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Ehmen HG, Lüder CGK. Long-Term Impact of Toxoplasma gondii Infection on Human Monocytes. Front Cell Infect Microbiol 2019; 9:235. [PMID: 31316920 PMCID: PMC6611340 DOI: 10.3389/fcimb.2019.00235] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 06/14/2019] [Indexed: 12/17/2022] Open
Abstract
Toxoplasma gondii is a prevalent parasite of mammals and birds including up to 30% of humans world-wide. Primary infection of immunocompetent hosts leads to a robust cell-mediated immune response, which controls but does not clear the infection, thus enabling long-term parasite persistence in brain and muscle tissues. Chronic toxoplasmosis in mice is associated with resistance to heterologous pathogens and this has been related to increased numbers of inflammatory monocytes. Here we have analyzed whether chronic T. gondii infection impacts the subset distribution and the phenotype of peripheral human monocytes in vivo and their responses to parasite infection in vitro. CD14+ monocytes from T. gondii-seropositive blood donors expressed significantly less FcγRIII (CD16) than those from seronegative controls, but they did not show a shift in the distribution of classical, intermediate and non-classical monocyte subpopulations. Percentages of CD62L+ and CD64+ monocytes were however decreased and increased, respectively, in chronically infected individuals as compared to naïve controls. Infection of monocyte-enriched PBMCs from both seropositive and seronegative individuals with T. gondii led to an increase of CD14+CD16− classical monocytes and a decrease of CD14+CD16+ double positive monocytes. Remarkably, after in vitro parasite infection, expression of the chemokine receptor CCR2 was severely impaired in monocytes from both, individuals with chronic toxoplasmosis and seronegative controls. In contrast, only monocytes from chronically infected humans but not those from controls dose-dependently up-regulated HLA-DR, DP, DQ expression following in vitro infection. Furthermore, monocyte-enriched PBMCs from seropositive individuals up-regulated IL-12 mRNA more vigorously after in vitro infection than cells from naïve controls. Collectively, our results establish that infection of humans with T. gondii exerts long-term effects on the phenotype and responsiveness of blood monocytes. This may have important implications for innate immune responses to T. gondii and unrelated pathogens.
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Affiliation(s)
- Hauke G Ehmen
- Institute for Medical Microbiology, University Medical Center Goettingen, Georg-August-University, Goettingen, Germany
| | - Carsten G K Lüder
- Institute for Medical Microbiology, University Medical Center Goettingen, Georg-August-University, Goettingen, Germany
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2
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Campos TM, Costa R, Passos S, Carvalho LP. Cytotoxic activity in cutaneous leishmaniasis. Mem Inst Oswaldo Cruz 2017; 112:733-740. [PMID: 29091132 PMCID: PMC5661895 DOI: 10.1590/0074-02760170109] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/10/2017] [Indexed: 01/27/2023] Open
Abstract
Cutaneous leishmaniasis (CL) is a chronic disease caused by species of the protozoan Leishmania and characterised by the presence of ulcerated skin lesions. Both parasite and host factors affect the clinical presentation of the disease. The development of skin ulcers in CL is associated with an inflammatory response mediated by cells that control parasite growth but also contribute to pathogenesis. CD8+ T cells contribute to deleterious inflammatory responses in patients with CL through cytotoxic mechanisms. In addition, natural killer cells also limit Leishmania infections by production of interferon-γ and cytotoxicity. In this review, we focus on studies of cytotoxicity in CL and its contribution to the pathogenesis of this disease.
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Affiliation(s)
- Taís M Campos
- Universidade Federal da Bahia, Serviço de Imunologia, Salvador, BA, Brasil.,Universidade Federal da Bahia, Faculdade de Medicina da Bahia, Programa de Pós-Graduação em Ciências da Saúde, Salvador, BA, Brasil
| | - Rúbia Costa
- Universidade Federal da Bahia, Serviço de Imunologia, Salvador, BA, Brasil.,Universidade Federal da Bahia, Faculdade de Medicina da Bahia, Programa de Pós-Graduação em Ciências da Saúde, Salvador, BA, Brasil
| | - Sara Passos
- Universidade Federal da Bahia, Serviço de Imunologia, Salvador, BA, Brasil.,Houston Methodist Research Institute, Department of Nanomedicine, Houston, TX, United States
| | - Lucas P Carvalho
- Universidade Federal da Bahia, Serviço de Imunologia, Salvador, BA, Brasil.,Universidade Federal da Bahia, Faculdade de Medicina da Bahia, Programa de Pós-Graduação em Ciências da Saúde, Salvador, BA, Brasil.,Instituto Nacional de Ciências e Tecnologia-Doenças Tropicais, Salvador, BA, Brasil.,Fundação Oswaldo Cruz-Fiocruz, Instituto Gonçalo Moniz, Laboratório Avançado de Saúde Pública, Salvador, BA, Brasil
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Inflammatory early events associated to the role of P2X7 receptor in acute murine toxoplasmosis. Immunobiology 2016; 222:676-683. [PMID: 28069296 DOI: 10.1016/j.imbio.2016.12.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 12/19/2016] [Accepted: 12/27/2016] [Indexed: 12/22/2022]
Abstract
Activation of the purinergic P2X7 receptor by extracellular ATP (eATP) potentiates proinflammatory responses during infections by intracellular pathogens. Extracellular ATP triggers an antimicrobial response in macrophages infected with Toxoplasma gondii in vitro, suggesting that purinergic signaling may stimulate host defense mechanisms against toxoplasmosis. Here, we provide in vivo evidence in support of this hypothesis, by showing that P2X7-/- mice are more susceptible than P2X7+/+ mice to acute infection by the RH strain of T. gondii, and that this phenomenon is associated with a deficient proinflammatory response. Four days post-infection, peritoneal washes from infected P2X7-/- mice had no or little increase in the levels of the proinflammatory cytokines IL-12, IL-1β, IFN-γ, and TNF-α, whose levels increased markedly in samples from infected P2X7+/+ mice. Infected P2X7-/- mice displayed an increase in organ weight and histological alterations in some of the 'shock organs' in toxoplasmosis - the liver, spleen and mesenteric lymph nodes. The liver of infected P2X7-/- mice had smaller granulomas, but increased parasite load/granuloma. Our results confirm that the P2X7 receptor is involved in containing T. gondii spread in vivo, by stimulating inflammation.
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Lee DH, Kim AR, Lee SH, Quan FS. Cross-protection induced by Toxoplasma gondii virus-like particle vaccine upon intraperitoneal route challenge. Acta Trop 2016; 164:77-83. [PMID: 27586039 DOI: 10.1016/j.actatropica.2016.08.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 07/29/2016] [Accepted: 08/16/2016] [Indexed: 12/17/2022]
Abstract
The inner membrane complex sub-compartment has a critical role in Toxoplasma gondii endodyogeny. In this study, we investigated the protection upon intraperitoneal route (IP) challenge induced by the virus-like particles (VLPs) vaccine containing Toxoplasma gondii IMC ISP (RH strain) (Type I). Intranasal immunization with the VLPs in mice elicited enhanced systemic and mucosal Toxoplasma gondii-specific IgG, IgG1, IgG2a and IgA antibody responses, and CD4+ and CD8+ responses. Immunized mice significantly reduced T. gondii cyst burden and size in brain, resulting in cross-protection upon T. gondii (ME49) (Type II) challenge infection. These results indicate that the IP route challenge infection induced by T. gondii IMC ISP VLPs might be a very good target for vaccination representing novel approach to reduce infection.
