The gasdermins, a protein family executing cell death and inflammation

Staphylococcus pseudintermedius induces pyroptosis of canine corneal epithelial cells by activating the ROS-NLRP3 signalling pathway

Staphylococcus pseudintermedius (S. pseudintermedius) is a common pathogen that causes canine corneal ulcers. However, the pathogenesis remained unclear. In this study, it has been demonstrated that S. pseudintermedius invaded canine corneal epithelial cells (CCECs) intracellularly, mediating oxidative damage and pyroptosis by promoting the accumulation of intracellular reactive oxygen species (ROS) and activating the NLRP3 inflammasome. The canine corneal stroma was infected with S. pseudintermedius to establish the canine corneal ulcer model in vivo. The intracellular infectious model in CCECs was established in vitro to explore the mechanism of the ROS - NLRP3 signalling pathway during the S. pseudintermedius infection by adding NAC or MCC950. Results showed that the expression of NLRP3 and gasdermin D (GSDMD) proteins increased significantly in the infected corneas (p < 0.01). The intracellular infection of S. pseudintermedius was confirmed by transmission electron microscopy and immunofluorescent 3D imaging. Flow cytometry analysis revealed that ROS and pyroptosis rates increased in the experimental group in contrast to the control group (p < 0.01). Furthermore, NAC or MCC950 inhibited activation of the ROS - NLRP3 signalling pathway and pyroptosis rate significantly, by suppressing pro-IL-1β, cleaved-IL-1β, pro-caspase-1, cleaved-caspase-1, NLRP3, GSDMD, GSDMD-N, and HMGB1 proteins. Thus, the research confirmed that oxidative damage and pyroptosis were involved in the process of CCECs infected with S. pseudintermedius intracellularly by the ROS - NLRP3 signalling pathway. The results enrich the understanding of the mechanisms of canine corneal ulcers and facilitate the development of new medicines and prevention measures.

The role of extracellular vesicles in pyroptosis-mediated infectious and non-infectious diseases

Pyroptosis, a lytic and pro-inflammatory cell death, is important in various pathophysiological processes. Host- and bacteria-derived extracellular vesicles (EVs), as natural nanocarriers messengers, are versatile mediators of intercellular communication between different types of cells. Recently, emerging research has suggested that EVs exhibit multifaceted roles in disease progression by manipulating pyroptosis. This review focuses on new findings concerning how EVs shape disease progression in infectious and non-infectious diseases by regulating pyroptosis. Understanding the characteristics and activity of EVs-mediated pyroptotic death may conducive to the discovery of novel mechanisms and more efficient therapeutic targets in infectious and non-infectious diseases.

Mycobacterium tuberculosis Utilizes Serine/Threonine Kinase PknF to Evade NLRP3 Inflammasome-driven Caspase-1 and RIPK3/Caspase-8 Activation in Murine Dendritic Cells

Dendritic cells (DCs) are crucial for initiating the acquired immune response to infectious diseases such as tuberculosis. Mycobacterium tuberculosis has evolved strategies to inhibit activation of the NLRP3 inflammasome in macrophages via its serine/threonine protein kinase, protein kinase F (PknF). It is not known whether this pathway is conserved in DCs. In this study, we show that the pknF deletion mutant of M. tuberculosis (MtbΔpknF) compared with wild-type M. tuberculosis-infected cells induces increased production of IL-1β and increased pyroptosis in murine bone marrow-derived DCs (BMDCs). As shown for murine macrophages, the enhanced production of IL-1β postinfection of BMDCs with MtbΔpknF is dependent on NLRP3, ASC, and caspase-1/11. In contrast to macrophages, we show that MtbΔpknF mediates RIPK3/caspase-8-dependent IL-1β production in BMDCs. Consistently, infection with MtbΔpknF results in increased activation of caspase-1 and caspase-8 in BMDCs. When compared with M. tuberculosis-infected cells, the IL-6 production by MtbΔpknF-infected cells was unchanged, indicating that the mutant does not affect the priming phase of inflammasome activation. In contrast, the activation phase was impacted because the MtbΔpknF-induced inflammasome activation in BMDCs depended on potassium efflux, chloride efflux, reactive oxygen species generation, and calcium influx. In conclusion, PknF is important for M. tuberculosis to evade NLRP3 inflammasome-mediated activation of caspase-1 and RIPK3/caspase-8 pathways in BMDCs.

Pyroptosis: A promising biomarker for predicting colorectal cancer prognosis and enhancing immunotherapy efficacy

In this editorial, we comment on the article by Zhu et al published in the recent issue of the World Journal of Clinical Oncology. We focus specifically on the characteristics and mechanisms of pyroptosis and the impact of changes in the tumor immune microenvironment (TIME) on cancer prognosis. Pyroptosis is a distinct form of programmed cell death; its occurrence can change the TIME and regulate the growth and spread of tumors and therefore is significantly correlated with cancer prognosis. Previous research has demonstrated that pyroptosis-related genes can be used in prognostic models for various types of cancer. These models enhance the mechanistic understanding of tumor evolution and serve as valuable guides for clinical treatment decision-making. Nevertheless, further studies are required to thoroughly understand the function of pyroptosis within the TIME and to assess its mode of action. Such studies should reveal new tumor therapeutic targets and more successful tumor immunotherapy strategies.

Septins promote macrophage pyroptosis by regulating gasdermin D cleavage and ninjurin-1-mediated plasma membrane rupture

The septin cytoskeleton is primarily known for roles in cell division and host defense against bacterial infection. Despite recent insights, the full breadth of roles for septins in host defense is poorly understood. In macrophages, Shigella induces pyroptosis, a pro-inflammatory form of cell death dependent upon gasdermin D (GSDMD) pores at the plasma membrane and cell surface protein ninjurin-1 (NINJ1) for membrane rupture. Here, we discover that septins promote macrophage pyroptosis induced by lipopolysaccharide (LPS)/nigericin and Shigella infection, but do not affect cytokine expression or release. We observe that septin filaments assemble at the plasma membrane, and cleavage of GSDMD is impaired in septin-depleted cells. We found that septins regulate mitochondrial dynamics and the expression of NINJ1. Using a Shigella-zebrafish infection model, we show that septin-mediated pyroptosis is an in vivo mechanism of infection control. The discovery of septins as a mediator of pyroptosis may inspire innovative anti-bacterial and anti-inflammatory treatments.

Reuterin promotes pyroptosis in hepatocellular cancer cells through mtDNA-mediated STING activation and caspase 8 expression

Hepatocellular carcinoma (HCC) is the most common form of liver cancer with poor prognosis. The available drugs for advanced HCC are limited and substantial therapeutic advances including new drugs and new combination therapies are still in urgent need. In this study, we found that the major metabolite of Lactobacillus reuteri (L. reuteri), reuterin showed great anti-HCC potential and could help in sorafenib treatment. Reuterin treatment impaired mitophagy and caused the aberrant clustering of mitochondrial nucleoids to block mitochondrial DNA (mtDNA) replication and mitochondrial fission, which could promote mtDNA leakage and subsequent STING activation in HCC cells. STING could activate pyroptosis and necroptosis, while reuterin treatment also induced caspase 8 expression to inhibit necroptosis through cleaving RIPK3 in HCC cells. Thus, pyroptosis was the main death form in reuterin-treated HCC cells and STING suppression remarkably rescued the growth inhibitory effect of reuterin and concurrently knockdown caspase 8 synergized to restrain the induction of pyroptosis. In conclusion, our study explains the detailed molecular mechanisms of the antitumor effect of reuterin and reveals its potential to perform as a combinational drug for HCC treatment.

Gasdermin D cysteine residues synergistically control its palmitoylation-mediated membrane targeting and assembly

Gasdermin D (GSDMD) executes the cell death program of pyroptosis by assembling into oligomers that permeabilize the plasma membrane. Here, by single-molecule imaging, we elucidate the yet unclear mechanism of Gasdermin D pore assembly and the role of cysteine residues in GSDMD oligomerization. We show that GSDMD preassembles at the membrane into dimeric and trimeric building blocks that can either be inserted into the membrane, or further assemble into higher-order oligomers prior to insertion into the membrane. The GSDMD residues Cys39, Cys57, and Cys192 are the only relevant cysteines involved in GSDMD oligomerization. S-palmitoylation of Cys192, combined with the presence of negatively-charged lipids, controls GSDMD membrane targeting. Simultaneous Cys39/57/192-to-alanine (Ala) mutations, but not Ala mutations of Cys192 or the Cys39/57 pair individually, completely abolish GSDMD insertion into artificial membranes as well as into the plasma membrane. Finally, either Cys192 or the Cys39/Cys57 pair are sufficient to enable formation of GSDMD dimers/trimers, but they are all required for functional higher-order oligomer formation. Overall, our study unveils a cooperative role of Cys192 palmitoylation-mediated membrane binding and Cys39/57/192-mediated oligomerization in GSDMD pore assembly. This study supports a model in which Gasdermin D oligomerization relies on a two-step mechanism mediated by specific cysteine residues.

