The evolution of regulated cell death pathways in animals and their evasion by pathogens

The regulatory role of the Netrin-1/UNC5H3 pathway in neuronal pyroptosis after stroke

Currently, stroke is a disease with high disability and mortality risks and no effective treatment. The pathogenesis and molecular mechanisms of neuronal damage in stroke are highly complex. Pyroptosis participates in neuronal death after stroke. Thus, inhibiting pyroptosis could be a potential therapeutic method to improve the poor prognosis of stroke patients. However, the regulated mechanisms of pyroptosis remain unclear. Furthermore, although the role of Netrin-1 and its receptors in ischemic apoptosis is well-known, their specific functions in ischemia-induced pyroptosis are still unknown. The current study aimed to explore whether Netrin-1 and its receptor UNC5H3 could regulate pyroptosis after ischemic stroke. PC12 cells decreased Netrin-1 expression and increased UNC5H3 expression after OGD/R injury, subsequently leading to the dissociation of Netrin-1 from UNC5H3, accompanied by increased pyroptotic activity. UNC5H3 inhibition in the absence of Netrin-1 could inhibit OGD/R injury-induced cell pyroptosis. Furthermore, a decreased Netrin-1/UNC5H3 interaction could mitigate Netrin-1-elicited protective role against OGD/R injury. Additionally, Netrin-1 provided a neuroprotective effect against MCAO injury in vivo. Therefore, the Netrin-1/UNC5H3 pathway plays a regulatory role in neuronal pyroptosis after ischemic stroke, representing a novel therapeutic target and strategy for stroke therapy.

Lipotoxicity-induced upregulation of FIS1 exacerbates mitochondrial fragmentation and promotes NLRP3-dependent pyroptosis in diabetic cardiomyopathy

BACKGROUND

Lipotoxicity is a significant factor in the pathogenesis of diabetic cardiomyopathy (DbCM), a condition characterized by mitochondrial fragmentation and pyroptosis. Mitochondrial fission protein 1 (FIS1) plays a role in mitochondrial fission by anchoring dynamin-related protein 1 (DRP1). However, the specific contribution of FIS1 to DbCM remains unclear. This study aims to clarify how lipotoxicity-induced upregulation of FIS1 affects mitochondrial fragmentation and the mechanisms linking this fragmentation to NLRP3-dependent pyroptosis in DbCM.

METHODS

To model lipotoxicity in DbCM, we used db/db mice and primary neonatal rat cardiomyocytes (NRCMs) treated with palmitic acid (PA) and conducted a series of in vivo and in vitro experiments. Gain- and loss-of-function studies on NRCMs were performed using pharmacological inhibitors and small interfering RNA (siRNA) transfection, and we assessed the expression and function of FIS1, mitochondrial dynamics, mitochondrial reactive oxygen species (mitoROS) production, NLRP3-dependent pyroptosis, and their interrelationships.

RESULTS

Our results show that in the myocardium of db/db mice, NLRP3-dependent pyroptosis is associated with upregulation of FIS1, mitochondrial fragmentation, and increased oxidative stress. In NRCMs subjected to PA, the application of VX-765 and MCC950 to inhibit caspase-1 and NLRP3, respectively, significantly reduced pyroptosis. Additionally, pretreatment with Mito-TEMPO (MT) demonstrated that mitoROS are critical initiators for NLRP3 inflammasome activation and subsequent pyroptosis. Furthermore, PA-induced upregulation of FIS1 exacerbates mitochondrial fragmentation. Downregulation of FIS1 or inhibition of FIS1/DRP1 interaction reversed mitochondrial fragmentation, reduced mitoROS levels, and mitigated pyroptosis.

CONCLUSIONS

Lipotoxicity-induced FIS1 upregulation exacerbates mitochondrial fragmentation through its interaction with DRP1, leading to increased mitoROS production and the initiation of NLRP3-dependent pyroptosis in DbCM. Therefore, targeting FIS1 emerges as a potential therapeutic approach for managing DbCM.

Residue Y362 is crucial for FLIPL to impart catalytic activity to pro-caspase-8 to suppress necroptosis

The pro-form of caspase-8 prevents necroptosis by functioning in a proteolytically active complex with its catalytic-dead homolog, FLICE (FADD [Fas-associated death domain]-like interleukin 1β-converting enzyme)-like inhibitory protein long-form (FLIPL). However, how FLIPL imparts caspase-8 the catalytic activity to suppress necroptosis remains elusive. Here, we show that the protease-like domain of FLIPL is essential for the activity of the caspase-8-FLIPL heterodimer in blocking necroptosis. While substitution of two amino acids whose difference may contribute to the pseudo-caspase property of FLIPL with the corresponding amino acids in caspase-8 does not restore the protease activity of FLIPL, one of the amino acid replacements, tyrosine (Y) 362 to cysteine (C), is sufficient to completely abolish the activity of the caspase-8-FLIPL heterodimer in cleaving receptor-interacting protein 1 (RIP1), thus releasing the necroptosis blockade. Unconstrained necroptosis is observed in embryonic day (E)10.5-E11.5 embryos of FLIPL-Y362C knockin mice. Collectively, these results reveal that the protease-like domain of FLIPL has a special structure that imparts the pro-caspase-8-FLIPL heterodimer a unique catalytic activity toward RIP1 to prevent necroptosis.

Lizhong decoction inhibits porcine epidemic diarrhea virus in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Lizhong decoction (LZD) is a frequently utilized traditional Chinese remedy for diarrhea. It is unknown how effective it is as an antiviral against PEDV infection.

AIM OF THE STUDY

In vitro and in vivo PEDV infection models were used to evaluate the anti-PEDV potential of LZD extract.

MATERIALS AND METHODS

LC-MS was used for qualitative analysis of LZD. The antiviral effect of LZD against PEDV using flow cytometry (FC), Quantitative real-time polymerase chain reaction (QPCR), immunofluorescence assay (IFA) analysis in Vero and IPEC-J2 cells. Additionally, we measured the survival rate, clinical symptoms, body weights, fecal scores, temperature, histological analysis, and viral load in a model of newborn piglets infected with PEDV in order to assess the antiviral impact of LZD in vivo.

RESULTS

In total, 648 compounds were identified, including 144 Alkaloids, 128 Terpenoids, etc. LZD effectively suppressed PEDV replication in vitro. According to time of addition experiments, LZD mostly inhibited PEDV during the viral life cycle's replication stages. During PEDV infection, LZD can Significantly decrease the apoptotic rate of IPEC-J2 cells and Vero cells. In comparison to the model group, LZD was able to decrease the viral titers in the infected piglets' intestinal and visceral tissues, ameliorate their intestinal pathology, cause a significant increase in body weight growth and increase the piglet survival rate.

CONCLUSION

Our findings indicate that the aqueous solution derived from LZD suppressed PEDV replication both in vitro and in vivo, indicating its potential as a candidate for pharmaceutical development.

Pyroptosis regulation by Salmonella effectors

The genus Salmonella contains the most common foodborne pathogens frequently isolated from food-producing animals and is responsible for zoonotic infections in humans and animals. Salmonella infection in humans and animals can cause intestinal damage, resulting in intestinal inflammation and disruption of intestinal homeostasis more severe cases can lead to bacteremia. Pyroptosis, a proinflammatory form of programmed cell death, is involved in many disease processes. Inflammasomes, pyroptosis, along with their respective signaling cascades, are instrumental in the preservation of intestinal homeostasis. In recent years, with the in-depth study of pyroptosis, our comprehension of the virulence factors and effector proteins in Salmonella has reached an extensive level, a deficit persists in our knowledge regarding the intrinsic pathogenic mechanisms about pyroptosis, necessitating a continued pursuit of understanding and investigation. In this review, we discuss the occurrence of pyroptosis induced by Salmonella effectors to provide new ideas for elucidating the regulatory mechanisms through which Salmonella virulence factors and effector proteins trigger pyroptosis could pave the way for novel concepts and strategies in the clinical prevention of Salmonella infections and the treatment of associated diseases.

