1
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Normile TG, Bryan AM, Del Poeta M. Animal Models of Cryptococcus neoformans in Identifying Immune Parameters Associated With Primary Infection and Reactivation of Latent Infection. Front Immunol 2020; 11:581750. [PMID: 33042164 PMCID: PMC7522366 DOI: 10.3389/fimmu.2020.581750] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 08/12/2020] [Indexed: 12/13/2022] Open
Abstract
Cryptococcus species are environmental fungal pathogens and the causative agents of cryptococcosis. Infection occurs upon inhalation of infectious particles, which proliferate in the lung causing a primary infection. From this primary lung infection, fungal cells can eventually disseminate to other organs, particularly the brain, causing lethal meningoencephalitis. However, in most cases, the primary infection resolves with the formation of a lung granuloma. Upon severe immunodeficiency, dormant cryptococcal cells will start proliferating in the lung granuloma and eventually will disseminate to the brain. Many investigators have sought to study the protective host immune response to this pathogen in search of host parameters that keep the proliferation of cryptococcal cells under control. The majority of the work assimilates research carried out using the primary infection animal model, mainly because a reactivation model has been available only very recently. This review will focus on anti-cryptococcal immunity in both the primary and reactivation models. An understanding of the differences in host immunity between the primary and reactivation models will help to define the key host parameters that control the infections and are important for the research and development of new therapeutic and vaccine strategies against cryptococcosis.
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Affiliation(s)
- Tyler G Normile
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY, United States
| | - Arielle M Bryan
- Ingenious Targeting Laboratory Incorporated, Ronkonkoma, NY, United States
| | - Maurizio Del Poeta
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY, United States.,Division of Infectious Diseases, School of Medicine, Stony Brook University, Stony Brook, NY, United States.,Veterans Administration Medical Center, Northport, NY, United States
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2
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Ogbomo H, Timm-McCann M, Barnes T, Xiang RF, Jamil K, Ganguly A, Stack D, Huston SM, Li SS, Colarusso P, Mody CH. Granule-Dependent NK Cell Killing of Cryptococcus Requires Kinesin to Reposition the Cytolytic Machinery for Directed Cytotoxicity. Cell Rep 2019; 24:3017-3032. [PMID: 30208325 DOI: 10.1016/j.celrep.2018.08.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 04/23/2018] [Accepted: 08/10/2018] [Indexed: 12/31/2022] Open
Abstract
Cryptococcus is the most important cause of fungal meningitis in immunocompromised individuals. Host defense against Cryptococcus involves direct killing by NK cells. That NK cells from HIV-infected patients fail to polarize perforin to the microbial synapse and kill C. neoformans led us to explore the mechanisms used to reposition and polarize the cytolytic granules to the synapse. Using live-cell imaging, we observed microtubule and granule movements in response to Cryptococcus that revealed a kinesin-dependent event. Eg5-kinesin bound to perforin-containing granules and was required for association with the microtubules. Inhibition of Eg5-kinesin abrogated dynein-dependent granule convergence to the MTOC and granule and MTOC polarization to the synapse and suppressed NK cell killing of Cryptococcus. In contrast, Eg5-kinesin was dispensable for tumor killing. This reveals an alternative mechanism of MTOC repositioning and granule polarization, not used in tumor cytotoxicity, in which Eg5-kinesin is required to initiate granule movement, leading to microbial killing.
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Affiliation(s)
- Henry Ogbomo
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Martina Timm-McCann
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Tavish Barnes
- Department of Internal Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Richard F Xiang
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Khusraw Jamil
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Anutosh Ganguly
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Danuta Stack
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Shaunna M Huston
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Shu Shun Li
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Pina Colarusso
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Christopher H Mody
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Internal Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
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3
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Xiang RF, Li S, Ogbomo H, Stack D, Mody CH. β1 Integrins Are Required To Mediate NK Cell Killing of Cryptococcus neoformans. THE JOURNAL OF IMMUNOLOGY 2018; 201:2369-2376. [PMID: 30201811 DOI: 10.4049/jimmunol.1701805] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 08/08/2018] [Indexed: 12/22/2022]
Abstract
Cryptococcus neoformans is a fungal pathogen that causes fatal meningitis and pneumonia. During host defense to Cryptococcus, NK cells directly recognize and kill C. neoformans using cytolytic degranulation analogous to killing of tumor cells. This fungal killing requires independent activation of Src family kinase (SFK) and Rac1-mediated pathways. Recognition of C. neoformans requires the natural cytotoxicity receptor, NKp30; however, it is not known whether NKp30 activates both signal transduction pathways or whether a second receptor is involved in activation of one of the pathways. We used primary human NK cells and a human NK cell line and found that NKp30 activates SFK → PI3K but not Rac1 cytotoxic signaling, which led to a search for the receptor leading to Rac1 activation. We found that NK cells require integrin-linked kinase (ILK) to activate Rac1 for effective fungal killing. This observation led to our identification of β1 integrin as an essential anticryptococcal receptor. These findings demonstrate that multiple receptors, including β1 integrins and NKp30 and their proximal signaling pathways, are required for recognition of Cryptococcus, which activates a central cytolytic antimicrobial pathway leading to fungal killing.
