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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.
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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
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2
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Zhou Y, Huang Y, Yang C, Zang X, Deng H, Liu J, Zhao E, Tian T, Pan L, Xue X. The pathways and the mechanisms by which Cryptococcus enters the brain. Mycology 2024; 15:345-359. [PMID: 39247889 PMCID: PMC11376299 DOI: 10.1080/21501203.2023.2295409] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 12/11/2023] [Indexed: 09/10/2024] Open
Abstract
Generally, Cryptococcus initially infects the respiratory tract, but can spread, eventually crossing the blood-brain barrier (BBB) and causing meningitis or meningoencephalitis. Specifically, Cryptococcus invades the vascular endothelial cells of the BBB, from which it enters the brain. The main mechanisms through which Cryptococcus crosses the BBB are transcellular traversal, the paracellular pathway, and via Trojan horse. In this paper, the mechanisms by which Cryptococcus crosses the BBB were explained in detail. In addition to pathways of entry to the brain, this paper presents a discussion on some rare cryptococcal infections and provides some insights for future research directions.
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Affiliation(s)
- Yangyu Zhou
- Department of Respiratory and Critical Care, Emergency and Critical Care Medical Center, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Yemei Huang
- Department of Respiratory and Critical Care, Emergency and Critical Care Medical Center, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Chen Yang
- Department of Respiratory and Critical Care, Weifang Medical College, Weifang, China
| | - Xuelei Zang
- Department of Respiratory and Critical Care, Emergency and Critical Care Medical Center, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Hengyu Deng
- Department of Laboratory Medicine, Chinese PLA General Hospital, the First Medical Centre, Beijing, China
| | - Jing Liu
- Department of Laboratory Medicine, Chinese PLA General Hospital, the First Medical Centre, Beijing, China
| | - Enqi Zhao
- Department of Respiratory and Critical Care, Emergency and Critical Care Medical Center, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Tingyue Tian
- Department of Respiratory and Critical Care, Emergency and Critical Care Medical Center, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Lei Pan
- Department of Respiratory and Critical Care, Emergency and Critical Care Medical Center, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Xinying Xue
- Department of Respiratory and Critical Care, Emergency and Critical Care Medical Center, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
- Department of Laboratory Medicine, Chinese PLA General Hospital, the First Medical Centre, Beijing, China
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3
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Lanser DM, Bennett AB, Vu K, Gelli A. Macropinocytosis as a potential mechanism driving neurotropism of Cryptococcus neoformans. Front Cell Infect Microbiol 2023; 13:1331429. [PMID: 38149006 PMCID: PMC10750359 DOI: 10.3389/fcimb.2023.1331429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 11/27/2023] [Indexed: 12/28/2023] Open
Abstract
Cryptococcus neoformans can invade the central nervous system by crossing the blood-brain barrier via a transcellular mechanism that relies on multiple host factors. In this narrative, we review the evidence that a direct interplay between C. neoformans and brain endothelial cells forms the basis for invasion and transmigration across the brain endothelium. Adherence and internalization of C. neoformans is dependent on transmembrane proteins, including a hyaluronic acid receptor and an ephrin receptor tyrosine kinase. We consider the role of EphA2 in facilitating the invasion of the central nervous system by C. neoformans and highlight experimental evidence supporting macropinocytosis as a potential mechanism of internalization and transcytosis. How macropinocytosis might be conclusively demonstrated in the context of C. neoformans is also discussed.
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Affiliation(s)
| | | | | | - Angie Gelli
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States
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4
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Mani S, Dubey R, Lai IC, Babu MA, Tyagi S, Swargiary G, Mody D, Singh M, Agarwal S, Iqbal D, Kumar S, Hamed M, Sachdeva P, Almutary AG, Albadrani HM, Ojha S, Singh SK, Jha NK. Oxidative Stress and Natural Antioxidants: Back and Forth in the Neurological Mechanisms of Alzheimer's Disease. J Alzheimers Dis 2023; 96:877-912. [PMID: 37927255 DOI: 10.3233/jad-220700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
Alzheimer's disease (AD) is characterized by the progressive degeneration of neuronal cells. With the increase in aged population, there is a prevalence of irreversible neurodegenerative changes, causing a significant mental, social, and economic burden globally. The factors contributing to AD are multidimensional, highly complex, and not completely understood. However, it is widely known that aging, neuroinflammation, and excessive production of reactive oxygen species (ROS), along with other free radicals, substantially contribute to oxidative stress and cell death, which are inextricably linked. While oxidative stress is undeniably important in AD, limiting free radicals and ROS levels is an intriguing and potential strategy for deferring the process of neurodegeneration and alleviating associated symptoms. Therapeutic compounds from natural sources have recently become increasingly accepted and have been effectively studied for AD treatment. These phytocompounds are widely available and a multitude of holistic therapeutic efficiencies for treating AD owing to their antioxidant, anti-inflammatory, and biological activities. Some of these compounds also function by stimulating cholinergic neurotransmission, facilitating the suppression of beta-site amyloid precursor protein-cleaving enzyme 1, α-synuclein, and monoamine oxidase proteins, and deterring the occurrence of AD. Additionally, various phenolic, flavonoid, and terpenoid phytocompounds have been extensively described as potential palliative agents for AD progression. Preclinical studies have shown their involvement in modulating the cellular redox balance and minimizing ROS formation, displaying them as antioxidant agents with neuroprotective abilities. This review emphasizes the mechanistic role of natural products in the treatment of AD and discusses the various pathological hypotheses proposed for AD.
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Affiliation(s)
- Shalini Mani
- Centre for Emerging Diseases, Department of Biotechnology, Jaypee Institute of Information Technology, Noida, UP, India
| | - Rajni Dubey
- Division of Cardiology, Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan
| | - I-Chun Lai
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Division of Radiation Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan
- The Ph.D. Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University and Academia Sinica, Taipei, Taiwan
| | - M Arockia Babu
- Institute of Pharmaceutical Research, GLA University, Mathura, India
| | - Sakshi Tyagi
- Centre for Emerging Diseases, Department of Biotechnology, Jaypee Institute of Information Technology, Noida, UP, India
| | - Geeta Swargiary
- Centre for Emerging Diseases, Department of Biotechnology, Jaypee Institute of Information Technology, Noida, UP, India
| | - Deepansh Mody
- Centre for Emerging Diseases, Department of Biotechnology, Jaypee Institute of Information Technology, Noida, UP, India
| | - Manisha Singh
- Centre for Emerging Diseases, Department of Biotechnology, Jaypee Institute of Information Technology, Noida, UP, India
| | - Shriya Agarwal
- Department of Molecular Sciences, Macquarie University, Sydney, Australia
| | - Danish Iqbal
- Department of Health Information Management, College of Applied Medical Sciences, Buraydah Private Colleges, Buraydah, Saudi Arabia
| | - Sanjay Kumar
- Department of Life Sciences, School of Basic Sciences and Research (SBSR), Sharda University, Greater Noida, Uttar Pradesh, India
| | - Munerah Hamed
- Department of Pathology, Faculty of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia
| | | | - Abdulmajeed G Almutary
- Department of Biomedical Sciences, College of Health Sciences, Abu Dhabi University, Abu Dhabi, United Arab Emirates
| | - Hind Muteb Albadrani
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Imam Abdulrahman Bin Faisal University, Dammam, Eastern Province, Kingdom of Saudi Arabia
| | - Shreesh Ojha
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Abu Dhabi, United Arab Emirates
| | | | - Niraj Kumar Jha
- Department of Biotechnology, School of Engineering & Technology (SET), Sharda University, Greater Noida, Uttar Pradesh, India
- School of Bioengineering and Biosciences, Lovely Professional University, Phagwara, Punjab, India
- Department of Biotechnology, School of Applied & Life Sciences (SALS), Uttaranchal University, Dehradun, Uttarakhand, India
- Department of Biotechnology Engineering and Food Technology, Chandigarh University, Mohali, India
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5
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Cryptococcus neoformans Infection in the Central Nervous System: The Battle between Host and Pathogen. J Fungi (Basel) 2022; 8:jof8101069. [PMID: 36294634 PMCID: PMC9605252 DOI: 10.3390/jof8101069] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 09/28/2022] [Accepted: 10/07/2022] [Indexed: 11/17/2022] Open
Abstract
Cryptococcus neoformans (C. neoformans) is a pathogenic fungus with a global distribution. Humans become infected by inhaling the fungus from the environment, and the fungus initially colonizes the lungs. If the immune system fails to contain C. neoformans in the lungs, the fungus can disseminate to the blood and invade the central nervous system, resulting in fatal meningoencephalitis particularly in immunocompromised individuals including HIV/AIDS patients. Following brain invasion, C. neoformans will encounter host defenses involving resident as well as recruited immune cells in the brain. To overcome host defenses, C. neoformans possesses multiple virulence factors capable of modulating immune responses. The outcome of the interactions between the host and C. neoformans will determine the disease progression. In this review, we describe the current understanding of how C. neoformans migrates to the brain across the blood–brain barrier, and how the host immune system responds to the invading organism in the brain. We will also discuss the virulence factors that C. neoformans uses to modulate host immune responses.
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6
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Reyes EY, Shinohara ML. Host immune responses in the central nervous system during fungal infections. Immunol Rev 2022; 311:50-74. [PMID: 35672656 PMCID: PMC9489659 DOI: 10.1111/imr.13101] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 04/24/2022] [Accepted: 05/18/2022] [Indexed: 12/19/2023]
Abstract
Fungal infections in the central nervous system (CNS) cause high morbidity and mortality. The frequency of CNS mycosis has increased over the last two decades as more individuals go through immunocompromised conditions for various reasons. Nevertheless, options for clinical interventions for CNS mycoses are still limited. Thus, there is an urgent need to understand the host-pathogen interaction mechanisms in CNS mycoses for developing novel treatments. Although the CNS has been regarded as an immune-privileged site, recent studies demonstrate the critical involvement of immune responses elicited by CNS-resident and CNS-infiltrated cells during fungal infections. In this review, we discuss mechanisms of fungal invasion in the CNS, fungal pathogen detection by CNS-resident cells (microglia, astrocytes, oligodendrocytes, neurons), roles of CNS-infiltrated leukocytes, and host immune responses. We consider that understanding host immune responses in the CNS is crucial for endeavors to develop treatments for CNS mycosis.
