Necrosis, a well-orchestrated form of cell demise: signalling cascades, important mediators and concomitant immune response

Plasticity of Retinal Gap Junctions: Roles in Synaptic Physiology and Disease

Electrical synaptic transmission via gap junctions underlies direct and rapid neuronal communication in the central nervous system. The diversity of functional roles played by electrical synapses is perhaps best exemplified in the vertebrate retina, in which gap junctions are expressed by each of the five major neuronal types. These junctions are highly plastic; they are dynamically regulated by ambient illumination and circadian rhythms acting through light-activated neuromodulators. The networks formed by electrically coupled neurons provide plastic, reconfigurable circuits positioned to play key and diverse roles in the transmission and processing of visual information at every retinal level. Recent work indicates gap junctions also play a role in the progressive cell death and aberrant activity seen in various pathological conditions of the retina. Gap junctions thus form potential targets for novel neuroprotective therapies in the treatment of neurodegenerative retinal diseases such as glaucoma and ischemic retinopathies.

Cardioprotective role of FA against isoproterenol induced cardiac toxicity

The present study was designed to investigate the protective effect of ferulic acid (FA) against isoproterenol (ISO)-induced cardiac toxicity in rats. Isoproterenol challenged in a dose of 85 mg/kg body weight (b.w.) subcutaneously for two consecutive days in the experimental group resulted in acute cardiac toxicity as evidenced by changes in electrocardiogram (ECG) pattern and marked elevation of serum cardiac enzymes viz aspartate aminotransferase (AST), alanine transaminase (ALT), creatinine kinase (CK-MB) and lactate dehydrogenase (LDH) also increases inflammatory cytokines. Moreover, acute toxicity effect was exhibited by disturbance in the antioxidant system as decrease in activities of superoxide dismutase (SOD) and glutathione (GSH) with the rise in activities of malondialdehyde (MDA) and nitric oxide (NO). Pre-treatment with FA at the increasing dose of (10, 20 and 40 mg/kg b.w.) orally for 28 consecutive days followed by isoproterenol injection for 2 days significantly attenuated changes in serum cardiac enzymes. Furthermore, histopathological evaluation confirmed the restoration of cellular architecture in FA pretreated rats. The cardioprotective effect of FA was comparable with standard drug treatment metoprolol. Taken together, FA demonstrated cardioprotective effect against ISO-induced cardiac toxicity by normalization of serum cardiac biomarkers, alleviating oxidative stress and augmenting endogenous antioxidant system.

The reduced level of growth factors in an animal model of depression is accompanied by regulated necrosis in the frontal cortex but not in the hippocampus

In the present study, we asked if the different types of stress alter neuronal plasticity markers distinctively in the frontal cortex (FCx) and in the hippocampus (Hp). To do so, we implemented various stress regimens to analyze changes evoked in these rat brain structures. We utilized several molecular techniques, including western blot, ELISA, quantitative RT-PCR, and various biochemical assays, to examine a range of proteins and subjected rats to behavioral tests to evaluate potential maladaptive alterations. A decrease in the level of growth factors in the FCx was accompanied by changes suggesting damage of this structure in the manner of regulated necrosis, while the Hp appeared to be protected. The observed changes in the brain region-specific alterations in neurotrophin processing may also depend on the period of life, in which an animal experiences stress and the duration of the stressful stimuli. We conclude that chronic stress during pregnancy can result in serious alterations in the functioning of the FCx of the progeny, facilitating the development of depressive behavior later in life. We also suggest that the altered energy metabolism may redirect pro-NGF/p75^NTR/ATF2 signaling in the cortical neurons towards cellular death resembling regulated necrosis, rather than apoptosis.

Induction of Oxidative DNA Damage in Bovine Herpesvirus 1 Infected Bovine Kidney Cells (MDBK Cells) and Human Tumor Cells (A549 Cells and U2OS Cells)

Bovine herpesvirus 1 (BoHV-1) is an important pathogen of cattle that causes lesions in mucosal surfaces, genital tracts and nervous systems. As a novel oncolytic virus, BoHV-1 infects and kills numerous human tumor cells. However, the mechanisms underlying the virus-induced cell damages are not fully understood. In this study, we demonstrated that virus infection of MDBK cells induced high levels of DNA damage, because the percentage of comet tail DNA (tailDNA%) determined by comet assay, a direct indicator of DNA damage, and the levels of 8-hydroxyguanine (8-oxoG) production, an oxidative DNA damage marker, consistently increased following the virus infection. The expression of 8-oxoguanine DNA glycosylase (OGG-1), an enzyme responsible for the excision of 8-oxoG, was significantly decreased due to the virus infection, which corroborated with the finding that BoHV-1 infection stimulated 8-oxoG production. Furthermore, the virus replication in human tumor cells such as in A549 cells and U2OS cells also induced DNA damage. Chemical inhibition of reactive oxidative species (ROS) production by either ROS scavenger N-Acetyl-l-cysteine or NOX inhibitor diphenylene iodonium (DPI) significantly decreased the levels of tailDNA%, suggesting the involvement of ROS in the virus induced DNA lesions. Collectively, these results indicated that BoHV-1 infection of these cells elicits oxidative DNA damages, providing a perspective in understanding the mechanisms by which the virus induces cell death in both native host cells and human tumor cells.

Cell Death Pathways: a Novel Therapeutic Approach for Neuroscientists

In the first part, the following mechanisms involved in different forms of cell death are considered, with a view to identifying potential therapeutic targets: tumour necrosis factor receptors (TNFRs) and their engagement by tumour necrosis factor-alpha (TNF-α); poly [ADP-ribose] polymerase (PARP)-1 cleavage; the apoptosis signalling kinase (ASK)-c-Jun N-terminal kinase (JNK) axis; lysosomal permeability; activation of programmed necrotic cell death; oxidative stress, caspase-3 inhibition and parthanatos; activation of inflammasomes by reactive oxygen species and the development of pyroptosis; oxidative stress, calcium dyshomeostasis and iron in the development of lysosomal-mediated necrosis and lysosomal membrane permeability; and oxidative stress, lipid peroxidation, iron dyshomeostasis and ferroptosis. In the second part, there is a consideration of the role of lethal and sub-lethal activation of these pathways in the pathogenesis and pathophysiology of neurodegenerative and neuroprogressive disorders, with particular reference to the TNF-α-TNFR signalling axis; dysregulation of ASK-1-JNK signalling; prolonged or chronic PARP-1 activation; the role of pyroptosis and chronic inflammasome activation; and the roles of lysosomal permeabilisation, necroptosis and ferroptosis. Finally, it is suggested that, in addition to targeting oxidative stress and inflammatory processes generally, neuropsychiatric disorders may respond to therapeutic targeting of TNF-α, PARP-1, the Nod-like receptor NLRP3 inflammasome and the necrosomal molecular switch receptor-interacting protein kinase-3, since their widespread activation can drive and/or exacerbate peripheral inflammation and neuroinflammation even in the absence of cell death. To this end, the use is proposed of a combination of the tetracycline derivative minocycline and N-acetylcysteine as adjunctive treatment for a range of neuropsychiatric disorders.

