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Schulze-Luehrmann J, Liebler-Tenorio E, Felipe-López A, Lührmann A. Cell death induction facilitates egress of Coxiella burnetii from infected host cells at late stages of infection. Mol Microbiol 2024; 121:513-528. [PMID: 38115201 DOI: 10.1111/mmi.15210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 11/22/2023] [Accepted: 11/27/2023] [Indexed: 12/21/2023]
Abstract
Intracellular bacteria have evolved mechanisms to invade host cells, establish an intracellular niche that allows survival and replication, produce progeny, and exit the host cell after completion of the replication cycle to infect new target cells. Bacteria exit their host cell by (i) initiation of apoptosis, (ii) lytic cell death, and (iii) exocytosis. While bacterial egress is essential for bacterial spreading and, thus, pathogenesis, we currently lack information about egress mechanisms for the obligate intracellular pathogen C. burnetii, the causative agent of the zoonosis Q fever. Here, we demonstrate that C. burnetii inhibits host cell apoptosis early during infection, but induces and/or increases apoptosis at later stages of infection. Only at later stages of infection did we observe C. burnetii egress, which depends on previously established large bacteria-filled vacuoles and a functional intrinsic apoptotic cascade. The released bacteria are not enclosed by a host cell membrane and can infect and replicate in new target cells. In summary, our data argue that C. burnetii egress in a non-synchronous way at late stages of infection. Apoptosis-induction is important for C. burnetii egress, but other pathways most likely contribute.
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Affiliation(s)
- Jan Schulze-Luehrmann
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | | | - Alfonso Felipe-López
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anja Lührmann
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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2
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Baars I, Jaedtka M, Dewitz LA, Fu Y, Franz T, Mohr J, Gintschel P, Berlin H, Degen A, Freier S, Rygol S, Schraven B, Kahlfuß S, van Zandbergen G, Müller AJ. Leishmania major drives host phagocyte death and cell-to-cell transfer depending on intracellular pathogen proliferation rate. JCI Insight 2023; 8:e169020. [PMID: 37310793 PMCID: PMC10443809 DOI: 10.1172/jci.insight.169020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 06/05/2023] [Indexed: 06/15/2023] Open
Abstract
The virulence of intracellular pathogens relies largely on the ability to survive and replicate within phagocytes but also on release and transfer into new host cells. Such cell-to-cell transfer could represent a target for counteracting microbial pathogenesis. However, our understanding of the underlying cellular and molecular processes remains woefully insufficient. Using intravital 2-photon microscopy of caspase-3 activation in the Leishmania major-infected (L. major-infected) live skin, we showed increased apoptosis in cells infected by the parasite. Also, transfer of the parasite to new host cells occurred directly without a detectable extracellular state and was associated with concomitant uptake of cellular material from the original host cell. These in vivo findings were fully recapitulated in infections of isolated human phagocytes. Furthermore, we observed that high pathogen proliferation increased cell death in infected cells, and long-term residency within an infected host cell was only possible for slowly proliferating parasites. Our results therefore suggest that L. major drives its own dissemination to new phagocytes by inducing host cell death in a proliferation-dependent manner.
