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Wang X, Zhou WT, Dong HH, Li CY, Jiang YY, Xie P, Xu ZY, Xie SH, Yang SX, Huang L, Chen H, Wang LY, Wei X, Huang YQ. Isobavachalcone: A redox antifungal agent impairs the mitochondria protein of Cryptococcus neoformans. Int J Antimicrob Agents 2024; 64:107253. [PMID: 38925229 DOI: 10.1016/j.ijantimicag.2024.107253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 04/30/2024] [Accepted: 06/13/2024] [Indexed: 06/28/2024]
Abstract
Isobavachalcone (IBC) is a natural small molecule with various biological activities; however, its inhibitory effects on Cryptococcus neoformans remain unclear. In our study, IBC showed a good antifungal effect. Through in vitro experiments, its minimum inhibitory concentration was 0.5-1 µg/mL. It exhibited the same antifungal effect as Amphotericin B in brain and lung infections in in vivo experiments. IBC also showed a synergistic antifungal effect with emodin with lower toxicity, and C. neoformans did not develop drug resistance to IBC. In the mechanistic study, significantly damaged mitochondria of C. neoformans, a significant reduction in mitochondrial membrane potential and adenosine triphosphate production, and an increase in hydrogen peroxide (H2O2) caused by IBC were observed using transmission electron microscopy. Through drug affinity-responsive target stability combined with phenotype detection, riboflavin synthases of aconitase and succinate dehydrogenase were screened. Molecular docking, quantitative polymerase chain reaction experiments, target inhibitor and agonist intervention, molecular interaction measurements, and minimum inhibitory concentration detection of the constructed expression strains revealed that IBC targeted the activity of these two enzymes, interfered by the tricarboxylic acid cycle, inhibited the production of adenosine triphosphate, blocked electron transport, reduced mitochondrial membrane potential, and induced antioxidation imbalance and reactive oxygen species accumulation, thus producing an antifungal effect. Therefore, IBC is a promising lead drug and redox antifungal agent for C. neoformans.
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Affiliation(s)
- Xue Wang
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China; Graduate School of Youjiang Medical University for Nationalities, Baise, China
| | - Wen-Ting Zhou
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China; Graduate School of Youjiang Medical University for Nationalities, Baise, China
| | - Hui-Hua Dong
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China; Graduate School of Youjiang Medical University for Nationalities, Baise, China
| | - Chen-Yan Li
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China; Graduate School of Youjiang Medical University for Nationalities, Baise, China
| | - Yu-Ying Jiang
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China; Graduate School of Youjiang Medical University for Nationalities, Baise, China
| | - Ping Xie
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China; Graduate School of Youjiang Medical University for Nationalities, Baise, China
| | - Zhen-Yi Xu
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China; Graduate School of Youjiang Medical University for Nationalities, Baise, China
| | - Shuo-Hua Xie
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China; Graduate School of Youjiang Medical University for Nationalities, Baise, China
| | - Shi-Xian Yang
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China
| | - Liang Huang
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China
| | - Hao Chen
- Department of Pathology, Wannan Medical College, Wuhu, China
| | - Lu-Yao Wang
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China.
| | - Xian Wei
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China.
| | - Yan-Qiang Huang
- Guangxi Technology Innovation Cooperation Base of Prevention and Control Pathogenic Microbes with Drug Resistance, Youjiang Medical University for Nationalities, Baise, China; Education Department of Guangxi Zhuang Autonomous Region, Key Laboratory of the Prevention and Treatment of Drug Resistant Microbial Infecting, Youjiang Medical University for Nationalities, Baise, China.
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2
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Mukherjee A, Ghosh KK, Chakrabortty S, Gulyás B, Padmanabhan P, Ball WB. Mitochondrial Reactive Oxygen Species in Infection and Immunity. Biomolecules 2024; 14:670. [PMID: 38927073 PMCID: PMC11202257 DOI: 10.3390/biom14060670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 06/04/2024] [Accepted: 06/05/2024] [Indexed: 06/28/2024] Open
Abstract
Reactive oxygen species (ROS) contain at least one oxygen atom and one or more unpaired electrons and include singlet oxygen, superoxide anion radical, hydroxyl radical, hydroperoxyl radical, and free nitrogen radicals. Intracellular ROS can be formed as a consequence of several factors, including ultra-violet (UV) radiation, electron leakage during aerobic respiration, inflammatory responses mediated by macrophages, and other external stimuli or stress. The enhanced production of ROS is termed oxidative stress and this leads to cellular damage, such as protein carbonylation, lipid peroxidation, deoxyribonucleic acid (DNA) damage, and base modifications. This damage may manifest in various pathological states, including ageing, cancer, neurological diseases, and metabolic disorders like diabetes. On the other hand, the optimum levels of ROS have been implicated in the regulation of many important physiological processes. For example, the ROS generated in the mitochondria (mitochondrial ROS or mt-ROS), as a byproduct of the electron transport chain (ETC), participate in a plethora of physiological functions, which include ageing, cell growth, cell proliferation, and immune response and regulation. In this current review, we will focus on the mechanisms by which mt-ROS regulate different pathways of host immune responses in the context of infection by bacteria, protozoan parasites, viruses, and fungi. We will also discuss how these pathogens, in turn, modulate mt-ROS to evade host immunity. We will conclude by briefly giving an overview of the potential therapeutic approaches involving mt-ROS in infectious diseases.
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Affiliation(s)
- Arunima Mukherjee
- Department of Biological Sciences, School of Engineering and Sciences, SRM University AP Andhra Pradesh, Guntur 522502, Andhra Pradesh, India;
| | - Krishna Kanta Ghosh
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore 636921, Singapore; (K.K.G.); (B.G.)
| | - Sabyasachi Chakrabortty
- Department of Chemistry, School of Engineering and Sciences, SRM University AP Andhra Pradesh, Guntur 522502, Andhra Pradesh, India;
| | - Balázs Gulyás
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore 636921, Singapore; (K.K.G.); (B.G.)
- Cognitive Neuroimaging Centre, 59 Nanyang Drive, Nanyang Technological University, Singapore 636921, Singapore
- Department of Clinical Neuroscience, Karolinska Institute, 17176 Stockholm, Sweden
| | - Parasuraman Padmanabhan
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore 636921, Singapore; (K.K.G.); (B.G.)