An investigation into E-cigarette cytotoxicity in-vitro using a novel 3D differentiated co-culture model of human airways

Currently there is a lack of consensus on the possible adverse health effects of E-cigarettes (ECs). Important factors including cell model employed and exposure method determine the physiological relevance of EC studies. The present study aimed to evaluate EC cytotoxicity using a physiologically relevant in-vitro multicellular model of human airways. Human bronchial epithelial cells (CALU-3) and pulmonary fibroblasts (MRC-5) were co-cultured at air-liquid-interface for 11-14 days post which they were exposed to whole cigarette smoke (WCS) or EC vapour (ECV) at standard ISO-3308 regime for 7 m using a bespoke aerosol delivery system. ECV effects were further investigated at higher exposure times (1 h-6 h). Results showed that while WCS significantly reduced cell viability after 7 m, ECV decreased cell viability only at exposure times higher than 3 h. Furthermore, ECV caused elevated IL-6 and IL-8 production despite reduced cell viability. ECV exposure also produced a marked increase in oxidative stress. Finally, WCS but not ECV exposure induced caspase 3/7 activation, suggesting a caspase independent death of ECV exposed cells. Overall, our results indicate that prolonged ECV exposure (≥3 h) has a significant impact on pro-inflammatory mediators' production, oxidative stress and cell viability but not caspase 3/7 activity.

Melatonin ameliorates the adverse effects of leptin on sperm

This study examined the effects of melatonin on leptin-induced changes in sperm parameters in adult rats. Five groups of Sprague-Dawley rats were treated with either leptin or leptin and melatonin or melatonin for 6 weeks. Leptin was given daily via the intraperitoneal route (60 μg kg⁻¹ body weight) and melatonin was given in drinking water (10 mg kg⁻¹ or 20 mg kg⁻¹ body weight per day). Upon completion, sperm count, sperm morphology, 8-hydroxy-2-deoxyguanosine, Comet assay, TUNEL assay, gene expression profiles of antioxidant enzymes, respiratory chain reaction enzymes, DNA damage, and apoptosis genes were estimated. Data were analyzed using ANOVA. Sperm count was significantly lower whereas the fraction of sperm with abnormal morphology, the level of 8-hydroxy-2-deoxyguanosine, and sperm DNA fragmentation were significantly higher in rats treated with leptin only. Microarray analysis revealed significant upregulation of apoptosis-inducing factor, histone acetyl transferase, respiratory chain reaction enzyme, cell necrosis and DNA repair genes, and downregulation of antioxidant enzyme genes in leptin-treated rats. Real-time polymerase chain reaction showed significant decreases in glutathione peroxidase 1 expression with increases in the expression of apoptosis-inducing factor and histone acetyl transferase in leptin-treated rats. There was no change in the gene expression of caspase-3 (CASP-3). In conclusion, the adverse effects of leptin on sperm can be prevented by concurrent melatonin administration.

Cytosolic Recognition of RNA Drives the Immune Response to Heterologous Erythrocytes

The archetypal T cell-dependent antigen is sheep red blood cells (SRBCs), which have defined much of what we know about humoral immunity. Early studies using solubilized or sonicated SRBCs argued that the intact structure of SRBCs was important for optimal antibody responses. However, the reason for the requirement of intact SRBCs for the response to polyvalent protein antigen remained unknown. Here, we report that the immune response to SRBCs is driven by cytosolic recognition of SRBC RNA through the RIG-I-like receptor (RLR)-mitochondrial anti-viral signaling adaptor (MAVS) pathway. Following the uptake of SRBCs by antigen-presenting cells, the MAVS signaling complex governs the differentiation of both T follicular cells and antibody-producing B cells. Importantly, the involvement of the RLR-MAVS pathway precedes that of endosomal Toll-like receptor pathways, yet both are required for optimal effect.

Triad3a induces the degradation of early necrosome to limit RipK1-dependent cytokine production and necroptosis

Understanding the molecular signaling in programmed cell death is vital to a practical understanding of inflammation and immune cell function. Here we identify a previously unrecognized mechanism that functions to downregulate the necrosome, a central signaling complex involved in inflammation and necroptosis. We show that RipK1 associates with RipK3 in an early necrosome, independent of RipK3 phosphorylation and MLKL-induced necroptotic death. We find that formation of the early necrosome activates K48-ubiquitin-dependent proteasomal degradation of RipK1, Caspase-8, and other necrosomal proteins. Our results reveal that the E3-ubiquitin ligase Triad3a promotes this negative feedback loop independently of typical RipK1 ubiquitin editing enzymes, cIAPs, A20, or CYLD. Finally, we show that Triad3a-dependent necrosomal degradation limits necroptosis and production of inflammatory cytokines. These results reveal a new mechanism of shutting off necrosome signaling and may pave the way to new strategies for therapeutic manipulation of inflammatory responses.

Accidental and Programmed Cell Death in Investigative and Toxicologic Pathology

Cellular development and homeostasis are regulated via programmed cell death (PCD; apoptosis), which is a genetically regulated cellular process. Accidental cell death (ACD; necrosis) can be triggered by chemical, physical, or mechanical stress. Necrosis is the presence of dead tissues or cells in a living organism regardless of the initiating process and can be observed in infectious and non-infectious diseases and toxicities. This article describes tissue-based immunohistotechnical protocols used for assessing PCD and necrosis in formalin-fixed tissues obtained from preclinical species used in investigative and toxicologic pathology. Two commonly employed protocols for the identification of PCD and necrosis are described in this article: immunohistochemistry (IHC) for cleaved caspase 3, and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL). TUNEL has been used to detect DNA fragmentation by labeling the terminal ends of nucleic acids in necrotic and apoptotic cells. © 2018 by John Wiley & Sons, Inc.

Anisomycin prevents OGD-induced necroptosis by regulating the E3 ligase CHIP

Necroptosis is an essential pathophysiological process in cerebral ischemia-related diseases. Therefore, targeting necroptosis may prevent cell death and provide a much-needed therapy. Ansiomycin is an inhibitor of protein synthesis which can also activate c-Jun N-terminal kinases. The present study demonstrated that anisomycin attenuated necroptosis by upregulating CHIP (carboxyl terminus of Hsc70-interacting protein) leading to the reduced levels of receptor-interacting protein kinase 1 (RIPK1) and receptor-interacting protein kinase 3 (RIPK3) proteins in two in vitro models of cerebral ischemia. Further exploration in this research revealed that losing neither the co-chaperone nor the ubiquitin E3 ligase function of CHIP could abolish its ability to reduce necroptosis. Collectively, this study identifies a novel means of preventing necroptosis in two in vitro models of cerebral ischemia injury through activating the expression of CHIP, and it may provide a potential target for the further study of the disease.