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Affiliation(s)
- Richard F Xiang
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta T2N 4N1, Canada; and
| | - ShuShun Li
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta T2N 4N1, Canada; and
| | - Henry Ogbomo
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta T2N 4N1, Canada; and
| | - Danuta Stack
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta T2N 4N1, Canada; and
| | - Christopher H Mody
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada; .,Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta T2N 4N1, Canada; and.,Department of Internal Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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4
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Schmidt S, Tramsen L, Rais B, Ullrich E, Lehrnbecher T. Natural killer cells as a therapeutic tool for infectious diseases - current status and future perspectives. Oncotarget 2018; 9:20891-20907. [PMID: 29755697 PMCID: PMC5945539 DOI: 10.18632/oncotarget.25058] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 03/21/2018] [Indexed: 12/12/2022] Open
Abstract
Natural Killer (NK) cells are involved in the host immune response against infections due to viral, bacterial and fungal pathogens, all of which are a significant cause of morbidity and mortality in immunocompromised patients. Since the recovery of the immune system has a major impact on the outcome of an infectious complication, there is major interest in strengthening the host response in immunocompromised patients, either by using cytokines or growth factors or by adoptive cellular therapies transfusing immune cells such as granulocytes or pathogen-specific T-cells. To date, relatively little is known about the potential of adoptively transferring NK cells in immunocompromised patients with infectious complications, although the anti-cancer property of NK cells is already being investigated in the clinical setting. This review will focus on the antimicrobial properties of NK cells and the current standing and future perspectives of generating and using NK cells as immunotherapy in patients with infectious complications, an approach which is promising and might have an important clinical impact in the future.
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Affiliation(s)
- Stanislaw Schmidt
- Division for Pediatric Hematology and Oncology, Johann Wolfgang Goethe University, Frankfurt, Germany
| | - Lars Tramsen
- Division for Pediatric Hematology and Oncology, Johann Wolfgang Goethe University, Frankfurt, Germany
| | - Bushra Rais
- Division of Stem Cell Transplantation and Immunology, Laboratory for Cellular Immunology, Hospital for Children and Adolescents, Johann Wolfgang Goethe University, Frankfurt, Germany.,LOEWE Center for Cell and Gene Therapy, Cellular Immunology, Johann Wolfgang Goethe University, Frankfurt, Germany
| | - Evelyn Ullrich
- Division of Stem Cell Transplantation and Immunology, Laboratory for Cellular Immunology, Hospital for Children and Adolescents, Johann Wolfgang Goethe University, Frankfurt, Germany.,LOEWE Center for Cell and Gene Therapy, Cellular Immunology, Johann Wolfgang Goethe University, Frankfurt, Germany
| | - Thomas Lehrnbecher
- Division for Pediatric Hematology and Oncology, Johann Wolfgang Goethe University, Frankfurt, Germany.,LOEWE Center for Cell and Gene Therapy, Cellular Immunology, Johann Wolfgang Goethe University, Frankfurt, Germany
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5
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Abstract
Cryptococcus species are encapsulated fungi found in the environment that predominantly cause disease in immunocompromised hosts after inhalation into the lungs. Even with contemporary antifungal regimens, patients with cryptococcosis continue to have high morbidity and mortality rates. The development of more effective therapies may depend on our understanding of the cellular and molecular mechanisms by which the host promotes sterilizing immunity against the fungus. This review will highlight our current knowledge of how Cryptococcus, primarily the species C. neoformans, is sensed by the mammalian host and how subsequent signaling pathways direct the anti-cryptococcal response by effector cells of the innate immune system.
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Affiliation(s)
- Lena J Heung
- Infectious Diseases Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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6
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Li SS, Mody CH. NKp46 Is an NK Cell Fungicidal Pattern Recognition Receptor. Trends Microbiol 2016; 24:929-931. [PMID: 27816327 DOI: 10.1016/j.tim.2016.10.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 10/25/2016] [Indexed: 11/26/2022]
Abstract
Natural killer (NK) cells are an important contributor to innate host defense because of their role in direct microbial recognition and killing. Vitenshtein et al. make an important contribution by demonstrating that NK cells kill Candida glabrata using the NK activating receptor, NKp46, which recognizes the Epa adhesins.
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Affiliation(s)
- Shu Shun Li
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Canada; The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Canada.
| | - Christopher H Mody
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Canada; The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Canada; Department of Medicine, University of Calgary, Calgary, Canada.
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7
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Xiang RF, Stack D, Huston SM, Li SS, Ogbomo H, Kyei SK, Mody CH. Ras-related C3 Botulinum Toxin Substrate (Rac) and Src Family Kinases (SFK) Are Proximal and Essential for Phosphatidylinositol 3-Kinase (PI3K) Activation in Natural Killer (NK) Cell-mediated Direct Cytotoxicity against Cryptococcus neoformans. J Biol Chem 2016; 291:6912-22. [PMID: 26867574 PMCID: PMC4807276 DOI: 10.1074/jbc.m115.681544] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 01/13/2016] [Indexed: 11/06/2022] Open
Abstract
The activity of Rac in leukocytes is essential for immunity. However, its role in NK cell-mediated anti-microbial signaling remains unclear. In this study, we investigated the role of Rac in NK cell mediated anti-cryptococcal killing. We found thatCryptococcus neoformansindependently activates both Rac and SFK pathways in NK cells, and unlike in tumor killing,Cryptococcusinitiated a novel Rac → PI3K → Erk cytotoxicity cascade. Remarkably, Rac was not required for conjugate formation, despite its essential role in NK cytotoxicity againstC. neoformans Taken together, our data show that, unlike observations with tumor cells, NK cells use a novel Rac cytotoxicity pathway in conjunction with SFK, to killC. neoformans.
