bims-cediti 2025-05-18 papers

bims-cediti

Biomed News

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

Issue of 2025–05–18
23 papers selected by
Kateryna Shkarina, Universität Bonn

Gasdermin-D pores induce an inactivating caspase-4 cleavage that limits IL-18 production in the intestinal epithelium.
Improved humanized mouse model of Staphylococcus aureus infection.
The scaffolding and activation of NLRP3 on acidic vesicles depends on their biophysical properties and is independent of intermediate filaments.
Pharmacologic Targeting of PDIA1 Inhibits NLRP3 Inflammasome Assembly and Activation.
Immune cell activation produces locally scrambled foci of plasma membrane lipids.
Gasdermin E links tumor cell-intrinsic nucleic acid signaling to proinflammatory cell death for successful checkpoint inhibitor cancer immunotherapy.
Caspase-1-licensed pyroptosis drives dsRNA-mediated necroptosis and dampens host defense against bacterial pneumonia.
Platelet NLRP6 protects from microvascular thrombosis in sepsis.
Calpains orchestrate secretion of annexin-containing microvesicles during membrane repair.
SENP2-mediated deSumoylation of NCOA4 protects against ferritinophagy-dependent ferroptosis in myocardial ischemia-reperfusion injury.
RING1 dictates GSDMD-mediated inflammatory response and host susceptibility to pathogen infection.
Host PIK3C3 promotes Shigella flexneri spread from cell to cell through vacuole formation.
Investigating endogenous immune-mediated monocyte memory in rheumatoid arthritis.
Annexin A2 Contributes to Release of Extracellular Vimentin in Response to Inflammation.
A fluorescent sensor for real-time monitoring of DPP8/9 reveals crucial roles in immunity and cancer.
Pyrazolone-Modified Photosensitizers for Precise Cell Membrane Rupture to Enhance Cancer Immunotherapy.
NLRP3 inflammasome activation expands immunosuppressive myeloid stroma and antagonizes the therapeutic benefit of STING activation in glioblastoma.
Fever-range temperature alters continual efferocytosis mediated by mouse pro-inflammatory macrophages.
Targeted p38 mitogen-activated protein kinase inhibition potently augment inflammatory responses of human macrophages toward Staphylococcus aureus.
A review of cell death pathways in hemorrhagic stroke.
HSPA9 contributes to tumor progression and ferroptosis resistance by enhancing USP14-driven SLC7A11 deubiquitination in multiple myeloma.
Mitochondrial metabolism is rapidly re-activated in mature neutrophils to support stimulation-induced response.
Molecular machineries shaping the mitochondrial inner membrane.

Commun Biol. 2025 May 13. 8(1): 737

Gasdermin-D pores induce an inactivating caspase-4 cleavage that limits IL-18 production in the intestinal epithelium.

J K Bruce, L Y Li, Y Tang, E G Forster, N J Winsor, P Y Bi, C Krustev, S Keely, J E Lee, J R Rohde, H Y Gaisano, D J Philpott, S E Girardin.

Intestinal epithelial-derived IL-18 is critical for homeostatic intestinal barrier function and is secreted through Gasdermin D (GSDMD) pores. Inflammasome activation is a prerequisite for both IL-18 maturation and GSDMD pore formation. However, GSDMD pores also cause pyroptotic cell death, which could be detrimental to the intestinal epithelial barrier. How epithelial cells balance the need to secrete IL-18 and to maintain barrier integrity remains poorly understood. In human intestinal epithelial cell lines and in primary human epithelial intestinal organoids, but not in immune cells, GSDMD plasma membrane pore formation by LPS electroporation and by gram-negative bacterial infection induced a non-conventional p37 caspase-4 fragment that was associated with reduced levels of mature IL-18. By contrast, limiting GSDMD plasma membrane pores pharmacologically and via point-mutagenesis prevented caspase-4 cleavage and increased IL-18 production, suggesting that p37 caspase-4 cleavage may regulate IL-18 maturation in the intestinal epithelium. In support, co-expression of caspase-4 cleavage mutants and IL-18 in HEK293T cells revealed that non-cleavable caspase-4 produced more mature IL-18 than cleaved caspase-4. Overall, these studies suggest that epithelial inflammasomes encode feedback pathways that control the balance between cytokine secretion and cell death. This may be an important mechanism to ensure homeostatic IL-18 production in the intestinal epithelium.

DOI: https://doi.org/10.1038/s42003-025-08183-9
Mucosal Immunol. 2025 May 10. pii: S1933-0219(25)00048-0. [Epub ahead of print]

Improved humanized mouse model of Staphylococcus aureus infection.

Hui Wang, Dane Parker.

  Staphylococcus aureus is a significant cause of pulmonary infections, but existing mouse models fail to recapitulate human-specific responses. In this study, we developed a novel mouse model of S. aureus infection using humanized mice implanted with autologous fetal lung tissue. We show that these human lung implants support S. aureus survival and dissemination. Immunological profiling revealed extensive immune cell death after infection and an absence of chemokine induction. Transcriptomic profiling of the human lung implants revealed significant changes in gene expression, including NF-κB and JAK/STAT signaling. We identified upregulation of Cyp24a1, suggesting a role for vitamin D metabolism in host defense, but it had a mild effect on dissemination. Examination of the bacterial response to the host environment, found downregulation of virulence factors and metabolic genes, and upregulation of stress response pathways. The importance of the heat shock response in bacterial survival was shown as hrcA-deficient S. aureus exhibited reduced tissue colonization. These findings underscore the utility of this humanized lung model for studying S. aureus pathogenesis and bacterial adaptation to the human pulmonary environment.

