1
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Neuber J, Lang C, Aurass P, Flieger A. Tools and mechanisms of vacuolar escape leading to host egress in Legionella pneumophila infection: Emphasis on bacterial phospholipases. Mol Microbiol 2024; 121:368-384. [PMID: 37891705 DOI: 10.1111/mmi.15183] [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: 06/28/2023] [Revised: 09/29/2023] [Accepted: 10/06/2023] [Indexed: 10/29/2023]
Abstract
The phenomenon of host cell escape exhibited by intracellular pathogens is a remarkably versatile occurrence, capable of unfolding through lytic or non-lytic pathways. Among these pathogens, the bacterium Legionella pneumophila stands out, having adopted a diverse spectrum of strategies to disengage from their host cells. A pivotal juncture that predates most of these host cell escape modalities is the initial escape from the intracellular compartment. This critical step is increasingly supported by evidence suggesting the involvement of several secreted pathogen effectors, including lytic proteins. In this intricate landscape, L. pneumophila emerges as a focal point for research, particularly concerning secreted phospholipases. While nestled within its replicative vacuole, the bacterium deftly employs both its type II (Lsp) and type IVB (Dot/Icm) secretion systems to convey phospholipases into either the phagosomal lumen or the host cell cytoplasm. Its repertoire encompasses numerous phospholipases A (PLA), including three enzymes-PlaA, PlaC, and PlaD-bearing the GDSL motif. Additionally, there are 11 patatin-like phospholipases A as well as PlaB. Furthermore, the bacterium harbors three extracellular phospholipases C (PLCs) and one phospholipase D. Within this comprehensive review, we undertake an exploration of the pivotal role played by phospholipases in the broader context of phagosomal and host cell egress. Moreover, we embark on a detailed journey to unravel the established and potential functions of the secreted phospholipases of L. pneumophila in orchestrating this indispensable process.
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Affiliation(s)
- Jonathan Neuber
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
| | - Christina Lang
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
| | - Philipp Aurass
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
| | - Antje Flieger
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
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2
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Sonnberger J, Kasper L, Lange T, Brunke S, Hube B. "We've got to get out"-Strategies of human pathogenic fungi to escape from phagocytes. Mol Microbiol 2024; 121:341-358. [PMID: 37800630 DOI: 10.1111/mmi.15149] [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: 06/30/2023] [Revised: 08/08/2023] [Accepted: 08/16/2023] [Indexed: 10/07/2023]
Abstract
Human fungal pathogens are a deadly and underappreciated risk to global health that most severely affect immunocompromised individuals. A virulence attribute shared by some of the most clinically relevant fungal species is their ability to survive inside macrophages and escape from these immune cells. In this review, we discuss the mechanisms behind intracellular survival and elaborate how escape is mediated by lytic and non-lytic pathways as well as strategies to induce programmed host cell death. We also discuss persistence as an alternative to rapid host cell exit. In the end, we address the consequences of fungal escape for the host immune response and provide future perspectives for research and development of targeted therapies.
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Affiliation(s)
- Johannes Sonnberger
- Department of Microbial Pathogenicity Mechanisms, Hans Knoell Institute, Jena, Germany
| | - Lydia Kasper
- Department of Microbial Pathogenicity Mechanisms, Hans Knoell Institute, Jena, Germany
| | - Theresa Lange
- Department of Microbial Pathogenicity Mechanisms, Hans Knoell Institute, Jena, Germany
| | - Sascha Brunke
- Department of Microbial Pathogenicity Mechanisms, Hans Knoell Institute, Jena, Germany
| | - Bernhard Hube
- Department of Microbial Pathogenicity Mechanisms, Hans Knoell Institute, Jena, Germany
- Institute of Microbiology, Friedrich Schiller University, Jena, Germany
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3
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de Castro RJA, Marina CL, Sturny-Leclère A, Hoffmann C, Bürgel PH, Wong SSW, Aimanianda V, Varet H, Agrawal R, Bocca AL, Alanio A. Kicking sleepers out of bed: Macrophages promote reactivation of dormant Cryptococcus neoformans by extracellular vesicle release and non-lytic exocytosis. PLoS Pathog 2023; 19:e1011841. [PMID: 38033163 PMCID: PMC10715671 DOI: 10.1371/journal.ppat.1011841] [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: 06/16/2023] [Revised: 12/12/2023] [Accepted: 11/18/2023] [Indexed: 12/02/2023] Open
Abstract
Macrophages play a key role in disseminated cryptococcosis, a deadly fungal disease caused by Cryptococcus neoformans. This opportunistic infection can arise following the reactivation of a poorly characterized latent infection attributed to dormant C. neoformans. Here, we investigated the mechanisms underlying reactivation of dormant C. neoformans using an in vitro co-culture model of viable but non-culturable (VBNC; equivalent of dormant) yeast cells with bone marrow-derived murine macrophages (BMDMs). Comparative transcriptome analysis of BMDMs incubated with log, stationary phase or VBNC cells of C. neoformans showed that VBNC cells elicited a reduced transcriptional modification of the macrophage but retaining the ability to regulate genes important for immune response, such as NLRP3 inflammasome-related genes. We further confirmed the maintenance of the low immunostimulatory capacity of VBNC cells using multiplex cytokine profiling, and analysis of cell wall composition and dectin-1 ligands exposure. In addition, we evaluated the effects of classic (M1) or alternative (M2) macrophage polarization on VBNC cells. We observed that intracellular residence sustained dormancy, regardless of the polarization state of macrophages and despite indirect detection of pantothenic acid (or its derivatives), a known reactivator for VBNC cells, in the C. neoformans-containing phagolysosome. Notably, M0 and M2, but not M1 macrophages, induced extracellular reactivation of VBNC cells by the secretion of extracellular vesicles and non-lytic exocytosis. Our results indicate that VBNC cells retain the low immunostimulatory profile required for persistence of C. neoformans in the host. We also describe a pro-pathogen role of macrophage-derived extracellular vesicles in C. neoformans infection and reinforce the impact of non-lytic exocytosis and the macrophage profile on the pathophysiology of cryptococcosis.
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Affiliation(s)
- Raffael Júnio Araújo de Castro
- Translational Mycology Research Group, National Reference Center for Invasive Mycoses and Antifungals, Mycology Department, Institut Pasteur, Université Paris Cité, Paris, France
- Laboratory of Applied Immunology, Department of Cell Biology, Institute of Biological Sciences, University of Brasilia, Brasília, Distrito Federal, Brazil
| | - Clara Luna Marina
- Laboratory of Applied Immunology, Department of Cell Biology, Institute of Biological Sciences, University of Brasilia, Brasília, Distrito Federal, Brazil
| | - Aude Sturny-Leclère
- Translational Mycology Research Group, National Reference Center for Invasive Mycoses and Antifungals, Mycology Department, Institut Pasteur, Université Paris Cité, Paris, France
| | - Christian Hoffmann
- Food Research Center, Department of Food Sciences and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, São Paulo, Brazil
| | - Pedro Henrique Bürgel
- Laboratory of Applied Immunology, Department of Cell Biology, Institute of Biological Sciences, University of Brasilia, Brasília, Distrito Federal, Brazil
| | - Sarah Sze Wah Wong
- Immunobiology of Aspergillus, Institut Pasteur, Université Paris Cité, Paris, France
| | - Vishukumar Aimanianda
- Immunobiology of Aspergillus, Institut Pasteur, Université Paris Cité, Paris, France
| | - Hugo Varet
- Plate-forme Technologique Biomics, Institut Pasteur, Université Paris Cité, Paris, France
| | - Ruchi Agrawal
- Translational Mycology Research Group, National Reference Center for Invasive Mycoses and Antifungals, Mycology Department, Institut Pasteur, Université Paris Cité, Paris, France
| | - Anamélia Lorenzetti Bocca
- Laboratory of Applied Immunology, Department of Cell Biology, Institute of Biological Sciences, University of Brasilia, Brasília, Distrito Federal, Brazil
| | - Alexandre Alanio
- Translational Mycology Research Group, National Reference Center for Invasive Mycoses and Antifungals, Mycology Department, Institut Pasteur, Université Paris Cité, Paris, France
- Laboratoire de parasitologie-mycologie, AP-HP, Hôpital Saint-Louis, Paris, France
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4
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Goughenour KD, Nair AS, Xu J, Olszewski MA, Wozniak KL. Dendritic Cells: Multifunctional Roles in Host Defenses to Cryptococcus Infections. J Fungi (Basel) 2023; 9:1050. [PMID: 37998856 PMCID: PMC10672120 DOI: 10.3390/jof9111050] [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: 09/30/2023] [Revised: 10/19/2023] [Accepted: 10/23/2023] [Indexed: 11/25/2023] Open
Abstract
Fungal infections are an increasingly growing public health concern, and Cryptococcus is one of the most problematic fungal organisms causing substantial mortality and morbidity worldwide. Clinically, this high incidence of cryptococcosis is most commonly seen in immunocompromised patients, especially those who lack an adaptive T cell response, such as HIV/AIDS patients. However, patients with other underlying immunodeficiencies are also at an increased risk for cryptococcosis. The adaptive immune response, in particular the Th1/Th17 T-cell-mediated responses, to pulmonary Cryptococcus infections are required for host protection. Dendritic cells (DCs), encompassing multiple subsets identified to date, are recognized as the major professional antigen-presenting cell (APC) subset essential for the initiation and execution of T-cell immunity. Apart from their prominent role in orchestration of the adaptive arm of the immune defenses, DCs are fully armed cells from the innate immune system capable of the recognition, uptake, and killing of the fungal cells. Thus, DCs serve as a critical point for the endpoint outcomes of either fungal control or unrestrained fungal infection. Multiple studies have shown that DCs are required for anti-cryptococcal defense in the lungs. In addition, the role of DCs in Cryptococcus gattii infections is just starting to be elucidated. C. gattii has recently risen to prominence with multiple outbreaks in the US and Canada, demonstrating increased virulence in non-immunocompromised individuals. C. gattii infection fails to generate an inflammatory immune response or a protective Th1/Th17 T cell response, at least in part, through a lack of proper DC function. Here we summarize the multiple roles of DCs, including subsets of DCs in both mouse and human models, the roles of DCs during cryptococcal infection, and mechanisms by cryptococcal cells to attempt to undermine these host defenses.
