Autophagy. 2012 Mar 1;8(3). [Epub ahead of print]
Role of ATG3 in the parasite Toxoplasma gondii: Autophagy in an early branching eukaryote.
Besteiro S.
Source
DIMNP; UMR 5235 CNRS; Université de Montpellier 2; Montpellier, France.
Abstract
Toxoplasma gondii belongs to the phylum Apicomplexa, a diverse group of early branching unicellular eukaryotes related to dinoflagellates and ciliates. Like several other Apicomplexa such as Plasmodium (the causative agent of malaria), T. gondii is a human pathogen responsible for a potentially lethal disease called toxoplasmosis. Most Apicomplexa have complex life cycles, involving intermediate hosts and vectors, which include obligatory intracellular developmental stages. In the case of malaria and toxoplasmosis, it is that replicative process, leading to the ultimate lysis of the host cell, which is causing the symptoms of the disease. For Toxoplasma, the invasive and fast-replicating form of the parasite is called the tachyzoite. While autophagy has been a fast-growing field of research in recent years, not much was known about the relevance of this catabolic process in medically important apicomplexan parasites. Vesicles resembling autophagosomes had been described in drug-treated Plasmodium parasites in the early 1970s and a potential role for autophagy in organelle recycling during differentiation between Plasmodium life stages has also been recently described. Interestingly, recent database searches have identified putative orthologs of the core machinery responsible for the formation of autophagosomes in several protists, including Toxoplasma. In spite of an apparently reduced machinery (only about one-third of the yeast ATG genes appear to be conserved), T. gondii seemed thus able to perform macroautophagy, but the cellular functions of the pathway for this parasite remained to be demonstrated.
PMID: 22361579 [PubMed - as supplied by publisher]
Sunday, March 04, 2012
Interactions between the ROP18 kinase and host cell proteins that aid in the parasitism of Toxoplasma gondii
Acta Trop. 2012 Feb 16. [Epub ahead of print]
Interactions between the ROP18 kinase and host cell proteins that aid in the parasitism of Toxoplasma gondii.
Cheng L, Chen Y, Chen L, Shen Y, Shen J, An R, Luo Q, Du J.
Source
Department of Biochemistry and Molecular Biology, Anhui Medical University, Hefei 230032, China.
Abstract
Serine/threonine kinases secreted from rhoptry organelles are important virulence factors for Toxoplasma gondii. Among rhoptry proteins, the ROP18 kinase has been identified as a key virulence determinant mediating pathogenesis in T. gondii; however, the molecular mechanisms by which this kinase exerts its pathogenic action remain poorly understood. In this study, the interactions between the ROP18 kinase of Toxoplasma gondii and the host cell proteins were analyzed using a yeast two-hybrid technique. The cMyc-ROP18(25-251) fusion proteins expressed by pGBKT7 plasmids in AH109 yeast were bound to host cell proteins from a human fetal brain cDNA library transformed to AH109 yeast using a mating method. Using these selection procedures, we identified seven host proteins that had not previously been reported to interact with ROP18 such as DDB1, TOR1AIP1, integrin, SLC3A2, TPST2, DERL2 and OCIAD1. These host proteins are associated with DNA repair, transcriptional regulation, translation modification, protein degradation and cell adhesion. Our data strongly support the hypothesis that the secreted kinase ROP18 is involved in several complex cellular pathways for the invasion and commandeering of host functions.
Copyright © 2012. Published by Elsevier B.V.
PMID: 22365922 [PubMed - as supplied by publisher]
Interactions between the ROP18 kinase and host cell proteins that aid in the parasitism of Toxoplasma gondii.
Cheng L, Chen Y, Chen L, Shen Y, Shen J, An R, Luo Q, Du J.
Source
Department of Biochemistry and Molecular Biology, Anhui Medical University, Hefei 230032, China.
Abstract
Serine/threonine kinases secreted from rhoptry organelles are important virulence factors for Toxoplasma gondii. Among rhoptry proteins, the ROP18 kinase has been identified as a key virulence determinant mediating pathogenesis in T. gondii; however, the molecular mechanisms by which this kinase exerts its pathogenic action remain poorly understood. In this study, the interactions between the ROP18 kinase of Toxoplasma gondii and the host cell proteins were analyzed using a yeast two-hybrid technique. The cMyc-ROP18(25-251) fusion proteins expressed by pGBKT7 plasmids in AH109 yeast were bound to host cell proteins from a human fetal brain cDNA library transformed to AH109 yeast using a mating method. Using these selection procedures, we identified seven host proteins that had not previously been reported to interact with ROP18 such as DDB1, TOR1AIP1, integrin, SLC3A2, TPST2, DERL2 and OCIAD1. These host proteins are associated with DNA repair, transcriptional regulation, translation modification, protein degradation and cell adhesion. Our data strongly support the hypothesis that the secreted kinase ROP18 is involved in several complex cellular pathways for the invasion and commandeering of host functions.
Copyright © 2012. Published by Elsevier B.V.
PMID: 22365922 [PubMed - as supplied by publisher]
The impaired pregnancy outcome in murine congenital toxoplasmosis is associated with a pro-inflammatory immune response
Int J Parasitol. 2012 Feb 17. [Epub ahead of print]
The impaired pregnancy outcome in murine congenital toxoplasmosis is associated with a pro-inflammatory immune response, but not correlated with decidual inducible nitric oxide synthase expression.
Coutinho LB, Gomes AO, Araújo EC, Barenco PV, Santos JL, Caixeta DR, Silva DA, Junior JP, Ferro EA, Silva NM.
Source
Laboratory of Immunopathology, Institute of Biomedical Sciences, Federal University of Uberlândia, Av. Pará 1720, Uberlândia, MG 38400-902, Brazil.
Abstract
Congenital toxoplasmosis is associated with adverse pregnancy outcome. Despite the type 1 immune response, C57BL/6 mice are more susceptible than BALB/c mice to Toxoplasma gondii infection. Additionally, successful pregnancy appears to be correlated with type 2 T helper maternal immunity and regulatory T cells. In order to investigate the mechanisms of susceptibility/resistance to congenital toxoplasmosis in mice with different genetic backgrounds and the influence of inducible nitric oxide synthase in pregnancy outcome, groups of C57BL/6, BALB/c and C57BL/6 iNOS(-/-) females were orally infected with T. gondii ME-49 strain on day 1 of pregnancy and were sacrificed on day 8 p.i. and day 19 p.i. The uterus and placenta were evaluated for the foetal resorption rate, parasite load, immunological and histological changes. C57BL/6 mice presented inflammatory foci in the decidua (endometrium) of the uterus at a higher frequency than BALB/c mice on day 8 p.i., and a large number of pregnant C57BL/6 mice presented necrotic implantation sites. The parasite was seldom found in the uterus or placenta of either lineage of mice. Interestingly, there was no observed difference in inducible nitric oxide synthase expression in the uterus and placenta of infected mice. In addition, higher levels of TNF-α were detected in serum samples from C57BL/6 mice compared with BALB/c mice. Accordingly, C57BL/6 mice presented with levels of 90% abortion compared with 50% in BALB/c mice on day 19 p.i. C57BL/6 iNOS(-/-) mice showed low placental parasite counts and high absorption rates, similar to wild type mice. The data suggest that the impaired pregnancy outcome due to T. gondii infection in C57BL/6 mice could be associated with a higher inflammatory response leading to cell apoptosis and necrosis of implantation sites compared with BALB/c mice, and this phenomenon was not due to inducible nitric oxide synthase expression in the decidua.
Copyright © 2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.
PMID: 22366549 [PubMed - as supplied by publisher]
The impaired pregnancy outcome in murine congenital toxoplasmosis is associated with a pro-inflammatory immune response, but not correlated with decidual inducible nitric oxide synthase expression.
Coutinho LB, Gomes AO, Araújo EC, Barenco PV, Santos JL, Caixeta DR, Silva DA, Junior JP, Ferro EA, Silva NM.
Source
Laboratory of Immunopathology, Institute of Biomedical Sciences, Federal University of Uberlândia, Av. Pará 1720, Uberlândia, MG 38400-902, Brazil.
Abstract
Congenital toxoplasmosis is associated with adverse pregnancy outcome. Despite the type 1 immune response, C57BL/6 mice are more susceptible than BALB/c mice to Toxoplasma gondii infection. Additionally, successful pregnancy appears to be correlated with type 2 T helper maternal immunity and regulatory T cells. In order to investigate the mechanisms of susceptibility/resistance to congenital toxoplasmosis in mice with different genetic backgrounds and the influence of inducible nitric oxide synthase in pregnancy outcome, groups of C57BL/6, BALB/c and C57BL/6 iNOS(-/-) females were orally infected with T. gondii ME-49 strain on day 1 of pregnancy and were sacrificed on day 8 p.i. and day 19 p.i. The uterus and placenta were evaluated for the foetal resorption rate, parasite load, immunological and histological changes. C57BL/6 mice presented inflammatory foci in the decidua (endometrium) of the uterus at a higher frequency than BALB/c mice on day 8 p.i., and a large number of pregnant C57BL/6 mice presented necrotic implantation sites. The parasite was seldom found in the uterus or placenta of either lineage of mice. Interestingly, there was no observed difference in inducible nitric oxide synthase expression in the uterus and placenta of infected mice. In addition, higher levels of TNF-α were detected in serum samples from C57BL/6 mice compared with BALB/c mice. Accordingly, C57BL/6 mice presented with levels of 90% abortion compared with 50% in BALB/c mice on day 19 p.i. C57BL/6 iNOS(-/-) mice showed low placental parasite counts and high absorption rates, similar to wild type mice. The data suggest that the impaired pregnancy outcome due to T. gondii infection in C57BL/6 mice could be associated with a higher inflammatory response leading to cell apoptosis and necrosis of implantation sites compared with BALB/c mice, and this phenomenon was not due to inducible nitric oxide synthase expression in the decidua.