Keywords:  Humanized mice; Lung; Mouse model; Pneumonia; Staphylococcus aureus

DOI:  https://doi.org/10.1016/j.mucimm.2025.05.001
Mol Biol Cell. 2025 May 15. mbcE24110511

The scaffolding and activation of NLRP3 on acidic vesicles depends on their biophysical properties and is independent of intermediate filaments.

Guillermo de Paz Linares, Jan Mossemann, Blayne Sayed, Spencer A Freeman.

Inflammasomes are nucleated by receptors that become activated upon cellular stresses including ionic dyshomeostasis. Rather than forming in the cytosol, recent evidence suggests that inflammasomes are nucleated at specific sites in the cell including on cytoskeletal polymers and the membrane surfaces of organelles. The NLRP3 inflammasome, which is formed upon the loss of cytosolic K+, had been proposed to form on intermediate filaments as well as on vesicles along the endocytic pathway. To determine the necessary requirement of either mechanism, we used vimentin knockout macrophages which do not have intermediate filaments and compared the formation and function of NLRP3 inflammasomes. We report that vimentin was dispensable for the activation of caspase-1, IL-1β cleavage and release, and inflammatory responses in mice attributed to the inflammasome. Instead, NLRP3 was recruited to PI(3,5)P2, PI(4)P- and LAMP1-positive compartments undergoing osmotic swelling. Swelling of these compartments was dependent on the V-ATPase, the inhibition of which curtailed NLRP3 recruitment and inflammasome activation. Similarly, decreasing the hydrostatic pressure on these vesicles prevented NLRP3 recruitment, IL-1β release and pyroptosis. The results suggest that NLRP3 is activated by biophysical features of acidic organelles in the endocytic pathway. [Media: see text].

DOI: https://doi.org/10.1091/mbc.E24-11-0511
Isr J Chem. 2024 Dec;pii: e202300125. [Epub ahead of print]64(12):

Pharmacologic Targeting of PDIA1 Inhibits NLRP3 Inflammasome Assembly and Activation.

Jessica D Rosarda, Caroline R Stanton, Emily B Chen, Michael J Bollong, R Luke Wiseman.

  The NLRP3 inflammasome is a cytosolic protein complex that regulates innate immune signaling in response to diverse pathogenic insults through the proteolytic processing and secretion of pro-inflammatory cytokines such as IL-1β. Hyperactivation of NLRP3 inflammasome signaling is implicated in the onset and pathogenesis of numerous diseases, motivating the discovery of new strategies to suppress NLRP3 inflammasome activity. We sought to define the potential for the proteostasis regulator AA147 to inhibit the assembly and activation of the NLRP3 inflammasome. AA147 is a pro-drug that is metabolically converted to a reactive metabolite at the endoplasmic reticulum (ER) membrane to covalently modify ER-localized proteins such as protein disulfide isomerases (PDIs). We show that AA147 inhibits NLRP3 inflammasome activity in monocytes and monocyte-derived macrophages through a mechanism involving impaired assembly of the active inflammasome complex. This inhibition is mediated through AA147-dependent covalent modification of PDIA1. Genetic depletion or treatment with other highly selective PDIA1 inhibitors similarly blocks NLRP3 inflammasome assembly and activation. Our results identify PDIA1 as a potential therapeutic target to mitigate NLRP3 inflammasome-mediated pro-inflammatory signaling implicated in etiologically diverse diseases.

Keywords:  NLRP3; inflammasome; inhibitor; innate immunity; protein disulfide isomerase; small molecule

DOI:  https://doi.org/10.1002/ijch.202300125
Faraday Discuss. 2025 May 12.

Immune cell activation produces locally scrambled foci of plasma membrane lipids.

Daryna Sputay, Milka Doktorova, Sze Ham Chan, Emma Han Guo, Hong-Yin Wang, Joseph H Lorent, Ilya Levental, Kandice R Levental.

Most eukaryotic cells maintain a large disparity in lipid compositions between the cytosolic and external leaflets of the plasma membrane (PM) bilayer. This lipid asymmetry is maintained by energy-consuming flippase enzymes that selectively drive phospholipids into the cytosolic leaflet, often against large concentration gradients. Scramblases, activated by intracellular Ca2+ or apoptotic signaling, shuttle phospholipids down their concentration gradient to release lipid asymmetry. Such scrambling is typically evidenced by exposure of phosphatidylserine (PS) to the external leaflet and is associated with many physiological processes, most notably blood clotting and cell death, but also activation of immune cells. Here, we show that both PS and phosphatidylethanolamine (PE) appear on the PM external leaflet following immune receptor-mediated activation of mast cells. We also observe similar effects in T cells. Importantly, in contrast to wholesale release of PM asymmetry induced by calcium ionophores or apoptosis, we show that scrambling in activated immune cells is focal, with small, stable regions of surface exposed PS. These scrambled foci are calcium dependent, have lower lipid packing than their surrounding outer leaflet, and are reversible. These observations of local, transient scrambling during physiological activation of healthy immune cells suggest important roles for the lateral and transbilayer organization of membrane lipids.

DOI: https://doi.org/10.1039/d4fd00205a
Oncoimmunology. 2025 Dec;14(1): 2504244

Gasdermin E links tumor cell-intrinsic nucleic acid signaling to proinflammatory cell death for successful checkpoint inhibitor cancer immunotherapy.

Stefan Enssle, Anna Sax, Peter May, Nadia El Khawanky, Nardine Soliman, Markus Perl, Julius C Enssle, Karsten Krey, Jürgen Ruland, Andreas Pichlmair, Florian Bassermann, Hendrik Poeck, Simon Heidegger.