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Zhuo X, Sun H, Wang S, Guo X, Ding H, Yang Y, Shan Y, Du A. Ginseng Stem-and-Leaf Saponin (GSLS)-Enhanced Protective Immune Responses Induced by Toxoplasma gondii Heat Shocked Protein 70 (HSP70) Against Toxoplasmosis in Mice. J Parasitol 2016; 103:111-117. [PMID: 27828760 DOI: 10.1645/16-54] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Toxoplasma gondii is an obligate intracellular protozoan parasite and is able to infect birds and mammals including humans. In order to find effective antigen-adjuvant combinations that can boost the immunogenicity and protection of antigen vaccines against toxoplasmosis, we examined the protective efficacy in mice immunized with recombinant protein HSP70 when co-administered with ginseng stem-and-leaf saponins (GSLS) isolated from Panax ginseng . All immunized mice produced significantly high levels of specific antibodies against rTgHSP70, and splenocytes from mice presented strong proliferative immune responses. Vaccinated mice displayed a significantly increased percentage of CD4+ and CD8+ T cells, indicating a strong immune response was triggered. The cellular and humoral immune responses were enhanced, which could be reflected of the increased mRNA levels of IFN-γ and IL-4, respectively. Immunization with rTgHSP70 and GSLS prolonged survival time of the treated mice compared to the controls, which died within 6 days after challenge with the virulent T. gondii RH strain. Our data demonstrate that by addition with GSLS, rTgHSP70 induced a strong immune response and provided partial protection against T. gondii ; therefore GSLS could be used as a promising vaccine adjuvant against acute toxoplasmosis.
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Affiliation(s)
- Xunhui Zhuo
- Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Institute of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Hongchao Sun
- Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Institute of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Suhua Wang
- Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Institute of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xiaolu Guo
- Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Institute of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Haojie Ding
- Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Institute of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yi Yang
- Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Institute of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Ying Shan
- Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Institute of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Aifang Du
- Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Institute of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
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Hassan IA, Wang S, Xu L, Yan R, Song X, Li X. Immunoglobulin and cytokine changes induced following immunization with a DNA vaccine encoding Toxoplasma gondii selenium-dependent glutathione reductase protein. Exp Parasitol 2014; 146:1-10. [DOI: 10.1016/j.exppara.2014.08.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Revised: 08/07/2014] [Accepted: 08/11/2014] [Indexed: 01/30/2023]
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7
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Hassan IA, Wang S, Xu L, Yan R, Song X, Li X. DNA vaccination with a gene encoding Toxoplasma gondii Deoxyribose Phosphate Aldolase (TgDPA) induces partial protective immunity against lethal challenge in mice. Parasit Vectors 2014; 7:431. [PMID: 25201636 PMCID: PMC4164750 DOI: 10.1186/1756-3305-7-431] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 09/03/2014] [Indexed: 12/02/2022] Open
Abstract
Background Toxoplasma gondii is an obligate intracellular parasite that causes a pathological status known as toxoplasmosis, which has a huge impact on human and animal health. Currently, the main control strategy depends on the usage of drugs that target the acute stage of the infection, however, drawbacks were encountered while applying this method; therefore, development of an alternative effective method would be important progress. Deoxyribose Phosphate Aldolase (TgDPA) plays an important role supporting cell invasion and providing energy for the parasite. Methods TgDPA was expressed in Escherichia coli and the purified recombinant protein was used to immunize rats. The antibodies obtained were used to verify in vitro expression of TgDPA. The vector pVAX1 was utilized to formulate a DNA vaccine designated as pTgDPA, which was used to evaluate the immunological changes and the level of protection against challenge with the virulent RH strain of T. gondii. Results DNA vaccine, TgDPA revealed that it can induce a strong humoral as well as cellular mediated response in mice. These responses were a contribution of TH1, TH2 and TH17 type of responses. Following challenge, mice immunized with TgDPA showed longer survival rates than did those in control groups. Conclusions Further investigation regarding TgDPA is required to shed more light on its immunogenicity and its possible selection as a vaccine candidate.
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Affiliation(s)
| | | | | | | | | | - Xiangrui Li
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu 210095, People's Republic of China.
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8
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CTL induction by DNA vaccine with Toxoplasma gondii-HSP70 gene. Parasitol Int 2014; 63:408-16. [DOI: 10.1016/j.parint.2014.01.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 12/25/2013] [Accepted: 01/08/2014] [Indexed: 11/18/2022]
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9
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Bhadra R, Gigley JP, Khan IA. The CD8 T-cell road to immunotherapy of toxoplasmosis. Immunotherapy 2012; 3:789-801. [PMID: 21668315 DOI: 10.2217/imt.11.68] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Toxoplasma gondii infection induces a robust CD8 T-cell immunity that is critical for keeping chronic infection under control. In studies using animal models, it has been demonstrated that the absence of this response can compromise the host ability to keep chronic infection under check. Therapeutic agents that facilitate the induction and maintenance of CD8 T-cell response against the pathogen need to be developed. In the last decade, major strides in understanding the development of effector and memory response, particularly in viral and tumor models, have been made. However, factors involved in the generation of effector or memory response against T. gondii infection have not been extensively investigated. This information will be invaluable in designing immunotherapeutic regimens needed for combating this intracellular pathogen that poses a severe risk for pregnant women and immunocompromised individuals.
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Affiliation(s)
- Rajarshi Bhadra
- Department of Microbiology, Immunology & Tropical Medicine, George Washington University, Washington, DC 20037, USA
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10
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Subauste CS, Ajzenberg D, Kijlstra A. Review of the series "Disease of the year 2011: toxoplasmosis" pathophysiology of toxoplasmosis. Ocul Immunol Inflamm 2012; 19:297-306. [PMID: 21970661 DOI: 10.3109/09273948.2010.605198] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Toxoplasma gondii is a major cause of chronic parasitic infection in the world. This protozoan can cause retino-choroiditis in newborns and in adults, both immunocompetent and immunodeficient. This disease tends to be recurrent and can lead to severe visual impairment. The authors review current knowledge on the role of parasite genetics in influencing susceptibility to ocular toxoplasmosis and on the immuno-pathogenesis of this disease.
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Affiliation(s)
- Carlos S Subauste
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.
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11
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Yuan ZG, Zhang XX, Lin RQ, Petersen E, He S, Yu M, He XH, Zhou DH, He Y, Li HX, Liao M, Zhu XQ. Protective effect against toxoplasmosis in mice induced by DNA immunization with gene encoding Toxoplasma gondii ROP18. Vaccine 2011; 29:6614-9. [PMID: 21762755 DOI: 10.1016/j.vaccine.2011.06.110] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Revised: 05/17/2011] [Accepted: 06/28/2011] [Indexed: 12/01/2022]
Abstract
Toxoplasma gondii is an obligate intracellular protozoan parasite infecting mammals and birds including humans. Rhoptry protein 18 has been implicated as an important virulence factor. In this study, we constructed a DNA vaccine expressing rhoptry protein 18 (ROP18) of T. gondii, and evaluated the immune response and protective immunity in Kunming mice. The gene sequence encoding ROP18 was inserted into the eukaryotic expression vector pVAX I. Intramuscular immunization of mice with pVAX-ROP18 elicited specific humoral responses and stimulated lymphoproliferation (P<0.05). The cellular immune response was associated with the production of IFN-γ, indicating that a Th1 type response was elicited, which was confirmed by the production of large amounts of IgG2a (P<0.05). By the expression of the CD69, an activation marker of CD4+ and CD8+ T cells, we found that pVAX-ROP18 enhanced the activation of CD4+ and CD8+ T cells in lymphoid in mice. After lethal challenge, the mice immunized with the pVAX-ROP18 showed a significantly increased survival time (27.9±15.1 days) compared with control mice which died within 7 days of challenge (P<0.05). Our results show for the first time, that a ROP18 vaccine construct can enhance the T. gondii-specific CTL. Th1 responses and increased survival suggested that ROP18 is a promising vaccine candidate against infection with T. gondii.
