Necroptosis in the Pathophysiology of Disease

A novel necroptosis-related lncRNAs signature for survival prediction in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common kind of kidney cancer with poor prognosis. Necroptosis is a newly observed type of programmed cell death in recent years. However, the effects of necroptosis-related lncRNAs (NRlncRNAs) on ccRCC have not been widely explored. The transcription profile and clinical information were obtained from The Cancer Genome Atlas. Necroptosis-related lncRNAs were identified by utilizing a co-expression network of necroptosis-related genes and lncRNAs. Univariate Cox regression, least absolute shrinkage, and selection operator regression and multivariate Cox regression were performed to screen out ideal prognostic necroptosis-related lncRNAss and develop a multi-lncRNA signature. Finally, 6 necroptosis-related lncRNA markers were established. Patients were separated into high- and low-risk groups based on the performance value of the median risk score. Kaplan-Meier analysis identified that high-risk patients had poorer prognosis than low-risk patients. Furthermore, the area under time-dependent receiver operating characteristic curve reached 0.743 at 1 year, 0.719 at 3 years, and 0.742 at 5 years, which indicating that they can be used to predict ccRCC prognosis. In addition, the proposed signature was related to immunocyte infiltration. A nomogram model was also established to provide a more beneficial prognostic indicator for the clinic. Altogether, in the present study, the 6-lncRNA prognostic risk signature are trustworthy and effective indicators for predicting the prognosis of ccRCC.

Identification and validation of a novel necroptosis-related prognostic signature in cervical squamous cell carcinoma and endocervical adenocarcinoma

Background

The purpose of this study was to investigate the prognostic signature of necroptosis-related lncRNAs (NRLs) and explore their association with immune-related functions and sensitivity of the therapeutic drug in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC).

Methods

UCSC Xena provided lncRNA sequencing and clinical data about CESC, and a necroptosis gene list was obtained from the KEGG database. NRLs were selected by structuring a co-expression network of lncRNAs and necroptosis-related genes. To further screen lncRNAs, we used the univariate Cox regression method, Lasso regression, and multivariate Cox regression. Afterward, an NRL signature was established. We used the xCell algorithm and single-sample gene set enrichment analysis (ssGSEA) to clarify the pertinence between immune infiltration and NRL expressions in CESC patients and explored the relationship between the target lncRNAs and immune-related genes. By leveraging the GDSC database, the therapy-sensitive response of the prognostic signature was forecasted and an experimental validation was performed. We performed GSEA with the aim of recognizing the potential pathway related to the individual prognostic signature.

Results

The two prognostic NRLs (AC009095.1 and AC005332.4) showed significant diversity and constituted the NRL signature. On the grounds of our signature, risk score was an independent element which was bound up with patient outcome (HR = 4.97 CI: 1.87–13.2, P = 0.001). The CESC patients were classified by the median risk score. Immune infiltration analysis revealed significant increases in CD4 + Tcm, eosinophils, epithelial cells, fibroblasts, NKT, plasma cells, platelets, and smooth muscle in the high-risk group (P< 0.05). Target lncRNAs also showed some correlation with NRGs. The estimated IC50 values of bicalutamide, CHIR.99021, and imatinib were lower in the high-risk group. Through the subsequent experimental validation, both AC009095.1 and AC005332.4 were significantly more highly expressed in SiHa than in Hela. AC009095.1 was expressed more highly in SiHa than in HUCEC, but the expression of AC005332.4 was reversed.

Conclusions

This study elucidated that NRLs, as a novel signature, were indispensable factors which can significantly influence the prognosis of patients with CESC and could provide novel clinical evidence to serve as a potential molecular biomarker for future therapeutic targets.

Effect of drying method on the production of in vitro short-chain fatty acids and histone deacetylase mediation of cocoa pod husk

We evaluated the effect of cocoa pod husk (CPH) processing (microwave [MW], forced-air drying [FAD], and FAD plus extrusion [FAD-E]), and in vitro gastrointestinal digestion on the in vitro human colonic fermentation metabolism, in vitro bioactivity on human HT-29 colon cancer cell, and the in silico mechanism of selected compounds. CPH as a substrate for human colonic microbiota significantly decrease local pH (MW -0.7, FAD -0.2, and FAD-E -0.3, 24 h) and modifies their metabolic activity (short-chain fatty acids [SCFAs] production). FAD-E generated the highest butyric (7.6 mM/L, 4 h) and FAD the highest acetic and propionic acid levels (71.4 and 36.7 mM/L, 24 h). The in vitro colonic fermented FAD-E sample (FE/FAD-E) caused HT-29 colorectal cancer cells death by inducing damage on membrane integrity and inhibiting (up to 92%) histone-deacetylase (HDAC) activity. In silico results showed that chlorogenic acid, (-)-epicatechin, and (+)-catechin, followed by butyric and propionic acids, are highly involved in the HDAC6 inhibitory activity. The results highlight the potential human health postbiotic benefits of CPH consumption, mediated by colonic microbiota-derived metabolites. PRACTICAL APPLICATION: The enormous amount of CPH (10 tons/1 ton of dry beans) generated by the cocoa industry can be used as a removable source of bioactive compounds with physicochemical functionality and health bioactivity. However, their potential applications and health benefits are insufficiently explored. CPH represents a serious disposal problem; practical and innovative ideas to use this highly available and affordable material are urgent. Research exploring their potential applications can increase the sustainability of the cocoa agro-industry. This paper highlights the value addition that can be achieved with this valuable industrial co-product, generating new functional products and ingredients.

A necroptosis -related signature for predicting prognosis and immunotherapy in hepatocellular carcinoma

Background: Hepatocellular Carcinoma (HCC) is an aggressive tumor with an inferior prognosis. Necroptosis is a new form of programmed death that plays a dual effect on the tumor. However, the role of necroptosis-related genes(NRGs) in HCC remains unknown.

Methods: All datasets were downloaded from publicly available databases. The consensus clustering analysis was used to classify patients into different subtypes based on NRGs. The Least Absolute Shrinkage and Selection Operator (LASSO) Cox regression were used to develop a prognostic signature. Tumor Immune Dysfunction and Exclusion (TIDE) was used to predict immunotherapy response.

Results: The genetic and transcriptional changes of NRGs were observed in HCC. Patients were classified into three clusters based on differentially expressed NRGs, of which Cluster-3 had the worst prognosis and the highest immune infiltration. The prognostic signature was developed based on 8-NRGs, which have shown excellent prognostic performance. The high-risk group in the signature presented significantly higher immune infiltration, such as aDCs, iDCs, macrophages, and Treg, compared to the low-risk group. TMB and immune checkpoints were also higher in the high-risk group. Moreover, a lower TIDE score was observed in the high-risk group, indicating the patients with high risk-score may be suitable for immunotherapy. Via the dataset of IMvigor210, we found a higher risk score in the immunotherapy response group.

Conclusion: We developed a new necroptosis-related signature for predicting prognosis with the potential to predict immunotherapy for HCC patients.

Zearalenone Induces MLKL-Dependent Necroptosis in Goat Endometrial Stromal Cells via the Calcium Overload/ROS Pathway

Zearalenone (ZEA) is a fungal mycotoxin known to exert strong reproductive toxicity in animals. As a newly identified type of programmed cell death, necroptosis is regulated by receptor-interacting protein kinase 1 (RIPK1), receptor-interacting protein kinase 3 (RIPK3), and mixed-lineage kinase domain-like pseudokinase (MLKL). However, the role and mechanism of necroptosis in ZEA toxicity remain unclear. In this study, we confirmed the involvement of necroptosis in ZEA-induced cell death in goat endometrial stromal cells (gESCs). The release of lactate dehydrogenase (LDH) and the production of PI-positive cells markedly increased. At the same time, the expression of RIPK1 and RIPK3 mRNAs and P-RIPK3 and P-MLKL proteins were significantly upregulated in ZEA-treated gESCs. Importantly, the MLKL inhibitor necrosulfonamide (NSA) dramatically attenuated gESCs necroptosis and powerfully blocked ZEA-induced reactive oxygen species (ROS) generation and mitochondrial dysfunction. The reactive oxygen species (ROS) scavengers and N-acetylcysteine (NAC) inhibited ZEA-induced cell death. In addition, the inhibition of MLKL alleviated the intracellular Ca²⁺ overload caused by ZEA. The calcium chelator BAPTA-AM markedly suppressed ROS production and mitochondrial damage, thus inhibiting ZEA-induced necroptosis. Therefore, our results revealed the mechanism by which ZEA triggers gESCs necroptosis, which may provide a new therapeutic strategy for ZEA poisoning.

