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Pruksaphon K, Amsri A, Thammasit P, Nosanchuk JD, Aiumurai P, Youngchim S. Diagnostic Performances of an in-House Immunochromatography Test Based on the Monoclonal Antibody 18B7 to Glucuronoxylomannan for Clinical Suspected Cryptococcosis: a Large-Scale Prototype Evaluation in Northern Thailand. Mycopathologia 2024; 189:75. [PMID: 39120647 DOI: 10.1007/s11046-024-00882-x] [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: 02/03/2024] [Accepted: 07/30/2024] [Indexed: 08/10/2024]
Abstract
OBJECTIVE Cryptococcosis predominantly presents as a meningoencephalitis in Thailand. Early and expeditious diagnosis is essential for reducing both mortality and morbidity associated with cryptococcal meningitis. We aim to define and establish the diagnostic performances between the benchmark commercially available diagnostic kit (CrAg® LFA) and the large-scale prototype of an inexpensive in-house immunochromatographic test (ICT) based on monoclonal antibody (MAb) 18B7. METHODS We have developed the large-scale prototype for the rapid detection of cryptococcal polysaccharide antigens by utilizing a single antibody sandwich ICT format employing MAb 18B7, which is highly specific to Cryptococcus neoformans glucuronoxylomannan (GXM) antigens. An in-house MAb18B7 ICT was manufactured in accordance with industry standards under the control of the International Organization for Standardization (ISO) 13485. RESULTS The diagnostic sensitivity, specificity, and accuracy for the in-house MAb 18B7 ICT were 99.10%, 97.61%, and 97.83%, respectively. The agreement kappa (κ) coefficient was 0.968 based on the retrospective evaluation of 580 specimens from patients living in northern Thailand with clinically suspected cryptococcosis. CONCLUSION The data suggest that this in-house MAb 18B7 ICT will be highly beneficial for addressing the issue of cryptococcal infection in Thailand. Moreover, it is anticipated that this inexpensive ICT can play a pivotal role in various global strategies aimed at eradicating cryptococcal meningitis among individuals living with HIV by 2030.
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Affiliation(s)
- Kritsada Pruksaphon
- Department of Medical Technology, School of Allied Health Sciences, Walailak University, Nakhon Si Thammarat, 80160, Thailand
- Center of Excellence Research for Melioidosis and Microorganisms (CERMM), Walailak University, Nakhon Si Thammarat, 80160, Thailand
| | - Artid Amsri
- Office of Research Administration, Chiang Mai University, Chiang Mai, 50200, Thailand
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Patcharin Thammasit
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Joshua D Nosanchuk
- Department of Medicine (Division of Infectious Diseases), Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Pisinee Aiumurai
- Center of Research Excellence in Allergy and Immunology, Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Sirida Youngchim
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
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2
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Baker RP, Liu AZ, Casadevall A. Cell wall melanin impedes growth of the Cryptococcus neoformans polysaccharide capsule by sequestering calcium. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.20.599928. [PMID: 38948764 PMCID: PMC11212976 DOI: 10.1101/2024.06.20.599928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Cryptococcus neoformans has emerged as a frontrunner among deadly fungal pathogens and is particularly life-threatening for many HIV-infected individuals with compromised immunity. Multiple virulence factors contribute to the growth and survival of C. neoformans within the human host, the two most prominent of which are the polysaccharide capsule and melanin. As both of these features are associated with the cell wall, we were interested to explore possible cooperative or competitive interactions between these two virulence factors. Whereas capsule thickness had no effect on the rate at which cells became melanized, build-up of the melanin pigment layer resulted in a concomitant loss of polysaccharide material, leaving melanized cells with significantly thinner capsules than their non-melanized counterparts. When melanin was provided exogenously to cells in a transwell culture system we observed a similar inhibition of capsule growth and maintenance. Our results show that melanin sequesters calcium thereby limiting its availability to form divalent bridges between polysaccharide subunits required for outer capsule assembly. The decreased ability of melanized cells to incorporate exported polysaccharide into the growing capsule correlated with the amount of shed polysaccharide, which could have profound negative impacts on the host immune response. Significance Statement Cryptococcus neoformans is an opportunistic fungal pathogen that presents a significant health risk for immunocompromised individuals. We report an interaction between the two major cryptococcal virulence factors, the polysaccharide capsule and melanin. Melanin impacted the growth and maintenance of the polysaccharide capsule, resulting in loss of capsular material during melanization. Our results suggest that melanin can act as a sink for calcium, thereby limiting its availability to form ionic bridges between polysaccharide chains on the growing surface of the outer capsule. As polysaccharide is continuously exported to support capsule growth, failure of melanized cells to incorporate this material results in a higher concentration of shed polysaccharide in the extracellular milieu, which is expected to interfere with host immunity.
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3
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Crawford C, Liporagi-Lopes L, Coelho C, Santos Junior SR, Moraes Nicola A, Wear MP, Vij R, Oscarson S, Casadevall A. Semisynthetic Glycoconjugate Vaccine Candidates against Cryptococcus neoformans. ACS Infect Dis 2024; 10:2089-2100. [PMID: 38819951 PMCID: PMC11184550 DOI: 10.1021/acsinfecdis.4c00094] [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: 02/03/2024] [Revised: 05/07/2024] [Accepted: 05/21/2024] [Indexed: 06/02/2024]
Abstract
Cryptococcus neoformans is a fungus classified by the World Health Organization as a critically important pathogen, which poses a significant threat to immunocompromised individuals. In this study, we present the chemical synthesis and evaluation of two semisynthetic vaccine candidates targeting the capsular polysaccharide glucuronoxylomannan (GXM) of C. neoformans. These semisynthetic glycoconjugate vaccines contain an identical synthetic decasaccharide (M2 motif) antigen. This antigen is present in serotype A strains, which constitute 95% of the clinical cryptococcosis cases. This synthetic oligosaccharide was conjugated to two proteins (CRM197 and Anthrax 63 kDa PA) and tested for immunogenicity in mice. The conjugates elicited a specific antibody response that bound to the M2 motif but also exhibited additional cross-reactivity toward M1 and M4 GXM motifs. Both glycoconjugates produced antibodies that bound to GXM in ELISA assays and to live fungal cells. Mice immunized with the CRM197 glycoconjugate produced weakly opsonic antibodies and displayed trends toward increased median survival relative to mice given a mock PBS injection (18 vs 15 days, p = 0.06). These findings indicate promise, achieving a successful vaccine demands further optimization of the glycoconjugate. This antigen could serve as a component in a multivalent GXM motif vaccine.
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Affiliation(s)
- Conor
J. Crawford
- Centre
for Synthesis and Chemical Biology, University
College Dublin, Belfield, Dublin D04 V1W8, Ireland
- Department
of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore 21205, Maryland, United States
| | - Livia Liporagi-Lopes
- Department
of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore 21205, Maryland, United States
| | - Carolina Coelho
- Department
of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore 21205, Maryland, United States
| | - Samuel R. Santos Junior
- Department
of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore 21205, Maryland, United States
| | - André Moraes Nicola
- Department
of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore 21205, Maryland, United States
| | - Maggie P. Wear
- Department
of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore 21205, Maryland, United States
| | - Raghav Vij
- Department
of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore 21205, Maryland, United States
| | - Stefan Oscarson
- Centre
for Synthesis and Chemical Biology, University
College Dublin, Belfield, Dublin D04 V1W8, Ireland
| | - Arturo Casadevall
- Department
of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore 21205, Maryland, United States
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4
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Jimenez IA, Stempinski PR, Dragotakes Q, Greengo SD, Ramirez LS, Casadevall A. The buoyancy of cryptococcal cells and its implications for transport and persistence of Cryptococcus in aqueous environments. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.20.595024. [PMID: 38826196 PMCID: PMC11142132 DOI: 10.1101/2024.05.20.595024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Cryptococcus is a genus of saprophytic fungi with global distribution. Two species complexes, C. neoformans and C. gattii, pose health risks to humans and animals. Cryptococcal infections result from inhalation of aerosolized spores and/or desiccated yeasts from terrestrial reservoirs such as soil, trees, and avian guano. More recently, C. gattii has been implicated in infections in marine mammals, suggesting that inhalation of liquid droplets or aerosols from the air-water interface is also an important, yet understudied, mode of respiratory exposure. Water transport has also been suggested to play a role in the spread of C. gattii from tropical to temperate environments. However, the dynamics of fungal survival, persistence, and transport via water have not been fully studied. The size of the cryptococcal capsule was previously shown to reduce cell density and increase buoyancy. Here, we demonstrate that cell buoyancy is also impacted by the salinity of the media in which cells are suspended, with formation of a halocline interface significantly slowing the rate of settling of cryptococcal cells through water, resulting in persistence of C. neoformans within 1 cm of the air-water interface for over 60 min and C. gattii for 4-6 h. Our data also showed that during culture in yeast peptone dextrose media (YPD), polysaccharide accumulating in the supernatant formed a raft that augmented buoyancy and further slowed settling of cryptococcal cells. These findings illustrate new mechanisms by which cryptococcal cells may persist in aquatic environments, with important implications for aqueous transport and pathogen exposure.
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Affiliation(s)
- Isabel A. Jimenez
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Piotr R. Stempinski
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Quigly Dragotakes
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Seth D. Greengo
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Lia Sanchez Ramirez
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
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5
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Hargett AA, Azurmendi HF, Crawford CJ, Wear MP, Oscarson S, Casadevall A, Freedberg DI. The structure of a C. neoformans polysaccharide motif recognized by protective antibodies: A combined NMR and MD study. Proc Natl Acad Sci U S A 2024; 121:e2315733121. [PMID: 38330012 PMCID: PMC10873606 DOI: 10.1073/pnas.2315733121] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 12/02/2023] [Indexed: 02/10/2024] Open
Abstract
Cryptococcus neoformans is a fungal pathogen responsible for cryptococcosis and cryptococcal meningitis. The C. neoformans' capsular polysaccharide and its shed exopolysaccharide function both as key virulence factors and to protect the fungal cell from phagocytosis. Currently, a glycoconjugate of these polysaccharides is being explored as a vaccine to protect against C. neoformans infection. In this study, NOE and J-coupling values from NMR experiments were consistent with a converged structure of the synthetic decasaccharide, GXM10-Ac3, calculated from MD simulations. GXM10-Ac3 was designed as an extension of glucuronoxylomannan (GXM) polysaccharide motif (M2) which is common in the clinically predominant serotype A strains and is recognized by protective forms of GXM-specific monoclonal antibodies. The M2 motif is a hexasaccharide with a three-residue α-mannan backbone, modified by β-(1→2)-xyloses (Xyl) on the first two mannoses (Man) and a β-(1→2)-glucuronic acid (GlcA) on the third Man. Combined NMR and MD analyses reveal that GXM10-Ac3 adopts an extended structure, with Xyl/GlcA branches alternating sides along the α-mannan backbone. O-acetyl esters also alternate sides and are grouped in pairs. MD analysis of a twelve M2-repeating unit polymer supports the notion that the GXM10-Ac3 structure is uniformly represented throughout the polysaccharide. This derived GXM model displays high flexibility while maintaining a structural identity, yielding insights to further explore intermolecular interactions between polysaccharides, interactions with anti-GXM mAbs, and the cryptococcal polysaccharide architecture.
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Affiliation(s)
- Audra A. Hargett
- Laboratory of Bacterial Polysaccharides, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993
| | - Hugo F. Azurmendi
- Laboratory of Bacterial Polysaccharides, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993
| | - Conor J. Crawford
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD21205
- Centre for Synthesis and Chemical Biology, University College Dublin, Dublin 4, Ireland
| | - Maggie P. Wear
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD21205
| | - Stefan Oscarson
- Centre for Synthesis and Chemical Biology, University College Dublin, Dublin 4, Ireland
| | - Arturo Casadevall
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD21205
| | - Darón I. Freedberg
- Laboratory of Bacterial Polysaccharides, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993
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6
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Wang Z, Teixeira SCM, Strother C, Bowen A, Casadevall A, Cordero RJB. Neutron Scattering Analysis of Cryptococcus neoformans Polysaccharide Reveals Solution Rigidity and Repeating Fractal-like Structural Patterns. Biomacromolecules 2024; 25:690-699. [PMID: 38157431 PMCID: PMC10922810 DOI: 10.1021/acs.biomac.3c00911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Cryptococcus neoformans is a fungal pathogen that can cause life-threatening brain infections in immunocompromised individuals. Unlike other fungal pathogens, it possesses a protective polysaccharide capsule that is crucial for its virulence. During infections, Cryptococcus cells release copious amounts of extracellular polysaccharides (exo-PS) that interfere with host immune responses. Both exo-PS and capsular-PS play pivotal roles in Cryptococcus infections and serve as essential targets for disease diagnosis and vaccine development strategies. However, understanding their structure is complicated by their polydispersity, complexity, sensitivity to sample isolation and processing, and scarcity of methods capable of isolating and analyzing them while preserving their native structure. In this study, we employ small-angle neutron scattering (SANS) and ultra-small-angle neutron scattering (USANS) for the first time to investigate both fungal cell suspensions and extracellular polysaccharides in solution. Our data suggests that exo-PS in solution exhibits collapsed chain-like behavior and demonstrates mass fractal properties that indicate a relatively condensed pore structure in aqueous environments. This observation is also supported by scanning electron microscopy (SEM). The local structure of the polysaccharide is characterized as a rigid rod, with a length scale corresponding to 3-4 repeating units. This research not only unveils insights into exo-PS and capsular-PS structures but also demonstrates the potential of USANS for studying changes in cell dimensions and the promise of contrast variation in future neutron scattering studies.