- Cognitive Neuroimaging Centre, 59 Nanyang Drive, Nanyang Technological University, Singapore 636921, Singapore
| | - Writoban Basu Ball
- Department of Biological Sciences, School of Engineering and Sciences, SRM University AP Andhra Pradesh, Guntur 522502, Andhra Pradesh, India;
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3
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Xue P, Sánchez-León E, Hu G, Lee CWJ, Black B, Brisland A, Li H, Jung WH, Kronstad JW. The interplay between electron transport chain function and iron regulatory factors influences melanin formation in Cryptococcus neoformans. mSphere 2024; 9:e0025024. [PMID: 38687055 PMCID: PMC11237718 DOI: 10.1128/msphere.00250-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 03/28/2024] [Indexed: 05/02/2024] Open
Abstract
Mitochondrial functions are critical for the ability of the fungal pathogen Cryptococcus neoformans to cause disease. However, mechanistic connections between key functions such as the mitochondrial electron transport chain (ETC) and virulence factor elaboration have yet to be thoroughly characterized. Here, we observed that inhibition of ETC complex III suppressed melanin formation, a major virulence factor. This inhibition was partially overcome by defects in Cir1 or HapX, two transcription factors that regulate iron acquisition and use. In this regard, loss of Cir1 derepresses the expression of laccase genes as a potential mechanism to restore melanin, while HapX may condition melanin formation by controlling oxidative stress. We hypothesize that ETC dysfunction alters redox homeostasis to influence melanin formation. Consistent with this idea, inhibition of growth by hydrogen peroxide was exacerbated in the presence of the melanin substrate L-DOPA. In addition, loss of the mitochondrial chaperone Mrj1, which influences the activity of ETC complex III and reduces ROS accumulation, also partially overcame antimycin A inhibition of melanin. The phenotypic impact of mitochondrial dysfunction was consistent with RNA-Seq analyses of WT cells treated with antimycin A or L-DOPA, or cells lacking Cir1 that revealed influences on transcripts encoding mitochondrial functions (e.g., ETC components and proteins for Fe-S cluster assembly). Overall, these findings reveal mitochondria-nuclear communication via ROS and iron regulators to control virulence factor production in C. neoformans.IMPORTANCEThere is a growing appreciation of the importance of mitochondrial functions and iron homeostasis in the ability of fungal pathogens to sense the vertebrate host environment and cause disease. Many mitochondrial functions such as heme and iron-sulfur cluster biosynthesis, and the electron transport chain (ETC), are dependent on iron. Connections between factors that regulate iron homeostasis and mitochondrial activities are known in model yeasts and are emerging for fungal pathogens. In this study, we identified connections between iron regulatory transcription factors (e.g., Cir1 and HapX) and the activity of complex III of the ETC that influence the formation of melanin, a key virulence factor in the pathogenic fungus Cryptococcus neoformans. This fungus causes meningoencephalitis in immunocompromised people and is a major threat to the HIV/AIDS population. Thus, understanding how mitochondrial functions influence virulence may support new therapeutic approaches to combat diseases caused by C. neoformans and other fungi.
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Affiliation(s)
- Peng Xue
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eddy Sánchez-León
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Guanggan Hu
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher W J Lee
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Braydon Black
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Anna Brisland
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Haohua Li
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Won Hee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong, South Korea
| | - James W Kronstad
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
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4
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Edrich ESM, Duvenage L, Gourlay CW. Alternative Oxidase - Aid or obstacle to combat the rise of fungal pathogens? BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2024; 1865:149031. [PMID: 38195037 DOI: 10.1016/j.bbabio.2024.149031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 11/16/2023] [Accepted: 01/03/2024] [Indexed: 01/11/2024]
Abstract
Fungal pathogens present a growing threat to both humans and global health security alike. Increasing evidence of antifungal resistance in fungal populations that infect both humans and plant species has increased reliance on combination therapies and shown the need for new antifungal therapeutic targets to be investigated. Here, we review the roles of mitochondria and fungal respiration in pathogenesis and discuss the role of the Alternative Oxidase enzyme (Aox) in both human fungal pathogens and phytopathogens. Increasing evidence exists for Aox within mechanisms that underpin fungal virulence. Aox also plays important roles in adaptability that may prove useful within dual targeted fungal-specific therapeutic approaches. As improved fungal specific mitochondrial and Aox inhibitors are under development we may see this as an emerging target for future approaches to tackling the growing challenge of fungal infection.
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Affiliation(s)
| | - Lucian Duvenage
- CMM AFRICA Medical Mycology Research Unit, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Campbell W Gourlay
- Kent Fungal Group, School of Biosciences, University of Kent, Kent CT2 9HY, UK.
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5
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Li J, Yang S, Wu Y, Wang R, Liu Y, Liu J, Ye Z, Tang R, Whiteway M, Lv Q, Yan L. Alternative Oxidase: From Molecule and Function to Future Inhibitors. ACS OMEGA 2024; 9:12478-12499. [PMID: 38524433 PMCID: PMC10955580 DOI: 10.1021/acsomega.3c09339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 01/31/2024] [Accepted: 02/07/2024] [Indexed: 03/26/2024]
Abstract
In the respiratory chain of the majority of aerobic organisms, the enzyme alternative oxidase (AOX) functions as the terminal oxidase and has important roles in maintaining metabolic and signaling homeostasis in mitochondria. AOX endows the respiratory system with flexibility in the coupling among the carbon metabolism pathway, electron transport chain (ETC) activity, and ATP turnover. AOX allows electrons to bypass the main cytochrome pathway to restrict the generation of reactive oxygen species (ROS). The inhibition of AOX leads to oxidative damage and contributes to the loss of adaptability and viability in some pathogenic organisms. Although AOXs have recently been identified in several organisms, crystal structures and major functions still need to be explored. Recent work on the trypanosome alternative oxidase has provided a crystal structure of an AOX protein, which contributes to the structure-activity relationship of the inhibitors of AOX. Here, we review the current knowledge on the development, structure, and properties of AOXs, as well as their roles and mechanisms in plants, animals, algae, protists, fungi, and bacteria, with a special emphasis on the development of AOX inhibitors, which will improve the understanding of respiratory regulation in many organisms and provide references for subsequent studies of AOX-targeted inhibitors.
