1
|
Al-Huthaifi AM, Radman BA, Al-Alawi AA, Mahmood F, Liu TB. Mechanisms and Virulence Factors of Cryptococcus neoformans Dissemination to the Central Nervous System. J Fungi (Basel) 2024; 10:586. [PMID: 39194911 DOI: 10.3390/jof10080586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2024] [Revised: 07/31/2024] [Accepted: 08/15/2024] [Indexed: 08/29/2024] Open
Abstract
Cryptococcosis is a prevalent fungal infection of the central nervous system (CNS) caused by Cryptococcus neoformans, a yeast with a polysaccharide capsule in the basidiomycete group. Normally, C. neoformans infects the respiratory tract and then breaches the blood-brain barrier (BBB), leading to meningitis or meningoencephalitis, which leads to hundreds of thousands of deaths each year. Although the mechanism by which C. neoformans infiltrates the BBB to invade the brain has yet to be fully understood, research has revealed that C. neoformans can cross the BBB using transcellular penetration, paracellular traversal, and infected phagocytes (the "Trojan horse" mechanism). The secretion of multiple virulence factors by C. neoformans is crucial in facilitating the spread of infection after breaching the BBB and causing brain infections. Extensive research has shown that various virulence factors play a significant role in the dissemination of infection beyond the lungs. This review explores the mechanisms of C. neoformans entering the CNS and explains how it bypasses the BBB. Additionally, it aims to understand the interplay between the regulatory mechanisms and virulence factors of C. neoformans.
Collapse
Affiliation(s)
| | - Bakeel A Radman
- Cancer Center, Integrated Hospital of Traditional Chinese Medicine, Southern Medical University, Guangzhou 510315, China
| | | | - Fawad Mahmood
- Medical Research Institute, Southwest University, Chongqing 400715, China
| | - Tong-Bao Liu
- Medical Research Institute, Southwest University, Chongqing 400715, China
- Jinfeng Laboratory, Chongqing 401329, China
- Engineering Research Center for Cancer Biomedical and Translational Medicine, Southwest University, Chongqing 400715, China
| |
Collapse
|
2
|
Tang S, Hao R, Liu X, He H, Tian Y, Jing T, Liu Z, Xu Y, Li X. Global trends in Cryptococcus and its interactions with the host immune system: a bibliometric analysis. Front Immunol 2024; 15:1397338. [PMID: 38774865 PMCID: PMC11106374 DOI: 10.3389/fimmu.2024.1397338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Accepted: 04/18/2024] [Indexed: 05/24/2024] Open
Abstract
Objectives This manuscript undertakes a systematic examination of the research landscape concerning global Cryptococcus species and their dynamism with the host immune system spanning the past decade. It furnishes a detailed survey of leading knowledge institutions and critical focal points in this area, utilizing bibliometric analysis. Methods VOSviewer and CiteSpace software platforms were employed to systematically analyze and graphically depict the relevant literature indexed in the WoSCC database over the preceding ten years. Results In the interval between October 1, 2013, and October 1, 2023, a corpus of 795 publications was amassed. The primary research institutions involved in this study include Duke University, the University of Minnesota, and the University of Sydney. The leading trio of nations, in terms of publication volume, comprises the United States, China, and Brazil. Among the most prolific authors are Casadevall, Arturo; Wormley, Floyd L., Jr.; and Olszewski, Michal A., with the most highly cited author being Perfect, Jr. The most esteemed journal is Mbio, while Infection and Immunity commands the highest citation frequency, and the Journal of Clinical Microbiology boasts the most significant impact factor. Present research foci encompass the intricate interactions between Cryptococcus pathogenesis and host immunity, alongside immune mechanisms, complications, and immunotherapies. Conclusion This represents the first exhaustive scholarly review and bibliometric scrutiny of the evolving landscapes in Cryptococcus research and its interactions with the host immune system. The analyses delineated herein provide insights into prevailing research foci and trajectories, thus furnishing critical directions for subsequent inquiries in this domain.
Collapse
Affiliation(s)
- Shiqin Tang
- School of Clinical Medicine, The Hebei University of Engineering, Handan, Hebei, China
| | - Ruiying Hao
- School of Clinical Medicine, The Hebei University of Engineering, Handan, Hebei, China
| | - Xin Liu
- Handan Stomatological Hospital, Endodontics, Handan, Hebei, China
| | - Huina He
- School of Clinical Medicine, The Hebei University of Engineering, Handan, Hebei, China
| | - Yanan Tian
- School of Clinical Medicine, The Hebei University of Engineering, Handan, Hebei, China
| | - Tingting Jing
- Department of Dermatology, Affiliated Hospital of Hebei University of Engineering, Handan, Hebei, China
| | - Zhao Liu
- Department of Dermatology, Affiliated Hospital of Hebei University of Engineering, Handan, Hebei, China
| | - Yanyan Xu
- Department of Dermatology, Affiliated Hospital of Hebei University of Engineering, Handan, Hebei, China
| | - Xiaojing Li
- School of Clinical Medicine, The Hebei University of Engineering, Hebei Key Laboratory of Immunological Dermatology, Handan, Hebei, China
| |
Collapse
|
3
|
Qu J, Lv X. Cryptococcal meningitis in apparently immunocompetent patients. Crit Rev Microbiol 2024; 50:76-86. [PMID: 36562731 DOI: 10.1080/1040841x.2022.2159786] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022]
Abstract
Cryptococcal meningitis (CM) is an invasive fungal disease that currently poses a threat to human health worldwide, with high morbidity and mortality, particularly in immunocompromised patients. Although CM mainly occurs in HIV-positive patients and other immunocompromised patients, it is also increasingly seen in seemingly immunocompetent hosts. The clinical characteristics of CM between immunocompromised and immunocompetent populations are different. However, few studies have focussed on CM in immunocompetent individuals. This review summarizes the clinical characteristics of apparently immunocompetent CM patients in terms of aetiology, immune pathogenesis, clinical presentation, laboratory data, imaging findings, treatment strategies and prognosis. It is of great significance to further understand the disease characteristics of CM, explore new treatment strategies and improve the prognosis of CM in immunocompetent individuals.
Collapse
Affiliation(s)
- Junyan Qu
- Center of Infectious Disease, West China Hospital, Sichuan University, Chengdu, China
| | - Xiaoju Lv
- Center of Infectious Disease, West China Hospital, Sichuan University, Chengdu, China
| |
Collapse
|
4
|
Carvalho JHDS, Nascimento JKC, Silva KGV, Silveira Neto S, Macedo ATD, Lima França H, Ferreira LDR, Silva RDS, Sa JC, Ramos DG, Marques DDAV, Furst C, Santos DA, Santos JRA, Holanda RA. Yeast-amoeba interaction influences murine cryptococcosis. Microbes Infect 2023; 25:105153. [PMID: 37244475 DOI: 10.1016/j.micinf.2023.105153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 05/21/2023] [Accepted: 05/22/2023] [Indexed: 05/29/2023]
Abstract
The virulence of Cryptococcus spp. is modulated in the natural environment through interaction with abiotic and biotic factors, and this can occasionally have implications for the progression of cryptococcosis in mammals. Hence, we evaluated whether the prior interaction of highly virulent Cryptococcus gattii strain R265 with Acanthamoeba castellanii influenced the progression of cryptococcosis. The influence of the capsule on endocytosis was evaluated using amoeba and yeast morphometrics. Mice were intratracheally infected with yeast re-isolated from the amoeba (Interaction), yeast without prior contact with the amoeba (Non-Interaction), or sterile phosphate-buffered saline (SHAM). Morbidity signs and symptoms were monitored during the survival curve, while cytokine and fungal burden measurements and histopathological analysis were performed on the 10th day post infection. Morbidity and mortality parameters in experimental cryptococcosis were influenced by the prior interaction of yeast with amoeba, which led to phenotypic changes in the cryptococcal cells, polysaccharide secretion, and their tolerance to oxidative stress. Our results suggest that a prior yeast-amoeba interaction modulates yeast virulence, which is associated with a greater tolerance to oxidative stress related to the exo-polysaccharide content and influences the progression of cryptococcal infection.
Collapse
Affiliation(s)
| | | | | | - Sebastiao Silveira Neto
- Laboratório de Biologia Molecular de Microrganismos Patogênicos, Universidade CEUMA, São Luís, Maranhão, Brazil
| | | | - Hermeson Lima França
- Laboratório de Biologia Molecular de Microrganismos Patogênicos, Universidade CEUMA, São Luís, Maranhão, Brazil
| | - Larissa Dos Reis Ferreira
- Laboratório de Biologia Molecular de Microrganismos Patogênicos, Universidade CEUMA, São Luís, Maranhão, Brazil
| | - Rayssa de Sousa Silva
- Laboratório de Biologia Molecular de Microrganismos Patogênicos, Universidade CEUMA, São Luís, Maranhão, Brazil
| | - Joicy Cortez Sa
- Laboratório de Imunologia, Universidade CEUMA, São Luís, Maranhão, Brazil
| | - Diego Gomes Ramos
- Laboratório Integrado de Biotecnologia Aplicada, Universidade de Pernambuco, Recife, Pernambuco, Brazil
| | | | - Cinthia Furst
- Departamento de Patologia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo, Brazil
| | - Daniel Assis Santos
- Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | | | - Rodrigo Assuncao Holanda
- Laboratório de Biologia Molecular de Microrganismos Patogênicos, Universidade CEUMA, São Luís, Maranhão, Brazil.
| |
Collapse
|
5
|
Liu Y, Zhang Y, Zhao X, Lu W, Zhong Y, Fu YV. Antifungal Peptide SP1 Damages Polysaccharide Capsule of Cryptococcus neoformans and Enhances Phagocytosis of Macrophages. Microbiol Spectr 2023; 11:e0456222. [PMID: 36916981 PMCID: PMC10100895 DOI: 10.1128/spectrum.04562-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 02/22/2023] [Indexed: 03/16/2023] Open
Abstract
Cryptococcus neoformans is a fungal pathogen which causes nearly half a million deaths worldwide each year. Under host-relevant conditions, it produces a characteristic polysaccharide capsule. The polysaccharide capsule is one of the main virulence factors of C. neoformans, which involves antiphagocytosis and immune responses of the host to cause a lack of an immune. Meanwhile, the polysaccharide capsule is a promising drug target because of the absence of analogs in the host. Here, we demonstrate that antifungal peptide SP1, which is derived from the N terminus of Saccharomyces cerevisiae GAPDH (glyceraldehyde-3-phosphate dehydrogenase), disrupts the polysaccharide capsule of C. neoformans H99. The mechanism is possibly due to the interaction of SP1 with glucuronoxylomannan (GXM). Disruption of the polysaccharide capsule enhances the adhesion and phagocytosis of C. neoformans H99 by macrophages and reduces the replication of C. neoformans H99 within macrophages. Additionally, SP1 exhibits antifungal activity against cryptococcal biofilms associated with the capsular polysaccharides. These findings suggest the potential of SP1 as a drug candidate for the treatment of cryptococcosis. IMPORTANCE C. neoformans is an opportunistic pathogen that causes invasive infections with a high mortality rate. Currently, the clinical drugs available for the treatment of cryptococcosis are limited to amphotericin B, azoles, and flucytosine. Amphotericin is nephrotoxic, and the widespread use of azoles and 5-flucytosine has led to a rapid development of drug resistance in C. neoformans. There is an urgent need to develop new and effective anticryptococcal drugs. Targeting virulence factors is a novel strategy for developing antifungal drugs. The antifungal peptide SP1 is capable of disrupting the polysaccharide capsule, which is a principal virulence factor of C. neoformans. Studying the mechanism by which SP1 damages the polysaccharide capsule and investigating the potential benefits of SP1 in removing C. neoformans from the host provides baseline data to develop a therapeutic strategy against refractory cryptococcal infections. This strategy would involve both inhibiting virulence factors and directly killing C. neoformans cells.
