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Singh S, Bensalem J, Hein LK, Casey A, Mäkinen VP, Sargeant TJ. epHero - a tandem-fluorescent probe to track the fate of apoptotic cells during efferocytosis. Cell Death Discov 2024; 10:179. [PMID: 38632247 PMCID: PMC11024195 DOI: 10.1038/s41420-024-01952-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 04/01/2024] [Accepted: 04/08/2024] [Indexed: 04/19/2024] Open
Abstract
The efficient removal of apoptotic cells via efferocytosis is critical for maintaining optimal tissue function. This involves the binding and engulfment of apoptotic cells by phagocytes and the subsequent maturation of the phagosome, culminating in lysosomal fusion and cargo destruction. However, current approaches to measure efferocytosis rely on labelling apoptotic targets with fluorescent dyes, which do not sufficiently distinguish between changes to the engulfment and acidification of apoptotic material. To address this limitation, we have developed a genetically coded ratiometric probe epHero which when expressed in the cytoplasm of target cells, bypasses the need for additional labelling steps. We demonstrate that epHero is a pH-sensitive reporter for efferocytosis and can be used to simultaneously track changes to apoptotic cell uptake and acidification, both in vitro and in mice. As proof-of-principle, we modify extracellular nutrition to show how epHero can distinguish between changes to cargo engulfment and acidification. Thus, tracking efferocytosis with epHero is a simple, cost-effective improvement on conventional techniques.
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Affiliation(s)
- Sanjna Singh
- South Australian Health and Medical Research Institute, Adelaide, SA, Australia
- University of Adelaide, Adelaide, SA, Australia
| | - Julien Bensalem
- South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Leanne K Hein
- South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Aaron Casey
- South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Ville-Petteri Mäkinen
- Research Unit of Population Health, Faculty of Medicine, University of Oulu, Oulu, Finland
- Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Timothy J Sargeant
- South Australian Health and Medical Research Institute, Adelaide, SA, Australia.
- University of Adelaide, Adelaide, SA, Australia.
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Brown GC. Cell death by phagocytosis. Nat Rev Immunol 2024; 24:91-102. [PMID: 37604896 DOI: 10.1038/s41577-023-00921-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2023] [Indexed: 08/23/2023]
Abstract
Cells can die as a consequence of being phagocytosed by other cells - a form of cell death that has been called phagotrophy, cell cannibalism, programmed cell removal and primary phagocytosis. However, these are all different manifestations of cell death by phagocytosis (termed 'phagoptosis' for short). The engulfed cells die as a result of cytotoxic oxidants, peptides and degradative enzymes within acidic phagolysosomes. Cell death by phagocytosis was discovered by Metchnikov in the 1880s, but was neglected until recently. It is now known to contribute to developmental cell death in nematodes, Drosophila and mammals, and is central to innate and adaptive immunity against pathogens. Cell death by phagocytosis mediates physiological turnover of erythrocytes and other leucocytes, making it the most abundant form of cell death in the mammalian body. Immunity against cancer is also partly mediated by macrophage phagocytosis of cancer cells, but cancer cells can also phagocytose host cells and other cancer cells in order to survive. Recent evidence indicates neurodegeneration and other neuropathologies can be mediated by microglial phagocytosis of stressed neurons. Thus, despite cell death by phagocytosis being poorly recognized, it is one of the oldest, commonest and most important forms of cell death.
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Affiliation(s)
- Guy C Brown
- Department of Biochemistry, University of Cambridge, Cambridge, UK.
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3
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Crespo-Yanez X, Oddy J, Lamrabet O, Jauslin T, Marchetti A, Cosson P. Sequential action of antibacterial effectors in Dictyostelium discoideum phagosomes. Mol Microbiol 2023; 119:74-85. [PMID: 36416195 PMCID: PMC10107278 DOI: 10.1111/mmi.15004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 11/08/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022]
Abstract
Mammalian professional phagocytic cells ingest and kill invading microorganisms and prevent the development of bacterial infections. Our understanding of the sequence of events that results in bacterial killing and permeabilization in phagosomes is still largely incomplete. In this study, we used the Dictyostelium discoideum amoeba as a model phagocyte to study the fate of the bacteria Klebsiella pneumoniae inside phagosomes. Our analysis distinguishes three consecutive phases: bacteria first lose their ability to divide (killing), then their cytosolic content is altered (permeabilization), and finally their DNA is degraded (digestion). Phagosomal acidification and production of free radicals are necessary for rapid killing, membrane-permeabilizing proteins BpiC and AlyL are required for efficient permeabilization. These results illustrate how a combination of genetic and microscopical tools can be used to finely dissect the molecular events leading to bacterial killing and permeabilization in a maturing phagosome.
