bims-cediti 2025-06-22 papers

bims-cediti

Biomed News

on Cell death in innate immunity, inflammation, and tissue repair

Issue of 2025–06–22
thirteen papers selected by
Kateryna Shkarina, Universität Bonn

TNF switches homeostatic efferocytosis to lytic caspase-8-dependent pyroptosis and IL-1β maturation.
CARD8 inflammasome activation during HIV-1 cell-to-cell transmission.
Pseudorabies virus DNA binding to porcine NLRC3 unleashes the activation of the porcine NLRP3 inflammasome.
TAK1 inhibition activates pore-forming proteins to block intracellular bacterial growth through modulating mitochondria.
Dendritic cells activate pyroptosis and effector-triggered apoptosis to restrict Legionella infection.
Nigericin Induces Paraptosis-Like Cell Death Instead of Pyroptosis in Corneal Keratocytes.
Exploring circulating cell-free DNA as a biomarker and as an inducer of AIM2-inflammasome-mediated inflammation in patients with abdominal aortic aneurysm.
Dual-Luciferase Reporter Assay to Investigate Virus-Host Interactions.
Executioner caspase is proximal to Fasciclin 3 which facilitates non-lethal activation in Drosophila olfactory receptor neurons.
Discovery and Validation of a Novel Class of Necroptosis Inhibitors Targeting RIPK1.
Dectin-1 participates in β-glucan- or PMA-induced neutrophil extracellular trap formation during antifungal defense.
Time matters: the dynamics of plasma membrane repair.
Piezo1 senses hyphae and initiates host defense against pathogenic fungi.

Sci Immunol. 2025 Jun 20. 10(108): eadq0043

TNF switches homeostatic efferocytosis to lytic caspase-8-dependent pyroptosis and IL-1β maturation.

Hayley I Muendlein, Wilson M Connolly, Jamie Leiriao, Mei-An Nolan, Jennifer Judge, Irina Smirnova, Rebecca Batorsky, Alexander Poltorak.

Efferocytosis, wherein phagocytes engulf dead or dying cells, is a critical function of macrophages that supports cellular turnover, tissue repair, and resolution of inflammation. Despite its well-established anti-inflammatory mechanism in homeostasis, whether efferocytosis remains immunologically silent in the context of dysregulated immune responses such as sepsis or systemic inflammatory response syndrome (SIRS) has not been investigated. Here, we used mouse models of tumor necrosis factor (TNF)-induced SIRS and Escherichia coli-induced septic peritonitis to uncover a potential negative consequence of efferocytosis. We found that when activated with TNF, phagocytes efferocytosing neutrophils initiated a caspase-8-dependent, but NLRP3 inflammasome-independent, form of pyroptosis, which we termed "efferoptosis." The maturation of IL-1β, a hallmark of pyroptotic cell death, also occurred independently of canonical inflammasome activation, supporting direct cleavage by caspase-8. Inhibition of efferocytosis protected mice against TNF-induced SIRS, suggesting that efferoptosis contributes to the pathology of sepsis and other TNF-mediated inflammatory conditions.

DOI: https://doi.org/10.1126/sciimmunol.adq0043
Elife. 2025 Jun 16. pii: RP102676. [Epub ahead of print]13

CARD8 inflammasome activation during HIV-1 cell-to-cell transmission.

Jessie Kulsuptrakul, Michael Emerman, Patrick S Mitchell.

  Our previous work demonstrated that CARD8 detects HIV-1 infection by sensing the enzymatic activity of the HIV protease, resulting in CARD8-dependent inflammasome activation (Kulsuptrakul et al., 2023). CARD8 harbors a motif in its N-terminus that functions as a HIV protease substrate mimic, permitting innate immune recognition of HIV-1 protease activity, which when cleaved by HIV protease triggers CARD8 inflammasome activation. Here, we sought to understand CARD8 responses in the context of HIV-1 cell-to-cell transmission via a viral synapse. We observed that cell-to-cell transmission of HIV-1 between infected T cells and primary human monocyte-derived macrophages induces CARD8 inflammasome activation in a manner that is dependent on viral protease activity and largely independent of the NLRP3 inflammasome. Additionally, to further evaluate the viral determinants of CARD8 sensing, we tested a panel of HIV protease inhibitor-resistant clones to establish how variation in HIV protease affects CARD8 activation. We identified mutant HIV-1 proteases that differentially cleave and activate CARD8 compared to wildtype HIV-1, thus indicating that natural variation in HIV protease affects not only the cleavage of the viral Gag-Pol polyprotein but also likely impacts innate sensing and inflammation.

