Trends Parasitol. 2012 Jul 18. [Epub ahead of print]
Autophagy in Apicomplexa: a life sustaining death mechanism?
Sinai AP, Roepe PD.
Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40526, USA.
Programmed cell death (PCD) pathways remain understudied in parasitic protozoa in spite of the fact that they provide potential targets for the development of new therapy. The best understood PCD pathway in higher eukaryotes is apoptosis although emerging evidence also points to autophagy as a mediator of death in certain physiological contexts. Bioinformatic analyses coupled with biochemical and cell biological studies suggest that parasitic protozoa possess the capacity for PCD including a primordial form of apoptosis. Recent work in Toxoplasma and emerging data from Plasmodium suggest that autophagy-related processes may serve as an additional death promoting pathway in Apicomplexa. Detailed mechanistic studies into the molecular basis for PCD in parasitic protozoa represent a fertile area for investigation and drug development.
PMID: 22819059 [PubMed - as supplied by publisher]
Tuesday, July 24, 2012
Slower postnatal motor development in infants of mothers with latent toxoplasmosis during the first 18months of life
Early Hum Dev. 2012 Jul 18. [Epub ahead of print]
Slower postnatal motor development in infants of mothers with latent toxoplasmosis during the first 18months of life
Kaňková S, Sulc J, Křivohlavá R, Kuběna A, Flegr J.
Department of Philosophy and History of Science, Faculty of Science, Charles University in Prague, CZ-128 44 Prague 2, Czech Republic.
Toxoplasmosis, a zoonosis caused by a protozoan, Toxoplasma gondii, is probably the most widespread human parasitosis in developed countries. Pregnant women with latent toxoplasmosis have seemingly younger fetuses especially in the 16th week of gestation, which suggests that fetuses of Toxoplasma-infected mothers have slower rates of development in the first trimester of pregnancy. In the present retrospective cohort study, we analyzed data on postnatal motor development of infants from 331 questionnaire respondents including 53 Toxoplasma-infected mothers to search for signs of early postnatal development disorders. During the first year of life, a slower postnatal motor development was observed in infants of mothers with latent toxoplasmosis. These infants significantly later developed the ability to control the head position (p=0.039), to roll from supine to prone position (p=0.022) and were slightly later to begin crawling (p=0.059). Our results are compatible with the hypothesis that the difference in the rates of prenatal and early postnatal development between children of Toxoplasma-negative and Toxoplasma-positive mothers might be caused by a decreased stringency of embryo quality control in partly immunosuppressed Toxoplasma-positive mothers resulting in a higher proportion of infants with genetic or developmental disorders in offspring. However, because of relatively low return rate of questionnaires and an associated risk of a sieve effect, our results should be considered as preliminary and performing a large scale prospective study in the future is critically needed.
PMID: 22819214 [PubMed - as supplied by publisher]
Slower postnatal motor development in infants of mothers with latent toxoplasmosis during the first 18months of life
Kaňková S, Sulc J, Křivohlavá R, Kuběna A, Flegr J.
Department of Philosophy and History of Science, Faculty of Science, Charles University in Prague, CZ-128 44 Prague 2, Czech Republic.
Toxoplasmosis, a zoonosis caused by a protozoan, Toxoplasma gondii, is probably the most widespread human parasitosis in developed countries. Pregnant women with latent toxoplasmosis have seemingly younger fetuses especially in the 16th week of gestation, which suggests that fetuses of Toxoplasma-infected mothers have slower rates of development in the first trimester of pregnancy. In the present retrospective cohort study, we analyzed data on postnatal motor development of infants from 331 questionnaire respondents including 53 Toxoplasma-infected mothers to search for signs of early postnatal development disorders. During the first year of life, a slower postnatal motor development was observed in infants of mothers with latent toxoplasmosis. These infants significantly later developed the ability to control the head position (p=0.039), to roll from supine to prone position (p=0.022) and were slightly later to begin crawling (p=0.059). Our results are compatible with the hypothesis that the difference in the rates of prenatal and early postnatal development between children of Toxoplasma-negative and Toxoplasma-positive mothers might be caused by a decreased stringency of embryo quality control in partly immunosuppressed Toxoplasma-positive mothers resulting in a higher proportion of infants with genetic or developmental disorders in offspring. However, because of relatively low return rate of questionnaires and an associated risk of a sieve effect, our results should be considered as preliminary and performing a large scale prospective study in the future is critically needed.
