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Stegmann F, Diersing C, Lepenies B. Legionella pneumophila modulates macrophage functions through epigenetic reprogramming via the C-type lectin receptor Mincle. iScience 2024; 27:110700. [PMID: 39252966 PMCID: PMC11382120 DOI: 10.1016/j.isci.2024.110700] [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] [Received: 10/20/2023] [Revised: 12/12/2023] [Accepted: 08/06/2024] [Indexed: 09/11/2024] Open
Abstract
Legionella pneumophila is a pathogen which can lead to a severe form of pneumonia in humans known as Legionnaires disease after replication in alveolar macrophages. Viable L. pneumophila actively secrete effector molecules to modulate the host's immune response. Here, we report that L. pneumophila-derived factors reprogram macrophages into a tolerogenic state, a process to which the C-type lectin receptor Mincle (CLEC4E) markedly contributes. The underlying epigenetic state is characterized by increases of the closing mark H3K9me3 and decreases of the opening mark H3K4me3, subsequently leading to the reduced secretion of the cytokines TNF, IL-6, IL-12, the production of reactive oxygen species, and cell-surface expression of MHC-II and CD80 upon re-stimulation. In summary, these findings provide important implications for our understanding of Legionellosis and the contribution of Mincle to reprogramming of macrophages by L. pneumophila.
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Affiliation(s)
- Felix Stegmann
- Institute for Immunology, University of Veterinary Medicine Hannover, 30559 Hanover, Lower Saxony, Germany
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hanover, Lower Saxony, Germany
| | - Christina Diersing
- Institute for Immunology, University of Veterinary Medicine Hannover, 30559 Hanover, Lower Saxony, Germany
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hanover, Lower Saxony, Germany
| | - Bernd Lepenies
- Institute for Immunology, University of Veterinary Medicine Hannover, 30559 Hanover, Lower Saxony, Germany
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hanover, Lower Saxony, Germany
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2
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Schmidt S, Mondino S, Gomez-Valero L, Escoll P, Mascarenhas DPA, Gonçalves A, Camara PHM, Garcia Rodriguez FJ, Rusniok C, Sachse M, Moya-Nilges M, Fontaine T, Zamboni DS, Buchrieser C. The unique Legionella longbeachae capsule favors intracellular replication and immune evasion. PLoS Pathog 2024; 20:e1012534. [PMID: 39259722 PMCID: PMC11419355 DOI: 10.1371/journal.ppat.1012534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 09/23/2024] [Accepted: 08/26/2024] [Indexed: 09/13/2024] Open
Abstract
Legionella longbeachae and Legionella pneumophila are the most common causative agents of Legionnaires' disease. While the clinical manifestations caused by both species are similar, species-specific differences exist in environmental niches, disease epidemiology, and genomic content. One such difference is the presence of a genomic locus predicted to encode a capsule. Here, we show that L. longbeachae indeed expresses a capsule in post-exponential growth phase as evidenced by electron microscopy analyses, and that capsule expression is abrogated when deleting a capsule transporter gene. Capsule purification and its analysis via HLPC revealed the presence of a highly anionic polysaccharide that is absent in the capsule mutant. The capsule is important for replication and virulence in vivo in a mouse model of infection and in the natural host Acanthamoeba castellanii. It has anti-phagocytic function when encountering innate immune cells such as human macrophages and it is involved in the low cytokine responses in mice and in human monocyte derived macrophages, thus dampening the innate immune response. Thus, the here characterized L. longbeachae capsule is a novel virulence factor, unique among the known Legionella species, which may aid L. longbeachae to survive in its specific niches and which partly confers L. longbeachae its unique infection characteristics.