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Affiliation(s)
- Iris Baars
- Experimental Immunodynamics, Institute of Molecular and Clinical Immunology, Medical Faculty, and
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Moritz Jaedtka
- Division of Immunology, Paul Ehrlich Institute, Langen, Germany
- Institute for Immunology, University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Leon-Alexander Dewitz
- Experimental Immunodynamics, Institute of Molecular and Clinical Immunology, Medical Faculty, and
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Yan Fu
- Experimental Immunodynamics, Institute of Molecular and Clinical Immunology, Medical Faculty, and
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Tobias Franz
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
- Institute of Molecular and Clinical Immunology, Medical Faculty, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Juliane Mohr
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
- Institute of Molecular and Clinical Immunology, Medical Faculty, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Patricia Gintschel
- Experimental Immunodynamics, Institute of Molecular and Clinical Immunology, Medical Faculty, and
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Hannes Berlin
- Experimental Immunodynamics, Institute of Molecular and Clinical Immunology, Medical Faculty, and
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Angelina Degen
- Experimental Immunodynamics, Institute of Molecular and Clinical Immunology, Medical Faculty, and
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Sandra Freier
- Experimental Immunodynamics, Institute of Molecular and Clinical Immunology, Medical Faculty, and
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Stefan Rygol
- Experimental Immunodynamics, Institute of Molecular and Clinical Immunology, Medical Faculty, and
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Burkhart Schraven
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
- Institute of Molecular and Clinical Immunology, Medical Faculty, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Sascha Kahlfuß
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
- Institute of Molecular and Clinical Immunology, Medical Faculty, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Ger van Zandbergen
- Division of Immunology, Paul Ehrlich Institute, Langen, Germany
- Institute for Immunology, University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
- Research Center for Immunotherapy (FZI), University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Andreas J. Müller
- Experimental Immunodynamics, Institute of Molecular and Clinical Immunology, Medical Faculty, and
- Health Campus Immunology, Infectiology and Inflammation (GCI3), Medical Faculty and Center for Health and Medical Prevention (CHaMP), Otto von Guericke University Magdeburg, Magdeburg, Germany
- Helmholtz Centre for Infection Research, Braunschweig, Germany
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3
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Weerasinghe H, Simm C, Djajawi TM, Tedja I, Lo TL, Simpson DS, Shasha D, Mizrahi N, Olivier FAB, Speir M, Lawlor KE, Ben-Ami R, Traven A. Candida auris uses metabolic strategies to escape and kill macrophages while avoiding robust activation of the NLRP3 inflammasome response. Cell Rep 2023; 42:112522. [PMID: 37204928 DOI: 10.1016/j.celrep.2023.112522] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 03/28/2023] [Accepted: 05/01/2023] [Indexed: 05/21/2023] Open
Abstract
Metabolic adaptations regulate the response of macrophages to infection. The contributions of metabolism to macrophage interactions with the emerging fungal pathogen Candida auris are poorly understood. Here, we show that C. auris-infected macrophages undergo immunometabolic reprogramming and increase glycolysis but fail to activate a strong interleukin (IL)-1β cytokine response or curb C. auris growth. Further analysis shows that C. auris relies on its own metabolic capacity to escape from macrophages and proliferate in vivo. Furthermore, C. auris kills macrophages by triggering host metabolic stress through glucose starvation. However, despite causing macrophage cell death, C. auris does not trigger robust activation of the NLRP3 inflammasome. Consequently, inflammasome-dependent responses remain low throughout infection. Collectively, our findings show that C. auris uses metabolic regulation to eliminate macrophages while remaining immunologically silent to ensure its own survival. Thus, our data suggest that host and pathogen metabolism could represent therapeutic targets for C. auris infections.
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Affiliation(s)
- Harshini Weerasinghe
- Infection Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Claudia Simm
- Infection Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Tirta Mario Djajawi
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; Department of Molecular and Translational Science, Monash University, Clayton, VIC 3168, Australia
| | - Irma Tedja
- Infection Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Tricia L Lo
- Infection Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Daniel S Simpson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - David Shasha
- Infectious Diseases Unit, Tel Aviv Sourasky Medical Centre, Tel Aviv, Israel; Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Naama Mizrahi
- Infectious Diseases Unit, Tel Aviv Sourasky Medical Centre, Tel Aviv, Israel
| | - Françios A B Olivier
- Infection Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia; The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Mary Speir
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; Department of Molecular and Translational Science, Monash University, Clayton, VIC 3168, Australia
| | - Kate E Lawlor
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; Department of Molecular and Translational Science, Monash University, Clayton, VIC 3168, Australia
| | - Ronen Ben-Ami
- Infectious Diseases Unit, Tel Aviv Sourasky Medical Centre, Tel Aviv, Israel; Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ana Traven
- Infection Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia.