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Affiliation(s)
- Kristie D. Goughenour
- Research Service, Department of Veterans Affairs Health System, Ann Arbor VA Healthcare System, Ann Arbor, MI 48105, USA
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109, USA
| | - Ayesha S. Nair
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
| | - Jintao Xu
- Research Service, Department of Veterans Affairs Health System, Ann Arbor VA Healthcare System, Ann Arbor, MI 48105, USA
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109, USA
| | - Michal A. Olszewski
- Research Service, Department of Veterans Affairs Health System, Ann Arbor VA Healthcare System, Ann Arbor, MI 48105, USA
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109, USA
| | - Karen L. Wozniak
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
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Stuckey PV, Santiago-Tirado FH. Fungal mechanisms of intracellular survival: what can we learn from bacterial pathogens? Infect Immun 2023; 91:e0043422. [PMID: 37506189 PMCID: PMC10501222 DOI: 10.1128/iai.00434-22] [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: 11/28/2022] [Accepted: 06/23/2023] [Indexed: 07/30/2023] Open
Abstract
Fungal infections represent a major, albeit neglected, public health threat with serious medical and economic burdens globally. With unacceptably high mortality rates, invasive fungal pathogens are responsible for millions of deaths each year, with a steadily increasing incidence primarily in immunocompromised individuals. The poor therapeutic options and rise of antifungal drug resistance pose further challenges in controlling these infections. These fungal pathogens have adapted to survive within mammalian hosts and can establish intracellular niches to promote survival within host immune cells. To do that, they have developed diverse methods to circumvent the innate immune system attack. This includes strategies such as altering their morphology, counteracting macrophage antimicrobial action, and metabolic adaptation. This is reminiscent of how bacterial pathogens have adapted to survive within host cells and cause disease. However, relative to the great deal of information available concerning intracellular bacterial pathogenesis, less is known about the mechanisms fungal pathogens employ. Therefore, here we review our current knowledge and recent advances in our understanding of how fungi can evade and persist within host immune cells. This review will focus on the major fungal pathogens, including Cryptococcus neoformans, Candida albicans, and Aspergillus fumigatus, among others. As we discover and understand the strategies used by these fungi, similarities with their bacterial counterparts are becoming apparent, hence we can use the abundant information from bacteria to guide our studies in fungi. By understanding these strategies, new lines of research will open that can improve the treatments of these devastating fungal diseases.
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Affiliation(s)
- Peter V. Stuckey
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Felipe H. Santiago-Tirado
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
- Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, Indiana, USA
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Conn BN, Wozniak KL. Innate Pulmonary Phagocytes and Their Interactions with Pathogenic Cryptococcus Species. J Fungi (Basel) 2023; 9:617. [PMID: 37367553 PMCID: PMC10299524 DOI: 10.3390/jof9060617] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 05/23/2023] [Accepted: 05/25/2023] [Indexed: 06/28/2023] Open
Abstract
Cryptococcus neoformans is an opportunistic fungal pathogen that causes over 180,000 annual deaths in HIV/AIDS patients. Innate phagocytes in the lungs, such as dendritic cells (DCs) and macrophages, are the first cells to interact with the pathogen. Neutrophils, another innate phagocyte, are recruited to the lungs during cryptococcal infection. These innate cells are involved in early detection of C. neoformans, as well as the removal and clearance of cryptococcal infections. However, C. neoformans has developed ways to interfere with these processes, allowing for the evasion of the host's innate immune system. Additionally, the innate immune cells have the ability to aid in cryptococcal pathogenesis. This review discusses recent literature on the interactions of innate pulmonary phagocytes with C. neoformans.
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Affiliation(s)
| | - Karen L. Wozniak
- Department of Microbiology and Molecular Genetics, Oklahoma State University, 307 Life Science East, Stillwater, OK 74078, USA;
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Lange T, Kasper L, Gresnigt MS, Brunke S, Hube B. "Under Pressure" - How fungi evade, exploit, and modulate cells of the innate immune system. Semin Immunol 2023; 66:101738. [PMID: 36878023 PMCID: PMC10109127 DOI: 10.1016/j.smim.2023.101738] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Indexed: 03/06/2023]
Abstract
The human immune system uses an arsenal of effector mechanisms to prevent and counteract infections. Yet, some fungal species are extremely successful as human pathogens, which can be attributed to a wide variety of strategies by which these fungi evade, exploit, and modulate the immune system. These fungal pathogens normally are either harmless commensals or environmental fungi. In this review we discuss how commensalism, but also life in an environmental niche without human contact, can drive the evolution of diverse and specialized immune evasion mechanisms. Correspondingly, we discuss the mechanisms contributing to the ability of these fungi to cause superficial to life-threatening infections.
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Affiliation(s)
- Theresa Lange
- Department of Microbial Pathogenicity Mechanisms, Hans Knoell Institute, Jena, Germany
| | - Lydia Kasper
- Department of Microbial Pathogenicity Mechanisms, Hans Knoell Institute, Jena, Germany
| | - Mark S Gresnigt
- Junior Research Group Adaptive Pathogenicity Strategies, Hans Knoell Institute, Jena, Germany
| | - Sascha Brunke
- Department of Microbial Pathogenicity Mechanisms, Hans Knoell Institute, Jena, Germany
| | - Bernhard Hube
- Department of Microbial Pathogenicity Mechanisms, Hans Knoell Institute, Jena, Germany; Institute of Microbiology, Friedrich Schiller University, Jena, Germany.
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8
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Baker RP, Casadevall A. Reciprocal modulation of ammonia and melanin production has implications for cryptococcal virulence. Nat Commun 2023; 14:849. [PMID: 36792633 PMCID: PMC9932161 DOI: 10.1038/s41467-023-36552-7] [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] [Received: 08/18/2022] [Accepted: 02/07/2023] [Indexed: 02/17/2023] Open
Abstract
The fungus Cryptococcus neoformans is the causative agent of cryptococcosis, a disease that is uniformly lethal unless treated with antifungal drugs, yet current regimens are hindered by host toxicity and pathogen resistance. An attractive alternative approach to combat this deadly disease is the direct targeting of pathogen-derived virulence mechanisms. C. neoformans expresses multiple virulence factors that have been studied previously as isolated entities. Among these, are urease, which increases phagosomal pH and promotes brain invasion, and melanization, which protects against immune cells and antifungal treatments. Here we report a reciprocal interdependency between these two virulence factors. Cells hydrolyzing urea release ammonia gas which acts at a distance to raise pH and increase melanization rates for nearby cells, which in turn reduces secretion of urease-carrying extracellular vesicles. This reciprocal relationship manifests as an emergent property that may explain why targeting isolated virulence mechanisms for drug development has been difficult and argues for a more holistic approach that considers the virulence composite.
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Affiliation(s)
- Rosanna P Baker
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, 21205, USA.