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Affiliation(s)
- Silke Schmidt
- Institut Pasteur, Université Paris Cité, Biologie des Bactéries Intracellulaires, CNRS UMR 6047, Paris, France
- Sorbonne Université, Collège Doctoral, Paris, France
| | - Sonia Mondino
- Institut Pasteur, Université Paris Cité, Biologie des Bactéries Intracellulaires, CNRS UMR 6047, Paris, France
| | - Laura Gomez-Valero
- Institut Pasteur, Université Paris Cité, Biologie des Bactéries Intracellulaires, CNRS UMR 6047, Paris, France
| | - Pedro Escoll
- Institut Pasteur, Université Paris Cité, Biologie des Bactéries Intracellulaires, CNRS UMR 6047, Paris, France
| | | | - Augusto Gonçalves
- Department of Cell Biology, Medical School of Ribeirão Preto, FMRP/USP, Ribeirão Preto, Brazil
| | - Pedro H. M. Camara
- Department of Cell Biology, Medical School of Ribeirão Preto, FMRP/USP, Ribeirão Preto, Brazil
| | | | - Christophe Rusniok
- Institut Pasteur, Université Paris Cité, Biologie des Bactéries Intracellulaires, CNRS UMR 6047, Paris, France
| | - Martin Sachse
- UTechS UBI, Centre de Ressources et Recherches Technologiques, Institut Pasteur, Paris, France
| | - Maryse Moya-Nilges
- UTechS UBI, Centre de Ressources et Recherches Technologiques, Institut Pasteur, Paris, France
| | - Thierry Fontaine
- Biologie et Pathogénicité fongiques, Institut Pasteur, Paris, France
| | - Dario S. Zamboni
- Department of Cell Biology, Medical School of Ribeirão Preto, FMRP/USP, Ribeirão Preto, Brazil
| | - Carmen Buchrieser
- Institut Pasteur, Université Paris Cité, Biologie des Bactéries Intracellulaires, CNRS UMR 6047, Paris, France
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3
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Klatt AB, Diersing C, Lippmann J, Mayer-Lambertz S, Stegmann F, Fischer S, Caesar S, Fiocca Vernengo F, Hönzke K, Hocke AC, Ruland J, Witzenrath M, Lepenies B, Opitz B. CLEC12A Binds to Legionella pneumophila but Has No Impact on the Host's Antibacterial Response. Int J Mol Sci 2023; 24:ijms24043891. [PMID: 36835297 PMCID: PMC9967056 DOI: 10.3390/ijms24043891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 02/10/2023] [Accepted: 02/12/2023] [Indexed: 02/17/2023] Open
Abstract
Legionella pneumophila is an intracellular pathogen that can cause severe pneumonia after the inhalation of contaminated aerosols and replication in alveolar macrophages. Several pattern recognition receptors (PRRs) have been identified that contribute to the recognition of L. pneumophila by the innate immune system. However, the function of the C-type lectin receptors (CLRs), which are mainly expressed by macrophages and other myeloid cells, remains largely unexplored. Here, we used a library of CLR-Fc fusion proteins to search for CLRs that can bind the bacterium and identified the specific binding of CLEC12A to L. pneumophila. Subsequent infection experiments in human and murine macrophages, however, did not provide evidence for a substantial role of CLEC12A in controlling innate immune responses to the bacterium. Consistently, antibacterial and inflammatory responses to Legionella lung infection were not significantly influenced by CLEC12A deficiency. Collectively, CLEC12A is able to bind to L. pneumophila-derived ligands but does not appear to play a major role in the innate defense against L. pneumophila.
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Affiliation(s)
- Ann-Brit Klatt
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| | - Christina Diersing
- Institute for Immunology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Juliane Lippmann
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
- Max Planck Institute for Infection Biology, Vector Biology, 10117 Berlin, Germany
| | - Sabine Mayer-Lambertz
- Institute for Immunology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Felix Stegmann
- Institute for Immunology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Swantje Fischer
- Institute for Immunology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Sandra Caesar
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| | - Facundo Fiocca Vernengo
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| | - Katja Hönzke
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
- Faculty of Health Sciences Brandenburg, Brandenburg University of Technology Cottbus—Senftenberg, 03046 Cottbus, Germany
| | - Andreas C. Hocke
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
- German Center for Lung Research (DZL), Augustenburger Platz 1, 13353 Berlin, Germany
| | - Jürgen Ruland
- Institute of Clinical Chemistry and Pathobiochemistry, School of Medicine, Technical University of Munich, 80333 Munich, Germany
- Center for Translational Cancer Research (TranslaTUM), 81675 Munich, Germany
- German Cancer Consortium (DKTK), Partner Site Munich, 80336 Munich, Germany
- German Research Center (DKFZ), 69120 Heidelberg, Germany
- German Center for Infection Research (DZIF), Partner Site Munich, 17493 Greifswald, Germany
| | - Martin Witzenrath
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
- German Center for Lung Research (DZL), Augustenburger Platz 1, 13353 Berlin, Germany
| | - Bernd Lepenies
- Institute for Immunology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
- Correspondence: (B.L.); (B.O.)
| | - Bastian Opitz
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
- German Center for Lung Research (DZL), Augustenburger Platz 1, 13353 Berlin, Germany
- Correspondence: (B.L.); (B.O.)