Dissecting the molecular pathophysiology of drug-induced liver injury

Drug-induced liver injury (DILI) has become a major topic in the field of Hepatology and Gastroenterology. DILI can be clinically divided into three phenotypes: hepatocytic, cholestatic and mixed. Although the clinical manifestations of DILI are variable and the pathogenesis complicated, recent insights using improved preclinical models, have allowed a better understanding of the mechanisms that trigger liver damage. In this review, we will discuss the pathophysiological mechanisms underlying DILI. The toxicity of the drug eventually induces hepatocellular damage through multiple molecular pathways, including direct hepatic toxicity and innate and adaptive immune responses. Drugs or their metabolites, such as the common analgesic, acetaminophen, can cause direct hepatic toxicity through accumulation of reactive oxygen species and mitochondrial dysfunction. The innate and adaptive immune responses play also a very important role in the occurrence of idiosyncratic DILI. Furthermore, we examine common forms of hepatocyte death and their association with the activation of specific signaling pathways.

Innate Immunity in the Persistent Inflammation, Immunosuppression, and Catabolism Syndrome and Its Implications for Therapy

Clinical and technological advances promoting early hemorrhage control and physiologic resuscitation as well as early diagnosis and optimal treatment of sepsis have significantly decreased in-hospital mortality for many critically ill patient populations. However, a substantial proportion of severe trauma and sepsis survivors will develop protracted organ dysfunction termed chronic critical illness (CCI), defined as ≥14 days requiring intensive care unit (ICU) resources with ongoing organ dysfunction. A subset of CCI patients will develop the persistent inflammation, immunosuppression, and catabolism syndrome (PICS), and these individuals are predisposed to a poor quality of life and indolent death. We propose that CCI and PICS after trauma or sepsis are the result of an inappropriate bone marrow response characterized by the generation of dysfunctional myeloid populations at the expense of lympho- and erythropoiesis. This review describes similarities among CCI/PICS phenotypes in sepsis, cancer, and aging and reviews the role of aberrant myelopoiesis in the pathophysiology of CCI and PICS. In addition, we characterize pathogen recognition, the interface between innate and adaptive immune systems, and therapeutic approaches including immune modulators, gut microbiota support, and nutritional and exercise therapy. Finally, we discuss the future of diagnostic and prognostic approaches guided by machine and deep-learning models trained and validated on big data to identify patients for whom these approaches will yield the greatest benefits. A deeper understanding of the pathophysiology of CCI and PICS and continued investigation into novel therapies harbor the potential to improve the current dismal long-term outcomes for critically ill post-injury and post-infection patients.

Novel drug discovery strategies for atherosclerosis that target necrosis and necroptosis

INTRODUCTION

Formation and enlargement of a necrotic core play a pivotal role in atherogenesis. Since the discovery of necroptosis, which is a regulated form of necrosis, prevention of necrotic cell death has become an attractive therapeutic goal to reduce plaque formation. Areas covered: This review highlights the triggers and consequences of (unregulated) necrosis and necroptosis in atherosclerosis. The authors discuss different pharmacological strategies to inhibit necrotic cell death in advanced atherosclerotic plaques. Expert opinion: Addition of a necrosis or necroptosis inhibitor to standard statin therapy could be a promising strategy for primary prevention of cardiovascular disease. However, a necrosis inhibitor cannot block all necrosis stimuli in atherosclerotic plaques. A necroptosis inhibitor could be more effective, because necroptosis is mediated by specific proteins, termed receptor-interacting serine/threonine-protein kinases (RIPK) and mixed lineage kinase domain-like pseudokinase (MLKL). Currently, only RIPK1 inhibitors have been successfully used in atherosclerotic mouse models to inhibit necroptosis. However, because RIPK1 is involved in both necroptosis and apoptosis, and also RIPK1-independent necroptosis can occur, we feel that targeting RIPK3 and MLKL could be a more attractive therapeutic approach to inhibit necroptosis. Therefore, future challenges will consist of developing RIPK3 and MLKL inhibitors applicable in both preclinical and clinical settings.

Cyanidin-3-o-glucoside directly binds to ERα36 and inhibits EGFR-positive triple-negative breast cancer

Anthocyanins have been shown to inhibit the growth and metastatic potential of breast cancer (BC) cells. However, the effects of individual anthocyanins on triple-negative breast cancer (TNBC) have not yet been studied. In this study, we found that cyanidin-3-o-glucoside (Cy-3-glu) preferentially promotes the apoptosis of TNBC cells, which co-express the estrogen receptor alpha 36 (ERα36) and the epidermal growth factor receptor (EGFR). We demonstrated that Cy-3-glu directly binds to the ligand-binding domain (LBD) of ERα36, inhibits EGFR/AKT signaling, and promotes EGFR degradation. We also confirmed the therapeutic efficacy of Cy-3-glu on TNBC in the xenograft mouse model. Our data indicates that Cy-3-glu could be a novel preventive/therapeutic agent against the TNBC co-expressed ERα36/EGFR.

A rare variant in MLKL confers susceptibility to ApoE ɛ4-negative Alzheimer's disease in Hong Kong Chinese population

Alzheimer's disease (AD) is the most common neurodegenerative disorders in the elderly. To identify rare genetic factors other than apolipoprotein E ɛ4 allele (ApoE ɛ4) contributing to the pathogenesis of late-onset AD (LOAD), we conducted a whole-exome analysis of 246 ApoE ɛ4-negative LOAD cases and 172 matched controls in Hong Kong Chinese population. LOAD patients showed a significantly higher burden of rare loss-of-function variants in genes related to immune function than healthy controls. Among the genes involved in immune function, we identified a rare stop-gain variant (p.Q48X) in mixed lineage kinase domain like pseudokinase (MLKL) gene present exclusively in 6 LOAD cases. MLKL is expressed in neurons, and the its expression levels in the p.Q48X carriers were significantly lower than that in age-matched wild-type controls. The ratio of Aβ42 to Aβ40 significantly increased in MLKL knockdown cells compared to scramble controls. MLKL loss-of-function mutation might contribute to late-onset ApoE ɛ4-negative AD in the Hong Kong Chinese population.

