Lipid Peroxidation Drives Gasdermin D-Mediated Pyroptosis in Lethal Polymicrobial Sepsis

Free Radical and Viral Infection: A Review from the Perspective of Ferroptosis

Free radicals, including reactive oxygen species (ROS) and reactive nitrogen species (RNS), play critical roles in various physiological activities such as cell differentiation, apoptosis, and vascular tension when existing in cells at low levels. However, excessive amounts of free radicals are harmful, causing DNA damage, lipid peroxidation, protein degeneration, and abnormal cell death. Certain viral infections induce cells to produce excessive free radicals, which in multiple ways help the virus to replicate, mature, and exit. Iron is a necessary element for many intracellular enzymes, involved in both cellular activities and viral replication. Ferroptosis, a programmed cell death mode distinct from apoptosis, necrosis, and pyroptosis, is characterized by lipid peroxide accumulation and damage to the antioxidant system, affecting many cellular processes. Viral infection commonly manifests as decreased glutathione (GSH) content and down-regulated glutathione peroxidase 4 (GPX4) activity, similar to ferroptosis. Recent studies have suggested a possible relationship among free radicals, viral infections and ferroptosis. This review aims to elucidate the molecular mechanism linking free radicals and ferroptosis during viral infections and provide a new theoretical basis for studying viral pathogenesis and control.

CONSTRUCTION OF SEPSIS DIAGNOSTIC MODELS AND IDENTIFICATION OF MACROPHAGE SUBPOPULATIONS BASED ON PYROPTOSIS-RELATED GENES

ABSTRACT

Background: Numerous studies have shown that pyroptosis is associated with sepsis progression, which can lead to dysregulated host immune responses and organ dysfunction. Therefore, investigating the potential prognostic and diagnostic values of pyroptosis in patients with sepsis is essential. Methods: We conducted a study using bulk and single-cell RNA sequencing (scRNA-seq) from the Gene Expression Omnibus database to examine the role of pyroptosis in sepsis. Univariate logistic analysis, least absolute shrinkage, and selection operator regression analysis were used to identify pyroptosis-related genes (PRGs), construct a diagnostic risk score model, and evaluate the selected genes' diagnostic value. Consensus clustering analysis was used to identify the PRG-related sepsis subtypes with varying prognoses. Functional and immune infiltration analyses were used to explain the subtypes' distinct prognoses, and scRNA-seq data were used to differentiate immune-infiltrating cells and macrophage subsets and study cell-cell communication. Results: A risk model was established based on 10 key PRGs ( NAIP , ELANE , GSDMB , DHX9 , NLRP3 , CASP8 , GSDMD , CASP4 , APIP , and DPP9 ), of which four ( ELANE , DHX9 , GSDMD , and CASP4 ) were associated with prognosis. Two subtypes with different prognoses were identified based on the key PRG expressions. Functional enrichment analysis revealed diminished nucleotide oligomerization domain-like receptor pathway activity and enhanced neutrophil extracellular trap formation in the subtype with a poor prognosis. Immune infiltration analysis suggested a different immune status between the two sepsis subtypes, with the subtype with a poor prognosis exhibiting stronger immunosuppression. The single-cell analysis identified a macrophage subpopulation characterized by gasdermin D (GSDMD) expression that may be involved in pyroptosis regulation, which was associated with the prognosis of sepsis. Conclusion: We developed and validated a risk score for sepsis identification based on 10 PRGs, four of which also have potential value in the prognosis of sepsis. We identified a subset of gasdermin D macrophages associated with poor prognosis, providing new insights into the role of pyroptosis in sepsis.

Harnessing the Potential of Non-Apoptotic Cell Death Processes in the Treatment of Drug-Resistant Melanoma

Melanoma is a highly malignant skin cancer that is known for its resistance to treatments. In recent years, there has been significant progress in the study of non-apoptotic cell death, such as pyroptosis, ferroptosis, necroptosis, and cuproptosis. This review provides an overview of the mechanisms and signaling pathways involved in non-apoptotic cell death in melanoma. This article explores the interplay between various forms of cell death, including pyroptosis, necroptosis, ferroptosis, and cuproptosis, as well as apoptosis and autophagy. Importantly, we discuss how these non-apoptotic cell deaths could be targeted as a promising therapeutic strategy for the treatment of drug-resistant melanoma. This review provides a comprehensive overview of non-apoptotic processes and gathers recent experimental evidence that will guide future research and eventually the creation of treatment strategies to combat drug resistance in melanoma.

ABCA1 deficiency contributes to podocyte pyroptosis priming via the APE1/IRF1 axis in diabetic kidney disease

Decreased ATP Binding Cassette Transporter A1 (ABCA1) expression and caspase-4-mediated noncanonical inflammasome contribution have been described in podocytes in diabetic kidney disease (DKD). To investigate a link between these pathways, we evaluated pyroptosis-related mediators in human podocytes with stable knockdown of ABCA1 (siABCA1) and found that mRNA levels of IRF1, caspase-4, GSDMD, caspase-1 and IL1β were significantly increased in siABCA1 compared to control podocytes and that protein levels of caspase-4, GSDMD and IL1β were equally increased. IRF1 knockdown in siABCA1 podocytes prevented increases in caspase-4, GSDMD and IL1β. Whereas TLR4 inhibition did not decrease mRNA levels of IRF1 and caspase-4, APE1 protein expression increased in siABCA1 podocytes and an APE1 redox inhibitor abrogated siABCA1-induced expression of IRF1 and caspase-4. RELA knockdown also offset the pyroptosis priming, but ChIP did not demonstrate increased binding of NFκB to IRF1 promoter in siABCA1 podocytes. Finally, the APE1/IRF1/Casp1 axis was investigated in vivo. APE1 IF staining and mRNA levels of IRF1 and caspase 11 were increased in glomeruli of BTBR ob/ob compared to wildtype. In conclusion, ABCA1 deficiency in podocytes caused APE1 accumulation, which reduces transcription factors to increase the expression of IRF1 and IRF1 target inflammasome-related genes, leading to pyroptosispriming.

Caffeic acid, but not ferulic acid, inhibits macrophage pyroptosis by directly blocking gasdermin D activation

Regulated pyroptosis is critical for pathogen elimination by inducing infected cell rupture and pro-inflammatory cytokines secretion, while overwhelmed pyroptosis contributes to organ dysfunction and pathological inflammatory response. Caffeic acid (CA) and ferulic acid (FA) are both well-known antioxidant and anti-inflammatory phenolic acids, which resemble in chemical structure. Here we found that CA, but not FA, protects macrophages from both Nigericin-induced canonical and cytosolic lipopolysaccharide (LPS)-induced non-canonical pyroptosis and alleviates LPS-induced mice sepsis. It significantly improved the survival of pyroptotic cells and LPS-challenged mice and blocked proinflammatory cytokine secretion. The anti-pyroptotic effect of CA is independent of its regulations in cellular lipid peroxidation, mitochondrial function, or pyroptosis-associated gene transcription. Instead, CA arrests pyroptosis by directly associating with gasdermin D (GSDMD) and blocking its processing, resulting in reduced N-GSDMD pore construction and less cellular content release. In LPS-induced septic mice, CA inhibits GSDMD activation in peritoneal macrophages and reduces the serum levels of interleukin-1β and tumor necrosis factor-α as the known pyroptosis inhibitors, disulfiram and dimethyl fumarate. Collectively, these findings suggest that CA inhibits pyroptosis by targeting GSDMD and is a potential candidate for curbing the pyroptosis-associated disease.

Mitochondrial dysfunctions induce PANoptosis and ferroptosis in cerebral ischemia/reperfusion injury: from pathology to therapeutic potential

Ischemic stroke (IS) accounts for more than 80% of the total stroke, which represents the leading cause of mortality and disability worldwide. Cerebral ischemia/reperfusion injury (CI/RI) is a cascade of pathophysiological events following the restoration of blood flow and reoxygenation, which not only directly damages brain tissue, but also enhances a series of pathological signaling cascades, contributing to inflammation, further aggravate the damage of brain tissue. Paradoxically, there are still no effective methods to prevent CI/RI, since the detailed underlying mechanisms remain vague. Mitochondrial dysfunctions, which are characterized by mitochondrial oxidative stress, Ca²⁺ overload, iron dyshomeostasis, mitochondrial DNA (mtDNA) defects and mitochondrial quality control (MQC) disruption, are closely relevant to the pathological process of CI/RI. There is increasing evidence that mitochondrial dysfunctions play vital roles in the regulation of programmed cell deaths (PCDs) such as ferroptosis and PANoptosis, a newly proposed conception of cell deaths characterized by a unique form of innate immune inflammatory cell death that regulated by multifaceted PANoptosome complexes. In the present review, we highlight the mechanisms underlying mitochondrial dysfunctions and how this key event contributes to inflammatory response as well as cell death modes during CI/RI. Neuroprotective agents targeting mitochondrial dysfunctions may serve as a promising treatment strategy to alleviate serious secondary brain injuries. A comprehensive insight into mitochondrial dysfunctions-mediated PCDs can help provide more effective strategies to guide therapies of CI/RI in IS.