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9
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Santiago-Burgos EJ, Stuckey PV, Santiago-Tirado FH. Real-time visualization of phagosomal pH manipulation by Cryptococcus neoformans in an immune signal-dependent way. Front Cell Infect Microbiol 2022; 12:967486. [PMID: 36211949 PMCID: PMC9538179 DOI: 10.3389/fcimb.2022.967486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Accepted: 09/08/2022] [Indexed: 11/21/2022] Open
Abstract
Understanding of how intracellular pathogens survive in their host cells is important to improve management of their diseases. This has been fruitful for intracellular bacteria, but it is an understudied area in fungal pathogens. Here we start elucidating and characterizing the strategies used by one of the commonest fungal pathogens, Cryptococcus neoformans, to survive intracellularly. The ability of the fungus to survive inside host cells is one of the main drivers of disease progression, yet it is unclear whether C. neoformans resides in a fully acidified, partially acidic, or neutral phagosome. Using a dye that only fluoresce under acidic conditions to stain C. neoformans, a hypha-defective Candida albicans mutant, and the nonpathogenic Saccharomyces cerevisiae, we characterized the fungal behaviors in infected macrophages by live microscopy. The main behavior in the C. albicans mutant strain and S. cerevisiae-phagosomes was rapid acidification after internalization, which remained for the duration of the imaging. In contrast, a significant number of C. neoformans-phagosomes exhibited alternative behaviors distinct from the normal phagosomal maturation: some phagosomes acidified with subsequent loss of acidification, and other phagosomes never acidified. Moreover, the frequency of these behaviors was affected by the immune status of the host cell. We applied the same technique to a flow cytometry analysis and found that a substantial percentage of C. neoformans-phagosomes showed impaired acidification, whereas almost 100% of the S. cerevisiae-phagosomes acidify. Lastly, using a membrane-damage reporter, we show phagosome permeabilization correlates with acidification alterations, but it is not the only strategy that C. neoformans uses to manipulate phagosomal acidification. The different behaviors described here provide an explanation to the confounding literature regarding cryptococcal-phagosome acidification and the methods can be applied to study other intracellular fungal pathogens.
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Affiliation(s)
| | - Peter V. Stuckey
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, United States
| | - Felipe H. Santiago-Tirado
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, United States
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States
- Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, IN, United States
- *Correspondence: Felipe H. Santiago-Tirado,
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Jung EH, Park YD, Dragotakes Q, Ramirez LS, Smith DQ, Reis FCG, Dziedzic A, Rodrigues ML, Baker RP, Williamson PR, Jedlicka A, Casadevall A, Coelho C. Cryptococcus neoformans releases proteins during intracellular residence that affect the outcome of the fungal-macrophage interaction. MICROLIFE 2022; 3:uqac015. [PMID: 36247839 PMCID: PMC9552768 DOI: 10.1093/femsml/uqac015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 09/13/2022] [Indexed: 05/26/2023]
Abstract
Cryptococcus neoformans is a facultative intracellular pathogen that can replicate and disseminate in mammalian macrophages. In this study, we analyzed fungal proteins identified in murine macrophage-like cells after infection with C. neoformans. To accomplish this, we developed a protocol to identify proteins released from cryptococcal cells inside macrophage-like cells; we identified 127 proteins of fungal origin in infected macrophage-like cells. Among the proteins identified was urease, a known virulence factor, and others such as transaldolase and phospholipase D, which have catalytic activities that could contribute to virulence. This method provides a straightforward methodology to study host-pathogen interactions. We chose to study further Yeast Oligomycin Resistance (Yor1), a relatively uncharacterized protein belonging to the large family of ATP binding cassette transporter (ABC transporters). These transporters belong to a large and ancient protein family found in all extant phyla. While ABC transporters have an enormous diversity of functions across varied species, in pathogenic fungi they are better studied as drug efflux pumps. Analysis of C. neoformans yor1Δ strains revealed defects in nonlytic exocytosis, capsule size, and dimensions of extracellular vesicles, when compared to wild-type strains. We detected no difference in growth rates and cell body size. Our results indicate that C. neoformans releases a large suite of proteins during macrophage infection, some of which can modulate fungal virulence and are likely to affect the fungal-macrophage interaction.
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Affiliation(s)
- Eric H Jung
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, United States
| | - Yoon-Dong Park
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Disease, National Institutes of Health, Memorial Drive, Bethesda, MD 20814, United States
| | - Quigly Dragotakes
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, United States
| | - Lia S Ramirez
- Department of Molecular and Cell Biology, Johns Hopkins University, 615 North Wolfe Street, Baltimore, MD 21205, United States
| | - Daniel Q Smith
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, United States
| | - Flavia C G Reis
- Instituto Carlos Chagas, Fundação Oswaldo Cruz (Fiocruz), Rua Professor Algacyr Munhoz Mader, 3775, Curitiba - PR, 81310-020, Brazil
- Centro de Desenvolvimento Tecnológico em Saúde (CDTS), Fundação Oswaldo Cruz Av. Brasil 4036. Room 814, Rio de Janeiro - RJ, 21040-361, Brazil
| | - Amanda Dziedzic
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, United States
| | - Marcio L Rodrigues
- Instituto Carlos Chagas, Fundação Oswaldo Cruz (Fiocruz), Rua Professor Algacyr Munhoz Mader, 3775, Curitiba - PR, 81310-020, Brazil
- Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro, Rio de Janeiro Cidade Universitária da Universidade Federal do Rio de Janeiro,, Rio de Janeiro - RJ, 21941-902, Brazil
| | - Rosanna P Baker
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, United States
| | - Peter R Williamson
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Disease, National Institutes of Health, Memorial Drive, Bethesda, MD 20814, United States
| | - Anne Jedlicka
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, United States
| | - Arturo Casadevall
- Corresponding author: Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, 615 N, Wolfe Street, Room E5132, Baltimore, MD 21205, United States. E-mail:
| | - Carolina Coelho
- Corresponding author: Medical Research Council Centre for Medical Mycology at University of Exeter, College of Health and Medicine, Geoffrey Pope Building, Room 325, University of Exeter, Stocker Road, Exeter EX4 4QD, Devon, United Kingdom. E-mail:
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11
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Tharappel AM, Li Z, Zhu YC, Wu X, Chaturvedi S, Zhang QY, Li H. Calcimycin Inhibits Cryptococcus neoformans In Vitro and In Vivo by Targeting the Prp8 Intein Splicing. ACS Infect Dis 2022; 8:1851-1868. [PMID: 35948057 PMCID: PMC9464717 DOI: 10.1021/acsinfecdis.2c00137] [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] [Indexed: 01/29/2023]
Abstract
Drug resistance is a significant concern in the treatment of diseases, including cryptococcosis caused by Cryptococcus neoformans (Cne) and Cryptococcus gattii (Cga). Alternative drug targets are necessary to overcome drug resistance before it attains a critical stage. Splicing of inteins from pro-protein precursors is crucial for activities of essential proteins hosting intein elements in many organisms, including human pathogens such as Cne and Cga. Through a high-throughput screening, we identified calcimycin (CMN) as a potent Prp8 intein splicing inhibitor with a minimum inhibitory concentration (MIC) of 1.5 μg/mL against the wild-type Cne-H99 (Cne-WT or Cne). In contrast, CMN inhibited the intein-less mutant strain (Cne-Mut) with a 16-fold higher MIC. Interestingly, Aspergillus fumigatus and a few Candida species were resistant to CMN. Further studies indicated that CMN reduced virulence factors such as urease activity, melanin production, and biofilm formation in Cne. CMN also inhibited Cne intracellular infection in macrophages. In a target-specific split nanoluciferase assay, the IC50 of CMN was 4.6 μg/mL. Binding of CMN to recombinant Prp8 intein was demonstrated by thermal shift assay and microscale thermophoresis. Treating Cne cells with CMN reduced intein splicing. CMN was fungistatic and showed a synergistic effect with the known antifungal drug amphotericin B. Finally, CMN treatment at 20 mg/kg body weight led to 60% reduction in lung fungal load in a cryptococcal pulmonary infection mouse model. Overall, CMN represents a potent antifungal with a novel mechanism of action to treat Cne and possibly Cga infections.