  Durable clinical responses to immune checkpoint inhibitors (ICI) are limited to a minority of patients, and molecular pathways that modulate their efficacy remain incompletely defined. We have recently shown that activation of the innate RNA-sensing receptor RIG-I and associated apoptotic tumor cell death can facilitate tumor immunosurveillance and -therapy, but the mechanism that drives its immunogenicity remained unclear. We here show that intratumoral activity of the pore-forming protein gasdermin E (GSDME) links active RIG-I signaling and apoptotic cell death in tumor cells to inflammatory pyroptosis. Activation of tumor-intrinsic RIG‑I triggered cleavage of GSDME, pore formation, loss of cell membrane integrity and leakage of cytosolic components from dying tumor cells. Tumor antigen cross-presentation by dendritic cells and subsequent expansion of cytotoxic T cells strongly relied on tumor-intrinsic GSDME activity. In preclinical murine cancer models, defective GSDME signaling rendered tumors resistant to ICI therapy. Epigenetic reprogramming with upregulation of Gdsme enhanced the susceptibility of tumor cells to inflammatory cell death and immunotherapy. In humans, transcriptome analysis of melanoma samples showed strong correlation between genetic activity of the RIG-I and pyroptosis pathways. In melanoma patients, high transcriptional activity of a pyroptosis gene set was associated with prolonged survival and beneficial response to ICI therapy. In summary, our data show that GSDME links RIG-I and apoptotic signaling to inflammatory cell death, thereby driving its immunogenicity and responsiveness to ICI. A deeper understanding of these pathways may allow for the development of novel combined modality approaches to improve ICI treatment responses in cancer patients.

Keywords:  Cancer immunotherapy; Gasdermin E; RIG-I; apoptosis; cancer resistance mechanism; immune checkpoint inhibitors; immunogenic cell death; programmed cell death; pryroptosis

DOI:  https://doi.org/10.1080/2162402X.2025.2504244
PLoS Pathog. 2025 May 13. 21(5): e1013167

Caspase-1-licensed pyroptosis drives dsRNA-mediated necroptosis and dampens host defense against bacterial pneumonia.

Qinyu Luo, Lihua Shen, Shiyue Yang, Yan Zhang, Yihang Pan, Zehua Wu, Qiang Shu, Qixing Chen.

Bacterial lung infections cause severe host responses. Here, we showed that global deficiency of caspase-1 can protect against lethal pulmonary Escherichia coli infection by reducing the necroptosis of infiltrated neutrophils, which are key players in immune responses in the lung. Mechanistically, neutrophil necroptosis was not directly triggered in a cell-intrinsic manner by invading bacteria but was triggered by bacteria-stimulated pyroptotic epithelial cell supernatants in vitro. In validation experiments, chimeric mice with nonhematopoietic caspase-1 or GSDMD knockout were protected from lung E. coli infection and exhibited decreased neutrophil death. Nonhematopoietic pyroptosis facilitates the release of dsRNAs and contributes to neutrophil ZBP1-related necroptosis. Moreover, blocking dsRNA or depleting ZBP1 ameliorated the pathophysiological process of pulmonary E. coli infection. Overall, our results demonstrate a paradigm of communication between necroptosis and pyroptosis in different cell types in cooperation with microbes and hosts and suggest that therapeutic targeting of the pyroptosis or necroptosis pathway may prevent pulmonary bacterial infection.

DOI: https://doi.org/10.1371/journal.ppat.1013167
Blood. 2025 May 15. pii: blood.2025028739. [Epub ahead of print]

Platelet NLRP6 protects from microvascular thrombosis in sepsis.

Huimin Jiang, Shuang Chen, Xiang Gui, Yingying Li, Yueyue Sun, Hui Zhu, Yue Dai, Jie Zhang, Xiaoqian Li, Wen Ju, Zhenyu Li, Lingyu Zeng, Kailin Xu, Jianlin Qiao.

Sepsis is characterized by a systemic inflammation and microvascular thrombosis induced by infection. NLRP6 possesses both pro- and anti-inflammatory effects with cell-type- or tissue-specific functions. However, the role of cell-type-specific NLRP6 in sepsis remains poorly understood. In the present study, we detected NLRP6 expression in platelets. By using platelet-specific NLRP6 knockout mice and the cecal ligation and puncture model of sepsis, we demonstrated that deletion of platelet NLRP6 increased the mortality, enhanced microvascular thrombosis in the lung and liver, and promoted platelet activation, platelet-neutrophil interactions as well as the neutrophil extracellular traps (NETs) formation following sepsis. Platelet function analysis in vitro showed that deletion of NLRP6 enhanced platelet aggregation, activation, and granules release. In addition, NLRP6 deletion promoted platelet NF-κB signaling via sustaining TAB1 expression independent of the inflammasome. Moreover, inhibition of NF-κB signaling abolished the aggravated effects of the absence of platelet NLRP6 on the intravascular microthrombosis and NETs formation in sepsis and increased the overall survival. Mechanistically, NLRP6 facilitated the interaction between TRIM21 and TAB1 in activated platelets, resulting in K48-linked polyubiquitination of TAB1 and subsequent degradation. Finally, sepsis plasma triggered TAB1 degradation mediated by NLRP6/TRIM21 in normal healthy platelets through TLR4/MyD88. Our study identifies a novel protective role of platelet NLRP6 in the microvascular thrombosis during sepsis, implying it as a novel target for the treatment of sepsis.

DOI: https://doi.org/10.1182/blood.2025028739
J Cell Biol. 2025 Jul 07. pii: e202408159. [Epub ahead of print]224(7):

Calpains orchestrate secretion of annexin-containing microvesicles during membrane repair.