Gasdermin D-mediated pyroptosis: mechanisms, diseases, and inhibitors

Gasdermin D (GSDMD)-mediated pyroptosis and downstream inflammation are important self-protection mechanisms against stimuli and infections. Hosts can defend against intracellular bacterial infections by inducing cell pyroptosis, which triggers the clearance of pathogens. However, pyroptosis is a double-edged sword. Numerous studies have revealed the relationship between abnormal GSDMD activation and various inflammatory diseases, including sepsis, coronavirus disease 2019 (COVID-19), neurodegenerative diseases, nonalcoholic steatohepatitis (NASH), inflammatory bowel disease (IBD), and malignant tumors. GSDMD, a key pyroptosis-executing protein, is linked to inflammatory signal transduction, activation of various inflammasomes, and the release of downstream inflammatory cytokines. Thus, inhibiting GSDMD activation is considered an effective strategy for treating related inflammatory diseases. The study of the mechanism of GSDMD activation, the formation of GSDMD membrane pores, and the regulatory strategy of GSDMD-mediated pyroptosis is currently a hot topic. Moreover, studies of the structure of caspase-GSDMD complexes and more in-depth molecular mechanisms provide multiple strategies for the development of GSDMD inhibitors. This review will mainly discuss the structures of GSDMD and GSDMD pores, activation pathways, GSDMD-mediated diseases, and the development of GSDMD inhibitors.

Pyroptosis-related genes prognostic model for predicting targeted therapy and immunotherapy response in soft tissue sarcoma

Several studies have highlighted the potential of pyroptosis as a target for cancer treatment. This article focuses on the specific roles and clinical implications of pyroptosis-related genes (PRGs) in soft tissue sarcoma (STS). By analyzing differentially expressed PRGs in STS compared to normal tissue, our study evaluates the interactions, biological functions, and prognostic values of PRGs in STS. Through LASSO COX regression analysis, a five-gene survival related-risk score (PLCG1, PYCARD, CASP8, NOD1, and NOD2) was created, which examined both in TCGA cohort and training cohort (GSE21050, GSE30929, and GSE63157). Furthermore, we developed a nomogram incorporating clinic factors and the risk scores of the PRGs, which showed decent accuracy of prediction as evidenced by calibration curves. Additionally, our study analyzed the Tumor Immune Dysfunction and Exclusion Algorithm (TIDE) and IMvigor 210 cohorts to investigate the immunotherapy response, and found that immunotherapy was more beneficial for patients with minimal risk of PRGs than those exhibiting greater risk. Finally, GDSC and CAMP databases were used to screen for effective chemotherapy or targeted drugs that are sensitive to the high-risk populations, including doxorubicin, imatinib, and sorafenib. In conclusion, this study provides a comprehensive analysis of the PRG landscape in STS and constructs a novel risk model to predict prognosis and different therapeutic responses of STS patients, which is helpful for achieving precision medicine.

Protection of Oxygen Glucose Deprivation-Induced Human Brain Vascular Pericyte Injury: Beneficial Effects of Bellidifolin in Cellular Pyroptosis

Pericytes play critical roles in the maintenance of brain vascular homeostasis. However, very little is currently known about how pericytes regulate ischemic stroke-induced brain injury. Inflammation is a key event in the pathobiology of stroke, in which the nod-like receptor protein-3 (NLRP3) inflammasome is involved in, triggering sterile inflammatory responses and pyroptosis. In the current study, an immortalized cell line derived from human brain vascular pericytes (HBVPs) was constructed, and it showed that HBVPs challenged with oxygen glucose deprivation (OGD) displays pronounced cellular excretion of LDH, IL-1β, IL-18 and increased PI positive staining. Mechanistically, upon OGD treatment, NLRP3 forms an inflammasome with its adaptor protein apoptosis-associated speck-like protein, containing a caspase recruitment domain (ASC) and caspase-1, manifested as much more co-stainings of NLRP3, ASC and Caspase-1 in HBVPs, accompanied by the increased protein levels of NLRP3, ASC, caspase-1 as well as the pyroptosis-associated protein gasdermin D (GSDMD). Intriguingly, GSDMD-N shuttled to the mitochondrial membrane triggered by OGD exposure, which promoted massive mitochondria-derived ROS generation. Importantly, the invention value of the specific targets was evaluated by treatment with bellidifolin, a kind of ketone compound derived from Swertia chirayita in traditional Tibetan medicine. It showed that bellidifolin exerts beneficial effects and attenuates the formation of NLRP3/ASC/Caspase-1 complex, thereby impeding GSDMD-N shuttling and resultant ROS generation, protecting against OGD-induced HBVPs pyroptosis. Overall, these findings unravel the potential mechanisms of pericyte injury induced by OGD and indicate that bellidifolin may exert its beneficial effects on pyroptosis, thus providing new therapeutic insights into stroke.

A Lipid Perspective on Regulated Pyroptosis

Pyroptosis is a novel pro-inflammatory cell programmed death dependent on Gasdermin (GSMD) family-mediated membrane pore formation and subsequent cell lysis, accompanied by the release of inflammatory factors and expanding inflammation in multiple tissues. All of these processes have impacts on a variety of metabolic disorders. Dysregulation of lipid metabolism is one of the most prominent metabolic alterations in many diseases, including the liver, cardiovascular system, and autoimmune diseases. Lipid metabolism produces many bioactive lipid molecules, which are important triggers and endogenous regulators of pyroptosis. Bioactive lipid molecules promote pyroptosis through intrinsic pathways involving reactive oxygen species (ROS) production, endoplasmic reticulum (ER) stress, mitochondrial dysfunction, lysosomal disruption, and the expression of related molecules. Pyroptosis can also be regulated during the processes of lipid metabolism, including lipid uptake and transport, de novo synthesis, lipid storage, and lipid peroxidation. Taken together, understanding the correlation between lipid molecules such as cholesterol and fatty acids and pyroptosis during metabolic processes can help to gain insight into the pathogenesis of many diseases and develop effective strategies from the perspective of pyroptosis.

Ferroptosis in lung cancer: a novel pathway regulating cell death and a promising target for drug therapy

Lung cancer is a common malignant tumor that occurs in the human body and poses a serious threat to human health and quality of life. The existing treatment methods mainly include surgical treatment, chemotherapy, and radiotherapy. However, due to the strong metastatic characteristics of lung cancer and the emergence of related drug resistance and radiation resistance, the overall survival rate of lung cancer patients is not ideal. There is an urgent need to develop new treatment strategies or new effective drugs to treat lung cancer. Ferroptosis, a novel type of programmed cell death, is different from the traditional cell death pathways such as apoptosis, necrosis, pyroptosis and so on. It is caused by the increase of iron-dependent reactive oxygen species due to intracellular iron overload, which leads to the accumulation of lipid peroxides, thus inducing cell membrane oxidative damage, affecting the normal life process of cells, and finally promoting the process of ferroptosis. The regulation of ferroptosis is closely related to the normal physiological process of cells, and it involves iron metabolism, lipid metabolism, and the balance between oxygen-free radical reaction and lipid peroxidation. A large number of studies have confirmed that ferroptosis is a result of the combined action of the cellular oxidation/antioxidant system and cell membrane damage/repair, which has great potential application in tumor therapy. Therefore, this review aims to explore potential therapeutic targets for ferroptosis in lung cancer by clarifying the regulatory pathway of ferroptosis. Based on the study of ferroptosis, the regulation mechanism of ferroptosis in lung cancer was understood and the existing chemical drugs and natural compounds targeting ferroptosis in lung cancer were summarized, with the aim of providing new ideas for the treatment of lung cancer. In addition, it also provides the basis for the discovery and clinical application of chemical drugs and natural compounds targeting ferroptosis to effectively treat lung cancer.

Predictive value of ferroptosis-related biomarkers for diabetic kidney disease: a prospective observational study

AIMS

To explore the predictive value of ferroptosis-related (FR) biomarkers for diabetic kidney disease (DKD) in patients with type 2 diabetes mellitus (T2DM).