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Affiliation(s)
- Zi-Guo Yuan
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu Province 730046, PR China
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12
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CD8 T Cells and Toxoplasma gondii: A New Paradigm. J Parasitol Res 2011; 2011:243796. [PMID: 21687650 PMCID: PMC3112509 DOI: 10.1155/2011/243796] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 03/10/2011] [Indexed: 01/09/2023] Open
Abstract
CD8 T cells are essential for control of Toxoplasma gondii infection. Once activated they undergo differentiation into short-lived effector and memory precursor effector cells. As effector cells, CD8 T cells exert immune pressure on the parasite via production of inflammatory cytokines and through their cytolytic activity. Once immune control has been established, the parasite encysts and develops into chronic infection regulated by the memory CD8 T-cell population. Several signals are needed for this process to be initiated and for development of fully differentiated memory CD8 T cells. With newly developed tools including CD8 T-cell tetramers and TCR transgenic mice, dissecting the biology behind T. gondii-specific CD8 T-cell responses can now be more effectively addressed. In this paper, we discuss what is known about the signals required for effective T. gondii-specific CD8 T-cell development, their differentiation, and effector function.
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Regulation of CD8+ T cell responses to infection with parasitic protozoa. Exp Parasitol 2010; 126:318-25. [PMID: 20493842 DOI: 10.1016/j.exppara.2010.05.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 04/05/2010] [Accepted: 05/15/2010] [Indexed: 11/24/2022]
Abstract
There are over 10,000 species of parasitic protozoa, a subset of which can cause considerable disease in humans. Here we examine in detail the complex immune response generated during infection with a subset of these parasites: Trypanosoma cruzi, Leishmania sp., Toxoplasma gondii, and Plasmodium sp. While these particular species perhaps represent the most studied parasites in terms of understanding how T cells function during infection, it is clear that the lessons learned from this body of work are also relevant to the other protozoa known to induce a CD8(+) T cell response. This review will highlight some of the key studies that established that CD8(+) T cells play a major role in protective immunity to protozoa, the factors that promote the generation as well as maintenance of the CD8(+) T cell response during these infections, and draw attention to some of the gaps in our knowledge. Moreover, the development of new tools, including MHC-Class I tetramer reagents and the use of TCR transgenic mice or genetically modified parasites, has provided a better appreciation of how parasite specific CD8(+) T cell responses are initiated and new insights into their phenotypic plasticity.
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Suzuki Y, Wang X, Jortner BS, Payne L, Ni Y, Michie SA, Xu B, Kudo T, Perkins S. Removal of Toxoplasma gondii cysts from the brain by perforin-mediated activity of CD8+ T cells. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 176:1607-13. [PMID: 20167872 DOI: 10.2353/ajpath.2010.090825] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Chronic infection with Toxoplasma gondii is one of the most common parasitic infections in humans. Formation of tissue cysts is the basis of persistence of the parasite in infected hosts, and this cyst stage has generally been regarded as untouchable. Here we provide the first evidence that the immune system can eliminate T. gondii cysts from the brains of infected hosts when immune T cells are transferred into infected immunodeficient animals that have already developed large numbers of cysts. This T cell-mediated immune process was associated with accumulation of microglia and macrophages around tissue cysts. CD8(+) immune T cells possess a potent activity to remove the cysts. The initiation of this process by CD8(+) T cells does not require their production of interferon-gamma, the major mediator to prevent proliferation of tachyzoites during acute infection, but does require perforin. These results suggest that CD8(+) T cells induce elimination of T. gondii cysts through their perforin-mediated cytotoxic activity. Our findings provide a new mechanism of the immune system to fight against chronic infection with T. gondii and suggest a possibility of developing a novel vaccine to eliminate cysts from patients with chronic infection and to prevent the establishment of chronic infection after a newly acquired infection.
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Affiliation(s)
- Yasuhiro Suzuki
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40536, USA.
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Jongert E, Lemiere A, Van Ginderachter J, De Craeye S, Huygen K, D'Souza S. Functional characterization of in vivo effector CD4(+) and CD8(+) T cell responses in acute Toxoplasmosis: an interplay of IFN-gamma and cytolytic T cells. Vaccine 2010; 28:2556-64. [PMID: 20117266 DOI: 10.1016/j.vaccine.2010.01.031] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2009] [Revised: 12/26/2009] [Accepted: 01/16/2010] [Indexed: 01/05/2023]
Abstract
Development of prophylactic vaccines against Toxoplasma gondii is based on the observation that latently infected subjects are protected against secondary infection during pregnancy. Cocktail DNA vaccines have been shown to provide high resistance to parasite challenge, and latently infected mice are protected against acute disease. In order to characterize the associated Th1 cellular immune responses in vivo, we used H2-K(k) bone marrow macrophage cell lines constitutively expressing T. gondii GRA1, GRA7 or ROP2 antigens, for the in vivo characterization of antigen-specific T cells in an antigenic challenge model, and as target cells in an in vivo CTL assay. In latently infected C3H/HeN mice, CD4(+) and CD8(+) T cells were recruited to the peritoneal cavity after i.p. challenge with these syngeneic cell lines. GRA1 and GRA7-specific T cells from infected mice were IFN-gamma(+) FasL(-) CD107(-). No IFN-gamma or lytic markers were observed against ROP2. In cocktail DNA vaccinated C3H/HeN mice, the response was restricted to GRA1-specific CD8(+) IFN-gamma(-) FasL(-) CD107(+) T cells. Target cells expressing GRA1 and GRA7, but not ROP2, were efficiently killed in an in vivo CTL assay in latently infected mice, while in DNA vaccinated mice only lysis of GRA1 expressing target cells was observed. Both forms of immunization, DNA vaccination and latent infection, completely protected mice against acute Toxoplasmosis. The results obtained in this work suggest that distinct in vivo cytolytic effector mechanisms are at work in DNA vaccinated and latently infected mice, but both converge to protect against acute toxoplasmosis.
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Affiliation(s)
- Erik Jongert
- Laboratory for Toxoplasmosis, Pasteur Institute of Brussels, Brussels, Belgium.
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16
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Expansion of CD8+CD57+ T Cells in an Immunocompetent Patient with Acute Toxoplasmosis. Adv Hematol 2009; 2009:173439. [PMID: 19946421 PMCID: PMC2778835 DOI: 10.1155/2009/173439] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2008] [Revised: 05/12/2009] [Accepted: 06/16/2009] [Indexed: 11/27/2022] Open
Abstract
CD57+ T cells increase in several viral infections like cytomegalovirus, herpesvirus, parvovirus, HIV and hepatitis C virus and are associated with several clinical conditions related to immune dysfunction and ageing. We report for the first time an expansion of CD8+ CD57+ T cells in a young patient with an acute infection with Toxoplasma gondii. Our report supports the concept that CD8+ CD57+ T cells could be important in the control of chronic phase of intracellular microorganisms and that the high numbers of these cells may reflect the continuing survey of the immune system, searching for parasite proliferation in the tissues.