Death at a funeral: Activation of the dead enzyme, MLKL, to kill cells by necroptosis

Necroptosis is a lytic form of programmed cell death implicated in inflammatory pathologies, leading to intense interest in the underlying mechanisms and therapeutic prospects. Here, we review our current structural understanding of how the terminal executioner of the pathway, the dead kinase, mixed lineage kinase domain-like (MLKL), is converted from a dormant to killer form by the upstream regulatory kinase, RIPK3. RIPK3-mediated phosphorylation of MLKL's pseudokinase domain toggles a molecular switch that induces dissociation from a cytoplasmic platform, assembly of MLKL oligomers, and trafficking to the plasma membrane, where activated MLKL accumulates and permeabilises the lipid bilayer to induce cell death. We highlight gaps in mechanistic knowledge of MLKL's activation, how mechanisms diverge between species, and the power of modelling in advancing structural insights.

Evolutionary and functional analyses reveal a role for the RHIM in tuning RIPK3 activity across vertebrates

Receptor interacting protein kinases (RIPK) RIPK1 and RIPK3 play important roles in diverse innate immune pathways. Despite this, some RIPK1/3-associated proteins are absent in specific vertebrate lineages, suggesting that some RIPK1/3 functions are conserved while others are more evolutionarily labile. Here, we perform comparative evolutionary analyses of RIPK1-5 and associated proteins in vertebrates to identify lineage-specific rapid evolution of RIPK3 and RIPK1 and recurrent loss of RIPK3-associated proteins. Despite this, diverse vertebrate RIPK3 proteins are able to activate NF-κB and cell death in human cells. Additional analyses revealed a striking conservation of the RIP homotypic interaction motif (RHIM) in RIPK3, as well as other human RHIM-containing proteins. Interestingly, diversity in the RIPK3 RHIM can tune activation of NF-κB while retaining the ability to activate cell death. Altogether, these data suggest that NF-κB activation is a core, conserved function of RIPK3, and the RHIM can tailor RIPK3 function to specific needs within and between species.

Osteogenesis imperfecta type 10 and the cellular scaffolds underlying common immunological diseases

Osteogenesis imperfecta type 10 (OI10) is caused by loss of function codon variants in the gene SERPINH1 that encodes heat shock protein 47 (HSP47), rather than in a gene specifying bone formation. The HSP47 variants disrupt the folding of both collagen and the endonuclease IRE1α (inositol-requiring enzyme 1α) that splices X-Box Binding Protein 1 (XBP1) mRNA. Besides impairing bone development, variants likely affect osteoclast differentiation. Three distinct biochemical scaffold play key roles in the differentiation and regulated cell death of osteoclasts. These scaffolds consist of non-templated protein modifications, ordered lipid arrays, and protein filaments. The scaffold components are specified genetically, but assemble in response to extracellular perturbagens, pathogens, and left-handed Z-RNA helices encoded genomically by flipons. The outcomes depend on interactions between RIPK1, RIPK3, TRIF, and ZBP1 through short interaction motifs called RHIMs. The causal HSP47 nonsynonymous substitutions occur in a novel variant leucine repeat region (vLRR) that are distantly related to RHIMs. Other vLRR protein variants are causal for a variety of different mendelian diseases. The same scaffolds that drive mendelian pathology are associated with many other complex disease outcomes. Their assembly is triggered dynamically by flipons and other context-specific switches rather than by causal, mendelian, codon variants.

Oridonin attenuates liver ischemia-reperfusion injury by suppressing PKM2/NLRP3-mediated macrophage pyroptosis

BACKGROUND

The NOD-like receptor protein 3 (NLRP3) mediated pyroptosis of macrophages is closely associated with liver ischemia reperfusion injury (IRI). As a covalent inhibitor of NLRP3, Oridonin (Ori), has strong anti-inflammasome effect, but its effect and mechanisms for liver IRI are still unknown.

METHODS

Mice and liver macrophages were treated with Ori, respectively. Co-IP and LC-MS/MS analysis of the interaction between PKM2 and NLRP3 in macrophages. Liver damage was detected using H&E staining. Pyroptosis was detected by WB, TEM, and ELISA.

RESULTS

Ori ameliorated liver macrophage pyroptosis and liver IRI. Mechanistically, Ori inhibited the interaction between pyruvate kinase M2 isoform (PKM2) and NLRP3 in hypoxia/reoxygenation（H/R）-induced macrophages, while the inhibition of PKM2/NLRP3 reduced liver macrophage pyroptosis and liver IRI.

CONCLUSION

Ori exerted protective effects on liver IRI via suppressing PKM2/NLRP3-mediated liver macrophage pyroptosis, which might become a potential therapeutic target in the clinic.

NLRP3-dependent pyroptosis exacerbates coxsackievirus A16 and coxsackievirus A10-induced inflammatory response and viral replication in SH-SY5Y cells

Coxsackievirus A16 (CV-A16) and coxsackievirus A10 (CV-A10), more commonly etiological agents of hand, foot and mouth disease (HFMD), are capable of causing severe neurological syndromes with high fatalities, but their neuropathogenesis has rarely been studied. Mounting evidence indicated that pyroptosis is an inflammatory form of cell death that might be widely involved in the pathogenic mechanisms of neurotropic viruses. Our study was designed to examine the effects of NLRP3-mediated pyroptosis in CV-A16- and CV-A10-induced inflammatory neuropathologic formation. In this work, it was showed that SH-SY5Y cells were susceptible to CV-A16 and CV-A10, and meanwhile their infections could result in a decreasing cell viability and an increasing LDH release as well as Caspase1 activation. Moreover, CV-A16 and CV-A10 infections triggered NLRP3-mediated pyroptosis and promoted the release of inflammatory cytokines. Additionally, activated NLRP3 accelerated the pyroptosis formation and aggravated the inflammatory response, but inhibited NLRP3 had a dampening effect on the above situation. Finally, it was further revealed that NLRP3 agonist enhanced the viral replication, but NLRP3 inhibitor suppressed the viral replication, suggesting that NLRP3-driven pyroptosis might support CV-A16 and CV-A10 production in SH-SY5Y cells. Together, our findings demonstrated a mechanism by which CV-A16 and CV-A10 induce inflammatory responses by evoking NLRP3 inflammasome-regulated pyroptosis, which in turn further stimulated the viral replication, providing novel insights into the pathogenesis of CV-A16 and CV-A10 infections.

The interaction between RIPK1 and FADD controls perinatal lethality and inflammation

Perturbation of the apoptosis and necroptosis pathways critically influences embryogenesis. Receptor-associated protein kinase-1 (RIPK1) interacts with Fas-associated via death domain (FADD)-caspase-8-cellular Flice-like inhibitory protein long (cFLIPL) to regulate both extrinsic apoptosis and necroptosis. Here, we describe Ripk1-mutant animals (Ripk1R588E [RE]) in which the interaction between FADD and RIPK1 is disrupted, leading to embryonic lethality. This lethality is not prevented by further removal of the kinase activity of Ripk1 (Ripk1R588E K45A [REKA]). Both Ripk1RE and Ripk1REKA animals survive to adulthood upon ablation of Ripk3. While embryonic lethality of Ripk1RE mice is prevented by ablation of the necroptosis effector mixed lineage kinase-like (MLKL), animals succumb to inflammation after birth. In contrast, Mlkl ablation does not prevent the death of Ripk1REKA embryos, but animals reach adulthood when both MLKL and caspase-8 are removed. Ablation of the nucleic acid sensor Zbp1 largely prevents lethality in both Ripk1RE and Ripk1REKA embryos. Thus, the RIPK1-FADD interaction prevents Z-DNA binding protein-1 (ZBP1)-induced, RIPK3-caspase-8-mediated embryonic lethality, affected by the kinase activity of RIPK1.