METHODS

This prospective observational study enrolled patients with T2DM at the Second Hospital of Jilin University between December 2021 and March 2022. DKD was measured by the urinary albumin-to-creatinine ratio. Receiver operating characteristic curve (ROC) analysis was performed to assess the predictive value of ferroptosis-related biomarkers for DKD.The risk factors for massive proteinuria were performed by multivariable logistic regression analysis.

RESULTS

Finally, 118 patients (53.0 ± 12.2 years, 76 males) were enrolled, 52 of them without DKD (had normal proteinuria), while 66 with DKD. (Forty-one had microproteinuria, and 25 had massive proteinuria.) FR biomarkers, including acyl-CoA synthase long chain family member 4 (ACSL4), malondialdehyde (MDA), and reactive oxygen species (ROS), were significantly higher in the massive proteinuria group than in the other groups, while glutathione peroxidase 4 (GPX4) was significantly lower (all P < 0.05). The area under the ROC of the combination of GPX4, ACSL4, MDA, and ROS for predicting DKD was 0.804 (P < 0.001). Additionally, multivariate logistic regression analysis showed that the course of disease and ferritin levels were independent risk factors for massive proteinuria, while high serum iron, transferrin, and GPX4 levels were independent protective factors for massive proteinuria in patients with T2DM (all P < 0.05).

CONCLUSIONS

The GPX4, ACSL4, MDA, and ROS combination might have a good predictive value for DKD. Additionally, the course of disease, ferritin levels, serum iron, transferrin, and GPX4 were independently associated with massive proteinuria.

Neurochemical effects of sepsis on the brain

Sepsis is a life-threatening organ dysfunction triggered by a dysregulated host immune response to eliminate an infection. After the host immune response is activated, a complex, dynamic, and time-dependent process is triggered. This process promotes the production of inflammatory mediators, including acute-phase proteins, complement system proteins, cytokines, chemokines, and antimicrobial peptides, which are required to initiate an inflammatory environment for eliminating the invading pathogen. The physiological response of this sepsis-induced systemic inflammation can affect blood-brain barrier (BBB) function; subsequently, endothelial cells produce inflammatory mediators, including cytokines, chemokines, and matrix metalloproteinases (MMPs) that degrade tight junction (TJ) proteins and decrease BBB function. The resulting BBB permeability allows peripheral immune cells from the bloodstream to enter the brain, which then release a range of inflammatory mediators and activate glial cells. The activated microglia and astrocytes release reactive oxygen species (ROS), cytokines, chemokines, and neurochemicals, initiate mitochondrial dysfunction and neuronal damage, and exacerbate the inflammatory milieu in the brain. These changes trigger sepsis-associated encephalopathy (SAE), which has the potential to increase cognitive deterioration and susceptibility to cognitive decline later in life.

The interaction between ferroptosis and inflammatory signaling pathways

Ferroptosis is an iron-dependent regulated cell death driven by excessive lipid peroxidation. Inflammation is one common and effective physiological event that protects against various stimuli to maintain tissue homeostasis. However, the dysregulation of inflammatory responses can cause imbalance of the immune system, cell dysfunction and death. Recent studies have pointed out that activation of inflammation, including the activation of multiple inflammation-related signaling pathways, can lead to ferroptosis. Among the related signal transduction pathways, we focused on five classical inflammatory pathways, namely, the JAK-STAT, NF-κB, inflammasome, cGAS-STING and MAPK signaling pathways, and expounded on their roles in ferroptosis. To date, many agents have shown therapeutic effects on ferroptosis-related diseases by modulating the aforementioned pathways in vivo and in vitro. Moreover, the regulatory effects of these pathways on iron metabolism and lipid peroxidation have been described in detail, contributing to further understanding of the pathophysiological process of ferroptosis. Taken together, targeting these pathways related to inflammation will provide appropriate ways to intervene ferroptosis and diseases.

Regulated cell death in cancer: from pathogenesis to treatment

ABSTRACT

Regulated cell death (RCD), including apoptosis, pyroptosis, necroptosis, and ferroptosis, is regulated by a series of evolutionarily conserved pathways, and is required for development and tissue homeostasis. Based on previous genetic and biochemical explorations of cell death subroutines, the characteristics of each are generally considered distinctive. However, recent in-depth studies noted the presence of crosstalk between the different forms of RCD; hence, the concept of PANoptosis appeared. Cancer, a complex genetic disease, is characterized by stepwise deregulation of cell apoptosis and proliferation, with significant morbidity and mortality globally. At present, studies on the different RCD pathways, as well as the intricate relationships between different cell death subroutines, mainly focus on infectious diseases, and their roles in cancer remain unclear. As cancers are characterized by dysregulated cell death and inflammatory responses, most current treatment strategies aim to selectively induce cell death via different RCD pathways in cancer cells. In this review, we describe five types of RCD pathways in detail with respect to tumorigenesis and cancer progression. The potential value of some of these key effector molecules in tumor diagnosis and therapeutic response has also been raised. We then review and highlight recent progress in cancer treatment based on PANoptosis and ferroptosis induced by small-molecule compounds, immune checkpoint inhibitors, and nanoparticles. Together, these findings may provide meaningful evidence to fill in the gaps between cancer pathogenesis and RCD pathways to develop better cancer therapeutic strategies.

ALDH2 attenuates myocardial pyroptosis through breaking down Mitochondrion-NLRP3 inflammasome pathway in septic shock

Cell survival or death is critical for cardiac function. Myocardial pyroptosis, as a newly recognized programmed cell death, remains poorly understood in sepsis. In this study, we evaluated the effect of aldehyde dehydrogenase (ALDH2) on myocardial pyroptosis and revealed the underlying mechanisms in sepsis. We established a septic shock mice model by intraperitoneal injection of Lipopolysaccharide (LPS, 15 mg/kg) 12 h before sacrifice. It was found that aldehyde dehydrogenase significantly inhibited NOD-like receptor protein 3 (NLRP3) inflammasome activation and Caspase-1/GSDMD-dependent pyroptosis, which remarkably improved survival rate and septic shock-induced cardiac dysfunction, relative to the control group. While aldehyde dehydrogenase knockout or knockdown significantly aggravated these phenomena. Intriguingly, we found that aldehyde dehydrogenase inhibited LPS-induced deacetylation of Hydroxyacyl-CoA dehydrogenase trifunctional multienzyme complex α subunit (HADHA) by suppressing the translocation of Histone deacetylase 3 (HDAC3) from nuclei to mitochondria. Acetylated HADHA is essential for mitochondrial fatty acid β-oxidation, and its interruption can result in accumulation of toxic lipids, induce mROS and cause mtDNA and ox-mtDNA release. Our results confirmed the role of Histone deacetylase 3 and HADHA in NOD-like receptor protein 3 inflammasome activation. Hdac3 knockdown remarkedly suppressed NOD-like receptor protein 3 inflammasome and pyroptosis, but Hadha knockdown eliminated the effect. aldehyde dehydrogenase inhibited the translocation of Histone deacetylase 3, protected ac-HADHA from deacetylation, and significantly reduced the accumulation of toxic aldehyde, and inhibited mROS and ox-mtDNA, thereby avoided NOD-like receptor protein 3 inflammasome activation and pyroptosis. This study provided a novel mechanism of myocardial pyroptosis through mitochondrial Histone deacetylase 3/HADHA- NOD-like receptor protein 3 inflammasome pathway and demonstrated a significant role of aldehyde dehydrogenase as a therapeutic target for myocardial pyroptosis in sepsis.

Ferroptosis, pyroptosis and necroptosis in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is an acute and uncontrolled pulmonary inflammation caused by various insults. Cell death is a critical mechanism in the pathogenesis of ARDS. Ferroptosis, a novel form of cell death defined as iron-mediated lipid peroxidation, has been shown to play a role in the pathogenesis of ARDS. Additionally, pyroptosis and necroptosis are also involved in the pathophysiological process of ARDS. The crosstalk among ferroptosis, pyroptosis, and necroptosis is getting increasing attention. Therefore, this review will mainly summarize the molecular mechanisms and central pathophysiological role of ferroptosis in ARDS. We will also discuss our understanding of pyroptosis and necroptosis as they pertain to the pathogenesis of ARDS. Furthermore, we also describe the pathological processes that engage crosstalk among ferroptosis, pyroptosis, and necroptosis. We consider that individual pathways of ferroptosis, pyroptosis, and necroptosis are highly interconnected and can compensate for one another to promote cell death.