Keywords:  CARD8; HIV-1; cell-to-cell; human; immunology; infectious disease; inflammasome; inflammation; microbiology; viral protease; viruses

DOI:  https://doi.org/10.7554/eLife.102676
Vet Microbiol. 2025 Jun 13. pii: S0378-1135(25)00239-1. [Epub ahead of print]307 110604

Pseudorabies virus DNA binding to porcine NLRC3 unleashes the activation of the porcine NLRP3 inflammasome.

Minjie Li, Xiangyu Huang, Hongyan Yin, Lvye Chai, Haiwei Wang, Xin Li.

  Viral infection activates multiple inflammatory pathways, with the NLRP3 inflammasome playing a pivotal role in host defense. However, negative regulation of the NLRP3 inflammasome is essential for maintaining host homeostasis. Here, we report that double-stranded DNA (dsDNA) from pseudorabies virus (PRV) induces NLRP3 inflammasome activation and pyroptosis through gasdermin D (GSDMD) cleavage and IL-1β secretion. Importantly, the inhibitory NLR porcine NLRC3 (pNLRC3) interacts with porcine NLRP3 (pNLRP3) and attenuates GSDMD cleavage and IL-1β release. Upon PRV infection, overexpression of pNLRC3 enhances GSDMD cleavage and lactate dehydrogenase release, whereas knockdown of pNLRC3 reduces pyroptosis. Mechanistically, pNLRC3 binds PRV dsDNA and unleashes its inhibitory effect on pNLRP3, functioning as a checkpoint to regulate inflammasome activation. Furthermore, pNLRC3 contributes to PRV restriction by controlling viral replication and limiting infection. In summary, our findings reveal a dual role of pNLRC3, acting both as a negative regulator of the pNLRP3 inflammasome and as a viral sensor that regulates pyroptosis-mediated viral clearance. These insights provide a deeper understanding of virus-host interactions and innate immune regulation.

Keywords:  Inflammasome; Porcine NLRC3; Porcine NLRP3; Pseudorabies virus; Pyroptosis

DOI:  https://doi.org/10.1016/j.vetmic.2025.110604
Cell Death Dis. 2025 Jun 18. 16(1): 456

TAK1 inhibition activates pore-forming proteins to block intracellular bacterial growth through modulating mitochondria.

Wilfred López-Pérez, Roland E González-Calderón, Kazuhito Sai, Prashant Rai, Jacqueline M MacStudy, Yosuke Sakamachi, Cameron Parsons, Sophia Kathariou, Michael B Fessler, Jun Ninomiya-Tsuji.

Mitogen-activated protein kinase kinase kinase 7 (MAP3K7), known as TAK1, is a central mediator of intracellular host defense signaling promoting inflammatory gene expression. Hence, TAK1 is a prime target of intracellular bacterial effectors in blocking inflammatory responses. However, when TAK1 is inhibited, host cells alternatively activate multiple cell death pathways, namely caspase 8-dependent apoptosis and pyroptosis, and receptor interacting protein kinase 3 (RIPK3)-dependent necroptosis. While these pathways ultimately lead to cell death, we found that they also modulate mitochondria to produce mitochondrial reactive oxygen species (ROS). Although as cell death executors, mixed lineage kinase-like (MLKL) and gasdermins are known to form pores in the plasma membrane, we found that TAK1 inhibition translocates them to mitochondria resulting in elevated mitochondrial ROS. Ablation of both MLKL and gasdermins diminished TAK1 inhibition-induced elevation of ROS and exacerbated intracellular bacterial colonization. Our results reveal that these cell death pathways have an alternative host defense role to prevent intracellular pathogen colonization.

DOI: https://doi.org/10.1038/s41419-025-07760-4
mBio. 2025 Jun 18. e0125725

Dendritic cells activate pyroptosis and effector-triggered apoptosis to restrict Legionella infection.