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Affiliation(s)
- Estefany Y. Reyes
- Department of Immunology, Duke University School of Medicine, Durham, NC 27705, USA
| | - Mari L. Shinohara
- Department of Immunology, Duke University School of Medicine, Durham, NC 27705, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27705, USA
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7
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Tran VTA, Lee LP, Cho H. Neuroinflammation in neurodegeneration via microbial infections. Front Immunol 2022; 13:907804. [PMID: 36052093 PMCID: PMC9425114 DOI: 10.3389/fimmu.2022.907804] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 07/01/2022] [Indexed: 11/13/2022] Open
Abstract
Recent epidemiological studies show a noticeable correlation between chronic microbial infections and neurological disorders. However, the underlying mechanisms are still not clear due to the biological complexity of multicellular and multiorgan interactions upon microbial infections. In this review, we show the infection leading to neurodegeneration mediated by multiorgan interconnections and neuroinflammation. Firstly, we highlight three inter-organ communications as possible routes from infection sites to the brain: nose-brain axis, lung-brain axis, and gut-brain axis. Next, we described the biological crosstalk between microglia and astrocytes upon pathogenic infection. Finally, our study indicates how neuroinflammation is a critical player in pathogen-mediated neurodegeneration. Taken together, we envision that antibiotics targeting neuro-pathogens could be a potential therapeutic strategy for neurodegeneration.
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Affiliation(s)
- Van Thi Ai Tran
- Department of Biophysics, Institute of Quantum Biophysics, Sungkyunkwan University, Suwon, South Korea
| | - Luke P. Lee
- Department of Biophysics, Institute of Quantum Biophysics, Sungkyunkwan University, Suwon, South Korea
- Department of Medicine, Harvard Medical School, Brigham and Women’s Hospital, Harvard Institute of Medicine, Harvard University, Boston, MA, United States
- *Correspondence: Hansang Cho, ; Luke P. Lee,
| | - Hansang Cho
- Department of Biophysics, Institute of Quantum Biophysics, Sungkyunkwan University, Suwon, South Korea
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, South Korea
- *Correspondence: Hansang Cho, ; Luke P. Lee,
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8
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Chen Y, Li C, Sun D, Strickland AB, Liu G, Shi M. Quantitative analysis reveals internalisation of Cryptococcus neoformans by brain endothelial cells in vivo. Cell Microbiol 2021; 23:e13330. [PMID: 33745221 DOI: 10.1111/cmi.13330] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 12/12/2022]
Abstract
Migration of Cryptococcus neoformans from the blood to the brain parenchyma is crucial to cause fatal meningoencephalitis. Although mechanisms involved in brain migration of C. neoformans have been widely studied in vitro, less is known about how the fungus crosses the blood-brain barrier (BBB) in vivo. This is in part because of the lack of an approach to quantitatively analyse the dynamics of fungal transmigration into the brain across the BBB in vivo. In this study, we report a novel approach to quantitatively analyse the interactions between C. neoformans and brain endothelial cells in a mouse model using flow cytometry. Using this system, we show that C. neoformans was internalised by brain endothelial cells in vivo and that mice infected with acapsular or heat-killed C. neoformans yeast cells displayed a lower frequency of brain endothelial cells containing the yeast cell compared to mice infected with wild-type or viable yeast cells, respectively. We further demonstrate that brain endothelial cells were invaded by serotype A strain (H99 strain) at a higher rate compared to serotype D strain (52D strain). Our experiments established that internalisation of C. neoformans by brain endothelial cells occurred in vivo and offered a powerful approach to quantitatively analyse fungal migration into the brain.
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Affiliation(s)
- Yanli Chen
- Division of Immunology, Virginia-Maryland College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Chang Li
- Division of Immunology, Virginia-Maryland College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Donglei Sun
- Division of Immunology, Virginia-Maryland College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Ashley B Strickland
- Division of Immunology, Virginia-Maryland College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Gongguan Liu
- Division of Immunology, Virginia-Maryland College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Meiqing Shi
- Division of Immunology, Virginia-Maryland College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
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9
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Strickland AB, Shi M. Mechanisms of fungal dissemination. Cell Mol Life Sci 2021; 78:3219-3238. [PMID: 33449153 PMCID: PMC8044058 DOI: 10.1007/s00018-020-03736-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 11/23/2020] [Accepted: 12/08/2020] [Indexed: 12/13/2022]
Abstract
Fungal infections are an increasing threat to global public health. There are more than six million fungal species worldwide, but less than 1% are known to infect humans. Most of these fungal infections are superficial, affecting the hair, skin and nails, but some species are capable of causing life-threatening diseases. The most common of these include Cryptococcus neoformans, Aspergillus fumigatus and Candida albicans. These fungi are typically innocuous and even constitute a part of the human microbiome, but if these pathogens disseminate throughout the body, they can cause fatal infections which account for more than one million deaths worldwide each year. Thus, systemic dissemination of fungi is a critical step in the development of these deadly infections. In this review, we discuss our current understanding of how fungi disseminate from the initial infection sites to the bloodstream, how immune cells eliminate fungi from circulation and how fungi leave the blood and enter distant organs, highlighting some recent advances and offering some perspectives on future directions.
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Affiliation(s)
- Ashley B Strickland
- Division of Immunology, Virginia-Maryland College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA.
| | - Meiqing Shi
- Division of Immunology, Virginia-Maryland College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA.
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Marina CL, Bürgel PH, Agostinho DP, Zamith-Miranda D, Las-Casas LDO, Tavares AH, Nosanchuk JD, Bocca AL. Nutritional Conditions Modulate C. neoformans Extracellular Vesicles' Capacity to Elicit Host Immune Response. Microorganisms 2020; 8:E1815. [PMID: 33217920 PMCID: PMC7698703 DOI: 10.3390/microorganisms8111815] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/10/2020] [Accepted: 11/13/2020] [Indexed: 12/11/2022] Open
Abstract
Cryptococcus neoformans is a human pathogenic fungus that mainly afflicts immunocompromised patients. One of its virulence strategies is the production of extracellular vesicles (EVs), containing cargo with immunomodulatory properties. We evaluated EV's characteristics produced by capsular and acapsular strains of C. neoformans (B3501 and ΔCap67, respectively) growing in nutritionally poor or rich media and co-cultures with bone marrow-derived macrophages or dendritic cells from C57BL/6 mice. EVs produced under a poor nutritional condition displayed a larger hydrodynamic size, contained more virulence compounds, and induced a more robust inflammatory pattern than those produced in a rich nutritional medium, independently of strain. We treated infected mice with EVs produced in the rich medium, and the EVs inhibited more genes related to the inflammasome than untreated infected mice. These findings suggest that the EVs participate in the pathogenic processes that result in the dissemination of C. neoformans. Thus, these results highlight the versatility of EVs' properties during infection by C. neoformans in different tissues and support ongoing efforts to harness EVs to prevent and treat cryptococcosis.
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Affiliation(s)
- Clara Luna Marina
- Laboratory of Applied Immunity, Institute of Biology Sciences, University of Brasília, Brasília, Distrito Federal 70910-900, Brazil; (C.L.M.); (P.H.B.); (L.d.O.L.-C.)
| | - Pedro Henrique Bürgel
- Laboratory of Applied Immunity, Institute of Biology Sciences, University of Brasília, Brasília, Distrito Federal 70910-900, Brazil; (C.L.M.); (P.H.B.); (L.d.O.L.-C.)
| | - Daniel Paiva Agostinho
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, New York, NY 10461, USA; (D.P.A.); (D.Z.-M.); (J.D.N.)
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Daniel Zamith-Miranda
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, New York, NY 10461, USA; (D.P.A.); (D.Z.-M.); (J.D.N.)
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Lucas de Oliveira Las-Casas
- Laboratory of Applied Immunity, Institute of Biology Sciences, University of Brasília, Brasília, Distrito Federal 70910-900, Brazil; (C.L.M.); (P.H.B.); (L.d.O.L.-C.)
| | | | - Joshua Daniel Nosanchuk
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, New York, NY 10461, USA; (D.P.A.); (D.Z.-M.); (J.D.N.)
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Anamelia Lorenzetti Bocca
- Laboratory of Applied Immunity, Institute of Biology Sciences, University of Brasília, Brasília, Distrito Federal 70910-900, Brazil; (C.L.M.); (P.H.B.); (L.d.O.L.-C.)
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Oxidative Stress-Mediated Blood-Brain Barrier (BBB) Disruption in Neurological Diseases. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020. [DOI: 10.1155/2020/4356386] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The blood-brain barrier (BBB), as a crucial gate of brain-blood molecular exchange, is involved in the pathogenesis of multiple neurological diseases. Oxidative stress is caused by an imbalance between the production of reactive oxygen species (ROS) and the scavenger system. Since oxidative stress plays a significant role in the production and maintenance of the BBB, the cerebrovascular system is especially vulnerable to it. The pathways that initiate BBB dysfunction include, but are not limited to, mitochondrial dysfunction, excitotoxicity, iron metabolism, cytokines, pyroptosis, and necroptosis, all converging on the generation of ROS. Interestingly, ROS also provide common triggers that directly regulate BBB damage, parameters including tight junction (TJ) modifications, transporters, matrix metalloproteinase (MMP) activation, inflammatory responses, and autophagy. We will discuss the role of oxidative stress-mediated BBB disruption in neurological diseases, such as hemorrhagic stroke, ischemic stroke (IS), Alzheimer’s disease (AD), Parkinson’s disease (PD), traumatic brain injury (TBI), amyotrophic lateral sclerosis (ALS), and cerebral small vessel disease (CSVD). This review will also discuss the latest clinical evidence of potential biomarkers and antioxidant drugs towards oxidative stress in neurological diseases. A deeper understanding of how oxidative stress damages BBB may open up more therapeutic options for the treatment of neurological diseases.
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12
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Vu K, Garcia JA, Gelli A. Cryptococcal Meningitis and Anti-virulence Therapeutic Strategies. Front Microbiol 2019; 10:353. [PMID: 30863389 PMCID: PMC6399105 DOI: 10.3389/fmicb.2019.00353] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Accepted: 02/11/2019] [Indexed: 01/31/2023] Open
Abstract
Fungal infections of the central nervous system are responsible for significant morbidity and mortality. Cryptococcus neoformans (Cn) is the primary cause of fungal meningitis. Infection begins in the lung after inhalation of fungal spores but often spreads to other organs, particularly the brain in immunosuppressed individuals. Cn’s ability to survive phagocytosis and endure the onslaught of oxidative attack imposed by the innate immune response facilitates dissemination to the central nervous system (CNS). Despite the success of Cn at bypassing innate immunity, entry into the heavily protected brain requires that Cn overwhelm the highly restricted blood-brain barrier (BBB). This is a formidable task but mounting evidence suggests that Cn expresses surface-bound and secreted virulence factors including urease, metalloprotease, and hyaluronic acid that can undermine the BBB. In addition, Cn can exploit multiple routes of entry to gain access to the CNS. In this review, we discuss the cellular and molecular interface of Cn and the BBB, and we propose that the virulence factors mediating BBB crossing could be targeted for the development of anti-virulence drugs aimed at preventing fungal colonization of the CNS.