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Affiliation(s)
- Richard F Xiang
- From the Departments of Microbiology, Immunology and Infectious Diseases and the Snyder Institute for Chronic Disease, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Danuta Stack
- From the Departments of Microbiology, Immunology and Infectious Diseases and the Snyder Institute for Chronic Disease, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Shaunna M Huston
- From the Departments of Microbiology, Immunology and Infectious Diseases and the Snyder Institute for Chronic Disease, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Shu Shun Li
- From the Departments of Microbiology, Immunology and Infectious Diseases and the Snyder Institute for Chronic Disease, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Henry Ogbomo
- From the Departments of Microbiology, Immunology and Infectious Diseases and the Snyder Institute for Chronic Disease, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Stephen K Kyei
- From the Departments of Microbiology, Immunology and Infectious Diseases and the Snyder Institute for Chronic Disease, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Christopher H Mody
- From the Departments of Microbiology, Immunology and Infectious Diseases and the Snyder Institute for Chronic Disease, University of Calgary, Calgary, Alberta T2N 4N1, Canada Internal Medicine and
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8
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Li S, Kyei S, Timm-McCann M, Ogbomo H, Jones G, Shi M, Xiang R, Oykhman P, Huston S, Islam A, Gill M, Robbins S, Mody C. The NK Receptor NKp30 Mediates Direct Fungal Recognition and Killing and Is Diminished in NK Cells from HIV-Infected Patients. Cell Host Microbe 2013; 14:387-97. [DOI: 10.1016/j.chom.2013.09.007] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 07/20/2013] [Accepted: 08/30/2013] [Indexed: 01/10/2023]
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9
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Requirement and redundancy of the Src family kinases Fyn and Lyn in perforin-dependent killing of Cryptococcus neoformans by NK cells. Infect Immun 2013; 81:3912-22. [PMID: 23918783 DOI: 10.1128/iai.00533-13] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Natural killer (NK) cells directly recognize and kill fungi, such as the pathogenic fungus Cryptococcus neoformans, via cytolytic mechanisms. However, the precise signaling pathways governing this NK cell microbicidal activity and the implications for fungal recognition are still unknown. Previously, it was reported that NK cell anticryptococcal activity is mediated through a conserved phosphatidylinositol 3-kinase-extracellular signal-regulated kinase 1/2 (PI3K-ERK1/2) pathway. Using YT (a human NK-like cell line) and primary human NK cells, we sought to identify the upstream, receptor-proximal signaling elements that led to fungal cytolysis. We demonstrate that Src family kinases were activated in response to C. neoformans. Furthermore, pharmacologic inhibition with an Src kinase inhibitor blocked C. neoformans-induced downstream activation of PI3K and ERK1/2 and abrogated cryptococcal killing. At the same time, the inhibitor disrupted the polarization of perforin-containing granules toward the NK cell-cryptococcal synapse but had no effect on conjugate formation between the organism and the NK cell. Finally, small interfering RNA (siRNA) double (but not single) knockdown of two Src family kinases, Fyn and Lyn, blocked cryptococcal killing. Together these data demonstrate a mechanism whereby the Src family kinases, Fyn and Lyn, redundantly mediate anticryptococcal activity through the activation of PI3K and ERK1/2, which in turn facilitates killing by inducing the polarization of perforin-containing granules to the NK cell-cryptococcal synapse.
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10
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Islam A, Li SS, Oykhman P, Timm-McCann M, Huston SM, Stack D, Xiang RF, Kelly MM, Mody CH. An acidic microenvironment increases NK cell killing of Cryptococcus neoformans and Cryptococcus gattii by enhancing perforin degranulation. PLoS Pathog 2013; 9:e1003439. [PMID: 23853583 PMCID: PMC3708852 DOI: 10.1371/journal.ppat.1003439] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 05/06/2013] [Indexed: 12/14/2022] Open
Abstract
Cryptococcus gattii and Cryptococcus neoformans are encapsulated yeasts that can produce a solid tumor-like mass or cryptococcoma. Analogous to malignant tumors, the microenvironment deep within a cryptococcoma is acidic, which presents unique challenges to host defense. Analogous to malignant cells, NK cells kill Cryptococcus. Thus, as in tumor defense, NK cells must kill yeast cells across a gradient from physiologic pH to less than 6 in the center of the cryptococcoma. As acidic pH inhibits anti-tumor activities of NK cells, we sought to determine if there was a similar reduction in the anticryptococcal activity of NK cells. Surprisingly, we found that both primary human NK cells and the human NK cell line, YT, have preserved or even enhanced killing of Cryptococcus in acidic, compared to physiological, pH. Studies to explore the mechanism of enhanced killing revealed that acidic pH does not increase the effector to target ratio, binding of cytolytic cells to Cryptococcus, or the active perforin content in effector cells. By contrast, perforin degranulation was greater at acidic pH, and increased degranulation was preceded by enhanced ERK1/2 phosphorylation, which is essential for killing. Moreover, using a replication defective ras1 knockout strain of Cryptococcus increased degranulation occurred during more rapid replication of the organisms. Finally, NK cells were found intimately associated with C. gattii within the cryptococcoma of a fatal infection. These results suggest that NK cells have amplified signaling, degranulation, and greater killing at low pH and when the organisms are replicating quickly, which would help maintain microbicidal host defense despite an acidic microenvironment. Immune responses that protect from infection must occur in a variety of unique and potentially hostile environments. Within these environments, acidosis causes profound affects on protective responses. Low pH can occur in focal tumor-like infections, such as in a cryptococcoma produced by the fungal pathogen Cryptococcus. Similarly, low pH occurs in focal malignant tumors. It follows that Cryptococcus and malignant cells can both be killed by NK cells, which provide an important mechanism of host defense. Thus, we asked whether low pH, which impairs tumor killing, might also affect NK cell killing of Cryptococcus. Surprisingly, despite impaired tumor killing, NK cells possess enhanced killing of Cryptococcus at low pH. The mechanism involved a gain in intracellular signal transduction that led to enhanced perforin degranulation. This led us to examine NK cells in persistent cryptococcoma of a fatal brain infection and lung. We found that NK cells associate with Cryptococcus within the cryptococcoma, but perforin is reduced. These studies suggest NK cell cytotoxicity need not be impaired at low pH, and that enhanced signal transduction and degranulation at low pH might be used to enhance host defense.