Víctor R Vázquez Marrero, Jessica Doerner, Kimberly A Wodzanowski, Jenna Zhang, Allyson Lu, Frankie D Boyer, Isabel Vargas, Suzana Hossain, Karly B Kammann, Madison V Dresler, Sunny Shin.

  The innate immune system relies on pattern recognition receptors (PRRs) to detect pathogen-associated molecular patterns (PAMPs) and guard proteins to monitor pathogen disruption of host cell processes. How different immune cell types engage PRRs and guard proteins to respond to infection is poorly understood. Here, we show that macrophages and dendritic cells (DCs) distinctly respond to bacterial virulence activities. In macrophages, the bacterial pathogen Legionella pneumophila deploys its Dot/Icm type IV secretion system (T4SS) to deliver effector proteins that facilitate robust intracellular replication. In contrast, T4SS activity triggers rapid death of DCs, which potently restricts Legionella replication. Intriguingly, we found that infected DCs exhibit considerable heterogeneity at the single-cell level. Initially, some DCs activate caspase-11 and NLRP3 inflammasome-dependent pyroptosis early during infection. At later time points, other DCs undergo apoptosis driven by T4SS effectors that block host protein synthesis, thereby depleting the pro-survival proteins Mcl-1 and cFLIP. Together, pyroptosis and effector-triggered apoptosis robustly restrict Legionella replication in DCs. Collectively, our findings suggest a model where Mcl-1 and cFLIP guard host translation in DCs. Furthermore, our work shows that macrophages and DCs distinctly employ innate immune sensors and guard proteins to mount divergent responses to Legionella infection.IMPORTANCEThe innate immune system senses bacterial pathogens by employing pattern recognition receptors that detect pathogen-associated molecular patterns (PAMPs) and guard proteins that monitor pathogen disruption of host cell processes. How different immune cell types engage pattern recognition receptors (PRRs) and guard proteins to respond to infection is poorly understood. Here, we reveal how dendritic cells (DCs) detect and restrict the intracellular bacterial pathogen Legionella pneumophila. At the single-cell level, we find that early during infection, some DCs activate caspase-11 pyroptosis. At later time points, other DCs undergo apoptosis driven by type IV secretion system (T4SS) effectors that block host protein synthesis, which depletes levels of the pro-survival proteins Mcl-1 and cFLIP. Our findings suggest Mcl-1 and cFLIP safeguard mRNA translation in DCs and highlight differences in how macrophages and DCs employ PRRs and guard proteins to respond to bacterial infection.

Keywords:  Legionella pneumophila; apoptosis; caspase-11; dendritic cells; guard immunity; innate immunity; pyroptosis

DOI:  https://doi.org/10.1128/mbio.01257-25
FASEB J. 2025 Jun 30. 39(12): e70740

Nigericin Induces Paraptosis-Like Cell Death Instead of Pyroptosis in Corneal Keratocytes.

Xiangquan Mi, Xin Zhou, Shaochun Zhu, Andre Mateus, Ludvig J Backman, Patrik Danielson.

The purpose of this study was to examine the nature of the underlying molecular mechanisms of cell death in human keratocytes treated with nigericin, a known pyroptosis inducer. Human keratocytes were exposed to nigericin, and cell death was assessed through morphological analysis and detection of related molecular markers. Proteomic profiling was performed to identify cell death-related proteins, with key findings validated by western blot. Additionally, organelle disruptions were examined using immunostaining techniques. Pyroptosis-like cell death was observed morphologically in cultured keratocytes. Moreover, an elevated release of IL-1beta was detected, accompanied by a significant loss of mitochondrial membrane potential. However, nigericin treatment induced a form of non-inflammatory cell death characterized by extensive vacuolation, resembling paraptosis. This was accompanied by the absence of caspase-3 activation and endoplasmic reticulum (ER) stress markers, along with increased accumulation of the autophagic marker LC3-II. Proteomic analysis revealed the absence of key components of the canonical pyroptosis pathway, including proteins involved in inflammasome assembly and the gasdermin (GSDM) family. These results were further confirmed by western blot. Significant alterations were also observed in the Golgi apparatus, mitochondria, and lysosomes following nigericin treatment. These findings suggest that nigericin triggers a paraptosis-like cell death in human keratocytes, rather than pyroptosis, as keratocytes lack the canonical executors of pyroptosis. This highlights an alternative mechanism of cell death in the cornea, warranting further exploration to understand its role and potential therapeutic implications.