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Affiliation(s)
- Kiem Vu
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Javier A Garcia
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Angie Gelli
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States
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Abstract
BACKGROUND Fungal infections of the central nervous system (FIs-CNS) have become significantly more common over the past 2 decades. Invasion of the CNS largely depends on the immune status of the host and the virulence of the fungal strain. Infections with fungi cause a significant morbidity in immunocompromised hosts, and the involvement of the CNS may lead to fatal consequences. METHODS One hundred and thirty-five articles on fungal neuroinfection in PubMed, Google Scholar, and Cochrane databases were selected for review using the following search words: "fungi and CNS mycoses", CNS fungal infections", "fungal brain infections", " fungal cerebritis", fungal meningitis", "diagnostics of fungal infections", and "treatment of CNS fungal infections". All were published in English with the majority in the period 2000-2018. This review focuses on the current knowledge of the epidemiology, clinical presentations, diagnosis, and treatment of selected FIs-CNS. RESULTS The FIs-CNS can have various clinical presentations, mainly meningitis, encephalitis, hydrocephalus, cerebral abscesses, and stroke syndromes. The etiologic factors of neuroinfections are yeasts (Cryptococcus neoformans, Candida spp., Trichosporon spp.), moniliaceous moulds (Aspergillus spp., Fusarium spp.), Mucoromycetes (Mucor spp., Rhizopus spp.), dimorphic fungi (Blastomyces dermatitidis, Coccidioides spp., Histoplasma capsulatum), and dematiaceous fungi (Cladophialophora bantiana, Exophiala dermatitidis). Their common route of transmission is inhalation or inoculation from trauma or surgery, with subsequent hematogenous or contiguous spread. As the manifestations of FIs-CNS are often non-specific, their diagnosis is very difficult. A fast identification of the etiological factor of neuroinfection and the application of appropriate therapy are crucial in preventing an often fatal outcome. The choice of effective drug depends on its extent of CNS penetration and spectrum of activity. Pharmaceutical formulations of amphotericin B (AmB) (among others, deoxycholate-AmBd and liposomal L-AmB) have relatively limited distribution in the cerebrospinal fluid (CSF); however, their detectable therapeutic concentrations in the CNS makes them recommended drugs for the treatment of cryptococcal meningoencephalitis (AmBd with flucytosine) and CNS candidiasis (L-AmB) and mucormycosis (L-AmB). Voriconazole, a moderately lipophilic molecule with good CNS penetration, is recommended in the first-line therapy of CNS aspergillosis. Other triazoles, such as posaconazole and itraconazole, with negligible concentrations in the CSF are not considered effective drugs for therapy of CNS fungal neuroinfections. In contrast, clinical data have shown that a novel triazole, isavuconazole, achieved considerable efficacy for the treatment of some fungal neuroinfections. Echinocandins with relatively low or undetectable concentrations in the CSF do not play meaningful role in the treatment of FIs-CNS. CONCLUSION Although the number of fungal species causing CNS mycosis is increasing, only some possess well-defined treatment standards (e.g., cryptococcal meningitis and CNS aspergillosis). The early diagnosis of fungal infection, accompanied by identification of the etiological factor, is needed to allow the selection of effective therapy in patients with FIs-CNS and limit their high mortality.
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Affiliation(s)
- Katarzyna Góralska
- Department of Biomedicine and Genetics, Medical University of Lodz, Pomorska 251, 92-213, Lodz, Poland.
| | - Joanna Blaszkowska
- Department of Diagnostics and Treatment of Parasitic Diseases and Mycoses, Medical University of Lodz, Pomorska 251, 92-213, Lodz, Poland
| | - Magdalena Dzikowiec
- Department of Diagnostics and Treatment of Parasitic Diseases and Mycoses, Medical University of Lodz, Pomorska 251, 92-213, Lodz, Poland
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14
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Aaron PA, Jamklang M, Uhrig JP, Gelli A. The blood-brain barrier internalises Cryptococcus neoformans via the EphA2-tyrosine kinase receptor. Cell Microbiol 2018; 20. [PMID: 29197141 DOI: 10.1111/cmi.12811] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 11/13/2017] [Accepted: 11/14/2017] [Indexed: 02/06/2023]
Abstract
Cryptococcus neoformans is an opportunistic fungal pathogen that causes life-threatening meningitis most commonly in populations with impaired immunity. Here, we resolved the transcriptome of the human brain endothelium challenged with C. neoformans to establish whether C. neoformans invades the CNS by co-opting particular signalling pathways as a means to promote its own entry. Among the 5 major pathways targeted by C. neoformans, the EPH-EphrinA1 (EphA2) tyrosine kinase receptor-signalling pathway was examined further. Silencing the EphA2 receptor transcript in a human brain endothelial cell line or blocking EphA2 activity with an antibody or chemical inhibitor prevented transmigration of C. neoformans in an in vitro model of the blood-brain barrier (BBB). In contrast, treating brain endothelial cells with an EphA2 chemical agonist or an EphA2 ligand promoted greater migration of fungal cells across the BBB. C. neoformans activated the EPH-tyrosine kinase pathway through a CD44-dependent phosphorylation of EphA2, promoting clustering and internalisation of EphA2 receptors. Moreover, HEK293T cells expressing EphA2 revealed an association between EphA2 and C. neoformans that boosted internalisation of C. neoformans. Collectively, the results suggest that C. neoformans promotes EphA2 activity via CD44, and this in turn creates a permeable barrier that facilitates the migration of C. neoformans across the BBB.
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Affiliation(s)
- Phylicia A Aaron
- Department of Pharmacology, School of Medicine, Genome and Biomedical Sciences Facility, University of California, Davis, California, USA
| | - Mantana Jamklang
- Department of Pharmacology, School of Medicine, Genome and Biomedical Sciences Facility, University of California, Davis, California, USA
| | - John P Uhrig
- Department of Pharmacology, School of Medicine, Genome and Biomedical Sciences Facility, University of California, Davis, California, USA
| | - Angie Gelli
- Department of Pharmacology, School of Medicine, Genome and Biomedical Sciences Facility, University of California, Davis, California, USA
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Bagam P, Singh DP, Inda ME, Batra S. Unraveling the role of membrane microdomains during microbial infections. Cell Biol Toxicol 2017; 33:429-455. [PMID: 28275881 PMCID: PMC7088210 DOI: 10.1007/s10565-017-9386-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 02/06/2017] [Indexed: 01/06/2023]
Abstract
Infectious diseases pose major socioeconomic and health-related threats to millions of people across the globe. Strategies to combat infectious diseases derive from our understanding of the complex interactions between the host and specific bacterial, viral, and fungal pathogens. Lipid rafts are membrane microdomains that play important role in life cycle of microbes. Interaction of microbial pathogens with host membrane rafts influences not only their initial colonization but also their spread and the induction of inflammation. Therefore, intervention strategies aimed at modulating the assembly of membrane rafts and/or regulating raft-directed signaling pathways are attractive approaches for the. management of infectious diseases. The current review discusses the latest advances in terms of techniques used to study the role of membrane microdomains in various pathological conditions and provides updated information regarding the role of membrane rafts during bacterial, viral and fungal infections.
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Affiliation(s)
- Prathyusha Bagam
- Laboratory of Pulmonary Immuno-Toxicology, Department of Environmental Toxicology, Health Research Center, Southern University and A&M College, Baton Rouge, LA, 70813, USA
| | - Dhirendra P Singh
- Laboratory of Pulmonary Immuno-Toxicology, Department of Environmental Toxicology, Health Research Center, Southern University and A&M College, Baton Rouge, LA, 70813, USA
| | - Maria Eugenia Inda
- Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Suipacha, Rosario, Argentina
| | - Sanjay Batra
- Laboratory of Pulmonary Immuno-Toxicology, Department of Environmental Toxicology, Health Research Center, Southern University and A&M College, Baton Rouge, LA, 70813, USA.
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16
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Yang CL, Wang J, Zou LL. Innate immune evasion strategies against Cryptococcal meningitis caused by Cryptococcus neoformans. Exp Ther Med 2017; 14:5243-5250. [PMID: 29285049 PMCID: PMC5740712 DOI: 10.3892/etm.2017.5220] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 05/31/2017] [Indexed: 12/14/2022] Open
Abstract
As an infectious fungus that affects the respiratory tract, Cryptococcus neoformans (C. neoformans) commonly causes asymptomatic pulmonary infection. C. neoformans may target the brain instead of the lungs and cross the blood-brain barrier (BBB) in the early phase of infection; however, this is dependent on successful evasion of the host innate immune system. During the initial stage of fungal infection, a complex network of innate immune factors are activated. C. neoformans utilizes a number of strategies to overcome the anti-fungal mechanisms of the host innate immune system and cross the BBB. In the present review, the defensive mechanisms of C. neoformans against the innate immune system and its ability to cross the BBB were discussed, with an emphasis on recent insights into the activities of anti-phagocytotic and anti-oxidative factors in C. neoformans.
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Affiliation(s)
- Cheng-Liang Yang
- Translational Neuroscience and Neural Regeneration and Repair Institute, The First Hospital of Yichang, China Three Gorges University, Yichang, Hubei 443002, P.R. China.,Institute of Cell Therapy, The First Hospital of Yichang, China Three Gorges University, Yichang, Hubei 443002, P.R. China
| | - Jun Wang
- Translational Neuroscience and Neural Regeneration and Repair Institute, The First Hospital of Yichang, China Three Gorges University, Yichang, Hubei 443002, P.R. China.,Institute of Cell Therapy, The First Hospital of Yichang, China Three Gorges University, Yichang, Hubei 443002, P.R. China
| | - Li-Li Zou
- Translational Neuroscience and Neural Regeneration and Repair Institute, The First Hospital of Yichang, China Three Gorges University, Yichang, Hubei 443002, P.R. China.,Institute of Cell Therapy, The First Hospital of Yichang, China Three Gorges University, Yichang, Hubei 443002, P.R. China.,Department of Microbiology and Immunology, Medical College, China Three Gorges University, Yichang, Hubei 443002, P.R. China
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Na Pombejra S, Salemi M, Phinney BS, Gelli A. The Metalloprotease, Mpr1, Engages AnnexinA2 to Promote the Transcytosis of Fungal Cells across the Blood-Brain Barrier. Front Cell Infect Microbiol 2017; 7:296. [PMID: 28713781 PMCID: PMC5492700 DOI: 10.3389/fcimb.2017.00296] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 06/16/2017] [Indexed: 12/19/2022] Open
Abstract
Eukaryotic pathogens display multiple mechanisms for breaching the blood-brain barrier (BBB) and invading the central nervous system (CNS). Of the fungal spp., that cause disease in mammals, only some cross brain microvascular endothelial cells which constitute the BBB, and invade the brain. Cryptococcus neoformans, the leading cause of fungal meningoencephalitis, crosses the BBB directly by transcytosis or by co-opting monocytes. We previously determined that Mpr1, a secreted fungal metalloprotease, facilitates association of fungal cells to brain microvascular endothelial cells and we confirmed that the sole expression of CnMPR1 endowed S. cerevisiae with an ability to cross the BBB. Here, the gain of function conferred onto S. cerevisiae by CnMPR1 (i.e., Sc<CnMPR1> strain) was used to identify targets of Mpr1 that might reside on the surface of the BBB. Following biotin-labeling of BBB surface proteins, Sc<CnMPR1>-associated proteins were identified by LC-MS/MS. Of the 62 proteins identified several were cytoskeleton-endocytosis-associated including AnnexinA2 (AnxA2). Using an in vitro model of the human BBB where AnxA2 activity was blocked, we found that the lack of AnxA2 activity prevented the movement of S. cerevisiae across the BBB (i.e., transcytosis of Sc<CnMPR1> strain) but unexpectedly, TEM analysis revealed that AnxA2 was not required for the association or the internalization of Sc<CnMPR1>. Additionally, the co-localization of AnxA2 and Sc<CnMPR1> suggest that successful crossing of the BBB is dependent on an AxnA2-Mpr1-mediated interaction. Collectively the data suggest that AnxA2 plays a central role in fungal transcytosis in human brain microvascular endothelial cells. The movement and exocytosis of Sc<CnMPR1> is dependent on membrane trafficking events that involve AnxA2 but these events appear to be independent from the actions of AnxA2 at the host cell surface. We propose that Mpr1 activity promotes cytoskeleton remodeling in brain microvascular endothelial cells and thereby engages AnxA2 in order to facilitate fungal transcytosis of the BBB.