Justin Krish Williams, Jordan Matthew Ngo, Abinayaa Murugupandiyan, Dorothy E Croall, H Criss Hartzell, Randy Schekman.

Microvesicles (MVs) are membrane-enclosed, plasma membrane-derived particles released by cells from all branches of life. MVs have utility as disease biomarkers and may participate in intercellular communication; however, physiological processes that induce their secretion are not known. Here, we isolate and characterize annexin-containing MVs and show that these vesicles are secreted in response to the calcium influx caused by membrane damage. The annexins in these vesicles are cleaved by calpains. After plasma membrane injury, cytoplasmic calcium-bound annexins are rapidly recruited to the plasma membrane and form a scab-like structure at the lesion. In a second phase, recruited annexins are cleaved by calpains-1/2, disabling membrane scabbing. Cleavage promotes annexin secretion within MVs. Our data support a new model of plasma membrane repair, where calpains relax annexin-membrane aggregates in the lesion repair scab, allowing secretion of damaged membrane and annexins as MVs. We anticipate that cells experiencing plasma membrane damage, including muscle and metastatic cancer cells, secrete these MVs at elevated levels.

DOI: https://doi.org/10.1083/jcb.202408159
Autophagy. 2025 May 14.

SENP2-mediated deSumoylation of NCOA4 protects against ferritinophagy-dependent ferroptosis in myocardial ischemia-reperfusion injury.

Siyuan Xue, Jiaxin Zeng, Jingzhe Hao, Wanzhi Cai, Yuxuan Ding, Yuelin Chao, Zong Miao, Guanhua Xu, Lei Xu, Zeyu Jiang.

  Myocardial ischemia-reperfusion (MI/R) injury is a leading cause of morbidity and mortality around the world, characterized by injury to cardiomyocytes that leads to various forms of cell death, including necrosis, apoptosis, autophagy, and ferroptosis. Preventing cell death is crucial for preserving cardiac function after ischemia-reperfusion injury. Ferroptosis, a novel type of cell death, has recently been identified as a key driver of cardiomyocyte death following MI/R. However, the complex regulatory mechanisms involved in ferroptosis remain unclear. Here, we found that SENP2 expression decreased following myocardial ischemia reperfusion injury. Deletion of SENP2 increased cardiomyocyte ferroptosis and hindered cardiac function recovery after MI/R injury, whereas overexpression of SENP2 significantly reduced cardiomyocyte ferroptosis and mitigated MI/R injury. Mechanistically, SENP2 removed the SUMOylation of NCOA4 modified by SUMO1 at K81, K343, and K600 sites. The level of NCOA4 SUMOylation regulated ferritinophagy-dependent ferroptosis through affecting NCOA4 protein stability. SENP2-mediated NCOA4 deSUMOylation alleviated the interaction between NCOA4 and OTUB1, which directly deubiquitinated NCOA4 and maintained its protein stability. Furthermore, administration of SENP2 in the animal MI/R model reduced ferroptosis events, protected the injured myocardium and promoted cardiac function recovery. Collectively, our results demonstrate that SENP2 catalyzes deSUMOylation of NCOA4, alleviates ferritinophagy-mediated ferroptosis in an OTUB1-dependent manner, thereby facilitating cardiac function recovery following MI/R. These findings suggest a potential therapeutic strategy for MI/R treatment.

Keywords:  Ferritinophagy; NCOA4; OTUB1; Sumoylation; ferroptosis; myocardial ischemia-reperfusion

DOI:  https://doi.org/10.1080/15548627.2025.2504792
Cell Death Differ. 2025 May 14.

RING1 dictates GSDMD-mediated inflammatory response and host susceptibility to pathogen infection.

Yuanyuan Li, Wenqing Gao, Yuxin Qiu, Jiasong Pan, Qingqing Guo, Xuehe Liu, Lu Geng, Yajie Shen, Yifan Deng, Zhidong Hu, Suhua Li, Shanshan Liu, Adi Idris, Jinqing Huang, Hua Yang, Baoxue Ge, Xiaoyong Fan, Xiangjun Chen, Jixi Li.

RING1 is an E3 ligase component of the polycomb repressive complex 1 (PRC1) with known roles in chromatin regulation and cellular processes such as apoptosis and autophagy. However, its involvement in inflammation and pyroptosis remains elusive. Here, we demonstrate that human RING1, not RING2, promotes K48-linked ubiquitination of Gasdermin D (GSDMD) and acts as a negative regulator of pyroptosis and bacterial infection. Indeed, we showed that loss of Ring1 increased S. typhimurium infectious load and mortality in vivo. Though RING1 deletion initially reduced M. tuberculosis (Mtb) infectious load in vivo, increased lung inflammation and impaired immune defense responses were later observed. Moreover, Ring1 knockout exacerbated acute sepsis induced by lipopolysaccharide (LPS) in vivo. Mechanistically, RING1 directly interacts with GSDMD and ubiquitinates the K51 and K168 sites of GSDMD for K48-linked proteasomal degradation, thereby inhibiting pyroptosis. Inhibition of RING1 E3 ligase activity by direct mutation or with the use of small molecule inhibitors increased GSDMD level and cell death during pyroptosis. Our findings reveal that RING1 dictates GSDMD-mediated inflammatory response and host susceptibility to pathogen infection, highlighting RING1 as a potential therapeutic target for combating infectious diseases.

DOI: https://doi.org/10.1038/s41418-025-01527-2
PLoS Pathog. 2025 May 16. 21(5): e1012707

Host PIK3C3 promotes Shigella flexneri spread from cell to cell through vacuole formation.