Collapse
Affiliation(s)
- Yan Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Yang Zhang
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Xi Zhao
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Weilai Lu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Yuxin Zhong
- Department of Pancreatic and Gastric Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yu V. Fu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| |
Collapse
|
6
|
Yang C, Huang Y, Zhou Y, Zang X, Deng H, Liu Y, Shen D, Xue X. Cryptococcus escapes host immunity: What do we know? Front Cell Infect Microbiol 2022; 12:1041036. [PMID: 36310879 PMCID: PMC9606624 DOI: 10.3389/fcimb.2022.1041036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 09/30/2022] [Indexed: 11/13/2022] Open
Abstract
Cryptococcus is an invasive fungus that seriously endangers human life and health, with a complex and well-established immune-escaping mechanism that interferes with the function of the host immune system. Cryptococcus can attenuate the host’s correct recognition of the fungal antigen and escape the immune response mediated by host phagocytes, innate lymphoid cells, T lymphocytes, B lymphocytes with antibodies, and peripheral cytokines. In addition, the capsule, melanin, dormancy, Titan cells, biofilm, and other related structures of Cryptococcus are also involved in the process of escaping the host’s immunity, as well as enhancing the ability of Cryptococcus to infect the host.
Collapse
Affiliation(s)
- Chen Yang
- Department of Laboratory Medicine, the First Medical Centre, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China
| | - Yemei Huang
- Department of Respiratory and Critical Care, Beijing Shijitan Hospital, Capital Medical University, Peking University Ninth School of Clinical Medicine, Beijing, China
| | - Yangyu Zhou
- Department of Respiratory and Critical Care, Beijing Shijitan Hospital, Capital Medical University, Peking University Ninth School of Clinical Medicine, Beijing, China
| | - Xuelei Zang
- Department of Respiratory and Critical Care, Beijing Shijitan Hospital, Capital Medical University, Peking University Ninth School of Clinical Medicine, Beijing, China
| | - Hengyu Deng
- School of Clinical Medicine, Weifang Medical University, Weifang, China
| | - Yitong Liu
- Department of Respiratory and Critical Care, Beijing Shijitan Hospital, Capital Medical University, Peking University Ninth School of Clinical Medicine, Beijing, China
| | - Dingxia Shen
- Department of Laboratory Medicine, the First Medical Centre, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China
- *Correspondence: Dingxia Shen, ; Xinying Xue,
| | - Xinying Xue
- Department of Respiratory and Critical Care, Beijing Shijitan Hospital, Capital Medical University, Peking University Ninth School of Clinical Medicine, Beijing, China
- School of Clinical Medicine, Weifang Medical University, Weifang, China
- *Correspondence: Dingxia Shen, ; Xinying Xue,
| |
Collapse
|
7
|
Pathogenesis of Fungal Infections in the Central Nervous System: Host and Pathogen Factors in Neurotropism. CURRENT FUNGAL INFECTION REPORTS 2022. [DOI: 10.1007/s12281-022-00444-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
8
|
Bagwe P, Bajaj L, Gala RP, D‘Souza MJ, Zughaier SM. Assessment of In Vitro Immunostimulatory Activity of an Adjuvanted Whole-Cell Inactivated Neisseria gonorrhoeae Microparticle Vaccine Formulation. Vaccines (Basel) 2022; 10:983. [PMID: 35891147 PMCID: PMC9320116 DOI: 10.3390/vaccines10070983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/13/2022] [Accepted: 06/17/2022] [Indexed: 02/04/2023] Open
Abstract
The emergence of drug-resistant gonorrhea infections worldwide combined with the lack of a vaccine is alarming. We prepared a novel microparticulate (MP) vaccine formulation using whole-cell inactivated Neisseria gonorrhoeae as the vaccine antigen, with Alum and AddaVax™ as vaccine adjuvants. The adjuvanted vaccine MP formulation was assessed for in vitro immunostimulatory activity, autophagy, and antigen presentation ability. The data shows that the adjuvanted gonococci vaccine MP enhanced autophagy induction in antigen presenting cells (APCs) compared to gonococci vaccine MP without adjuvants, which is important for enhancing antigen presentation. In addition, the adjuvanted vaccine formulation increased the surface expression of antigen presenting molecules MHCI and MHCII as well as co-stimulatory molecules CD40 and CD86 on the surface of dendritic cells. In addition, the gonococci vaccine microparticles at lower doses did not significantly increase the expression of the death receptor CD95 in APCs, which when elevated leads to suboptimal antigen presentation and reduced immune responses. The adjuvanted whole-cell inactivated gonococci microparticle vaccine formulation enhanced antigen uptake, processing, and antigen presentation.
Collapse
Affiliation(s)
- Priyal Bagwe
- Vaccine Nanotechnology Laboratory, Center for Drug Delivery Research, College of Pharmacy, Mercer University, Atlanta, GA 30341, USA; (P.B.); (L.B.); (M.J.D.)
| | - Lotika Bajaj
- Vaccine Nanotechnology Laboratory, Center for Drug Delivery Research, College of Pharmacy, Mercer University, Atlanta, GA 30341, USA; (P.B.); (L.B.); (M.J.D.)
| | - Rikhav P. Gala
- Fraunhofer USA, Center Mid-Atlantic, Biotechnology Division, 9, Innovation Way, Newark, DE 19011, USA;
| | - Martin J. D‘Souza
- Vaccine Nanotechnology Laboratory, Center for Drug Delivery Research, College of Pharmacy, Mercer University, Atlanta, GA 30341, USA; (P.B.); (L.B.); (M.J.D.)
| | - Susu M. Zughaier
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha P.O. Box 2731, Qatar
| |
Collapse
|
9
|
Oliveira-Brito PKM, de Campos GY, Guimarães JG, Serafim da Costa L, Silva de Moura E, Lazo-Chica JE, Roque-Barreira MC, da Silva TA. Adjuvant Curdlan Contributes to Immunization against Cryptococcus gattii Infection in a Mouse Strain-Specific Manner. Vaccines (Basel) 2022; 10:vaccines10040620. [PMID: 35455369 PMCID: PMC9030172 DOI: 10.3390/vaccines10040620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 04/05/2022] [Accepted: 04/07/2022] [Indexed: 02/06/2023] Open
Abstract
The low efficacy and side effects associated with antifungal agents have highlighted the importance of developing immunotherapeutic approaches to treat Cryptococcus gattii infection. We developed an immunization strategy that uses selective Dectin-1 agonist as an adjuvant. BALB/c or C57BL/6 mice received curdlan or β-glucan peptide (BGP) before immunization with heat-killed C. gattii, and the mice were infected with viable C. gattii on day 14 post immunization and euthanized 14 days after infection. Adjuvant curdlan restored pulmonary tumor necrosis factor- α (TNF-α) levels, as induced by immunization with heat-killed C. gattii. The average area and relative frequency of C. gattii titan cells in the lungs of curdlan-treated BALB/c mice were reduced. However, this did not reduce the pulmonary fungal burden or decrease the i0,nflammatory infiltrate in the pulmonary parenchyma of BALB/c mice. Conversely, adjuvant curdlan induced high levels of interferon-γ (IFN-γ) and interleukin (IL)-10 and decreased the C. gattii burden in the lungs of C57BL/6 mice, which was not replicated in β-glucan peptide-treated mice. The adjuvant curdlan favors the control of C. gattii infection depending on the immune response profile of the mouse strain. This study will have implications for developing new immunotherapeutic approaches to treat C. gattii infection.
Collapse
Affiliation(s)
- Patrícia Kellen Martins Oliveira-Brito
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto 14049-900, SP, Brazil; (P.K.M.O.-B.); (G.Y.d.C.); (J.G.G.); (E.S.d.M.); (M.C.R.-B.)
| | - Gabriela Yamazaki de Campos
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto 14049-900, SP, Brazil; (P.K.M.O.-B.); (G.Y.d.C.); (J.G.G.); (E.S.d.M.); (M.C.R.-B.)
| | - Júlia Garcia Guimarães
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto 14049-900, SP, Brazil; (P.K.M.O.-B.); (G.Y.d.C.); (J.G.G.); (E.S.d.M.); (M.C.R.-B.)
| | - Letícia Serafim da Costa
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 14049-900, SP, Brazil;
| | - Edanielle Silva de Moura
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto 14049-900, SP, Brazil; (P.K.M.O.-B.); (G.Y.d.C.); (J.G.G.); (E.S.d.M.); (M.C.R.-B.)
| | - Javier Emílio Lazo-Chica
- Institute of Natural and Biological Sciences, Federal University of Triângulo Mineiro, Uberaba 38025-189, MG, Brazil;
| | - Maria Cristina Roque-Barreira
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto 14049-900, SP, Brazil; (P.K.M.O.-B.); (G.Y.d.C.); (J.G.G.); (E.S.d.M.); (M.C.R.-B.)
| | - Thiago Aparecido da Silva
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto 14049-900, SP, Brazil; (P.K.M.O.-B.); (G.Y.d.C.); (J.G.G.); (E.S.d.M.); (M.C.R.-B.)
- Thiago Aparecido da Silva, Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, Ribeirão Preto 14049-900, SP, Brazil
- Correspondence: or ; Tel.: +55-16-3315-3049
| |
Collapse
|
10
|
Rathore SS, Sathiyamoorthy J, Lalitha C, Ramakrishnan J. A holistic review on Cryptococcus neoformans. Microb Pathog 2022; 166:105521. [DOI: 10.1016/j.micpath.2022.105521] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 04/06/2022] [Accepted: 04/06/2022] [Indexed: 12/21/2022]
|
11
|
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.
Collapse
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,
| |
Collapse
|
12
|
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: 11] [Impact Index Per Article: 5.5] [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.
Collapse
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
| |
Collapse
|
13
|
Camilli G, Blagojevic M, Naglik JR, Richardson JP. Programmed Cell Death: Central Player in Fungal Infections. Trends Cell Biol 2020; 31:179-196. [PMID: 33293167 DOI: 10.1016/j.tcb.2020.11.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 11/08/2020] [Accepted: 11/11/2020] [Indexed: 12/26/2022]
Abstract
Fungal diseases contribute significantly to morbidity and mortality in humans. Although recent research has improved our understanding of the complex and dynamic interplay that occurs between pathogenic fungi and the human host, much remains to be elucidated concerning the molecular mechanisms that drive fungal pathogenicity and host responses to fungal infections. In recent times, there has been a significant increase in studies investigating the immunological functions of microbial-induced host cell death. In addition, pathogens use many strategies to manipulate host cell death pathways to facilitate their survival and dissemination. This review will focus on the mechanisms of host programmed cell death that occur during opportunistic fungal infections, and explore how cell death pathways may affect immunity towards pathogenic fungi.