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4
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Human macrophages utilize a wide range of pathogen recognition receptors to recognize Legionella pneumophila, including Toll-Like Receptor 4 engaging Legionella lipopolysaccharide and the Toll-like Receptor 3 nucleic-acid sensor. PLoS Pathog 2021; 17:e1009781. [PMID: 34280250 PMCID: PMC8321404 DOI: 10.1371/journal.ppat.1009781] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 07/29/2021] [Accepted: 07/03/2021] [Indexed: 12/15/2022] Open
Abstract
Cytokines made by macrophages play a critical role in determining the course of Legionella pneumophila infection. Prior murine-based modeling indicated that this cytokine response is initiated upon recognition of L. pneumophila by a subset of Toll-like receptors, namely TLR2, TLR5, and TLR9. Through the use of shRNA/siRNA knockdowns and subsequently CRISPR/Cas9 knockouts (KO), we determined that TRIF, an adaptor downstream of endosomal TLR3 and TLR4, is required for full cytokine secretion by human primary and cell-line macrophages. By characterizing a further set of TLR KO's in human U937 cells, we discerned that, contrary to the viewpoint garnered from murine-based studies, TLR3 and TLR4 (along with TLR2 and TLR5) are in fact vital to the macrophage response in the early stages of L. pneumophila infection. This conclusion was bolstered by showing that i) chemical inhibitors of TLR3 and TLR4 dampen the cytokine output of primary human macrophages and ii) transfection of TLR3 and TLR4 into HEK cells conferred an ability to sense L. pneumophila. TLR3- and TLR4-dependent cytokines promoted migration of human HL-60 neutrophils across an epithelial layer, pointing to the biological importance for the newfound signaling pathway. The response of U937 cells to L. pneumophila LPS was dependent upon TLR4, a further contradiction to murine-based studies, which had concluded that TLR2 is the receptor for Legionella LPS. Given the role of TLR3 in sensing nucleic acid (i.e., dsRNA), we utilized newly-made KO U937 cells to document that DNA-sensing by cGAS-STING and DNA-PK are also needed for the response of human macrophages to L. pneumophila. Given the lack of attention given them in the bacterial field, C-type lectin receptors were similarly examined; but, they were not required. Overall, this study arguably represents the most extensive, single-characterization of Legionella-recognition receptors within human macrophages.
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Lembo-Fazio L, Billod JM, Di Lorenzo F, Paciello I, Pallach M, Vaz-Francisco S, Holgado A, Beyaert R, Fresno M, Shimoyama A, Lanzetta R, Fukase K, Gully D, Giraud E, Martín-Santamaría S, Bernardini ML, Silipo A. Bradyrhizobium Lipid A: Immunological Properties and Molecular Basis of Its Binding to the Myeloid Differentiation Protein-2/Toll-Like Receptor 4 Complex. Front Immunol 2018; 9:1888. [PMID: 30154796 PMCID: PMC6102379 DOI: 10.3389/fimmu.2018.01888] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 07/31/2018] [Indexed: 11/24/2022] Open
Abstract
Lipopolysaccharides (LPS) are potent activator of the innate immune response through the binding to the myeloid differentiation protein-2 (MD-2)/toll-like receptor 4 (TLR4) receptor complexes. Although a variety of LPSs have been characterized so far, a detailed molecular description of the structure–activity relationship of the lipid A part has yet to be clarified. Photosynthetic Bradyrhizobium strains, symbiont of Aeschynomene legumes, express distinctive LPSs bearing very long-chain fatty acids with a hopanoid moiety covalently linked to the lipid A region. Here, we investigated the immunological properties of LPSs isolated from Bradyrhizobium strains on both murine and human immune systems. We found that they exhibit a weak agonistic activity and, more interestingly, a potent inhibitory effect on MD-2/TLR4 activation exerted by toxic enterobacterial LPSs. By applying computational modeling techniques, we also furnished a plausible explanation for the Bradyrhizobium LPS inhibitory activity at atomic level, revealing that its uncommon lipid A chemical features could impair the proper formation of the receptorial complex, and/or has a destabilizing effect on the pre-assembled complex itself.