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Jongert E, Melkebeek V, De Craeye S, Dewit J, Verhelst D, Cox E. An enhanced GRA1–GRA7 cocktail DNA vaccine primes anti-Toxoplasma immune responses in pigs. Vaccine 2008; 26:1025-31. [DOI: 10.1016/j.vaccine.2007.11.058] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 11/12/2007] [Accepted: 11/21/2007] [Indexed: 10/22/2022]
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18
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Jongert E, de Craeye S, Dewit J, Huygen K. GRA7 provides protective immunity in cocktail DNA vaccines against Toxoplasma gondii. Parasite Immunol 2007; 29:445-53. [PMID: 17727568 DOI: 10.1111/j.1365-3024.2007.00961.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In a previous study, single-gene vaccination with GRA1, GRA7 or ROP2 was shown to elicit partial protection against Toxoplasma gondii. In this study, the contribution of each antigen in the evoked humoral and cellular immune responses was evaluated after vaccination with plasmid mixtures containing GRA1, GRA7 and ROP2. Cocktail DNA vaccinated mice developed high antibody titers against the antigens from two-gene DNA vaccine cocktails, but lower titres when immunized with the three-gene cocktail. High numbers of IFN-gamma secreting splenocytes were generated predominantly against GRA7. Brain cyst burden was reduced by 81% in mice vaccinated with the three-gene mixture and they were completely protected against acute toxoplasmosis. Similar high levels of brain cyst reductions were obtained after vaccination with cocktails composed of GRA1 and GRA7 (89% reduction), or GRA7 and ROP2 (79% reduction), but not with the cocktail composed of GRA1 and ROP2. In low dose single-gene vaccinations, IFN-gamma and strong protection could only be elicited by GRA7. Hence, the presence of GRA7 in the DNA vaccine formulation was important for optimal protection and this was correlated with GRA7-specific IFN-gamma production. We propose GRA7 as a main component in cocktail DNA vaccines for vaccination against T. gondii.
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Affiliation(s)
- E Jongert
- Toxoplasma Research Unit, WIV-Pasteur Institute of Brussels (Federal Service of Public Health), Brussels, Belgium.
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Innes EA, Vermeulen AN. Vaccination as a control strategy against the coccidial parasitesEimeria,ToxoplasmaandNeospora. Parasitology 2007; 133 Suppl:S145-68. [PMID: 17274844 DOI: 10.1017/s0031182006001855] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The protozoan parasitesEimeriaspp.Toxoplasma gondiiandNeospora caninumare significant causes of disease in livestock worldwide andT. gondiiis also an important human pathogen. Drugs have been used with varying success to help control aspects of these diseases and commercial vaccines are available for all three groups of parasites. However, there are issues with increasing development of resistance to many of the anti-coccidial drugs used to help control avian eimeriosis and public concerns about the use of drugs in food animals. In addition there are no drugs available that can act against the tissue cyst stage of eitherT. gondiiorN. caninumand thus cure animals or people of infection. All three groups of parasites multiply within the cells of their host species and therefore cell mediated immune mechanisms are thought to be an important component of host protective immunity. Successful vaccination strategies for bothEimeriaandToxoplasmahave relied on using a live vaccination approach using attenuated parasites which allows correct processing and presentation of antigen to the host immune system to stimulate appropriate cell mediated immune responses. However, live vaccines can have problems with safety, short shelf-life and large-scale production; therefore there is continued interest in devising new vaccines using defined recombinant antigens. The major challenges in devising novel vaccines are to select relevant antigens and then present them to the immune system in an appropriate manner to enable the induction of protective immune responses. With all three groups of parasites, vaccine preparations comprising antigens from the different life cycle stages may also be advantageous. In the case ofEimeriaparasites there are also problems with strain-specific immunity therefore a cocktail of antigens from different parasite strains may be required. Improving our knowledge of the different parasite transmission routes, host-parasite relationships, disease pathogenesis and determining the various roles of the host immune response being at times host-protective, parasite protective and in causing immunopathology will help to tailor a vaccination strategy against a particular disease target. This paper discusses current vaccination strategies to help combat infections withEimeria,ToxoplasmaandNeosporaand recent research looking towards developing new vaccine targets and approaches.
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Affiliation(s)
- E A Innes
- Moredun Research Institute, Pentlands Science Park, Edinburgh EH26 OPZ, UK.
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20
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Prigione I, Chiesa S, Taverna P, Ceccarelli R, Frulio R, Morandi F, Bocca P, Cesbron-Delauw MF, Pistoia V. T cell mediated immune responses to Toxoplasma gondii in pregnant women with primary toxoplasmosis. Microbes Infect 2006; 8:552-60. [PMID: 16324868 DOI: 10.1016/j.micinf.2005.08.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Revised: 07/27/2005] [Accepted: 08/19/2005] [Indexed: 10/25/2022]
Abstract
The aim of this study was to investigate T cell immunity to Toxoplasma gondii (Tg) in pregnant women with primary toxoplasmosis. This issue has never been addressed before in humans and available information derives from murine models. Peripheral blood mononuclear cells (PBMC) from pregnant women with primary Tg infection were stimulated with Tg tachyzoites, excretory-secretory antigens (ESA) or recombinant surface antigen-1 (rSAG-1), and tested for proliferation, immunophenotype, cytokine production and antigen specific cytotoxic activity. Pregnant women with primary toxoplasmosis displayed a significant decrease of the CD4/CD8 T cell ratio and a significant increase of circulating T cell receptor (TCR) gammadelta+ cells as compared to their uninfected counterparts. T cells from Tg infected pregnant women proliferated to Tg tachyzoites, ESA or rSAG-1. Most tachyzoite and ESA specific T cell blasts were CD4+, whereas SAG-1 specific blasts were CD4+ and CD8+. ESA and tachyzoite specific T cell blasts displayed a Th1 or Th0 cytokine profile with overexpression of IFN-gamma. This pattern was unchanged upon in vitro exposure of T cells to progesterone, tested at a concentration close to that reached in vivo at the maternal-fetal interface. Finally, tachyzoite or ESA specific T cell blasts lysed, through a granule exocytosis dependent mechanism, autologous lymphoblastoid cell lines presenting Tg antigens. In conclusion, pregnant women with primary toxoplasmosis mounted in vitro Tg-specific Th1/Th0 responses whose impact on neonatal infection warrants further investigation.
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Affiliation(s)
- Ignazia Prigione
- Laboratory of Oncology, Department of Experimental and Laboratory Medicine, G. Gaslini Scientific Institute, Largo G. Gaslini 5, 16148 Genoa, Italy.
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21
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Lüder CGK, Gross U. Apoptosis and its modulation during infection with Toxoplasma gondii: molecular mechanisms and role in pathogenesis. Curr Top Microbiol Immunol 2005; 289:219-37. [PMID: 15791958 DOI: 10.1007/3-540-27320-4_10] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Infection with the obligate intracellular protozoan Toxoplasma gondii leads to lifelong persistence of the parasite in its mammalian hosts including humans. Apoptosis plays crucial roles in the interaction between the host and the parasite. This includes innate and adaptive defense mechanisms to restrict intracellular parasite replication as well as regulatory functions to modulate the host's immune response. Not surprisingly, however, T. gondii also extensively modifies apoptosis of its own host cell or of uninfected bystander cells. After infection, apoptosis is triggered in T lymphocytes and other leukocytes, thereby leading to suppressed immune responses to the parasite. T cell apoptosis may be largely mediated by Fas engagement but also occurs independently of Fas under certain conditions. Depending on the magnitude of T cell apoptosis, it is either associated with unrestricted parasite replication and severe pathology or facilitates a stable parasite-host-interaction. However, T. gondii has also evolved strategies to inhibit host cell apoptosis. Apoptosis is blocked by indirect mechanisms in uninfected bystander cells, thereby modulating the inflammatory response to the parasite. In contrast, inhibition of apoptosis in infected host cells by direct interference with apoptosis-signaling cascades is thought to facilitate the intracellular development of T. gondii. Blockade of apoptosis by intracellular parasites may be achieved by different means including interference with the caspase cascade, increased expression of antiapoptotic molecules by infected host cells, and a decreased activity of the poly(ADP-ribose) polymerase. The intriguing dual activity of T. gondii to both promote and inhibit apoptosis requires a tight regulation to promote a stable parasite host-interaction and establishment of persistent toxoplasmosis.