PMID: 22819214 [PubMed - as supplied by publisher]
Maternal antibodies to infectious agents and risk for non-affective psychoses in the offspring-a matched case-control study
Schizophr Res. 2012 Jul 20. [Epub ahead of print]
Maternal antibodies to infectious agents and risk for non-affective psychoses in the offspring-a matched case-control study
Blomström A, Karlsson H, Wicks S, Yang S, Yolken RH, Dalman C.
Division of Public Health Epidemiology, Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden.
BACKGROUND:
An increasing number of studies suggest that certain maternal infections are associated with non-affective psychoses in the offspring. Here we investigated if maternal exposure to Toxoplasma gondii, cytomegalovirus (CMV), herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2) prior to delivery was associated with future diagnosis of schizophrenia or other non-affective psychoses in the offspring.
METHODS:
This case-control study included 198 individuals born in Sweden 1975-85, diagnosed with schizophrenia (ICD-10, F20) and other non-affective psychoses (ICD-10, F21-29) as in- or outpatients, and 524 matched controls. Specific immunoglobulin G (IgG) levels in archived neonatal dried blood samples from these individuals were determined by immunoassays. Reference levels were determined by prevalences among pregnant women in Sweden 1975-85. Odds ratios (OR) for schizophrenia and other non-affective psychoses were calculated, considering maternal and gestational factors as covariates.
RESULTS:
Levels of IgG directed at T. gondii corresponding to maternal exposure was associated with subsequent schizophrenia (OR=2.1, 95% CI 1.0-4.5) as were levels of IgG directed at CMV (OR=2.2, 95% CI 1.0-5.1) but not at HSV-1 or -2. There were even stronger associations with higher levels of T. gondii or CMV antibodies. There were no associations between any of the infectious agents and other non-affective psychoses.
CONCLUSIONS:
This study supports findings of maternal exposure to T. gondii and schizophrenia risk in offspring, and extends the risk to also include maternal exposure to CMV. Future studies should confirm the association with CMV exposure and identify mechanisms underlying these associations.
PMID: 22819777
Maternal antibodies to infectious agents and risk for non-affective psychoses in the offspring-a matched case-control study
Blomström A, Karlsson H, Wicks S, Yang S, Yolken RH, Dalman C.
Division of Public Health Epidemiology, Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden.
BACKGROUND:
An increasing number of studies suggest that certain maternal infections are associated with non-affective psychoses in the offspring. Here we investigated if maternal exposure to Toxoplasma gondii, cytomegalovirus (CMV), herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2) prior to delivery was associated with future diagnosis of schizophrenia or other non-affective psychoses in the offspring.
METHODS:
This case-control study included 198 individuals born in Sweden 1975-85, diagnosed with schizophrenia (ICD-10, F20) and other non-affective psychoses (ICD-10, F21-29) as in- or outpatients, and 524 matched controls. Specific immunoglobulin G (IgG) levels in archived neonatal dried blood samples from these individuals were determined by immunoassays. Reference levels were determined by prevalences among pregnant women in Sweden 1975-85. Odds ratios (OR) for schizophrenia and other non-affective psychoses were calculated, considering maternal and gestational factors as covariates.
RESULTS:
Levels of IgG directed at T. gondii corresponding to maternal exposure was associated with subsequent schizophrenia (OR=2.1, 95% CI 1.0-4.5) as were levels of IgG directed at CMV (OR=2.2, 95% CI 1.0-5.1) but not at HSV-1 or -2. There were even stronger associations with higher levels of T. gondii or CMV antibodies. There were no associations between any of the infectious agents and other non-affective psychoses.
CONCLUSIONS:
This study supports findings of maternal exposure to T. gondii and schizophrenia risk in offspring, and extends the risk to also include maternal exposure to CMV. Future studies should confirm the association with CMV exposure and identify mechanisms underlying these associations.