Evolution of Caspases and the Invention of Pyroptosis

The protein scaffold that includes the caspases is ancient and found in all domains of life. However, the stringent specificity that defines the caspase biologic function is relatively recent and found only in multicellular animals. During the radiation of the Chordata, members of the caspase family adopted roles in immunity, events coinciding with the development of substrates that define the modern innate immune response. This review focuses on the switch from the non-inflammatory cellular demise of apoptosis to the highly inflammatory innate response driven by distinct members of the caspase family, and the interplay between these two regulated cell death pathways.

Did mitophagy follow the origin of mitochondria?

Mitophagy is the process of selective autophagy that removes superfluous and dysfunctional mitochondria. Mitophagy was first characterized in mammalian cells and is now recognized to follow several pathways including basal forms in specific organs. Mitophagy pathways are regulated by multiple, often interconnected factors. The present review aims to streamline this complexity and evaluate common elements that may define the evolutionary origin of mitophagy. Key issues surrounding mitophagy signaling at the mitochondrial surface may fundamentally derive from mitochondrial membrane dynamics. Elements of such membrane dynamics likely originated during the endosymbiosis of the alphaproteobacterial ancestor of our mitochondria but underwent an evolutionary leap forward in basal metazoa that determined the currently known variations in mitophagy signaling.Abbreviations: AGPAT, 1-acylglycerol-3-phosphate O-acyltransferase; ATG, autophagy related; BCL2L13, BCL2 like 13; BNIP3, BCL2 interacting protein 3; BNIP3L, BCL2 interacting protein 3 like; CALCOCO, calcium binding and coiled-coil domain; CL, cardiolipin; ER, endoplasmic reticulum; ERMES, ER-mitochondria encounter structure; FBXL4, F-box and leucine rich repeat protein 4; FUNDC1, FUN14 domain containing 1; GABARAPL1, GABA type A receptor associated protein like 1; HIF, hypoxia inducible factor; IMM, inner mitochondrial membrane; LBPA/BMP, lysobisphosphatidic acid; LIR, LC3-interacting region; LPA, lysophosphatidic acid; MAM, mitochondria-associated membranes; MAP1LC3/LC3, microtubule associated protein 1 light chain 3; MCL, monolysocardiolipin; ML, maximum likelihood; NBR1, NBR1 autophagy cargo receptor; OMM, outer mitochondrial membrane; PA, phosphatidic acid; PACS2, phosphofurin acidic cluster sorting protein 2; PC/PLC, phosphatidylcholine; PE, phosphatidylethanolamine; PHB2, prohibitin 2; PINK1, PTEN induced kinase 1; PtdIns, phosphatidylinositol; SAR, Stramenopiles, Apicomplexa and Rhizaria; TAX1BP1, Tax1 binding protein 1; ULK1, unc-51 like autophagy activating kinase 1; VDAC/porin, voltage dependent anion channel.

Diabetic Cardiomyopathy and Cell Death: Focus on Metal-Mediated Cell Death

Cardiac myocyte death is an essential initiator of the pathogenesis and progression of various etiological cardiomyopathies, including diabetic cardiomyopathy (DCM), a disease that has been reported since 1972. Cardiac cell death has been detected in the hearts of patients with diabetes and in animal models, and the role of cell death in the pathogenesis of DCM has been extensively investigated. The first review by the authors, specifically focusing on "Cell death and diabetic cardiomyopathy," was published in the journal, Cardiovascular Toxicology in 2003. Over the past two decades, studies investigating the role of cardiac cell death in the pathogenesis of DCM have gained significant attention, resulting in the discovery of several new kinds of cell death involving different mechanisms, including apoptosis, necroptosis, pyroptosis, autophagy, ferroptosis, and cuproptosis. After the 20th anniversary of the review published in 2003, we now provide an update with a focus on the potential role of metal-mediated cell death, ferroptosis, and cuproptosis in the development of DCM in compliance with this special issue. The intent of our review is to further stimulate work in the field to advance the body of knowledge and continue to drive efforts to develop more advanced therapeutic approaches to prevent cell death, particularly metal-dependent cell death, and, ultimately, to reduce or prevent the development of DCM.

Pyroptosis: Mechanisms and links with diabetic cardiomyopathy

Diabetes mellitus (DM) is a chronic metabolic disease characterized by hyperglycaemia that seriously affects human health. Diabetic cardiomyopathy (DCM) is a major cardiovascular complication and one of the main causes of death in patients with DM. Although DCM attracts great attention, and new therapeutic methods are continuously developed, there is a lack of effective treatment strategies. Therefore, exploring and targeting new signalling pathways related to the evolution of DCM becomes a hotspot and difficulty in the prevention and treatment of DCM. Pyroptosis is a newly discovered regulated cell death that is heavily dependent on the formation of plasma membrane pores by members of the gasdermin protein family and is reported to be involved in the occurrence, development, and pathogenesis of DCM. In this review, we focus on the molecular mechanisms of pyroptosis, its involvement in the relevant signalling pathways of DCM, and potential pyroptosis-targeting therapeutic strategies for the treatment of DCM. Our review provides new insights into the use of pyroptosis as a useful tool for the prevention and treatment of DCM and clarifies future research directions.

Prognostic Impact of Heat Shock Protein 90 Expression in Women Diagnosed with Cervical Cancer

Heat Shock Protein 90 (HSP90), a major molecular chaperone, plays a crucial role in cell function by folding and stabilizing proteins and maintaining proteostasis. This study aimed to elucidate the prognostic impact of HSP90 in cervical cancer. We analyzed HSP90 expression using immunohistochemistry in cervical cancer tissue microarrays from 250 patients. This study investigated correlations between HSP90 expression levels and key clinical outcomes, including overall survival (OS), progression-free survival (PFS), and FIGO classification. The statistical analyses employed included the Kruskal-Wallis-H test, log-rank (Mantel-Cox), and Cox regression. Our findings indicate that high nuclear HSP90 expression is associated with improved OS, while high cytoplasmic HSP90 expression correlates with better PFS and a lower FIGO classification in cervical squamous cell carcinoma patients. These results suggest that HSP90 could serve as a positive prognostic factor in patients diagnosed with cervical squamous cell carcinoma, underlining its potential as a biomarker for patient prognosis and as a target for therapeutic strategies.

Paralichthys olivaceus MLKL-mediated necroptosis is activated by RIPK1/3 and involved in anti-microbial immunity

Necroptosis is a type of proinflammatory programmed necrosis essential for innate immunity. The receptor interacting protein kinases 1/3 (RIPK1/3) and the substrate mixed lineage kinase domain-like protein (MLKL) are core components of the necroptotic axis. The activation and immunological function of necroptosis in fish remain elusive. Herein, we studied the function and activation of RIPK1/3 (PoRIPK1/3) and MLKL (PoMLKL) in teleost Paralichthys olivaceus. Bacterial infection increased the expression of RIPK1/3 and MLKL. The N-terminal four-helix bundle (4HB) domain of PoMLKL exhibited necroptosis-inducing activity, and the C-terminal pseudokinase domain exerted auto-inhibitory effect on the 4HB domain. PoRIPK3 was capable of phosphorylating the T360/S361 residues in the PoMLKL C-terminal domain and initiated necroptosis, and this necroptosis-inducing activity was enhanced by PoRIPK1. PoRIPK1/3 interacted with PoMLKL in a manner that depended on the RIP homotypic interaction motif (RHIM), and deletion of RHIM from PoRIPK1/3 led to the dissociation of PoRIPK1/3 with PoMLKL. Inhibition of PoMLKL-mediated necroptosis increased Edwardsiella tarda infection in fish cells and tissues, and led to significantly enhanced lethality of the host. Taken together, these results revealed the activation mechanism of PoRIPK1/3-PoMLKL signaling pathway and the immunological function of necroptosis in the immune defense of teleost.