Collapse
Affiliation(s)
- Giorgio Camilli
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, London SE1 1UL, UK.
| | - Mariana Blagojevic
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, London SE1 1UL, UK
| | - Julian R Naglik
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, London SE1 1UL, UK
| | - Jonathan P Richardson
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, London SE1 1UL, UK
| |
Collapse
|
14
|
Apoptosis of vaginal epithelial cells in clinical samples from women with diagnosed bacterial vaginosis. Sci Rep 2020; 10:1978. [PMID: 32029862 PMCID: PMC7005030 DOI: 10.1038/s41598-020-58862-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 01/22/2020] [Indexed: 01/10/2023] Open
Abstract
Bacterial vaginosis (BV) is one of the most common vaginal infections among women of childbearing age. Gardnerella vaginalis (G. vaginalis) is a keystone microorganism present in more than 95% of all BV cases. The first step of the infection process in BV is mediated by interaction of microorganisms with epithelial cells (ECs). However, the role of these cells in BV pathogenesis is largely unknown. The present study aimed to investigate the vaginal EC response during BV. Twenty healthy women and 34 women with BV were enrolled in this study. The number of ECs in the vaginal swab was counted and analyzed for intracellular signals and apoptosis by flow cytometry. Cell damage was evaluated by lactate dehydrogenase assay. Compared to that in healthy donors, the percentage of exfoliated vaginal ECs was increased in women with BV, and an absence of neutrophils was observed in both groups. Activation signals, such as p-IκBα and c-Fos were unmodulated in the vaginal ECs of women with BV. Moreover, EC damage and apoptosis were significantly increased in patients with BV. Apoptosis was related to caspase-3 activation and the presence of G. vaginalis. This study provides the first evidence of a direct involvement of G. vaginalis in the apoptotic process of vaginal ECs during BV. This effect was mediated by caspase-3 activation, and G. vaginalis appeared to be one of causes for inducing EC apoptosis in BV. Hence, our findings suggest a possible explanation for the increased exfoliation of ECs in the vagina during BV.
Collapse
|
15
|
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.
Collapse
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
| |
Collapse
|
16
|
Decote-Ricardo D, LaRocque-de-Freitas IF, Rocha JDB, Nascimento DO, Nunes MP, Morrot A, Freire-de-Lima L, Previato JO, Mendonça-Previato L, Freire-de-Lima CG. Immunomodulatory Role of Capsular Polysaccharides Constituents of Cryptococcus neoformans. Front Med (Lausanne) 2019; 6:129. [PMID: 31275938 PMCID: PMC6593061 DOI: 10.3389/fmed.2019.00129] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 05/24/2019] [Indexed: 12/13/2022] Open
Abstract
Cryptococcosis is a systemic fungal infection caused by Cryptococcus neoformans. In immunocompetent patients, cryptococcal infection is often confined to the lungs. In immunocompromised individuals, C. neoformans may cause life-threatening illness, either from novel exposure or through reactivation of a previously acquired latent infection. For example, cryptococcal meningitis is a severe clinical disease that can manifest in people that are immunocompromised due to AIDS. The major constituents of the Cryptococcus polysaccharide capsule, glucuronoxylomannan (GXM), and galactoxylomannan (GalXM), also known as glucuronoxylomanogalactan (GXMGal), are considered the primary virulence factors of Cryptococcus. Despite the predominance of GXM in the polysaccharide capsule, GalXM has more robust immunomodulatory effects on host cellular immunity. This review summarizes current knowledge regarding host-Crytococcus neoformans interactions and the role of capsular polysaccharides in host immunomodulation. Future studies will likely facilitate a better understanding of the mechanisms involved in antigenic recognition and host immune response to C. neoformans and lead to the development of new therapeutic pathways for cryptococcal infection.
Collapse
Affiliation(s)
- Debora Decote-Ricardo
- Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, Brazil
| | | | - Juliana Dutra B Rocha
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Danielle O Nascimento
- Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, Brazil.,Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marise P Nunes
- Laboratório de Imunoparasitologia, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
| | - Alexandre Morrot
- Laboratório de Imunoparasitologia, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil.,Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Leonardo Freire-de-Lima
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Jose Osvaldo Previato
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Lucia Mendonça-Previato
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | |
Collapse
|
17
|
Previato JO, Vinogradov E, Maes E, Fonseca LM, Guerardel Y, Oliveira PAV, Mendonça-Previato L. Distribution of the O-acetyl groups and β-galactofuranose units in galactoxylomannans of the opportunistic fungus Cryptococcus neoformans. Glycobiology 2018; 27:582-592. [PMID: 27986834 DOI: 10.1093/glycob/cww127] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 12/09/2016] [Indexed: 01/07/2023] Open
Abstract
Galactoxylomannans (GalXMs) are a mixture of neutral and acidic capsular polysaccharides produced by the opportunistic fungus Cryptococcus neoformans that exhibit potent suppressive effects on the host immune system. Previous studies describing the chemical structure of C. neoformans GalXMs have reported species without O-acetyl substituents. Herein we describe that C. neoformans grown in capsule-inducing medium produces highly O-acetylated GalXMs. The location of the O-acetyl groups was determined by nuclear magnetic resonance (NMR) spectroscopy. In the neutral GalXM (NGalXM), 80% of 3-linked mannose (α-Manp) residues present in side chains are acetylated at the O-2 position. In the acidic GalXM also termed glucuronoxylomannogalactan (GXMGal), 85% of the 3-linked α-Manp residues are acetylated either in the O-2 (75%) or in the O-6 (25%) position, but O-acetyl groups are not present at both positions simultaneously. In addition, NMR spectroscopy and methylation analysis showed that β-galactofuranose (β-Galf) units are linked to O-2 and O-3 positions of nonbranched α-galactopyranose (α-Galp) units present in the GalXMs backbone chain. These findings highlight new structural features of C. neoformans GalXMs. Among these features, the high degree of O-acetylation is of particular interest, since O-acetyl group-containing polysaccharides are known to possess a range of immunobiological activities.
Collapse
Affiliation(s)
- Jose O Previato
- Laboratório de Glicobiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941902Rio de Janeiro, Brazil
| | | | - Emmanuel Maes
- Université Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle,F 59000Lille, France
| | - Leonardo M Fonseca
- Laboratório de Glicobiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941902Rio de Janeiro, Brazil
| | - Yann Guerardel
- Université Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle,F 59000Lille, France
| | - Priscila A V Oliveira
- Laboratório de Glicobiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941902Rio de Janeiro, Brazil
| | - Lucia Mendonça-Previato
- Laboratório de Glicobiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941902Rio de Janeiro, Brazil
| |
Collapse
|
18
|
Casadevall A, Coelho C, Alanio A. Mechanisms of Cryptococcus neoformans-Mediated Host Damage. Front Immunol 2018; 9:855. [PMID: 29760698 PMCID: PMC5936990 DOI: 10.3389/fimmu.2018.00855] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/06/2018] [Indexed: 01/22/2023] Open
Abstract
Cryptococcus neoformans is not usually considered a cytotoxic fungal pathogen but there is considerable evidence that this microbe can damage host cells and tissues. In this essay, we review the evidence that C. neoformans damages host cells and note that the mechanisms involved are diverse. We consider C. neoformans-mediated host damage at the molecular, cellular, tissue, and organism level. Direct mechanisms of cytotoxicity include lytic exocytosis, organelle dysfunction, phagolysosomal membrane damage, and cytoskeletal alterations. Cytotoxicity contributes to pathogenesis by interfering with immune effector cell function and disrupting endothelial barriers thus allowing dissemination. When C. neoformans-mediated and immune-mediated host damage is sufficient to affect homeostasis, cryptococcosis occurs at the organism level.
Collapse
Affiliation(s)
- Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, MD, United States
| | - Carolina Coelho
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, MD, United States
| | - Alexandre Alanio
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, MD, United States
- Institut Pasteur, Molecular Mycology Unit, CNRS UMR2000, Paris, France
- Laboratoire de Parasitologie-Mycologie, Hôpital Saint-Louis, Groupe Hospitalier Lariboisière, Saint-Louis, Fernand Widal, Assistance Publique-Hôpitaux de Paris (AP-HP), Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| |
Collapse
|
19
|
Abstract
Cryptococcus is among the most common invasive fungal pathogens globally and is one of the leading causes of acquired immunodeficiency virus-related deaths. Cryptococcus neoformans and Cryptococcus gattii are the most clinically relevant species and account for most cryptococcal disease. Pulmonary manifestations can range from mild symptoms to life-threatening infection. Treatment is tailored based on the severity of pulmonary infection, the presence of disseminated or central nervous system disease, and patient immune status. Amphotericin B and flucytosine followed by fluconazole remain the standard agents for the treatment of severe cryptococcal infection.
Collapse
Affiliation(s)
- Kate Skolnik
- Division of Respirology, Department of Internal Medicine, Rockyview General Hospital, University of Calgary, Respirology Offices, 7007 14th Street Southwest, Calgary, Alberta T2V 1P9, Canada
| | - Shaunna Huston
- Department of Physiology and Pharmacology, Health Research Innovation Centre, University of Calgary, Room 4AA08, 3330 Hospital Drive Northwest, Calgary, Alberta T2N 4N1, Canada
| | - Christopher H Mody
- Department of Microbiology and Infectious Diseases, Health Research Innovation Centre, University of Calgary, Room 4AA14, 3330 Hospital Drive Northwest, Calgary, Alberta T2N 4N1, Canada; Department of Internal Medicine, Health Research Innovation Centre, University of Calgary, Room 4AA14, 3330 Hospital Drive Northwest, Calgary, Alberta T2N 4N1, Canada.
| |
Collapse
|
20
|
Hernández-Chávez MJ, Pérez-García LA, Niño-Vega GA, Mora-Montes HM. Fungal Strategies to Evade the Host Immune Recognition. J Fungi (Basel) 2017; 3:jof3040051. [PMID: 29371567 PMCID: PMC5753153 DOI: 10.3390/jof3040051] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 09/18/2017] [Accepted: 09/19/2017] [Indexed: 12/23/2022] Open
Abstract
The recognition of fungal cells by the host immune system is key during the establishment of a protective anti-fungal response. Even though the immune system has evolved a vast number of processes to control these organisms, they have developed strategies to fight back, avoiding the proper recognition by immune components and thus interfering with the host protective mechanisms. Therefore, the strategies to evade the immune system are as important as the virulence factors and attributes that damage the host tissues and cells. Here, we performed a thorough revision of the main fungal tactics to escape from the host immunosurveillance processes. These include the composition and organization of the cell wall, the fungal capsule, the formation of titan cells, biofilms, and asteroid bodies; the ability to undergo dimorphism; and the escape from nutritional immunity, extracellular traps, phagocytosis, and the action of humoral immune effectors.