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Affiliation(s)
- Ziwei Wang
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, 21205, USA
| | - Susana C. M. Teixeira
- NIST Center of Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899, USA
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware, 19716, USA
| | - Camilla Strother
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, 21205, USA
| | - Anthony Bowen
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, 21205, USA
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, 21205, USA
| | - Radamés JB Cordero
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, 21205, USA
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7
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Crawford CJ, Liporagi-Lopes L, Coelho C, Santos SR, Nicola AM, Wear MP, Vij R, Oscarson S, Casadevall A. Semi-synthetic glycoconjugate vaccine candidate against Cryptococcus neoformans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.02.578725. [PMID: 38352552 PMCID: PMC10862886 DOI: 10.1101/2024.02.02.578725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
Cryptococcus neoformans is a fungus classified by the World Health Organization as a critically important pathogen, posing a significant threat to immunocompromised individuals. In this study, we present the chemical synthesis and evaluation of two semi-synthetic vaccine candidates targeting the capsular polysaccharide glucuronoxylomannan (GXM) of C. neoformans. These semi-synthetic glycoconjugate vaccines contain the identical synthetic decasaccharide (M2 motif) antigen. This motif is present in serotype A strains, which constitute 95% of clinical cryptococcosis cases. This synthetic oligosaccharide was conjugated to two proteins (CRM197 and Anthrax 63 kDa PA) and tested for immunogenicity in mice. The conjugates elicited a specific antibody response that bound to the M2 motif but also exhibited additional cross-reactivity towards M1 and M4 GXM motifs. Both glycoconjugates produced antibodies that bound to GXM in ELISA assays and to live fungal cells. Mice immunized with the CRM197 glycoconjugate produced opsonic antibodies and displayed trends toward increased median survival relative to mice given a mock PBS injection (18 vs 15 days, p = 0.06). While these findings indicate promise, achieving a successful vaccine demands further optimization of the glycoconjugate. It could serve as a component in a multi-valent GXM motif vaccine, enhancing both strength and breadth of immune responses.
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Affiliation(s)
- Conor J Crawford
- Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin, Ireland
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health 615 North Wolfe Street, Baltimore, MD 21205, USA
- Present Address: Max Planck Institute of Colloids and Interfaces, Am Mühlenberg1, 14476 Potsdam, Germany
| | - Livia Liporagi-Lopes
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health 615 North Wolfe Street, Baltimore, MD 21205, USA
- Present Address: Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Carolina Coelho
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health 615 North Wolfe Street, Baltimore, MD 21205, USA
- Present Address: MRC Centre for Medical Mycology, University of Exeter, Exeter Devon UK
| | - Samuel R Santos
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health 615 North Wolfe Street, Baltimore, MD 21205, USA
| | - André Moraes Nicola
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health 615 North Wolfe Street, Baltimore, MD 21205, USA
- Present Address: Faculty of Medicine, University of Brasília, Brasília, Brazil
| | - Maggie P Wear
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health 615 North Wolfe Street, Baltimore, MD 21205, USA
| | - Raghav Vij
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health 615 North Wolfe Street, Baltimore, MD 21205, USA
- Present address: Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany
| | - Stefan Oscarson
- Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin, Ireland
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health 615 North Wolfe Street, Baltimore, MD 21205, USA
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8
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Jozefowicz LJ, Rodrigues ML. Preparation of Biologically Active Fractions Enriched with Glucuronoxylomannan, the Main Antigen of the Cryptococcal Capsule. Methods Mol Biol 2024; 2775:367-373. [PMID: 38758330 DOI: 10.1007/978-1-0716-3722-7_24] [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] [Indexed: 05/18/2024]
Abstract
Glucuronoxylomannan (GXM) is the principal capsular component in the Cryptococcus genus. This complex polysaccharide participates in numerous events related to the physiology and pathogenesis of Cryptococcus, which highlights the importance of establishing methods for its isolation and analysis. Conventional methods for GXM isolation have been extensively discussed in the literature. In this chapter, we describe two fast methods for obtaining extracellular fractions enriched with cryptococcal GXM.
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Affiliation(s)
- Luisa J Jozefowicz
- Instituto Carlos Chagas, Fundação Oswaldo Cruz (Fiocruz), Curitiba, Brazil
| | - Marcio L Rodrigues
- Instituto Carlos Chagas, Fundação Oswaldo Cruz (Fiocruz), Curitiba, Brazil.
- Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
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9
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Wang Z, Teixeira SCM, Strother C, Bowen A, Casadevall A, Cordero RJB. Neutron Scattering Analysis of Cryptococcus neoformans Polysaccharide Reveals Solution Rigidity and Repeating Fractal-like Structural Patterns. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.22.559017. [PMID: 37790378 PMCID: PMC10542156 DOI: 10.1101/2023.09.22.559017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Cryptococcus neoformans is a fungal pathogen that can cause life-threatening brain infections in immunocompromised individuals. Unlike other fungal pathogens, it possesses a protective polysaccharide capsule that is crucial for its virulence. During infections, Cryptococcus cells release copious amounts of extracellular polysaccharides (exo-PS) that interfere with host immune responses. Both exo-PS and capsular-PS play pivotal roles in Cryptococcus infections and serve as essential targets for disease diagnosis and vaccine development strategies. However, understanding their structure is complicated by their polydispersity, complexity, sensitivity to sample isolation and processing, and scarcity of methods capable of isolating and analyzing them while preserving their native structure. In this study, we employ small-angle neutron scattering (SANS) and ultra-small angle neutron scattering (USANS) for the first time to investigate both fungal cell suspensions and extracellular polysaccharides in solution. Our data suggests that exo-PS in solution exhibits collapsed chain-like behavior and demonstrates mass fractal properties that indicate a relatively condensed pore structure in aqueous environments. This observation is also supported by scanning electron microscopy (SEM). The local structure of the polysaccharide is characterized as a rigid rod, with a length-scale corresponding to 3 to 4 repeating units. This research not only unveils insights into exo-PS and capsular-PS structures but also demonstrates the potential of USANS for studying changes in cell dimensions and the promise of contrast variation in future neutron scattering studies.
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Affiliation(s)
- Ziwei Wang
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, 21205, USA
| | - Susana C. M. Teixeira
- NIST Center of Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899, USA
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware, 19716, USA
| | - Camilla Strother
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, 21205, USA
| | - Anthony Bowen
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, 21205, USA
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, 21205, USA
| | - Radamés JB Cordero
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, 21205, USA
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10
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Hargett AA, Azurmendi HF, Crawford CJ, Wear MP, Oscarson S, Casadevall A, Freedberg DI. The structure of a C. neoformans polysaccharide motif recognized by protective antibodies: A combined NMR and MD study. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.06.556507. [PMID: 37732210 PMCID: PMC10508755 DOI: 10.1101/2023.09.06.556507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
Cryptococcus neoformans is a fungal pathogen responsible for cryptococcosis and cryptococcal meningitis. The C. neoformans capsular polysaccharide and shed exopolysaccharide functions both as a key virulence factor and to protect the fungal cell from phagocytosis. Currently, a glycoconjugate of these polysaccharides is being explored as a vaccine to protect against C. neoformans infection. In this combined NMR and MD study, experimentally determined NOEs and J-couplings support a structure of the synthetic decasaccharide, GXM10-Ac3, obtained by MD. GXM10-Ac3 was designed as an extension of glucuronoxylomannan (GXM) polysaccharide motif (M2) which is common in the clinically predominant serotype A strains and is recognized by protective forms of GXM-specific monoclonal antibodies. The M2 motif is characterized by a 6-residue α-mannan backbone repeating unit, consisting of a triad of α-(1→3)-mannoses, modified by β-(1→2)-xyloses on the first two mannoses and a β-(1→2)-glucuronic acid on the third mannose. The combined NMR and MD analyses reveal that GXM10-Ac3 adopts an extended structure, with xylose/glucuronic acid branches alternating sides along the α-mannan backbone. O-acetyl esters also alternate sides and are grouped in pairs. MD analysis of a twelve M2-repeating unit polymer supports the notion that the GXM10-Ac3 structure is uniformly represented throughout the polysaccharide. This experimentally consistent GXM model displays high flexibility while maintaining a structural identity, yielding new insights to further explore intermolecular interactions between polysaccharides, interactions with anti-GXM mAbs, and the cryptococcal polysaccharide architecture.
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Affiliation(s)
- Audra A. Hargett
- Laboratory of Bacterial Polysaccharides, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Hugo F. Azurmendi
- Laboratory of Bacterial Polysaccharides, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Conor J. Crawford
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
- Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
- Current address: Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Maggie P. Wear
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Stefan Oscarson
- Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Arturo Casadevall
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Darόn I. Freedberg
- Laboratory of Bacterial Polysaccharides, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
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Lee HH, Carmichael DJ, Ríbeiro V, Parisi DN, Munzen ME, Charles-Niño CL, Hamed MF, Kaur E, Mishra A, Patel J, Rooklin RB, Sher A, Carrillo-Sepulveda MA, Eugenin EA, Dores MR, Martinez LR. Glucuronoxylomannan intranasal challenge prior to Cryptococcus neoformans pulmonary infection enhances cerebral cryptococcosis in rodents. PLoS Pathog 2023; 19:e1010941. [PMID: 37115795 PMCID: PMC10171644 DOI: 10.1371/journal.ppat.1010941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 05/10/2023] [Accepted: 04/17/2023] [Indexed: 04/29/2023] Open
Abstract
The encapsulated fungus Cryptococcus neoformans is the most common cause of fungal meningitis, with the highest rate of disease in patients with AIDS or immunosuppression. This microbe enters the human body via inhalation of infectious particles. C. neoformans capsular polysaccharide, in which the major component is glucuronoxylomannan (GXM), extensively accumulates in tissues and compromises host immune responses. C. neoformans travels from the lungs to the bloodstream and crosses to the brain via transcytosis, paracytosis, or inside of phagocytes using a "Trojan horse" mechanism. The fungus causes life-threatening meningoencephalitis with high mortality rates. Hence, we investigated the impact of intranasal exogenous GXM administration on C. neoformans infection in C57BL/6 mice. GXM enhances cryptococcal pulmonary infection and facilitates fungal systemic dissemination and brain invasion. Pre-challenge of GXM results in detection of the polysaccharide in lungs, serum, and surprisingly brain, the latter likely reached through the nasal cavity. GXM significantly alters endothelial cell tight junction protein expression in vivo, suggesting significant implications for the C. neoformans mechanisms of brain invasion. Using a microtiter transwell system, we showed that GXM disrupts the trans-endothelial electrical resistance, weakening human brain endothelial cell monolayers co-cultured with pericytes, supportive cells of blood vessels/capillaries found in the blood-brain barrier (BBB) to promote C. neoformans BBB penetration. Our findings should be considered in the development of therapeutics to combat the devastating complications of cryptococcosis that results in an estimated ~200,000 deaths worldwide each year.
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Affiliation(s)
- Hiu Ham Lee
- Department of Biomedical Sciences, NYIT College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, New York, United States of America
| | - Dylan J Carmichael
- Department of Biomedical Sciences, NYIT College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, New York, United States of America
| | - Victoria Ríbeiro
- Department of Neuroscience, Cell Biology, and Anatomy, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Dana N Parisi
- Department of Biomedical Sciences, NYIT College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, New York, United States of America
- Department of Biomedical Sciences, Long Island University-Post, Brookville, New York, United States of America
| | - Melissa E Munzen
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, United States of America
| | - Claudia L Charles-Niño
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, United States of America
| | - Mohamed F Hamed
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, United States of America
- Department of Pathology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Ettiman Kaur
- Department of Biology, Hofstra University, Hempstead, New York, United States of America
| | - Ayush Mishra
- Department of Biology, Hofstra University, Hempstead, New York, United States of America
| | - Jiya Patel
- Department of Biology, Hofstra University, Hempstead, New York, United States of America
| | - Rikki B Rooklin
- Department of Biology, Hofstra University, Hempstead, New York, United States of America
| | - Amina Sher
- Department of Biology, Hofstra University, Hempstead, New York, United States of America
| | - Maria A Carrillo-Sepulveda
- Department of Biomedical Sciences, NYIT College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, New York, United States of America
| | - Eliseo A Eugenin
- Department of Neuroscience, Cell Biology, and Anatomy, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Michael R Dores
- Department of Biology, Hofstra University, Hempstead, New York, United States of America
| | - Luis R Martinez
- Department of Biomedical Sciences, NYIT College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, New York, United States of America
- Department of Biomedical Sciences, Long Island University-Post, Brookville, New York, United States of America
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- Center for Immunology and Transplantation, University of Florida, Gainesville, Florida, United States of America
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, United States of America
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12
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de Andrade IB, Corrêa-Junior D, Alves V, Figueiredo-Carvalho MHG, Santos MV, Almeida MA, Valdez AF, Nimrichter L, Almeida-Paes R, Frases S. Cyclosporine Affects the Main Virulence Factors of Cryptococcus neoformans In Vitro. J Fungi (Basel) 2023; 9:jof9040487. [PMID: 37108941 PMCID: PMC10140927 DOI: 10.3390/jof9040487] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 04/13/2023] [Accepted: 04/17/2023] [Indexed: 04/29/2023] Open
Abstract
This study aimed to investigate the effects of cyclosporine on the morphology, cell wall structure, and secretion characteristics of Cryptococcus neoformans. The minimum inhibitory concentration (MIC) of cyclosporine was found to be 2 µM (2.4 µg/mL) for the H99 strain. Yeast cells treated with cyclosporine at half the MIC showed altered morphology, including irregular shapes and elongated projections, without an effect on cell metabolism. Cyclosporine treatment resulted in an 18-fold increase in chitin and an 8-fold increase in lipid bodies, demonstrating changes in the fungal cell wall structure. Cyclosporine also reduced cell body and polysaccharide capsule diameters, with a significant reduction in urease secretion in C. neoformans cultures. Additionally, the study showed that cyclosporine increased the viscosity of secreted polysaccharides and reduced the electronegativity and conductance of cells. The findings suggest that cyclosporine has significant effects on C. neoformans morphology, cell wall structure, and secretion, which could have implications for the development of new antifungal agents.