Research progress on astrocyte autophagy in ischemic stroke

Ischemic stroke is a highly disabling and potentially fatal disease. After ischemic stroke, autophagy plays a key regulatory role as an intracellular catabolic pathway for misfolded proteins and damaged organelles. Mounting evidence indicates that astrocytes are strongly linked to the occurrence and development of cerebral ischemia. In recent years, great progress has been made in the investigation of astrocyte autophagy during ischemic stroke. This article summarizes the roles and potential mechanisms of astrocyte autophagy in ischemic stroke, briefly expounds on the crosstalk of astrocyte autophagy with pathological mechanisms and its potential protective effect on neurons, and reviews astrocytic autophagy-targeted therapeutic methods for cerebral ischemia. The broader aim of the report is to provide new perspectives and strategies for the treatment of cerebral ischemia and a reference for future research on cerebral ischemia.

A novel prognostic and therapeutic target biomarker based on necroptosis-related gene signature and immune microenvironment infiltration in gastric cancer

Background: Gastric cancer is a major global public health burden worldwide. Although treatment strategies are continuously improving, the overall prognosis remains poor. Necroptosis is a newly discovered form of cell death associated with anti-tumor immunity.

Methods: Gastric cancer (GC) data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) were downloaded. Bioinformatics analysis was performed to construct a necroptosis-related risk model and to establish cancer subtypes. Potential associations of the tumor immune microenvironment and immunotherapy response with necroptosis-related prognostic risk score (NRG risk score) were comprehensively explored. 16 GC and paired normal tissues were collected and RT-PCR was performed to examine expression of NRG related genes.

Results: GC samples were stratified into three subtypes according to prognostic necroptosis gene expression. A necroptosis risk model based on 12 genes (NPC1L1, GAL, RNASE1, PCDH7, NOX4, GJA4, SLC39A4, BASP1, BLVRA, NCF1, PNOC, and CCR5) was constructed and validated. The model was significantly associated with the OS and PFS of GC patients and the tumor immune microenvironment including immune cell infiltration, microsatellite instability (MSI) status, tumor mutational burden (TMB) score, immune checkpoint, and human leukocyte antigen (HLA) gene expression. A prognostic nomogram based on the NRG_score was additionally constructed. A low NRG risk score was correlated with high tumor immunogenicity and might benefit from immunotherapy.

Conclusion: We have identified a useful prognostic model based on necroptosis-related genes in GC and comprehensively the relationship between necroptosis and tumor immunity. Predicting value to immunotherapy response is promising, and further research to validate the model in clinical practice is needed.

Insight into the interplay between mitochondria-regulated cell death and energetic metabolism in osteosarcoma

Osteosarcoma (OS) is a pediatric malignant bone tumor that predominantly affects adolescent and young adults. It has high risk for relapse and over the last four decades no improvement of prognosis was achieved. It is therefore crucial to identify new drug candidates for OS treatment to combat drug resistance, limit relapse, and stop metastatic spread. Two acquired hallmarks of cancer cells, mitochondria-related regulated cell death (RCD) and metabolism are intimately connected. Both have been shown to be dysregulated in OS, making them attractive targets for novel treatment. Promising OS treatment strategies focus on promoting RCD by targeting key molecular actors in metabolic reprogramming. The exact interplay in OS, however, has not been systematically analyzed. We therefore review these aspects by synthesizing current knowledge in apoptosis, ferroptosis, necroptosis, pyroptosis, and autophagy in OS. Additionally, we outline an overview of mitochondrial function and metabolic profiles in different preclinical OS models. Finally, we discuss the mechanism of action of two novel molecule combinations currently investigated in active clinical trials: metformin and the combination of ADI-PEG20, Docetaxel and Gemcitabine.

Acidosis induces RIPK1-dependent death of glioblastoma stem cells via acid-sensing ion channel 1a

Eliciting regulated cell death, like necroptosis, is a potential cancer treatment. However, pathways eliciting necroptosis are poorly understood. It has been reported that prolonged activation of acid-sensing ion channel 1a (ASIC1a) induces necroptosis in mouse neurons. Glioblastoma stem cells (GSCs) also express functional ASIC1a, but whether prolonged activation of ASIC1a induces necroptosis in GSCs is unknown. Here we used a tumorsphere formation assay to show that slight acidosis (pH 6.6) induces necrotic cell death in a manner that was sensitive to the necroptosis inhibitor Nec-1 and to the ASIC1a antagonist PcTx1. In addition, genetic knockout of ASIC1a rendered GSCs resistant to acid-induced reduction in tumorsphere formation, while the ASIC1 agonist MitTx1 reduced tumorsphere formation also at neutral pH. Finally, a 20 amino acid fragment of the ASIC1 C-terminus, thought to interact with the necroptosis kinase RIPK1, was sufficient to reduce the formation of tumorspheres. Meanwhile, the genetic knockout of MLKL, the executive protein in the necroptosis cascade, did not prevent a reduction in tumor sphere formation, suggesting that ASIC1a induced an alternative cell death pathway. These findings demonstrate that ASIC1a is a death receptor on GSCs that induces cell death during prolonged acidosis. We propose that this pathway shapes the evolution of a tumor in its acidic microenvironment and that pharmacological activation of ASIC1a might be a potential new strategy in tumor therapy.

A computational study to target necroptosis via RIPK1 inhibition

The human receptor-interacting serine/threonine-protein kinase 1 (RIPK1) is a critical necroptosis regulator implicated in cancer, psoriasis, ulcerative colitis, rheumatoid arthritis, Alzheimer's disease, and multiple sclerosis. Currently, there are no specific RIPK1 antagonists in clinical practice. In this study, we took a target-based computational approach to identify blood-brain-barrier-permeable potent RIPK1 ligands with novel chemotypes. Using molecular docking, we virtually screened the Marine Natural Products (MNP) library of 14,492 small molecules. Initial 18 hits were subjected to detailed ADMET profiling for bioavailability, brain penetration, druglikeness, and toxicities and eventually yielded 548773-66-6 as the best ligand. RIPK1 548773-66-6 binding was validated through duplicated molecular dynamics (MD) simulations where the co-crystallized ligand L8D served as a reference. Trajectory analysis indicated negligible Root-Mean-Square-Deviations (RMSDs) of the best ligand 548773-66-6 relative to the protein backbone: 0.156 ± 0.043 nm and 0.296 ± 0.044 nm (mean ± standard deviations) in two individual simulations. Visual inspection confirmed that 548773-66-6 occupied the RIPK1 ligand-binding pocket associated with the kinase activation loop. Further computations demonstrated consistent hydrogen bond interactions of the ligand with the residue ASP156. Binding free energy estimation also supported stable interactions of 548773-66-6 and RIPK1. Together, our in silico analysis predicted 548773-66-6 as a novel ligand for RIPK1. Therefore, 548773-66-6 could be a viable lead for inhibiting necroptosis in central nervous system inflammatory disorders.

Necroptosis in Alzheimer's disease: Potential therapeutic target

Alzheimer's disease is the sixth leading cause of death in the United States, and the number of patients with the disease is set to hit 20 million by 2050. In addition, necroptosis is a form of cell death that is found to occur in virtually all tissues. Its key feature is the disruption of the cell membrane that results in an inflammatory immune response. This study aimed to investigate the role of necroptosis in the development of Alzheimer's disease through a literature review. It was found that necroptosis not only occurs in Alzheimer's disease but also may play a crucial role due to several factors. Hyperglycemia activates the switch from apoptosis to necroptosis, and Alzheimer's disease is considered "diabetes type 3.' Second, reactive oxygen species are produced in excess during necroptosis, and affect the production of amyloid beta in Alzheimer's. Inflammation, a key consequence of necroptosis, also increases neurodegeneration and contributes to the overproduction of amyloid beta. These connections lend themselves to the 'starving brain' theory of Alzheimer's disease, and insulin resistance exacerbates the role of necroptosis in the development of Alzheimer's disease. Necroptosis may have a vicious-cycle effect in Alzheimer's disease due to various factors, and it is a key therapeutic target in Alzheimer's disease that should be further examined.

Buffalo Milk Whey Activates Necroptosis and Apoptosis in a Xenograft Model of Colorectal Cancer

Recent pharmacological research on milk whey, a byproduct of the dairy industry, has identified several therapeutic properties that could be exploited in modern medicine. In the present study, we investigated the anticancer effects of whey from Mediterranean buffalo (Bubalus bubalis) milk. The antitumour effect of delactosed milk whey (DMW) was evaluated using the HCT116 xenograft mouse model of colorectal cancer (CRC). There were no discernible differences in tumour growth between treated and untreated groups. Nevertheless, haematoxylin and eosin staining of the xenograft tissues showed clearer signs of different cell death in DMW-treated mice compared to vehicle-treated mice. Detailed biochemical and molecular biological analyses revealed that DMW was able to downregulate the protein expression levels of c-myc, phospho-Histone H3 (ser 10) and p-ERK. Moreover, DMW also activated RIPK1, RIPK3, and MLKL axis in tumour tissues from xenograft mice, thus, suggesting a necroptotic effect. The necroptotic pathway was accompanied by activation of the apoptotic pathway as revealed by increased expression of both cleaved caspase-3 and PARP-1. At the molecular level, DMW-induced cell death was also associated with (i) upregulation of SIRT3, SIRT6, and PPAR-γ and (ii) downregulation of LDHA and PPAR-α. Overall, our results unveil the potential of whey as a source of biomolecules of food origin in the clinical setting of novel strategies for the treatment of CRC.