Collapse
Affiliation(s)
- Marco J Hernández-Chávez
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P., Guanajuato Gto. 36050, México.
| | - Luis A Pérez-García
- Unidad Académica Multidisciplinaria Zona Huasteca, Universidad Autónoma de San Luis Potosí, Romualdo del Campo 501, Fracc. Rafael Curiel, C.P., Cd. Valle SLP. 79060, México.
| | - Gustavo A Niño-Vega
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P., Guanajuato Gto. 36050, México.
| | - Héctor M Mora-Montes
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P., Guanajuato Gto. 36050, México.
| |
Collapse
|
21
|
Immune Recognition of Fungal Polysaccharides. J Fungi (Basel) 2017; 3:jof3030047. [PMID: 29371564 PMCID: PMC5715945 DOI: 10.3390/jof3030047] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/21/2017] [Accepted: 08/23/2017] [Indexed: 02/06/2023] Open
Abstract
The incidence of fungal infections has dramatically increased in recent years, in large part due to increased use of immunosuppressive medications, as well as aggressive medical and surgical interventions that compromise natural skin and mucosal barriers. There are relatively few currently licensed antifungal drugs, and rising resistance to these agents has led to interest in the development of novel preventative and therapeutic strategies targeting these devastating infections. One approach to combat fungal infections is to augment the host immune response towards these organisms. The polysaccharide-rich cell wall is the initial point of contact between fungi and the host immune system, and therefore, represents an important target for immunotherapeutic approaches. This review highlights the advances made in our understanding of the mechanisms by which the immune system recognizes and interacts with exopolysaccharides produced by four of the most common fungal pathogens: Aspergillus fumigatus, Candida albicans, Cryptococcus neoformans, and Histoplasma capsulatum. Work to date suggests that inner cell wall polysaccharides that play an important structural role are the most conserved across diverse members of the fungal kingdom, and elicit the strongest innate immune responses. The immune system senses these carbohydrates through receptors, such as lectins and complement proteins. In contrast, a greater diversity of polysaccharides is found within the outer cell walls of pathogenic fungi. These glycans play an important role in immune evasion, and can even induce anti-inflammatory host responses. Further study of the complex interactions between the host immune system and the fungal polysaccharides will be necessary to develop more effective therapeutic strategies, as well as to explore the use of immunosuppressive polysaccharides as therapeutic agents to modulate inflammation.
Collapse
|
22
|
Abstract
The protective effect of meningococcal vaccines targeting disease causing serogroups exemplified by the introduction of MenAfriVac™ in Africa, is well established and documented in large population-based studies. Due to the emergence of other meningococcal disease causing serogroups, novel vaccine formulations are needed. There is a high potential for novel nanotechnology-based meningococcal vaccine formulations that can provide wider vaccine coverage. The proposed meningococcal vaccine formulation contains spherical shaped micro and nanoparticles that are biological mimics of Niesseria meningitidis, therefore present to immune system as invader and elicit robust immune responses. Vaccine nanoparticles encapsulate meningococcal CPS polymers in a biodegradable material that slowly release antigens, therefore enhance antigen presentation by exerting antigen depot effect. The antigenicity of meningococcal vaccine delivered in nanoparticles is significantly higher when compared to vaccine delivered in solution. Preclinical studies are required to assess the immunogenicity of novel vaccine formulations. Therefore, implementing various in-vitro human immune cell-based assays that mimic in-vivo interactions, would provide good insight on optimal antigen dose, effective antigen presentation, facilitate screening of various vaccine and adjuvant combinations and predict in-vivo immunogenicity. This rapid approach is cost-effective and provides data required for the preclinical immunogenicity assessment of novel meningococcal vaccine formulations.
Collapse
Affiliation(s)
- Susu M Zughaier
- a Laboratory of Bacterial Pathogenesis , Department of Veterans Affairs Medical Center , Decatur , GA , USA.,b Department of Microbiology and Immunology , Emory University School of Medicine , Atlanta , GA , USA
| |
Collapse
|
23
|
Movahed E, Tan GMY, Munusamy K, Yeow TC, Tay ST, Wong WF, Looi CY. Triclosan Demonstrates Synergic Effect with Amphotericin B and Fluconazole and Induces Apoptosis-Like Cell Death in Cryptococcus neoformans. Front Microbiol 2016; 7:360. [PMID: 27047474 PMCID: PMC4800180 DOI: 10.3389/fmicb.2016.00360] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 03/07/2016] [Indexed: 11/20/2022] Open
Abstract
Objectives:Cryptococcus neoformans is an opportunistic fungus that causes fatal meningoencephalitis especially in AIDS patients. There is an increasing need for discovery of new anti-cryptococcal drugs due to emergence of resistance cases in recent years. In this study, we aim to elucidate the antifungal effect of triclosan against C. neoformans. Methods: Minimal inhibitory concentration (MIC) of triclosan in different C. neoformans strains was first examined. The in vitro interactions between triclosan and two standard anti-fungal drugs (amphotericin B and fluconazole) were further evaluated by microdilution checkerboard assay. Mechanism of triclosan fungicidal activity was then investigated by viewing the cell morphology under transmission electron microscope. Results: We reported that triclosan potently inhibited the growth of C. neoformans. A combination of triclosan with amphotericin B or with fluconazole enhanced their fungicidal effects. Triclosan-treated C. neoformans displayed characteristics such as nuclear chromatin condensation, extensive intracellular vacuolation and mitochondrial swelling, indicating that triclosan triggered apoptosis-like cell death. Conclusion: In summary, our report suggests triclosan as an independent drug or synergent for C. neoformans treatment.
Collapse
Affiliation(s)
- Elaheh Movahed
- Department of Medical Microbiology, Tropical Infectious Disease Research and Education Center, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia
| | - Grace Min Yi Tan
- Department of Medical Microbiology, Tropical Infectious Disease Research and Education Center, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia
| | - Komathy Munusamy
- Department of Medical Microbiology, Tropical Infectious Disease Research and Education Center, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia
| | - Tee Cian Yeow
- Department of Medical Microbiology, Tropical Infectious Disease Research and Education Center, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia
| | - Sun Tee Tay
- Department of Medical Microbiology, Tropical Infectious Disease Research and Education Center, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia
| | - Won Fen Wong
- Department of Medical Microbiology, Tropical Infectious Disease Research and Education Center, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia
| | - Chung Yeng Looi
- Department of Pharmacology, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia
| |
Collapse
|
24
|
Abstract
Enzymes play key roles in fungal pathogenesis. Manipulation of enzyme expression or activity can significantly alter the infection process, and enzyme expression profiles can be a hallmark of disease. Hence, enzymes are worthy targets for better understanding pathogenesis and identifying new options for combatting fungal infections. Advances in genomics, proteomics, transcriptomics, and mass spectrometry have enabled the identification and characterization of new fungal enzymes. This review focuses on recent developments in the virulence-associated enzymes from Cryptococcus neoformans. The enzymatic suite of C. neoformans has evolved for environmental survival, but several of these enzymes play a dual role in colonizing the mammalian host. We also discuss new therapeutic and diagnostic strategies that could be based on the underlying enzymology.
Collapse
|
25
|
Gibson JF, Johnston SA. Immunity to Cryptococcus neoformans and C. gattii during cryptococcosis. Fungal Genet Biol 2014; 78:76-86. [PMID: 25498576 PMCID: PMC4503824 DOI: 10.1016/j.fgb.2014.11.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Revised: 11/25/2014] [Accepted: 11/29/2014] [Indexed: 10/25/2022]
Abstract
The vast majority of infection with cryptococcal species occurs with Cryptococcus neoformans in the severely immunocompromised. A significant exception to this is the infections of those with apparently normal immune systems by Cryptococcus gattii. Susceptibility to cryptococcosis can be broadly categorised as a defect in adaptive immune responses, especially in T cell immunity. However, innate immune cells such as macrophages play a key role and are likely the primary effector cell in the killing and ultimate clearance of cryptococcal infection. In this review we discuss the current state of our understanding of how the immune system responds to cryptococcal infection in health and disease, with reference to the work communicated at the 9th International Conference on Cryptococcus and Cryptococcosis (ICCC9). We have focussed on cell mediated responses, particularly early in infection, but with the aim of presenting a broad overview of our understanding of immunity to cryptococcal infection, highlighting some recent advances and offering some perspectives on future directions.
Collapse
Affiliation(s)
- Josie F Gibson
- Department of Infection and Immunity, Medical School, University of Sheffield, S10 2RX, UK; Bateson Centre, Department of Biomedical Sciences, University of Sheffield, S10 2TN, UK
| | - Simon A Johnston
- Department of Infection and Immunity, Medical School, University of Sheffield, S10 2RX, UK; Bateson Centre, Department of Biomedical Sciences, University of Sheffield, S10 2TN, UK.
| |
Collapse
|
26
|
Pericolini E, Gabrielli E, Alunno A, Bartoloni Bocci E, Perito S, Chow SK, Cenci E, Casadevall A, Gerli R, Vecchiarelli A. Functional improvement of regulatory T cells from rheumatoid arthritis subjects induced by capsular polysaccharide glucuronoxylomannogalactan. PLoS One 2014; 9:e111163. [PMID: 25338013 PMCID: PMC4206502 DOI: 10.1371/journal.pone.0111163] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 09/25/2014] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Regulatory T cells (Treg) play a critical role in the prevention of autoimmunity, and the suppressive activity of these cells is impaired in rheumatoid arthritis (RA). The aim of the present study was to investigate function and properties of Treg of RA patients in response to purified polysaccharide glucuronoxylomannogalactan (GXMGal). METHODS Flow cytometry and western blot analysis were used to investigate the frequency, function and properties of Treg cells. RESULTS GXMGal was able to: i) induce strong increase of FOXP3 on CD4+ T cells without affecting the number of CD4+CD25+FOXP3+ Treg cells with parallel increase in the percentage of non-conventional CD4+CD25-FOXP3+ Treg cells; ii) increase intracellular levels of TGF-β1 in CD4+CD25-FOXP3+ Treg cells and of IL-10 in both CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells; iii) enhance the suppressive activity of CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells in terms of inhibition of effector T cell activity and increased secretion of IL-10; iv) decrease Th1 response as demonstrated by inhibition of T-bet activation and down-regulation of IFN-γ and IL-12p70 production; v) decrease Th17 differentiation by down-regulating pSTAT3 activation and IL-17A, IL-23, IL-21, IL-22 and IL-6 production. CONCLUSION These data show that GXMGal improves Treg functions and increases the number and function of CD4+CD25-FOXP3+ Treg cells of RA patients. It is suggested that GXMGal may be potentially useful for restoring impaired Treg functions in autoimmune disorders and for developing Treg cell-based strategies for the treatment of these diseases.