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Affiliation(s)
- Anil Mathew Tharappel
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson Arizona 85721-0207, United States
- Wadsworth Center, New York State Department of Health, Albany, New York 12208, United States
| | - Zhong Li
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson Arizona 85721-0207, United States
- Wadsworth Center, New York State Department of Health, Albany, New York 12208, United States
| | - Yan Chun Zhu
- Wadsworth Center, New York State Department of Health, Albany, New York 12208, United States
| | - Xiangmeng Wu
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson Arizona 85721-0207, United States
| | - Sudha Chaturvedi
- Wadsworth Center, New York State Department of Health, Albany, New York 12208, United States
| | - Qing-Yu Zhang
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson Arizona 85721-0207, United States
| | - Hongmin Li
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson Arizona 85721-0207, United States
- Wadsworth Center, New York State Department of Health, Albany, New York 12208, United States
- The BIO5 Institute, The University of Arizona, Tucson, Arizona 85721, United States
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12
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Dragotakes Q, Jacobs E, Ramirez LS, Yoon OI, Perez-Stable C, Eden H, Pagnotta J, Vij R, Bergman A, D’Alessio F, Casadevall A. Bet-hedging antimicrobial strategies in macrophage phagosome acidification drive the dynamics of Cryptococcus neoformans intracellular escape mechanisms. PLoS Pathog 2022; 18:e1010697. [PMID: 35816543 PMCID: PMC9302974 DOI: 10.1371/journal.ppat.1010697] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/21/2022] [Accepted: 06/23/2022] [Indexed: 11/19/2022] Open
Abstract
The fungus Cryptococcus neoformans is a major human pathogen with a remarkable intracellular survival strategy that includes exiting macrophages through non-lytic exocytosis (Vomocytosis) and transferring between macrophages (Dragotcytosis) by a mechanism that involves sequential events of non-lytic exocytosis and phagocytosis. Vomocytosis and Dragotcytosis are fungal driven processes, but their triggers are not understood. We hypothesized that the dynamics of Dragotcytosis could inherit the stochasticity of phagolysosome acidification and that Dragotcytosis was triggered by fungal cell stress. Consistent with this view, fungal cells involved in Dragotcytosis reside in phagolysosomes characterized by low pH and/or high oxidative stress. Using fluorescent microscopy, qPCR, live cell video microscopy, and fungal growth assays we found that the that mitigating pH or oxidative stress reduced Dragotcytosis frequency, whereas ROS susceptible mutants of C. neoformans underwent Dragotcytosis more frequently. Dragotcytosis initiation was linked to phagolysosomal pH, oxidative stresses, and macrophage polarization state. Dragotcytosis manifested stochastic dynamics thus paralleling the dynamics of phagosomal acidification, which correlated with the inhospitality of phagolysosomes in differently polarized macrophages. Hence, randomness in phagosomal acidification randomly created a population of inhospitable phagosomes where fungal cell stress triggered stochastic C. neoformans non-lytic exocytosis dynamics to escape a non-permissive intracellular macrophage environment.
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Affiliation(s)
- Quigly Dragotakes
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Ella Jacobs
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Lia Sanchez Ramirez
- Department of Molecular and Cell Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Olivia Insun Yoon
- Department of Molecular and Cell Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Caitlin Perez-Stable
- Department of Molecular and Cell Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Hope Eden
- Department of Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Jenlu Pagnotta
- Department of Molecular and Cell Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Raghav Vij
- Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany
| | - Aviv Bergman
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, New York City, New York, United States of America
- Santa Fe Institute, Santa Fe, New Mexico, United States of America
| | - Franco D’Alessio
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, United States of America
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
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13
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Wang Y, Pawar S, Dutta O, Wang K, Rivera A, Xue C. Macrophage Mediated Immunomodulation During Cryptococcus Pulmonary Infection. Front Cell Infect Microbiol 2022; 12:859049. [PMID: 35402316 PMCID: PMC8987709 DOI: 10.3389/fcimb.2022.859049] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 02/28/2022] [Indexed: 12/21/2022] Open
Abstract
Macrophages are key cellular components of innate immunity, acting as the first line of defense against pathogens to modulate homeostatic and inflammatory responses. They help clear pathogens and shape the T-cell response through the production of cytokines and chemokines. The facultative intracellular fungal pathogen Cryptococcus neoformans has developed a unique ability to interact with and manipulate host macrophages. These interactions dictate how Cryptococcus infection can remain latent or how dissemination within the host is achieved. In addition, differences in the activities of macrophages have been correlated with differential susceptibilities of hosts to Cryptococcus infection, highlighting the importance of macrophages in determining disease outcomes. There is now abundant information on the interaction between Cryptococcus and macrophages. In this review we discuss recent advances regarding macrophage origin, polarization, activation, and effector functions during Cryptococcus infection. The importance of these strategies in pathogenesis and the potential of immunotherapy for cryptococcosis treatment is also discussed.
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Affiliation(s)
- Yan Wang
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, United States
- Department of Microbiology and Immunology , Guangdong Medical University, Dongguan, China
| | - Siddhi Pawar
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, United States
| | - Orchi Dutta
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, United States
| | - Keyi Wang
- Center for Immunity and Inflammation, New Jersey Medical School, Rutgers University, Newark, NJ, United States
| | - Amariliz Rivera
- Center for Immunity and Inflammation, New Jersey Medical School, Rutgers University, Newark, NJ, United States
| | - Chaoyang Xue
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, United States
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14
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Hawkins AN, Determann BF, Nelson BN, Wozniak KL. Transcriptional Changes in Pulmonary Phagocyte Subsets Dictate the Outcome Following Interaction With The Fungal Pathogen Cryptococcus neoformans. Front Immunol 2021; 12:722500. [PMID: 34650554 PMCID: PMC8505728 DOI: 10.3389/fimmu.2021.722500] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/31/2021] [Indexed: 12/24/2022] Open
Abstract
With over 220,000 cases and 180,000 deaths annually, Cryptococcus neoformans is the most common cause of fungal meningitis and a leading cause of death in HIV/AIDS patients in Sub-Saharan Africa. Either C. neoformans can be killed by innate airway phagocytes, or it can survive intracellularly. Pulmonary murine macrophage and dendritic cell (DC) subsets have been identified in the naïve lung, and we hypothesize that each subset has different interactions with C. neoformans. For these studies, we purified murine pulmonary macrophage and DC subsets from naïve mice - alveolar macrophages, Ly6c- and Ly6c+ monocyte-like macrophages, interstitial macrophages, CD11b+ and CD103+ DCs. With each subset, we examined cryptococcal association (binding/internalization), fungicidal activity, intracellular fungal morphology, cytokine secretion and transcriptional profiling in an ex vivo model using these pulmonary phagocyte subsets. Results showed that all subsets associate with C. neoformans, but only female Ly6c- monocyte-like macrophages significantly inhibited growth, while male CD11b+ DCs significantly enhanced fungal growth. In addition, cytokine analysis revealed that some subsets from female mice produced increased amounts of cytokines compared to their counterparts in male mice following exposure to C. neoformans. In addition, although cells were analyzed ex vivo without the influence of the lung microenviroment, we did not find evidence of phagocyte polarization following incubation with C. neoformans. Imaging flow cytometry showed differing ratios of cryptococcal morphologies, c-shaped or budding, depending on phagocyte subset. RNA sequencing analysis revealed the up- and down-regulation of many genes, from immunological pathways (including differential regulation of MHC class I in the antigen processing pathway and the cell adhesion pathway) and pathways relating to relating to metabolic activity (genes in the Cytochrome P450 family, genes related to actin binding, calcium voltage channels, serine proteases, and phospholipases). Future studies gaining a more in-depth understanding on the functionality of individual genes and pathways specific to permissive and non-permissive pulmonary phagocytes will allow identification of key targets when developing therapeutic strategies to prevent cryptococcal meningitis.
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Affiliation(s)
- Ashlee N Hawkins
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Brenden F Determann
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Benjamin N Nelson
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Karen L Wozniak
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
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15
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Cheng L, Niu MM, Yan T, Ma Z, Huang K, Yang L, Zhong X, Li C. Bioresponsive micro-to-nano albumin-based systems for targeted drug delivery against complex fungal infections. Acta Pharm Sin B 2021; 11:3220-3230. [PMID: 34729311 PMCID: PMC8546853 DOI: 10.1016/j.apsb.2021.04.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/09/2021] [Accepted: 03/25/2021] [Indexed: 12/14/2022] Open
Abstract
As a typical human pathogenic fungus, Cryptococcus neoformans is a life-threatening invasive fungal pathogen with a worldwide distribution causing ∼700,000 deaths annually. Cryptococcosis is not just an infection with multi-organ involvement, intracellular survival and extracellular multiplication of the fungus also play important roles in the pathogenesis of C. neoformans infections. Because adequate accumulation of drugs at target organs and cells is still difficult to achieve, an effective delivery strategy is desperately required to treat these infections. Here, we report a bioresponsive micro-to-nano (MTN) system that effectively clears the C. neoformans in vivo. This strategy is based on our in-depth study of the overexpression of matrix metalloproteinase 3 (MMP-3) in infectious microenvironments (IMEs) and secreted protein acidic and rich in cysteine (SPARC) in several associated target cells. In this MTN system, bovine serum albumin (BSA, a natural ligand of SPARC) was used for the preparation of nanoparticles (NPs), and then microspheres were constructed by conjugation with a special linker, which mainly consisted of a BSA-binding peptide and an MMP-3-responsive peptide. This MTN system was mechanically captured by the smallest capillaries of the lungs after intravenous injection, and then hydrolyzed into BSA NPs by MMP-3 in the IMEs. The NPs further targeted the lung tissue, brain and infected macrophages based on the overexpression of SPARC, reaching multiple targets and achieving efficient treatment. We have developed a size-tunable strategy where microspheres "shrink" to NPs in IMEs, which effectively combines active and passive targeting and may be especially powerful in the fight against complex fungal infections.
