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El-Kowrany SI, El Ghaffar AESA, Shoheib ZS, Mady RF, Gamea GAM. Evaluation of nitazoxanide as a novel drug for the treatment of acute and chronic toxoplasmosis. Acta Trop 2019; 195:145-154. [PMID: 30986380 DOI: 10.1016/j.actatropica.2019.04.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/11/2019] [Accepted: 04/11/2019] [Indexed: 01/03/2023]
Abstract
Toxoplasmosis is a widespread, neglected disease with significant morbidity and mortality. In search of an effective treatment, nitazoxanide (NTZ) was evaluated in the treatment of acute and chronic toxoplasmosis in experimental mice. For this purpose, mice were infected with 20 cysts (acute infection model) or 10 cysts (chronic infection model) of Toxoplasma gondii (ME 49 strain). Treated mice received NTZ (at doses of 100 and 150 mg/kg), starting from the third day (acute model) or the fifth week (chronic model) post-infection, which continued for 14 consecutive days. The effects of NTZ were evaluated in comparison to the pyrimethamine/sulfadiazine combination. Evaluation included mortality rates, brain cyst count, inflammatory scoring and immunological studies. The latter included estimation of interferon-gamma (IFN-γ) and induced nitric oxide synthase (iNOS). In the acute infection model, NTZ at 100 and 150 mg/kg significantly reduced the number of brain cysts by 78 and 87% compared to the infected untreated controls and reduced the mortality rate to 24 and 20%, respectively, compared with 44% in the infected untreated control. In the chronic infection model, cyst reduction reached 32 and 38% for 100 and 150 mg/kg NTZ treatments, respectively. NTZ was significantly able to reduce inflammation caused by acute and chronic T. gondii infection with slight necrosis and few infiltrating mononuclear cells. Additionally, the immunological analysis revealed that NTZ significantly increased the production of serum IFN-γ and enhanced iNOS production in brain tissue, suggesting an immunomodulatory role for the drug. Based on the findings of the present study, it can be concluded that NTZ is a potential drug for the treatment of acute and chronic toxoplasmosis.
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Polymorphisms in toll-like receptor (TLR) 1, 4, 9 and SLC11A1 genes and their association with paratuberculosis susceptibility in Holstein and indigenous crossbred cattle in Turkey. J Genet 2018. [DOI: 10.1007/s12041-018-1008-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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3
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Li Y, Xiu F, Mou Z, Xue Z, Du H, Zhou C, Li Y, Shi Y, He S, Zhou H. Exosomes derived from Toxoplasma gondii stimulate an inflammatory response through JNK signaling pathway. Nanomedicine (Lond) 2018. [PMID: 29542367 DOI: 10.2217/nnm-2018-0035] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
AIM Exosomes are nanoscale membranous vesicles secreted by most cell types able to transfer bioactive molecules among cells, which play crucial roles in intercellular communication. We characterized the exosomes derived from Toxoplasma gondii and detected the immune response in macrophages. METHODS We used transmission electron microscopy, nanotracking analysis and western blotting to identify T. gondii exosomes. Functional experiments were performed in RAW264.7 cells for the induction of cytokines, MAPKs (p38 MAPK, ERK 1/2 and c-Jun N-terminal kinase [JNK]), mRNAs and nuclear translocation of phosphorylated JNK protein. RESULTS JNK pathway was activated by T. gondii exosomes, and the production of IL-12, IFN-γ and TNF-α was significantly increased in macrophages. CONCLUSION Our findings demonstrated that T. gondii exosomes elicit innate immune through JNK activation, which could provide new insight into the essential regulators of host-pathogen interactions.
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Affiliation(s)
- Yawen Li
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Jinan, PR China
| | - Fangming Xiu
- Translational Medicine, SickKids Research Institute, The Hospital for Sick Children, Toronto, Canada
| | - Zezhong Mou
- Cheeloo Health Sciences Center, Shandong University, Jinan, PR China
| | - Zhiwei Xue
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Jinan, PR China
| | - Huanhui Du
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Jinan, PR China
| | - Chunxue Zhou
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Jinan, PR China
| | - Yan Li
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Jinan, PR China
| | - Yongyu Shi
- Department of Immunology, School of Basic Medical Sciences, Shandong University, Jinan, PR China
| | - Shenyi He
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Jinan, PR China
| | - Huaiyu Zhou
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Jinan, PR China
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Must K, Hytönen MK, Orro T, Lohi H, Jokelainen P. Toxoplasma gondii seroprevalence varies by cat breed. PLoS One 2017; 12:e0184659. [PMID: 28886182 PMCID: PMC5590984 DOI: 10.1371/journal.pone.0184659] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 08/28/2017] [Indexed: 11/18/2022] Open
Abstract
Toxoplasma gondii is a widespread zoonotic parasite that is relevant for veterinary and public health. The domestic cat, the definitive host species with the largest worldwide population, has become evolutionarily and epidemiologically the most important host of T. gondii. The outcome of T. gondii infection is influenced by congenital and acquired host characteristics. We detected differences in T. gondii seroprevalence by cat breed in our previous studies. The aims of this study were to estimate T. gondii seroprevalence in selected domestic cat breeds, and to evaluate whether being of a certain breed is associated with T. gondii seropositivity, when the age and lifestyle of the cat are taken into account. The studied breeds were the Birman, British Shorthair, Burmese, Korat, Norwegian Forest Cat, Ocicat, Persian, and Siamese. Plasma samples were analyzed for the presence of immunoglobulin G antibodies against T. gondii with a commercial direct agglutination test at dilution 1:40. The samples were accompanied by owner-completed questionnaires that provided background data on the cats. Overall, 41.12% of the 1121 cats tested seropositive, and the seroprevalence increased with age. The Burmese had the lowest seroprevalence (18.82%) and the Persian had the highest (60.00%). According to the final multivariable logistic regression model, the odds to test seropositive were four to seven times higher in Birmans, Ocicats, Norwegian Forest Cats, and Persians when compared with the Burmese, while older age and receiving raw meat were also risk factors for T. gondii seropositivity. This study showed that T. gondii seroprevalence varies by cat breed and identified being of certain breeds, older age, and receiving raw meat as risk factors for seropositivity.