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Affiliation(s)
- Jiye Li
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
- Institute
of Medicinal Biotechnology, Chinese Academy
of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Shiyun Yang
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Yujie Wu
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Ruina Wang
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Yu Liu
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Jiacun Liu
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Zi Ye
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Renjie Tang
- Beijing
South Medical District of Chinese PLA General Hospital, Beijing 100072, China
| | - Malcolm Whiteway
- Department
of Biology, Concordia University, Montreal, H4B 1R6 Quebec, Canada
| | - Quanzhen Lv
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
- Basic
Medicine Innovation Center for Fungal Infectious Diseases, (Naval Medical University), Ministry of Education, Shanghai 200433, China
- Key
Laboratory of Biosafety Defense (Naval Medical University), Ministry
of Education, Shanghai 200433, China
- Shanghai
Key Laboratory of Medical Biodefense, Shanghai 200433, China
| | - Lan Yan
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
- Basic
Medicine Innovation Center for Fungal Infectious Diseases, (Naval Medical University), Ministry of Education, Shanghai 200433, China
- Key
Laboratory of Biosafety Defense (Naval Medical University), Ministry
of Education, Shanghai 200433, China
- Shanghai
Key Laboratory of Medical Biodefense, Shanghai 200433, China
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6
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Xue P, Sánchez-León E, Hu G, Lee CWJ, Black B, Brisland A, Li H, Jung WH, Kronstad JW. The interplay between electron transport chain function and iron regulatory factors influences melanin formation in Cryptococcus neoformans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.15.580540. [PMID: 38405941 PMCID: PMC10888943 DOI: 10.1101/2024.02.15.580540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Mitochondrial functions are critical for the ability of the fungal pathogen Cryptococcus neoformans to cause disease. However, mechanistic connections between key functions such as the mitochondrial electron transport chain (ETC) and virulence factor elaboration have yet to be thoroughly characterized. Here, we observed that inhibition of ETC complex III suppressed melanin formation, a major virulence factor. This inhibition was partially blocked upon loss of Cir1 or HapX, two transcription factors that regulate iron acquisition and use. In this regard, loss of Cir1 derepresses the expression of laccase genes as a potential mechanism to restore melanin, while HapX may condition melanin formation by controlling oxidative stress. We hypothesize that ETC dysfunction alters redox homeostasis to influence melanin formation. Consistent with this idea, inhibition of growth by hydrogen peroxide was exacerbated in the presence of the melanin substrate L-DOPA. Additionally, loss of the mitochondrial chaperone Mrj1, which influences the activity of ETC complex III and reduces ROS accumulation, also partially blocked antimycin A inhibition of melanin. The phenotypic impact of mitochondrial dysfunction was consistent with RNA-Seq analyses of WT cells treated with antimycin A or L-DOPA, or cells lacking Cir1 that revealed influences on transcripts encoding mitochondrial functions (e.g., ETC components and proteins for Fe-S cluster assembly). Overall, these findings reveal mitochondria-nuclear communication via ROS and iron regulators to control virulence factor production in C. neoformans.
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Affiliation(s)
- Peng Xue
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
- Present address: Nantong Key Laboratory of Environmental Toxicology, Department of Occupational Medicine and Environmental Toxicology, School of Public Health, Nantong University, Nantong, Jiangsu, China
| | - Eddy Sánchez-León
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Guanggan Hu
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher WJ Lee
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Braydon Black
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Anna Brisland
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Haohua Li
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Won Hee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong, Republic of Korea
| | - James W. Kronstad
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
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Berguson HP, Caulfield LW, Price MS. Influence of Pathogen Carbon Metabolism on Interactions With Host Immunity. Front Cell Infect Microbiol 2022; 12:861405. [PMID: 35372116 PMCID: PMC8968422 DOI: 10.3389/fcimb.2022.861405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 02/24/2022] [Indexed: 11/22/2022] Open
Abstract
Cryptococcus neoformans is a ubiquitous opportunistic fungal pathogen typically causing disease in immunocompromised individuals and is globally responsible for about 15% of AIDS-related deaths annually. C. neoformans first causes pulmonary infection in the host and then disseminates to the brain, causing meningoencephalitis. The yeast must obtain and metabolize carbon within the host in order to survive in the central nervous system and cause disease. Communication between pathogen and host involves recognition of multiple carbon-containing compounds on the yeast surface: polysaccharide capsule, fungal cell wall, and glycosylated proteins comprising the major immune modulators. The structure and function of polysaccharide capsule has been studied for the past 70 years, emphasizing its role in virulence. While protected by the capsule, fungal cell wall has likewise been a focus of study for several decades for its role in cell integrity and host recognition. Associated with both of these major structures are glycosylated proteins, which exhibit known immunomodulatory effects. While many studies have investigated the role of carbon metabolism on virulence and survival within the host, the precise mechanism(s) affecting host-pathogen communication remain ill-defined. This review summarizes the current knowledge on mutants in carbon metabolism and their effect on the host immune response that leads to changes in pathogen recognition and virulence. Understanding these critical interactions will provide fresh perspectives on potential treatments and the natural history of cryptococcal disease.
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Affiliation(s)
- Hannah P. Berguson
- Department of Anatomical Sciences, Liberty University College of Osteopathic Medicine, Lynchburg, VA, United States
| | - Lauren W. Caulfield
- Department of Biology and Chemistry, Liberty University, Lynchburg, VA, United States
| | - Michael S. Price
- Department of Molecular and Cellular Sciences, Liberty University College of Osteopathic Medicine, Lynchburg, VA, United States
- Department of Medicine, Duke University School of Medicine, Durham, NC, United States
- *Correspondence: Michael S. Price,
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8
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X-linked immunodeficient (XID) mice exhibit high susceptibility to Cryptococcus gattii infection. Sci Rep 2021; 11:18397. [PMID: 34526536 PMCID: PMC8443669 DOI: 10.1038/s41598-021-97041-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 08/19/2021] [Indexed: 12/12/2022] Open
Abstract
Cryptococcosis is an opportunistic disease caused by the fungus Cryptococcus neoformans and Cryptococcus gattii. It starts as a pulmonary infection that can spread to other organs, such as the brain, leading to the most serious occurrence of the disease, meningoencephalitis. The humoral response has already been described in limiting the progression of cryptococcosis where the B-1 cell seems to be responsible for producing natural IgM antibodies, crucial for combating fungal infections. The role of the B-1 cell in C. neoformans infection has been initially described, however the role of the humoral response of B-1 cells has not yet been evaluated during C. gattii infections. In the present study we tried to unravel this issue using XID mice, a murine model deficient in the Btk protein which compromises the development of B-1 lymphocytes. We use the XID mice compared to BALB/c mice that are sufficient for the B-1 population during C. gattii infection. Our model of chronic lung infection revealed that XID mice, unlike the sufficient group of B-1, had early mortality with significant weight loss, in addition to reduced levels of IgM and IgG specific to GXM isolated from the capsule of C. neoformans. In addition to this, we observed an increased fungal load in the blood and in the brain. We described an increase in the capsular size of C. gattii and the predominant presence of cytokines with a Th2 profile was also observed in these animals. Thus, the present study strongly points to a higher susceptibility of the XID mouse to C. gattii, which suggests that the presence of B-1 cells and anti-GXM antibodies is fundamental during the control of infection by C. gattii.