Autophagy-Dependent Ferroptosis in Cancer

Significance: Autophagy is a self-degrading process that determines cell fate in response to various environmental stresses. In contrast to autophagy-mediated cell survival, the signals, mechanisms, and effects of autophagy-dependent cell death remain obscure. The discovery of autophagy-dependent ferroptosis provides a paradigm for understanding the relationship between aberrant degradation pathways and excessive lipid peroxidation in driving regulated cell death. Recent Advances: Ferroptosis was originally described as an autophagy-independent and iron-mediated nonapoptotic cell death. Current studies reveal that the level of intracellular autophagy is positively correlated with ferroptosis sensitivity. Selective autophagic degradation of proteins (e.g., ferritin, SLC40A1, ARNTL, GPX4, and CDH2) or organelles (e.g., lipid droplets or mitochondria) promotes ferroptosis by inducing iron overload and/or lipid peroxidation. Several upstream autophagosome regulators (e.g., TMEM164), downstream autophagy receptors (e.g., HPCAL1), or danger signals (e.g., DCN) are selectively required for ferroptosis-related autophagy, but not for starvation-induced autophagy. The induction of autophagy-dependent ferroptosis is an effective approach to eliminate drug-resistant cancer cells. Critical Issues: How different organelles selectively activate autophagy to modulate ferroptosis sensitivity is not fully understood. Identifying direct protein effectors of ferroptotic cell death remains a challenge. Future Directions: Further understanding of the molecular mechanics and immune consequences of autophagy-dependent ferroptosis is critical for the development of precision antitumor therapies.

Pyroptosis and airway homeostasis regulation

Pyroptosis is a form of cell death associated with inflammation. In the maintenance of airway homeostasis, pyroptosis goes through activation and assembly of Inflammasome. The pyroptosis pathway is mediated by caspase which activates the pore-forming effect of substrate gasdermin family members. It eventually leads to lysis and release of the cell contents and then induces an inflammatory response. In this process, it participates in airway homeostasis regulation by affecting airway immunity, airway epithelial structure and airway microbiota. Therefore, we discussed the correlation between airway immunity, airway epithelial structure, airway microbiota and the mechanism of pyroptosis to describe the role of pyroptosis in airway homeostasis regulation which is of great significance for understanding the occurrence and treatment of airway inflammatory diseases.

Dissection of pyroptosis-related prognostic signature and CASP6-mediated regulation in pancreatic adenocarcinoma: new sights to clinical decision-making

Recent studies have indicated that pyroptosis may participate in the regulation of tumorigenesis and immune microenvironment. However, the role of pyroptosis-related genes (PRGs) in pancreatic adenocarcinoma (PAAD) remains unclear. Through multiple bioinformatics analysis, we constructed a prognostic gene model and competing endogenous RNA network. The correlation between PRGs and prognosis, immune infiltration, immune checkpoints, and tumor mutational burden was analyzed by Kaplan-Meier curve, univariate Cox, multivariate regression, and Spearman's analysis in PAAD patients. The qRT-PCR, Western blotting, CCK-8, Wound healing, and Transwell assay were applied to examine the role of CASP6 in PANC-1 cell. Thirty-one PRGs were upregulated in PAAD. Functional enrichment analysis revealed that the PRGs were mainly involved in pyroptosis, NOD-like receptor signaling pathway, and response to bacteria. We established a novel 4-gene signature related to PRGs for evaluating the prognosis of PAAD patients. Patients with PAAD in the low-risk group had a better prognosis than those in the high-risk group. The nomogram suggested that the 1-, 3-, and 5-years survival probability exhibited robust predictive performance. Significant correlation was observed between prognostic PRGs and immune infiltration, immune checkpoints, and tumor mutational burden. We first identified the potential competing endogenous RNA regulatory axis in PAAD: lncRNA PVT1/hsa-miR-16-5p/CASP6/CASP8. Moreover, knockdown of CASP6 dramatically inhibited the proliferation, migration, and invasion ability of PANC-1 cell in vitro. In conclusion, CASP6 could be a potential biomarker, promoting the occurrence and progression in PAAD. The lncRNA PVT1/hsa-miR-16-5p/CASP6/CASP8 regulatory axis plays an vital role in regulating the anti-tumor immune responses for PAAD.

Ferroptosis in life: To be or not to be

Ferroptosis is a novel type of programmed cell death, characterized by a dysregulated iron metabolism and accumulation of lipid peroxides. It features the alteration of mitochondria and aberrant accumulation of excessive iron as well as loss of the cysteine-glutathione-GPX4 axis. Eventually, the accumulated lipid peroxides result in lethal damage to the cells. Ferroptosis is induced by the overloading of iron and the accumulation of ROS and can be inhibited by the activation of the GPX4 pathway, FS1-CoQ10 pathway, GCH1-BH4 pathway, and the DHODH pathway, it is also regulated by the oncogenes and tumor suppressors. Ferroptosis involves various physiological and pathological processes, and increasing evidence indicates that ferroptosis play a critical role in cancers and other diseases. It inhibits the proliferation of malignant cells in various types of cancers and inducing ferroptosis may become a new method of cancer treatment. Many inhibitors targeting the key factors of ferroptosis such as SLC7A11, GPX4, and iron overload have been developed. The application of ferroptosis is mainly divided into two directions, i.e. to avoid ferroptosis in healthy cells and selectively induce ferroptosis in cancers. In this review, we provide a critical analysis of the concept, and regulation pathways of ferroptosis and explored its roles in various diseases, we also summarized the compounds targeting ferroptosis, aiming to promote the speed of clinical use of ferroptosis induction in cancer treatment.

GPX4 utilization by selenium is required to alleviate cadmium-induced ferroptosis and pyroptosis in sheep kidney

Cadmium (Cd), a persistent and harmful heavy metal in the environment, can accumulate in the kidneys and cause nephrotoxicity. Selenium (Se) is a beneficial natural element that alleviates the toxicity of Cd. To ascertain the relationship between the protective mechanism of Se against Cd nephrotoxicity and ferroptosis and pyroptosis, we randomly divided 48 sheep into four groups and treated them with Cd chloride and/or sodium selenite for 50 days. The data confirmed that Cd apparently resulted in impaired kidney histology and function, depletion of GSH and nicotinamide adenine dinucleotide phosphate contents and CAT and SOD activities, elevation of MDA level, as well as the reduction in selenoprotein mRNA (GPX1, GPX4, TXNRD1, SELP) levels and GPX4 protein level and immunofluorescence intensity. Meanwhile, Cd induced ferroptosis by causing iron overload, up-regulating PTGS2, NCOA4, TFR1, and LC3B mRNA levels and PTGS2 and LC3B-II/LC3B-I protein levels, reducing SLC7A11 and FTH1 mRNA and protein levels, and enhancing the immunofluorescence co-localization of FTH1/LC3B. Moreover, it was also found that Cd triggered pyroptosis, which was evidenced by the increase of NLRP3 immunohistochemical positive signal, GSDMD-N immunofluorescence intensity, IL-1β and IL-18 release and the levels of pyroptosis-related mRNA (NLRP3, ASC, Caspase-1, GSDMD, IL-1β and IL-18) and proteins (NLRP3, Caspase-1p20, GSDMD-N, IL-1β and IL-18). Notably, Se increased the expression level of GPX4 and the transcription factors TFAP2c and SP1, and ameliorated Cd-induced changes in aforementioned factors. In conclusion, GPX4 utilization by Se might be required to alleviate Cd-induced ferroptosis and pyroptosis in sheep kidney.

Tetrahedral framework nucleic acid nanomaterials reduce the inflammatory damage in sepsis by inhibiting pyroptosis

Sepsis is a highly lethal condition and is caused by the dysregulation of the body's immune response to infection. Indeed, sepsis remains the leading cause of death in severely ill patients, and currently, no effective treatment is available. Pyroptosis, which is mainly activated by cytoplasmic danger signals and eventually promote the release of the pro-inflammatory factors, is a newly discovered programmed cell death procedure that clears infected cells while simultaneously triggering an inflammatory response. Increasing evidence indicates that pyroptosis participates in the development of sepsis. As a novel DNA nanomaterial, tetrahedral framework nucleic acids (tFNAs) characterized by its unique spatial structure, possess an excellent biosafety profile and can quickly enter the cell to impart anti-inflammatory and anti-oxidation effects. In this study, the roles of tFNAs in the in vitro model of macrophage cell pyroptosis and in the in vivo model of septic mice were examined, and it was found that tFNAs could mitigate organ inflammatory damage in septic mice, wherein they reduced inflammatory factor levels by inhibiting pyroptosis. These results provide possible new strategies for the future treatment of sepsis.