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Affiliation(s)
- Kärt Must
- Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu, Estonia
- * E-mail:
| | - Marjo K. Hytönen
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- Folkhälsan Institute of Genetics, Helsinki, Finland
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Toomas Orro
- Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu, Estonia
| | - Hannes Lohi
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- Folkhälsan Institute of Genetics, Helsinki, Finland
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Pikka Jokelainen
- Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu, Estonia
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
- Statens Serum Institut, Copenhagen, Denmark
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5
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Tassi I, Claudio E, Wang H, Tang W, Ha HL, Saret S, Sher A, Jankovic D, Siebenlist U. Adaptive immune-mediated host resistance to Toxoplasma gondii is governed by the NF-κB regulator Bcl-3 in dendritic cells. Eur J Immunol 2015; 45:1972-9. [PMID: 25884683 PMCID: PMC11042791 DOI: 10.1002/eji.201445045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 03/03/2015] [Accepted: 04/14/2015] [Indexed: 12/21/2022]
Abstract
The atypical IκB family member Bcl-3 associates with p50/NF-κB1 or p52/NF-κB2 homodimers in nuclei, thereby either positively or negatively modulating transcription in a context-dependent manner. Previously we reported that Bcl-3 was critical for host resistance to Toxoplasma gondii. Bcl-3-deficient mice succumbed within 3-5 weeks after infection, correlating with an apparently impaired Th1-type adaptive immune response. However in which cell type(s) Bcl-3 functioned to assure resistance remained unknown. We now show that Bcl-3 expression in dendritic cells is required to generate a protective Th1-type immune response and confer resistance to T. gondii. Surprisingly, mice lacking Bcl-3 in dendritic cells were as susceptible as mice globally deficient for Bcl-3. Furthermore, early innate defenses were not compromised by the absence of Bcl-3, as initial production of IL-12 by dendritic cells and IFN-γ by NK cells were preserved. However, subsequent production of IFN-γ by CD4(+) and CD8(+) T-cells was compromised when dendritic cells lacked Bcl-3, and these mice succumbed at a time when T-cell-mediated IFN-γ production was essential for host resistance. These findings demonstrate that Bcl-3 is required in dendritic cells to prime protective T-cell-mediated immunity to T. gondii.
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Affiliation(s)
- Ilaria Tassi
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Estefania Claudio
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hongshan Wang
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wanhu Tang
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hye-lin Ha
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sun Saret
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alan Sher
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dragana Jankovic
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ulrich Siebenlist
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Patil V, Zhao Y, Shah S, Fox BA, Rommereim LM, Bzik DJ, Yap GS. Co-existence of classical and alternative activation programs in macrophages responding to Toxoplasma gondii. Int J Parasitol 2013; 44:161-4. [PMID: 24083945 DOI: 10.1016/j.ijpara.2013.08.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 08/23/2013] [Accepted: 08/27/2013] [Indexed: 12/21/2022]
Abstract
Pro-inflammatory M1 macrophages are critical for defense against intracellular pathogens while alternatively-activated M2 macrophages mediate tissue homeostasis and repair. Whether these distinct activation programs are mutually exclusive or can co-exist within the same cell is unclear. Here, we report the co-existence of these programs in Toxoplasma gondii-elicited inflammatory macrophages. This is independent of parasite expression of the virulence factor ROP16 and host cell expression of signal transducer and activator of transcription 6 (STAT6). Furthermore, this observation was recapitulated by IFN-γ and IL-4 treated bone marrow-derived macrophages in vitro. These results highlight the multi-functionality of macrophages as they respond to diverse microbial and endogenous stimuli.
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Affiliation(s)
- Veerupaxagouda Patil
- Department of Medicine, Center for Immunity and Inflammation, Rutgers-New Jersey Medical School (NJMS), Newark, NJ 07101, USA
| | - Yanlin Zhao
- Department of Medicine, Center for Immunity and Inflammation, Rutgers-New Jersey Medical School (NJMS), Newark, NJ 07101, USA
| | - Suhagi Shah
- Department of Medicine, Center for Immunity and Inflammation, Rutgers-New Jersey Medical School (NJMS), Newark, NJ 07101, USA
| | - Barbara A Fox
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Leah M Rommereim
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - David J Bzik
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - George S Yap
- Department of Medicine, Center for Immunity and Inflammation, Rutgers-New Jersey Medical School (NJMS), Newark, NJ 07101, USA.
