Streptococcal pyrogenic exotoxin B cleaves GSDMA and triggers pyroptosis

Cell death

Cell death supports morphogenesis during development and homeostasis after birth by removing damaged or obsolete cells. It also curtails the spread of pathogens by eliminating infected cells. Cell death can be induced by the genetically programmed suicide mechanisms of apoptosis, necroptosis, and pyroptosis, or it can be a consequence of dysregulated metabolism, as in ferroptosis. Here, we review the signaling mechanisms underlying each cell-death pathway, discuss how impaired or excessive activation of the distinct cell-death processes can promote disease, and highlight existing and potential therapies for redressing imbalances in cell death in cancer and other diseases.

Multiomics characterization of pyroptosis in the tumor microenvironment and therapeutic relevance in metastatic melanoma

BACKGROUND

Pyroptosis, mediated by gasdermins with the release of multiple inflammatory cytokines, has emerged as playing an important role in targeted therapy and immunotherapy due to its effectiveness at inhibiting tumor growth. Melanoma is one of the most commonly used models for immunotherapy development, though an inadequate immune response can occur. Moreover, the development of pyroptosis-related therapy and combinations with other therapeutic strategies is limited due to insufficient understanding of the role of pyroptosis in the context of different tumor immune microenvironments (TMEs).

METHODS

Here, we present a computational model (pyroptosis-related gene score, PScore) to assess the pyroptosis status. We applied PScore to 1388 melanoma samples in our in-house cohort and eight other publicly available independent cohorts and then calculated its prognostic power of and potential as a predictive marker of immunotherapy efficacy. Furthermore, we performed association analysis for PScore and the characteristics of the TME by using bulk, single-cell, and spatial transcriptomics and assessed the association of PScore with mutation status, which contributes to targeted therapy.

RESULTS

Pyroptosis-related genes (PRGs) showed distinct expression patterns and prognostic predictive ability in melanoma. Most PRGs were associated with better survival in metastatic melanoma. Our PScore model based on genes associated with prognosis exhibits robust performance in survival prediction in multiple metastatic melanoma cohorts. We also found PScore to be associated with BRAF mutation and correlate positively with multiple molecular signatures, such as KRAS signaling and the IFN gamma response pathway. Based on our data, melanoma with an immune-enriched TME had a higher PScore than melanoma with an immune-depleted or fibrotic TME. Additionally, monocytes had the highest PScore and malignant cells and fibroblasts the lowest PScore based on single-cell and spatial transcriptome analyses. Finally, a higher PScore was associated with better therapeutic efficacy of immune checkpoint blockade, suggesting the potential of pyroptosis to serve as a marker of immunotherapy response.

CONCLUSIONS

Collectively, our findings indicate that pyroptosis is a prognostic factor and is associated with the immune response in metastatic melanoma, as based on multiomics data. Our results provide a theoretical basis for drug combination and reveal potential immunotherapy response markers.

Nanomaterial-induced pyroptosis: a cell type-specific perspective

This review presents the advancements in nanomaterial (NM)-induced pyroptosis in specific types of cells. We elucidate the relevance of pyroptosis and delineate its mechanisms and classifications. We also retrospectively analyze pyroptosis induced by various NMs in a broad spectrum of non-tumorous cellular environments to highlight the multifunctionality of NMs in modulating cell death pathways. We identify key knowledge gaps in current research and propose potential areas for future exploration. This review emphasizes the need to focus on less-studied areas, including the pathways and mechanisms of NM-triggered pyroptosis in non-tumor-specific cell types, the interplay between biological and environmental factors, and the interactions between NMs and cells. This review aims to encourage further investigations into the complex interplay between NMs and pyroptosis, thereby providing a basis for developing safer and more effective nanomedical therapeutic applications.

Characterization of immunomodulating agents from Staphylococcus aureus for priming immunotherapy in triple-negative breast cancers

Immunotherapy, specifically immune checkpoint blockade (ICB), has revolutionized the treatment paradigm of triple-negative breast cancers (TNBCs). However, a subset of TNBCs devoid of tumor-infiltrating T cells (TILs) or PD-L1 expression generally has a poor response to immunotherapy. In this study, we aimed to sensitize TNBCs to ICB by harnessing the immunomodulating potential of S. aureus, a breast-resident bacterium. We show that intratumoral injection of spent culture media from S. aureus recruits TILs and suppresses tumor growth in a preclinical TNBC model. We further demonstrate that α-hemolysin (HLA), an S. aureus-produced molecule, increases the levels of CD8+ T cells and PD-L1 expression in tumors, delays tumor growth, and triggers tumor necrosis. Mechanistically, while tumor cells treated with HLA display Gasdermin E (GSDME) cleavage and a cellular phenotype resembling pyroptosis, splenic T cells incubated with HLA lead to selective expansion of CD8+ T cells. Notably, intratumoral HLA injection prior to ICB augments the therapeutic efficacy compared to ICB alone. This study uncovers novel immunomodulatory properties of HLA and suggests that intratumoral administration of HLA could be a potential priming strategy to expand the population of TNBC patients who may respond to ICB.

Caspase-1 activates gasdermin A in non-mammals

Gasdermins oligomerize to form pores in the cell membrane, causing regulated lytic cell death called pyroptosis. Mammals encode five gasdermins that can trigger pyroptosis: GSDMA, B, C, D, and E. Caspase and granzyme proteases cleave the linker regions of and activate GSDMB, C, D, and E, but no endogenous activation pathways are yet known for GSDMA. Here, we perform a comprehensive evolutionary analysis of the gasdermin family. A gene duplication of GSDMA in the common ancestor of caecilian amphibians, reptiles and birds gave rise to GSDMA-D in mammals. Uniquely in our tree, amphibian, reptile and bird GSDMA group in a separate clade than mammal GSDMA. Remarkably, GSDMA in numerous bird species contain caspase-1 cleavage sites like YVAD or FASD in the linker. We show that GSDMA from birds, amphibians, and reptiles are all cleaved by caspase-1. Thus, GSDMA was originally cleaved by the host-encoded protease caspase-1. In mammals the caspase-1 cleavage site in GSDMA is disrupted; instead, a new protein, GSDMD, is the target of caspase-1. Mammal caspase-1 uses exosite interactions with the GSDMD C-terminal domain to confer the specificity of this interaction, whereas we show that bird caspase-1 uses a stereotypical tetrapeptide sequence to confer specificity for bird GSDMA. Our results reveal an evolutionarily stable association between caspase-1 and the gasdermin family, albeit a shifting one. Caspase-1 repeatedly changes its target gasdermin over evolutionary time at speciation junctures, initially cleaving GSDME in fish, then GSDMA in amphibians/reptiles/birds, and finally GSDMD in mammals.

