Pyroptosis in neutrophils: Multimodal integration of inflammasome and regulated cell death signaling pathways

Neutrophils in Tissue Injury and Repair: Molecular Mechanisms and Therapeutic Targets

Tissue repair represents a highly intricate and ordered dynamic process, critically reliant on the orchestration of immune cells. Among these, neutrophils, the most abundant leukocytes in the body, emerge as the initial immune responders at injury sites. Traditionally recognized for their antimicrobial functions in innate immunity, neutrophils now garner attention for their indispensable roles in tissue repair. This review delves into their novel functions during the early stages of tissue injury. We elucidate the mechanisms underlying neutrophil recruitment and activation following tissue damage and explore their contributions to vascular network formation. Furthermore, we investigate the pivotal role of neutrophils during the initial phase of repair across different tissue types. Of particular interest is the investigation into how the fate of neutrophils influences overall tissue healing outcomes. By shedding light on these emerging aspects of neutrophil function in tissue repair, this review aims to pave the way for novel strategies and approaches in future organ defect repair, regeneration studies, and advancements in tissue engineering. The insights provided here have the potential to significantly impact the field of tissue repair and regeneration.

Pyroptosis in sepsis-associated acute kidney injury: mechanisms and therapeutic perspectives

Sepsis-associated acute kidney injury (S-AKI) is a severe complication characterized by high morbidity and mortality, driven by multi-organ dysfunction. Recent evidence suggests that pyroptosis, a form of programmed cell death distinct from apoptosis and necrosis, plays a critical role in the pathophysiology of S-AKI. This review examines the mechanisms of pyroptosis, focusing on inflammasome activation (e.g., NLRP3), caspase-mediated processes, and the role of Gasdermin D in renal tubular damage. We also discuss the contributions of inflammatory mediators, oxidative stress, and potential therapeutic strategies targeting pyroptosis, including inflammasome inhibitors, caspase inhibitors, and anti-inflammatory therapies. Lastly, we highlight the clinical implications and challenges in translating these findings into effective treatments, underscoring the need for personalized medicine approaches in managing S-AKI.

Therapeutic potential of quercitrin in intervertebral disc degeneration: Targeting pyroptosis and inflammation

BACKGROUND

Intervertebral disc degeneration (IDD) is the predominant cause of low back pain (LBP), that leads to significant disability and imposes a substantial socioeconomic burden. Despite its prevalence, effective treatment for IDD has yet to be fully established. This study aimed to explore the therapeutic potential of quercitrin (QUE) in IDD development and to elucidate its underlying mechanisms.

METHODS

In vitro, we investigated the effects of QUE on ECM metabolism, inflammatory response and pyroptosis in IL-1β-stimulated nucleus pulposus cells (NPCs), along with the potential mechanisms. In vivo, mice lumbar spinal instability (LSI) was established to determined the impact of QUE on IDD progression.

RESULTS

QUE significantly alleviated inflammation and maintained the ECM homeostasis under IL-1β stimulation in NPCs. Moreover, QUE appeared to inhibit pyroptosis, which was closely related to intense inflammatory response. Notably, the protective effects of QUE were abrogated upon inhibition of TRIM31 activity, indicating that TRIM31 mediated pyroptosis suppression is crucial for the therapeutic effects of QUE.

CONCLUSION

QUE plays an important role in alleviating pyroptosis and inflammation within NPCs, thereby slowing the progression of IDD. Therefore, QUE might emerge as a promising therapeutic candidate for IDD, holding the potential for clinical application in the future.

The roles of neutrophils in cardiovascular diseases

The immune response plays a vital role in the development of cardiovascular diseases (CVDs). As a crucial component of the innate immune system, neutrophils are involved in the initial inflammatory response following cardiovascular injury, thereby inducing subsequent damage and promoting recovery. Neutrophils exert their functional effects in tissues through various mechanisms, including activation and the formation of neutrophil extracellular traps (NETs). Once activated, neutrophils are recruited to the site of injury, where they release inflammatory mediators and cytokines. This study discusses the main mechanisms associated with neutrophil activity and proposes potential new therapeutic targets. In this review, we systematically summarize the diverse phenotypes of neutrophils in disease regulatory mechanisms, different modes of cell death, and focus on the relevance of neutrophils to various CVDs, including atherosclerosis, acute coronary syndrome, myocardial ischemia/reperfusion injury, hypertension, atrial fibrillation, heart failure, and viral myocarditis. Finally, we also emphasize the preclinical/clinical translational significance of neutrophil-targeted strategies.