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Braun L, Brenier-Pinchart MP, Yogavel M, Curt-Varesano A, Curt-Bertini RL, Hussain T, Kieffer-Jaquinod S, Coute Y, Pelloux H, Tardieux I, Sharma A, Belrhali H, Bougdour A, Hakimi MA. A Toxoplasma dense granule protein, GRA24, modulates the early immune response to infection by promoting a direct and sustained host p38 MAPK activation. ACTA ACUST UNITED AC 2013; 210:2071-86. [PMID: 24043761 PMCID: PMC3782045 DOI: 10.1084/jem.20130103] [Citation(s) in RCA: 187] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Toxoplasma gondii secretes a novel dense granule protein, GRA24, that traffics from the vacuole to the host cell nucleus where it prolongs p38a activation and correlates with proinflammatory cytokine production. Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular protozoan parasite that resides inside a parasitophorous vacuole. During infection, Toxoplasma actively remodels the transcriptome of its hosting cells with profound and coupled impact on the host immune response. We report that Toxoplasma secretes GRA24, a novel dense granule protein which traffics from the vacuole to the host cell nucleus. Once released into the host cell, GRA24 has the unique ability to trigger prolonged autophosphorylation and nuclear translocation of the host cell p38α MAP kinase. This noncanonical kinetics of p38α activation correlates with the up-regulation of the transcription factors Egr-1 and c-Fos and the correlated synthesis of key proinflammatory cytokines, including interleukin-12 and the chemokine MCP-1, both known to control early parasite replication in vivo. Remarkably, the GRA24–p38α complex is defined by peculiar structural features and uncovers a new regulatory signaling path distinct from the MAPK signaling cascade and otherwise commonly activated by stress-related stimuli or various intracellular microbes.
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Affiliation(s)
- Laurence Braun
- Centre National de la Recherche Scientifique (CNRS), UMR5163, Laboratoire Adaptation et Pathogénie des Microorganismes, F-38041 Grenoble, France
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8
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MAP kinase phosphatase-2 plays a key role in the control of infection with Toxoplasma gondii by modulating iNOS and arginase-1 activities in mice. PLoS Pathog 2013; 9:e1003535. [PMID: 23966857 PMCID: PMC3744406 DOI: 10.1371/journal.ppat.1003535] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 06/18/2013] [Indexed: 11/19/2022] Open
Abstract
The dual specific phosphatase, MAP kinase phosphatase-2 (MKP-2) has recently been demonstrated to negatively regulate macrophage arginase-1 expression, while at the same time to positively regulate iNOS expression. Consequently, MKP-2 is likely to play a significant role in the host interplay with intracellular pathogens. Here we demonstrate that MKP-2(-/-) mice on the C57BL/6 background have enhanced susceptibility compared with wild-type counterparts following infection with type-2 strains of Toxoplasma gondii as measured by increased parasite multiplication during acute infection, increased mortality from day 12 post-infection onwards and increased parasite burdens in the brain, day 30 post-infection. MKP-2(-/-) mice did not, however, demonstrate defective type-1 responses compared with MKP-2(+/+) mice following infection although they did display significantly reduced serum nitrite levels and enhanced tissue arginase-1 expression. Early resistance to T. gondii in MKP-2(+/+), but not MKP-2(-/-), mice was nitric oxide (NO) dependent as infected MKP-2(+/+), but not MKP-2(-/-) mice succumbed within 10 days post-infection with increased parasite burdens following treatment with the iNOS inhibitor L-NAME. Conversely, treatment of infected MKP-2(-/-) but not MKP-2(+/+) mice with nor-NOHA increased parasite burdens indicating a protective role for arginase-1 in MKP-2(-/-) mice. In vitro studies using tachyzoite-infected bone marrow derived macrophages and selective inhibition of arginase-1 and iNOS activities confirmed that both iNOS and arginase-1 contributed to inhibiting parasite replication. However, the effects of arginase-1 were transient and ultimately the role of iNOS was paramount in facilitating long-term inhibition of parasite multiplication within macrophages.