The study of the calpain and caspase-1 expression in ultrastructural dynamics of Ehrlich ascites carcinoma necrosis

An expression of calpain and caspase-1 as well as the concomitant ultrastructural alterations were investigated during necrosis of the mouse Ehrlich ascites carcinoma. The calpain expression was registered at 0 h and 1 h although caspase-1 did not induce any signals during these time periods. The rise of the cytoplasmic lytic zones contacted by calpain antibodies was identified as a morphologic event corresponding to the expression of calpain. Lytic zone's distribution followed by the appearance of the calpain/caspase-1 clusters assigned for lysis of the Golgi vesicles and ER. Also, the microapocrine secretion of the vesicles containing the calpain/caspase-1 clusters was detected. Further, the lysis of the plasma membrane occurred due to progression of intracellular lysis. Rupture of the plasma membrane resulted in the termination of secretion and dissemination of cell contents. The nuclei still had their normal shape. Nuclear lysis continued to rise with intranuclear lytic zones, of which the progression was accompanied with the presence of calpain/caspase-1 clusters. The data contribute to the concept of the initial role of calpain for tumor cell destruction, provide first evidence of the calpain/caspase-1 pathway in tumor cells, and highlight microapocrine secretion as a possible tumor cell death signalling mechanism.

Listeria monocytogenes: The Impact of Cell Death on Infection and Immunity

Listeria monocytogenes has evolved exquisite mechanisms for invading host cells and spreading from cell-to-cell to ensure maintenance of its intracellular lifecycle. As such, it is not surprising that loss of the intracellular replication niche through induction of host cell death has significant implications on the development of disease and the subsequent immune response. Although L. monocytogenes can activate multiple pathways of host cell death, including necrosis, apoptosis, and pyroptosis, like most intracellular pathogens L. monocytogenes has evolved a series of adaptations that minimize host cell death to promote its virulence. Understanding how L. monocytogenes modulates cell death during infection could lead to novel therapeutic approaches. In addition, as L. monocytogenes is currently being developed as a tumor immunotherapy platform, understanding how cell death pathways influence the priming and quality of cell-mediated immunity is critical. This review will focus on the mechanisms by which L. monocytogenes modulates cell death, as well as the implications of cell death on acute infection and the generation of adaptive immunity.

Antitumor activity of HPA3P through RIPK3-dependent regulated necrotic cell death in colon cancer

The antimicrobial peptide HPA3 shows anticancer activity in gastric cancer and leukaemia. However, how HPA3 exerts its anticancer activity, as well as whether it also exhibits activity in other cancers, remains unknown. Therefore, the aim of this study was to evaluate the anticancer activity of HPA3 and its analogues in colon cancer and to elucidate the mechanisms responsible for this activity. HPA3P decreased cell viability, whereas HPA3 and HPA3P2 did not decrease cell viability in colon cancer cells compared with control cells. This reduction in cell viability occurred through necrosis, a conclusion supported by our observation of the release of cellular contents, our intracellular PI staining results, and our observation of the release of HMGB1. Moreover, RIPK3 inhibition blocks the reduction of cell viability by HPA3P. Consistent with this finding, we found that knocking down RIPK3 and MLKL, key necroptosis proteins, attenuates the reductions in cell viability induced by HPA3P. Furthermore, HPA3P can improve the anticancer activity of chemotherapeutic agents and exhibits anticancer activity in other cancer cells. These results suggest that HPA3P may have potential as an anticancer agent in the treatment of colon cancer.

IMMUNEPOTENT CRP induces cell cycle arrest and caspase-independent regulated cell death in HeLa cells through reactive oxygen species production

BACKGROUND

Regulated cell death (RCD) is a mechanism by which the cell activates its own machinery to self-destruct. RCD is important for the maintenance of tissue homeostasis and its deregulation is involved in diseases such as cervical cancer. IMMUNEPOTENT CRP (I-CRP) is a dialyzable bovine leukocyte extract that contains transfer factors and acts as an immunomodulator, and can be cytotoxic to cancer cell lines and reduce tumor burden in vivo. Although I-CRP has shown to improve or modulate immune response in inflammation, infectious diseases and cancer, its widespread use has been limited by the absence of conclusive data on the molecular mechanism of its action.

METHODS

In this study we analyzed the mechanism by which I-CRP induces cytotoxicity in HeLa cells. We assessed cell viability, cell death, cell cycle, nuclear morphology and DNA integrity, caspase dependence and activity, mitochondrial membrane potential, and reactive oxygen species production.

RESULTS

I-CRP diminishes cell viability in HeLa cells through a RCD pathway and induces cell cycle arrest in the G2/M phase. We show that the I-CRP induces caspase activation but cell death induction is independent of caspases, as observed by the use of a pan-caspase inhibitor, which blocked caspase activity but not cell death. Moreover, we show that I-CRP induces DNA alterations, loss of mitochondrial membrane potential, and production of reactive-oxygen species. Finally, pretreatment with N-acetyl-L-cysteine (NAC), a ROS scavenger, prevented both ROS generation and cell death induced by I-CRP.

CONCLUSIONS

Our data indicate that I-CRP treatment induced cell cycle arrest in G2/M phase, mitochondrial damage, and ROS-mediated caspase-independent cell death in HeLa cells. This work opens the way to the elucidation of a more detailed cell death pathway that could potentially work in conjunction with caspase-dependent cell death induced by classical chemotherapies.

Exposure of vital cells to necrotic cell lysates induce the IRE1α branch of the unfolded protein response and cell proliferation

Necrosis is a form of cell death that is detrimental to the affected tissue because the cell ruptures and releases its content (reactive oxygen species among others) into the extracellular space. Clusterin (CLU), a cytoprotective extracellular chaperone has been shown to be upregulated in the face of necrosis. We here show that in addition to CLU upregulation, necrotic cell lysates induce JNK/SAPK signaling, the IRE1α branch of the unfolded protein response (UPR), the MAPK/ERK1/2, and the mTOR signaling pathways and results in an enhanced proliferation of the vital surrounding cells. We name this novel response mechanism: Necrosis-induced Proliferation (NiP).