Collapse
Affiliation(s)
- Eva Pericolini
- Microbiology Section, Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | - Elena Gabrielli
- Microbiology Section, Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | - Alessia Alunno
- Rheumatology Unit, Department of Medicine, University of Perugia, Perugia, Italy
| | | | - Stefano Perito
- Microbiology Section, Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | - Siu-Kei Chow
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, New York, United States of America
| | - Elio Cenci
- Microbiology Section, Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | - Arturo Casadevall
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, New York, United States of America
| | - Roberto Gerli
- Rheumatology Unit, Department of Medicine, University of Perugia, Perugia, Italy
| | - Anna Vecchiarelli
- Microbiology Section, Department of Experimental Medicine, University of Perugia, Perugia, Italy
- * E-mail:
| |
Collapse
|
27
|
Ubale RV, Gala RP, Zughaier SM, D'Souza MJ. Induction of death receptor CD95 and co-stimulatory molecules CD80 and CD86 by meningococcal capsular polysaccharide-loaded vaccine nanoparticles. AAPS JOURNAL 2014; 16:986-93. [PMID: 24981893 DOI: 10.1208/s12248-014-9635-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 06/05/2014] [Indexed: 01/04/2023]
Abstract
Neisseria meningitidis is a leading cause of bacterial meningitis and sepsis, and its capsular polysaccharides (CPS) are a major virulence factor in meningococcal infections and form the basis for serogroup designation and protective vaccines. We formulated a novel nanovaccine containing meningococcal CPS as an antigen encapsulated in albumin-based nanoparticles (NPs) that does not require chemical conjugation to a protein carrier. These nanoparticles are taken up by antigen-presenting cells and act as antigen depot by slowly releasing the antigen. In this study, we determined the ability of CPS-loaded vaccine nanoparticles to induce co-stimulatory molecules, namely CD80, CD86, and CD95 that impact effective antigen presentation. Co-stimulatory molecule gene induction and surface expression on macrophages and dendritic cells pulsed with meningococcal CPS-loaded nanoparticles were investigated using gene array and flow cytometry methods. Meningococcal CPS-loaded NP significantly induced the surface protein expression of CD80 and CD86, markers of dendritic cell maturation, in human THP-1 macrophages and in murine dendritic cells DC2.4 in a dose-dependent manner. The massive upregulation was also observed at the gene expression. However, high dose of CPS-loaded NP, but not empty NP, induced the expression of death receptor CD95 (Fas) leading to reduced TNF-α release and reduction in cell viability. The data suggest that high expression of CD95 may lead to death of antigen-presenting cells and consequently suboptimal immune responses to vaccine. The CPS-loaded NP induces the expression of co-stimulatory molecules and acts as antigen depot and can spare antigen dose, highly desirable criteria for vaccine formulations.
Collapse
Affiliation(s)
- Ruhi V Ubale
- Department of Pharmaceutical Sciences, School of Pharmacy, Union University, Jackson, Tennessee, 38305, USA
| | | | | | | |
Collapse
|
28
|
Kozarski M, Klaus A, Jakovljevic D, Todorovic N, Niksic M, Vrvic MM, van Griensven LJLD. Dietary polysaccharide extracts of Agaricus brasiliensis fruiting bodies: chemical characterization and bioactivities at different levels of purification. Food Res Int 2014; 64:53-64. [PMID: 30011685 DOI: 10.1016/j.foodres.2014.05.075] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 05/06/2014] [Accepted: 05/29/2014] [Indexed: 12/13/2022]
Abstract
Polysaccharides of the European strain of A. brasiliensis were obtained by hot water extraction and ethanol precipitation (HWPE I) of fruiting bodies, and further purified by dialysis (HWPE II) and pronase incubation (PPE). These polysaccharides consisted mainly of (1→6)-β-d-glucans. PPE was free of proteins and polyphenols as demonstrated by quantitative assays and NMR profiling. They showed a clear IFN-γ inducing activity in human PBMCs, which suggests these polysaccharides to have proinflammatory effects. Treatment by β-glucosidase caused the polysaccharides to be degraded into smaller fragments and at the same time increased their IFN-γ inducing activity in PBMCs fourfold. In vitro, PPE showed a dose-dependent inhibition of the proliferation of the human leukemia Jurkat cell. At 100μg/mL the cells' viability was decreased by appr. 51% compared to the control. EPR spin trapping demonstrated a high antioxidative activity against •OH and •O2- radicals of HWPE I and PPE. Further, the results of the antioxidant assays indicated that antioxidant activity against •OH radicals in the Fenton system was achieved through scavenging or through chelating iron mechanisms. The good immunomodulating and antioxidative properties of A. brasiliensis polysaccharide extract obtained by hot water extraction and ethanol precipitation make it suitable for everyday use as an inexpensive dietary supplement.
Collapse
Affiliation(s)
- Maja Kozarski
- Department for Chemistry and Biochemistry, Faculty of Agriculture, University of Belgrade, Nemanjina 6, Belgrade 11080, Serbia
| | - Anita Klaus
- Department for Industrial Microbiology, Faculty of Agriculture, University of Belgrade, Nemanjina 6, Belgrade 11080, Serbia
| | - Dragica Jakovljevic
- Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Njegoseva 12, Belgrade 11001, Serbia
| | - Nina Todorovic
- Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Njegoseva 12, Belgrade 11001, Serbia
| | - Miomir Niksic
- Department for Industrial Microbiology, Faculty of Agriculture, University of Belgrade, Nemanjina 6, Belgrade 11080, Serbia
| | - Miroslav M Vrvic
- Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Njegoseva 12, Belgrade 11001, Serbia; Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade, Serbia
| | - Leo J L D van Griensven
- Plant Research International, Wageningen University and Research, P.O. Box 16, 6700 AA Wageningen, The Netherlands.
| |
Collapse
|
29
|
Heiss C, Skowyra ML, Liu H, Klutts JS, Wang Z, Williams M, Srikanta D, Beverley SM, Azadi P, Doering TL. Unusual galactofuranose modification of a capsule polysaccharide in the pathogenic yeast Cryptococcus neoformans. J Biol Chem 2013; 288:10994-1003. [PMID: 23408430 DOI: 10.1074/jbc.m112.441998] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Galactofuranose (Galf) is the five-membered ring form of galactose. Although it is absent from mammalian glycans, it occurs as a structural and antigenic component of important cell surface molecules in a variety of microbes, ranging from bacteria to parasites and fungi. One such organism is Cryptococcus neoformans, a pathogenic yeast that causes lethal meningoencephalitis in immunocompromised individuals, particularly AIDS patients. C. neoformans is unique among fungal pathogens in bearing a complex polysaccharide capsule, a critical virulence factor reported to include Galf. Notably, how Galf modification contributes to the structure and function of the cryptococcal capsule is not known. We have determined that Galf is β1,2-linked to an unusual tetrasubstituted galactopyranose of the glucuronoxylomannogalactan (GXMGal) capsule polysaccharide. This discovery fills a longstanding gap in our understanding of a major polymer of the cryptococcal capsule. We also engineered a C. neoformans strain that lacks UDP-galactopyranose mutase; this enzyme forms UDP-Galf, the nucleotide sugar donor required for Galf addition. Mutase activity was required for the incorporation of Galf into glucuronoxylomannogalactan but was dispensable for vegetative growth, cell integrity, and virulence in a mouse model.
Collapse
Affiliation(s)
- Christian Heiss
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Pericolini E, Alunno A, Gabrielli E, Bartoloni E, Cenci E, Chow SK, Bistoni G, Casadevall A, Gerli R, Vecchiarelli A. The microbial capsular polysaccharide galactoxylomannan inhibits IL-17A production in circulating T cells from rheumatoid arthritis patients. PLoS One 2013; 8:e53336. [PMID: 23308194 PMCID: PMC3540098 DOI: 10.1371/journal.pone.0053336] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Accepted: 11/29/2012] [Indexed: 12/18/2022] Open
Abstract
The persistence of activated T cells in rheumatoid arthritis (RA) synovium may be attributable to increased homing, increased retention or a possible imbalance between cell proliferation and programmed cell death. Induction of apoptosis may represent a potential therapeutic approach. Galactoxylomannan (GalXM) from the opportunistic fungus Cryptococcus neoformans can interact with T cells and induce T-cell apoptosis through the inhibition of CD45 phosphatase activity. The aim of this study was to determine the effect of GalXM on circulating T cells from patients with RA and the underlying mechanisms. GalXM immunomodulating effect on apoptosis and signal transduction pathway involved in IL-17A production was evaluated on T cells. RA T-cell apoptosis, higher than that of control T cells, was further increased by GalXM through induction of caspase-3 activation. Activated T cells expressing the CD45RO molecule and producing IL-17A were the main target of GalXM-induced apoptosis. GalXM induced consistent impairment of IL-17A production and inhibition of STAT3, which was hyperactivated in RA. In conclusion, GalXM triggered apoptosis of activated memory T cells and interfered with IL-17A production in RA. These data suggest therapeutic targeting of deleterious Th17 cells in RA and other autoimmune diseases.
Collapse
Affiliation(s)
- Eva Pericolini
- Microbiology Section, Department of Experimental Medicine and Biochemical Science, University of Perugia, Perugia, Italy
| | - Alessia Alunno
- Rheumatology Unit, Department of Clinical and Experimental Medicine, University of Perugia, Perugia, Italy
| | - Elena Gabrielli
- Microbiology Section, Department of Experimental Medicine and Biochemical Science, University of Perugia, Perugia, Italy
| | - Elena Bartoloni
- Rheumatology Unit, Department of Clinical and Experimental Medicine, University of Perugia, Perugia, Italy
| | - Elio Cenci
- Microbiology Section, Department of Experimental Medicine and Biochemical Science, University of Perugia, Perugia, Italy
| | - Siu-Kei Chow
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, New York, United States of America
| | - Giovanni Bistoni
- Department of Plastic and Reconstructive Surgery, “La Sapienza” Medical School, University of Rome, Rome, Italy
| | - Arturo Casadevall
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, New York, United States of America
| | - Roberto Gerli
- Rheumatology Unit, Department of Clinical and Experimental Medicine, University of Perugia, Perugia, Italy
- * E-mail:
| | - Anna Vecchiarelli
- Microbiology Section, Department of Experimental Medicine and Biochemical Science, University of Perugia, Perugia, Italy
| |
Collapse
|
31
|
Ben-Abdallah M, Sturny-Leclère A, Avé P, Louise A, Moyrand F, Weih F, Janbon G, Mémet S. Fungal-induced cell cycle impairment, chromosome instability and apoptosis via differential activation of NF-κB. PLoS Pathog 2012; 8:e1002555. [PMID: 22396644 PMCID: PMC3291658 DOI: 10.1371/journal.ppat.1002555] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 01/12/2012] [Indexed: 12/15/2022] Open
Abstract
Microbial pathogens have developed efficient strategies to compromise host immune responses. Cryptococcus neoformans is a facultative intracellular pathogen, recognised as the most common cause of systemic fungal infections leading to severe meningoencephalitis, mainly in immunocompromised patients. This yeast is characterized by a polysaccharide capsule, which inhibits its phagocytosis. Whereas phagocytosis escape and macrophage intracellular survival have been intensively studied, extracellular survival of this yeast and restraint of host innate immune response are still poorly understood. In this study, we have investigated whether C. neoformans affected macrophage cell viability and whether NF-κB (nuclear factor-κB), a key regulator of cell growth, apoptosis and inflammation, was involved. Using wild-type (WT) as well as mutant strains of C. neoformans for the pathogen side, and WT and mutant cell lines with altered NF-κB activity or signalling as well as primary macrophages for the host side, we show that C. neoformans manipulated NF-κB-mediated signalling in a unique way to regulate macrophage cell fate and viability. On the one hand, serotype A strains reduced macrophage proliferation in a capsule-independent fashion. This growth decrease, which required a critical dosage of NF-κB activity, was caused by cell cycle disruption and aneuploidy, relying on fungal-induced modification of expression of several cell cycle checkpoint regulators in S and G2/M phases. On the other hand, C. neoformans infection induced macrophage apoptosis in a capsule-dependent manner with a differential requirement of the classical and alternative NF-κB signalling pathways, the latter one being essential. Together, these findings shed new light on fungal strategies to subvert host response through uncoupling of NF-κB activity in pathogen-controlled apoptosis and impairment of cell cycle progression. They also provide the first demonstration of induction of aneuploidy by a fungal pathogen, which may have wider implications for human health as aneuploidy is proposed to promote tumourigenesis.
