ZBP1 promotes fungi-induced inflammasome activation and pyroptosis, apoptosis, and necroptosis (PANoptosis)

Inhibition of Piezo1 ameliorates septic cardiomyopathy by blocking calcium-dependent PANoptosis

Sepsis-induced cardiomyopathy (SIC) represents a severe and often fatal complication of sepsis, characterized by significant mortality. Despite extensive research, the underlying mechanisms remain incompletely understood. Recent studies have highlighted PANoptosis, an emerging form of programmed cell death, as a critical factor in inflammatory diseases. Piezo1, a mechanosensitive ion channel, has been implicated in various pathological conditions; however, its role in SIC and its involvement in PANoptosis require further investigation. In this study, the role of Piezo1 in SIC and calcium-dependent PANoptosis were investigated. SIC was induced in mice via cecal ligation and puncture (CLP), and the effects of Piezo1 inhibition on cardiac function, histological changes, mitochondrial function, and PANoptosis were assessed. Our results show that sepsis upregulates Piezo1 expression in cardiomyocytes through TLR4-NF-κB signaling. Pharmacological blockade of Piezo1 with its inhibitor GsMTx4 attenuated CLP-induced cardiac injury, histological damage, and mitochondrial dysfunction. Importantly, Piezo1 inhibition also significantly suppressed PANoptosis in septic hearts. In vitro experiments with Piezo1 siRNA, GsMTx4 and the calcium chelator BAPTA confirmed that inhibition of Piezo1 attenuates LPS-induced PANoptosis by limiting calcium release in cardiomyocytes after LPS treatment, linking Piezo1 to the regulation of these key events. Collectively, these findings reveal Piezo1 as a novel mechanosensor for sepsis and reveal a previously unrecognized role of Piezo1 in the activation of calcium-mediated PANoptosis in SIC. Given the ability of Piezo1 inhibition to mitigate key pathological features of SIC, targeting Piezo1 represents a promising therapeutic strategy for improving the outcomes of sepsis-related cardiac dysfunction.

Candidalysin biology and activation of host cells

Candida albicans is an opportunistic fungal pathogen that can cause life-threatening systemic infections and distressing mucosal infections. A major breakthrough in understanding C. albicans pathogenicity was the discovery of candidalysin, the first cytolytic peptide toxin identified in a human pathogenic fungus. Secreted by C. albicans hyphae and encoded by the ECE1 gene, this 31-amino acid peptide integrates into and permeabilizes host cell membranes, causing damage across diverse cell types. Beyond its cytolytic activity, candidalysin can trigger potent innate immune responses in epithelial cells, macrophages, and neutrophils. Additionally, candidalysin plays a key role in nutrient acquisition during infection. This review explores the biology of candidalysin, its role in host cell activation, and extends the discussion to non-candidalysin Ece1p peptides, shedding light on their emerging significance.

PANoptosis: a potential target of atherosclerotic cardiovascular disease

PANoptosis is a newly discovered cell death pathway triggered by the innate immunizer, which in turn promotes the assembly of the PANoptosome and activates downstream effectors. As a special cell death mode, it is characterized by apoptosis, pyroptosis, and necroptosis at the same time; therefore, it is not feasible to inhibit PANoptosis by suppressing a single cell death pathway. However, active ingredients targeting the PANoptosome can effectively inhibit PANoptosis.Given the importance of cell death in disease, targeting PANoptosis would be an important therapeutic tool. Previous studies have focused more on infectious diseases and cancer, and the role of PANoptosis in the cardiovascular field has not been comprehensively addressed. While ASCVD is the number one killer of cardiovascular diseases, it is important to explore new targets to determine future research directions. Therefore, this review focuses on the assembly of PANoptosome, the molecular mechanism of PANoptosis, and the related mechanisms of PANoptosis leading to ASCVD such as myocardial infarction, ischemic cardiomyopathy and ischemic stroke, in order to provide a new perspective for the prevention and treatment of ASCVD.

Investigation of PANoptosis pathway in age-related macular degeneration triggered by Aβ1-40

Our study aimed to identify PANoptosis in Aβ1-40-induced AMD, both in vivo and in vitro, and to determine if AIM2-PANoptosome mediates this process. We used transcriptomics to explore the signaling pathways and target genes linked to PANoptosis within a mouse model of AMD triggered by Aβ1-40. Optical coherence tomography (OCT), hematoxylin and eosin (H&E) staining, and electroretinography (ERG) were employed to assess retinal damage in terms of morphology and function. Morphological changes in ARPE-19 cells were observed using optical microscopy and scanning electron microscopy. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of cytokines in cell supernatants, mouse orbital serum, and human plasma to evaluate the severity of inflammation. CO-immunoprecipitation(CoIP) and molecular docking were performed to assess the impact and expression of proteins associated with the AIM2-PANoptosome. Quantitative polymerase chain reaction (qPCR), Western blot (WB), immunofluorescence, and apoptosis detection kits were used to evaluate the expression levels of genes and proteins related to PANoptosis-like cell death. Our results showed that the Aβ1-40-induced AMD model had increased expression of apoptosis, necroptosis, and pyroptosis pathways, and AIM2-PANoptosome components. CoIP and docking confirmed increased AIM2, ZBP1, and PYRIN levels under Aβ1-40 treatment. WB and immunofluorescence showed upregulation of PANoptosis-related proteins. Inhibitors reduced Aβ-induced protein expression. ELISA showed increased inflammatory cytokines. Apoptosis assays and microscopy revealed Aβ1-40-induced ARPE-19 cell loss and morphological changes. In conclusion, the Aβ1-40-induced AMD model displayed PANoptosis-like cell death, offering insights into disease pathogenesis.

How Cells Die in Psoriasis?

Psoriasis, a chronic immune-mediated inflammatory skin disorder characterized by keratinocyte hyperproliferation and inflammatory cell infiltration, involves multiple distinct programmed cell death pathways in its pathogenesis. Following the Nomenclature Committee on Cell Death recommendations, we analyzed the current literature examining diverse modes of cellular death in psoriatic lesions, with particular focus on keratinocyte cell death patterns and their molecular signatures. Analysis revealed several distinct cell death mechanisms: autophagy dysfunction through IL-17A pathways, decreased apoptotic activity in lesional skin, medication targeting anoikis in psoriasis, upregulated necroptosis mediated by RIPK1/MLKL signaling, gasdermin-mediated pyroptosis with enhanced IL-1β secretion, coordinated PANoptotic activation through specialized complexes, PARP1-mediated parthanatos promoting cutaneous inflammation, iron-dependent ferroptosis correlating with Th22/Th17 responses, copper-dependent cuproptosis with elevated MTF1/ATP7B/SLC31A1 expression, and NETosis amplifying immune responses through interaction with the Th17 axis. The intricate interplay between these cell death mechanisms has led to the development of targeted therapeutic strategies, including mTOR inhibitors for autophagy modulation, RIPK1 inhibitors for necroptosis, and various approaches targeting ferroptosis and NETosis, providing new directions for more effective psoriasis treatments.

Discovery of novel sitolactone derivative leading to PANoptosis and differentiation of acute myeloid leukemia cells

Acute Myeloid Leukemia (AML) is a devastating hematologic malignancy. Chemotherapy remains the primary treatment, offering rapid disease control and potential complete remission. However, more than half of the patients develop resistance and relapse, significantly reducing patient survival. Research has shown that drug-resistance and recurrence of AML are closely linked to leukemic stemness. Consequently, discovering new anti-Leukemia stem cell (LSC) compounds is a promising strategy for the treatment of AML in clinic. Additionally, the recent focus on inducing non-apoptotic programmed cell death in AML cells presents an alternative direction for therapeutic drug development, targeting current anti-apoptotic pathways. In this study, novel Sitolactone analogues, potential anti-LSCs compounds, were designed and synthesized based on the "biomimetic design" strategy. Compound 42 was found to significantly inhibit proliferation of AML cells. Subsequent biological evaluation revealed that this compound not only reduced the population of LSCs but also effectively induced PANoptosis in AML cells. Given the active compound's poor water solubility, a prodrug modification strategy was employed to enhance in vivo delivery with superior oral bioavailability and PK properties. This approach significantly suppressed AML cell growth in a mouse orthotropic model with favorable in vivo tolerance.