Necroptosis promotes autophagy-dependent upregulation of DAMP and results in immunosurveillance

Programmed necrosis, necroptosis, is considered to be a highly immunogenic activity, often mediated via the release of damage-associated molecular patterns (DAMPs). Interestingly, enhanced macroautophagic/autophagic activity is often found to be accompanied by necroptosis. However, the possible role of autophagy in the immunogenicity of necroptotic death remains largely obscure. In this study, we investigated the possible mechanistic correlation between phytochemical shikonin-induced autophagy and the shikonin-induced necroptosis for tumor immunogenicity. We show that shikonin can instigate RIPK1 (receptor [TNFRSF]-interacting serine-threonine kinase 1)- and RIPK3 (receptor-interacting serine-threonine kinase 3)-dependent necroptosis that is accompanied by enhanced autophagy. Shikonin-induced autophagy can directly contribute to DAMP upregulation. Counterintuitively, among the released and ectoDAMPs, only the latter were shown to be able to activate the cocultured dendritic cells (DCs). Interruption of autophagic flux via chloroquine further upregulated ectoDAMP activity and resultant DC activation. For potential clinical application, DC vaccine preparations treated with tumor cells that were already pretreated with chloroquine and shikonin further enhanced the antimetastatic activity of 4T1 tumors and reduced the effective dosage of doxorubicin. The enhanced immunogenicity and vaccine efficacy obtained via shikonin and chloroquine cotreatment of tumor cells may thus constitute a compelling strategy for developing cancer vaccines via the use of a combinational drug treatment.

Senescence and cell death in chronic liver injury: roles and mechanisms underlying hepatocarcinogenesis

Chronic liver injury (CLI) is a complex pathological process typically characterized by progressive destruction and regeneration of liver parenchymal cells due to diverse risk factors such as alcohol abuse, drug toxicity, viral infection, and genetic metabolic disorders. When the damage to hepatocytes is mild, the liver can regenerate itself and restore to the normal state; when the damage is irreparable, hepatocytes would undergo senescence or various forms of death including apoptosis, necrosis and necroptosis. These pathological changes not only promote the progression of the existing hepatopathies via various underlying mechanisms but are closely associated with hepatocarcinogenesis. In this review, we discuss the pathological changes that hepatocytes undergo during CLI, and their roles and mechanisms in the progression of hepatopathies and hepatocarcinogenesis. We also give a brief introduction about some animal models currently used for the research of CLI and progress in the research of CLI.

Digital-PCR for gene expression: impact from inherent tissue RNA degradation

Subtle molecular differences indicate the heterogeneity present in a number of disease settings. Digital-PCR (dPCR) platforms achieve the necessary levels of sensitivity and accuracy over standard quantitative RT-PCR (qPCR) that promote their use for such situations, detecting low abundance transcript and subtle changes from gene expression. An underlying requisite is good quality RNA, principally dictated by appropriate tissue handling and RNA extraction. Here we consider the application of dPCR to measures of gene expression in pathological tissues with inherent necrosis, focusing on rheumatoid subcutaneous nodules. Variable RNA fragmentation is a feature of RNA from such tissues. Increased presence of transcript fragmentation is reflected in a proportionate decrease in Agilent DV₂₀₀ metric and downstream, a reduction in endogenous control genes' expression, measured by RT-dPCR. We show that normalisation of target gene expression to that for endogenous control genes sufficiently corrects for the variable level of fragmented RNA. Recovery of target gene values was achieved in samples comprising as much as 50 percent fragmented RNA, indicating the suitability and appropriate limitation of such data treatment when applied to samples obtained from inherently necrotic tissues.

Development and Validation of an Individualized Immune Prognostic Signature in Early-Stage Nonsquamous Non-Small Cell Lung Cancer

Importance

The prevalence of early-stage non-small cell lung cancer (NSCLC) is expected to increase with recent implementation of annual screening programs. Reliable prognostic biomarkers are needed to identify patients at a high risk for recurrence to guide adjuvant therapy.

Objective

To develop a robust, individualized immune signature that can estimate prognosis in patients with early-stage nonsquamous NSCLC.

Design, Setting, and Participants

This retrospective study analyzed the gene expression profiles of frozen tumor tissue samples from 19 public NSCLC cohorts, including 18 microarray data sets and 1 RNA-Seq data set for The Cancer Genome Atlas (TCGA) lung adenocarcinoma cohort. Only patients with nonsquamous NSCLC with clinical annotation were included. Samples were from 2414 patients with nonsquamous NSCLC, divided into a meta-training cohort (729 patients), meta-testing cohort (716 patients), and 3 independent validation cohorts (439, 323, and 207 patients). All patients underwent surgery with a negative surgical margin, received no adjuvant or neoadjuvant therapy, and had publicly available gene expression data and survival information. Data were collected from July 22 through September 8, 2016.

Main Outcomes and Measures

Overall survival.

Results

Of 2414 patients (1205 men [50%], 1111 women [46%], and 98 of unknown sex [4%]; median age [range], 64 [15-90] years), a prognostic immune signature of 25 gene pairs consisting of 40 unique genes was constructed using the meta-training data set. In the meta-testing and validation cohorts, the immune signature significantly stratified patients into high- vs low-risk groups in terms of overall survival across and within subpopulations with stage I, IA, IB, or II disease and remained as an independent prognostic factor in multivariate analyses (hazard ratio range, 1.72 [95% CI, 1.26-2.33; P < .001] to 2.36 [95% CI, 1.47-3.79; P < .001]) after adjusting for clinical and pathologic factors. Several biological processes, including chemotaxis, were enriched among genes in the immune signature. The percentage of neutrophil infiltration (5.6% vs 1.8%) and necrosis (4.6% vs 1.5%) was significantly higher in the high-risk immune group compared with the low-risk groups in TCGA data set (P < .003). The immune signature achieved a higher accuracy (mean concordance index [C-index], 0.64) than 2 commercialized multigene signatures (mean C-index, 0.53 and 0.61) for estimation of survival in comparable validation cohorts. When integrated with clinical characteristics such as age and stage, the composite clinical and immune signature showed improved prognostic accuracy in all validation data sets relative to molecular signatures alone (mean C-index, 0.70 vs 0.63) and another commercialized clinical-molecular signature (mean C-index, 0.68 vs 0.65).

Conclusions and Relevance

The proposed clinical-immune signature is a promising biomarker for estimating overall survival in nonsquamous NSCLC, including early-stage disease. Prospective studies are needed to test the clinical utility of the biomarker in individualized management of nonsquamous NSCLC.

A novel protein derived from lamprey supraneural body tissue with efficient cytocidal actions against tumor cells

BACKGROUND

In previous research, we found that cell secretion from the adult lamprey supraneural body tissues possesses cytocidal activity against tumor cells, but the protein with cytocidal activity was unidentified.

METHODS

A novel lamprey immune protein (LIP) as defense molecule was first purified and identified in jawless vertebrates (cyclostomes) using hydroxyapatite column and Q Sepharose Fast Flow column. After LIP stimulation, morphological changes of tumor cells were analysed and measured whether in vivo or in vitro.