Copyright © 2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.
PMID: 22366549 [PubMed - as supplied by publisher]
Metabolic pathway analysis and molecular docking analysis for identification of putative drug targets in Toxoplasma gondii: novel approach
Bioinformation. 2012;8(3):134-41. Epub 2012 Feb 3.
Metabolic pathway analysis and molecular docking analysis for identification of putative drug targets in Toxoplasma gondii: novel approach.
Gautam B, Singh G, Wadhwa G, Farmer R, Singh S, Singh AK, Jain PA, Yadav PK.
Abstract
Toxoplasma gondii is an obligate intracellular apicomplexan parasite that can infect a wide range of warm-blooded animals including humans. In humans and other intermediate hosts, toxoplasma develops into chronic infection that cannot be eliminated by host's immune response or by currently used drugs. In most cases, chronic infections are largely asymptomatic unless the host becomes immune compromised. Thus, toxoplasma is a global health problem and the situation has become more precarious due to the advent of HIV infections and poor toleration of drugs used to treat toxoplasma infection, having severe side effects and also resistance have been developed to the current generation of drugs. The emergence of these drug resistant varieties of T. gondii has led to a search for novel drug targets. We have performed a comparative analysis of metabolic pathways of the host Homo sapiens and the pathogen T. gondii. The enzymes in the unique pathways of T. gondii, which do not show similarity to any protein from the host, represent attractive potential drug targets. We have listed out 11 such potential drug targets which are playing some important work in more than one pathway. Out of these, one important target is Glutamate dehydrogenase enzyme; it plays crucial part in oxidation reduction, metabolic process and amino acid metabolic process. As this is also present in the targets of tropical diseases of TDR (Tropical disease related Drug) target database and no PDB and MODBASE 3D structural model is available, homology models for Glutamate dehydrogenase enzyme were generated using MODELLER9v6. The model was further explored for the molecular dynamics simulation study with GROMACS, virtual screening and docking studies with suitable inhibitors against the NCI diversity subset molecules from ZINC database, by using AutoDock-Vina. The best ten docking solutions were selected (ZINC01690699, ZINC17465979, ZINC17465983, ZINC18141294_03, ZINC05462670, ZINC01572309, ZINC18055497_01, ZINC18141294, ZINC05462674 and ZINC13152284_01). Further the Complexes were analyzed through LIGPLOT. On the basis of Complex scoring and binding ability it is deciphered that these NCI diversity set II compounds, specifically ZINC01690699 (as it has minimum energy score and one of the highest number of interactions with the active site residue), could be promising inhibitors for T. gondii using Glutamate dehydrogenase as Drug target.
PMID: 22368385 [PubMed - in process] PMCID: PMC3283885
Metabolic pathway analysis and molecular docking analysis for identification of putative drug targets in Toxoplasma gondii: novel approach.
Gautam B, Singh G, Wadhwa G, Farmer R, Singh S, Singh AK, Jain PA, Yadav PK.
Abstract
Toxoplasma gondii is an obligate intracellular apicomplexan parasite that can infect a wide range of warm-blooded animals including humans. In humans and other intermediate hosts, toxoplasma develops into chronic infection that cannot be eliminated by host's immune response or by currently used drugs. In most cases, chronic infections are largely asymptomatic unless the host becomes immune compromised. Thus, toxoplasma is a global health problem and the situation has become more precarious due to the advent of HIV infections and poor toleration of drugs used to treat toxoplasma infection, having severe side effects and also resistance have been developed to the current generation of drugs. The emergence of these drug resistant varieties of T. gondii has led to a search for novel drug targets. We have performed a comparative analysis of metabolic pathways of the host Homo sapiens and the pathogen T. gondii. The enzymes in the unique pathways of T. gondii, which do not show similarity to any protein from the host, represent attractive potential drug targets. We have listed out 11 such potential drug targets which are playing some important work in more than one pathway. Out of these, one important target is Glutamate dehydrogenase enzyme; it plays crucial part in oxidation reduction, metabolic process and amino acid metabolic process. As this is also present in the targets of tropical diseases of TDR (Tropical disease related Drug) target database and no PDB and MODBASE 3D structural model is available, homology models for Glutamate dehydrogenase enzyme were generated using MODELLER9v6. The model was further explored for the molecular dynamics simulation study with GROMACS, virtual screening and docking studies with suitable inhibitors against the NCI diversity subset molecules from ZINC database, by using AutoDock-Vina. The best ten docking solutions were selected (ZINC01690699, ZINC17465979, ZINC17465983, ZINC18141294_03, ZINC05462670, ZINC01572309, ZINC18055497_01, ZINC18141294, ZINC05462674 and ZINC13152284_01). Further the Complexes were analyzed through LIGPLOT. On the basis of Complex scoring and binding ability it is deciphered that these NCI diversity set II compounds, specifically ZINC01690699 (as it has minimum energy score and one of the highest number of interactions with the active site residue), could be promising inhibitors for T. gondii using Glutamate dehydrogenase as Drug target.
PMID: 22368385 [PubMed - in process] PMCID: PMC3283885
Multiple determinants for selective inhibition of apicomplexan calcium-dependent protein kinase CDPK1
J Med Chem. 2012 Feb 27. [Epub ahead of print]
Multiple determinants for selective inhibition of apicomplexan calcium-dependent protein kinase CDPK1.
Larson ET, Ojo KK, Murphy RC, Johnson SM, Zhang Z, Kim JE, Leibly DJ, Fox AM, Reid MC, Dale EJ, Perera BG, Kim J, Hewitt SN, Hol WG, Verlinde CL, Fan E, Van Voorhis WC, Maly DJ, Merritt EA.
Abstract
Diseases caused by the apicomplexan protozoans Toxoplasma gondii and Cryptosporidium parvum are a major health concern. The life cycle of these parasites is regulated by a family of calcium-dependent protein kinases (CDPKs) that have no direct homologs in the human host. Fortuitously, CDPK1 from both parasites contains a rare glycine gatekeeper residue adjacent to the ATP-binding pocket. This has allowed creation of a series of C3-substituted pyrazolopyrimidine compounds that are potent inhibitors selective for CDPK1 over a panel of human kinases. Here we demonstrate that selectivity is further enhanced by modification of the scaffold at the C1 position. The explanation for this unexpected result is provided by crystal structures of the inhibitors bound to CDPK1 and the human kinase c-SRC. Furthermore, the insight gained from these studies was applied to transform an alternative ATP-competitive scaffold lacking potency and selectivity for CDPK1 into a low nanomolar inhibitor of this enzyme with no activity against SRC.
PMID: 22369268 [PubMed - as supplied by publisher]
Multiple determinants for selective inhibition of apicomplexan calcium-dependent protein kinase CDPK1.
Larson ET, Ojo KK, Murphy RC, Johnson SM, Zhang Z, Kim JE, Leibly DJ, Fox AM, Reid MC, Dale EJ, Perera BG, Kim J, Hewitt SN, Hol WG, Verlinde CL, Fan E, Van Voorhis WC, Maly DJ, Merritt EA.
Abstract
Diseases caused by the apicomplexan protozoans Toxoplasma gondii and Cryptosporidium parvum are a major health concern. The life cycle of these parasites is regulated by a family of calcium-dependent protein kinases (CDPKs) that have no direct homologs in the human host. Fortuitously, CDPK1 from both parasites contains a rare glycine gatekeeper residue adjacent to the ATP-binding pocket. This has allowed creation of a series of C3-substituted pyrazolopyrimidine compounds that are potent inhibitors selective for CDPK1 over a panel of human kinases. Here we demonstrate that selectivity is further enhanced by modification of the scaffold at the C1 position. The explanation for this unexpected result is provided by crystal structures of the inhibitors bound to CDPK1 and the human kinase c-SRC. Furthermore, the insight gained from these studies was applied to transform an alternative ATP-competitive scaffold lacking potency and selectivity for CDPK1 into a low nanomolar inhibitor of this enzyme with no activity against SRC.
PMID: 22369268 [PubMed - as supplied by publisher]
Vaccination with a DNA vaccine coding Perforin-like Protein 1 (TgPLP1) and MIC6 Induces Significant Protective Immunity Against Toxoplasma
Clin Vaccine Immunol. 2012 Feb 29. [Epub ahead of print]
Vaccination with a DNA vaccine coding Perforin-like Protein 1 (TgPLP1) and MIC6 Induces Significant Protective Immunity Against Toxoplasma gondii.
Yan HK, Yuan ZG, Song HQ, Petersen E, Zhou Y, Ren D, Zhou DH, Li HX, Lin RQ, Yang GL, Zhu XQ.
Source
State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu Province 730046, People's Republic of China.