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Black B, Lee C, Horianopoulos LC, Jung WH, Kronstad JW. Respiring to infect: Emerging links between mitochondria, the electron transport chain, and fungal pathogenesis. PLoS Pathog 2021; 17:e1009661. [PMID: 34237096 PMCID: PMC8266039 DOI: 10.1371/journal.ppat.1009661] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- Braydon Black
- Michael Smith Laboratories, Department of Microbiology & Immunology, University of British Columbia, Vancouver, Canada
| | - Christopher Lee
- Michael Smith Laboratories, Department of Microbiology & Immunology, University of British Columbia, Vancouver, Canada
| | - Linda C. Horianopoulos
- Michael Smith Laboratories, Department of Microbiology & Immunology, University of British Columbia, Vancouver, Canada
| | - Won Hee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong, Republic of Korea
| | - James W. Kronstad
- Michael Smith Laboratories, Department of Microbiology & Immunology, University of British Columbia, Vancouver, Canada
- * E-mail:
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Bhattacharya S, Oliveira NK, Savitt AG, Silva VKA, Krausert RB, Ghebrehiwet B, Fries BC. Low Glucose Mediated Fluconazole Tolerance in Cryptococcus neoformans. J Fungi (Basel) 2021; 7:jof7060489. [PMID: 34207384 PMCID: PMC8233753 DOI: 10.3390/jof7060489] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/13/2021] [Accepted: 06/16/2021] [Indexed: 01/07/2023] Open
Abstract
Chronic meningoencephalitis is caused by Cryptococcus neoformans and is treated in many parts of the world with fluconazole (FLC) monotherapy, which is associated with treatment failure and poor outcome. In the host, C. neoformans propagates predominantly under low glucose growth conditions. We investigated whether low glucose, mimicked by growing in synthetic media (SM) with 0.05% glucose (SMlowglu), affects FLC-resistance. A > 4-fold increase in FLC tolerance was observed in seven C. neoformans strains when minimum inhibitory concentration (MIC) was determined in SMlowglu compared to MIC in SM with normal (2%) glucose (SMnlglu). In SMlowglu, C. neoformans cells exhibited upregulation of efflux pump genes AFR1 (8.7-fold) and AFR2 (2.5-fold), as well as decreased accumulation (2.6-fold) of Nile Red, an efflux pump substrate. Elevated intracellular ATP levels (3.2-fold and 3.4-fold), as well as decreased mitochondrial reactive oxygen species levels (12.8-fold and 17-fold), were found in the presence and absence of FLC, indicating that low glucose altered mitochondrial function. Fluorescence microscopy revealed that mitochondria of C. neoformans grown in SMlowglu were fragmented, whereas normal glucose promoted a reticular network of mitochondria. Although mitochondrial membrane potential (MMP) was not markedly affected in SMlowglu, it significantly decreased in the presence of FLC (12.5-fold) in SMnlglu, but remained stable in SMlowglu-growing C. neoformans cells. Our data demonstrate that increased FLC tolerance in low glucose-growing C. neoformans is the result of increased efflux pump activities and altered mitochondrial function, which is more preserved in SMlowglu. This mechanism of resistance is different from FLC heteroresistance, which is associated with aneuploidy of chromosome 1 (Chr1).
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Affiliation(s)
- Somanon Bhattacharya
- Division of Infectious Diseases, Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; (S.B.); (V.K.A.S.)
| | - Natalia Kronbauer Oliveira
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; (N.K.O.); (A.G.S.); (R.B.K.)
| | - Anne G. Savitt
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; (N.K.O.); (A.G.S.); (R.B.K.)
| | - Vanessa K. A. Silva
- Division of Infectious Diseases, Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; (S.B.); (V.K.A.S.)
| | - Rachel B. Krausert
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; (N.K.O.); (A.G.S.); (R.B.K.)
| | - Berhane Ghebrehiwet
- Division of Rheumatology, Allergy and Immunology, Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA;
| | - Bettina C. Fries
- Division of Infectious Diseases, Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; (S.B.); (V.K.A.S.)
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; (N.K.O.); (A.G.S.); (R.B.K.)
- Veterans Administration Medical Center, Northport, NY 11768, USA
- Correspondence:
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Lev S, Li C, Desmarini D, Liuwantara D, Sorrell TC, Hawthorne WJ, Djordjevic JT. Monitoring Glycolysis and Respiration Highlights Metabolic Inflexibility of Cryptococcus neoformans. Pathogens 2020; 9:pathogens9090684. [PMID: 32839374 PMCID: PMC7559270 DOI: 10.3390/pathogens9090684] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/13/2020] [Accepted: 08/20/2020] [Indexed: 12/14/2022] Open
Abstract
Cryptococcus neoformans is a human fungal pathogen that adapts its metabolism to cope with limited oxygen availability, nutrient deprivation and host phagocytes. To gain insight into cryptococcal metabolism, we optimized a protocol for the Seahorse Analyzer, which measures extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) as indications of glycolytic and respiratory activities. In doing so we achieved effective immobilization of encapsulated cryptococci, established Rotenone/Antimycin A and 2-deoxyglucose as effective inhibitors of mitochondrial respiration and glycolysis, respectively, and optimized a microscopy-based method of data normalization. We applied the protocol to monitor metabolic changes in the pathogen alone and in co-culture with human blood-derived monocytes. We also compared metabolic flux in wild-type C. neoformans, its isogenic 5-PP-IP5/IP7-deficient metabolic mutant kcs1∆, the sister species of C. neoformans, Cryptococcus deuterogattii/VGII, and two other yeasts, Saccharomyces cerevisiae and Candida albicans. Our findings show that in contrast to monocytes and C. albicans, glycolysis and respiration are tightly coupled in C. neoformans and C. deuterogattii, as no compensatory increase in glycolysis occurred following inhibition of respiration. We also demonstrate that kcs1∆ has reduced metabolic activity that correlates with reduced mitochondrial function. Metabolic inflexibility in C. neoformans is therefore consistent with its obligate aerobe status and coincides with phagocyte tolerance of ingested cryptococcal cells.
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Affiliation(s)
- Sophie Lev
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia; (S.L.); (C.L.); (D.D.); (T.C.S.)
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW 2050, Australia
| | - Cecilia Li
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia; (S.L.); (C.L.); (D.D.); (T.C.S.)
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia; (S.L.); (C.L.); (D.D.); (T.C.S.)
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW 2050, Australia
| | - David Liuwantara
- Centre for Transplant and Renal Research, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia;
| | - Tania C. Sorrell
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia; (S.L.); (C.L.); (D.D.); (T.C.S.)
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW 2050, Australia
| | - Wayne J. Hawthorne
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
- Centre for Transplant and Renal Research, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia;
| | - Julianne T. Djordjevic
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia; (S.L.); (C.L.); (D.D.); (T.C.S.)