Leptospira interrogans Prevents Macrophage Cell Death and Pyroptotic IL-1β Release through Its Atypical Lipopolysaccharide

Leptospira interrogans are bacteria that can infect all vertebrates and are responsible for leptospirosis, a neglected zoonosis. Some hosts, such as humans, are susceptible to the disease, whereas mice are resistant and get chronically colonized. Although leptospires escape recognition by some immune receptors, they activate the NOD-like receptor pyrin 3-inflammasome and trigger IL-1β secretion. Classically, IL-1β secretion is associated with lytic inflammatory cell death called pyroptosis, resulting from cytosolic LPS binding to inflammatory caspases, such as caspase 11. Interestingly, we showed that L. interrogans and Leptospira biflexa do not trigger cell death in either murine, human, hamster, or bovine macrophages, escaping both pyroptosis and apoptosis. We showed, in murine cells, that the mild IL-1β secretion induced by leptospires occurred through nonlytic caspase 8-dependent gasdermin D pore formation and not through activation of caspase 11/noncanonical inflammasome. Strikingly, we demonstrated a potent antagonistic effect of pathogenic L. interrogans and their atypical LPS on spontaneous and Escherichia coli LPS-induced cell death. Indeed, LPS of L. interrogans efficiently prevents caspase 11 dimerization and subsequent massive gasdermin D cleavage. Finally, we showed that pyroptosis escape by leptospires prevents massive IL-1β release, and we consistently found no major role of IL-1R in controlling experimental leptospirosis in vivo. Overall, to our knowledge, our findings described a novel mechanism by which leptospires dampen inflammation, thus potentially contributing to their stealthiness.

Disruption of Zinc Homeostasis by a Novel Platinum(IV)-Terthiophene Complex for Antitumor Immunity

Zinc homeostatic medicine is of great potential for cancer chemo-immunotherapy; however, there are few reports on antitumor compounds that can trigger Zn²⁺ -mediated immune responses. In this work, we developed a novel cyclometalated Pt^IV -terthiophene complex, Pt3, that not only induces DNA damage and cellular metabolism dysregulation, but also disrupts zinc homeostasis as indicated by the abnormal transcriptional level of zinc regulatory proteins, excess accumulation of Zn²⁺ in cytoplasm, and down-regulation of metallothioneins (MTs), which further caused redox imbalance. The simultaneous disruption of zinc and redox homeostasis in response to Pt3 treatment activated gasdermin-D mediated pyroptosis accompanied by cytoskeleton remodeling, thus releasing pro-inflammatory cytokines to promote dendritic cell (DC) maturation and T cell tumor-infiltration, eventually eliminating both primary and distant tumors in vivo. As far as we know, this is the first metal complex that can regulate zinc homeostasis to activate antitumor immunity.

The redox protein HMGB1 in cell death and cancer

SIGNIFICANCE

As a redox-sensitive protein, high-mobility group box 1 (HMGB1) is implicated in regulating stress responses to oxidative damage and cell death, which are closely related to the pathology of inflammatory diseases, including cancer.

RECENT ADVANCES

HMGB1 is a non-histone nuclear protein that acts as a DNA chaperone to control chromosomal structure and function. HMGB1 can also be released into the extracellular space and function as a damage-associated molecular pattern protein during cell death, including during apoptosis, necrosis, necroptosis, pyroptosis, ferroptosis, alkaliptosis, and cuproptosis. Once released, HMGB1 binds to membrane receptors to shape immune and metabolic responses. In addition to subcellular localization, the function and activity of HMGB1 also depends on its redox state and protein posttranslational modifications. Abnormal HMGB1 plays a dual role in tumorigenesis and anticancer therapy (e.g., chemotherapy, radiation therapy, and immunotherapy) depending on tumor types and stages.

CRITICAL ISSUES

A comprehensive understanding of the role of HMGB1 in cellular redox homeostasis is important for deciphering normal cellular functions and pathological manifestations. In this review, we discuss compartmental-defined roles of HMGB1 in regulating cell death and cancer. Understanding these advances may help us develop potential HMGB1-targeting drugs or approaches to treat oxidative stress-related diseases or pathological conditions.

FUTURE DIRECTIONS

Further studies are required to dissect the mechanism by which HMGB1 maintains redox homeostasis under different stress conditions. A multidisciplinary effort is also required to evaluate the potential applications of precisely targeting the HMGB1 pathway in human health and disease.

Caspase-11 promotes high-fat diet-induced NAFLD by increasing glycolysis, OXPHOS, and pyroptosis in macrophages

Introduction

Non-alcoholic fatty liver disease (NAFLD) has a global prevalence of 25% of the population and is a leading cause of cirrhosis and hepatocellular carcinoma. NAFLD ranges from simple steatosis (non-alcoholic fatty liver) to non-alcoholic steatohepatitis (NASH). Hepatic macrophages, specifically Kupffer cells (KCs) and monocyte-derived macrophages, act as key players in the progression of NAFLD. Caspases are a family of endoproteases that provide critical connections to cell regulatory networks that sense disease risk factors, control inflammation, and mediate inflammatory cell death (pyroptosis). Caspase-11 can cleave gasdermin D (GSDMD) to induce pyroptosis and specifically defends against bacterial pathogens that invade the cytosol. However, it's still unknown whether high fat diet (HFD)-facilitated gut microbiota-generated cytoplasmic lipopolysaccharides (LPS) activate caspase-11 and promote NAFLD.

Methods

To examine this hypothesis, we performed liver pathological analysis, RNA-seq, FACS, Western blots, Seahorse mitochondrial stress analyses of macrophages and bone marrow transplantation on HFD-induced NAFLD in WT and Casp11-/- mice.

Results and Discussion

Our results showed that 1) HFD increases body wight, liver wight, plasma cholesterol levels, liver fat deposition, and NAFLD activity score (NAS score) in wild-type (WT) mice; 2) HFD increases the expression of caspase-11, GSDMD, interleukin-1β, and guanylate-binding proteins in WT mice; 3) Caspase-11 deficiency decreases fat liver deposition and NAS score; 4) Caspase-11 deficiency decreases bone marrow monocyte-derived macrophage (MDM) pyroptosis (inflammatory cell death) and inflammatory monocyte (IM) surface GSDMD expression; 5) Caspase-11 deficiency re-programs liver transcriptomes and reduces HFD-induced NAFLD; 6) Caspase-11 deficiency decreases extracellular acidification rates (glycolysis) and oxidative phosphorylation (OXPHOS) in inflammatory fatty acid palmitic acid-stimulated macrophages, indicating that caspase-11 significantly contributes to maintain dual fuel bioenergetics-glycolysis and OXPHOS for promoting pyroptosis in macrophages. These results provide novel insights on the roles of the caspase-11-GSDMD pathway in promoting hepatic macrophage inflammation and pyroptosis and novel targets for future therapeutic interventions involving the transition of NAFLD to NASH, hyperlipidemia, type II diabetes, metabolic syndrome, metabolically healthy obesity, atherosclerotic cardiovascular diseases, autoimmune diseases, liver transplantation, and hepatic cancers.

Programmed cell death and lipid metabolism of macrophages in NAFLD

Non-alcoholic fatty liver disease (NAFLD) has now become the leading chronic liver disease worldwide with lifestyle changes. This may lead to NAFLD becoming the leading cause of end-stage liver disease in the future. To date, there are still no effective therapeutic drugs for NAFLD. An in-depth exploration of the pathogenesis of NAFLD can help to provide a basis for new therapeutic agents or strategies. As the most important immune cells of the liver, macrophages play an important role in the occurrence and development of liver inflammation and are expected to become effective targets for NAFLD treatment. Programmed cell death (PCD) of macrophages plays a regulatory role in phenotypic transformation, and there is also a certain connection between different types of PCD. However, how PCD regulates macrophage polarization has still not been systematically elucidated. Based on the role of lipid metabolic reprogramming in macrophage polarization, PCD may alter the phenotype by regulating lipid metabolism. We reviewed the effects of macrophages on inflammation in NAFLD and changes in their lipid metabolism, as well as the relationship between different types of PCD and lipid metabolism in macrophages. Furthermore, interactions between different types of PCD and potential therapeutic agents targeting of macrophages PCD are also explored.

