The in vivo evidence for regulated necrosis

IRE1α determines ferroptosis sensitivity through regulation of glutathione synthesis

Cellular sensitivity to ferroptosis is primarily regulated by mechanisms mediating lipid hydroperoxide detoxification. We show that inositol-requiring enzyme 1 (IRE1α), an endoplasmic reticulum (ER) resident protein critical for the unfolded protein response (UPR), also determines cellular sensitivity to ferroptosis. Cancer and normal cells depleted of IRE1α gain resistance to ferroptosis, while enhanced IRE1α expression promotes sensitivity to ferroptosis. Mechanistically, IRE1α's endoribonuclease activity cleaves and down-regulates the mRNA of key glutathione biosynthesis regulators glutamate-cysteine ligase catalytic subunit (GCLC) and solute carrier family 7 member 11 (SLC7A11). This activity of IRE1α is independent of its role in regulating the UPR and is evolutionarily conserved. Genetic deficiency and pharmacological inhibition of IRE1α have similar effects in inhibiting ferroptosis and reducing renal ischemia-reperfusion injury in mice. Our findings reveal a previously unidentified role of IRE1α to regulate ferroptosis and suggests inhibition of IRE1α as a promising therapeutic strategy to mitigate ferroptosis-associated pathological conditions.

Fatty acid-binding protein 5 is a functional biomarker and indicator of ferroptosis in cerebral hypoxia

The progression of human degenerative and hypoxic/ischemic diseases is accompanied by widespread cell death. One death process linking iron-catalyzed reactive species with lipid peroxidation is ferroptosis, which shows hallmarks of both programmed and necrotic death in vitro. While evidence of ferroptosis in neurodegenerative disease is indicated by iron accumulation and involvement of lipids, a stable marker for ferroptosis has not been identified. Its prevalence is thus undetermined in human pathophysiology, impeding recognition of disease areas and clinical investigations with candidate drugs. Here, we identified ferroptosis marker antigens by analyzing surface protein dynamics and discovered a single protein, Fatty Acid-Binding Protein 5 (FABP5), which was stabilized at the cell surface and specifically elevated in ferroptotic cell death. Ectopic expression and lipidomics assays demonstrated that FABP5 drives redistribution of redox-sensitive lipids and ferroptosis sensitivity in a positive-feedback loop, indicating a role as a functional biomarker. Notably, immunodetection of FABP5 in mouse stroke penumbra and in hypoxic postmortem patients was distinctly associated with hypoxically damaged neurons. Retrospective cell death characterized here by the novel ferroptosis biomarker FABP5 thus provides first evidence for a long-hypothesized intrinsic ferroptosis in hypoxia and inaugurates a means for pathological detection of ferroptosis in tissue.

TCM targets ferroptosis: potential treatments for cancer

Ferroptosis is caused by the accumulation of cellular reactive oxygen species that exceed the antioxidant load that glutathione (GSH) and phospholipid hydroperoxidases with GSH-based substrates can carry When the antioxidant capacity of cells is reduced, lipid reactive oxygen species accumulate, which can cause oxidative death. Ferroptosis, an iron-dependent regulatory necrosis pathway, has emerged as a new modality of cell death that is strongly associated with cancer. Surgery, chemotherapy and radiotherapy are the main methods of cancer treatment. However, resistance to these mainstream anticancer drugs and strong toxic side effects have forced the development of alternative treatments with high efficiency and low toxicity. In recent years, an increasing number of studies have shown that traditional Chinese medicines (TCMs), especially herbs or herbal extracts, can inhibit tumor cell growth and metastasis by inducing ferroptosis, suggesting that they could be promising agents for cancer treatment. This article reviews the current research progress on the antitumor effects of TCMs through the induction of ferroptosis. The aim of these studies was to elucidate the potential mechanisms of targeting ferroptosis in cancer, and the findings could lead to new directions and reference values for developing better cancer treatment strategies.

Ferroptosis and oxidative stress in endometriosis: A systematic review of the literature

BACKGROUND

Endometriosis (EMT) a common gynecological condition in women, an inflammatory disease characterized by the presence of endometrial tissue on organs and tissues in the pelvis, and is mainly associated with chronic pelvic pain and infertility. As the etiology has not been fully elucidated, current treatment is limited to surgery, hormones and painkillers, with more side effects and difficulty in achieving long-term relief. Oxidative stress manifests itself as an overproduction of reactive oxygen species, which has an integral impact in the pathology of female reproductive disorders. In this review, we evaluate the mechanisms of iron overload-induced oxidative stress and ferroptosis in EMT and their pathophysiological implications.

METHODS

Because the etiology has not been fully elucidated, current treatments are limited to surgery, hormones, and painkillers, which have many side effects and are difficult to achieve long-term relief.

RESULTS

We interpreted that antioxidants as well as ferroptosis inducers show promising results in the treatment of EMT, but their application in this population needs to be further investigated.

CONCLUSION

In combination with the interpretation of previous studies, it was shown that iron overload is present in the peritoneal fluid, endometriotic lesions, peritoneum and macrophages in the abdominal cavity. However, the programmed cellular ferroptosis associated with iron overload is resisted by endometriotic foci, which is critical to the pathophysiology of EMT with local iron overload and inflammation.

Current updates on metabolites and its interlinked pathways as biomarkers for diabetic kidney disease: A systematic review

Diabetic kidney disease (DKD) is a major microvascular complication of diabetes mellitus (DM) that poses a serious risk as it can lead to end-stage renal disease (ESRD). DKD is linked to changes in the diversity, composition, and functionality of the microbiota present in the gastrointestinal tract. The interplay between the gut microbiota and the host organism is primarily facilitated by metabolites generated by microbial metabolic processes from both dietary substrates and endogenous host compounds. The production of numerous metabolites by the gut microbiota is a crucial factor in the pathogenesis of DKD. However, a comprehensive understanding of the precise mechanisms by which gut microbiota and its metabolites contribute to the onset and progression of DKD remains incomplete. This review will provide a summary of the current scenario of metabolites in DKD and the impact of these metabolites on DKD progression. We will discuss in detail the primary and gut-derived metabolites in DKD, and the mechanisms of the metabolites involved in DKD progression. Further, we will address the importance of metabolomics in helping identify potential DKD markers. Furthermore, the possible therapeutic interventions and research gaps will be highlighted.

Chemoproteomic Profiling of Erastin-Interacting Proteins

Ferroptosis is an iron-related cell death caused by irregular lipid peroxidation that has been implicated with a variety of disease. Erastin is a canonical ferroptosis inducer that is known to function by inhibiting system Xc- and cystine transport; however, the global interactome of erastin in cells remains unexplored. In this work, we employed a quantitative chemoproteomic approach to profile direct interacting proteins of erastin in living cells using a multifunctional photo-cross-linking probe. A number of novel erastin-interacting proteins were identified, including a serine hydrolase, ABHD6, whose overexpression showed a potentiating impact on ferroptosis. Further biochemical experiments revealed that erastin can allosterically activate ABHD6's activity to produce more arachidonic acids and elevate the level of lipid reactive oxygen species. Collectively, our work provided a global portrait of erastin-interacting proteins and discovered ABHD6 as a new ferroptosis regulator.

