1
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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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2
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Viveiro LRDG, Rehem AR, Santos ELDS, do Carmo PHF, Junqueira JC, Scorzoni L. In vitro effects of selective serotonin reuptake inhibitors on Cryptococcus gattii capsule and biofilm. Pathog Dis 2024; 82:ftae001. [PMID: 38204138 PMCID: PMC10849314 DOI: 10.1093/femspd/ftae001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 10/23/2023] [Accepted: 01/09/2024] [Indexed: 01/12/2024] Open
Abstract
Infections caused by Cryptococcus gattii mainly affect immunocompetent individuals and the treatment presents important limitations. This study aimed to validate the efficacy of selective serotonin reuptake inhibitors (SSRI), fluoxetine hydrochloride (FLH), and paroxetine hydrochloride (PAH) in vitro against C. gattii. The antifungal activity of SSRI using the microdilution method revealed a minimal inhibitory concentration (MIC) of 31.25 µg/ml. The combination of FLH or PAH with amphotericin B (AmB) was analyzed using the checkerboard assay and the synergistic effect of SSRI in combination with AmB was able to reduce the SSRI or AmB MIC values 4-8-fold. When examining the effect of SSRI on the induced capsules, we observed that FLH and PAH significantly decreased the size of C. gattii capsules. In addition, the effects of FLH and PAH were evaluated in biofilm biomass and viability. The SSRI were able to reduce biofilm biomass and biofilm viability. In conclusion, our results indicate the use of FLH and PAH exhibited in vitro anticryptococcal activity, representing a possible future alternative for the cryptococcosis treatment.
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Affiliation(s)
- Letícia Rampazzo da Gama Viveiro
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), São Paulo 12245-000, Brazil
| | - Amanda Rodrigues Rehem
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), São Paulo 12245-000, Brazil
| | - Evelyn Luzia De Souza Santos
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), São Paulo 12245-000, Brazil
| | - Paulo Henrique Fonseca do Carmo
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), São Paulo 12245-000, Brazil
| | - Juliana Campos Junqueira
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), São Paulo 12245-000, Brazil
| | - Liliana Scorzoni
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), São Paulo 12245-000, Brazil
- Programa de Pós-Graduação em Enfermagem, Universidade de Guarulhos, Guarulhos, São Paulo 07023-070, Brazil
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3
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Boodwa-Ko D, Doering TL. A Quick reCAP: Discovering Cryptococcus neoformans Capsule Mutants. J Fungi (Basel) 2024; 10:114. [PMID: 38392786 PMCID: PMC10889740 DOI: 10.3390/jof10020114] [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: 12/26/2023] [Revised: 01/25/2024] [Accepted: 01/27/2024] [Indexed: 02/24/2024] Open
Abstract
Cryptococcus neoformans is an opportunistic fungal pathogen that can cause severe meningoencephalitis in immunocompromised hosts and is a leading cause of death in HIV/AIDS patients. This pathogenic yeast is surrounded by a polysaccharide capsule that is critical for virulence and plays important roles in host-pathogen interactions. Understanding capsule biosynthesis is therefore key to defining the biology of C. neoformans and potentially discovering novel therapeutic targets. By exploiting methods to identify mutants deficient in capsule, June Kwon-Chung and other investigators have discovered numerous genes involved in capsule biosynthesis and regulation. Successful approaches have incorporated combinations of techniques including mutagenesis and systematic gene deletion; complementation and genetic screens; morphological examination, physical separation, and antibody binding; and computational modeling based on gene expression analysis. In this review, we discuss these methods and how they have been used to identify capsule mutants.
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Affiliation(s)
- Daphne Boodwa-Ko
- Department of Molecular Microbiology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Tamara L Doering
- Department of Molecular Microbiology, Washington University in St. Louis, St. Louis, MO 63110, USA
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4
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Melhem MSC, Leite Júnior DP, Takahashi JPF, Macioni MB, Oliveira LD, de Araújo LS, Fava WS, Bonfietti LX, Paniago AMM, Venturini J, Espinel-Ingroff A. Antifungal Resistance in Cryptococcal Infections. Pathogens 2024; 13:128. [PMID: 38392866 PMCID: PMC10891860 DOI: 10.3390/pathogens13020128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 01/20/2024] [Accepted: 01/22/2024] [Indexed: 02/25/2024] Open
Abstract
Antifungal therapy, especially with the azoles, could promote the incidence of less susceptible isolates of Cryptococcus neoformans and C. gattii species complexes (SC), mostly in developing countries. Given that these species affect mostly the immunocompromised host, the infections are severe and difficult to treat. This review encompasses the following topics: 1. infecting species and their virulence, 2. treatment, 3. antifungal susceptibility methods and available categorical endpoints, 4. genetic mechanisms of resistance, 5. clinical resistance, 6. fluconazole minimal inhibitory concentrations (MICs), clinical outcome, 7. environmental influences, and 8. the relevance of host factors, including pharmacokinetic/pharmacodynamic (PK/PD) parameters, in predicting the clinical outcome to therapy. As of now, epidemiologic cutoff endpoints (ECVs/ECOFFs) are the most reliable antifungal resistance detectors for these species, as only one clinical breakpoint (amphotericin B and C. neoformans VNI) is available.
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Affiliation(s)
- Marcia S C Melhem
- Graduate Program in Sciences, Secretary of Health, São Paulo 01246-002, SP, Brazil
- Graduate Program in Infectious and Parasitic Diseases, Federal University of Mato Grosso do Sul, Campo Grande 79070-900, MS, Brazil
- Graduate Program in Tropical Diseases, State University of São Paulo, Botucatu 18618-687, SP, Brazil
| | | | - Juliana P F Takahashi
- Graduate Program in Infectious and Parasitic Diseases, Federal University of Mato Grosso do Sul, Campo Grande 79070-900, MS, Brazil
- Pathology Division, Adolfo Lutz Institute, São Paulo 01246-002, SP, Brazil
| | | | | | - Lisandra Siufi de Araújo
- Graduate Program in Infectious and Parasitic Diseases, Federal University of Mato Grosso do Sul, Campo Grande 79070-900, MS, Brazil
- Central Public Health Laboratory-LACEN, Mycology Unit, Adolfo Lutz Institut, São Paulo 01246-002, SP, Brazil
| | - Wellington S Fava
- Graduate Program in Infectious and Parasitic Diseases, Federal University of Mato Grosso do Sul, Campo Grande 79070-900, MS, Brazil
| | - Lucas X Bonfietti
- Central Public Health Laboratory-LACEN, Mycology Unit, Adolfo Lutz Institut, São Paulo 01246-002, SP, Brazil
| | - Anamaria M M Paniago
- Graduate Program in Infectious and Parasitic Diseases, Federal University of Mato Grosso do Sul, Campo Grande 79070-900, MS, Brazil
| | - James Venturini
- Graduate Program in Infectious and Parasitic Diseases, Federal University of Mato Grosso do Sul, Campo Grande 79070-900, MS, Brazil
| | - Ana Espinel-Ingroff
- Central Public Health Laboratory-LACEN, Campo Grande 79074-460, MS, Brazil
- VCU Medical Center, Richmond, VA 23284, USA
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5
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Miramón P, Pountain AW, Lorenz MC. Candida auris-macrophage cellular interactions and transcriptional response. Infect Immun 2023; 91:e0027423. [PMID: 37815367 PMCID: PMC10652981 DOI: 10.1128/iai.00274-23] [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: 07/14/2023] [Accepted: 08/29/2023] [Indexed: 10/11/2023] Open
Abstract
The pathogenic yeast Candida auris represents a global threat of the utmost clinical relevance. This emerging fungal species is remarkable in its resistance to commonly used antifungal agents and its persistence in the nosocomial settings. The innate immune system is one the first lines of defense preventing the dissemination of pathogens in the host. C. auris is susceptible to circulating phagocytes, and understanding the molecular details of these interactions may suggest routes to improved therapies. In this work, we examined the interactions of this yeast with macrophages. We found that macrophages avidly phagocytose C. auris; however, intracellular replication is not inhibited, indicating that C. auris resists the killing mechanisms imposed by the phagocyte. Unlike Candida albicans, phagocytosis of C. auris does not induce macrophage lysis. The transcriptional response of C. auris to macrophage phagocytosis is very similar to other members of the CUG clade (C. albicans, C. tropicalis, C. parapsilosis, C. lusitaniae), i.e., downregulation of transcription/translation and upregulation of alternative carbon metabolism pathways, transporters, and induction of oxidative stress response and proteolysis. Gene family expansions are common in this yeast, and we found that many of these genes are induced in response to macrophage co-incubation. Among these, amino acid and oligopeptide transporters, as well as lipases and proteases, are upregulated. Thus, C. auris shares key transcriptional signatures shared with other fungal pathogens and capitalizes on the expansion of gene families coding for potential virulence attributes that allow its survival, persistence, and evasion of the innate immune system.
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Affiliation(s)
- Pedro Miramón
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, USA
| | | | - Michael C. Lorenz
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, USA
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6
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Wilde S, Dash A, Johnson A, Mackey K, Okumura CYM, LaRock CN. Detoxification of reactive oxygen species by the hyaluronic acid capsule of group A Streptococcus. Infect Immun 2023; 91:e0025823. [PMID: 37874162 PMCID: PMC10652860 DOI: 10.1128/iai.00258-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 09/17/2023] [Indexed: 10/25/2023] Open
Abstract
The pro-inflammatory cytokine IL-6 regulates antimicrobial responses that are broadly crucial in the defense against infection. Our prior work shows that IL-6 promotes the killing of the M4 serotype group A Streptococcus (GAS) but does not impact the globally disseminated M1T1 serotype associated with invasive infections. Using in vitro and in vivo infection models, we show that IL-6 induces phagocyte reactive oxygen species (ROS) that are responsible for the differential susceptibility of M4 and M1T1 GAS to IL-6-mediated defenses. Clinical isolates naturally deficient in capsule, or M1T1 strains deficient in capsule production, are sensitive to this ROS killing. The GAS capsule is made of hyaluronic acid, an antioxidant that detoxifies ROS and can protect acapsular M4 GAS when added exogenously. During in vitro interactions with macrophages and neutrophils, acapsular GAS can also be rescued with the antioxidant N-acetylcysteine, suggesting this is a major virulence contribution of the capsule. In an intradermal infection model with gp91phox -/- (chronic granulomatous disease [CGD]) mice, phagocyte ROS production had a modest effect on bacterial proliferation and the cytokine response but significantly limited the size of the bacterial lesion in the skin. These data suggest that the capsule broadly provides enhanced resistance to phagocyte ROS but is not essential for invasive infection. Since capsule-deficient strains are observed across several GAS serotypes and are competent for transmission and both mild and invasive infections, additional host or microbe factors may contribute to ROS detoxification during GAS infections.
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Affiliation(s)
- Shyra Wilde
- Microbiology and Molecular Genetics Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, Georgia, USA
| | - Ananya Dash
- Immunology and Molecular Pathogenesis Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, Georgia, USA
| | - Anders Johnson
- Microbiology and Molecular Genetics Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, Georgia, USA
| | - Kialani Mackey
- Department of Biology, Occidental College, Los Angeles, California, USA
| | | | - Christopher N. LaRock
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
- Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia, USA
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7
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Tugume L, Ssebambulidde K, Kasibante J, Ellis J, Wake RM, Gakuru J, Lawrence DS, Abassi M, Rajasingham R, Meya DB, Boulware DR. Cryptococcal meningitis. Nat Rev Dis Primers 2023; 9:62. [PMID: 37945681 DOI: 10.1038/s41572-023-00472-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/09/2023] [Indexed: 11/12/2023]
Abstract
Cryptococcus neoformans and Cryptococcus gattii species complexes cause meningoencephalitis with high fatality rates and considerable morbidity, particularly in persons with deficient T cell-mediated immunity, most commonly affecting people living with HIV. Whereas the global incidence of HIV-associated cryptococcal meningitis (HIV-CM) has decreased over the past decade, cryptococcosis still accounts for one in five AIDS-related deaths globally due to the persistent burden of advanced HIV disease. Moreover, mortality remains high (~50%) in low-resource settings. The armamentarium to decrease cryptococcosis-associated mortality is expanding: cryptococcal antigen screening in the serum and pre-emptive azole therapy for cryptococcal antigenaemia are well established, whereas enhanced pre-emptive combination treatment regimens to improve survival of persons with cryptococcal antigenaemia are in clinical trials. Short courses (≤7 days) of amphotericin-based therapy combined with flucytosine are currently the preferred options for induction therapy of cryptococcal meningitis. Whether short-course induction regimens improve long-term morbidity such as depression, reduced neurocognitive performance and physical disability among survivors is the subject of further study. Here, we discuss underlying immunology, changing epidemiology, and updates on the management of cryptococcal meningitis with emphasis on HIV-associated disease.