Photocatalytic Carbon Dots-Triggered Pyroptosis for Whole Cancer Cell Vaccines

Manufacturing whole cancer cell vaccines (WCCV) with both biosafety and efficacy is crucial for tumor immunotherapy. Pyroptotic cancer cells, due to their highly immunogenic properties, present a promising avenue for the development of WCCV. However, the successful development of WCCV based on pyroptotic cancer cells is yet to be accomplished. Here, a facile strategy that utilized photocatalytic carbon dots (CDs) to induce pyroptosis of cancer cells for fabricating WCCV is reported. Photocatalytic CDs are capable of generating substantial amounts of hydroxyl radicals and can effectively decrease cytoplasmic pH values under white light irradiation. This process efficiently triggers cancer cell pyroptosis through the reactive oxygen species (ROS)-mitochondria-caspase 3-gasdermin E pathway and the proton motive force-driven mitochondrial ATP synthesis pathway. Moreover, in vitro, these photocatalytic CDs-induced pyroptotic cancer cells (PCIP) can hyperactivate macrophage (M0-M1) with upregulation of major histocompatibility complex class II expression. In vivo, PCIP induced specific immune-preventive effects in melanoma and breast cancer mouse models through anticancer immune memory, demonstrating effective WCCV. This work provides novel insights for inducing cancer cell pyroptosis and bridges the gap in the fabrication of WCCV based on pyroptotic cancer cells.

Pyroptosis and the fight against lung cancer

Pyroptosis, a newly characterized type of inflammatory programmed cell death (PCD), is usually triggered by multiple inflammasomes which can recognize different danger or damage-associated molecular patterns (DAMPs), leading to the activation of caspase-1 and the cleavage of gasdermin D (GSDMD). Gasdermin family pore-forming proteins are the executers of pyroptosis and are normally maintained in an inactive state through auto-inhibition. Upon caspases mediated cleavage of gasdermins, the pro-pyroptotic N-terminal fragment is released from the auto-inhibition of C-terminal fragment and oligomerizes, forming pores in the plasma membrane. This results in the secretion of interleukin (IL)-1β, IL-18, and high-mobility group box 1 (HMGB1), generating osmotic swelling and lysis. Current therapeutic approaches including chemotherapy, radiotherapy, molecularly targeted therapy and immunotherapy for lung cancer treatment efficiently force the cancer cells to undergo pyroptosis, which then generates local and systemic antitumor immunity. Thus, pyroptosis is recognized as a new therapeutic regimen for the treatment of lung cancer. In this review, we briefly describe the signaling pathways involved in pyroptosis, and endeavor to discuss the antitumor effects of pyroptosis and its potential application in lung cancer therapy, focusing on the contribution of pyroptosis to microenvironmental reprogramming and evocation of antitumor immune response.

Endoplasmic reticulum-targeted iridium(III) photosensitizer induces pyroptosis for augmented tumor immunotherapy

An ideal tumor treatment strategy involves therapeutic approaches that can enhance the immunogenicity of the tumor microenvironment while simultaneously eliminating the primary tumor. A cholic acid-modified iridium(III) (Ir3) photosensitizer, targeted to the endoplasmic reticulum (ER), has been reported to exhibit potent type I and type II photodynamic therapeutic effects against triple-negative breast cancer (MDA-MB-231). This photosensitizer induces pyroptotic cell death mediated by gasdermin E (GSDME) through photodynamic means and enhances tumor immunotherapy. Mechanistic studies have revealed that complex Ir3 induces characteristics of damage-related molecular patterns (DAMPs) in MDA-MB-231 breast cancer cells under light conditions. These include cell-surface calreticulin (CRT) eversion, extracellular high mobility group box 1 (HMGB1) and ATP release, accompanied by ER stress and increased reactive oxygen species (ROS). Consequently, complex Ir3 promotes dendritic cell maturation and antigen presentation under light conditions, fully activates T cell-dependent immune response in vivo, and ultimately eliminates distant tumors while destroying primary tumors. In conclusion, immune regulation and targeted intervention mediated by metal complexes represent a new and promising approach to tumor therapy. This provides an effective strategy for the development of combined targeted therapy and immunotherapy.

Igniting hope: Harnessing NLRP3 inflammasome-GSDMD-mediated pyroptosis for cancer immunotherapy

In the contemporary landscape of oncology, immunotherapy, represented by immune checkpoint blockade (ICB) therapy, stands out as a beacon of innovation in cancer treatment. Despite its promise, the therapy's progression is hindered by suboptimal clinical response rates. Addressing this challenge, the modulation of the NLRP3 inflammasome-GSDMD-mediated pyroptosis pathway holds promise as a means to augment the efficacy of immunotherapy. In the pathway, the NLRP3 inflammasome serves as a pivotal molecular sensor that responds to inflammatory stimuli within the organism. Its activation leads to the release of cytokines interleukin 1β and interleukin 18 through the cleavage of GSDMD, thereby forming membrane pores and potentially resulting in pyroptosis. This cascade of processes exerts a profound impact on tumor development and progression, with its function and expression exhibiting variability across different tumor types and developmental stages. Consequently, understanding the specific roles of the NLRP3 inflammasome and GSDMD-mediated pyroptosis in diverse tumors is imperative for comprehending tumorigenesis and crafting precise therapeutic strategies. This review aims to elucidate the structure and activation mechanisms of the NLRP3 inflammasome, as well as the induction mechanisms of GSDMD-mediated pyroptosis. Additionally, we provide a comprehensive overview of the involvement of this pathway in various cancer types and its applications in tumor immunotherapy, nanotherapy, and other fields. Emphasis is placed on the feasibility of leveraging this approach to enhance ICB therapy within the field of immunotherapy. Furthermore, we discuss the potential applications of this pathway in other immunotherapy methods, such as chimeric antigen receptor T-cell (CAR-T) therapy and tumor vaccines.

Necrostatin-1 protects corneal epithelial cells by inhibiting the RIPK1/RIPK3/MLKL cascade in a benzalkonium chloride-induced model of necroptosis

PURPOSE

Benzalkonium chloride (BAC) is commonly used as a preservative in ophthalmic medications, despite its potential to induce chemical injury. Extensive research has demonstrated that BAC can lead to adverse effects, including injuries to the ocular surface. Our study aimed to elucidate the underlying mechanism of necroptosis induced by BAC.

METHODS

Human corneal epithelial (HCE) cells and mouse corneas were subjected to chemical injury, and the necrostatin-1 (Nec1) group was compared to the dimethylsulfoxide (DMSO) group. The extent of damage to HCE cells was assessed using CCK-8 and flow cytometry. Hematoxylin and eosin staining, as well as fluorescein sodium staining, were used to detect and characterize corneal injury. The activation of inflammatory cytokines and necroptosis-related proteins and genes was evaluated using Western blotting, immunofluorescence staining, and quantitative RT‒PCR.

RESULTS

In our study, the induction of necroptosis by a hypertonic solution was not observed. However, necroptosis was observed in HCE cells exposed to NaOH and BAC, which activated the receptor-interacting protein kinase 1 (RIPK1) - receptor-interacting protein kinase 3 (RIPK3) - mixed lineage kinase domain-like protein (MLKL) signaling pathway. In mouse corneal tissues, BAC could induce necroptosis and inflammation. The administration of Nec1 mitigated the inflammatory response and ocular surface damage caused by BAC-induced necroptosis in our experimental models. Furthermore, our in vivo experiments revealed that the severity of necroptosis was greater in the 3-day group than in the 7-day group.

CONCLUSIONS

Necroptosis plays a role in the pathological development of ocular surface injury caused by exposure to BAC. Furthermore, our study demonstrated that the administration of Nec1 could mitigate the pathological effects of necroptosis induced by BAC in clinical settings.