NETosis Genes and Pathomic Signature: A Novel Prognostic Marker for Ovarian Serous Cystadenocarcinoma

To evaluate the prognostic significance and molecular mechanism of NETosis markers in ovarian serous cystadenocarcinoma (OSC), we constructed a machine learning-based pathomic model utilizing hematoxylin and eosin (H&E) slides. We analyzed 333 patients with OSC from The Cancer Genome Atlas for prognostic-related neutrophil extracellular trap formation (NETosis) genes through bioinformatics analysis. Pathomic features were extracted from 54 cases with complete pathological images, genetic matrices, and clinical information. Two pathomic prognostic models were constructed using support vector machine (SVM) and logistic regression (LR) algorithms. Additionally, we established a predictive scoring system that integrated pathomic scores based on the NETcluster subtypes and clinical signature. We identified four NETosis genes significantly correlated with OSC prognosis, which were functionally associated with immune response, somatic mutations, tumor invasion, and metastasis. Five robust pathomic features were selected for overall survival prediction. The LR and SVM pathomic models demonstrated strong predictive performance for the NETcluster subtype classification through five-fold cross-validation. Time-dependent ROC analysis revealed excellent prognostic capability of the LR pathomic model's score for the overall survival (AUC values of 0.658, 0.761, and 0.735 at 36, 48, and 60 months, respectively), further validated by Kaplan-Meier analysis. The expression levels of NETosis genes greatly affected OSC patients' prognoses. The pathomic analysis of H&E slide pathological images provides an effective approach for predicting both NETcluster subtype and overall survival in OSC patients.

Nano titanium dioxide induces HaCaT cell pyroptosis via regulating the NLRP3/caspase-1/GSDMD pathway

Nano-titanium dioxide (Nano-TiO2) is extensively utilized across various industries and has the capacity to penetrate human tissues through multiple biological barriers. The HaCaT cell line, as one of human immortalized keratinocytes, is usually used as a model for studying skin drug toxicology. The objective was to assess the toxic effects of nano-TiO2 on HaCaT cells and to trigger pyroptosis. We used MTT method to evaluate the effects of three nano-TiO2 particle sizes (15 nm, 30 nm and 80 nm) on cell viability at different concentrations. Subsequently, we used LDH, Hoechst 33342 and propidium iodide (PI) double staining, scanning electron microscopy (SEM), Western blotting (WB) and real-time quantitative polymerase chain reaction (RT-qPCR) to evaluate the effects of different particle sizes on cells at the same concentration. Our findings indicated that HaCaT cell viability diminished with increasing nano-TiO2 concentrations. Moreover, nano-TiO2 increased LDH level in cellular supernatant. Fluorescence double staining, SEM, WB and RT-qPCR showed that nano-TiO2 induced cell membrane damage by activating pyroptosis pathway of NLRP3/caspase-1/GSDMD. These results suggest that nano-TiO2 toxicity in HaCaT cells is influenced by both dose and particle size, and is associated with the induction of pyroptosis. Frequent and large exposures to nano- TiO2 in daily life may cause serious health hazards.

Caspase-1 knockout disrupts pyroptosis and protects photoreceptor cells from photochemical damage

AIM

Retinal photochemical damage (RPD) plays a significant role in the development of various ocular diseases, with Caspase-1 being a key contributor. This study investigates the protective effects of Caspase-1 gene-mediated pyroptosis against RPD.

METHODS

Differentially expressed genes (DEGs) associated with RPD were identified through the analysis of two expression profiles from the GEO database. Correlation analysis was used to pinpoint pyroptosis-related genes (PRGs) linked to RPD. A Caspase-1 knockout 661 W cell line was generated via CRISPR-Cas9 gene editing, and single-cell colonies were screened and purified. Validation of knockout cells was performed through RT-qPCR, gene sequencing, and Western blot analysis. Comparative assays on cell proliferation, intracellular reactive oxygen species (ROS), and cytotoxicity were conducted between wild-type and Caspase-1 knockout cells under light exposure. Further RT-qPCR and Western blot experiments examined changes in the mRNA and protein levels of key pyroptosis pathway components.

RESULTS

Significant alterations in Caspase-1 expression were observed among PRGs. Homozygous Caspase-1 knockout cell lines were confirmed through RT-qPCR, genomic PCR product sequencing, and Western blot analysis. Compared to wild-type 661 W cells, Caspase-1 knockout cells exhibited higher viability and proliferation rates after 24 h of light exposure, alongside reduced LDH release. The expression of downstream pyroptosis factors at both the mRNA and protein levels was markedly decreased in the knockout group.

CONCLUSION

CRISPR/Cas9-mediated Caspase-1 knockout enhanced the resistance of 661 W cells to photochemical damage, suggesting that Caspase-1 may serve as a potential therapeutic target for RPD-related diseases.