Hydrogen Sulfide Suppresses Skin Fibroblast Proliferation via Oxidative Stress Alleviation and Necroptosis Inhibition

Keloid is a common dermatofibrotic disease with excessive skin fibroblast proliferation. Hydrogen sulfide (H₂S) as the third gasotransmitter improves fibrosis of various organs and tissues. Our study is aimed at investigating the effects and possible mechanisms of H₂S on skin fibroblast proliferation. Scar tissues from six patients with keloid and discarded skin tissue from six normal control patients were collected after surgery, respectively. Plasma H₂S content and skin H₂S production in patients with keloid were measured. Keloid fibroblasts and transforming growth factor-β₁- (TGF-β₁, 10 ng/mL) stimulated normal skin fibroblasts were pretreated with H₂S donor as NaHS (50 μM) for 4 h. Cell migration after scratch was assessed. The expressions of α-smooth muscle actin (α-SMA), proliferating cell nuclear antigen (PCNA), collagen I, and collagen III were detected by immunofluorescence, real-time PCR, and/or Western blot. Intracellular superoxide anion and mitochondrial superoxide were evaluated by dihydroethidium (DHE) and MitoSOX staining, respectively. Mitochondrial membrane potential was detected by JC-1 staining. Apoptotic cells were detected by TDT-mediated dUTP nick end labeling (TUNEL). The expressions of receptor interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like protein (MLKL) were measured by Western blot. We found that H₂S production was impaired in both the plasma and skin of patients with keloid. In keloid fibroblasts and TGF-β₁-stimulated normal skin fibroblasts, exogenous H₂S supplementation suppressed the expressions of α-SMA, PCNA, collagen I, and collagen III, reduced intracellular superoxide anion and mitochondrial superoxide, improved the mitochondrial membrane potential, decreased the positive rate of TUNEL staining, and inhibited RIPK1 and RIPK3 expression as well as MLKL phosphorylation. Overall, H₂S suppressed skin fibroblast proliferation via oxidative stress alleviation and necroptosis inhibition.

Ca2+/Calmodulin-Dependent Protein Kinase II Regulation by Inhibitor of Receptor Interacting Protein Kinase 3 Alleviates Necroptosis in Glycation End Products-Induced Cardiomyocytes Injury

Necroptosisis a regulatory programmed form of necrosis. Receptor interacting protein kinase 3 (RIPK3) is a robust indicator of necroptosis. RIPK3 mediates myocardial necroptosis through activation of calcium/calmodulin-dependent protein kinase II (CaMKII) in cardiac ischemia-reperfusion (I/R) injury and heart failure. However, the exact mechanism of RIPK3 in advanced glycation end products (AGEs)-induced cardiomyocytes necroptosis is not clear. In this study, cardiomyocytes were subjected to AGEs stimulation for 24 h. RIPK3 expression, CaMKII expression, and necroptosis were determined in cardiomyocytes after AGEs stimulation. Then, cardiomyocytes were transfected with RIPK3 siRNA to downregulate RIPK3 followed by AGEs stimulation for 24 h. CaMKIIδ alternative splicing, CaMKII activity, oxidative stress, necroptosis, and cell damage were detected again. Next, cardiomyocytes were pretreated with GSK′872, a specific RIPK3 inhibitor to assess whether it could protect cardiomyocytes against AGEs stimulation. We found that AGEs increased the expression of RIPK3, aggravated the disorder of CaMKII δ alternative splicing, promoted CaMKII activation, enhanced oxidative stress, induced necroptosis, and damaged cardiomyocytes. RIPK3 downregulation or RIPK3 inhibitor GSK′872 corrected CaMKIIδ alternative splicing disorder, inhibited CaMKII activation, reduced oxidative stress, attenuated necroptosis, and improved cell damage in cardiomyocytes.

Comprehensive Characterization of Necroptosis-Related lncRNAs in Bladder Cancer Identifies a Novel Signature for Prognosis Prediction

Background

Bladder cancer (BC) is one of the most serious genitourinary malignant diseases with a poor prognosis. Necroptosis is a regulated form of cell death, and targeting necroptosis is emerging as a potential tumor therapy strategy. Nevertheless, the roles of necroptosis-related long noncoding RNAs (nrlncRNAs) in BC remains to be illustrated. This work is aimed at studying the clinical implications of nrlncRNAs in BC.

Methods

The RNA-seq data and corresponding clinical data, downloaded from The Cancer Genome Atlas (TCGA) database, were utilized to obtain prognostic nrlncRNAs and construct a prediction nomogram for BC. The comprehensive profiling of the functional pathways, immune status, mutational landscape, and drug sensitivity related to the necroptosis-related lncRNA signature (NerRLsig) was performed.

Results

Herein, a signature consisting of 12 necroptosis-related lncRNAs (AC015802.4, AL391807.1, AL078644.1, AC023825.2, AL132655.2, AP003352.1, STAG3L5P-PVRIG2P-PILRB, AC024451.4, MAP3K14-AS1, AL731567.1, AC010542.5, and AC009299.2) was constructed. The established signature can independently predict the poor overall survival of BC patients. Additionally, the NerRLsig had higher diagnostic validity compared to other clinicopathological variables, with a greater area under the receptor operating characteristic and concordance index curves. Finally, we found the differences in the functional signaling pathway, immune status, mutational profile, and drug sensitivity between the two subgroups.

Conclusion

This research revealed that the prognostic NerRLsig and nomogram could accurately predict the prognosis of BC.

Chondrocyte death involvement in osteoarthritis

Chondrocyte apoptosis is known to contribute to articular cartilage damage in osteoarthritis and is correlated to a number of cartilage disorders. Micromass cultures represent a convenient means for studying chondrocyte biology, and, in particular, their death. In this review, we focused the different kinds of chondrocyte death through a comparison between data reported in the literature. Chondrocytes show necrotic features and, occasionally, also apoptotic features, but usually undergo a new form of cell death called Chondroptosis, which occurs in a non-classical manner. Chondroptosis has some features in common with classical apoptosis, such as cell shrinkage, chromatin condensation, and involvement, not always, of caspases. The most crucial peculiarity of chondroptosis relates to the ultimate elimination of cellular remnants. Independent of phagocytosis, chondroptosis may serve to eliminate cells without inflammation in situations in which phagocytosis would be difficult. This particular death mechanism is probably due to the unusual condition chondrocytes both in vivo and in micromass culture. This review highlights on the morpho-fuctional alterations of articular cartilage and focus attention on various types of chondrocyte death involved in this degeneration. The death features have been detailed and discussed through in vitro studies based on tridimensional chondrocyte culture (micromasses culture). The study of this particular mechanism of cartilage death and the characterization of different biological and biochemical underlying mechanisms can lead to the identification of new potentially therapeutic targets in various joint diseases.

Targeting Necroptosis as a Promising Therapy for Alzheimer's Disease

Alzheimer's disease (AD) is an irreversible and progressive neurodegenerative disorder featured by memory loss and cognitive default. However, there has been no effective therapeutic approach to prevent the development of AD and the available therapies are only to alleviate some symptoms with limited efficacy and severe side effects. Necroptosis is a new kind of cell death, being regarded as a genetically programmed and regulated pattern of necrosis. Increasing evidence reveals that necroptosis is tightly related to the occurrence and development of AD. This review aims to summarize the potential role of necroptosis in AD progression and the therapeutic capacity of targeting necroptosis for AD patients.

Ca2+/Calmodulin-Dependent Protein Kinase II Regulation by RIPK3 Alleviates Necroptosis in Transverse Arch Constriction-Induced Heart Failure

Some studies have reported that the activation of Ca²⁺/calmodulin dependent protein kinase (CaMKII) plays a vital role in the pathogenesis of cardiovascular disease. Moreover, receptor interacting protein kinase 3 (RIPK3)-mediated necroptosis is also involved in the pathological process of various heart diseases. In the present study, we aimed to investigate the effect of RIPK3-regulated CaMKII on necroptosis in heart failure (HF) and its underlying mechanism. Wild type (WT) and RIPK3-depleted (RIPK3^–/–) mice were treated with transverse arch constriction (TAC). After 6 weeks, echocardiography, myocardial injury, CaMKII activity, necroptosis, RIPK3 expression, mixed lineage kinase domain-like protein (MLKL) phosphorylation, and mitochondrial ultrastructure were measured. The results showed that TAC aggravated cardiac dysfunction, CaMKII activation, and necroptosis in WT mice. However, depletion of RIPK3 alleviated cardiac insufficiency, CaMKII activation, and necroptosis in TAC-treated mice. To verify the experimental results, WT mice were transfected with AAV-vector and AAV-RIPK3 shRNA, followed by TAC operation. The findings were consistent with the expected results. Collectively, our current data indicated that the activation of CaMKII, MLKL and necroptosis in HF mice were increased in a RIPK3-dependent manner, providing valuable insights into the pathogenesis and treatment strategy of HF.