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9
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Ek C, Whary MT, Ihrig M, Bravo LE, Correa P, Fox JG. Serologic evidence that ascaris and toxoplasma infections impact inflammatory responses to Helicobacter pylori in Colombians. Helicobacter 2012; 17:107-15. [PMID: 22404440 PMCID: PMC3305284 DOI: 10.1111/j.1523-5378.2011.00916.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND Helicobacter pylori-infected children from coastal Tumaco, Colombia, have more parasitism, and adults have lower gastric cancer risk compared with high-altitude Pasto/Tuquerres residents. Because helminth and Toxoplasma gondii infections alter helicobacter gastritis in rodent models, we determined whether seropositivity to Ascaris lumbricoides or T. gondii was associated with Th2-IgG1 or Th1-IgG2 responses to H. pylori. METHODS Sera (240) from the two populations were evaluated for A. lumbricoides and T. gondii seropositivity and results correlated with IgE and IgG isotype responses to H. pylori. RESULTS Most Tumaco children and adults were seropositive for A. lumbricoides (89%, 66%), T. gondii (59%, 98%), or both (45%, 66%). In contrast, seropositivity among Pasto/Tuquerres children was much lower (9%A. lumbricoides, 11%T. gondii, and 2% dual positive) but increased in adults (58%A. lumbricoides, 82%T. gondii, and 41% dual positive). A. lumbricoides seropositivity correlated with elevated IgE and anti-inflammatory Th2-IgG1 responses to H. pylori, while T. gondiigondii seropositivity was linked to elevated IgE, pro-inflammatory Th1-IgG2, IgG3, and IgG4 responses to H. pylori. Individuals with high T. gondii titers had reduced Th1-IgG2, IgG3, and IgG4 responses to H. pylori. CONCLUSIONS Results support regional differences for childhood parasitism and indicate A. lumbricoides and T. gondii infections may impact inflammatory responses to H. pylori and partially explain differences in gastric cancer risk in Colombia.
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Affiliation(s)
- Courtney Ek
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Mark T. Whary
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Melanie Ihrig
- Comparative Medicine Program, The Methodist Hospital Research Institute, Houston, Texas 77030, USA
| | - Luis E. Bravo
- Department of Pathology, Universidad del Valle School of Medicine, Cali, 25360, Colombia
| | - Pelayo Correa
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37240, USA
| | - James G. Fox
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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CD8α(+) dendritic cells are the critical source of interleukin-12 that controls acute infection by Toxoplasma gondii tachyzoites. Immunity 2011; 35:249-59. [PMID: 21867928 PMCID: PMC3171793 DOI: 10.1016/j.immuni.2011.08.008] [Citation(s) in RCA: 298] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 05/13/2011] [Accepted: 08/08/2011] [Indexed: 02/02/2023]
Abstract
CD8α(+) dendritic cells (DCs) are important in vivo for cross-presentation of antigens derived from intracellular pathogens and tumors. Additionally, secretion of interleukin-12 (IL-12) by CD8α(+) DCs suggests a role for these cells in response to Toxoplasma gondii antigens, although it remains unclear whether these cells are required for protection against T. gondii infection. Toward this goal, we examined T. gondii infection of Batf3(-/-) mice, which selectively lack only lymphoid-resident CD8α(+) DCs and related peripheral CD103(+) DCs. Batf3(-/-) mice were extremely susceptible to T. gondii infection, with decreased production of IL-12 and interferon-γ. IL-12 administration restored resistance in Batf3(-/-) mice, and mice in which IL-12 production was ablated only from CD8α(+) DCs failed to control infection. These results reveal that the function of CD8α(+) DCs extends beyond a role in cross-presentation and includes a critical role for activation of innate immunity through IL-12 production during T. gondii infection.
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Ong YC, Boyle JP, Boothroyd JC. Strain-dependent host transcriptional responses to Toxoplasma infection are largely conserved in mammalian and avian hosts. PLoS One 2011; 6:e26369. [PMID: 22022607 PMCID: PMC3192797 DOI: 10.1371/journal.pone.0026369] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 09/25/2011] [Indexed: 11/19/2022] Open
Abstract
Toxoplasma gondii has a remarkable ability to infect an enormous variety of mammalian and avian species. Given this, it is surprising that three strains (Types I/II/III) account for the majority of isolates from Europe/North America. The selective pressures that have driven the emergence of these particular strains, however, remain enigmatic. We hypothesized that strain selection might be partially driven by adaptation of strains for mammalian versus avian hosts. To test this, we examine in vitro, strain-dependent host responses in fibroblasts of a representative avian host, the chicken (Gallus gallus). Using gene expression profiling of infected chicken embryonic fibroblasts and pathway analysis to assess host response, we show here that chicken cells respond with distinct transcriptional profiles upon infection with Type II versus III strains that are reminiscent of profiles observed in mammalian cells. To identify the parasite drivers of these differences, chicken fibroblasts were infected with individual F1 progeny of a Type II x III cross and host gene expression was assessed for each by microarray. QTL mapping of transcriptional differences suggested, and deletion strains confirmed, that, as in mammalian cells, the polymorphic rhoptry kinase ROP16 is the major driver of strain-specific responses. We originally hypothesized that comparing avian versus mammalian host response might reveal an inversion in parasite strain-dependent phenotypes; specifically, for polymorphic effectors like ROP16, we hypothesized that the allele with most activity in mammalian cells might be less active in avian cells. Instead, we found that activity of ROP16 alleles appears to be conserved across host species; moreover, additional parasite loci that were previously mapped for strain-specific effects on mammalian response showed similar strain-specific effects in chicken cells. These results indicate that if different hosts select for different parasite genotypes, the selection operates downstream of the signaling occurring during the beginning of the host's immune response.