Deficiency of hasB accelerated the clearance of Streptococcus equi subsp. Zooepidemicus through gasdermin d-dependent neutrophil extracellular traps

Streptococcus equi subsp. zooepidemicus (S. zooepidemicus, SEZ) is an essential zoonotic bacterial pathogen that can cause various inflammation, such as meningitis, endocarditis, and pneumonia. UDP-glucose dehydrogenase (hasB) is indispensable in synthesizing SEZ virulence factor hyaluronan capsules. Our study investigated the infection of hasB on mice response to SEZ by employing a constructed capsule-deficient mutant strain designated as the ΔhasB strain. This deficiency was associated with a reduced SEZ bacterial load in the mice's blood and peritoneal lavage fluid (PLF) post-infection. Besides, the ΔhasB SEZ strain exhibited a higher propensity for neutrophil infiltration and release of cell-free DNA (cfDNA) in vivo compared to the wild-type (WT) SEZ strain. In vitro experiments further revealed that ΔhasB SEZ more effectively induced the formation of neutrophil extracellular traps (NETs) containing histone 3 (H3), neutrophil elastase (NE), and DNA, than its WT counterpart. Moreover, the release of NETs was determined to be gasdermin D (GSDMD)-dependent during the infection process. Taken together, these findings underscore that the deficiency of the hasB gene in SEZ leads to enhanced GSDMD-dependent NET release from neutrophils, thereby reducing SEZ's capacity to resist NETs-mediated eradication during infection. Our finding paves the way for the development of innovative therapeutic strategies against SEZ.

Pyroptosis: A major trigger of excessive immune response in the gingiva

OBJECTIVES

The gingival mucosal barrier, an important oral cavity barrier, plays a significant role in preventing pathogenic microorganism invasion and maintaining periodontal tissue health. Pathogenic microorganism invasion of the gingival mucosa produces a large number of cytokines. Among them, pyroptosis is an important player in exacerbating immune-inflammatory responses, leading to tissue destruction. However, the mechanism of pyroptosis and the immune response it triggers have not been fully elucidated. We provide an overview of recent advances in understanding gingival physical barrier pyroptosis and inflammation-induced hyperimmunity.

METHODS

PubMed, Web of Science databases were searched for articles, reviews, and clinical studies published until March 2024.

RESULTS

We summarised the importance of the gingival barrier in terms of the functions of different cells, described the progress in research on gingival epithelial cell and gingival fibroblast pyroptosis and the immune-inflammatory response it induces, and discussed the relationship between pyroptosis and systemic diseases, association of multiple cell death systems. Finally, we propose future directions for pyroptosis research.

CONCLUSIONS

Pyroptosis often triggers a range of inflammatory immune responses that lead to associated diseases. Therefore, further study of the molecular mechanisms of pyroptosis and the immune responses is warranted.

NLRP1-dependent activation of Gasdermin D in neutrophils controls cutaneous leishmaniasis

Intracellular pathogens that replicate in host myeloid cells have devised ways to inhibit the cell's killing machinery. Pyroptosis is one of the host strategies used to reduce the pathogen replicating niche and thereby control its expansion. The intracellular Leishmania parasites can survive and use neutrophils as a silent entry niche, favoring subsequent parasite dissemination into the host. Here, we show that Leishmania mexicana induces NLRP1- and caspase-1-dependent Gasdermin D (GSDMD)-mediated pyroptosis in neutrophils, a process critical to control the parasite-induced pathology. In the absence of GSDMD, we observe an increased number of infected dermal neutrophils two days post-infection. Using adoptive neutrophil transfer in neutropenic mice, we show that pyroptosis contributes to the regulation of the neutrophil niche early after infection. The critical role of neutrophil pyroptosis and its positive influence on the regulation of the disease outcome was further demonstrated following infection of mice with neutrophil-specific deletion of GSDMD. Thus, our study establishes neutrophil pyroptosis as a critical regulator of leishmaniasis pathology.

Revisiting the potential of regulated cell death in glioma treatment: a focus on autophagy-dependent cell death, anoikis, ferroptosis, cuproptosis, pyroptosis, immunogenic cell death, and the crosstalk between them

Gliomas are primary tumors that originate in the central nervous system. The conventional treatment options for gliomas typically encompass surgical resection and temozolomide (TMZ) chemotherapy. However, despite aggressive interventions, the median survival for glioma patients is merely about 14.6 months. Consequently, there is an urgent necessity to explore innovative therapeutic strategies for treating glioma. The foundational study of regulated cell death (RCD) can be traced back to Karl Vogt's seminal observations of cellular demise in toads, which were documented in 1842. In the past decade, the Nomenclature Committee on Cell Death (NCCD) has systematically classified and delineated various forms and mechanisms of cell death, synthesizing morphological, biochemical, and functional characteristics. Cell death primarily manifests in two forms: accidental cell death (ACD), which is caused by external factors such as physical, chemical, or mechanical disruptions; and RCD, a gene-directed intrinsic process that coordinates an orderly cellular demise in response to both physiological and pathological cues. Advancements in our understanding of RCD have shed light on the manipulation of cell death modulation - either through induction or suppression - as a potentially groundbreaking approach in oncology, holding significant promise. However, obstacles persist at the interface of research and clinical application, with significant impediments encountered in translating to therapeutic modalities. It is increasingly apparent that an integrative examination of the molecular underpinnings of cell death is imperative for advancing the field, particularly within the framework of inter-pathway functional synergy. In this review, we provide an overview of various forms of RCD, including autophagy-dependent cell death, anoikis, ferroptosis, cuproptosis, pyroptosis and immunogenic cell death. We summarize the latest advancements in understanding the molecular mechanisms that regulate RCD in glioma and explore the interconnections between different cell death processes. By comprehending these connections and developing targeted strategies, we have the potential to enhance glioma therapy through manipulation of RCD.