Types of necroinflammation, the effect of cell death modalities on sterile inflammation

Distinct types of immune responses are activated by infections, which cause the development of type I, II, or III inflammation, regulated by Th1, Th2, Th17 helper T cells and ILC1, ILC2 and ILC3 cells, respectively. While the classification of immune responses to different groups of pathogens is widely accepted, subtypes of the immune response elicited by sterile inflammation have not yet been detailed. Necroinflammation is associated with the release of damage-associated molecular patterns (DAMP) from dying cells. In this review, we present that the distinct molecular mechanisms activated during apoptosis, necroptosis, pyroptosis, and ferroptosis lead to the release of different patterns of DAMPs and their suppressors, SAMPs. We summarize the currently available data on how regulated cell death pathways and released DAMPs and SAMPs direct the differentiation of T helper and ILC cells. Understanding the subtypes of necroinflammation can be crucial in developing strategies for the treatment of sterile inflammatory diseases caused by cell death processes.

A strategy for attenuation of acute radiation-induced lung injury using crocetin from gardenia fruit

PURPOSE

Radiation-induced lung injury limits the implementation of radiotherapy plans and severely impairs the quality of life. Crocetin has the capability to protect against radiation. This study is aimed at estimate the preventive effect and mechanism of crocetin on acute radiation induced lung injury.

METHODS AND MATERIALS

In this study, we offer a strategy for radiation-induced lung injury by using crocetin, an extract of gardenia fruit. Histopathology, transcriptomics, flow cytometry, and other methods have served to examine the effect and mechanism of crocetin on acute radiation-induced lung injury.

RESULTS

Crocetin effectively alleviates radiation-induced alveolar wall thickening and alveolar destruction. The number of normal alveoli and lung structure of mice is well protected by the prevention of crocetin. It is found that crocetin inhibits necroptosis to achieve effective radioprotection by down regulating the Tnfrsf10b gene in vitro.

CONCLUSION

Crocetin inhibits necroptosis through transcriptional regulation of the Tnfrsf10b gene, thereby preventing radiation-induced lung injury. This work may provide a new strategy for the prevention of lung radiation injury by the extract from Chinese herbal medicine.

Interplay between Cell Death and Cell Proliferation Reveals New Strategies for Cancer Therapy

Cell division and cell death are fundamental processes governing growth and development across the tree of life. This relationship represents an evolutionary link between cell cycle and cell death programs that is present in all cells. Cancer is characterized by aberrant regulation of both, leading to unchecked proliferation and replicative immortality. Conventional anti-cancer therapeutic strategies take advantage of the proliferative dependency of cancer yet, in doing so, are triggering apoptosis, a death pathway to which cancer is inherently resistant. A thorough understanding of how therapeutics kill cancer cells is needed to develop novel, more durable treatment strategies. While cancer evolves cell-intrinsic resistance to physiological cell death pathways, there are opportunities for cell cycle agnostic forms of cell death, for example, necroptosis or ferroptosis. Furthermore, cell cycle independent death programs are immunogenic, potentially licensing host immunity for additional antitumor activity. Identifying cell cycle independent vulnerabilities of cancer is critical for developing alternative strategies that can overcome therapeutic resistance.

Identification of Bladder Cancer Subtypes Based on Necroptosis-Related Genes, Construction of a Prognostic Model

Background

Necroptosis is associated with the development of many tumors but in bladder cancer the tumor microenvironment (TME) and prognosis associated with necroptosis is unclear.

Methods

We classified patients into different necroptosis subtypes by the expression level of NRGS (necroptosis-related genes) and analyzed the relationship between necroptosis subtypes of bladder cancer and TME, then extracted differentially expressed genes (DEGS) of necroptosis subtypes, classified patients into different gene subtypes according to DEGS, and performed univariate COX analysis on DEGS to obtain prognosis-related DEGS. All patients included in the analysis were randomized into the Train and Test groups in a 1:1 ratio, and the prognostic model was obtained using the LASSO algorithm and multivariate COX analysis with the Train group as the sample, and external validation of the model was conducted using the GSE32894.

Results

Two necroptosis subtypes and three gene subtypes were obtained by clustering analysis and the prognosis-related DEGS was subjected to the LASSO algorithm and multivariate COX analysis to determine six predictors to construct the prognostic model using the formula: riskScore = CERCAM × 0.0035 + POLR1H × −0.0294 + KCNJ15 × −0.0172 + GSDMB × −0.0109 + EHBP1 × 0.0295 + TRIM38 × −0.0300. The results of the survival curve, roc curve, and risk curve proved the reliability of the prognostic model by validating the model with the test group and the results of the calibration chart of the Nomogram applicable to the clinic also showed its good accuracy. Necroptosis subtype A with high immune infiltration had a higher risk score than necroptosis subtype B, gene subtype B with low immune infiltration had a lower risk score than gene subtypes A and C, CSC index was negatively correlated with the risk score and drug sensitivity prediction showed that commonly used chemotherapeutic agents were highly sensitive to the high-risk group.

Conclusion

Our analysis of NRGS in bladder cancer reveals their potential role in TME, immunity, and prognosis. These findings may improve our understanding of necroptosis in bladder cancer and provide some reference for predicting prognosis and developing immunotherapies.

Anticancer potential and through study of the cytotoxicity mechanism of ionic liquids that are based on the trifluoromethanesulfonate and bis(trifluoromethylsulfonyl)imide anions

Ionic liquids (ILs) are known for their unique physicochemical properties. However, despite the great number of published papers, still little attention has been paid to their biological activity. Anticancer potential and the molecular mechanisms underlying the toxicity of these compounds are especially interesting and still unexplored. In the current work, a broad analysis of the cytotoxicity towards colon and breast cancers as well as glioblastoma of the ILs with pyridinium, piperidinium, pyrrolidinium, and imidazolium cations and trifluoromethanesulfonate or bis(trifluoromethylsulfonyl)imide anions indicated previously as the most toxic for normal human dermal fibroblasts were presented. In the case of MCF-7 cells, the activity of 1-decyl-3-methylimidazolium trifluoromethanesulfonate was more than twice as high as cisplatin. It was found that the inhibition of the cell cycle of colon cancer and glioblastoma cells occurs in different phases. More importantly, the different types of cell death were detected for both selected ILs, namely 1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and 1-hexyl-3-methylimidazolium trifluoromethane-sulfonate, on colon cancer and glioblastoma, respectively, apoptosis and autophagy, confirmed at the gene and protein levels. Additionally, kinetic studies of the reactive oxygen species indicated that the tested ILs disturbed the cellular redox homeostasis.

The Lck inhibitor, AMG-47a, blocks necroptosis and implicates RIPK1 in signalling downstream of MLKL

Necroptosis is a form of caspase-independent programmed cell death that arises from disruption of cell membranes by the mixed lineage kinase domain-like (MLKL) pseudokinase after its activation by the upstream kinases, receptor interacting protein kinase (RIPK)-1 and RIPK3, within a complex known as the necrosome. Dysregulated necroptosis has been implicated in numerous inflammatory pathologies. As such, new small molecule necroptosis inhibitors are of great interest, particularly ones that operate downstream of MLKL activation, where the pathway is less well defined. To better understand the mechanisms involved in necroptosis downstream of MLKL activation, and potentially uncover new targets for inhibition, we screened known kinase inhibitors against an activated mouse MLKL mutant, leading us to identify the lymphocyte-specific protein tyrosine kinase (Lck) inhibitor AMG-47a as an inhibitor of necroptosis. We show that AMG-47a interacts with both RIPK1 and RIPK3, that its ability to protect from cell death is dependent on the strength of the necroptotic stimulus, and that it blocks necroptosis most effectively in human cells. Moreover, in human cell lines, we demonstrate that AMG-47a can protect against cell death caused by forced dimerisation of MLKL truncation mutants in the absence of any upstream signalling, validating that it targets a process downstream of MLKL activation. Surprisingly, however, we also found that the cell death driven by activated MLKL in this model was completely dependent on the presence of RIPK1, and to a lesser extent RIPK3, although it was not affected by known inhibitors of these kinases. Together, these results suggest an additional role for RIPK1, or the necrosome, in mediating human necroptosis after MLKL is phosphorylated by RIPK3 and provide further insight into reported differences in the progression of necroptosis between mouse and human cells.