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Key Words
- Albumin
- AmB, amphotericin B
- BBB, blood‒brain barrier
- BSA, bovine serum albumin
- Complex fungal infection
- DDS, drug delivery system
- IME, infectious microenvironment
- MMP-3
- MMP-3, matrix metalloproteinase 3
- MTN, micro-to-nano
- Microenvironment responsive
- NP, nanoparticle
- PEG, polyethylene glycol
- PMVECs, pulmonary microvascular endothelial cells
- RFP, red fluorescent protein
- SPARC
- SPARC, secreted protein acidic and rich in cysteine
- Size-tunable strategy
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Affiliation(s)
- Liting Cheng
- Medical Research Institute, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Miao-Miao Niu
- Key Laboratory of Drug Quality Control and Pharmacovigilance (Ministry of Education), China Pharmaceutical University, Nanjing 210009, China
| | - Tong Yan
- Medical Research Institute, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Zhongyi Ma
- Medical Research Institute, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Kexin Huang
- Medical Research Institute, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Ling Yang
- Medical Research Institute, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Xin Zhong
- Medical Research Institute, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Chong Li
- Medical Research Institute, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
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16
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Toplis B, Bosch C, Stander M, Taylor M, Perfect JR, Botha A. A link between urease and polyamine metabolism in Cryptococcus neoformans. Microb Pathog 2021; 158:105076. [PMID: 34216740 DOI: 10.1016/j.micpath.2021.105076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 05/05/2021] [Accepted: 06/24/2021] [Indexed: 01/09/2023]
Abstract
The urease enzyme of Cryptococcus neoformans is linked to different metabolic pathways within the yeast cell, several of which are involved in polyamine metabolism. Cryptococcal biogenic amine production is, however, largely unexplored and is yet to be investigated in relation to urease. The aim of this study was therefore to explore and compare polyamine metabolism in wild-type, urease-negative and urease-reconstituted strains of C. neoformans. Mass spectrometry analysis showed that agmatine and spermidine were the major extra- and intracellular polyamines of C. neoformans and significant differences were observed between 26 and 37 °C. In addition, compared to the wild-type, the relative percentages of extracellular putrescine and spermidine were found to be lower and agmatine higher in cultures of the urease-deficient mutant. The inverse was true for intracellular spermidine and agmatine. Cyclohexylamine was a more potent polyamine inhibitor compared to DL-α-difluoromethylornithine and inhibitory effects were more pronounced at 37 °C than at 26 °C. At both temperatures, the urease-deficient mutant was less susceptible to cyclohexylamine treatment compared to the wild-type. For both inhibitors, growth inhibition was alleviated with polyamine supplementation. This study has provided novel insight into the polyamine metabolism of C. neoformans, highlighting the involvement of urease in biogenic amine production.
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Affiliation(s)
- Barbra Toplis
- Department of Microbiology, University of Stellenbosch, Matieland, 7602, Stellenbosch, South Africa
| | - Caylin Bosch
- Department of Microbiology, University of Stellenbosch, Matieland, 7602, Stellenbosch, South Africa
| | - Marietjie Stander
- Mass Spectrometry Unit, Central Analytical Facilities, University of Stellenbosch, Matieland, 7602, Stellenbosch, South Africa
| | - Malcolm Taylor
- Mass Spectrometry Unit, Central Analytical Facilities, University of Stellenbosch, Matieland, 7602, Stellenbosch, South Africa
| | - John R Perfect
- Division of Infectious Diseases, Duke University Medical Centre, Durham, NC, 27710-1000, USA
| | - Alfred Botha
- Department of Microbiology, University of Stellenbosch, Matieland, 7602, Stellenbosch, South Africa.
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17
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Fu MS, Liporagi-Lopes LC, Dos Santos SR, Tenor JL, Perfect JR, Cuomo CA, Casadevall A. Amoeba Predation of Cryptococcus neoformans Results in Pleiotropic Changes to Traits Associated with Virulence. mBio 2021; 12:e00567-21. [PMID: 33906924 PMCID: PMC8092252 DOI: 10.1128/mbio.00567-21] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 03/30/2021] [Indexed: 11/20/2022] Open
Abstract
Amoeboid predators, such as amoebae, are proposed to select for survival traits in soil microbes such as Cryptococcus neoformans; these traits can also function in animal virulence by defeating phagocytic immune cells, such as macrophages. Consistent with this notion, incubation of various fungal species with amoebae enhanced their virulence, but the mechanisms involved are unknown. In this study, we exposed three strains of C. neoformans (1 clinical and 2 environmental) to predation by Acanthamoeba castellanii for prolonged times and then analyzed surviving colonies phenotypically and genetically. Surviving colonies comprised cells that expressed either pseudohyphal or yeast phenotypes, which demonstrated variable expression of traits associated with virulence, such as capsule size, urease production, and melanization. Phenotypic changes were associated with aneuploidy and DNA sequence mutations in some amoeba-passaged isolates, but not in others. Mutations in the gene encoding the oligopeptide transporter (CNAG_03013; OPT1) were observed among amoeba-passaged isolates from each of the three strains. Isolates derived from environmental strains gained the capacity for enhanced macrophage toxicity after amoeba selection and carried mutations on the CNAG_00570 gene encoding Pkr1 (AMP-dependent protein kinase regulator) but manifested reduced virulence in mice because they elicited more effective fungal-clearing immune responses. Our results indicate that C. neoformans survival under constant amoeba predation involves the generation of strains expressing pleiotropic phenotypic and genetic changes. Given the myriad potential predators in soils, the diversity observed among amoeba-selected strains suggests a bet-hedging strategy whereby variant diversity increases the likelihood that some will survive predation.IMPORTANCECryptococcus neoformans is a ubiquitous environmental fungus that is also a leading cause of fatal fungal infection in humans, especially among immunocompromised patients. A major question in the field is how an environmental yeast such as C. neoformans becomes a human pathogen when it has no need for an animal host in its life cycle. Previous studies showed that C. neoformans increases its pathogenicity after interacting with its environmental predator amoebae. Amoebae, like macrophages, are phagocytic cells that are considered an environmental training ground for pathogens to resist macrophages, but the mechanism by which C. neoformans changes its virulence through interactions with protozoa is unknown. Our study indicates that fungal survival in the face of amoeba predation is associated with the emergence of pleiotropic phenotypic and genomic changes that increase the chance of fungal survival, with this diversity suggesting a bet-hedging strategy to ensure that some forms survive.
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Affiliation(s)
- Man Shun Fu
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Livia C Liporagi-Lopes
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Samuel R Dos Santos
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Jennifer L Tenor
- Division of Infectious Diseases, Department of Medicine and Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - John R Perfect
- Division of Infectious Diseases, Department of Medicine and Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - Christina A Cuomo
- Infectious Disease and Microbiome Program, Broad Institute, Cambridge, Massachusetts, USA
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
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18
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Kalem MC, Humby MS, Wohlfert EA, Jacobs A, Panepinto JC. Cryptococcus neoformans Coinfection Dampens the TNF-α Response in HIV-1-Infected Human THP-1 Macrophages. mSphere 2021; 6:e00213-21. [PMID: 33762317 PMCID: PMC8546698 DOI: 10.1128/msphere.00213-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 03/08/2021] [Indexed: 01/14/2023] Open
Abstract
Cryptococcus neoformans is a devastating opportunistic fungal pathogen. It mostly impacts people in an immunocompromised state, such as people living with HIV/AIDS and following organ transplantation. Macrophages, in addition to being a major cellular reservoir of HIV-1, represent a unique niche in which both C. neoformans and HIV-1 can coinhabit in the course of natural infection. Here, we report the observation that HIV-1 infection of THP-1 macrophages increases the rate at which they phagocytose C. neoformans cells. We investigated the tumor necrosis factor alpha (TNF-α) signaling and nuclear factor kappa B (NF-κB) activation in human monocyte-derived macrophages infected with HIV-1 alone, as well as those coinfected with HIV-1 and C. neoformans Our findings showed that while HIV-1 infection alone upregulates TNF-α production and activates NF-κB signaling, C. neoformans coinfection drastically and rapidly dampens this proinflammatory response. These data suggest an antagonism between two important human pathogens during coinfection of macrophages.IMPORTANCE Fungal infections are one of the leading causes of death for people who live with HIV/AIDS. Even though these pathogens are independently well studied, it is still enigmatic how coinfection with HIV-1 and C. neoformans alters gene expression and cellular processes, especially in clinically relevant cell types. Understanding the interplay between these two pathogens is especially critical because C. neoformans mortality largely depends on the host's immunocompromised state during viral infection. Studying this coinfection is challenging since HIV-1 only infects human cells, and the modified murine HIV-1 virus does not reproduce the clinical landmarks of HIV-1 infection or AIDS in mice. Our observations shed light on how these two pathogens trigger opposing trends in TNF-α and NF-κB signaling in human monocyte-derived macrophages.