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Affiliation(s)
- Iara Bastos de Andrade
- Laboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Dario Corrêa-Junior
- Laboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Vinicius Alves
- Laboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | | | - Marcos Vinicius Santos
- Laboratório de Micologia, Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz, Rio de Janeiro 21941-902, Brazil
| | - Marcos Abreu Almeida
- Laboratório de Micologia, Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz, Rio de Janeiro 21941-902, Brazil
| | - Alessandro Fernandes Valdez
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Leonardo Nimrichter
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
- Rede Micologia RJ, FAPERJ, Rio de Janeiro 21941-902, Brazil
| | - Rodrigo Almeida-Paes
- Laboratório de Micologia, Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz, Rio de Janeiro 21941-902, Brazil
- Rede Micologia RJ, FAPERJ, Rio de Janeiro 21941-902, Brazil
| | - Susana Frases
- Laboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
- Rede Micologia RJ, FAPERJ, Rio de Janeiro 21941-902, Brazil
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13
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Physicochemical properties of intact fungal cell wall determine vesicles release and nanoparticles internalization. Heliyon 2023; 9:e13834. [PMID: 36873462 PMCID: PMC9981904 DOI: 10.1016/j.heliyon.2023.e13834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 02/12/2023] [Accepted: 02/14/2023] [Indexed: 02/19/2023] Open
Abstract
Our previous microscopic observations on the wet mount of cultured Candida yeast showed release of large extracellular vesicles (EVs) that contained intracellular bacteria (∼500-5000 nm). We used Candida tropicalis, to examine the internalization of nanoparticles (NPs) with different properties to find out whether the size and flexibility of both EVs and cell wall pores play role in transport of large particles across the cell wall. Candida tropicalis was cultured in N-acetylglucoseamine-yeast extract broth (NYB) and examined for release of EVs every 12 h by the light microscope. The yeast was also cultured in NYB supplemented with of 0.1%, 0.01% of Fluorescein isothiocyanate (FITC)-labelled NPs; gold (0.508 mM/L and 0.051 mM/L) (45, 70 and 100 nm), albumin (0.0015 mM/L and 0.015 mM/L) (100 nm) and Fluospheres (0.2 and 0.02%) (1000 and 2000 nm). Internalization of NPs was recorded with fluorescence microscope after 30 s to 120 min. Release of EVs mostly occurred at 36 h and concentration of 0.1% was the best for internalization of NPs that occurred at 30 s after treatment. Positively charged 45 nm NPs internalized into >90% of yeasts but 100 nm gold NPs destroyed them. However, 70 nm gold and 100 nm negatively-charged albumin were internalized into <10% of yeasts without destroying them. Inert Fluospheres either remained intact on the surface of yeasts or became degraded and internalized into ∼100% of yeasts. Release of large EVs from the yeast but internalization of 45 nm NPs indicated that flexibility of EVs and cell wall pores as well as physicochemical properties of NPs determine transport across the cell wall.
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Phospholipase B Is Critical for Cryptococcus neoformans Survival in the Central Nervous System. mBio 2023; 14:e0264022. [PMID: 36786559 PMCID: PMC10127605 DOI: 10.1128/mbio.02640-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
Cryptococcus neoformans (Cn) is an opportunistic, encapsulated, yeast-like fungus that causes severe meningoencephalitis, especially in countries with high HIV prevalence. In addition to its well-known polysaccharide capsule, Cn has other virulence factors such as phospholipases, a heterogeneous group of enzymes that hydrolyze ester linkages in glycerophospholipids. Phospholipase B (PLB1) has been demonstrated to play a key role in Cn pathogenicity. In this study, we used a PLB1 mutant (plb1) and its reconstituted strain (Rec1) to assess the importance of this enzyme on Cn brain infection in vivo and in vitro. Mice infected with the plb1 strain survive significantly longer, have lower peripheral and central nervous system (CNS) fungal loads, and have fewer and smaller cryptococcomas or biofilm-like brain lesions compared to H99- and Rec1-infected animals. PLB1 causes extensive brain tissue damage and changes microglia morphology during cryptococcal disease, observations which can have important implications in patients with altered mental status or dementia as these manifestations are related to poorer survival outcomes. plb1 cryptococci are significantly more phagocytosed and killed by NR-9460 microglia-like cells. plb1 cells have altered capsular polysaccharide biophysical properties which impair their ability to stimulate glial cell responses or morphological changes. Here, we provide significant evidence demonstrating that Cn PLB1 is an important virulence factor for fungal colonization of and survival in the CNS as well as in the progression of cryptococcal meningoencephalitis. These findings may potentially help fill in a gap of knowledge in our understanding of cerebral cryptococcosis and provide novel research avenues in Cn pathogenesis. IMPORTANCE Cryptococcal meningoencephalitis (CME) is a serious disease caused by infection by the neurotropic fungal pathogen Cryptococcus neoformans. Due to the increasing number of cases in HIV-infected individuals, as well as the limited therapies available, investigation into potential targets for new therapeutics has become critical. Phospholipase B is an enzyme synthesized by Cn that confers virulence to the fungus through capsular enlargement, immunomodulation, and intracellular replication. In this study, we examined the properties of PLB1 by comparing infection of a Cn PLB1 mutant strain with both the wild-type and a PLB1-reconstituted strain. We show that PLB1 augments the survival and proliferation of the fungus in the CNS and strengthens virulence by modulating the immune response and enhancing specific biophysical properties of the fungus. PLB1 expression causes brain tissue damage and impacts glial cell functions, which may be responsible for the dementia observed in patients which may persist even after resolving from CME. The implications of PLB1 inhibition reveal its involvement in Cn infection and suggest that it may be a possible molecular target in the development of antifungal therapies. The results of this study support additional investigation into the mechanism of PLB1 to further understand the intricacies of cerebral Cn infection.
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15
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Lyophilization induces physicochemical alterations in cryptococcal exopolysaccharide. Carbohydr Polym 2022; 291:119547. [PMID: 35698377 PMCID: PMC10064552 DOI: 10.1016/j.carbpol.2022.119547] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/14/2022] [Accepted: 04/25/2022] [Indexed: 11/23/2022]
Abstract
Microbial polysaccharide characterization requires purification that often involves detergent precipitation and lyophilization. Here we examined physicochemical changes following lyophilization of Cryptococcus neoformans exopolysaccharide (EPS). Solution 1H Nuclear Magnetic Resonance (NMR) reveals significant anomeric signal attenuation following lyophilization of native EPS while 1H solid-state Nuclear Magnetic Resonance (ssNMR) shows few changes, suggesting diminished molecular motion and consequent broadening of 1H NMR polysaccharide resonances. 13C ssNMR, dynamic light scattering, and transmission electron microscopy show that, while native EPS has rigid molecular characteristics and contains small, loosely packed polysaccharide assemblies, lyophilized and resuspended EPS is disordered and contains larger dense aggregates, suggesting that structural water molecules in the interior of the polysaccharide assemblies are removed during extensive lyophilization. Importantly, mAbs to C. neoformans polysaccharide bind native EPS more strongly than lyophilized EPS. Together, these observations argue for caution when interpreting the biological and immunological attributes of polysaccharides that have been lyophilized to dryness.
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Abstract
Cryptococcosis is a disease caused by the pathogenic fungi Cryptococcus neoformans and Cryptococcus gattii, both environmental fungi that cause severe pneumonia and may even lead to cryptococcal meningoencephalitis. Although C. neoformans affects more fragile individuals, such as immunocompromised hosts through opportunistic infections, C. gattii causes a serious indiscriminate primary infection in immunocompetent individuals. Typically seen in tropical and subtropical environments, C. gattii has increased its endemic area over recent years, largely due to climatic factors that favor contagion in warmer climates. It is important to point out that not only C. gattii, but the Cryptococcus species complex produces a polysaccharidic capsule with immunomodulatory properties, enabling the pathogenic species of Cryptococccus to subvert the host immune response during the establishment of cryptococcosis, facilitating its dissemination in the infected organism. C. gattii causes a more severe and difficult-to-treat infection, with few antifungals eliciting an effective response during chronic treatment. Much of the immunopathology of this cryptococcosis is still poorly understood, with most studies focusing on cryptococcosis caused by the species C. neoformans. C. gattii became more important in the epidemiological scenario with the outbreaks in the Pacific Northwest of the United States, which resulted in phylogenetic studies of the virulent variant responsible for the severe infection in the region. Since then, the study of cryptococcosis caused by C. gattii has helped researchers understand the immunopathological aspects of different variants of this pathogen.
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17
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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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18
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Wear MP, Jacobs E, Wang S, McConnell S, Bowen A, Strother C, Cordero RJB, Crawford CJ, Casadevall A. Cryptococcus neoformans capsule regrowth experiments reveal dynamics of enlargement and architecture. J Biol Chem 2022; 298:101769. [PMID: 35218774 PMCID: PMC8942833 DOI: 10.1016/j.jbc.2022.101769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 11/25/2022] Open
Abstract
The polysaccharide capsule of fungal pathogen Cryptococcus neoformans is a critical virulence factor that has historically evaded complete characterization. Cryptococcal polysaccharides are known to either remain attached to the cell as capsular polysaccharides (CPS) or to be shed into the extracellular space as exopolysaccharides (EPS). While many studies have examined the properties of EPS, far less is known about CPS. In this work, we detail the development of a new physical and enzymatic method for the isolation of CPS which can be used to explore the architecture of the capsule and isolated capsular material. We show that sonication or Glucanex enzyme cocktail digestion yields soluble CPS preparations, while use of a French pressure cell press and Glucanex digestion followed by cell disruption removed the capsule and produced cell wall-associated polysaccharide aggregates that we call 'capsule ghosts', implying an inherent organization that allows the CPS to exist independent of the cell wall surface. Since sonication and Glucanex digestion were non-cytotoxic, it was also possible to observe the cryptococcal cells rebuilding their capsule, revealing the presence of reducing-end glycans throughout the capsule. Finally, analysis of DMSO-extracted and sonicated CPS preparations revealed the conservation of previously identified GXM motifs only in the sonicated CPS. Together, these observations provide new insights into capsule architecture and synthesis, consistent with a model in which the capsule is assembled from the cell wall outwards using smaller polymers, which are then compiled into larger ones.
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Affiliation(s)
- Maggie P Wear
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
| | - Ella Jacobs
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Siqing Wang
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Scott McConnell
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Anthony Bowen
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Camilla Strother
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Radames J B Cordero
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Conor J Crawford
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Arturo Casadevall
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
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19
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Figueiredo ABC, Fonseca FL, Kuczera D, Conte FDP, Arissawa M, Rodrigues ML. Monoclonal Antibodies against Cell Wall Chitooligomers as Accessory Tools for the Control of Cryptococcosis. Antimicrob Agents Chemother 2021; 65:e0118121. [PMID: 34570650 PMCID: PMC8597760 DOI: 10.1128/aac.01181-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 09/21/2021] [Indexed: 11/20/2022] Open
Abstract
Therapeutic strategies against systemic mycoses can involve antifungal resistance and significant toxicity. Thus, novel therapeutic approaches to fight fungal infections are urgent. Monoclonal antibodies (MAbs) are promising tools to fight systemic mycoses. In this study, MAbs of the IgM isotype were developed against chitin oligomers. Chitooligomers derive from chitin, an essential component of the fungal cell wall and a promising therapeutic target, as it is not synthesized by humans or animals. Surface plasmon resonance (SPR) assays and cell-binding tests showed that the MAbs recognizing chitooligomers have high affinity and specificity for the chitin derivatives. In vitro tests showed that the chitooligomer MAbs increased the fungicidal capacity of amphotericin B against Cryptococcus neoformans. The chitooligomer-binding MAbs interfered with two essential properties related to cryptococcal pathogenesis: biofilm formation and melanin production. In a murine model of C. neoformans infection, the combined administration of the chitooligomer-binding MAb and subinhibitory doses of amphotericin B promoted disease control. The data obtained in this study support the hypothesis that chitooligomer antibodies have great potential as accessory tools in the control of cryptococcosis.