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Affiliation(s)
- Anowara Islam
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Shu Shun Li
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Paul Oykhman
- Department of Medical Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Martina Timm-McCann
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Shaunna M. Huston
- Department of Medical Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Danuta Stack
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Richard F. Xiang
- Department of Medical Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Margaret M. Kelly
- Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Christopher H. Mody
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
- Department of Internal Medicine, University of Calgary, Calgary, Alberta, Canada
- * E-mail:
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11
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Abstract
Cryptococcus neoformans and Cryptococcus gattii are the cause of life-threatening meningoencephalitis in immunocompromised and immunocompetent individuals respectively. The increasing incidence of cryptococcal infection as a result of the AIDS epidemic, the recent emergence of a hypervirulent cryptococcal strain in Canada and the fact that mortality from cryptococcal disease remains high have stimulated intensive research into this organism. Here we outline recent advances in our understanding of C. neoformans and C. gattii, including intraspecific complexity, virulence factors, and key signaling pathways. We discuss the molecular basis of cryptococcal virulence and the interaction between these pathogens and the host immune system. Finally, we discuss future challenges in the study and treatment of cryptococcosis.
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Affiliation(s)
- Hansong Ma
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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12
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Cryptococcus neoformans directly stimulates perforin production and rearms NK cells for enhanced anticryptococcal microbicidal activity. Infect Immun 2009; 77:2436-46. [PMID: 19307209 DOI: 10.1128/iai.01232-08] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
NK cells, in addition to possessing antitumor and antiviral activity, exhibit perforin-dependent microbicidal activity against the opportunistic pathogen Cryptococcus neoformans. However, the factors controlling this response, particularly whether the pathogen itself provides an activation or rearming signal, are largely unknown. The current studies were performed to determine whether exposure to this fungus alters subsequent NK cell anticryptococcal activity. NK cells lost perforin and mobilized lysosome-associated membrane protein 1 to the cell surface following incubation with the fungus, indicating that degranulation had occurred. Despite a reduced perforin content during killing, NK cells acquired an enhanced ability to kill C. neoformans, as demonstrated using auxotrophs that allowed independent assessment of the killing of two strains. De novo protein synthesis was required for optimal killing; however, there was no evidence that a soluble factor contributed to the enhanced anticryptococcal activity. Exposure of NK cells to C. neoformans caused the cells to rearm, as demonstrated by increased perforin mRNA levels and enhanced loss of perforin when transcription was blocked. Degranulation alone was insufficient to provide the activation signal as NK cells lost anticryptococcal activity following treatment with strontium chloride. However, NK cells regained the activity upon prolonged exposure to C. neoformans, which is consistent with activation by the microbe. The enhanced cytotoxicity did not extend to tumor killing since NK cells exposed to C. neoformans failed to kill NK-sensitive tumor targets (K562 cells). These studies demonstrate that there is contact-mediated microbe-specific rearming and activation of microbicidal activity that are necessary for optimal killing of C. neoformans.
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13
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Cleare W, Casadevall A. Scanning electron microscopy of encapsulated and non-encapsulated Cryptococcus neoformans and the effect of glucose on capsular polysaccharide release 1. Med Mycol 2008. [DOI: 10.1111/j.1365-280x.1999.00226.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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14
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Capilla J, Clemons KV, Stevens DA. Animal models: an important tool in mycology. Med Mycol 2007; 45:657-84. [PMID: 18027253 PMCID: PMC7107685 DOI: 10.1080/13693780701644140] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Accepted: 08/22/2007] [Indexed: 10/29/2022] Open
Abstract
Animal models of fungal infections are, and will remain, a key tool in the advancement of the medical mycology. Many different types of animal models of fungal infection have been developed, with murine models the most frequently used, for studies of pathogenesis, virulence, immunology, diagnosis, and therapy. The ability to control numerous variables in performing the model allows us to mimic human disease states and quantitatively monitor the course of the disease. However, no single model can answer all questions and different animal species or different routes of infection can show somewhat different results. Thus, the choice of which animal model to use must be made carefully, addressing issues of the type of human disease to mimic, the parameters to follow and collection of the appropriate data to answer those questions being asked. This review addresses a variety of uses for animal models in medical mycology. It focuses on the most clinically important diseases affecting humans and cites various examples of the different types of studies that have been performed. Overall, animal models of fungal infection will continue to be valuable tools in addressing questions concerning fungal infections and contribute to our deeper understanding of how these infections occur, progress and can be controlled and eliminated.