Melatonin, a potentially effective drug for the treatment of infected bone nonunion

Osteomyelitis (OM), characterized by heterogeneity and complexity in treatment, has a high risk of infection recurrence which may cause limb disability. Management of chronic inactive osteomyelitis (CIOM) without typical inflammatory symptoms is a great challenge for orthopedic surgeons. On the basis of data analysis of 1091 OM cases, we reported that latent osteogenic decline in CIOM patients was the main cause of secondary surgery. Our research shows that impairment of osteoblasts capacity in CIOM patients is associated with ferroptosis of osteoblasts caused by internalization of Staphylococcus aureus. Further studies show that melatonin could alleviate ferroptosis of osteoblasts in infected states through Nox4/ROS/P38 axis and protect the osteogenic ability of CIOM patients. Knockout of NADPH oxidase 4 (Nox4) in vivo could effectively relieve ferroptosis of osteoblasts in the state of infection and promote osteogenesis. Through a large number of clinical data analyses combined with molecular experiments, this study clarified that occult osteogenic disorders in CIOM patients were related to ferroptosis of osteoblasts. We revealed that melatonin might be a potential therapeutic drug for CIOM patients and provided a new insight for the treatment of OM.

Green synthesis and anti-tumor efficacy via inducing pyroptosis of novel 1H-benzo[e]indole-2(3H)-one spirocyclic derivatives

Pyroptosis induction is anticipated to be a new approach to developing anti-tumor medications. A novel class of spirocyclic compounds was designed by hybridization of 1H-Benzo[e]indole-2(3H)-one with 1,4-dihydroquinoline and synthesized through a new green "one-pot" synthesis method using 10 wt% SDS/H2O as a solvent to screen novel tumor cell pyroptosis inducers. The anti-tumor activity of all compounds in vitro was determined by the MTT method, and a fraction of the compounds showed good cell growth inhibitory activity. The quantitative structure-activity relationship models of the compounds were established by artificial intelligence random forest algorithm (R2 = 0.9656 and 0.9747). The ideal compound A9 could, in a concentration-dependent manner, prevent ovarian cancer cells from forming colonies, migrating, and invading. Furthermore, A9 could significantly induce pyroptosis and upregulate the expression of pyroptosis-related proteins GSDME-N, in addition to inducing apoptosis and mediating the expression of apoptosis-related proteins in ovarian cancer cells. A9 (5 mg/kg) significantly reduced tumor volume and weight of ovarian cancer in vivo, decreased caspase-3 expression in tumor tissue, and induced the production of GSDME-N. This study provides a green and efficient atom-economic synthesis method for 1H-Benzo[e]indole-2(3H)-one spirocyclic derivatives and a promising pyroptosis inducer with anti-tumor activity.

The neuropathological mechanism of EV-A71 infection attributes to inflammatory pryoptosis and viral replication via activating the hsa_circ_0045431/ hsa_miR_584/NLRP3 regulatory axis

Neuropathological damage has been considered to be the main cause of death from EV-A71 infection, but the underlying mechanism has not been elucidated. Pyroptosis, a new form of inflammatory programmed cell death, has been verified to be involved in the pathogenesis of various viruses. circRNAs are a novel type of endogenous noncoding RNA gaining research interest in recent years, especially their special roles in the process of virus infection. Thus, in this study, we combined EV-A71, pyroptosis and circRNA to find a breakthrough in the pathogenesis of EV-A71 infection. Firstly, whether EV-A71 infection leaded to pyroptosis formation was examined by a series detection of cell death, cell viability, LDH release, caspase 1 activity, the expression levels of pyroptosis-related molecules and the concentrations of IL-1β and IL-18. Secondly, high-throughput sequencing of circRNAs was carried out to excavate the circRNA-miRNA-mRNA regulatory axis which might be associated with pyroptosis formation. Finally, the gain- and loss-of-functional experiments were further conducted to identify their functions. Our results showed that EV-A71 infection caused pyroptosis formation in SH-SY5Y cells. The circRNA sequencing analyzed the differentially expressed circRNAs and their possible functions. It was found that the hsa_circ_0045431/hsa_miR_584/NLRP3 regulatory axis might be involved in pyroptosis formation during EV-A71 infection. Then, hsa_circ_0045431 sponged hsa_miR_584 and hsa_miR_584 directly targeted NLRP3 were validated by IF, dual-luciferase, qRT-PCR and WB assays. Functional experiments were performed to further uncover that the up-regulation of hsa_circ_0045431 and NLRP3 promoted the inflammatory pyroptosis and viral replication, while the up-regulation of hsa_miR_584 suppressed the inflammatory pyroptosis and viral replication, and vice versa. Collectively, our study demystified that EV-A71 infection induced pyroptosis formation by activating hsa_circ_0045431/hsa_miR_584/NLRP3 regulatory axis, which could further effect viral replication. These findings provided novel insights into the pathogenesis of EV-A71 infection, and meanwhile revealed that the hsa_circ_0045431/ hsa_miR_584/NLRP3 regulatory axis can serve as a potential biological therapeutic target for EV-A71 infection.

Mitochondria in health, disease, and aging

Mitochondria are well known as organelles responsible for the maintenance of cellular bioenergetics through the production of ATP. Although oxidative phosphorylation may be their most important function, mitochondria are also integral for the synthesis of metabolic precursors, calcium regulation, the production of reactive oxygen species, immune signaling, and apoptosis. Considering the breadth of their responsibilities, mitochondria are fundamental for cellular metabolism and homeostasis. Appreciating this significance, translational medicine has begun to investigate how mitochondrial dysfunction can represent a harbinger of disease. In this review, we provide a detailed overview of mitochondrial metabolism, cellular bioenergetics, mitochondrial dynamics, autophagy, mitochondrial damage-associated molecular patterns, mitochondria-mediated cell death pathways, and how mitochondrial dysfunction at any of these levels is associated with disease pathogenesis. Mitochondria-dependent pathways may thereby represent an attractive therapeutic target for ameliorating human disease.

Inflammasomes as regulators of non-infectious disease

Inflammasomes are cytoplasmic organelles that stimulate inflammation upon cellular detection of infectious or non-infectious stress. While much foundational work has focused on the infection-associated aspects of inflammasome activities, recent studies have highlighted the role of inflammasomes in non-infectious cellular and organismal functions. Herein, we discuss the evolution of inflammasome components and highlight characteristics that permit inflammasome regulation of physiologic processes. We focus on emerging data that highlight the importance of inflammasome proteins in the regulation of reproduction, development, and malignancy. A framework is proposed to contextualize these findings.

The Achromobacter type 3 secretion system drives pyroptosis and immunopathology via independent activation of NLRC4 and NLRP3 inflammasomes

How the opportunistic Gram-negative pathogens of the genus Achromobacter interact with the innate immune system is poorly understood. Using three Achromobacter clinical isolates from two species, we show that the type 3 secretion system (T3SS) is required to induce cell death in human macrophages by inflammasome-dependent pyroptosis. Macrophages deficient in the inflammasome sensors NLRC4 or NLRP3 undergo pyroptosis upon bacterial internalization, but those deficient in both NLRC4 and NLRP3 do not, suggesting either sensor mediates pyroptosis in a T3SS-dependent manner. Detailed analysis of the intracellular trafficking of one isolate indicates that the intracellular bacteria reside in a late phagolysosome. Using an intranasal mouse infection model, we observe that Achromobacter damages lung structure and causes severe illness, contingent on a functional T3SS. Together, we demonstrate that Achromobacter species can survive phagocytosis by promoting macrophage cell death and inflammation by redundant mechanisms of pyroptosis induction in a T3SS-dependent manner.