The role of inflammasome in chronic viral hepatitis

Infections of hepatotropic viruses cause a wide array of liver diseases including acute hepatitis, chronic hepatitis and the consequently developed cirrhosis and hepatocellular carcinoma (HCC). Among the five classical hepatotropic viruses, hepatitis B virus (HBV) and hepatitis C virus (HCV) usually infect human persistently and cause chronic hepatitis, leading to major troubles to humanity. Previous studies have revealed that several types of inflammasomes are involved in the infections of HBV and HCV. Here, we summarize the current knowledge about their roles in hepatitis B and C. NLRP3 inflammasome can be activated and regulated by HBV and HCV. It is found to exert antiviral function or mediates inflammatory response in viral infections depending on different experimental models. Besides NLRP3 inflammasome, IFI16 and AIM2 inflammasomes participate in the pathological process of hepatitis B, and NALP3 inflammasome may sense HCV infection in hepatocytes. The inflammasomes affect the pathological process of viral hepatitis through its downstream secretion of inflammatory cytokines interleukin-1β (IL-1β) and IL-18 or induction of pyroptosis resulting from cleaved gasdermin D (GSDMD). However, the roles of inflammasomes in different stages of viral infection remains mainly unclear. More proper experimental models of viral hepatitis should be developed for specific studies in future, so that we can understand more about the complexity of inflammasome regulation and multifunction of inflammasomes and their downstream effectors during HBV and HCV infections.

The Role of Pyroptosis in Coronary Heart Disease

The incidence and mortality of cardiovascular diseases, of which coronary heart disease (CHD) is a significant cardiovascular burden, are on the rise. Pyroptosis as an incipient programmed cell death mediated by inflammasomes can sense cytoplasmic contamination or interference and is typically marked by intracellular swelling, plasma membrane blistering and intense inflammatory cytokine release. As research on pyroptosis continues to progress, there is mounting evidence that pyroptosis is a vital participant in the pathophysiological basis of CHD. Atherosclerosis is the major pathophysiological basis of CHD and involves pyroptosis of endothelial cells, macrophages, vascular smooth muscle cells, and other immune cells, often in association with the release of pro-inflammatory factors. When cardiomyocytes are damaged, it will eventually lead to heart failure. Previous studies have covered that pyroptosis plays a critical role in CHD. In this review, we describe the properties of pyroptosis, summarize its contribution and related targets to diseases involving angina pectoris, myocardial infarction, myocardial ischemia in perfusion injury and heart failure, and highlight potential drugs for different heart diseases.

CircMLH3 induces mononuclear macrophage pyroptosis in sepsis by sponging miR-590-3p to regulate TAK1 expression

Sepsis is a fatal syndrome characterized by uncontrolled systemic inflammatory responses. Circular RNAs (circRNAs) are involved in the modulation of various pathophysiological processes, but their potential role in sepsis has largely been unexplored. In this study, we observed differential expression of circMLH3 between healthy volunteers and septic patients, and revealed the value of circMLH3 for sepsis diagnosis and prognostic prediction. Interestingly, we discovered a correlation between the expression level of circMLH3 and the degree of pyroptosis, a critical mechanism contributing to uncontrolled inflammation in sepsis patients. Knocking down circMLH3 alleviated macrophage pyroptosis whereas overexpressing circMLH3 aggravated pyroptosis. circMLH3 regulated macrophage pyroptosis by sponging miR-590-3p and subsequently modulating TAK1 expression. Furthermore, we found that the miR-590-3p/TAK1 axis inhibited the activation of pro-caspase-1 and the NLRP3 inflammasome. miR-590-3p overexpression had a protective effect by reducing macrophage pyroptosis, thereby alleviating sepsis-induced lung injury and systemic inflammatory responses. In conclusion, our study elucidated the circMLH3/miR-590-3p/TAK1 signaling pathway and identified its role in regulating mononuclear macrophage pyroptosis, thus providing potential novel targets and strategies for sepsis diagnosis and therapy.