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW 2050, Australia
- Correspondence:
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12
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Young L, Rosell-Hidalgo A, Inaoka DK, Xu F, Albury M, May B, Kita K, Moore AL. Kinetic and structural characterisation of the ubiquinol-binding site and oxygen reduction by the trypanosomal alternative oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148247. [PMID: 32565080 DOI: 10.1016/j.bbabio.2020.148247] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 06/08/2020] [Accepted: 06/12/2020] [Indexed: 12/15/2022]
Abstract
The alternative oxidase (AOX) is a monotopic di‑iron carboxylate protein which acts as a terminal respiratory chain oxidase in a variety of plants, fungi and protists. Of particular importance is the finding that both emerging infectious diseases caused by human and plant fungal pathogens, the majority of which are multi-drug resistant, appear to be dependent upon AOX activity for survival. Since AOX is absent in mammalian cells, AOX is considered a viable therapeutic target for the design of specific fungicidal and anti-parasitic drugs. In this work, we have mutated conserved residues within the hydrophobic channel (R96, D100, R118, L122, L212, E215 and T219), which crystallography has indicated leads to the active site. Our data shows that all mutations result in a drastic reduction in Vmax and catalytic efficiency whilst some also affected the Km for quinol and oxygen. The extent to which mutation effects inhibitor sensitivity was also investigated, with mutation of R118 and T219 leading to a complete loss of inhibitor potency. However, only a slight reduction in IC50 values was observed when R96 was mutated, implying that this residue is less important in inhibitor binding. In silico modelling has been used to provide insight into the reason for such changes, which we suggest is due to disruptions in the proton transfer network, resulting in a reduction in overall reaction kinetics. We discuss our results in terms of the structural features of the ubiquinol binding site and consider the implications of such findings on the nature of the catalytic cycle. SIGNIFICANCE: The alternative oxidase is a ubiquinol oxidoreductase enzyme that catalyses the oxidation of ubiquinol and the reduction of oxygen to water. It is widely distributed amongst the plant, fungal and parasitic kingdoms and plays a central role in metabolism through facilitating the turnover of the TCA cycle whilst reducing ROS production.
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Affiliation(s)
- Luke Young
- Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom.
| | - Alicia Rosell-Hidalgo
- Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom
| | - Daniel Ken Inaoka
- Department of Molecular Infection Dynamics, Shinogi Global Infectious Diseases Division, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki 852-8523, Japan; School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki 852-8523, Japan
| | - Fei Xu
- Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom
| | - Mary Albury
- Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom
| | - Benjamin May
- Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom
| | - Kiyoshi Kita
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki 852-8523, Japan
| | - Anthony L Moore
- Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom
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The Novel J-Domain Protein Mrj1 Is Required for Mitochondrial Respiration and Virulence in Cryptococcus neoformans. mBio 2020; 11:mBio.01127-20. [PMID: 32518190 PMCID: PMC7373193 DOI: 10.1128/mbio.01127-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cryptococcus neoformans is the causative agent of cryptococcal meningitis, a disease responsible for ∼15% of all HIV-related deaths. Unfortunately, development of antifungal drugs is challenging because potential targets are conserved between humans and C. neoformans. In this context, we characterized a unique J-domain protein, Mrj1, which lacks orthologs in humans. We showed that Mrj1 was required for normal mitochondrial respiration and that mutants lacking Mrj1 were deficient in growth, capsule elaboration, and virulence. Furthermore, we were able to phenocopy the defects in growth and capsule elaboration by inhibiting respiration. This result suggests that the role of Mrj1 in mitochondrial function was responsible for the observed virulence defects and reinforces the importance of mitochondria to fungal pathogenesis. Mitochondria are difficult to target, as their function is also key to human cells; however, Mrj1 presents an opportunity to target a unique fungal protein required for mitochondrial function and virulence in C. neoformans. The opportunistic fungal pathogen Cryptococcus neoformans must adapt to the mammalian environment to establish an infection. Proteins facilitating adaptation to novel environments, such as chaperones, may be required for virulence. In this study, we identified a novel mitochondrial co-chaperone, Mrj1 (mitochondrial respiration J-domain protein 1), necessary for virulence in C. neoformans. The mrj1Δ and J-domain-inactivated mutants had general growth defects at both routine laboratory and human body temperatures and were deficient in the major virulence factor of capsule elaboration. The latter phenotype was associated with cell wall changes and increased capsular polysaccharide shedding. Accordingly, the mrj1Δ mutant was avirulent in a murine model of cryptococcosis. Mrj1 has a mitochondrial localization and co-immunoprecipitated with Qcr2, a core component of complex III of the electron transport chain. The mrj1 mutants were deficient in mitochondrial functions, including growth on alternative carbon sources, growth without iron, and mitochondrial polarization. They were also insensitive to complex III inhibitors and hypersensitive to an alternative oxidase (AOX) inhibitor, suggesting that Mrj1 functions in respiration. In support of this conclusion, mrj1 mutants also had elevated basal oxygen consumption rates which were completely abolished by the addition of the AOX inhibitor, confirming that Mrj1 is required for mitochondrial respiration through complexes III and IV. Furthermore, inhibition of complex III phenocopied the capsule and cell wall defects of the mrj1 mutants. Taken together, these results indicate that Mrj1 is required for normal mitochondrial respiration, a key aspect of adaptation to the host environment and virulence.
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14
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Maliehe M, Ntoi MA, Lahiri S, Folorunso OS, Ogundeji AO, Pohl CH, Sebolai OM. Environmental Factors That Contribute to the Maintenance of Cryptococcus neoformans Pathogenesis. Microorganisms 2020; 8:microorganisms8020180. [PMID: 32012843 PMCID: PMC7074686 DOI: 10.3390/microorganisms8020180] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/04/2019] [Accepted: 12/11/2019] [Indexed: 02/07/2023] Open
Abstract
The ability of microorganisms to colonise and display an intracellular lifestyle within a host body increases their fitness to survive and avoid extinction. This host–pathogen association drives microbial evolution, as such organisms are under selective pressure and can become more pathogenic. Some of these microorganisms can quickly spread through the environment via transmission. The non-transmittable fungal pathogens, such as Cryptococcus, probably return into the environment upon decomposition of the infected host. This review analyses whether re-entry of the pathogen into the environment causes restoration of its non-pathogenic state or whether environmental factors and parameters assist them in maintaining pathogenesis. Cryptococcus (C.) neoformans is therefore used as a model organism to evaluate the impact of environmental stress factors that aid the survival and pathogenesis of C. neoformans intracellularly and extracellularly.
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15
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Chung KY, Brown JCS. Biology and function of exo-polysaccharides from human fungal pathogens. CURRENT CLINICAL MICROBIOLOGY REPORTS 2020; 7:1-11. [PMID: 33042730 DOI: 10.1007/s40588-020-00137-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Purpose of review Environmental fungi such as Cryptococcus neoformans and Aspergillus fumigatus must survive many different and changing environments as they transition from their environmental niches to human lungs and other organs. Fungi alter their cell surfaces and secreted macromolecules to respond to and manipulate their surroundings. Recent findings This review focuses on exo-polysaccharides, chains of sugars that transported out of the cell and spread to the local environment. Major exo-polysaccharides for C. neoformans and A. fumigatus are glucuronylxylomannan (GXM) and galactosaminogalactan (GAG), respectively, which accumulate at high concentrations in growth medium and infected patients. Summary Here we discuss GXM and GAG synthesis and export, their immunomodulatory properties, and their roles in biofilm formation. We also propose areas of future research to address outstanding questions in the field that could facilitate development of new disease treatments.