Steven J Rolland, Zachary J Lifschin, Erin A Weddle, Lauren K Yum, Tsuyoshi Miyake, Daniel A Engel, Hervé F Agaisse.

Shigella flexneri is a human intracellular pathogen responsible for bacillary dysentery (bloody diarrhea). S. flexneri invades colonic epithelial cells and spreads from cell to cell, leading to massive epithelial cell fenestration, a critical determinant of pathogenesis. Cell-to-cell spread relies on actin-based motility, which leads to formation of membrane protrusions, as bacteria project into adjacent cells. Membrane protrusions resolve into intermediate structures termed vacuole-like protrusions (VLPs), which remain attached to the primary infected cell by a membranous tether. The resolution of the membranous tether leads to formation of double-membrane vacuoles (DMVs), from which S. flexneri escapes to gain access to the cytosol of adjacent cells. Here, we identify the class III PI3K family member PIK3C3 as a critical determinant of S. flexneri cell-to-cell spread. Inhibition of PIK3C3 decreased the size of infection foci formed by S. flexneri in HT-29 cells. Tracking experiments using live-fluorescence confocal microscopy showed that PIK3C3 is required for efficient resolution of VLPs into DMVs. PIK3C3-dependent accumulation of PtdIns(3)P at the VLP membrane in adjacent cells correlated with the transient recruitment of the membrane scission machinery component Dynamin 2 at the neck of VLPs at the time of DMV formation. By contrast, Listeria monocytogenes did not form VLPs and protrusions resolved directly into DMVs. However, PIK3C3 was also required for L. monocytogenes dissemination, but at the stage of vacuole escape. Finally, we showed that PIK3C3 inhibition decreased S. flexneri dissemination in the infant rabbit model of shigellosis. We propose a model of Shigella dissemination in which vacuole formation relies on the PIK3C3-dependent accumulation of PtdIns(3)P at the VLP stage of cell-to-cell spread, thereby supporting the resolution of VLPs into DMVs through recruitment of the membrane scission machinery component, DNM2.

DOI: https://doi.org/10.1371/journal.ppat.1012707
Ann Rheum Dis. 2025 May 10. pii: S0003-4967(25)00883-0. [Epub ahead of print]

Investigating endogenous immune-mediated monocyte memory in rheumatoid arthritis.

Anna M Marzeda, Anja Schwenzer, Bogdan S Didov, Kieran Woolcock, Jean-Baptiste Richard, Libby K Jennings, Amélie M Julé, Nan Yang, Sarah Davidson, Steve Sansom, Adam P Cribbs, Calliope A Dendrou, Wyatt W Yue, Carl S Goodyear, Karim Raza, Kim S Midwood.

OBJECTIVES: Inflammation triggered by endogenous stimuli that signal cellular stress or tissue injury must be tightly controlled to balance robust protection from intrinsic danger while avoiding catastrophic destruction of healthy tissues. Here, we assess the contribution of innate memory to this balance.
METHODS: Memory evoked by the extracellular matrix protein tenascin-C, a damage-associated, toll-like receptor 4 (TLR4) agonist, was compared to that induced by the pathogenic TLR4 agonist lipopolysaccharide (LPS) by transcriptomic and epigenetic profiling of monocytes from healthy individuals or people wirh rheumatoid arthritis (RA), and tissue macrophages from the RA synovium.
RESULTS: Tenascin-C reprograms monocyte response to subsequent threats, inducing concomitantly suppressed and enhanced responses to rechallenge. Comparative analysis of tenascin-C and LPS revealed common and distinct gene expression signatures, effects controlled transcriptionally and associated with stimulus-specific epigenetic mediators. Altered responses following rechallenge after priming with tenascin-C were not limited to subsequent TLR4 activation but were evident in response to various pathogenic and endogenous stimuli detected by different receptors. In healthy monocytes primed with tenascin-C, rechallenge with stimuli found at high levels in the joints of people with RA resulted in trained responses that were not induced by LPS, including genes associated with chronic inflammation, tissue destruction, altered metabolism, and poor treatment response in RA. The expression of a large subset of these genes was elevated in monocytes from people with RA in the absence of any stimulation and in RA synovial macrophage populations associated with disease flare. Moreover, higher levels of permissive complexes within key epigenetic nodes and increased bivalent modification creating poised loci within endogenously trained genes were observed in RA cells.
CONCLUSIONS: These data highlight how innate reprogramming during 'sterile' inflammatory diseases contributes to chronicity, uncovering pathways unique to endogenous immune triggers that could provide disease-specific points of intervention without engendering global immune suppression.

DOI: https://doi.org/10.1016/j.ard.2025.03.016
FASEB J. 2025 May 15. 39(9): e70621

Annexin A2 Contributes to Release of Extracellular Vimentin in Response to Inflammation.

Zhiyao Yuan, Z Ostrowska-Podhorodecka, T Cox, M Norouzi, Y Wang, K Robaszkiewicz, M Siatkowska, K Xia, A Ali, M Abovsky, I Jurisica, P Smith, C A McCulloch.