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Affiliation(s)
- C G K Lüder
- Institute of Medical Microbiology, Georg-August-University, Kreuzbergring 57, 37075 Göttingen, Germany.
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22
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Abstract
Toxoplasma gondii is a protozoan parasite that infects up to a third of the world's population. Infection is mainly acquired by ingestion of food or water that is contaminated with oocysts shed by cats or by eating undercooked or raw meat containing tissue cysts. Primary infection is usually subclinical but in some patients cervical lymphadenopathy or ocular disease can be present. Infection acquired during pregnancy may cause severe damage to the fetus. In immunocompromised patients, reactivation of latent disease can cause life-threatening encephalitis. Diagnosis of toxoplasmosis can be established by direct detection of the parasite or by serological techniques. The most commonly used therapeutic regimen, and probably the most effective, is the combination of pyrimethamine with sulfadiazine and folinic acid. This Seminar provides an overview and update on management of patients with acute infection, pregnant women who acquire infection during gestation, fetuses or infants who are congenitally infected, those with ocular disease, and immunocompromised individuals. Controversy about the effectiveness of primary and secondary prevention in pregnant women is discussed. Important topics of current and future research are presented.
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Affiliation(s)
- J G Montoya
- Department of Medicine and Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA, USA
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23
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Mun HS, Aosai F, Chen M, Piao LX, Norose K, Iwakura Y, Yano A. Pathogenicity of Toxoplasma gondii through B-2 cell-mediated downregulation of host defense responses. Microbiol Immunol 2003; 47:533-42. [PMID: 12953847 DOI: 10.1111/j.1348-0421.2003.tb03415.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
IFN-gamma is the primary mediator of anti-parasite effector mechanisms against Toxoplasma gondii. After intraperitoneal infection with the Fukaya strain of T. gondii, unirradiated IFN-gamma knock-out (GKO) mice transferred with wild type (WT) CD8+ effector T cells from infected mice failed to induce the production of IFN-gamma and died, whereas irradiated (IR) GKO mice transferred with WT CD8+ T cells induced IFN-y production and survived more than 6 months. IR GKO mice transferred with WT CD8+ T cells together with GKO B-2 cells died 8 days after infection, whereas those transferred with WT CD8+ T cells together with B-la or T cells survived. B-2 cells of infected GKO mice activated CD11b+ cells for IL-4 production, and down-regulated NO release, STAT1 phosphorylation, and interferon regulatory factor-1 expression in the peritoneal exudates cells of IR GKO mice transferred with WT CD8+ T cells together with GKO B-2 cells after infection. Thus, B-2 cells in T. gondii-infected mice act as suppressor cells in the host defense of infected mice.
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Affiliation(s)
- Hye-Seong Mun
- Department of Infection and Host Defense, Graduate School of Medicine, Chiba University, Chiba, Chiba 260-8670, Japan
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24
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Abstract
The present review article deals with the pathogenesis of toxoplasmosis. The article briefly highlights some important aspects such as different strains, mode of infection and clinical characteristics, entry into host cell, immune response, host parasite interaction, tissue cyst formation and disease recurrence.
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Affiliation(s)
- G M Bhopale
- Parasitology and Immunodiagnostic Laboratory, Research and Development Division, Hindustan Antibiotics Ltd, Pimpri, 411018, Pune, India
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25
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Staska LM, McGuire TC, Davies CJ, Lewin HA, Baszler TV. Neospora caninum-infected cattle develop parasite-specific CD4+ cytotoxic T lymphocytes. Infect Immun 2003; 71:3272-9. [PMID: 12761108 PMCID: PMC155777 DOI: 10.1128/iai.71.6.3272-3279.2003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cattle infected with Neospora caninum readily experience transplacental parasite transmission, presumably after maternal parasitemia, leading to abortion or birth of congenitally infected calves. Cytotoxic T lymphocytes (CTL) are important mediators of protective immunity against Toxoplasma gondii, an intracellular apicomplexan protozoan closely related to N. caninum. In this study, N. caninum-specific CTL expanded from peripheral blood mononuclear cells of two major histocompatibility complex-mismatched, experimentally infected cattle were identified by using a (51)Cr release cytotoxicity assay. Enrichment and blocking of CD4(+)- and CD8(+)-T-lymphocyte effector subsets indicated that CD4(+) CTL killed N. caninum-infected, autologous target cells and that killing was mediated through a perforin/granzyme pathway. Detection and characterization of CTL responses to N. caninum in the natural, outbred, bovine host will facilitate identification of immunogens and design of immunization strategies to induce parasite-specific CTL against transplacental N. caninum transmission in cattle.
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Affiliation(s)
- Lauren M Staska
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman 99164, USA
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26
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Scorza T, D'Souza S, Laloup M, Dewit J, De Braekeleer J, Verschueren H, Vercammen M, Huygen K, Jongert E. A GRA1 DNA vaccine primes cytolytic CD8(+) T cells to control acute Toxoplasma gondii infection. Infect Immun 2003; 71:309-16. [PMID: 12496180 PMCID: PMC143232 DOI: 10.1128/iai.71.1.309-316.2003] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protective immunity against Toxoplasma gondii is known to be mediated mainly by T lymphocytes and gamma interferon (IFN-gamma). The contribution of CD4(+) and CD8(+) T-lymphocyte subsets to protective immune responses against T. gondii infection, triggered by a GRA1 (p24) DNA vaccine, was assessed in this study. In vitro T-cell depletion experiments indicated that both CD4(+) and CD8(+) T-cell subsets produced IFN-gamma upon restimulation with a T. gondii lysate. In addition, the GRA1 DNA vaccine elicited CD8(+) T cells that were shown to have cytolytic activity against parasite-infected target cells and a GRA1-transfected cell line. C3H mice immunized with the GRA1 DNA vaccine showed 75 to 100% protection, while 0 to 25% of the mice immunized with the empty control vector survived challenge with T. gondii cysts. In vivo T-cell depletion experiments indicated that CD8(+) T cells were essential for the survival of GRA1-vaccinated C3H mice during the acute phase of T. gondii infection, while depletion of CD4(+) T cells led to an increase in brain cyst burden during the chronic phase of infection.
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Affiliation(s)
- T Scorza
- Department of Toxoplasmosis, Pasteur Institute of Brussels, 1180 Brussels, Belgium
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27
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Yano A, Mun HS, Chin M, Norose K, Hata K, Kobayashi M, Aosai F, Iwakura Y. Roles of IFN-gamma on stage conversion of an obligate intracellular protozoan parasite, Toxoplasma gondii. Int Rev Immunol 2002; 21:405-21. [PMID: 12486821 DOI: 10.1080/08830180213279] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
IFN-gamma downregulates the stage conversion of Toxoplasma gondii (T. gondii), from bradyzoites to tachyzoites, and the expression of heat shock protein 70 (HSP70) of T. gondii (T.g.HSP70) by tachyzoites. T.g.HSP70 has been shown to downregulate NO release from macrophages and also to induce auto-HSP70 antibody formation and IL-10 secretion by VH11-JH1 B-1 cells, resulting in the suppression of host defense responses to T. gondii infection. A novel category of virulent tachyzoite stage of T. gondii expressing T.g.HSP70 (virulent tachyzoite), which indirectly manifests its pathogenicity by downregulating host defense responses, has been proposed.