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Affiliation(s)
- Krystal Y Chung
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Jessica C S Brown
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
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16
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Kumari P, Arora N, Chatrath A, Gangwar R, Pruthi V, Poluri KM, Prasad R. Delineating the Biofilm Inhibition Mechanisms of Phenolic and Aldehydic Terpenes against Cryptococcus neoformans. ACS OMEGA 2019; 4:17634-17648. [PMID: 31681870 PMCID: PMC6822124 DOI: 10.1021/acsomega.9b01482] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 09/25/2019] [Indexed: 05/31/2023]
Abstract
The recalcitrant biofilm formed by fungus Cryptococcus neoformans is a life-threatening pathogenic condition responsible for further intensifying cryptococcosis. Considering the enhanced biofilm resistance and toxicity of synthetic antifungal drugs, the search for efficient, nontoxic, and cost-effective natural therapeutics has received a major boost. Phenolic (thymol and carvacrol) and aldehydic (citral) terpenes are natural and safe alternatives capable of efficient microbial biofilm inhibition. However, the biofilm inhibition mechanism of these terpenes still remains unclear. In this study, we adopted an integrative biophysical and biochemical approach to elucidate the hierarchy of their action against C. neoformans biofilm cells. The microscopic analysis revealed disruption of the biofilm cell surface with elevation in surface roughness and reduction in cell height. Although all terpenes acted through ergosterol biosynthesis inhibition, the phenolic terpenes also selectively interacted via ergosterol binding. Further, the alterations in the fatty acid profile in response to terpenes attenuated the cell membrane fluidity with enhanced permeability, resulting in pore formation and efflux of the K+/intracellular content. Additionally, mitochondrial depolarization caused higher levels of reactive oxygen species, which led to increased lipid peroxidation and activation of the antioxidant defense system. Indeed, the oxidative stress caused a significant decline in the amount of extracellular polymeric matrix and capsule sugars (mannose, xylose, and glucuronic acid), leading to a reduced capsule size and an overall negative charge on the cell surface. This comprehensive data revealed the mechanistic insights into the mode of action of terpenes on biofilm inhibition, which could be exploited for formulating novel anti-biofilm agents.
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Affiliation(s)
- Poonam Kumari
- Department of Biotechnology, Indian Institute
of Technology Roorkee, Roorkee 247677, Uttarakhand, India
| | - Neha Arora
- Department of Biotechnology, Indian Institute
of Technology Roorkee, Roorkee 247677, Uttarakhand, India
| | - Apurva Chatrath
- Department of Biotechnology, Indian Institute
of Technology Roorkee, Roorkee 247677, Uttarakhand, India
| | - Rashmi Gangwar
- Department of Biotechnology, Indian Institute
of Technology Roorkee, Roorkee 247677, Uttarakhand, India
| | - Vikas Pruthi
- Department of Biotechnology, Indian Institute
of Technology Roorkee, Roorkee 247677, Uttarakhand, India
| | - Krishna Mohan Poluri
- Department of Biotechnology, Indian Institute
of Technology Roorkee, Roorkee 247677, Uttarakhand, India
| | - Ramasare Prasad
- Department of Biotechnology, Indian Institute
of Technology Roorkee, Roorkee 247677, Uttarakhand, India
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Caza M, Kronstad JW. The cAMP/Protein Kinase a Pathway Regulates Virulence and Adaptation to Host Conditions in Cryptococcus neoformans. Front Cell Infect Microbiol 2019; 9:212. [PMID: 31275865 PMCID: PMC6592070 DOI: 10.3389/fcimb.2019.00212] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 05/31/2019] [Indexed: 12/28/2022] Open
Abstract
Nutrient sensing is critical for adaptation of fungi to environmental and host conditions. The conserved cAMP/PKA signaling pathway contributes to adaptation by sensing the availability of key nutrients such as glucose and directing changes in gene expression and metabolism. Interestingly, the cAMP/PKA pathway in fungal pathogens also influences the expression of virulence determinants in response to nutritional and host signals. For instance, protein kinase A (PKA) in the human pathogen Cryptococcus neoformans plays a central role in orchestrating phenotypic changes, such as capsule elaboration and melanin production, that directly impact disease development. In this review, we focus first on insights into the role of the cAMP/PKA pathway in nutrient sensing for the model yeast Saccharomyces cerevisiae to provide a foundation for understanding the pathway in C. neoformans. We then discuss key features of cAMP/PKA signaling in C. neoformans including new insights emerging from the analysis of transcriptional and proteomic changes in strains with altered PKA activity and expression. Finally, we highlight recent studies that connect the cAMP/PKA pathway to cell surface remodeling and the formation of titan cells.
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Affiliation(s)
- Mélissa Caza
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - James W Kronstad
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
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18
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Connecting iron regulation and mitochondrial function in Cryptococcus neoformans. Curr Opin Microbiol 2019; 52:7-13. [PMID: 31085406 DOI: 10.1016/j.mib.2019.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/04/2019] [Accepted: 04/05/2019] [Indexed: 12/13/2022]
Abstract
Iron acquisition is essential for the proliferation of microorganisms, and human pathogens such as the fungus Cryptococcus neoformans must use sophisticated uptake mechanisms to overcome host iron sequestration. Iron is of particular interest for C. neoformans because its availability is an important cue for the elaboration of virulence factors. In fungi, extracellular iron is taken up through high affinity, low affinity, siderophore-mediated, and heme uptake pathways, and the details of these mechanisms are under active investigation in C. neoformans. Following uptake, iron is transported to intracellular organelles including mitochondria where it is used in heme biosynthesis and the synthesis of iron-sulfur (Fe-S) cluster precursors. One Fe-S cluster binding protein of note is the monothiol glutaredoxin Grx4 which has emerged as a master regulator of iron sensing in C. neoformans and other fungi through its influence on the expression of proteins for iron uptake or use. The activity of Grx4 likely occurs through interactions with Fe-S clusters and transcription factors known to control expression of the iron-related functions. Although the extent to which Grx4 controls the iron regulatory network is still being investigated in C. neoformans, it is remarkable that it also influences the expression of many genes encoding mitochondrial functions. Coupled with recent studies linking mitochondrial morphology and electron transport to virulence factor elaboration, there is an emerging appreciation of mitochondria as central players in cryptococcal disease.