Modulating ferroptosis sensitivity: environmental and cellular targets within the tumor microenvironment

Ferroptosis, a novel form of cell death triggered by iron-dependent phospholipid peroxidation, presents significant therapeutic potential across diverse cancer types. Central to cellular metabolism, the metabolic pathways associated with ferroptosis are discernible in both cancerous and immune cells. This review begins by delving into the intricate reciprocal regulation of ferroptosis between cancer and immune cells. It subsequently details how factors within the tumor microenvironment (TME) such as nutrient scarcity, hypoxia, and cellular density modulate ferroptosis sensitivity. We conclude by offering a comprehensive examination of distinct immunophenotypes and environmental and metabolic targets geared towards enhancing ferroptosis responsiveness within the TME. In sum, tailoring precise ferroptosis interventions and combination strategies to suit the unique TME of specific cancers may herald improved patient outcomes.

Carnosine attenuates renal ischemia-reperfusion injury by inhibiting GPX4-mediated ferroptosis

Increasing evidence and our preliminary work have revealed the significant role of ferroptosis in acute kidney injury (AKI) induced by ischemia/reperfusion (IR). Carnosine (Car), a dipeptide consisting of β-alanine and L-histidine, has been shown to ameliorate HG-induced tubular epithelial cells inflammation. Whether Car exerts protective effects on AKI, and its molecular mechanism have not been clarified. Our in vivo and in vitro IR-AKI mouse models demonstrated that Car alleviates kidney injury, inflammation and ferroptosis. In hypoxia/reoxygenation (HR) induced human renal tubular epithelial cells (HK2), Car treatment reduced lipid peroxidation and iron accumulation, suppressed oxidative stress, and inhibited ferroptosis. Through cellular thermal shift assay (CETSA) and molecular docking, we identified GPX4 as a potential target that binds with Car. Further study showed that overexpressed GPX4 had a comparable protective effect on HK2 cells under HR conditions, similar to Car. Additionally, our findings demonstrated that Car exhibited similar anti-ferroptosis effects in both folic acid (FA)-induced AKI mouse models and Erastin induced HK2 cells. In conclusion, our results highlight that Car alleviate renal IR injury by inhibiting GPX4-mediated ferroptosis. Car shows promise as a potential therapeutic drug for IR-AKI and other diseases associated with ferroptosis.

Ferrostatin-1 post-treatment attenuates acute kidney injury in mice by inhibiting ferritin production and regulating iron uptake-related proteins

Background

Acute kidney injury (AKI) is a common and serious medical condition with high morbidity and mortality. Recent research has highlighted ferroptosis, a novel form of programmed cell death, as a potential therapeutic target in mitigating renal tubular injury in AKI. Ferrostatin-1, a specific ferroptosis inhibitor, has been demonstrated to prevent renal injury through ferroptosis inhibition.

Methods

Utilizing a murine AKI model, we investigated the effects of Ferrostatin-1 by administering it post-injury. Through high-throughput sequencing and pathological analysis, we focused on the critical role of ferroptosis-related pathways in the treatment.

Results

Ferrostatin-1 post-conditioning effectively mitigated oxidative damage and reduced iron content associated with AKI. Additionally, critical ferroptosis-related proteins, such as GPX4, SLC7A11, NRF2, and FTH1, exhibited increased expression levels. In vitro, Ferrostatin-1 treatment of HK-2 cells significantly diminished lipid peroxidation and iron accumulation. Furthermore, Ferrostatin-1 was found to downregulate the PI3K signalling pathway.

Conclusion

Ferrostatin-1 acted as a potential ferroptosis inhibitor with the capacity to enhance antioxidant defences. This study suggests that Ferrostatin-1 could serve as a promising novel strategy for improving the treatment of AKI and promoting recovery from the condition.

Non-Vesicular Release of Alarmin Prothymosin α Complex Associated with Annexin-2 Flop-Out

Nuclear protein prothymosin α (ProTα) is a unique member of damage-associated molecular patterns (DAMPs)/alarmins. ProTα prevents neuronal necrosis by causing a cell death mode switch in serum-starving or ischemic/reperfusion models in vitro and in vivo. Underlying receptor mechanisms include Toll-like receptor 4 (TLR4) and G_i-coupled receptor. Recent studies have revealed that the mode of the fatal stress-induced extracellular release of nuclear ProTα from cortical neurons in primary cultures, astrocytes and C6 glioma cells has two steps: ATP loss-induced nuclear release and the Ca²⁺-mediated formation of a multiple protein complex and its extracellular release. Under the serum-starving condition, ProTα is diffused from the nucleus throughout the cell due to the ATP loss-induced impairment of importin α-mediated nuclear transport. Subsequent mechanisms are all Ca²⁺-dependent. They include the formation of a protein complex with ProTα, S100A13, p40 Syt-1 and Annexin A2 (ANXA2); the fusion of the protein complex to the plasma membrane via p40 Syt-1-Stx-1 interaction; and TMEM16F scramblase-mediated ANXA2 flop-out. Subsequently, the protein complex is extracellularly released, leaving ANXA2 on the outer cell surface. The ANXA2 is then flipped in by a force of ATP8A2 activity, and the non-vesicular release of protein complex is repeated. Thus, the ANXA2 flop-out could play key roles in a new type of non-vesicular and non-classical release for DAMPs/alarmins, which is distinct from the modes conducted via gasdermin D or mixed-lineage kinase domain-like pseudokinase pores.

Current Understanding of and Future Directions for Endometriosis-Related Infertility Research with a Focus on Ferroptosis

BACKGROUND

To date, the development of therapy for endometriosis and disease-related infertility remains a major challenge. Iron overload caused by periodic bleeding is a hallmark of endometriosis. Ferroptosis is an iron- and lipid-reactive oxygen species-dependent type of programmed cell death that is distinct from apoptosis, necrosis, and autophagy. This review summarizes the current understanding of and future directions for the research and treatment of endometriosis and disease-related infertility, with the main focus on the molecular basis of ferroptosis in endometriotic and granulosa cells.

METHODS

Papers published between 2000 and 2022 in the PubMed and Google Scholar databases were included in this review.

RESULTS

Emerging evidence suggests that ferroptosis is closely linked to the pathophysiology of endometriosis. Endometriotic cells are characterized by ferroptosis resistance, whereas granulosa cells remain highly susceptible to ferroptosis, suggesting that the regulation of ferroptosis is utilized as an interventional target for research into the treatment of endometriosis and disease-related infertility. New therapeutic strategies are urgently needed to efficiently kill endometriotic cells while protecting granulosa cells.

CONCLUSIONS

An analysis of the ferroptosis pathway in in vitro, in vivo, and animal research enhances our understanding of the pathogenesis of this disease. Here, we discuss the role of ferroptosis modulators as a research approach and potential novel treatment for endometriosis and disease-related infertility.

Berberine modulates gut microbiota to attenuate cerebral ferroptosis induced by ischemia-reperfusion in mice

Ferroptosis was reported to be involved in cerebral ischemia-reperfusion injury (CIRI), on which the effects of berberine (BBR) remain unclear. Moreover, based on the critical role of gut microbiota in pleiotropic actions of BBR, we hypothesized that BBR can suppress CIRI-induced ferroptosis by modulating the gut microbiota. In this study, the results showed that BBR obviously attenuated the behavioral deficits of CIRI mice, accompanied with the improved survival rate and neuron damages, as phenocopied by dirty cage experiment. The typical morphological changes in ferroptotic cells and biomarkers of ferroptosis were attenuated in BBR- and its fecal microbiota-treated mice, accompanied by reduced malondialdehyde and reactive oxygen species, and the increased glutathione (GSH). BBR was found to alter the gut microbiota of CIRI mice with decreased abundance of Muribaculaceae, Erysipelotrichaceae, Helicobacteraceae, Streptococcaceae and Tannerellaceae, but elevated Bacteroidaceae and Enterobacteriaceae. KEGG analysis based on the 16S rRNA results indicated that multiple metabolic pathways including ferroptosis and GSH metabolism, were altered by BBR. Oppositely, the antibiotics administration counteracted the protective properties of BBR. Summarily, this study revealed the therapeutic potential of BBR on CIRI via inhibiting neuronal ferroptosis, in which upregulated glutathione peroxidase 1 (GPX1) was possibly involved. Moreover, the BBR-modulated gut microbiota was shown to play the critical role in the underlying mechanism.