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Affiliation(s)
- Akihiko Yano
- Department of Infection and Host Defense, Graduate School of Medicine, Chiba University, Chiba, Japan.
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28
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Fatoohi AF, Cozon GJN, Greenland T, Ferrandiz J, Bienvenu J, Picot S, Peyron F. Cellular immune responses to recombinant antigens in pregnant women chronically infected with Toxoplasma gondii. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2002; 9:704-7. [PMID: 11986281 PMCID: PMC120002 DOI: 10.1128/cdli.9.3.704-707.2002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The parasite Toxoplasma gondii can infect most mammals and birds, sometimes causing severe pathology. Primary infection during pregnancy can result in abortion or fetal defects. Host immunity, particularly cellular immunity towards antigenic peptides, can control infection, but an efficient vaccine is not yet available. We have evaluated T-cell responses to a crude soluble toxoplasma antigen (ST-Ag) and to five recombinant peptide antigens of cells in whole-blood cultures from 22 pregnant women with preexisting infections and from 7 pregnant negative controls. Cells from all infected patients but from none of the controls responded specifically to ST-Ag by expressing surface CD25 on culture. Responses to the recombinant antigens showed considerable variation between individuals. rGRA1 elicited a response in 16 of the 22 samples (73%), rSAG1 in 13, rGRA7 in 9, rGRA6-CT in 4, and rGRA6-NT in only 1. Most responding cells were CD4(+). Cells from infected subjects cultured with ST-Ag all released high levels of gamma interferon (IFN-gamma) into the culture supernatant (4,343 +/- 2,536 pg/ml). Cells from 12 patients released IFN-gamma after culture with rGRA1 (130 +/- 98 pg/ml), those from 10 patients released it after culture with rSAG1 (183 +/- 128 pg/ml), and those from 4 patients released it after culture with rGRA7 (324 +/- 374 pg/ml). Intensity of IFN-gamma production in response to the latter two recombinant antigens correlated with responses to ST-Ag (r = 0.61 and 0.53, respectively; P < 0.01). Interleukin-4 was always absent from supernatants of cells stimulated with toxoplasma antigens. The heterogeneity of human responses to individual recombinant toxoplasma antigens should be considered in the design of potential vaccines.
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Affiliation(s)
- A F Fatoohi
- E. A. 3087 Parasitologie, Faculté de Médecine Lyon Nord, Lyon, France
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29
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Abstract
Interferon (IFN)-gamma-dependent, cell-mediated immunity plays the major role in resistance against development of toxoplasmic encephalitis (TE). Humoral immunity also participates in controlling Toxoplasma gondii in the brain. Resistance is operative under collaboration among T and B cells, IFN-gamma-producing non-T cells, microglia, astrocytes, and dendritic cells. A number of cytokines, including IFN-gamma, mediate interactions between these cells and activation of effector cells that prevent intracellular replication of the parasite. The L(d) gene confers resistance against development of TE in mice. In humans, the HLA-DQ1 and -DQ3 genes are involved in regulating the resistance and susceptibility. Since these genes are a part of the major histocompatibility complex, which regulates the immune responses, the regulation of the responses by these genes appears to be important for determining host resistance to this disease. Strains of T. gondii also affect development of TE. Genotypes of the parasite may be an important factor for determining development of TE.
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Affiliation(s)
- Yasuhiro Suzuki
- Department of Immunology and Infectious Diseases, Research Institute, Palo Alto Medical Foundation, California, USA.
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30
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Lüder CG, Seeber F. Toxoplasma gondii and MHC-restricted antigen presentation: on degradation, transport and modulation. Int J Parasitol 2001; 31:1355-69. [PMID: 11566303 DOI: 10.1016/s0020-7519(01)00260-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Resistance against Toxoplasma gondii, an obligate intracellular protozoan parasite surrounded by a parasitophorous vacuolar membrane, is mediated by the cellular arm of the immune system, namely CD8+ and CD4+ T cells. Thus, priming and activation of these cells by presentation of antigenic peptides in the context of major histocompatibility complex class I and class II molecules have to take place. This is despite the fact that the vacuolar membrane avoids fusion with the endocytic compartment and acts like a molecular sieve, restricting passive diffusion of larger molecules. This raises several cell biological and immunological questions which will be discussed in this review in the context of our current knowledge about major histocompatibility complex-restricted antigen presentation in other systems: (1) By which pathways are parasite-derived antigens presented to T cells? (2) Has the parasite evolved mechanisms to interfere with major histocompatibility complex-restricted antigen presentation in order to avoid immune recognition? (3) To what extent and by which mechanism is antigenic material, originating from the parasite, able to pass through the vacuolar membrane into the cytosol of the infected cell and is it then accessible to the antigen presentation machinery of the infected cell? (4) What are the actual antigen-presenting cells which prime specific T cells in lymphoid organs? An understanding of these mechanisms will not only provide new insights into the pathogenesis of Toxoplasma gondii and possibly other intravacuolar parasites, but will also improve vaccination strategies.
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Affiliation(s)
- C G Lüder
- Department of Bacteriology, Georg-August-Universität Göttingen, Kreuzbergring 57, D-37075 Göttingen, Germany.
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31
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Prigione I, Facchetti P, Lecordier L, Deslée D, Chiesa S, Cesbron-Delauw MF, Pistoia V. T cell clones raised from chronically infected healthy humans by stimulation with Toxoplasma gondii excretory-secretory antigens cross-react with live tachyzoites: characterization of the fine antigenic specificity of the clones and implications for vaccine development. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:3741-8. [PMID: 10725733 DOI: 10.4049/jimmunol.164.7.3741] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Excreted-secreted Ags (ESA) of Toxoplasma gondii (Tg) play an important role in the stimulation of the host immune system in both acute and chronic infections. To identify the parasite Ag(s) involved in the maintenance of T cell-mediated long term immunity, 40 ESA-specific T cell clones were derived from three chronically infected healthy subjects. All the clones were CD4+ and recognized both ESA and live tachyzoites in a HLA-DR-restricted manner. Conversely, CD4+ tachyzoite-specific T cell clones from the same subjects proliferated in response to ESA, pointing to shared immunodominant Ags between ESA and Tg tachyzoites. By T cell blot analysis using SDS-PAGE-fractionated parasite extracts, the following patterns of reactivity were detected. Of 25 clones, 6 recognized Tg fractions in the 24- to 28-kDa range and proliferated to purified GRA2, 5 reacted with Tg fractions in the 30- to 33-kDa range; and 4 of them proved to be specific for rSAg1. Although surface Ag (SAg1) is not a member of ESA, small amounts of this protein were present in ESA preparation by Western blot. Of 25 clones, 8 responded to Tg fractions in the 50- to 60-kDa range but not to the 55-kDa recombinant rhoptries-2 parasite Ag, and 6 did not react with any Tg fraction but proliferated in response to either ESA or total parasite extracts. In conclusion, CD4+ T cells specific for either ESA (GRA2) or SAg1 may be involved in the maintenance of long term immunity to Tg in healthy chronically infected individuals.