Collapse
Affiliation(s)
- Mariem Ben-Abdallah
- Institut Pasteur, Unité de Mycologie Moléculaire, Département Infection et Epidémiologie, Paris, France
- CNRS, URA3012, Paris, France
| | - Aude Sturny-Leclère
- Institut Pasteur, Unité de Mycologie Moléculaire, Département Infection et Epidémiologie, Paris, France
- CNRS, URA3012, Paris, France
| | - Patrick Avé
- Institut Pasteur, Unité d'Histopathologie, Département Infection et Epidémiologie, Paris, France
| | - Anne Louise
- Institut Pasteur, Plateforme d'Imagerie Dynamique, Paris, France
| | - Frédérique Moyrand
- Institut Pasteur, Unité des Aspergillus, Département de Parasitologie et Mycologie, Paris, France
| | - Falk Weih
- Leibniz-Institute for Age Research - Fritz-Lipmann-Institute, Research Group Immunology, Jena, Germany
| | - Guilhem Janbon
- Institut Pasteur, Unité des Aspergillus, Département de Parasitologie et Mycologie, Paris, France
| | - Sylvie Mémet
- Institut Pasteur, Unité de Mycologie Moléculaire, Département Infection et Epidémiologie, Paris, France
- CNRS, URA3012, Paris, France
- * E-mail:
| |
Collapse
|
32
|
Abstract
Fungal meningitis is a serious disease caused by a fungal infection of the central nervous system (CNS) mostly in individuals with immune system deficiencies. Fungal meningitis is often fatal without proper treatment, and the mortality rate remains unacceptably high even with antifungal drug interventions. Currently, cryptococcal meningitis is the most common fungal meningitis in HIV-1/AIDS, and its disease mechanism has been extensively studied. The key steps for fungi to infect brain and cause meningitis after establishment of local infection are the dissemination of fungal cells to the bloodstream and invasion through the blood brain barrier to reach the CNS. In this review, we use cryptococcal CNS infection as an example to describe the current molecular understanding of fungal meningitis, including the establishment of the infection, dissemination, and brain invasion. Host and microbial factors that contribute to these infection steps are also discussed.
Collapse
Affiliation(s)
- Tong-Bao Liu
- The Public Health Research Institute, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ, USA
| | | | | |
Collapse
|
33
|
Affiliation(s)
- Martin B. Dickman
- Borlaug Advanced Research Center, Texas A&M University, College Station, Texas, United States of America
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Paul de Figueiredo
- Borlaug Advanced Research Center, Texas A&M University, College Station, Texas, United States of America
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station, Texas, United States of America
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
- Department of Microbial and Molecular Pathogenesis, Texas A&M Health Science Center, College Station, Texas, United States of America
- * E-mail:
| |
Collapse
|
34
|
Fontaine T, Delangle A, Simenel C, Coddeville B, van Vliet SJ, van Kooyk Y, Bozza S, Moretti S, Schwarz F, Trichot C, Aebi M, Delepierre M, Elbim C, Romani L, Latgé JP. Galactosaminogalactan, a new immunosuppressive polysaccharide of Aspergillus fumigatus. PLoS Pathog 2011; 7:e1002372. [PMID: 22102815 PMCID: PMC3213105 DOI: 10.1371/journal.ppat.1002372] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 09/27/2011] [Indexed: 01/24/2023] Open
Abstract
A new polysaccharide secreted by the human opportunistic fungal pathogen Aspergillus fumigatus has been characterized. Carbohydrate analysis using specific chemical degradations, mass spectrometry, 1H and 13C nuclear magnetic resonance showed that this polysaccharide is a linear heterogeneous galactosaminogalactan composed of α1-4 linked galactose and α1-4 linked N-acetylgalactosamine residues where both monosacharides are randomly distributed and where the percentage of galactose per chain varied from 15 to 60%. This polysaccharide is antigenic and is recognized by a majority of the human population irrespectively of the occurrence of an Aspergillus infection. GalNAc oligosaccharides are an essential epitope of the galactosaminogalactan that explains the universal antibody reaction due to cross reactivity with other antigenic molecules containing GalNAc stretches such as the N-glycans of Campylobacter jejuni. The galactosaminogalactan has no protective effect during Aspergillus infections. Most importantly, the polysaccharide promotes fungal development in immunocompetent mice due to its immunosuppressive activity associated with disminished neutrophil infiltrates. Aspergillus fumigatus is an opportunistic human fungal pathogen that causes a wide range of diseases including allergic reactions and local or systemic infections such as invasive pulmonary aspergillosis that has emerged in the recent years as a leading cause of infection related mortality among immunocompromised patients. Polysaccharides from the fungal cell wall play essential biological functions in the fungal cell biology and in host-pathogen interactions. Indeed, it has been shown that polysaccharides can modulate the human immune response; some of them (β-glucan and α-glucans) having a protective effect against Aspergillus infection. We report here the purification and chemical characterization of a new antigenic polysaccharide (galactosaminogalactan) produced by A. fumigatus. This polymer is secreted during infection. In murine models of aspergillosis, this galactosaminogalactan is not protective but it is immunosuppressive and favors A. fumigatus infection. Particularly it induces the apoptotic death of neutrophils that are the phagocytes playing an essential role in the killing of fungal pathogens.
Collapse
|
35
|
Vecchiarelli A, Pericolini E, Gabrielli E, Chow SK, Bistoni F, Cenci E, Casadevall A. Cryptococcus neoformans galactoxylomannan is a potent negative immunomodulator, inspiring new approaches in anti-inflammatory immunotherapy. Immunotherapy 2011; 3:997-1005. [DOI: 10.2217/imt.11.86] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cryptococcus neoformans is an opportunistic fungal pathogen responsible for life-threatening infections in immunocompromised individuals and occasionally in those with no known immune impairment. The fungus is endowed with several virulence factors, including capsular polysaccharides that play a key role in virulence. The capsule is composed of 90–95% glucuronoxylomannan (GXM), 5–8% galactoxylomannan (GalXM) and <1% mannoproteins. Capsular polysaccharides are shed into tissue where they produce many deleterious effects. Since GalXM has a smaller molecular mass, the molar concentration of GalXM in polysaccharide that is shed could exceed that of GXM in C. neoformans exopolysaccharides. Moreover, GalXM exhibits a number of unusual biologic properties both in vitro and in vivo. Here, we summarize the principal immunomodulatory effects of GalXM described during the last 20 years, particularly the mechanisms leading to induction of apoptosis in T lymphocytes, B lymphocytes and macrophages. Since the capacity of GalXM to induce widespread immune suppression is believed to contribute to the virulence of C. neoformans, this property might be exploited therapeutically to dampen the aberrant activation of immune cells during autoimmune disorders.
Collapse
Affiliation(s)
| | - Eva Pericolini
- Microbiology Section, Department of Experimental Medicine & Biochemical Sciences, University of Perugia, Via del Giochetto, 06126 Perugia, Italy
| | - Elena Gabrielli
- Microbiology Section, Department of Experimental Medicine & Biochemical Sciences, University of Perugia, Via del Giochetto, 06126 Perugia, Italy
| | - Siu-Kei Chow
- Department of Microbiology & Immunology of the Albert Einstein College of Medicine, Bronx, NY, USA
| | - Francesco Bistoni
- Microbiology Section, Department of Experimental Medicine & Biochemical Sciences, University of Perugia, Via del Giochetto, 06126 Perugia, Italy
| | - Elio Cenci
- Microbiology Section, Department of Experimental Medicine & Biochemical Sciences, University of Perugia, Via del Giochetto, 06126 Perugia, Italy
| | - Arturo Casadevall
- Department of Microbiology & Immunology of the Albert Einstein College of Medicine, Bronx, NY, USA
| |
Collapse
|
36
|
Chow SK, Casadevall A. Evaluation of Cryptococcus neoformans galactoxylomannan-protein conjugate as vaccine candidate against murine cryptococcosis. Vaccine 2011; 29:1891-8. [PMID: 21238568 DOI: 10.1016/j.vaccine.2010.12.134] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 12/19/2010] [Accepted: 12/26/2010] [Indexed: 11/28/2022]
Abstract
Galactoxylomannan (GalXM) is a complex polysaccharide produced by the human pathogenic fungus Cryptococcus neoformans that mediates profound immunological derangements in murine models. GalXM is essentially non-immunogenic and produces immune paralysis in mice. Previous studies have attempted to enhance immunogenicity by conjugating GalXM to a protein carrier, but only transient antibody responses were elicited. Here we report the generation of two GalXM conjugates with bovine serum albumin (BSA) and protective antigen (PA) of Bacillus anthracis, respectively, using 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP) as the cyanylating reagent. Both conjugates induced potent and sustained antibody responses as detected by both cross antigen-based and CovaLink direct ELISAs. We confirmed the specificity of the response to GalXM by inhibition ELISA and immunofluorescence. The isotype composition analysis revealed that IgG and IgM were abundant in the immune sera against GalXM, consistent with the induction of a T cell-dependent response. IgG1 was the predominant IgG subclass against GalXM, while immunization with Quil A as adjuvant elicited a significantly higher production of IgG2a than with Freund's adjuvant. Immune sera were not opsonic for C. neoformans and there was no survival difference between immune and non-immune mice challenged with C. neoformans. These results demonstrated the effectiveness of the GalXM-protein conjugate to induce robust immune responses although no evidence was obtained that such responses contributed to host defense.