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.

Epigenetic Regulation of Ferroptosis in Central Nervous System Diseases

Ferroptosis, a newly identified form of cell death, is characterized by iron overload and accumulation of lipid reactive oxygen species. Inactivation of pathways, such as glutathione/glutathione peroxidase 4, NAD(P)H/ferroptosis suppressor protein 1/ubiquinone, dihydroorotate dehydrogenase/ubiquinol, or guanosine triphosphate cyclohydrolase-1/6(R)-L-erythro-5,6,7,8-tetrahydrobiopterin pathways, have been found to induce ferroptosis. The accumulating data suggest that epigenetic regulation can determine cell sensitivity to ferroptosis at both the transcriptional and translational levels. While many of the effectors that regulate ferroptosis have been mapped, epigenetic regulation in ferroptosis is not yet fully understood. Neuronal ferroptosis is a driver in several central nervous system (CNS) diseases, such as stroke, Parkinson's disease, traumatic brain injury, and spinal cord injury, and thus, research on how to inhibit neuronal ferroptosis is required to develop novel therapies for these diseases. In this review, we have summarized epigenetic regulation of ferroptosis in these CNS diseases, focusing in particular on DNA methylation, non-coding RNA regulation, and histone modification. Understanding epigenetic regulation in ferroptosis will hasten the development of promising therapeutic strategies in CNS diseases associated with ferroptosis.

Pre-Treatment of Transplant Donors with Hydrogen Sulfide to Protect against Warm and Cold Ischemia-Reperfusion Injury in Kidney and Other Transplantable Solid Organs

Ischemia-reperfusion injury (IRI), a pathological condition resulting from prolonged cessation and subsequent restoration of blood flow to a tissue, is an inevitable consequence of solid organ transplantation. Current organ preservation strategies, such as static cold storage (SCS), are aimed at reducing IRI. However, prolonged SCS exacerbates IRI. Recent research has examined pre-treatment approaches to more effectively attenuate IRI. Hydrogen sulfide (H₂S), the third established member of a family of gaseous signaling molecules, has been shown to target the pathophysiology of IRI and thus appears to be a viable candidate that can overcome the transplant surgeon's enemy. This review discusses pre-treatment of renal grafts and other transplantable organs with H₂S to mitigate transplantation-induced IRI in animal models of transplantation. In addition, ethical principles of pre-treatment and potential applications of H₂S pre-treatment in the prevention of other IRI-associated conditions are discussed.

Bibliometric analysis of ferroptosis in acute kidney injury from 2014 to 2022

INTRODUCTION

Acute kidney injury (AKI) is a global disease with high morbidity and mortality. At present, the treatment of AKI still lacks targeted measures. Ferroptosis, a form of regulated cell death, plays an essential role in the initiation and progression of AKI. Current evidence proves that targeting ferroptosis is supposed to be a novel potential strategy to cure AKI. In this study, we aim to use bibliometric analysis to identify research trends and hotspots in the field of "ferroptosis in AKI".

METHODS

We chose the Science Citation Index Expanded (SCI-EXPANDED) index of the Web of Science Core Collection (WoSCC) as the source database for data retrieval. Data were retrieved from the WoSCC on May 24, 2022. Full records and cited references of all the documents in WoSCC were collected. The R software and the Online Analysis Platform of Literature Metrology were used for data analysis and visual analysis.

RESULTS

There were 120 documents on "ferroptosis in AKI" in the WOSCC from 2014 to 2022 (May 24, 2022). There was a clear upward trend each year in the number of documents published. According to WoS report, China, the United States, and Germany were the top three countries involved in this research area, the majority of publications were included in the subject area "Cell Biology". Technical University of Dresden contributed the most publications, followed by Central South University and University of Pittsburgh. The Journal of Cell Death and Disease had the highest H-index and contributed the most publications. Linkermann A authored 16 articles and had the highest H-index. Multifactorial analysis of the keywords show that the research field is divided into two clusters. The most contributing publications and the most cited publications were also determined by factorial analysis.

CONCLUSION

This bibliometric analysis provides a comprehensive analysis of research trends and hot spots on the topic of "ferroptosis in AKI". The study of ferroptosis-related AKI research remains in its early stages. There will be a dramatically increasing number of publications on this field. Further research should focus on exploring the mechanisms of crosstalk between ferroptosis and other programmed cell deaths, and improves clinical applications and therapeutic effects against AKI.

Generation of transgenic mice expressing a FRET biosensor, SMART, that responds to necroptosis

Necroptosis is a regulated form of cell death involved in various pathological conditions, including ischemic reperfusion injuries, virus infections, and drug-induced tissue injuries. However, it is not fully understood when and where necroptosis occurs in vivo. We previously generated a Forster resonance energy transfer (FRET) biosensor, termed SMART (the sensor for MLKL activation by RIPK3 based on FRET), which monitors conformational changes of MLKL along with progression of necroptosis in human and murine cell lines in vitro. Here, we generate transgenic (Tg) mice that express the SMART biosensor in various tissues. The FRET ratio is increased in necroptosis, but not apoptosis or pyroptosis, in primary cells. Moreover, the FRET signals are elevated in renal tubular cells of cisplatin-treated SMART Tg mice compared to untreated SMART Tg mice. Together, SMART Tg mice may provide a valuable tool for monitoring necroptosis in different types of cells in vitro and in vivo.

Temporal radiographic and histological study of necrosis development in a mouse glioblastoma model

Tumor necrosis is a poor prognostic marker in glioblastoma (GBM) and a variety of other solid cancers. Accumulating evidence supports that necrosis could facilitate tumor progression and resistance to therapeutics. GBM necrosis is typically first detected by magnetic resonance imaging (MRI), after prominent necrosis has already formed. Therefore, radiological appearances of early necrosis formation and the temporal-spatial development of necrosis alongside tumor progression remain poorly understood. This knowledge gap leads to a lack of reliable radiographic diagnostic/prognostic markers in early GBM progression to detect necrosis. Recently, we reported an orthotopic xenograft GBM murine model driven by hyperactivation of the Hippo pathway transcriptional coactivator with PDZ-binding motif (TAZ) which recapitulates the extent of GBM necrosis seen among patients. In this study, we utilized this model to perform a temporal radiographic and histological study of necrosis development. We observed tumor tissue actively undergoing necrosis first appears more brightly enhancing in the early stages of progression in comparison to the rest of the tumor tissue. Later stages of tumor progression lead to loss of enhancement and unenhancing signals in the necrotic central portion of tumors on T1-weighted post-contrast MRI. This central unenhancing portion coincides with the radiographic and clinical definition of necrosis among GBM patients. Moreover, as necrosis evolves, two relatively more contrast-enhancing rims are observed in relationship to the solid enhancing tumor surrounding the central necrosis in the later stages. The outer more prominently enhancing rim at the tumor border probably represents the infiltrating tumor edge, and the inner enhancing rim at the peri-necrotic region may represent locally infiltrating immune cells. The associated inflammation at the peri-necrotic region was further confirmed by immunohistochemical study of the temporal development of tumor necrosis. Neutrophils appear to be the predominant immune cell population in this region as necrosis evolves. This study shows central, brightly enhancing areas associated with inflammation in the tumor microenvironment may represent an early indication of necrosis development in GBM.