Identification of Pyroptosis-Related Genes Regulating the Progression of Chronic Rhinosinusitis with Nasal Polyps

INTRODUCTION

Chronic rhinosinusitis with nasal polyps (CRSwNP) is an immunologic disease, and pyroptosis, an inflammation-based cellular death, strictly modulates CRSwNP pathology, whereas the pyroptosis genes and mechanisms involved in CRSwNP remain unclear. Herein, we explored disease biomarkers and potential therapeutic targets for pyroptosis and immune regulation in CRSwNP using bioinformatics analysis and tissue-based verification.

METHODS

We retrieved the transcriptional profiles of the high-throughput dataset GSE136825 from the Gene Expression Omnibus database, as well as 170 pyroptosis-related gene expressions from GeneCards. Using R, we identified differentially expressed pyroptosis-related genes and examined the potential biological functions of the aforementioned genes using Gene Ontology, Kyoto Encyclopedia of the Genome pathway, immune infiltration, and protein-protein interaction (PPI) network analyses, thereby generating a list of hub genes. The hub genes were, in turn, verified using real-time quantitative polymerase chain reaction (qRT-PCR), immunohistochemistry (IHC), and Western blotting (WB). Ultimately, using the StarBase and miRTarBase databases, we estimated the targeting microRNAs and long chain non-coding RNAs.

RESULTS

We demonstrated that the identified pyroptosis-related genes primarily modulated bacterial defense activities, as well as inflammasome immune response and assembly. Moreover, they were intricately linked to neutrophil and macrophage infiltration. Furthermore, we validated the tissue contents of hub genes AIM2, NLPR6, and CASP5 and examined potential associations with clinical variables. We also developed a competitive endogenous RNA (ceRNA) modulatory axis to examine possible underlying molecular mechanisms.

CONCLUSION

We found AIM2, CASP5, and NLRP6, three hub genes for pyroptosis in chronic rhinosinusitis with nasal polyps, by biological analysis, experimental validation, and clinical variable validation.

Non-apoptotic cell death programs in cervical cancer with an emphasis on ferroptosis

BACKGROUND

Cervical cancer, a pernicious gynecological malignancy, causes the mortality of hundreds of thousands of females worldwide. Despite a considerable decline in mortality, the surging incidence rate among younger women has raised serious concerns. Immortality is the most important characteristic of tumor cells, hence the carcinogenesis of cervical cancer cells pivotally requires compromising with cell death mechanisms.

METHODS

The current study comprehensively reviewed the mechanisms of non-apoptotic cell death programs to provide possible disease management strategies.

RESULTS

Comprehensive evidence has stated that focusing on necroptosis, pyroptosis, and autophagy for disease management is associated with significant limitations such as insufficient understanding, contradictory functions, dependence on disease stage, and complexity of intracellular pathways. However, ferroptosis represents a predictable role in cervix carcinogenesis, and ferroptosis-related genes demonstrate a remarkable correlation with patient survival and clinical outcomes.

CONCLUSION

Ferroptosis may be an appropriate option for disease management strategies from predicting prognosis to treatment.

Identification and Validation of Hub Genes Related to Neutrophil Extracellular Traps-Mediated Cell Damage During Myocardial Infarction

Purpose

Studies have shown that neutrophil-mediated formation of neutrophil extracellular traps (NETs) leads to increased inflammatory response and cellular tissue damage during myocardial infarction (MI). We aimed to identify and validate possible hub genes in the process of NETs-mediated cell damage.

Methods

We performed an immune cell infiltration analysis of the MI transcriptome dataset based on CIBERSORT and ssGSEA algorithms. Gene expression profiles of NETs formation (GSE178883) were used to analyze the physiological processes of peripheral blood neutrophils after phorbol myristate acetate (PMA) stimulation. Bioinformatics and machine learning algorithms were utilized to find candidate hub genes based on NETs-related genes and transcriptome datasets (GSE66360 and GSE179828). We generated the receiver operating curve (ROC) to evaluate the diagnostic value of hub genes. Next, the correlation between hub genes and immune cells was analyzed using CIBERSORT, ssGSEA and xCell algorithms. Finally, we used quantitative real-time PCR (qRT-PCR) and immunohistochemistry to verify gene expression.

Results

Immune cell infiltration analysis revealed that inflammatory cells such as neutrophils were highly expressed in the peripheral blood of patients with MI. Functional analysis of differentially expressed genes (DEGs) in GSE178883 indicated that the potential pathogenesis lies in immune terms. Using weighted gene co-expression network analysis (WGCNA) and machine learning algorithms, we finally identified the seven hub genes (FCAR, IL1B, MMP9, NFIL3, CXCL2, ICAM1, and ZFP36). The qRT-PCR results showed that IL-1B, MMP9, and NFIL3 mRNA expression was up-regulated in the MI group compared to the control. Immunohistochemical results showed high MMP9, IL-1B, and NFIL3 expression in the infarcted area compared to the non-infarcted area and sham-operated groups.