PMID: 22819777
Wednesday, July 18, 2012
A Toxoplasma gondii Pseudokinase Inhibits Host IRG Resistance Proteins
PLoS Biol. 2012 Jul;10(7):e1001358. Epub 2012 Jul 10.
A Toxoplasma gondii Pseudokinase Inhibits Host IRG Resistance Proteins
Fleckenstein MC, Reese ML, Könen-Waisman S, Boothroyd JC, Howard JC, Steinfeldt T.
Institute for Genetics, University of Cologne, Cologne, Germany.
The ability of mice to resist infection with the protozoan parasite, Toxoplasma gondii, depends in large part on the function of members of a complex family of atypical large GTPases, the interferon-gamma-inducible immunity-related GTPases (IRG proteins). Nevertheless, some strains of T. gondii are highly virulent for mice because, as recently shown, they secrete a polymorphic protein kinase, ROP18, from the rhoptries into the host cell cytosol at the moment of cell invasion. Depending on the allele, ROP18 can act as a virulence factor for T. gondii by phosphorylating and thereby inactivating mouse IRG proteins. In this article we show that IRG proteins interact not only with ROP18, but also strongly with the products of another polymorphic locus, ROP5, already implicated as a major virulence factor from genetic crosses, but whose function has previously been a complete mystery. ROP5 proteins are members of the same protein family as ROP18 kinases but are pseudokinases by sequence, structure, and function. We show by a combination of genetic and biochemical approaches that ROP5 proteins act as essential co-factors for ROP18 and present evidence that they work by enforcing an inactive GDP-dependent conformation on the IRG target protein. By doing so they prevent GTP-dependent activation and simultaneously expose the target threonines on the switch I loop for phosphorylation by ROP18, resulting in permanent inactivation of the protein. This represents a novel mechanism in which a pseudokinase facilitates the phosphorylation of a target by a partner kinase by preparing the substrate for phosphorylation, rather than by upregulation of the activity of the kinase itself.
PMID: 22802726 [PubMed - in process]
A Toxoplasma gondii Pseudokinase Inhibits Host IRG Resistance Proteins
Fleckenstein MC, Reese ML, Könen-Waisman S, Boothroyd JC, Howard JC, Steinfeldt T.
Institute for Genetics, University of Cologne, Cologne, Germany.
The ability of mice to resist infection with the protozoan parasite, Toxoplasma gondii, depends in large part on the function of members of a complex family of atypical large GTPases, the interferon-gamma-inducible immunity-related GTPases (IRG proteins). Nevertheless, some strains of T. gondii are highly virulent for mice because, as recently shown, they secrete a polymorphic protein kinase, ROP18, from the rhoptries into the host cell cytosol at the moment of cell invasion. Depending on the allele, ROP18 can act as a virulence factor for T. gondii by phosphorylating and thereby inactivating mouse IRG proteins. In this article we show that IRG proteins interact not only with ROP18, but also strongly with the products of another polymorphic locus, ROP5, already implicated as a major virulence factor from genetic crosses, but whose function has previously been a complete mystery. ROP5 proteins are members of the same protein family as ROP18 kinases but are pseudokinases by sequence, structure, and function. We show by a combination of genetic and biochemical approaches that ROP5 proteins act as essential co-factors for ROP18 and present evidence that they work by enforcing an inactive GDP-dependent conformation on the IRG target protein. By doing so they prevent GTP-dependent activation and simultaneously expose the target threonines on the switch I loop for phosphorylation by ROP18, resulting in permanent inactivation of the protein. This represents a novel mechanism in which a pseudokinase facilitates the phosphorylation of a target by a partner kinase by preparing the substrate for phosphorylation, rather than by upregulation of the activity of the kinase itself.