Abstract
Host cell invasion by Toxoplasma gondii is tightly related to micronemal protein 6 (MIC6) and T. gondii perforin-like protein 1 (TgPLP1). In this study, we constructed a DNA vaccine expressing a fusion protein of TgPLP1/MIC6 using vector pIRESneo, and evaluated the immune response it induced in Kunming mice. Levels of IgG antibody, IFN-γ, IL-2, IL-12, IL-4 and IL-10 were examined. Five mice were randomly chosen from every group (vaccinated or non-vaccinated control groups) and were intragastrically challenged with 80 cysts of the T. gondii PRU strain (genotype II) strain to observe mortality daily. To analyze protection against less virulent challenge, eight mice of each group were orally infected with 20 cysts of the PRU strain at the 14th day after the last immunization. The brain parasite load was evaluated 6 weeks after infection. The results demonstrated that the immunization with pIRESneo/MIC6/PLP1 resulted in the lowest brain cyst count and prolonged the survival time of immunized mice. The levels of Toxoplasma-specific IgG, IFN-γ, IL-2 and IL-12 increased significantly, and the cysts in brains decreased more obviously in the group immunized with the plasmid pIRESneo/MIC6/PLP1 than the other groups (P < 0.05). Compared with pIRESneo/MIC6/PLP1, co-immunization of pIRESneo/MIC6/PLP1 with adjuvant murine IL-18 promoted cellular and humoral immune responses, but did not contribute significantly in cyst reduction (65.43% vs 61.60%) or survival of immunized mice (45.0 ± 2.9 days vs 42.8 ± 2.9 days) (P > 0.05). Furthermore, the study also showed that immune efficacy induced by pIRESneo/MIC6/PLP1 was better than that induced by pVAX/PLP1 or pVAX/MIC6 alone.
PMID: 22379063 [PubMed - as supplied by publisher]
Vaccination with a DNA vaccine coding Perforin-like Protein 1 (TgPLP1) and MIC6 Induces Significant Protective Immunity Against Toxoplasma gondii.
Yan HK, Yuan ZG, Song HQ, Petersen E, Zhou Y, Ren D, Zhou DH, Li HX, Lin RQ, Yang GL, Zhu XQ.
Source
State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu Province 730046, People's Republic of China.
Abstract
Host cell invasion by Toxoplasma gondii is tightly related to micronemal protein 6 (MIC6) and T. gondii perforin-like protein 1 (TgPLP1). In this study, we constructed a DNA vaccine expressing a fusion protein of TgPLP1/MIC6 using vector pIRESneo, and evaluated the immune response it induced in Kunming mice. Levels of IgG antibody, IFN-γ, IL-2, IL-12, IL-4 and IL-10 were examined. Five mice were randomly chosen from every group (vaccinated or non-vaccinated control groups) and were intragastrically challenged with 80 cysts of the T. gondii PRU strain (genotype II) strain to observe mortality daily. To analyze protection against less virulent challenge, eight mice of each group were orally infected with 20 cysts of the PRU strain at the 14th day after the last immunization. The brain parasite load was evaluated 6 weeks after infection. The results demonstrated that the immunization with pIRESneo/MIC6/PLP1 resulted in the lowest brain cyst count and prolonged the survival time of immunized mice. The levels of Toxoplasma-specific IgG, IFN-γ, IL-2 and IL-12 increased significantly, and the cysts in brains decreased more obviously in the group immunized with the plasmid pIRESneo/MIC6/PLP1 than the other groups (P < 0.05). Compared with pIRESneo/MIC6/PLP1, co-immunization of pIRESneo/MIC6/PLP1 with adjuvant murine IL-18 promoted cellular and humoral immune responses, but did not contribute significantly in cyst reduction (65.43% vs 61.60%) or survival of immunized mice (45.0 ± 2.9 days vs 42.8 ± 2.9 days) (P > 0.05). Furthermore, the study also showed that immune efficacy induced by pIRESneo/MIC6/PLP1 was better than that induced by pVAX/PLP1 or pVAX/MIC6 alone.
PMID: 22379063 [PubMed - as supplied by publisher]
Friday, February 24, 2012
Novel N-Benzoyl-2-hydroxybenzamide Disrupts Unique Parasite Secretory Pathway
Antimicrob Agents Chemother. 2012 Feb 21. [Epub ahead of print]
Novel N-Benzoyl-2-hydroxybenzamide Disrupts Unique Parasite Secretory Pathway.
Fomovska A, Huang Q, El Bissati K, Mui EJ, Witola WH, Cheng G, Zhou Y, Sommerville C, Roberts CW, Bettis S, Prigge ST, Afanador GA, Hickman MR, Lee PJ, Leed SE, Auschwitz JM, Pieroni M, Stec J, Muench SP, Rice DW, Kozikowski AP, McLeod R.
Source
Department of Ophthalmology and Visual Sciences, Pediatrics (Infectious Diseases), Committees on Genetics, Immunology, and Molecular Medicine, Institute of Genomics and Systems Biology, and The College, The University of Chicago, Chicago, Illinois 60637, United States.
Abstract
Toxoplasma gondii is a protozoan parasite that can damage the human brain and eyes. There are no curative medicines. Herein, we describe our discovery of N-benzoyl-2-hydroxybenzamides as a class of compounds effective in low nanomolar range against T. gondii in vitro and in vivo. Our lead compound QQ-437 displays robust activity against the parasite, useful as a new scaffold for development of novel and improved inhibitors of T. gondii. Our genome-wide investigations reveal a specific mechanism of resistance to N-benzoyl-2-hydroxybenzamides mediated by Adaptin-3β, a large protein from the secretory protein complex. N-benzoyl-2-hydroxybenzamide -resistant clones have alterations of their secretory pathway which traffics proteins to micronemes, rhoptries, dense granules and acidocalcisome/Plant-Like Vacuole (PLV). N-benzoyl-2-hydroxybenzamide treatment also alters micronemes, rhoptries, the contents of dense granules and most markedly acidocalcisomes/PLV. Furthermore, QQ-437 is active against chloroquine-resistant Plasmodium falciparum. Our studies reveal a novel class of compounds that disrupts a unique secretory pathway of T. gondii, with potential to be used as scaffolds to discover improved compounds to treat the devastating diseases caused by apicomplexan parasites.
PMID: 22354304 [PubMed - as supplied by publisher]
Novel N-Benzoyl-2-hydroxybenzamide Disrupts Unique Parasite Secretory Pathway.
Fomovska A, Huang Q, El Bissati K, Mui EJ, Witola WH, Cheng G, Zhou Y, Sommerville C, Roberts CW, Bettis S, Prigge ST, Afanador GA, Hickman MR, Lee PJ, Leed SE, Auschwitz JM, Pieroni M, Stec J, Muench SP, Rice DW, Kozikowski AP, McLeod R.
Source
Department of Ophthalmology and Visual Sciences, Pediatrics (Infectious Diseases), Committees on Genetics, Immunology, and Molecular Medicine, Institute of Genomics and Systems Biology, and The College, The University of Chicago, Chicago, Illinois 60637, United States.
Abstract
Toxoplasma gondii is a protozoan parasite that can damage the human brain and eyes. There are no curative medicines. Herein, we describe our discovery of N-benzoyl-2-hydroxybenzamides as a class of compounds effective in low nanomolar range against T. gondii in vitro and in vivo. Our lead compound QQ-437 displays robust activity against the parasite, useful as a new scaffold for development of novel and improved inhibitors of T. gondii. Our genome-wide investigations reveal a specific mechanism of resistance to N-benzoyl-2-hydroxybenzamides mediated by Adaptin-3β, a large protein from the secretory protein complex. N-benzoyl-2-hydroxybenzamide -resistant clones have alterations of their secretory pathway which traffics proteins to micronemes, rhoptries, dense granules and acidocalcisome/Plant-Like Vacuole (PLV). N-benzoyl-2-hydroxybenzamide treatment also alters micronemes, rhoptries, the contents of dense granules and most markedly acidocalcisomes/PLV. Furthermore, QQ-437 is active against chloroquine-resistant Plasmodium falciparum. Our studies reveal a novel class of compounds that disrupts a unique secretory pathway of T. gondii, with potential to be used as scaffolds to discover improved compounds to treat the devastating diseases caused by apicomplexan parasites.
PMID: 22354304 [PubMed - as supplied by publisher]
Wednesday, February 22, 2012
Transcriptomic analysis of toxoplasma development reveals many novel functions and structures specific to sporozoites and oocysts
PLoS One. 2012;7(2):e29998. Epub 2012 Feb 13.
Transcriptomic analysis of toxoplasma development reveals many novel functions and structures specific to sporozoites and oocysts.
Fritz HM, Buchholz KR, Chen X, Durbin-Johnson B, Rocke DM, Conrad PA, Boothroyd JC.
Source
Department of Pathology, Microbiology and Immunology, University of California Davis, School of Veterinary Medicine, Davis, California, United States of America.
Abstract
Sexual reproduction of Toxoplasma gondii occurs exclusively within enterocytes of the definitive felid host. The resulting immature oocysts are excreted into the environment during defecation, where in the days following, they undergo a complex developmental process. Within each oocyst, this culminates in the generation of two sporocysts, each containing 4 sporozoites. A single felid host is capable of shedding millions of oocysts, which can survive for years in the environment, are resistant to most methods of microbial inactivation during water-treatment and are capable of producing infection in warm-blooded hosts at doses as low as 1-10 ingested oocysts. Despite its extremely interesting developmental biology and crucial role in initiating an infection, almost nothing is known about the oocyst stage beyond morphological descriptions. Here, we present a complete transcriptomic analysis of the oocyst from beginning to end of its development. In addition, and to identify genes whose expression is unique to this developmental form, we compared the transcriptomes of developing oocysts with those of in vitro-derived tachyzoites and in vivo-derived bradyzoites. Our results reveal many genes whose expression is specifically up- or down-regulated in different developmental stages, including many genes that are likely critical to oocyst development, wall formation, resistance to environmental destruction and sporozoite infectivity. Of special note is the up-regulation of genes that appear "off" in tachyzoites and bradyzoites but that encode homologues of proteins known to serve key functions in those asexual stages, including a novel pairing of sporozoite-specific paralogues of AMA1 and RON2, two proteins that have recently been shown to form a crucial bridge during tachyzoite invasion of host cells. This work provides the first in-depth insight into the development and functioning of one of the most important but least studied stages in the Toxoplasma life cycle.