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Affiliation(s)
| | - Fernanda L. Fonseca
- Centro de Desenvolvimento Tecnológico em Saúde, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Diogo Kuczera
- Instituto Carlos Chagas, Fundação Oswaldo Cruz, Curitiba, Brazil
| | - Fernando de Paiva Conte
- Projeto Implantação Planta Piloto, Bio-Manguinhos, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Marcia Arissawa
- Vice Diretoria de Desenvolvimento Técnologico, Bio-Manguinhos, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Marcio L. Rodrigues
- Instituto Carlos Chagas, Fundação Oswaldo Cruz, Curitiba, Brazil
- Instituto de Microbiologia Paulo de Góes da Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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20
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Inositol Metabolism Regulates Capsule Structure and Virulence in the Human Pathogen Cryptococcus neoformans. mBio 2021; 12:e0279021. [PMID: 34724824 PMCID: PMC8561382 DOI: 10.1128/mbio.02790-21] [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: 02/06/2023] Open
Abstract
The environmental yeast Cryptococcus neoformans is the most common cause of deadly fungal meningitis in primarily immunocompromised populations. A number of factors contribute to cryptococcal pathogenesis. Among them, inositol utilization has been shown to promote C. neoformans development in nature and invasion of central nervous system during dissemination. The mechanisms of the inositol regulation of fungal virulence remain incompletely understood. In this study, we analyzed inositol-induced capsule growth and the contribution of a unique inositol catabolic pathway in fungal development and virulence. We found that genes involved in the inositol catabolic pathway are highly induced by inositol, and they are also highly expressed in the cerebrospinal fluid of patients with meningoencephalitis. This pathway in C. neoformans contains three genes encoding myo-inositol oxygenases that convert myo-inositol into d-glucuronic acid, a substrate of the pentose phosphate cycle and a component of the polysaccharide capsule. Our mutagenesis analysis demonstrates that inositol catabolism is required for C. neoformans virulence and deletion mutants of myo-inositol oxygenases result in altered capsule growth as well as the polysaccharide structure, including O-acetylation. Our study indicates that the ability to utilize the abundant inositol in the brain may contribute to fungal pathogenesis in this neurotropic fungal pathogen. IMPORTANCE The human pathogen Cryptococcus neoformans is the leading cause of fungal meningitis in primarily immunocompromised populations. Understanding how this environmental organism adapts to the human host to cause deadly infection will guide our development of novel disease control strategies. Our recent studies revealed that inositol utilization by the fungus promotes C. neoformans development in nature and invasion of the central nervous system during infection. The mechanisms of the inositol regulation in fungal virulence remain incompletely understood. In this study, we found that C. neoformans has three genes encoding myo-inositol oxygenase, a key enzyme in the inositol catabolic pathway. Expression of these genes is highly induced by inositol, and they are highly expressed in the cerebrospinal fluid of patients with meningoencephalitis. Our mutagenesis analysis indeed demonstrates that inositol catabolism is required for C. neoformans virulence by altering the growth and structure of polysaccharide capsule, a major virulence factor. Considering the abundance of free inositol and inositol-related metabolites in the brain, our study reveals an important mechanism of host inositol-mediated fungal pathogenesis for this neurotropic fungal pathogen.
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21
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Bhalla K, Qu X, Kretschmer M, Kronstad JW. The phosphate language of fungi. Trends Microbiol 2021; 30:338-349. [PMID: 34479774 DOI: 10.1016/j.tim.2021.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 07/31/2021] [Accepted: 08/03/2021] [Indexed: 11/20/2022]
Abstract
Phosphate is an essential macronutrient for fungal proliferation as well as a key mediator of antagonistic, beneficial, and pathogenic interactions between fungi and other organisms. In this review, we summarize recent insights into the integration of phosphate metabolism with mechanisms of fungal adaptation that support growth and survival. In particular, we highlight aspects of phosphate sensing important for responses to stress and regulation of cell-surface changes with an impact on fungal pathogenesis, host immune responses, and disease outcomes. Additionally, new studies provide insights into the influence of phosphate availability on cooperative or antagonistic interactions between fungi and other microbes, the associations of mycorrhizal and endophytic fungi with plants, and connections with plant immunity. Overall, phosphate homeostasis is emerging as an integral part of fungal metabolism and communication to support diverse lifestyles.
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Affiliation(s)
- Kabir Bhalla
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Xianya Qu
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Matthias Kretschmer
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - James W Kronstad
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada.
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22
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Oliveira DSLD, Paredes V, Caixeta AV, Henriques NM, Wear MP, Albuquerque P, Felipe MSS, Casadevall A, Nicola AM. Hinge influences in murine IgG binding to Cryptococcus neoformans capsule. Immunology 2021; 165:110-121. [PMID: 34458991 DOI: 10.1111/imm.13411] [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: 06/01/2021] [Revised: 08/07/2021] [Accepted: 08/19/2021] [Indexed: 11/30/2022] Open
Abstract
Decades of studies on antibody structure led to the tenet that the V region binds antigens while the C region interacts with immune effectors. In some antibodies, however, the C region affects affinity and/or specificity for the antigen. One example is the 3E5 monoclonal murine IgG family, in which the mIgG3 isotype has different fine specificity to the Cryptococcus neoformans capsule polysaccharide than the other mIgG isotypes despite their identical variable sequences. Our group serendipitously found another pair of mIgG1/mIgG3 antibodies based on the 2H1 hybridoma to the C. neoformans capsule that recapitulated the differences observed with 3E5. In this work, we report the molecular basis of the constant domain effects on antigen binding using recombinant antibodies. As with 3E5, immunofluorescence experiments show a punctate pattern for 2H1-mIgG3 and an annular pattern for 2H1-mIgG1; these binding patterns have been associated with protective efficacy in murine cryptococcosis. Also as observed with 3E5, 2H1-mIgG3 bound on ELISA to both acetylated and non-acetylated capsular polysaccharide, whereas 2H1-mIgG1 only bound well to the acetylated form, consistent with differences in fine specificity. In engineering hybrid mIgG1/mIgG3 antibodies, we found that switching the 2H1-mIgG3 hinge for its mIgG1 counterpart changed the immunofluorescence pattern to annular, but a 2H1-mIgG1 antibody with an mIgG3 hinge still had an annular pattern. The hinge is thus necessary but not sufficient for these changes in binding to the antigen. This important role for the constant region in antigen binding could affect antibody biology and engineering.
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Affiliation(s)
| | | | | | | | - Maggie P Wear
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | | | - Maria Sueli Soares Felipe
- Graduate Program in Genomic Sciences and Biotechnology, Catholic University of Brasília, Brasília, Brazil
| | - Arturo Casadevall
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - André Moraes Nicola
- Faculty of Medicine, University of Brasília, Brasília, Brazil.,Graduate Program in Genomic Sciences and Biotechnology, Catholic University of Brasília, Brasília, Brazil
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Piffer AC, Santos FMD, Thomé MP, Diehl C, Garcia AWA, Kinskovski UP, Schneider RDO, Gerber A, Feltes BC, Schrank A, Vasconcelos ATR, Lenz G, Kmetzsch L, Vainstein MH, Staats CC. Transcriptomic analysis reveals that mTOR pathway can be modulated in macrophage cells by the presence of cryptococcal cells. Genet Mol Biol 2021; 44:e20200390. [PMID: 34352067 PMCID: PMC8341293 DOI: 10.1590/1678-4685-gmb-2020-0390] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 05/05/2021] [Indexed: 11/21/2022] Open
Abstract
Cryptococcus neoformans and Cryptococcus gattii are the etiological agents of cryptococcosis, a high mortality disease. The development of such disease depends on the interaction of fungal cells with macrophages, in which they can reside and replicate. In order to dissect the molecular mechanisms by which cryptococcal cells modulate the activity of macrophages, a genome-scale comparative analysis of transcriptional changes in macrophages exposed to Cryptococcus spp. was conducted. Altered expression of nearly 40 genes was detected in macrophages exposed to cryptococcal cells. The major processes were associated with the mTOR pathway, whose associated genes exhibited decreased expression in macrophages incubated with cryptococcal cells. Phosphorylation of p70S6K and GSK-3β was also decreased in macrophages incubated with fungal cells. In this way, Cryptococci presence could drive the modulation of mTOR pathway in macrophages possibly to increase the survival of the pathogen.
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Affiliation(s)
- Alícia C Piffer
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
| | - Francine M Dos Santos
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
| | - Marcos P Thomé
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
| | - Camila Diehl
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
| | - Ane Wichine Acosta Garcia
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
| | - Uriel Perin Kinskovski
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
| | - Rafael de Oliveira Schneider
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
| | - Alexandra Gerber
- Laboratório Nacional de Computação Científica, Petrópolis, RJ, Brazil
| | - Bruno César Feltes
- Universidade Federal do Rio Grande do Sul, Instituto de Informática, Porto Alegre, RS, Brazil
| | - Augusto Schrank
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
| | | | - Guido Lenz
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
| | - Lívia Kmetzsch
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
| | - Marilene H Vainstein
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
| | - Charley C Staats
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Porto Alegre, RS, Brazil
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Production of Secreted Carbohydrates that Present Immunologic Similarities with the Cryptococcus Glucuronoxylomannan by Members of the Trichosporonaceae Family: A Comparative Study Among Species of Clinical Interest. Mycopathologia 2021; 186:377-385. [PMID: 33956292 DOI: 10.1007/s11046-021-00558-w] [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: 04/22/2021] [Indexed: 10/20/2022]
Abstract
Glucuronoxylomannan (GXM) participates in several immunoregulatory mechanisms, which makes it an important Cryptococcus virulence factor that is essential for the disease. Trichosporon asahii and Trichosporon mucoides share with Cryptococcus species the ability to produce GXM. To check whether other opportunistic species in the Trichosporonaceae family produce GXM-like polysaccharides, extracts from 28 strains were produced from solid cultures and their carbohydrate content evaluated by the sulfuric acid / phenol method. Moreover, extracts were assessed for cryptococcal GXM cross-reactivity through latex agglutination and lateral flow assay methods. Cryptococcus neoformans and Saccharomyces cerevisiae were used as positive and negative controls, respectively. In addition to T. asahii, the species Trichosporon inkin, Apiotrichum montevideense, Trichosporon japonicum, Trichosporon faecale, Trichosporon ovoides, Cutaneotrichosporon debeurmannianum, and Cutaneotrichosporon arboriformis are also producers of a polysaccharide immunologically similar to the GXM produced by human pathogenic Cryptococcus species. The carbohydrate concentration of the extracts presented a positive correlation with the GXM contents determined by titration of both methodologies. These results add several species to the list of fungal pathogens that produce glycans of the GXM type and bring information about the origin of potential false-positive results on immunological tests for diagnosis of cryptococcosis based on GXM detection.
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Pruksaphon K, Intaramat A, Simsiriwong P, Mongkolsuk S, Ratanabanangkoon K, Nosanchuk JD, Kaltsas A, Youngchim S. An inexpensive point-of-care immunochromatographic test for Talaromyces marneffei infection based on the yeast phase specific monoclonal antibody 4D1 and Galanthus nivalis agglutinin. PLoS Negl Trop Dis 2021; 15:e0009058. [PMID: 33945531 PMCID: PMC8096094 DOI: 10.1371/journal.pntd.0009058] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/22/2020] [Indexed: 11/29/2022] Open
Abstract
Talaromyces marneffei is a thermally dimorphic fungus that causes opportunistic systemic mycoses in patients with AIDS or other immunodeficiency syndromes. The purpose of this study was to develop an immunochromatographic strip test (ICT) based on a solid phase sandwich format immunoassay for the detection of T. marneffei antigens in clinical urine specimens. The T. marneffei yeast phase specific monoclonal antibody 4D1 (MAb4D1) conjugated with colloidal gold nanoparticle was used as a specific signal reporter. Galanthus nivalis Agglutinin (GNA) was adsorbed onto nitrocellulose membrane to serve as the test line. Similarly, a control line was created above the test line by immobilization of rabbit anti-mouse IgG. The immobilized GNA served as capturing molecule and as non-immune mediated anti-terminal mannose of T. marneffei antigenic mannoprotein. The MAb4D1–GNA based ICT showed specific binding activity with yeast phase antigen of T. marneffei, and it did not react with other common pathogenic fungal antigens. The limit of detection of this ICT for T. marneffei antigen spiked in normal urine was approximately 0.6 μg/ml. The diagnostic performance of the ICT was validated using 341 urine samples from patents with culture- confirmed T. marneffei infection and from a control group of healthy individuals and patients with other infections in an endemic area. The ICT exhibited 89.47% sensitivity, 100% specificity, and 97.65% accuracy. Our results demonstrate that the urine-based GNA–MAb4D1 based ICT produces a visual result within 30 minutes and that the test is highly specific for the diagnosis of T. marneffei infection. The findings validate the deployment of the ICT for clinical use. Talaromycosis (Penicilliosis marneffei) is a neglected disease that causes an opportunistic systemic mycoses in AIDS and other immune-deficient patients living in Southeast Asia, China and the Indian subcontinent. Although laboratory culture remains a gold standard diagnostic method, it lacks sensitivity and is time-consuming, which results in delayed patient’s treatment and needed care. In this study, we develop an immunochromatographic strip test (ICT) by utilizing a yeast phase specific monoclonal antibody 4D1 and Galanthus nivalis agglutinin for detection of T. marneffei antigens in clinical urine specimens. Our data showed that the assay exhibited high sensitivity (89.47%) and specificity (100%), with its result available within 30 minutes. In addition, this diagnostic assay is inexpensive, reproducible, and simple to perform. Therefore, the T. marneffei ICT should be considered for clinical application in the context of rapid and affordable point-of-care diagnostic test to reduce the burden of talaromycosis mortality in patients in low resource countries.