Inhibiting caspase-3/GSDME-mediated pyroptosis ameliorates septic lung injury in mice model

Acute lung injury is one of the most serious complications of sepsis, which is a common critical illness in clinic. This study aims to investigate the role of caspase-3/ gasdermin-E (GSDME)-mediated pyroptosis in sepsis-induced lung injury in mice model. Cecal ligation (CLP) operation was used to establish mice sepsis-induced lung injury model. Lung coefficient, hematoxylin and eosin staining and transmission electron microscopy were used to observe the lung injury degree. In addition, caspase-3-specific inhibitor Z-DEVD-FMK and GSDME-derived inhibitor AC-DMLD-CMK were used in CLP model, caspase-3 activity, GSDME immunofluorescence, serum lactate dehydrogenase (LDH) and interleukin-6 (IL-6) levels, TUNEL staining, and the expression levels of GSDME related proteins were detected. The mice in CLP group showed the increased expressions of cleaved-caspase-3 and GSDME-N terminal, destruction of lung structure, and the increases of LDH, IL-6, IL-18 and IL-1β levels, which were improved in mice treated with Z-DEVD-FMK or AC-DMLD-CMK. In conclusion, caspase-3/GSDME mediated pyroptosis is involved in the occurrence of sepsis-induced lung injury in mice model, inhibiting caspase-3 or GSDME can both alleviate lung injury.

The significant mechanism and treatments of cell death in heatstroke

With global warming, extreme environmental heat is becoming a social issue of concern, which can cause adverse health results including heatstroke (HS). Severe heat stress is characterized by cell death of direct heat damage, excessive inflammatory responses, and coagulation disorders that can lead to multiple organ dysfunction (MODS) and even death. However, the significant pathophysiological mechanism and treatment of HS are still not fully clear. Various modes of cell death, including apoptosis, pyroptosis, ferroptosis, necroptosis and PANoptosis are involved in MODS induced by heatstroke. In this review, we summarized molecular mechanism, key transcriptional regulation as for HSF1, NRF2, NF-κB and PARP-1, and potential therapies of cell death resulting in CNS, liver, intestine, reproductive system and kidney injury induced by heat stress. Understanding the mechanism of cell death provides new targets to protect multi-organ function in HS.

Systemic mechanisms of necrotic cell debris clearance

Necrosis is an overarching term that describes cell death modalities caused by (extreme) adverse conditions in which cells lose structural integrity. A guaranteed consequence of necrosis is the production of necrotic cell remnants, or debris. Necrotic cell debris is a strong trigger of inflammation, and although inflammatory responses are required for tissue healing, necrotic debris may lead to uncontrolled immune responses and collateral damage. Besides local phagocytosis by recruited leukocytes, there is accumulating evidence that extracellular mechanisms are also involved in necrotic debris clearance. In this review, we focused on systemic clearance mechanisms present in the bloodstream and vasculature that often cooperate to drive the clearance of cell debris. We reviewed the contribution and cooperation of extracellular DNases, the actin-scavenger system, the fibrinolytic system and reticuloendothelial cells in performing clearance of necrotic debris. Moreover, associations of the (mis)functioning of these clearance systems with a variety of diseases were provided, illustrating the importance of the mechanisms of clearance of dead cells in the organism.

1,8-cineole ameliorates experimental diabetic angiopathy by inhibiting NLRP3 inflammasome-mediated pyroptosis in HUVECs via SIRT2

Accumulating evidence strongly support the key role of NLRP3-mediated pyroptosis in the pathogenesis and progression of vascular endothelial dysfunction associated with diabetes mellitus. Various studies have demonstrated that the activation or upregulation of Silent Information Regulation 2 homolog 2 (SIRT2) exerts inhibitory effect on the expression of NLRP3. Although 1,8-cineole has been found to protect against endothelial dysfunction and cardiovascular diseases, its role and mechanism in diabetic angiopathy remain unknown. Therefore, the aim of this study was to investigate the ameliorative effect of 1,8-cineole through SIRT2 on pyroptosis associated with diabetic angiopathy in human umbilical vein endothelial cells (HUVECs) and to elucidate the underlying mechanism. The findings revealed that 1,8-cineole exhibited a protective effect against vascular injury and ameliorated pathological alterations in the thoracic aorta of diabetic mice. Moreover, it effectively mitigated pyroptosis induced by palmitic acid-high glucose (PA-HG) in HUVECs. Treatment with 1,8-cineole effectively restored the reduced levels of SIRT2 and suppressed the elevated expression of pyroptosis-associated proteins. Additionally, our findings demonstrated the occurrence of NLRP3 deacetylation and the physical interaction between NLRP3 and SIRT2. The SIRT2 inhibitor AGK2 and siRNA-SIRT2 effectively attenuated the effect of 1,8-cineole on NLRP3 deacetylation in HUVECs and compromised its inhibitory effect against pyroptosis in HUVECs. However, overexpression of SIRT2 inhibited PA-HG-induced pyroptosis in HUVECs. 1,8-Cineole inhibited the deacetylation of NLRP3 by regulating SIRT2, thereby reducing pyroptosis in HUVECs. In conclusion, our findings suggest that PA-HG-induced pyroptosis in HUVECs plays a crucial role in the development of diabetic angiopathy, which can be mitigated by 1,8-cineole.

Programmed cell death: NINJ1 and mechanisms of plasma membrane rupture

Lytic cell death culminates in cell swelling and plasma membrane rupture (PMR). The cellular contents released, including proteins, metabolites, and nucleic acids, can act as danger signals and induce inflammation. During regulated cell death (RCD), lysis is actively initiated and can be preceded by an initial loss of membrane integrity caused by pore-forming proteins, allowing small molecules and cytokines to exit the cell. A recent seminal discovery showed that ninjurin1 (NINJ1) is the common executioner of PMR downstream of RCD, resulting in the release of large proinflammatory molecules and representing a novel target of cell death-associated lysis. We summarize recent developments in understanding membrane integrity and rupture of the plasma membrane with a focus on NINJ1.

Urolithin A Protects against Hypoxia-Induced Pulmonary Hypertension by Inhibiting Pulmonary Arterial Smooth Muscle Cell Pyroptosis via AMPK/NF-κB/NLRP3 Signaling

Recent studies confirmed that pyroptosis is involved in the progression of pulmonary hypertension (PH), which could promote pulmonary artery remodeling. Urolithin A (UA), an intestinal flora metabolite of ellagitannins (ETs) and ellagic acid (EA), has been proven to possess inhibitory effects on pyroptosis under various pathological conditions. However, its role on PH remained undetermined. To investigate the potential of UA in mitigating PH, mice were exposed to hypoxia (10% oxygen, 4 weeks) to induce PH, with or without UA treatment. Moreover, in vitro experiments were carried out to further uncover the underlying mechanisms. The in vivo treatment of UA suppressed the progression of PH via alleviating pulmonary remodeling. Pyroptosis-related genes were markedly upregulated in mice models of PH and reversed after the administration of UA. In accordance with that, UA treatment significantly inhibited hypoxia-induced pulmonary arterial smooth muscle cell (PASMC) pyroptosis via the AMPK/NF-κB/NLRP3 pathway. Our results revealed that UA treatment effectively mitigated PH progression through inhibiting PASMC pyroptosis, which represents an innovative therapeutic approach for PH.

A human commensal-pathogenic fungus suppresses host immunity via targeting TBK1

Candida albicans stably colonizes humans but is the leading cause of hospital-acquired fungemia. Traditionally, masking immunogenic moieties has been viewed as a tactic for immune evasion. Here, we demonstrate that C. albicans blocks type I interferon (IFN-I) signaling via translocating an effector protein Cmi1 into host cells. Mechanistically, Cmi1 binds and inhibits TANK-binding kinase 1 (TBK1) to abrogate IFN-regulatory factor 3 (IRF3) phosphorylation, thereby suppressing the IFN-I cascade. Murine infection with a cmi1 mutant displays an exaggerated IFN-I response in both kidneys and bone-marrow-derived macrophages, leading to rapid fungal clearance and host survival. Remarkably, the lack of CMI1 compromises gut commensalism and increases IFN-I response in mouse colonic cells. These phenotypes of cmi1 are rescued by the depletion of IFN-I receptor. This work establishes the importance of TBK1 inhibition in fungal pathogenesis and reveals that a human commensal-pathogenic fungus significantly impacts host immunity during gut colonization and infection via delivering effector proteins into host cells.