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Affiliation(s)
- Javier Capilla
- California Institute for Medical Research, San Jose, USA
- Department of Medicine, Division of Infectious Diseases, Santa Clara Valley Medical Center, San Jose, USA
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University, Stanford, California, USA
| | - Karl V. Clemons
- California Institute for Medical Research, San Jose, USA
- Department of Medicine, Division of Infectious Diseases, Santa Clara Valley Medical Center, San Jose, USA
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University, Stanford, California, USA
| | - David A. Stevens
- California Institute for Medical Research, San Jose, USA
- Department of Medicine, Division of Infectious Diseases, Santa Clara Valley Medical Center, San Jose, USA
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University, Stanford, California, USA
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15
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Wiseman JCD, Ma LL, Marr KJ, Jones GJ, Mody CH. Perforin-dependent cryptococcal microbicidal activity in NK cells requires PI3K-dependent ERK1/2 signaling. THE JOURNAL OF IMMUNOLOGY 2007; 178:6456-64. [PMID: 17475875 DOI: 10.4049/jimmunol.178.10.6456] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Previously, NK cells have been reported to kill the opportunistic fungal pathogen Cryptococcus neoformans through a perforin-dependent mechanism; however, the receptor and signaling involved are unknown. In this report we sought to identify the signaling pathways activated and required for direct perforin-mediated killing of microbes. In this study, using the NK-like cell line YT and primary peripheral blood NK cells, it is demonstrated that YT cells kill C. neoformans and that the killing is accompanied by the activation of PI3K. We demonstrate that inhibition of either the catalytic subunit (using a pharmacological inhibitor) or the alpha-regulatory subunit (using small interfering RNA knockdown) of PI3K significantly inhibited the killing of C. neoformans. Downstream of PI3K, ERK1/2 was activated in a PI3K-dependent fashion and was required for cryptococcal killing. Furthermore, we demonstrate that perforin release from YT cells can be detected by 4 h after contact of the YT cells with C. neoformans and that the release of perforin is blocked by pharmacological inhibition of either PI3K or ERK1/2. Defective degranulation is rooted in the inability to polarize perforin-containing granules toward the target. Finally, we demonstrate that PI3K-ERK1/2-dependent signaling is activated and required for the killing of C. neoformans by primary NK cells. Taken together, these data identify a conserved PI3K-ERK1/2 pathway that is used by NK cells during the direct killing of C. neoformans and demonstrate that the pathway is essential in the formation and activation of the microbicidal mechanism.
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Zhou Q, Murphy WJ. Immune response and immunotherapy to Cryptococcus infections. Immunol Res 2007; 35:191-208. [PMID: 17172646 DOI: 10.1385/ir:35:3:191] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 11/11/2022]
Abstract
Cryptococcus neoformans is a ubiquitous fungus that can cause lifethreatening infections during immunosuppressive states such as acquired immunodeficiency syndrome (AIDS) and after bone marrow transplantation (BMT). Infected individuals normally succumb to meningitis and meningoencephalitis caused by dissemination of C. neoformans to the brain. In this review, we analyze the current understanding of the interaction between host immune response and C. neoformans as well as the current state of immunotherapeutic strategies for treating cryptococcosis.
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Affiliation(s)
- Qing Zhou
- Department of Microbiology and Immunology, University of Nevada, Reno, NV 89557, USA
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Ma LL, Wang CLC, Neely GG, Epelman S, Krensky AM, Mody CH. NK Cells Use Perforin Rather than Granulysin for Anticryptococcal Activity. THE JOURNAL OF IMMUNOLOGY 2004; 173:3357-65. [PMID: 15322199 DOI: 10.4049/jimmunol.173.5.3357] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cytotoxic lymphocytes have the capacity to kill microbes directly; however, the mechanisms involved are poorly understood. Using Cryptococcus neoformans, which causes a potentially fatal fungal infection in HIV-infected patients, our previous studies showed that granulysin is necessary, while perforin is dispensable, for CD8 T lymphocyte fungal killing. By contrast, the mechanisms by which NK cells exert their antimicrobial activity are not clear, and in particular, the contribution of granulysin and perforin to NK-mediated antifungal activity is unknown. Primary human NK cells and a human NK cell line YT were found to constitutively express granulysin and perforin, and possessed anticryptococcal activity, in contrast to CD8 T lymphocytes, which required stimulation. When granulysin protein and mRNA were blocked by granulysin small interfering RNA, the NK cell-mediated antifungal effect was not affected in contrast to the abrogated activity observed in CD8 T lymphocytes. However, when perforin was inhibited by concanamycin A, and silenced using hairpin small interfering RNA, the anticryptococcal activities of NK cells were abrogated. Furthermore, when granulysin and perforin were both inhibited, the anticryptococcal activities of the NK cells were not reduced further than by silencing perforin alone. These results indicate that the antifungal activity is constitutively expressed in NK cells in contrast to CD8 T lymphocytes, in which it requires prior activation, and perforin, but not granulysin, plays the dominant role in NK cell anticryptococcal activity, in contrast to CD8 T lymphocytes, in which granulysin, but not perforin, plays the dominant role in anticryptococcal activity.