Expression patterns and immunological characterization of PANoptosis -related genes in gastric cancer

Background

Accumulative studies have demonstrated the close relationship between tumor immunity and pyroptosis, apoptosis, and necroptosis. However, the role of PANoptosis in gastric cancer (GC) is yet to be fully understood.

Methods

This research attempted to identify the expression patterns of PANoptosis regulators and the immune landscape in GC by integrating the GSE54129 and GSE65801 datasets. We analyzed GC specimens and established molecular clusters associated with PANoptosis-related genes (PRGs) and corresponding immune characteristics. The differentially expressed genes were determined with the WGCNA method. Afterward, we employed four machine learning algorithms (Random Forest, Support Vector Machine, Generalized linear Model, and eXtreme Gradient Boosting) to select the optimal model, which was validated using nomogram, calibration curve, decision curve analysis (DCA), and two validation cohorts. Additionally, this study discussed the relationship between infiltrating immune cells and variables in the selected model.

Results

This study identified dysregulated PRGs and differential immune activities between GC and normal samples, and further identified two PANoptosis-related molecular clusters in GC. These clusters demonstrated remarkable immunological heterogeneity, with Cluster1 exhibiting abundant immune infiltration. The Support Vector Machine signature was found to have the best discriminative ability, and a 5-gene-based SVM signature was established. This model showed excellent performance in the external validation cohorts, and the nomogram, calibration curve, and DCA indicated its reliability in predicting GC patterns. Further analysis confirmed that the 5 selected variables were remarkably related to infiltrating immune cells and immune-related pathways.

Conclusion

Taken together, this work demonstrates that the PANoptosis pattern has the potential as a stratification tool for patient risk assessment and a reflection of the immune microenvironment in GC.

Regulated cell death pathways in cardiomyopathy

Heart disease is a worldwide health menace. Both intractable primary and secondary cardiomyopathies contribute to malignant cardiac dysfunction and mortality. One of the key cellular processes associated with cardiomyopathy is cardiomyocyte death. Cardiomyocytes are terminally differentiated cells with very limited regenerative capacity. Various insults can lead to irreversible damage of cardiomyocytes, contributing to progression of cardiac dysfunction. Accumulating evidence indicates that majority of cardiomyocyte death is executed by regulating molecular pathways, including apoptosis, ferroptosis, autophagy, pyroptosis, and necroptosis. Importantly, these forms of regulated cell death (RCD) are cardinal features in the pathogenesis of various cardiomyopathies, including dilated cardiomyopathy, diabetic cardiomyopathy, sepsis-induced cardiomyopathy, and drug-induced cardiomyopathy. The relevance between abnormity of RCD with adverse outcome of cardiomyopathy has been unequivocally evident. Therefore, there is an urgent need to uncover the molecular and cellular mechanisms for RCD in order to better understand the pathogenesis of cardiomyopathies. In this review, we summarize the latest progress from studies on RCD pathways in cardiomyocytes in context of the pathogenesis of cardiomyopathies, with particular emphasis on apoptosis, necroptosis, ferroptosis, autophagy, and pyroptosis. We also elaborate the crosstalk among various forms of RCD in pathologically stressed myocardium and the prospects of therapeutic applications targeted to various cell death pathways.

Defective efferocytosis by aged macrophages promotes STING signaling mediated inflammatory liver injury

Aged livers have shown aggravated liver ischemia and reperfusion (IR) injury. Timely efferocytosis of apoptotic cells is a key mechanism for avoiding excessive inflammation and tissue injury. Here, we investigated the alteration of efferocytosis by aged macrophages and its role in regulating macrophage STING (stimulator of interferon genes) signaling and liver IR injury. Aged and young mice were subjected to liver partial IR model. Liver injury and inflammation were measured. Efferocytosis by aged macrophages and the underlying regulatory mechanism were analyzed as well. Aged macrophages exhibited impaired efferocytosis with decreased MerTK (c-mer proto-oncogene tyrosine kinase) activation, which was reversed by treatment of the MerTK CRISPR activation plasmid. Increased MerTK cleavage by ADAM17 (a disintegrin and metalloproteinase 17) due to enhanced ROS (reactive oxygen species) levels contributed to defective efferocytosis by aged macrophages. MerTK activation by suppressing ADAM17 or ROS improved aged macrophage efferocytosis, leading to reduced inflammatory liver injury. Moreover, increased apoptotic hepatocytes, DNA accumulation, and macrophage STING activation were observed in aged ischemic livers. Improvement in efferocytosis by aged macrophages via MerTK activation suppressed STING activation and inflammatory liver injury. Our study demonstrates that aging suppresses MerTK- mediated macrophage efferocytosis to promote macrophage STING activation and inflammatory liver IR injury, suggesting a new mechanism and potential therapy to promote inflammation resolution and efferocytosis in aged livers.

A novel colchicine-myricetin heterozygous molecule: design, synthesis, and effective evaluations on the pathological models of acute lung injury in vitro and in vivo

Acute lung injury (ALI) is an inflammatory condition and there are no effective treatments. A novel new compound----colchicine-myricetin hybrid (CMyrH) was herein designed and synthesized. To evaluate the activity of CMyrH in ALI, we used a bleomycin (BLM) induced BEAS-2B injury model in vitro and established a well-recognized rat model of BLM-induced lung injury in vivo. The results demonstrated that colchicine-myricetin hybrid protected BEAS-2B cells against BLM-induced cell injury in an increased dose manner, and reduced wet/dry weight ratio, histological scoring, and inflammation cytokines IL-1β, IL-6, IL-18, and TNF-α levels of lung tissue of the rats. Furthermore, we found colchicine-myricetin hybrid inhibited caspase-1, ASC, GSDMD, and NLRP-3 expression in vivo. Meanwhile, we used molecular docking to analyze the binding mode of colchicine-myricetin hybrid and human neutrophil elastase (HNE), it revealed that colchicine-myricetin hybrid showed strong binding affinity toward human neutrophil elastase when compared to its parent molecules. In conclusion, It is suggested that colchicine-myricetin hybrid antagonized acute lung injury by focusing on multi-targets via multi-mechanisms, and might be served as a potential therapeutic agent for acute lung injury.

Cell death checkpoints in the TNF pathway

Tumor necrosis factor (TNF) plays a central role in orchestrating mammalian inflammatory responses. It promotes inflammation either directly by inducing inflammatory gene expression or indirectly by triggering cell death. TNF-mediated cell death-driven inflammation can be beneficial during infection by providing cell-extrinsic signals that help to mount proper immune responses. Uncontrolled cell death caused by TNF is instead highly detrimental and is believed to cause several human autoimmune diseases. Death is not the default response to TNF sensing. Molecular brakes, or cell death checkpoints, actively repress TNF cytotoxicity to protect the organism from its detrimental consequences. These checkpoints therefore constitute essential safeguards against inflammatory diseases. Recent advances in the field have revealed the existence of several new and unexpected brakes against TNF cytotoxicity and pathogenicity.