Induction of Paraptosis by Cyclometalated Iridium Complex-Peptide Hybrids and CGP37157 via a Mitochondrial Ca2+ Overload Triggered by Membrane Fusion between Mitochondria and the Endoplasmic Reticulum

We previously reported that a cyclometalated iridium (Ir) complex-peptide hybrid (IPH) 4 functionalized with a cationic KKKGG peptide unit on the 2-phenylpyridine ligand induces paraptosis, a relatively newly found programmed cell death, in cancer cells (Jurkat cells) via the direct transport of calcium (Ca²⁺) from the endoplasmic reticulum (ER) to mitochondria. Here, we describe that CGP37157, an inhibitor of a mitochondrial sodium (Na⁺)/Ca²⁺ exchanger, induces paraptosis in Jurkat cells via intracellular pathways similar to those induced by 4. The findings allow us to suggest that the induction of paraptosis by 4 and CGP37157 is associated with membrane fusion between mitochondria and the ER, subsequent Ca²⁺ influx from the ER to mitochondria, and a decrease in the mitochondrial membrane potential (ΔΨ_m). On the contrary, celastrol, a naturally occurring triterpenoid that had been reported as a paraptosis inducer in cancer cells, negligibly induces mitochondria-ER membrane fusion. Consequently, we conclude that the paraptosis induced by 4 and CGP37157 (termed paraptosis II herein) proceeds via a signaling pathway different from that of the previously known paraptosis induced by celastrol, a process that negligibly involves membrane fusion between mitochondria and the ER (termed paraptosis I herein).

Inhibition of RIP3 increased ADSC viability under OGD and modified the competency of adipogenesis, angiogenesis, and inflammation regulation

Adipose-derived stem cells (ADSCs) showed decreased cell viability and increased cell death under oxygen-glucose deprivation (OGD). Meanwhile, vital necroptotic proteins, including receptor-interacting protein kinase (RIP) 3 (RIP3) and mixed lineage kinase domain-like pseudokinase (MLKL), were expressed in the early stage. The present study aims to explore the effect of necroptosis inhibition on ADSCs. ADSCs were obtained from normal human subcutaneous fat and verified by multidirectional differentiation and flow cytometry. By applying cell counting kit-8 (CCK-8), calcein/propidium iodide (PI) staining and immunostaining, we determined the OGD treatment time of 4 h, a timepoint when the cells showed a significant decrease in viability and increased protein expression of RIP3, phosphorylated RIP3 (pRIP3) and phosphorylated MLKL (pMLKL). After pretreatment with the inhibitor of RIP3, necroptotic protein expression decreased under OGD conditions, and cell necrosis decreased. Transwell assays proved that cell migration ability was retained. Furthermore, the expression of the adipogenic transcription factor peroxisome proliferator-activated receptor γ (PPARγ) and quantitative analysis of Oil Red O staining increased in the inhibitor group. The expression of vascular endothelial growth factor-A (VEGFA) and fibroblast growth factor 2 (FGF2) and the migration test suggest that OGD increases the secretion of vascular factors, promotes the migration of human umbilical vein endothelial cells (HUVECs), and forms unstable neovascularization. ELISA revealed that inhibition of RIP3 increased the secretion of the anti-inflammatory factor, interleukin (IL)-10 (IL-10) and reduced the expression of the proinflammatory factor IL-1β. Inhibition of RIP3 can reduce the death of ADSCs, retain their migration ability and adipogenic differentiation potential, reduce unstable neovascularization and inhibit the inflammatory response.

Modes of podocyte death in diabetic kidney disease: an update

Diabetic kidney disease (DKD) accounts for a large proportion of end-stage renal diseases that require renal replacement therapies including dialysis and transplantation. Therefore, it is critical to understand the occurrence and development of DKD. Podocytes are mainly injured during the development of DKD, ultimately leading to their extensive death and loss. In turn, the injury and death of glomerular podocytes are also the main culprits of DKD. This review introduces the characteristics of podocytes and summarizes the modes of their death in DKD, including apoptosis, autophagy, mitotic catastrophe (MC), anoikis, necroptosis, and pyroptosis. Apoptosis is characterized by nuclear condensation and the formation of apoptotic bodies, and it exerts a different effect from autophagy in mediating DKD-induced podocyte loss. MC mediates a faulty mitotic process while anoikis separates podocytes from the basement membrane. Moreover, pyroptosis activates inflammatory factors to aggravate podocyte injuries whilst necroptosis drives signaling cascades, such as receptor-interacting protein kinases 1 and 3 and mixed lineage kinase domain-like, ultimately promoting the death of podocytes. In conclusion, a thorough knowledge of the modes of podocyte death in DKD can help us understand the development of DKD and lay the foundation for strategies in DKD disease therapy.

Development and Validation of a Necroptosis-Related Prognostic Model in Head and Neck Squamous Cell Carcinoma

Necroptosis is a new regulated cell-death mechanism that plays a critical role in various cancers. However, few studies have considered necroptosis-related genes (NRGs) as prognostic indexes for cancer. As one of the most common cancers in the world, head and neck squamous cell carcinoma (HNSCC) lacks effective diagnostic strategies at present. Hence, a series of novel prognostic indexes are required to support clinical diagnosis. Recently, many studies have confirmed that necroptosis was a key regulated mechanism in HNSCC, but no systematic study has ever studied the correlation between necroptosis-related signatures and the prognosis of HNSCC. Thus, in the current study, we aimed to construct a risk model of necroptosis-related signatures for HNSCC. We acquired 159 NRGs from the Kyoto Encyclopedia of Genes and Genomes (KEGG) and compared them with samples of normal tissue downloaded from The Cancer Genome Atlas (TCGA), ultimately screening 38 differentially expressed NRGs (DE-NRGs). Then, by Cox regression analysis, we successfully identified 7 NRGs as prognostic factors. We next separated patients into high- and low-risk groups via the prognostic model consisting of 7 NRGs. Individuals in the high-risk group had much shorter overall survival (OS) times than their counterparts. Furthermore, using Cox regression analysis, we confirmed the necroptosis-related prognostic model to be an independent prognostic factor for HNSCC. Receiver operating characteristic (ROC) curve analysis proved the predictive ability of this model. Finally, Gene Expression Omnibus (GEO) data sets (GSE65858, GSE4163) were used as independent databases to verify the model’s predictive ability, and similar results obtained from two data sets confirmed our conclusion. Collectively, in this study, we first referred to necroptosis-related signatures as an independent prognostic model for cancer via bioinformatics measures, and the necroptosis-related prognostic model we constructed could precisely forecast the OS time of patients with HNSCC. Utilizing the model may significantly improve the diagnostic rate and provide a series of new targets for treatment in the future.

Identification and Quantification of Necroptosis Landscape on Therapy and Prognosis in Kidney Renal Clear Cell Carcinoma

Kidney renal clear cell carcinoma (KIRC) has high morbidity and gradually increased in recent years, and the rate of progression once relapsed is high. At present, owing to lack of effective prognosis predicted markers and post-recurrence drug selection guidelines, the prognosis of KIRC patients is greatly affected. Necroptosis is a regulated form of cell necrosis in a way that is independent of caspase. Induced necroptosis is considered an effective strategy in chemotherapy and targeted drugs, and it can also be used to improve the efficacy of immunotherapy. Herein, we quantified the necroptosis landscape of KIRC patients from The Cancer Genome Atlas (TCGA) database and divided them into two distinct necroptosis-related patterns (C1 and C2) through the non-negative matrix factorization (NMF) algorithm. Multi-analysis revealed the differences in clinicopathological characteristics and tumor immune microenvironment (TIME). Then, we constructed the NRG prognosis signature (NRGscore), which contained 10 NRGs (PLK1, APP, TNFRSF21, CXCL8, MYCN, TNFRSF1A, TRAF2, HSP90AA1, STUB1, and FLT3). We confirmed that NRGscore could be used as an independent prognostic marker for KIRC patients and performed excellent stability and accuracy. A nomogram model was also established to provide a more beneficial prognostic indicator for the clinic. We found that NRGscore was significantly correlated with clinicopathological characteristics, TIME, and tumor mutation burden (TMB) of KIRC patients. Moreover, NRGscore had effective guiding significance for immunotherapy, chemotherapy, and targeted drugs.

Primary and Secondary Cone Cell Death Mechanisms in Inherited Retinal Diseases and Potential Treatment Options

Inherited retinal diseases (IRDs) are a leading cause of blindness. To date, 260 disease-causing genes have been identified, but there is currently a lack of available and effective treatment options. Cone photoreceptors are responsible for daylight vision but are highly susceptible to disease progression, the loss of cone-mediated vision having the highest impact on the quality of life of IRD patients. Cone degeneration can occur either directly via mutations in cone-specific genes (primary cone death), or indirectly via the primary degeneration of rods followed by subsequent degeneration of cones (secondary cone death). How cones degenerate as a result of pathological mutations remains unclear, hindering the development of effective therapies for IRDs. This review aims to highlight similarities and differences between primary and secondary cone cell death in inherited retinal diseases in order to better define cone death mechanisms and further identify potential treatment options.