  Vimentin, an abundant intracellular cytoskeletal protein, is secreted into the extracellular space, where it can amplify tissue destruction in inflammatory diseases. The mechanisms by which inflammation promotes the release of extracellular vimentin (ECV) are not defined. In human subjects, we found > twofold higher levels of ECV in gingival crevicular fluid from periodontitis sites with inflammation compared with healthy sites. In cultures of human gingival fibroblasts (hGFs) treated with 1% serum or IL-1β (10 ng/mL) to model tissue injury or inflammation, respectively, we found that 1% serum increased ECV release > 11-fold while IL-1β further enhanced release 17-fold. Mass spectrometry of vimentin immunoprecipitates identified Annexin A2 (AnxA2), a Ca2+-dependent phospholipid-binding protein, as a potential binding protein of ECV, which was confirmed by immunoprecipitation of cultured hGFs and immunostaining of inflamed human gingiva. IL-1β treatment enhanced the abundance of AnxA2 and vimentin in membrane fractions prepared by sucrose gradients of hGF lysates. IL-1β increased colocalization of ECV and AnxA2 at the outer aspect of the plasma membrane of intact hGFs. Knockdown of AnxA2 with siRNA or inhibition of the unconventional secretory pathway reduced ECV release from hGFs. These findings indicate that the production of ECV by hGFs in response to inflammation is mediated by an AnxA2-dependent, unconventional secretory pathway that may play a role in amplification of the inflammatory response.

Keywords:  Annexin A2; extracellular vimentin; periodontitis; secretion; unconventional protein secretion pathways

DOI:  https://doi.org/10.1096/fj.202500793R
Life Sci Alliance. 2025 Aug;pii: e202403076. [Epub ahead of print]8(8):

A fluorescent sensor for real-time monitoring of DPP8/9 reveals crucial roles in immunity and cancer.

Konstantin Weiss, Yelizaveta Agarkova, Alexandra Zwosta, Sarah Hoevel, Ann-Kathrin Himmelreich, Magdalena Shumanska, Julia Etich, Gereon Poschmann, Bent Brachvogel, Ivan Bogeski, Dirk Mielenz, Jan Riemer.

Dipeptidyl peptidases 8 and 9 (DPP8/9) are critical for the quality control of mitochondrial and endoplasmic reticulum protein import, immune regulation, cell adhesion, and cell migration. Dysregulation of DPP8/9 is associated with pathologies including tumorigenesis and inflammation. Commonly, DPP8/9 activity is analysed by in vitro assays using artificial substrates, which allow neither continuously monitoring DPP8/9 activity in individual, living cells nor detecting effects from endogenous interactors and posttranslational modifications. Here, we developed DiPAK (for DPP8/9 activity sensor based on AK2), a ratiometric genetically encoded fluorescent sensor, which enables studying DPP8/9 activity in living cells. Using DiPAK, we determined the dynamic range of DPP8/9 activity in cells overexpressing or lacking DPP9. We identified distinct activity levels among melanoma cell lines and found that LPS-induced primary B-cell activation depends on DPP8/9 as the absence of DPP8/9 activity results in apoptotic but not pyroptotic cell death. Consistently, we observed increasing DPP8/9 activity during B-cell maturation. Overall, DiPAK is a versatile tool for real-time single-cell monitoring of DPP8/9 activity in a broad range of cells and organisms.

DOI: https://doi.org/10.26508/lsa.202403076
J Am Chem Soc. 2025 May 15.

Pyrazolone-Modified Photosensitizers for Precise Cell Membrane Rupture to Enhance Cancer Immunotherapy.

Yingchao Chen, Tao Xiong, Mingrui Gu, Mingle Li, Xiaoqiang Chen, Lei Wang, Jiangli Fan, Xiaojun Peng.

The advancement of immunotherapy aims to achieve complete tumor eradication. However, several critical challenges hinder the efficacy of conventional phototherapy-mediated immune responses, including insufficient immunogenicity and the presence of an immunosuppressive tumor microenvironment. Nonprogrammed cell death, as a highly immunogenic pathway, offers a promising strategy to enhance immune responses. Herein, a membrane-anchored photodynamic immunotherapy agent, PNBSe, was developed by conjugating a selenium-substituted benzophenothiazine photosensitizer with a pyrazolone group, enabling membrane targeting via pyrazolone-protein interactions. Upon light irradiation, PNBSe induced rapid and intense cell necrosis characterized by significant cell membrane rupture, organelle swelling, and content leakage. Further investigations demonstrated that PNBSe activated inflammatory signaling pathways, induced immunogenic cell death, and reshaped the immunosuppressive tumor microenvironment, ultimately promoting systemic antitumor immune responses in vivo. This membrane-anchored small molecule provides a novel perspective for promoting cancer photodynamic immunotherapy.

DOI: https://doi.org/10.1021/jacs.5c02764
Cancer Res Commun. 2025 May 16.

NLRP3 inflammasome activation expands immunosuppressive myeloid stroma and antagonizes the therapeutic benefit of STING activation in glioblastoma.

Spencer T Lea, Chao-Hsien Chen, Jun Wei, Ivana William, Ines Lopez Del Castillo, Michael A Curran.

Glioblastoma is the most common and deadly primary brain malignancy and is clinically refractory to immunotherapy. Active NLRP3 inflammasome signaling and IL-1β secretion has been observed in glioblastoma (GBM), and NLRP3-driven myeloid derived suppressor cell (MDSC) recruitment can mediate cancer immune evasion. Agonists of the cytosolic dsDNA-sensing Stimulator of Interferon Genes (STING) pathway can mediate proinflammatory conversion of cancer MDSC; however, secretion of the NLRP3 products IL-1β and IL-18 has also been observed in certain myeloid populations following STING activation. Here we aimed to determine both the potential mechanistic synergy between STING and NLRP3 agonists, and the effects of this innate immune combination on the GBM tumor immune landscape. We find that STING activation does not prime pro-IL-1β expression for activated NLRP3 inflammasome secretion. In subcutaneous GL261 GBM, we show that NLRP3 activation expands the immunosuppressive myeloid stroma primarily via granulocytic MDSC recruitment and antagonizes the benefit of STING activation. In brain GL261, we find that NLRP3 activation expands granulocytic MDSC but does not antagonize the therapeutic benefit of STING activation. Finally, we report that mesenchymal subtype GBM tumors have elevated neutrophil, IL-1β , and NLRP3 gene expression, a setting where our data suggests NLRP3 activation could counteract STING agonists.