Unravelling the Role of PANoptosis in Liver Diseases: Mechanisms and Therapeutic Implications

PANoptosis is a multimodal form of cell death that involves inflammatory, apoptotic, and necroptotic pathways, playing a key role in the development of liver diseases. This article first outlines the definition and characteristics of PANoptosis, and then explores its mechanisms of action in different types of liver diseases, including acute liver injury, liver failure, metabolic dysfunction-associated fatty liver disease, and hepatocellular carcinoma. Furthermore, this article analyses the molecular regulatory network of PANoptosis and potential therapeutic targets. Finally, this article summarises the current research on PANoptosis in liver diseases and future research directions, and it reviews the role of the emerging cell death mechanism of PANoptosis in liver diseases.

Emerging role of PANoptosis in kidney diseases: molecular mechanisms and therapeutic opportunities

Kidney diseases represent a significant global public health challenge, characterized by complex pathogenesis, high incidence, low awareness, insufficient early screening, and substantial treatment disparities. Effective therapeutic options remain lacking. Programmed cell death (PCD), including apoptosis, pyroptosis, and necroptosis, play pivotal roles in the pathogenesis of various kidney diseases. In 2019, PANoptosis, a novel form of inflammatory cell death, was introduced, providing new insights into innate immunity and PCD research. Although research on PANoptosis in kidney diseases is still limited, identifying key molecules within PANoptosomes and understanding their regulatory roles is critical for disease prevention and management. This review summarizes the various forms of PCD implicated in kidney diseases, along with PANoptosomes activated by Z-DNA binding protein 1 (ZBP1), absent in melanoma 2 (AIM2), receptor-interacting protein kinase 1 (RIPK1), NOD-like receptor family CARD domain containing 12 (NLRP12), and NOD-like receptor family member C5 (NLRC5). It also reviews the advancements in PANoptosis research in the field of kidney diseases, particularly in renal tumors and acute kidney injuries (AKI). The goal is to establish a foundation for future research into the role of PANoptosis in kidney diseases.

Nd:YAG1064nm laser functions against Sporothrix globosa by inducing PANoptosis via the regulation of ZBP1-induced PANoptosome activation

Background

Due to the emergence of drug resistance in recent years, there is a need for new non-pharmacological treatment methods for sporotrichosis. Our previous study demonstrated that the Nd:YAG1064nm laser exhibited remarkable antifungal activity against Sporothrix globosa, but its exact mechanism remains unclear. This study aimed to detect PANoptosis regulatory protein ZBP1 expression in the skin lesions of patients with sporotrichosis, reveal the exact mechanism of Nd:YAG1064nm laser against sporotrichosis, and provide novel targets and methods for the diagnosis, assessment, and treatment of sporotrichosis.

Methodology/principal findings

The ZBP1 level of 60 patients with sporotrichosis (≤3 months; n = 30 and >3 months; n = 30) and 30 HC were retrospectively reviewed using immunohistochemistry. The morphological changes, Hoechst/PI apoptosis and necroptosis preliminary exploration analysis, DNA fragmentation, calcium determination, and metacaspase activation were investigated in vitro. For the in vivo studies, mice were infected with S. globosa and then treated with a laser, and their footpad skin lesions and changes in the histology of tissue samples were compared. Changes in the levels of ZBP1, PANoptosome [RIPK1, RIPK3, Fas-associated death domain protein (FADD), CASP8], pyroptosis (CASP1, GSDMD), apoptosis (CASP3), and necroptosis (MLKL) related proteins were assessed using immunohistochemistry, whereas the levels of interleukin 17 (IL-17) and interferon gamma (IFN-γ) in peripheral blood were tested by enzyme-linked immunosorbent assay. ZBP1 expression was significantly increased in S. globosa-infected patients. Laser treatment effectively inhibited the growth of S. globosa in vitro, destroying its morphological structure, and maybe inducing apoptosis and necroptosis. Moreover, DNA fragmentation, calcium release into the cytoplasm, and metacaspase activation were observed. In addition, laser treatment demonstrated a clear therapeutic effect in animal models of sporotrichosis, which can lead to PANoptosis-related apoptosis, pyroptosis, and necroptosis. Immune response-related macrophages perceive nucleic acid level changes through ZBP1 to recognize S. globosa and induce PANoptosis by activating the PANoptosome (RIPK1/RIPK3/FADD/CASP8) complex with a Th1/Th17 cell response to combat sporotrichosis.

Conclusion

Nd:YAG1064nm laser mediated PANoptosis resistance to sporotrichosis via ZBP1-PANoptosome-PANoptosis pathway.

TAK1 at the crossroads of multiple regulated cell death pathways: from molecular mechanisms to human diseases

Regulated cell death (RCD), the form of cell death that can be genetically controlled by multiple signaling pathways, plays an important role in organogenesis, tissue remodeling, and maintenance of organism homeostasis and is closely associated with various human diseases. Transforming growth factor‐beta‐activated kinase 1 (TAK1) is a member of the serine/threonine protein kinase family, which can respond to different internal and external stimuli and participate in inflammatory and immune responses. Emerging evidence suggests that TAK1 is an important regulator at the crossroad of multiple RCD pathways, including apoptosis, necroptosis, pyroptosis, and PANoptosis. The regulation of TAK1 affects disease progression through multiple signaling pathways, and therapeutic strategies targeting TAK1 have been proposed for inflammatory diseases, central nervous system diseases, and cancers. In this review, we provide an overview of the downstream signaling pathways regulated by TAK1 and its binding proteins. Their critical regulatory roles in different forms of cell death are also summarized. In addition, we discuss the potential of targeting TAK1 in the treatment of human diseases, with a specific focus on neurological disorders and cancer.

Integrative analysis of immunogenic PANoptosis and experimental validation of cinobufagin-induced activation to enhance glioma immunotherapy

BACKGROUND

Glioma, particularly glioblastoma (GBM), is a highly aggressive tumor with limited responsiveness to immunotherapy. PANoptosis, a form of programmed cell death merging pyroptosis, apoptosis, and necroptosis, plays an important role in reshaping the tumor microenvironment (TME) and enhancing immunotherapy effectiveness. This study investigates PANoptosis dynamics in glioma and explores the therapeutic potential of its activation, particularly through natural compounds such as cinobufagin.

METHODS

We comprehensively analyzed PANoptosis-related genes (PANoRGs) in multiple glioma cohorts, identifying different PANoptosis patterns and constructing the PANoptosis enrichment score (PANoScore) to evaluate its relationship with patient prognosis and immune activity. Cinobufagin, identified as a PANoptosis activator, was evaluated for its ability to induce PANoptosis and enhance anti-tumor immune responses both in vitro and in vivo GBM models.

RESULTS

Our findings indicate that high PANoScore gliomas showed increased immune cell infiltration, particularly effector T cells, and enhanced sensitivity to immunotherapies. Cinobufagin effectively induced PANoptosis, leading to increased immunogenic cell death, facilitated tumor-associated microglia/macrophages (TAMs) polarization towards an M1-like phenotype while augmenting CD4+/CD8 + T cell infiltration and activation. Importantly, cinobufagin combined with anti-PD-1 therapy exhibited significant synergistic effects and prolonged survival in GBM models.

CONCLUSIONS

These findings highlight the therapeutic potential of PANoptosis-targeting agents, such as cinobufagin, in combination with immunotherapy, offering a promising approach to convert "cold" tumors into "hot" ones and improving glioma treatment outcomes.

Regulated cell death in acute myocardial infarction: Molecular mechanisms and therapeutic implications

Acute myocardial infarction (AMI), primarily caused by coronary atherosclerosis, initiates a series of events that culminate in the obstruction of coronary arteries, resulting in severe myocardial ischemia and hypoxia. The subsequent myocardial ischemia/reperfusion (I/R) injury further aggravates cardiac damage, leading to a decline in heart function and the risk of life-threatening complications. The complex interplay of multiple regulated cell death (RCD) pathways plays a pivotal role in the pathogenesis of AMI. Each RCD pathway is orchestrated by a symphony of molecular regulatory mechanisms, highlighting the dynamic changes and critical roles of key effector molecules. Strategic disruption or inhibition of these molecular targets offers a tantalizing prospect for mitigating or even averting the onset of RCD, thereby limiting the extensive loss of cardiomyocytes and the progression of detrimental myocardial fibrosis. This review systematically summarizes the mechanisms underlying various forms of RCD, provides an in-depth exploration of the pathogenesis of AMI through the lens of RCD, and highlights a range of promising therapeutic targets that hold the potential to revolutionize the management of AMI.