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Affiliation(s)
- Luigi Lembo-Fazio
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza-Università di Roma, Rome, Italy
| | - Jean-Marc Billod
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas, CIB-CSIC, Madrid, Spain
| | - Flaviana Di Lorenzo
- Dipartimento di Scienze Chimiche, Complesso Universitario Monte Sant'Angelo, Università di Napoli Federico II, Naples, Italy
| | - Ida Paciello
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza-Università di Roma, Rome, Italy
| | - Mateusz Pallach
- Dipartimento di Scienze Chimiche, Complesso Universitario Monte Sant'Angelo, Università di Napoli Federico II, Naples, Italy
| | | | - Aurora Holgado
- Center for Inflammation Research, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Rudi Beyaert
- Center for Inflammation Research, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Manuel Fresno
- Diomune SL, Parque Científico de Madrid, Madrid, Spain
| | - Atsushi Shimoyama
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan
| | - Rosa Lanzetta
- Dipartimento di Scienze Chimiche, Complesso Universitario Monte Sant'Angelo, Università di Napoli Federico II, Naples, Italy
| | - Koichi Fukase
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan
| | - Djamel Gully
- IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes (LSTM), UMR IRD/SupAgro/INRA/UM2/CIRAD, TA-A82/J - Campus de Baillarguet, Montpellier, France
| | - Eric Giraud
- IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes (LSTM), UMR IRD/SupAgro/INRA/UM2/CIRAD, TA-A82/J - Campus de Baillarguet, Montpellier, France
| | - Sonsoles Martín-Santamaría
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas, CIB-CSIC, Madrid, Spain
| | - Maria-Lina Bernardini
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza-Università di Roma, Rome, Italy.,Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Sapienza-Università di Roma, Rome, Italy
| | - Alba Silipo
- Dipartimento di Scienze Chimiche, Complesso Universitario Monte Sant'Angelo, Università di Napoli Federico II, Naples, Italy
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6
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Schrammel B, Petzold M, Cervero-Aragó S, Sommer R, Lück C, Kirschner A. Persistent presence of outer membrane epitopes during short- and long-term starvation of five Legionella pneumophila strains. BMC Microbiol 2018; 18:75. [PMID: 30016940 PMCID: PMC6050704 DOI: 10.1186/s12866-018-1220-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 06/29/2018] [Indexed: 11/25/2022] Open
Abstract
Background Legionella pneumophila, the causative agent of Legionnaire’s disease, may enter a viable but non-culturable (VBNC) state triggered by environmental stress conditions. Specific outer-membrane epitopes of L. pneumophila are used in many diagnostic applications and some of them are linked to important virulence-related factors or endotoxins. However, it is not clear how the presence and status of these epitopes are influenced by environmental stress conditions. In this study, changes of outer membrane epitopes for monoclonal antibodies (mAb) from the Dresden panel and the major outer membrane protein MOMP were analysed for five L. pneumophila strains during short- and long-term starvation in ultrapure water. Results With ELISA and single cell immuno-fluorescence analysis, we could show that for most of the investigated mAb-strain combinations the total number of mAb-stained Legionella cells stayed constant for up to 400 days. Especially the epitopes of mAb 3/1, 8/5, 26/1 and 20/1, which are specific for L. pneumophila serogroup 1 subtypes, and the mAb 9/1, specific for serogroup 6, showed long-term persistence. For most mAb- stained cells, a high percentage of viable cells was observed at least until 118 days of starvation. At the same time, we observed a reduction of the fluorescence intensity of the stained cells during starvation indicating a loss of epitopes from the cell surface. However, most of the epitopes, including the virulence-associated mAb 3/1 epitope were still present with high fluorescence intensity after 400 days of starvation in up to 50% of the starved L. pneumophila population. Conclusions The results demonstrate the continuous presence of outer membrane epitopes of L. pneumophila during short-term and long-term starvation. Thus, culture-independent mAb-based diagnostic and detection tools, such as immuno-magnetic separation and microarray techniques are applicable for both L. pneumophila in the culturable and the VBNC state even after long-term starvation but nevertheless require careful testing before application. However, the mere presence of those epitopes is not necessarily an indication of viability or infectivity. Electronic supplementary material The online version of this article (10.1186/s12866-018-1220-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Barbara Schrammel
- Institute for Hygiene and Applied Immunology - Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria
| | - Markus Petzold
- Institute for Medical Microbiology and Hygiene, Medical Faculty "Carl Gustav Carus", University of Technology Dresden, Dresden, Germany
| | - Sílvia Cervero-Aragó
- Institute for Hygiene and Applied Immunology - Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria.,Interuniversity Cooperation Centre for Water and Health, Vienna, Austria
| | - Regina Sommer
- Institute for Hygiene and Applied Immunology - Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria.,Interuniversity Cooperation Centre for Water and Health, Vienna, Austria
| | - Christian Lück
- Institute for Medical Microbiology and Hygiene, Medical Faculty "Carl Gustav Carus", University of Technology Dresden, Dresden, Germany
| | - Alexander Kirschner
- Institute for Hygiene and Applied Immunology - Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria. .,Interuniversity Cooperation Centre for Water and Health, Vienna, Austria.