RESULTS

LIP induces remarkable morphological changes in tumor cells, including cell blebbing, cytoskeletal alterations, mitochondrial fragmentation and endoplasmic reticulum vacuolation, and most of the cytoplasmic and organelle proteins are released following treatment with LIP. LIP evokes an elevation of intracellular calcium and inflammatory molecule levels. Our analysis of the cytotoxic mechanism suggests that LIP can upregulate the expression of caspase 1, RIPK1, RIP3 to trigger pyroptosis and necroptosis. To examine the effect of LIP in vivo, tumor xenograft experiments were performed, and the results indicated that LIP inhibits tumor growth without damage to mice. In addition, the cytotoxic action of LIP depended on the phosphatidylserine (PS) content of the cell membrane.

CONCLUSIONS

These observations suggest that LIP plays a crucial role in tumor cell survival and growth. The findings will also help to elucidate the mechanisms of host defense in lamprey.

Epithelial Cell Inflammasomes in Intestinal Immunity and Inflammation

Pattern recognition receptors (PRR), such as NOD-like receptors (NLRs), sense conserved microbial signatures, and host danger signals leading to the coordination of appropriate immune responses. Upon activation, a subset of NLR initiate the assembly of a multimeric protein complex known as the inflammasome, which processes pro-inflammatory cytokines and mediates a specialized form of cell death known as pyroptosis. The identification of inflammasome-associated genes as inflammatory bowel disease susceptibility genes implicates a role for the inflammasome in intestinal inflammation. Despite the fact that the functional importance of inflammasomes within immune cells has been well established, the contribution of inflammasome expression in non-hematopoietic cells remains comparatively understudied. Given that intestinal epithelial cells (IEC) act as a barrier between the host and the intestinal microbiota, inflammasome expression by these cells is likely important for intestinal immune homeostasis. Accumulating evidence suggests that the inflammasome plays a key role in shaping epithelial responses at the host-lumen interface with many inflammasome components highly expressed by IEC. Recent studies have exposed functional roles of IEC inflammasomes in mucosal immune defense, inflammation, and tumorigenesis. In this review, we present the main features of the predominant inflammasomes and their effector mechanisms contributing to intestinal homeostasis and inflammation. We also discuss existing controversies in the field and open questions related to their implications in disease. A comprehensive understanding of the molecular basis of intestinal inflammasome signaling could hold therapeutic potential for clinical translation.

No patient left behind: The promise of immune priming with epigenetic agents

Checkpoint inhibitors, monoclonal antibodies that inhibit PD-1 or CTLA-4, have revolutionized the treatment of multiple cancers. Despite the enthusiasm for the clinical successes of checkpoint inhibitors, and immunotherapy, in general, only a minority of patients with specific tumor types actually benefit from treatment. Emerging evidence implicates epigenetic alterations as a mechanism of clinical resistance to immunotherapy. This review presents evidence for that association, summarizes the epi-based mechanisms by which tumors evade immunogenic cell death, discusses epigenetic modulation as a component of an integrated strategy to boost anticancer T cell effector function in relation to a tumor immunosuppression cycle and, finally, makes the case that the success of this no-patient-left-behind strategy critically depends on the toxicity profile of the epigenetic agent(s).

Combination treatment of ergosterol followed by amphotericin B induces necrotic cell death in human hepatocellular carcinoma cells

The incidence of liver cancer, the second leading cause of cancer-related deaths has increased over the past few decades. Although recent treatments such as sorafenib are promising in patients with advanced hepatocellular carcinoma (HCC), the response rates remain poor thereby warranting the identification of novel therapeutic agents against liver cancer. Herein, we investigated the anti-cancer effect of ergosterol (a secondary metabolite in medicinal fungus) pretreatment followed by amphotericin B (AmB) treatment on liver cancer cell lines. We demonstrated that pretreatment with a nontoxic dose of ergosterol synergistically enhanced the cytotoxicity of AmB in both Hep3B and HepJ5 cells. The combination treatment-mediated suppression of cancer cell viability occurred through necrosis characterized by disrupted cell membrane and significant amounts of debris accumulation. In addition, we also observed a concomitant increase in reactive oxygen species (ROS) and LC3-II levels in HepJ5 cells treated with ergosterol and AmB. Our results suggest that ergosterol-AmB combination treatment effectively induced necrotic cell death in cancer cells, and deserves further evaluation for development as an anti-cancer agent.

Relationship between necrotic patterns in glioblastoma and patient survival: fractal dimension and lacunarity analyses using magnetic resonance imaging

Necrosis is a hallmark feature of glioblastoma (GBM). This study investigated the prognostic role of necrotic patterns in GBM using fractal dimension (FD) and lacunarity analyses of magnetic resonance imaging (MRI) data and evaluated the role of lacunarity in the biological processes leading to necrosis. We retrospectively reviewed clinical and MRI data of 95 patients with GBM. FD and lacunarity of the necrosis on MRI were calculated by fractal analysis and subjected to survival analysis. We also performed gene ontology analysis in 32 patients with available RNA-seq data. Univariate analysis revealed that FD < 1.56 and lacunarity > 0.46 significantly correlated with poor progression-free survival (p = 0.006 and p = 0.012, respectively) and overall survival (p = 0.008 and p = 0.005, respectively). Multivariate analysis revealed that both parameters were independent factors for unfavorable progression-free survival (p = 0.001 and p = 0.015, respectively) and overall survival (p = 0.002 and p = 0.007, respectively). Gene ontology analysis revealed that genes positively correlated with lacunarity were involved in the suppression of apoptosis and necrosis-associated biological processes. We demonstrate that the fractal parameters of necrosis in GBM can predict patient survival and are associated with the biological processes of tumor necrosis.

Leaf and Root Extracts from Campomanesia adamantium (Myrtaceae) Promote Apoptotic Death of Leukemic Cells via Activation of Intracellular Calcium and Caspase-3

Phytochemical studies are seeking new alternatives to prevent or treat cancer, including different types of leukemias. Campomanesia adamantium, commonly known as guavira or guabiroba, exhibits pharmacological properties including antioxidant, antimicrobial, and antiproliferative activities. Considering the anticancer potential of this plant species, the aim of this study was to evaluate the antileukemic activity and the chemical composition of aqueous extracts from the leaves (AECL) and roots (AECR) of C. adamantium and their possible mechanisms of action. The extracts were analyzed by LC-DAD-MS, and their constituents were identified based on the UV, MS, and MS/MS data. The AECL and AECR showed different chemical compositions, which were identified as main compounds glycosylated flavonols from AECL and ellagic acid and their derivatives from AECR. The cytotoxicity promoted by these extracts were evaluated using human peripheral blood mononuclear cells and Jurkat leukemic cell line. The cell death profile was evaluated using annexin-V-FITC and propidium iodide labeling. Changes in the mitochondrial membrane potential, the activity of caspases, and intracellular calcium levels were assessed. The cell cycle profile was evaluated using propidium iodide. Both extracts caused concentration-dependent cytotoxicity only in Jurkat cells via late apoptosis. This activity was associated with loss of the mitochondrial membrane potential, activation of caspases-9 and -3, changes in intracellular calcium levels, and cell cycle arrest in S-phase. Therefore, the antileukemic activity of the AECL and AECR is mediated by mitochondrial dysfunction and intracellular messengers, which activate the intrinsic apoptotic pathway. Hence, aqueous extracts of the leaves and roots of C. adamantium show therapeutic potential for use in the prevention and treatment of diseases associated the proliferation of tumor cell.