Nanomaterials for Disease Treatment by Modulating the Pyroptosis Pathway

Pyroptosis differs significantly from apoptosis and cell necrosis as an alternative mode of programmed cell death. Its occurrence is mediated by the gasdermin protein, leading to characteristic outcomes including cell swelling, membrane perforation, and release of cell contents. Research underscores the role of pyroptosis in the etiology and progression of many diseases, making it a focus of research intervention as scientists explore ways to regulate pyroptosis pathways in disease management. Despite numerous reviews detailing the relationship between pyroptosis and disease mechanisms, few delve into recent advancements in nanomaterials as a mechanism for modulating the pyroptosis pathway to mitigate disease effects. Therefore, there is an urgent need to fill this gap and elucidate the path for the use of this promising technology in the field of disease treatment. This review article delves into recent developments in nanomaterials for disease management through pyroptosis modulation, details the mechanisms by which drugs interact with pyroptosis pathways, and highlights the promise that nanomaterial research holds in driving forward disease treatment.

Cell Death Pathway Regulation by Functional Nanomedicines for Robust Antitumor Immunity

Cancer immunotherapy has become a mainstream cancer treatment over traditional therapeutic modes. Cancer cells can undergo programmed cell death including ferroptosis, pyroptosis, autophagy, necroptosis, apoptosis and cuproptosis which are find to have intrinsic relationships with host antitumor immune response. However, direct use of cell death inducers or regulators may bring about severe side effects that can also be rapidly excreted and degraded with low therapeutic efficacy. Nanomaterials are able to carry them for long circulation time, high tumor accumulation and controlled release to achieve satisfactory therapeutic effect. Nowadays, a large number of studies have focused on nanomedicines-based strategies through modulating cell death modalities to potentiate antitumor immunity. Herein, immune cell types and their function are first summarized, and state-of-the-art research progresses in nanomedicines mediated cell death pathways (e.g., ferroptosis, pyroptosis, autophagy, necroptosis, apoptosis and cuproptosis) with immune response provocation are highlighted. Subsequently, the conclusion and outlook of potential research focus are discussed.

Stress/cell death pathways, neuroinflammation, and neuropathic pain

Neuropathic pain is a common and debilitating modality of chronic pain induced by a lesion or disease of the somatosensory nervous system. Albeit the elucidation of numerous pathophysiological mechanisms and the development of potential treatment compounds, safe and reliable therapies of neuropathic pain remain poor. Multiple stress/cell death pathways have been shown to be implicated in neuroinflammation during neuropathic pain. Here, we summarize the current knowledge of stress/cell death pathways and present an overview of the roles and molecular mechanisms of stress/cell death pathways in neuroinflammation during neuropathic pain, covering intrinsic and extrinsic apoptosis, autophagy, mitophagy, ferroptosis, pyroptosis, necroptosis, and phagoptosis. Small molecule compounds that modulate stress/cell death pathways in alleviating neuropathic pain are discussed mainly based on preclinical neuropathic pain models. These findings will contribute to in-depth understanding of the pathological processes during neuropathic pain as well as bridge the gap between basic and translational research to uncover new neuroprotective interventions.

Pyroptosis in microbial infectious diseases

Pyroptosis is a gasdermins-mediated programmed cell death that plays an essential role in immune regulation, and its role in autoimmune disease and cancer has been studied extensively. Increasing evidence shows that various microbial infections can lead to pyroptosis, associated with the occurrence and development of microbial infectious diseases. This study reviews the recent advances in pyroptosis in microbial infection, including bacterial, viral, and fungal infections. We also explore potential therapeutic strategies for treating microbial infection-related diseases by targeting pyroptosis.

The role of pyroptosis and gasdermin family in tumor progression and immune microenvironment

Pyroptosis, an inflammatory programmed cell death, distinguishes itself from apoptosis and necroptosis and has drawn increasing attention. Recent studies have revealed a correlation between the expression levels of many pyroptosis-related genes and both tumorigenesis and progression. Despite advancements in cancer treatments such as surgery, radiotherapy, chemotherapy, and immunotherapy, the persistent hallmark of cancer enables malignant cells to elude cell death and develop resistance to therapy. Recent findings indicate that pyroptosis can overcome apoptosis resistance amplify treatment-induced tumor cell death. Moreover, pyroptosis triggers antitumor immunity by releasing pro-inflammatory cytokines, augmenting macrophage phagocytosis, and activating cytotoxic T cells and natural killer cells. Additionally, it transforms "cold" tumors into "hot" tumors, thereby enhancing the antitumor effects of various treatments. Consequently, pyroptosis is intricately linked to tumor development and holds promise as an effective strategy for boosting therapeutic efficacy. As the principal executive protein of pyroptosis, the gasdermin family plays a pivotal role in influencing pyroptosis-associated outcomes in tumors and can serve as a regulatory target. This review provides a comprehensive summary of the relationship between pyroptosis and gasdermin family members, discusses their roles in tumor progression and the tumor immune microenvironment, and analyses the underlying therapeutic strategies for tumor treatment based on pyroptotic cell death.

Carboxypeptidase A4 negatively regulates HGS-ETR1/2-induced pyroptosis by forming a positive feedback loop with the AKT signalling pathway

Pyroptosis, a mode of inflammatory cell death, has recently gained significant attention. However, the underlying mechanism remains poorly understood. HGS-ETR1/2 is a humanized monoclonal antibody that can bind to DR4/5 on the cell membrane and induce cell apoptosis by activating the death receptor signalling pathway. In this study, by using morphological observation, fluorescence double staining, LDH release and immunoblot detection, we confirmed for the first time that HGS-ETR1/2 can induce GSDME-mediated pyroptosis in hepatocellular carcinoma cells. Our study found that both inhibition of the AKT signalling pathway and silencing of CPA4 promote pyroptosis, while the overexpression of CPA4 inhibits it. Furthermore, we identified a positive regulatory feedback loop is formed between CPA4 and AKT phosphorylation. Specifically, CPA4 modulates AKT phosphorylation by regulating the expression of the AKT phosphatase PP2A, while inhibition of the AKT signalling pathway leads to a decreased transcription and translation levels of CPA4. Our study reveals a novel mechanism of pyroptosis induced by HGS-ETR1/2, which may provide a crucial foundation for future investigations into cancer immunotherapy.

RopB-regulated SpeB cysteine protease degrades extracellular vesicles-associated streptolysin O and bacterial proteins from group A Streptococcus

Extracellular vesicles (EVs) can be released from gram-positive bacteria and would participate in the delivery of bacterial toxins. Streptococcus pyogenes (group A Streptococcus, GAS) is one of the most common pathogens of monomicrobial necrotizing fasciitis. Spontaneous inactivating mutation in the CovR/CovS two-component regulatory system is related to the increase of EVs production via an unknown mechanism. This study aimed to investigate whether the CovR/CovS-regulated RopB, the transcriptional regulator of GAS exoproteins, would participate in regulating EVs production. Results showed that the size, morphology, and number of EVs released from the wild-type strain and the ropB mutant were similar, suggesting RopB is not involved in controlling EVs production. Nonetheless, RopB-regulated SpeB protease degrades streptolysin O and bacterial proteins in EVs. Although SpeB has crucial roles in modulating protein composition in EVs, the SpeB-positive EVs failed to trigger HaCaT keratinocytes pyroptosis, suggesting that EVs did not deliver SpeB into keratinocytes or the amount of SpeB in EVs was not sufficient to trigger cell pyroptosis. Finally, we identified that EV-associated enolase was resistant to SpeB degradation, and therefore could be utilized as the internal control protein for verifying SLO degradation. This study revealed that RopB would participate in modulating protein composition in EVs via SpeB-dependent protein degradation and suggested that enolase is a potential internal marker for studying GAS EVs.