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Affiliation(s)
- Sarisa Na Pombejra
- Department of Pharmacology, School of Medicine, Genome and Biomedical Sciences Facility, University of California, DavisDavis, CA, United States
| | - Michelle Salemi
- Proteomics Core Facility, Genome and Biomedical Sciences Facility, University of California, DavisDavis, CA, United States
| | - Brett S Phinney
- Proteomics Core Facility, Genome and Biomedical Sciences Facility, University of California, DavisDavis, CA, United States
| | - Angie Gelli
- Department of Pharmacology, School of Medicine, Genome and Biomedical Sciences Facility, University of California, DavisDavis, CA, United States
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18
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He X, Shi X, Puthiyakunnon S, Zhang L, Zeng Q, Li Y, Boddu S, Qiu J, Lai Z, Ma C, Xie Y, Long M, Du L, Huang SH, Cao H. CD44-mediated monocyte transmigration across Cryptococcus neoformans-infected brain microvascular endothelial cells is enhanced by HIV-1 gp41-I90 ectodomain. J Biomed Sci 2016; 23:28. [PMID: 26897523 PMCID: PMC4761181 DOI: 10.1186/s12929-016-0247-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 02/15/2016] [Indexed: 12/19/2022] Open
Abstract
Background Cryptococcus neoformans (Cn) is an important opportunistic pathogen in the immunocompromised people, including AIDS patients, which leads to fatal cryptococcal meningitis with high mortality rate. Previous researches have shown that HIV-1 gp41-I90 ectodomain can enhance Cn adhesion to and invasion of brain microvascular endothelial cell (BMEC), which constitutes the blood brain barrier (BBB). However, little is known about the role of HIV-1 gp41-I90 in the monocyte transmigration across Cn-infected BBB. In the present study, we provide evidence that HIV-1 gp41-I90 and Cn synergistically enhance monocytes transmigration across the BBB in vitro and in vivo. The underlying mechanisms for this phenomenon require further study. Methods In this study, the enhancing role of HIV-1 gp41-I90 in monocyte transmigration across Cn-infected BBB was demonstrated by performed transmigration assays in vitro and in vivo. Results Our results showed that the transmigration rate of monocytes are positively associated with Cn and/or HIV-1 gp41-I90, the co-exposure (HIV-1 gp41-I90 + Cn) group showed a higher THP-1 transmigration rate (P < 0.01). Using CD44 knock-down HBMEC or CD44 inhibitor Bikunin in the assay, the facilitation of transmigration rates of monocyte enhanced by HIV-1 gp41-I90 was significantly suppressed. Western blotting analysis and biotin/avidin enzyme-linked immunosorbent assays (BA-ELISAs) showed that Cn and HIV-1 gp41-I90 could increase the expression of CD44 and ICAM-1 on the HBMEC. Moreover, Cn and/or HIV-1 gp41-I90 could also induce CD44 redistribution to the membrane lipid rafts. By establishing the mouse cryptococcal meningitis model, we found that HIV-1 gp41-I90 and Cn could synergistically enhance the monocytes transmigration, increase the BBB permeability and injury in vivo. Conclusions Collectively, our findings suggested that HIV-1 gp41-I90 ectodomain can enhance the transmigration of THP-1 through Cn-infected BBB, which may be mediated by CD44. This novel study enlightens the future prospects to elaborate the inflammatory responses induced by HIV-1 gp41-I90 ectodomain and to effectively eliminate the opportunistic infections in AIDS patients.
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Affiliation(s)
- Xiaolong He
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Xiaolu Shi
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Santhosh Puthiyakunnon
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Like Zhang
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Qing Zeng
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Yan Li
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Swapna Boddu
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Jiawen Qiu
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Zhihao Lai
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Chao Ma
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Yulong Xie
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Min Long
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Lei Du
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Sheng-He Huang
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China. .,Saban Research Institute, Children's Hospital Los Angeles, University of Southern California, Los Angeles, CA, 90027, USA.
| | - Hong Cao
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
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Albataineh MT, Kadosh D. Regulatory roles of phosphorylation in model and pathogenic fungi. Med Mycol 2015; 54:333-52. [PMID: 26705834 PMCID: PMC4818690 DOI: 10.1093/mmy/myv098] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 11/01/2015] [Indexed: 12/25/2022] Open
Abstract
Over the past 20 years, considerable advances have been made toward our understanding
of how post-translational modifications affect a wide variety of biological
processes, including morphology and virulence, in medically important fungi.
Phosphorylation stands out as a key molecular switch and regulatory modification that
plays a critical role in controlling these processes. In this article, we first
provide a comprehensive and up-to-date overview of the regulatory roles that both
Ser/Thr and non-Ser/Thr kinases and phosphatases play in model and pathogenic fungi.
Next, we discuss the impact of current global approaches that are being used to
define the complete set of phosphorylation targets (phosphoproteome) in medically
important fungi. Finally, we provide new insights and perspectives into the potential
use of key regulatory kinases and phosphatases as targets for the development of
novel and more effective antifungal strategies.
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Affiliation(s)
- Mohammad T Albataineh
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
| | - David Kadosh
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
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Abstract
Cryptococcosis is a globally distributed invasive fungal infection that is caused by species within the genus Cryptococcus which presents substantial therapeutic challenges. Although natural human-to-human transmission has never been observed, recent work has identified multiple virulence mechanisms that enable cryptococci to infect, disseminate within and ultimately kill their human host. In this Review, we describe these recent discoveries that illustrate the intricacy of host-pathogen interactions and reveal new details about the host immune responses that either help to protect against disease or increase host susceptibility. In addition, we discuss how this improved understanding of both the host and the pathogen informs potential new avenues for therapeutic development.
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Tseng HK, Huang TY, Wu AYJ, Chen HH, Liu CP, Jong A. How Cryptococcus interacts with the blood-brain barrier. Future Microbiol 2015; 10:1669-82. [PMID: 26437710 DOI: 10.2217/fmb.15.83] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Cryptococcus demonstrates predilection for invasion of the brain, but the mechanism by which Cryptococcus crosses the blood-brain barrier (BBB) to cause brain invasion is largely unknown. In order for Cryptococcus to cross the BBB, there must be a way to either cross human brain microvascular endothelial cells, which are the main constitute of the BBB, or go in between tight junctions. Recent evidence of human brain microvascular endothelial cell responses to transcellular brain invasions includes membrane rearrangements, intracellular signaling pathways and cytoskeletal activations. Several Cryptococcal genes related to the traversal of BBB have been identified, including CPS1, ITR1a, ITR3c, PLB1, MPR1, FNX1 and RUB1. In addition, Cryptococcus neoformans-derived microvesicles may contribute to cryptococcal brain invasion. Paracellularly, Cryptococcus may traverse across BBB using either routes utilizing plasmin, ammonia or macrophages in a Trojan horse mechanism.
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Affiliation(s)
- Hsiang-Kuang Tseng
- Department of Medicine, MacKay Medical College, No. 46, Sec. 3, Zhongzheng Road, Sanzhi Distric, New Taipei City 25245, Taiwan.,Division of Infectious Diseases, Department of Internal Medicine, MacKay Memorial Hospital, Taipei Branch, No. 92, Sec. 2, Zhongshan North Road, Taipei City 10449, Taiwan.,Microbiology Section, Department of Medical Research, MacKay Memorial Hospital, Tamshui Branch, No. 45, Minsheng Road, Tamshui District, New Taipei City 25160, Taiwan
| | - Tseng-Yu Huang
- Division of Infectious Diseases, Department of Internal Medicine, MacKay Memorial Hospital, Taipei Branch, No. 92, Sec. 2, Zhongshan North Road, Taipei City 10449, Taiwan
| | - Alice Ying-Jung Wu
- Division of Infectious Diseases, Department of Internal Medicine, MacKay Memorial Hospital, Taipei Branch, No. 92, Sec. 2, Zhongshan North Road, Taipei City 10449, Taiwan
| | - Hsin-Hong Chen
- Microbiology Section, Department of Medical Research, MacKay Memorial Hospital, Tamshui Branch, No. 45, Minsheng Road, Tamshui District, New Taipei City 25160, Taiwan
| | - Chang-Pan Liu
- Department of Medicine, MacKay Medical College, No. 46, Sec. 3, Zhongzheng Road, Sanzhi Distric, New Taipei City 25245, Taiwan.,Division of Infectious Diseases, Department of Internal Medicine, MacKay Memorial Hospital, Taipei Branch, No. 92, Sec. 2, Zhongshan North Road, Taipei City 10449, Taiwan.,Microbiology Section, Department of Medical Research, MacKay Memorial Hospital, Tamshui Branch, No. 45, Minsheng Road, Tamshui District, New Taipei City 25160, Taiwan
| | - Ambrose Jong
- Hematology-Oncology/BMT, Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
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Zhang B, Yu JY, Liu LQ, Peng L, Chi F, Wu CH, Jong A, Wang SF, Cao H, Huang SH. Alpha7 nicotinic acetylcholine receptor is required for blood-brain barrier injury-related CNS disorders caused by Cryptococcus neoformans and HIV-1 associated comorbidity factors. BMC Infect Dis 2015; 15:352. [PMID: 26285576 PMCID: PMC4543465 DOI: 10.1186/s12879-015-1075-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 07/31/2015] [Indexed: 01/11/2023] Open
Abstract
Background Cryptococcal meningitis is the most common fungal infection of the central nervous system (CNS) in HIV/AIDS. HIV-1 virotoxins (e.g., gp41) are able to induce disorders of the blood-brain barrier (BBB), which mainly consists of BMEC. Our recent study suggests that α7 nAChR is an essential regulator of inflammation, which contributes to regulation of NF-κB signaling, neuroinflammation and BBB disorders caused by microbial (e.g., HIV-1 gp120) and non-microbial [e.g., methamphetamine (METH)] factors. However, the underlying mechanisms for multiple comorbidities are unclear. Methods In this report, an aggravating role of α7 nAChR in host defense against CNS disorders caused by these comorbidities was demonstrated by chemical [inhibitor: methyllycaconitine (MLA)] and genetic (α7−/− mice) blockages of α7 nAChR. Results As shown in our in vivo studies, BBB injury was significantly reduced in α7−/− mice infected with C. neoformans. Stimulation by the gp41 ectodomain peptide (gp41-I90) and METH was abolished in the α7−/− animals. C. neoformans and gp41-I90 could activate NF-κB. Gp41-I90- and METH-induced monocyte transmigration and senescence were significantly inhibited by MLA and CAPE (caffeic acid phenethyl ester, an NF-κB inhibitor). Conclusions Collectively, our data suggest that α7 nAChR plays a detrimental role in the host defense against C. neoformans- and HIV-1 associated comorbidity factors-induced BBB injury and CNS disorders.