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19
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de Oliveira HC, Trevijano-Contador N, Garcia-Rodas R. Cryptococcal Pathogenicity and Morphogenesis. CURRENT FUNGAL INFECTION REPORTS 2019. [DOI: 10.1007/s12281-019-00340-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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20
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Metin B, Döğen A, Yıldırım E, de Hoog GS, Heitman J, Ilkit M. Mating type (MAT) locus and possible sexuality of the opportunistic pathogen Exophiala dermatitidis. Fungal Genet Biol 2019; 124:29-38. [PMID: 30611834 DOI: 10.1016/j.fgb.2018.12.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 12/27/2018] [Accepted: 12/30/2018] [Indexed: 11/27/2022]
Abstract
Sexual reproduction among the black yeasts is generally limited to environmental saprobic species and is rarely observed among opportunists in humans. To date, a complete sexual cycle has not been observed in Exophiala dermatitidis. In this study, we aimed to gain insight into the reproductive mode of E. dermatitidis by characterizing its mating type (MAT) locus, conducting MAT screening of environmental and clinical isolates, examining the expression of the MAT genes and analyzing the virulence of the isolates of different mating types. Similar to other members of the Pezizomycotina, the E. dermatitidis genome harbors a high mobility group (HMG) domain gene (MAT1-2-1) in the vicinity of the SLA2 and APN2 genes. The MAT loci of 74 E. dermatitidis isolates (11 clinical and 63 environmental) were screened by PCR, and the surrounding region was amplified using long-range PCR. Sequencing of the ∼ 12-kb PCR product of a MAT1-1 isolate revealed an α-box gene (MAT1-1-1). The MAT1-1 idiomorph was 3544-bp long and harbored the MAT1-1-1 and MAT1-1-4 genes. The MAT1-2 idiomorph was longer, 3771-bp, and harbored only the MAT1-2-1 gene. This structure suggests a heterothallic reproduction mode. The distribution of MAT among 74 isolates was ∼ 1:1 with a MAT1-1:MAT1-2 ratio of 35:39. RT-PCR analysis indicated that the MAT genes are transcribed. No significant difference was detected in the virulence of isolates representing different mating types using a Galleria mellonella model (P > 0.05). Collectively, E. dermatitidis is the first opportunistic black yeast in which both MAT idiomorphs have been characterized. The occurrence of isolates bearing both idiomorphs, their approximately equal distribution, and the expression of the MAT genes suggest that E. dermatitidis might reproduce sexually.
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Affiliation(s)
- Banu Metin
- Department of Food Engineering, Faculty of Engineering and Natural Sciences, Istanbul Sabahattin Zaim University, Istanbul, Turkey.
| | - Aylin Döğen
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Mersin University, Mersin, Turkey.
| | - Esra Yıldırım
- Department of Food Engineering, Faculty of Engineering and Natural Sciences, Istanbul Sabahattin Zaim University, Istanbul, Turkey.
| | - G Sybren de Hoog
- Westerdijk Fungal Biodiversity Institute, Utrecht, the Netherlands; Center of Expertise in Mycology of Radboudumc/CWZ, Nijmegen, the Netherlands.
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, USA.
| | - Macit Ilkit
- Division of Mycology, Department of Microbiology, Faculty of Medicine, Çukurova University, Adana, Turkey.
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21
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Zhou X, Ballou ER. The Cryptococcus neoformans Titan Cell: From In Vivo Phenomenon to In Vitro Model. CURRENT CLINICAL MICROBIOLOGY REPORTS 2018. [DOI: 10.1007/s40588-018-0107-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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22
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The Sec1/Munc18 (SM) protein Vps45 is involved in iron uptake, mitochondrial function and virulence in the pathogenic fungus Cryptococcus neoformans. PLoS Pathog 2018; 14:e1007220. [PMID: 30071112 PMCID: PMC6091972 DOI: 10.1371/journal.ppat.1007220] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 08/14/2018] [Accepted: 07/16/2018] [Indexed: 12/19/2022] Open
Abstract
The battle for iron between invading microorganisms and mammalian hosts is a pivotal determinant of the outcome of infection. The pathogenic fungus, Cryptococcus neoformans, employs multiple mechanisms to compete for iron during cryptococcosis, a disease primarily of immunocompromised hosts. In this study, we examined the role of endocytic trafficking in iron uptake by characterizing a mutant defective in the Sec1/Munc18 (SM) protein Vps45. This protein is known to regulate the machinery for vesicle trafficking and fusion via interactions with SNARE proteins. As expected, a vps45 deletion mutant was impaired in endocytosis and showed sensitivity to trafficking inhibitors. The mutant also showed poor growth on iron-limited media and a defect in transporting the Cfo1 ferroxidase of the high-affinity iron uptake system from the plasma membrane to the vacuole. Remarkably, we made the novel observation that Vps45 also contributes to mitochondrial function in that a Vps45-Gfp fusion protein associated with mitotracker, and a vps45 mutant showed enhanced sensitivity to inhibitors of electron transport complexes as well as changes in mitochondrial membrane potential. Consistent with mitochondrial function, the vps45 mutant was impaired in calcium homeostasis. To assess the relevance of these defects for virulence, we examined cell surface properties of the vps45 mutant and found increased sensitivity to agents that challenge cell wall integrity and to antifungal drugs. A change in cell wall properties was consistent with our observation of altered capsule polysaccharide attachment, and with attenuated virulence in a mouse model of cryptococcosis. Overall, our studies reveal a novel role for Vps45-mediated trafficking for iron uptake, mitochondrial function and virulence. Cryptococcus neoformans is a causative agent of cryptococcal meningitis, a disease that is estimated to cause ~ 15% of AIDS-related deaths. In this context, cryptococosis is one of the most common causes of mortality in people with HIV/AIDS, closely behind tuberculosis. Unfortunately, very few antifungal drugs are available to treat this disease. However, understanding mechanisms involved in the pathogenesis of C. neoformans can lead to new therapeutic avenues. In this study, we discovered a new role for a regulatory protein involved in vesicle transport. Specifically, we found that the Vps45 protein, which regulates vesicle fusion, participates in the trafficking of iron into fungal cells, supports mitochondria function, mediates antifungal resistance and is required for virulence. These discoveries shed light on the molecular mechanisms underlying the uptake and use of iron as an essential nutrient for the virulence of C. neoformans. Further investigations could lead to the development of drugs that target Vps45-mediated processes.
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Casadevall A, Coelho C, Cordero RJB, Dragotakes Q, Jung E, Vij R, Wear MP. The capsule of Cryptococcus neoformans. Virulence 2018; 10:822-831. [PMID: 29436899 PMCID: PMC6779390 DOI: 10.1080/21505594.2018.1431087] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The capsule of Cryptococcus neoformans is its dominant virulence factor and plays a key role in the biology of this fungus. In this essay, we focus on the capsule as a cellular structure and note the limitations inherent in the current methodologies available for its study. Given that no single method can provide the structure of the capsule, our notions of what is the cryptococcal capsule must be arrived at by synthesizing information gathered from very different methodological approaches including microscopy, polysaccharide chemistry and physical chemistry of macromolecules. The emerging picture is one of a carefully regulated dynamic structure that is constantly rearranged as a response to environmental stimulation and cellular replication. In the environment, the capsule protects the fungus against desiccation and phagocytic predators. In animal hosts the capsule functions in both offensive and defensive modes, such that it interferes with immune responses while providing the fungal cell with a defensive shield that is both antiphagocytic and capable of absorbing microbicidal oxidative bursts from phagocytic cells. Finally, we delineate a set of unsolved problems in the cryptococcal capsule field that could provide fertile ground for future investigations.