Evolution of the gasdermin family and pyroptosis

Gasdermins have been identified as playing a prominent role in the innate immune response as the executors of a specific type of cell death called pyroptosis. Specific proteolytic cleavage of gasdermins generates an N-terminal that oligomerizes and forms pores in the cell membrane. Although pyroptosis has been widely described in mammals, the importance of gasdermins and gasdermin-like proteins in inducing cell death in other vertebrates, in invertebrates and in other taxa including fungi and bacteria is still being determined. Mammalian, fungal and bacterial gasdermins have in common the fact that they go through the same stages (such as proteolytic activation) when inducing membrane rupture, which suggests that pyroptosis is as an ancient mechanism. In this review, we summarize the evolution and function of the gasdermin and gasdermin-like proteins in animals, fungi and bacteria.

Gasdermins in sepsis

Sepsis is a hyper-heterogeneous syndrome in which the systemic inflammatory response persists throughout the course of the disease and the inflammatory and immune responses are dynamically altered at different pathogenic stages. Gasdermins (GSDMs) proteins are pore-forming executors in the membrane, subsequently mediating the release of pro-inflammatory mediators and inflammatory cell death. With the increasing research on GSDMs proteins and sepsis, it is believed that GSDMs protein are one of the most promising therapeutic targets in sepsis in the future. A more comprehensive and in-depth understanding of the functions of GSDMs proteins in sepsis is important to alleviate the multi-organ dysfunction and reduce sepsis-induced mortality. In this review, we focus on the function of GSDMs proteins, the molecular mechanism of GSDMs involved in sepsis, and the regulatory mechanism of GSDMs-mediated signaling pathways, aiming to provide novel ideas and therapeutic strategies for the diagnosis and treatment of sepsis.

Epigenetic and transcriptional control of gasdermins

Cells undergo an inflammatory programmed lytic cell death called 'pyroptosis' (with the Greek roots 'fiery'), often featuring morphological hallmarks such as large ballooning protrusions and subsequent bursting. Originally described as a caspase-1-dependent cell death in response to bacterial infection, pyroptosis has since been re-defined in 2018 as a cell death dependent on plasma membrane pores by a gasdermin (GSDM) family member [1,2]. GSDMs form pores in the plasma membrane as well as organelle membranes, thereby initiating membrane destruction and the rapid and lytic demise of a cell. The gasdermin family plays a profound role in the execution of pyroptosis in the context of infection, inflammation, tumor pathogenesis, and anti-tumor therapy. More recently, cell-death-independent functions for some of the GSDMs have been proposed. Therefore, a comprehensive understanding of gasdermin gene regulation, including mechanisms in both homeostatic conditions and during inflammation, is essential. In this review, we will summarize the role of gasdermins in pyroptosis and focus our discussion on the transcriptional and epigenetic mechanisms controlling the expression of GSDMs.

The implication of pyroptosis in cancer immunology: Current advances and prospects

Pyroptosis is a regulated cell death pathway involved in numerous human diseases, especially malignant tumors. Recent studies have identified multiple pyroptosis-associated signaling molecules, like caspases, gasdermin family and inflammasomes. In addition, increasing in vitro and in vivo studies have shown the significant linkage between pyroptosis and immune regulation of cancers. Pyroptosis-associated biomarkers regulate the infiltration of tumor immune cells, such as CD4+ and CD8+ T cells, thus strengthening the sensitivity to therapeutic strategies. In this review, we explained the relationship between pyroptosis and cancer immunology and focused on the significance of pyroptosis in immune regulation. We also proposed the future application of pyroptosis-associated biomarkers in basic research and clinical practices to address malignant behaviors. Exploration of the underlying mechanisms and biological functions of pyroptosis is critical for immune response and cancer immunotherapy.

Caspase-3/GSDME mediated pyroptosis: A potential pathway for sepsis

The inflammatory response is one of the host's mechanisms to combat pathogens. Normal and controlled inflammation can accelerate the clearance of pathogens. However, in sepsis, the host often exhibits an excessive inflammatory response to infection, leading to tissue and organ damage. Therefore, studying the mechanisms underlying the occurrence and development of sepsis is of significant importance. Pyroptosis is a form of programmed cell death (PCD) executed by the gasdermins (GSDMs) family, and its pro-inflammatory characteristics are considered a crucial component of the sepsis mechanism. Previous research on pyroptosis in sepsis has mainly focused on the caspase-1/4/5/11-GSDMD pathway, which has made significant progress. However, there is a lack of research on the roles of other GSDMs family members in sepsis. New research has revealed that the caspase-3/GSDME pathway can also mediate pyroptosis, playing important roles in cancer, other inflammatory diseases, and even some sepsis-related conditions. This discovery suggests the potential value of investigating caspase-3/GSDME in sepsis research. This review provides an overview of the role of the GSDMs family in infectious diseases, summarizes current research on the caspase-1/4/5/11-GSDMD pathway, describes the role of caspase-3 in sepsis, and discusses the research findings related to pyroptosis mediated by the caspase-3/GSDME pathway in cancer, inflammatory diseases, and sepsis-related conditions. The aim of this article is to propose the concept of caspase-3/GSDME as a potential target in sepsis research. Considering the role of this pathway in other diseases, including inflammatory conditions, and given the unique nature of sepsis as an inflammatory disease, the article suggests that this pathway may also play a role in sepsis. This hypothesis provides new insights and options for future sepsis research, although direct experiments are needed to validate this hypothesis.

Pyroptosis: the dawn of a new era in endometrial cancer treatment

Endometrial cancer (EC) is a malignancy of the inner epithelial lining of the uterus. While early-stage EC is often curable through surgery, the management of advanced, recurrent and metastatic EC poses significant challenges and is associated with a poor prognosis. Pyroptosis, an emerging form of programmed cell death, is characterized by the cleavage of gasdermin proteins, inducing the formation of extensive gasdermin pores in the cell membrane and the leakage of interleukin-1β (IL-1β) and interleukin-18 (IL-18), consequently causing cell swelling, lysis and death. It has been found to be implicated in the occurrence and progression of almost all tumors. Recent studies have demonstrated that regulating tumor cells pyroptosis can exploit synergies function with traditional tumor treatments. This paper provides an overview of the research progress made in molecular mechanisms of pyroptosis. It then discusses the role of pyroptosis and its components in initiation and progression of endometrial cancer, emphasizing recent insights into the underlying mechanisms and highlighting unresolved questions. Furthermore, it explores the potential value of pyroptosis in the treatment of endometrial cancer, considering its current application in tumor radiotherapy, chemotherapy, targeted therapy and immunotherapy.