Hesperidin alleviates ZBP1-drived PANoptosis induced by copper nanoparticles in immune organs of gallus

With the application of copper nanoparticles (nano-Cu) in livestock and poultry feed addition, their biotoxicity has been gradually recognized. Therefore, it has become an urgent problem to find the effective natural antagonists to reduce the toxicity of copper nanoparticles. Here, we found that hesperidin could alleviate nano-Cu-induced pathological injury in the immune organs of chickens via the histopathological examination of the spleen, thymus, and bursa of Fabricius. Additionally, the results of western blot showed that nano-Cu exposure activated ZBP1-mediated PANoptosis in immune organs, with evidenced by the significant up-regulation of ZBP1 signal molecule and PANoptosis-related proteins (apoptosis: Caspase-7, Caspase-3, Caspase-8; pyroptosis: Caspase-1, GSDMD, GSDME; necroptosis: RIPK1 and MLKL). Besides that, immunohistochemistry and immunofluorescence also showed that the staining intensity of Caspase-9 and Caspase-8 proteins was observably elevated in nano-Cu group compared to control group, and the staining intensity of the hesperidin mixed nano-copper group was markedly lower than that of the nano-Cu group. Meanwhile, hesperidin effectively attenuated the ZBP1 expression and PANoptosis under nano-Cu exposure. These findings suggested that excessive nano-Cu could cause ZBP1-drived PANoptosis in immune organs, while hesperidin could alleviate toxic damage induced by nano-Cu exposure.

Increased NFAT and NFκB signalling contribute to the hyperinflammatory phenotype in response to Aspergillus fumigatus in a mouse model of cystic fibrosis

Aspergillus fumigatus (Af) is a major mould pathogen found ubiquitously in the air. It commonly infects the airways of people with cystic fibrosis (CF) leading to Aspergillus bronchitis or allergic bronchopulmonary aspergillosis. Resident alveolar macrophages and recruited neutrophils are important first lines of defence for clearance of Af in the lung. However, their contribution to the inflammatory phenotype in CF during Af infection is not well understood. Here, utilising CFTR deficient mice we describe a hyperinflammatory phenotype in both acute and allergic murine models of pulmonary aspergillosis. We show that during aspergillosis, CFTR deficiency leads to increased alveolar macrophage death and persistent inflammation of the airways in CF, accompanied by impaired fungal control. Utilising CFTR deficient murine cells and primary human CF cells we show that at a cellular level there is increased activation of NFκB and NFAT in response to Af which, as in in vivo models, is associated with increased cell death and reduced fungal control. Taken together, these studies indicate that CFTR deficiency promotes increased activation of inflammatory pathways, the induction of macrophage cell death and reduced fungal control contributing to the hyper-inflammatory of pulmonary aspergillosis phenotypes in CF.

Nanomaterials-Induced PANoptosis: A Promising Anti-Tumor Strategy

Malignant tumors pose a significant threat to global public health. Promoting programmed cell death in cancer cells has become a critical strategy for cancer treatment. PANoptosis, a newly discovered form of regulated cell death, integrates key molecular components of pyroptosis, apoptosis, and necroptosis, activating these three death pathways simultaneously to achieve synergistic multi-mechanistic killing. PANoptosis significantly inhibits cancer cell growth and resistance and activates strong anti-tumor immune response, making tumor-specific induction of PANoptosis a potential cancer therapeutic strategy. Currently, cancer treatment research related to PANoptosis is focused mainly on the development of small molecules and cytokines. However, these approaches still face limitations in terms of metabolic stability and tumor specificity. The unique physicochemical properties and biological activities of nanomaterials hold significant promise for optimizing PANoptosis induction strategies. This review summarizes the concept and mechanisms of PANoptosis, highlights the latest applications of nanoagents in PANoptosis-based anti-cancer therapy, and discusses the challenges and future directions for clinical translation. It is hoped that this review will inspire further exploration and development of PANoptosis-based cancer treatments, providing new perspectives for researchers in the field.

ZBP1-mediated PANoptosis is a crucial lethal form in diverse keratinocyte death modalities in UVB-induced skin injury

UVB irradiation induces diverse modalities of regulatory cell death in keratinocytes. Recently, the pattern of coexistence of pyroptosis, apoptosis, and necroptosis has been termed PANoptosis; however, whether PANoptosis occurs in keratinocytes in UVB-induced skin injury remains unclear. We observed that the key molecules of GSDMD-mediated pyroptosis, apoptosis, and necroptosis, which are N-terminal GSDMD, cleaved caspase-3/PARP, and phosphorylated MLKL, respectively, were elevated in keratinocytes of UVB-challenged mice and human skin tissue. Through keratinocyte-specific gene knockout or using corresponding inhibitors, we found that individual inhibition of GSDMD-mediated pyroptosis, caspase-3-mediated apoptosis, or MLKL-mediated necroptosis did not reduce the overall level of keratinocyte death after UVB exposure, and that the other two pathways maintained the activation. However, when the PANoptosome sensor ZBP1 was knocked out, keratinocyte death was reduced and epidermal thickening was alleviated in UVB-challenged mice. In conclusion, our study demonstrated that UVB irradiation induces ZBP1-mediated PANoptosis in keratinocytes, which is a crucial lethal form in diverse keratinocyte death modalities in UVB-induced skin injury. The above findings provide a new insight on the complexity of regulated cell death modalities in keratinocytes exposed to UV irradiation.

ZBP1 senses Brucella abortus DNA triggering type I interferon signaling pathway and unfolded protein response activation

The innate immune system promptly detects and responds to invading pathogens, with a key role played by the recognition of bacterial-derived DNA through pattern recognition receptors. The Z-DNA binding protein 1 (ZBP1) functions as a DNA sensor inducing type I interferon (IFN) production, innate immune responses and also inflammatory cell death. ZBP1 interacts with cytosolic DNA via its DNA-binding domains, crucial for its activation. Brucella abortus is the etiologic agent of brucellosis in livestock and humans, leading to significant economic losses and public health impact. Despite other innate immune sensors that recognize B. abortus DNA, including Toll-like receptor 9 and the Stimulator of interferon genes (STING), here we evaluated the ZBP1 participation as a cytosolic receptor sensing Brucella infection. Using macrophages derived from ZBP1 knockout (KO) mice we demonstrated that ZBP1 partially contributes to IFN-β expression upon B. abortus infection or Brucella DNA transfection. The knockdown of STING by siRNA decreased the residual IFN-β signal elicited by B. abortus infection, demonstrating the presence of a redundant cytosolic DNA-sensing mechanism driving type I IFN production. Furthermore, ZBP1 is involved in type I IFN signaling inducing IRF-1 expression. Additionally, ZBP1 also contributes to Unfolded Protein Response (UPR) activation during infection. However, ZBP1 does not influence the production of proinflammatory mediators, inflammasome activation and it is dispensable to control bacterial infection in mice or replication in macrophages. This study highlights the complex interactions of Brucella components with innate immune receptors and identifies ZBP1 as a sensor for B. abortus DNA-induced IFN-β response.

Caspases in PANoptosis

Recent studies prove that the three well-established cell death pathways-pyroptosis, apoptosis, and necroptosis-are not isolated but rather engage in extensive crosstalk. PANoptosis, a newly identified pathway of inflammatory regulated cell death (RCD), integrates characteristics of apoptosis, pyroptosis, and necroptosis. Caspases are a family of conserved cysteine proteases that play critical roles in pyroptosis, apoptosis, and necroptosis. Similarly, caspases also play a role in PANoptosis. In this paper, we review the molecular mechanisms of these three RCDs and the crosstalk between them. We also delineate the discovery of PANoptosis and its association with disease. Furthermore, we discuss the caspase function in PANoptosis, mainly focusing on caspase-6 and caspase-8 molecules. This review describes the key molecules, especially caspases, in the context of PANoptosis research, aiming to provide a foundation for targeted interventions in PANoptosis-associated diseases.