Whole-genome CRISPR screen identifies RAVER1 as a key regulator of RIPK1-mediated inflammatory cell death, PANoptosis

Transforming growth factor-β-activated kinase 1 (TAK1) is a central regulator of innate immunity, cell death, inflammation, and cellular homeostasis. Therefore, many pathogens carry TAK1 inhibitors (TAK1i). As a host strategy to counteract this, inhibition or deletion of TAK1 induces spontaneous inflammatory cell death, PANoptosis, through the RIPK1-PANoptosome complex, containing the NLRP3 inflammasome and caspase-8/FADD/RIPK3 as integral components; however, PANoptosis also promotes pathological inflammation. Therefore, understanding molecular mechanisms that regulate TAK1i-induced cell death is essential. Here, we report a genome-wide CRISPR screen in macrophages that identified TAK1i-induced cell death regulators, including polypyrimidine tract-binding (PTB) protein 1 (PTBP1), a known regulator of RIPK1, and a previously unknown regulator RAVER1. RAVER1 blocked alternative splicing of Ripk1, and its genetic depletion inhibited TAK1i-induced, RIPK1-mediated inflammasome activation and PANoptosis. Overall, our CRISPR screen identified several positive regulators of PANoptosis. Moreover, our study highlights the utility of genome-wide CRISPR-Cas9 screens in myeloid cells for comprehensive characterization of complex cell death pathways to discover therapeutic targets.

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.

Oxidative Stress Induced by Selenium Deficiency Contributes to Inflammation, Apoptosis and Necroptosis in the Lungs of Calves

Selenium is an essential trace element for health that can only be obtained through food. However, the pathological processes of selenium deficiency in cattle have received little attention. This study investigated the effects of selenium deficiency on oxidative stress, apoptosis, inflammation, and necroptosis in the lungs of weaning calves compared with healthy calves as controls. The lung selenium content and the expression of 11 selenoproteins mRNA in selenium-deficient calves were substantially reduced compared with the controls. Pathological results showed engorged alveolar capillaries, thickened alveolar septa, and diffuse interstitial inflammation throughout the alveolar septa. The levels of GSH and T-AOC, as well as the CAT, SOD, and TrxR activities, were significantly decreased compared with healthy calves. MDA and H₂O₂ were significantly elevated. Meanwhile, the apoptosis activation in the Se-D group was validated. Next, in the Se-D group, several pro-inflammatory cytokines showed higher expression. Further research revealed that the lungs in the Se-D group experienced inflammation via hyperactive NF-κB and MAPK pathways. The high level of expression of c-FLIP, MLKL, RIPK1, and RIPK3 indicated that necroptosis also causes lung damage during selenium deficiency.

CircSHOC2 Knockdown Alleviates High Glucose-Induced Vascular Endothelial Cell Pyroptosis via Targeting miR-145/FOXO1 Axis In Vitro Condition

Emerging evidence indicates that pyroptosis participates in the pathogenic process of vascular endothelial cells in cardiovascular system complications of diabetes. The roles of circular RNAs (circRNAs) in high glucose (HG)-induced vascular endothelial cells are still unclear. Here, our research investigated the function and mechanism of circRNA circSHOC2 in pyroptosis of vascular endothelial cells. Results indicated that circSHOC2 was up-regulated in HG-induced human umbilical vein endothelial cells (HUVECs). Functionally, cellular assays indicated that circSHOC2 silencing repressed HG-induced HUVECs pyroptosis. Moreover, circSHOC2 targeted miR-145 through miRNA sponge, and FOXO1 functioned as downstream target of miR-145. In conclusion, these findings suggested the potential roles of circSHOC2 on HG-induced vascular endothelial cells in vitro condition, providing new insights for cardiovascular system complications of diabetes.

Selenium Deficiency-Induced Oxidative Stress Causes Myocardial Injury in Calves by Activating Inflammation, Apoptosis, and Necroptosis

Selenium (Se) is essential for human and animal health, but there have been few studies on the mechanisms of injury in dairy cows with Se deficiency. This study aimed to evaluate the effects of Se deficiency on myocardial injury in weaned calves. The Se-D group had significantly lower myocardial Se concentrations than the Se-C group. Histological analysis indicated that Se deficiency induced a large area of necrosis in the myocardium, accompanied by inflammatory changes. Se deficiency significantly decreased the expression of 10 of the 21 selenoprotein genes and increased the expression of SEPHS2. Furthermore, we found that oxidative stress occurred in the Se-D group by detection of redox-related indicators. Additionally, TUNEL staining showed that Se deficiency causes severe apoptosis in the myocardium, which was characterized by activating the exogenous apoptotic pathway and the mitochondrial apoptotic pathway. Se deficiency also induced necroptosis in the myocardium by upregulating MLKL, RIPK1, and RIPK3. Moreover, Se-deficient calves have severe inflammation in the myocardium. Se deficiency significantly reduced anti-inflammatory factor levels while increasing pro-inflammatory factor levels. We also found that the NF-κB pathway and MAPK pathway were activated in Se-deficient conditions. Our findings suggest that Se deficiency causes myocardial injury in weaned calves by regulating oxidative stress, inflammation, apoptosis, and necroptosis.

Pyroptosis in bone loss

Pyroptosis could be responsible for the bone loss from bone metabolic diseases, leading to the negative impact on people's health and life. It has been shown that osteoclasts, osteoblasts, macrophages, chondrocytes, periodontal and gingival cells may be involved in bone loss linked with pyroptosis. So far, the involved mechanisms have not been fully elucidated. In this review, we introduced the related cells involved in the pyroptosis associated with bone loss and summarized the role of these cells in the bone metabolism during the process of pyroptosis. We also discuss the clinical potential of targeting mechanisms in the osteoclasts, osteoblasts, macrophages, chondrocytes, periodontal and gingival cells touched upon pyroptosis to treat bone loss from bone metabolic diseases as well as the challenges of avoiding potential side effects and producing efficient treatment methods.

Role of necroptosis in kidney health and disease

Cell death, particularly that of tubule epithelial cells, contributes critically to the pathophysiology of kidney disease. A body of evidence accumulated over the past 15 years has ascribed a central pathophysiological role to a particular form of regulated necrosis, termed necroptosis, to acute tubular necrosis, nephron loss and maladaptive renal fibrogenesis. Unlike apoptosis, which is a non-immunogenic process, necroptosis results in the release of cellular contents and cytokines, which triggers an inflammatory response in neighbouring tissue. This necroinflammatory environment can lead to severe organ dysfunction and cause lasting tissue injury in the kidney. Despite evidence of a link between necroptosis and various kidney diseases, there are no available therapeutic options to target this process. Greater understanding of the molecular mechanisms, triggers and regulators of necroptosis in acute and chronic kidney diseases may identify shortcomings in current approaches to therapeutically target necroptosis regulators and lead to the development of innovative therapeutic approaches.

Pyroptosis Provides New Strategies for the Treatment of Cancer

Cancer is an important cause of death worldwide. The main types of cancer treatment are still surgery, chemotherapy and radiotherapy, and immunotherapy is becoming an important cancer treatment. Pyroptosis is a type of programmed cell death that accompanies an inflammatory response. This paper reviews the recent research progress in pyroptosis in tumors. Pyroptosis has been observed since 1986 and until recently has been recognized as programmed cell death mediated by GSDM family proteins. The molecular pathway of pyroptosis depends on the inflammasome-mediated caspase-1/GSDMD pathway, which is the canonical pathway, and the caspase-4/5/11/GSDMD pathway, which is the noncanonical pathway. Other pathways include caspase3/GSDME. Pyroptosis is a double-edged sword that is closely related to the tumor immune microenvironment. On the one hand, pyroptosis produces a chronic inflammatory environment, promotes the transition of normal cells to tumor cells, helps tumor cells achieve immune escape, and promotes tumor growth and metastasis. On the other hand, some tumor cell treatments can induce pyroptosis, which is a nonapoptotic form of cell death. Additionally, pyroptosis releases inflammatory molecules that promote lymphocyte recruitment and enhance the immune system's ability to kill tumor cells. With the advent of immunotherapy, pyroptosis has been shown to enhance the antitumor efficacy of immune checkpoint inhibitors. Some antineoplastic agents, such as chemotherapeutic agents, can also exert antineoplastic effects through the pyroptosis pathway. Pyroptosis, which is a programmed cell death mode, has been the focus of research in recent years, and the relationship between pyroptosis, tumors and tumor immunity has attracted attention, but there are still some questions to be answered regarding the specific mechanism. Further study of pyroptosis would aid in developing new antitumor therapies and has great clinical prospects.