Dual-Responsive Epigenetic Inhibitor Nanoprodrug Combined with Oncolytic Virus Synergistically Boost Cancer Immunotherapy by Igniting Gasdermin E-Mediated Pyroptosis

Cancer immunotherapy has emerged as a promising approach for the treatment of various cancers. However, the immunosuppressive tumor microenvironment (TME) limits the efficacy of current immunotherapies. In this study, we designed a dual-responsive DNA methyltransferase inhibitor nanoprodrug ACNPs for combination therapy with oncolytic herpes simplex virus (oHSV). We found that the epigenetic inhibitor 5-Azacytidine (5-Aza) upregulated gasdermin E (GSDME) expression at the gene level, whereas the oHSV decreased the ubiquitination and degradation of GSDME to elevate its levels. Based on these observations, we further discovered that ACNPs and oHSV synergistically enhanced GSDME-mediated pyroptosis. Additionally, the combination therapy of ACNPs and oHSV effectively inhibited tumor growth, remodeled the immunosuppressive TME, and improved the efficacy of immune checkpoint blockade (ICB) therapy. These results demonstrate the potential to overcome immunosuppression through synergistic combinations, offering a promising approach for cancer immunotherapy.

The Role and Therapeutic Potential of Pyroptosis in Colorectal Cancer: A Review

Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality worldwide. The unlimited proliferation of tumor cells is one of the key features resulting in the malignant development and progression of CRC. Consequently, understanding the potential proliferation and growth molecular mechanisms and developing effective therapeutic strategies have become key in CRC treatment. Pyroptosis is an emerging type of regulated cell death (RCD) that has a significant role in cells proliferation and growth. For the last few years, numerous studies have indicated a close correlation between pyroptosis and the occurrence, progression, and treatment of many malignancies, including CRC. The development of effective therapeutic strategies to inhibit tumor growth and proliferation has become a key area in CRC treatment. Thus, this review mainly summarized the different pyroptosis pathways and mechanisms, the anti-tumor (tumor suppressor) and protective roles of pyroptosis in CRC, and the clinical and prognostic value of pyroptosis in CRC, which may contribute to exploring new therapeutic strategies for CRC.

The impact of AIM2 inflammasome-induced pyroptosis on acute gouty arthritis and asymptomatic hyperuricemia patients

Objective

This study aimed to evaluate the role of absent in melanoma 2 (AIM2) inflammasome-mediated pyroptosis in the pathogenesis of acute gouty arthritis (AGA) and asymptomatic hyperuricemia(AHU).

Methods

A cohort of 30 AGA patients, 30 AHU individuals, and 30 healthy controls (HC) was assembled. Demographic and biochemical data, along with blood samples, were collected. Serum double-stranded DNA (dsDNA) levels were quantified using a fluorescent assay. Transcriptomic and proteomic analysis of AIM2, Caspase-1, GSDMD, IL-1β, and IL-18 in peripheral blood mononuclear cells was performed using qRT-PCR and Western blot. Enzyme-linked immunosorbent assay (ELISA) was employed to measure serum IL-1β and IL-18. Spearman correlation analysis was utilized to assess relationships between variables.

Results

Both AGA and AHU groups demonstrated elevated metabolic indicators and serum levels of dsDNA, IL-1β, and IL-18 compared to the HC group. AGA patients exhibited higher inflammatory markers than the AHU group. In the AGA group, there was a significant increase in the mRNA and protein levels of AIM2, Caspase-1, GSDMD, IL-1β, and IL-18 (P<0.05 to P<0.001). The AHU group showed higher AIM2, Caspase-1, GSDMD, and IL-18 mRNA levels than the HC group (P<0.001 to P<0.01), with a non-significant increase in AIM2, GSDMD, and IL-1β proteins (P>0.05). In contrast, Caspase-1 and IL-18 proteins were significantly higher in the AHU group (P<0.05). Notable correlations were observed between AIM2 protein expression and levels of Caspase-1 and GSDMD in both AGA and AHU groups. In the AGA group, AIM2 protein correlated with IL-1β, but not in the AHU group. The AIM2 protein in the AHU group was positively associated with IL-18, with no such correlation in the AGA group.

Conclusion

AIM2 inflammasome may play a role in the inflammatory processes of AGA and AHU and that its activation may be related to the pyroptosis pathway.

Scutellarin inhibits inflammatory PANoptosis by diminishing mitochondrial ROS generation and blocking PANoptosome formation

PANoptosis is manifested with simultaneous activation of biomarkers for both pyroptotic, apoptotic and necroptotic signaling via the molecular platform PANoptosome and it is involved in pathologies of various inflammatory diseases including hemophagocytic lymphohistiocytosis (HLH). Scutellarin is a flavonoid isolated from herbal Erigeron breviscapus (Vant.) Hand.-Mazz. and has been shown to possess multiple pharmacological effects, but it is unknown whether scutellarin has any effects on PANoptosis and related inflammatory diseases. In this study, we found that scutellarin inhibited cell death in bone marrow-derived macrophages (BMDMs) and J774A.1 cells treated with TGF-β-activated kinase 1 (TAK1) inhibitor 5Z-7-oxozeaenol (OXO) plus lipopolysaccharide (LPS), which has been commonly used to induce PANoptosis. Western blotting showed that scutellarin dose-dependently inhibited the activation biomarkers for pyroptotic (Caspase-1p10 and GSDMD-NT), apoptotic (cleaved Casp3/8/9 and GSDME-NT), and necroptotic (phosphorylated MLKL) signaling. The inhibitory effect of scutellarin was unaffected by NLRP3 or Caspase-1 deletion. Interestingly, scutellarin blocked the assembly of PANoptosome that encompasses ASC, RIPK3, Caspase-8 and ZBP1, suggesting its action on upstream signaling. Consistent with this, scutellarin inhibited mitochondrial damage and mitochondrial reactive oxygen species (mtROS) generation in cells treated with OXO+LPS. Further, mito-TEMPO that can scavenge mtROS significantly inhibited OXO+LPS-induced PANoptotic cell death. In line with the in vitro results, scutellarin markedly alleviated systemic inflammation, multiple organ injury, and activation of PANoptotic biomarkers in mice with HLH. Collectively, our data suggest that scutellarin can inhibit PANoptosis by suppressing mitochondrial damage and mtROS generation and thereby mitigating multiple organ injury in mice with inflammatory disorders.

Inducers and Inhibitors of Pyroptotic Death of Granulosa Cells in Models of Premature Ovarian Insufficiency and Polycystic Ovary Syndrome

Granulosa cells (GCs), the largest cell population and primary source of steroid hormones in the ovary, are the important somatic ovarian components. They have critical roles in folliculogenesis by supporting oocyte, facilitating its growth, and providing a microenvironment suitable for follicular development and oocyte maturation, thus having essential functions in maintaining female fertility and in reproductive health in general. Pyroptotic death of GCs and associated inflammation have been implicated in the pathogenesis of several reproductive disorders in females including Premature Ovarian Insufficiency (POI) and Polycystic Ovary Syndrome (PCOS). Here, I reviewed factors, either intrinsic or extrinsic, that induce or inhibit pyroptosis in GCs in various models of these disorders, both in vitro and in vivo, and also covered associated molecular mechanisms. Most of these studied factors influence NLRP3 inflammasome- and GSDMD (Gasdermin D)-mediated pyroptosis in GCs, compared to other inflammasomes and gasdermins (GSDMs). I conclude that a more complete mechanistic understanding of these factors in terms of GC pyroptosis is required to be able to develop novel strategies targeting inflammatory cell death in the ovary.

Palmitoylation at a conserved cysteine residue facilitates gasdermin D-mediated pyroptosis and cytokine release

Gasdermin D (GSDMD)-mediated pyroptotic cell death drives inflammatory cytokine release and downstream immune responses upon inflammasome activation, which play important roles in host defense and inflammatory disorders. Upon activation by proteases, the GSDMD N-terminal domain (NTD) undergoes oligomerization and membrane translocation in the presence of lipids to assemble pores. Despite intensive studies, the molecular events underlying the transition of GSDMD from an autoinhibited soluble form to an oligomeric pore form inserted into the membrane remain incompletely understood. Previous work characterized S-palmitoylation for gasdermins from bacteria, fungi, invertebrates, as well as mammalian gasdermin E (GSDME). Here, we report that a conserved residue Cys191 in human GSDMD was S-palmitoylated, which promoted GSDMD-mediated pyroptosis and cytokine release. Mutation of Cys191 or treatment with palmitoyltransferase inhibitors cyano-myracrylamide (CMA) or 2-bromopalmitate (2BP) suppressed GSDMD palmitoylation, its localization to the membrane and dampened pyroptosis or IL-1β secretion. Furthermore, Gsdmd-dependent inflammatory responses were alleviated by inhibition of palmitoylation in vivo. By contrast, coexpression of GSDMD with palmitoyltransferases enhanced pyroptotic cell death, while introduction of exogenous palmitoylation sequences fully restored pyroptotic activities to the C191A mutant, suggesting that palmitoylation-mediated membrane localization may be distinct from other molecular events such as GSDMD conformational change during pore assembly. Collectively, our study suggests that S-palmitoylation may be a shared regulatory mechanism for GSDMD and other gasdermins, which points to potential avenues for therapeutically targeting S-palmitoylation of gasdermins in inflammatory disorders.