Non-apoptotic programmed cell deaths in diabetic pulmonary dysfunction: the new side of advanced glycation end products

Diabetes mellitus (DM) is a chronic metabolic disorder that affects multiple organs and systems, including the pulmonary system. Pulmonary dysfunction in DM patients has been observed and studied for years, but the underlying mechanisms have not been fully understood. In addition to traditional mechanisms such as the production and accumulation of advanced glycation end products (AGEs), angiopathy, tissue glycation, oxidative stress, and systemic inflammation, recent studies have focused on programmed cell deaths (PCDs), especially the non-apoptotic ones, in diabetic pulmonary dysfunction. Non-apoptotic PCDs (NAPCDs) including autophagic cell death, necroptosis, pyroptosis, ferroptosis, and copper-induced cell death have been found to have certain correlations with diabetes and relevant complications. The AGE-AGE receptor (RAGE) axis not only plays an important role in the traditional pathogenesis of diabetes lung disease but also plays an important role in non-apoptotic cell death. In this review, we summarize novel studies about the roles of non-apoptotic PCDs in diabetic pulmonary dysfunction and focus on their interactions with the AGE-RAGE axis.

Recent advances in natural compounds inducing non-apoptotic cell death for anticancer drug resistance

The induction of cell death is recognized as a potent strategy for cancer treatment. Apoptosis is an extensively studied form of cell death, and multiple anticancer drugs exert their therapeutic effects by inducing it. Nonetheless, apoptosis evasion is a hallmark of cancer, rendering cancer cells resistant to chemotherapy drugs. Consequently, there is a growing interest in exploring novel non-apoptotic forms of cell death, such as ferroptosis, necroptosis, pyroptosis, and paraptosis. Natural compounds with anticancer properties have garnered significant attention due to their advantages, including a reduced risk of drug resistance. Over the past two decades, numerous natural compounds have been discovered to exert anticancer and anti-resistance effects by triggering these four non-apoptotic cell death mechanisms. This review primarily focuses on these four non-apoptotic cell death mechanisms and their recent advancements in overcoming drug resistance in cancer treatment. Meanwhile, it highlights the role of natural compounds in effectively addressing cancer drug resistance through the induction of these forms of non-apoptotic cell death.

ER stress induces caspase-2-tBID-GSDME-dependent cell death in neurons lytically infected with herpes simplex virus type 2

Neurotropic viruses, including herpes simplex virus (HSV) types 1 and 2, have the capacity to infect neurons and can cause severe diseases. This is associated with neuronal cell death, which may contribute to morbidity or even mortality if the infection is not controlled. However, the mechanistic details of HSV-induced neuronal cell death remain enigmatic. Here, we report that lytic HSV-2 infection of human neuron-like SH-SY5Y cells and primary human and murine brain cells leads to cell death mediated by gasdermin E (GSDME). HSV-2-induced GSDME-mediated cell death occurs downstream of replication-induced endoplasmic reticulum stress driven by inositol-requiring kinase 1α (IRE1α), leading to activation of caspase-2, cleavage of the pro-apoptotic protein BH3-interacting domain death agonist (BID), and mitochondria-dependent activation of caspase-3. Finally, necrotic neurons released alarmins, which activated inflammatory responses in human iPSC-derived microglia. In conclusion, lytic HSV infection in neurons activates an ER stress-driven pathway to execute GSDME-mediated cell death and promote inflammation.

A high-throughput Gaussia luciferase reporter assay for screening potential gasdermin E activators against pancreatic cancer

It is discovered that activated caspase-3 tends to induce apoptosis in gasdermin E (GSDME)-deficient cells, but pyroptosis in GSDME-sufficient cells. The high GSDME expression and apoptosis resistance of pancreatic ductal adenocarcinoma (PDAC) cells shed light on another attractive strategy for PDAC treatment by promoting pyroptosis. Here we report a hGLuc-hGSDME-PCA system for high-throughput screening of potential GSDME activators against PDAC. This screening system neatly quantifies the oligomerization of GSDME-N to characterize whether pyroptosis occurs under the stimulation of chemotherapy drugs. Based on this system, ponatinib and perifosine are screened out from the FDA-approved anti-cancer drug library containing 106 compounds. Concretely, they exhibit the most potent luminescent activity and cause drastic pyroptosis in PDAC cells. Further, we demonstrate that perifosine suppresses pancreatic cancer by promoting pyroptosis via caspase-3/GSDME pathway both in vitro and in vivo. Collectively, this study reveals the great significance of hGLuc-hGSDME-PCA in identifying compounds triggering GSDME-dependent pyroptosis and developing promising therapeutic agents for PDAC.

Roles of pyroptosis in atherosclerosis pathogenesis

Pyroptosis is a pro-inflammatory type of regulated cell death (RCD) characterized by gasdermin protein-mediated membrane pore formation, cell swelling, and rapid lysis. Recent studies have suggested that pyroptosis is closely related to atherosclerosis (AS). Previous studies reported that pyroptosis involving endothelial cells (ECs), macrophages, and smooth muscle cells (SMCs) plays an important role in the formation and development of AS. Pyroptosis not only causes local inflammation but also amplifies the inflammatory response and it aggravates plaque instability, leading to plaque rupture and thrombosis, eventually resulting in acute cardiovascular events. In this review, we clarified some novel pathways and mechanics and presented some potential drugs.

Streptococcus pyogenes: Pathogenesis and the Current Status of Vaccines

Streptococcus pyogenes (group A Streptococcus; GAS), a Gram-positive coccal bacterium, poses a significant global disease burden, especially in low- and middle-income countries. Its manifestations can range from pharyngitis and skin infection to severe and aggressive diseases, such as necrotizing fasciitis and streptococcal toxic shock syndrome. At present, although GAS is still sensitive to penicillin, there are cases of treatment failure for GAS pharyngitis, and antibiotic therapy does not universally prevent subsequent disease. In addition to strengthening global molecular epidemiological surveillance and monitoring of antibiotic resistance, developing a safe and effective licensed vaccine against GAS would be the most effective way to broadly address GAS-related diseases. Over the past decades, the development of GAS vaccines has been stalled, mainly because of the wide genetic heterogeneity of GAS and the diverse autoimmune responses to GAS. With outbreaks of scarlet fever in various countries in recent years, accelerating the development of a safe and effective vaccine remains a high priority. When developing a GAS vaccine, many factors need to be considered, including the selection of antigen epitopes, avoidance of self-response, and vaccine coverage. Given the challenges in GAS vaccine development, this review describes the important virulence factors that induce disease by GAS infection and how this has influenced the progression of vaccine development efforts, focusing on several candidate vaccines that are further along in development.

Precise Orchestration of Gasdermins' Pore-Forming Function by Posttranslational Modifications in Health and Disease

Gasdermins (GSDMs) serve as pivotal executors of pyroptosis and play crucial roles in host defence, cytokine secretion, innate immunity, and cancer. However, excessive or inappropriate GSDMs activation is invariably accompanied by exaggerated inflammation and results in tissue damage. In contrast, deficient or impaired activation of GSDMs often fails to promptly eliminate pathogens, leading to the increasing severity of infections. The activity of GSDMs requires meticulous regulation. The dynamic modulation of GSDMs involves many aspects, including autoinhibitory structures, proteolytic cleavage, lipid binding and membrane translocation (oligomerization and pre-pore formation), oligomerization (pore formation) and pore removal for membrane repair. As the most comprehensive and efficient regulatory pathway, posttranslational modifications (PTMs) are widely implicated in the regulation of these aspects. In this comprehensive review, we delve into the complex mechanisms through which a variety of proteases cleave GSDMs to enhance or hinder their function. Moreover, we summarize the intricate regulatory mechanisms of PTMs that govern GSDMs-induced pyroptosis.