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Affiliation(s)
- Bao Zhang
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China. .,Saban Research Institute of Childrens Hospital Los Angeles, Department of Pediatrics, University of Southern California, 4650 Sunset Blvd., Mailstop #51, Los Angeles, CA, 90027, USA.
| | - Jing-Yi Yu
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China. .,Saban Research Institute of Childrens Hospital Los Angeles, Department of Pediatrics, University of Southern California, 4650 Sunset Blvd., Mailstop #51, Los Angeles, CA, 90027, USA.
| | - Li-Qun Liu
- Division of Pediatric Neurology, Children's Medical Center, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China.
| | - Liang Peng
- Saban Research Institute of Childrens Hospital Los Angeles, Department of Pediatrics, University of Southern California, 4650 Sunset Blvd., Mailstop #51, Los Angeles, CA, 90027, USA. .,Department of Clinic Laboratory, the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510260, China.
| | - Feng Chi
- Saban Research Institute of Childrens Hospital Los Angeles, Department of Pediatrics, University of Southern California, 4650 Sunset Blvd., Mailstop #51, Los Angeles, CA, 90027, USA.
| | - Chun-Hua Wu
- Saban Research Institute of Childrens Hospital Los Angeles, Department of Pediatrics, University of Southern California, 4650 Sunset Blvd., Mailstop #51, Los Angeles, CA, 90027, USA.
| | - Ambrose Jong
- Saban Research Institute of Childrens Hospital Los Angeles, Department of Pediatrics, University of Southern California, 4650 Sunset Blvd., Mailstop #51, Los Angeles, CA, 90027, USA.
| | - Shi-Fu Wang
- Saban Research Institute of Childrens Hospital Los Angeles, Department of Pediatrics, University of Southern California, 4650 Sunset Blvd., Mailstop #51, Los Angeles, CA, 90027, USA. .,Department of Children's Medical Laboratory Diagnosis Center, Qilu Children's Hospital of Shandong University, Jinan, 250022, China.
| | - Hong Cao
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Sheng-He Huang
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China. .,Saban Research Institute of Childrens Hospital Los Angeles, Department of Pediatrics, University of Southern California, 4650 Sunset Blvd., Mailstop #51, Los Angeles, CA, 90027, USA.
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Day J, Imran D, Ganiem AR, Tjahjani N, Wahyuningsih R, Adawiyah R, Dance D, Mayxay M, Newton P, Phetsouvanh R, Rattanavong S, Chan AK, Heyderman R, van Oosterhout JJ, Chierakul W, Day N, Kamali A, Kibengo F, Ruzagira E, Gray A, Lalloo DG, Beardsley J, Binh TQ, Chau TTH, Chau NVV, Cuc NTK, Farrar J, Hien TT, Van Kinh N, Merson L, Phuong L, Tho LT, Thuy PT, Thwaites G, Wertheim H, Wolbers M. CryptoDex: a randomised, double-blind, placebo-controlled phase III trial of adjunctive dexamethasone in HIV-infected adults with cryptococcal meningitis: study protocol for a randomised control trial. Trials 2014; 15:441. [PMID: 25391338 PMCID: PMC4289250 DOI: 10.1186/1745-6215-15-441] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 09/16/2014] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Cryptococcal meningitis (CM) is a severe AIDS-defining illness with 90-day case mortality as high as 70% in sub-Saharan Africa, despite treatment. It is the leading cause of death in HIV patients in Asia and Africa.No major advance has been made in the treatment of CM since the 1970s. The mainstays of induction therapy are amphotericin B and flucytosine, but these are often poorly available where the disease burden is highest. Adjunctive treatments, such as dexamethasone, have had dramatic effects on mortality in other neurologic infections, but are untested in CM. Given the high death rates in patients receiving current optimal treatment, and the lack of new agents on the horizon, adjuvant treatments, which offer the potential to reduce mortality in CM, should be tested.The principal research question posed by this study is as follows: does adding dexamethasone to standard antifungal therapy for CM reduce mortality? Dexamethasone is a cheap, readily available, and practicable intervention. METHOD A double-blind placebo-controlled trial with parallel arms in which patients are randomised to receive either dexamethasone or placebo, in addition to local standard of care. The study recruits patients in both Asia and Africa to ensure the relevance of its results to the populations in which the disease burden is highest. The 10-week mortality risk in the control group is expected to be between 30% and 50%, depending on location, and the target hazard ratio of 0.7 corresponds to absolute risk reductions in mortality from 30% to 22%, or from 50% to 38%. Assuming an overall 10-week mortality of at least 30% in our study population, recruitment of 824 patients will be sufficient to observe the expected number of deaths. Allowing for some loss to follow-up, the total sample size for this study is 880 patients. To generate robust evidence across both continents, we aim to recruit roughly similar numbers of patients from each continent. The primary end point is 10-week mortality. Ethical approval has been obtained from Oxford University's Tropical Research Ethics Committee (OxTREC), and as locally mandated at each site. TRIAL REGISTRATION International Standard Randomised Controlled Trial Number: ISRCTN59144167 26-July-2012.
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Affiliation(s)
- Jeremy Day
- />Wellcome Trust Major Overseas Programme Vietnam, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | - Darma Imran
- />Cipto Mangunkusum Hospital, Jakarta, Indonesia
| | | | | | - Retno Wahyuningsih
- />Cipto Mangunkusum Hospital, Jakarta, Indonesia
- />Department of Parasitology, Indonesia Christian University, School of Medicine, Jakarta, Indonesia
| | - Robiatul Adawiyah
- />Department of Parasitology, Faculty of Medicine, University of Indonesia, Jakarta, Indonesia
| | - David Dance
- />Laos Oxford Mahosot Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Laos
| | - Mayfong Mayxay
- />Laos Oxford Mahosot Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Laos
| | - Paul Newton
- />Laos Oxford Mahosot Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Laos
| | | | - Sayaphet Rattanavong
- />Laos Oxford Mahosot Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Laos
| | | | - Robert Heyderman
- />Malawi-Liverpool-Wellcome Trust, Clinical Research Programme, University of Malawi College of Medicine, Blantyre, Malawi
| | | | - Wirongrong Chierakul
- />Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Nick Day
- />Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Anatoli Kamali
- />MRC/UVRI Uganda Research Unit on AIDS, Entebbe/Masaka, Uganda
| | - Freddie Kibengo
- />MRC/UVRI Uganda Research Unit on AIDS, Entebbe/Masaka, Uganda
| | - Eugene Ruzagira
- />MRC/UVRI Uganda Research Unit on AIDS, Entebbe/Masaka, Uganda
| | - Alastair Gray
- />Nuffield Department of Population Health, University of Oxford Health Economics Research Centre, Oxford, UK
| | - David G Lalloo
- />Wellcome Trust Tropical Centre Liverpool, Liverpool, UK
| | - Justin Beardsley
- />Wellcome Trust Major Overseas Programme Vietnam, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | | | - Tran Thi Hong Chau
- />Wellcome Trust Major Overseas Programme Vietnam, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | | | | | - Jeremy Farrar
- />Wellcome Trust Major Overseas Programme Vietnam, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | - Tran Tinh Hien
- />Wellcome Trust Major Overseas Programme Vietnam, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | | | - Laura Merson
- />Wellcome Trust Major Overseas Programme Vietnam, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | - Lan Phuong
- />Cho Ray Hospital, Ho Chi Minh City, Vietnam
| | - Loc Truong Tho
- />Wellcome Trust Major Overseas Programme Vietnam, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | | | - Guy Thwaites
- />Wellcome Trust Major Overseas Programme Vietnam, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | - Heiman Wertheim
- />National Hospital for Tropical Diseases Oxford University Clinical Research Unit, Hanoi, Vietnam
| | - Marcel Wolbers
- />Wellcome Trust Major Overseas Programme Vietnam, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
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Abstract
To infect the host and cause disease, many medically important fungi invade normally nonphagocytic host cells, such as endothelial cells and epithelial cells. Host cell invasion is a two-step process consisting of adherence followed by invasion. There are two general mechanisms of host cell invasion, induced endocytosis and active penetration. Furthermore, fungi can traverse epithelial or endothelial cell barriers either by proteolytic degradation of intercellular tight junctions or via a Trojan horse mechanism in which they are transported by leukocytes. Although these mechanisms of host cell invasion have been best studied using Candida albicans and Cryptococcus neoformans, it is probable that other invasive fungi also use one or more of these mechanisms to invade host cells. Identification of these invasion mechanisms holds promise to facilitate the development of new approaches to inhibit fungal invasion and thereby prevent disease.
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Affiliation(s)
- Donald C Sheppard
- Departments of Microbiology and Immunology and Medicine, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Scott G Filler
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California 90502 David Geffen School of Medicine at UCLA, Los Angeles, California 90025
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25
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McHarg S, Hopkins G, Lim L, Garrod D. Down-regulation of desmosomes in cultured cells: the roles of PKC, microtubules and lysosomal/proteasomal degradation. PLoS One 2014; 9:e108570. [PMID: 25291180 PMCID: PMC4188543 DOI: 10.1371/journal.pone.0108570] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 09/01/2014] [Indexed: 11/23/2022] Open
Abstract
Desmosomes are intercellular adhesive junctions of major importance for tissue integrity. To allow cell motility and migration they are down-regulated in epidermal wound healing. Electron microscopy indicates that whole desmosomes are internalised by cells in tissues, but the mechanism of down-regulation is unclear. In this paper we provide an overview of the internalisation of half-desmosomes by cultured cells induced by calcium chelation. Our results show that: (i) half desmosome internalisation is dependent on conventional PKC isoforms; (ii) microtubules transport internalised half desmosomes to the region of the centrosome by a kinesin-dependent mechanism; (iii) desmosomal proteins remain colocalised after internalisation and are not recycled to the cell surface; (iv) internalised desmosomes are degraded by the combined action of lysosomes and proteasomes. We also confirm that half desmosome internalisation is dependent upon the actin cytoskeleton. These results suggest that half desmosomes are not disassembled and recycled during or after internalisation but instead are transported to the centrosomal region where they are degraded. These findings may have significance for the down-regulation of desmosomes in wounds.