Mechanisms of programmed cell death associated to severe dengue in human renal lesions

Dengue virus (DENV) is a global health problem. Severe dengue can manifest with hemorrhage and signs of organ dysfunction, including the kidneys. The innate immune system is an important barrier against arbovirus infection and, specifically in dengue, the cytokines IL1β and IL18 and caspase-1 activation make up a set of host immune strategies. Cell death mechanisms include pyroptosis, necroptosis and autophagy, each with peculiar markers: gasdermin, RIPK3/MLKL, LC3, respectively. In DENV infection, necrosis and apoptosis are involved and, when infecting monocytes and macrophages in vitro, DENV is capable of inducing pyroptosis. Our objective was to explore the presence of markers of necroptosis, pyroptosis and autophagy in renal lesions caused by DENV.

MATERIAL AND METHODS

twenty specimens of lesions from patients who died due to DENV infection, from the pathology department of Hospital Guilherme Álvaro, Santos, SP, were subjected to histological and immunohistochemical studies. Histological sections were stained with hematoxylin-eosin to evaluate tissue changes or collected for research with antibodies: anti-DENV (Instituto Evandro Chagas-PA), RIPK3 (NBP2-45592), MLKL (ab184718), gasdermin D (#36425 ), LC3 (14600-AP), caspase 1 (#98033), IL1β (AF201-NA) and IL18 (SC6178). Semi-quantitative analysis was performed on 20 glomeruli and evaluation on tubules and mononuclear cells. This study was approved by the ethics committee of the USP Faculty of Medicine.

RESULTS

histological analysis demonstrated glomerular congestion, glomerulitis (medium to severe), acute kidney injury and hyalinization of the glomeruli. Viral antigens were visualized on mononuclear cells. LC3 (autophagy) expression ranged from moderate to intense (++/+++) in glomeruli, tubules and mononuclear cells. The expression of gasdermin (pyroptosis) was mild (+) in most cases in the glomeruli and moderate (++) in the tubules. RIPK3 and MLKL (necroptosis) mild in tubules and mononuclear cells (+). The expression of the cytokines IL1β and IL18 and caspase 1 was moderate (++). Statistical analysis showed greater expression of LC3 over the others.

CONCLUSIONS

Our results contribute to the understanding of the pathogenesis of renal involvement in severe dengue, considering the likely anti-viral mechanism of autophagy. To a lesser extent, pyroptosis is also present, corroborating previous data.

[Recent research on pyroptosis in sepsis-induced myocardial depression]

Sepsis-induced myocardial depression (SIMD), a common complication of sepsis, is one of the main causes of death in patients with sepsis. The pathogenesis of SIMD is complicated, and the process of SIMD remains incompletely understood, with no single or definitive mechanism fully elucidated. Notably, pyroptosis, as a pro-inflammatory programmed cell death, is characterized by Gasdermin-mediated formation of pores on the cell membrane, cell swelling, and cell rupture accompanied by the release of large amounts of inflammatory factors and other cellular contents. Mechanistically, pyroptosis is mainly divided into the canonical pathway mediated by caspase-1 and the non-canonical pathway mediated by caspase-4/5/11. Pyroptosis has been confirmed to participate in various inflammation-associated diseases. In recent years, more and more studies have shown that pyroptosis is also involved in the occurrence and development of SIMD. This article reviews the molecular mechanisms of pyroptosis and its research progress in SIMD, aiming to provide novel strategies and targets for the treatment of SIMD.

Synergistic induction of mitotic pyroptosis and tumor remission by inhibiting proteasome and WEE family kinases

Mitotic catastrophe (MC), which occurs under dysregulated mitosis, represents a fascinating tactic to specifically eradicate tumor cells. Whether pyroptosis can be a death form of MC remains unknown. Proteasome-mediated protein degradation is crucial for M-phase. Bortezomib (BTZ), which inhibits the 20S catalytic particle of proteasome, is approved to treat multiple myeloma and mantle cell lymphoma, but not solid tumors due to primary resistance. To date, whether and how proteasome inhibitor affected the fates of cells in M-phase remains unexplored. Here, we show that BTZ treatment, or silencing of PSMC5, a subunit of 19S regulatory particle of proteasome, causes G2- and M-phase arrest, multi-polar spindle formation, and consequent caspase-3/GSDME-mediated pyroptosis in M-phase (designated as mitotic pyroptosis). Further investigations reveal that inhibitor of WEE1/PKMYT1 (PD0166285), but not inhibitor of ATR, CHK1 or CHK2, abrogates the BTZ-induced G2-phase arrest, thus exacerbates the BTZ-induced mitotic arrest and pyroptosis. Combined BTZ and PD0166285 treatment (named BP-Combo) selectively kills various types of solid tumor cells, and significantly lessens the IC50 of both BTZ and PD0166285 compared to BTZ or PD0166285 monotreatment. Studies using various mouse models show that BP-Combo has much stronger inhibition on tumor growth and metastasis than BTZ or PD0166285 monotreatment, and no obvious toxicity is observed in BP-Combo-treated mice. These findings disclose the effect of proteasome inhibitors in inducing pyroptosis in M-phase, characterize pyroptosis as a new death form of mitotic catastrophe, and identify dual inhibition of proteasome and WEE family kinases as a promising anti-cancer strategy to selectively kill solid tumor cells.

Full-length GSDME mediates pyroptosis independent from cleavage

Gasdermin (GSDM) family proteins, known as the executors of pyroptosis, undergo protease-mediated cleavage before inducing pyroptosis. We here discovered a form of pyroptosis mediated by full-length (FL) GSDME without proteolytic cleavage. Intense ultraviolet-C irradiation-triggered DNA damage activates nuclear PARP1, leading to extensive formation of poly(ADP-ribose) (PAR) polymers. These PAR polymers are released to the cytoplasm, where they activate PARP5 to facilitate GSDME PARylation, resulting in a conformational change in GSDME that relieves autoinhibition. Moreover, ultraviolet-C irradiation promotes cytochrome c-catalysed cardiolipin peroxidation to elevate lipid reactive oxygen species, which is then sensed by PARylated GSDME, leading to oxidative oligomerization and plasma membrane targeting of FL-GSDME for perforation, eventually inducing pyroptosis. Reagents that concurrently stimulate PARylation and oxidation of FL-GSDME, synergistically promoting pyroptotic cell death. Overall, the present findings elucidate an unreported mechanism underlying the cleavage-independent function of GSDME in executing cell death, further enriching the paradigms and understanding of FL-GSDME-mediated pyroptosis.

4-Octyl itaconate blocks GSDMB-mediated pyroptosis and restricts inflammation by inactivating granzyme A

GSDMB-mediated pyroptosis facilitates a pro-inflammatory immune microenvironment and needs to be tightly regulated to avoid excessive inflammation. Here, we provide evidence that itaconate and its cell-permeable derivative 4-octyl itaconate (4-OI) can significantly inhibit GSDMB-rendered pyroptotic activity independent of Nrf2. 4-OI interferes proteolytic process of GSDMB by directly modifying Cys54, Cys148 and Ser212 on granzyme A (GrzA), a serine protease that site-specifically cleaves the inter-domain linker of GSDMB, instead of interaction with GSDMB, thereby blocking pyroptosis and exerts anti-inflammatory effects. Moreover, 4-OI alleviates inflammation by suppressing GSDMB-induced pyroptotic cell death during acute colitis models in intestinal epithelial GSDMB conditional transgenic mice. Our data expand the role of 4-OI as a crucial immunometabolic derivative that regulates innate immunity and inflammation through a newly identified posttranslational modification, and targeting of pyroptosis by 4-OI therefore holds potent therapeutic potential for primarily inflammatory and/or autoimmune diseases.

Curcumin ameliorates pyroptosis in diabetic seminal vesicles by upregulating TRPV6

BACKGROUND

Diabetes damages the seminal vesicle tissues leading to a decrease in seminal fluid secretion, so investigations are ongoing to identify specific therapeutic approaches to address diabetes-induced damage to seminal vesicles.