Z-Nucleic Acid Sensing and Activation of ZBP1 in Cellular Physiology and Disease Pathogenesis

Z-nucleic acid binding protein 1 (ZBP1) is an innate immune sensor recognizing nucleic acids in Z-conformation. Upon Z-nucleic acid sensing, ZBP1 triggers innate immune activation, inflammation, and programmed cell death during viral infections, mice development, and inflammation-associated diseases. The Zα domains of ZBP1 sense Z-nucleic acids and promote RIP-homotypic interaction motif (RHIM)-dependent signaling complex assembly to mount cell death and inflammation. The studies on ZBP1 spurred an understanding of the role of Z-form RNA and DNA in cellular and physiological functions. In particular, short viral genomic segments, endogenous retroviral elements, and 3'UTR regions are likely sources of Z-RNAs that orchestrate ZBP1 functions. Recent seminal studies identify an intriguing association of ZBP1 with adenosine deaminase acting on RNA-1 (ADAR1), and cyclic GMP-AMP synthase (cGAS) in regulating aberrant nucleic acid sensing, chronic inflammation, and cancer. Thus, ZBP1 is an attractive target to aid the development of specific therapeutic regimes for disease biology. Here, we discuss the role of ZBP1 in Z-RNA sensing, activation of programmed cell death, and inflammation. Also, we discuss how ZBP1 coordinates intracellular perturbations in homeostasis, and Z-nucleic acid formation to regulate chronic diseases and cancer.

Korean Red ginseng enhances ZBP1-mediated cell death to suppress viral protein expression in host defense against Influenza A virus

Korean Red ginseng has emerged as a potent candidate in the fight against various viral infections, demonstrating significant efficacy both in vitro and in vivo, particularly against influenza A viruses. Despite substantial evidence of its antiviral properties, the detailed molecular mechanisms through which it reduces viral lethality remain insufficiently understood. Our investigations have highlighted the superior effectiveness of Korean Red ginseng against influenza viruses, outperforming its effects on numerous other viral strains. We aim to uncover the specific mechanisms by which Korean Red ginseng exerts its antiviral effects, focusing on influenza A viruses. Our prior studies have identified the role of Z-DNA-binding protein 1 (ZBP1), a signaling complex involved in inducing programmed cell death in response to influenza virus infection. Given the critical role of ZBP1 as a sensor for viral nucleic acid, we hypothesize that Korean Red ginseng may modulate the ZBP1-derived cell death pathway. This interaction is anticipated to enhance cell death while concurrently suppressing viral protein expression, offering novel insights into the antiviral mechanism of Korean Red ginseng against influenza A viruses.

An apoptosis-inducing factor controls programmed cell death and laccase expression during fungal interactions

Apoptotic-like programmed cell death (PCD) is one of the main strategies for fungi to resist environmental stresses and maintain homeostasis. The apoptosis-inducing factor (AIF) has been shown in different fungi to trigger PCD through upregulating reactive oxygen species (ROS). This study identified a mitochondrial localized AIF homolog, CcAIF1, from Coprinopsis cinerea monokaryon Okayama 7. Heterologous overexpression of CcAIF1 in Saccharomyces cerevisiae caused apoptotic-like PCD of the yeast cells. Ccaif1 was increased in transcription when C. cinerea interacted with Gongronella sp. w5, accompanied by typical apoptotic-like PCD in C. cinerea, including phosphatidylserine externalization and DNA fragmentation. Decreased mycelial ROS levels were observed in Ccaif1 silenced C. cinerea transformants during cocultivation, as well as reduction of the apoptotic levels, mycelial growth, and asexual sporulation. By comparison, Ccaif1 overexpression led to the opposite phenotypes. Moreover, the transcription and expression levels of laccase Lcc9 decreased by Ccaif1 silencing but increased firmly in Ccaif1 overexpression C. cinerea transformants in coculture. Thus, in conjunction with our previous report that intracellular ROS act as signal molecules to stimulate defense responses, we conclude that CcAIF1 is a regulator of ROS to promote apoptotic-like PCD and laccase expression in fungal-fungal interactions. In an axenic culture of C. cinerea, CcAIF1 overexpression and H2O2 stimulation together increased laccase secretion with multiplied production yield. The expression of two other normally silent isozymes, Lcc8 and Lcc13, was unexpectedly triggered along with Lcc9. KEY POINTS: • Mitochondrial CcAIF1 induces PCD during fungal-fungal interactions • CcAIF1 is a regulator of ROS to trigger the expression of Lcc9 for defense • CcAIF1 overexpression and H2O2 stimulation dramatically increase laccase production.

The Potential Therapeutic Prospect of PANoptosis in Heart Failure

Heart failure (HF) represents a serious manifestation or advanced stage of various cardiac diseases. HF continues to impose a significant global disease burden, characterized by high rates of hospitalization and fatality. Furthermore, the pathogenesis and pathophysiological processes underlying HF remain incompletely understood, complicating its prevention and treatment strategies. One significant pathophysiological mechanism associated with HF is the systemic inflammatory response. PANoptosis, a novel mode of inflammatory cell death, has been extensively studied in the context of infectious diseases, neurodegenerative disorders, cancers, and other inflammatory conditions. Recent investigations have revealed that PANoptosis-related genes are markedly dysregulated in HF specimens. Consequently, the PANoptosis-mediated inflammatory response may represent a potential mechanism and therapeutic target for HF. This paper conducts a comprehensive analysis of the molecular pathways that drive PANoptosis. We discuss its role and potential therapeutic targets in HF, thereby providing valuable insights for clinical treatment and the development of novel therapies.

Trimethylamine Induced Chronic Kidney Injury by Activating the ZBP1-NLRP3 Inflammasome Pathway

Trimethylamine N-oxide (TMAO), a bioactive metabolite of gut microbes, plays a pivotal role in the pathogenesis of kidney diseases by activating programmed cell death (PCD) pathways. However, whether trimethylamine (TMA) contributes to chronic kidney injury and which kind of PCD is involved in TMA-induced chronic kidney injury has not been previously evaluated. To observe the effect of TMA, male C57BL/6J mice were randomly divided into two groups: the Control group and the TMA group. The mice in the TMA group were intraperitoneally injected with 100 micromol/kg/day TMA for three months, whereas the mice in the Control group were injected with normal saline for the same period. After three months, plasma creatinine and blood urea nitrogen levels, indicators of kidney function, increased significantly in the TMA group as compared with those in the Control group. Furthermore, Masson staining assay showed that TMA treatment led to a larger area of fibrosis than the Control group. TMA treatment did not change the Bax/Bcl-2 ratio, RIP1, RIP3 and MLKL phosphorylation, or iron and malondialdehyde levels in kidney tissues, indicating that apoptosis, ferroptosis and necroptosis were not involved in TMA-induced chronic kidney injury. However, compared with the Control group, TMA treatment significantly upregulated NLRP3, Caspase-1, IL-1beta, cleaved-Caspase 8, Caspase-8, and ZBP1 protein expression in kidney tissues. These results indicated that the ZBP1-NLRP3 inflammasome pathway was involved in TMA-induced chronic kidney injury. In conclusion, our studies revealed that the ZBP1-NLRP3 inflammasome may take part in the progression of TMA induced chronic kidney injury.

Cuproptosis, ferroptosis and PANoptosis in tumor immune microenvironment remodeling and immunotherapy: culprits or new hope

Normal life requires cell division to produce new cells, but cell death is necessary to maintain balance. Dysregulation of cell death can lead to the survival and proliferation of abnormal cells, promoting tumor development. Unlike apoptosis, necrosis, and autophagy, the newly recognized forms of regulated cell death (RCD) cuproptosis, ferroptosis, and PANoptosis provide novel therapeutic strategies for tumor treatment. Increasing research indicates that the death of tumor and immune cells mediated by these newly discovered forms of cell death can regulate the tumor microenvironment (TME) and influence the effectiveness of tumor immunotherapy. This review primarily elucidates the molecular mechanisms of cuproptosis, ferroptosis, and PANoptosis and their complex effects on tumor cells and the TME. This review also summarizes the exploration of nanoparticle applications in tumor therapy based on in vivo and in vitro evidence derived from the induction or inhibition of these new RCD pathways.

PANoptosis opens new treatment options for allergic bronchopulmonary aspergillosis

Background

Allergic bronchopulmonary aspergillosis (ABPA) is a rare airway disorder primarily affecting patients with asthma and cystic fibrosis. Persistent airway inflammation brought on by Aspergillus fumigatus exacerbates the underlying condition and can cause significant respiratory damage. Treatments center on reducing inflammation with the use of corticosteroids and antifungals. PANoptosis is a new concept in the field of cell death and inflammation that posits the existence of cross talk and a master control system for the 3 programmed cell death (PCD) pathways, namely, apoptosis, pyroptosis, and necroptosis. This concept has revolutionized the understanding of PCD and opened new avenues for its exploration. Studies show that Aspergillus is one of the pathogens that is capable of activating PANoptosis via the Z-DNA binding protein 1 (ZBP1) pathway and plays an active role in the inflammation caused by this organism.