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Affiliation(s)
- Ling Ling Ma
- Department of Medical Sciences, University of Calgary, Alberta, Canada
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18
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Kawakami K, Koguchi Y, Qureshi MH, Yara S, Kinjo Y, Uezu K, Saito A. NK cells eliminate Cryptococcus neoformans by potentiating the fungicidal activity of macrophages rather than by directly killing them upon stimulation with IL-12 and IL-18. Microbiol Immunol 2001; 44:1043-50. [PMID: 11220678 DOI: 10.1111/j.1348-0421.2000.tb02601.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In the present study, we examined whether natural killer (NK) cells have direct fungicidal activity against Cryptococcus neoformans. Splenic NK cells were obtained from SCID mice and stimulated with a combination of interleukin (IL)-12 and IL-18 in flat culture plates or round tubes. They were then or at the same time cultured with the yeast cells and the number of viable yeast cells was examined. We could not detect direct fungicidal activity by NK cells under any culture condition, although they produced a large amount of IFN-gamma and exerted marked cytotoxic activity against YAC-1 cells. On the other hand, NK cells significantly potentiated the nitric oxide-mediated cryptococcocidal activity of thioglycolate-elicited peritoneal macrophages obtained from SCID mice upon stimulation with IL-12 and IL-18. The culture supernatants of NK cells stimulated with IL-12 and IL-18 provided similar results when used in place of NK cells. The induction of macrophage anticryptococcal activity by NK cells and NK cell culture supernatants were both mediated by IFN-gamma because the specific mAb almost completely abrogated such effect. Considered collectively, our results suggested that NK cells may play a regulatory role in potentiating macrophage-mediated fungicidal mechanisms in host resistance to infection with C. neoformans rather than exerting a direct killing activity against the fungal pathogen.
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Affiliation(s)
- K Kawakami
- The First Department of Internal Medicine, Faculty of Medicine, University of the Ryukyus, Nishihara, Okinawa, Japan.
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Cleare W, Casadevall A. Scanning electron microscopy of encapsulated and non-encapsulated Cryptococcus neoformans and the effect of glucose on capsular polysaccharide release 1. Med Mycol 1999. [DOI: 10.1046/j.1365-280x.1999.00226.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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20
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CLEARE W, CASADEVALL A. Scanning electron microscopy of encapsulated and non-encapsulated Cryptococcus neoformansand the effect of glucose on capsular polysaccharide release. Med Mycol 1999. [DOI: 10.1080/j.1365-280x.1999.00226.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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21
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MARTINS, RODRIGUEZ, SAVARY, GRAZZIUTTI, DESHPANDE, COHEN, COWART, WOODSIDE, McINTYRE, ANAISSIE, REX. Activated lymphocytes reduce adherence of Aspergillus fumigatus. Med Mycol 1998. [DOI: 10.1046/j.1365-280x.1998.00158.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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22
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Martins M, Rodriguez L, Savary C, Grazziutti M, Deshpande D, Cohen D, Cowart R, Woodside D, Mcintyre B, Anaissie E, Rex J. Activated lymphocytes reduce adherence ofAspergillus fumigatus. Med Mycol 1998. [DOI: 10.1080/02681219880000451] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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23
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Murphy JW, Zhou A, Wong SC. Direct interactions of human natural killer cells with Cryptococcus neoformans inhibit granulocyte-macrophage colony-stimulating factor and tumor necrosis factor alpha production. Infect Immun 1997; 65:4564-71. [PMID: 9353034 PMCID: PMC175655 DOI: 10.1128/iai.65.11.4564-4571.1997] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Human natural killer (NK) cells and T lymphocytes can bind to and inhibit the growth of the yeast-like organism Cryptococcus neoformans. Binding of target cells to NK or T cells also has the potential to modulate cytokine production by the effector cells. In this study, we assessed the ability of C. neoformans to modulate NK cell production, or in some cases T-cell production, of granulocyte-macrophage colony-stimulating factor (GM-CSF) or tumor necrosis factor alpha (TNF-alpha). We found that freshly isolated human NK cells from most individuals make GM-CSF and TNF-alpha constitutively when cultured in vitro. The addition of C. neoformans to T-cell fractions which do not make GM-CSF constitutively did not affect GM-CSF production, but the addition of C. neoformans to NK cell fractions significantly reduced the amounts of GM-CSF produced in most NK cell samples. The reduction in the amount of GM-CSF in C. neoformans-NK cell cocultures could not be attributed to loss of lymphocyte viability or to C. neoformans adsorbing or degrading the cytokine and was dependent on direct contact between the NK cells and cryptococcal cells. GM-CSF was not the only cytokine to be down-regulated. TNF-alpha production was also diminished when NK cells were incubated with C. neoformans. The regulation of both cytokines was at the transcriptional level because GM-CSF and TNF-alpha mRNA levels were lower in NK cell samples incubated with C. neoformans than in NK cell samples incubated without C. neoformans. Diminished production of constitutively produced cytokines resulting from the interaction of NK cells with cryptococcal cells has the potential to affect phagocytic cells in the immediate regional environment and to damp the immune response.
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Affiliation(s)
- J W Murphy
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA.