OBJECTIVE

This study investigated the secretory dysfunction of seminal vesicles and how curcumin can ameliorate this dysfunction.

MATERIALS AND METHODS

First, 40 diabetic males (DM group) and 40 nondiabetic males (control group) underwent seminal vesicle ultrasound evaluation and ejaculate volume measurements. Then, the effects of curcumin on seminal vesicle function were investigated in a diabetic rat model. Fifty 8-week-old SPF-grade SD rats were categorized into five groups: control, DM (diabetes mellitus), low-dose CUR (curcumin 50 mg/kg/d), medium-dose CUR (curcumin 100 mg/kg/d), and high-dose CUR (curcumin 150 mg/kg/d). After a month-long diet with varying curcumin doses, key parameters such as body weight, blood glucose levels, seminal vesicle volume, and seminal fluid secretion were measured. Transcriptome sequencing was performed to assess differences in gene expression and structural changes in rat seminal vesicle tissues were examined by HE staining. Finally, human seminal vesicle cell lines were cultured and divided into five groups (HG-CON, HG-CUR-5 µM, HG-CUR-10 µM, HG-CUR-20 µM, and HG-CUR-50 µM) to measure the fructose levels in the seminal vesicle cell culture fluids and evaluate the expression of CASP1, GSDMD, and TRPV6. Post TRPV6 interference, variations in the gene expression of CASP1, GSDMD, and TRPV6 were monitored.

RESULTS

Diabetic patients exhibited a notable reduction in seminal vesicle volume and ejaculate volume compared with the control group, with a direct correlation between the decrease in ejaculate and seminal vesicle volume. Animal studies demonstrated that curcumin supplementation significantly augmented seminal vesicle volume in diabetic rats and notably improved their seminal vesicle secretory dysfunction, particularly in the high-dose curcumin group. Transcriptome sequencing and experimental verification pinpointed the differential expression of TPRV6 and pyroptosis-associated genes (CASP1, GSDMD), with reduced TRPV6 expression but increased markers of pyroptosis (CASP1 and GSDMD) in diabetic rats. Curcumin treatment reversed these effects with an increase in TRPV6 and a decrease in GSDMD and CASP1. Cell transfection experiments indicated that TRPV6 downregulation increased GSDMD and CASP1 gene expression.

CONCLUSION

Curcumin effectively activates TRPV6, thereby diminishing pyroptosis in the seminal vesicle tissues of diabetic rats. This activation not only leads to an increase in the seminal vesicle volume but also significantly ameliorates the seminal vesicle secretory dysfunction in diabetic rats.

A Cascade-Amplified Pyroptosis Inducer: Optimizing Oxidative Stress Microenvironment by Self-Supplying Reactive Nitrogen Species Enables Potent Cancer Immunotherapy

Selective generation of sufficient pyroptosis inducers at the tumor site without external stimulation holds immense significance for a longer duration of immunotherapy. Here, we report a cascade-amplified pyroptosis inducer CSCCPT/SNAP that utilizes reactive nitrogen species (RNS), self-supplied from the diffusion-controlled reaction between reactive oxygen species (ROS) and nitric oxide (NO) to potentiate pyroptosis and immunotherapy, while both endogenous mitochondrial ROS stimulated by released camptothecin and released NO initiate pyroptosis. Mechanistically, cascade amplification of the antitumor immune response is prompted by the cooperation of ROS and NO and enhanced by RNS with a long lifetime, which could be used as a pyroptosis trigger to effectively compensate for the inherent drawbacks of ROS, resulting in long-lasting pyroptosis for favoring immunotherapy. Tumor growth is efficiently inhibited in mouse melanoma tumors through the facilitation of reactive oxygen/nitrogen species (RONS)-NO synergy. In summary, our therapeutic approach utilizes supramolecular engineering and nanotechnology to integrate ROS producers and NO donors of tumor-specific stimulus responses into a system that guarantees synchronous generation of these two reactive species to elicit pyroptosis-evoked immune response, while using self-supplied RNS as a pyroptosis amplifier. RONS-NO synergy achieves enhanced and sustained pyroptosis and antitumor immune responses for robust cancer immunotherapy.

GSDME-mediated pyroptosis promotes anti-tumor immunity of neoadjuvant chemotherapy in breast cancer

Paclitaxel and anthracycline-based chemotherapy is one of the standard treatment options for breast cancer. However, only about 6-30% of breast cancer patients achieved a pathological complete response (pCR), and the mechanism responsible for the difference is still unclear. In this study, random forest algorithm was used to screen feature genes, and artificial neural network (ANN) algorithm was used to construct an ANN model for predicting the efficacy of neoadjuvant chemotherapy for breast cancer. Furthermore, digital pathology, cytology, and molecular biology experiments were used to verify the relationship between the efficacy of neoadjuvant chemotherapy and immune ecology. It was found that paclitaxel and doxorubicin, an anthracycline, could induce typical pyroptosis and bubbling in breast cancer cells, accompanied by gasdermin E (GSDME) cleavage. Paclitaxel with LDH release and Annexin V/PI doubule positive cell populations, and accompanied by the increased release of damage-associated molecular patterns, HMGB1 and ATP. Cell coculture experiments also demonstrated enhanced phagocytosis of macrophages and increased the levels of IFN-γ and IL-2 secretion after paclitaxel treatment. Mechanistically, GSDME may mediate paclitaxel and doxorubicin-induced pyroptosis in breast cancer cells through the caspase-9/caspase-3 pathway, activate anti-tumor immunity, and promote the efficacy of paclitaxel and anthracycline-based neoadjuvant chemotherapy. This study has practical guiding significance for the precision treatment of breast cancer, and can also provide ideas for understanding molecular mechanisms related to the chemotherapy sensitivity.

The role of pyroptosis in metabolism and metabolic disease

Pyroptosis is a lytic and pro-inflammatory form of regulated cell death characterized by the formation of membrane pores mediated by the gasdermin protein family. Two main activation pathways have been documented: the caspase-1-dependent canonical pathway and the caspase-4/5/11-dependent noncanonical pathway. Pyroptosis leads to cell swelling, lysis, and the subsequent release of inflammatory mediators, including interleukin-1β (IL-1β) and interleukin-18 (IL-18). Chronic inflammation is a well-established foundation and driver for the development of metabolic diseases. Conversely, metabolic pathway dysregulation can also induce cellular pyroptosis. Recent studies have highlighted the significant role of pyroptosis modulation in various metabolic diseases, including type 2 diabetes mellitus, obesity, and metabolic (dysfunction) associated fatty liver disease. These findings suggest that pyroptosis may serve as a promising novel therapeutic target for metabolic diseases. This paper reviews an in-depth study of the current advancements in understanding the role of pyroptosis in the progression of metabolic diseases.

Depletion of Gsdma1/2/3 alleviates PMA-induced epidermal hyperplasia by inhibiting the EGFR-Stat3/Akt pathway

Homeostasis of the skin barrier is essential for maintaining normal skin function. Gasdermin A (GSDMA) is highly expressed in the skin and associated with many skin diseases, such as melanoma and psoriasis. In mice, GSDMA is encoded by three gene homologues, namely Gsdma1, Gsdma2, and Gsdma3. Although Gsdma3 gain-of-function mutations cause hair loss and skin inflammation, Gsdma3-deficient mice do not show any visible phenotypes in skin and hair structures. To explore the physiological function of GSDMA, we generated conventional Gsdma1/2/3 knockout (KO) mice. These mice showed significantly alleviated epidermal hyperplasia and inflammation induced by phorbol 12-myristate 13-acetate (PMA). Furthermore, the alleviation of epidermal hyperplasia depended on the expression of Gsdma1/2/3 specifically in keratinocytes. Mechanistically, Gsdma1/2/3 depletion downregulated epidermal growth factor receptor (EGFR) ligands, leading to the decreased EGFR-Stat3/Akt signalling. These results demonstrate that depletion of Gsdma1/2/3 alleviates PMA-induced epidermal hyperplasia partially by inhibiting the EGFR-Stat3/Akt pathway.