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Affiliation(s)
- Selina McHarg
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Gemma Hopkins
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Lusiana Lim
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - David Garrod
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
- * E-mail:
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26
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Invasion of the central nervous system by Cryptococcus neoformans requires a secreted fungal metalloprotease. mBio 2014; 5:e01101-14. [PMID: 24895304 PMCID: PMC4049100 DOI: 10.1128/mbio.01101-14] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Cryptococcus spp. cause life-threatening fungal infection of the central nervous system (CNS), predominantly in patients with a compromised immune system. Why Cryptococcus neoformans has this remarkable tropism for the CNS is not clear. Recent research on cerebral pathogenesis of C. neoformans revealed a predominantly transcellular migration of cryptococci across the brain endothelium; however, the identities of key fungal virulence factors that function specifically to invade the CNS remain unresolved. Here we found that a novel, secreted metalloprotease (Mpr1) that we identified in the extracellular proteome of C. neoformans (CnMpr1) is required for establishing fungal disease in the CNS. Mpr1 belongs to a poorly characterized M36 class of fungalysins that are expressed in only some fungal species. A strain of C. neoformans lacking the gene encoding Mpr1 (mpr1Δ) failed to breach the endothelium in an in vitro model of the human blood-brain barrier (BBB). A mammalian host infected with the mpr1Δ null strain demonstrated significant improvement in survival due to a reduced brain fungal burden and lacked the brain pathology commonly associated with cryptococcal disease. The in vivo studies further indicate that Mpr1 is not required for fungal dissemination and Mpr1 likely targets the brain endothelium specifically. Remarkably, the sole expression of CnMPR1 in Saccharomyces cerevisiae resulted in a robust migration of yeast cells across the brain endothelium, demonstrating Mpr1's specific activity in breaching the BBB and suggesting that Mpr1 may function independently of the hyaluronic acid-CD44 pathway. This distinct role for Mpr1 may develop into innovative treatment options and facilitate a brain-specific drug delivery platform. IMPORTANCE Cryptococcus neoformans is a medically relevant fungal pathogen causing significant morbidity and mortality, particularly in immunocompromised individuals. An intriguing feature is its strong neurotropism, and consequently the hallmark of cryptococcal disease is a brain infection, cryptococcal meningoencephalitis. For C. neoformans to penetrate the central nervous system (CNS), it first breaches the blood-brain barrier via a transcellular pathway; however, the identities of fungal factors required for this transmigration remain largely unknown. In an effort to identify extracellular fungal proteins that could mediate interactions with the brain endothelium, we undertook a proteomic analysis of the extracellular proteome and identified a secreted metalloprotease (Mpr1) belonging to the M36 class of fungalysins. Here we found that Mpr1 promotes migration of C. neoformans across the brain endothelium and into the CNS by facilitating attachment of cryptococci to the endothelium surface, thus underscoring the critical role of M36 proteases in fungal pathogenesis.
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27
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Srikanta D, Santiago-Tirado FH, Doering TL. Cryptococcus neoformans: historical curiosity to modern pathogen. Yeast 2014; 31:47-60. [PMID: 24375706 PMCID: PMC3938112 DOI: 10.1002/yea.2997] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 12/06/2013] [Accepted: 12/10/2013] [Indexed: 12/22/2022] Open
Abstract
The importance of the Basidiomycete Cryptococcus neoformans to human health has stimulated its development as an experimental model for both basic physiology and pathogenesis. We briefly review the history of this fascinating and versatile fungus, some notable aspects of its biology that contribute to virulence, and current tools available for its study.
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Affiliation(s)
- Deepa. Srikanta
- Department of Molecular Microbiology, Washington University School of Medicine
| | | | - Tamara L. Doering
- Department of Molecular Microbiology, Washington University School of Medicine
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28
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Filler SG. Can host receptors for fungi be targeted for treatment of fungal infections? Trends Microbiol 2013; 21:389-96. [PMID: 23796589 DOI: 10.1016/j.tim.2013.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 05/23/2013] [Accepted: 05/24/2013] [Indexed: 11/19/2022]
Abstract
The invasion and stimulation of normally non-phagocytic host cells, such as epithelial and endothelial cells, is a key step in the pathogenesis of many fungal infections. In most cases, host cell invasion and/or stimulation of a proinflammatory response is induced when proteins or carbohydrates on the fungal cell surface bind to receptors on the host cell. Although many of these fungal-host cell interactions have only been investigated in vitro, the therapeutic efficacy of blocking the host cell receptors for Candida albicans and Rhizopus oryzae has been demonstrated in experimental animal models of infection. We summarize recent studies of the fungal receptors on normally non-phagocytic host cells and the therapeutic implications of blocking these receptors.
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Affiliation(s)
- Scott G Filler
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, 1124 West Carson Street, Torrance, CA 90502, USA.
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29
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Liu TB, Kim JC, Wang Y, Toffaletti DL, Eugenin E, Perfect JR, Kim KJ, Xue C. Brain inositol is a novel stimulator for promoting Cryptococcus penetration of the blood-brain barrier. PLoS Pathog 2013; 9:e1003247. [PMID: 23592982 PMCID: PMC3617100 DOI: 10.1371/journal.ppat.1003247] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 02/01/2013] [Indexed: 11/17/2022] Open
Abstract
Cryptococcus neoformans is the most common cause of fungal meningitis, with high mortality and morbidity. The reason for the frequent occurrence of Cryptococcus infection in the central nervous system (CNS) is poorly understood. The facts that human and animal brains contain abundant inositol and that Cryptococcus has a sophisticated system for the acquisition of inositol from the environment suggests that host inositol utilization may contribute to the development of cryptococcal meningitis. In this study, we found that inositol plays an important role in Cryptococcus traversal across the blood-brain barrier (BBB) both in an in vitro human BBB model and in in vivo animal models. The capacity of inositol to stimulate BBB crossing was dependent upon fungal inositol transporters, indicated by a 70% reduction in transmigration efficiency in mutant strains lacking two major inositol transporters, Itr1a and Itr3c. Upregulation of genes involved in the inositol catabolic pathway was evident in a microarray analysis following inositol treatment. In addition, inositol increased the production of hyaluronic acid in Cryptococcus cells, which is a ligand known to binding host CD44 receptor for their invasion. These studies suggest an inositol-dependent Cryptococcus traversal of the BBB, and support our hypothesis that utilization of host-derived inositol by Cryptococcus contributes to CNS infection. Cryptococcus neoformans is an AIDS-associated human fungal pathogen that annually causes over 1 million cases of meningitis world-wide, and more than 600,000 attributable deaths. Cryptococcus often causes lung and brain infection and is the leading cause of fungal meningitis in immunosuppressed patients. Why Cryptococcus frequently infects the central nervous system to cause fatal meningitis is an unanswered critical question. Our previous studies revealed a sophisticated inositol acquisition system in Cryptococcus that plays a central role in utilizing environmental inositol to complete its sexual cycle. Here we further demonstrate that inositol acquisition is also important for fungal infection in the brain, where abundant inositol is available. We found that inositol promotes the traversal of Cryptococcus across the blood-brain barrier (BBB), and such stimulation is fungal inositol transporter dependent. We also identified the effects of host inositol on fungal cellular functions that contribute to the stimulation of fungal penetration of the BBB. We propose that inositol utilization is a novel virulence factor for CNS cryptococcosis. Our work lays an important foundation for understanding how fungi respond to available host inositol and indicates the impact of host inositol acquisition on the development of cryptococcal meningitis.
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Affiliation(s)
- Tong-Bao Liu
- Public Health Research Institute Center, University of Medicine and Dentistry of New Jersey, Newark, New Jersey, United States of America
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30
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Stie J, Fox D. Induction of brain microvascular endothelial cell urokinase expression by Cryptococcus neoformans facilitates blood-brain barrier invasion. PLoS One 2012; 7:e49402. [PMID: 23145170 PMCID: PMC3493525 DOI: 10.1371/journal.pone.0049402] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 10/10/2012] [Indexed: 11/30/2022] Open
Abstract
The invasive ability of the blood-borne fungal pathogen Cryptococcus neoformans can be enhanced through interactions with host plasma components, such as plasminogen. Previously we showed by in vitro studies that plasminogen coats the surface of C. neoformans and is converted to the active serine protease, plasmin, by host plasminogen activators. Viable, but not formaldehyde- or sodium azide-killed, cryptococcal strains undergo brain microvascular endothelial cell-dependent plasminogen-to-plasmin activation, which results in enhanced, plasmin-dependent cryptococcal invasion of primary bovine brain microvascular endothelial cells and fungal ability to degrade plasmin substrates. In the present work, brain microvascular endothelial cells cultured with viable, but not killed, cryptococcal strains led to significant increases in both urokinase mRNA transcription and cell-associated urokinase protein expression. Soluble urokinase was also detected in conditioned medium from brain microvascular endothelial cells cultured with viable, but not killed, C. neoformans. Exposure of plasminogen pre-coated viable C. neoformans to conditioned medium from strain-matched brain microvascular endothelial cell-fungal co-cultures resulted in plasminogen-to-plasmin activation and plasmin-dependent cryptococcal invasion. siRNA-mediated silencing of urokinase gene expression or the use of specific inhibitors of urokinase activity abrogated both plasminogen-to-plasmin activation on C. neoformans and cryptococcal-brain microvascular endothelial cell invasion. Our results suggest that pathogen exploitation of the host urokinase-plasmin(ogen) system may contribute to C. neoformans virulence during invasive cryptococcosis.
