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Francis VI, Liddle C, Camacho E, Kulkarni M, Junior SRS, Harvey JA, Ballou ER, Thomson DD, Brown GD, Hardwick JM, Casadevall A, Witton J, Coelho C. Cryptococcus neoformans rapidly invades the murine brain by sequential breaching of airway and endothelial tissues barriers, followed by engulfment by microglia. mBio 2024; 15:e0307823. [PMID: 38511961 PMCID: PMC11005363 DOI: 10.1128/mbio.03078-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 02/29/2024] [Indexed: 03/22/2024] Open
Abstract
Cryptococcus neoformans causes lethal meningitis and accounts for approximately 10%-15% of AIDS-associated deaths worldwide. There are major gaps in our understanding of how this fungus invades the mammalian brain. To investigate the dynamics of C. neoformans tissue invasion, we mapped fungal localization and host cell interactions in infected brain, lung, and upper airways using mouse models of systemic and airway infection. To enable this, we developed an in situ imaging pipeline capable of measuring large volumes of tissue while preserving anatomical and cellular information by combining thick tissue sections, tissue clarification, and confocal imaging. We confirm high fungal burden in mouse upper airway after nasal inoculation. Yeast in turbinates were frequently titan cells, with faster kinetics than reported in mouse lungs. Importantly, we observed one instance of fungal cells enmeshed in lamina propria of the upper airways, suggesting penetration of airway mucosa as a possible route of tissue invasion and dissemination to the bloodstream. We extend previous literature positing bloodstream dissemination of C. neoformans, by finding viable fungi in the bloodstream of mice a few days after intranasal infection. As early as 24 h post systemic infection, the majority of C. neoformans cells traversed the blood-brain barrier, and were engulfed or in close proximity to microglia. Our work presents a new method for investigating microbial invasion, establishes that C. neoformans can breach multiple tissue barriers within the first days of infection, and demonstrates microglia as the first cells responding to C. neoformans invasion of the brain.IMPORTANCECryptococcal meningitis causes 10%-15% of AIDS-associated deaths globally. Still, brain-specific immunity to cryptococci is a conundrum. By employing innovative imaging, this study reveals what occurs during the first days of infection in brain and in airways. We found that titan cells predominate in upper airways and that cryptococci breach the upper airway mucosa, which implies that, at least in mice, the upper airways are a site for fungal dissemination. This would signify that mucosal immunity of the upper airway needs to be better understood. Importantly, we also show that microglia, the brain-resident macrophages, are the first responders to infection, and microglia clusters are formed surrounding cryptococci. This study opens the field to detailed molecular investigations on airway immune response, how fungus traverses the blood-brain barrier, how microglia respond to infection, and ultimately how microglia monitor the blood-brain barrier to preserve brain function.
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Affiliation(s)
- Vanessa I. Francis
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
- Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom
| | - Corin Liddle
- Bioimaging Facility, University of Exeter, Exeter, United Kingdom
| | - Emma Camacho
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Madhura Kulkarni
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | | | - Jamie A. Harvey
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
| | - Elizabeth R. Ballou
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
| | - Darren D. Thomson
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
| | - Gordon D. Brown
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
- Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom
| | - J. Marie Hardwick
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Arturo Casadevall
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jonathan Witton
- Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom
| | - Carolina Coelho
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
- Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom
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Wang X, Qu L, Chen J, Jin Y, Hu K, Zhou Z, Zhang J, An Y, Zheng J. Toxoplasma rhoptry proteins that affect encephalitis outcome. Cell Death Discov 2023; 9:439. [PMID: 38049394 PMCID: PMC10696021 DOI: 10.1038/s41420-023-01742-1] [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: 06/29/2023] [Revised: 11/07/2023] [Accepted: 11/23/2023] [Indexed: 12/06/2023] Open
Abstract
Toxoplasma gondii, a widespread obligate intracellular parasite, can infect almost all warm-blooded animals, including humans. The cellular barrier of the central nervous system (CNS) is generally able to protect the brain parenchyma from infectious damage. However, T. gondii typically causes latent brain infections in humans and other vertebrates. Here, we discuss how T. gondii rhoptry proteins (ROPs) affect signaling pathways in host cells and speculate how this might affect the outcome of Toxoplasma encephalitis.
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Affiliation(s)
- Xinlei Wang
- Department of Clinical Laboratory, The Second Hospital of Jilin University, Changchun, 130021, China
| | - Lai Qu
- Department of Intensive Care Unit, First Hospital of Jilin University, Changchun, 130021, China
| | - Jie Chen
- Institute of Theoretical Chemistry, Jilin University, Changchun, 130021, China
| | - Yufen Jin
- Department of Clinical Laboratory, The Second Hospital of Jilin University, Changchun, 130021, China
| | - Kaisong Hu
- Department of Pathogenobiology, College of Basic Medical Sciences, Jilin University, Changchun, 130021, China
| | - Zhengjie Zhou
- Department of Pathogenobiology, College of Basic Medical Sciences, Jilin University, Changchun, 130021, China
| | - Jiaqi Zhang
- Department of Pathogenobiology, College of Basic Medical Sciences, Jilin University, Changchun, 130021, China
| | - Yiming An
- Department of Pathogenobiology, College of Basic Medical Sciences, Jilin University, Changchun, 130021, China
| | - Jingtong Zheng
- Department of Pathogenobiology, College of Basic Medical Sciences, Jilin University, Changchun, 130021, China.