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Affiliation(s)
- Lillian Tugume
- Infectious Diseases Institute, Makerere University, Kampala, Uganda.
| | - Kenneth Ssebambulidde
- Infectious Diseases Institute, Makerere University, Kampala, Uganda
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - John Kasibante
- Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - Jayne Ellis
- Infectious Diseases Institute, Makerere University, Kampala, Uganda
- Clinical Research Department, Faculty of Infectious and Tropical Diseases London School of Hygiene and Tropical Medicine, London, UK
| | - Rachel M Wake
- Institute for Infection and Immunity, St George's University of London, London, UK
| | - Jane Gakuru
- Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - David S Lawrence
- Clinical Research Department, Faculty of Infectious and Tropical Diseases London School of Hygiene and Tropical Medicine, London, UK
- Botswana Harvard AIDS Institute Partnership, Gaborone, Botswana
| | - Mahsa Abassi
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Radha Rajasingham
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - David B Meya
- Infectious Diseases Institute, Makerere University, Kampala, Uganda
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - David R Boulware
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
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8
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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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9
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Sauters TJC, Roth C, Murray D, Sun S, Floyd Averette A, Onyishi CU, May RC, Heitman J, Magwene PM. Amoeba predation of Cryptococcus: A quantitative and population genomic evaluation of the accidental pathogen hypothesis. PLoS Pathog 2023; 19:e1011763. [PMID: 37956179 PMCID: PMC10681322 DOI: 10.1371/journal.ppat.1011763] [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: 04/18/2023] [Revised: 11/27/2023] [Accepted: 10/18/2023] [Indexed: 11/15/2023] Open
Abstract
The "Amoeboid Predator-Fungal Animal Virulence Hypothesis" posits that interactions with environmental phagocytes shape the evolution of virulence traits in fungal pathogens. In this hypothesis, selection to avoid predation by amoeba inadvertently selects for traits that contribute to fungal escape from phagocytic immune cells. Here, we investigate this hypothesis in the human fungal pathogens Cryptococcus neoformans and Cryptococcus deneoformans. Applying quantitative trait locus (QTL) mapping and comparative genomics, we discovered a cross-species QTL region that is responsible for variation in resistance to amoeba predation. In C. neoformans, this same QTL was found to have pleiotropic effects on melanization, an established virulence factor. Through fine mapping and population genomic comparisons, we identified the gene encoding the transcription factor Bzp4 that underlies this pleiotropic QTL and we show that decreased expression of this gene reduces melanization and increases susceptibility to amoeba predation. Despite the joint effects of BZP4 on amoeba resistance and melanin production, we find no relationship between BZP4 genotype and escape from macrophages or virulence in murine models of disease. Our findings provide new perspectives on how microbial ecology shapes the genetic architecture of fungal virulence, and suggests the need for more nuanced models for the evolution of pathogenesis that account for the complexities of both microbe-microbe and microbe-host interactions.
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Affiliation(s)
- Thomas J. C. Sauters
- Department of Biology, Duke University, Durham, North Carolina, United States of America
- University Program in Genetics and Genomics, Duke University, Durham, North Carolina, United States of America
| | - Cullen Roth
- Department of Biology, Duke University, Durham, North Carolina, United States of America
- University Program in Genetics and Genomics, Duke University, Durham, North Carolina, United States of America
| | - Debra Murray
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America
| | - Anna Floyd Averette
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America
| | - Chinaemerem U. Onyishi
- School of Biosciences, College of Life and Environmental Sciences, The University of Birmingham, Birmingham, United Kingdom
| | - Robin C. May
- School of Biosciences, College of Life and Environmental Sciences, The University of Birmingham, Birmingham, United Kingdom
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America
| | - Paul M. Magwene
- Department of Biology, Duke University, Durham, North Carolina, United States of America
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10
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Munzen ME, Reguera Gomez M, Hamed MF, Enriquez V, Charles-Niño CL, Dores MR, Alviña K, Martinez LR. Palmitoylethanolamide shows limited efficacy in controlling cerebral cryptococcosis in vivo. Antimicrob Agents Chemother 2023; 67:e0045923. [PMID: 37750714 PMCID: PMC10583666 DOI: 10.1128/aac.00459-23] [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: 04/07/2023] [Accepted: 07/13/2023] [Indexed: 09/27/2023] Open
Abstract
Cryptococcus neoformans (Cn) is an encapsulated neurotropic fungal pathogen and the causative agent of cryptococcal meningoencephalitis (CME) in humans. Recommended treatment for CME is Amphotericin B (AmpB) and 5-fluorocytosine (5-FC). Though effective, AmpB has displayed numerous adverse side effects due to its potency and nephrotoxicity, prompting investigation into alternative treatments. Palmitoylethanolamide (PEA) is an immunomodulatory compound capable of promoting neuroprotection and reducing inflammation. To investigate the efficacy of PEA as a therapeutic alternative for CME, we intracerebrally infected mice with Cn and treated them with PEA or AmpB alone or in combination. Our results demonstrate that PEA alone does not significantly prolong survival nor reduce fungal burden, but when combined with AmpB, PEA exerts an additive effect and promotes both survivability and fungal clearance. However, we compared this combination to traditional AmpB and 5-FC treatment in a survivability study and observed lower efficacy. Overall, our study revealed that PEA alone is not effective as an antifungal agent in the treatment of CME. Importantly, we describe the therapeutic capability of PEA in the context of Cn infection and show that its immunomodulatory properties may confer limited protection when combined with an effective fungicidal agent.
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Affiliation(s)
- Melissa E. Munzen
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Marta Reguera Gomez
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Mohamed F. Hamed
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
- Department of Pathology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Vanessa Enriquez
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Claudia L. Charles-Niño
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Michael R. Dores
- Department of Biology, Hofstra University, Hempstead, New York, USA
| | - Karina Alviña
- Department of Neuroscience, University of Florida, Gainesville, Florida, USA
- Center for Translational Research in Neurodegenerative Disease, Gainesville, Florida, USA
| | - Luis R. Martinez
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
- Center for Translational Research in Neurodegenerative Disease, Gainesville, Florida, USA
- Center for Immunology and Transplantation, Gainesville, Florida, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
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11
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Carvalho JHDS, Nascimento JKC, Silva KGV, Silveira Neto S, Macedo ATD, Lima França H, Ferreira LDR, Silva RDS, Sa JC, Ramos DG, Marques DDAV, Furst C, Santos DA, Santos JRA, Holanda RA. Yeast-amoeba interaction influences murine cryptococcosis. Microbes Infect 2023; 25:105153. [PMID: 37244475 DOI: 10.1016/j.micinf.2023.105153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 05/21/2023] [Accepted: 05/22/2023] [Indexed: 05/29/2023]
Abstract
The virulence of Cryptococcus spp. is modulated in the natural environment through interaction with abiotic and biotic factors, and this can occasionally have implications for the progression of cryptococcosis in mammals. Hence, we evaluated whether the prior interaction of highly virulent Cryptococcus gattii strain R265 with Acanthamoeba castellanii influenced the progression of cryptococcosis. The influence of the capsule on endocytosis was evaluated using amoeba and yeast morphometrics. Mice were intratracheally infected with yeast re-isolated from the amoeba (Interaction), yeast without prior contact with the amoeba (Non-Interaction), or sterile phosphate-buffered saline (SHAM). Morbidity signs and symptoms were monitored during the survival curve, while cytokine and fungal burden measurements and histopathological analysis were performed on the 10th day post infection. Morbidity and mortality parameters in experimental cryptococcosis were influenced by the prior interaction of yeast with amoeba, which led to phenotypic changes in the cryptococcal cells, polysaccharide secretion, and their tolerance to oxidative stress. Our results suggest that a prior yeast-amoeba interaction modulates yeast virulence, which is associated with a greater tolerance to oxidative stress related to the exo-polysaccharide content and influences the progression of cryptococcal infection.
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Affiliation(s)
| | | | | | - Sebastiao Silveira Neto
- Laboratório de Biologia Molecular de Microrganismos Patogênicos, Universidade CEUMA, São Luís, Maranhão, Brazil
| | | | - Hermeson Lima França
- Laboratório de Biologia Molecular de Microrganismos Patogênicos, Universidade CEUMA, São Luís, Maranhão, Brazil
| | - Larissa Dos Reis Ferreira
- Laboratório de Biologia Molecular de Microrganismos Patogênicos, Universidade CEUMA, São Luís, Maranhão, Brazil
| | - Rayssa de Sousa Silva
- Laboratório de Biologia Molecular de Microrganismos Patogênicos, Universidade CEUMA, São Luís, Maranhão, Brazil
| | - Joicy Cortez Sa
- Laboratório de Imunologia, Universidade CEUMA, São Luís, Maranhão, Brazil
| | - Diego Gomes Ramos
- Laboratório Integrado de Biotecnologia Aplicada, Universidade de Pernambuco, Recife, Pernambuco, Brazil
| | | | - Cinthia Furst
- Departamento de Patologia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo, Brazil
| | - Daniel Assis Santos
- Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | | | - Rodrigo Assuncao Holanda
- Laboratório de Biologia Molecular de Microrganismos Patogênicos, Universidade CEUMA, São Luís, Maranhão, Brazil.
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12
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Lee SH, Jang YB, Choi Y, Lee Y, Shin BN, Lee HS, Lee JS, Bahn YS. Adenylyl-Sulfate Kinase (Met14)-Dependent Cysteine and Methionine Biosynthesis Pathways Contribute Distinctively to Pathobiological Processes in Cryptococcus neoformans. Microbiol Spectr 2023; 11:e0068523. [PMID: 37036370 PMCID: PMC10269642 DOI: 10.1128/spectrum.00685-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 03/17/2023] [Indexed: 04/11/2023] Open
Abstract
Blocking of nutrient uptake and amino acid biosynthesis are considered potential targets for next-generation antifungal drugs against pathogenic fungi, including Cryptococcus neoformans. In this regard, the sulfate assimilation pathway is particularly attractive, as it is only present in eukaryotes such as plants and fungi, yet not in mammals. Here, we demonstrated that the adenylyl sulfate kinase (Met14) in the sulfate assimilation pathway is not essential yet is required for the viability of C. neoformans due to its involvement in biosynthesis of two sulfur-containing amino acids, cysteine and methionine. Met14-dependent cysteine and methionine biosynthesis was found to significantly contribute to a diverse range of pathobiological processes in C. neoformans. Met14-dependent cysteine rather than methionine biosynthesis was also found to play pivotal roles in cell growth and tolerance to environmental stresses and antifungal drugs. In contrast, the Met14-dependent methionine biosynthesis was found to be more important than cysteine biosynthesis for the production of major cryptococcal virulence factors of melanin pigments and polysaccharide capsules. Finally, we also found that despite its attenuated virulence in an insect model, Galleria mellonella, the met14Δ mutant yielded no difference in virulence in a murine model of systemic cryptococcosis. Hence, clinical inhibition of Met14-dependent amino acid biosynthetic pathways may not be advantageous for the treatment of systemic cryptococcosis. IMPORTANCE Current antifungal drugs have several limitations, such as drug resistance, severe side effects, and a narrow spectrum. Therefore, novel antifungal targets are urgently needed. To this end, fungal sulfur amino acid biosynthetic pathways are considered potential targets for development of new antifungal agents. Here, we demonstrated that Met14 in the sulfate assimilation pathway promotes growth, stress response, and virulence factor production in C. neoformans via synthesis of sulfur-containing amino acids methionine and cysteine. Met14-dependent cysteine rather than methionine synthesis was found to be critical for growth and stress responses, whereas Met14-dependent methionine synthesis was more important for the production of antiphagocytic capsules and antioxidant melanin in C. neoformans. Surprisingly, deletion of the MET14 gene was found to attenuate cryptococcal virulence in an insect model, yet not in a murine model. Collectively, our results showed that Met14-dependent cysteine and methionine biosynthesis play roles that are distinct from each other in C. neoformans. Moreover, Met14 is unlikely to be a suitable anticryptococcal drug target.