E3 ubiquitin ligase TRIM31: A potential therapeutic target

Ubiquitination is a key mechanism for post-translational protein modification, affecting protein localization, metabolism, degradation and various cellular physiological processes. Dysregulation of ubiquitination is associated with the pathogenesis of various diseases, such as tumors and cardiovascular diseases, making it a primary area of interest in biochemical research and drug development endeavors. E3 ubiquitin ligases play a pivotal role in modulating the ubiquitination of substrate proteins through their unique recognition functions. TRIM31, a member of the TRIM family of E3 ubiquitin ligases, is aberrantly expressed in different pathophysiological conditions. The biological function of TRIM31 is associated with the occurrence and development of diverse diseases. TRIM31 has been demonstrated to inhibit inflammation by promoting ubiquitin-proteasome-mediated degradation of the sensing protein NLRP3 in the inflammasome. TRIM31 mediates ubiquitination of MAVS, inducing the formation of prion-like aggregates, and triggering innate antiviral immune responses. TRIM31 is also implicated in tumor pathophysiology through its ability to promote ubiquitination of the tumor suppressor protein p53. These findings indicate that TRIM31 is a potential therapeutic target, and subsequent in-depth research of TRIM31 is anticipated to provide information on its clinical application in therapy.

Targeting inflammasomes and pyroptosis in retinal diseases-molecular mechanisms and future perspectives

Retinal diseases encompass various conditions associated with sight-threatening immune responses and are leading causes of blindness worldwide. These diseases include age-related macular degeneration, diabetic retinopathy, glaucoma and uveitis. Emerging evidence underscores the vital role of the innate immune response in retinal diseases, beyond the previously emphasized T-cell-driven processes of the adaptive immune system. In particular, pyroptosis, a newly discovered programmed cell death process involving inflammasome formation, has been implicated in the loss of membrane integrity and the release of inflammatory cytokines. Several disease-relevant animal models have provided evidence that the formation of inflammasomes and the induction of pyroptosis in innate immune cells contribute to inflammation in various retinal diseases. In this review article, we summarize current knowledge about the innate immune system and pyroptosis in retinal diseases. We also provide insights into translational targeting approaches, including novel drugs countering pyroptosis, to improve the diagnosis and treatment of retinal diseases.

Diallyl trisulfide induces pyroptosis and impairs lung CSC-like properties by activating the ROS/Caspase 1 signaling pathway

Lung cancer stem cells (CSCs) drive continuous cancer growth and metastatic dissemination; thus, there is an urgent requirement to acquire effective therapeutic strategies for targeting lung CSCs. Diallyl trisulfide (DATS), a garlic organosulfide, possesses suppressive potential in lung cancer; however, its underlying mechanism is still unclear. In this study, we identified DATS as a pyroptosis inducer in lung cancer cells. DATS-treated A549 and H460 cells exhibited pyroptotic cell death, with characteristic large bubbles appearing on their plasma membrane and LDH release. DATS induced cell death, arrested the cell cycle at the G2/M phase, and inhibited colony formation in lung cancer cells. Meanwhile, we found that DATS significantly suppressed the malignant features by impairing lung CSC-like properties, including sphere formation ability, CD133 positive cell number, and lung CSCs marker expression. Mechanistically, DATS induced cell pyroptosis via increasing the expression of NLRP3, ASC, Pro Caspase 1, Cleaved Caspase 1, GSDMD, GSDMD-N, and IL-1β. The verification experiments showed that the effects of DATS on pyroptosis and lung CSC-like properties were weakened after Caspase 1 inhibitor VX-765 treatment, indicating that DATS activated NLRP3 inflammasome-mediated pyroptosis by targeting Caspase 1 in lung cancer cells. Moreover, DATS increased ROS overproduction and mitochondrial dysfunction, which contributed to DATS-induced pyroptosis of lung cancer cells. NAC treatment reversed the effects of DATS on pyroptosis and CSC-like properties. In vivo experiment further confirmed that DATS restrained tumor growth. Together, our results suggest that DATS promotes pyroptosis and impairs lung CSC-like properties by activating ROS/Caspase 1 signaling pathway, thereby retarding lung cancer progression.

Novel strategies for targeting neutrophil against myocardial infarction

Inflammation is a crucial factor in cardiac remodeling after acute myocardial infarction (MI). Neutrophils, as the first wave of leukocytes to infiltrate the injured myocardium, exacerbate inflammation and cardiac injury. However, therapies that deplete neutrophils to manage cardiac remodeling after MI have not consistently produced promising outcomes. Recent studies have revealed that neutrophils at different time points and locations may have distinct functions. Thus, transferring neutrophil phenotypes, rather than simply blocking their activities, potentially meet the needs of cardiac repair. In this review, we focus on discussing the fate, heterogeneity, functions of neutrophils, and attempt to provide a more comprehensive understanding of their roles and targeting strategies in MI. We highlight the strategies and translational potential of targeting neutrophils to limit cardiac injury to reduce morbidity and mortality from MI.

Gasdermin-B (GSDMB) takes center stage in antibacterial defense, inflammatory diseases, and cancer

One of the hottest topics in biomedical research is to decipher the functional implications of the Gasdermin (GSDM) protein family in human pathologies. These proteins are the key effectors of a lytic and pro-inflammatory cell death type termed pyroptosis (also known as "Gasdermin-mediated programmed cell death"). However, ever-growing evidence showed that GSDMs can play multiple and complex roles in a context-dependent manner. In this sense, Gasdermin-B (GSDMB; the only GSDM gene absent in mice and rats) has been implicated in antibacterial defense, numerous inflammatory pathologies (e.g., asthma, ulcerative colitis), and cancer, but both cell death-dependent and -independent functions have been reported in these diseases, fueling the debate on whether GSDMB has genuine pyroptotic capacity. Recently, a series of seminal papers cast light on the GSDMB multitasking capacity by showing that different GSDMB transcriptional isoforms have distinct biological activities. Nonetheless, there are still obscure areas to be clarified on the precise functional involvement of GSDMB translated variants in physiological and pathological conditions. In this viewpoint, we critically discuss the most recent and exciting data on this topic and propose a series of relevant challenges that need to be overcome before GSDMB-driven biomedical applications (as a biomarker of disease risk/progression/outcome or as specific therapeutic target) become a reality in clinical settings.

The immune modules conserved across the tree of life: Towards a definition of ancestral immunity

Immune defence mechanisms exist across the tree of life in such diversity that prokaryotic antiviral responses have historically been considered unrelated to eukaryotic immunity. Mechanisms of defence in divergent eukaryotes were similarly believed to be largely clade specific. However, recent data indicate that a subset of modules (domains and proteins) from prokaryote defence systems are conserved in eukaryotes and populate many stages of innate immune pathways. In this Essay, we propose the notion of ancestral immunity, which corresponds to the set of immune modules conserved between prokaryotes and eukaryotes. After offering a typology of ancestral immunity, we speculate on the selective pressures that could have led to the differential conservation of specific immune modules across domains of life. The exploration of ancestral immunity is in its infancy and appears full of promises to illuminate immune evolution, and also to identify and decipher immune mechanisms of economic, ecological, and therapeutic importance.

Pyroptosis-related crosstalk in osteoarthritis: Macrophages, fibroblast-like synoviocytes and chondrocytes

The pathogenesis of osteoarthritis (OA) involves a multifaceted interplay of inflammatory processes. The initiation of pyroptosis involves the secretion of pro-inflammatory cytokines and has been identified as a critical factor in regulating the development of OA. Upon initiation of pyroptosis, a multitude of inflammatory mediators are released and can be disseminated throughout the synovial fluid within the joint cavity, thereby facilitating intercellular communication across the entire joint. The main cellular components of joints include chondrocytes (CC), fibroblast-like synoviocytes (FLS) and macrophages (MC). Investigating their interplay can enhance our understanding of OA pathogenesis. Therefore, we comprehensively examine the mechanisms underlying pyroptosis and specifically investigate the intercellular interactions associated with pyroptosis among these three cell types, thereby elucidating their collective contribution to the progression of OA. We propose the concept of ' CC-FLS-MC pyroptosis-related crosstalk', describe the various pathways of pyroptotic interactions among these three cell types, and focus on recent advances in intervening pyroptosis in these three cell types for treating OA. We hope this will provide a possible direction for diversification of treatment for OA. The Translational potential of this article. The present study introduces the concept of 'MC-FLS-CC pyroptosis-related crosstalk' and provides an overview of the mechanisms underlying pyroptosis, as well as the pathways through which it affects MC, FLS, and CC. In addition, the role of regulation of these three types of cellular pyroptosis in OA has also been concerned. This review offers novel insights into the interplay between these cell types, with the aim of providing a promising avenue for diversified management of OA.