Programmed Necrosis in Host Defense

Host control over infectious disease relies on the ability of cells in multicellular organisms to detect and defend against pathogens to prevent disease. Evolution affords mammals with a wide variety of independent immune mechanisms to control or eliminate invading infectious agents. Many pathogens acquire functions to deflect these immune mechanisms and promote infection. Following successful invasion of a host, cell autonomous signaling pathways drive the production of inflammatory cytokines, deployment of restriction factors and induction of cell death. Combined, these innate immune mechanisms attract dendritic cells, neutrophils and macrophages as well as innate lymphoid cells such as natural killer cells that all help control infection. Eventually, the development of adaptive pathogen-specific immunity clears infection and provides immune memory of the encounter. For obligate intracellular pathogens such as viruses, diverse cell death pathways make a pivotal contribution to early control by eliminating host cells before progeny are produced. Pro-apoptotic caspase-8 activity (along with caspase-10 in humans) executes extrinsic apoptosis, a nonlytic form of cell death triggered by TNF family death receptors (DRs). Over the past two decades, alternate extrinsic apoptosis and necroptosis outcomes have been described. Programmed necrosis, or necroptosis, occurs when receptor interacting protein kinase 3 (RIPK3) activates mixed lineage kinase-like (MLKL), causing cell leakage. Thus, activation of DRs, toll-like receptors (TLRs) or pathogen sensor Z-nucleic acid binding protein 1 (ZBP1) initiates apoptosis as well as necroptosis if not blocked by virus-encoded inhibitors. Mammalian cell death pathways are blocked by herpesvirus- and poxvirus-encoded cell death suppressors. Growing evidence has revealed the importance of Z-nucleic acid sensor, ZBP1, in the cell autonomous recognition of both DNA and RNA virus infection. This volume will explore the detente between viruses and cells to manage death machinery and avoid elimination to support dissemination within the host animal.

RIPK1 and RIPK3 are positive prognosticators for cervical cancer patients and C2 ceramide can inhibit tumor cell proliferation in vitro

Introduction

The enzymes Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) und 3 (RIPK3) as well as the protein Mixed lineage kinase domain like pseudokinase (pMLKL) play a role in the signaling cascade of necroptosis. This is a form of programmed cell death which is caspase-independent. High-risk human papilloma virus infection can inhibit necroptosis. Thereby, a persistent infection and consequently the development of cervical cancer can be triggered. Aim of this study was the analysis of the expression of RIPK1, RIPK3 and pMLKL in cervical cancer tissue and the evaluation of its prognostic value on overall survival, progression-free survival and additional clinical parameters.

Methods

The expression of RIPK1, RIPK3, and pMLKL in cervical cancer tissue microarrays of n = 250 patients was analyzed immunohistochemically. Further, the effect of C2 ceramide on several cervical cancer cell lines (CaSki, HeLa, SiHa) was examined. C2 ceramide is a biologically active short-chain ceramide that induces necroptosis in human luteal granulosa cells.

Results

Significantly longer overall survival and progression-free survival rates could be detected in cervical cancer patients expressing nuclear RIPK1 or RIPK3 alone or simultaneously (RIPK1 and RIPK3). Cell viability and proliferation was reduced through C2 ceramide stimulation of cervical cancer cells. Simultaneous stimulation of C2 ceramide and the pan-caspase inhibitor Z-VAD-fmk, or the RIPK1-inhibitor necrostatin-1, partly reversed the negative effect of C2 ceramide on cell viability. This observation could imply that caspase-dependent and -independent forms of cell death, including necroptosis, can occur. AnnexinV-FITC apoptosis staining induced a significant increase in apoptotic cells in CaSki and SiHa cells. The stimulation of CaSki cells with C2 ceramide led to a significant percentual increase in necrotic/intermediate (dying) cells after stimulation with C2 ceramide. In addition, after stimulation with C2 ceramide, CaSki and HeLa cells live cell imaging showed morphological changes which are common for necroptosis.

Discussion

In conclusion, RIPK1 and RIPK3 are independent positive predictors for overall survival and progression-free survival in cervical cancer patients. C2 ceramide can reduce cell viability and proliferation in cervical cancer cells by inducing most likely both apoptosis and necroptosis.

Triacetyl Resveratrol Inhibits PEDV by Inducing the Early Apoptosis In Vitro

PEDV represents an ancient Coronavirus still causing huge economic losses to the porcine breeding industry. Resveratrol has excellent antiviral effects. Triacetyl resveratrol (TCRV), a novel natural derivative of resveratrol, has been recently discovered, and its pharmacological effects need to be explored further. This paper aims to explore the relationship between PEDV and TCRV, which offers a novel strategy in the research of antivirals. In our study, Vero cells and IPEC-J2 cells were used as an in vitro model. First, we proved that TCRV had an obvious anti-PEDV effect and a strong inhibitory effect at different time points. Then, we explored the mechanism of inhibition of PEDV infection by TCRV. Our results showed that TCRV could induce the early apoptosis of PEDV-infected cells, in contrast to PEDV-induced apoptosis. Moreover, we observed that TCRV could promote the expression and activation of apoptosis-related proteins and release mitochondrial cytochrome C into cytoplasm. Based on these results, we hypothesized that TCRV induced the early apoptosis of PEDV-infected cells and inhibited PEDV infection by activating the mitochondria-related caspase pathway. Furthermore, we used the inhibitors Z-DEVD-FMK and Pifithrin-α (PFT-α) to support our hypothesis. In conclusion, the TCRV-activated caspase pathway triggered early apoptosis of PEDV-infected cells, thereby inhibiting PEDV infections.

Death by TNF: a road to inflammation

Tumour necrosis factor (TNF) is a central cytokine in inflammatory reactions, and biologics that neutralize TNF are among the most successful drugs for the treatment of chronic inflammatory and autoimmune pathologies. In recent years, it became clear that TNF drives inflammatory responses not only directly by inducing inflammatory gene expression but also indirectly by inducing cell death, instigating inflammatory immune reactions and disease development. Hence, inhibitors of cell death are being considered as a new therapy for TNF-dependent inflammatory diseases.

Mitochondria supply sub-lethal signals for cytokine secretion and DNA-damage in H. pylori infection

The bacterium Helicobacter pylori induces gastric inflammation and predisposes to cancer. H. pylori-infected epithelial cells secrete cytokines and chemokines and undergo DNA-damage. We show that the host cell's mitochondrial apoptosis system contributes to cytokine secretion and DNA-damage in the absence of cell death. H. pylori induced secretion of cytokines/chemokines from epithelial cells, dependent on the mitochondrial apoptosis machinery. A signalling step was identified in the release of mitochondrial Smac/DIABLO, which was required for alternative NF-κB-activation and contributed to chemokine secretion. The bacterial cag-pathogenicity island and bacterial muropeptide triggered mitochondrial host cell signals through the pattern recognition receptor NOD1. H. pylori-induced DNA-damage depended on mitochondrial apoptosis signals and the caspase-activated DNAse. In biopsies from H. pylori-positive patients, we observed a correlation of Smac-levels and inflammation. Non-apoptotic cells in these samples showed evidence of caspase-3-activation, correlating with phosphorylation of the DNA-damage response kinase ATM. Thus, H. pylori activates the mitochondrial apoptosis pathway to a sub-lethal level. During infection, Smac has a cytosolic, pro-inflammatory role in the absence of apoptosis. Further, DNA-damage through sub-lethal mitochondrial signals is likely to contribute to mutagenesis and cancer development.