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Affiliation(s)
- Yi-Ching Ong
- Stanford University, Department of Microbiology and Immunology, Stanford, California, United States of America
| | - Jon P. Boyle
- University of Pittsburgh, Department of Molecular Biology, Pittsburgh, Pennsylvania, United States of America
| | - John C. Boothroyd
- Stanford University, Department of Microbiology and Immunology, Stanford, California, United States of America
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12
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Divanovic S, Sawtell NM, Trompette A, Warning JI, Dias A, Cooper AM, Yap GS, Arditi M, Shimada K, Duhadaway JB, Prendergast GC, Basaraba RJ, Mellor AL, Munn DH, Aliberti J, Karp CL. Opposing biological functions of tryptophan catabolizing enzymes during intracellular infection. J Infect Dis 2011; 205:152-61. [PMID: 21990421 DOI: 10.1093/infdis/jir621] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Recent studies have underscored physiological and pathophysiological roles for the tryptophan-degrading enzyme indolamine 2,3-dioxygenase (IDO) in immune counterregulation. However, IDO was first recognized as an antimicrobial effector, restricting tryptophan availability to Toxoplasma gondii and other pathogens in vitro. The biological relevance of these findings came under question when infectious phenotypes were not forthcoming in IDO-deficient mice. The recent discovery of an IDO homolog, IDO-2, suggested that the issue deserved reexamination. IDO inhibition during murine toxoplasmosis led to 100% mortality, with increased parasite burdens and no evident effects on the immune response. Similar studies revealed a counterregulatory role for IDO during leishmaniasis (restraining effector immune responses and parasite clearance), and no evident role for IDO in herpes simplex virus type 1 (HSV-1) infection. Thus, IDO plays biologically important roles in the host response to diverse intracellular infections, but the dominant nature of this role--antimicrobial or immunoregulatory--is pathogen-specific.
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Affiliation(s)
- Senad Divanovic
- Division of Molecular Immunology, Cincinnati Children's Hospital Research Foundation, and the University of Cincinnati College of Medicine, Ohio, USA
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13
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Abstract
Toxoplasma gondii is a highly successful parasite capable of infecting virtually all warm-blooded animals by actively invading nucleated host cells and forming a modified compartment where it replicates within the cytosol. The parasite-containing vacuole provides a safe haven, even in professional phagocytes such as macrophages, which normally destroy foreign microbes. In an effort to eliminate the parasite, the host up-regulates a family of immunity-related p47 GTPases (IRGs), which are recruited to the parasite-containing vacuole, resulting in membrane rupture and digestion of the parasite. To avoid this fate, highly virulent strains of Toxoplasma coat the external surface of their vacuole with a secretory serine/threonine kinase, known as ROP18. At this host-pathogen interface, ROP18 phosphorylates and inactivates IRGs, thereby protecting the parasite from killing. These findings reveal a novel molecular mechanism by which the parasite disarms host innate immunity.
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Affiliation(s)
- Sarah J Fentress
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA
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14
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Fentress SJ, Behnke MS, Dunay IR, Mashayekhi M, Rommereim LM, Fox BA, Bzik DJ, Taylor GA, Turk BE, Lichti CF, Townsend RR, Qiu W, Hui R, Beatty WL, Sibley LD. Phosphorylation of immunity-related GTPases by a Toxoplasma gondii-secreted kinase promotes macrophage survival and virulence. Cell Host Microbe 2011; 8:484-95. [PMID: 21147463 DOI: 10.1016/j.chom.2010.11.005] [Citation(s) in RCA: 224] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 10/22/2010] [Accepted: 11/18/2010] [Indexed: 12/13/2022]
Abstract
Macrophages are specialized to detect and destroy intracellular microbes and yet a number of pathogens have evolved to exploit this hostile niche. Here we demonstrate that the obligate intracellular parasite Toxoplasma gondii disarms macrophage innate clearance mechanisms by secreting a serine threonine kinase called ROP18, which binds to and phosphorylates immunity-related GTPases (IRGs). Substrate profiling of ROP18 revealed a preference for a conserved motif within switch region I of the GTPase domain, a modification predicted to disrupt IRG function. Consistent with this, expression of ROP18 was both necessary and sufficient to block recruitment of Irgb6, which was in turn required for parasite destruction. ROP18 phosphorylation of IRGs prevented clearance within inflammatory monocytes and IFN-γ-activated macrophages, conferring parasite survival in vivo and promoting virulence. IRGs are implicated in clearance of a variety of intracellular pathogens, suggesting that other virulence factors may similarly thwart this innate cellular defense mechanism.