Steroidal saponins PPI/CCRIS/PSV induce cell death in pancreatic cancer cell through GSDME-dependent pyroptosis

Pancreatic cancer is highly aggressive and lethal, and treatment options for it are limited. Gasdermin E (GSDME) is highly expressed in pancreatic cancer and can induce pyroptosis. In this type of programmed cell death, cells swell and emit large gas bubbles through their plasma membranes. Hence, GSDME induction is potentially an efficacious therapeutic approach against pancreatic cancer. In the present study, we found that the steroidal saponins polyphyllin I (PPI), collettiside III (CCRIS), and paris saponin V (PSV) significantly inhibited PANC-1, AsPC-1, and BxPC-3 cell proliferation. PPI/CCRIS/PSV altered the morphology of PANC-1 cells and induced the release of lactate dehydrogenase (LDH) from them. Therefore, these three constituents caused PANC-1 cells to undergo pyroptosis. This conclusion was confirmed by propidium iodide (PI) staining and flow cytometry assays. The present work also revealed that PPI/CCRIS/PSV induced pyroptosis via GSDME rather than gasdermin D (GSDMD). Whereas PPI/CCRIS/PSV induced caspase-3 to cleave GSDME, it had no such effect on GSDMD. We also established a PANC-1 xenograft tumor model in BALB/c nude mice and administered CCRIS to them as this compound demonstrated the most substantial pyroptotic effect in the in vitro experiments. This treatment significantly inhibited tumor growth in the mice by activating GSDME-dependent pyroptosis. This research demonstrates demonstrate that pyroptosis induction by PPI/CCRIS/PSV has important implications in basic science and clinical medicine. Future investigations should endeavor to determine the benefits and risks associated with the administration of these steroidal saponins as anti-PDAC therapy.

The gasdermins: a pore-forming protein family expressed in the epidermis

Gasdermins comprise a family of pore-forming proteins, which play critical roles in (auto)inflammatory diseases and cancer. They are expressed as self-inhibited precursor proteins consisting of an aminoterminal cytotoxic effector domain (NT-GSDM) and a carboxyterminal inhibitor domain (GSDM-CT) separated by an unstructured linker region. Proteolytic processing in the linker region liberates NT-GSDM, which translocates to membranes, forms oligomers, and induces membrane permeabilization, which can disturb the cellular equilibrium that can lead to cell death. Gasdermin activation and pore formation are associated with inflammation, particularly when induced by the inflammatory protease caspase-1 upon inflammasome activation. These gasdermin pores allow the release of the pro-inflammatory cytokines interleukin(IL)-1β and IL-18 and induce a lytic type of cell death, termed pyroptosis that supports inflammation, immunity, and tissue repair. However, even at the cellular level, the consequences of gasdermin activation are diverse and range from induction of programmed cell death - pyroptosis or apoptosis - to poorly characterized protective mechanisms. The specific effects of gasdermin activation can vary between species, cell types, the membrane that is being permeabilized (plasma membrane, mitochondrial membrane, etc.), and the overall biological state of the local tissue/cells. In epithelia, gasdermins seem to play crucial roles. Keratinocytes represent the main cell type of the epidermis, which is the outermost skin layer with an essential barrier function. Compared to other tissues, keratinocytes express all members of the gasdermin family, in part in a differentiation-specific manner. That raises questions regarding the specific roles of individual GSDM family members in the skin, the mechanisms and consequences of their activation, and the potential crosstalk between them. In this review, we summarize the current knowledge about gasdermins with a focus on keratinocytes and the skin and discuss the possible roles of the different family members in immunity and disease.

In Silico Identification and Validation of Pyroptosis-Related Genes in Chlamydia Respiratory Infection

The incidence of Chlamydia trachomatis respiratory infection is increasing, and its pathogenesis is still unclear. Pyroptosis, as a mode of inflammatory cell death, plays a vital role in the occurrence and development of Chlamydia trachomatis respiratory infection. In this study, the potential pyroptosis-related genes involved in Chlamydia trachomatis respiratory infection were identified by constructing a mouse model of C. muridarum infection combined with bioinformatics analysis. Through in-depth analysis of the RNA sequencing data, 13 differentially expressed pyroptosis-related genes were screened, including 1 downregulated gene and 12 upregulated genes. Gene ontology (GO) analysis showed that these genes mainly regulate inflammatory responses and produce IL-1β. Protein-protein interaction network analysis identified eight hub genes of interest: Tnf, Tlr2, Il1b, Nlrp3, Tlr9, Mefv, Zbp1 and Tnfaip3. Through quantitative real-time PCR (qPCR) analysis, we found that the expression of these genes in the lungs of C. muridarum-infected mice was significantly reduced, consistent with the bioinformatics results. At the same time, we detected elevated levels of caspase-3, gasdermin D and gasdermin E proteins in the lungs of C. muridarum-infected mice, demonstrating that Chlamydia trachomatis infection does induce pyroptosis. We then predicted nine miRNAs targeting these hub genes and constructed a key competitive endogenous RNA (ceRNA) network. In summary, we identified six key pyroptosis-related genes involved in Chlamydia trachomatis respiratory infection and constructed a ceRNA network associated with these genes. These findings will improve understanding of the molecular mechanisms underlying pyroptosis in Chlamydia trachomatis respiratory infections.

Unconventional protein secretion by gasdermin pores

Unconventional protein secretion (UPS) allows the release of specific leaderless proteins independently of the classical endoplasmic reticulum (ER)-Golgi secretory pathway. While it remains one of the least understood mechanisms in cell biology, UPS plays an essential role in immunity as it controls the release of the IL-1 family of cytokines, which coordinate host defense and inflammatory responses. The unconventional secretion of IL-1β and IL-18, the two most prominent members of the IL-1 family, is initiated by inflammasome complexes - cytosolic signaling platforms that are assembled in response to infectious or noxious stimuli. Inflammasomes activate inflammatory caspases that proteolytically mature IL-1β/- 18, but also induce pyroptosis, a lytic form of cell death. Pyroptosis is caused by gasdermin-D (GSDMD), a member of the gasdermin protein family, which is activated by caspase cleavage and forms large β-barrel plasma membrane pores. This pore-forming activity is shared with other family members that are activated during infection or upon treatment with chemotherapy drugs. While the induction of cell death was assumed to be the main function of gasdermin pores, accumulating evidence suggests that they have also non-lytic functions, such as in the release of cytokines and alarmins, or in regulating ion fluxes. This has raised the possibility that gasdermin pores are one of the main mediators of UPS. Here, I summarize and discuss new insights into gasdermin activation and pore formation, how gasdermin pores achieve selective cargo release, and how gasdermin pore formation and ninjurin-1-driven plasma membrane rupture are executed and regulated.