Copper-dependent autophagic degradation of GPX4 drives ferroptosis

Ferroptosis is a type of iron-dependent regulated cell death characterized by unrestricted lipid peroxidation and membrane damage. Although GPX4 (glutathione peroxidase 4) plays a master role in blocking ferroptosis by eliminating phospholipid hydroperoxides, the regulation of GPX4 remains poorly understood. Here, we report an unexpected role for copper in promoting ferroptotic cell death, but not cuproptosis, by inducing macroautophagic/autophagic degradation of GPX4. Copper chelators reduce ferroptosis sensitivity but do not inhibit other types of cell death, such as apoptosis, necroptosis, and alkaliptosis. Conversely, exogenous copper increases GPX4 ubiquitination and the formation of GPX4 aggregates by directly binding to GPX4 protein cysteines C107 and C148. TAX1BP1 (Tax1 binding protein 1) then acts as an autophagic receptor for GPX4 degradation and subsequent ferroptosis in response to copper stress. Consequently, copper enhances ferroptosis-mediated tumor suppression in a mouse model of pancreatic cancer tumor, whereas copper chelators attenuate experimental acute pancreatitis associated with ferroptosis. Taken together, these findings provide new insights into the link between metal stress and autophagy-dependent cell death.Abbreviations: CALCOCO2, calcium binding and coiled-coil domain 2; GPX4, glutathione peroxidase 4; MAP1LC3A/B, microtubule associated protein 1 light chain 3 alpha/beta; MPO, myeloperoxidase; NCOA4, nuclear receptor coactivator 4; OPTN, optineurin; PDAC, pancreatic ductal adenocarcinoma; RIPK1, receptor interacting serine/threonine kinase 1; ROS, reactive oxygen species; SLC40A1, solute carrier family 40 member 1; SQSTM1, sequestosome 1; TAX1BP1, Tax1 binding protein 1; TEPA, tetraethylenepentamine; TM, tetrathiomolybdate.

Dual-Site Chemosensor for Monitoring ·OH-Cysteine Redox in Cells and In Vivo

The reaction between hydroxyl radical (^·OH) and cysteine (Cys) plays an important role in the redox balance of living cells. A deeper insight into this intracellular reaction modulation and process is necessary and draws great interest. A highly effective technique consists of the real-time visualization of the two bioactive species and the perception of their respective changes by using a fluorescent probe. In this study, a dual-site chemosensor SPI based on phenothiazine-cyanine was developed, which realized quantitative detection and real-time imaging of ^·OH and Cys at their own fluorescence channels (^·OH: λ_ex = 485 nm, λ_em = 608 nm; Cys: λ_ex = 426 nm, λ_em = 538 nm) without spectral crosstalk. The fluorescent sensor showed excellent anti-interference and selectivity for common biological substances, apart from the successful imaging of exogenous and endogenous ^·OH and Cys. We further visualized the redox dynamic reaction and explored the correlation of ^·OH and Cys generated by different inhibitors (sulfasalazine and (1S, 3R)-RSL3). Notably, the chemosensor also possesses the capacity to clearly monitor ^·OH and Cys in living mice and zebrafish. This study reports on the first chemosensor to investigate the process of intracellular redox modulation and control between ^·OH and Cys, which show potential to further explore some metabolic and physiological mechanisms.

The Therapeutic Potential of Pyroptosis in Melanoma

Pyroptosis is a programmed cell death characterized by the rupture of the plasma membranes and release of cellular content leading to inflammatory reaction. Four cellular mechanisms inducing pyroptosis have been reported thus far, including the (i) caspase 1-mediated canonical, (ii) caspase 4/5/11-mediated non-canonical, (iii) caspase 3/8-mediated and (iv) caspase-independent pathways. Although discovered as a defense mechanism protecting cells from infections of intracellular pathogens, pyroptosis plays roles in tumor initiation, progression and metastasis of tumors, as well as in treatment response to antitumor drugs and, consequently, patient outcome. Pyroptosis induction following antitumor therapies has been reported in several tumor types, including lung, colorectal and gastric cancer, hepatocellular carcinoma and melanoma. This review provides an overview of the cellular pathways of pyroptosis and discusses the therapeutic potential of pyroptosis induction in cancer, particularly in melanoma.

Ferroptosis: Mechanism and connections with cutaneous diseases

Ferroptosis is a recognized novel form of programmed cell death pathway, featuring abnormalities in iron metabolism, SystemXc^-/glutathione axis, and lipid peroxidation regulation. A variety of ferroptosis inducers can influence glutathione peroxidase directly or indirectly via diverse pathways, leading to decreased antioxidant capacity, accumulated cellular lipid peroxides, and finally inducing ferroptosis. To date, mounting studies confirm the association of ferroptosis with various cutaneous diseases, including skin homeostasis, neoplastic diseases, infectious diseases, genetic skin disease, inflammatory skin diseases, and autoimmune diseases. There are shared characteristics regarding ferroptosis and various cutaneous diseases in terms of pathophysiological mechanisms, such as oxidative stress associated with iron metabolism disorder and accumulated lipid peroxides. Therefore, we summarize the current knowledge regarding the mechanisms involved in the regulation of ferroptosis for further discussion of its role in the pathogenesis and prognosis of skin diseases. Gaining insight into the underlying mechanisms of ferroptosis and the associated dermatological disorders could illuminate the pathogenesis and treatments of different cutaneous diseases.

Ferroptosis triggers airway inflammation in asthma

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

Flow Cytometric Analysis of Regulated Cell Death

Cell death is a crucial and fundamental process in the biology of all living organisms and plays an essential role in developmental, cellular, and molecular biology. With a deeper understanding of the mechanisms of different types of cell death, quantitative experiments are becoming increasingly necessary to analyze the dynamic changes and coordinate physiological processes. Flow cytometry is the most widely used method for detecting and quantifying cell processes in mammalian cells, providing a comprehensive and high-throughput approach, even at the single-cell level. This chapter provides a brief overview of guidelines for performing flow cytometry in the detection of regulated cell deaths, including apoptosis, autophagy, ferroptosis, pyroptosis, and immunogenic cell death.

Protectin Conjugates in Tissue Regeneration 1 Inhibits Macrophage Pyroptosis by Restricting NLRP3 Inflammasome Assembly to Mitigate Sepsis via the cAMP-PKA Pathway

Protectin conjugates in tissue regeneration 1 (PCTR1) is a novel anti-inflammatory and proresolving lipid mediator biosynthesized from docosahexaenoic acid. Excessive activation of NLR family pyrin domain containing 3 (NLRP3) inflammasome and consequent pyroptosis are involved in diverse inflammatory diseases. However, how PCTR1 affects NLRP3 inflammasome activation and pyroptosis are still unclear. Here, we demonstrated that PCTR1 inhibited NLRP3 inflammasome activation and pyroptosis. These results show that PCTR1 dose-dependently inhibited gasdermin D cleavage in lipopolysaccharide (LPS)-primed murine primary macrophages upon nigericin stimulation. Additionally, PCTR1 treatment after LPS priming inhibited caspase-1 activation and subsequent mature interleukin-1β release independent of the nuclear factor-kappa B pathway. PCTR1 exerted its inhibitory effects by blocking NLRP3-apoptosis-associated speck-like protein containing a CARD (ASC) interaction and ASC oligomerization, thereby restricting NLRP3 inflammasome assembly. However, the inhibitory effect of PCTR1 could be reversed by KH7 and H89, which are the inhibitors of the cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling pathway. Moreover, PCTR1 treatment alleviated lung tissue damage and improved mouse survival in LPS-induced sepsis. Our study unveils the molecular mechanism of negative regulation of NLRP3 inflammasome activation and pyroptosis by a novel lipid mediator and suggests that PCTR1 may serve as a potential treatment option for NLRP3-inflammasome driven diseases.

Inhibition of PFKFB Preserves Intestinal Barrier Function in Sepsis by Inhibiting NLRP3/GSDMD

Intestinal barrier dysfunction is associated with the occurrence and development of sepsis. Further, aerobic glycolysis plays an essential role in inflammation and cell death. This study is aimed at investigating the protective effect and mechanism of PFKFB3 inhibition on intestinal barrier dysfunction in sepsis mice. Sepsis mouse models were established by cecal ligation and puncture (CLP) in wild-type mice and Gsdmd^-/- mice. The results showed that the expression of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) in the small intestines was significantly upregulated in sepsis. 3-(3-Pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO), the specific inhibitor of PFKFB3, and Gsdmd gene knockout significantly inhibited the inflammatory response and cell death caused by sepsis, thus alleviating intestinal damage and barrier dysfunction. 3PO was also shown to significantly inhibit oxidative stress and NLRP3/caspase-1/GSDMD-dependent cell pyroptosis in the small intestines. The in vitro studies revealed that 3PO reduced NLRP3/caspase-1/GSDMD-dependent cell pyroptosis by inhibiting ROS. Taken together, our results suggest that PFKFB3 is involved in inflammation, oxidative stress, and pyroptosis during sepsis and enhances intestinal damage, which may provide important clues about the potential targets to be exploited in this highly lethal disease.