DOI: https://doi.org/10.1158/2767-9764.CRC-23-0189
J Leukoc Biol. 2025 May 14. pii: qiaf061. [Epub ahead of print]

Fever-range temperature alters continual efferocytosis mediated by mouse pro-inflammatory macrophages.

Mathieu Vetter, Melissa Maraux, Francis Bonnefoy, Ludivine Dal Zuffo, Baptiste Lamarthée, Gwenaël Rolin, Audrey Wetzel, Sylvain Perruche, Paul Peixoto, Philippe Saas.

  Fever, a cardinal sign of inflammation, has been shown to modulate macrophage functions. Here, we investigate whether fever affects macrophage efferocytosis. This process is essential for the resolution of inflammation and the return to homeostasis with the reprogramming of macrophages towards a pro-resolving phenotype. Using primary mouse bone marrow-derived macrophages stimulated with lipopolysaccharide and interferon-γ (i.e., pro-inflammatory macrophages), we first validated that exposure to febrile temperature (39.5°C) induced a heat shock protein response. Then, we observed that febrile temperature decreased the capacity of pro-inflammatory macrophages to uptake apoptotic cells. This reduced efferocytic capacity of macrophages exposed to febrile temperature resulted from a decreased capacity to interact with apoptotic cells and to internalize these dying cells. Exposure to febrile temperature reduced the cell motility of macrophages in response to apoptotic cells, as assessed by IncuCyte® live-cell imaging. RNA sequencing analysis of pro-inflammatory macrophages exposed to febrile temperature identified an upregulation of the Adam17 gene. As this gene encodes a protease that sheds the efferocytic receptor Mer, we determined cell surface expression of Mer and quantified soluble Mer in the culture supernatants of pro-inflammatory macrophages exposed to febrile temperature. While febrile hyperthermia induced the Mer cleavage from the cell surface of pro-inflammatory macrophages, ADAM17 inhibition during exposure to febrile temperature did not restore the efferocytic capacity of pro-inflammatory macrophages. Thus, reduction of Mer expression induced by hyperthermia did not represent the main mechanism explaining reduced efferocytosis. Nevertheless, our work suggests that fever, by decreasing efferocytic capacity of macrophages, maintains their pro-inflammatory state.

Keywords:  Efferocytosis; apoptotic cells; fever; inflammation; macrophage

DOI:  https://doi.org/10.1093/jleuko/qiaf061
Mol Immunol. 2025 May 14. pii: S0161-5890(25)00130-0. [Epub ahead of print]183 145-155

Targeted p38 mitogen-activated protein kinase inhibition potently augment inflammatory responses of human macrophages toward Staphylococcus aureus.

Astrid Lund, David Moffat, Stine Dam Jepsen, Claus Desler, Lars Andresen, Søren Bregenholt, Venkat Reddy, Søren Skov.

  Antibiotic-resistant Staphylococcus aureus (S. aureus) is a growing challenge for human health and novel treatment options are needed. Here we examine a novel therapeutic approach against persistent S. aureus infections based on monocyte/macrophage specific inhibition of the p38α mitogen-activated protein kinase activity. Since systemic p38α kinase inhibition cause aberrant toxicity, we used the myeloid specific p38α kinase inhibitor, MPL-5821. P38α kinase inhibition caused a potent increase in the pro-inflammatory profile of human macrophages after exposure to S. aureus, including upregulation of M1-markers and induction of pro-inflammatory cytokines including IFN-γ, TNF-α, IL-1β, IL12p70, IL-6 and IL-8, as well as an increase in phagocytic capacities. These pro-inflammatory signals were only seen after combined S. aureus exposure and p38α inhibition. Macrophages are often regulated by changes in intracellular metabolism. In agreement with this, the combination of S. aureus exposure and p38α inhibition led to specific changes in glycolytic and mitochondrial activity within the responding macrophages. Our study thus unravels a novel and specific activation of macrophages that augment their response toward S. aureus, without causing aberrant inflammation. This constitutes a unique non-antibiotic therapeutic approach that can potentially be used against persistent S. aureus infection.

Keywords:  Immunology; Macrophage metabolism; Macrophage polarization; Staphylococcus aureus; p38 MAPK inhibition

DOI:  https://doi.org/10.1016/j.molimm.2025.05.010
Front Cell Dev Biol. 2025 ;13 1570569

A review of cell death pathways in hemorrhagic stroke.

John H Rinald, Carol M Troy.

  Hemorrhagic stroke is a debilitating neurological disease, affecting millions worldwide. Characterized by bleeding in the brain, it is caused by a breakdown of the blood-brain barrier (BBB) and causes damage through the presence of iron in the brain, immune activation and increased intracranial pressure. The goal of this mini-review is to explore the signaling pathways that lead to cell death that are a part of disease progression in hemorrhagic stroke. This mini-review will highlight clinical observations and data, while also incorporating findings using preclinical disease models. There are important roles for apoptosis, necroptosis, necrosis, autophagy, ferroptosis, and pyroptosis in hemorrhagic stroke. Recent work has highlighted the interplay between these phenomena, providing key regulators as potential therapeutic targets, including reactive oxygen species, iron metabolism, and caspases. Therapeutic strategies that can delay or counteract the cytotoxic effects of hemorrhage can improve clinical outcomes in hemorrhagic stroke patients.