PMID: 22347997 [PubMed - in process]
Transcriptomic analysis of toxoplasma development reveals many novel functions and structures specific to sporozoites and oocysts.
Fritz HM, Buchholz KR, Chen X, Durbin-Johnson B, Rocke DM, Conrad PA, Boothroyd JC.
Source
Department of Pathology, Microbiology and Immunology, University of California Davis, School of Veterinary Medicine, Davis, California, United States of America.
Abstract
Sexual reproduction of Toxoplasma gondii occurs exclusively within enterocytes of the definitive felid host. The resulting immature oocysts are excreted into the environment during defecation, where in the days following, they undergo a complex developmental process. Within each oocyst, this culminates in the generation of two sporocysts, each containing 4 sporozoites. A single felid host is capable of shedding millions of oocysts, which can survive for years in the environment, are resistant to most methods of microbial inactivation during water-treatment and are capable of producing infection in warm-blooded hosts at doses as low as 1-10 ingested oocysts. Despite its extremely interesting developmental biology and crucial role in initiating an infection, almost nothing is known about the oocyst stage beyond morphological descriptions. Here, we present a complete transcriptomic analysis of the oocyst from beginning to end of its development. In addition, and to identify genes whose expression is unique to this developmental form, we compared the transcriptomes of developing oocysts with those of in vitro-derived tachyzoites and in vivo-derived bradyzoites. Our results reveal many genes whose expression is specifically up- or down-regulated in different developmental stages, including many genes that are likely critical to oocyst development, wall formation, resistance to environmental destruction and sporozoite infectivity. Of special note is the up-regulation of genes that appear "off" in tachyzoites and bradyzoites but that encode homologues of proteins known to serve key functions in those asexual stages, including a novel pairing of sporozoite-specific paralogues of AMA1 and RON2, two proteins that have recently been shown to form a crucial bridge during tachyzoite invasion of host cells. This work provides the first in-depth insight into the development and functioning of one of the most important but least studied stages in the Toxoplasma life cycle.
PMID: 22347997 [PubMed - in process]
Identification of potential apicoplast associated therapeutic targets in human and animal pathogen Toxoplasma gondii ME49
Bioinformation. 2011;7(8):379-83. Epub 2011 Dec 21.
Identification of potential apicoplast associated therapeutic targets in human and animal pathogen Toxoplasma gondii ME49.
Saremy S, Boroujeni ME, Bhattacharjee B, Mittal V, Chatterjee J.
Abstract
Toxoplasma gondii ME49 is an obligatory intracellular apicomplexa parasite that causes toxoplasmosis in humans, domesticated and wild animals. Waterborne outbreaks of acute toxoplasmosis worldwide reinforce the transmission of Toxoplasma gondii ME49 to humans through contaminated water and may have a greater epidemiological impact than previously believed. In the quest for drug and vaccine target identification subtractive genomics involving subtraction between the host and pathogen genome has been implemented for enlisting essential pathogen specific proteins. Using this approach, our analysis on both human and Toxoplasma gondii ME49 reveals that out of 7987 protein coding sequences of the pathogen, 950 represent essential non human-homologous proteins. Subcellular localization prediction & comparative-biochemical pathway analysis of these essential proteins gives a list of apicoplast-associated proteins having unique pathogen-specific metabolic pathway. These apicoplast-associated enzymes involved in fatty acid biosynthesis pathway of Toxoplasma gondii ME49, may be used as potential drug targets, as the pathway is vital for the protozoan's survival. Structure prediction of drug target proteins was done using fold based recognition method. Screening of the functional inhibitors against these novel targets may result in discovery of novel therapeutic compounds that can be effective against Toxoplasma gondii ME49. ABBREVIATIONS: DEG - Database of Essential Gene, KEGG - Kyoto Encyclopaedia of Genes and Genomes, KAAS - KEGG Automated Annotation Server, PFP - Protein Function Prediction, COG - Cluster of Orthologous Genes.
PMID: 22347778 [PubMed - in process]
Identification of potential apicoplast associated therapeutic targets in human and animal pathogen Toxoplasma gondii ME49.
Saremy S, Boroujeni ME, Bhattacharjee B, Mittal V, Chatterjee J.
Abstract
Toxoplasma gondii ME49 is an obligatory intracellular apicomplexa parasite that causes toxoplasmosis in humans, domesticated and wild animals. Waterborne outbreaks of acute toxoplasmosis worldwide reinforce the transmission of Toxoplasma gondii ME49 to humans through contaminated water and may have a greater epidemiological impact than previously believed. In the quest for drug and vaccine target identification subtractive genomics involving subtraction between the host and pathogen genome has been implemented for enlisting essential pathogen specific proteins. Using this approach, our analysis on both human and Toxoplasma gondii ME49 reveals that out of 7987 protein coding sequences of the pathogen, 950 represent essential non human-homologous proteins. Subcellular localization prediction & comparative-biochemical pathway analysis of these essential proteins gives a list of apicoplast-associated proteins having unique pathogen-specific metabolic pathway. These apicoplast-associated enzymes involved in fatty acid biosynthesis pathway of Toxoplasma gondii ME49, may be used as potential drug targets, as the pathway is vital for the protozoan's survival. Structure prediction of drug target proteins was done using fold based recognition method. Screening of the functional inhibitors against these novel targets may result in discovery of novel therapeutic compounds that can be effective against Toxoplasma gondii ME49. ABBREVIATIONS: DEG - Database of Essential Gene, KEGG - Kyoto Encyclopaedia of Genes and Genomes, KAAS - KEGG Automated Annotation Server, PFP - Protein Function Prediction, COG - Cluster of Orthologous Genes.
PMID: 22347778 [PubMed - in process]
A Genetic Screen to Isolate Toxoplasma gondii Host-cell Egress Mutants
J Vis Exp. 2012 Feb 8;(60). pii: 3807. doi: 10.3791/3807.
A Genetic Screen to Isolate Toxoplasma gondii Host-cell Egress Mutants.
Coleman BI, Gubbels MJ.
Source
Department of Biology, Boston College.
Abstract
The widespread, obligate intracellular, protozoan parasite Toxoplasma gondii causes opportunistic disease in immuno-compromised patients and causes birth defects upon congenital infection. The lytic replication cycle is characterized by three stages: 1. active invasion of a nucleated host cell; 2. replication inside the host cell; 3. active egress from the host cell. The mechanism of egress is increasingly being appreciated as a unique, highly regulated process, which is still poorly understood at the molecular level. The signaling pathways underlying egress have been characterized through the use of pharmacological agents acting on different aspects of the pathways(1-5). As such, several independent triggers of egress have been identified which all converge on the release of intracellular Ca(2+), a signal that is also critical for host cell invasion(6-8). This insight informed a candidate gene approach which led to the identification of plant like calcium dependent protein kinase (CDPK) involved in egress(9). In addition, several recent breakthroughs in understanding egress have been made using (chemical) genetic approaches(10-12). To combine the wealth of pharmacological information with the increasing genetic accessibility of Toxoplasma we recently established a screen permitting the enrichment for parasite mutants with a defect in host cell egress(13). Although chemical mutagenesis using N-ethyl-N-nitrosourea (ENU) or ethyl methanesulfonate (EMS) has been used for decades in the study of Toxoplasma biology(11,14,15), only recently has genetic mapping of mutations underlying the phenotypes become routine(16-18). Furthermore, by generating temperature-sensitive mutants, essential processes can be dissected and the underlying genes directly identified. These mutants behave as wild-type under the permissive temperature (35 °C), but fail to proliferate at the restrictive temperature (40 °C) as a result of the mutation in question. Here we illustrate a new phenotypic screening method to isolate mutants with a temperature-sensitive egress phenotype(13). The challenge for egress screens is to separate egressed from non-egressed parasites, which is complicated by fast re-invasion and general stickiness of the parasites to host cells. A previously established egress screen was based on a cumbersome series of biotinylation steps to separate intracellular from extracellular parasites(11). This method also did not generate conditional mutants resulting in weak phenotypes. The method described here overcomes the strong attachment of egressing parasites by including a glycan competitor, dextran sulfate (DS), that prevents parasites from sticking to the host cell(19). Moreover, extracellular parasites are specifically killed off by pyrrolidine dithiocarbamate (PDTC), which leaves intracellular parasites unharmed(20). Therefore, with a new phenotypic screen to specifically isolate parasite mutants with defects in induced egress, the power of genetics can now be fully deployed to unravel the molecular mechanisms underlying host cell egress.
PMID: 22349295 [PubMed - in process]
A Genetic Screen to Isolate Toxoplasma gondii Host-cell Egress Mutants.
Coleman BI, Gubbels MJ.
Source
Department of Biology, Boston College.