Conservation and similarity of bacterial and eukaryotic innate immunity

Pathogens are ubiquitous and a constant threat to their hosts, which has led to the evolution of sophisticated immune systems in bacteria, archaea and eukaryotes. Bacterial immune systems encode an astoundingly large array of antiviral (antiphage) systems, and recent investigations have identified unexpected similarities between the immune systems of bacteria and animals. In this Review, we discuss advances in our understanding of the bacterial innate immune system and highlight the components, strategies and pathogen restriction mechanisms conserved between bacteria and eukaryotes. We summarize evidence for the hypothesis that components of the human immune system originated in bacteria, where they first evolved to defend against phages. Further, we discuss shared mechanisms that pathogens use to overcome host immune pathways and unexpected similarities between bacterial immune systems and interbacterial antagonism. Understanding the shared evolutionary path of immune components across domains of life and the successful strategies that organisms have arrived at to restrict their pathogens will enable future development of therapeutics that activate the human immune system for the precise treatment of disease.

GSDMD in regulated cell death: A novel therapeutic target for sepsis

Sepsis is a life-threatening multi-organ dysfunction syndrome caused by an abnormal host response to infection. Regulated cell death is essential for maintaining tissue homeostasis and eliminating damaged, infected, or aging cells in multicellular organisms. Gasdermin D, as a member of the gasdermin family, plays a crucial role in the formation of cytoplasmic membrane pores. Research has found that GSDMD plays important roles in various forms of regulated cell death such as pyroptosis, NETosis, and necroptosis. Therefore, through mediating regulated cell death, GSDMD regulates different stages of disease pathophysiology. This article mainly summarizes the concept of GSDMD, its role in regulated cell death, its involvement in organ damage associated with sepsis-related injuries mediated by regulated cell death via GSDMD activation and introduces potential drugs targeting GSDMD that may provide more effective treatment options for sepsis patients through drug modification.

Non-Apoptotic Programmed Cell Death as Targets for Diabetic Retinal Neurodegeneration

Diabetic retinopathy (DR) remains the leading cause of blindness among the global working-age population. Emerging evidence underscores the significance of diabetic retinal neurodegeneration (DRN) as a pivotal biomarker in the progression of vasculopathy. Inflammation, oxidative stress, neural cell death, and the reduction in neurotrophic factors are the key determinants in the pathophysiology of DRN. Non-apoptotic programmed cell death (PCD) plays a crucial role in regulating stress response, inflammation, and disease management. Therapeutic modalities targeting PCD have shown promising potential for mitigating DRN. In this review, we highlight recent advances in identifying the role of various PCD types in DRN, with specific emphasis on necroptosis, pyroptosis, ferroptosis, parthanatos, and the more recently characterized PANoptosis. In addition, the therapeutic agents aimed at the regulation of PCD for addressing DRN are discussed.

Tmem30a protects against podocyte injury through suppression of pyroptosis

Podocytopathies, such as focal segmental glomerulosclerosis (FSGS), are characterized by podocyte injury and can easily progress to end-stage kidney disease. However, the mechanisms underlying podocyte injury remain unclear. We observed podocyte injury along with pyroptosis in patients with FSGS. Bioinformatic analysis of public datasets revealed that transmembrane protein 30a (Tmem30a) might be associated with FSGS. The expression of Temem30a and the podocyte-related protein, nephrin, were significantly downregulated in patients with FSGS, adriamycin (ADR)-induced mice, and podocyte-specific Tmem30a lox P /loxP ; NPHS2-Cre mice, whereas the expression of NLR family pyrin domain containing 3 (NLRP3) and ASC, two pyroptosis-related proteins, were significantly upregulated. Meanwhile, the pyroptosis inhibitor MCC950 and disulfiram (DSF) increased Tmem30a and podocyte-related proteins expression, and inhibited pyroptosis-related proteins expression in ADR-induced mouse podocytes and Tmem30a knockdown (KD) mouse podocytes. Therefore, Tmem30a might protect against podocyte injury by inhibiting pyroptosis, suggesting a potential therapeutic target for podocytopathies.

PJA1-mediated suppression of pyroptosis as a driver of docetaxel resistance in nasopharyngeal carcinoma

Chemoresistance is a main reason for treatment failure in patients with nasopharyngeal carcinoma, but the exact regulatory mechanism underlying chemoresistance in nasopharyngeal carcinoma remains to be elucidated. Here, we identify PJA1 as a key E3 ubiquitin ligase involved in nasopharyngeal carcinoma chemoresistance that is highly expressed in nasopharyngeal carcinoma patients with nonresponse to docetaxel-cisplatin-5-fluorouracil induction chemotherapy. We find that PJA1 facilitates docetaxel resistance by inhibiting GSDME-mediated pyroptosis in nasopharyngeal carcinoma cells. Mechanistically, PJA1 promotes the degradation of the mitochondrial protein PGAM5 by increasing its K48-linked ubiquitination at K88, which further facilitates DRP1 phosphorylation at S637 and reduced mitochondrial reactive oxygen species production, resulting in suppression of GSDME-mediated pyroptosis and the antitumour immune response. PGAM5 knockdown fully restores the docetaxel sensitization effect of PJA1 knockdown. Moreover, pharmacological targeting of PJA1 with the small molecule inhibitor RTA402 enhances the docetaxel sensitivity of nasopharyngeal carcinoma in vitro and in vivo. Clinically, high PJA1 expression indicates inferior survival and poor clinical efficacy of TPF IC in nasopharyngeal carcinoma patients. Our study emphasizes the essential role of E3 ligases in regulating chemoresistance and provides therapeutic strategies for nasopharyngeal carcinoma based on targeting the ubiquitin-proteasome system.

Mechanisms of host adaptation by bacterial pathogens

The emergence of new infectious diseases poses a major threat to humans, animals, and broader ecosystems. Defining factors that govern the ability of pathogens to adapt to new host species is therefore a crucial research imperative. Pathogenic bacteria are of particular concern, given dwindling treatment options amid the continued expansion of antimicrobial resistance. In this review, we summarize recent advancements in the understanding of bacterial host species adaptation, with an emphasis on pathogens of humans and related mammals. We focus particularly on molecular mechanisms underlying key steps of bacterial host adaptation including colonization, nutrient acquisition, and immune evasion, as well as suggest key areas for future investigation. By developing a greater understanding of the mechanisms of host adaptation in pathogenic bacteria, we may uncover new strategies to target these microbes for the treatment and prevention of infectious diseases in humans, animals, and the broader environment.

Picrasidine S Induces cGAS-Mediated Cellular Immune Response as a Novel Vaccine Adjuvant

New adjuvants that trigger cellular immune responses are urgently needed for the effective development of cancer and virus vaccines. Motivated by recent discoveries that show activation of type I interferon (IFN-I) signaling boosts T cell immunity, this study proposes that targeting this pathway can be a strategic approach to identify novel vaccine adjuvants. Consequently, a comprehensive chemical screening of 6,800 small molecules is performed, which results in the discovery of the natural compound picrasidine S (PS) as an IFN-I inducer. Further analysis reveals that PS acts as a powerful adjuvant, significantly enhancing both humoral and cellular immune responses. At the molecular level, PS initiates the activation of the cGAS-IFN-I pathway, leading to an enhanced T cell response. PS vaccination notably increases the population of CD8+ central memory (TCM)-like cells and boosts the CD8+ T cell-mediated anti-tumor immune response. Thus, this study identifies PS as a promising candidate for developing vaccine adjuvants in cancer prevention.

Bioinspired Nano-Photosensitizer-Activated Caspase-3/GSDME Pathway Induces Pyroptosis in Lung Cancer Cells

Noninflammatory apoptosis is transformed into inflammatory pyroptosis by activating caspase-3 to lyse gasdermin E (GSDME), and this process can be used as an effective therapeutic strategy. Thus, a selective and powerful inducer of activated caspase-3 plays a vital role in pyroptosis-based cancer therapy. Herein, a human cell membrane vesicle-based nanoplatform (HCNP) is designed for photodynamic therapy (PDT). HCNP is modified with vesicular stomatitis virus G-protein (VSVG) to anchor nano-photosensitizers on the tumor cell membrane. Photosensitizers are bonded to HCNP by clicking chemical reaction as pyroptosis inducers. The results show that HCNP effectively disrupts the mitochondrial function of cells by generating reactive oxygen species (ROS) upon laser irradiation; concomitantly, GSDME is cleaved by activated caspase-3 and promotes pyroptosis of lung cancer cells. Here an effective intervention strategy is proposed to induce pyroptosis based on light-activated PDT.