Objective

This article explores the nature of inflammation in ABPA and ways in which PCD could lead to novel treatment options.

Method

PubMed was used to review the literature surrounding Aspergillus infection-related inflammation and PANoptosis.

Results

There is evidence that apoptosis and pyroptosis protect against Aspergillus-induced inflammation, whereas necroptosis promotes inflammation.

Conclusion

Experimental medications, in particular, necroptosis inhibitors such as necrosulfonamide and necrostatin-1, should be studied for use in the treatment of ABPA.

Characterizing PANoptosis gene signature in prognosis and chemosensitivity of colorectal cancer

Background

PANoptosis is a cell death pathway involved in pyroptosis, apoptosis and necrosis, and plays a key role in the development of malignant tumors. However, the molecular signature of PANoptosis in colorectal cancer (CRC) prognosis has not been thoroughly explored. The present study aimed to develop a novel prognostic model based on PANoptosis-related genes in CRC.

Methods

We initially included transcriptome data of 404 CRC samples from The Cancer Genome Atlas (TCGA) cohort and identified differentially expressed genes related to PANoptosis. We then employed Cox, least absolute shrinkage and selection operator (LASSO) regression, and Random Forest methods to determine the prognostic value and constructed a PANoptosis prognostic model, followed by the validation on both internal (TCGA) and external datasets [Nanjing Colorectal Cancer (NJCRC) and Gene Expression Omnibus (GEO), n=635]. We performed immune infiltration analysis and gene set enrichment analysis to reveal biological processes and pathways against differential risk score. Ultimately, we carried out drug sensitivity analysis to predict the response of CRC patients to diverse treatment strategies.

Results

We constructed a predictive model based on four PANoptosis-related genes (TIMP1, CDKN2A, CAMK2B, and TLR3), with a high performance [area under the curve (AUC)1-year =0.702, AUC3-year =0.725, AUC5-year =0.668] and being an independent prognostic factor in predicting the prognosis of CRC patients. Notably, colorectal tumor with high PANoptosis risk score performed higher levels of macrophage infiltration and immune scores, but a greater reduction of Tumor Microenvironment Score (TMEscore) and DNA replication. Particularly, patients in high-risk group exhibited higher sensitivity to fluorouracil, oxaliplatin and lapatinib compared to the low-risk group.

Conclusions

This study highlights the prognostic potential of PANoptosis-related features in CRC, demonstrating their role as key biomarkers significantly associated with patient survival and aiding in the identification of high-risk patients, thereby advancing immunotherapy approaches.

Sensing of endogenous retroviruses-derived RNA by ZBP1 triggers PANoptosis in DNA damage and contributes to toxic side effects of chemotherapy

Excessive DNA damage triggers various types of programmed cell death (PCD), yet the regulatory mechanism of DNA damage-induced cell death is not fully understood. Here, we report that PANoptosis, a coordinated PCD pathway, including pyroptosis, apoptosis and necroptosis, is activated by DNA damage. The Z-DNA binding protein 1 (ZBP1) is the apical sensor of PANoptosis and essential for PANoptosome assembly in response to DNA damage. We find endogenous retroviruses (ERVs) are activated by DNA damage and act as ligands for ZBP1 to trigger PANoptosis. By using ZBP1 knock-out and knock-in mice disrupting ZBP1 nucleic acid-binding activity, we demonstrate that ZBP1-mediated PANoptosis contributes to the toxic effects of chemotherapeutic drugs, which is dependent on ZBP1 nucleic acid-binding activity. We found that ZBP1 expression is downregulated in tumor tissue. Furthermore, in colorectal cancer patients, dsRNA is induced by chemotherapy and sensed by ZBP1 in normal colonic tissues, suggesting ZBP1-mediated PANoptosis is activated by chemotherapy in normal tissues. Our findings indicate that ZBP1-mediated PANoptosis is activated by DNA damage and contributes to the toxic side effects of DNA-damage-based chemotherapy. These data suggest that ZBP1 could be a promising therapeutic target to alleviate chemotherapy-related side effects.

Cell death pathways in dry eye disease: Insights into ocular surface inflammation

Dry eye disease (DED) is increasingly prevalent, with inflammation playing a crucial role in its pathogenesis. Severe cases of DED result in significant ocular discomfort and visual impairment due to damage and loss of ocular surface epithelial cells. The precise mechanisms underlying the loss of these epithelial cells remain a subject of ongoing research and debate. Programmed cell death (PCD) mechanisms, including pyroptosis, apoptosis, and necroptosis, are known to be critical in maintaining ocular surface homeostasis and responding to stressors in DED. The concept of PANoptosis, which integrates elements of various PCD pathways, has been implicated in the development of numerous systemic diseases, including infections, cancer, neurodegenerative, and inflammatory conditions. It also provides novel insights into the inflammatory processes underlying DED. This review highlights the crosstalk of PCD pathways in DED, particularly the significance of PANoptosis in ocular inflammation and its potential as a therapeutic target for more effective interventions.

Overview of pyroptosis mechanism and in-depth analysis of cardiomyocyte pyroptosis mediated by NF-κB pathway in heart failure

The pyroptosis of cardiomyocytes has become an essential topic in heart failure research. The abnormal accumulation of these biological factors, including angiotensin II, advanced glycation end products, and various growth factors (such as connective tissue growth factor, vascular endothelial growth factor, transforming growth factor beta, among others), activates the nuclear factor-κB (NF-κB) signaling pathway in cardiovascular diseases, ultimately leading to pyroptosis of cardiomyocytes. Therefore, exploring the underlying molecular biological mechanisms is essential for developing novel drugs and therapeutic strategies. However, our current understanding of the precise regulatory mechanism of this complex signaling pathway in cardiomyocyte pyroptosis is still limited. Given this, this study reviews the milestone discoveries in the field of pyroptosis research since 1986, analyzes in detail the similarities, differences, and interactions between pyroptosis and other cell death modes (such as apoptosis, necroptosis, autophagy, and ferroptosis), and explores the deep connection between pyroptosis and heart failure. At the same time, it depicts in detail the complete pathway of the activation, transmission, and eventual cardiomyocyte pyroptosis of the NF-κB signaling pathway in the process of heart failure. In addition, the study also systematically summarizes various therapeutic approaches that can inhibit NF-κB to reduce cardiomyocyte pyroptosis, including drugs, natural compounds, small molecule inhibitors, gene editing, and other cutting-edge technologies, aiming to provide solid scientific support and new research perspectives for the prevention and treatment of heart failure.

Determining the Feasibility of a Cadmium Exposure Model to Activate the Inflammatory Arm of PANoptosis in Murine Monocytes

A prevalence of cigarette smoking can cause the accumulation of cadmium (Cd2+) in the lungs, kidneys, and blood. The effects of exposure can cause multiple chronic disease types to emerge in the affected organ systems. The only moderately effective therapeutic option is chelation therapy; the health risks associated with this therapy have caused much criticism. The disease types associated with Cd2+ toxicity have inflammatory components and greatly impact innate immunity. These factors are affected at the cellular level and cause pathways like apoptosis, pyroptosis, and necroptosis. A development in understanding these pathways stipulates that these three pathways act as one complex of pathways, known together as PANoptosis. The inflammatory mechanisms of PANoptosis are particularly interesting in Cd2+ toxicity due to its inflammatory effects. Proteins in the gasdermin family act to release inflammatory cytokines, like interleukin-1β, into the extracellular environment. Cytokines cause inflammatory disease pathologies like fibrosis and cancer. RAW 264.7 monocytes are key in the murine immune system and provide an excellent model to investigate Cd2+ toxicity. Exposure of 0-15 µM CdCl2 was sufficient to increase expression of cleaved gasdermin D (GSDMD) and gasdermin E (GSDME) in this cell type. Cd2+ also exhibits a dose-dependent cytotoxicity in this cell type.

PANoptosis: a new insight for oral diseases

PANoptosis, a burgeoning area of research, is a unique type of programmed cell death typified by pyroptosis, apoptosis, and necroptosis, yet it defies singular classification by any one mode of death. The assembly and activation of PANoptosomes are pivotal processes in PANoptosis, with several PANoptosomes already identified. Linkages between PANoptosis and the pathophysiology of various systemic illnesses are established, with increasing recognition of its association with oral ailments. This paper aims to deepen understanding by conducting a comprehensive analysis of the molecular pathways driving PANoptosis and exploring its potential implications in oral diseases.