Mechanisms of TNF-independent RIPK3-mediated cell death

Apoptosis and necroptosis regulate many aspects of organismal biology and are involved in various human diseases. TNF is well known to induce both of these forms of cell death and the underlying mechanisms have been elaborately described. However, cells can also engage apoptosis and necroptosis through TNF-independent mechanisms, involving, for example, activation of the pattern recognition receptors Toll-like receptor (TLR)-3 and -4, or zDNA-binding protein 1 (ZBP1). In this context, cell death signaling depends on the presence of receptor-interacting serine/threonine protein kinase 3 (RIPK3). Whereas RIPK3 is required for TNF-induced necroptosis, it mediates both apoptosis and necroptosis upon TLR3/4 and ZBP1 engagement. Here, we review the intricate mechanisms by which TNF-independent cell death is regulated by RIPK3.

Eugenol Attenuates Transmissible Gastroenteritis Virus-Induced Oxidative Stress and Apoptosis Via ROS-NRF2-ARE Signaling

Transmissible gastroenteritis virus (TGEV), a coronavirus that causes severe diarrhea due to oxidative stress in the piglet intestine, is a major cause of economic loss in the livestock industry. However, limited interventions have been shown to be effective in the treatment of TGEV. Here, we demonstrate the therapeutic activity of eugenol in TGEV-induced intestinal oxidative stress and apoptosis. Our data show that eugenol supplementation protects intestine and IPEC-J2 cells from TGEV-induced damage. Mechanistically, eugenol reduces TGEV-induced oxidative stress in intestinal epithelial cells by reducing reactive oxygen species levels. Interestingly, eugenol also inhibits TGEV-induced intestinal cell apoptosis in vitro and in vivo. In conclusion, our data suggest that eugenol prevents TGEV-induced intestinal oxidative stress by reducing ROS-mediated damage to antioxidant signaling pathways. Therefore, eugenol may be a promising therapeutic strategy for TGEV infection.

The role of RHIM in necroptosis

The RIP homotypic interaction motif (RHIM) is a conserved protein domain that is approximately 18–22 amino acids in length. In humans, four proteins carrying RHIM domains have been identified: receptor-interacting serine/threonine protein kinase (RIPK) 1, RIPK3, Z-DNA-binding protein 1 (ZBP1), and TIR domain-containing adapter-inducing IFN-β (TRIF), which are all major players in necroptosis, a distinct form of regulated cell death. Necroptosis is mostly presumed to be a fail-safe form of cell death, occurring in cells in which apoptosis is compromised. Upon activation, RIPK1, ZBP1, and TRIF each hetero-oligomerize with RIPK3 and induce the assembly of an amyloid-like structure of RIPK3 homo-oligomers. These act as docking stations for the recruitment of the pseudokinase mixed-lineage kinase domain like (MLKL), the pore-forming executioner of necroptosis. As RHIM domain interactions are a vital component of the signaling cascade and can also be involved in apoptosis and pyroptosis activation, it is unsurprising that viral and bacterial pathogens have developed means of disrupting RHIM-mediated signaling to ensure survival. Moreover, as these mechanisms play an essential part of regulated cell death signaling, they have received much attention in recent years. Herein, we present the latest insights into the supramolecular structure of interacting RHIM proteins and their distinct signaling cascades in inflammation and infection. Their uncovering will ultimately contribute to the development of new therapeutic strategies in the regulation of lytic cell death.

Involvement of Pore Formation and Osmotic Lysis in the Rapid Killing of Gamma Interferon-Pretreated C166 Endothelial Cells by Rickettsia prowazekii

Rickettsia prowazekii, the bacterial cause of epidemic typhus in humans, proliferates mainly within the microvascular endothelial cells. Previous studies have shown that murine macrophage-like RAW264.7 cells are rapidly damaged if they are pretreated with gamma interferon (IFN-γ) and then infected with R. prowazekii. In the present study, the effects of IFN-γ and R. prowazekii on murine C166 endothelial cells were evaluated. In the IFN-γ-pretreated R. prowazekii-infected endothelial cell cultures, evidence of cell damage was observed within several hours after addition of the rickettsiae. Considerable numbers of the cells became permeable to trypan blue dye and ethidium bromide, and substantial amounts of lactate dehydrogenase (LDH) were released from the cells. Such evidence of cellular injury was not observed in the untreated infected cultures or in any of the mock-infected cultures. Polyethylene glycols (PEGs) of different nominal average molecular weights were used to assess the possible involvement of pore formation and osmotic lysis in this cellular injury. PEG 8000 dramatically suppressed LDH release, PEG 4000 partially inhibited it, and PEGs 2000 and 1450 had no effect. Despite its inhibition of LDH release, PEG 8000 did not prevent the staining of the IFN-γ-pretreated infected endothelial cells by ethidium bromide. These findings suggest that the observed cellular injury involves the formation of pores in the endothelial cell membranes, followed by osmotic lysis of the cells.

Ferroptosis, necroptosis, and pyroptosis in the occurrence and development of ovarian cancer

Ovarian cancer (OC) is one of the most common malignancies that causes death in women and is a heterogeneous disease with complex molecular and genetic changes. Because of the relatively high recurrence rate of OC, it is crucial to understand the associated mechanisms of drug resistance and to discover potential target for rational targeted therapy. Cell death is a genetically determined process. Active and orderly cell death is prevalent during the development of living organisms and plays a critical role in regulating life homeostasis. Ferroptosis, a novel type of cell death discovered in recent years, is distinct from apoptosis and necrosis and is mainly caused by the imbalance between the production and degradation of intracellular lipid reactive oxygen species triggered by increased iron content. Necroptosis is a regulated non-cysteine protease–dependent programmed cell necrosis, morphologically exhibiting the same features as necrosis and occurring via a unique mechanism of programmed cell death different from the apoptotic signaling pathway. Pyroptosis is a form of programmed cell death that is characterized by the formation of membrane pores and subsequent cell lysis as well as release of pro-inflammatory cell contents mediated by the abscisin family. Studies have shown that ferroptosis, necroptosis, and pyroptosis are involved in the development and progression of a variety of diseases, including tumors. In this review, we summarized the recent advances in ferroptosis, necroptosis, and pyroptosis in the occurrence, development, and therapeutic potential of OC.

Advances in Crosstalk between Porcine Circoviruses and Host

Porcine circoviruses (PCVs), including PCV1 to PCV4, are non-enveloped DNA viruses with a diameter of about 20 nm, belonging to the genus Circovirus in the family Circoviridae. PCV2 is an important causative agent of porcine circovirus disease or porcine circovirus-associated disease (PCVD/PCVAD), which is highly prevalent in pigs and seriously affects the swine industry globally. Furthermore, PCV2 mainly causes subclinical symptoms and immunosuppression, and PCV3 and PCV4 were detected in healthy pigs, sick pigs, and other animals. Although the pathogenicity of PCV3 and PCV4 in the field is still controversial, the infection rates of PCV3 and PCV4 in pigs are increasing. Moreover, PCV3 and PCV4 rescued from infected clones were pathogenic in vivo. It is worth noting that the interaction between virus and host is crucial to the infection and pathogenicity of the virus. This review discusses the latest research progress on the molecular mechanism of PCVs–host interaction, which may provide a scientific basis for disease prevention and control.