Abstract
The widespread, obligate intracellular, protozoan parasite Toxoplasma gondii causes opportunistic disease in immuno-compromised patients and causes birth defects upon congenital infection. The lytic replication cycle is characterized by three stages: 1. active invasion of a nucleated host cell; 2. replication inside the host cell; 3. active egress from the host cell. The mechanism of egress is increasingly being appreciated as a unique, highly regulated process, which is still poorly understood at the molecular level. The signaling pathways underlying egress have been characterized through the use of pharmacological agents acting on different aspects of the pathways(1-5). As such, several independent triggers of egress have been identified which all converge on the release of intracellular Ca(2+), a signal that is also critical for host cell invasion(6-8). This insight informed a candidate gene approach which led to the identification of plant like calcium dependent protein kinase (CDPK) involved in egress(9). In addition, several recent breakthroughs in understanding egress have been made using (chemical) genetic approaches(10-12). To combine the wealth of pharmacological information with the increasing genetic accessibility of Toxoplasma we recently established a screen permitting the enrichment for parasite mutants with a defect in host cell egress(13). Although chemical mutagenesis using N-ethyl-N-nitrosourea (ENU) or ethyl methanesulfonate (EMS) has been used for decades in the study of Toxoplasma biology(11,14,15), only recently has genetic mapping of mutations underlying the phenotypes become routine(16-18). Furthermore, by generating temperature-sensitive mutants, essential processes can be dissected and the underlying genes directly identified. These mutants behave as wild-type under the permissive temperature (35 °C), but fail to proliferate at the restrictive temperature (40 °C) as a result of the mutation in question. Here we illustrate a new phenotypic screening method to isolate mutants with a temperature-sensitive egress phenotype(13). The challenge for egress screens is to separate egressed from non-egressed parasites, which is complicated by fast re-invasion and general stickiness of the parasites to host cells. A previously established egress screen was based on a cumbersome series of biotinylation steps to separate intracellular from extracellular parasites(11). This method also did not generate conditional mutants resulting in weak phenotypes. The method described here overcomes the strong attachment of egressing parasites by including a glycan competitor, dextran sulfate (DS), that prevents parasites from sticking to the host cell(19). Moreover, extracellular parasites are specifically killed off by pyrrolidine dithiocarbamate (PDTC), which leaves intracellular parasites unharmed(20). Therefore, with a new phenotypic screen to specifically isolate parasite mutants with defects in induced egress, the power of genetics can now be fully deployed to unravel the molecular mechanisms underlying host cell egress.
PMID: 22349295 [PubMed - in process]
Thursday, February 16, 2012
The Relationship Between Toxoplasma gondii Infection and Mood Disorders in the Third National Health and Nutrition Survey
Biol Psychiatry. 2012 Feb 9. [Epub ahead of print]
The Relationship Between Toxoplasma gondii Infection and Mood Disorders in the Third National Health and Nutrition Survey.
Pearce BD, Kruszon-Moran D, Jones JL.
Source
Department of Epidemiology, Emory University, Atlanta, Georgia.
Abstract
BACKGROUND:
Toxoplasma gondii (T. gondii) is a neurotropic protozoan parasite that causes persistent infection in humans. A substantial literature suggests that schizophrenia is associated with increased seroprevalence of T. gondii, but a possible link of the parasite with mood disorders has not been as thoroughly investigated.
METHODS:
We examined the association of Toxoplasma-specific immunoglobulin G results with mood disorder outcomes in 7440 respondents from the third National Health and Nutrition Survey, which is a nationally representative sample of the United States noninstitutionalized civilian population. Regression models were adjusted for numerous potential confounders, including tobacco smoking and C-reactive protein levels.
RESULTS:
No statistically significant associations were found between T. gondii seroprevalence and a history of major depression (n = 574; adjusted odds ratio [OR]: .8; 95% confidence interval [CI]: .5-1.2), severe major depression (n = 515; adjusted OR: .8; 95% CI: .6-1.2), dysthymia (n = 548; adjusted OR: 1.1; 95% CI: .7-1.8), or dysthymia with comorbid major depression (n = 242, adjusted OR: 1.2; 95% CI: .6-2.4), all p values were > .05, including analysis stratified by gender. However, there was a significant relationship between T. gondii seroprevalence and bipolar disorder type I for respondents in which both manic and major depression symptoms were reported (n = 41; adjusted OR: 2.4; 95% CI: 1.2-4.8; p < .05).
CONCLUSIONS:
In a population-based sample, T. gondii seroprevalence is not elevated in unipolar mood disorders but is higher in a subset of respondents with a history of bipolar disorder type 1.
Copyright © 2012 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
PMID: 22325983 [PubMed - as supplied by publisher]
The Relationship Between Toxoplasma gondii Infection and Mood Disorders in the Third National Health and Nutrition Survey.
Pearce BD, Kruszon-Moran D, Jones JL.
Source
Department of Epidemiology, Emory University, Atlanta, Georgia.
Abstract
BACKGROUND:
Toxoplasma gondii (T. gondii) is a neurotropic protozoan parasite that causes persistent infection in humans. A substantial literature suggests that schizophrenia is associated with increased seroprevalence of T. gondii, but a possible link of the parasite with mood disorders has not been as thoroughly investigated.
METHODS:
We examined the association of Toxoplasma-specific immunoglobulin G results with mood disorder outcomes in 7440 respondents from the third National Health and Nutrition Survey, which is a nationally representative sample of the United States noninstitutionalized civilian population. Regression models were adjusted for numerous potential confounders, including tobacco smoking and C-reactive protein levels.
RESULTS:
No statistically significant associations were found between T. gondii seroprevalence and a history of major depression (n = 574; adjusted odds ratio [OR]: .8; 95% confidence interval [CI]: .5-1.2), severe major depression (n = 515; adjusted OR: .8; 95% CI: .6-1.2), dysthymia (n = 548; adjusted OR: 1.1; 95% CI: .7-1.8), or dysthymia with comorbid major depression (n = 242, adjusted OR: 1.2; 95% CI: .6-2.4), all p values were > .05, including analysis stratified by gender. However, there was a significant relationship between T. gondii seroprevalence and bipolar disorder type I for respondents in which both manic and major depression symptoms were reported (n = 41; adjusted OR: 2.4; 95% CI: 1.2-4.8; p < .05).
CONCLUSIONS:
In a population-based sample, T. gondii seroprevalence is not elevated in unipolar mood disorders but is higher in a subset of respondents with a history of bipolar disorder type 1.
Copyright © 2012 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
PMID: 22325983 [PubMed - as supplied by publisher]
Sunday, February 12, 2012
The Use and Abuse of Haem in Apicomplexan Parasites
Antioxid Redox Signal. 2012 Feb 9. [Epub ahead of print]
The Use and Abuse of Haem in Apicomplexan Parasites.
van Dooren G, Kennedy A, McFadden G.
Source
Australian National University, Research School of Biology, Building 134, Linnaeus Way, Canberra, Australian Capital Territory, Australia, 0200, +61-2-61250665, +61-2-61250313; giel.vandooren@anu.edu.au.
Abstract
Significance. Haem is an essential prosthetic group for most life on Earth. It functions in numerous cellular redox reactions, including in antioxidant defences and at several stages of the electron transport chain in prokaryotes and eukaryotic mitochondria. Haem also functions as a sensor and transport molecule for gases such as oxygen. Haem is a complex organic molecule and can only be synthesised through a multi-enzyme pathway from simpler precursors. Most free-living organisms synthesise their own haem by a broadly conserved metabolic pathway. Parasites are adept at scavenging molecules from their hosts, and haem is no exception. Recent Advances. In this review we examine recent advances in understanding haem usage and acquisition in Apicomplexa, a group of parasites that include the causative agents of malaria, toxoplasmosis and several major parasites of livestock. Critical Issues. Haem is critical to the survival of Apicomplexa, although the functions of haem in these organisms remain poorly understood. Some Apicomplexa likely scavenge haem from their host organisms, while others retain the ability to synthesise haem. Surprisingly, some Apicomplexa may be able to both synthesise and scavenge haem. Several Apicomplexa live in intracellular environments that contain high levels of haem. Since haem is toxic at high concentrations, parasites must carefully regulate intracellular haem levels and develop mechanisms to detoxify excess haem. Indeed, drugs interfering with haem detoxification serve as major antimalarials. Future Directions. Understanding haem requirements and regulation in apicomplexan parasites promises to reveal multiple targets for much-needed therapeutic intervention against these parasites.
PMID: 22320355 [PubMed - as supplied by publisher]
The Use and Abuse of Haem in Apicomplexan Parasites.
van Dooren G, Kennedy A, McFadden G.
Source
Australian National University, Research School of Biology, Building 134, Linnaeus Way, Canberra, Australian Capital Territory, Australia, 0200, +61-2-61250665, +61-2-61250313; giel.vandooren@anu.edu.au.
Abstract
Significance. Haem is an essential prosthetic group for most life on Earth. It functions in numerous cellular redox reactions, including in antioxidant defences and at several stages of the electron transport chain in prokaryotes and eukaryotic mitochondria. Haem also functions as a sensor and transport molecule for gases such as oxygen. Haem is a complex organic molecule and can only be synthesised through a multi-enzyme pathway from simpler precursors. Most free-living organisms synthesise their own haem by a broadly conserved metabolic pathway. Parasites are adept at scavenging molecules from their hosts, and haem is no exception. Recent Advances. In this review we examine recent advances in understanding haem usage and acquisition in Apicomplexa, a group of parasites that include the causative agents of malaria, toxoplasmosis and several major parasites of livestock. Critical Issues. Haem is critical to the survival of Apicomplexa, although the functions of haem in these organisms remain poorly understood. Some Apicomplexa likely scavenge haem from their host organisms, while others retain the ability to synthesise haem. Surprisingly, some Apicomplexa may be able to both synthesise and scavenge haem. Several Apicomplexa live in intracellular environments that contain high levels of haem. Since haem is toxic at high concentrations, parasites must carefully regulate intracellular haem levels and develop mechanisms to detoxify excess haem. Indeed, drugs interfering with haem detoxification serve as major antimalarials. Future Directions. Understanding haem requirements and regulation in apicomplexan parasites promises to reveal multiple targets for much-needed therapeutic intervention against these parasites.