PMID: 22802726 [PubMed - in process]
Tuesday, July 17, 2012
A Cluster of Interferon-γ-Inducible p65 GTPases Plays a Critical Role in Host Defense against Toxoplasma gondii
Immunity. 2012 Jul 10. [Epub ahead of print]
A Cluster of Interferon-γ-Inducible p65 GTPases Plays a Critical Role in Host Defense against Toxoplasma gondii
Yamamoto M, Okuyama M, Ma JS, Kimura T, Kamiyama N, Saiga H, Ohshima J, Sasai M, Kayama H, Okamoto T, Huang DC, Soldati-Favre D, Horie K, Takeda J, Takeda K.
Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan; Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan; Laboratory of Immunoparasitology, WPI Immunology Frontier Research Center, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan; Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama 332-0012, Japan.
Interferon-γ (IFN-γ) is essential for host defense against intracellular pathogens. Stimulation of innate immune cells by IFN-γ upregulates ∼2,000 effector genes such as immunity-related GTPases including p65 guanylate-binding protein (Gbp) family genes. We show that a cluster of Gbp genes was required for host cellular immunity against the intracellular parasite Toxoplasma gondii. We generated mice deficient for all six Gbp genes located on chromosome 3 (Gbp(chr3)) by targeted chromosome engineering. Mice lacking Gbp(chr3) were highly susceptible to T. gondii infection, resulting in increased parasite burden in immune organs. Furthermore, Gbp(chr3)-deleted macrophages were defective in IFN-γ-mediated suppression of T. gondii intracellular growth and recruitment of IFN-γ-inducible p47 GTPase Irgb6 to the parasitophorous vacuole. In addition, some members of Gbp(chr3) restored the protective response against T. gondii in Gbp(chr3)-deleted cells. Our results suggest that Gbp(chr3) play a pivotal role in anti-T. gondii host defense by controlling IFN-γ-mediated Irgb6-dependent cellular innate immunity.
PMID: 22795875 [PubMed - as supplied by publisher]
A Cluster of Interferon-γ-Inducible p65 GTPases Plays a Critical Role in Host Defense against Toxoplasma gondii
Yamamoto M, Okuyama M, Ma JS, Kimura T, Kamiyama N, Saiga H, Ohshima J, Sasai M, Kayama H, Okamoto T, Huang DC, Soldati-Favre D, Horie K, Takeda J, Takeda K.
Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan; Laboratory of Mucosal Immunology, WPI Immunology Frontier Research Center, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan; Laboratory of Immunoparasitology, WPI Immunology Frontier Research Center, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan; Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama 332-0012, Japan.
Interferon-γ (IFN-γ) is essential for host defense against intracellular pathogens. Stimulation of innate immune cells by IFN-γ upregulates ∼2,000 effector genes such as immunity-related GTPases including p65 guanylate-binding protein (Gbp) family genes. We show that a cluster of Gbp genes was required for host cellular immunity against the intracellular parasite Toxoplasma gondii. We generated mice deficient for all six Gbp genes located on chromosome 3 (Gbp(chr3)) by targeted chromosome engineering. Mice lacking Gbp(chr3) were highly susceptible to T. gondii infection, resulting in increased parasite burden in immune organs. Furthermore, Gbp(chr3)-deleted macrophages were defective in IFN-γ-mediated suppression of T. gondii intracellular growth and recruitment of IFN-γ-inducible p47 GTPase Irgb6 to the parasitophorous vacuole. In addition, some members of Gbp(chr3) restored the protective response against T. gondii in Gbp(chr3)-deleted cells. Our results suggest that Gbp(chr3) play a pivotal role in anti-T. gondii host defense by controlling IFN-γ-mediated Irgb6-dependent cellular innate immunity.
PMID: 22795875 [PubMed - as supplied by publisher]
Benzoylbenzimidazole-based selective inhibitors targeting Cryptosporidium parvum and Toxoplasma gondii calcium-dependent protein kinase-1
Bioorg Med Chem Lett. 2012 Jun 23. [Epub ahead of print]
Benzoylbenzimidazole-based selective inhibitors targeting Cryptosporidium parvum and Toxoplasma gondii calcium-dependent protein kinase-1
Zhang Z, Ojo KK, Johnson SM, Larson ET, He P, Geiger JA, Castellanos-Gonzalez A, White AC Jr, Parsons M, Merritt EA, Maly DJ, Verlinde CL, Van Voorhis WC, Fan E.
Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
Calcium-dependent protein kinase-1 (CDPK1) from Cryptosporidium parvum (CpCDPK1) and Toxoplasma gondii (TgCDPK1) have become attractive targets for discovering selective inhibitors to combat infections caused by these protozoa. We used structure-based design to improve a series of benzoylbenzimidazole-based compounds in terms of solubility, selectivity, and potency against CpCDPK1 and TgCDPK1. The best inhibitors show inhibitory potencies below 50nM and selectivity well above 200-fold over two human kinases with small gatekeeper residues.
PMID: 22795629 [PubMed - as supplied by publisher]
Benzoylbenzimidazole-based selective inhibitors targeting Cryptosporidium parvum and Toxoplasma gondii calcium-dependent protein kinase-1
Zhang Z, Ojo KK, Johnson SM, Larson ET, He P, Geiger JA, Castellanos-Gonzalez A, White AC Jr, Parsons M, Merritt EA, Maly DJ, Verlinde CL, Van Voorhis WC, Fan E.
Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
Calcium-dependent protein kinase-1 (CDPK1) from Cryptosporidium parvum (CpCDPK1) and Toxoplasma gondii (TgCDPK1) have become attractive targets for discovering selective inhibitors to combat infections caused by these protozoa. We used structure-based design to improve a series of benzoylbenzimidazole-based compounds in terms of solubility, selectivity, and potency against CpCDPK1 and TgCDPK1. The best inhibitors show inhibitory potencies below 50nM and selectivity well above 200-fold over two human kinases with small gatekeeper residues.
PMID: 22795629 [PubMed - as supplied by publisher]
Oxidative stress and tryptophan degradation pattern of acute Toxoplasma gondii infection in mice
Parasitol Res. 2012 Jul 12. [Epub ahead of print]
Oxidative stress and tryptophan degradation pattern of acute Toxoplasma gondii infection in mice
Engin AB, Dogruman-Al F, Ercin U, Celebi B, Babur C, Bukan N.
Department of Toxicology, Faculty of Pharmacy, Gazi University, 06330, Hipodrom, Ankara, Turkey, abengin@gmail.com.
Toxoplasma gondii is a very common obligate single-cell protozoan parasite which induces overproduction of interferon (IFN)-gamma and of other proinflammatory cytokines. Although immunomodulatory role of IFN-gamma favors tryptophan (Trp) degradation via indoleamine-2,3-dioxygenase (IDO) activity and is related with nitric oxide (NO) synthesis, the mechanism of antitoxoplasma activity is complex. In order to characterize the Trp degradation pattern during the acute T. gondii infection, serum Trp, kynurenine (Kyn), and urinary biopterin levels of mice were measured. The possible oxidative status was evaluated by the liver, spleen, brain, and serum malondialdehyde (MDA) and NO levels. Increased free radical toxicity may cause elevation in tissue MDA in T. gondii-infected mice, while unchanged serum MDA might indicate the increased oxidative stress due to T. gondii infection restricted to intracellular area. Elevated serum NO most probably might be due to the formation of reactive nitrogen radicals. The Kyn/Trp ratio was higher in T. gondii-infected mice compared to healthy animals (p < 0.05); however, it was not correlated with urinary biopterin. These results suggested that Trp degradation might be promoted by a pathway other than IDO during T. gondii infection and the reduction of Trp concentration favors the local immunosuppression and systemic tolerance.
PMID: 22790966 [PubMed - as supplied by publisher]
Oxidative stress and tryptophan degradation pattern of acute Toxoplasma gondii infection in mice
Engin AB, Dogruman-Al F, Ercin U, Celebi B, Babur C, Bukan N.
Department of Toxicology, Faculty of Pharmacy, Gazi University, 06330, Hipodrom, Ankara, Turkey, abengin@gmail.com.