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Affiliation(s)
- Seung-Heon Lee
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Yu-Byeong Jang
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Yeseul Choi
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Yujin Lee
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Bich Na Shin
- AmtixBio Co., Ltd., Hanam-si, Gyeonggi-do, Republic of Korea
| | - Han-Seung Lee
- AmtixBio Co., Ltd., Hanam-si, Gyeonggi-do, Republic of Korea
| | - Jong-Seung Lee
- AmtixBio Co., Ltd., Hanam-si, Gyeonggi-do, Republic of Korea
| | - Yong-Sun Bahn
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
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13
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Munzen ME, Reguera-Gomez M, Hamed MF, Enriquez V, Charles-Nino CL, Dores MR, Alviña K, Martinez LR. Palmitoylethanolamide shows limited efficacy in controlling cerebral cryptococcosis in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.10.536237. [PMID: 37090670 PMCID: PMC10120726 DOI: 10.1101/2023.04.10.536237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Cryptococcus neoformans ( Cn ) is an encapsulated neurotropic fungal pathogen and the causative agent of cryptococcal meningoencephalitis (CME) in humans. Recommended treatment for CME is Amphotericin B (AmpB) and 5-fluorocytosine (5-FC). Though effective, AmpB has displayed numerous adverse side effects due to its potency and nephrotoxicity, prompting investigation into alternative treatments. Palmitoylethanolamide (PEA) is an immunomodulatory compound capable of promoting neuroprotection and reducing inflammation. To investigate the efficacy of PEA as a therapeutic alternative for CME, we intracerebrally infected mice with Cn and treated them with PEA or AmpB alone or in combination. Our results demonstrate that PEA alone does not significantly prolong survival nor reduce fungal burden, but when combined with AmpB, PEA exerts an additive effect and promotes both survivability and fungal clearance. However, we compared this combination to traditional AmpB and 5-FC treatment in a survivability study and observed lower efficacy. Overall, our study revealed that PEA alone is not effective as an antifungal agent in the treatment of CME. Importantly, we describe the therapeutic capability of PEA in the context of Cn infection and show that its immunomodulatory properties may confer limited protection when combined with an effective fungicidal agent.
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Affiliation(s)
- Melissa E. Munzen
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
| | - Marta Reguera-Gomez
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
| | - Mohamed F. Hamed
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
- Department of Pathology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Vanessa Enriquez
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
| | - Claudia L. Charles-Nino
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
| | | | - Karina Alviña
- Department of Neuroscience, University of Florida, Gainesville, FL, USA
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, USA
| | - Luis R. Martinez
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, USA
- Center for Immunology and Transplantation, University of Florida, Gainesville, FL, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
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14
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De Jesus DFF, De Freitas ALD, De Oliveira IM, De Almeida LC, Bastos RW, Spadari CDC, Melo ASDA, Santos DDA, Costa-Lotufo LV, Reis FCG, Rodrigues ML, Stefani HA, Ishida K. Organoselenium Has a Potent Fungicidal Effect on Cryptococcus neoformans and Inhibits the Virulence Factors. Antimicrob Agents Chemother 2023; 67:e0075922. [PMID: 36815840 PMCID: PMC10019174 DOI: 10.1128/aac.00759-22] [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: 05/30/2022] [Accepted: 01/14/2023] [Indexed: 02/24/2023] Open
Abstract
Cryptococcosis therapy is often limited by toxicity problems, antifungal tolerance, and high costs. Studies approaching chalcogen compounds, especially those containing selenium, have shown promising antifungal activity against pathogenic species. This work aimed to evaluate the in vitro and in vivo antifungal potential of organoselenium compounds against Cryptococcus neoformans. The lead compound LQA_78 had an inhibitory effect on C. neoformans planktonic cells and dispersed cells from mature biofilms at similar concentrations. The fungal growth inhibition led to an increase in budding cells arrested in the G2/M phase, but the compound did not significantly affect structural cell wall components or chitinase activity, an enzyme that regulates the dynamics of the cell wall. The compound also inhibited titan cell (Tc) and enlarged capsule yeast (NcC) growth and reduced the body diameter and capsule thickness associated with increased capsular permeability of both virulent morphotypes. LQA_78 also reduced fungal melanization through laccase activity inhibition. The fungicidal activity was observed at higher concentrations (16 to 64 μg/mL) and may be associated with augmented plasma membrane permeability, ROS production, and loss of mitochondrial membrane potential. While LQA_78 is a nonhemolytic compound, its cytotoxic effects were cell type dependent, exhibiting no toxicity on Galleria mellonella larvae at a dose ≤46.5 mg/kg. LQA_78 treatment of larvae infected with C. neoformans effectively reduced the fungal burden and inhibited virulent morphotype formation. To conclude, LQA_78 displays fungicidal action and inhibits virulence factors of C. neoformans. Our results highlight the potential use of LQA_78 as a lead molecule for developing novel pharmaceuticals for treating cryptococcosis.
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Affiliation(s)
| | | | | | | | - Rafael Wesley Bastos
- Center of Biosciences, Federal University of Rio Grande do Norte (UFRN), Natal, Brazil
| | | | | | - Daniel de Assis Santos
- Institute of Biomedical Sciences, Federal University of Minas Gerais (UFMG), Belo Horizonte, Brazil
| | | | - Flavia C. G. Reis
- Carlos Chagas Institute, Oswaldo Cruz Foundation, Curitiba, Brazil
- Center for Technological Development in Health (CDTS), Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Marcio L. Rodrigues
- Carlos Chagas Institute, Oswaldo Cruz Foundation, Curitiba, Brazil
- Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
| | | | - Kelly Ishida
- Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, Brazil
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15
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Liu Y, Zhang Y, Zhao X, Lu W, Zhong Y, Fu YV. Antifungal Peptide SP1 Damages Polysaccharide Capsule of Cryptococcus neoformans and Enhances Phagocytosis of Macrophages. Microbiol Spectr 2023; 11:e0456222. [PMID: 36916981 PMCID: PMC10100895 DOI: 10.1128/spectrum.04562-22] [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: 11/08/2022] [Accepted: 02/22/2023] [Indexed: 03/16/2023] Open
Abstract
Cryptococcus neoformans is a fungal pathogen which causes nearly half a million deaths worldwide each year. Under host-relevant conditions, it produces a characteristic polysaccharide capsule. The polysaccharide capsule is one of the main virulence factors of C. neoformans, which involves antiphagocytosis and immune responses of the host to cause a lack of an immune. Meanwhile, the polysaccharide capsule is a promising drug target because of the absence of analogs in the host. Here, we demonstrate that antifungal peptide SP1, which is derived from the N terminus of Saccharomyces cerevisiae GAPDH (glyceraldehyde-3-phosphate dehydrogenase), disrupts the polysaccharide capsule of C. neoformans H99. The mechanism is possibly due to the interaction of SP1 with glucuronoxylomannan (GXM). Disruption of the polysaccharide capsule enhances the adhesion and phagocytosis of C. neoformans H99 by macrophages and reduces the replication of C. neoformans H99 within macrophages. Additionally, SP1 exhibits antifungal activity against cryptococcal biofilms associated with the capsular polysaccharides. These findings suggest the potential of SP1 as a drug candidate for the treatment of cryptococcosis. IMPORTANCE C. neoformans is an opportunistic pathogen that causes invasive infections with a high mortality rate. Currently, the clinical drugs available for the treatment of cryptococcosis are limited to amphotericin B, azoles, and flucytosine. Amphotericin is nephrotoxic, and the widespread use of azoles and 5-flucytosine has led to a rapid development of drug resistance in C. neoformans. There is an urgent need to develop new and effective anticryptococcal drugs. Targeting virulence factors is a novel strategy for developing antifungal drugs. The antifungal peptide SP1 is capable of disrupting the polysaccharide capsule, which is a principal virulence factor of C. neoformans. Studying the mechanism by which SP1 damages the polysaccharide capsule and investigating the potential benefits of SP1 in removing C. neoformans from the host provides baseline data to develop a therapeutic strategy against refractory cryptococcal infections. This strategy would involve both inhibiting virulence factors and directly killing C. neoformans cells.
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Affiliation(s)
- Yan Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Yang Zhang
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Xi Zhao
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Weilai Lu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Yuxin Zhong
- Department of Pancreatic and Gastric Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yu V. Fu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
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16
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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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17
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Sato K, Kawakami K. Mouse Model of Latent Cryptococcal Infection and Reactivation. Methods Mol Biol 2023; 2667:87-98. [PMID: 37145277 DOI: 10.1007/978-1-0716-3199-7_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
AbstractCryptococcus neoformans is an opportunistic fungal pathogen that frequently causes fatal meningoencephalitis in patients with impaired immune responses. This fungus, an intracellularly growing microbe, evades host immunity, leading to a latent infection (latent C. neoformans infection: LCNI), and cryptococcal disease is developed by its reactivation when host immunity is suppressed. Elucidation of the pathophysiology of LCNI is difficult due to the lack of mouse models. Here we show the established methods for LCNI and reactivation.
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Affiliation(s)
- Ko Sato
- Department of Medical Microbiology, Mycology and Immunology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
- Department of Intelligent Network for Infection Control, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
| | - Kazuyoshi Kawakami
- Department of Medical Microbiology, Mycology and Immunology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
- Department of Intelligent Network for Infection Control, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
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18
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Jang EH, Kim JS, Yu SR, Bahn YS. Unraveling Capsule Biosynthesis and Signaling Networks in Cryptococcus neoformans. Microbiol Spectr 2022; 10:e0286622. [PMID: 36287085 PMCID: PMC9769619 DOI: 10.1128/spectrum.02866-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 09/29/2022] [Indexed: 01/09/2023] Open
Abstract
The polysaccharide capsule of Cryptococcus neoformans-an opportunistic basidiomycete pathogen and the major etiological agent of fungal meningoencephalitis-is a key virulence factor that prevents its phagocytosis by host innate immune cells. However, the complex signaling networks for their synthesis and attachment remain elusive. In this study, we systematically analyzed capsule biosynthesis and signaling networks using C. neoformans transcription factor (TF) and kinase mutant libraries under diverse capsule-inducing conditions. We found that deletion of GAT201, YAP1, BZP4, and ADA2 consistently caused capsule production defects in all tested media, indicating that they are capsule-regulating core TFs. Epistatic and expression analyses showed that Yap1 and Ada2 control Gat201 upstream, whereas Bzp4 and Gat201 independently regulate capsule production. Next, we searched for potential upstream kinases and found that mutants lacking PKA1, BUD32, POS5, IRE1, or CDC2801 showed reduced capsule production under all three capsule induction conditions, whereas mutants lacking HOG1 and IRK5 displayed enhanced capsule production. Pka1 and Irk5 controlled the induction of GAT201 and BZP4, respectively, under capsule induction conditions. Finally, we monitored the transcriptome profiles governed by Bzp4, Gat201, and Ada2 under capsule-inducing conditions and demonstrated that these TFs regulate redundant and unique sets of downstream target genes. Bzp4, Ada2, and Gat201 govern capsule formation in C. neoformans by regulating the expression of various capsule biosynthesis genes and chitin/chitosan synthesis genes in a positive and negative manner, respectively. In conclusion, this study provides further insights into the complex regulatory mechanisms of capsule production-related signaling pathways in C. neoformans. IMPORTANCE Over the past decades, human fungal pathogens, including C. neoformans, have emerged as a major public threat since the AIDS pandemic, only to gain more traction in connection to COVID-19. Polysaccharide capsules are rare fungal virulence factors that are critical for protecting C. neoformans from phagocytosis by macrophages. To date, more than 75 proteins involved in capsule synthesis and cell wall attachment have been reported in C. neoformans; however, their complex upstream signaling networks remain elusive. In this study, we demonstrated that Ada2, Yap1, Bzp4, and Gat201 were key capsule-inducing transcriptional regulators. Yap1 and Ada2 function upstream of Gat201, whereas Bzp4 and Gat201 function independently. Genome-wide transcriptome profiling revealed that Bzp4, Gat201, and Ada2 promote capsule production and attachment by positively and negatively regulating genes involved in capsule synthesis and chitin/chitosan synthesis, respectively. Thus, this study provides comprehensive insights into the complex capsule-regulating signaling pathway in C. neoformans.