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Affiliation(s)
- Murat C Kalem
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, SUNY, Buffalo, New York, USA
| | - Monica S Humby
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, SUNY, Buffalo, New York, USA
| | - Elizabeth A Wohlfert
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, SUNY, Buffalo, New York, USA
| | - Amy Jacobs
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, SUNY, Buffalo, New York, USA
| | - John C Panepinto
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, SUNY, Buffalo, New York, USA
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19
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Gaylord EA, Choy HL, Doering TL. Dangerous Liaisons: Interactions of Cryptococcus neoformans with Host Phagocytes. Pathogens 2020; 9:E891. [PMID: 33121050 PMCID: PMC7692806 DOI: 10.3390/pathogens9110891] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 10/22/2020] [Accepted: 10/25/2020] [Indexed: 02/07/2023] Open
Abstract
Cryptococcus neoformans is an opportunistic fungal pathogen and a leading cause of death in immunocompromised individuals. The interactions of this yeast with host phagocytes are critical to disease outcome, and C. neoformans is equipped with an array of factors to modulate these processes. Cryptococcal infection begins with the deposition of infectious particles into the lungs, where the fungal cells deploy various antiphagocytic factors to resist internalization by host cells. If the cryptococci are still engulfed, they can survive and proliferate within host cells by modulating the phagolysosome environment in which they reside. Lastly, cryptococcal cells may escape from phagocytes by host cell lysis, nonlytic exocytosis, or lateral cell-to-cell transfer. The interactions between C. neoformans and host phagocytes also influence the dissemination of this pathogen to the brain, where it may cross the blood-brain barrier and cause an often-fatal meningoencephalitis. In this review, we highlight key cryptococcal factors involved in various stages of cryptococcal-host interaction and pathogenesis.
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Affiliation(s)
| | | | - Tamara L. Doering
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA; (E.A.G.); (H.L.C.)
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20
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Normile TG, Bryan AM, Del Poeta M. Animal Models of Cryptococcus neoformans in Identifying Immune Parameters Associated With Primary Infection and Reactivation of Latent Infection. Front Immunol 2020; 11:581750. [PMID: 33042164 PMCID: PMC7522366 DOI: 10.3389/fimmu.2020.581750] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 08/12/2020] [Indexed: 12/13/2022] Open
Abstract
Cryptococcus species are environmental fungal pathogens and the causative agents of cryptococcosis. Infection occurs upon inhalation of infectious particles, which proliferate in the lung causing a primary infection. From this primary lung infection, fungal cells can eventually disseminate to other organs, particularly the brain, causing lethal meningoencephalitis. However, in most cases, the primary infection resolves with the formation of a lung granuloma. Upon severe immunodeficiency, dormant cryptococcal cells will start proliferating in the lung granuloma and eventually will disseminate to the brain. Many investigators have sought to study the protective host immune response to this pathogen in search of host parameters that keep the proliferation of cryptococcal cells under control. The majority of the work assimilates research carried out using the primary infection animal model, mainly because a reactivation model has been available only very recently. This review will focus on anti-cryptococcal immunity in both the primary and reactivation models. An understanding of the differences in host immunity between the primary and reactivation models will help to define the key host parameters that control the infections and are important for the research and development of new therapeutic and vaccine strategies against cryptococcosis.
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Affiliation(s)
- Tyler G Normile
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY, United States
| | - Arielle M Bryan
- Ingenious Targeting Laboratory Incorporated, Ronkonkoma, NY, United States
| | - Maurizio Del Poeta
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY, United States.,Division of Infectious Diseases, School of Medicine, Stony Brook University, Stony Brook, NY, United States.,Veterans Administration Medical Center, Northport, NY, United States
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21
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Dragotakes Q, Stouffer KM, Fu MS, Sella Y, Youn C, Yoon OI, De Leon-Rodriguez CM, Freij JB, Bergman A, Casadevall A. Macrophages use a bet-hedging strategy for antimicrobial activity in phagolysosomal acidification. J Clin Invest 2020; 130:3805-3819. [PMID: 32298242 PMCID: PMC7346583 DOI: 10.1172/jci133938] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 04/10/2020] [Indexed: 12/13/2022] Open
Abstract
Microbial ingestion by a macrophage results in the formation of an acidic phagolysosome but the host cell has no information on the pH susceptibility of the ingested organism. This poses a problem for the macrophage and raises the fundamental question of how the phagocytic cell optimizes the acidification process to prevail. We analyzed the dynamical distribution of phagolysosomal pH in murine and human macrophages that had ingested live or dead Cryptococcus neoformans cells, or inert beads. Phagolysosomal acidification produced a range of pH values that approximated normal distributions, but these differed from normality depending on ingested particle type. Analysis of the increments of pH reduction revealed no forbidden ordinal patterns, implying that the phagosomal acidification process was a stochastic dynamical system. Using simulation modeling, we determined that by stochastically acidifying a phagolysosome to a pH within the observed distribution, macrophages sacrificed a small amount of overall fitness to gain the benefit of reduced variation in fitness. Hence, chance in the final phagosomal pH introduces unpredictability to the outcome of the macrophage-microbe, which implies a bet-hedging strategy that benefits the macrophage. While bet hedging is common in biological systems at the organism level, our results show its use at the organelle and cellular level.
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Affiliation(s)
- Quigly Dragotakes
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, USA
| | - Kaitlin M. Stouffer
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, USA
| | - Man Shun Fu
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, USA
| | - Yehonatan Sella
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Christine Youn
- Department of Dermatology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Olivia Insun Yoon
- Johns Hopkins University, Krieger School of Arts and Sciences, Baltimore, Maryland, USA
| | - Carlos M. De Leon-Rodriguez
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, USA
| | - Joudeh B. Freij
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, USA
| | - Aviv Bergman
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, New York, USA
- Santa Fe Institute, Santa Fe, New Mexico, USA
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, USA
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22
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Thak EJ, Lee SB, Xu-Vanpala S, Lee DJ, Chung SY, Bahn YS, Oh DB, Shinohara ML, Kang HA. Core N-Glycan Structures Are Critical for the Pathogenicity of Cryptococcus neoformans by Modulating Host Cell Death. mBio 2020; 11:e00711-20. [PMID: 32398313 PMCID: PMC7218283 DOI: 10.1128/mbio.00711-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 04/13/2020] [Indexed: 12/17/2022] Open
Abstract
Cryptococcus neoformans is a human-pathogenic fungal pathogen that causes life-threatening meningoencephalitis in immunocompromised individuals. To investigate the roles of N-glycan core structure in cryptococcal pathogenicity, we constructed mutant strains of C. neoformans with defects in the assembly of lipid-linked N-glycans in the luminal side of the endoplasmic reticulum (ER). Deletion of ALG3 (alg3Δ), which encodes dolichyl-phosphate-mannose (Dol-P-Man)-dependent α-1,3-mannosyltransferase, resulted in the production of truncated neutral N-glycans carrying five mannose residues as a major species. Despite moderate or nondetectable defects in virulence-associated phenotypes in vitro, the alg3Δ mutant was avirulent in a mouse model of systemic cryptococcosis. Notably, the mutant did not show defects in early stages of host cell interaction during infection, including attachment to lung epithelial cells, opsonic/nonopsonic phagocytosis, and manipulation of phagosome acidification. However, the ability to drive macrophage cell death was greatly decreased in this mutant, without loss of cell wall remodeling capacity. Furthermore, deletion of ALG9 and ALG12, encoding Dol-P-Man-dependent α-1,2-mannosyltransferases and α-1,6-mannosyltransferases, generating truncated core N-glycans with six and seven mannose residues, respectively, also displayed remarkably reduced macrophage cell death and in vivo virulence. However, secretion levels of interleukin-1β (IL-1β) were not reduced in the bone marrow-derived dendritic cells obtained from Asc- and Gsdmd-deficient mice infected with the alg3Δ mutant strain, excluding the possibility that pyroptosis is a main host cell death pathway dependent on intact core N-glycans. Our results demonstrated N-glycan structures as a critical feature in modulating death of host cells, which is exploited by as a strategy for host cell escape for dissemination of C. neoformansIMPORTANCE We previously reported that the outer mannose chains of N-glycans are dispensable for the virulence of C. neoformans, which is in stark contrast to findings for the other human-pathogenic yeast, Candida albicans Here, we present evidence that an intact core N-glycan structure is required for C. neoformans pathogenicity by systematically analyzing alg3Δ, alg9Δ, and alg12Δ strains that have defects in lipid-linked N-glycan assembly and in in vivo virulence. The alg null mutants producing truncated core N-glycans were defective in inducing host cell death after phagocytosis, which is triggered as a mechanism of pulmonary escape and dissemination of C. neoformans, thus becoming inactive in causing fatal infection. The results clearly demonstrated the critical features of the N-glycan structure in mediating the interaction with host cells during fungal infection. The delineation of the roles of protein glycosylation in fungal pathogenesis not only provides insight into the glycan-based fungal infection mechanism but also will aid in the development of novel antifungal agents.