Toxoplasma gondii is a very common obligate single-cell protozoan parasite which induces overproduction of interferon (IFN)-gamma and of other proinflammatory cytokines. Although immunomodulatory role of IFN-gamma favors tryptophan (Trp) degradation via indoleamine-2,3-dioxygenase (IDO) activity and is related with nitric oxide (NO) synthesis, the mechanism of antitoxoplasma activity is complex. In order to characterize the Trp degradation pattern during the acute T. gondii infection, serum Trp, kynurenine (Kyn), and urinary biopterin levels of mice were measured. The possible oxidative status was evaluated by the liver, spleen, brain, and serum malondialdehyde (MDA) and NO levels. Increased free radical toxicity may cause elevation in tissue MDA in T. gondii-infected mice, while unchanged serum MDA might indicate the increased oxidative stress due to T. gondii infection restricted to intracellular area. Elevated serum NO most probably might be due to the formation of reactive nitrogen radicals. The Kyn/Trp ratio was higher in T. gondii-infected mice compared to healthy animals (p < 0.05); however, it was not correlated with urinary biopterin. These results suggested that Trp degradation might be promoted by a pathway other than IDO during T. gondii infection and the reduction of Trp concentration favors the local immunosuppression and systemic tolerance.
PMID: 22790966 [PubMed - as supplied by publisher]
Kinetic analysis of cytokines, chemokines, chemokine receptors and adhesion molecules in murine ocular toxoplasmosis
Br J Ophthalmol. 2012 Jul 11. [Epub ahead of print]
Kinetic analysis of cytokines, chemokines, chemokine receptors and adhesion molecules in murine ocular toxoplasmosis
Kikumura A, Ishikawa T, Norose K.
Graduate School of Medicine, Chiba University, Chiba, Japan.
BACKGROUND/AIMS:
To investigate the molecules possibly influencing the recruitment and migration of leucocytes in murine ocular toxoplasmosis, the kinetics of the messenger RNA expression levels of cytokines, chemokines, chemokine receptors and adhesion molecules in the retina were analysed.
METHODS:
Retina and brain were obtained sequentially from Toxoplasma gondii Fukaya strain-infected wild-type (WT) C57BL/6 and interferon gamma (IFN-γ) knockout (GKO) mice of the same background. The mRNA expression levels of these molecules were analysed by real-time PCR assay.
RESULTS:
In the retina of WT mice the expression levels of IFN-γ, interleukin 17A, CCL3, CCL4, CCL5, CXCL1, CXCL2, CXCL10, CCR5, CCR7, CXCR2, CXCR3 and intracellular adhesion molecule 1 increased, reaching peaks approximately 14-28 days after infection. The expression levels of CXCR4 and CXCR5 were absent and very low, respectively, during the infection. In the brain of WT mice, the kinetic patterns of these expression levels tended to be the same as in the retina except CXCR4. On the other hand, in GKO mice these molecules, except CXCL1, CXCL2 and CXCR2, remained at basal levels.
CONCLUSION:
In murine ocular toxoplasmosis, cytokines, chemokines, chemokine receptors and adhesion molecules were involved in the pathogenesis, and IFN-γ played a pivotal role.
PMID: 22790439 [PubMed - as supplied by publisher]
Kinetic analysis of cytokines, chemokines, chemokine receptors and adhesion molecules in murine ocular toxoplasmosis
Kikumura A, Ishikawa T, Norose K.
Graduate School of Medicine, Chiba University, Chiba, Japan.
BACKGROUND/AIMS:
To investigate the molecules possibly influencing the recruitment and migration of leucocytes in murine ocular toxoplasmosis, the kinetics of the messenger RNA expression levels of cytokines, chemokines, chemokine receptors and adhesion molecules in the retina were analysed.
METHODS:
Retina and brain were obtained sequentially from Toxoplasma gondii Fukaya strain-infected wild-type (WT) C57BL/6 and interferon gamma (IFN-γ) knockout (GKO) mice of the same background. The mRNA expression levels of these molecules were analysed by real-time PCR assay.
RESULTS:
In the retina of WT mice the expression levels of IFN-γ, interleukin 17A, CCL3, CCL4, CCL5, CXCL1, CXCL2, CXCL10, CCR5, CCR7, CXCR2, CXCR3 and intracellular adhesion molecule 1 increased, reaching peaks approximately 14-28 days after infection. The expression levels of CXCR4 and CXCR5 were absent and very low, respectively, during the infection. In the brain of WT mice, the kinetic patterns of these expression levels tended to be the same as in the retina except CXCR4. On the other hand, in GKO mice these molecules, except CXCL1, CXCL2 and CXCR2, remained at basal levels.