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MESH Headings
- Animals
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Antigens, Protozoan/isolation & purification
- Cell Communication/immunology
- Chemical Fractionation
- Chronic Disease
- Clone Cells/immunology
- Clone Cells/metabolism
- Clone Cells/parasitology
- Epitopes, T-Lymphocyte/chemistry
- Epitopes, T-Lymphocyte/genetics
- Epitopes, T-Lymphocyte/immunology
- Humans
- Interferon-gamma/biosynthesis
- Interleukin-4/biosynthesis
- Lymphocyte Activation/immunology
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Protozoan Proteins/isolation & purification
- Protozoan Proteins/metabolism
- Protozoan Vaccines/chemical synthesis
- Protozoan Vaccines/genetics
- Protozoan Vaccines/immunology
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- T-Lymphocytes/parasitology
- Toxoplasma/growth & development
- Toxoplasma/immunology
- Toxoplasmosis/immunology
- Toxoplasmosis/parasitology
- Vaccines, Attenuated/chemical synthesis
- Vaccines, Attenuated/genetics
- Vaccines, Attenuated/immunology
- Vaccines, Synthetic/immunology
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Affiliation(s)
- I Prigione
- Laboratorio di Oncologia, Istituto G. Gaslini, Genoa, Italy
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32
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Nielsen HV, Lauemøller SL, Christiansen L, Buus S, Fomsgaard A, Petersen E. Complete protection against lethal Toxoplasma gondii infection in mice immunized with a plasmid encoding the SAG1 gene. Infect Immun 1999; 67:6358-63. [PMID: 10569750 PMCID: PMC97042 DOI: 10.1128/iai.67.12.6358-6363.1999] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Infection with the protozoan parasite Toxoplasma gondii is transmitted to humans from infected animals by tissue cysts and oocysts excreted by cats. Immunization with inactivated parasites or recombinant proteins has at best shown partial protection. We constructed a plasmid expressing the SAG1 surface antigen of T. gondii, p1tPASAG1, and showed that animals immunized with the plasmid produce anti-SAG1 antibodies which recognize the native SAG1. Mice immunized with p1tPASAG1 showed 80 to 100% protection against challenge with the non-cyst-producing, virulent RH isolate, compared to an 80% mortality in mice immunized with empty plasmid, which is the greatest efficacy of any vaccine against T. gondii produced so far. The SAG1 molecule was analyzed for potential cytotoxic T-lymphocyte (CTL) epitopes, and four peptides with the best fit were synthesized. The ability of the peptides to stimulate gamma interferon production by CD8(+) T cells from p1tPASAG1-immunized mice was tested in an ELISPOT assay, and one new CTL epitope was identified. Adoptive transfer of CD8(+) T cells from p1tPASAG1-immunized to naïve mice showed partial protection. In conclusion, DNA vaccination with p1tPASAG1 gave effective protection in mice against T. gondii infection and the protection could be adoptively transferred by purified CD8(+) T cells.
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Affiliation(s)
- H V Nielsen
- Department of Mycobacteria and Parasitology, Statens Serum Institut, University of Copenhagen, Copenhagen, Denmark.
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33
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Khan IA, Casciotti L. IL-15 Prolongs the Duration of CD8+ T Cell-Mediated Immunity in Mice Infected with a Vaccine Strain of Toxoplasma gondii. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.8.4503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Immunization of mice with a vaccine (ts-4) strain of Toxoplasma gondii is known to induce complete protection against subsequent lethal infection. Ts-4-mediated protection has been reported to be primarily dependent on IFN-γ-producing CD8+ T cells. However, duration of CD8+ T cell-mediated immunity in the ts-4-vaccinated animals is not known. In the present study, the kinetics of the CD8+ T cell response in mice immunized with the ts-4 strain of T. gondii was evaluated. Optimal CD8+ T cell immunity persisted at least 6 mo after vaccination, and mice at this time point continued to overcome lethal challenge with a more virulent strain. However, at 9 mo postimmunization, CD8+ T cell immunity was severely diminished and the mice succumbed to Toxoplasma challenge. Pretreatment of animals, vaccinated 9 mo earlier, with rIL-15 prevented the mortality induced by Toxoplasma challenge. The protective effect of IL-15 treatment was due to a rise in the frequency of Ag-specific CD8+ T cells. CD8+ T cells from IL-15-administered animals showed increased proliferation and IFN-γ production in response to antigenic restimulation. These findings suggest that rIL-15 can reverse the decline in the long-term CD8+ T cell immune response in mice immunized with vaccine strain of T. gondii.
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Affiliation(s)
- Imtiaz A. Khan
- Department of Medicine, Dartmouth Medical School, Lebanon, NH 03756
| | - Lori Casciotti
- Department of Medicine, Dartmouth Medical School, Lebanon, NH 03756
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34
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Jungersen G, Jensen L, Riber U, Heegaard PM, Petersen E, Poulsen JS, Bille-Hansen V, Lind P. Pathogenicity of selected Toxoplasma gondii isolates in young pigs. Int J Parasitol 1999; 29:1307-19. [PMID: 10576580 DOI: 10.1016/s0020-7519(99)00078-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The pathogenicity in 7-week-old pigs to five different Toxoplasma gondii strains of various host species origin was compared after i.v. inoculation of 10(4) tachyzoites. Additionally, one group of pigs was inoculated i.v. with 10(6) tachyzoites of the reference strain, SSI 119. In response to the infection a significant effect of T. gondii tachyzoite inoculation dose as well as differences among strains could be observed in several parameters. The 10(6)-dose inoculated pigs showed variable degrees of clinical illness and recurrent episodes of fever 4-17 days p.i., while pigs of four of the 10(4) tachyzoite inoculated groups experienced a short-lived rise in body temperature from day 6-8 p.i. without any apparent illness or inappetence. Control pigs and pigs infected with the least pathogenic strain had normal body temperature throughout the experiment. In all inoculated pigs, T. gondii-specific IgM and IgG antibodies appeared from day 8-10 and 10-17 p.i., respectively. Serum levels of alkaline phosphatase and the acute phase protein haptoglobin were decreased or increased, respectively, in response to the infection. Differential leukocyte count on peripheral blood revealed a significant lymphocytopenia on day 6 p.i. equal to both CD4+ and CD8+ T-cells, but shifting towards a reduced ratio of CD4+/CD8+ T-cells from day 8-14 p.i. In the 10(6)-dose inoculated pigs a considerable increase in zymosan induced and spontaneous oxidative burst capacity of peripheral blood leukocytes was observed from 6 days p.i. compared with control pigs. Oxidative burst capacity was not examined for other pigs. In conclusion, several useful parameters to identify differences in T. gondii pathogenicity other than mortality were identified. Furthermore, even at low doses, significant differences between recently collected Danish T. gondii field isolates were demonstrated after i.v. inoculation in young pigs.
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Affiliation(s)
- G Jungersen
- Danish Veterinary Laboratory, Copenhagen, Denmark.
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35
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Shibahara T, Kokuho T, Eto M, Haritani M, Hamaoka T, Shimura K, Nakamura K, Yokomizo Y, Yamane I. Pathological and immunological findings of athymic nude and congenic wild type BALB/c mice experimentally infected with Neospora caninum. Vet Pathol 1999; 36:321-7. [PMID: 10421099 DOI: 10.1354/vp.36-4-321] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Neospora is a cyst-forming coccidian parasite that causes abortions and neuromuscular disorders in a wide variety of mammals. Japanese bovine isolate JPA1 was inoculated intraperitoneally into BALB/c nu/ nu (athymic nude) and BALB/c (congenic wild type) female mice to examine the distribution of parasites and resistance mechanisms to Neospora infection. All the athymic nude mice died within 28 days after intraperitoneal injection of 2 x 10(5) JPA1 tachyzoites, whereas all the congenic wild type mice survived without exhibiting any clinical signs. Tachyzoites were identified in the uterus and pancreas and later spread to many other organs. Most tachyzoites identified in the necrotic foci were localized in the epithelium of the venules and capillaries. Nude mice developed high level of serum interferon-gamma and interleukin-6 as infection proceeded. Inflammatory response to Neospora infection might be mediated by Th1-type dependent cellular immunity.