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Muth SM, Murphy JW. Effects of immunization with Cryptococcus neoformans cells or cryptococcal culture filtrate antigen on direct anticryptococcal activities of murine T lymphocytes. Infect Immun 1995; 63:1645-51. [PMID: 7729868 PMCID: PMC173204 DOI: 10.1128/iai.63.5.1645-1651.1995] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Immunizing CBA/J mice with intact Cryptococcus neoformans cells or with a cryptococcal culture filtrate antigen (CneF) induces an anticryptococcal delayed-type hypersensitivity response. Recently, it has been shown that two phenotypically different T-cell populations are responsible for delayed-type hypersensitivity reactivity in mice immunized with intact cryptococcal cells, whereas only one of those populations is present in mice immunized with soluble cryptococcal antigens in complete Freund's adjuvant (CFA). The purpose of this study was to determine if differences occur with regard to direct anticryptococcal activity between T-lymphocyte-enriched populations from mice immunized with intact viable or dead cryptococcal cells and similar cell populations from mice immunized with the soluble cryptococcal culture filtrate antigen, CneF, emulsified in CFA. The percentage of lymphocytes which form conjugates with C. neoformans and the percentage of cryptococcal growth inhibition in vitro are greater with T-lymphocyte-enriched populations from mice sublethally infected with C. neoformans or from mice immunized with intact heat-killed cryptococcal cells in the presence or absence of CFA than with lymphocyte populations from mice immunized with CneF-CFA. Enhanced anticryptococcal activity of T lymphocytes could be induced by immunizing mice with heat-killed C. neoformans cells of serotype A, B, C, or D as well as by immunizing with a similar preparation of an acapsular C. neoformans mutant but not by immunizing with CFA emulsified with CneF prepared from any one of the C. neoformans isolates. These data indicate that the soluble cryptococcal culture filtrate antigens do not induce the same array of functional T lymphocytes as whole cryptococcal cells.
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Affiliation(s)
- S M Muth
- Department of Microbiology and Immunology, University of Oklahoma Health Science Center, Oklahoma City 73190, USA
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25
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Muth SM, Murphy JW. Direct anticryptococcal activity of lymphocytes from Cryptococcus neoformans-immunized mice. Infect Immun 1995; 63:1637-44. [PMID: 7729867 PMCID: PMC173203 DOI: 10.1128/iai.63.5.1637-1644.1995] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Assessment of the direct anticryptococcal activity of murine lymphocytes from both Cryptococcus neoformans-immunized and control mice was the focus of this investigation. We demonstrate that at a 2:1 effector cell-to-cryptococcal target cell ratio, effector cell populations comprised of alpha beta T-cell receptor-positive T lymphocytes (98 to 99% CD3+) from C. neoformans-immunized mice inhibited the growth of cryptococcal cells better than similar populations of lymphocytes from nonimmunized control mice. Almost immediately after mixing of cryptococci with the effector cells, C. neoformans-lymphocyte conjugates were observed. The percentage of conjugates increased over the first 30 min of incubation and then remained constant over the next 1.5 h. T-lymphocyte-enriched populations from C. neoformans-immunized mice formed significantly greater percentages of conjugates with cryptococci than control T lymphocytes at each time period that assessment was made. For growth inhibition to occur, direct contact between the effector and target cells was necessary, as evidenced by abrogation of cryptococcal growth inhibition when lymphocyte and cryptococcal cell populations were separated by a porous membrane during the growth inhibition assay. Vital staining of cryptococci after incubation with the T-cell-enriched populations showed that the T lymphocytes killed the cryptococcal cells.
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Affiliation(s)
- S M Muth
- Department of Microbiology and Immunology, University of Oklahoma Health Science Center, Oklahoma City 73190, USA
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26
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Blasi E, Barluzzi R, Mazzolla R, Bistoni F. Differential host susceptibility to intracerebral infections with Candida albicans and Cryptococcus neoformans. Infect Immun 1993; 61:3476-81. [PMID: 8335378 PMCID: PMC281025 DOI: 10.1128/iai.61.8.3476-3481.1993] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
To investigate the immune defense mechanisms employed against fungi in the brain, mice were experimentally infected by intracerebral inoculation of Candida albicans or Cryptococcus neoformans. Parameters such as median survival time and numbers of yeast cells in the brains were assessed for naive and immunomodulated mice. We found that no mice survived either C. albicans or C. neoformans challenge at doses of > or = 10(6) yeast cells per mouse. However, when the inoculum size was decreased (< or = 10(5) yeast cells per mouse), C. albicans was no longer lethal (100% survival), whereas 100 and 70% of the mice still succumbed to challenge doses of 10(4) and 10(3) C. neoformans yeast cells, respectively. Pharmacological manipulation and transfer experiments revealed that the myelomonocytic compartment had a minor role against C. neoformans but was deeply involved in the control of intracerebral C. albicans infection. By counting the number of yeast cells in the brains of naive and immunomodulated animals, we established that, unlike C. albicans, C. neoformans remained essentially in the brain, where massive colonization and damage occurred whether naive or immunomodulated defense mechanisms were employed by the host. Overall, these data suggest that the differential role of the myelomonocytic compartment, together with the diverse tropisms of the two fungi, can explain the different development and outcome of intracerebral C. albicans and C. neoformans infections.