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Affiliation(s)
- Kritsada Pruksaphon
- Graduate Program in Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Akarin Intaramat
- Translational Research Unit, Laboratory of Immunology and Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Pavinee Simsiriwong
- Translational Research Unit, Laboratory of Immunology and Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Translational Research Unit, Laboratory of Immunology and Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Kavi Ratanabanangkoon
- Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Joshua D. Nosanchuk
- Department of Medicine (Infectious Diseases), Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Anna Kaltsas
- Department of Medicine, Division of Infectious Diseases, Memorial Sloan Kettering Cancer Center, United States of America
- Department of Medicine, Weill Cornell Medical College, Cornell University, New York, United States of America
| | - Sirida Youngchim
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- * E-mail:
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A Novel, Inexpensive In-House Immunochromatographic Strip Test for Cryptococcosis Based on the Cryptococcal Glucuronoxylomannan Specific Monoclonal Antibody 18B7. Diagnostics (Basel) 2021; 11:diagnostics11050758. [PMID: 33922698 PMCID: PMC8145812 DOI: 10.3390/diagnostics11050758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/16/2021] [Accepted: 04/21/2021] [Indexed: 12/01/2022] Open
Abstract
The aim of this study was to develop a novel lateral flow immunochromatoghaphic strip test (ICT) for detecting cryptococcal polysaccharide capsular antigens using only a single specific monoclonal antibody, mAb 18B7. The mAb 18B7 is a well characterized antibody that specifically binds repeating epitopes displayed on the cryptococcal polysaccharide glucuronoxylomannan (GXM). We validated the immunoreactivities of mAb 18B7 against capsular antigens of different cryptococcal serotypes. The mAb 18B7 ICT was constructed as a sandwich ICT strip and the antibody serving in the mobile phase (colloidal gold conjugated mAb 18B7) to bind one of the GXM epitopes while the stationary phase antibody (immobilized mAb18B7 on test line) binding to other remaining unoccupied epitopes to generate a positive visual readout. The lower limit of detection of capsular antigens for each of the Cryptococcus serotypes tested was 0.63 ng/mL. No cross-reaction was found against a panel of antigens isolated from cultures of other pathogenic fungal, except the crude antigen of Trichosporon sp. with the lower limit of detection of 500 ng/mL (~800 times higher than that for cryptococcal GXM). The performance of the mAb 18B7 ICT strip was studied using cerebrospinal fluid (CSF) and serum and compared to commercial diagnostic kits (latex agglutination CALAS and CrAg IMMY). The sensitivity, specificity and accuracy of the mAb18B7 ICT with CSF from patients with confirmed cryptococcal meningitis were 92.86%, 100% and 96.23%, respectively. No false positives were observed with samples from non-cryptococcosis patients. With serum samples, the mAb 18B7 ICT gave a sensitivity, specificity and accuracy of 96.15%, 97.78% and 96.91%, respectively. Our results show that the mAb 18B7 based ICT was reliable, reproducible, and cost-effective as a point-of-care immunodiagnostic test for cryptococcosis. The mAb 18B7 ICT may be particularly useful in countries where commercial kits are not available or affordable.
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27
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Araújo GRDS, Alves V, Martins-de-Souza PH, Guimarães AJ, Honorato L, Nimrichter L, Takiya CM, Pontes B, Frases S. Dexamethasone and Methylprednisolone Promote Cell Proliferation, Capsule Enlargement, and in vivo Dissemination of C. neoformans. FRONTIERS IN FUNGAL BIOLOGY 2021; 2:643537. [PMID: 37744119 PMCID: PMC10512211 DOI: 10.3389/ffunb.2021.643537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 01/19/2021] [Indexed: 09/26/2023]
Abstract
Cryptococcus neoformans is a fungal pathogen that causes life-threatening infections in immunocompromised individuals, who often have some inflammatory condition and, therefore, end up using glucocorticoids, such as dexamethasone and methylprednisolone. Although the effects of this class of molecules during cryptococcosis have been investigated, their consequences for the biology of C. neoformans is less explored. Here, we studied the effects of dexamethasone and methylprednisolone on the metabolism and on the induction of virulence factors in C. neoformans. Our results showed that both glucocorticoids increased fungal cell proliferation and surface electronegativity but reduced capsule and secreted polysaccharide sizes, as well as capsule compaction, by decreasing the density of polysaccharide fibers. We also tested whether glucocorticoids could affect the fungal virulence in Galleria mellonella and mice. Although the survival rate of Galleria larvae increased, those from mice showed a tendency to decrease, with infected animals dying earlier after glucocorticoid treatments. The pathogenesis of spread of cryptococcosis and the interleukin secretion pattern were also assessed for lungs and brains of infected mice. While increases in the spread of the fungus to lungs were observed after treatment with glucocorticoids, a significant difference in brain was observed only for methylprednisolone, although a trend toward increasing was also observed for dexamethasone. Moreover, increases in both pulmonary and cerebral IL-10 production, reduction of IL-6 production but no changes in IL-4, IL-17, and INF-γ were also observed after glucocorticoid treatments. Finally, histopathological analysis confirmed the increase in number of fungal cells in lung and brain tissues of mice previously subjected to dexamethasone or methylprednisolone treatments. Together, our results provide compelling evidence for the effects of dexamethasone and methylprednisolone on the biology of C. neoformans and may have important implications for future clinical treatments, calling attention to the risks of using these glucocorticoids against cryptococcosis or in immunocompromised individuals.
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Affiliation(s)
- Glauber R. de S. Araújo
- Laboratório de Ultraestrutura Cellular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
- Laboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Vinicius Alves
- Laboratório de Ultraestrutura Cellular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
- Laboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Pedro H. Martins-de-Souza
- Laboratório de Ultraestrutura Cellular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
- Laboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Allan J. Guimarães
- Laboratório de Bioquímica e Imunologia das Micoses, Depto. de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil
| | - Leandro Honorato
- Instituto de Microbiologia Paulo de Góes, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Leonardo Nimrichter
- Instituto de Microbiologia Paulo de Góes, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Christina Maeda Takiya
- Laboratório de Imunopatologia. Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Bruno Pontes
- Instituto de Ciências Biomédicas, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
- Centro Nacional de Biologia Estrutural e Bioimagem (CENABIO), Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Susana Frases
- Laboratório de Ultraestrutura Cellular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
- Laboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
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Gonçalves DDS, Rodriguez de La Noval C, Ferreira MDS, Honorato L, Araújo GRDS, Frases S, Pizzini CV, Nosanchuk JD, Cordero RJB, Rodrigues ML, Peralta JM, Nimrichter L, Guimarães AJ. Histoplasma capsulatum Glycans From Distinct Genotypes Share Structural and Serological Similarities to Cryptococcus neoformans Glucuronoxylomannan. Front Cell Infect Microbiol 2021; 10:565571. [PMID: 33585262 PMCID: PMC7874066 DOI: 10.3389/fcimb.2020.565571] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 11/17/2020] [Indexed: 11/20/2022] Open
Abstract
The cell wall is a ubiquitous structure in the fungal kingdom, with some features varying depending on the species. Additional external structures can be present, such as the capsule of Cryptococcus neoformans (Cn), its major virulence factor, mainly composed of glucuronoxylomannan (GXM), with anti-phagocytic and anti-inflammatory properties. The literature shows that other cryptococcal species and even more evolutionarily distant species, such as the Trichosporon asahii, T. mucoides, and Paracoccidioides brasiliensis can produce GXM-like polysaccharides displaying serological reactivity to GXM-specific monoclonal antibodies (mAbs), and these complex polysaccharides have similar composition and anti-phagocytic properties to cryptococcal GXM. Previously, we demonstrated that the fungus Histoplasma capsulatum (Hc) incorporates, surface/secreted GXM of Cn and the surface accumulation of the polysaccharide enhances Hc virulence in vitro and in vivo. In this work, we characterized the ability of Hc to produce cellular-attached (C-gly-Hc) and secreted (E-gly) glycans with reactivity to GXM mAbs. These C-gly-Hc are readily incorporated on the surface of acapsular Cn cap59; however, in contrast to Cn GXM, C-gly-Hc had no xylose and glucuronic acid in its composition. Mapping of recognized Cn GXM synthesis/export proteins confirmed the presence of orthologs in the Hc database. Evaluation of C-gly and E-gly of Hc from strains of distinct monophyletic clades showed serological reactivity to GXM mAbs, despite slight differences in their molecular dimensions. These C-gly-Hc and E-gly-Hc also reacted with sera of cryptococcosis patients. In turn, sera from histoplasmosis patients recognized Cn glycans, suggesting immunogenicity and the presence of cross-reacting antibodies. Additionally, C-gly-Hc and E-gly-Hc coated Cn cap59 were more resistant to phagocytosis and macrophage killing. C-gly-Hc and E-gly-Hc coated Cn cap59 were also able to kill larvae of Galleria mellonella. These GXM-like Hc glycans, as well as those produced by other pathogenic fungi, may also be important during host-pathogen interactions, and factors associated with their regulation are potentially important targets for the management of histoplasmosis.
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Affiliation(s)
- Diego de Souza Gonçalves
- Laboratório de Bioquímica e Imunologia das Micoses, Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil
- Pós-Graduação em Doenças Infecciosas e Parasitárias, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Claudia Rodriguez de La Noval
- Laboratório de Bioquímica e Imunologia das Micoses, Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil
- Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marina da Silva Ferreira
- Laboratório de Bioquímica e Imunologia das Micoses, Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil
- Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Leandro Honorato
- Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Glauber Ribeiro de Sousa Araújo
- Laboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Susana Frases
- Laboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Claudia Vera Pizzini
- Laboratório de Micologia, Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Joshua D. Nosanchuk
- Department of Microbiology and Immunology and Division of infectious Diseases, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY, United States
| | - Radames J. B. Cordero
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Marcio L. Rodrigues
- Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Instituto Carlos Chagas, Fundação Oswaldo Cruz (Fiocruz), Curitiba, Brazil
| | - José Mauro Peralta
- Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Leonardo Nimrichter
- Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Allan J. Guimarães
- Laboratório de Bioquímica e Imunologia das Micoses, Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil
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Cryptococcus neoformans Secretes Small Molecules That Inhibit IL-1 β Inflammasome-Dependent Secretion. Mediators Inflamm 2020; 2020:3412763. [PMID: 33380899 PMCID: PMC7748918 DOI: 10.1155/2020/3412763] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 10/22/2020] [Accepted: 11/04/2020] [Indexed: 01/22/2023] Open
Abstract
Cryptococcus neoformans is an encapsulated yeast that causes disease mainly in immunosuppressed hosts. It is considered a facultative intracellular pathogen because of its capacity to survive and replicate inside phagocytes, especially macrophages. This ability is heavily dependent on various virulence factors, particularly the glucuronoxylomannan (GXM) component of the polysaccharide capsule. Inflammasome activation in phagocytes is usually protective against fungal infections, including cryptococcosis. Nevertheless, recognition of C. neoformans by inflammasome receptors requires specific changes in morphology or the opsonization of the yeast, impairing proper inflammasome function. In this context, we analyzed the impact of molecules secreted by C. neoformans B3501 strain and its acapsular mutant Δcap67 in inflammasome activation in an in vitro model. Our results showed that conditioned media derived from B3501 was capable of inhibiting inflammasome-dependent events (i.e., IL-1β secretion and LDH release via pyroptosis) more strongly than conditioned media from Δcap67, regardless of GXM presence. We also demonstrated that macrophages treated with conditioned media were less responsive against infection with the virulent strain H99, exhibiting lower rates of phagocytosis, increased fungal burdens, and enhanced vomocytosis. Moreover, we showed that the aromatic metabolite DL-Indole-3-lactic acid (ILA) and DL-p-Hydroxyphenyllactic acid (HPLA) were present in B3501's conditioned media and that ILA alone or with HPLA is involved in the regulation of inflammasome activation by C. neoformans. These results were confirmed by in vivo experiments, where exposure to conditioned media led to higher fungal burdens in Acanthamoeba castellanii culture as well as in higher fungal loads in the lungs of infected mice. Overall, the results presented show that conditioned media from a wild-type strain can inhibit a vital recognition pathway and subsequent fungicidal functions of macrophages, contributing to fungal survival in vitro and in vivo and suggesting that secretion of aromatic metabolites, such as ILA, during cryptococcal infections fundamentally impacts pathogenesis.