PMID: 22320355 [PubMed - as supplied by publisher]
Development of Toxoplasma gondii Calcium-Dependent Protein Kinase 1 (TgCDPK1) Inhibitors with Potent Anti-Toxoplasma Activity
J Med Chem. 2012 Feb 9. [Epub ahead of print]
Development of Toxoplasma gondii Calcium-Dependent Protein Kinase 1 (TgCDPK1) Inhibitors with Potent Anti-Toxoplasma Activity.
Johnson SM, Murphy RC, Geiger JA, Derocher A, Zhang Z, Ojo K, Larson E, Perera BG, Dale E, He P, Fox A, Mueller N, Merritt EA, Fan E, Reid M, Parsons M, Van Voorhis WC, Maly DJ.
Abstract
Toxoplasmosis is a disease of prominent health concern that is caused by the protozoan parasite, Toxoplasma gondii. Proliferation of T. gondii is dependent on its ability to invade host cells, which is mediated, in part, by calcium-dependent protein kinase 1 (CDPK1). We have developed ATP competitive inhibitors of TgCDPK1 that block invasion of parasites into host cells, preventing their proliferation. The presence of a unique glycine gatekeeper residue in TgCDPK1 permits selective inhibition of the parasite enzyme over human kinases. These potent TgCDPK1 inhibitors do not inhibit the growth of human cell lines and represent promising candidates as toxoplasmosis therapeutics.
PMID: 22320388 [PubMed - as supplied by publisher]
Development of Toxoplasma gondii Calcium-Dependent Protein Kinase 1 (TgCDPK1) Inhibitors with Potent Anti-Toxoplasma Activity.
Johnson SM, Murphy RC, Geiger JA, Derocher A, Zhang Z, Ojo K, Larson E, Perera BG, Dale E, He P, Fox A, Mueller N, Merritt EA, Fan E, Reid M, Parsons M, Van Voorhis WC, Maly DJ.
Abstract
Toxoplasmosis is a disease of prominent health concern that is caused by the protozoan parasite, Toxoplasma gondii. Proliferation of T. gondii is dependent on its ability to invade host cells, which is mediated, in part, by calcium-dependent protein kinase 1 (CDPK1). We have developed ATP competitive inhibitors of TgCDPK1 that block invasion of parasites into host cells, preventing their proliferation. The presence of a unique glycine gatekeeper residue in TgCDPK1 permits selective inhibition of the parasite enzyme over human kinases. These potent TgCDPK1 inhibitors do not inhibit the growth of human cell lines and represent promising candidates as toxoplasmosis therapeutics.
PMID: 22320388 [PubMed - as supplied by publisher]
Thursday, February 09, 2012
Animal Models for Toxoplasma gondii Infection
Curr Protoc Immunol. 2012 Feb;Chapter 19:Unit19.3.
Animal Models for Toxoplasma gondii Infection.
Subauste C.
Source
Case Western Reserve University School of Medicine, Cleveland, Ohio.
Abstract
Toxoplasma gondii is a protozoan of worldwide distribution. This unit describes murine models of acute T. gondii infection, toxoplasmic encephalitis, and Toxoplasma retinochoroiditis. T. gondii infection in SCID mice allows the study of T cell-independent mechanisms of defense. The uracil auxotroph strain cps1-1 and temperature-sensitive mutant strains of T. gondii allow studies of immunization and adoptive transfer. In vivo study of parasite host-interaction is possible with the use of parasites that express fluorescent proteins and model antigens, plus the use of transgenic mice that express the appropriate T cell receptor and fluorescently labeled leukocytes. Parasites that express bioluminescent markers make it possible to study the dynamics of infection in real time using bioluminescence imaging. Support protocols present methodology for evaluation of progression of infection and immune response to the parasite, the maintenance of T. gondii tissue cysts and tachyzoites, as well as preparation of T. gondii lysate antigens. Curr. Protoc. Immunol. 96:19.3.1-19.3.23. © 2012 by John Wiley & Sons, Inc.
PMID: 22314833 [PubMed - in process]
Animal Models for Toxoplasma gondii Infection.
Subauste C.
Source
Case Western Reserve University School of Medicine, Cleveland, Ohio.
Abstract
Toxoplasma gondii is a protozoan of worldwide distribution. This unit describes murine models of acute T. gondii infection, toxoplasmic encephalitis, and Toxoplasma retinochoroiditis. T. gondii infection in SCID mice allows the study of T cell-independent mechanisms of defense. The uracil auxotroph strain cps1-1 and temperature-sensitive mutant strains of T. gondii allow studies of immunization and adoptive transfer. In vivo study of parasite host-interaction is possible with the use of parasites that express fluorescent proteins and model antigens, plus the use of transgenic mice that express the appropriate T cell receptor and fluorescently labeled leukocytes. Parasites that express bioluminescent markers make it possible to study the dynamics of infection in real time using bioluminescence imaging. Support protocols present methodology for evaluation of progression of infection and immune response to the parasite, the maintenance of T. gondii tissue cysts and tachyzoites, as well as preparation of T. gondii lysate antigens. Curr. Protoc. Immunol. 96:19.3.1-19.3.23. © 2012 by John Wiley & Sons, Inc.
PMID: 22314833 [PubMed - in process]
Toxoplasma gondii invasion and replication in astrocyte primary cultures and astrocytoma cell lines: systematic review of the literature
Parasitol Res. 2012 Feb 8. [Epub ahead of print]
Toxoplasma gondii invasion and replication in astrocyte primary cultures and astrocytoma cell lines: systematic review of the literature.
Contreras-Ochoa CO, Lagunas-Martínez A, Belkind-Gerson J, Correa D.
Source
Centro de Investigación sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad no. 655, Colonia Santa María Ahuacatitlán, cerrada los Pinos y Caminera, Cuernavaca, Morelos, CP 62100, Mexico, ccontreras@insp.mx.
Abstract
Toxoplasma gondii is a cosmopolitan protozoan which infects all homoeothermic species, including humans. This parasite may cause severe neurological problems in congenitally infected newborns or immunocompromised individuals, but it also provokes psychiatric and neurological disorders as well as behavioural and sensory deficit. There is controversy regarding the effect of T. gondii upon astrocytes, which may serve as parasite proliferation recipients or protective immune response activators within the central nervous system. This apparent contradiction could partially be due to the infection degree obtained in the different experiments reported. Thus, we decided to systematically review the in vitro models used to study these phenomena. Fifteen articles from which direct invasion and replication data could be gathered were found. Very heterogeneous results emerged, mainly due to diversity of models in relation to parasite strain (virulence), host species, parasite dose and evaluation times after infection. Also, the results were measured in diverse ways, i.e. some reported percent infected cells, while others informed parasites per vacuole or cell, or parasitic vacuoles per cell. Very few conclusions could be drawn, among them that human astrocytoma cell lines and mouse astrocytes seem more susceptible to infection and less resistant to tachyzoite proliferation than human primary culture astrocytes. The present study supports the need to reanalyse T. gondii astrocyte invasion and replication processes, especially with the use of actual technology, which allows detailed mechanistic studies.
PMID: 22314782 [PubMed - as supplied by publisher]
Toxoplasma gondii invasion and replication in astrocyte primary cultures and astrocytoma cell lines: systematic review of the literature.
Contreras-Ochoa CO, Lagunas-Martínez A, Belkind-Gerson J, Correa D.
Source
Centro de Investigación sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad no. 655, Colonia Santa María Ahuacatitlán, cerrada los Pinos y Caminera, Cuernavaca, Morelos, CP 62100, Mexico, ccontreras@insp.mx.
Abstract
Toxoplasma gondii is a cosmopolitan protozoan which infects all homoeothermic species, including humans. This parasite may cause severe neurological problems in congenitally infected newborns or immunocompromised individuals, but it also provokes psychiatric and neurological disorders as well as behavioural and sensory deficit. There is controversy regarding the effect of T. gondii upon astrocytes, which may serve as parasite proliferation recipients or protective immune response activators within the central nervous system. This apparent contradiction could partially be due to the infection degree obtained in the different experiments reported. Thus, we decided to systematically review the in vitro models used to study these phenomena. Fifteen articles from which direct invasion and replication data could be gathered were found. Very heterogeneous results emerged, mainly due to diversity of models in relation to parasite strain (virulence), host species, parasite dose and evaluation times after infection. Also, the results were measured in diverse ways, i.e. some reported percent infected cells, while others informed parasites per vacuole or cell, or parasitic vacuoles per cell. Very few conclusions could be drawn, among them that human astrocytoma cell lines and mouse astrocytes seem more susceptible to infection and less resistant to tachyzoite proliferation than human primary culture astrocytes. The present study supports the need to reanalyse T. gondii astrocyte invasion and replication processes, especially with the use of actual technology, which allows detailed mechanistic studies.
PMID: 22314782 [PubMed - as supplied by publisher]
Toxoplasma gondii immune mapped protein-1 (TgIMP1) is a novel vaccine candidate against toxoplasmosis
Vaccine. 2012 Feb 3. [Epub ahead of print]
Toxoplasma gondii immune mapped protein-1 (TgIMP1) is a novel vaccine candidate against toxoplasmosis.
Cui X, Lei T, Yang D, Hao P, Li B, Liu Q.