CONCLUSION:
In murine ocular toxoplasmosis, cytokines, chemokines, chemokine receptors and adhesion molecules were involved in the pathogenesis, and IFN-γ played a pivotal role.
PMID: 22790439 [PubMed - as supplied by publisher]
Enhancement of protective immune responses induced by Toxoplasma gondii dense granule antigen 7 (GRA7) against toxoplasmosis in mice using a prime-boost vaccination strategy
Vaccine. 2012 Jul 9. [Epub ahead of print]
Enhancement of protective immune responses induced by Toxoplasma gondii dense granule antigen 7 (GRA7) against toxoplasmosis in mice using a prime-boost vaccination strategy
Min J, Qu D, Li C, Song X, Zhao Q, Li XA, Yang Y, Liu Q, He S, Zhou H.
Department of Parasitology, Shandong University School of Medicine, 44 Wenhua West Road, Jinan, Shandong 250012, PR China.
Effective vaccines against Toxoplasma gondii may contribute to preventing and controlling the spread of toxoplasmosis, which is important for improving outcomes of infections in humans and livestock animals. The dense granule antigen 7 (GRA7) of T. gondii might be an immunodominant antigen for a vaccine candidate. In the present study, a further exploration of its vaccine effect, a heterologous prime-boost vaccination strategy with a recombinant eukaryotic plasmid pEGFP-GRA7 and a recombinant protein GRA7 expressed from a prokaryotic plasmid pET30-GRA7, was performed in BALB/c mice. The data reveal that a DNA prime-protein boost vaccination induces both humoral and cellular immune responses against T. gondii associated with high levels of total IgG, IgG2a isotype and gamma interferon (IFN-γ). Challenge experiments further show that the DNA prime-protein boost vaccination significantly increases survival rate (60%), compared with controls in which all died within 8 days of challenge. Therefore, the DNA prime-protein boost vaccination based on GRA7 might be a promising regimen for further development of an effective vaccine against T. gondii.
PMID: 22789504 [PubMed - as supplied by publisher]
Enhancement of protective immune responses induced by Toxoplasma gondii dense granule antigen 7 (GRA7) against toxoplasmosis in mice using a prime-boost vaccination strategy
Min J, Qu D, Li C, Song X, Zhao Q, Li XA, Yang Y, Liu Q, He S, Zhou H.
Department of Parasitology, Shandong University School of Medicine, 44 Wenhua West Road, Jinan, Shandong 250012, PR China.
Effective vaccines against Toxoplasma gondii may contribute to preventing and controlling the spread of toxoplasmosis, which is important for improving outcomes of infections in humans and livestock animals. The dense granule antigen 7 (GRA7) of T. gondii might be an immunodominant antigen for a vaccine candidate. In the present study, a further exploration of its vaccine effect, a heterologous prime-boost vaccination strategy with a recombinant eukaryotic plasmid pEGFP-GRA7 and a recombinant protein GRA7 expressed from a prokaryotic plasmid pET30-GRA7, was performed in BALB/c mice. The data reveal that a DNA prime-protein boost vaccination induces both humoral and cellular immune responses against T. gondii associated with high levels of total IgG, IgG2a isotype and gamma interferon (IFN-γ). Challenge experiments further show that the DNA prime-protein boost vaccination significantly increases survival rate (60%), compared with controls in which all died within 8 days of challenge. Therefore, the DNA prime-protein boost vaccination based on GRA7 might be a promising regimen for further development of an effective vaccine against T. gondii.
PMID: 22789504 [PubMed - as supplied by publisher]
Thursday, July 05, 2012
The Rhoptry Proteins ROP18 and ROP5 Mediate Toxoplasma gondii Evasion of the Murine, But Not the Human, Interferon-Gamma Response
PLoS Pathog. 2012 Jun;8(6):e1002784. Epub 2012 Jun 28.