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30
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Fu Y, Huang X, Zhou Z. Insight into the Assembling Mechanism of Cryptococcus Capsular Glucuronoxylomannan Based on Molecular Dynamics Simulations. ACS OMEGA 2020; 5:29351-29356. [PMID: 33225166 PMCID: PMC7676341 DOI: 10.1021/acsomega.0c04164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 10/21/2020] [Indexed: 06/11/2023]
Abstract
Cryptococcus spp. is an invasive fungal pathogen and causes life-threatening cryptococcosis. Opportunistic cryptococcal infections among the immunocompromised population are mostly caused by Cryptococcus neoformans, whereas the geographical dissemination of Cryptococcus gattii in recent years has threatened lives of even immunocompetent people. The capsule, mainly composed of glucuronoxylomannan (GXM) polysaccharides, plays important roles in the virulence of Cryptococcus spp. The assembling mechanism of GXM polysaccharides into the capsule is little understood because of insufficient experimental data. Molecular modeling and molecular dynamics simulation provide insight into the assembling process. We first built GXM oligosaccharide models of serotypes D, A, B, and C and extracted their secondary structure information from simulation trajectories. All the four mainchains tend to take the nearly twofold helical conformation, whereas peripheral sidechains prefer to form left-handed helices, which are further stabilized by intramolecular hydrogen bonds. Based on the obtained secondary structure information, GXM polysaccharide arrays were built to simulate capsule-assembling processes of C. neoformans and C. gattii using serotypes A and C as representatives, respectively. Trajectory analysis illustrates that electrostatic neutralization of acidic sidechain residues of GXM is a prerequisite for capsule assembling, followed by formation of intermolecular hydrogen bond networks. Further insight into the assembling mechanism of GXM polysaccharides provides the possibility to develop novel treatment and prevention solutions for cryptococcosis.
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Affiliation(s)
- Yankai Fu
- Key
Laboratory of Bioactive Materials, Ministry of Education, College
of Life Sciences, and State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China
- Beijing
Key Laboratory for Mechanism Study and Precision Diagnosis of Invasive
Fungal Diseases, Dynamiker Biotechnology
Sub-Center, Tianjin 300467, China
| | - Xinglu Huang
- Key
Laboratory of Bioactive Materials, Ministry of Education, College
of Life Sciences, and State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China
| | - Zeqi Zhou
- Beijing
Key Laboratory for Mechanism Study and Precision Diagnosis of Invasive
Fungal Diseases, Dynamiker Biotechnology
Sub-Center, Tianjin 300467, China
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Kuttel MM, Casadevall A, Oscarson S. Cryptococcus neoformans Capsular GXM Conformation and Epitope Presentation: A Molecular Modelling Study. Molecules 2020; 25:E2651. [PMID: 32517333 PMCID: PMC7321252 DOI: 10.3390/molecules25112651] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/01/2020] [Accepted: 06/04/2020] [Indexed: 12/31/2022] Open
Abstract
The pathogenic encapsulated Cryptococcus neoformans fungus causes serious disease in immunosuppressed hosts. The capsule, a key virulence factor, consists primarily of the glucuronoxylomannan polysaccharide (GXM) that varies in composition according to serotype. While GXM is a potential vaccine target, vaccine development has been confounded by the existence of epitopes that elicit non-protective antibodies. Although there is evidence for protective antibodies binding conformational epitopes, the secondary structure of GXM remains an unsolved problem. Here an array of molecular dynamics simulations reveal that the GXM mannan backbone is consistently extended and relatively inflexible in both C. neoformans serotypes A and D. Backbone substitution does not alter the secondary structure, but rather adds structural motifs: β DGlcA and β DXyl side chains decorate the mannan backbone in two hydrophillic fringes, with mannose-6-O-acetylation forming a hydrophobic ridge between them. This work provides mechanistic rationales for clinical observations-the importance of O-acetylation for antibody binding; the lack of binding of protective antibodies to short GXM fragments; the existence of epitopes that elicit non-protective antibodies; and the self-aggregation of GXM chains-indicating that molecular modelling can play a role in the rational design of conjugate vaccines.
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Affiliation(s)
- Michelle M. Kuttel
- Department of Computer Science, University of Cape Town, Cape Town 7701, South Africa
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, 615 N Wolfe St Room E5132, Baltimore, MD 21205, USA;
| | - Stefan Oscarson
- Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland;
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Crawford CJ, Cordero RJB, Guazzelli L, Wear MP, Bowen A, Oscarson S, Casadevall A. Exploring Cryptococcus neoformans capsule structure and assembly with a hydroxylamine-armed fluorescent probe. J Biol Chem 2020; 295:4327-4340. [PMID: 32005661 PMCID: PMC7105310 DOI: 10.1074/jbc.ra119.012251] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/30/2020] [Indexed: 11/06/2022] Open
Abstract
Chemical biology is an emerging field that enables the study and manipulation of biological systems with probes whose reactivities provide structural insights. The opportunistic fungal pathogen Cryptococcus neoformans possesses a polysaccharide capsule that is a major virulence factor, but is challenging to study. We report here the synthesis of a hydroxylamine-armed fluorescent probe that reacts with reducing glycans and its application to study the architecture of the C. neoformans capsule under a variety of conditions. The probe signal localized intracellularly and at the cell wall-membrane interface, implying the presence of reducing-end glycans at this location where the capsule is attached to the cell body. In contrast, no fluorescence signal was detected in the capsule body. We observed vesicle-like structures containing the reducing-end probe, both intra- and extracellularly, consistent with the importance of vesicles in capsular assembly. Disrupting the capsule with DMSO, ultrasound, or mechanical shear stress resulted in capsule alterations that affected the binding of the probe, as reducing ends were exposed and cell membrane integrity was compromised. Unlike the polysaccharides in the assembled capsule, isolated exopolysaccharides contained reducing ends. The reactivity of the hydroxylamine-armed fluorescent probe suggests a model for capsule assembly whereby reducing ends localize to the cell wall surface, supporting previous findings suggesting that this is an initiation point for capsular assembly. We propose that chemical biology is a promising approach for studying the C. neoformans capsule and its associated polysaccharides to unravel their roles in fungal virulence.
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Affiliation(s)
- Conor J Crawford
- Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland; Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205
| | - Radamés J B Cordero
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205
| | - Lorenzo Guazzelli
- Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Maggie P Wear
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205
| | - Anthony Bowen
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205
| | - Stefan Oscarson
- Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205.
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Oliveira FFM, Paes HC, Peconick LDF, Fonseca FL, Marina CLF, Bocca AL, Homem-de-Mello M, Rodrigues ML, Albuquerque P, Nicola AM, Alspaugh JA, Felipe MSS, Fernandes L. Erg6 affects membrane composition and virulence of the human fungal pathogen Cryptococcus neoformans. Fungal Genet Biol 2020; 140:103368. [PMID: 32201128 DOI: 10.1016/j.fgb.2020.103368] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 02/12/2020] [Accepted: 02/17/2020] [Indexed: 12/12/2022]
Abstract
Ergosterol is the most important membrane sterol in fungal cells and a component not found in the membranes of human cells. We identified the ERG6 gene in the AIDS-associated fungal pathogen, Cryptococcus neoformans, encoding the sterol C-24 methyltransferase of fungal ergosterol biosynthesis. In this work, we have explored its relationship with high-temperature growth and virulence of C. neoformans by the construction of a loss-of-function mutant. In contrast to other genes involved in ergosterol biosynthesis, C. neoformans ERG6 is not essential for growth under permissive conditions in vitro. However, the erg6 mutant displayed impaired thermotolerance and increased susceptibility to osmotic and oxidative stress, as well as to different antifungal drugs. Total lipid analysis demonstrated a decrease in the erg6Δ strain membrane ergosterol content. In addition, this mutant strain was avirulent in an invertebrate model of C. neoformans infection. C. neoformans Erg6 was cyto-localized in the endoplasmic reticulum and Golgi complex. Our results demonstrate that Erg6 is crucial for growth at high temperature and virulence, likely due to its effects on C. neoformans membrane integrity and dynamics. These pathogen-focused investigations into ergosterol biosynthetic pathway components reinforce the multiple roles of ergosterol in the response of diverse fungal species to alterations in the environment, especially that of the infected host. These studies open perspectives to understand the participation of ergosterol in mechanism of resistance to azole and polyene drugs. Observed synergistic growth defects with co-inhibition of Erg6 and other components of the ergosterol biosynthesis pathway suggests novel approaches to treatment in human fungal infections.
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Affiliation(s)
- Fabiana Freire M Oliveira
- Faculty of Medicine, Campus Darcy Ribeiro, University of Brasília, Asa Norte, Brasília, Federal District 70910-900, Brazil
| | - Hugo Costa Paes
- Faculty of Medicine, Campus Darcy Ribeiro, University of Brasília, Asa Norte, Brasília, Federal District 70910-900, Brazil
| | - Luísa Defranco F Peconick
- Faculty of Ceilândia, Campus UnB Ceilândia, University of Brasília, Ceilândia Sul, Centro Metropolitano, Brasília, Federal District 72220-275, Brazil
| | - Fernanda L Fonseca
- Center for Technological Development in Health (CDTS), Fiocruz-RJ, Rio de Janeiro 21045-360, Brazil.
| | - Clara Luna Freitas Marina
- Laboratory of Applied Immunology, Institute of Biology, Room J1 28/8, Building J, 2nd Floor, Campus Darcy Ribeiro, University of Brasília, Asa Norte, Brasilia, Federal District 70910-900, Brazil
| | - Anamélia Lorenzetti Bocca
- Laboratory of Applied Immunology, Institute of Biology, Room J1 28/8, Building J, 2nd Floor, Campus Darcy Ribeiro, University of Brasília, Asa Norte, Brasilia, Federal District 70910-900, Brazil.
| | - Mauricio Homem-de-Mello
- Faculty of Health Science, Campus Darcy Ribeiro, University of Brasília, Asa Norte, Brasília, Federal District 70910-900, Brazil.
| | - Márcio Lourenço Rodrigues
- Carlos Chagas Institute, Fiocruz-PR, Curitiba 81310-020, Brazil; Microbiology Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21941-590, Brazil
| | - Patrícia Albuquerque
- Faculty of Ceilândia, Campus UnB Ceilândia, University of Brasília, Ceilândia Sul, Centro Metropolitano, Brasília, Federal District 72220-275, Brazil
| | - André Moraes Nicola
- Faculty of Medicine, Campus Darcy Ribeiro, University of Brasília, Asa Norte, Brasília, Federal District 70910-900, Brazil
| | - J Andrew Alspaugh
- Duke University School of Medicine, Dept. of Medicine, Durham, DUMC Box 102359, 303 Sands Building, Research Drive, Durham, NC 27710, USA.
| | - Maria Sueli S Felipe
- Catolic University of Brasilia, Campus Asa Norte, SGAN 916 Módulo B Avenida W5, Asa Norte, Brasília, Federal District 70790-160, Brazil
| | - Larissa Fernandes
- Faculty of Ceilândia, Campus UnB Ceilândia, University of Brasília, Ceilândia Sul, Centro Metropolitano, Brasília, Federal District 72220-275, Brazil; Laboratory of Applied Immunology, Institute of Biology, Room J1 28/8, Building J, 2nd Floor, Campus Darcy Ribeiro, University of Brasília, Asa Norte, Brasilia, Federal District 70910-900, Brazil.
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Garcia-Santamarina S, Probst C, Festa RA, Ding C, Smith AD, Conklin SE, Brander S, Kinch LN, Grishin NV, Franz KJ, Riggs-Gelasco P, Lo Leggio L, Johansen KS, Thiele DJ. A lytic polysaccharide monooxygenase-like protein functions in fungal copper import and meningitis. Nat Chem Biol 2020; 16:337-344. [PMID: 31932719 PMCID: PMC7036007 DOI: 10.1038/s41589-019-0437-9] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 11/22/2019] [Indexed: 12/21/2022]
Abstract
Infection by the fungal pathogen Cryptococcus neoformans causes lethal meningitis, primarily in immune-compromised individuals. Colonization of the brain by C. neoformans is dependent on copper (Cu) acquisition from the host, which drives critical virulence mechanisms. While C. neoformans Cu+ import and virulence are dependent on the Ctr1 and Ctr4 proteins, little is known concerning extracellular Cu ligands that participate in this process. We identified a C. neoformans gene, BIM1, that is strongly induced during Cu limitation and which encodes a protein related to lytic polysaccharide monooxygenases (LPMOs). Surprisingly, bim1 mutants are Cu deficient, and Bim1 function in Cu accumulation depends on Cu2+ coordination and cell-surface association via a glycophosphatidyl inositol anchor. Bim1 participates in Cu uptake in concert with Ctr1 and expression of this pathway drives brain colonization in mouse infection models. These studies demonstrate a role for LPMO-like proteins as a critical factor for Cu acquisition in fungal meningitis.
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Affiliation(s)
- Sarela Garcia-Santamarina
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
- Genome Biology Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Corinna Probst
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Richard A Festa
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
- Irvine Scientific, Santa Ana, CA, USA
| | - Chen Ding
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
- College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Aaron D Smith
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Steven E Conklin
- Department of Chemistry, Duke University, Durham, NC, USA
- Division of Clinical Chemistry, Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Søren Brander
- Department of Geoscience and Natural Resource, University of Copenhagen, Copenhagen, Denmark
| | - Lisa N Kinch
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Nick V Grishin
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | | | - Leila Lo Leggio
- Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
| | - Katja Salomon Johansen
- Department of Geoscience and Natural Resource, University of Copenhagen, Copenhagen, Denmark
| | - Dennis J Thiele
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA.