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Affiliation(s)
- Sarah J Fentress
- Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO 63130, USA
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Henriquez FL, Woods S, Cong H, McLeod R, Roberts CW. Immunogenetics of Toxoplasma gondii informs vaccine design. Trends Parasitol 2010; 26:550-5. [DOI: 10.1016/j.pt.2010.06.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 05/31/2010] [Accepted: 06/02/2010] [Indexed: 11/27/2022]
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16
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Yamamoto M, Standley DM, Takashima S, Saiga H, Okuyama M, Kayama H, Kubo E, Ito H, Takaura M, Matsuda T, Soldati-Favre D, Takeda K. A single polymorphic amino acid on Toxoplasma gondii kinase ROP16 determines the direct and strain-specific activation of Stat3. ACTA ACUST UNITED AC 2009; 206:2747-60. [PMID: 19901082 PMCID: PMC2806617 DOI: 10.1084/jem.20091703] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Infection by Toxoplasma gondii down-regulates the host innate immune responses, such as proinflammatory cytokine production, in a Stat3-dependent manner. A forward genetic approach recently demonstrated that the type II strain fails to suppress immune responses because of a potential defect in a highly polymorphic parasite-derived kinase, ROP16. We generated ROP16-deficient type I parasites by reverse genetics and found a severe defect in parasite-induced Stat3 activation, culminating in enhanced production of interleukin (IL) 6 and IL-12 p40 in the infected macrophages. Furthermore, overexpression of ROP16 but not ROP18 in mammalian cells resulted in Stat3 phosphorylation and strong activation of Stat3-dependent promoters. In addition, kinase-inactive ROP16 failed to activate Stat3. Comparison of type I and type II ROP16 revealed that a single amino acid substitution in the kinase domain determined the strain difference in terms of Stat3 activation. Moreover, ROP16 bound Stat3 and directly induced phosphorylation of this transcription factor. These results formally establish an essential and direct requirement of ROP16 in parasite-induced Stat3 activation and the significance of a single amino acid replacement in the function of type II ROP16.
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Affiliation(s)
- Masahiro Yamamoto
- Department of Microbiology and Immunology, Graduate School of Medicine, World Premier International Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
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17
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Tomita T, Yamada T, Weiss LM, Orlofsky A. Externally triggered egress is the major fate of Toxoplasma gondii during acute infection. THE JOURNAL OF IMMUNOLOGY 2009; 183:6667-80. [PMID: 19846885 DOI: 10.4049/jimmunol.0900516] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The apicomplexan parasite Toxoplasma gondii expands during acute infection via a cycle of invasion, intracellular replication, and lytic egress. Physiological regulation has not yet been demonstrated for either invasion or egress. We now report that, in contrast to cell culture systems, in which egress occurs only after five or more parasite divisions (2-3 days), intracellular residence is strikingly abbreviated in inflammatory cells in vivo, and early egress (after zero to two divisions) is the dominant parasite fate in acutely infected mice. Adoptive transfer experiments demonstrate rapid, reciprocal, kinetically uniform parasite transfer between donor and recipient compartments, with a t(1/2) of approximately 3 h. Inflammatory macrophages are major participants in this cycle of lytic egress and reinfection, which drives rapid macrophage turnover. Inflammatory triggering cells, principally macrophages, elicit egress in infected target macrophages, a process we term externally triggered egress (ETE). The mechanism of ETE does not require reactive oxygen or nitrogen species, the mitochondrial permeability transition pore, or a variety of signal transduction mediators, but is dependent on intracellular calcium and is highly sensitive to SB203580, an inhibitor of p38 MAPK as well as a related parasite-encoded kinase. SB203580 both inhibited the initiation of ETE and altered the progression of egress. Parasites recently completing a cycle of egress and reinfection were preferentially restricted in vivo, supporting a model in which ETE may favor host defense by a process of haven disruption. ETE represents a novel example of interaction between a parasite infectious cycle and host microenvironment.
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Affiliation(s)
- Tadakimi Tomita
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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18
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Miller CM, Boulter NR, Ikin RJ, Smith NC. The immunobiology of the innate response to Toxoplasma gondii. Int J Parasitol 2008; 39:23-39. [PMID: 18775432 DOI: 10.1016/j.ijpara.2008.08.002] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 08/07/2008] [Accepted: 08/11/2008] [Indexed: 01/17/2023]
Abstract
Toxoplasma gondii is a unique intracellular parasite. It can infect a variety of cells in virtually all warm-blooded animals. It has a worldwide distribution and, overall, around one-third of people are seropositive for the parasite, with essentially the entire human population being at risk of infection. For most people, T. gondii causes asymptomatic infection but the parasite can cause serious disease in the immunocompromised and, if contracted for the first time during pregnancy, can cause spontaneous abortion or congenital defects, which have a substantial emotional, social and economic impact. Toxoplasma gondii provokes one of the most potent innate, pro-inflammatory responses of all infectious disease agents. It is also a supreme manipulator of the immune response so that innate immunity to T. gondii is a delicate balance between the parasite and its host involving a coordinated series of cellular interactions involving enterocytes, neutrophils, dendritic cells, macrophages and natural killer cells. Underpinning these interactions is the regulation of complex molecular reactions involving Toll-like receptors, activation of signalling pathways, cytokine production and activation of anti-microbial effector mechanisms including generation of reactive nitrogen and oxygen intermediates.
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Affiliation(s)
- Catherine M Miller
- Institute for the Biotechnology of Infectious Diseases, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia
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19
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Vyas JM, Van der Veen AG, Ploegh HL. The known unknowns of antigen processing and presentation. Nat Rev Immunol 2008; 8:607-18. [PMID: 18641646 PMCID: PMC2735460 DOI: 10.1038/nri2368] [Citation(s) in RCA: 425] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The principal components of both MHC class I and class II antigen processing and presentation pathways are well known. In dendritic cells, these pathways are tightly regulated by Toll-like-receptor signalling and include features, such as cross-presentation, that are not seen in other cell types. However, the exact mechanisms involved in the subcellular trafficking of antigens remain poorly understood and in some cases are controversial. Recent data suggest that diverse cellular machineries, including autophagy, participate in antigen processing and presentation, although their relative contributions remain to be fully elucidated. Here, we highlight some emerging themes of antigen processing and presentation that we think merit further attention.