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Affiliation(s)
- E Blasi
- Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Italy
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27
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Murphy JW, Hidore MR, Wong SC. Direct interactions of human lymphocytes with the yeast-like organism, Cryptococcus neoformans. J Clin Invest 1993; 91:1553-66. [PMID: 8473499 PMCID: PMC288131 DOI: 10.1172/jci116361] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Lymphocytes, especially CD4+ T cells, are essential for clearance of the yeast-like organism Cryptococcus neoformans from the infected host. The mechanism(s) by which the lymphocytes facilitate elimination of cryptococci has not been elucidated. It is generally thought, however, that lymphocytes reactive with C. neoformans indirectly function by production of lymphokines to enhance clearance of the organism by natural effector cells such as macrophages. In the present study, we assessed the ability of freshly isolated human lymphocytes to interact directly with C. neoformans and to limit the growth of the organism in vitro. We found that large granular lymphocytes (LGL) as well as T cells bound to cryptococcal cells when the lymphocytes were mixed with the cryptococcal cells at a 2:1 ratio. The physical binding interactions of the two lymphocyte populations were different. LGL attached to the cryptococcal cells by many microvilli; T lymphocytes associated with the yeast through broad areas of membrane attached to the cryptococcal cell surface. The two types of lymphocyte interactions did not result in phagocytosis but resulted in direct inhibition of cryptococcal growth, making these lymphocyte interactions with cryptococci distinctly different from interactions of monocytes with cryptococci. With the human natural killer (NK) cell line, NK 3.3, we confirmed that NK cells that were present in the LGL population were capable of limiting the growth of C. neoformans. Through immunoelectron microscopy, human CD3+ lymphocytes were seen attached to cryptococcal cells and by mass cytolysis, human CD3+ lymphocytes were shown to be responsible for inhibition of C. neoformans growth. The direct inhibitory interactions of NK cells and T lymphocytes with cryptococcal cells may be important means of host defense against this ubiquitous organism that frequently causes life-threatening disease in AIDS patients.
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Affiliation(s)
- J W Murphy
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City 73190
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28
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Murphy JW. Natural killer cells and Cryptococcus neoformans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1993; 335:269-75. [PMID: 8237604 DOI: 10.1007/978-1-4615-2980-4_37] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- J W Murphy
- University of Oklahoma Health Sciences Center, Department of Microbiology and Immunology, Oklahoma City
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29
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Blasi E, Barluzzi R, Mazzolla R, Mosci P, Bistoni F. Experimental model of intracerebral infection with Cryptococcus neoformans: roles of phagocytes and opsonization. Infect Immun 1992; 60:3682-8. [PMID: 1500177 PMCID: PMC257377 DOI: 10.1128/iai.60.9.3682-3688.1992] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
A murine model of intracerebral (i.c.) infection with Cryptococcus neoformans in which naive mice receiving an i.c. fungal inoculation developed a severe disease has been established. The effect was strictly dependent on the number of microorganisms injected and evolved as lethal meningoencephalitis. Murine susceptibility to i.c. infection with C. neoformans was enhanced by treatment with chloroquine and colchicine, agents known to greatly affect the host phagocytic compartment. Furthermore, the life spans of both naive and drug-treated mice were significantly augmented when opsonized fungi were injected. Therefore, phagocyte-mediated mechanisms are likely involved in local resistance to i.c. infection with C. neoformans. Further support for this conclusion was supplied by in vitro data showing that microglial cells were proficient anticryptococcal effectors, provided opsonized microorganisms were used.
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Affiliation(s)
- E Blasi
- Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Italy
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30
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Merkel G, Cunningham R. The interaction ofCryptococcus neoformanswith primary rat lung cell cultures. Med Mycol 1992. [DOI: 10.1080/02681219280000161] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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31
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Hidore MR, Nabavi N, Sonleitner F, Murphy JW. Murine natural killer cells are fungicidal to Cryptococcus neoformans. Infect Immun 1991; 59:1747-54. [PMID: 1708359 PMCID: PMC257911 DOI: 10.1128/iai.59.5.1747-1754.1991] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Murine natural killer (NK) cells have been shown to bind to and inhibit the growth of Cryptococcus neoformans in vitro and to contribute to clearance of the organism in vivo. However, it is unclear whether NK cells actually kill cryptococci or simply inhibit proliferation of the fungal target. Therefore, the studies presented here were designed to determine whether NK cells are fungicidal to C. neoformans targets. C. neoformans viability was determined on the basis of the metabolic function of two different enzyme systems, as measured by the two vital stains MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and fluorescein diacetate. Cryptococcal viability, as determined by vital stains, was compared with cryptococcal proliferation, as measured by microcolony formation in agarose at the individual cell level and by CFU counts or extinction dilution analysis in the total cell suspension. Initial comparisons of the vital stains and proliferation assays indicated that these methods effectively distinguished between live and heat-killed cryptococci at the individual cell level and in the total cell suspensions. After cryptococci were incubated with murine NK cells for 18 h, vital stains demonstrated that at the single conjugate level and in the total cell suspension, NK cells kill bound C. neoformans target cells. In addition, the numbers of dead cryptococci in the NK cell-C. neoformans suspensions as determined by the vital stains were comparable to the numbers of cryptococci that were unable to proliferate. Kinetics of NK cell-mediated C. neoformans binding and killing at the single conjugate level and in the total cell suspension were assessed by MTT staining at 2-h intervals after mixing effector and target cells, and the data support the concept that NK cell-C. neoformans binding precedes cryptococcal death. Furthermore, unbound, dead fungal cells were observed in the NK cell-C. neoformans suspensions after 18 h, suggesting that NK cell-C. neoformans interactions may involve both effector cell recycling and killing of unbound cryptococci by soluble cytotoxic factors. In conclusion, the results of these studies firmly establish that NK cells kill C. neoformans.
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Affiliation(s)
- M R Hidore
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City 73190
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