Biliary Epithelial Senescence in Liver Disease: There Will Be SASP

Cellular senescence is a pathophysiological phenomenon in which proliferative cells enter cell cycle arrest following DNA damage and other stress signals. Natural, permanent DNA damage can occur after repetitive cell division; however, acute stress or other injuries can push cells into premature senescence and eventually a senescence-associated secretory phenotype (SASP). In recent years, there has been increased evidence for the role of premature senescence in disease progression including diabetes, cardiac diseases, and end-stage liver diseases including cholestasis. Liver size and function change with aging, and presumably with increasing cellular senescence, so it is important to understand the mechanisms by which cellular senescence affects the functional nature of the liver in health and disease. As well, cells in a SASP state secrete a multitude of inflammatory and pro-fibrogenic factors that modulate the microenvironment. Cellular SASP and the associated, secreted factors have been implicated in the progression of liver diseases, such as cholestatic injury that target the biliary epithelial cells (i.e., cholangiocytes) lining the bile ducts. Indeed, cholangiocyte senescence/SASP is proposed to be a driver of disease phenotypes in a variety of liver injuries. Within this review, we will discuss the impact of cholangiocyte senescence and SASP in the pathogenesis of cholestatic disorders.

Preliminary evidence for the presence of multiple forms of cell death in diabetes cardiomyopathy

Diabetic mellitus (DM) is a common degenerative chronic metabolic disease often accompanied by severe cardiovascular complications (DCCs) as major causes of death in diabetic patients with diabetic cardiomyopathy (DCM) as the most common DCC. The metabolic disturbance in DCM generates the conditions/substrates and inducers/triggers and activates the signaling molecules and death executioners leading to cardiomyocyte death which accelerates the development of DCM and the degeneration of DCM to heart failure. Various forms of programmed active cell death including apoptosis, pyroptosis, autophagic cell death, autosis, necroptosis, ferroptosis and entosis have been identified and characterized in many types of cardiac disease. Evidence has also been obtained for the presence of multiple forms of cell death in DCM. Most importantly, published animal experiments have demonstrated that suppression of cardiomyocyte death of any forms yields tremendous protective effects on DCM. Herein, we provide the most updated data on the subject of cell death in DCM, critical analysis of published results focusing on the pathophysiological roles of cell death, and pertinent perspectives of future studies.

The role of necroptosis in common respiratory diseases in children

Studies have shown that necroptosis (NEC) relies on a unique gene-regulated molecular pathway to cause cell death. With the development of knockout mouse models and specific molecular inhibitors of necrotic proteins, this cell death pathway has been considered one of the important causes of the pathogenesis of human diseases. In this review, we explored the possible roles and mechanisms of NEC in common respiratory diseases in children, such as acute lung injury, acute respiratory distress syndrome, pulmonary infection, childhood asthma, pulmonary hypertension, etc., in order to provide new ideas for the prevention and treatment of such diseases.

Cell Death in Hepatocellular Carcinoma: Pathogenesis and Therapeutic Opportunities

Simple Summary

The progression of liver tumors is highly influenced by the interactions between cancer cells and the surrounding environment, and, consequently, can determine whether the primary tumor regresses, metastasizes, or establishes micrometastases. In the context of liver cancer, cell death is a double-edged sword. On one hand, cell death promotes inflammation, fibrosis, and angiogenesis, which are tightly orchestrated by a variety of resident and infiltrating host cells. On the other hand, targeting cell death in advanced hepatocellular carcinoma could represent an attractive therapeutic approach for limiting tumor growth. Further studies are needed to investigate therapeutic strategies combining current chemotherapies with novel drugs targeting either cell death or the tumor microenvironment.

Abstract

Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer and the third leading cause of cancer death worldwide. Closely associated with liver inflammation and fibrosis, hepatocyte cell death is a common trigger for acute and chronic liver disease arising from different etiologies, including viral hepatitis, alcohol abuse, and fatty liver. In this review, we discuss the contribution of different types of cell death, including apoptosis, necroptosis, pyroptosis, or autophagy, to the progression of liver disease and the development of HCC. Interestingly, inflammasomes have recently emerged as pivotal innate sensors with a highly pathogenic role in various liver diseases. In this regard, an increased inflammatory response would act as a key element promoting a pro-oncogenic microenvironment that may result not only in tumor growth, but also in the formation of a premetastatic niche. Importantly, nonparenchymal hepatic cells, such as liver sinusoidal endothelial cells, hepatic stellate cells, and hepatic macrophages, play an important role in establishing the tumor microenvironment, stimulating tumorigenesis by paracrine communication through cytokines and/or angiocrine factors. Finally, we update the potential therapeutic options to inhibit tumorigenesis, and we propose different mechanisms to consider in the tumor microenvironment field for HCC resolution.

Controlled decompression attenuates brain damage in a rat model of epidural extreme intracranial hypertension: Partially via inhibiting necroptosis and inflammatory response

Intracranial hypertension (IH) remains a common symptom of neurological diseases, and requires stepwise treatments to release intracranial pressure (ICP). In the present study, we built a rat model of epidural extreme intracranial hypertension (EEIH) and verified the effectiveness of a surgery method called controlled decompression on attenuating brain injury induced by EEIH. For the model part, we determined the level of EEIH of rats via recording ICP and cerebral perfusion pressure (CPP) and the variation tendency of survival rates, mean blood artery pressure and mean velocity (Vm) of left middle cerebral artery (LMCA) as ICP ascending. SD rats were assigned into 4 groups: Sham group, Controlled decompression group (Con group), Rapid decompression group (Rap group) and Rapid decompression + Necrostatin-1 (Nec-1) group (Rap+Nec-1 group). The results suggested that controlled decompression lowered cerebral water content, improved neurological function, and attenuated EEIH-induced inflammation response and ROS generation to a greater extent than rapid decompression. Meanwhile, controlled decompression functioned to preserve more Nissl bodies, indicating alleviated neuron injury after EEIH. Additionally, the permeability of blood brain barrier (BBB) was also safeguarded in the Con group. Western blotting (WB) and Real-time Polymerase Chain Reaction (rt-PCR) assays consistently determined lower protein and mRNA levels of necroptosis-related molecules receptor interacting protein kinase 1 (RIPK1), interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL) (WB only) in the Con and Rap+Nec-1 group. Double immunofluorescent staining found weaker fluorescence intensity of RIPK3 in the compressed cortex of the Con and Rap+Nec-1 group.

RIPK1 inhibition enhances the therapeutic efficacy of chidamide in FLT3-ITD positive AML, both in vitro and in vivo

Acute myeloid leukemia (AML) with FLT3-ITD mutation accounts for a large proportion of relapsed/refractory AML with poor prognosis. RIPK1 is a known key regulator of necroptosis and RIPK1 inhibition shows anti-AML effects in vitro. Chidamide is a histone deacetylase inhibitor (HDACi) with proven ability to induce apoptosis in FLT3-ITD positive AML cells. In the present study, we evaluated the effects of the combination of 22b, a novel RIPK1 inhibitor, and chidamide on proliferation and apoptosis in FLT3-ITD positive AML cell lines and primary cells. The results showed that 22b could significantly enhance the anti-leukemia effect of low-dose chidamide both on cell lines and primary cells. In a subcutaneous xenograft AML model, the combination of 22b and chidamide exhibited obviously elevated anti-tumor activity. In conclusion, our results support that the combination of RIPK1 inhibitor 22b and chidamide may be a novel therapeutic avenue for FLT3-ITD positive AML patients.

Biologic and pathologic aspects of osteocytes in the setting of medication-related osteonecrosis of the jaw (MRONJ)

Medication-related osteonecrosis of the jaw (MRONJ) is a potentially severe, debilitating condition affecting patients with cancer and patients with osteoporosis who have been treated with powerful antiresorptives (pARs) or angiogenesis inhibitors (AgIs). Oral risk factors associated with the development of MRONJ include tooth extraction and inflammatory dental disease (e.g., periodontitis, periapical infection). In bone tissues, osteocytes play a bidirectional role in which they not only act as the "receiver" of systemic signals from blood vessels, such as hormones and drugs, or local signals from the mineralized matrix as it is deformed, but they also play a critical role as "transmitter" of signals to the cells that execute bone modeling and remodeling (osteoclasts, osteoblasts and lining cells). When the survival capacity of osteocytes is overwhelmed, they can die. Osteocyte death has been associated with several pathological conditions. Whereas the causes and mechanisms of osteocyte death have been studied in conditions like osteonecrosis of the femoral head (ONFH), few studies of the causes and mechanisms of osteocyte death have been done in MRONJ. The three forms of cell death that affect most of the different cells in the body (apoptosis, autophagy, and necrosis) have been recognized in osteocytes. Notably, necroptosis, a form of regulated cell death with "a necrotic cell death phenotype," has also been identified as a form of cell death in osteocytes under certain pathologic conditions. Improving the understanding of osteocyte death in MRONJ may be critical for preventing disease and developing treatment approaches. In this review, we intend to provide insight into the biology of osteocytes, cell death, in general, and osteocyte death, in particular, and discuss hypothetical mechanisms involved in osteocyte death associated with MRONJ.