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Affiliation(s)
- Eun-Ha Jang
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Ji-Seok Kim
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Seong-Ryong Yu
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Yong-Sun Bahn
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
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19
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Sato K, Kawakami K. PAMPs and Host Immune Response in Cryptococcal Infection. Med Mycol J 2022; 63:133-138. [DOI: 10.3314/mmj.22.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Ko Sato
- Department of Medical Microbiology, Mycology and Immunology, Tohoku University Graduate School of Medicine
| | - Kazuyoshi Kawakami
- Department of Medical Microbiology, Mycology and Immunology, Tohoku University Graduate School of Medicine
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20
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Reyes EY, Shinohara ML. Host immune responses in the central nervous system during fungal infections. Immunol Rev 2022; 311:50-74. [PMID: 35672656 PMCID: PMC9489659 DOI: 10.1111/imr.13101] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 04/24/2022] [Accepted: 05/18/2022] [Indexed: 12/19/2023]
Abstract
Fungal infections in the central nervous system (CNS) cause high morbidity and mortality. The frequency of CNS mycosis has increased over the last two decades as more individuals go through immunocompromised conditions for various reasons. Nevertheless, options for clinical interventions for CNS mycoses are still limited. Thus, there is an urgent need to understand the host-pathogen interaction mechanisms in CNS mycoses for developing novel treatments. Although the CNS has been regarded as an immune-privileged site, recent studies demonstrate the critical involvement of immune responses elicited by CNS-resident and CNS-infiltrated cells during fungal infections. In this review, we discuss mechanisms of fungal invasion in the CNS, fungal pathogen detection by CNS-resident cells (microglia, astrocytes, oligodendrocytes, neurons), roles of CNS-infiltrated leukocytes, and host immune responses. We consider that understanding host immune responses in the CNS is crucial for endeavors to develop treatments for CNS mycosis.
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Affiliation(s)
- Estefany Y. Reyes
- Department of Immunology, Duke University School of Medicine, Durham, NC 27705, USA
| | - Mari L. Shinohara
- Department of Immunology, Duke University School of Medicine, Durham, NC 27705, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27705, USA
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21
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Li Z, Heng H, Qin Q, Chen L, Wang Y, Zhou Z. Physicochemical properties, molecular structure, antioxidant activity, and biological function of extracellular melanin from Ascosphaera apis. J Zhejiang Univ Sci B 2022; 23:365-381. [PMID: 35557038 DOI: 10.1631/jzus.b2100718] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Ascosphaera apis spores containing a dark-colored pigment infect honeybee larvae, resulting in a large-scale collapse of the bee colony due to chalkbrood disease. However, little is known about the pigment or whether it plays a role in bee infection caused by A. apis. In this study, the pigment was isolated by alkali extraction, acid hydrolysis, and repeated precipitation. Ultraviolet (UV) analysis revealed that the pigment had a color value of 273, a maximum absorption peak at 195 nm, and a high alkaline solubility (7.67%) and acid precipitability. Further chemical structure analysis of the pigment, including elemental composition, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, mass spectrometry, and nuclear magnetic resonance (NMR), proved that it was a eumelanin with a typical indole structure. The molecular formula of melanin is C10H6O4N2, and its molecular weight is 409 Da. Melanin has hydroxyl, carboxyl, amino, and phenolic groups that can potentially chelate to metal ions. Antioxidant function analyses showed that A. apis melanin had a high scavenging activity against superoxide, hydroxyl, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, and a high reducing ability to Fe3+. Indirect immunofluorescence assay (IFA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses showed that A. apis melanin was located on the spore wall. The spore wall localization, antioxidant activity, and metal ion chelating properties of fungal melanin have been suggested to contribute to spore pathogenicity. However, further infection experiments showed that melanin-deficient spores did not reduce the mortality of bee larvae, indicating that melanin does not increase the virulence of A. apis spores. This study is the first report on melanin produced by A. apis, providing an important background reference for further study on its role in A. apis.
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Affiliation(s)
- Zhi Li
- College of Life Sciences, Chongqing Normal University, Chongqing 401331, China. .,Chongqing Key Laboratory of Vector Insects, Chongqing 401331, China. .,Chongqing Key Laboratory of Animal Biology, Chongqing 401331, China.
| | - Hui Heng
- College of Life Sciences, Chongqing Normal University, Chongqing 401331, China
| | - Qiqian Qin
- College of Life Sciences, Chongqing Normal University, Chongqing 401331, China
| | - Lanchun Chen
- College of Life Sciences, Chongqing Normal University, Chongqing 401331, China
| | - Yuedi Wang
- College of Life Sciences, Chongqing Normal University, Chongqing 401331, China
| | - Zeyang Zhou
- College of Life Sciences, Chongqing Normal University, Chongqing 401331, China.,Chongqing Key Laboratory of Microsporidia Infection and Control, Chongqing 400715, China.,The State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China
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22
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Rathore SS, Sathiyamoorthy J, Lalitha C, Ramakrishnan J. A holistic review on Cryptococcus neoformans. Microb Pathog 2022; 166:105521. [DOI: 10.1016/j.micpath.2022.105521] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 04/06/2022] [Accepted: 04/06/2022] [Indexed: 12/21/2022]
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Berguson HP, Caulfield LW, Price MS. Influence of Pathogen Carbon Metabolism on Interactions With Host Immunity. Front Cell Infect Microbiol 2022; 12:861405. [PMID: 35372116 PMCID: PMC8968422 DOI: 10.3389/fcimb.2022.861405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 02/24/2022] [Indexed: 11/22/2022] Open
Abstract
Cryptococcus neoformans is a ubiquitous opportunistic fungal pathogen typically causing disease in immunocompromised individuals and is globally responsible for about 15% of AIDS-related deaths annually. C. neoformans first causes pulmonary infection in the host and then disseminates to the brain, causing meningoencephalitis. The yeast must obtain and metabolize carbon within the host in order to survive in the central nervous system and cause disease. Communication between pathogen and host involves recognition of multiple carbon-containing compounds on the yeast surface: polysaccharide capsule, fungal cell wall, and glycosylated proteins comprising the major immune modulators. The structure and function of polysaccharide capsule has been studied for the past 70 years, emphasizing its role in virulence. While protected by the capsule, fungal cell wall has likewise been a focus of study for several decades for its role in cell integrity and host recognition. Associated with both of these major structures are glycosylated proteins, which exhibit known immunomodulatory effects. While many studies have investigated the role of carbon metabolism on virulence and survival within the host, the precise mechanism(s) affecting host-pathogen communication remain ill-defined. This review summarizes the current knowledge on mutants in carbon metabolism and their effect on the host immune response that leads to changes in pathogen recognition and virulence. Understanding these critical interactions will provide fresh perspectives on potential treatments and the natural history of cryptococcal disease.
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Affiliation(s)
- Hannah P. Berguson
- Department of Anatomical Sciences, Liberty University College of Osteopathic Medicine, Lynchburg, VA, United States
| | - Lauren W. Caulfield
- Department of Biology and Chemistry, Liberty University, Lynchburg, VA, United States
| | - Michael S. Price
- Department of Molecular and Cellular Sciences, Liberty University College of Osteopathic Medicine, Lynchburg, VA, United States
- Department of Medicine, Duke University School of Medicine, Durham, NC, United States
- *Correspondence: Michael S. Price,
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Cellular Responses Required for Oxidative Stress Tolerance of the Necrotrophic Fungus Alternaria alternata, Causal Agent of Pear Black Spot. Microorganisms 2022; 10:microorganisms10030621. [PMID: 35336198 PMCID: PMC8951605 DOI: 10.3390/microorganisms10030621] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/11/2022] [Accepted: 03/12/2022] [Indexed: 01/02/2023] Open
Abstract
To establish successful infections in host plants, pathogenic fungi must sense and respond to an array of stresses, such as oxidative stress. In this study, we systematically analyzed the effects of 30 mM H2O2 treatment on reactive oxygen species (ROS) metabolism in Alternaria alternata. Results showed that 30 mM H2O2 treatment lead to increased O2− generation rate and H2O2 content, and simultaneously, increased the activities and transcript levels of NADPH oxidase (NOX). The activities and gene expression levels of enzymes related with ascorbic acid-glutathione cycle (AsA-GSH cycle) and thioredoxin systems, including superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), ascorbate peroxidase (AXP) and thioredoxin (TrxR), were remarkably enhanced by 30 mM H2O2 stress treatment. Additionally, 30 mM H2O2 treatment decreased the glutathione (GSH) content, whereas it increased the amount of oxidized glutathione (GSSG), dehydroascorbate (DHA) and ascorbic acid (AsA). These results revealed that cellular responses are required for oxidative stress tolerance of the necrotrophic fungus A. alternata.
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Deciphering the Association among Pathogenicity, Production and Polymorphisms of Capsule/Melanin in Clinical Isolates of Cryptococcus neoformans var. grubii VNI. J Fungi (Basel) 2022; 8:jof8030245. [PMID: 35330247 PMCID: PMC8950468 DOI: 10.3390/jof8030245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/17/2022] [Accepted: 02/21/2022] [Indexed: 01/27/2023] Open
Abstract
Background: Cryptococcus neoformans is an opportunistic fungal pathogen that can cause meningitis in immunocompromised individuals. The objective of this work was to study the relationship between the phenotypes and genotypes of isolates of clinical origin from different cities in Colombia. Methods: Genome classification of 29 clinical isolates of C. neoformans var. grubii was performed using multilocus sequence typing (MLST), and genomic sequencing was used to genotype protein-coding genes. Pathogenicity was assessed in a larval model, and melanin production and capsule size were evaluated in vitro and in vivo. Results: Eleven MLST sequence types (STs) were found, the most frequent being ST69 (n = 9), ST2, ST93, and ST377 (each with n = 4). In the 29 isolates, different levels of pigmentation, capsule size and pathogenicity were observed. Isolates classified as highly pathogenic showed a tendency to exhibit larger increases in capsule size. In the analysis of polymorphisms, 48 non-synonymous variants located in the predicted functional domains of 39 genes were found to be associated with capsule size change, melanin, or pathogenicity. Conclusions: No clear patterns were found in the analysis of the phenotype and genotype of Cryptococcus. However, the data suggest that the increase in capsule size is a key variable for the differentiation of pathogenic isolates, regardless of the method used for its induction.
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Trevijano-Contador N, Roselletti E, García-Rodas R, Vecchiarelli A, Zaragoza Ó. Role of IL-17 in Morphogenesis and Dissemination of Cryptococcus neoformans during Murine Infection. Microorganisms 2022; 10:microorganisms10020373. [PMID: 35208830 PMCID: PMC8876707 DOI: 10.3390/microorganisms10020373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 01/20/2022] [Indexed: 02/04/2023] Open
Abstract
Cryptococcus neoformans is a pathogenic yeast that can form Titan cells in the lungs, which are fungal cells of abnormally large size. The factors that regulate Titan cell formation in vivo are still unknown, although an increased proportion of these fungal cells of infected mice correlates with induction of Th2-type responses. Here, we focused on the role played by the cytokine IL-17 in the formation of cryptococcal Titan cells using Il17a−/− knockout mice. We found that after 9 days of infection, there was a lower proportion of Titan cells in Il17a−/− mice compared to the fungal cells found in wild-type animals. Dissemination to the brain occurred earlier in Il17a−/− mice, which correlated with the lower proportion of Titan cells in the lungs. Furthermore, knockout-infected mice increased brain size more than WT mice. We also determined the profile of cytokines accumulated in the brain, and we found significant differences between both mouse strains. We found that in Il17a−/−, there was a modest increase in the concentrations of the Th1 cytokine TNF-α. To validate if the increase in this cytokine had any role in cryptococcal morphogenesis, we injected wild-type mice with TNF-α t and observed that fungal cell size was significantly reduced in mice treated with this cytokine. Our results suggest a compensatory production of cytokines in Il17a−/− mice that influences both cryptococcal morphology and dissemination.