C5b-9 mediates ferroptosis of tubular epithelial cells in trichloroethylene-sensitization mice

Occupational medicamentose-like dermatitis due to trichloroethylene (OMDT) is a key but unresolved question. OMDT patients often present multiple organ damage, including kidney damage. However, the underlying mechanism remains unknown. The purpose of our study was to explore the effect of tubule-specific C5b-9 deposition induced by TCE sensitization on renal tubular ferroptosis and its mechanism. By analyzing pathological changes of TCE-sensitization-mice kidney, we observed a significant renal tubular ferroptosis, which was alleviated by CD59, a C5b-9 inhibitory protein. Moreover, this phenomenon was also replicated in a C5b-9-attacked HK-2 cell model. Further experiments identified that C5b-9 induced cytosolic Ca2+ overload in renal tubular epithelia cells from TCE-sensitization-mice and HK-2 cells. Furthermore, in vitro experiments showed that BAPTA-AM, an intracellular Ca2+ chelator, could rescued ferroptosis induced by C5b-9 in HK-2 cells. Taken together, TCE sensitization induced renal tubular ferroptosis is mediated by C5b-9 and cytosolic Ca2+ overload may play a key role.

Galectin-3 critically mediates the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting pyroptosis but not necroptosis signalling

We previously documented that M2-like macrophages exert a hepatoprotective effect in acute-on-chronic liver failure (ACLF) by inhibiting necroptosis signalling. Nevertheless, the molecular mechanism behind this hepatoprotection still needs to be further dissected. Galectin-3 (GAL3) has been reported to be critically involved in the pathogenesis of multiple liver diseases, whereas the potential role of GAL3 in ACLF remains to be explored. Herein, we hypothesised that GAL3 plays a pivotal role in the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting necroptosis. To test this hypothesis, we first assessed the expression of GAL3 in control and fibrotic mice with or without acute insult. Second, loss- and gain-of-function experiments of GAL3 were performed. Third, the correlation between GAL3 and M2-like macrophage activation was analysed, and the potential role of GAL3 in M2-like macrophage-conferred hepatoprotection was confirmed. Finally, the molecular mechanism underlying GAL3-mediated hepatoprotection was dissected. GAL3 was found to be obviously upregulated in fibrotic mice with or without acute insult but not in acutely injured mice. Depletion of GAL3 aggravated hepatic damage in fibrotic mice upon insult. Conversely, adoptive transfer of GAL3 provided normal mice enhanced resistance against acute insult. The expression of GAL3 is closely correlated with M2-like macrophage activation. Through adoptive transfer and depletion experiments, M2-like macrophages were verified to act as a major source of GAL3. Importantly, GAL3 was confirmed to hold a pivotal place in the hepatoprotection conferred by M2-like macrophages through loss- and gain-of-function experiments. Unexpectedly, the depletion and adoptive transfer of GAL3 resulted in significant differences in the expression levels of pyroptosis but not necroptosis signalling molecules. Taken together, GAL3 plays a pivotal role in the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting pyroptosis but not necroptosis signalling. Our findings provide novel insights into the pathogenesis and therapy of ACLF.

PPARα alleviates iron overload-induced ferroptosis in mouse liver

Ferroptosis is an iron‐dependent form of non‐apoptotic cell death implicated in liver, brain, kidney, and heart pathology. How ferroptosis is regulated remains poorly understood. Here, we show that PPARα suppresses ferroptosis by promoting the expression of glutathione peroxidase 4 (Gpx4) and by inhibiting the expression of the plasma iron carrier TRF. PPARα directly induces Gpx4 expression by binding to a PPRE element within intron 3. PPARα knockout mice develop more severe iron accumulation and ferroptosis in the liver when fed a high‐iron diet than wild‐type mice. Ferrous iron (Fe²⁺) triggers ferroptosis via Fenton reactions and ROS accumulation. We further find that a rhodamine‐based "turn‐on" fluorescent probe(probe1) is suitable for the in vivo detection of Fe²⁺. Probe1 displays high selectivity towards Fe²⁺, and exhibits a stable response for Fe²⁺ with a concentration of 20 μM in tissue. Our data thus show that PPARα activation alleviates iron overload‐induced ferroptosis in mouse livers through Gpx4 and TRF, suggesting that PPARα may be a promising therapeutic target for drug discovery in ferroptosis‐related tissue injuries. Moreover, we identified a fluorescent probe that specifically labels ferrous ions and can be used to monitor Fe²⁺in vivo.

The Role of Ferroptosis in Acute Kidney Injury

Ferroptosis is a novel cell death method discovered in recent years. It is usually accompanied by massive accumulations of iron and lipid peroxidation during cell death. Recent studies have shown that ferroptosis is closely associated with the pathophysiological processes of many diseases, such as tumors, neurological diseases, localized ischemia-reperfusion injury, kidney injury, and hematological diseases. How to intervene in the incidence and development of associated diseases by regulating the ferroptosis of cells has become a hot topic of research. This article provides a review of the role of ferroptosis in the pathogenesis and potential treatment of acute kidney injury.

Roles and Mechanisms of Regulated Necrosis in Corneal Diseases: Progress and Perspectives

Regulated necrosis is defined as cell death characterized by loss of the cell membrane integrity and release of the cytoplasmic content. It contributes to the development and progression of some diseases, including ischemic stroke injury, liver diseases, hypertension, and cancer. Various forms of regulated necrosis, particularly pyroptosis, necroptosis, and ferroptosis, have been implicated in the pathogenesis of corneal disease. Regulated necrosis of corneal cells enhances inflammatory reactions in the adjacent corneal tissues, leading to recurrence and aggravation of corneal disease. In this review, we summarize the molecular mechanisms of pyroptosis, necroptosis, and ferroptosis in corneal diseases and discuss the roles of regulated necrosis in inflammation regulation, tissue repair, and corneal disease outcomes.

Potential Key Markers for Predicting the Prognosis of Gastric Adenocarcinoma Based on the Expression of Ferroptosis-Related lncRNA

Background. Gastric cancer is one of the most common malignant tumors, and it ranks third in global cancer-related mortality. This research was aimed at identifying new targeted treatments for gastric adenocarcinoma by constructing a ferroptosis-related lncRNA prognostic feature model. Methods. The gene expression profile and clinical data of gastric adenocarcinoma patients were downloaded from TCGA database. FerrDb database was used to determine the expression of iron death-related genes. We used R software to clean the TCAG gastric adenocarcinoma gene expression cohort and screen iron death-related differential genes and lncRNAs. The potential prognostic markers and immune infiltration characteristics were determined by constructing prognostic model and multivariate validation of lncRNA related to ferroptosis prognosis. Finally, the characteristics of immune infiltration were determined by immune correlation analysis. Results. We identified 26 ferroptosis-related lncRNAs with independent prognostic value. The Kaplan-Meier analysis identified high-risk lncRNAs associated with poor prognosis of STAD. The risk scoring model constructed by AC115619.1, AC005165.1, LINC01614, and AC002451.1 was better than traditional clinicopathological features. The 1-, 3-, and 5-year survival rates of STAD patients were predicted by the nomogram. GSEA reveals the oxidative respiration and tumor-related pathways in different risk groups. Immune analysis found significant differences in the expression of immune checkpoint-related genes TNFSF9, TNFSF4, and PDCD1LG2 between the two groups of patients. Meanwhile, there were significant differences in APC co stimulation, CCR, and checkpoint between the two groups. Conclusion. Based on the prognostic characteristics of ferroptosis-related lncRNAs, we identified the potential ferroptosis-related lncRNAs and immune infiltration characteristics in gastric adenocarcinoma, which will help provide new targeted treatments for gastric adenocarcinoma.