RIPK3-mediated cell death is involved in DUX4-mediated toxicity in facioscapulohumeral dystrophy

BACKGROUND

Facioscapulohumeral dystrophy (FSHD) is caused by mutations leading to the aberrant expression of the DUX4 transcription factor in muscles. DUX4 was proposed to induce cell death, but the involvement of different death pathways is still discussed. A possible pro-apoptotic role of DUX4 was proposed, but as FSHD muscles are characterized by necrosis and inflammatory infiltrates, non-apoptotic pathways may be also involved.

METHODS

We explored DUX4-mediated cell death by focusing on the role of one regulated necrosis pathway called necroptosis, which is regulated by RIPK3. We investigated the effect of necroptosis on cell death in vitro and in vivo experiments using RIPK3 inhibitors and a RIPK3-deficient transgenic mouse model.

RESULTS

We showed in vitro that DUX4 expression causes a caspase-independent and RIPK3-mediated cell death in both myoblasts and myotubes. In vivo, RIPK3-deficient animals present improved body and muscle weights, a reduction of the aberrant activation of the DUX4 network genes, and an improvement of muscle histology.

CONCLUSIONS

These results provide evidence for a role of RIPK3 in DUX4-mediated cell death and open new avenues of research.

Evolving Medical Imaging Techniques for the Assessment of Delayed Graft Function: A Narrative Review

Purpose of review

Delayed graft function (DGF) is a significant complication that contributes to poorer graft function and shortened graft survival. In this review, we sought to evaluate the current and emerging role of medical imaging modalities in the assessment of DGF and how it may guide clinical management.

Sources of information

PubMed, Google Scholar, and ClinicalTrial.gov up until February 2021.

Methods

This narrative review first examined the pathophysiology of DGF and current clinical management. We then summarized relevant studies that utilized medical imaging to assess posttransplant renal complications, namely, DGF. We focused our attention on noninvasive, evolving imaging modalities with the greatest potential for clinical translation, including contrast-enhanced ultrasound (CEUS) and multiparametric magnetic resonance imaging (MRI).

Key findings

A kidney biopsy in the setting of DGF can be used to assess the degree of ischemic renal injury and to rule out acute rejection. Biopsies are accompanied by complications and may be limited by sampling bias. Early studies on CEUS and MRI have shown their potential to distinguish between the 2 most common causes of DGF (acute tubular necrosis and acute rejection), but they have generally included only small numbers of patients and have not kept pace with more recent technical advances of these imaging modalities. There remains unharnessed potential with CEUS and MRI, and more robust clinical studies are needed to better evaluate their role in the current era.

Limitations

The adaptation of emerging approaches for imaging DGF will depend on additional clinical trials to study the feasibility and diagnostic test characteristics of a given modality. This is limited by access to devices, technical competence, and the need for interdisciplinary collaborations to ensure that such studies are well designed to appropriately inform clinical decision-making.

iPSC-Derived Gaucher Macrophages Display Growth Impairment and Activation of Inflammation-Related Cell Death

Gaucher disease is a lysosomal storage disorder characterized by β-glucosidase enzyme deficiency and substrate accumulation, especially in cells of the reticuloendothelial system. Typical features of the disease are the unrestrained activation of inflammatory mechanisms, whose molecular pathways are still unclear. To investigate biological mechanisms underlying the macrophage activation in GD, we derived iPSCs from a healthy donor and a GD patient line and differentiated them into hematopoietic progenitors. While GD iPSCs are able to efficiently give rise to CD33+/CD45+ myeloid progenitors, the maturation towards the CD14+/CD163+ monocyte/macrophages fate resulted enhanced in the GD lines, that in addition displayed a decreased growth potential compared to control cells either in semisolid or in liquid culture. The GD lines growth impairment was associated with a significant upregulation of RIPK3 and MLKL, two key effectors of necroptosis, the inflammation related cell death pathway. The activation of necroptosis, which has already been linked to neuronopathic GD, may play a role in the disease proinflammatory condition and in the identified cell growth defects. Understanding the GD macrophage role in the alteration of mechanisms linked to cellular metabolism imbalance, cell death and inflammation are crucial in identifying new ways to approach the disease.

Cell death mechanisms involved in cell injury caused by SARS-CoV-2

Coronavirus disease 2019 (Covid‐19) is an emerging novel respiratory infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) that rapidly spread worldwide. In addition to lung injury, Covid‐19 patients may develop extrapulmonary symptoms, including cardiac, liver, kidney, digestive tract, and neurological injuries. Angiotensin converting enzyme 2 is the major receptor for the entry of SARS‐CoV‐2 into host cells. The specific mechanisms that lead to cell death in different tissues during infection by SARS‐CoV‐2 remains unknown. Based on data of the previous human coronavirus SARS‐CoV together with information about SARS‐CoV‐2, this review provides a summary of the mechanisms involved in cell death, including apoptosis, autophagy, and necrosis, provoked by severe acute respiratory syndrome coronavirus.

Dispensable roles of Gsdmd and Ripk3 in sustaining IL-1β production and chronic inflammation in Th17-mediated autoimmune arthritis

Programmed necrosis, such as necroptosis and pyroptosis, is a highly pro-inflammatory cellular event that is associated with chronic inflammation. Although there are various triggers of pyroptosis and necroptosis in autoimmune tissue inflammation and subsequent lytic forms of cell death release abundant inflammatory mediators, including damage-associated molecular patterns and IL-1β, capable of amplifying autoimmune Th17 effector functions, it remains largely unclear whether the programs play a crucial role in the pathogenesis of autoimmune arthritis. We herein report that Gasdermin D (Gsdmd) and receptor interacting serine/threonine kinase 3 (Ripk3)-key molecules of pyroptosis and necroptosis, respectively-are upregulated in inflamed synovial tissues, but dispensable for IL-1β production and the development of IL-17-producing T helper (Th17) cell-mediated autoimmune arthritis in SKG mice. Gsdmd-/-, Ripk3-/-, or Gsdmd-/- Ripk3-/- SKG mice showed severe arthritis with expansion of arthritogenic Th17 cells in the draining LNs and inflamed joints, which was comparable to that in wild-type SKG mice. Despite the marked reduction of IL-1β secretion from Gsdmd-/- or Ripk3-/- bone marrow-derived DCs by canonical stimuli, IL-1β levels in the inflamed synovium were not affected in the absence of Gsdmd or Ripk3. Our results revealed that T cell-mediated autoimmune arthritis proceeds independently of the pyroptosis and necroptosis pathways.

NLRP3 inflammasome activation and cell death

The NLRP3 inflammasome is a cytosolic multiprotein complex composed of the innate immune receptor protein NLRP3, adapter protein ASC, and inflammatory protease caspase-1 that responds to microbial infection, endogenous danger signals, and environmental stimuli. The assembled NLRP3 inflammasome can activate the protease caspase-1 to induce gasdermin D-dependent pyroptosis and facilitate the release of IL-1β and IL-18, which contribute to innate immune defense and homeostatic maintenance. However, aberrant activation of the NLRP3 inflammasome is associated with the pathogenesis of various inflammatory diseases, such as diabetes, cancer, and Alzheimer's disease. Recent studies have revealed that NLRP3 inflammasome activation contributes to not only pyroptosis but also other types of cell death, including apoptosis, necroptosis, and ferroptosis. In addition, various effectors of cell death have been reported to regulate NLRP3 inflammasome activation, suggesting that cell death is closely related to NLRP3 inflammasome activation. In this review, we summarize the inextricable link between NLRP3 inflammasome activation and cell death and discuss potential therapeutics that target cell death effectors in NLRP3 inflammasome-associated diseases.

Cell-Type-Specific Gene Expression in Developing Mouse Neocortex: Intermediate Progenitors Implicated in Axon Development

Cerebral cortex projection neurons (PNs) are generated from intermediate progenitors (IPs), which are in turn derived from radial glial progenitors (RGPs). To investigate developmental processes in IPs, we profiled IP transcriptomes in embryonic mouse neocortex, using transgenic Tbr2-GFP mice, cell sorting, and microarrays. These data were used in combination with in situ hybridization to ascertain gene sets specific for IPs, RGPs, PNs, interneurons, and other neural and non-neural cell types. RGP-selective transcripts (n = 419) included molecules for Notch receptor signaling, proliferation, neural stem cell identity, apical junctions, necroptosis, hippo pathway, and NF-κB pathway. RGPs also expressed specific genes for critical interactions with meningeal and vascular cells. In contrast, IP-selective genes (n = 136) encoded molecules for activated Delta ligand presentation, epithelial-mesenchymal transition, core planar cell polarity (PCP), axon genesis, and intrinsic excitability. Interestingly, IPs expressed several “dependence receptors” (Unc5d, Dcc, Ntrk3, and Epha4) that induce apoptosis in the absence of ligand, suggesting a competitive mechanism for IPs and new PNs to detect key environmental cues or die. Overall, our results imply a novel role for IPs in the patterning of neuronal polarization, axon differentiation, and intrinsic excitability prior to mitosis. Significantly, IPs highly express Wnt-PCP, netrin, and semaphorin pathway molecules known to regulate axon polarization in other systems. In sum, IPs not only amplify neurogenesis quantitatively, but also molecularly “prime” new PNs for axogenesis, guidance, and excitability.