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Affiliation(s)
- Nuria Trevijano-Contador
- Mycology Reference Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III, Carretera Majadahonda-Pozuelo, 28222 Madrid, Spain;
- Correspondence: (N.T.-C.); (Ó.Z.)
| | - Elena Roselletti
- Department of Experimental Medicine, Microbiology Section, University of Perugia, 06123 Perugia, Italy; (E.R.); (A.V.)
| | - Rocío García-Rodas
- Mycology Reference Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III, Carretera Majadahonda-Pozuelo, 28222 Madrid, Spain;
| | - Anna Vecchiarelli
- Department of Experimental Medicine, Microbiology Section, University of Perugia, 06123 Perugia, Italy; (E.R.); (A.V.)
| | - Óscar Zaragoza
- Mycology Reference Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III, Carretera Majadahonda-Pozuelo, 28222 Madrid, Spain;
- Correspondence: (N.T.-C.); (Ó.Z.)
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27
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Bosch C, Volschenk H, Botha A. The copper transporter, Ctr4, and the microtubule-associated protein, Cgp1, are important for Cryptococcus neoformans adaptation to nitrogen availability. FEMS Microbiol Lett 2021; 368:6402899. [PMID: 34665227 DOI: 10.1093/femsle/fnab134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/14/2021] [Indexed: 11/13/2022] Open
Abstract
Nitrogen limitation was previously shown to be an important regulator of several genes associated with virulence in Cryptococcus neoformans. Among the most highly expressed genes under low-nitrogen conditions were CTR4 and CGP1, encoding a copper transporter and a microtubule-associated protein, respectively. However, the functional association of these genes with nitrogen limitation-a nutritional stress experienced in both environment and host-remains to be determined. Moreover, whether increased CTR4 and CGP1 expression is linked to the enhanced cryptococcal drug tolerance previously observed in low-nitrogen conditions is yet to be elucidated. Therefore, the present study explored the role of Cgp1 and Ctr4 in C. neoformans nitrogen stress adaptation and antifungal susceptibility. Our results showed that these genes play a role in the growth of C. neoformans in nitrogen-limited media, nitrogen source assimilation and growth on nitrogen-poor woody debris. Furthermore, we demonstrate that both Ctr4 and Cgp1 contribute to oxidative stress and antifungal susceptibility, with a ctr4∆ mutant being more susceptible to fluconazole and a cgp1∆ mutant being more susceptible to fluconazole and amphotericin B. Overall, our findings improve our understanding of the role of Ctr4 and Cgp1 in cryptococcal drug tolerance and adaptation to nitrogen availability.
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Affiliation(s)
- Caylin Bosch
- Department of Microbiology, Stellenbosch University, Matieland, Stellenbosch 7602, South Africa
| | - Heinrich Volschenk
- Department of Microbiology, Stellenbosch University, Matieland, Stellenbosch 7602, South Africa
| | - Alfred Botha
- Department of Microbiology, Stellenbosch University, Matieland, Stellenbosch 7602, South Africa
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Capsule Promotes Intracellular Survival and Vascular Endothelial Cell Translocation during Invasive Pneumococcal Disease. mBio 2021; 12:e0251621. [PMID: 34634940 PMCID: PMC8510516 DOI: 10.1128/mbio.02516-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The polysaccharide capsule that surrounds Streptococcus pneumoniae (Spn) is one of its most important virulence determinants, serving to protect against phagocytosis. To date, 100 biochemical and antigenically distinct capsule types, i.e., serotypes, of Spn have been identified. Yet how capsule influences pneumococcal translocation across vascular endothelial cells (VEC), a key step in the progression of invasive disease, was unknown. Here, we show that despite capsule being inhibitory of Spn uptake by VEC, capsule enhances the escape rate of internalized pneumococci and thereby promotes translocation. Upon investigation, we determined that capsule protected Spn against intracellular killing by VEC and H2O2-mediated killing in vitro. Using a nitroblue tetrazolium reduction assay and nuclear magnetic resonance (NMR) analyses, purified capsule was confirmed as having antioxidant properties which varied according to serotype. Using an 11-member panel of isogenic capsule-switch mutants, we determined that serotype affected levels of Spn resistance to H2O2-mediated killing in vitro, with killing resistance correlated positively with survival duration within VEC, rate of transcytosis to the basolateral surface, and human attack rates. Experiments with mice supported our in vitro findings, with Spn producing oxidative-stress-resistant type 4 capsule being more organ-invasive than that producing oxidative-stress-sensitive type 2 capsule during bacteremia. Capsule-mediated protection against intracellular killing was also observed for Streptococcus pyogenes and Staphylococcus aureus. We conclude that capsular polysaccharide plays an important role within VEC, serving as an intracellular antioxidant, and that serotype-dependent differences in antioxidant capabilities impact the efficiency of VEC translocation and a serotype’s potential for invasive disease.
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Phenotypic Plasticity in the Productions of Virulence Factors Within and Among Serotypes in the Cryptococcus neoformans Species Complex. Mycopathologia 2021; 187:65-83. [PMID: 34697686 DOI: 10.1007/s11046-021-00597-3] [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: 01/05/2021] [Accepted: 10/12/2021] [Indexed: 10/20/2022]
Abstract
The Cryptococcus neoformans species complex (CNSC) is a common opportunistic human fungal pathogen and the most frequent cause of fungal meningitis. There are three major serotypes in CNSC: A, D, and their hybrids AD, and they have different geographic distributions and medical significance. Melanin pigment and a polysaccharide capsule are the two major virulence factors in CNSC. However, the relationships between serotype and virulence factor production and how environmental factors might impact their relationships are not known. This study investigated the expressions of melanin and capsular polysaccharide in a genetically diverse group of CNSC strains and how their phenotypic expressions were influenced by oxidative and nitrosative stress levels. We found significant differences in melanin and capsular polysaccharide productions among serotypes and across stress conditions. Under oxidative stress, the laboratory hybrids exhibited the highest phenotypic plasticity for melanin production while serotype A showed the highest for capsular polysaccharide production. In contrast, serotype D exhibited the highest phenotypic plasticity for capsular polysaccharide production and clinical serotype AD the highest phenotypic plasticity for melanin production under nitrosative stress. These results demonstrated that different serotypes have different environmental condition-specific mechanisms to modulate the expression of virulence factors.
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30
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Cell Wall Integrity Pathway Involved in Morphogenesis, Virulence and Antifungal Susceptibility in Cryptococcus neoformans. J Fungi (Basel) 2021; 7:jof7100831. [PMID: 34682253 PMCID: PMC8540506 DOI: 10.3390/jof7100831] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/28/2021] [Accepted: 09/30/2021] [Indexed: 11/17/2022] Open
Abstract
Due to its location, the fungal cell wall is the compartment that allows the interaction with the environment and/or the host, playing an important role during infection as well as in different biological functions such as cell morphology, cell permeability and protection against stress. All these processes involve the activation of signaling pathways within the cell. The cell wall integrity (CWI) pathway is the main route responsible for maintaining the functionality and proper structure of the cell wall. This pathway is highly conserved in the fungal kingdom and has been extensively characterized in Saccharomyces cerevisiae. However, there are still many unknown aspects of this pathway in the pathogenic fungi, such as Cryptococcus neoformans. This yeast is of particular interest because it is found in the environment, but can also behave as pathogen in multiple organisms, including vertebrates and invertebrates, so it has to adapt to multiple factors to survive in multiple niches. In this review, we summarize the components of the CWI pathway in C. neoformans as well as its involvement in different aspects such as virulence factors, morphological changes, and its role as target for antifungal therapies among others.
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31
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X-linked immunodeficient (XID) mice exhibit high susceptibility to Cryptococcus gattii infection. Sci Rep 2021; 11:18397. [PMID: 34526536 PMCID: PMC8443669 DOI: 10.1038/s41598-021-97041-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 08/19/2021] [Indexed: 12/12/2022] Open
Abstract
Cryptococcosis is an opportunistic disease caused by the fungus Cryptococcus neoformans and Cryptococcus gattii. It starts as a pulmonary infection that can spread to other organs, such as the brain, leading to the most serious occurrence of the disease, meningoencephalitis. The humoral response has already been described in limiting the progression of cryptococcosis where the B-1 cell seems to be responsible for producing natural IgM antibodies, crucial for combating fungal infections. The role of the B-1 cell in C. neoformans infection has been initially described, however the role of the humoral response of B-1 cells has not yet been evaluated during C. gattii infections. In the present study we tried to unravel this issue using XID mice, a murine model deficient in the Btk protein which compromises the development of B-1 lymphocytes. We use the XID mice compared to BALB/c mice that are sufficient for the B-1 population during C. gattii infection. Our model of chronic lung infection revealed that XID mice, unlike the sufficient group of B-1, had early mortality with significant weight loss, in addition to reduced levels of IgM and IgG specific to GXM isolated from the capsule of C. neoformans. In addition to this, we observed an increased fungal load in the blood and in the brain. We described an increase in the capsular size of C. gattii and the predominant presence of cytokines with a Th2 profile was also observed in these animals. Thus, the present study strongly points to a higher susceptibility of the XID mouse to C. gattii, which suggests that the presence of B-1 cells and anti-GXM antibodies is fundamental during the control of infection by C. gattii.
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32
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Merryman M, Crigler J, Seipelt-Thiemann R, McClelland E. A mutation in C. neoformans mitochondrial NADH dehydrogenase results in increased virulence in mice. Virulence 2021; 11:1366-1378. [PMID: 33103620 PMCID: PMC7588220 DOI: 10.1080/21505594.2020.1831332] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cryptococcus neoformans: (H99W) was serially passaged in the invertebrate wax moth Galleria mellonella fifteen times to study how fungal virulence evolves under selection and whether those adaptations affect virulence. The G. mellonella passaged strain (P15) and the pre-passage H99W strains were used to infect three different host models of C. neoformans: C. elegans, G. mellonella, and Balb/c mice. While there was no difference in survival in the invertebrate models, P15 killed mice faster than H99W through both intratracheal and intravenous routes of infection and mice infected intravenously with P15 showed higher fungal burden in the brain. Characterization of the major virulence factors of C. neoformans found that P15 had increased capsule size, GXM release, and melanization. Whole genome sequencing of P15 and H99W revealed two mutations in P15, an insertion in the promoter region of NADH dehydrogenase (CNAG_09000) and an insertion in the LMP1 gene (CNAG_06765). Both ATP production and metabolic rate were higher in P15 compared to H99W. Quantitative RT-PCR suggested that the increased ATP was due to increased RNA levels of NADH dehydrogenase. Thus, adaptation to growth in hemocytes resulted in increased production of ATP, increased metabolic rate, and increased virulence in mice. This was likely due to differential expression of virulence factors, which skewed the host immune response to a less efficient Th2 response, with higher levels of IL-4, IL-10, and TNF-α in the brain. Overall, serial passage experiments have increased our understanding of how this yeast evolves under innate immune selection pressure.
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Affiliation(s)
- Mitch Merryman
- Department of Biology, Middle Tennessee State University , Murfreesboro, TN, USA
| | - Jacob Crigler
- Department of Biology, Middle Tennessee State University , Murfreesboro, TN, USA
| | | | - Erin McClelland
- Department of Biology, Middle Tennessee State University , Murfreesboro, TN, USA.,M&P Associates , Murfreesboro, TN, USA
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Omar NF, Widiasih Widiyanto T, Utami ST, Niimi M, Niimi K, Toh-E A, Kajiwara S. Vph1 is associated with the copper homeostasis of Cryptococcus neoformans serotype D. J GEN APPL MICROBIOL 2021; 67:195-206. [PMID: 34219070 DOI: 10.2323/jgam.2021.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We clarified the roles of VPH1 in Cryptococcus neoformans serotype D by examining the detailed phenotypes of VPH1-deficient cells (Δvph1) in terms of their capability to grow in acidic and alkaline pH, at a high temperature, and under high osmotic conditions, in addition to the involvement of VPH1 in copper (Cu) homeostasis and the expression of some C. neoformans virulence factors. Δvph1 could grow well on minimal medium (YNB) but exhibited hypersensitivity to 20 μM Cu due to the failure to induce Cu-detoxifying metallothionein genes (CMT1 and CMT2). In contrast, Δvph1 exhibited defective growth on rich medium (YPD), and the induction of Cu transporter genes (CTR1 and CTR4) did not occur in this medium, implying that this strain was incapable of the uptake of Cu ions for growth. However, the addition of excess Cu promoted CTR gene expression and supported Δvph1 growth. These results suggested that the lack of the VPH1 gene disturbed Cu homeostasis in C. neoformans. Moreover, the loss of Vph1 function influenced the urease activity of C. neoformans.