Regulation of the release of damage-associated molecular patterns from necroptotic cells

Damage-associated molecular patterns (DAMPs) are molecules within living cells that are released when cell membranes are ruptured. Although DAMPs have physiological functions inside the cell, once DAMPs are released extracellularly, they elicit various biological responses, including inflammation, proliferation, tissue damage, and tissue repair, in a context-dependent manner. In past decades, it was assumed that the release of DAMPs was induced by a membrane rupture, caused by passive ATP depletion, or by chemical or mechanical damage to the membrane. However, that concept has been challenged by recent advancements in understanding the regulation of cell death. Necroptosis is a form of regulated cell death, where cells show necrotic morphology. Necroptosis is triggered by death receptors, toll-like receptors, and some viral infections. The membrane rupture is executed by the mixed lineage-like kinase domain-like pseudokinase (MLKL), which forms oligomers that translocate to the plasma membrane during necroptosis. Although the causal relationship between MLKL function and membrane rupture has been extensively investigated, the detailed molecular mechanisms by which oligomerized MLKL induces membrane rupture are not fully understood. This review summarizes recent advances in understanding how MLKL regulates DAMP release and new technologies for visualizing DAMP release at single-cell resolution.

Upregulated Fibulin-1 Increased Endometrial Stromal Cell Viability and Migration by Repressing EFEMP1-Dependent Ferroptosis in Endometriosis

Endometriosis (EMS) is a prevalent disease in women characterized by the presence of endometrial stroma and glands outside the uterus. Recent studies have showed that EMS is correlated with the resistance of endometrial stromal cells (ESCs) to ferroptosis, an iron-dependent nonapoptotic cell death. Fibulin-1 (FBLN1) is a newly identified target regulated by progesterone in the process of ESC decidualization. However, the role of FBLN1 in regulating ESC ferroptosis and EMS remains unclear. In the present study, the gene expression profiles of GSE58178, GSE23339, and GSE25628 were downloaded from the Gene Expression Omnibus (GEO) database, and the commonly differential genes were identified using Venn diagram analysis. The role of FBLN1 in ESC viability and migration was evaluated using Cell Counting Kit-8, transwell, and western blot analysis. We found that the FBLN1 expression was increased significantly in eutopic and ectopic endometrial tissues of patients with EMS compared with normal endometrium. FBLN1 overexpression in normal ESCs (NESCs) promoted cell viability and migration, whereas FBLN1 inhibition in ectopic ESCs (EESCs) decreased cell viability and migration. Furthermore, FBLN1 inhibition facilitated EESC death by triggering ferroptosis, as evidenced by increased Fe2+, lipid ROS, and malondialdehyde (MDA) level and decreased glutathione peroxidase 4 (GPX4) expression and glutathione (GSH) level. Mechanistically, FBLN1 interacted with EGF-containing fibulin-like extracellular matrix protein 1 (EFEMP1) and increased the protein stability of EFEMP1. More importantly, EFEMP1 silencing repressed the effect of FBLN1 on regulating EESC ferroptosis, death, and migration. Taken together, these results verify the role of the FBLN1/EFEMP1/ferroptosis pathway in the pathogenesis of EMS, and silencing of FBLN1/EFEMP1 might be an effective approach to treat EMS.

Abnormal Iron and Lipid Metabolism Mediated Ferroptosis in Kidney Diseases and Its Therapeutic Potential

Ferroptosis is a newly identified form of regulated cell death driven by iron-dependent phospholipid peroxidation and oxidative stress. Ferroptosis has distinct biological and morphology characteristics, such as shrunken mitochondria when compared to other known regulated cell deaths. The regulation of ferroptosis includes different molecular mechanisms and multiple cellular metabolic pathways, including glutathione/glutathione peroxidase 4(GPX4) signaling pathways, which are involved in the amino acid metabolism and the activation of GPX4; iron metabolic signaling pathways, which are involved in the regulation of iron import/export and the storage/release of intracellular iron through iron-regulatory proteins (IRPs), and lipid metabolic signaling pathways, which are involved in the metabolism of unsaturated fatty acids in cell membranes. Ferroptosis plays an essential role in the pathology of various kidneys diseases, including acute kidney injury (AKI), chronic kidney disease (CKD), autosomal dominant polycystic kidney disease (ADPKD), and renal cell carcinoma (RCC). Targeting ferroptosis with its inducers/initiators and inhibitors can modulate the progression of kidney diseases in animal models. In this review, we discuss the characteristics of ferroptosis and the ferroptosis-based mechanisms, highlighting the potential role of the main ferroptosis-associated metabolic pathways in the treatment and prevention of various kidney diseases.

Role of Ferroptosis in Non-Alcoholic Fatty Liver Disease and Its Implications for Therapeutic Strategies

Non-alcoholic fatty liver disease (NAFLD) has become the chronic liver disease with the highest incidence throughout the world, but its pathogenesis has not been fully elucidated. Ferroptosis is a novel form of programmed cell death caused by iron-dependent lipid peroxidation. Abnormal iron metabolism, lipid peroxidation, and accumulation of polyunsaturated fatty acid phospholipids (PUFA-PLs) can all trigger ferroptosis. Emerging evidence indicates that ferroptosis plays a critical role in the pathological progression of NAFLD. Because the liver is the main organ for iron storage and lipid metabolism, ferroptosis is an ideal target for liver diseases. Inhibiting ferroptosis may become a new therapeutic strategy for the treatment of NAFLD. In this article, we describe the role of ferroptosis in the progression of NAFLD and its related mechanisms. This review will highlight further directions for the treatment of NAFLD and the selection of corresponding drugs that target ferroptosis.

Macrophages regulates the transition of pericyte to peritoneal fibrosis through the GSDMD/IL-1β axis

BACKGROUND

End stage renal disease (ESRD) has caused public health problem with high prevalence worldwide. Peritoneum from peritoneal dialysis patients with ESRD can induce pathological changes of the peritoneum, including fibrosis. The trans-differentiation of pericytes has been found to be closely associated with inflammatory diseases, such as organ fibrosis. However, the function of macrophages in regulating the transition of pericyte to peritoneal fibrosis is unclear.

METHODS

Histological examination was conducted using Hematoxylin and eosin (HE) staining and Masson's trichrome staining. The protein levels were determined via western blot. Enzyme-linked immunosorbent assay (ELISA) was used to examine IL-1β concentrations. Gasdermin D (GSDMD) was knocked out in mice by Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR-Associated 9 (CRISPR-Cas9).

RESULTS

Mice receiving dextrose peritoneal dialysate displayed mesothelial cell monolayer loss and thickness of submesothelial compact zone increase. Moreover, dextrose peritoneal dialysate treatment up-regulated GSDMD expression. GSDMD knockdown inhibited IL-1β production in macrophages. Further, pericytes were treated with cultural supernatant from macrophages. We found that GSDMD knockdown suppressed fibrosis and vascular endothelial growth factor (VEGF)/phosphoinositide 3-kinase (PI3K) pathway in pericytes. In addition, GSDMD were knocked out in mice using CRISPR/Cas9. The histological examinations revealed that GSDMD-/- alleviated the damage of peritoneal tissue and thickness of submesothelial compact zone. GSDMD-/- attenuated interleukin-1beta (IL-1β) level and peritoneal fibrosis induced by dextrose peritoneal dialysate treatment in pericytes in vivo.