Conclusion

We identified seven hub genes associated with NETs-mediated cellular damage during MI. Our results may provide insights into the mechanisms of neutrophil-mediated cell injury during MI.

Gasdermin E dictates inflammatory responses by controlling the mode of neutrophil death

Both lytic and apoptotic cell death remove senescent and damaged cells in living organisms. However, they elicit contrasting pro- and anti-inflammatory responses, respectively. The precise cellular mechanism that governs the choice between these two modes of death remains incompletely understood. Here we identify Gasdermin E (GSDME) as a master switch for neutrophil lytic pyroptotic death. The tightly regulated GSDME cleavage and activation in aging neutrophils are mediated by proteinase-3 and caspase-3, leading to pyroptosis. GSDME deficiency does not alter neutrophil overall survival rate; instead, it specifically precludes pyroptosis and skews neutrophil death towards apoptosis, thereby attenuating inflammatory responses due to augmented efferocytosis of apoptotic neutrophils by macrophages. In a clinically relevant acid-aspiration-induced lung injury model, neutrophil-specific deletion of GSDME reduces pulmonary inflammation, facilitates inflammation resolution, and alleviates lung injury. Thus, by controlling the mode of neutrophil death, GSDME dictates host inflammatory outcomes, providing a potential therapeutic target for infectious and inflammatory diseases.

The role of exosomes in cancer-related programmed cell death

Cancer arises from the growth and division of uncontrolled erroneous cells. Programmed cell death (PCD), or regulated cell death (RCD), includes natural processes that eliminate damaged or abnormal cells. Dysregulation of PCD is a hallmark of cancer, as cancer cells often evade cell death and continue to proliferate. Exosomes nanoscale extracellular vesicles secreted by different types of cells carrying a variety of molecules, including nucleic acids, proteins, and lipids, to have indispensable role in the communication between cells, and can influence various cellular processes, including PCD. Exosomes have been shown to modulate PCD in cancer cells by transferring pro- or antideath molecules to neighboring cells. Additionally, exosomes can facilitate the spread of PCD to surrounding cancer cells, making them promising in the treatment of various cancers. The exosomes' diagnostic potential in cancer is also an active area of research. Exosomes can be isolated from a wide range of bodily fluids and tissues, such as blood and urine, and can provide a noninvasive way to monitor cancer progression and treatment response. Furthermore, exosomes have also been employed as a delivery system for therapeutic agents. By engineering exosomes to carry drugs or other therapeutic molecules, they can be targeted specifically to cancer cells, reducing toxicity to healthy tissues. Here, we discussed exosomes in the diagnosis and prevention of cancers, tumor immunotherapy, and drug delivery, as well as in different types of PCD.

cFLIPL alleviates myocardial ischemia-reperfusion injury by regulating pyroptosis

Alleviating myocardial ischemia-reperfusion injury (MIRI) plays a critical role in the prognosis and improvement of cardiac function following acute myocardial infarction. Pyroptosis is a newly identified form of cell death that has been implicated in the regulation of MIRI. In our study, H9c2 cells and SD rats were transfected using a recombinant adenovirus vector carrying cFLIPL , and the transfection was conducted for 3 days. Subsequently, H9c2 cells were subjected to 4 h of hypoxia followed by 12 h of reoxygenation to simulate an in vitro ischemia-reperfusion model. SD rats underwent 30 min of ischemia followed by 2 h of reperfusion to establish an MIRI model. Our findings revealed a notable decrease in cFLIPL expression in response to ischemia/reperfusion (I/R) and hypoxia/reoxygenation (H/R) injuries. Overexpression of cFLIPL can inhibit pyroptosis, reducing myocardial infarction area in vivo, and enhancing H9c2 cell viability in vitro. I/R and H/R injuries induced the upregulation of ASC, cleaved Caspase 1, NLRP3, GSDMD-N, IL-1β, and IL-18 proteins, promoting cell apoptosis. Our research indicates that cFLIPL may suppress pyroptosis by strategically binding with Caspase 1, inhibiting the release of inflammatory cytokines and preventing cell membrane rupture. Therefore, cFLIPL could potentially serve as a promising target for alleviating MIRI by suppressing the pyroptotic pathway.