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Affiliation(s)
- Jamal Stie
- Research Institute for Children, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Deborah Fox
- Research Institute for Children, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
- Department of Pediatrics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
- * E-mail:
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31
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Cryptococcus neoformans-derived microvesicles enhance the pathogenesis of fungal brain infection. PLoS One 2012; 7:e48570. [PMID: 23144903 PMCID: PMC3492498 DOI: 10.1371/journal.pone.0048570] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 09/27/2012] [Indexed: 12/22/2022] Open
Abstract
Cryptococcal meningoencephalitis is the most common fungal disease in the central nervous system. The mechanisms by which Cryptococcus neoformans invades the brain are largely unknown. In this study, we found that C. neoformans-derived microvesicles (CnMVs) can enhance the traversal of the blood-brain barrier (BBB) by C. neoformans invitro. The immunofluorescence imaging demonstrates that CnMVs can fuse with human brain microvascular endothelial cells (HBMECs), the constituents of the BBB. This activity is presumably due to the ability of the CnMVs to activate HBMEC membrane rafts and induce cell fusogenic activity. CnMVs also enhanced C. neoformans infection of the brain, found in both infected brains and cerebrospinal fluid. In infected mouse brains, CnMVs are distributed inside and around C. neoformans-induced cystic lesions. GFAP (glial fibrillary acidic protein)-positive astrocytes were found surrounding the cystic lesions, overlapping with the 14-3-3-GFP (14-3-3-green fluorescence protein fusion) signals. Substantial changes could be observed in areas that have a high density of CnMV staining. This is the first demonstration that C. neoformans-derived microvesicles can facilitate cryptococcal traversal across the BBB and accumulate at lesion sites of C. neoformans-infected brains. Results of this study suggested that CnMVs play an important role in the pathogenesis of cryptococcal meningoencephalitis.
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32
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Abstract
The human fungal pathogen Cryptococcus neoformans is characterized by its ability to induce a distinct polysaccharide capsule in response to a number of host-specific environmental stimuli. The induction of capsule is a complex biological process encompassing regulation at multiple steps, including the biosynthesis, transport, and maintenance of the polysaccharide at the cell surface. By precisely regulating the composition of its cell surface and secreted polysaccharides, C. neoformans has developed intricate ways to establish chronic infection and dormancy in the human host. The plasticity of the capsule structure in response to various host conditions also underscores the complex relationship between host and parasite. Much of this precise regulation of capsule is achieved through the transcriptional responses of multiple conserved signaling pathways that have been coopted to regulate this C. neoformans-specific virulence-associated phenotype. This review focuses on specific host stimuli that trigger the activation of the signal transduction cascades and on the downstream transcriptional responses that are required for robust encapsulation around the cell.
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33
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Shi M, Colarusso P, Calaruso P, Mody CH. Real-time in vivo imaging of fungal migration to the central nervous system. Cell Microbiol 2012; 14:1819-27. [PMID: 22966777 DOI: 10.1111/cmi.12027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Revised: 08/26/2012] [Accepted: 08/29/2012] [Indexed: 01/18/2023]
Abstract
Recent technical advances have afforded valuable new insights into the pathogenesis of fungal infections in the central nervous system (CNS), which continue to cause devastating complications, particularly in immunocompromised individuals. To cause CNS mycosis, organisms such as Cryptococcus neoformans become blood borne and progress through a series of pathogenic checkpoints that culminate in fungal replication in the brain. Critical steps include fungal arrest in the vasculature of the brain, interaction and signalling of the fungal and endothelial cells leading to transmigration with subsequent parenchymal invasion and fungal replication in the CNS. Previous studies that made use of in vitro and ex vivo approaches contributed greatly to our understanding of brain invasion by fungi. However, the knowledge gained from previous studies relied on in vitro models that did not account for vascular haemodynamics. For this reason, more refined approaches that model blood flow and vascular anatomy are required, andultimately studying fungal invasion and dissemination in vivo. Indeed, in vivo imaging (also known as intravital imaging) has emerged as a valuable technique to probe host-pathogen interactions. In this review, with a focus on C. neoformans, we will provide an overview of the applications of the prior techniques and recent advances, their strengths and limitations in characterizing the migration of fungi into the brain, and unanswered questions that may provide new directions for research.
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Affiliation(s)
- Meiqing Shi
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD 20742, USA
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34
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Tseng HK, Liu CP, Price MS, Jong AY, Chang JC, Toffaletti DL, Betancourt-Quiroz M, Frazzitta AE, Cho WL, Perfect JR. Identification of genes from the fungal pathogen Cryptococcus neoformans related to transmigration into the central nervous system. PLoS One 2012; 7:e45083. [PMID: 23028773 PMCID: PMC3447876 DOI: 10.1371/journal.pone.0045083] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 08/17/2012] [Indexed: 12/25/2022] Open
Abstract
Background A mouse brain transmigration assessment (MBTA) was created to investigate the central nervous system (CNS) pathogenesis of cryptococcal meningoencephalitis. Methodology/Principal Findings Two cryptococcal mutants were identified from a pool of 109 pre-selected mutants that were signature-tagged with the nourseothricin acetyltransferase (NAT) resistance cassette. These two mutants displayed abnormal transmigration into the central nervous system. One mutant displaying decreased transmigration contains a null mutation in the putative FNX1 gene, whereas the other mutant possessing a null mutation in the putative RUB1 gene exhibited increased transmigration into the brain. Two macrophage adhesion-defective mutants in the pool, 12F1 and 3C9, showed reduced phagocytosis by macrophages, but displayed no defects in CNS entry suggesting that transit within macrophages (the “Trojan horse” model of CNS entry) is not the primary mechanism for C. neoformans migration into the CNS in this MBTA. Conclusions/Significance This research design provides a new strategy for genetic impact studies on how Cryptococcus passes through the blood-brain barrier (BBB), and the specific isolated mutants in this assay support a transcellular mechanism of CNS entry.
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Affiliation(s)
- Hsiang-Kuang Tseng
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
- Division of Infectious Diseases, Department of Internal Medicine, Mackay Memorial Hospital, Taipei, Taiwan
- Department of Medicine, Mackay Medical College, New Taipei, Taiwan
| | - Chang-Pan Liu
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Michael S. Price
- Division of Infectious Diseases, Department of Medicine, Duke University Medical Center, Durham, NC, United States of America
| | - Ambrose Y. Jong
- Division of Hematology-Oncology, The Saban Research Institute, Children’s Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Jui-Chih Chang
- Division of Thoracic and Cardiovascular Surgery, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
| | - Dena L. Toffaletti
- Division of Infectious Diseases, Department of Medicine, Duke University Medical Center, Durham, NC, United States of America
| | - Marisol Betancourt-Quiroz
- Division of Infectious Diseases, Department of Medicine, Duke University Medical Center, Durham, NC, United States of America
| | - Aubrey E. Frazzitta
- Division of Infectious Diseases, Department of Medicine, Duke University Medical Center, Durham, NC, United States of America
| | - Wen-Long Cho
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
- Department of Medicine, Mackay Medical College, New Taipei, Taiwan
- * E-mail: (WLC); (JRP)
| | - John R. Perfect
- Division of Infectious Diseases, Department of Medicine, Duke University Medical Center, Durham, NC, United States of America
- * E-mail: (WLC); (JRP)
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35
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Kim JC, Crary B, Chang YC, Kwon-Chung KJ, Kim KJ. Cryptococcus neoformans activates RhoGTPase proteins followed by protein kinase C, focal adhesion kinase, and ezrin to promote traversal across the blood-brain barrier. J Biol Chem 2012; 287:36147-57. [PMID: 22898813 DOI: 10.1074/jbc.m112.389676] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cryptococcus neoformans is an opportunistic fungal pathogen that causes meningoencephalitis. Previous studies have demonstrated that Cryptococcus binding and invasion of human brain microvascular endothelial cells (HBMEC) is a prerequisite for transmigration across the blood-brain barrier. However, the molecular mechanism involved in the cryptococcal blood-brain barrier traversal is poorly understood. In this study we examined the signaling events in HBMEC during interaction with C. neoformans. Analysis with inhibitors revealed that cryptococcal association, invasion, and transmigration require host actin cytoskeleton rearrangement. Rho pulldown assays revealed that Cryptococcus induces activation of three members of RhoGTPases, e.g. RhoA, Rac1, and Cdc42, and their activations are required for cryptococcal transmigration across the HBMEC monolayer. Western blot analysis showed that Cryptococcus also induces phosphorylation of focal adhesion kinase (FAK), ezrin, and protein kinase C α (PKCα), all of which are involved in the rearrangement of host actin cytoskeleton. Down-regulation of FAK, ezrin, or PKCα by shRNA knockdown, dominant-negative transfection, or inhibitors significantly reduces cryptococcal ability to traverse the HBMEC monolayer, indicating their positive role in cryptococcal transmigration. In addition, activation of RhoGTPases is the upstream event for phosphorylation of FAK, ezrin, and PKCα during C. neoformans-HBMEC interaction. Taken together, our findings demonstrate that C. neoformans activates RhoGTPases and subsequently FAK, ezrin, and PKCα to promote their traversal across the HBMEC monolayer, which is the critical step for cryptococcal brain infection and development of meningitis.
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Affiliation(s)
- Jong-Chul Kim
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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Tucker IG, Yang L, Mujoo H. Delivery of drugs to the brain via the blood brain barrier using colloidal carriers. J Microencapsul 2012; 29:475-86. [PMID: 22563886 DOI: 10.3109/02652048.2012.658445] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Delivering drugs to the brain is challenging given the selective permeability of the blood brain barrier (BBB). Targeted colloidal carriers containing drug payloads offer some promise for enhanced and perhaps selective delivery to brain. This review examines the recent literature and identifies issues to be addressed if these systems are to be rationally designed. These include opsonization of nanoparticles and off-target clearance; the cerebral microvasculature, flow of nanoparticles in capillaries and binding to the capillary wall; and transcytosis. Capillary architecture, blood flow and BBB permeability are affected by disease and age and there are species differences. These complexities caution against making extravagant claims for a particular nanosystem but they also highlight the rich opportunities and need for critical research in this field.
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Affiliation(s)
- Ian G Tucker
- School of Pharmacy, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
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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.
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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
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Lipid raft/caveolae signaling is required for Cryptococcus neoformans invasion into human brain microvascular endothelial cells. J Biomed Sci 2012; 19:19. [PMID: 22316086 PMCID: PMC3308189 DOI: 10.1186/1423-0127-19-19] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 02/08/2012] [Indexed: 12/30/2022] Open
Abstract
Background Cryptococcus neoformans has a predilection for central nervous system infection. C. neoformans traversal of the blood brain barrier, composed of human brain microvascular endothelial cells (HBMEC), is the crucial step in brain infection. However, the molecular mechanism of the interaction between Cryptococcus neoformans and HBMEC, relevant to its brain invasion, is still largely unknown. Methods In this report, we explored several cellular and molecular events involving the membrane lipid rafts and caveolin-1 (Cav1) of HBMEC during C. neoformans infection. Immunofluorescence microscopy was used to examine the roles of Cav1. The knockdown of Cav1 by the siRNA treatment was performed. Phosphorylation of Cav1 relevant to its invasion functions was investigated. Results We found that the host receptor CD44 colocalized with Cav1 on the plasma membrane, and knockdown of Cav1 significantly reduced the fungal ability to invade HBMEC. Although the CD44 molecules were still present, HBMEC membrane organization was distorted by Cav1 knockdown. Concomitantly, knockdown of Cav1 significantly reduced the fungal crossing of the HBMEC monolayer in vitro. Upon C. neoformans engagement, host Cav1 was phosphorylated in a CD44-dependent manner. This phosphorylation was diminished by filipin, a disrupter of lipid raft structure. Furthermore, the phosphorylated Cav1 at the lipid raft migrated inward to the perinuclear localization. Interestingly, the phospho-Cav1 formed a thread-like structure and colocalized with actin filaments but not with the microtubule network. Conclusion These data support that C. neoformans internalization into HBMEC is a lipid raft/caveolae-dependent endocytic process where the actin cytoskeleton is involved, and the Cav1 plays an essential role in C. neoformans traversal of the blood-brain barrier.