Keywords:  apoptosis; caspases; cell death; hemorrhagic stroke; inflammation; neurovascular disease

DOI:  https://doi.org/10.3389/fcell.2025.1570569
Cell Rep. 2025 May 14. pii: S2211-1247(25)00491-7. [Epub ahead of print]44(5): 115720

HSPA9 contributes to tumor progression and ferroptosis resistance by enhancing USP14-driven SLC7A11 deubiquitination in multiple myeloma.

Na Shen, Yuan Xia, Xuxing Shen, Wei Hua, Min Shi, Lijuan Chen.

  Ferroptosis, a regulated cell death triggered by overload-dependent lipid peroxidation, is implicated in multiple human cancers. The mechanisms underlying ferroptosis in multiple myeloma (MM) remain enigmatic. Here, we confirmed that HSPA9 is overexpressed in MM samples and correlates with unfavorable outcomes. Functionally, HSPA9 enhances MM cell viability, ferroptosis resistance, and tumorigenicity, suggesting its oncogenic role. Proteomics screening identified SLC7A11, a key ferroptosis suppressor, as a HSPA9 interactor. Mechanistically, HSPA9 serves as a bridge to strengthen the interaction between USP14 and SLC7A11, modulating USP14-mediated SLC7A11 deubiquitination. Furthermore, the inhibition of USP14 with IU1 enhances the SLC7A11 ubiquitination and degradation, promoting ferroptosis and showing therapeutic efficacy in MM xenograft models. Clinically, HSPA9, USP14, and SLC7A11 expression are positively correlated in MM samples, which have a prognostic value. Our study reveals HSPA9-USP14-SLC7A11 axis as a key regulator of ferroptosis in MM and a potential therapeutic target.

Keywords:  CP: Cancer; HSPA9; SLC7A11; USP14; deubiquitination; multiple myeloma

DOI:  https://doi.org/10.1016/j.celrep.2025.115720
Front Immunol. 2025 ;16 1572927

Mitochondrial metabolism is rapidly re-activated in mature neutrophils to support stimulation-induced response.

Jorgo Lika, James A Votava, Rupsa Datta, Carlos A Mellado Fritz, Aleksandr M Kralovec, Frances M Smith, Anna Huttenlocher, Melissa C Skala, Jing Fan.

   Introduction: Neutrophils are highly abundant innate immune cells that are constantly produced from myeloid progenitors in the bone marrow. Differentiated neutrophils can perform an arsenal of effector functions critical for host defense. This study aims to quantitatively understand neutrophil mitochondrial metabolism throughout differentiation and activation, and to elucidate the impact of mitochondrial metabolism on neutrophil functions.
Methods: To study metabolic remodeling throughout neutrophil differentiation, murine ER-Hoxb8 myeloid progenitor-derived neutrophils and human induced pluripotent stem cell-derived neutrophils were assessed as models. To study the metabolic remodeling upon neutrophil activation, differentiated ER-Hoxb8 neutrophils and primary human neutrophils were activated with various stimuli, including ionomycin, monosodium urate crystals, and phorbol 12-myristate 13-acetate. Characterization of cellular metabolism by isotopic tracing, extracellular flux analysis, metabolomics, and fluorescence-lifetime imaging microscopy revealed dynamic changes in mitochondrial metabolism.
Results: As neutrophils mature, mitochondrial metabolism decreases drastically, energy production is offloaded from oxidative phosphorylation, and glucose oxidation through the TCA cycle is substantially reduced. Nonetheless, mature neutrophils retain the capacity for mitochondrial metabolism. Upon stimulation with certain stimuli, TCA cycle is rapidly activated. Mitochondrial pyruvate carrier inhibitors reduce this re-activation of the TCA cycle and inhibit the release of neutrophil extracellular traps. Treatment with these inhibitors also impacts neutrophil redox status, migration, and apoptosis without significantly changing overall bioenergetics.
Conclusions: Together, these results demonstrate that mitochondrial metabolism is dynamically remodeled and plays a significant role in neutrophils. Furthermore, these findings point to the therapeutic potential of mitochondrial pyruvate carrier inhibitors in a range of conditions where dysregulated neutrophil response drives inflammation and contributes to pathology.

Keywords:  TCA cycle; metabolism; mitochondria; neutrophil; neutrophil extracellular traps

DOI:  https://doi.org/10.3389/fimmu.2025.1572927
Nat Rev Mol Cell Biol. 2025 May 14.

Molecular machineries shaping the mitochondrial inner membrane.

Oliver Daumke, Martin van der Laan.

Mitochondria display intricately shaped deep invaginations of the mitochondrial inner membrane (MIM) termed cristae. This peculiar membrane architecture is essential for diverse mitochondrial functions, such as oxidative phosphorylation or the biosynthesis of cellular building blocks. Conserved protein nano-machineries such as F1Fo-ATP synthase oligomers and the mitochondrial contact site and cristae organizing system (MICOS) act as adaptable protein-lipid scaffolds controlling MIM biogenesis and its dynamic remodelling. Signal-dependent rearrangements of cristae architecture and MIM fusion events are governed by the dynamin-like GTPase optic atrophy 1 (OPA1). Recent groundbreaking structural insights into these nano-machineries have considerably advanced our understanding of the functional architecture of mitochondria. In this Review, we discuss how the MIM-shaping machineries cooperate to control cristae and crista junction dynamics, including MIM fusion, in response to cellular signalling pathways. We also explore how mutations affecting MIM-shaping machineries compromise mitochondrial functions.

DOI: https://doi.org/10.1038/s41580-025-00854-z