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4
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Brucella Egresses from Host Cells Exploiting Multivesicular Bodies. mBio 2023; 14:e0333822. [PMID: 36622142 PMCID: PMC9973279 DOI: 10.1128/mbio.03338-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Host cell egress is a critical step in the life cycle of intracellular pathogens, especially in microbes capable of establishing chronic infections. The Gram-negative bacterium Brucella belongs to such a group of pathogens. Even though much has been done to understand how Brucella avoids killing and multiplies in its intracellular niche, the mechanism that this bacterium deploys to egress from the cell to complete its cycle has been poorly studied. In the manuscript, we quantify the kinetics of bacterial egress and show that Brucella exploits multivesicular bodies to exit host cells. For the first time, we visualized the process of egress in real time by live video microscopy and showed that a population of intracellular bacteria exit from host cells in vacuoles containing multivesicular body-like features. We observed the colocalization of Brucella with two multivesicular markers, namely, CD63 and LBPA, both during the final stages of the intracellular life cycle and in egressed bacteria. Moreover, drugs that either promote or inhibit multivesicular bodies either increased or decreased the number of extracellular bacteria, respectively. Our results strongly suggest that Brucella hijacks multivesicular bodies to exit the host cells to initiate new infection events. IMPORTANCE How intracellular bacterial pathogens egress from host cells has been poorly studied. This is particularly important because this stage of the infectious cycle can have a strong impact on how the host resolves the infection. Brucella is an intracellular pathogen that infects mammals, including humans, and causes a chronic debilitating illness. The bacterium has evolved a plethora of mechanisms to invade host cells, avoid degradation in the endocytic pathway, and actively multiply within a specialized intracellular compartment. However, how this pathogen exits from infected cells to produce reinfection and complete its life cycle is poorly understood. In the manuscript, we shed some light on the mechanisms that are exploited by Brucella to egress from host cells. We observed for the first time the egress of Brucella from infected cells by time-lapse video microscopy, and we found that the bacterium exits in vesicles containing multivesicular bodies (MVBs) features. Moreover, the drug manipulation of MVBs resulted in the alteration of bacterial egress efficiency. Our results indicate that Brucella hijacks MVBs to exit host cells and that this strongly contributes to the reinfection cycle.
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5
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Olivier FAB, Hilsenstein V, Weerasinghe H, Weir A, Hughes S, Crawford S, Vince JE, Hickey MJ, Traven A. The escape of Candida albicans from macrophages is enabled by the fungal toxin candidalysin and two host cell death pathways. Cell Rep 2022; 40:111374. [PMID: 36130496 DOI: 10.1016/j.celrep.2022.111374] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 06/15/2022] [Accepted: 08/26/2022] [Indexed: 11/25/2022] Open
Abstract
The egress of Candida hyphae from macrophages facilitates immune evasion, but it also alerts macrophages to infection and triggers inflammation. To better define the mechanisms, here we develop an imaging assay to directly and dynamically quantify hyphal escape and correlate it to macrophage responses. The assay reveals that Candida escapes by using two pore-forming proteins to permeabilize macrophage membranes: the fungal toxin candidalysin and Nlrp3 inflammasome-activated Gasdermin D. Candidalysin plays a major role in escape, with Nlrp3 and Gasdermin D-dependent and -independent contributions. The inactivation of Nlrp3 does not reduce hyphal escape, and we identify ETosis via macrophage extracellular trap formation as an additional pathway facilitating hyphal escape. Suppressing hyphal escape does not reduce fungal loads, but it does reduce inflammatory activation. Our findings explain how Candida escapes from macrophages by using three strategies: permeabilizing macrophage membranes via candidalysin and engaging two host cell death pathways, Gasdermin D-mediated pyroptosis and ETosis.
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Affiliation(s)
- Françios A B Olivier
- Infection Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton 3800 VIC, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | | | - Harshini Weerasinghe
- Infection Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton 3800 VIC, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Ashley Weir
- The Walter and Eliza Hall Institute of Medical Research, University of Melbourne, Parkville, VIC 3052, Australia; The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Sebastian Hughes
- The Walter and Eliza Hall Institute of Medical Research, University of Melbourne, Parkville, VIC 3052, Australia; The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Simon Crawford
- Monash Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, VIC 3800, Australia
| | - James E Vince
- The Walter and Eliza Hall Institute of Medical Research, University of Melbourne, Parkville, VIC 3052, Australia; The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Michael J Hickey
- Monash Centre for Inflammatory Diseases, Monash University Department of Medicine, Monash Medical Centre, Clayton, VIC 3168, Australia
| | - Ana Traven
- Infection Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton 3800 VIC, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia.
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6
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Chimalapati S, de Souza Santos M, Lafrance AE, Ray A, Lee WR, Rivera-Cancel G, Vale G, Pawlowski K, Mitsche MA, McDonald JG, Liou J, Orth K. Vibrio deploys type 2 secreted lipase to esterify cholesterol with host fatty acids and mediate cell egress. eLife 2020; 9:58057. [PMID: 32808593 PMCID: PMC7434443 DOI: 10.7554/elife.58057] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 07/28/2020] [Indexed: 12/23/2022] Open
Abstract
Pathogens find diverse niches for survival including inside a host cell where replication occurs in a relatively protective environment. Vibrio parahaemolyticus is a facultative intracellular pathogen that uses its type 3 secretion system 2 (T3SS2) to invade and replicate inside host cells. Analysis of the T3SS2 pathogenicity island encoding the T3SS2 appeared to lack a mechanism for egress of this bacterium from the invaded host cell. Using a combination of molecular tools, we found that VPA0226, a constitutively secreted lipase, is required for escape of V. parahaemolyticus from the host cells. This lipase must be delivered into the host cytoplasm where it preferentially uses fatty acids associated with innate immune response to esterify cholesterol, weakening the plasma membrane and allowing egress of the bacteria. This study reveals the resourcefulness of microbes and the interplay between virulence systems and host cell resources to evolve an ingenious scheme for survival and escape.