Source
Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
Abstract
Immune mapped protein1 (IMP1) is a new protective protein in apicomplexan parasites, and exists in Toxoplasma gondii. In the present study, a DNA vaccine expressing IMP1 of T. gondii was constructed and the immune response induced in BALB/c mice was evaluated. The coding sequence of IMP1 was inserted into the eukaryotic expression vector pcDNA 3.1(+), resulting a recombinant plasmid pcDNA-IMP1, which was used to immunize BALB/c mice intramuscularly. After immunization, the immune response was evaluated using lymphoproliferative assay, and cytokine and antibody measurements. The mice were challenged with tachyzoites of the virulent T. gondii RH strain 14th day after the last immunization to observe the survival time. The results showed that the group immunized with pcDNA-IMP1 developed a high level of specific antibody responses against Escherichia coli expressed recombinant TgIMP1, with high IgG antibody titers, predominance of IgG2a production, a strong lymphoproliferative response, and significant levels of IFN-γ, IL-2, IL-4 and IL-10 production compared with the control groups. These results demonstrate that pcDNA-IMP1 could elicit strong humoral and Th1 immune responses. Immunized mice showed a significantly (15.8±6 days) prolonged survival time compared with control mice, which died within 7 days of challenge infection. These results suggest that IMP1 is a promising vaccine candidate against toxoplasmosis.
Copyright © 2012. Published by Elsevier Ltd.
PMID: 22310204 [PubMed - as supplied by publisher]
Toxoplasma gondii immune mapped protein-1 (TgIMP1) is a novel vaccine candidate against toxoplasmosis.
Cui X, Lei T, Yang D, Hao P, Li B, Liu Q.
Source
Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
Abstract
Immune mapped protein1 (IMP1) is a new protective protein in apicomplexan parasites, and exists in Toxoplasma gondii. In the present study, a DNA vaccine expressing IMP1 of T. gondii was constructed and the immune response induced in BALB/c mice was evaluated. The coding sequence of IMP1 was inserted into the eukaryotic expression vector pcDNA 3.1(+), resulting a recombinant plasmid pcDNA-IMP1, which was used to immunize BALB/c mice intramuscularly. After immunization, the immune response was evaluated using lymphoproliferative assay, and cytokine and antibody measurements. The mice were challenged with tachyzoites of the virulent T. gondii RH strain 14th day after the last immunization to observe the survival time. The results showed that the group immunized with pcDNA-IMP1 developed a high level of specific antibody responses against Escherichia coli expressed recombinant TgIMP1, with high IgG antibody titers, predominance of IgG2a production, a strong lymphoproliferative response, and significant levels of IFN-γ, IL-2, IL-4 and IL-10 production compared with the control groups. These results demonstrate that pcDNA-IMP1 could elicit strong humoral and Th1 immune responses. Immunized mice showed a significantly (15.8±6 days) prolonged survival time compared with control mice, which died within 7 days of challenge infection. These results suggest that IMP1 is a promising vaccine candidate against toxoplasmosis.
Copyright © 2012. Published by Elsevier Ltd.
PMID: 22310204 [PubMed - as supplied by publisher]
PRMT1 methylates the single Argonaute of Toxoplasma gondii and is important for the recruitment of Tudor nuclease for target RNA cleavage
Cell Microbiol. 2012 Feb 6. doi: 10.1111/j.1462-5822.2012.01763.x. [Epub ahead of print]
PRMT1 methylates the single Argonaute of Toxoplasma gondii and is important for the recruitment of Tudor nuclease for target RNA cleavage by antisense guide RNA.
Musiyenko A, Majumdar T, Andrews J, Adams B, Barik S.
Source
Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA. Center for Gene Regulation in Health and Disease, and Department of Biological, Geological and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Ave., Cleveland, Ohio 44115, USA.
Abstract
Argonaute (Ago) plays a central role in RNA interference in metazoans, but its status in lower organisms remains ill-defined. We report on the Ago complex of the unicellular protozoan, Toxoplasma gondii (Tg), an obligatory pathogen of mammalian hosts. The PIWI-like domain of TgAgo lacked the canonical DDE/H catalytic triad, explaining its weak target RNA cleavage activity. However, TgAgo associated with a stronger RNA slicer, a Tudor staphylococcal nuclease (TSN), and with a protein Arg methyl transferase, PRMT1. Mutational analysis suggested that the N-terminal RGG-repeat domain of TgAgo was methylated by PRMT1, correlating with the recruitment of TSN. The slicer activity of TgAgo was Mg(+2) -dependent and required perfect complementarity between the guide RNA and the target. In contrast, the TSN activity was Ca(+2) -dependent and required an imperfectly paired guide RNA. Ago knockout parasites showed essentially normal growth, but in contrast, the PRMT1 knockouts grew abnormally. Chemical inhibition of Arg methylation also had an anti-parasitic effect. These results suggest that the parasitic PRMT1 plays multiple roles, and its loss affects the recruitment of a more potent second slicer to the paras. © 2012 Blackwell Publishing Ltd.
© 2012 Blackwell Publishing Ltd.
PMID: 22309152 [PubMed - as supplied by publisher]
PRMT1 methylates the single Argonaute of Toxoplasma gondii and is important for the recruitment of Tudor nuclease for target RNA cleavage by antisense guide RNA.
Musiyenko A, Majumdar T, Andrews J, Adams B, Barik S.
Source
Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA. Center for Gene Regulation in Health and Disease, and Department of Biological, Geological and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Ave., Cleveland, Ohio 44115, USA.
Abstract
Argonaute (Ago) plays a central role in RNA interference in metazoans, but its status in lower organisms remains ill-defined. We report on the Ago complex of the unicellular protozoan, Toxoplasma gondii (Tg), an obligatory pathogen of mammalian hosts. The PIWI-like domain of TgAgo lacked the canonical DDE/H catalytic triad, explaining its weak target RNA cleavage activity. However, TgAgo associated with a stronger RNA slicer, a Tudor staphylococcal nuclease (TSN), and with a protein Arg methyl transferase, PRMT1. Mutational analysis suggested that the N-terminal RGG-repeat domain of TgAgo was methylated by PRMT1, correlating with the recruitment of TSN. The slicer activity of TgAgo was Mg(+2) -dependent and required perfect complementarity between the guide RNA and the target. In contrast, the TSN activity was Ca(+2) -dependent and required an imperfectly paired guide RNA. Ago knockout parasites showed essentially normal growth, but in contrast, the PRMT1 knockouts grew abnormally. Chemical inhibition of Arg methylation also had an anti-parasitic effect. These results suggest that the parasitic PRMT1 plays multiple roles, and its loss affects the recruitment of a more potent second slicer to the paras. © 2012 Blackwell Publishing Ltd.
© 2012 Blackwell Publishing Ltd.
PMID: 22309152 [PubMed - as supplied by publisher]
Wednesday, February 01, 2012
Brain cancer mortality rates increase with Toxoplasma gondii seroprevalence in France
Infect Genet Evol. 2012 Jan 25. [Epub ahead of print]
Brain cancer mortality rates increase with Toxoplasma gondii seroprevalence in France.
Vittecoq M, Elguero E, Lafferty K, Roche B, Brodeur J, Gauthier-Clerc M, Missé D, Thomas F.
Source
IRD, MIVEGEC (UMR CNRS/IRD/UM1), 911 Ave. Agropolis, BP 64501, FR-34394 Montpellier Cedex 5, France; Centre de Recherche de la Tour du Valat, Le Sambuc, 13200 Arles, France.
Abstract
The incidence of adult brain cancer was shown to be higher in countries where the parasite Toxoplasma gondii is common, suggesting that this brain protozoan could potentially increase the risk of tumor formation. Using countries as replicates has, however, several potential confounding factors, particularly because detection rates vary with country wealth. Using an independent dataset entirely within France, we further establish the significance of the association between T. gondii and brain cancer and find additional demographic resolution. In adult age classes 55years and older, regional mortality rates due to brain cancer correlated positively with the local seroprevalence of T. gondii. This effect was particularly strong for men. While this novel evidence of a significant statistical association between T. gondii infection and brain cancer does not demonstrate causation, these results suggest that investigations at the scale of the individual are merited.
Copyright © 2012. Published by Elsevier B.V.
PMID: 22285308 [PubMed - as supplied by publisher
Brain cancer mortality rates increase with Toxoplasma gondii seroprevalence in France.
Vittecoq M, Elguero E, Lafferty K, Roche B, Brodeur J, Gauthier-Clerc M, Missé D, Thomas F.
Source
IRD, MIVEGEC (UMR CNRS/IRD/UM1), 911 Ave. Agropolis, BP 64501, FR-34394 Montpellier Cedex 5, France; Centre de Recherche de la Tour du Valat, Le Sambuc, 13200 Arles, France.
Abstract
The incidence of adult brain cancer was shown to be higher in countries where the parasite Toxoplasma gondii is common, suggesting that this brain protozoan could potentially increase the risk of tumor formation. Using countries as replicates has, however, several potential confounding factors, particularly because detection rates vary with country wealth. Using an independent dataset entirely within France, we further establish the significance of the association between T. gondii and brain cancer and find additional demographic resolution. In adult age classes 55years and older, regional mortality rates due to brain cancer correlated positively with the local seroprevalence of T. gondii. This effect was particularly strong for men. While this novel evidence of a significant statistical association between T. gondii infection and brain cancer does not demonstrate causation, these results suggest that investigations at the scale of the individual are merited.
Copyright © 2012. Published by Elsevier B.V.
PMID: 22285308 [PubMed - as supplied by publisher
Apicoplast targeting of a T. gondii transmembrane protein requires a cytosolic tyrosine-based motif
Traffic. 2012 Jan 30. doi: 10.1111/j.1600-0854.2012.01335.x. [Epub ahead of print]
Apicoplast targeting of a T. gondii transmembrane protein requires a cytosolic tyrosine-based motif.