Sorafenib tosylate inhibits directly necrosome complex formation and protects in mouse models of inflammation and tissue injury

Necroptosis contributes to the pathophysiology of several inflammatory, infectious and degenerative disorders. TNF-induced necroptosis involves activation of the receptor-interacting protein kinases 1 and 3 (RIPK1/3) in a necrosome complex, eventually leading to the phosphorylation and relocation of mixed lineage kinase domain like protein (MLKL). Using a high-content screening of small compounds and FDA-approved drug libraries, we identified the anti-cancer drug Sorafenib tosylate as a potent inhibitor of TNF-dependent necroptosis. Interestingly, Sorafenib has a dual activity spectrum depending on its concentration. In murine and human cell lines it induces cell death, while at lower concentrations it inhibits necroptosis, without affecting NF-κB activation. Pull down experiments with biotinylated Sorafenib show that it binds independently RIPK1, RIPK3 and MLKL. Moreover, it inhibits RIPK1 and RIPK3 kinase activity. In vivo Sorafenib protects against TNF-induced systemic inflammatory response syndrome (SIRS) and renal ischemia–reperfusion injury (IRI). Altogether, we show that Sorafenib can, next to the reported Braf/Mek/Erk and VEGFR pathways, also target the necroptotic pathway and that it can protect in an acute inflammatory RIPK1/3-mediated pathology.

Investigating fibroblast cells under "safe" and "injurious" blue-light exposure by holographic microscopy

The exposure to visible light has been shown to exert various biological effects, such as erythema and retinal degeneration. However, the phototoxicity mechanisms in living cells are still not well understood. Here we report a study on the temporal evolution of cell morphology and volume during blue light exposure. Blue laser irradiation is switched during the operation of a digital holography (DH) microscope between what we call here "safe" and "injurious" exposure (SE & IE). The results reveal a behaviour that is typical of necrotic cells, with early swelling and successive leakage of the intracellular liquids when the laser is set in the "injurious" operation. In the phototoxicity investigation reported here the light dose modulation is performed through the very same laser light source adopted for monitoring the cell's behaviour by digital holographic microscope. We believe the approach may open the route to a deep investigation of light-cell interactions, with information about death pathways and threshold conditions between healthy and damaged cells when subjected to light-exposure. 3D Morphology and quantitative phase information from late stage of necrosis cell death.

15-Deoxy-Δ12,14-prostaglandin J2 alleviates hepatic ischemia-reperfusion injury in mice via inducing antioxidant response and inhibiting apoptosis and autophagy

Hepatic ischemia-reperfusion (I/R) injury is a common clinical impairment that occurs in many circumstances and leads to poor prognosis. Both apoptosis and autophagy have been shown to contribute to cell death in hepatic I/R injury. 15-Deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ2) is one of the best-studied anti-inflammatory prostaglandins, which has been verified to exert anti-inflammatory and cell-protective functions in various types of cells and animal models. In this study we explored the effects of 15d-PGJ2 on both apoptosis and autophagy in mouse hepatic I/R injury and its possible mechanisms. A model of segmental (70%) hepatic warm ischemia was established in Balb/c mice, and the pathological changes in serum and liver tissues were detected at 6, 12, and 24 h post-surgery, while 15d-PGJ2 (2.5, 7.5, 15 μg, iv) was administered 30 min prior the surgery. Pretreatment with 15d-PGJ2 (7.5, 15 μg) significantly ameliorated I/R-induced hepatic injury evidenced by dose-dependent reduction of serum ALT and AST levels as well as alleviated tissue damages. 15d-PGJ2 pretreatment significantly decreased the serum TNF-α and IL-1β levels and the hepatic expression of F4/80, a major biomarker of macrophages. 15d-PGJ2 pretreatment upregulated the Bcl-2/Bax ratio, thus reducing the number of apoptotic cells in the livers. 15d-PGJ2 pretreatment considerably suppressed the expression of Beclin-1 and LC3, thus decreasing the number of autophagosomes in the livers. Furthermore, 15d-PGJ2 pretreatment activated Nrf2 and inhibited a ROS/HIF1α/BNIP3 pathway in the livers. Pretreatment with the PPARγ receptor blocker GW9662 (2 μg, ip) partly reversed the protective effects of 15d-PGJ2 on hepatic I/R injury. In conclusion, our results confirm the protective effect of 15d-PGJ2 on hepatic I/R injury, an effect that may rely on a reduction in the activation of Kupffer cells and on activation of the Nrf2 pathway, which lead to inhibition of ROS generation, apoptosis, and autophagy.

The human cancer cell active toxin Cry41Aa from Bacillus thuringiensis acts like its insecticidal counterparts

Understanding how certain protein toxins from the normally insecticidal bacterium Bacillus thuringiensis (Bt) target human cell lines has implications for both the risk assessment of products containing these toxins and potentially for cancer therapy. This understanding requires knowledge of whether the human cell active toxins work by the same mechanism as their insecticidal counterparts or by alternative ones. The Bt Cry41Aa (also known as Parasporin3) toxin is structurally related to the toxins synthesised by commercially produced transgenic insect-resistant plants, with the notable exception of an additional C-terminal β-trefoil ricin domain. To better understand its mechanism of action, we developed an efficient expression system for the toxin and created mutations in regions potentially involved in the toxic mechanism. Deletion of the ricin domain did not significantly affect the activity of the toxin against the human HepG2 cell line, suggesting that this region was not responsible for the mammalian specificity of Cry41Aa. Various biochemical assays suggested that unlike some other human cell active toxins from Bt Cry41Aa did not induce apoptosis, but that its mechanism of action was consistent with that of a pore-forming toxin. The toxin induced a rapid and significant decrease in metabolic activity. Adenosine triphosphate depletion, cell swelling and membrane damage were also observed. An exposed loop region believed to be involved in receptor binding of insecticidal Cry toxins was shown to be important for the activity of Cry41Aa against HepG2 cells.

Antiviral activity of PHA767491 against human herpes simplex virus in vitro and in vivo

BACKGROUND

Herpes simplex virus (HSV) is a common human pathogen that causes a variety of diseases, including oral-labial, genital lesions and life-threatening encephalitis. The antiviral nucleoside analogues such as acyclovir are currently used in anti-HSV therapies; however, clinical overuse of these drugs has led to the emergence of drug-resistant viral strains. Hence, there is an urgent need to develop new anti-HSV agents.