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7
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Pilla DM, Hagar JA, Haldar AK, Mason AK, Degrandi D, Pfeffer K, Ernst RK, Yamamoto M, Miao EA, Coers J. Guanylate binding proteins promote caspase-11-dependent pyroptosis in response to cytoplasmic LPS. Proc Natl Acad Sci U S A 2014; 111:6046-51. [PMID: 24715728 PMCID: PMC4000848 DOI: 10.1073/pnas.1321700111] [Citation(s) in RCA: 248] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
IFN receptor signaling induces cell-autonomous immunity to infections with intracellular bacterial pathogens. Here, we demonstrate that IFN-inducible guanylate binding protein (Gbp) proteins stimulate caspase-11-dependent, cell-autonomous immunity in response to cytoplasmic LPS. Caspase-11-dependent pyroptosis is triggered in IFN-activated macrophages infected with the Gram-negative bacterial pathogen Legionella pneumophila. The rapid induction of pyroptosis in IFN-activated macrophages required a cluster of IFN-inducible Gbp proteins encoded on mouse chromosome 3 (Gbp(chr3)). Induction of pyroptosis in naive macrophages by infections with the cytosol-invading ΔsdhA L. pneumophila mutant was similarly dependent on Gbp(chr3), suggesting that these Gbp proteins play a role in the detection of bacteria accessing the cytosol. Cytoplasmic LPS derived from Salmonella ssp. or Escherichia coli has recently been shown to trigger caspase-11 activation and pyroptosis, but the cytoplasmic sensor for LPS and components of the caspase-11 inflammasome are not yet defined. We found that the induction of caspase-11-dependent pyroptosis by cytoplasmic L. pneumophila-derived LPS required Gbp(chr3) proteins. Similarly, pyroptosis induced by cytoplasmic LPS isolated from Salmonella was diminished in Gbp(chr3)-deficient macrophages. These data suggest a role for Gbp(chr3) proteins in the detection of cytoplasmic LPS and the activation of the noncanonical inflammasome.
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Affiliation(s)
- Danielle M. Pilla
- Departments of Molecular Genetics and Microbiology and Immunology, Duke University Medical Center, Durham, NC 27710
| | - Jon A. Hagar
- Department of Microbiology and Immunology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Arun K. Haldar
- Departments of Molecular Genetics and Microbiology and Immunology, Duke University Medical Center, Durham, NC 27710
| | - Ashley K. Mason
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21203
| | - Daniel Degrandi
- Institute of Medical Microbiology and Hospital Hygiene, Heinrich Heine University Duesseldorf, Duesseldorf 40225, Germany; and
| | - Klaus Pfeffer
- Institute of Medical Microbiology and Hospital Hygiene, Heinrich Heine University Duesseldorf, Duesseldorf 40225, Germany; and
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21203
| | - Masahiro Yamamoto
- Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Edward A. Miao
- Department of Microbiology and Immunology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Jörn Coers
- Departments of Molecular Genetics and Microbiology and Immunology, Duke University Medical Center, Durham, NC 27710
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