Prognosis and immune features of pyroptosis-related RNA patterns in low-grade glioma

Purpose

Low-grade gliomas (LGG), which are malignant primary brain tumors, are more prevalent in young adults. Pyroptosis, an inflammatory form of programmed cell death, has been shown in recent years to be directly associated with tumor growth and tumor microenvironment (TME). However, the correlation between LGG and pyroptosis remained to be explored. In this research, we explored pyroptosis-related gene expression patterns and their prognostic significance based on transcriptome profiles and clinical data in LGG.

Methods

We identified 31 pyroptosis-related genes differentially expressed at the mRNA level between the data of LGG patients from TCGA and the data of normal brain tissues from GTEx. Univariate Cox regression analysis was used to screen 16 differentially expressed genes (DEGs) based on survival data. Next, the prognostic model was established using LASSO Cox regression, which divided LGG patients into high- and low- risk subgroups and showed an independent prognostic value for overall survival (OS) combined with clinical factors in the CGGA test cohort. Pyroptosis and immune cells were correlated through the CIBERSORT R package and the TIMER database.

Results

Based on the analyses of 523 LGG and 1152 normal tissues, nine significant differential genes were identified. The AUC remained at about 0.74 when combined with the risk score and clinical factors. Enrichment analyses revealed that DEGs were mainly enriched in cytokine-cytokine receptor interactions, immune response and chemokine signaling pathways. Immune cell enrichment analysis demonstrated that scores for most immune cell types differed significantly between the high-and low-risk groups, and further infiltrating analysis showed obvious differences between these two risk subgroups.

Conclusion

Pyroptosis-related genes play a pivotal role in LGG and are associated with tumor immunity, which may be beneficial to the prognosis and immunotherapy of LGG.

The Emerging Role of Deubiquitinases in Cell Death

Regulated cell death (RCD) is a signal-controlled process that not only eliminates infected, damaged, or aged cells but is also implicated in a variety of pathological conditions. The process of RCD is regulated by intracellular proteins that undergo varying levels of post-translational modifications, including mono- or polyubiquitination. Functionally, ubiquitination can affect protein abundance, localization, and activity. Like other post-translational modifications, ubiquitination is a dynamic and reversible process mediated by deubiquitinases, a large class of proteases that cleave ubiquitin from proteins and other substrates. The balance between ubiquitination and deubiquitination machinery determines cell fate under stressful conditions. Here, we review the latest advances in our understanding of the role of deubiquitinases in regulating the main types of RCD, including apoptosis, necroptosis, pyroptosis, and ferroptosis. This knowledge may contribute to identifying new protein degradation-related prognostic markers and therapeutic targets for human disease.

Ferroptosis in heart failure

With its complicated pathobiology and pathophysiology, heart failure (HF) remains an increasingly prevalent epidemic that threatens global human health. Ferroptosis is a form of regulated cell death characterized by the iron-dependent lethal accumulation of lipid peroxides in the membrane system and is different from other types of cell death such as apoptosis and necrosis. Mounting evidence supports the claim that ferroptosis is mainly regulated by several biological pathways including iron handling, redox homeostasis, and lipid metabolism. Recently, ferroptosis has been identified to play an important role in HF induced by different stimuli such as myocardial infarction, myocardial ischemia reperfusion, chemotherapy, and others. Thus, it is of great significance to deeply explore the role of ferroptosis in HF, which might be a prerequisite to precise drug targets and novel therapeutic strategies based on ferroptosis-related medicine. Here, we review current knowledge on the link between ferroptosis and HF, followed by critical perspectives on the development and progression of ferroptotic signals and cardiac remodeling in HF.

Emerging roles of ferroptosis in infectious diseases

In living organisms, lipid peroxidation is a continuously occurring cellular process and therefore involved in various physiological and pathological contexts. Among the broad variety of lipids, polyunsaturated fatty acids (PUFA) constitute a major target of oxygenation either when released as mediators by phospholipases or when present in membranous phospholipids. The last decade has seen the characterization of an iron- and lipid peroxidation-dependent cell necrosis, namely, ferroptosis, that involves the accumulation of peroxidized PUFA-containing phospholipids. Further studies could link ferroptosis in a very large body of (physio)-pathological processes, including cancer, neurodegenerative, and metabolic diseases. In this review, we mostly focus on the emerging involvement of lipid peroxidation-driven ferroptosis in infectious diseases, and the immune consequences. We also discuss the putative ability of microbial virulence factors to exploit or to dampen ferroptosis regulatory pathways to their own benefit.

HSP70 alleviates sepsis-induced cardiomyopathy by attenuating mitochondrial dysfunction-initiated NLRP3 inflammasome-mediated pyroptosis in cardiomyocytes

BACKGROUND

Sepsis-induced cardiomyopathy (SIC) is an identified serious complication of sepsis that is associated with adverse outcomes and high mortality. Heat shock proteins (HSPs) have been implicated in suppressing septic inflammation. The aim of this study was to investigate whether HSP70 can attenuate cellular mitochondrial dysfunction, exuberated inflammation and inflammasome-mediated pyroptosis for SIC intervention.

METHODS

Mice with cecal ligation plus perforation (CLP) and lipopolysaccharide (LPS)-treated H9C2 cardiomyocytes were used as models of SIC. The mouse survival rate, gross profile, cardiac function, pathological changes and mitochondrial function were observed by photography, echocardiography, hematoxylin-eosin staining and transmission electron microscopy. In addition, cell proliferation and the levels of cardiac troponin I (cTnI), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were determined by Cell Counting Kit-8, crystal violet staining and enzyme-linked immunosorbent assay. Moreover, mitochondrial membrane potential was assessed by immunofluorescence staining, and dynamin-related protein 1 and pyroptosis-related molecules [nucleotide-binding domain, leucine-rich-repeat containing family pyrin domain-containing 3 (NLRP3), caspase-1, gasdermin-D (GSDMD), gasdermin-D N-terminal (GSDMD-N)] were measured by western blotting, immunoprecipitation and immunoblotting. Finally, hsp70.1 knockout mice with CLP were used to verify the effects of HSP70 on SIC and the underlying mechanism.

RESULTS

Models of SIC were successfully established, as reduced consciousness and activity with liparotrichia in CLP mice were observed, and the survival rate and cardiac ejection fraction (EF) were decreased; conversely, the levels of cTnI, TNF-α and IL-1β and myocardial tissue damage were increased in CLP mice. In addition, LPS stimulation resulted in a reduction in cell viability, mitochondrial destabilization and activation of NLRP3-mediated pyroptosis molecules in vitro. HSP70 treatment improved myocardial tissue damage, survival rate and cardiac dysfunction caused by CLP. Additionally, HSP70 intervention reversed LPS-induced mitochondrial destabilization, inhibited activation of the NLRP3 inflammasome, caspase-1, GSDMD and GSDMD-N, and decreased pyroptosis. Finally, knockout of hsp70.1 mice with CLP aggravated cardiac dysfunction and upregulated NLRP3 inflammasome activity, and exogenous HSP70 significantly rescued these changes. It was further confirmed that HSP70 plays a protective role in SIC by attenuating mitochondrial dysfunction and inactivating pyroptotic molecules.

CONCLUSIONS

Our study demonstrated that mitochondrial destabilization and NLRP3 inflammasome activation-mediated pyroptosis are attributed to SIC. Interestingly, HSP70 ameliorates sepsis-induced myocardial dysfunction by improving mitochondrial dysfunction and inhibiting the activation of NLRP3 inflammasome-mediated pyroptosis, and such a result may provide approaches for novel therapies for SIC.

GPX4 regulates cellular necrosis and host resistance in Mycobacterium tuberculosis infection

Cellular necrosis during Mycobacterium tuberculosis (Mtb) infection promotes both immunopathology and bacterial dissemination. Glutathione peroxidase-4 (Gpx4) is an enzyme that plays a critical role in preventing iron-dependent lipid peroxidation-mediated cell death (ferroptosis), a process previously implicated in the necrotic pathology seen in Mtb-infected mice. Here, we document altered GPX4 expression, glutathione levels, and lipid peroxidation in patients with active tuberculosis and assess the role of this pathway in mice genetically deficient in or overexpressing Gpx4. We found that Gpx4-deficient mice infected with Mtb display substantially increased lung necrosis and bacterial burdens, while transgenic mice overexpressing the enzyme show decreased bacterial loads and necrosis. Moreover, Gpx4-deficient macrophages exhibited enhanced necrosis upon Mtb infection in vitro, an outcome suppressed by the lipid peroxidation inhibitor, ferrostatin-1. These findings provide support for the role of ferroptosis in Mtb-induced necrosis and implicate the Gpx4/GSH axis as a target for host-directed therapy of tuberculosis.