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Affiliation(s)
- Eun Jung Thak
- Department of Life Science, Chung-Ang University, Seoul, South Korea
| | - Su-Bin Lee
- Department of Life Science, Chung-Ang University, Seoul, South Korea
| | - Shengjie Xu-Vanpala
- Department of Immunology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Dong-Jik Lee
- Department of Life Science, Chung-Ang University, Seoul, South Korea
| | - Seung-Yeon Chung
- Department of Life Science, Chung-Ang University, Seoul, South Korea
| | - Yong-Sun Bahn
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Doo-Byoung Oh
- Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
| | - Mari L Shinohara
- Department of Immunology, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Microbiology and Molecular Genetics, Duke University School of Medicine, Durham, North Carolina, USA
| | - Hyun Ah Kang
- Department of Life Science, Chung-Ang University, Seoul, South Korea
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23
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Abstract
Among fungal pathogens, Cryptococcus neoformans has gained great importance among the scientific community of several reasons. This fungus is the causative agent of cryptococcosis, a disease mainly associated to HIV immunosuppression and characterized by the appearance of meningoencephalitis. Cryptococcal meningitis is responsible for hundreds of thousands of deaths every year. Research of the pathogenesis and virulence mechanisms of this pathogen has focused on three main different areas: Adaptation to the host environment (nutrients, pH, and free radicals), mechanism of immune evasion (which include phenotypic variations and the ability to behave as a facultative intracellular pathogen), and production of virulence factors. Cryptococcus neoformans has two phenotypic characteristics, the capsule and synthesis of melanin that have a profound effect in the virulence of the yeast because they both have protective effects and induce host damage as virulence factors. Finally, the mechanisms that result in dissemination and brain invasion are also of key importance to understand cryptococcal disease. In this review, I will provide a brief overview of the main mechanisms that makes C. neoformans a pathogen in susceptible patients. Abbreviations: RNS: reactive nitrogen species; BBB: brain blood barrier; GXM: glucuronoxylomannan; GXMGal: glucuronoxylomannogalactan
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Affiliation(s)
- Oscar Zaragoza
- a Mycology Reference Laboratory National Centre for Microbiology , Instituto de Salud Carlos III Carretera Majadahonda-Pozuelo , Madrid , Spain
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24
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Nelson BN, Hawkins AN, Wozniak KL. Pulmonary Macrophage and Dendritic Cell Responses to Cryptococcus neoformans. Front Cell Infect Microbiol 2020; 10:37. [PMID: 32117810 PMCID: PMC7026008 DOI: 10.3389/fcimb.2020.00037] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/20/2020] [Indexed: 12/12/2022] Open
Abstract
The fungal pathogen Cryptococcus neoformans can cause life-threatening infections in immune compromised individuals. This pathogen is typically acquired via inhalation, and enters the respiratory tract. Innate immune cells such as macrophages and dendritic cells (DCs) are the first host cells that encounter C. neoformans, and the interactions between Cryptococcus and innate immune cells play a critical role in the progression of disease. Cryptococcus possesses several virulence factors and evasion strategies to prevent its killing and destruction by pulmonary phagocytes, but these phagocytic cells can also contribute to anti-cryptococcal responses. This review will focus on the interactions between Cryptococcus and primary macrophages and dendritic cells (DCs), dealing specifically with the cryptococcal/pulmonary cell interface.
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Affiliation(s)
- Benjamin N Nelson
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Ashlee N Hawkins
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Karen L Wozniak
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
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25
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Abstract
Macrophages are well known for their phagocytic activity and their role in innate immune responses. Macrophages eat non-self particles, via a variety of mechanisms, and typically break down internalized cargo into small macromolecules. However, some pathogenic agents have the ability to evade this endosomal degradation through a nonlytic exocytosis process termed vomocytosis. Macrophages are well known for their phagocytic activity and their role in innate immune responses. Macrophages eat non-self particles, via a variety of mechanisms, and typically break down internalized cargo into small macromolecules. However, some pathogenic agents have the ability to evade this endosomal degradation through a nonlytic exocytosis process termed vomocytosis. This phenomenon has been most often studied for Cryptococcus neoformans, a yeast that causes roughly 180,000 deaths per year, primarily in immunocompromised (e.g., human immunodeficiency virus [HIV]) patients. Existing dogma purports that vomocytosis involves distinctive cellular pathways and intracellular physicochemical cues in the host cell during phagosomal maturation. Moreover, it has been observed that the immunological state of the individual and macrophage phenotype affect vomocytosis outcomes. Here we compile the current knowledge on the factors (with respect to the phagocytic cell) that promote vomocytosis of C. neoformans from macrophages.
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26
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Seoane PI, May RC. Vomocytosis: What we know so far. Cell Microbiol 2019; 22:e13145. [PMID: 31730731 DOI: 10.1111/cmi.13145] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/23/2019] [Accepted: 10/26/2019] [Indexed: 01/10/2023]
Abstract
Vomocytosis, or nonlytic exocytosis, has been reported for Cryptococcus neoformans since 2006. Since then, the repertoire of vomocytosing pathogens and host cells has increased and so have the molecular components linked to vomocytosis occurrence. Nonetheless, the mechanism underlying this phenomenon, whether it is triggered by the host or the pathogen, and how it affects disease progression are still unresolved. This review contains a summary of the main findings regarding vomocytosis and the outstanding questions puzzling scientists to this day.
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Affiliation(s)
- Paula I Seoane
- Laboratory of Host and Pathogen Interactions, Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, UK
| | - Robin C May
- Laboratory of Host and Pathogen Interactions, Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, UK
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27
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Pulmonary Iron Limitation Induced by Exogenous Type I IFN Protects Mice from Cryptococcus gattii Independently of T Cells. mBio 2019; 10:mBio.00799-19. [PMID: 31213551 PMCID: PMC6581853 DOI: 10.1128/mbio.00799-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cryptococcus neoformans and Cryptococcus gattii cause fatal infection in immunodeficient and immunocompetent individuals. While these fungi are sibling species, C. gattii infects very few AIDS patients, while C. neoformans infection is an AIDS-defining illness, suggesting that the host response to HIV selects C. neoformans over C. gattii. We used a viral mimic molecule (pICLC) to stimulate the immune response, and pICLC treatment improved mouse outcomes from both species. pICLC-induced action against C. neoformans was due to activation of well-defined immune pathways known to deter C. neoformans, whereas these immune pathways were dispensable for pICLC treatment of C. gattii. Since these immune pathways are eventually destroyed by HIV/AIDS, our data help explain why the antiviral immune response in AIDS patients is unable to control C. neoformans infection but is protective against C. gattii. Furthermore, pICLC induced tighter control of iron in the lungs of mice, which inhibited C. gattii, thus suggesting an entirely new mode of nutritional immunity activated by viral signals. Cryptococcus neoformans causes deadly mycosis primarily in AIDS patients, whereas Cryptococcus gattii infects mostly non-HIV patients, even in regions with high burdens of HIV/AIDS and an established environmental presence of C. gattii. As HIV induces type I IFN (t1IFN), we hypothesized that t1IFN would differentially affect the outcome of C. neoformans and C. gattii infections. Exogenous t1IFN induction using stabilized poly(I·C) (pICLC) improved murine outcomes in either cryptococcal infection. In C. neoformans-infected mice, pICLC activity was associated with C. neoformans containment and classical Th1 immunity. In contrast, pICLC activity against C. gattii did not require any immune factors previously associated with C. neoformans immunity: T, B, and NK cells, IFN-γ, and macrophages were all dispensable. Interestingly, C. gattii pICLC activity depended on β-2-microglobulin, which impacts iron levels among other functions. Iron supplementation reversed pICLC activity, suggesting C. gattii pICLC activity requires iron limitation. Also, pICLC induced a set of iron control proteins, some of which were directly inhibitory to cryptococcus in vitro, suggesting t1IFN regulates iron availability in the pulmonary air space fluids. Thus, exogenous induction of t1IFN significantly improves the outcome of murine infection by C. gattii and C. neoformans but by distinct mechanisms; the C. gattii effect was mediated by iron limitation, while the effect on C. neoformans infection was through induction of classical T-cell-dependent immunity. Together this difference in types of T-cell-dependent t1IFN immunity for different Cryptococcus species suggests a possible mechanism by which HIV infection may select against C. gattii but not C. neoformans.