CONCLUSION

These results demonstrated that macrophages can regulate the transition of pericyte to peritoneal fibrosis via the GSDMD/IL-1β axis, which provides a new therapeutic target.

Ferroptosis, a New Insight Into Acute Lung Injury

Acute lung injury (ALI), a common and critical illness with high morbidity and mortality, is caused by multiple causes. It has been confirmed that oxidative stress plays an important role in the development of ALI. Ferroptosis, a newly discovered programmed cell death in 2012, is characterized by iron-dependent lipid peroxidation and involved in many diseases. To date, compelling evidence reveals the emerging role of ferroptosis in the pathophysiological process of ALI. Here, we review the role of ferroptosis in the pathogenesis of ALI and its therapeutic potential in ALI.

Tumor necrosis: A synergistic consequence of metabolic stress and inflammation

Tumor necrosis is a common histological feature and poor prognostic predictor in various cancers. Despite its significant clinical implications, the mechanism underlying tumor necrosis remains largely unclear due to lack of appropriate pre-clinical modeling. We propose that tumor necrosis is a synergistic consequence of metabolic stress and inflammation, which lead to oxidative stress-induced cell death, such as ferroptosis. As a natural consequence of tumor expansion, tumor cells are inevitably stripped of vascular supply, resulting in deprivation of oxygen and nutrients. The resulting metabolic stress has commonly been considered the cause of tumor necrosis. Recent studies found that immune cells, such as neutrophils, when recruited to tumors, can directly trigger ferroptosis in tumor cells, suggesting that immune cells can be involved in amplifying tumor necrosis. This article will discuss potential mechanisms underlying tumor necrosis development and its impact on tumor progression as well as the immune response to tumors.

Crosstalk between Oxidative Stress and Ferroptosis/Oxytosis in Ischemic Stroke: Possible Targets and Molecular Mechanisms

Oxidative stress is a key cause of ischemic stroke and an initiator of neuronal dysfunction and death, mainly through the overproduction of peroxides and the depletion of antioxidants. Ferroptosis/oxytosis is a unique, oxidative stress-induced cell death pathway characterized by lipid peroxidation and glutathione depletion. Both oxidative stress and ferroptosis/oxytosis have common molecular pathways. This review summarizes the possible targets and the mechanisms underlying the crosstalk between oxidative stress and ferroptosis/oxytosis in ischemic stroke. This knowledge might help to further understand the pathophysiology of ischemic stroke and open new perspectives for the treatment of ischemic stroke.

Ferroptosis resistance mechanisms in endometriosis for diagnostic model establishment

RESEARCH QUESTION

Does ferroptosis resistance occur in patients with endometriosis, and can it be used as an indicator for diagnosis?

DESIGN

Six datasets including 164 expression arrays from endometriosis studies were selected from the National Center for Biotechnology Information Gene Expression Omnibus. Surrogate variable analysis was used for data integration after RobustRankAggreg to determine ferroptosis-associated gene expression trends. Differential genes between eutopic and normal endometrium, as well as between ectopic and eutopic endometrium, were determined. Ferroptosis resistance mechanisms during the development of endometriosis were determined by intergenic co-expression and the Kyoto Encyclopedia of Genes and Genomes pathway. Independent factors were then screened by least absolute shrinkage and selection operator regression to build a nomogram diagnostic model. The Hosmer-Lemeshow test and receiver operating characteristic (ROC) curve were used to verify model consistency and diagnostic efficacy, respectively.

RESULTS

Differential analysis revealed a progressive increase in changes of ferroptosis-related genes in endometriosis patients during the process of endometrium development from eutopic to ectopic. In the subsequent regression selection, nine ferroptosis-associated genes in the eutopic endometrium could, in most cases, distinguish endometriosis patients from healthy patients. Therefore, these genes can be used as independent factors for endometriosis diagnosis. The nomogram model established by these molecular markers had an area under the ROC curve of 0.979.

CONCLUSIONS

The eutopic and ectopic endometrium of patients with endometriosis is associated with ferroptosis resistance genetic alterations. Ferroptosis-associated genes have excellent clinical value in endometriosis diagnosis, achieved by the nomogram model.

Ferroptosis and its emerging roles in cardiovascular diseases

Ferroptosis is a new form of regulated cell death (RCD) driven by iron-dependent lipid peroxidation, which is morphologically and mechanistically distinct from other forms of RCD including apoptosis, autophagic cell death, pyroptosis and necroptosis. Recently, ferroptosis has been found to participate in the development of various cardiovascular diseases (CVDs) including doxorubicin-induced cardiotoxicity, ischemia/reperfusion-induced cardiomyopathy, heart failure, aortic dissection and stroke. Cardiovascular homeostasis is indulged in delicate equilibrium of assorted cell types composing the heart or vessels, and how ferroptosis contributes to the pathophysiological responses in CVD progression is unclear. Herein, we reviewed recent discoveries on the basis of ferroptosis and its involvement in CVD pathogenesis, together with related therapeutic potentials, aiming to provide insights on fundamental mechanisms of ferroptosis and implications in CVDs and associated disorders.

The NLRP3 inflammasome: Multiple activation pathways and its role in primary cells during ventricular remodeling

Inflammasomes are a group of multiprotein signaling complexes located in the cytoplasm. Several inflammasomes have been identified, including NLRP1, NLRP2, NLRP3, AIM2, and NLRC4. Among them, NLRP3 was investigated in most detail, and it was reported that it can be activated by many different stimuli. Increased NLRP3 protein expression and inflammasome assembly lead to caspase-1 mediated maturation and release of IL-1β, which triggers inflammation and pyroptosis. The activation of the NLRP3 inflammasome has been widely reported in studies of tumors and neurological diseases, but relatively few studies on the cardiovascular system. Ventricular remodeling (VR) is an important factor contributing to heart failure (HF) after myocardial infarction (MI). Consequently, delaying VR is of great significance for improving heart function. Studies have shown that the NLRP3 inflammasome plays an essential role in the process of VR. Here, we reviewed the latest studies on the activation pathway of the NLRP3 inflammasome, focusing on the effects of the NLRP3 inflammasome in primary cells during VR, and finally discuss future research directions in this field.

M2-like macrophages exert hepatoprotection in acute-on-chronic liver failure through inhibiting necroptosis-S100A9-necroinflammation axis

Necroptosis has emerged as a novel and crucial player in acute and chronic liver diseases. Necroptotic cells lead to the release of DAMPs including S100A9, followed by the development of necroinflammation. We previously have documented the beneficial hepatoprotection conferred by M2-like macrophages in acute-on-chronic liver failure (ACLF) in vitro and in vivo, namely, M2-like macrophages protect hepatocytes against apoptosis. Herein, we integrated necroptosis, S100A9, and necroinflammation into this hepatoprotection, and hypothesized M2-like macrophages exert a hepatoprotective effect through inhibiting necroptosis-S100A9-necroinflammation axis. To testify this hypothesis, control mice were pre-treated with necroptosis or S100A9 inhibitors followed by D-GalN/LPS challenge. The extent of liver injury and M1/M2 macrophage activation was assessed. Necroptosis signaling and S100A9 expression were analysed and compared in control and fibrotic mice with or without acute insult. To document the pivotal role of M2-like macrophages in necroptosis and S100A9 inhibition, loss-of-function and gain-of-function experiments were performed. In addition, necroinflammation and its dependence on necroptosis and S100A9 were analysed. Moreover, the inhibitory effects of M2-like macrophages on necroinflammation were investigated in vivo and in vitro. We found that: firstly, the inhibition of necroptosis signaling and S100A9 expression alleviated D-GalN/LPS-induced hepatic damage, which was accompanied by M2-like macrophage activation; secondly, fibrosis inhibited necroptosis signaling and S100A9 expression, which could be attributed to M2-like macrophage activation; thirdly, S100A9 may function as a downstream player of necroptosis signaling; fourthly, fibrosis suppressed necroptosis- and S100A9-dependent necroinflammation; and finally, M2-like macrophages inhibited NLRP3 inflammasome activation and resultant necroinflammation via IL-10. Therefore, M2-like macrophages exert a beneficial hepatoprotection by inhibiting necroptosis-S100A9-necroinflammation axis in ACLF. Our findings provide novel insight for treating ACLF patients by specially targeting this signaling axis.