Arsenic induces hepatotoxicity in chickens via PANoptosis pathway

Environmental pollution caused by arsenic or its compounds is called arsenic pollution. Arsenic pollution mainly comes from people's mining and smelting of arsenic compounds. In addition, the widespread use of arsenic compounds, such as the use and production of arsenic-containing pesticides, is also a source of arsenic contamination. Arsenic contamination leads to an increased risk of arsenic exposure, and the multi-organ toxicity induced by arsenic exposure is a global health problem. As a non-mammalian vertebrate with high nutrient levels, chickens readily absorb and accumulate arsenic from their food. Relevant studies have shown that arsenic exposure induces hepatotoxicity in chickens, and there has been a steady stream of research into the specific mechanisms involved. PANoptosis, a newly discovered and unique mode of programmed cell death (PCD) characterized by both apoptosis, cellular pyroptosis, and necroptosis. There are no studies to indicate whether chicken liver toxicity due to arsenic is associated with PANoptosis. Therefore, we established chicken animal models and chicken primary hepatocyte models exposed to different arsenic concentrations to dissect the role and mechanism of PANoptosis in arsenic exposure-induced hepatotoxicity in chickens. Our histopathological results showed that arsenic treatment caused dose-dependent damage to chicken liver structure. Meanwhile, different doses of arsenic treatment groups caused significant up-regulation of the protein level of ZBP1, a key factor of PANoptosis. And then consequently triggered the abnormal gene and protein expression levels of apoptosis-associated factors (Caspase-8, Caspase-7, Caspase-3), cellular pyroptosis-associated factors (NLRP3, ASC, GSDMD) and necroptosis-associated factors (RIPK1, RIPK3, MLKL). In conclusion, our study revealed that PANoptosis is involved in arsenic-induced chicken hepatotoxicity. Our findings provide a new perspective on the pathogenesis of arsenic exposure-induced hepatotoxicity in chickens.

Innate immune sensing of cell death in disease and therapeutics

Innate immunity, cell death and inflammation underpin many aspects of health and disease. Upon sensing pathogens, pathogen-associated molecular patterns or damage-associated molecular patterns, the innate immune system activates lytic, inflammatory cell death, such as pyroptosis and PANoptosis. These genetically defined, regulated cell death pathways not only contribute to the host defence against infectious disease, but also promote pathological manifestations leading to cancer and inflammatory diseases. Our understanding of the underlying mechanisms has grown rapidly in recent years. However, how dying cells, cell corpses and their liberated cytokines, chemokines and inflammatory signalling molecules are further sensed by innate immune cells, and their contribution to further amplify inflammation, trigger antigen presentation and activate adaptive immunity, is less clear. Here, we discuss how pattern-recognition and PANoptosome sensors in innate immune cells recognize and respond to cell-death signatures. We also highlight molecular targets of the innate immune response for potential therapeutic development.

Molecular characterization analysis of PANoptosis-related genes in colorectal cancer based on bioinformatic analysis

Colorectal cancer (CRC) ranks as the third most prevalent cancer globally and stands as the second principal contributor to cancer-related fatalities. Recently, emerging research has emphasized the role of pan apoptosis (PANoptosis) in tumor development and anti-tumor therapy. In the course of this investigation, we meticulously identified and conducted a correlation analysis between differentially expressed genes associated with PANoptosis in CRC (CPAN_DEGs) and the proportion of immune cells. Subsequently, we formulated a prognostic score based on the CPAN_DEGs. Further our analysis revealed a noteworthy reduction in UNC5D mRNA expression within HCT116, HT29 and SW480 cells, as validated by qRT-PCR assay. Furthermore, scrutinizing the TCGA database unveiled a distinctive trend wherein individuals with the low UNC5D expression exhibited significantly reduced overall survival compared to their counterparts with the high UNC5D levels. The drug susceptibility analysis of UNC5D was further performed, which showed that UNC5D was corassociated with the sensitivity of CRC to 6-Thioguanine. The outcomes of our investigation underscore the mechanisms by which PANoptosis influences immune dysregulation as well as prognostic outcome in CRC.

Analysis of PANoptosis-related ceRNA network reveals lncRNA MIR17HG involved in osteogenic differentiation inhibition impaired by tumor necrosis factor-α

BACKGROUND

Inflammatory cytokines such as Interleukin 1β(IL1β), IL6,Tumor Necrosis Factor-α (TNF-α) can inhibit osteoblast differentiation and induce osteoblast apoptosis. PANoptosis, a newly identified type of programmed cell death (PCD), may be influenced by long noncoding RNA (lncRNAs) which play important roles in regulating inflammation. However, the potential role of lncRNAs in inflammation and PANoptosis during osteogenic differentiation remains unclear. This study aimed to investigate the regulatory functions of lncRNAs in inflammation and apoptosis during osteogenic differentiation.

METHODS AND RESULTS

High-throughput sequencing was used to identify differentially expressed genes involved in osteoblast differentiation under inflammatory conditions. Two lncRNAs associated with inflammation and PANoptosis during osteogenic differentiation were identified from sequencing data and Gene Expression Omnibus (GEO) databases. Their functionalities were analyzed using diverse bioinformatics methodologies, resulting in the construction of the lncRNA-miRNA-mRNA network. Among these, lncRNA (MIR17HG) showed a high correlation with PANoptosis. Bibliometric methods were employed to collect literature data on PANoptosis, and its components were inferred. PCR and Western Blotting experiments confirmed that lncRNA MIR17HG is related to PANoptosis in osteoblasts during inflammation.

CONCLUSIONS

Our data suggest that TNF-α-induced inhibition of osteogenic differentiation and PANoptosis in MC3T3-E1 osteoblasts is associated with MIR17HG. These findings highlight the critical role of MIR17HG in the interplay between inflammation, PANoptosis, and osteogenic differentiation, suggesting potential therapeutic targets for conditions involving impaired bone formation and inflammatory responses.

The mechanosensitive Piezo1 channel exacerbates myocardial ischaemia/reperfusion injury by activating caspase-8-mediated PANoptosis

PANoptosis is a newly discovered type of cell death characterized by pyroptosis, apoptosis and/or necroptosis and has been implicated in the inflammatory response. Piezo1 is a mechanosensitive ion channel that plays important roles in physiological development and various diseases. However, whether cardiomyocytes undergo PANoptosis during myocardial ischaemia/reperfusion (I/R) injury and the role of Piezo1 in this process remain largely unexplored. In this study, our results revealed that the expression levels of the main components of the PANoptosome, including caspase-8, caspase-3, NLRP3, caspase-1, GSDMD, RIPK1, RIPK3 and MLKL, were significantly upregulated in I/R heart tissues over time, indicating the occurrence of PANoptosis in I/R hearts. Accordingly, Piezo1 expression was significantly upregulated in I/R-injured hearts and hypoxia/reoxygenation (H/R)-treated cardiomyocytes. In contrast, pharmacological inhibition of Piezo1 by the inhibitor GsMTx4 in mice markedly attenuated the I/R-mediated decline in cardiac contractile function and increases in infarct size, apoptosis, oxidative stress and inflammation accompanied by the inhibition of PANoptosis-related mediators in I/R hearts. Consistently, the effects of Piezo1 on calcium influx and PANoptosis were further verified by GsMTx4 and Piezo1 activator Yoda1 in H/R-treated cardiomyocytes in vitro. Moreover, caspase-8 rather than calcium influx was required for H/R-induced PANoptosis in vitro. Mechanistically, Piezo1 interacts with caspase-8, a key initial activator of the PANoptosome complex, which subsequently activates cardiomyocyte PANoptosis, leading to cardiac dysfunction. In summary, these data suggest that Piezo1 is a new cardiac mechanosensor that promotes cardiac I/R injury possibly through the caspase-8-mediated activation of cardiomyocyte PANoptosis and highlight that Piezo1 may represent a new target for treating ischaemic heart disease.