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, USA.
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35
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Chung KY, Brown JCS. Biology and function of exo-polysaccharides from human fungal pathogens. CURRENT CLINICAL MICROBIOLOGY REPORTS 2020; 7:1-11. [PMID: 33042730 DOI: 10.1007/s40588-020-00137-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Purpose of review Environmental fungi such as Cryptococcus neoformans and Aspergillus fumigatus must survive many different and changing environments as they transition from their environmental niches to human lungs and other organs. Fungi alter their cell surfaces and secreted macromolecules to respond to and manipulate their surroundings. Recent findings This review focuses on exo-polysaccharides, chains of sugars that transported out of the cell and spread to the local environment. Major exo-polysaccharides for C. neoformans and A. fumigatus are glucuronylxylomannan (GXM) and galactosaminogalactan (GAG), respectively, which accumulate at high concentrations in growth medium and infected patients. Summary Here we discuss GXM and GAG synthesis and export, their immunomodulatory properties, and their roles in biofilm formation. We also propose areas of future research to address outstanding questions in the field that could facilitate development of new disease treatments.
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Affiliation(s)
- Krystal Y Chung
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Jessica C S Brown
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
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37
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Polysaccharide diversity in VNI isolates of Cryptococcus neoformans from Roraima, Northern Brazil. Fungal Biol 2019; 123:699-708. [DOI: 10.1016/j.funbio.2019.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/03/2019] [Accepted: 06/03/2019] [Indexed: 02/03/2023]
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38
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Araújo GRDS, Viana NB, Gómez F, Pontes B, Frases S. The mechanical properties of microbial surfaces and biofilms. ACTA ACUST UNITED AC 2019; 5:100028. [PMID: 32743144 PMCID: PMC7389442 DOI: 10.1016/j.tcsw.2019.100028] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 07/23/2019] [Indexed: 12/13/2022]
Abstract
Microbes can modify their surface structure as an adaptive mechanism for survival and dissemination in the environment or inside the host. Altering their ability to respond to mechanical stimuli is part of this adaptive process. Since the 1990s, powerful micromanipulation tools have been developed that allow mechanical studies of microbial cell surfaces, exploring little known aspects of their dynamic behavior. This review concentrates on the study of mechanical and rheological properties of bacteria and fungi, focusing on their cell surface dynamics and biofilm formation.
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Affiliation(s)
- Glauber R de S Araújo
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Nathan B Viana
- Laboratório de Pinças Óticas (LPO-COPEA), Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.,Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.,Centro Nacional de Biologia Estrutural e Bioimagem (CENABIO), Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Fran Gómez
- Laboratório de Pinças Óticas (LPO-COPEA), Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.,Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Bruno Pontes
- Laboratório de Pinças Óticas (LPO-COPEA), Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.,Centro Nacional de Biologia Estrutural e Bioimagem (CENABIO), Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Susana Frases
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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de S Araújo GR, Viana NB, Pontes B, Frases S. Rheological properties of cryptococcal polysaccharide change with fiber size, antibody binding and temperature. Future Microbiol 2019; 14:867-884. [PMID: 31340660 DOI: 10.2217/fmb-2018-0320] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Aim: Cryptococcus neoformans is the major agent of cryptococcosis. The main virulence factor is the polysaccharide (PS) capsule. Changes in cryptococcal PS properties have been poorly elucidated. Materials & methods: We analyzed the mechanical properties of secreted PS and intact capsules, using dynamic light scattering and optical tweezers. Results: Storage and loss moduli showed that secreted PS behaves as a viscoelastic liquid, while capsular PS behaves as a viscoelastic solid. The secreted PS remains as a viscoelastic fluid at different temperatures with thermal hysteresis after 85°C. Antibody binding altered the viscoelastic behavior of both secreted and capsular PS. Conclusion: Deciphering the mechanical aspects of these structures could reveal features that may have consequences in novel therapies against cryptococcosis.
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Affiliation(s)
- Glauber R de S Araújo
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Nathan B Viana
- Laboratório de Pinças Óticas (LPO-COPEA), Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.,Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Bruno Pontes
- Laboratório de Pinças Óticas (LPO-COPEA), Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Susana Frases
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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Cryptococcus neoformans Glucuronoxylomannan and Sterylglucoside Are Required for Host Protection in an Animal Vaccination Model. mBio 2019; 10:mBio.02909-18. [PMID: 30940711 PMCID: PMC6445945 DOI: 10.1128/mbio.02909-18] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The number of deaths from cryptococcal meningitis is around 180,000 per year. The disease is the second leading cause of mortality among individuals with AIDS. Antifungal treatment is costly and associated with adverse effects and resistance, evidencing the urgency of development of both therapeutic and prophylactic tools. Here we demonstrate the key roles of polysaccharide- and glycolipid-containing structures in a vaccination model to prevent cryptococcosis. Cryptococcus neoformans is an encapsulated fungal pathogen that causes meningoencephalitis. There are no prophylactic tools for cryptococcosis. Previously, our group showed that a C. neoformans mutant lacking the gene encoding sterylglucosidase (Δsgl1) induced protection in both immunocompetent and immunocompromised murine models of cryptococcosis. Since sterylglucosidase catalyzes degradation of sterylglucosides (SGs), accumulation of this glycolipid could be responsible for protective immunity. In this study, we analyzed whether the activity of SGs is sufficient for the protective effect induced by the Δsgl1 strain. We observed that the accumulation of SGs impacted several properties of the main polysaccharide that composes the fungal capsule, glucuronoxylomannan (GXM). We therefore used genetic manipulation to delete the SGL1 gene in the acapsular mutant Δcap59 to generate a double mutant (strain Δcap59/Δsgl1) that was shown to be nonpathogenic and cleared from the lung of mice within 7 days post-intranasal infection. The inflammatory immune response triggered by the Δcap59/Δsgl1 mutant in the lung differed from the response seen with the other strains. The double mutant did not induce protection in a vaccination model, suggesting that SG-related protection requires the main capsular polysaccharide. Finally, GXM-containing extracellular vesicles (EVs) enriched in SGs delayed the acute lethality of Galleria mellonella against C. neoformans infection. These studies highlighted a key role for GXM and SGs in inducing protection against a secondary cryptococcal infection, and, since EVs notoriously contain GXM, these results suggest the potential use of Δsgl1 EVs as a vaccination strategy for cryptococcosis.
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A Novel Protocol for the Isolation of Fungal Extracellular Vesicles Reveals the Participation of a Putative Scramblase in Polysaccharide Export and Capsule Construction in Cryptococcus gattii. mSphere 2019; 4:4/2/e00080-19. [PMID: 30894430 PMCID: PMC6429041 DOI: 10.1128/msphere.00080-19] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Extracellular vesicles (EVs) are fundamental components of the physiology of cells from all kingdoms. In pathogenic fungi, they participate in important mechanisms of transfer of antifungal resistance and virulence, as well as in immune stimulation and prion transmission. However, studies on the functions of fungal EVs are still limited by the lack of efficient methods for isolation of these compartments. In this study, we developed an alternative protocol for isolation of fungal EVs and demonstrated an application of this new methodology in the study of the physiology of the fungal pathogen Cryptococcus gattii. Our results describe a fast and reliable method for the study of fungal EVs and reveal the participation of scramblase, a phospholipid-translocating enzyme, in secretory processes of C. gattii. Regular protocols for the isolation of fungal extracellular vesicles (EVs) are time-consuming, hard to reproduce, and produce low yields. In an attempt to improve the protocols used for EV isolation, we explored a model of vesicle production after growth of Cryptococcus gattii and Cryptococcus neoformans on solid media. Nanoparticle tracking analysis in combination with transmission electron microscopy revealed that C. gattii and C. neoformans produced EVs in solid media. The properties of cryptococcal vesicles varied according to the culture medium used and the EV-producing species. EV detection was reproduced with an acapsular mutant of C. neoformans, as well as with isolates of Candida albicans, Histoplasma capsulatum, and Saccharomyces cerevisiae. Cryptococcal EVs produced in solid media were biologically active and contained regular vesicular components, including the major polysaccharide glucuronoxylomannan (GXM) and RNA. Since the protocol had higher yields and was much faster than the regular methods used for the isolation of fungal EVs, we asked if it would be applicable to address fundamental questions related to cryptococcal secretion. On the basis that polysaccharide export in Cryptococcus requires highly organized membrane traffic culminating with EV release, we analyzed the participation of a putative scramblase (Aim25; CNBG_3981) in EV-mediated GXM export and capsule formation in C. gattii. EVs from a C. gattiiaim25Δ strain differed from those obtained from wild-type (WT) cells in physical-chemical properties and cargo. In a model of surface coating of an acapsular cryptococcal strain with vesicular GXM, EVs obtained from the aim25Δ mutant were more efficiently used as a source of capsular polysaccharides. Lack of the Aim25 scramblase resulted in disorganized membranes and increased capsular dimensions. These results associate the description of a novel protocol for the isolation of fungal EVs with the identification of a previously unknown regulator of polysaccharide release. IMPORTANCE Extracellular vesicles (EVs) are fundamental components of the physiology of cells from all kingdoms. In pathogenic fungi, they participate in important mechanisms of transfer of antifungal resistance and virulence, as well as in immune stimulation and prion transmission. However, studies on the functions of fungal EVs are still limited by the lack of efficient methods for isolation of these compartments. In this study, we developed an alternative protocol for isolation of fungal EVs and demonstrated an application of this new methodology in the study of the physiology of the fungal pathogen Cryptococcus gattii. Our results describe a fast and reliable method for the study of fungal EVs and reveal the participation of scramblase, a phospholipid-translocating enzyme, in secretory processes of C. gattii.
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Wang ZA, Li LX, Doering TL. Unraveling synthesis of the cryptococcal cell wall and capsule. Glycobiology 2019; 28:719-730. [PMID: 29648596 DOI: 10.1093/glycob/cwy030] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 03/28/2018] [Indexed: 11/15/2022] Open
Abstract
Fungal pathogens cause devastating infections in millions of individuals each year, representing a huge but underappreciated burden on human health. One of these, the opportunistic fungus Cryptococcus neoformans, kills hundreds of thousands of patients annually, disproportionately affecting people in resource-limited areas. This yeast is distinguished from other pathogenic fungi by a polysaccharide capsule that is displayed on the cell surface. The capsule consists of two complex polysaccharide polymers: a mannan substituted with xylose and glucuronic acid, and a galactan with galactomannan side chains that bear variable amounts of glucuronic acid and xylose. The cell wall, with which the capsule is associated, is a matrix of alpha and beta glucans, chitin, chitosan, and mannoproteins. In this review, we focus on synthesis of the wall and capsule, both of which are critical for the ability of this microbe to cause disease and are distinct from structures found in either model yeasts or the mammals afflicted by this infection. Significant research effort over the last few decades has been applied to defining the synthetic machinery of these two structures, including nucleotide sugar metabolism and transport, glycosyltransferase activities, polysaccharide export, and assembly and association of structural elements. Discoveries in this area have elucidated fundamental biology and may lead to novel targets for antifungal therapy. In this review, we summarize the progress made in this challenging and fascinating area, and outline future research questions.
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Affiliation(s)
- Zhuo A Wang
- Department of Molecular Microbiology, Washington University School of Medicine, 660 South Euclid Avenue, Saint Louis, MO, USA
| | - Lucy X Li
- Department of Molecular Microbiology, Washington University School of Medicine, 660 South Euclid Avenue, Saint Louis, MO, USA
| | - Tamara L Doering
- Department of Molecular Microbiology, Washington University School of Medicine, 660 South Euclid Avenue, Saint Louis, MO, USA
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Involvement of the capsular GalXM-induced IL-17 cytokine in the control of Cryptococcus neoformans infection. Sci Rep 2018; 8:16378. [PMID: 30401972 PMCID: PMC6219535 DOI: 10.1038/s41598-018-34649-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 10/22/2018] [Indexed: 12/22/2022] Open
Abstract
Cryptococcus neoformans is an opportunistic fungus that can cause lethal brain infections in immunosuppressed individuals. Infection usually occurs via the inhalation of a spore or desiccated yeast which can then disseminate from the lung to the brain and other tissues. Dissemination and disease is largely influence by the production of copious amounts of cryptococcal polysaccharides, both which are secreted to the extracellular environment or assembled into a thick capsule surrounding the cell body. There are two important polysaccharides: glucuronoxylomannan (GXM) and galactoxylomannan, also called as glucuronoxylomanogalactan (GXMGal or GalXM). Although GXM is more abundant, GalXM has a more potent modulatory effect. In the present study, we show that GalXM is a potent activator of murine dendritic cells, and when co-cultured with T cells, induces a Th17 cytokine response. We also demonstrated that treating mice with GalXM prior to infection with C. neoformans protects from infection, and this phenomenon is dependent on IL-6 and IL-17. These findings help us understand the immune biology of capsular polysaccharides in fungal pathogenesis.