Time-course effect of ultrasmall superparamagnetic iron oxide nanoparticles on intracellular iron metabolism and ferroptosis activation

Ferroptosis is an iron-dependent cell death caused by excessive peroxidation of polyunsaturated fatty acids. It can be activated by iron-based nanoparticles as a potential cancer therapeutic target. However, the intracellular transformation of iron-based nanoparticles is still ambiguous and the subsequent ferroptosis mechanism is also obscure. Here, we identified the time-course metabolism of ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) in cells by using X-ray absorption near edge structure spectroscopy. Also, the integrated quantitative transcriptome and proteome data obtained from the cells exposed to USPIO exhibited hallmark features of ferroptosis. With the chemical species of iron oxide transforming to ferritin, the intracellular GPX4 down-regulated, and lipid peroxide began to accumulate. These results provide evidence that the intracellular metabolism of USPIO induced ferroptosis in a time-dependent manner, and iron over-loaded in cytoplasm along with lipid peroxidation of the membrane are involved in the detailed mechanism of ferroptosis signaling activation.

Ferroptosis as a novel therapeutic target for cardiovascular disease

Cell death is an important component of the pathophysiology of cardiovascular disease. An understanding of how cardiomyocytes die, and why regeneration of cells in the heart is limited, is a critical area of study. Ferroptosis is a form of regulated cell death that is characterized by iron overload, leading to accumulation of lethal levels of lipid hydroperoxides. The metabolism of iron, lipids, amino acids and glutathione tightly controls the initiation and execution of ferroptosis. Emerging evidence shows that ferroptosis is closely associated with the occurrence and progression of various diseases. In recent years, ferroptosis has been found to play critical roles in cardiomyopathy, myocardial infarction, ischemia/reperfusion injury, and heart failure. This article reviews the mechanisms by which ferroptosis is initiated and controlled and discusses ferroptosis as a novel therapeutic target for various cardiovascular diseases.

Peptides in Colorectal Cancer: Current State of Knowledge

Colorectal cancer (CRC) is the second most deadly and the third most commonly diagnosed cancer in the world. CRC treatment is mainly based on surgery, chemotherapy, and even though the probability of complications after surgery is very low, chemo drugs affect the patient's quality of life. Multiple studies have shown a strong correlation between diet and the onset and progression of CRC. Thus, the consumption of dietary nutraceuticals for its treatment and prevention has been suggested as a promising option. Peptides have increasingly become of interest in human health due to their antioxidant, antihypertensive, and anticancer potential. In recent years, there have been extensive reports on peptides with anti-tumor activity, and some studies suggest that peptides modulate cell proliferation, evasion of cell death, and metastasis in malignant cells. Plant-derived peptides such as soybean, bean, and rice have received main attention. In this review, we show evidence of several mechanisms through which bioactive peptides exert anti-tumor activity over in vitro and in vivo CRC models. We also report the current status of major production techniques, as well as limitations and future perspectives. Graphical Abstract.

ROS-Mediated Necroptosis Is Involved in Iron Overload-Induced Osteoblastic Cell Death

Excess iron has been reported to lead to osteoblastic cell damage, which is a crucial pathogenesis of iron overload-related osteoporosis. However, the cytotoxic mechanisms have not been fully documented. In the present study, we focused on whether necroptosis contributes to iron overload-induced osteoblastic cell death and related underlying mechanisms. Here, we showed that the cytotoxicity of iron overload in osteoblastic cells was mainly due to necrosis, as evidenced by the Hoechst 33258/PI staining, Annexin-V/PI staining, and transmission electronic microscopy. Furthermore, we revealed that iron overload-induced osteoblastic necrosis might be mediated via the RIPK1/RIPK3/MLKL necroptotic pathway. In addition, we also found that iron overload was able to trigger mitochondrial permeability transition pore (mPTP) opening, which is a critical downstream event in the execution of necroptosis. The key finding of our experiment was that iron overload-induced necroptotic cell death might depend on reactive oxygen species (ROS) generation, as N-acetylcysteine effectively rescued mPTP opening and necroptotic cell death. ROS induced by iron overload promote necroptosis via a positive feedback mechanism, as on the one hand N-acetylcysteine attenuates the upregulation of RIPK1 and RIPK3 and phosphorylation of RIPK1, RIPK3, and MLKL and on the other hand Nec-1, siRIPK1, or siRIPK3 reduced ROS generation. In summary, iron overload induced necroptosis of osteoblastic cells in vitro, which is mediated, at least in part, through the RIPK1/RIPK3/MLKL pathway. We also highlight the critical role of ROS in the regulation of iron overload-induced necroptosis in osteoblastic cells.

The role of lysosome in regulated necrosis

Lysosome is a ubiquitous acidic organelle fundamental for the turnover of unwanted cellular molecules, particles, and organelles. Currently, the pivotal role of lysosome in regulating cell death is drawing great attention. Over the past decades, we largely focused on how lysosome influences apoptosis and autophagic cell death. However, extensive studies showed that lysosome is also prerequisite for the execution of regulated necrosis (RN). Different types of RN have been uncovered, among which, necroptosis, ferroptosis, and pyroptosis are under the most intensive investigation. It becomes a hot topic nowadays to target RN as a therapeutic intervention, since it is important in many patho/physiological settings and contributing to numerous diseases. It is promising to target lysosome to control the occurrence of RN thus altering the outcomes of diseases. Therefore, we aim to give an introduction about the common factors influencing lysosomal stability and then summarize the current knowledge on the role of lysosome in the execution of RN, especially in that of necroptosis, ferroptosis, and pyroptosis.

T95 nucleophosmin phosphorylation as a novel mediator and marker of regulated cell death in acute kidney injury

The function of site-specific phosphorylation of nucleophosmin (NPM), an essential Bax chaperone, in stress-induced cell death is unknown. We hypothesized that NPM threonine 95 (T95) phosphorylation both signals and promotes cell death. In resting cells, NPM exclusively resides in the nucleus and T95 is nonphosphorylated. In contrast, phosphorylated T95 NPM (pNPM T95) accumulates in the cytosol after metabolic stress, in multiple human cancer cell lines following γ-radiation, and in postischemic human kidney tissue. Based on the T95 phosphorylation consensus sequence, we hypothesized that glycogen synthase kinase-3β (GSK-3β) regulates cytosolic NPM translocation by phosphorylating T95 NPM. In a cell-free system, GSK-3β phosphorylated a synthetic NPM peptide containing T95. In vitro, bidirectional manipulation of GSK-3β activity substantially altered T95 phosphorylation, cytosolic NPM translocation, and cell survival during stress, mechanistically linking these lethal events. Furthermore, GSK-3β inhibition in vivo decreased cytosolic pNPM T95 accumulation in kidney tissue after experimental ischemia. In patients with acute kidney injury, both cytosolic NPM accumulation in proximal tubule cells and NPM-rich intratubular casts were detected in frozen renal biopsy tissue. These observations show, for the first time, that GSK-3β promotes cell death partly by phosphorylating NPM at T95, to promote cytosolic NPM accumulation. T95 NPM is also a rational therapeutic target to ameliorate ischemic renal cell injury and may be a universal injury marker in mammalian cells.