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28
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Westman J, Hube B, Fairn GD. Integrity under stress: Host membrane remodelling and damage by fungal pathogens. Cell Microbiol 2019; 21:e13016. [DOI: 10.1111/cmi.13016] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/30/2019] [Accepted: 02/05/2019] [Indexed: 12/28/2022]
Affiliation(s)
- Johannes Westman
- Program in Cell Biology The Hospital for Sick Children Toronto Ontario Canada
| | - Bernhard Hube
- Department Microbial Pathogenicity Mechanisms Hans Knoell Institute Jena Germany
- Institute of Microbiology Microbial Pathogenicity Friedrich Schiller University Jena Germany
| | - Gregory D. Fairn
- Keenan Research Centre for Biomedical Sciences St. Michael's Hospital Toronto Ontario Canada
- Department of Surgery University of Toronto Toronto Ontario Canada
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29
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Abstract
Cryptococcus neoformans is the causative agent of cryptococcosis, a devastating fungal disease that affects thousands of individuals worldwide. This fungus has the capacity to survive inside phagocytic cells, which contributes to persistence of infection and dissemination. One of the major antimicrobial mechanisms of host phagocytes is to acidify the phagosomal compartment after ingestion of microbes. This study shows that the capsule of C. neoformans can interfere with full phagosomal acidification by serving as a buffer. Phagosomal acidification is a critical cellular mechanism for the inhibition and killing of ingested microbes by phagocytic cells. The acidic environment activates microbicidal proteins and creates an unfavorable environment for the growth of many microbes. Consequently, numerous pathogenic microbes have developed strategies for countering phagosomal acidification through various mechanisms that include interference with phagosome maturation. The human-pathogenic fungus Cryptococcus neoformans resides in acidic phagosomes after macrophage ingestion that actually provides a favorable environment for replication, since the fungus replicates faster at acidic pH. We hypothesized that the glucuronic acid residues in the capsular polysaccharide had the capacity to affect phagosomal acidity through their acid-base properties. A ratiometric fluorescence comparison of imaged phagosomes containing C. neoformans to phagosomes containing beads showed that the latter were significantly more acidic. Similarly, phagosomes containing nonencapsulated C. neoformans cells were more acidic than those containing encapsulated cells. Acid-base titrations of isolated C. neoformans polysaccharide revealed that it behaves as a weak acid with maximal buffering capacity around pH 4 to 5. We interpret these results as indicating that the glucuronic acid residues in the C. neoformans capsular polysaccharide can buffer phagosomal acidification. Interference with phagosomal acidification represents a new function for the cryptococcal capsule in virulence and suggests the importance of considering the acid-base properties of microbial capsules in the host-microbe interaction for other microbes with charged residues in their capsules. IMPORTANCECryptococcus neoformans is the causative agent of cryptococcosis, a devastating fungal disease that affects thousands of individuals worldwide. This fungus has the capacity to survive inside phagocytic cells, which contributes to persistence of infection and dissemination. One of the major antimicrobial mechanisms of host phagocytes is to acidify the phagosomal compartment after ingestion of microbes. This study shows that the capsule of C. neoformans can interfere with full phagosomal acidification by serving as a buffer.
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30
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Abstract
For pathogenic microbes to survive ingestion by macrophages, they must subvert powerful microbicidal mechanisms within the phagolysosome. After ingestion, Candida albicans undergoes a morphological transition producing hyphae, while the surrounding phagosome exhibits a loss of phagosomal acidity. However, how these two events are related has remained enigmatic. Now Westman et al. (mBio 9:e01226-18, 2018, https://doi.org/10.1128/mBio.01226-18) report that phagosomal neutralization results from disruption of phagosomal membrane integrity by the enlarging hyphae, directly implicating the morphological transition in physical damage that promotes intracellular survival. The C. albicans intracellular strategy shows parallels with another fungal pathogen, Cryptococcus neoformans, where a morphological changed involving capsular enlargement intracellularly is associated with loss of membrane integrity and death of the host cell. These similarities among distantly related pathogenic fungi suggest that morphological transitions that are common in fungi directly affect the outcome of the fungal cell-macrophage interaction. For this class of organisms, form determines fate in the intracellular environment.
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31
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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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32
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Camacho E, Casadevall A. Cryptococcal Traits Mediating Adherence to Biotic and Abiotic Surfaces. J Fungi (Basel) 2018; 4:jof4030088. [PMID: 30060601 PMCID: PMC6162697 DOI: 10.3390/jof4030088] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 07/25/2018] [Accepted: 07/27/2018] [Indexed: 01/22/2023] Open
Abstract
Several species in the genus Cryptococcus are facultative intracellular pathogens capable of causing disease associated with high mortality and morbidity in humans. These fungi interact with other organisms in the soil, and these interactions may contribute to the development of adaptation mechanisms that function in virulence by promoting fungal survival in animal hosts. Fungal adhesion molecules, also known as adhesins, have been classically considered as cell-surface or secreted proteins that play critical roles in microbial pathogenesis or in biofilm formation as structural components. Pathogenic Cryptococcus spp. differ from other pathogenic yeasts in having a polysaccharide capsule that covers the cell wall surface and precludes interactions of those structures with host cell receptors. Hence, pathogenic Cryptococcus spp. use unconventional tools for surface attachment. In this essay, we review the unique traits and mechanisms favoring adhesion of Cryptococcus spp. to biotic and abiotic surfaces. Knowledge of the traits that mediate adherence could be exploited in the development of therapeutic, biomedical, and/or industrial products.
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Affiliation(s)
- Emma Camacho
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, 615 N Wolfe St Room E5132, Baltimore, MD 21205, USA.
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, 615 N Wolfe St Room E5132, Baltimore, MD 21205, USA.
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33
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Fu MS, Coelho C, De Leon-Rodriguez CM, Rossi DCP, Camacho E, Jung EH, Kulkarni M, Casadevall A. Cryptococcus neoformans urease affects the outcome of intracellular pathogenesis by modulating phagolysosomal pH. PLoS Pathog 2018; 14:e1007144. [PMID: 29906292 PMCID: PMC6021110 DOI: 10.1371/journal.ppat.1007144] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 06/27/2018] [Accepted: 06/05/2018] [Indexed: 01/22/2023] Open
Abstract
Cryptococcus neoformans is a facultative intracellular pathogen and its interaction with macrophages is a key event determining the outcome of infection. Urease is a major virulence factor in C. neoformans but its role during macrophage interaction has not been characterized. Consequently, we analyzed the effect of urease on fungal-macrophage interaction using wild-type, urease-deficient and urease-complemented strains of C. neoformans. The frequency of non-lytic exocytosis events was reduced in the absence of urease. Urease-positive C. neoformans manifested reduced and delayed intracellular replication with fewer macrophages displaying phagolysosomal membrane permeabilization. The production of urease was associated with increased phagolysosomal pH, which in turn reduced growth of urease-positive C. neoformans inside macrophages. Interestingly, the ure1 mutant strain grew slower in fungal growth medium which was buffered to neutral pH (pH 7.4). Mice inoculated with macrophages carrying urease-deficient C. neoformans had lower fungal burden in the brain than mice infected with macrophages carrying wild-type strain. In contrast, the absence of urease did not affect survival of yeast when interacting with amoebae. Because of the inability of the urease deletion mutant to grow on urea as a sole nitrogen source, we hypothesize urease plays a nutritional role involved in nitrogen acquisition in the environment. Taken together, our data demonstrate that urease affects fitness within the mammalian phagosome, promoting non-lytic exocytosis while delaying intracellular replication and thus reducing phagolysosomal membrane damage, events that could facilitate cryptococcal dissemination when transported inside macrophages. This system provides an example where an enzyme involved in nutrient acquisition modulates virulence during mammalian infection.
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Affiliation(s)
- Man Shun Fu
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Carolina Coelho
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Carlos M. De Leon-Rodriguez
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Diego C. P. Rossi
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Emma Camacho
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Eric H. Jung
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Madhura Kulkarni
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
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