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Affiliation(s)
- Noor Fatin Omar
- School of Life Science and Technology, Tokyo Institute of Technology
| | | | | | - Masakazu Niimi
- School of Life Science and Technology, Tokyo Institute of Technology
| | - Kyoko Niimi
- School of Life Science and Technology, Tokyo Institute of Technology
| | - Akio Toh-E
- Medical Mycology Research Center, Chiba University
| | - Susumu Kajiwara
- School of Life Science and Technology, Tokyo Institute of Technology
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34
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The Environmental Effects on Virulence Factors and the Antifungal Susceptibility of Cryptococcus neoformans. Int J Mol Sci 2021; 22:ijms22126302. [PMID: 34208294 PMCID: PMC8230809 DOI: 10.3390/ijms22126302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/09/2021] [Accepted: 06/10/2021] [Indexed: 01/10/2023] Open
Abstract
Cryptococcus neoformans is a facultative intracellular pathogen responsible for fungal meningoencephalitis primarily in immunocompromised individuals. It has become evident the pathogenicity of C. neoformans is dependent on the fungal cell’s environment. The differential expression of virulence factors, based on the cell’s environmental conditions, is one mechanism allowing for the environmental control of the pathogenic ability of C. neoformans. Here, we discuss how these virulence factors (including melanin, the polysaccharide capsule, and Antiphagocytic protein 1) have been shown to be differentially expressed dependent on the cell’s environment. The genetics and signaling pathways leading to the environmental-dependent regulation of virulence factors will also be examined. Susceptibility to antifungal therapeutics is also regulated by the environment, and thus affects the pathogenic abilities of C. neoformans and disease outcomes. This review will also examine the role of the C. neoformans’s environment on antifungal susceptibilities, and the genetics and signaling pathways responsible for these susceptibility alterations. By examining the complex interplay between the environment and the pathogenicity of C. neoformans, we have a better understanding of the intricacies of the pathogen–environment interaction and how to exploit this interaction to develop the most effective treatment protocols.
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35
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Mitochondrial Reactive Oxygen Species Enhance Alveolar Macrophage Activity against Aspergillus fumigatus but Are Dispensable for Host Protection. mSphere 2021; 6:e0026021. [PMID: 34077261 PMCID: PMC8265640 DOI: 10.1128/msphere.00260-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Aspergillus fumigatus is the most common cause of mold pneumonia worldwide, and a significant cause of infectious morbidity and mortality in immunocompromised individuals. The oxidative burst, which generates reactive oxidative species (ROS), plays a pivotal role in host defense against aspergillosis and induces regulated cell death in Aspergillus conidia, the infectious propagules. Beyond the well-established role of NADP (NADPH) oxidase in ROS generation by neutrophils and other innate effector cells, mitochondria represent a major ROS production site in many cell types, though it is unclear whether mitochondrial ROS (mtROS) contribute to antifungal activity in the lung. Following A. fumigatus infection, we observed that innate effector cells, including alveolar macrophages (AMs), monocyte-derived dendritic cells (Mo-DCS), and neutrophils, generated mtROS, primarily in fungus-infected cells. To examine the functional role of mtROS, specifically the H2O2 component, in pulmonary host defense against A. fumigatus, we infected transgenic mice that expressed a mitochondrion-targeted catalase. Using a reporter of fungal viability during interactions with leukocytes, mitochondrial H2O2 (mtH2O2) was essential for optimal AM, but not for neutrophil phagocytic and conidiacidal activity in the lung. Catalase-mediated mtH2O2 neutralization did not lead to invasive aspergillosis in otherwise immunocompetent mice and did not shorten survival in mice that lack NADPH oxidase function. Collectively, these studies indicate that mtROS-associated defects in AM antifungal activity can be functionally compensated by the action of NADPH oxidase and by nonoxidative effector mechanisms during murine A. fumigatus lung infection. IMPORTANCE Aspergillus fumigatus is a fungal pathogen that causes invasive disease in humans with defects in immune function. Airborne conidia, the infectious propagules, are ubiquitous and inhaled on a daily basis. In the respiratory tree, conidia are killed by the coordinated actions of phagocytes, including alveolar macrophages, neutrophils, and monocyte-derived dendritic cells. The oxidative burst represents a central killing mechanism and relies on the assembly of the NADPH oxidase complex on the phagosomal membrane. However, NADPH oxidase-deficient leukocytes have significant residual fungicidal activity in vivo, indicating the presence of alternative effector mechanisms. Here, we report that murine innate immune cells produce mitochondrial reactive oxygen species (mtROS) in response to fungal interactions. Neutralizing the mtROS constituent hydrogen peroxide (H2O2) via a catalase expressed in mitochondria of innate immune cells substantially diminished fungicidal properties of alveolar macrophages, but not of other innate immune cells. These data indicate that mtH2O2 represent a novel AM killing mechanism against Aspergillus conidia. mtH2O2 neutralization is compensated by other killing mechanisms in the lung, demonstrating functional redundancy at the level of host defense in the respiratory tree. These findings have important implications for the development of host-directed therapies against invasive aspergillosis in susceptible patient populations.
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36
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Johns LE, Goldman GH, Ries LN, Brown NA. Nutrient sensing and acquisition in fungi: mechanisms promoting pathogenesis in plant and human hosts. FUNGAL BIOL REV 2021. [DOI: 10.1016/j.fbr.2021.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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37
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Shchukarev A, Backman E, Watts S, Salentinig S, Urban CF, Ramstedt M. Applying Cryo-X-ray Photoelectron Spectroscopy to Study the Surface Chemical Composition of Fungi and Viruses. Front Chem 2021; 9:666853. [PMID: 34124001 PMCID: PMC8194281 DOI: 10.3389/fchem.2021.666853] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 05/14/2021] [Indexed: 11/21/2022] Open
Abstract
Interaction between microorganisms and their surroundings are generally mediated via the cell wall or cell envelope. An understanding of the overall chemical composition of these surface layers may give clues on how these interactions occur and suggest mechanisms to manipulate them. This knowledge is key, for instance, in research aiming to reduce colonization of medical devices and device-related infections from different types of microorganisms. In this context, X-ray photoelectron spectroscopy (XPS) is a powerful technique as its analysis depth below 10 nm enables studies of the outermost surface structures of microorganism. Of specific interest for the study of biological systems is cryogenic XPS (cryo-XPS). This technique allows studies of intact fast-frozen hydrated samples without the need for pre-treatment procedures that may cause the cell structure to collapse or change due to the loss of water. Previously, cryo-XPS has been applied to study bacterial and algal surfaces with respect to their composition of lipids, polysaccharides and peptide (protein and/or peptidoglycan). This contribution focuses onto two other groups of microorganisms with widely different architecture and modes of life, namely fungi and viruses. It evaluates to what extent existing models for data treatment of XPS spectra can be applied to understand the chemical composition of their very different surface layers. XPS data from model organisms as well as reference substances representing specific building blocks of their surface were collected and are presented. These results aims to guide future analysis of the surface chemical composition of biological systems.
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Affiliation(s)
| | - Emelie Backman
- Department of Clinical Microbiology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Samuel Watts
- Biointerfaces Lab, Empa, Swiss Federal Laboratories for Material Science and Technology, St. Gallen, Switzerland.,Department of Chemistry, Fribourg University, Fribourg, Switzerland
| | | | - Constantin F Urban
- Department of Clinical Microbiology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Madeleine Ramstedt
- Department of Chemistry, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
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Flotillin-Dependent Membrane Microdomains Are Required for Functional Phagolysosomes against Fungal Infections. Cell Rep 2021; 32:108017. [PMID: 32814035 PMCID: PMC10054021 DOI: 10.1016/j.celrep.2020.108017] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 04/03/2020] [Accepted: 07/17/2020] [Indexed: 11/23/2022] Open
Abstract
Lipid rafts form signaling platforms on biological membranes with incompletely characterized role in immune response to infection. Here we report that lipid-raft microdomains are essential components of phagolysosomal membranes of macrophages and depend on flotillins. Genetic deletion of flotillins demonstrates that the assembly of both major defense complexes vATPase and NADPH oxidase requires membrane microdomains. Furthermore, we describe a virulence mechanism leading to dysregulation of membrane microdomains by melanized wild-type conidia of the important human-pathogenic fungus Aspergillus fumigatus resulting in reduced phagolysosomal acidification. We show that phagolysosomes with ingested melanized conidia contain a reduced amount of free Ca2+ ions and that inhibition of Ca2+-dependent calmodulin activity led to reduced lipid-raft formation. We identify a single-nucleotide polymorphism in the human FLOT1 gene resulting in heightened susceptibility for invasive aspergillosis in hematopoietic stem cell transplant recipients. Collectively, flotillin-dependent microdomains on the phagolysosomal membrane play an essential role in protective antifungal immunity.
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Bosch C, Bhana Z, Toplis B, Volschenk H, Botha A. Transcriptomic response of Cryptococcus neoformans to ecologically relevant nitrogen concentrations. FEMS Yeast Res 2021; 21:6249451. [PMID: 33893798 DOI: 10.1093/femsyr/foab028] [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: 02/01/2021] [Accepted: 04/22/2021] [Indexed: 11/12/2022] Open
Abstract
Nitrogen availability is vital for the growth and survival of Cryptococcus neoformans in the natural environment. Two major ecological reservoirs were previously described for C. neoformans, namely, pigeon guano and the woody debris of various tree species. In contrast to the abundance of available nitrogen in guano, C. neoformans must adapt to severely limited nitrogen conditions within arboreal ecological niches. Previously, we demonstrated the role of nitrogen limitation in the production of cryptococcal virulence factors and drug tolerance. The genetic response underlying this adaptation to nitrogen deficiency, however, remains to be determined. Therefore, in the present study we investigated the transcriptomic response of C. neoformans to ecologically relevant nitrogen concentrations using RNA-sequencing. Our data revealed that low nitrogen conditions modulate the expression of numerous virulence genes in C. neoformans. Among these were, CTR4 and CGP1, which showed highly significant modulation under low nitrogen conditions. Furthermore, data analysis revealed the upregulation of antifungal tolerance-related genes in low nitrogen conditions, including genes involved in ergosterol biosynthetic processes and cell wall integrity. Overall, our findings provide insight into the survival of C. neoformans in nitrogen-poor ecological niches and suggest that pre-adaptation to these conditions may influence the pathobiology of this yeast.