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Affiliation(s)
- Suneeta Chimalapati
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Marcela de Souza Santos
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Alexander E Lafrance
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Ann Ray
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Wan-Ru Lee
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Giomar Rivera-Cancel
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Gonçalo Vale
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, United States
| | - Krzysztof Pawlowski
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States.,Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Warsaw, Poland
| | - Matthew A Mitsche
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jeffrey G McDonald
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jen Liou
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
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7
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Tucey TM, Verma J, Olivier FAB, Lo TL, Robertson AAB, Naderer T, Traven A. Metabolic competition between host and pathogen dictates inflammasome responses to fungal infection. PLoS Pathog 2020; 16:e1008695. [PMID: 32750090 PMCID: PMC7433900 DOI: 10.1371/journal.ppat.1008695] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Revised: 08/18/2020] [Accepted: 06/07/2020] [Indexed: 12/11/2022] Open
Abstract
The NLRP3 inflammasome has emerged as a central immune regulator that senses virulence factors expressed by microbial pathogens for triggering inflammation. Inflammation can be harmful and therefore this response must be tightly controlled. The mechanisms by which immune cells, such as macrophages, discriminate benign from pathogenic microbes to control the NLRP3 inflammasome remain poorly defined. Here we used live cell imaging coupled with a compendium of diverse clinical isolates to define how macrophages respond and activate NLRP3 when faced with the human yeast commensal and pathogen Candida albicans. We show that metabolic competition by C. albicans, rather than virulence traits such as hyphal formation, activates NLRP3 in macrophages. Inflammasome activation is triggered by glucose starvation in macrophages, which occurs when fungal load increases sufficiently to outcompete macrophages for glucose. Consistently, reducing Candida’s ability to compete for glucose and increasing glucose availability for macrophages tames inflammatory responses. We define the mechanistic requirements for glucose starvation-dependent inflammasome activation by Candida and show that it leads to inflammatory cytokine production, but it does not trigger pyroptotic macrophage death. Pyroptosis occurs only with some Candida isolates and only under specific experimental conditions, whereas inflammasome activation by glucose starvation is broadly relevant. In conclusion, macrophages use their metabolic status, specifically glucose metabolism, to sense fungal metabolic activity and activate NLRP3 when microbial load increases. Therefore, a major consequence of Candida-induced glucose starvation in macrophages is activation of inflammatory responses, with implications for understanding how metabolism modulates inflammation in fungal infections. Activation of the immune regulator NLRP3 inflammasome by microbial pathogens has been shown to play both protective and destructive roles in infection, underscoring the importance of tight control over NLRP3-driven inflammation to ensure host health. A key microbe recognised by NLRP3 is the human yeast commensal and pathogen Candida albicans, which is responsible for mucosal and invasive infections. We demonstrate that innate immune cells sense their metabolic status to trigger NLRP3 activation only when microbial numbers have reached dangerous levels. This regulation is a consequence of metabolic competition between C. albicans and macrophages for an essential nutrient–glucose. The NLRP3 inflammasome is activated when increased fungal load in the infection microenvironment drives down glucose levels, thereby causing glucose starvation in macrophages. Restoring glucose homeostasis in macrophages reduced NLRP3 activation and production of the proinflammatory cytokine IL-1β, suggesting that metabolism regulates NLRP3 inflammasome activity in fungal infections.