Collapse
Affiliation(s)
- Siu-Kei Chow
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA
| | | |
Collapse
|
37
|
Olszewski MA, Zhang Y, Huffnagle GB. Mechanisms of cryptococcal virulence and persistence. Future Microbiol 2010; 5:1269-88. [PMID: 20722603 DOI: 10.2217/fmb.10.93] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cryptococcus neoformans is an environmental yeast that is a leading cause of fatal mycosis in AIDS patients and a major cause of meningoencephalitis and CNS-related mortality around the globe. Although C. neoformans infection is mostly a manifestation of immune deficiency, up to 25% of cases reported in the USA occur in patients without recognizable immune defects, indicating that C. neoformans can develop mechanisms that allow it to evade immune defenses and persist in noncompromised hosts. This article discusses mechanisms and routes of infection and the most important elements of host response as well as the mechanisms that promote cryptococcal survival within the host. Metabolic adaptation to physiological host conditions and the mechanisms limiting immune recognition, interfering with phagocytosis and extending intracellular survival of C. neoformans are highlighted. We describe the mechanisms by which C. neoformans can alter adaptive host responses, especially cell-mediated immunity, which is required for clearance of this microbe. We also review cryptococcal strategies of survival in the CNS and briefly discuss adaptations developing in response to medical treatment.
Collapse
Affiliation(s)
- Michal A Olszewski
- Ann Arbor Veterans Administration Health System (11R), 2215 Fuller Road, Ann Arbor, MI 48105, USA.
| | | | | |
Collapse
|
38
|
Pericolini E, Gabrielli E, Bistoni G, Cenci E, Perito S, Chow SK, Riuzzi F, Donato R, Casadevall A, Vecchiarelli A. Role of CD45 signaling pathway in galactoxylomannan-induced T cell damage. PLoS One 2010; 5:e12720. [PMID: 20856869 PMCID: PMC2939064 DOI: 10.1371/journal.pone.0012720] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Accepted: 08/20/2010] [Indexed: 11/19/2022] Open
Abstract
Previously, we reported that Galactoxylomannan (GalXM) activates the extrinsic and intrinsic apoptotic pathways through an interaction with the glycoreceptors on T cells. In this study we establish the role of the glycoreceptor CD45 in GalXM-induced T cell apoptosis, using CD45(+/+) and CD45(-/-) cell lines, derived from BW5147 murine T cell lymphoma. Our results show that whereas CD45 expression is not required for GalXM association by the cells, it is essential for apoptosis induction. In CD45(+/+) cells, CD45 triggering by GalXM reduces the activation of Lck, ZAP70 and Erk1/2. Conversely, in CD45(-/-) cells, Lck was hyperphosphorylated and did not show any modulation after GalXM stimulation. On the whole, our findings provide evidence that the negative regulation of Lck activation occurs via CD45 engagement. This appears to be related to the capacity of GalXM to antagonize T cell activation and induce T cell death. Overall this mechanism may be responsible for the immune paralysis that follows GalXM administration and could explain the powerful immunosuppression that accompanies cryptococcosis.
Collapse
Affiliation(s)
- Eva Pericolini
- Microbiology and Anatomy Sections, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy
| | - Elena Gabrielli
- Microbiology and Anatomy Sections, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy
| | - Giovanni Bistoni
- Department of Plastic and Reconstructive Surgery, University of Rome “La Sapienza” Medical School, Rome, Italy
| | - Elio Cenci
- Microbiology and Anatomy Sections, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy
| | - Stefano Perito
- Microbiology and Anatomy Sections, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy
| | - Siu-Kei Chow
- Department of Microbiology and Immunology of the Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Francesca Riuzzi
- Microbiology and Anatomy Sections, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy
| | - Rosario Donato
- Microbiology and Anatomy Sections, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy
| | - Arturo Casadevall
- Department of Microbiology and Immunology of the Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Anna Vecchiarelli
- Microbiology and Anatomy Sections, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy
- * E-mail:
| |
Collapse
|
39
|
Galactoxylomannans from Cryptococcus neoformans varieties neoformans and grubii are structurally and antigenically variable. EUKARYOTIC CELL 2010; 9:1018-28. [PMID: 20061411 DOI: 10.1128/ec.00268-09] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Prior studies have established that the Cryptococcus neoformans capsular polysaccharide component galactoxylomannan (GalXM) manifests serotype-related structural differences that translate into antigenic differences. We analyzed GalXM from acapsular serotype A and D strains by carbohydrate analysis and static and dynamic light scattering to determine mass, effective diameter, polydispersity, and diffusion coefficients. Multiangle laser light scattering showed that GalXM from C. neoformans var. grubii strain cap59 (serotype A) had larger molecular mass (4.21 x 10(6) +/- 0.95 x 10(6) g/mol) and radius of gyration (207 +/- 27 nm) than GalXM from C. neoformans var. neoformans cap67 (serotype D). cap67 GalXM had corresponding values of 0.70 x 10(6) +/- 0.05 x 10(6) g/mol and 120 +/- 22 nm, respectively. The effective diameter for GalXM and polydispersity from the two strains varied depending on temperature and medium growth conditions, indicating that GalXM structure can vary within a strain, depending on its environment. Zeta potential determinations were negative for GalXM from both strains under all conditions, consistent with the recently reported presence of glucuronic acid. These results imply that C. neoformans GalXM, like glucuronoxylomannan, can manifest variety- and growth condition-related variations. Analysis of 16 C. neoformans and 7 Cryptococcus gattii strains with polyclonal antibody to a GalXM strain revealed antigenic similarities among the C. neoformans variety neoformans and grubii strains and no reactivity with C. gattii. As a result of the deleterious effects of GalXM on immune function, structural and antigenic variability between serotypes may translate into differences in immunomodulatory effects.
Collapse
|
40
|
Doering TL. How sweet it is! Cell wall biogenesis and polysaccharide capsule formation in Cryptococcus neoformans. Annu Rev Microbiol 2009; 63:223-47. [PMID: 19575556 DOI: 10.1146/annurev.micro.62.081307.162753] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cryptococcus neoformans is a pathogenic fungus responsible for severe opportunistic infections. The most prominent feature of this yeast is its elaborate polysaccharide capsule, a complex structure that is required for virulence. The capsule is intimately associated with the cell wall, which underlies the capsule and offers the organism strength and flexibility in potentially hostile environments. Both structures are primarily composed of polysaccharides, offering a glimpse of the tremendous variation inherent in natural carbohydrate structures and their multiple biological functions. The steps in cell wall and capsule biosynthesis and assembly pose fascinating questions of metabolism, enzymology, cell biology, and regulation; the answers have potential application to treatment of a deadly infection. This article reviews current knowledge of cryptococcal cell wall and capsule biosynthesis and outstanding questions for the future.
Collapse
Affiliation(s)
- Tamara Lea Doering
- Department of Molecular Microbiology, Washington University Medical School, St. Louis, Missouri, USA.
| |
Collapse
|
41
|
De Jesus M, Nicola AM, Frases S, Lee IR, Mieses S, Casadevall A. Galactoxylomannan-mediated immunological paralysis results from specific B cell depletion in the context of widespread immune system damage. THE JOURNAL OF IMMUNOLOGY 2009; 183:3885-94. [PMID: 19684080 DOI: 10.4049/jimmunol.0900449] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The mechanisms responsible for polysaccharide-induced immunological paralysis have remained unexplained almost a century after this phenomenon was first described. Cryptococcus neoformans capsular polysaccharides glucuronoxylomannan and galactoxylomannan (GalXM) elicit little or no Ab responses. This study investigates the immunological and biological effects of GalXM in mice. GalXM immunization elicits a state of immunological paralysis in mice characterized by the disappearance of Ab-producing cells in the spleen. Immunological paralysis and lack of immunogenicity could not be overcome by immunization with GalXM conjugated to a protein carrier, Bacillus anthracis protective Ag. Additionally, immunization with GalXM in either complete or IFA was associated with spleen enlargement in BALB/c mice. TUNEL and flow cytometry revealed widespread apoptosis in the spleen after GalXM administration. Administration of a cocktail of caspase-3 inhibitor Z-DEVD-FMK and general caspase inhibitor Z-VAD-FMK or Fas-deficient mice abrogated the complete disappearance of Ab-producing cells. Analysis of spleen cytokine expression in response to GalXM systemic injection revealed that GalXM down-regulated the production of inflammatory cytokines. Hence, we conclude that GalXM-induced immune paralysis is a result of specific B cell depletion mediated by its proapoptotic properties in the context of widespread dysregulation of immune function.
Collapse
Affiliation(s)
- Magdia De Jesus
- Department of Microbiology and Immunology of the Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | | | | | | | | | | |
Collapse
|
42
|
The capsule of the fungal pathogen Cryptococcus neoformans. ADVANCES IN APPLIED MICROBIOLOGY 2009; 68:133-216. [PMID: 19426855 DOI: 10.1016/s0065-2164(09)01204-0] [Citation(s) in RCA: 321] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The capsule of the fungal pathogen Cryptococcus neoformans has been studied extensively in recent decades and a large body of information is now available to the scientific community. Well-known aspects of the capsule include its structure, antigenic properties and its function as a virulence factor. The capsule is composed primarily of two polysaccharides, glucuronoxylomannan (GXM) and galactoxylomannan (GalXM), in addition to a smaller proportion of mannoproteins (MPs). Most of the studies on the composition of the capsule have focused on GXM, which comprises more than 90% of the capsule's polysaccharide mass. It is GalXM, however, that is of particular scientific interest because of its immunological properties. The molecular structure of these polysaccharides is very complex and has not yet been fully elucidated. Both GXM and GalXM are high molecular mass polymers with the mass of GXM equaling roughly 10 times that of GalXM. Recent findings suggest, however, that the actual molecular weight might be different to what it has traditionally been thought to be. In addition to their structural roles in the polysaccharide capsule, these molecules have been associated with many deleterious effects on the immune response. Capsular components are therefore considered key virulence determinants in C. neoformans, which has motivated their use in vaccines and made them targets for monoclonal antibody treatments. In this review, we will provide an update on the current knowledge of the C. neoformans capsule, covering aspects related to its structure, synthesis and particularly, its role as a virulence factor.
Collapse
|
43
|
Pericolini E, Gabrielli E, Cenci E, De Jesus M, Bistoni F, Casadevall A, Vecchiarelli A. Involvement of glycoreceptors in galactoxylomannan-induced T cell death. THE JOURNAL OF IMMUNOLOGY 2009; 182:6003-10. [PMID: 19414751 DOI: 10.4049/jimmunol.0803833] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The major virulence factor of Cryptococcus neoformans is its capsular polysaccharide, which is also released into tissues. The shed polysaccharide is composed of glucuronoxylomannan, galactoxylomannan (GalXM), and mannoproteins. In a previous study, we demonstrated a direct interaction of purified soluble GalXM with T cells that induced their apoptosis. In this study, we focus on the mechanisms involved in the apoptotic effect of GalXM. In our experimental system, we analyzed the effect of GalXM on purified human T cells and Jurkat cells, a T cell line routinely used for apoptotic studies. Our results reveal that GalXM activates the extrinsic and intrinsic apoptotic pathways through the cleavage and recruitment of caspase-8. Caspase-8 elicits the downstream executioner caspase-3, caspase-6, and caspase-7 both directly and indirectly, via Bid cleavage and caspase-9 activation. These effects appeared to be primarily mediated by the interaction of GalXM with the glycoreceptors, which differed in human T and Jurkat cells. CD45 was primarily involved in Jurkat cells apoptosis while CD7 and CD43 mediated human T cell apoptosis. Our results highlight a new mechanism by which a microbial product can contribute to virulence through direct interaction with T cell glycoreceptors, thereby triggering lymphocyte apoptosis.