DOI: https://doi.org/10.1096/fj.202500502R
Sci Rep. 2025 Jun 20. 15(1): 20196

Exploring circulating cell-free DNA as a biomarker and as an inducer of AIM2-inflammasome-mediated inflammation in patients with abdominal aortic aneurysm.

Susanne Dihlmann, Carolin Kaduk, Karola H Passek, Anja Spieler, Dittmar Böckler, Andreas S Peters.

  Circulating cell-free (cf) DNA in blood plasma is considered a diagnostic and prognostic biomarker of tissue damage and could be a driver of chronic inflammation by stimulating the innate immune response via activation of inflammasomes. Increased AIM2-inflammasome activity in the aortic wall is associated with abdominal aortic aneurysm (AAA). We here hypothesized that cfDNAs are elevated in the plasma of AAA patients and are associated with chronic inflammation. Single strand (ss)DNA, double strand (ds)DNA and mitochondrial (mt)DNA levels were explored in plasma and leucocytes from 93 AAA patients, 89 controls (non-AAA patients) and 10 healthy subjects, using fluorescence-based quantification and real-time qPCR, respectively. To analyse inflammasome activation by cfDNA, differentiated THP-1 macrophages were primed with lipopolysaccharide (LPS) and then stimulated for one, six or 24 h with DNA extracted from peripheral blood mononuclear cells (PBMC) of AAA patients. Our analysis revealed significantly increased levels of ssDNA, dsDNA and mtDNA levels in plasma from AAA patients compared with non-AAA patients and healthy subjects. In addition, the mtDNA copy number was significantly higher in PBMC from AAA patients. Stimulation of THP-1 cells with PBMC-DNA resulted in increased expression of inflammasome genes, especially the DNA sensors AIM2 and IFI16. At early time points, PBMC-DNA stimulated THP-1 showed significantly increased apoptosis-associated speck-like protein with a CARD (ASC) and Pro-Interleukin-1β protein levels compared to untreated or only LPS-primed cells, resulting in the formation of significantly more ASC specks after 24 h, a sign of inflammasome activation. We conclude from our data that cfDNA of AAA patients triggers a proinflammatory response in macrophages by activating the AIM2 inflammasome and thus could be a driving force for the chronic inflammation observed in these patients.

Keywords:  AIM2; Abdominal aortic aneurysm; Biomarker; Cell free DNA; Inflammasome; Proinflammatory response; THP-1 cells; mtDNA

DOI:  https://doi.org/10.1038/s41598-025-06220-5
Methods Mol Biol. 2025 ;2940 337-341

Dual-Luciferase Reporter Assay to Investigate Virus-Host Interactions.

Li Yi, Chunfu Zheng.

  The interplay between viruses and host innate immunity is very intricate, with viral proteins having evolved various strategies to target multiple steps of antiviral innate immune signaling pathways. The dual-luciferase reporter assay is a high-flux and efficient method that can rapidly screen potential viral immune evasion components. In this context, a dual-luciferase reporter assay is applied to screen and identify viral proteins that target the host signaling pathway for immune evasion, which provides valuable insights into the function of viral proteins during infections.

Keywords:  Antiviral innate immunity; DLR; Immune evasion; Viral proteins

DOI:  https://doi.org/10.1007/978-1-0716-4615-1_29
Elife. 2025 Jun 17. pii: RP99650. [Epub ahead of print]13

Executioner caspase is proximal to Fasciclin 3 which facilitates non-lethal activation in Drosophila olfactory receptor neurons.

Masaya Muramoto, Nozomi Hanawa, Misako Okumura, Takahiro Chihara, Masayuki Miura, Natsuki Shinoda.