NLRP3 selectively drives IL-1β secretion by Pseudomonas aeruginosa infected neutrophils and regulates corneal disease severity

Macrophages infected with Gram-negative bacteria expressing Type III secretion system (T3SS) activate the NLRC4 inflammasome, resulting in Gasdermin D (GSDMD)-dependent, but GSDME independent IL-1β secretion and pyroptosis. Here we examine inflammasome signaling in neutrophils infected with Pseudomonas aeruginosa strain PAO1 that expresses the T3SS effectors ExoS and ExoT. IL-1β secretion by neutrophils requires the T3SS needle and translocon proteins and GSDMD. In macrophages, PAO1 and mutants lacking ExoS and ExoT (ΔexoST) require NLRC4 for IL-1β secretion. While IL-1β release from ΔexoST infected neutrophils is also NLRC4-dependent, infection with PAO1 is instead NLRP3-dependent and driven by the ADP ribosyl transferase activity of ExoS. Genetic and pharmacologic approaches using MCC950 reveal that NLRP3 is also essential for bacterial killing and disease severity in a murine model of P. aeruginosa corneal infection (keratitis). Overall, these findings reveal a function for ExoS ADPRT in regulating inflammasome subtype usage in neutrophils versus macrophages and an unexpected role for NLRP3 in P. aeruginosa keratitis.

Integrated Analysis of Immune Infiltration and Hub Pyroptosis-Related Genes for Multiple Sclerosis

Purpose

Studies on overall immune infiltration and pyroptosis in patients with multiple sclerosis (MS) are limited. This study explored immune cell infiltration and pyroptosis in MS using bioinformatics and experimental validation.

Methods

The GSE131282 and GSE135511 microarray datasets including brain autopsy tissues from controls and MS patients were downloaded for bioinformatic analysis. The gene expression-based deconvolution method, CIBERSORT, was used to determine immune infiltration. Differentially expressed genes (DEGs) and functional enrichments were analyzed. We then extracted pyroptosis-related genes (PRGs) from the DEGs by using machine learning strategies. Their diagnostic ability for MS was evaluated in both the training set (GSE131282 dataset) and validation set (GSE135511 dataset). In addition, messenger RNA (mRNA) expression of PRGs was validated using quantitative real-time polymerase chain reaction (qRT-PCR) in cortical tissue from an experimental autoimmune encephalomyelitis (EAE) model of MS. Moreover, the functional enrichment pathways of each hub PRG were estimated. Finally, co-expressed competitive endogenous RNA (ceRNA) networks of PRGs in MS were constructed.

Results

Among the infiltrating cells, naive CD4+ T cells (P=0.006), resting NK cells (P=0.002), activated mast cells (P=0.022), and neutrophils (P=0.002) were significantly higher in patients with MS than in controls. The DEGs of MS were screened. Analysis of enrichment pathways showed that the pathways of transcriptional regulatory mechanisms and ion channels associating with pyroptosis. Four PRGs genes CASP4, PLCG1, CASP9 and NLRC4 were identified. They were validated in both the GSE135511 dataset and the EAE model by using qRT-PCR. CASP4 and NLRC4 were ultimately identified as stable hub PRGs for MS. Single-gene Gene Set Enrichment Analysis showed that they mainly participated in biosynthesis, metabolism, and organism resistance. ceRNA networks containing CASP4 and NLRC4 were constructed.

Conclusion

MS was associated with immune infiltration. CASP4 and NLRC4 were key biomarkers of pyroptosis in MS.

Comprehensive characterization of pyroptosis phenotypes with distinct tumor immune profiles in gastric cancer to aid immunotherapy

OBJECTIVE

Pyroptosis is a form of programmed cell death that is essential for immunity. Herein, this study was conducted to uncover the implication of pyroptosis in immunomodulation and tumor microenvironment (TME) in gastric cancer.

METHODS

Prognostic pyroptosis-related genes were extracted to identify different pyroptosis phenotypes and pyroptosis genomic phenotypes via unsupervised clustering analysis in the gastric cancer meta-cohort cohort (GSE15459, GSE62254, GSE84437, GSE26253 and TCGA-STAD). The activation of hallmark gene sets was quantified by GSVA and immune cell infiltration was estimated via ssGSEA and CIBERSORT. Through PCA algorithm, pyroptosis score was conducted. The predictors of immune response (TMB and IPS) and genetic mutations were evaluated. The efficacy of pyroptosis score in predicting immune response was verified in two anti-PD-1 therapy cohorts.

RESULTS

Three different pyroptosis phenotypes with different prognosis, biological pathways and tumor immune microenvironment were established among 1275 gastric cancer patients, corresponding to three immune phenotypes: immune-inflamed, immune-desert, and immune-excluded. According to the pyroptosis score, patients were separated into high and low pyroptosis score groups. Low pyroptosis score indicated favorable survival outcomes, enhanced immune responses, and increased mutation frequency. Moreover, low pyroptosis score patients displayed more clinical benefits from anti-PD-1 and prolonged survival time.

CONCLUSION

Our findings uncovered a nonnegligible role of pyroptosis in immunomodulation and TME multiformity and complicacy in gastric cancer. Quantifying the pyroptosis score in individual tumors may tailor more effective immunotherapeutic strategies.