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Affiliation(s)
- Caylin Bosch
- Department of Microbiology, Stellenbosch University, Van der Bijl Street, Stellenbosch, South Africa
| | - Zoë Bhana
- Department of Microbiology, Stellenbosch University, Van der Bijl Street, Stellenbosch, South Africa
| | - Barbra Toplis
- Department of Microbiology, Stellenbosch University, Van der Bijl Street, Stellenbosch, South Africa
| | - Heinrich Volschenk
- Department of Microbiology, Stellenbosch University, Van der Bijl Street, Stellenbosch, South Africa
| | - Alfred Botha
- Department of Microbiology, Stellenbosch University, Van der Bijl Street, Stellenbosch, South Africa
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40
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Balbino TR, da Silveira FA, Ventorim RZ, do Nascimento AG, de Oliveira LL, da Silveira WB. Adaptive responses of Kluyveromyces marxianus CCT 7735 to 2-phenylethanol stress: Alterations in membrane fatty-acid composition, ergosterol content, exopolysaccharide production and reduction in reactive oxygen species. Fungal Genet Biol 2021; 151:103561. [PMID: 33819626 DOI: 10.1016/j.fgb.2021.103561] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 01/06/2021] [Accepted: 03/08/2021] [Indexed: 11/27/2022]
Abstract
2-phenylethanol (2-PE) is a higher aromatic alcohol with a rose-like aroma used in the cosmetic and food industries as a flavoring and displays potential for application as an antifungal. Biotechnological production of 2-PE from yeast is an interesting alternative due to the non-use of toxic compounds and the generation of few by-products. Kluyveromyces marxianus CCT 7735 is a thermotolerant strain capable of producing high 2-PE titers from L-Phenylalanine; however, like other yeast species, its growth has been strongly inhibited by this alcohol. Herein, we aimed to evaluate the effect of 2-PE on cell growth, cell viability, membrane permeability, glucose uptake, metabolism, and morphology in K. marxianus CCT 7735, as well as its adaptive responses. The stress condition was imposed after 4 h of cultivation by adding 3.0 g.L-1 of 2-PE in exponential growing cells. 2-PE stress impaired yeast growth, glucose uptake, fermentative metabolism, membrane permeability, and cell viability. Moreover, the stress condition provoked changes in both morphology and surface roughness. The reactive oxygen species (ROS) increased immediately on exposure to 2-PE. Changes in membrane fatty-acid composition, ergosterol content, exopolysaccharides production, and reduction of the ROS levels appear to be the result of adaptive responses in K. marxianus. Our results provided insights into a better understanding of the effects of 2-PE on K. marxianus and its adaptive responses.
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Affiliation(s)
- Thércia Rocha Balbino
- Laboratory of Microbial Physiology, Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Fernando Augusto da Silveira
- Laboratory of Microbial Physiology, Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Rafaela Zandonade Ventorim
- Laboratory of Microbial Physiology, Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Antônio Galvão do Nascimento
- Laboratory of Microbial Physiology, Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Leandro Licursi de Oliveira
- Laboratory of Immunochemistry and Glycobiology, Department of General Biology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Wendel Batista da Silveira
- Laboratory of Microbial Physiology, Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG, Brazil.
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41
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Strickland AB, Shi M. Mechanisms of fungal dissemination. Cell Mol Life Sci 2021; 78:3219-3238. [PMID: 33449153 PMCID: PMC8044058 DOI: 10.1007/s00018-020-03736-z] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 11/23/2020] [Accepted: 12/08/2020] [Indexed: 12/13/2022]
Abstract
Fungal infections are an increasing threat to global public health. There are more than six million fungal species worldwide, but less than 1% are known to infect humans. Most of these fungal infections are superficial, affecting the hair, skin and nails, but some species are capable of causing life-threatening diseases. The most common of these include Cryptococcus neoformans, Aspergillus fumigatus and Candida albicans. These fungi are typically innocuous and even constitute a part of the human microbiome, but if these pathogens disseminate throughout the body, they can cause fatal infections which account for more than one million deaths worldwide each year. Thus, systemic dissemination of fungi is a critical step in the development of these deadly infections. In this review, we discuss our current understanding of how fungi disseminate from the initial infection sites to the bloodstream, how immune cells eliminate fungi from circulation and how fungi leave the blood and enter distant organs, highlighting some recent advances and offering some perspectives on future directions.
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Affiliation(s)
- Ashley B Strickland
- Division of Immunology, Virginia-Maryland College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA.
| | - Meiqing Shi
- Division of Immunology, Virginia-Maryland College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA.
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42
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Associations between Cryptococcus Genotypes, Phenotypes, and Clinical Parameters of Human Disease: A Review. J Fungi (Basel) 2021; 7:jof7040260. [PMID: 33808500 PMCID: PMC8067209 DOI: 10.3390/jof7040260] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 03/25/2021] [Accepted: 03/25/2021] [Indexed: 12/11/2022] Open
Abstract
The genus Cryptococcus contains two primary species complexes that are significant opportunistic human fungal pathogens: C. neoformans and C. gattii. In humans, cryptococcosis can manifest in many ways, but most often results in either pulmonary or central nervous system disease. Patients with cryptococcosis can display a variety of symptoms on a spectrum of severity because of the interaction between yeast and host. The bulk of our knowledge regarding Cryptococcus and the mechanisms of disease stem from in vitro experiments and in vivo animal models that make a fair attempt, but do not recapitulate the conditions inside the human host. To better understand the dynamics of initiation and progression in cryptococcal disease, it is important to study the genetic and phenotypic differences in the context of human infection to identify the human and fungal risk factors that contribute to pathogenesis and poor clinical outcomes. In this review, we summarize the current understanding of the different clinical presentations and health outcomes that are associated with pathogenicity and virulence of cryptococcal strains with respect to specific genotypes and phenotypes.
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43
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Ueno K, Otani Y, Yanagihara N, Urai M, Nagamori A, Sato-Fukushima M, Shimizu K, Saito N, Miyazaki Y. Cryptococcus gattii evades CD11b-mediated fungal recognition by coating itself with capsular polysaccharides. Eur J Immunol 2021; 51:2281-2295. [PMID: 33728652 DOI: 10.1002/eji.202049042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/25/2021] [Accepted: 03/10/2021] [Indexed: 12/15/2022]
Abstract
Cryptococcus gattii is a capsular pathogenic fungus causing life-threatening cryptococcosis. Although the capsular polysaccharides (CPs) of C. gattii are considered as virulence factors, the physiological significance of CP biosynthesis and of CPs themselves is not fully understood, with many conflicting data reported. First, we demonstrated that CAP gene deletant of C. gattii completely lacked capsule layer and its virulence, and that the strain was susceptible to host-related factors including oxidizing, hypoxic, and hypotrophic conditions in vitro. Extracellular CPs recovered from culture supernatant bound specifically to C. gattii acapsular strains, not to other fungi and immune cells, and rendered them the immune escape effects. In fact, dendritic cells (DCs) did not efficiently uptake the CP-treated acapsular strains, which possessed no visible capsule layer, and a decreased amount of phosphorylated proteins and cytokine levels after the stimulation. DCs recognized C. gattii acapuslar cells via an immune receptor CD11b- and Syk-related pathway; however, CD11b did not bind to CP-treated acapsular cells. These results suggested that CPs support immune evasion by coating antigens on C. gattii and blocking the interaction between CD11b and C. gattii cells. Here, we describe the importance of CPs in pathogenicity and immune evasion mechanisms of C. gattii.
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Affiliation(s)
- Keigo Ueno
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
| | - Yoshiko Otani
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan.,Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, Katsushika-ku, Tokyo, Japan
| | - Nao Yanagihara
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan.,Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, Katsushika-ku, Tokyo, Japan
| | - Makoto Urai
- Department of Chemistry for Life Sciences and Agriculture, Faculty of Life Sciences, Tokyo University of Agriculture, Setagaya-ku, Tokyo, Japan
| | - Akiko Nagamori
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
| | - Miyuki Sato-Fukushima
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
| | - Kiminori Shimizu
- Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, Katsushika-ku, Tokyo, Japan
| | - Noriko Saito
- Laboratory of Electron Microscopy, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
| | - Yoshitsugu Miyazaki
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
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44
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F. Q. Smith D, Casadevall A. Fungal immunity and pathogenesis in mammals versus the invertebrate model organism Galleria mellonella. Pathog Dis 2021; 79:ftab013. [PMID: 33544836 PMCID: PMC7981337 DOI: 10.1093/femspd/ftab013] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 02/03/2021] [Indexed: 02/07/2023] Open
Abstract
In recent decades, Galleria mellonella (Lepidoptera: Pyralidae) have emerged as a model system to explore experimental aspects of fungal pathogenesis. The benefits of the G. mellonella model include being faster, cheaper, higher throughput and easier compared with vertebrate models. Additionally, as invertebrates, their use is subject to fewer ethical and regulatory issues. However, for G. mellonella models to provide meaningful insight into fungal pathogenesis, the G. mellonella-fungal interactions must be comparable to mammalian-fungal interactions. Indeed, as discussed in the review, studies suggest that G. mellonella and mammalian immune systems share many similarities, and fungal virulence factors show conserved functions in both hosts. While the moth model has opened novel research areas, many comparisons are superficial and leave large gaps of knowledge that need to be addressed concerning specific mechanisms underlying G. mellonella-fungal interactions. Closing these gaps in understanding will strengthen G. mellonella as a model for fungal virulence in the upcoming years. In this review, we provide comprehensive comparisons between fungal pathogenesis in mammals and G. mellonella from immunological and virulence perspectives. When information on an antifungal immune component is unknown in G. mellonella, we include findings from other well-studied Lepidoptera. We hope that by outlining this information available in related species, we highlight areas of needed research and provide a framework for understanding G. mellonella immunity and fungal interactions.
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Affiliation(s)
- Daniel F. Q. Smith
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Arturo Casadevall
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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45
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Paccoud O, Bougnoux ME, Desnos-Ollivier M, Varet B, Lortholary O, Lanternier F. Cryptococcus gattii in Patients with Lymphoid Neoplasms: An Illustration of Evolutive Host-Fungus Interactions. J Fungi (Basel) 2021; 7:212. [PMID: 33809570 PMCID: PMC8001097 DOI: 10.3390/jof7030212] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/09/2021] [Accepted: 03/11/2021] [Indexed: 12/12/2022] Open
Abstract
Recent outbreaks of Cryptococcus gattii (CG) infections in North America have sparked renewed interest in the pathogenic potential of CG, and have underscored notable differences with Cryptococcus neoformans in terms of geographic distribution, pathogen virulence, and host susceptibility. While cases of CG are increasingly reported in patients with a wide variety of underlying conditions, only very few have been reported in patients with lymphoid neoplasms. Herein, we report a case of autochthonous CG meningitis in a patient receiving ibrutinib for chronic lymphocytic leukemia in France, and review available data on the clinical epidemiology of CG infections in patients with lymphoid neoplasms. We also summarise recent data on the host responses to CG infection, as well as the potential management pitfalls associated with its treatment in the haematological setting. The clinical epidemiology, clinical presentation, and course of disease during infections caused by CG involve complex interactions between environmental exposure to CG, infecting genotype, pathogen virulence factors, host susceptibility, and host immune responses. Future treatment guidelines should address the challenges associated with the management of antifungal treatments in the onco-haematological setting and the potential drug-drug interactions.
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Affiliation(s)
- Olivier Paccoud
- University of Paris, Necker-Pasteur Center for Infectious Diseases and Tropical Medicine, Necker-Enfants Malades University Hospital, Assistance Publique des Hôpitaux de Paris (AP-HP), 75015 Paris, France; (O.P.); (O.L.)
| | - Marie-Elisabeth Bougnoux
- University of Paris, Department of Mycology, Necker-Enfants Malades University Hospital, Assistance Publique des Hôpitaux de Paris (AP-HP), 75015 Paris, France;
| | - Marie Desnos-Ollivier
- Molecular Mycology Unit, Centre National de la Recherche Scientifique (CNRS), National Reference Center for Invasive Mycoses & Antifungals (NRCMA), Pasteur Institute, UMR2000, 75015 Paris, France;
| | - Bruno Varet
- University of Paris, Department of Hematology, Necker-Enfants Malades University Hospital, Assistance Publique des Hôpitaux de Paris (AP-HP), 75015 Paris, France;
| | - Olivier Lortholary
- University of Paris, Necker-Pasteur Center for Infectious Diseases and Tropical Medicine, Necker-Enfants Malades University Hospital, Assistance Publique des Hôpitaux de Paris (AP-HP), 75015 Paris, France; (O.P.); (O.L.)
- Molecular Mycology Unit, Centre National de la Recherche Scientifique (CNRS), National Reference Center for Invasive Mycoses & Antifungals (NRCMA), Pasteur Institute, UMR2000, 75015 Paris, France;
| | - Fanny Lanternier
- University of Paris, Necker-Pasteur Center for Infectious Diseases and Tropical Medicine, Necker-Enfants Malades University Hospital, Assistance Publique des Hôpitaux de Paris (AP-HP), 75015 Paris, France; (O.P.); (O.L.)