Derocher AE, Karnataki A, Vaney P, Parsons M.
Source
Seattle Biomedical Research Institute, 307 Westlake Ave N, Seattle Washington 98109-5219 University of Washington, Department of Global Health, Seattle Washington 98195-5065.
Abstract
Toxoplasma gondii, like most apicomplexan parasites, possesses an essential relict chloroplast, the apicoplast. Several apicoplast membrane proteins lack the bipartite targeting sequences of luminal proteins. Vesicles bearing these membrane proteins are detected during apicoplast enlargement, but the means of cargo selection remains obscure. We used a combination of deletion mutagenesis, point mutations, and protein chimeras to identify a short motif prior to the first transmembrane domain of the T. gondii apicoplast phosphate transporter 1 (APT1) that is necessary for apicoplast trafficking. Tyrosine 16 was essential for proper localization; any substitution resulted in misdirection of APT1 to the Golgi body. Glycine 17 was also important, with significant Golgi body accumulation in the alanine mutant. Separation of at least eight amino acids from the transmembrane domain was required for full motif function. Similarly placed YG motifs are present in apicomplexan APT1 orthologues and the corresponding N-terminal domain from Plasmodium vivax was able to route T. gondii APT1 to the apicoplast. Differential permeabilization demonstrated that both the N- and C- termini of APT1 are exposed to the cytosol. We propose that this YG motif facilitates APT1 trafficking via interactions that occur on the cytosolic face of nascent vesicles destined for the apicoplast.
© 2012 John Wiley & Sons A/S.
PMID: 22288938 [PubMed - as supplied by publisher]
Apicoplast targeting of a T. gondii transmembrane protein requires a cytosolic tyrosine-based motif.
Derocher AE, Karnataki A, Vaney P, Parsons M.
Source
Seattle Biomedical Research Institute, 307 Westlake Ave N, Seattle Washington 98109-5219 University of Washington, Department of Global Health, Seattle Washington 98195-5065.
Abstract
Toxoplasma gondii, like most apicomplexan parasites, possesses an essential relict chloroplast, the apicoplast. Several apicoplast membrane proteins lack the bipartite targeting sequences of luminal proteins. Vesicles bearing these membrane proteins are detected during apicoplast enlargement, but the means of cargo selection remains obscure. We used a combination of deletion mutagenesis, point mutations, and protein chimeras to identify a short motif prior to the first transmembrane domain of the T. gondii apicoplast phosphate transporter 1 (APT1) that is necessary for apicoplast trafficking. Tyrosine 16 was essential for proper localization; any substitution resulted in misdirection of APT1 to the Golgi body. Glycine 17 was also important, with significant Golgi body accumulation in the alanine mutant. Separation of at least eight amino acids from the transmembrane domain was required for full motif function. Similarly placed YG motifs are present in apicomplexan APT1 orthologues and the corresponding N-terminal domain from Plasmodium vivax was able to route T. gondii APT1 to the apicoplast. Differential permeabilization demonstrated that both the N- and C- termini of APT1 are exposed to the cytosol. We propose that this YG motif facilitates APT1 trafficking via interactions that occur on the cytosolic face of nascent vesicles destined for the apicoplast.
© 2012 John Wiley & Sons A/S.
PMID: 22288938 [PubMed - as supplied by publisher]
Inhibition of ATF6β-dependent host adaptive immune response by a Toxoplasma virulence factor ROP18
Virulence. 2012 Jan 1;3(1). [Epub ahead of print]
Inhibition of ATF6β-dependent host adaptive immune response by a Toxoplasma virulence factor ROP18.
Yamamoto M, Takeda K.
Source
Department of Microbiology and Immunology; Graduate School of Medicine; and Laboratory of Mucosal Immunology; WPI Immunology Frontier Research Center; Osaka University; Suita, Osaka Japan.
Abstract
Toxoplasma gondii (T. gondii) secretes various effector molecules, which co-opt host cells and enable parasite proliferation. Of these, the rhoptry protein, ROP18, is a parasite-derived factor that determines acute virulence. ROP18 is injected into the host cytoplasm during infection and, eventually, localizes to parasitophorous vacuole (PV) membranes. ROP18 is predicted to be a serine/threonine kinase; however, the molecular mechanism by which ROP18 mediates its pathological effects remains unclear. At the end of 2010, two groups reported that ROP18 targets and phosphorylates interferon-inducible p47 small GTPases (IRGs), demonstrating the parasite's strategy for disarming the innate defense system. Recently, we described a mechanism by which ROP18 mediates degradation of the host endoplasmic reticulum-localizing transcription factor, ATF6β, to downregulate CD8 T cell-mediated type I adaptive immune responses. Taken together, these results suggest that T. gondii inactivates host innate and adaptive immune responses by targeting different host immunity-related molecules: IRGs and ATF6β.
PMID: 22286708 [PubMed - as supplied by publisher]
Inhibition of ATF6β-dependent host adaptive immune response by a Toxoplasma virulence factor ROP18.
Yamamoto M, Takeda K.
Source
Department of Microbiology and Immunology; Graduate School of Medicine; and Laboratory of Mucosal Immunology; WPI Immunology Frontier Research Center; Osaka University; Suita, Osaka Japan.
Abstract
Toxoplasma gondii (T. gondii) secretes various effector molecules, which co-opt host cells and enable parasite proliferation. Of these, the rhoptry protein, ROP18, is a parasite-derived factor that determines acute virulence. ROP18 is injected into the host cytoplasm during infection and, eventually, localizes to parasitophorous vacuole (PV) membranes. ROP18 is predicted to be a serine/threonine kinase; however, the molecular mechanism by which ROP18 mediates its pathological effects remains unclear. At the end of 2010, two groups reported that ROP18 targets and phosphorylates interferon-inducible p47 small GTPases (IRGs), demonstrating the parasite's strategy for disarming the innate defense system. Recently, we described a mechanism by which ROP18 mediates degradation of the host endoplasmic reticulum-localizing transcription factor, ATF6β, to downregulate CD8 T cell-mediated type I adaptive immune responses. Taken together, these results suggest that T. gondii inactivates host innate and adaptive immune responses by targeting different host immunity-related molecules: IRGs and ATF6β.
PMID: 22286708 [PubMed - as supplied by publisher]
Toxoplasma gondii infection inhibits Th17-mediated spontaneous development of arthritis in IL-1 receptor antagonist-deficient mice
Infect Immun. 2012 Jan 30. [Epub ahead of print]
Toxoplasma gondii infection inhibits Th17-mediated spontaneous development of arthritis in IL-1 receptor antagonist-deficient mice.
Washino T, Moroda M, Iwakura Y, Aosai F.
Source
Department of Infection and Host Defense, Chiba University Graduate School of Medicine, 1-8-1 Inohana Chuo-ku, Chiba 260-8670, Japan.
Abstract
IL-1 receptor antagonist (IL-1Ra)-deficient BALB/c mice develop spontaneous arthritis resembling human rheumatoid arthritis. We herein report that infection with Toxoplasma gondii, an intracellular protozoan, is capable of ameliorating the spontaneous development of arthritis in IL-1Ra-deficient mice. The onset of arthritis development was delayed and the severity score of arthritis was significantly suppressed in T. gondii-infected mice. Expression of IL-12p40 mRNA from CD11c(+) cells of mesenteric lymph nodes (mLN) and spleen markedly increased at 1 week after peroral infection. While CD11c(+) cells also produced IL-10, IL-1β and IL-6, CD4(+) T cells from T. gondii-infected mice expressed significantly high levels of T-bet and IFN- γ mRNA at both mLN and spleen. Levels of GATA-3/IL-4 mRNA or RORγt/IL-17 mRNA decreased in the infected mice, indicating Th1 polarization and the reduction of Th2 and Th17 polarization. The severity of arthritis was related to Th1 polarization accompanied with Th17 reduction, demonstrating the protective role of T. gondii-derived Th1 response against Th17-mediated arthritis in IL-1Ra-deficient mice.
PMID: 22290145 [PubMed - as supplied by publisher]
Toxoplasma gondii infection inhibits Th17-mediated spontaneous development of arthritis in IL-1 receptor antagonist-deficient mice.
Washino T, Moroda M, Iwakura Y, Aosai F.
Source
Department of Infection and Host Defense, Chiba University Graduate School of Medicine, 1-8-1 Inohana Chuo-ku, Chiba 260-8670, Japan.
Abstract
IL-1 receptor antagonist (IL-1Ra)-deficient BALB/c mice develop spontaneous arthritis resembling human rheumatoid arthritis. We herein report that infection with Toxoplasma gondii, an intracellular protozoan, is capable of ameliorating the spontaneous development of arthritis in IL-1Ra-deficient mice. The onset of arthritis development was delayed and the severity score of arthritis was significantly suppressed in T. gondii-infected mice. Expression of IL-12p40 mRNA from CD11c(+) cells of mesenteric lymph nodes (mLN) and spleen markedly increased at 1 week after peroral infection. While CD11c(+) cells also produced IL-10, IL-1β and IL-6, CD4(+) T cells from T. gondii-infected mice expressed significantly high levels of T-bet and IFN- γ mRNA at both mLN and spleen. Levels of GATA-3/IL-4 mRNA or RORγt/IL-17 mRNA decreased in the infected mice, indicating Th1 polarization and the reduction of Th2 and Th17 polarization. The severity of arthritis was related to Th1 polarization accompanied with Th17 reduction, demonstrating the protective role of T. gondii-derived Th1 response against Th17-mediated arthritis in IL-1Ra-deficient mice.
PMID: 22290145 [PubMed - as supplied by publisher]
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