Insight into Crosstalk between Ferroptosis and Necroptosis: Novel Therapeutics in Ischemic Stroke

Ferroptosis is a nonapoptotic form of cell death characterized by iron-dependent accumulation of lipid hydroperoxides to lethal levels. Necroptosis, an alternative form of programmed necrosis, is regulated by receptor-interacting protein (RIP) 1 activation and by RIP3 and mixed-lineage kinase domain-like (MLKL) phosphorylation. Ferroptosis and necroptosis both play important roles in the pathological progress in ischemic stroke, which is a complex brain disease regulated by several cell death pathways. In the past few years, increasing evidence has suggested that the crosstalk occurs between necroptosis and ferroptosis in ischemic stroke. However, the potential links between ferroptosis and necroptosis in ischemic stroke have not been elucidated yet. Hence, in this review, we overview and analyze the mechanism underlying the crosstalk between necroptosis and ferroptosis in ischemic stroke. And we find that iron overload, one mechanism of ferroptosis, leads to mitochondrial permeability transition pore (MPTP) opening, which aggravates RIP1 phosphorylation and contributes to necroptosis. In addition, heat shock protein 90 (HSP90) induces necroptosis and ferroptosis by promoting RIP1 phosphorylation and suppressing glutathione peroxidase 4 (GPX4) activation. In this work, we try to deliver a new perspective in the exploration of novel therapeutic targets for the treatment of ischemic stroke.

Cell Death in Coronavirus Infections: Uncovering Its Role during COVID-19

Cell death mechanisms are crucial to maintain an appropriate environment for the functionality of healthy cells. However, during viral infections, dysregulation of these processes can be present and can participate in the pathogenetic mechanisms of the disease. In this review, we describe some features of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and some immunopathogenic mechanisms characterizing the present coronavirus disease (COVID-19). Lymphopenia and monocytopenia are important contributors to COVID-19 immunopathogenesis. The fine mechanisms underlying these phenomena are still unknown, and several hypotheses have been raised, some of which assign a role to cell death as far as the reduction of specific types of immune cells is concerned. Thus, we discuss three major pathways such as apoptosis, necroptosis, and pyroptosis, and suggest that all of them likely occur simultaneously in COVID-19 patients. We describe that SARS-CoV-2 can have both a direct and an indirect role in inducing cell death. Indeed, on the one hand, cell death can be caused by the virus entry into cells, on the other, the excessive concentration of cytokines and chemokines, a process that is known as a COVID-19-related cytokine storm, exerts deleterious effects on circulating immune cells. However, the overall knowledge of these mechanisms is still scarce and further studies are needed to delineate new therapeutic strategies.

Thromboplasminflammation in COVID-19 Coagulopathy: Three Viewpoints for Diagnostic and Therapeutic Strategies

Thromboplasminflammation in coronavirus disease 2019 (COVID-19) coagulopathy consists of angiotensin II (Ang II)-induced coagulopathy, activated factor XII (FXIIa)- and kallikrein, kinin system-enhanced fibrinolysis, and disseminated intravascular coagulation (DIC). All three conditions induce systemic inflammation via each pathomechanism-developed production of inflammatory cytokines. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) downregulates angiotensin-converting enzyme 2, leading to an increase in Ang II levels. Ang II-induced coagulopathy comprising platelet activation, thrombin generation, plasminogen activator inhibitor-1 expression and endothelial injury causes thrombosis via the angiotensin II type 1 receptor. SARS-CoV-2 RNA and neutrophil extracellular trap (NET) DNA activate FXII, resulting in plasmin generation through FXIIa- and kallikrein-mediated plasminogen conversion to plasmin and bradykinin-induced tissue-type plasminogen activator release from the endothelium via the kinin B2 receptor. NETs induce immunothrombosis at the site of infection (lungs), through histone- and DNA-mediated thrombin generation, insufficient anticoagulation control, and inhibition of fibrinolysis. However, if the infection is sufficiently severe, immunothrombosis disseminates into the systemic circulation, and DIC, which is associated with the endothelial injury, occurs. Inflammation, and serine protease networks of coagulation and fibrinolysis, militate each other through complement pathways, which exacerbates three pathologies of COVID-19 coagulopathy. COVID-19 coagulopathy causes microvascular thrombosis and bleeding, resulting in multiple organ dysfunction and death in critically ill patients. Treatment targets for improving the prognosis of COVID-19 coagulopathy include thrombin, plasmin, and inflammation, and SARS-CoV-2 infection. Several drugs are candidates for controlling these conditions; however, further advances are required to establish robust treatments based on a clear understanding of molecular mechanisms of COVID-19 coagulopathy.

Necroptosis molecular mechanisms: Recent findings regarding novel necroptosis regulators

Necroptosis is a form of programmed necrosis that is mediated by various cytokines and pattern recognition receptors (PRRs). Cells dying by necroptosis show necrotic phenotypes, including swelling and membrane rupture, and release damage-associated molecular patterns (DAMPs), inflammatory cytokines, and chemokines, thereby mediating extreme inflammatory responses. Studies on gene knockout or necroptosis-specific inhibitor treatment in animal models have provided extensive evidence regarding the important roles of necroptosis in inflammatory diseases. The necroptosis signaling pathway is primarily modulated by activation of receptor-interacting protein kinase 3 (RIPK3), which phosphorylates mixed-lineage kinase domain-like protein (MLKL), mediating MLKL oligomerization. In the necroptosis process, these proteins are fine-tuned by posttranslational regulation via phosphorylation, ubiquitination, glycosylation, and protein-protein interactions. Herein, we review recent findings on the molecular regulatory mechanisms of necroptosis.

Inhibition of receptor-interacting protein kinase-3 in the necroptosis pathway attenuates inflammatory bone loss in experimental apical periodontitis in Balb/c mice

AIM

To explore the role of necroptosis in apical periodontitis (AP), this study investigated necroptosis in a Fusobacterium nucleatum (Fn)-induced AP model of Balb/c mice and explored related intracellular signalling pathways in L929 cells affected by Fn.

METHODOLOGY

For the in vivo experiments, expression of receptor-interacting protein kinase-3 (RIP3) was inhibited using an adeno-associated virus and then the Balb/c mice model of AP was established by injecting Fn into the root canal of the first mandibular molars. Bone loss and number of osteoclasts were measured via micro-computed tomography and tartrate-resistant acid phosphatase staining, respectively; expression of RIP3 and phosphorylated mixed lineage kinase domain-like protein (pMLKL) was detected by immunohistochemistry and western blotting; expression of mRNA of inflammatory cytokines was evaluated using quantitative real-time polymerase chain reaction (qRT-PCR). For the in vitro experiments, L929 cells transfected with RIP3-Mus-siRNA or negative control siRNA were co-cultured with Fn; thereafter, western blotting, detection of cell death and viability and qRT-PCR analyses were performed to assess the activation of necroptosis pathway and expression of mRNA of inflammatory cytokines. Data were analysed with unpaired t-test and one-way analysis of variance with significance set at p < .05.

RESULTS

The Fn-induced apical lesions were associated with apical bone loss, an increased number of osteoclasts, enhanced expression of pMLKL and increased mRNA levels of inflammatory cytokines(IL-1α and IL-1β); all these effects were alleviated by RIP3 inhibition (p < .05). L929 cells infected with Fn displayed increased expression of pMLKL and increased cell death (p < .05), together with decreased cell viability (p < .05), whilst transfection with RIP3-Mus-siRNA decreased the mRNA expression of inflammatory cytokines(TNF-α and IL-6, p < .05).

CONCLUSIONS

Necroptosis may be involved in AP progression. RIP3 inhibition ameliorated the expression of inflammatory cytokines and bone resorption in Fn-induced AP lesions in Balb/c mice.

Advanced research on the regulated necrosis mechanism in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury is an important factor that seriously affects the prognosis of patients with myocardial infarction. It can cause myocardial stun, no-reflow phenomenon, reperfusion arrhythmia, and even irreversible cardiomyocyte death. Regulated necrosis is a newly discovered type of regulatory cell death that is different from apoptosis, including necroptosis, pyrolysis, iron death and other forms. Regulated necrosis plays an important role in myocardial infarction, heart failure and other cardiovascular diseases, as well as myocardial ischemia-reperfusion injury and other pathophysiological processes, and is expected to become a new target for intervention in this type of disease.