- Molecular Mycology Unit, Centre National de la Recherche Scientifique (CNRS), National Reference Center for Invasive Mycoses & Antifungals (NRCMA), Pasteur Institute, UMR2000, 75015 Paris, France;
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46
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The PTS Components in Klebsiella pneumoniae Affect Bacterial Capsular Polysaccharide Production and Macrophage Phagocytosis Resistance. Microorganisms 2021; 9:microorganisms9020335. [PMID: 33567595 PMCID: PMC7914778 DOI: 10.3390/microorganisms9020335] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 12/04/2022] Open
Abstract
Capsular polysaccharide (CPS) is a crucial virulence factor for Klebsiella pneumoniae infection. We demonstrated an association of CPS production with two phosphoenolpyruvate:carbohydrate phosphotransferase systems (PTSs). Deficiency of crr, encoding enzyme IIA of PTS, in K. pneumoniae enhanced the transcriptional activities of galF, wzi and gnd, which are in the cps gene cluster, leading to high CPS production. A crr mutant exhibited a higher survival rate in 1% hydrogen peroxide than the wild-type. The crr mutant showed less sensitivity to engulfment by macrophage (RAW 264.7) than the wild-type by observing the intracellular bacteria using confocal laser scanning microscopy (CLSM) and by calculating the colony-forming units (CFU) of intracellular bacteria. After long-term incubation, the survival rate of the intracellular crr mutant was higher than that of the wild-type. Deficiency of crr enhanced the transcriptional activities of etcABC which encodes another putative enzyme II complex of a PTS. Deletion of etcABC in the crr mutant reduced CPS production and the transcriptional activities of galF compared to those of the crr mutant. These results indicated that one PTS component, Crr, represses CPS production by repressing another PTS component, EtcABC, in K. pneumoniae. In addition, PTS plays a role in bacterial resistance to macrophage phagocytosis.
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47
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Wanke A, Malisic M, Wawra S, Zuccaro A. Unraveling the sugar code: the role of microbial extracellular glycans in plant-microbe interactions. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:15-35. [PMID: 32929496 PMCID: PMC7816849 DOI: 10.1093/jxb/eraa414] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 09/14/2020] [Indexed: 05/14/2023]
Abstract
To defend against microbial invaders but also to establish symbiotic programs, plants need to detect the presence of microbes through the perception of molecular signatures characteristic of a whole class of microbes. Among these molecular signatures, extracellular glycans represent a structurally complex and diverse group of biomolecules that has a pivotal role in the molecular dialog between plants and microbes. Secreted glycans and glycoconjugates such as symbiotic lipochitooligosaccharides or immunosuppressive cyclic β-glucans act as microbial messengers that prepare the ground for host colonization. On the other hand, microbial cell surface glycans are important indicators of microbial presence. They are conserved structures normally exposed and thus accessible for plant hydrolytic enzymes and cell surface receptor proteins. While the immunogenic potential of bacterial cell surface glycoconjugates such as lipopolysaccharides and peptidoglycan has been intensively studied in the past years, perception of cell surface glycans from filamentous microbes such as fungi or oomycetes is still largely unexplored. To date, only few studies have focused on the role of fungal-derived cell surface glycans other than chitin, highlighting a knowledge gap that needs to be addressed. The objective of this review is to give an overview on the biological functions and perception of microbial extracellular glycans, primarily focusing on their recognition and their contribution to plant-microbe interactions.
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Affiliation(s)
- Alan Wanke
- University of Cologne, Cluster of Excellence on Plant Sciences (CEPLAS), Institute for Plant Sciences, Cologne, Germany
- Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Milena Malisic
- University of Cologne, Cluster of Excellence on Plant Sciences (CEPLAS), Institute for Plant Sciences, Cologne, Germany
| | - Stephan Wawra
- University of Cologne, Cluster of Excellence on Plant Sciences (CEPLAS), Institute for Plant Sciences, Cologne, Germany
| | - Alga Zuccaro
- University of Cologne, Cluster of Excellence on Plant Sciences (CEPLAS), Institute for Plant Sciences, Cologne, Germany
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48
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Bian S, Zeng W, Li Q, Li Y, Wong NK, Jiang M, Zuo L, Hu Q, Li L. Genetic Structure, Function, and Evolution of Capsule Biosynthesis Loci in Vibrio parahaemolyticus. Front Microbiol 2021; 11:546150. [PMID: 33505361 PMCID: PMC7829505 DOI: 10.3389/fmicb.2020.546150] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 11/24/2020] [Indexed: 01/29/2023] Open
Abstract
Capsule-forming extracellular polysaccharides are crucial for bacterial host colonization, invasion, immune evasion, and ultimately pathogenicity. Due to warming ocean waters and human encroachment of coastal ecosystems, Vibrio parahaemolyticus has emerged as a globally important foodborne enteropathogen implicated in acute gastroenteritis, wound infections, and septic shock. Conventionally, the antigenic properties of lipopolysaccharide (LPS, O antigen) and capsular polysaccharide (CPS, K antigen) have provided a basis for serotyping V. parahaemolyticus, whereas disclosure of genetic elements encoding 13 O-serogroups have allowed molecular serotyping methods to be developed. However, the genetic structure of CPS loci for 71 K-serogroups has remained unidentified, limiting progress in understanding its roles in V. parahaemolyticus pathophysiology. In this study, we identified and characterized the genetic structure and their evolutionary relationship of CPS loci of 40 K-serogroups through whole genome sequencing of 443 V. parahaemolyticus strains. We found a distinct pattern of CPS gene cluster across different K-serogroups and expanded its new 3'-border by identifying glpX as a key gene conserved across all K-serogroups. A total of 217 genes involved in CPS biosynthesis were annotated. Functional contents and genetic structure of the 40 K-serogroups were analyzed. Based on inferences from species trees and gene trees, we proposed an evolution model of the CPS gene clusters of 40 K-serogroups. Horizontal gene transfer by recombination from other Vibrio species, gene duplication is likely to play instrumental roles in the evolution of CPS in V. parahaemolyticus. This is the first time, to the best of our knowledge, that a large scale of CPS gene clusters of different K-serogroups in V. parahaemolyticus have been identified and characterized in evolutionary contexts. This work should help advance understanding on the variation of CPS in V. parahaemolyticus and provide a framework for developing diagnostically relevant serotyping methods.
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Affiliation(s)
- Shengzhe Bian
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China
- BGI-Shenzhen, Shenzhen, China
- Shenzhen Key Laboratory of Unknown Pathogen Identification, Shenzhen, China
- School of Public Health (Shenzhen), Sun Yat-sen University, Guangzhou, China
| | - Wenhong Zeng
- Jiangxi University of Traditional Chinese Medicine, Nanchang, China
| | - Qiwen Li
- BGI-Shenzhen, Shenzhen, China
- Shenzhen Key Laboratory of Unknown Pathogen Identification, Shenzhen, China
| | - Yinghui Li
- Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Nai-Kei Wong
- National Clinical Research Center for Infectious Diseases, Shenzhen Third People’s Hospital, The Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen, China
| | - Min Jiang
- Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Le Zuo
- Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Qinghua Hu
- Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Liqiang Li
- BGI-Shenzhen, Shenzhen, China
- Shenzhen Key Laboratory of Unknown Pathogen Identification, Shenzhen, China
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49
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Pereira TC, de Menezes RT, de Oliveira HC, de Oliveira LD, Scorzoni L. In vitro synergistic effects of fluoxetine and paroxetine in combination with amphotericin B against Cryptococcus neoformans. Pathog Dis 2021; 79:6070654. [PMID: 33417701 DOI: 10.1093/femspd/ftab001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 01/05/2021] [Indexed: 12/16/2022] Open
Abstract
Cryptococcus neoformans is a yeast that mainly affects immunocompromised individuals and causes meningoencephalitis depending on the immune status of the host. The present study aimed to validate the efficacy of selective serotonin reuptake inhibitors, fluoxetine hydrochloride (FLH) and paroxetine hydrochloride (PAH), alone and in combination with amphotericin B (AmB) against C. neoformans. Susceptibility tests were conducted using the broth microdilution method and synergistic effects of combining FLH and PAH with AmB were analyzed using the checkerboard assay. Effects of minimum inhibitory concentration (MIC) and synergistic concentration were evaluated in biofilms by quantifying the biomass, measuring the viability by counting the colony-forming units (CFU/mL) and examining the size of the induced capsules. Cryptococcus neoformans was susceptible to FLH and PAH and the synergistic effect of FLH and PAH in combination with AmB reduced the MIC of AmB by up to 8-fold. The isolated substances and combination with AmB were able to reduce biofilm biomass and biofilm viability. In addition, FLH and PAH alone or in combination with AmB significantly decreased the size of the yeast capsules. Collectively, our results indicate the use of FLH and PAH as a promising prototype for the development of anti-cryptococcal drugs.
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Affiliation(s)
- Thaís Cristine Pereira
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), Av. Engenheiro Francisco José Longo, 777 São José dos Campos, São Paulo 12245-000, Brazil
| | - Raquel Teles de Menezes
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), Av. Engenheiro Francisco José Longo, 777 São José dos Campos, São Paulo 12245-000, Brazil
| | - Haroldo Cesar de Oliveira
- Instituto Carlos Chagas, Fundação Oswaldo Cruz (Fiocruz), Rua Prof. Algacyr Munhoz Mader, 3775 Curitiba, PR 81350-010, Brazil
| | - Luciane Dias de Oliveira
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), Av. Engenheiro Francisco José Longo, 777 São José dos Campos, São Paulo 12245-000, Brazil
| | - Liliana Scorzoni
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), Av. Engenheiro Francisco José Longo, 777 São José dos Campos, São Paulo 12245-000, Brazil
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Roth C, Murray D, Scott A, Fu C, Averette AF, Sun S, Heitman J, Magwene PM. Pleiotropy and epistasis within and between signaling pathways defines the genetic architecture of fungal virulence. PLoS Genet 2021; 17:e1009313. [PMID: 33493169 PMCID: PMC7861560 DOI: 10.1371/journal.pgen.1009313] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 02/04/2021] [Accepted: 12/17/2020] [Indexed: 01/11/2023] Open
Abstract
Cryptococcal disease is estimated to affect nearly a quarter of a million people annually. Environmental isolates of Cryptococcus deneoformans, which make up 15 to 30% of clinical infections in temperate climates such as Europe, vary in their pathogenicity, ranging from benign to hyper-virulent. Key traits that contribute to virulence, such as the production of the pigment melanin, an extracellular polysaccharide capsule, and the ability to grow at human body temperature have been identified, yet little is known about the genetic basis of variation in such traits. Here we investigate the genetic basis of melanization, capsule size, thermal tolerance, oxidative stress resistance, and antifungal drug sensitivity using quantitative trait locus (QTL) mapping in progeny derived from a cross between two divergent C. deneoformans strains. Using a "function-valued" QTL analysis framework that exploits both time-series information and growth differences across multiple environments, we identified QTL for each of these virulence traits and drug susceptibility. For three QTL we identified the underlying genes and nucleotide differences that govern variation in virulence traits. One of these genes, RIC8, which encodes a regulator of cAMP-PKA signaling, contributes to variation in four virulence traits: melanization, capsule size, thermal tolerance, and resistance to oxidative stress. Two major effect QTL for amphotericin B resistance map to the genes SSK1 and SSK2, which encode key components of the HOG pathway, a fungal-specific signal transduction network that orchestrates cellular responses to osmotic and other stresses. We also discovered complex epistatic interactions within and between genes in the HOG and cAMP-PKA pathways that regulate antifungal drug resistance and resistance to oxidative stress. Our findings advance the understanding of virulence traits among diverse lineages of Cryptococcus, and highlight the role of genetic variation in key stress-responsive signaling pathways as a major contributor to phenotypic variation.
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Affiliation(s)
- Cullen Roth
- Department of Biology, Duke University, Durham, North Carolina, United States of America
- University Program in Genetics and Genomics, Duke University, Durham, North Carolina, United States of America
| | - Debra Murray
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Alexandria Scott
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Ci Fu
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Anna F. Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Paul M. Magwene
- Department of Biology, Duke University, Durham, North Carolina, United States of America
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