Electroacupuncture Alleviates Lung Injury in CpG1826-Challenged Mice via Modulating CD39-NLRP3 Pathway

PURPOSE

Cytokine storm secondary lung injury (CSSLI) is the leading death cause in COVID-19 virus infection, and CD39-dominated purinergic brake drives NLRP3 inflammasome activation and pyroptosis, which plays a crucial role in the pathogenesis of CSSLI. Though electroacupuncture (EA) can alleviate lung injury caused by a variety of inducers, its effect on CSSLI and the underlying mechanism needs further investigation.

METHODS

We established a widely recognized CSSLI mice model with CpG1826 (CpG), a TLR-9 agonist agent. Luminex liquid chip was employed to detect serum levels of 12 cytokines/chemokines to evaluate cytokine storm formation. H+E staining and transmission electron microscope were applied to examine pulmonary pathological injury and alveolar macrophage structure, respectively. IL-1β, IL-18, IL-1α, and HMGB-1 in BAL fluid were determined by ELISA kits. mRNA and protein levels of lung CD39 and NLRP3 were assessed by qRT-PCR and Western blotting. An in vitro model was also established by incubating PMA-differentiated THP-1 cells with serum samples obtained from relevant group of mice.

RESULTS

Repeated CpG induced CSSLI together with the elevation of 11 cytokines/chemokines including GM-CSF, IL-16, IL-1α, MCP-1, IL-2, IL-10, CCL3, IL-1β, TNF-α, IL-6, and IL-17A, though not IFN-γ, which was reduced by EA pretreatment to a different extent. EA also alleviated lung injury and recovered lung macrophage structure. Moreover, CpG enhanced IL-1β and IL-18 level in BAL fluid, promoted NLRP3, while suppressing CD39 expression in lung, all of which were reversed by EA pretreatment. Of note, EA failed to further decrease BAL fluid IL-1β, IL-18, IL-1α, and HMGB-1 levels when A438079, a selective inhibitor of P2X7, was administered. However, both CD39 and NLRP3 are dispensable for EA decreasing multi-cytokine secretion in serum-incubated and CpG-stimulated THP-1 cells. Taken together, EA alleviated CSSLI in CpG-challenged mice by regulating the CD39-NLRP3 pathway in a P2X7-dependent way.

CONCLUSION

EA demonstrated potential to be applied in COVID-19 treatment.

Gasdermins assemble; recent developments in bacteriology and pharmacology

The discovery of gasdermin D (GSDMD) as the terminal executioner of pyroptosis provided a large piece of the cell death puzzle, whilst simultaneously and firmly putting the gasdermin family into the limelight. In its purest form, GSDMD provides a connection between the innate alarm systems to an explosive, inflammatory form of cell death to jolt the local environment into immunological action. However, the gasdermin field has moved rapidly and significantly since the original seminal work and novel functions and mechanisms have been recently uncovered, particularly in response to infection. Gasdermins regulate and are regulated by mechanisms such as autophagy, metabolism and NETosis in fighting pathogen and protecting host. Importantly, activators and interactors of the other gasdermins, not just GSDMD, have been recently elucidated and have opened new avenues for gasdermin-based discovery. Key to this is the development of potent and specific tool molecules, so far a challenge for the field. Here we will cover some of these recently discovered areas in relation to bacterial infection before providing an overview of the pharmacological landscape and the challenges associated with targeting gasdermins.

Immunity to pathogenic fungi in the eye

Fusarium, Aspergillus and Candida are important fungal pathogens that cause visual impairment and blindness in the USA and worldwide. This review will summarize the epidemiology and clinical features of corneal infections and discuss the immune and inflammatory responses that play an important role in clinical disease. In addition, we describe fungal virulence factors that are required for survival in infected corneas, and the activities of neutrophils in fungal killing, tissue damage and cytokine production.

Inflammasome and pyroptosis in autoimmune liver diseases

Autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), and IgG4-related sclerosing cholangitis (IgG4-SC) are the four main forms of autoimmune liver diseases (AILDs), which are all defined by an aberrant immune system attack on the liver. Most previous studies have shown that apoptosis and necrosis are the two major modes of hepatocyte death in AILDs. Recent studies have reported that inflammasome-mediated pyroptosis is critical for the inflammatory response and severity of liver injury in AILDs. This review summarizes our present understanding of inflammasome activation and function, as well as the connections among inflammasomes, pyroptosis, and AILDs, thus highlighting the shared features across the four disease models and gaps in our knowledge. In addition, we summarize the correlation among NLRP3 inflammasome activation in the liver-gut axis, liver injury, and intestinal barrier disruption in PBC and PSC. We summarize the differences in microbial and metabolic characteristics between PSC and IgG4-SC, and highlight the uniqueness of IgG4-SC. We explore the different roles of NLRP3 in acute and chronic cholestatic liver injury, as well as the complex and controversial crosstalk between various types of cell death in AILDs. We also discuss the most up-to-date developments in inflammasome- and pyroptosis-targeted medicines for autoimmune liver disorders.