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Abstract
Cryptococcus neoformans is the causative agent of cryptococcosis, a devastating fungal disease that affects thousands of individuals worldwide. This fungus has the capacity to survive inside phagocytic cells, which contributes to persistence of infection and dissemination. One of the major antimicrobial mechanisms of host phagocytes is to acidify the phagosomal compartment after ingestion of microbes. This study shows that the capsule of C. neoformans can interfere with full phagosomal acidification by serving as a buffer. Phagosomal acidification is a critical cellular mechanism for the inhibition and killing of ingested microbes by phagocytic cells. The acidic environment activates microbicidal proteins and creates an unfavorable environment for the growth of many microbes. Consequently, numerous pathogenic microbes have developed strategies for countering phagosomal acidification through various mechanisms that include interference with phagosome maturation. The human-pathogenic fungus Cryptococcus neoformans resides in acidic phagosomes after macrophage ingestion that actually provides a favorable environment for replication, since the fungus replicates faster at acidic pH. We hypothesized that the glucuronic acid residues in the capsular polysaccharide had the capacity to affect phagosomal acidity through their acid-base properties. A ratiometric fluorescence comparison of imaged phagosomes containing C. neoformans to phagosomes containing beads showed that the latter were significantly more acidic. Similarly, phagosomes containing nonencapsulated C. neoformans cells were more acidic than those containing encapsulated cells. Acid-base titrations of isolated C. neoformans polysaccharide revealed that it behaves as a weak acid with maximal buffering capacity around pH 4 to 5. We interpret these results as indicating that the glucuronic acid residues in the C. neoformans capsular polysaccharide can buffer phagosomal acidification. Interference with phagosomal acidification represents a new function for the cryptococcal capsule in virulence and suggests the importance of considering the acid-base properties of microbial capsules in the host-microbe interaction for other microbes with charged residues in their capsules. IMPORTANCECryptococcus neoformans is the causative agent of cryptococcosis, a devastating fungal disease that affects thousands of individuals worldwide. This fungus has the capacity to survive inside phagocytic cells, which contributes to persistence of infection and dissemination. One of the major antimicrobial mechanisms of host phagocytes is to acidify the phagosomal compartment after ingestion of microbes. This study shows that the capsule of C. neoformans can interfere with full phagosomal acidification by serving as a buffer.
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A glucuronoxylomannan-like glycan produced by Trichosporon mucoides. Fungal Genet Biol 2018; 121:46-55. [PMID: 30268928 DOI: 10.1016/j.fgb.2018.09.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 08/27/2018] [Accepted: 09/26/2018] [Indexed: 01/06/2023]
Abstract
Trichosporon asahii shares with Cryptococcus species the ability to produce glucuronoxylomannan (GXM), an immunomodulatory fungal polysaccharide. The ability of other opportunistic species of Trichosporon to produce GXM-like polysaccharides is unknown. In this study, we observed that T. mucoides was less pathogenic than T. asahii in an infection model of Galleria mellonella and asked whether this difference was related to the characteristics of GXM-like molecules. Compositional analysis of samples obtained from both pathogens indicated that the components of GXM (mannose, xylose and glucuronic acid) were, in fact, detected in T. mucoides and T. asahii glycans. The identification of the T. mucoides glycan as a GXM-like molecule was confirmed by its reactivity with a monoclonal antibody raised to cryptococcal GXM and incorporation of the glycan into the cell surface of an acapsular mutant of C. neoformans. T. mucoides and T. asahii glycans differed in molecular dimensions. The antibody to cryptococcal GXM recognized T. mucoides yeast forms less efficiently than T. asahii cells. Experiments with animal cells revealed that the T. mucoides glycan manifested antiphagocytic properties. Comparative phagocytosis assays revealed that T. mucoides and T. asahii were similarly recognized by macrophages. However, fungal association with the phagocytes did not depend on the typical receptors of cryptococcal GXM, as concluded from assays using macrophages obtained from Tlr2-/- and Cd14-/- knockout mice. These results add T. mucoides to the list of fungal pathogens producing GXM-like glycans, but also indicate a high functional diversity of this major fungal immunogen.
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Casadevall A, Coelho C, Cordero RJB, Dragotakes Q, Jung E, Vij R, Wear MP. The capsule of Cryptococcus neoformans. Virulence 2018; 10:822-831. [PMID: 29436899 PMCID: PMC6779390 DOI: 10.1080/21505594.2018.1431087] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The capsule of Cryptococcus neoformans is its dominant virulence factor and plays a key role in the biology of this fungus. In this essay, we focus on the capsule as a cellular structure and note the limitations inherent in the current methodologies available for its study. Given that no single method can provide the structure of the capsule, our notions of what is the cryptococcal capsule must be arrived at by synthesizing information gathered from very different methodological approaches including microscopy, polysaccharide chemistry and physical chemistry of macromolecules. The emerging picture is one of a carefully regulated dynamic structure that is constantly rearranged as a response to environmental stimulation and cellular replication. In the environment, the capsule protects the fungus against desiccation and phagocytic predators. In animal hosts the capsule functions in both offensive and defensive modes, such that it interferes with immune responses while providing the fungal cell with a defensive shield that is both antiphagocytic and capable of absorbing microbicidal oxidative bursts from phagocytic cells. Finally, we delineate a set of unsolved problems in the cryptococcal capsule field that could provide fertile ground for future investigations.
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Affiliation(s)
- Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Carolina Coelho
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Radames J B Cordero
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Quigly Dragotakes
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Eric Jung
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Raghav Vij
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Maggie P Wear
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
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Camacho E, Casadevall A. Cryptococcal Traits Mediating Adherence to Biotic and Abiotic Surfaces. J Fungi (Basel) 2018; 4:jof4030088. [PMID: 30060601 PMCID: PMC6162697 DOI: 10.3390/jof4030088] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 07/25/2018] [Accepted: 07/27/2018] [Indexed: 01/22/2023] Open
Abstract
Several species in the genus Cryptococcus are facultative intracellular pathogens capable of causing disease associated with high mortality and morbidity in humans. These fungi interact with other organisms in the soil, and these interactions may contribute to the development of adaptation mechanisms that function in virulence by promoting fungal survival in animal hosts. Fungal adhesion molecules, also known as adhesins, have been classically considered as cell-surface or secreted proteins that play critical roles in microbial pathogenesis or in biofilm formation as structural components. Pathogenic Cryptococcus spp. differ from other pathogenic yeasts in having a polysaccharide capsule that covers the cell wall surface and precludes interactions of those structures with host cell receptors. Hence, pathogenic Cryptococcus spp. use unconventional tools for surface attachment. In this essay, we review the unique traits and mechanisms favoring adhesion of Cryptococcus spp. to biotic and abiotic surfaces. Knowledge of the traits that mediate adherence could be exploited in the development of therapeutic, biomedical, and/or industrial products.
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Affiliation(s)
- Emma Camacho
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, 615 N Wolfe St Room E5132, Baltimore, MD 21205, USA.
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, 615 N Wolfe St Room E5132, Baltimore, MD 21205, USA.
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Rodrigues J, Ramos CL, Frases S, Godinho RMDC, Fonseca FL, Rodrigues ML. Lack of chitin synthase genes impacts capsular architecture and cellular physiology in Cryptococcus neoformans. Cell Surf 2018; 2:14-23. [PMID: 32743128 PMCID: PMC7389344 DOI: 10.1016/j.tcsw.2018.05.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/21/2018] [Accepted: 05/25/2018] [Indexed: 02/06/2023] Open
Abstract
Cryptococcus neoformans mutants lacking each of the eight putative chitin synthase genes (CHS) have been previously generated. However, it is still unclear how deletion of chitin synthase genes affects the cryptococcal capsule. Since the connections between chitin metabolism and capsular polysaccharides in C. neoformans are numerous, we analyzed the effects of deletion of CHS genes on capsular and capsule-related structures of C. neoformans. CHS deletion affected capsular morphology in multiple ways, as determined by scanning electron microscopy and immunofluorescence analysis. Molecular diameter, serological reactivity and export of capsular polysaccharide were also affected in most of the chsΔ mutants, but the most prominent alterations were observed in the chs3Δ strain. C. neoformans cells lacking CHS genes also had altered formation of extracellular vesicles and variable chitinase activity under stress conditions. These results reveal previously unknown functions of CHS genes that greatly impact the physiology of C. neoformans.
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Affiliation(s)
- Jessica Rodrigues
- Instituto de Microbiologia Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Caroline L Ramos
- Instituto de Microbiologia Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Susana Frases
- Instituto de Biofísica Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rodrigo M da C Godinho
- Instituto de Microbiologia Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fernanda L Fonseca
- Centro de Desenvolvimento Tecnológico em Saúde (CDTS) da Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil
| | - Marcio L Rodrigues
- Instituto de Microbiologia Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Carlos Chagas (ICC), Fundação Oswaldo Cruz (Fiocruz), Curitiba, PR, Brazil
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A Predicted Mannoprotein Participates in Cryptococcus gattii Capsular Structure. mSphere 2018; 3:3/2/e00023-18. [PMID: 29897877 PMCID: PMC5917426 DOI: 10.1128/msphere.00023-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 04/02/2018] [Indexed: 11/20/2022] Open
Abstract
The yeast-like pathogen Cryptococcus gattii is an etiological agent of cryptococcosis. The major cryptococcal virulence factor is the polysaccharide capsule, which is composed of glucuronoxylomannan (GXM), galactoxylomannan (GalXM), and mannoproteins (MPs). The GXM and GalXM polysaccharides have been extensively characterized; however, there is little information about the role of mannoproteins in capsule assembly and their participation in yeast pathogenicity. The present study characterized the function of a predicted mannoprotein from C. gattii, designated Krp1. Loss-of-function and gain-of-function mutants were generated, and phenotypes associated with the capsular architecture were evaluated. The null mutant cells were more sensitive to a cell wall stressor that disrupts beta-glucan synthesis. Also, these cells displayed increased GXM release to the culture supernatant than the wild-type strain did. The loss of Krp1 influenced cell-associated cryptococcal polysaccharide thickness and phagocytosis by J774.A1 macrophages in the early hours of interaction, but no difference in virulence in a murine model of cryptococcosis was observed. In addition, recombinant Krp1 was antigenic and differentially recognized by serum from an individual with cryptococcosis, but not with serum from an individual with candidiasis. Taken together, these results indicate that C. gattii Krp1 is important for the cell wall structure, thereby influencing capsule assembly, but is not essential for virulence in vivoIMPORTANCECryptococcus gattii has the ability to escape from the host's immune system through poorly understood mechanisms and can lead to the death of healthy individuals. The role of mannoproteins in C. gattii pathogenicity is not completely understood. The present work characterized a protein, Kpr1, that is essential for the maintenance of C. gattii main virulence factor, the polysaccharide capsule. Our data contribute to the understanding of the role of Kpr1 in capsule structuring, mainly by modulating the distribution of glucans in C. gattii cell wall.
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Barcellos VA, Martins LMS, Fontes ACL, Reuwsaat JCV, Squizani ED, de Sousa Araújo GR, Frases S, Staats CC, Schrank A, Kmetzsch L, Vainstein MH. Genotypic and Phenotypic Diversity of Cryptococcus gattii VGII Clinical Isolates and Its Impact on Virulence. Front Microbiol 2018; 9:132. [PMID: 29467743 PMCID: PMC5808156 DOI: 10.3389/fmicb.2018.00132] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 01/19/2018] [Indexed: 12/11/2022] Open
Abstract
The Cryptococcus gattii species complex harbors the main etiological agents of cryptococcosis in immunocompetent patients. C. gattii molecular type VGII predominates in the north and northeastern regions of Brazil, leading to high morbidity and mortality rates. C. gattii VGII isolates have a strong clinical relevance and phenotypic variations. These phenotypic variations among C. gattii species complex isolates suggest that some strains are more virulent than others, but little information is available related to the pathogenic properties of those strains. In this study, we analyzed some virulence determinants of C. gattii VGII strains (CG01, CG02, and CG03) isolated from patients in the state of Piauí, Brazil. The C. gattii R265 VGIIa strain, which was isolated from the Vancouver outbreak, differed from C. gattii CG01, CG02 and CG03 isolates (also classified as VGII) when analyzed the capsular dimensions, melanin production, urease activity, as well as the glucuronoxylomannan (GXM) secretion. Those differences directly reflected in their virulence potential. In addition, CG02 displayed higher virulence compared to R265 (VGIIa) strain in a cryptococcal murine model of infection. Lastly, we examined the genotypic diversity of these strains through Multilocus Sequence Type (MLST) and one new subtype was described for the CG02 isolate. This study confirms the presence and the phenotypic and genotypic diversity of highly virulent strains in the Northeast region of Brazil.
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Affiliation(s)
- Vanessa A Barcellos
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Liline M S Martins
- Laboratório de Imunogenética e Biologia Molecular, Universidade Federal do Piauí, Teresina, Brazil.,Faculdade de Ciências Médicas da Universidade Estadual do Piauí, Teresina, Brazil
| | - Alide C L Fontes
- Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Julia C V Reuwsaat
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Eamim D Squizani
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Glauber R de Sousa Araújo
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Susana Frases
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Charley C Staats
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Departamento de Biologia Molecular e Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Augusto Schrank
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Departamento de Biologia Molecular e Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Livia Kmetzsch
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Departamento de Biologia Molecular e Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Marilene H Vainstein
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Departamento de Biologia Molecular e Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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