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Affiliation(s)
- Timothy M. Tucey
- Infection and Immunity Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Jiyoti Verma
- Infection and Immunity Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Françios A. B. Olivier
- Infection and Immunity Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Tricia L. Lo
- Infection and Immunity Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Avril A. B. Robertson
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Australia
| | - Thomas Naderer
- Infection and Immunity Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Ana Traven
- Infection and Immunity Program and the Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- * E-mail:
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8
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Flieger A, Frischknecht F, Häcker G, Hornef MW, Pradel G. Pathways of host cell exit by intracellular pathogens. MICROBIAL CELL 2018; 5:525-544. [PMID: 30533418 PMCID: PMC6282021 DOI: 10.15698/mic2018.12.659] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Host cell exit is a critical step in the life-cycle of intracellular pathogens, intimately linked to barrier penetration, tissue dissemination, inflammation, and pathogen transmission. Like cell invasion and intracellular survival, host cell exit represents a well-regulated program that has evolved during host-pathogen co-evolution and that relies on the dynamic and intricate interplay between multiple host and microbial factors. Three distinct pathways of host cell exit have been identified that are employed by three different taxa of intracellular pathogens, bacteria, fungi and protozoa, namely (i) the initiation of programmed cell death, (ii) the active breaching of host cellderived membranes, and (iii) the induced membrane-dependent exit without host cell lysis. Strikingly, an increasing number of studies show that the majority of intracellular pathogens utilize more than one of these strategies, dependent on life-cycle stage, environmental factors and/or host cell type. This review summarizes the diverse exit strategies of intracellular-living bacterial, fungal and protozoan pathogens and discusses the convergently evolved commonalities as well as system-specific variations thereof. Key microbial molecules involved in host cell exit are highlighted and discussed as potential targets for future interventional approaches.
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Affiliation(s)
- Antje Flieger
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
| | | | - Georg Häcker
- Institute of Medical Microbiology and Hygiene, Medical Center - University of Freiburg, Germany
| | - Mathias W Hornef
- Institute of Medical Microbiology, RWTH Aachen University Hospital, Germany
| | - Gabriele Pradel
- Division of Cellular and Applied Infection Biology, Institute of Biology II, RWTH Aachen University, Germany
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9
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I love you Toxoplasma gondii. Microbes Infect 2017; 20:131-134. [PMID: 29248636 DOI: 10.1016/j.micinf.2017.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 11/27/2017] [Indexed: 11/20/2022]
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10
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Di Venanzio G, Lazzaro M, Morales ES, Krapf D, García Véscovi E. A pore-forming toxin enables Serratia a nonlytic egress from host cells. Cell Microbiol 2016; 19. [PMID: 27532510 DOI: 10.1111/cmi.12656] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 07/28/2016] [Accepted: 08/12/2016] [Indexed: 01/01/2023]
Abstract
Several pathogens co-opt host intracellular compartments to survive and replicate, and they thereafter disperse progeny to prosper in a new niche. Little is known about strategies displayed by Serratia marcescens to defeat immune responses and disseminate afterwards. Upon invasion of nonphagocytic cells, Serratia multiplies within autophagosome-like vacuoles. These Serratia-containing vacuoles (SeCV) circumvent progression into acidic/degradative compartments, avoiding elimination. In this work, we show that ShlA pore-forming toxin (PFT) commands Serratia escape from invaded cells. While ShlA-dependent, Ca2+ local increase was shown in SeCVs tight proximity, intracellular Ca2+ sequestration prevented Serratia exit. Accordingly, a Ca2+ surge rescued a ShlA-deficient strain exit capacity, demonstrating that Ca2+ mobilization is essential for egress. As opposed to wild-type-SeCV, the mutant strain-vacuole was wrapped by actin filaments, showing that ShlA expression rearranges host actin. Moreover, alteration of actin polymerization hindered wild-type Serratia escape, while increased intracellular Ca2+ reorganized the mutant strain-SeCV actin distribution, restoring wild-type-SeCV phenotype. Our results demonstrate that, by ShlA expression, Serratia triggers a Ca2+ signal that reshapes cytoskeleton dynamics and ends up pushing the SeCV load out of the cell, in an exocytic-like process. These results disclose that PFTs can be engaged in allowing bacteria to exit without compromising host cell integrity.
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Affiliation(s)
| | | | - Enrique S Morales
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Darío Krapf
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Eleonora García Véscovi
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Universidad Nacional de Rosario, Rosario, Argentina
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Chow SH, Deo P, Naderer T. Macrophage cell death in microbial infections. Cell Microbiol 2016; 18:466-74. [PMID: 26833712 DOI: 10.1111/cmi.12573] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 01/21/2016] [Accepted: 01/27/2016] [Indexed: 12/26/2022]
Abstract
Macrophages can respond to microbial infections with programmed cell death. The major cell death pathways of apoptosis, pyroptosis and necroptosis are tightly regulated to ensure adequate immune reactions to virulent and persistent invaders. Macrophage death eliminates the replicative niche of intracellular pathogens and induces immune attack. Not surprisingly, successful pathogens have evolved strategies to modulate macrophage cell death pathways to enable microbial survival and replication. Uncontrolled macrophage death can also lead to tissue damage, which may augment bacterial dissemination and pathology. In this review, we highlight how pathogens hijack macrophage cell death signals to promote microbial survival and immune evasion.