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Affiliation(s)
- Xènia Crespo-Yanez
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Joseph Oddy
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Otmane Lamrabet
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Tania Jauslin
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Anna Marchetti
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Pierre Cosson
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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Fortuna A, Collalto D, Schiaffi V, Pastore V, Visca P, Ascenzioni F, Rampioni G, Leoni L. The Pseudomonas aeruginosa DksA1 protein is involved in H 2O 2 tolerance and within-macrophages survival and can be replaced by DksA2. Sci Rep 2022; 12:10404. [PMID: 35729352 PMCID: PMC9213440 DOI: 10.1038/s41598-022-14635-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 06/09/2022] [Indexed: 12/02/2022] Open
Abstract
In Gram-negative pathogens, the stringent response regulator DksA controls the expression of hundreds of genes, including virulence-related genes. Interestingly, Pseudomonas aeruginosa has two functional DksA paralogs: DksA1 is constitutively expressed and has a zinc-finger motif, while DksA2 is expressed only under zinc starvation conditions and does not contain zinc. DksA1 stimulates the production of virulence factors in vitro and is required for full pathogenicity in vivo. DksA2 can replace these DksA1 functions. Here, the role of dksA paralogs in P. aeruginosa tolerance to H2O2-induced oxidative stress has been investigated. The P. aeruginosa dksA1 dksA2 mutant showed impaired H2O2 tolerance in planktonic and biofilm-growing cultures and increased susceptibility to macrophages-mediated killing compared to the wild type. Complementation with either dksA1 or dksA2 genes restored the wild type phenotypes. The DksA-dependent tolerance to oxidative stress involves, at least in part, the positive transcriptional control of both katA and katE catalase-encoding genes. These data support the hypothesis that DksA1 and DksA2 are eco-paralogs with indistinguishable function but optimal activity under different environmental conditions, and highlight their mutual contribution to P. aeruginosa virulence.
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Affiliation(s)
| | | | - Veronica Schiaffi
- Department of Molecular and Cellular Biology "Charles Darwin", University Roma Sapienza, Rome, Italy
| | - Valentina Pastore
- Department of Molecular and Cellular Biology "Charles Darwin", University Roma Sapienza, Rome, Italy
| | - Paolo Visca
- Department of Science, University Roma Tre, Rome, Italy.,IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Fiorentina Ascenzioni
- Department of Molecular and Cellular Biology "Charles Darwin", University Roma Sapienza, Rome, Italy
| | - Giordano Rampioni
- Department of Science, University Roma Tre, Rome, Italy.,IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Livia Leoni
- Department of Science, University Roma Tre, Rome, Italy.
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Riazanski V, Mauleon G, Zimnicka AM, Chen S, Nelson DJ. Phagosomal chloride dynamics in the alveolar macrophage. iScience 2022; 25:103636. [PMID: 35024579 PMCID: PMC8733233 DOI: 10.1016/j.isci.2021.103636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 10/11/2021] [Accepted: 12/14/2021] [Indexed: 12/04/2022] Open
Abstract
Acidification in intracellular organelles is tightly linked to the influx of Cl- counteracting proton translocation by the electrogenic V-ATPase. We quantified the dynamics of Cl- transfer accompanying cargo incorporation into single phagosomes in alveolar macrophages (AMs). Phagosomal Cl- concentration and acidification magnitude were followed in real time with maximal acidification achieved at levels of approximately 200 mM. Live cell confocal microscopy verified that phagosomal Cl- influx utilized predominantly the Cl- channel CFTR. Relative levels of elemental chlorine (Cl) in hard X-ray fluorescence microprobe (XFM) analysis within single phagosomes validated the increase in Cl- content. XFM revealed the complex interplay between elemental K content inside the phagosome and changes in Cl- during phagosomal particle uptake. Cl- -dependent changes in phagosomal membrane potential were obtained using second harmonic generation (SHG) microscopy. These studies provide a mechanistic insight for screening studies in drug development targeting pulmonary inflammatory disease.