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Affiliation(s)
- Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Carolina Coelho
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Radames J B Cordero
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Quigly Dragotakes
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Eric Jung
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Raghav Vij
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Maggie P Wear
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
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Miltefosine Has a Postantifungal Effect and Induces Apoptosis in Cryptococcus Yeasts. Antimicrob Agents Chemother 2018; 62:AAC.00312-18. [PMID: 29844051 DOI: 10.1128/aac.00312-18] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/18/2018] [Indexed: 02/04/2023] Open
Abstract
Cryptococcus spp. are common opportunistic fungal pathogens, particularly in HIV patients. The approved drug miltefosine (MFS) has potential as an alternative antifungal against cryptococcosis; however, the mechanism of action of MFS in Cryptococcus is poorly understood. Here, we examined the effects of MFS on C. neoformans and C. gattii yeasts (planktonic and biofilm lifestyles) to clarify its mechanism of action. MFS presented inhibitory and fungicidal effects against planktonic Cryptococcus cells, with similar activities against dispersion biofilm cells, while sessile biofilm cells were less sensitive to MFS. Interestingly, MFS had postantifungal effect on Cryptococcus, with a proliferation delay of up to 8.15 h after a short exposure to fungicidal doses. MFS at fungicidal concentrations increased the plasma membrane permeability, likely due to a direct interaction with ergosterol, as suggested by competition assays with exogenous ergosterol. Moreover, MFS reduced the mitochondrial membrane potential, increased reactive oxygen species (ROS) production, and induced DNA fragmentation and condensation, all of which are hallmarks of apoptosis. Transmission electron microscopy analysis showed that MFS-treated yeasts had a reduced mucopolysaccharide capsule (confirmed by morphometry with light microscopy), plasma membrane irregularities, mitochondrial swelling, and a less conspicuous cell wall. Our results suggest that MFS increases the plasma membrane permeability in Cryptococcus via an interaction with ergosterol and also affects the mitochondrial membrane, eventually leading to apoptosis, in line with its fungicidal activity. These findings confirm the potential of MFS as an antifungal against C. neoformans and C. gattii and warrant further studies to establish clinical protocols for MFS use against cryptococcosis.
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Esher SK, Zaragoza O, Alspaugh JA. Cryptococcal pathogenic mechanisms: a dangerous trip from the environment to the brain. Mem Inst Oswaldo Cruz 2018; 113:e180057. [PMID: 29668825 PMCID: PMC5909089 DOI: 10.1590/0074-02760180057] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 03/08/2018] [Indexed: 12/16/2022] Open
Abstract
Cryptococcus neoformans is an opportunistic pathogenic yeast that causes serious infections, most commonly of the central nervous system (CNS). C. neoformans is mainly found in the environment and acquired by inhalation. It could be metaphorically imagined that cryptococcal disease is a "journey" for the microorganism that starts in the environment, where this yeast loads its suitcase with virulence traits. C. neoformans first encounters the infected mammalian host in the lungs, a site in which it must choose the right elements from its "virulence suitcase" to survive the pulmonary immune response. However, the lung is often only the first stop in this journey, and in some individuals the fungal trip continues to the brain. To enter the brain, C. neoformans must "open" the main barrier that protects this organ, the blood brain barrier (BBB). Once in the brain, C. neoformans expresses a distinct set of protective attributes that confers a strong neurotropism and the ability to cause brain colonisation. In summary, C. neoformans is a unique fungal pathogen as shown in its ability to survive in the face of multiple stress factors and to express virulence factors that contribute to the development of disease.
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Affiliation(s)
- Shannon K Esher
- Duke University School of Medicine, Department of Molecular Genetics and Microbiology, Department of Medicine, Durham, USA
| | - Oscar Zaragoza
- Instituto de Salud Carlos III, National Centre for Microbiology, Mycology Reference Laboratory, Madrid, Spain
| | - James Andrew Alspaugh
- Duke University School of Medicine, Department of Molecular Genetics and Microbiology, Department of Medicine, Durham, USA
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Abstract
The balance between reactive oxygen species and reactive nitrogen species production by the host and stress response by fungi is a key axis of the host-pathogen interaction. This review will describe emerging themes in fungal pathogenesis underpinning this axis.
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Affiliation(s)
- Adilia Warris
- Medical Research Centre for Medical Mycology, Aberdeen Fungal Group, Institute of Medical Sciences, University of Aberdeen, UK
| | - Elizabeth R Ballou
- Institute for Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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Boral H, Metin B, Döğen A, Seyedmousavi S, Ilkit M. Overview of selected virulence attributes in Aspergillus fumigatus, Candida albicans, Cryptococcus neoformans, Trichophyton rubrum, and Exophiala dermatitidis. Fungal Genet Biol 2017; 111:92-107. [PMID: 29102684 DOI: 10.1016/j.fgb.2017.10.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/24/2017] [Accepted: 10/27/2017] [Indexed: 12/13/2022]
Abstract
The incidence of fungal diseases has been increasing since 1980, and is associated with excessive morbidity and mortality, particularly among immunosuppressed patients. Of the known 625 pathogenic fungal species, infections caused by the genera Aspergillus, Candida, Cryptococcus, and Trichophyton are responsible for more than 300 million estimated episodes of acute or chronic infections worldwide. In addition, a rather neglected group of opportunistic fungi known as black yeasts and their filamentous relatives cause a wide variety of recalcitrant infections in both immunocompetent and immunosuppressed hosts. This article provides an overview of selected virulence factors that are known to suppress host immunity and enhance the infectivity of these fungi.
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Affiliation(s)
- Hazal Boral
- Division of Mycology, Department of Microbiology, Faculty of Medicine, University of Çukurova, Adana, Turkey
| | - Banu Metin
- Department of Food Engineering, Faculty of Engineering and Natural Sciences, Istanbul Sabahattin Zaim University, Istanbul, Turkey
| | - Aylin Döğen
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Mersin, Mersin, Turkey
| | - Seyedmojtaba Seyedmousavi
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands; Invasive Fungi Research Center, Mazandaran University of Medical Sciences, Sari, Iran; Center of Excellence for Infection Biology and Antimicrobial Pharmacology, Tehran, Iran
| | - Macit Ilkit
- Division of Mycology, Department of Microbiology, Faculty of Medicine, University of Çukurova, Adana, Turkey.
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