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Affiliation(s)
- Jatin M Vyas
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA
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20
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Flores M, Saavedra R, Bautista R, Viedma R, Tenorio EP, Leng L, Sánchez Y, Juárez I, Satoskar AA, Shenoy AS, Terrazas LI, Bucala R, Barbi J, Satoskar AR, Rodriguez-Sosa M. Macrophage migration inhibitory factor (MIF) is critical for the host resistance against Toxoplasma gondii. FASEB J 2008; 22:3661-71. [PMID: 18606868 DOI: 10.1096/fj.08-111666] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Macrophage migration inhibitory factor (MIF) exerts either a protective or a deleterious role in the immune response to different pathogens. We analyzed herein the role of MIF in the host control of toxoplasmosis using MIF(-/-) mice backcrossed to either the BALB/c or the C57BL/6 genetic backgrounds. Both, wild-type (WT) BALB/c and MIF(-/-) BALB/c mice were susceptible to infection with highly virulent RH as well as moderately virulent ME49 strains of T. gondii. MIF(-/-) mice, however, showed greater liver damage and more brain cysts, produced less proinflammatory cytokines, and succumbed significantly faster than WT mice. Bone marrow-derived dendritic cells (BMDCs) from MIF(-/-) mice produced less interleukin-1beta, interleukin-12, and tumor necrosis factor-alpha than WT BMDCs after stimulation with soluble Toxoplasma antigen (STAg). Similar observations were made in CD11c(+) low-density cells isolated from the spleens of MIF(-/-) mice challenged with STAg. MIF(-/-) C57BL/6 mice succumbed to ME49 infection faster than their WT counterparts. C57BL/6 mice that succumbed to infection with the ME49 strain produced less MIF than resistant BALB/c mice similarly infected. Interestingly, an analysis of brains from patients with cerebral toxoplasmosis showed low levels of MIF expression. Together, these findings demonstrate that MIF plays a critical role in mediating host resistance against T. gondii.
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Affiliation(s)
- Marcos Flores
- Unidad de Biomedicina, FES-Iztacala, UNAM. Av. de los Barrios #1, Los Reyes Iztacala, 54090 Tlalnepantla, Mexico City, Mexico
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21
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Vidal SM, Malo D, Marquis JF, Gros P. Forward genetic dissection of immunity to infection in the mouse. Annu Rev Immunol 2008; 26:81-132. [PMID: 17953509 DOI: 10.1146/annurev.immunol.26.021607.090304] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Forward genetics is an experimental approach in which gene mapping and positional cloning are used to elucidate the molecular mechanisms underlying phenotypic differences between two individuals for a given trait. This strategy has been highly successful for the study of inbred mouse strains that show differences in innate susceptibility to bacterial, parasitic, fungal, and viral infections. Over the past 20 years, these studies have led to the identification of a number of cell populations and critical biochemical pathways and proteins that are essential for the early detection of and response to invading pathogens. Strikingly, the macrophage is the point of convergence for many of these genetic studies. This has led to the identification of diverse pathways involved in extracellular and intracellular pathogen recognition, modification of the properties and content of phagosomes, transcriptional response, and signal transduction for activation of adaptive immune mechanisms. In models of viral infections, elegant genetic studies highlighted the pivotal role of natural killer cells in the detection and destruction of infected cells.
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Affiliation(s)
- S M Vidal
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada H3G 1Y6
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22
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Maubon D, Ajzenberg D, Brenier-Pinchart MP, Dardé ML, Pelloux H. What are the respective host and parasite contributions to toxoplasmosis? Trends Parasitol 2008; 24:299-303. [PMID: 18514029 DOI: 10.1016/j.pt.2008.03.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Revised: 03/04/2008] [Accepted: 03/15/2008] [Indexed: 12/31/2022]
Abstract
The toxoplasmosis pathogenesis mechanism is complex because parasite and host specificities are interrelated. Advances in fundamental research (including strain genotyping, analyzing the progeny from crosses of different strains and exploring the implication of epigenetic effects on the parasite) have contributed greatly to our current knowledge of this mechanism. At the same time new data on the clinical characteristics of the disease have come to light. For example, highly virulent strains have been isolated recently in immunocompetent patients, and some studies suggest that toxoplasmosis also might be implicated in brain disorders. These recent tools and discoveries are likely to cast new light on the pathogenicity of Toxoplasma parasites and provide the key to understanding this unique form of parasitism.
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Affiliation(s)
- Danièle Maubon
- Laboratoire Adaptation et Pathogénie des Microorganismes, UMR 5163 CNRS-Université Joseph Fourier, Institut J. Roget, BP 170, 38042 Grenoble Cedex 9, France.