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Affiliation(s)
- Vladimir Riazanski
- The University of Chicago, Department of Pharmacological and Physiological Sciences, 947 E. 58th Street, MC 0926, Chicago, IL 60637, USA
| | - Gerardo Mauleon
- The University of Chicago, Department of Pharmacological and Physiological Sciences, 947 E. 58th Street, MC 0926, Chicago, IL 60637, USA
| | - Adriana M. Zimnicka
- The University of Chicago, Department of Pharmacological and Physiological Sciences, 947 E. 58th Street, MC 0926, Chicago, IL 60637, USA
| | - Si Chen
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Deborah J. Nelson
- The University of Chicago, Department of Pharmacological and Physiological Sciences, 947 E. 58th Street, MC 0926, Chicago, IL 60637, USA
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Liu JX, Chao XY, Chen P, Wang YD, Su TJ, Li M, Xu RY, Wu Q. Transcriptome Analysis of Selenium-Treated Porcine Alveolar Macrophages Against Lipopolysaccharide Infection. Front Genet 2021; 12:645401. [PMID: 33747052 PMCID: PMC7970123 DOI: 10.3389/fgene.2021.645401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/02/2021] [Indexed: 11/25/2022] Open
Affiliation(s)
- Jia-Xuan Liu
- Animal Science and Technology College, Beijing University of Agriculture, Beijing, China
| | - Xin-Yu Chao
- Animal Science and Technology College, Beijing University of Agriculture, Beijing, China
| | - Peng Chen
- Animal Science and Technology College, Beijing University of Agriculture, Beijing, China
| | - Yi-Ding Wang
- Animal Science and Technology College, Beijing University of Agriculture, Beijing, China
| | - Tong-Jian Su
- Animal Science and Technology College, Beijing University of Agriculture, Beijing, China
| | - Meng Li
- Animal Science and Technology College, Beijing University of Agriculture, Beijing, China
| | - Ru-Yu Xu
- Animal Science and Technology College, Beijing University of Agriculture, Beijing, China
| | - Qiong Wu
- Animal Science and Technology College, Beijing University of Agriculture, Beijing, China
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How Phagocytic Cells Kill Different Bacteria: a Quantitative Analysis Using Dictyostelium discoideum. mBio 2021; 12:mBio.03169-20. [PMID: 33593980 PMCID: PMC8545105 DOI: 10.1128/mbio.03169-20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ingestion and killing of bacteria by phagocytic cells protect the human body against infections. While many mechanisms have been proposed to account for bacterial killing in phagosomes, their relative importance, redundancy, and specificity remain unclear. In this study, we used the Dictyostelium discoideum amoeba as a model phagocyte and quantified the requirement of 11 individual gene products, including nine putative effectors, for the killing of bacteria. This analysis revealed that radically different mechanisms are required to kill Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis AlyL, a lysozyme-like protein equipped with a distinct bacteriolytic region, plays a specific role in the intracellular killing of K. pneumoniae, with assistance from BpiC and Aoah, two lipopolysaccharide (LPS)-binding proteins. Rapid killing of E. coli and P. aeruginosa requires the presence of BpiC and of the NoxA NADPH oxidase. No single effector tested is essential for rapid killing of S. aureus or B. subtilis Overall, our observations reveal an unsuspected degree of specificity in the elimination of bacteria in phagosomes.IMPORTANCE Phagocytic cells ingest and kill bacteria, a process essential for the defense of the human body against infections. Many potential killing mechanisms have been identified in phagocytic cells, including free radicals, toxic ions, enzymes, and permeabilizing peptides. Yet fundamental questions remain unanswered: what is the relative importance of these mechanisms, how redundant are they, and are different mechanisms used to kill different species of bacteria? We addressed these questions using Dictyostelium discoideum, a model phagocytic cell amenable to genetic manipulations and quantitative analysis. Our results reveal that vastly different mechanisms are required to kill different species of bacteria. This very high degree of specificity was unexpected and indicates that a lot remains to be discovered about how phagocytic cells eliminate bacteria.
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