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Affiliation(s)
- T Shibahara
- National Institute of Animal Health, Ministry of Agriculture, Forestry and Fisheries, Tsukuba-shi, Ibaraki, Japan.
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36
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Yamashita K, Yui K, Ueda M, Yano A. Cytotoxic T-lymphocyte-mediated lysis of Toxoplasma gondii-infected target cells does not lead to death of intracellular parasites. Infect Immun 1998; 66:4651-5. [PMID: 9746561 PMCID: PMC108572 DOI: 10.1128/iai.66.10.4651-4655.1998] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD8(+) T cells play a crucial role in the control of infection with intracellular microbes. The mechanisms underlying the CD8(+) T-cell-mediated clearance of the intracellular pathogen Toxoplasma gondii are, however, not completely understood. The effect of CD8(+) cytotoxic T-lymphocyte (CTL)-mediated lysis of host cells on the viability of intracellular T. gondii was investigated. Quantitative competitive PCR of the gene encoding T. gondii major surface antigen (SAG-1) was combined with treatment of the parasites with DNase, which removed the DNA template of nonviable parasites. The induction by CD8(+) CTLs of apoptosis in cells infected with T. gondii did not result in the reduction of live parasites, indicating that intracellular T. gondii remains alive after lysis of host cells by CTLs.
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Affiliation(s)
- K Yamashita
- Department of Medical Zoology, Nagasaki University School of Medicine, 1-12-4 Sakamoto, Nagasaki, Nagasaki 852-8523, Japan
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37
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Denkers EY, Gazzinelli RT. Regulation and function of T-cell-mediated immunity during Toxoplasma gondii infection. Clin Microbiol Rev 1998; 11:569-88. [PMID: 9767056 PMCID: PMC88897 DOI: 10.1128/cmr.11.4.569] [Citation(s) in RCA: 529] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The intracellular protozoan Toxoplasma gondii is a widespread opportunistic parasite of humans and animals. Normally, T. gondii establishes itself within brain and skeletal muscle tissues, persisting for the life of the host. Initiating and sustaining strong T-cell-mediated immunity is crucial in preventing the emergence of T. gondii as a serious pathogen. The parasite induces high levels of gamma interferon (IFN-gamma) during initial infection as a result of early T-cell as well as natural killer (NK) cell activation. Induction of interleukin-12 by macrophages is a major mechanism driving early IFN-gamma synthesis. The latter cytokine, in addition to promoting the differentiation of Th1 effectors, is important in macrophage activation and acquisition of microbicidal functions, such as nitric oxide release. During chronic infection, parasite-specific T lymphocytes release high levels of IFN-gamma, which is required to prevent cyst reactivation. T-cell-mediated cytolytic activity against infected cells, while easily demonstrable, plays a secondary role to inflammatory cytokine production. While part of the clinical manifestations of toxoplasmosis results from direct tissue destruction by the parasite, inflammatory cytokine-mediated immunopathologic changes may also contribute to disease progression.
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Affiliation(s)
- E Y Denkers
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853-6401, USA.
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38
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Subauste CS, Fuh F, de Waal Malefyt R, Remington JS. αβ T Cell Response to Toxoplasma gondii in Previously Unexposed Individuals. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.160.7.3403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The mechanisms by which T cells from previously unexposed hosts respond in vitro to certain intracellular pathogens remain to be fully understood. We report and characterize the in vitro reactivity to Toxoplasma gondii of human αβ T cells from T. gondii-seronegative individuals. Resting αβ T cells from these individuals proliferated in response to PBMC infected with T. gondii or pulsed with T. gondii lysate Ags. This was accompanied by an increase in the percentage of CD4+ αβ T cells. Purified CD4+ αβ T cells but not CD8+ αβ T cells proliferated in response to these T. gondii preparations. Both CD4+ αβ T cells with naive (CD45RA+) and memory (CD45RO+) phenotypes from adults as well as αβ T cells from T. gondii-seronegative newborns proliferated after incubation with T. gondii. This αβ T cell response to the parasite was inhibited by anti-HLA-DR mAb and to a lesser degree by anti-HLA-DQ mAb. Use of paraformaldehyde-fixed PBMC completely abrogated the proliferation of αβ T cells, indicating the need for processing of T. gondii Ags. Analysis of the TCR Vβ expression did not show evidence for restriction in TCR Vβ usage during T. gondii stimulation of αβ T cells. αβ T cells secreted significant amounts of IFN-γ after incubation with T. gondii-infected monocytes. This rapid and remarkable αβ T cell response may play an important role in the early events of the immune response to T. gondii.
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Affiliation(s)
- Carlos S. Subauste
- * Division of Infectious Diseases, University of Cincinnati College of Medicine, Cincinnati, OH 45267
- †Research Institute Palo Alto Medical Foundation, Palo Alto, CA 94301
| | - Franklin Fuh
- †Research Institute Palo Alto Medical Foundation, Palo Alto, CA 94301
| | - Rene de Waal Malefyt
- ‡DNAX Research Institute of Molecular and Cellular Biology, Inc., Palo Alto, CA 94304; and
| | - Jack S. Remington
- †Research Institute Palo Alto Medical Foundation, Palo Alto, CA 94301
- §Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA 94305
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39
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Purner MB, Berens RL, Nash PB, van Linden A, Ross E, Kruse C, Krug EC, Curiel TJ. CD4-mediated and CD8-mediated cytotoxic and proliferative immune responses to Toxoplasma gondii in seropositive humans. Infect Immun 1996; 64:4330-8. [PMID: 8926107 PMCID: PMC174375 DOI: 10.1128/iai.64.10.4330-4338.1996] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Both CD4+ and CD8+ cytotoxic T lymphocytes (CTL) are part of the human immune response to Toxoplasma gondii infection. To further our understanding of Toxoplasma immunity, we investigated factors influencing stimulation of CD4+ or CD8+ human T. gondii-specific immune cells. Both antigen-pulsed and Toxoplasma-infected antigen-presenting cells (APC) induced cell proliferation. Toxoplasma-infected APC elicited strong proliferation of CD4+ cells, but little or no proliferation of CD8+ cells, unless high antigen loads were used. Toxoplasma-infected APC stimulated specific cytotoxicity poorly or not at all, owing to death of stimulated cultures, whereas antigen-pulsed APC strongly elicited specific cytotoxicity. Cytotoxicity elicited by either type of APC resided exclusively in CD4+ T cells in polyclonal cultures. Thus, Toxoplasma-infected APC elicited stronger CD4-mediated than CD8-mediated cell proliferation and generated CD4+ CTL more readily than CD8+ CTL. Nonetheless, specific CD8+ memory cells were demonstrated, and rare CD8+ Toxoplasma-specific CTL were subcloned. Fixed Toxoplasma-infected APC (which induce CD8+ CTL) also elicited cell proliferation, but polyclonal cultures stimulated with these infected APC did not die. Unfixed Toxoplasma-infected APC strongly inhibited phytohemagglutinin-induced cell proliferation, whereas fixed APC did not. These data suggested that infected APC were inhibitory or lethal to some immune cells. Further investigations into interactions between immune cells and Toxoplasma-infected cells likely will help elucidate factors involved in the immunopathogenesis of Toxoplasma infection. As other intracellular parasites, including Plasmodium spp. and Leishmania spp., also elicit CD4+ CTL, such work may help establish paradigms governing immunity to intracellular parasites.
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Affiliation(s)
- M B Purner
- Department of Medicine, Division of Infectious Disease, Denver Veteran's Affairs Medical Center, Colorado 80220. USA
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