Collapse
Affiliation(s)
- Eva Pericolini
- Department of Experimental Medicine and Biochemical Sciences, Microbiology Section, University of Perugia, Perugia, Italy
| | | | | | | | | | | | | |
Collapse
|
44
|
Surfactant protein D increases phagocytosis of hypocapsular Cryptococcus neoformans by murine macrophages and enhances fungal survival. Infect Immun 2009; 77:2783-94. [PMID: 19451250 DOI: 10.1128/iai.00088-09] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cryptococcus neoformans is a facultative intracellular opportunistic pathogen and the leading cause of fungal meningitis in humans. In the absence of a protective cellular immune response, the inhalation of C. neoformans cells or spores results in pulmonary infection. C. neoformans cells produce a polysaccharide capsule composed predominantly of glucuronoxylomannan, which constitutes approximately 90% of the capsular material. In the lungs, surfactant protein A (SP-A) and SP-D contribute to immune defense by facilitating the aggregation, uptake, and killing of many microorganisms by phagocytic cells. We hypothesized that SP-D plays a role in C. neoformans pathogenesis by binding to and enhancing the phagocytosis of the yeast. Here, the abilities of SP-D to bind to and facilitate the phagocytosis and survival of the wild-type encapsulated strain H99 and the cap59Delta mutant hypocapsular strain are assessed. SP-D binding to cap59Delta mutant cells was approximately sixfold greater than binding to wild-type cells. SP-D enhanced the phagocytosis of cap59Delta cells by approximately fourfold in vitro. To investigate SP-D binding in vivo, SP-D(-/-) mice were intranasally inoculated with Alexa Fluor 488-labeled cap59Delta or H99 cells. By confocal microscopy, a greater number of phagocytosed C. neoformans cells in wild-type mice than in SP-D(-/-) mice was observed, consistent with in vitro data. Interestingly, SP-D protected C. neoformans cells against macrophage-mediated defense mechanisms in vitro, as demonstrated by an analysis of fungal viability using a CFU assay. These findings provide evidence that C. neoformans subverts host defense mechanisms involving surfactant, establishing a novel virulence paradigm that may be targeted for therapy.
Collapse
|
45
|
Capsular localization of the Cryptococcus neoformans polysaccharide component galactoxylomannan. EUKARYOTIC CELL 2008; 8:96-103. [PMID: 18952901 DOI: 10.1128/ec.00331-08] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cryptococcus neoformans capsular polysaccharide is composed of at least two components, glucuronoxylomannan (GXM) and galactoxylomannans (GalXM). Although GXM has been extensively studied, little is known about the location of GalXM in the C. neoformans capsule, in part because there are no serological reagents specific to this antigen. To circumvent the poor immunogenicity of GalXM, this antigen was conjugated to protective antigen from Bacillus anthracis as a protein carrier. The resulting conjugate elicited antibodies that reacted with GalXM in mice and yielded an immune serum that proved useful for studying GalXM in the polysaccharide capsule. In acapsular cells, immune serum localized GalXM to the cell wall. In capsulated cells, immune serum localized GalXM to discrete pockets near the capsule edge. GalXM was abundant on the nascent capsules of budding daughter cells. The constituent sugars of GalXM were found in vesicle fractions consistent with vesicular transport for this polysaccharide. In addition, we generated a single-chain fraction variable fragment antibody with specificity to oxidized carbohydrates that also produced punctate immunofluorescence on encapsulated cells that partially colocalized with GalXM. The results are interpreted to mean that GalXM is a transient component of the polysaccharide capsule of mature cells during the process of secretion. Hence, the function of GalXM appears to be more consistent with that of an exopolysaccharide than a structural component of the cryptococcal capsule.
Collapse
|
46
|
Pinto MR, Barreto-Bergter E, Taborda CP. Glycoconjugates and polysaccharides of fungal cell wall and activation of immune system. Braz J Microbiol 2008; 39:195-208. [PMID: 24031202 PMCID: PMC3768395 DOI: 10.1590/s1517-83822008000200001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Accepted: 02/24/2008] [Indexed: 11/21/2022] Open
Abstract
Glycoproteins, glycosphingolipids and polysaccharides exposed at the most external layers of the wall are involved in several types of interactions of fungal cells with the exocellular environment. These molecules are fundamental building blocks of organisms, contributing to the structure, integrity, cell growth, differentiation and signaling. Several of them are immunologically active compounds with potential as regulators of pathogenesis and the immune response of the host. Some of these structures can be specifically recognized by antibodies from patients’ sera, suggesting that they can be also useful in the diagnosis of fungal infections.
Collapse
Affiliation(s)
- M R Pinto
- Instituto de Ciências Biomédicas, Departamento de Microbiologia, Universidade de São Paulo , São Paulo, SP , Brasil
| | | | | |
Collapse
|
47
|
Klutts JS, Doering TL. Cryptococcal xylosyltransferase 1 (Cxt1p) from Cryptococcus neoformans plays a direct role in the synthesis of capsule polysaccharides. J Biol Chem 2008; 283:14327-34. [PMID: 18347023 PMCID: PMC2386922 DOI: 10.1074/jbc.m708927200] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 03/14/2008] [Indexed: 01/26/2023] Open
Abstract
The opportunistic yeast Cryptococcus neoformans causes serious disease in humans and expresses a prominent polysaccharide capsule that is required for its virulence. Little is known about how this capsule is synthesized. We previously identified a beta1,2-xylosyltransferase (Cxt1p) with in vitro enzymatic activity appropriate for involvement in capsule synthesis. Here, we investigate C. neoformans strains in which the corresponding gene has been deleted (cxt1Delta). Loss of CXT1 does not affect in vitro growth of the mutant cells or the general morphology of their capsules. However, NMR structural analysis of the two main capsule polysaccharides, glucuronoxylomannan (GXM) and galactoxylomannan (GalXM), showed that both were missing beta1,2-xylose residues. There was an approximately 30% reduction in the abundance of this residue in GXM in mutant compared with wild-type strains, and mutant GalXM was almost completely devoid of beta1,2-linked xylose. The GalXM from the mutant strain was also missing a beta1,3-linked xylose residue. Furthermore, deletion of CXT1 led to attenuation of cryptococcal growth in a mouse model of infection, suggesting that the affected xylose residues are important for normal host-pathogen interactions. Cxt1p is the first glycosyltransferase with a defined role in C. neoformans capsule biosynthesis, and cxt1Delta is the only strain identified to date with structural alterations of the capsule polysaccharide GalXM.
Collapse
Affiliation(s)
- J Stacey Klutts
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110, USA
| | | |
Collapse
|
48
|
Villena SN, Pinheiro RO, Pinheiro CS, Nunes MP, Takiya CM, DosReis GA, Previato JO, Mendonça-Previato L, Freire-de-Lima CG. Capsular polysaccharides galactoxylomannan and glucuronoxylomannan from Cryptococcus neoformans induce macrophage apoptosis mediated by Fas ligand. Cell Microbiol 2008; 10:1274-85. [PMID: 18284419 DOI: 10.1111/j.1462-5822.2008.01125.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effects of capsular polysaccharides, galactoxylomannan (GalXM) and glucuronoxylomannan (GXM), from acapsular (GXM negative) and encapsulate strains of Cryptococcus neoformans were investigated in RAW 264.7 and peritoneal macrophages. Here, we demonstrate that GalXM and GXM induced different cytokines profiles in RAW 264.7 macrophages. GalXM induced production of TNF-alpha, NO and iNOS expression, while GXM predominantly induced TGF-beta secretion. Both GalXM and GXM induced early morphological changes identified as autophagy and late macrophages apoptosis mediated by Fas/FasL interaction, a previously unidentified mechanism of virulence. GalXM was more potent than GXM at induction of Fas/FasL expression and apoptosis on macrophages in vitro and in vivo. These findings uncover a mechanism by which capsular polysaccharides from C. neoformans might compromise host immune responses.
Collapse
Affiliation(s)
- Suellen N Villena
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21 944970, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ, Brazil
| | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Cryptococcus neoformans capsular polysaccharide and exopolysaccharide fractions manifest physical, chemical, and antigenic differences. EUKARYOTIC CELL 2007; 7:319-27. [PMID: 18156290 DOI: 10.1128/ec.00378-07] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The human pathogenic fungus Cryptococcus neoformans has a large polysaccharide (PS) capsule and releases copious amounts of PS into cultures and infected tissues. The capsular PS is a major virulence factor that can elicit protective antibody responses. PS recovered from culture supernatants has historically provided an ample and convenient source of material for structural and immunological studies. Two major assumptions in such studies are that the structural features of the exopolysaccharide material faithfully mirror those of capsular PS and that the isolation methods do not change PS properties. However, a comparison of exopolysaccharide made by two isolation techniques with capsular PS stripped from cells with gamma radiation or dimethyl sulfoxide revealed significant differences in glycosyl composition, mass, size, charge, viscosity, circular-dichroism spectra, and reactivity with monoclonal antibodies. Our results strongly suggest that exopolysaccharides and capsular PS are structurally different. A noteworthy finding was that PS made by cetyltrimethylammonium bromide precipitation had a larger mass and a different conformation than PS isolated by concentration and filtration, suggesting that the method most commonly used to purify glucuronoxylomannan alters the PS. Hence, the method used to isolate PS can significantly influence the structural and antigenic properties of the product. Our findings have important implications for current views of the relationship between capsular PS and exopolysaccharides, for the generation of PS preparations suitable for immunological studies, and for the formulation of PS-based vaccines for the prevention of cryptococcosis.
Collapse
|
50
|
Binding of the wheat germ lectin to Cryptococcus neoformans suggests an association of chitinlike structures with yeast budding and capsular glucuronoxylomannan. EUKARYOTIC CELL 2007; 7:602-9. [PMID: 18039942 DOI: 10.1128/ec.00307-07] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The capsule of Cryptococcus neoformans is a complex structure whose assembly requires intermolecular interactions to connect its components into an organized structure. In this study, we demonstrated that the wheat germ agglutinin (WGA), which binds to sialic acids and beta-1,4-N-acetylglucosamine (GlcNAc) oligomers, can also bind to cryptococcal capsular structures. Confocal microscopy demonstrated that these structures form round or hooklike projections linking the capsule to the cell wall, as well as capsule-associated structures during yeast budding. Chemical analysis of capsular extracts by gas chromatography coupled to mass spectrometry and high-pH anion-exchange chromatography suggested that the molecules recognized by WGA were firmly associated with the cell wall. Enzymatic treatment, competition assays, and staining with chemically modified WGA revealed that GlcNAc oligomers, but not sialic acids, were the molecules recognized by the lectin. Accordingly, treatment of C. neoformans cells with chitinase released glucuronoxylomannan (GXM) from the cell surface and reduced the capsule size. Chitinase-treated acapsular cells bound soluble GXM in a modified pattern. These results indicate an association of chitin-derived structures with GXM and budding in C. neoformans, which may represent a new mechanism by which the capsular polysaccharide interacts with the cell wall and is rearranged during replication.
Collapse
|