METHODS

To identify novel anti-HSV-1 compounds, we screened the LOPAC small scale library of 1280 bioactive compounds to identify inhibitors of HSV-1-induced necroptosis. Further experiments including western blot analysis, Q-PCR analysis and immunohistochemistry were performed to explore the antiviral mechanism of the compounds.

RESULTS

Here, we identified PHA767491 as a new inhibitor of HSV. PHA767491 potently blocked the proliferation of HSV in cells, as well as HSV induced cell death. Further, we found that PHA767491 strongly inhibited HSV infection post viral entry. Moreover, PHA767491 reduced the expression of viral genes required for DNA synthesis including UL30/42 DNA polymerase and UL5/8/52 helicase-primase complex. The essential immediate early (IE) genes such as ICP4 and ICP27 are critical for the expression of the early and late genes. Of note, PHA767491 inhibited the expression of all IE genes of both HSV-1 and HSV-2. Importantly, PHA767491 reduced viral titers in the tissues from the mice infected with HSV-1. Consistently, immunohistochemistry analysis showed that PHA767491 dramatically attenuated expression of viral protein gB in the livers.

CONCLUSIONS

Taken together, PHA767491 has potent anti-HSV activity by inhibiting viral replication both in vitro and in mouse model. Thus, PHA767491 could be a promising agent for the development of new anti-HSV therapy.

MutY DNA Glycosylase Protects Cells From Tumor Necrosis Factor Alpha-Induced Necroptosis

Numerous studies have implied that mutY DNA glycosylase (MYH) is involved in the repair of post-replicative mispairs and plays a critical role in the base excision repair pathway. Recent in vitro studies have shown that MYH interacts with tumor necrosis factor receptor type 1-associated death domain (TRADD), a key effector protein of tumor necrosis factor receptor-1 (TNFR1) signaling. The association between MYH and TRADD is reversed during tumor necrosis factor alpha (TNF-α)- and camptothecin (CPT)-induced apoptosis, and enhanced during TNF-α-induced survival. After investigating the role of MYH interacts with various proteins following TNF-α stimulation, here, we focus on MYH and TRADD interaction functions in necroptosis and its effects to related proteins. We report that the level of the MYH and TRADD complex was also reduced during necroptosis induced by TNF-α and zVAD-fmk. In particular, we also found that MYH is a biologically important necrosis suppressor. Under combined TNF-α and zVAD-fmk treatment, MYH-deficient cells were induced to enter the necroptosis pathway but primary mouse embryonic fibroblasts (MEFs) were not. Necroptosis in the absence of MYH proceeds via the inactivation of caspase-8, followed by an increase in the formation of the kinase receptor- interacting protein 1 (RIP1)-RIP3 complex. Our results suggested that MYH, which interacts with TRADD, inhibits TNF-α necroptotic signaling. Therefore, MYH inactivation is essential for necroptosis via the downregulation of caspase-8. J. Cell. Biochem. 118: 1827-1838, 2017. © 2017 Wiley Periodicals, Inc.

Apoptosis-inducing ability of silver(I) cyanide-phosphines useful for anti-cancer studies

Metal-based drugs have shown early promise as anticancer agents suggesting the potential application of silver(I) complexes as apoptosis-inducing agents. The ability of a silver(I) cyanide containing phosphine complex to induce cell death was evaluated in both a malignant (SNO esophageal cancer) and non-malignant (HDF-a skin and HEK293 kidney) cell lines. A dose-dependent decrease in cell viability was observed in the SNO cells. Light microscopy revealed morphological features indicative of apoptotic cell death. The mode of cell death was confirmed as apoptosis by phosphatidylserine externalization, DNA fragmentation and nuclear condensation. Furthermore, both the non-malignant cell lines showed morphological features indicative of apoptosis when exposed to complex 1. We propose the use of this silver(I) cyanide phosphine complex as an highly effective positive apoptosis control for use in anticancer studies of phosphine complexes.

Listeria monocytogenes-Induced Cell Death Inhibits the Generation of Cell-Mediated Immunity

The influence of cell death on adaptive immunity has been studied for decades. Despite these efforts, the intricacies of how various cell death pathways shape immune responses in the context of infection remain unclear, particularly with regard to more recently discovered pathways such as pyroptosis. The emergence of Listeria monocytogenes as a promising immunotherapeutic platform demands a thorough understanding of how cell death induced in the context of infection influences the generation of CD8⁺ T-cell-mediated immune responses. To begin to address this question, we designed strains of L. monocytogenes that robustly activate necrosis, apoptosis, or pyroptosis. We hypothesized that proinflammatory cell death such as necrosis would be proimmunogenic while apoptosis would be detrimental, as has previously been reported in the context of sterile cell death. Surprisingly, we found that the activation of any host cell death in the context of L. monocytogenes infection inhibited the generation of protective immunity and specifically the activation of antigen-specific CD8⁺ T cells. Importantly, the mechanism of attenuation was unique for each type of cell death, ranging from deficits in costimulation in the context of necrosis to a suboptimal inflammatory milieu in the case of pyroptosis. Our results suggest that cell death in the context of infection is different from sterile-environment-induced cell death and that inhibition of cell death or its downstream consequences is necessary for developing effective cell-mediated immune responses using L. monocytogenes-based immunotherapeutic platforms.

Insights on Molecular Mechanisms of Chondrocytes Death in Osteoarthritis

Osteoarthritis (OA) is a joint pathology characterized by progressive cartilage degradation. Medical care is mainly based on alleviating pain symptoms. Compelling studies report the presence of empty lacunae and hypocellularity in cartilage with aging and OA progression, suggesting that chondrocyte cell death occurs and participates to OA development. However, the relative contribution of apoptosis per se in OA pathogenesis appears complex to evaluate. Indeed, depending on technical approaches, OA stages, cartilage layers, animal models, as well as in vivo or in vitro experiments, the percentage of apoptosis and cell death types can vary. Apoptosis, chondroptosis, necrosis, and autophagic cell death are described in this review. The question of cell death causality in OA progression is also addressed, as well as the molecular pathways leading to cell death in response to the following inducers: Fas, Interleukin-1β (IL-1β), Tumor Necrosis factor-α (TNF-α), leptin, nitric oxide (NO) donors, and mechanical stresses. Furthermore, the protective role of autophagy in chondrocytes is highlighted, as well as its decline during OA progression, enhancing chondrocyte cell death; the transition being mainly controlled by HIF-1α/HIF-2α imbalance. Finally, we have considered whether interfering in chondrocyte apoptosis or promoting autophagy could constitute therapeutic strategies to impede OA progression.