Gasdermins gone wild: new roles for GSDMs in regulating cellular homeostasis

Since their discovery, members of the gasdermin (GSDM) family of proteins have been firmly established as executors of pyroptosis, with the N-terminal fragment of most GSDMs capable of forming pores in the plasma membrane. More recent findings suggest that some GSDMs can drive additional cell death pathways, such as apoptosis and necroptosis, through mechanisms independent of plasma membrane perforation. There is also emerging evidence that by associating with cellular compartments such as mitochondria, peroxisomes, endosomes, and the nucleus, GSDMs regulate cell death-independent aspects of cellular homeostasis. Here, we review the diversity of GSDM function across several cell types and explore how various cellular stresses can promote relocalization - and thus refunctionalization - of GSDMs.

Pyroptosis in defense against intracellular bacteria

Pathogenic microbes invade the human body and trigger a host immune response to defend against the infection. In response, host-adapted pathogens employ numerous virulence strategies to overcome host defense mechanisms. As a result, the interaction between the host and pathogen is a dynamic process that shapes the evolution of the host's immune response. Among the immune responses against intracellular bacteria, pyroptosis, a lytic form of cell death, is a crucial mechanism that eliminates replicative niches for intracellular pathogens and modulates the immune system by releasing danger signals. This review focuses on the role of pyroptosis in combating intracellular bacterial infection. We examine the cell type specific roles of pyroptosis in neutrophils and intestinal epithelial cells. We discuss the regulatory mechanisms of pyroptosis, including its modulation by autophagy and interferon-inducible GTPases. Furthermore, we highlight that while host-adapted pathogens can often subvert pyroptosis, environmental microbes are effectively eliminated by pyroptosis.

Gasdermin A Is Required for Epidermal Cornification during Skin Barrier Regeneration and in an Atopic Dermatitis-Like Model

Atopic dermatitis is featured with impaired skin barrier. The stratum corneum and the intercellular tight junctions constitute the permeability barrier, which is essential to protect water loss in the host and prevent pathogen entry. The epidermal barrier is constantly renewed by differentiating keratinocytes through cornification, during which autophagy contributes to elimination of organelles and nucleus. The human GSDMA and its mouse homologs Gsdma1-3 are expressed in the suprabasal epidermis. Although a pyroptotic role of GSDMA/Gsdma1 in host defense against Streptococcus pyogenes has been reported, the physiological function of Gsdma1/a2/a3 in epidermal homeostasis remains elusive. Here, through repeated epidermal barrier disruption, we found that tight junction formation and stratum corneum maturation were defective in the Gsdma1/a3-deficient epidermis. Using comparative gene profiling analysis, mitochondrial respiration measurement, and in vivo tracing of mitophagy, our data indicate that Gsdma1/a3 activation leads to mitochondrial dysfunction and subsequently facilitates mitochondrial turnover and epidermal cornification. In calcipotriol (MC903)-induced atopic dermatitis-like animal model, we showed that Gsdma1/a3-deficiency selectively enhanced the T helper type 2 response. Remarkably, the GSDMA expression is reduced in the epidermis of patients with atopic dermatitis compared with that of normal individuals. Gsdma1/a3-deficiency might be involved in atopic dermatitis pathogenesis, likely through GSDMA-mediated epidermal differentiation and cornification.

Pyroptosis modulation by bacterial effector proteins

Pyroptosis is a proinflammatory form of programmed cell death featured with membrane pore formation that causes cellular swelling and allows the release of intracellular inflammatory mediators. This cell death process is elicited by the activation of the pore-forming proteins named gasdermins, and is intricately orchestrated by diverse regulatory factors in mammalian hosts to exert a prompt immune response against infections. However, growing evidence suggests that bacterial pathogens have evolved to regulate host pyroptosis for evading immune clearance and establishing progressive infection. In this review, we highlight current understandings of the functional role and regulatory network of pyroptosis in host antibacterial immunity. Thereafter, we further discuss the latest advances elucidating the mechanisms by which bacterial pathogens modulate pyroptosis through adopting their effector proteins to drive infections. A better understanding of regulatory mechanisms underlying pyroptosis at the interface of host-bacterial interactions will shed new light on the pathogenesis of infectious diseases and contribute to the development of promising therapeutic strategies against bacterial pathogens.

Application of pyroptosis in tumor research (Review)

As a potent clinical strategy, cancer therapy has sparked an academic boom over the past few years. Immune checkpoint inhibitors (ICIs) have been demonstrated to be highly successful. These achievements have progressed cancer treatment and have made an indelible mark on cancer. However, the inherent complexity of cancer means that only part of the population can benefit from this treatment. Pyroptosis is a new suicidal cellular mechanism that induces inflammation by releasing immunogenic cellular components. Inflammatory signaling cascades mediated by pyroptosis commonly inspire numerous cell lysis in immune diseases. Contrariwise, this consequence may be a promising target in cancer research. Therefore, the present study briefly described programmed cell death processes and their potential roles in cancer. Because of the rapid development of bioengineering in cancer, the present study also examined the associated scaffolding available for cancer, highlighting advances in tumor engineering approaches. Ultimately, an improved understanding of pyroptosis and tumor scaffolding might shed light on a combination that can be manipulated for therapeutic purposes.

Pyroptosis and the cellular consequences of gasdermin pores

The family of gasdermin proteins plays a key role in the host response against external and internal pathogenic signals by mediating the form of inflammatory regulated cell death known as pyroptosis. One of the most well-studied gasdermins within innate immunity is gasdermin D, which is cleaved, oligomerizes, and forms plasma membrane pores. Gasdermin D pores lead to a number of downstream cellular consequences including plasma membrane rupture, or cell lysis. In this review, we describe mechanisms of activation for each of the gasdermins, their cell type specificity and some disease associations. We then discuss downstream consequences of gasdermin pore formation, including cellular mechanisms of membrane repair. Finally, we present some important next steps to better understand pyroptosis and the cellular consequences of gasdermin pore formation.

Research Progress of Pyroptosis in Fatty Liver Disease

Fatty liver disease (FLD) is a clinical and pathological syndrome characterized by excessive fat deposition and even steatosis in hepatocytes. It has been proven that liver inflammation induced by fat and its derivatives are involved in the pathogenesis of FLD, while the precise mechanism still remains poorly understood. Pyroptosis is programmed inflammatory cell death driving cell swelling and membrane rupture. Pyroptosis is initiated by the activation of inflammasomes and caspases, which further cleaves and activates various gasdermins, leading to pores forming on the cell membrane and the release of pro-inflammatory factors such as interleukin (IL)-1β and IL-18. Recent studies demonstrate that pyroptosis occurs in hepatocytes, and inhibiting pyroptosis could effectively reduce fat deposition in the liver and could ameliorate inflammation from FLD, attracting our prime focus on the role of pyroptosis in FLD. In this manuscript, we reviewed the current understanding of pyroptosis in FLD development, aiming to provide new insights and potential research targets for the clinical diagnosis and intervention of FLD.