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23
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Dzierszinski FS, Hunter CA. Advances in the use of genetically engineered parasites to study immunity to Toxoplasma gondii. Parasite Immunol 2008; 30:235-44. [PMID: 18194347 DOI: 10.1111/j.1365-3024.2007.01016.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Studying in vivo biology and the host immune response to Toxoplasma gondii has yielded many insights into the pathogenesis of this parasitic organism. It is recognized that this infection in immune competent hosts elicits a strong Th1-type response, which is characterized by the generation of parasite-specific CD4(+) and CD8(+) T cells that produce IFN-gamma and provide protective immunity. One of the problems associated with studying resistance to Toxoplasma has been the lack of reagents to track parasite-specific T cell responses with a high degree of specificity. To overcome this difficulty, it is possible to use a combination of transgenic parasites that are engineered to express well-characterized heterologous reporters or antigens, and T cell hybridomas or naïve T cells that express a T cell receptor specific for the processed peptide. These approaches have provided new insights into parasite dissemination, antigen presentation, as well as immune regulation.
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Affiliation(s)
- F S Dzierszinski
- Institute of Parasitology, McGill University, Ste-Anne-de-Bellevue, Canada.
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24
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Immunological control of congenital toxoplasmosis in the murine model. Immunol Lett 2008; 115:83-9. [DOI: 10.1016/j.imlet.2007.10.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2007] [Revised: 10/09/2007] [Accepted: 10/12/2007] [Indexed: 11/23/2022]
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25
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Lee CW, Sukhumavasi W, Denkers EY. Phosphoinositide-3-kinase-dependent, MyD88-independent induction of CC-type chemokines characterizes the macrophage response to Toxoplasma gondii strains with high virulence. Infect Immun 2007; 75:5788-97. [PMID: 17908814 PMCID: PMC2168350 DOI: 10.1128/iai.00821-07] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chemokines play an important role in inflammation and infection due to their ability to recruit cells of innate and adaptive immunity. Here we examined mouse macrophage chemokine responses during intracellular infections with high- and low-virulence Toxoplasma gondii strains. The high-virulence type I strain RH induced a large panel of CC-type chemokines, whereas responses elicited by strains PTG (type II) and M7741 (type III) were much weaker. Strikingly, the T. gondii-induced chemokine response occurred independently of signaling through the Toll-like receptor adaptor MyD88. Instead, production of chemokines during infection was heavily dependent upon phosphoinositide-3-kinase signaling pathways. Because infection with type I strains such as RH results in an uncontrolled proinflammatory cytokine response, we hypothesize that this virulence phenotype is a consequence of early strong induction of chemokines by type I, but not type II or III, Toxoplasma strains.
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Affiliation(s)
- Chiang W Lee
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401, USA
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26
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Abstract
The protozoan, Toxoplasma gondii, is a natural pathogen of mouse and a zoonosis of man. Immunity against the pathogen is largely mediated by interferon-stimulated cell-autonomous mechanisms that are strikingly different between man and mouse. There are many poorly understood host and pathogen variables that affect the outcome of infection.
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27
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Dzierszinski F, Pepper M, Stumhofer JS, LaRosa DF, Wilson EH, Turka LA, Halonen SK, Hunter CA, Roos DS. Presentation of Toxoplasma gondii antigens via the endogenous major histocompatibility complex class I pathway in nonprofessional and professional antigen-presenting cells. Infect Immun 2007; 75:5200-9. [PMID: 17846116 PMCID: PMC2168266 DOI: 10.1128/iai.00954-07] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Challenge with the intracellular protozoan parasite Toxoplasma gondii induces a potent CD8+ T-cell response that is required for resistance to infection, but many questions remain about the factors that regulate the presentation of major histocompatibility complex class I (MHC-I)-restricted parasite antigens and about the role of professional and nonprofessional accessory cells. In order to address these issues, transgenic parasites expressing ovalbumin (OVA), reagents that track OVA/MHC-I presentation, and OVA-specific CD8+ T cells were exploited to compare the abilities of different infected cell types to stimulate CD8+ T cells and to define the factors that contribute to antigen processing. These studies reveal that a variety of infected cell types, including hematopoietic and nonhematopoietic cells, are capable of activating an OVA-specific CD8+ T-cell hybridoma, and that this phenomenon is dependent on the transporter associated with antigen processing and requires live T. gondii. Several experimental approaches indicate that T-cell activation is a consequence of direct presentation by infected host cells rather than cross-presentation. Surprisingly, nonprofessional antigen-presenting cells (APCs) were at least as efficient as dendritic cells at activating this MHC-I-restricted response. Studies to assess whether these cells are involved in initiation of the CD8+ T-cell response to T. gondii in vivo show that chimeric mice expressing MHC-I only in nonhematopoietic compartments are able to activate OVA-specific CD8+ T cells upon challenge. These findings associate nonprofessional APCs with the initial activation of CD8+ T cells during toxoplasmosis.
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Affiliation(s)
- Florence Dzierszinski
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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28
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Ottenhoff THM. Introduction: New susceptibility genes in mycobacterial infectious diseases. Microbes Infect 2006; 8:1117-8. [PMID: 16517199 DOI: 10.1016/j.micinf.2005.10.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Accepted: 10/19/2005] [Indexed: 10/25/2022]
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