after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) in swine. Methods: A total of 24 swine were randomized into three groups: sham (n = 6), CA/CPR (n = 10), and CA/CPR + Alda-1 (n = 8). The swine model was established by 8 min of electrically induced and untreated CA, and then 8 min of manual CPR. A dose of 0.88 mg/kg of Alda-1 was intravenously injected at 5 min after CA/CPR. After CA/CPR, extravascular lung water index (ELWI), pulmonary vascular permeability index (PVPI), and oxygenation index (OI) were regularly evaluated for 4 h. At 24 h after resuscitation, lung ALDH2 activity was detected, and its injury score, apoptosis, and ferroptosis were measured. Results: After experiencing the same procedure of CA and CPR, five swine in the CA/CPR group and six swine in the CA/CPR + Alda-1 group restored spontaneous circulation. Subsequently, significantly increased ELWI and PVPI, and markedly decreased OI were observed in these two groups compared with the sham group. However, all of them were gradually improved and significantly better in the swine treated with the Alda-1 compared with the CA/CPR group. Tissue analysis indicated that lung ALDH2 activity was significantly decreased in those swine experiencing the CA/CPR procedure compared with the sham group; nevertheless, its activity was significantly greater in the CA/CPR + Alda-1 group than in the CA/CPR group. In addition, lung injury score, and its apoptosis and ferroptosis were significantly increased in the CA/CPR and CA/CPR + Alda-1 groups compared with the sham group. Likewise, Alda-1 treatment significantly decreased these pathological damages in lung tissue when compared with the CA/CPR group. Conclusions: Alda-1 treatment was effective to alleviate lung injury after CA/CPR in a swine model, in which the protective role was possibly related to the inhibition of cell apoptosis and ferroptosis. It might provide a novel therapeutic target and a feasible therapeutic drug for lung protection after CA/CPR.