Tripping the wire: sensing of viral protease activity by CARD8 and NLRP1 inflammasomes

Host innate immune sensors are vital for the initial detection of pathogen infection. Such sensors thus need to constantly adapt in escalating evolutionary arms races with pathogens. Recently, two inflammasome-forming proteins, CARD8 and NLRP1, have emerged as innate immune sensors for the enzymatic activity of virus-encoded proteases. When cleaved within a rapidly evolving 'tripwire' region, CARD8 and NLRP1 assemble into inflammasomes that initiate pyroptotic cell death and pro-inflammatory cytokine release as a form of effector-triggered immunity. Short motifs in the CARD8 and NLRP1 tripwires mimic the protease-specific cleavage sites of picornaviruses, coronaviruses, and HIV-1, providing virus-specific sensing that can rapidly change between closely related hosts and within the human population. Recent work highlights the evolutionary arms races between viral proteases and NLRP1 and CARD8, including insights into the mechanisms of inflammasome activation, host diversity of viral sensing, and means that viruses have evolved to avoid tripping the wire.

Inhibition of CDC20 potentiates anti-tumor immunity through facilitating GSDME-mediated pyroptosis in prostate cancer

BACKGROUND

Increasing evidence suggests that immunotherapy, especially immune checkpoint inhibitors (ICIs), has the potential to facilitate long-term survival in various cancer besides prostate cancer. Emerging evidence indicated that pyroptosis, an immunogenic form of cell death, could trigger an anti-tumor immune microenvironment and enhance the effectiveness of immunotherapy. Nevertheless, the mechanism underlying the regulation of pyroptosis signaling in prostate cancer remains unclear.

METHODS

The differential expression of human E3 ligases in prostate cancer was integratedly analyzed from five independent public datasets. Moreover, the immunohistochemistry analysis of a tissue microarray derived from prostate cancer patients confirmed the results from the bioinformatic analysis. Furthermore, prostate cancer cell lines were evaluated via the next-generation RNA sequencing to assess transcriptomic profile upon CDC20 depletion. Next, qRT-PCR, Western blotting, cycloheximide assay, immunoprecipitation, and ubiquitination assay were employed to explore the correlation and interaction between CDC20 and GSDME. Both immune-deficient and immune-competent murine models were utilized to examine the anti-tumor efficacy of CDC20 inhibition with or without the anti-PD1 antibodies, respectively. To analyze the immune microenvironment of the xenografts, the tumor tissues were examined by immunohistochemistry and flow cytometry.

RESULTS

The analysis of multiple prostate cancer cohorts suggested that CDC20 was the most significantly over-expressed E3 ligase. In addition, CDC20 exerted a negative regulatory effect on the pyroptosis pathway by targeting GSDME for ubiquitination-mediated proteolysis in a degron-dependent manner. Knockdown of CDC20 leads to increased GSDME abundance and a transition from apoptosis to pyroptosis in response to death signals. Furthermore, in our syngeneic murine models, we found that depletion of CDC20 significantly enhances the anti-tumor immunity by promoting the infiltration of CD8⁺ T lymphocytes dependent on the existence of GSDME, as well as reducing myeloid immune cells. More importantly, Apcin, a small molecular inhibitor that targets CDC20, exhibited synergistic effects with anti-PD1-based immunotherapy in murine models of prostate cancer.

CONCLUSIONS

Overall, these findings provide new insights into the upstream regulation of GSDME-mediated pyroptosis by CDC20, which specifically interacts with GSDME and facilitates its ubiquitination in a degron-dependent manner. Importantly, our data highlight novel molecular pathways for targeting cellular pyroptosis and enhancing the effectiveness of anti-PD1-based immunotherapy.

Pyroptosis in renal inflammation and fibrosis: current knowledge and clinical significance

Pyroptosis is a novel inflammatory form of regulated cell death (RCD), characterized by cell swelling, membrane rupture, and pro-inflammatory effects. It is recognized as a potent inflammatory response required for maintaining organismal homeostasis. However, excessive and persistent pyroptosis contributes to severe inflammatory responses and accelerates the progression of numerous inflammation-related disorders. In pyroptosis, activated inflammasomes cleave gasdermins (GSDMs) and generate membrane holes, releasing interleukin (IL)-1β/18, ultimately causing pyroptotic cell death. Mechanistically, pyroptosis is categorized into caspase-1-mediated classical pyroptotic pathway and caspase-4/5/11-mediated non-classical pyroptotic pathway. Renal fibrosis is a kidney disease characterized by the loss of structural and functional units, the proliferation of fibroblasts and myofibroblasts, and extracellular matrix (ECM) accumulation, which leads to interstitial fibrosis of the kidney tubules. Histologically, renal fibrosis is the terminal stage of chronic inflammatory kidney disease. Although there is a multitude of newly discovered information regarding pyroptosis, the regulatory roles of pyroptosis involved in renal fibrosis still need to be fully comprehended, and how to improve clinical outcomes remains obscure. Hence, this review systematically summarizes the novel findings regarding the role of pyroptosis in the pathogenesis of renal fibrosis and discusses potential biomarkers and drugs for anti-fibrotic therapeutic strategies.

Bridging Pyroptosis and Immunity: A Comprehensive Study of the Pyroptosis-Related Long Non-Coding RNA Signature in Breast Cancer

Breast cancer continuously poses serious clinical challenges to human health due to its intrinsic heterogenicity and evolving drug resistance. Recently, increasing evidence has shown that pyroptosis, known as a programmed and inflammatory form of cell death, participates in tumorigenesis, progression, and remodeling of the tumor immune microenvironment (TIME). However, a comprehensive insight into pyroptosis-related signatures for breast cancer remains elusive. The current study established a pyroptosis-related lncRNA signature using transcriptome data and corresponding clinical information from The Cancer Genome Atlas (TCGA). Pyroptosis-related gene clusters, the associated differential expression in breast cancer patients' subtypes, and the potential mechanisms were all discussed. This integrative analysis revealed a unique signature underpinning the dichotomy of breast cancer progression and survival outcomes. Interestingly, the pyroptosis-related lncRNA signature was revealed as closely intertwined with the TIME. A correlation was established between the pyroptosis-related LncRNA signature and the TIME, underlying the mutual effect between pyroptosis and the immune responses implicated in breast cancer. The findings in this work underline the critical role exerted by pyroptosis in breast cancer, providing new insights into disease progression, prognosis, and therapeutic potential. This work has been poised to provide new avenues for personalized, immune-based cancer therapeutics by enhancing our understanding of pyroptosis in breast cancer.