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Chi F, Wang L, Zheng X, Jong A, Huang SH. Recruitment of α7 nicotinic acetylcholine receptor to caveolin-1-enriched lipid rafts is required for nicotine-enhanced Escherichia coli K1 entry into brain endothelial cells. Future Microbiol 2011; 6:953-66. [PMID: 21861625 DOI: 10.2217/fmb.11.65] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM We investigate how the α7 nicotinic acetylcholine receptor (α7 nAChR), an essential regulator of inflammation, contributes to the α7 agonist nicotine-enhanced Escherichia coli K1 invasion of human brain microvascular endothelial cells (HBMECs) through lipid rafts/caveolae-mediated signaling. MATERIALS & METHODS α7 nAChR-mediated signaling and bacterial invasion were defined by lipid raft fractionation, immunofluorescence microscopy and siRNA knockdown. RESULTS Nicotine-enhanced bacterial invasion was dose-dependently inhibited by two raft-disrupting agents, nystatin and filipin. Significant accumulation of the lipid raft marker GM3 was observed in HBMEC induced by E. coli K1 and nicotine. The recruitment of α7 nAChR and related signaling molecules, including vimentin, and Erk1/2, to caveolin-1 enriched lipid rafts was increased upon treatment with E44 or E44 plus nicotine. Erk1/2 activation (phosphorylation), which is required for α7 nAChR-mediated signaling and E44 invasion, was associated with lipid rafts and nicotine-enhanced bacterial infection. Furthermore, E44 invasion, E44/nicotine-induced activation of Erk1/2 and clustering of α7 nAChR and caveolin-1 was specifically blocked by both siRNAs. CONCLUSION α7 nAChR-mediated signaling through lipid rafts/caveolae is required for nicotine-enhanced E. coli K1 invasion of HBMEC.
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Affiliation(s)
- Feng Chi
- Saban Research Institute of Childrens Hospital Los Angeles, Department of Pediatrics, University of Southern California, USA
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HIV-1 gp41 ectodomain enhances Cryptococcus neoformans binding to human brain microvascular endothelial cells via gp41 core-induced membrane activities. Biochem J 2011; 438:457-66. [PMID: 21668410 DOI: 10.1042/bj20110218] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cryptococcus neoformans causes life-threatening meningoencephalitis, particularly prevalent in AIDS patients. The interrelationship between C. neoformans and HIV-1 is intriguing, as both pathogens elicit severe neuropathological complications. We have previously demonstrated that the HIV-1 gp41 ectodomain fragments gp41-I33 (amino acids 579-611) and gp41-I90 (amino acids 550-639) can enhance C. neoformans binding to HBMECs (human brain microvascular endothelial cells). Both peptides contain the loop region of gp41. In the present study, we used immunofluorescence microscopy and transmission and scanning electron microscopy to explore the underlying mechanisms. Our findings indicated that both C. neoformans and gp41-I90 up-regulated ICAM-1 (intercellular adhesion molecule 1) on the HBMECs and elicited membrane ruffling on the surface of HBMECs. The HIV-1 gp41 ectodomain could also induce CD44 and β-actin redistribution to the membrane lipid rafts, but it could not enhance PKCα (protein kinase Cα) phosphorylation like C. neoformans. Instead, gp41-I90 was able to induce syncytium formation on HBMECs. The results of the present study suggest HIV-1 gp41-enhanced C. neoformans binding to HBMECs via gp41 core domain-induced membrane activities, revealing a potential mechanism of invasion for this pathogenic fungus into the brain tissues of HIV-1-infected patients.
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Stie J, Fox D. Blood-brain barrier invasion by Cryptococcus neoformans is enhanced by functional interactions with plasmin. MICROBIOLOGY-SGM 2011; 158:240-258. [PMID: 21998162 DOI: 10.1099/mic.0.051524-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cryptococcus neoformans can invade the central nervous system through diverse mechanisms. We examined a possible role for host plasma proteases in the neurotropic behaviour of this blood-borne fungal pathogen. Plasminogen is a plasma-enriched zymogen that can passively coat the surface of blood-borne pathogens and, upon conversion to the serine protease plasmin, facilitate pathogen dissemination by degrading vascular barriers. In this study, plasminogen-to-plasmin conversion on killed and viable hypoencapsulated strains of C. neoformans required the addition of plasminogen activator (PA), but this conversion occurred in the absence of supplemented PA when viable strains were cultured with brain microvascular endothelial cells (BMEC). Plasmin-coated C. neoformans showed an enhanced invasive ability in Matrigel invasion assays that was significantly augmented in the presence of BMEC. The invasive effect of plasmin required viable pathogen and correlated with rapid declines in BMEC barrier function. Plasmin-enhanced invasion was inhibited by aprotinin, carboxypeptidase B, the lysine analogue epsilon-aminocaproic acid, and by capsule development. C. neoformans caused plasminogen-independent declines in BMEC barrier function that were associated with pathogen-induced host damage; however, such declines were significantly delayed and less extensive than those observed with plasmin-coated pathogen. BMEC adhesion and damage by hypoencapsulated C. neoformans were diminished by capsule induction but unaltered by plasminogen and/or PA. We conclude that hypoencapsulated C. neoformans can invade BMEC by a plasmin-dependent mechanism, in vitro, and that small, or minimal, surface capsule expression during the blood-borne phase of cryptococcosis may promote virulence by means of plasmin(ogen) acquisition.
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Affiliation(s)
- Jamal Stie
- Research Institute for Children, Louisiana State University Health Sciences Center, New Orleans, LA 70118, USA
| | - Deborah Fox
- Department of Pediatrics, Louisiana State University Health Sciences Center, New Orleans, LA 70118, USA.,Research Institute for Children, Louisiana State University Health Sciences Center, New Orleans, LA 70118, USA
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Chen Y, Chen J, Wen H, Gao P, Wang J, Zheng Z, Gu J. S100A10 downregulation inhibits the phagocytosis of Cryptococcus neoformans by murine brain microvascular endothelial cells. Microb Pathog 2011; 51:96-100. [DOI: 10.1016/j.micpath.2011.05.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 05/11/2011] [Accepted: 05/12/2011] [Indexed: 12/25/2022]
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Huang SH, Long M, Wu CH, Kwon-Chung KJ, Chang YC, Chi F, Lee S, Jong A. Invasion of Cryptococcus neoformans into human brain microvascular endothelial cells is mediated through the lipid rafts-endocytic pathway via the dual specificity tyrosine phosphorylation-regulated kinase 3 (DYRK3). J Biol Chem 2011; 286:34761-9. [PMID: 21693704 DOI: 10.1074/jbc.m111.219378] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cryptococcus neoformans is a neurotropic fungal pathogen, which provokes the onset of devastating meningoencephalitis. We used human brain microvascular endothelial cells (HBMEC) as the in vitro model to investigate how C. neoformans traverses across the blood-brain barrier. In this study, we present several lines of evidence indicating that C. neoformans invasion is mediated through the endocytic pathway via lipid rafts. Human CD44 molecules from lipid rafts can directly interact with hyaluronic acid, the C. neoformans ligand. Bikunin, which perturbs CD44 function in the lipid raft, can block C. neoformans adhesion and invasion of HBMEC. The lipid raft marker, ganglioside GM1, co-localizes with CD44 on the plasma membrane, and C. neoformans cells can adhere to the host cell in areas where GM1 is enriched. These findings suggest that C. neoformans entry takes place on the lipid rafts. Upon C. neoformans engagement, GM1 is internalized through vesicular structures to the nuclear membrane. This endocytic redistribution process is abolished by cytochalasin D, nocodazole, or anti-DYRK3 (dual specificity tyrosine-phosphorylation-regulated kinase 3) siRNA. Concomitantly, the knockdown of DYRK3 significantly reduces C. neoformans invasion across the HBMEC monolayer in vitro. Our data demonstrate that the lipid raft-dependent endocytosis process mediates C. neoformans internalization into HBMEC and that the CD44 protein of the hosts, cytoskeleton, and intracellular kinase-DYRK3 are involved in this process.
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Affiliation(s)
- Sheng-He Huang
- Department of Pediatrics, Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California 90027, USA
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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.
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Affiliation(s)
- Michal A Olszewski
- Ann Arbor Veterans Administration Health System (11R), 2215 Fuller Road, Ann Arbor, MI 48105, USA.
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Casadevall A. Cryptococci at the brain gate: break and enter or use a Trojan horse? J Clin Invest 2010; 120:1389-92. [PMID: 20424319 DOI: 10.1172/jci42949] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The mechanism by which Cryptococcus neoformans invades the central nervous system is fundamental for understanding pathogenesis because cryptococcosis commonly presents as meningoencephalitis. There is evidence for both direct invasion of the endothelial cells lining the brain vasculature and a "Trojan horse" mechanism whereby cryptococci enter the central nervous system after macrophage ingestion. However, in this issue of the JCI, Shi et al. use intravital microscopy to reveal that brain invasion by C. neoformans follows a capillary microembolic event. They find that after suddenly stopping in brain capillaries, cryptococci cross into the central nervous system in a process that is urease dependent, requires viability, and involves cellular deformation. This observation provides evidence for direct brain invasion by C. neoformans, but a consideration of all the currently available evidence suggests a role for both direct and phagocyte-associated invasion. Hence, the remarkable neurotropism of C. neoformans may have more than one mechanism.
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Affiliation(s)
- Arturo Casadevall
- Department of Microbiology and Immunology and Medicine, Albert Einstein College of Medicine, New York, New York, USA.
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Pulzova L, Bhide MR, Andrej K. Pathogen translocation across the blood-brain barrier. ACTA ACUST UNITED AC 2009; 57:203-13. [DOI: 10.1111/j.1574-695x.2009.00594.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Immortalized human brain endothelial cell line HCMEC/D3 as a model of the blood-brain barrier facilitates in vitro studies of central nervous system infection by Cryptococcus neoformans. EUKARYOTIC CELL 2009; 8:1803-7. [PMID: 19767445 DOI: 10.1128/ec.00240-09] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Cryptococcus neoformans cells must cross the blood-brain barrier prior to invading the central nervous system. Here we demonstrate that the immortalized human brain endothelial cell line HCMEC/D3 is a useful alternative to primary brain endothelial cells as a model of the blood-brain barrier for studies of central nervous system infection.
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