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Francis VI, Liddle C, Camacho E, Kulkarni M, Junior SRS, Harvey JA, Ballou ER, Thomson DD, Hardwick JM, Casadevall A, Witton J, Coelho C. Cryptococcus neoformans rapidly invades the murine brain by sequential breaching of airway and endothelial tissues barriers, followed by engulfment by microglia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.13.564824. [PMID: 38014111 PMCID: PMC10680653 DOI: 10.1101/2023.11.13.564824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The fungus Cryptococcus neoformans causes lethal meningitis in humans with weakened immune systems and is estimated to account for 10-15% of AIDS-associated deaths worldwide. There are major gaps in our understanding of how this environmental fungus evades the immune system and invades the mammalian brain before the onset of overt symptoms. To investigate the dynamics of C. neoformans tissue invasion, we mapped early fungal localisation and host cell interactions at early times in infected brain, lung, and upper airways using mouse models of systemic and airway infection. To enable this, we developed an in situ imaging pipeline capable of measuring large volumes of tissue while preserving anatomical and cellular information by combining thick tissue sections, tissue clarification, and confocal imaging. Made possible by these techniques, we confirm high fungal burden in mouse upper airway turbinates after nasal inoculation. Surprisingly, most yeasts in turbinates were titan cells, indicating this microenvironment enables titan cell formation with faster kinetics than reported in mouse lungs. Importantly, we observed one instance of fungal cells enmeshed in lamina propria of upper airways, suggesting penetration of airway mucosa as a possible route of tissue invasion and dissemination to the bloodstream. We extend previous literature positing bloodstream dissemination of C. neoformans, via imaging C. neoformans within blood vessels of mouse lungs and finding viable fungi in the bloodstream of mice a few days after intranasal infection, suggesting that bloodstream access can occur via lung alveoli. In a model of systemic cryptococcosis, we show that as early as 24 h post infection, majority of C. neoformans cells traversed the blood-brain barrier, and are engulfed or in close proximity to microglia. Our work establishes that C. neoformans can breach multiple tissue barriers within the first days of infection. This work presents a new method for investigating cryptococcal invasion mechanisms and demonstrates microglia as the primary cells responding to C. neoformans invasion.
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Affiliation(s)
- Vanessa I Francis
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, EX4 4QD, UK
- Faculty of Health and Life Sciences, University of Exeter, EX4 4QD, UK
| | - Corin Liddle
- Bioimaging Facility, University of Exeter, Exeter, EX4 4QD, UK
| | - Emma Camacho
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Madhura Kulkarni
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Samuel R S Junior
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jamie A Harvey
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, EX4 4QD, UK
| | - Elizabeth R Ballou
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, EX4 4QD, UK
| | - Darren D Thomson
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, EX4 4QD, UK
| | - J Marie Hardwick
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Arturo Casadevall
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jonathan Witton
- Faculty of Health and Life Sciences, University of Exeter, EX4 4QD, UK
| | - Carolina Coelho
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, EX4 4QD, UK
- Faculty of Health and Life Sciences, University of Exeter, EX4 4QD, UK
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Orchanian SB, Lodoen MB. Monocytes as primary defenders against Toxoplasma gondii infection. Trends Parasitol 2023; 39:837-849. [PMID: 37633758 DOI: 10.1016/j.pt.2023.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 07/14/2023] [Accepted: 07/21/2023] [Indexed: 08/28/2023]
Abstract
Monocytes are recruited from the bone marrow to sites of infection where they release cytokines and chemokines, function in antimicrobial immunity, and differentiate into macrophages and dendritic cells to control infection. Although many studies have focused on monocyte-derived macrophages and dendritic cells, recent work has examined the unique roles of monocytes during infection to promote immune defense. We focus on the effector functions of monocytes during infection with the parasite Toxoplasma gondii, and discuss the signals that mobilize monocytes to sites of infection, their production of inflammatory cytokines and antimicrobial mediators, their ability to shape the adaptive immune response, and their immunoregulatory functions. Insights from other infections, including Plasmodium and Listeria are also included for comparison and context.
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Affiliation(s)
- Stephanie B Orchanian
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California, USA; Institute for Immunology, University of California Irvine, Irvine, California, USA
| | - Melissa B Lodoen
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California, USA; Institute for Immunology, University of California Irvine, Irvine, California, USA.
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