Yersiniabactin-Producing E. coli Induces the Pyroptosis of Intestinal Epithelial Cells via the NLRP3 Pathway and Promotes Gut Inflammation

The high-pathogenicity island (HPI) was initially identified in Yersinia and can be horizontally transferred to Escherichia coli to produce yersiniabactin (Ybt), which enhances the pathogenicity of E. coli by competing with the host for Fe3+. Pyroptosis is gasdermin-induced necrotic cell death. It involves the permeabilization of the cell membrane and is accompanied by an inflammatory response. It is still unclear whether Ybt HPI can cause intestinal epithelial cells to undergo pyroptosis and contribute to gut inflammation during E. coli infection. In this study, we infected intestinal epithelial cells of mice with E. coli ZB-1 and the Ybt-deficient strain ZB-1Δirp2. Our findings demonstrate that Ybt-producing E. coli is more toxic and exacerbates gut inflammation during systemic infection. Mechanistically, our results suggest the involvement of the NLRP3/caspase-1/GSDMD pathway in E. coli infection. Ybt promotes the assembly and activation of the NLRP3 inflammasome, leading to GSDMD cleavage into GSDMD-N and promoting the pyroptosis of intestinal epithelial cells, ultimately aggravating gut inflammation. Notably, NLRP3 knockdown alleviated these phenomena, and the binding of free Ybt to NLRP3 may be the trigger. Overall, our results show that Ybt HPI enhances the pathogenicity of E. coli and induces pyroptosis via the NLRP3 pathway, which is a new mechanism through which E. coli promotes gut inflammation. Furthermore, we screened drugs targeting NLRP3 from an existing drug library, providing a list of potential drug candidates for the treatment of gut injury caused by E. coli.

Pyroptosis: A road to next-generation cancer immunotherapy

The goal of cancer immunotherapy is to clear tumor cells by activating antitumor immunity, especially by mobilizing tumor-reactive CD8+T cells. Pyroptosis, programmed lytic cell death mediated by gasdermin (GSDM), results in the release of cellular antigens, damage-associated molecular patterns (DAMPs) and cytokines. Therefore, pyroptotic tumor cell-derived tumor antigens and DAMPs not only reverse immunosuppression of the tumor microenvironment (TME) but also enhance tumor antigen presentation by dendritic cells, leading to robust antitumor immunity. Exploring nanoparticles and other approaches to spatiotemporally control tumor pyroptosis by regulating gasdermin expression and activation is promising for next-generation immunotherapy.

Pathogenesis, epidemiology and control of Group A Streptococcus infection

Streptococcus pyogenes (Group A Streptococcus; GAS) is exquisitely adapted to the human host, resulting in asymptomatic infection, pharyngitis, pyoderma, scarlet fever or invasive diseases, with potential for triggering post-infection immune sequelae. GAS deploys a range of virulence determinants to allow colonization, dissemination within the host and transmission, disrupting both innate and adaptive immune responses to infection. Fluctuating global GAS epidemiology is characterized by the emergence of new GAS clones, often associated with the acquisition of new virulence or antimicrobial determinants that are better adapted to the infection niche or averting host immunity. The recent identification of clinical GAS isolates with reduced penicillin sensitivity and increasing macrolide resistance threatens both frontline and penicillin-adjunctive antibiotic treatment. The World Health Organization (WHO) has developed a GAS research and technology road map and has outlined preferred vaccine characteristics, stimulating renewed interest in the development of safe and effective GAS vaccines.

Resistance of hypervirulent Klebsiella pneumoniae to cathepsin B-mediated pyroptosis in murine macrophages

Introduction

Hypervirulent Klebsiella pneumoniae (hvKp) has emerged as a clinically significant global pathogen in the last decade. However, the host immune responses of the macrophages during hvKp infection are largely unknown. In the present study, we aimed to compare the cytotoxic effects of hvKp and classical K. pneumoniae (cKp) in murine macrophages.

Results

We found that the activation of caspase-1 -dependent pyroptosis was higher in cKp-infected macrophages compared with that in hvKp-infected macrophages. In Caspase-1 deficiency macrophages, pyroptosis diminished during infection. Both hvKp and cKp strains led to nucleotide-binding and oligomerization domain-like receptor protein 3 (NLRP3) inflammasome formation and lysosomal cathepsin B activation, thus resulting in pyroptosis. Compared with the cKp strain, the hvKp strain inhibited these phenomena in murine macrophages.

Conclusion

HvKp infection resulted in different levels of pyroptosis via the activation of cathepsin B-NLRP3-caspase-1 in murine macrophages. Therefore, the manipulation of pyroptotic cell death is a potential target for host response during hvKp infection in macrophages.

Molecular mechanisms of gasdermin D pore-forming activity

The regulated disruption of the plasma membrane, which can promote cell death, cytokine secretion or both is central to organismal health. The protein gasdermin D (GSDMD) is a key player in this process. GSDMD forms membrane pores that can promote cytolysis and the release of interleukin-1 family cytokines into the extracellular space. Recent discoveries have revealed biochemical and cell biological mechanisms that control GSDMD pore-forming activity and its diverse downstream immunological effects. Here, we review these multifaceted regulatory activities, including mechanisms of GSDMD activation by proteolytic cleavage, dynamics of pore assembly, regulation of GSDMD activities by posttranslational modifications, membrane repair and the interplay of GSDMD and mitochondria. We also address recent insights into the evolution of the gasdermin family and their activities in species across the kingdoms of life. In doing so, we hope to condense recent progress and inform future studies in this rapidly moving field in immunology.

Non-lethal outcomes of engaging regulated cell death pathways in cancer

Regulated cell death (RCD) is essential for successful systemic cancer therapy. Yet, the engagement of RCD pathways does not inevitably result in cell death. Instead, RCD pathways can take part in diverse biological processes if the cells survive. Consequently, these surviving cells, for which we propose the term 'flatliners', harbor important functions. These evolutionarily conserved responses can be exploited by cancer cells to promote their own survival and growth, with challenges and opportunities for cancer therapy.

Role of pyroptosis in the pathogenesis and treatment of diseases

Programmed cell death (PCD) is regarded as a pathological form of cell death with an intracellular program mediated, which plays a pivotal role in maintaining homeostasis and embryonic development. Pyroptosis is a new paradigm of PCD, which has received increasing attention due to its close association with immunity and disease. Pyroptosis is a form of inflammatory cell death mediated by gasdermin that promotes the release of proinflammatory cytokines and contents induced by inflammasome activation. Recently, increasing evidence in studies shows that pyroptosis has a crucial role in inflammatory conditions like cardiovascular diseases (CVDs), cancer, neurological diseases (NDs), and metabolic diseases (MDs), suggesting that targeting cell death is a potential intervention for the treatment of these inflammatory diseases. Based on this, the review aims to identify the molecular mechanisms and signaling pathways related to pyroptosis activation and summarizes the current insights into the complicated relationship between pyroptosis and multiple human inflammatory diseases (CVDs, cancer, NDs, and MDs). We also discuss a promising novel strategy and method for treating these inflammatory diseases by targeting pyroptosis and focus on the pyroptosis pathway application in clinics.

Pyroptosis: A promising target for lung cancer therapy

Pyroptosis is a type of programed cell death that differs from apoptosis, ferroptosis, or necrosis. Numerous studies have reported that it plays a critical role in tumorigenesis and modification of the tumor microenvironment in multiple tumors. In this review, we briefly describe the canonical, non-canonical, and alternative mechanisms of pyroptotic cell death. We also summarize the potential roles of pyroptosis in oncogenesis, tumor development, and lung cancer treatment, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy. Pyroptosis has double-edged effects on the modulation of the tumor environment and lung cancer treatment. Further exploration of pyroptosis-based drugs could provide novel therapeutic strategies for lung cancer.