Necroptosis in Hepatosteatotic Ischaemia-Reperfusion Injury

While liver transplantation remains the sole treatment option for patients with end-stage liver disease, there are numerous limitations to liver transplantation including the scarcity of donor livers and a rise in livers that are unsuitable to transplant such as those with excess steatosis. Fatty livers are susceptible to ischaemia-reperfusion (IR) injury during transplantation and IR injury results in primary graft non-function, graft failure and mortality. Recent studies have described new cell death pathways which differ from the traditional apoptotic pathway. Necroptosis, a regulated form of cell death, has been associated with hepatic IR injury. Receptor-interacting protein kinase 3 (RIPK3) and mixed-lineage kinase domain-like pseudokinase (MLKL) are thought to be instrumental in the execution of necroptosis. The study of hepatic necroptosis and potential therapeutic approaches to attenuate IR injury will be a key factor in improving our knowledge regarding liver transplantation with fatty donor livers. In this review, we focus on the effect of hepatic steatosis during liver transplantation as well as molecular mechanisms of necroptosis and its involvement during liver IR injury. We also discuss the immune responses triggered during necroptosis and examine the utility of necroptosis inhibitors as potential therapeutic approaches to alleviate IR injury.

Regulated Necrosis in Pulmonary Disease. A Focus on Necroptosis and Ferroptosis

To date, increasing evidence suggests the possible involvement of various types of cell death in lung diseases. The recognized regulated cell death includes necrotic cell death that is immunogenic, releasing damage-associated molecular patterns and driving tissue inflammation. Necroptosis is a well-understood form of regulated necrosis that is executed by RIPK3 (receptor-interacting protein kinase 3) and the pseudokinase MLKL (mixed lineage kinase domain-like protein). Ferroptosis is a newly described caspase-independent form of regulated necrosis that is characterized by the increase of detrimental lipid reactive oxygen species produced via iron-dependent lipid peroxidation. The role of these two cell death pathways differs depending on the disease, cell type, and microenvironment. Moreover, some experimental cell death models have demonstrated shared ferroptotic and necroptotic cell death and the synergistic effect of simultaneous inhibition. This review examines the role of regulated necrotic cell death, particularly necroptosis and ferroptosis, in lung disease pathogenesis in the context of recent insights into the roles of the key effector molecules of these two cell death pathways.

Surviving anoxia: the maintenance of energy production and tissue integrity during anoxia and reoxygenation

The development of anoxia within tissues represents a significant challenge to most animals because of the decreased capacity for aerobic ATP production, the associated loss of essential cellular functions and the potential for detrimental tissue oxidation upon reoxygenation. Despite these challenges, there are many animals from multiple phyla that routinely experience anoxia and can fully recover. In this Review, we integrate knowledge gained from studies of anoxia-tolerant species across many animal taxa. We primarily focus on strategies used to reduce energy requirements, minimize the consequences of anaerobic ATP production and reduce the adverse effects of reactive oxygen species, which are responsible for tissue damage with reoxygenation. We aim to identify common strategies, as well as novel solutions, to the challenges of anoxia exposure. This Review chronologically examines the challenges faced by animals as they enter anoxia, as they attempt to maintain physiological function during prolonged anoxic exposure and, finally, as they emerge from anoxia. The capacity of animals to survive anoxia is also considered in relation to the increasing prevalence of anoxic zones within marine and freshwater environments, and the need to understand what limits survival.

Induction of programmed necrosis: A novel anti-cancer strategy for natural compounds

Cell death plays a critical role in organism development and the pathogenesis of diseases. Necrosis is considered a non-programmed cell death in an extreme environment. Recent advances have provided solid evidence that necrosis could be programmed and quite a few types of programmed necrosis, such as necroptosis, ferroptosis, pyroptosis, paraptosis, mitochondrial permeability transition-driven necrosis, and oncosis, have been identified. The specific biomarkers, detailed signaling, and precise pathophysiological importance of programmed necrosis are yet to be clarified, but these forms of necrosis provide novel strategies for the treatment of various diseases, including cancer. Natural compounds are a unique source of lead compounds for the discovery of anti-cancer drugs. Natural compounds can induce both apoptosis and programmed necrosis. In this review, we summarized the recent progress of programmed necrosis and introduced their natural inducers. Noptosis, which is a novel type of programmed necrosis that is strictly dependent on NAD(P)H: quinone oxidoreductase 1-derived oxidative stress was proposed. Furthermore, the anti-cancer strategies that take advantage of programmed necrosis and the main concerns from the scientific community in this regard were discussed.

GSDME-Dependent Incomplete Pyroptosis Permits Selective IL-1α Release under Caspase-1 Inhibition

Pyroptosis is a form of regulated cell death that is characterized by gasdermin processing and increased membrane permeability. Caspase-1 and caspase-11 have been considered to be essential for gasdermin D processing associated with inflammasome activation. In the present study, we found that NLRP3 inflammasome activation induces delayed necrotic cell death via ASC in caspase-1/11-deficient macrophages. Furthermore, ASC-mediated caspase-8 activation and subsequent gasdermin E processing are necessary for caspase-1-independent necrotic cell death. We define this necrotic cell death as incomplete pyroptosis because IL-1β release, a key feature of pyroptosis, is absent, whereas IL-1α release is induced. Notably, unprocessed pro-IL-1β forms a molecular complex to be retained inside pyroptotic cells. Moreover, incomplete pyroptosis accompanied by IL-1α release is observed under the pharmacological inhibition of caspase-1 with VX765. These findings suggest that caspase-1 inhibition during NLRP3 inflammasome activation modulates forms of cell death and permits the release of IL-1α from dying cells.

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NLRP3 inflammasome induces necrotic cell death in the absence of caspase-1/11

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ASC initiates GSDME-dependent pyroptosis via caspase-8

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IL-1α, but not IL-1β, is released during Casp1/11-independent pyroptosis

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Pharmacological inhibition of caspase-1 permits IL-1α release during pyroptosis

Imaging Cell Death: Focus on Early Evaluation of Tumor Response to Therapy

Cell death plays a prominent role in the treatment of cancer, because most anticancer therapies act by the induction of cell death including apoptosis, necrosis, and other pathways of cell death. Imaging cell death helps to identify treatment responders from nonresponders and thus enables patient-tailored therapy, which will increase the likelihood of treatment response and ultimately lead to improved patient survival. By taking advantage of molecular probes that specifically target the biomarkers/biochemical processes of cell death, cell death imaging can be successfully achieved. In recent years, with the increased understanding of the molecular mechanism of cell death, a variety of well-defined biomarkers/biochemical processes of cell death have been identified. By targeting these established cell death biomarkers/biochemical processes, a set of molecular imaging probes have been developed and evaluated for early monitoring treatment response in tumors. In this review, we mainly present the recent advances in identifying useful biomarkers/biochemical processes for both apoptosis and necrosis imaging and in developing molecular imaging probes targeting these biomarkers/biochemical processes, with a focus on their application in early evaluation of tumor response to therapy.