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Affiliation(s)
- Seong H Chow
- Department of Biochemistry and Molecular Biology and the Biomedicine Discovery Institute, Monash University, Clayton, 3800, VIC, Australia
| | - Pankaj Deo
- Department of Biochemistry and Molecular Biology and the Biomedicine Discovery Institute, Monash University, Clayton, 3800, VIC, Australia
| | - Thomas Naderer
- Department of Biochemistry and Molecular Biology and the Biomedicine Discovery Institute, Monash University, Clayton, 3800, VIC, Australia
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12
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Calderone R, Li D, Traven A. System-level impact of mitochondria on fungal virulence: to metabolism and beyond. FEMS Yeast Res 2015; 15:fov027. [PMID: 26002841 PMCID: PMC4542695 DOI: 10.1093/femsyr/fov027] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/26/2015] [Accepted: 05/14/2015] [Indexed: 12/23/2022] Open
Abstract
The mitochondrion plays wide-ranging roles in eukaryotic cell physiology. In pathogenic fungi, this central metabolic organelle mediates a range of functions related to disease, from fitness of the pathogen to developmental and morphogenetic transitions to antifungal drug susceptibility. In this review, we present the latest findings in this area. We focus on likely mechanisms of mitochondrial impact on fungal virulence pathways through metabolism and stress responses, but also potentially via control over signaling pathways. We highlight fungal mitochondrial proteins that lack human homologs, and which could be inhibited as a novel approach to antifungal drug strategy.
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Affiliation(s)
- Richard Calderone
- Department of Microbiology and Immunology, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Dongmei Li
- Department of Microbiology and Immunology, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Ana Traven
- Department of Biochemistry and Molecular Biology, Monash University Clayton, 3800 VIC, Australia
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13
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Tucey T, Naderer T, Traven A. Candida and macrophages: a deadly affair. MICROBIOLOGY AUSTRALIA 2015. [DOI: 10.1071/ma15019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Abstract
UNLABELLED Candida albicans is a major life-threatening human fungal pathogen in the immunocompromised host. Host defense against systemic Candida infection relies heavily on the capacity of professional phagocytes of the innate immune system to ingest and destroy fungal cells. A number of pathogens, including C. albicans, have evolved mechanisms that attenuate the efficiency of phagosome-mediated inactivation, promoting their survival and replication within the host. Here we visualize host-pathogen interactions using live-cell imaging and show that viable, but not heat- or UV-killed C. albicans cells profoundly delay phagosome maturation in macrophage cell lines and primary macrophages. The ability of C. albicans to delay phagosome maturation is dependent on cell wall composition and fungal morphology. Loss of cell wall O-mannan is associated with enhanced acquisition of phagosome maturation markers, distinct changes in Rab GTPase acquisition by the maturing phagosome, impaired hyphal growth within macrophage phagosomes, profound changes in macrophage actin dynamics, and ultimately a reduced ability of fungal cells to escape from macrophage phagosomes. The loss of cell wall O-mannan leads to exposure of β-glucan in the inner cell wall, facilitating recognition by Dectin-1, which is associated with enhanced phagosome maturation. IMPORTANCE Innate cells engulf and destroy invading organisms by phagocytosis, which is essential for the elimination of fungal cells to protect against systemic life-threatening infections. Yet comparatively little is known about what controls the maturation of phagosomes following ingestion of fungal cells. We used live-cell microscopy and fluorescent protein reporter macrophages to understand how C. albicans viability, filamentous growth, and cell wall composition affect phagosome maturation and the survival of the pathogen within host macrophages. We have demonstrated that cell wall glycosylation and yeast-hypha morphogenesis are required for disruption of host processes that function to inactivate pathogens, leading to survival and escape of this fungal pathogen from within host phagocytes. The methods employed here are applicable to study interactions of other pathogens with phagocytic cells to dissect how specific microbial features impact different stages of phagosome maturation and the survival of the pathogen or host.
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Journal Roundup. J Hosp Infect 2014. [DOI: 10.1016/j.jhin.2014.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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