Defining PANoptosis: Biochemical and Mechanistic Evaluation of Innate Immune Cell Death Activation

The innate immune system is the first line of host defense. Innate immune activation utilizes pattern recognition receptors to detect pathogens, pathogen-associated and damage-associated molecular patterns (PAMPs and DAMPs), and homeostatic alterations and drives inflammatory signaling pathways and regulated cell death. Cell death activation is critical to eliminate pathogens and aberrant or damaged cells, while excess activation can be linked to inflammation, tissue damage, and disease. Therefore, there is increasing interest in studying cell death mechanisms to understand the underlying biology and identify therapeutic strategies. However, there are significant technical challenges, as many cell death pathways share key molecules with each other, and genetic models where these cell death molecules are deleted remain the gold standard for evaluation. Furthermore, extensive crosstalk has been identified between the cell death pathways pyroptosis, apoptosis, necroptosis, and the more recently characterized PANoptosis, which is defined as a prominent, unique innate immune, lytic, and inflammatory cell death pathway initiated by innate immune sensors and driven by caspases and RIPKs through PANoptosomes. PANoptosomes are multi-protein complexes assembled by innate immune sensor(s) in response to pathogens, PAMPs, DAMPs, cytokines, and homeostatic changes that drive PANoptosis. In this article, we provide methods for molecularly defining distinct cell death pathways, including PANoptosis, using both genetic and chemical approaches through western blot, LDH assay, and microscopy readouts. This procedure allows for the assessment of cell death on the cell population and single-cell levels even without access to genetic models. Having this comprehensive workflow that is more accessible to all labs will improve our ability as a scientific community to accelerate discovery. Using these protocols will help identify new innate immune sensors that drive PANoptosis and define the molecular mechanisms and regulators involved to establish new targets for clinical translation. © 2024 The Author(s). Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Induction and quantification of cell death using live cell imaging Alternate Protocol 1: Quantification of cell death using LDH Alternate Protocol 2: Assessment of cell death complexes in single cells using immunofluorescence staining Basic Protocol 2: Analysis of cell death mechanisms by immunoblots (western blots).

Implications of inflammatory cell death-PANoptosis in health and disease

Regulated cell death (RCD) pathways, such as pyroptosis, apoptosis, and necroptosis, are essential for maintaining the body's balance, defending against pathogens, and eliminating abnormal cells that could lead to diseases like cancer. Although these pathways operate through distinct mechanisms, recent genetic and pharmacological studies have shown that they can interact and influence each other. The concept of "PANoptosis" has emerged, highlighting the interplay between pyroptosis, apoptosis, and necroptosis, especially during cellular responses to infections. This article provides a concise overview of PANoptosis and its molecular mechanisms, exploring its implications in various diseases. The review focuses on the extensive interactions among different RCD pathways, emphasizing the role of PANoptosis in infections, cytokine storms, inflammatory diseases, and cancer. Understanding PANoptosis is crucial for developing novel treatments for conditions involving infections, sterile inflammations, and cancer.

AIM2 enhances Candida albicans infection through promoting macrophage apoptosis via AKT signaling

Candida albicans is among the most prevalent invasive fungal pathogens for immunocompromised individuals and novel therapeutic approaches that involve immune response modulation are imperative. Absent in melanoma 2 (AIM2), a pattern recognition receptor for DNA sensing, is well recognized for its involvement in inflammasome formation and its crucial role in safeguarding the host against various pathogenic infections. However, the role of AIM2 in host defense against C. albicans infection remains uncertain. This study reveals that the gene expression of AIM2 is induced in human and mouse innate immune cells or tissues after C. albicans infection. Furthermore, compared to their wild-type (WT) counterparts, Aim2-/- mice surprisingly exhibit resistance to C. albicans infection, along with reduced inflammation in the kidneys post-infection. The resistance of Aim2-/- mice to C. albicans infection is not reliant on inflammasome or type I interferon production. Instead, Aim2-/- mice display lower levels of apoptosis in kidney tissues following infection than WT mice. The deficiency of AIM2 in macrophages, but not in dendritic cells, results in a phenocopy of the resistance observed in Aim2-/- mice against C. albican infection. The treatment of Clodronate Liposome, a reagent that depletes macrophages, also shows the critical role of macrophages in host defense against C. albican infection in Aim2-/- mice. Furthermore, the reduction in apoptosis is observed in Aim2-/- mouse macrophages following infection or treatment of DNA from C. albicans in comparison with controls. Additionally, higher levels of AKT activation are observed in Aim2-/- mice, and treatment with an AKT inhibitor reverses the host resistance to C. albicans infection. The findings collectively demonstrate that AIM2 exerts a negative regulatory effect on AKT activation and enhances macrophage apoptosis, ultimately compromising host defense against C. albicans infection. This suggests that AIM2 and AKT may represent promising therapeutic targets for the management of fungal infections.

IRF7 Exacerbates Candida albicans Infection by Compromising CD209-Mediated Phagocytosis and Autophagy-Mediated Killing in Macrophages

IFN regulatory factor 7 (IRF7) exerts anti-infective effects by promoting the production of IFNs in various bacterial and viral infections, but its role in highly morbid and fatal Candida albicans infections is unknown. We unexpectedly found that Irf7 gene expression levels were significantly upregulated in tissues or cells after C. albicans infection in humans and mice and that IRF7 actually exacerbates C. albicans infection in mice independent of its classical function in inducing IFNs production. Compared to controls, Irf7-/- mice showed stronger phagocytosis of fungus, upregulation of C-type lectin receptor CD209 expression, and enhanced P53-AMPK-mTOR-mediated autophagic signaling in macrophages after C. albicans infection. The administration of the CD209-neutralizing Ab significantly hindered the phagocytosis of Irf7-/- mouse macrophages, whereas the inhibition of p53 or autophagy impaired the killing function of these macrophages. Thus, IRF7 exacerbates C. albicans infection by compromising the phagocytosis and killing capacity of macrophages via regulating CD209 expression and p53-AMPK-mTOR-mediated autophagy, respectively. This finding reveals a novel function of IRF7 independent of its canonical IFNs production and its unexpected role in enhancing fungal infections, thus providing more specific and effective targets for antifungal therapy.

Z-DNA binding protein 1 orchestrates innate immunity and inflammatory cell death

Innate immunity is not only the first line of host defense against microbial infections but is also crucial for the host responses against a variety of noxious stimuli. Z-DNA binding protein 1 (ZBP1) is a cytosolic nucleic acid sensor that can induce inflammatory cell death in both immune and nonimmune cells upon sensing of incursive virus-derived Z-form nucleic acids and self-nucleic acids via its Zα domain. Mechanistically, aberrantly expressed or activated ZBP1 induced by pathogens or noxious stimuli enables recruitment of TANK binding kinase 1 (TBK1), interferon regulatory factor 3 (IRF3), receptor-interacting serine/threonine-protein kinase 1 (RIPK1) and RIPK3 to drive type I interferon (IFN-I) responses and activation of nuclear factor kappa B (NF-κB) signaling. Meanwhile, ZBP1 promotes the assembly of ZBP1- and absent in melanoma 2 (AIM2)-PANoptosome, which ultimately triggers PANoptosis through caspase 3-mediated apoptosis, mixed lineage kinase domain like pseudokinase (MLKL)-mediated necroptosis, and gasdermin D (GSDMD)-mediated pyroptosis. In response to damaged mitochondrial DNA, ZBP1 can interact with cyclic GMP-AMP synthase to augment IFN-I responses but inhibits toll like receptor 9-mediated inflammatory responses. This review summarizes the structure and expression pattern of ZBP1, discusses its roles in human diseases through immune-dependent (e.g., the production of IFN-I and pro-inflammatory cytokines) and -independent (e.g., the activation of cell death) functions, and highlights the attractive prospect of manipulating ZBP1 as a promising therapeutic target in diseases.

Targeting regulated cell death (RCD) in hematological malignancies: Recent advances and therapeutic potential

Regulated cell death (RCD) is a form of cell death that can be regulated by numerous biomacromolecules. Accumulating evidence suggests that dysregulated expression and altered localization of related proteins in RCD promote the development of cancer. Targeting subroutines of RCD with pharmacological small-molecule compounds is becoming a promising therapeutic avenue for anti-tumor treatment, especially in hematological malignancies. Herein, we summarize the aberrant mechanisms of apoptosis, necroptosis, pyroptosis, PANoptosis, and ferroptosis in hematological malignancies. In particular, we focus on the relationship between cell death and tumorigenesis, anti-tumor immunotherapy, and drug resistance in hematological malignancies. Furthermore, we discuss the emerging therapeutic strategies targeting different RCD subroutines. This review aims to summarize the significance and potential mechanisms of RCD in hematological malignancies, along with the development and utilization of pertinent therapeutic strategies.