  The nervous system undergoes functional modification independent of cell turnover. Caspase participates in reversible neuronal modulation via non-lethal activation. However, the mechanism that enables non-lethal activation remains unclear. Here, we analyzed proximal proteins of Drosophila executioner caspase in the adult brain using TurboID. We discovered that executioner caspase Drice is, as an inactive proform, proximal to cell membrane proteins, including a specific splicing isoform of cell adhesion molecule Fasciclin 3 (Fas3), Fas3G. To investigate whether sequestration of executioner caspase to plasma membrane of axons is the mechanism for non-lethal activation, we developed a Gal4-Manipulated Area-Specific CaspaseTracker/CasExpress system for sensitive monitoring of caspase activity near the plasma membrane. We demonstrated that Fas3G overexpression promotes caspase activation in olfactory receptor neurons without killing them, by inducing expression of initiator caspase Dronc, which also comes close to Fas3G. Physiologically, Fas3G overexpression-facilitated non-lethal caspase activation suppresses innate olfactory attraction behavior. Our findings suggest that subcellularly restricted caspase activation, defined by caspase-proximal proteins, is the mechanism for non-lethal activation, opening the methodological development of reversible modification of neuronal function via regulating caspase-proximal proteins.

Keywords:  D. melanogaster; MASCaT; TurboID; caspase; caspase-dependent non-lethal cellular processes; cell biology; neuroscience; olfaction

DOI:  https://doi.org/10.7554/eLife.99650
ACS Chem Biol. 2025 Jun 20.

Discovery and Validation of a Novel Class of Necroptosis Inhibitors Targeting RIPK1.

Lior Soday, Chotima Seripracharat, Janine L Gray, André F S Luz, Ryan T Howard, Ravi Singh, Thomas J Burden, Erika Bernardini, Miguel Mateus-Pinheiro, Jens Petersen, Anders Gunnarsson, Jenny Gunnarsson, Anna Aagaard, Tove Sjögren, Sarah Maslen, Edward J Bartlett, Abigail F Iles, David M Smith, James S Scott, Mark Skehel, Andrew M Davis, Ana S Ressurreição, Rui Moreira, Cecília M P Rodrigues, Avinash R Shenoy, Edward W Tate.

Necroptosis is a form of programmed cell death that, when dysregulated, is associated with cancer and inflammatory and neurodegenerative diseases. Here, starting from hits identified from a phenotypic high-throughput screen for inhibitors of necroptosis, we synthesized a library of compounds containing a 7-phenylquinoline motif and validated their anti-necroptotic activity in a novel live-cell assay. Based on these data, we designed an optimized photoaffinity probe for target engagement studies and through biochemical and cell-based assays established receptor-interacting kinase 1 (RIPK1) as the cellular target, with inhibition of necroptosis arising from the prevention of RIPK1 autophosphorylation and activation. X-ray crystallography and mass spectrometry revealed that these compounds bind at the hinge region of the active conformation of RIPK1, establishing them as type I kinase inhibitors. In addition, we demonstrated in vitro synergy with type III kinase inhibitors, such as necrostatin-1 and found that lead compounds protected mice against acute inflammation in necroptosis models in vivo. Overall, we present a novel pharmacophore for inhibition of human RIPK1, a key protein involved in necroptosis, and provide a photoaffinity probe to explore RIPK1 target engagement in cells.

DOI: https://doi.org/10.1021/acschembio.5c00112
Am J Transl Res. 2025 ;17(5): 3898-3907

Dectin-1 participates in β-glucan- or PMA-induced neutrophil extracellular trap formation during antifungal defense.

Shoude Zhang, Ying Lu, Yuan Zhao, Zhanwei Dong, Mao Jin, Mina Xu, Hong Pan, Mang Xiao.

   OBJECTIVES: The formation of neutrophil extracellular traps (NETs) plays a crucial role in neutrophil-mediated defense against fungal infections and has become a hot topic of immunological research. This study aimed to investigate whether high expression of Dectin-1, a key pattern recognition receptor, contributes to NET formation in response to fungal pathogens.
METHODS: Human neutrophils were isolated and characterized, then stimulated with cell wall β-glucan to induce NET formation. Phorbol 12-myristate 13-acetate (PMA), a diacylglycerol mimetic, was used as a positive control. Dectin-1 antibody was used to determine the functional significance of Dectin-1 in the formation of NETs. NET formation was detected by Sytox Green staining, myeloperoxidase (MPO) and neutrophil elastase (NE) immunofluorescence staining, and western blot analysis. The relative kits, 2',7'-dichlorodihydrofluorescein diacetate staining and MitoSOX Red staining were used to determine the mechanism of Dectin-1 induced NET formation.
RESULTS: Dectin-1 was overexpressed in β-glucan- and PMA-treated neutrophils. Dectin-1 deficiency reduced NET formation, accompanied by decreased Sytox Green fluorescence, lower levels of dsDNA content, and decreased expression of NE, MPO and citrullinated histone H3 (H3Cit). Dectin-1-mediated NET formation was dependent on reactive oxygen species (ROS) produced by NADPH oxidase (NOX), NOX2 protein and mitochondrial superoxide. Moreover, up-regulated Dectin-1 expression activated the extracellular regulated protein kinases (ERK) and p38 MAPK pathways, which were critical for the induction of NETs.
CONCLUSION: Dectin-1 promotes NET formation in neutrophils stimulated by β-glucan or PMA through activation of the ERK and p38 signaling pathways, which might contribute to defense against fungal pathogens.