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.

Bioactive Iridium Nanoclusters with Glutathione Depletion Ability for Enhanced Sonodynamic-Triggered Ferroptosis-Like Cancer Cell Death

Ferroptosis is a regulated form of necrotic cell death that involves the accumulation of lipid peroxide (LPO) species in an iron- and reactive oxygen species (ROS)-dependent manner. Previous investigations have reported that ferroptosis-based cancer therapy can overcome the limitations of traditional therapeutics targeting the apoptosis pathway. However, it is still challenging to enhance the antitumor efficacy of ferroptosis due to intrinsic cellular regulation. In this study, a ferroptosis-inducing agent, i.e., chlorin e6 (Ce6)-conjugated human serum albumin-iridium oxide (HSA-Ce6-IrO₂ , HCIr) nanoclusters, is developed to achieve sonodynamic therapy (SDT)-triggered ferroptosis-like cancer cell death. The sonosensitizing role of both Ce6 and IrO₂ within the HCIr nanoclusters exhibits highly efficient ¹ O₂ generation capacity upon ultrasound stimulation, which promotes the accumulation of LPO and subsequently induces ferroptosis. Meanwhile, the HCIr can deplete glutathione (GSH) by accelerating Ir (IV)-Ir (III) transition, which further suppresses the activity of glutathione peroxidase 4 (GPX4) to enhance the ferroptosis efficacy. Through in vitro and in vivo experiments, it is demonstrated that HCIr possesses tremendous capacity to reduce the intracellular GSH content, which enhances SDT-triggered ferroptosis-like cancer cell death. Thus, an iridium-nanoclusters-based ferroptosis-inducing agent is developed, providing a promising strategy for inducing ferroptosis-like cancer cell death.

Selenocompounds and Sepsis-Redox Bypass Hypothesis: Part B-Selenocompounds in the Management of Early Sepsis

Significance: Endothelial barrier damage, which is in part caused by excess production of reactive oxygen, halogen and nitrogen species (ROHNS), especially peroxynitrite (ONOO^-), is a major event in early sepsis and, with leukocyte hyperactivation, part of the generalized dysregulated immune response to infection, which may even become a complex maladaptive state. Selenoenzymes have major antioxidant functions. Their synthesis is related to the need to limit deleterious oxidant redox cycling by small selenocompounds, which may be of therapeutic cytotoxic interest. Plasma selenoprotein-P is crucial for selenium transport from the liver to the tissues and for antioxidant endothelial protection, especially against ONOO^-. Above micromolar concentrations, sodium selenite (Na₂SeO₃) becomes cytotoxic, with a lower cytotoxicity threshold in activated cells, which has led to cancer research. Recent Advances: Plasma selenium (<2% of total body selenium) is mainly contained in selenoprotein-P, and concentrations decrease rapidly in the early phase of sepsis, because of increased selenoprotein-P binding and downregulation of hepatic synthesis and excretion. At low concentrations, Na₂SeO₃ acts as a selenium donor, favoring selenoprotein-P synthesis in physiology, but probably not in the acute phase of sepsis. Critical Issues: The cytotoxic effects of Na₂SeO₃ against hyperactivated leukocytes, especially the most immature forms that liberate ROHNS, may be beneficial, but they may also be harmful for activated endothelial cells. Endothelial protection against ROHNS by selenoprotein-P may reduce Na₂SeO₃ toxicity, which is increased in sepsis. Future Direction: The combination of selenoprotein-P for endothelial protection and the cytotoxic effects of Na₂SeO₃ against hyperactivated leukocytes may be a promising intervention for early sepsis. Antioxid. Redox Signal. 37, 998-1029.

Targeting the PANoptosome with 3,4-Methylenedioxy-β-Nitrostyrene, Reduces PANoptosis and Protects the Kidney against Renal İschemia-Reperfusion Injury

OBJECTIVES

The objectives of this study were a) to investigate the effect of targeting the PANoptosome with 3,4-methylenedioxy-β-nitrostyrene (MNS) on PANoptosis in the Renal ischemia-reperfussion (RIR) model b) to investigate the kidney protective effect of MNS toward RIR injury.

METHODS

Thirty-two rats were divided into four groups randomly. The groups were assigned as Control, Sham, DMSO (dimethyl sulfoxide) and MNS groups. The rats in the MNS group were intraperitoneally given 20 mg/kg of MNS 30 minutes before reperfusion. 2% DMSO solvent that dissolves MNS were given to the rats in DMSO group. Left nephrectomy was performed on the rats under anesthesia at the 6th hour after reperfusion. Glutathione peroxidase (GPx), malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD) and 8-Okso-2'-deoksiguanozin (8-OHdG) levels were measured. Immunohistochemical analysis, electron microscopic and histological examinations were carried out in the tissues.

RESULTS

Total tubular injury score was lower in the MNS group (p < 0.001). Caspase-3, Gasdermin D and MLK (Mixed Lineage Kinase Domain Like Pseudokinase) expressions were considerably decreased in the MNS group (p < 0.001). Apoptotic index (AI) was found to be low in the MNS group (p < 0.001). CAT and SOD levels were higher in the MNS Group (p = 0.006, p = 0.0004, respectively). GPx, MDA, and 8-OH-dG levels were similar (p > 0.05) in all groups. MNS considerably improved the tissue structure, based on the electron microscopic analysis.

CONCLUSIONS

Our results suggested that MNS administrated before the reperfusion reduces pyroptosis, apoptosis and necroptosis. These findings suggest that MNS significantly protects the kidney against RIR injury by reducing PANoptosis as a result of specific inhibition of Nod-like receptor pyrin domain-containing 3 (NLRP 3), one of the PANoptosome proteins.

A novel signature based on pyroptosis-related genes for predicting prognosis and treatment response in prostate cancer patients

Background: Pyroptosis is a form of programmed cell death accompanied by specific inflammatory and immune responses, and it is closely related to the occurrence and progression of various cancers. However, the roles of pyroptosis-related genes (PRGs) in the prognosis, treatment response, and tumor microenvironment (TME) of prostate cancer (PCa) remain to be investigated. Methods: The mRNA expression data and clinical information of PCa patients were obtained from the Cancer Genome Atlas database (TCGA) and the cBioPortal for Cancer Genomics website, and the 52 PRGs were obtained from the published papers. The univariate, multivariate, and LASSO Cox regression algorithms were used to obtain prognostic hub PRGs. Meanwhile, qRT-PCR was used to validate the expression of hub genes between PCa lines and normal prostate epithelial cell lines. We then constructed and validated a risk model associated with the patient's disease-free survival (DFS). Finally, the relationships between risk score and clinicopathological characteristics, tumor immune microenvironment, and drug treatment response of PCa were systematically analyzed. Results: A prognostic risk model was constructed with 6 hub PRGs (CHMP4C, GSDMB, NOD2, PLCG1, CYCS, GPX4), and patients were divided into high and low-risk groups by median risk score. The risk score was confirmed to be an independent prognostic factor for PCa in both the training and external validation sets. Patients in the high-risk group had a worse prognosis than those in the low-risk group, and they had more increased somatic mutations, higher immune cell infiltration and higher expression of immune checkpoint-related genes. Moreover, they were more sensitive to cell cycle-related chemotherapeutic drugs and might be more responsive to immunotherapy. Conclusion: In our study, pyroptosis played a significant role in the management of the prognosis and tumor microenvironment of PCa. Meanwhile, the established model might help to develop more effective individual treatment strategies.

Molecular mechanisms and roles of pyroptosis in acute lung injury

ABSTRACT

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), which are characterized by excessive inflammation and accompanied by diffuse injury of alveoli, can result in severe respiratory failures. The morbidity and mortality of patients remain high because the major treatments for ALI/ARDS are mainly supportive due to the lack of effective therapies. Numerous studies have demonstrated that the aggravation of coronavirus disease 2019 (COVID-19) leads to severe pneumonia and even ARDS. Pyroptosis, a biological process identified as a type of programed cell death, is mainly triggered by inflammatory caspase activation and is directly meditated by the gasdermin protein family, as well as being associated with the secretion and release of pro-inflammatory cytokines. Clinical and experimental evidence corroborates that pyroptosis of various cells in the lung, such as immune cells and structural cells, may play an important role in the pathogenesis of "cytokine storms" in ALI/ARDS, including those induced by COVID-19. Here, with a focus on ALI/ARDS and COVID-19, we summarized the recent advances in this field and proposed the theory of an inflammatory cascade in pyroptosis to identify new targets and pave the way for new approaches to treat these diseases.