Innate Immunity in Protection and Pathogenesis During Coronavirus Infections and COVID-19

The COVID-19 pandemic was caused by the recently emerged β-coronavirus SARS-CoV-2. SARS-CoV-2 has had a catastrophic impact, resulting in nearly 7 million fatalities worldwide to date. The innate immune system is the first line of defense against infections, including the detection and response to SARS-CoV-2. Here, we discuss the innate immune mechanisms that sense coronaviruses, with a focus on SARS-CoV-2 infection and how these protective responses can become detrimental in severe cases of COVID-19, contributing to cytokine storm, inflammation, long-COVID, and other complications. We also highlight the complex cross talk among cytokines and the cellular components of the innate immune system, which can aid in viral clearance but also contribute to inflammatory cell death, cytokine storm, and organ damage in severe COVID-19 pathogenesis. Furthermore, we discuss how SARS-CoV-2 evades key protective innate immune mechanisms to enhance its virulence and pathogenicity, as well as how innate immunity can be therapeutically targeted as part of the vaccination and treatment strategy. Overall, we highlight how a comprehensive understanding of innate immune mechanisms has been crucial in the fight against SARS-CoV-2 infections and the development of novel host-directed immunotherapeutic strategies for various diseases.

Mitochondrial DNA release and sensing in innate immune responses

Mitochondria are pleiotropic organelles central to an array of cellular pathways including metabolism, signal transduction, and programmed cell death. Mitochondria are also key drivers of mammalian immune responses, functioning as scaffolds for innate immune signaling, governing metabolic switches required for immune cell activation, and releasing agonists that promote inflammation. Mitochondrial DNA (mtDNA) is a potent immunostimulatory agonist, triggering pro-inflammatory and type I interferon responses in a host of mammalian cell types. Here we review recent advances in how mtDNA is detected by nucleic acid sensors of the innate immune system upon release into the cytoplasm and extracellular space. We also discuss how the interplay between mtDNA release and sensing impacts cellular innate immune endpoints relevant to health and disease.

The NLR family of innate immune and cell death sensors

Nucleotide-binding oligomerization domain (NOD)-like receptors, also known as nucleotide-binding leucine-rich repeat receptors (NLRs), are a family of cytosolic pattern recognition receptors that detect a wide variety of pathogenic and sterile triggers. Activation of specific NLRs initiates pro- or anti-inflammatory signaling cascades and the formation of inflammasomes-multi-protein complexes that induce caspase-1 activation to drive inflammatory cytokine maturation and lytic cell death, pyroptosis. Certain NLRs and inflammasomes act as integral components of larger cell death complexes-PANoptosomes-driving another form of lytic cell death, PANoptosis. Here, we review the current understanding of the evolution, structure, and function of NLRs in health and disease. We discuss the concept of NLR networks and their roles in driving cell death and immunity. An improved mechanistic understanding of NLRs may provide therapeutic strategies applicable across infectious and inflammatory diseases and in cancer.

Inflammasome diversity: exploring novel frontiers in the innate immune response

Pathogens elicit complex mammalian immune responses by activating multiple sensors within inflammasomes, which recognize diverse pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). This simultaneous activation induces the formation of protein complexes referred to as multiple inflammasomes, that orchestrate a spectrum of programmed cell death pathways, including pyroptosis, apoptosis, and necroptosis. This concept is crucial for comprehending the complexity of the innate immune system's response to diverse pathogens and its implications for various diseases. Novel contributions here include emphasizing simultaneous sensor activation by pathogens, proposing the existence of multiple inflammasome complexes, and advocating for further exploration of their structural basis. Understanding these mechanisms may offer insights into disease pathogenesis, paving the way for potential therapeutic interventions targeting inflammasome-mediated immune responses.

PANoptosis, an indicator of COVID-19 severity and outcomes

Coronavirus disease 2019 (COVID-19) has been wreaking havoc for 3 years. PANoptosis, a distinct and physiologically relevant inflammatory programmed cell death, perpetuates cytokine storm and multi-organ injuries in COVID-19. Although PANoptosis performs indispensable roles in host defense, further investigation is needed to elucidate the exact processes through which PANoptosis modulates immunological responses and prognosis in COVID-19. This study conducted a bioinformatics analysis of online single-cell RNA sequence (scRNA-seq) and bulk RNA-seq datasets to explore the potential of PANoptosis as an indicator of COVID-19 severity. The degree of PANoptosis in bronchoalveolar lavage fluid (BALF) and peripheral blood mononuclear cells (PBMC) indicated the severity of COVID-19. Single-cell transcriptomics identified pro-inflammatory monocytes as one of the primary sites of PANoptosis in COVID-19. The study subsequently demonstrated the immune and metabolic characteristics of this group of pro-inflammatory monocytes. In addition, the analysis illustrated that dexamethasone was likely to alleviate inflammation in COVID-19 by mitigating PANoptosis. Finally, the study showed that the PANoptosis-related genes could predict the intensive care unit admission (ICU) and outcomes of COVID-19 patients who are hospitalized.

Metformin switches cell death modes to soothe the apical periodontitis via ZBP1

Apical periodontitis (AP) is a disease caused by pathogenic microorganisms and featured with the degradation of periapical hard tissue. Our recent research showed the crucial role of Z-DNA binding protein 1 (ZBP1)-mediated necroptosis and apoptosis in the pathogenesis of AP. However, the specific regulatory mechanisms of ZBP1 in AP are not fully elucidated. It was found that metformin has a regulatory role in cell necroptosis and apoptosis. But whether and how metformin regulates necroptosis and apoptosis through the ZBP1 in the context of AP remains unknown. This study provided evidence that lipopolysaccharide (LPS) promotes the synthesis of left-handed Z-nucleic acids (Z-NA), which in turn activates ZBP1. Knockout of Zbp1 by CRISPR/Cas9 technology significantly reduced LPS-induced necroptosis and apoptosis in vitro. By using Zbp1-knockout mice, periapical bone destruction was alleviated. Moreover, type I interferon induced the expression of interferon-stimulated genes (ISGs), which serve as a major source of Z-NA. In addition, the RNA-editing enzyme Adenosine Deaminase RNA specific 1 (ADAR1) prevented the accumulation of endogenous Z-NA. Meanwhile, metformin suppressed the ZBP1-mediated necroptosis by inhibiting the expression of ZBP1 and the accumulation of ISGs. Metformin also promoted mitochondrial apoptosis, which is critical for the elimination of intracellular bacterial infection. The enhanced apoptosis further promoted the healing of infected apical bone tissues. In summary, these results demonstrated that the recognition of Z-NA by ZBP1 plays an important role in AP pathogenesis. Metformin suppressed ZBP1-mediated necroptosis and promoted apoptosis, thereby contributing to the soothing of inflammation and bone healing in AP.

"We've got to get out"-Strategies of human pathogenic fungi to escape from phagocytes

Human fungal pathogens are a deadly and underappreciated risk to global health that most severely affect immunocompromised individuals. A virulence attribute shared by some of the most clinically relevant fungal species is their ability to survive inside macrophages and escape from these immune cells. In this review, we discuss the mechanisms behind intracellular survival and elaborate how escape is mediated by lytic and non-lytic pathways as well as strategies to induce programmed host cell death. We also discuss persistence as an alternative to rapid host cell exit. In the end, we address the consequences of fungal escape for the host immune response and provide future perspectives for research and development of targeted therapies.

A comparative study of apoptosis, pyroptosis, necroptosis, and PANoptosis components in mouse and human cells

Regulated cell death is a key component of the innate immune response, which provides the first line of defense against infection and homeostatic perturbations. However, cell death can also drive pathogenesis. The most well-defined cell death pathways can be categorized as nonlytic (apoptosis) and lytic (pyroptosis, necroptosis, and PANoptosis). While specific triggers are known to induce each of these cell death pathways, it is unclear whether all cell types express the cell death proteins required to activate these pathways. Here, we assessed the protein expression and compared the responses of immune and non-immune cells of human and mouse origin to canonical pyroptotic (LPS plus ATP), apoptotic (staurosporine), necroptotic (TNF-α plus z-VAD), and PANoptotic (influenza A virus infection) stimuli. When compared to fibroblasts, both mouse and human innate immune cells, macrophages, expressed higher levels of cell death proteins and activated cell death effectors more robustly, including caspase-1, gasdermins, caspase-8, and RIPKs, in response to specific stimuli. Our findings highlight the importance of considering the cell type when examining the mechanisms regulating inflammation and cell death. Improved understanding of the cell types that contain the machinery to execute different forms of cell death and their link to innate immune responses is critical to identify new strategies to target these pathways in specific cellular populations for the treatment of infectious diseases, inflammatory disorders, and cancer.