Keywords:  Dectin-1; PMA; neutrophil extracellular traps; β-glucan

DOI:  https://doi.org/10.62347/YQCM4496
Trends Cell Biol. 2025 Jun 16. pii: S0962-8924(25)00115-1. [Epub ahead of print]

Time matters: the dynamics of plasma membrane repair.

Nikita Raj, Volker Gerke.

  The plasma membrane (PM) of eukaryotic cells is constantly exposed to many challenges that can cause wounds that necessitate rapid and efficient repair mechanisms to ensure cell survival. PM wound repair not only encompasses the immediate resealing of the membrane barrier, which involves exocytosis of internal vesicles to deliver membrane, but also subsequent processes that are essential to restore cellular homeostasis. These include restoration of membrane and cortical cytoskeleton structures, as well as replenishment of intracellular organelles consumed during resealing. Recent evidence suggests that the different steps in PM repair, resealing, restructuring, and restoration, are spatiotemporally correlated and regulated by membrane tension. Recent advances in understanding the different phases of PM repair are reviewed and a time-dependent classification of repair mechanisms is proposed.

Keywords:  calcium; endocytosis; exocytosis; membrane wound

DOI:  https://doi.org/10.1016/j.tcb.2025.05.005
Cell Rep. 2025 Jun 16. pii: S2211-1247(25)00610-2. [Epub ahead of print]44(6): 115839

Piezo1 senses hyphae and initiates host defense against pathogenic fungi.

Yiran Shi, Bingying Yang, Yueyue Linghu, Yue Liu, Haoran Li, Yunzhi Xing, Binbin Wu, Yuting Gao, Liuqi Liao, Yi Zheng, Lei Pan, Xiufeng Sun, Qinghua Chen, Yongqiang Hou, Dongxue Su, Hongling Huang, Jiahuai Han, Shih-Chin Cheng, Dawang Zhou, Lanfen Chen.

  Candida albicans metamorphoses from benign yeast to a rigid hyphal, becoming an opportunistic pathogen in immunocompromised patients. The process by which immune cells discern fungal transformations remains elusive. Here, we report that the mechanosensitive ion channel Piezo1 is indispensable for recognizing fungal hyphae and triggering antifungal innate immune responses. Hyphae-triggered Piezo1 activation increased C-type lectin receptor (CLR) expression in innate immune cells by inducing the expression of CCAAT/enhancer-binding protein beta (C/EBPβ) via the Piezo1/Ca2+/calmodulin-dependent kinase (CaMK)/cAMP response element-binding protein (CREB) axis. In addition, Piezo1/CaMK signaling activated kinases nuclear Dbf2-related protein 1/2 (NDR1/2), which augmented NLRP3 inflammasome assembly and promoted hyphae-induced inflammation. Abolishing the yeast-to-hyphae transition dampens CLR expression and NLRP3 activation. Piezo1-deficient mice exhibit compromised clearance of C. albicans infection, whereas Piezo1 agonist amplifies C. albicans clearance. In addition, CaMK, CREB, or NDR1/2 inhibition exacerbates hyphae infections, such as Piezo1 deficiency. Therefore, we ascertain Piezo1-mediated mechanotransduction as vital for immune surveillance and control of hyphal C. albicans, heralding Piezo1 agonist as a potential remedy for fungal infections.

Keywords:  C-type lectin receptors; C. albicans; CP: Immunology; CP: Microbiology; NLRP3 inflammasome; Piezo1; fungal infection; mechanical force

DOI:  https://doi.org/10.1016/j.celrep.2025.115839