The Rhoptry Proteins ROP18 and ROP5 Mediate Toxoplasma gondii Evasion of the Murine, But Not the Human, Interferon-Gamma Response
Niedelman W, Gold DA, Rosowski EE, Sprokholt JK, Lim D, Farid Arenas A, Melo MB, Spooner E, Yaffe MB, Saeij JP.
Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
The obligate intracellular parasite Toxoplasma gondii secretes effector proteins into the host cell that manipulate the immune response allowing it to establish a chronic infection. Crosses between the types I, II and III strains, which are prevalent in North America and Europe, have identified several secreted effectors that determine strain differences in mouse virulence. The polymorphic rhoptry protein kinase ROP18 was recently shown to determine the difference in virulence between type I and III strains by phosphorylating and inactivating the interferon-γ (IFNγ)-induced immunity-related GTPases (IRGs) that promote killing by disrupting the parasitophorous vacuole membrane (PVM) in murine cells. The polymorphic pseudokinase ROP5 determines strain differences in virulence through an unknown mechanism. Here we report that ROP18 can only inhibit accumulation of the IRGs on the PVM of strains that also express virulent ROP5 alleles. In contrast, specific ROP5 alleles can reduce IRG coating even in the absence of ROP18 expression and can directly interact with one or more IRGs. We further show that the allelic combination of ROP18 and ROP5 also determines IRG evasion and virulence of strains belonging to other lineages besides types I, II and III. However, neither ROP18 nor ROP5 markedly affect survival in IFNγ-activated human cells, which lack the multitude of IRGs present in murine cells. These findings suggest that ROP18 and ROP5 have specifically evolved to block the IRGs and are unlikely to have effects in species that do not have the IRG system, such as humans.
PMID: 22761577 [PubMed - as supplied by publisher]
The Rhoptry Proteins ROP18 and ROP5 Mediate Toxoplasma gondii Evasion of the Murine, But Not the Human, Interferon-Gamma Response
Niedelman W, Gold DA, Rosowski EE, Sprokholt JK, Lim D, Farid Arenas A, Melo MB, Spooner E, Yaffe MB, Saeij JP.
Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
The obligate intracellular parasite Toxoplasma gondii secretes effector proteins into the host cell that manipulate the immune response allowing it to establish a chronic infection. Crosses between the types I, II and III strains, which are prevalent in North America and Europe, have identified several secreted effectors that determine strain differences in mouse virulence. The polymorphic rhoptry protein kinase ROP18 was recently shown to determine the difference in virulence between type I and III strains by phosphorylating and inactivating the interferon-γ (IFNγ)-induced immunity-related GTPases (IRGs) that promote killing by disrupting the parasitophorous vacuole membrane (PVM) in murine cells. The polymorphic pseudokinase ROP5 determines strain differences in virulence through an unknown mechanism. Here we report that ROP18 can only inhibit accumulation of the IRGs on the PVM of strains that also express virulent ROP5 alleles. In contrast, specific ROP5 alleles can reduce IRG coating even in the absence of ROP18 expression and can directly interact with one or more IRGs. We further show that the allelic combination of ROP18 and ROP5 also determines IRG evasion and virulence of strains belonging to other lineages besides types I, II and III. However, neither ROP18 nor ROP5 markedly affect survival in IFNγ-activated human cells, which lack the multitude of IRGs present in murine cells. These findings suggest that ROP18 and ROP5 have specifically evolved to block the IRGs and are unlikely to have effects in species that do not have the IRG system, such as humans.
PMID: 22761577 [PubMed - as supplied by publisher]
NK Cell-Derived Interferon-γ Orchestrates Cellular Dynamics and the Differentiation of Monocytes into Dendritic Cells at the Site of Infection
Immunity. 2012 Jun 29;36(6):1047-59.
NK Cell-Derived Interferon-γ Orchestrates Cellular Dynamics and the Differentiation of Monocytes into Dendritic Cells at the Site of Infection
Goldszmid RS, Caspar P, Rivollier A, White S, Dzutsev A, Hieny S, Kelsall B, Trinchieri G, Sher A.
Laboratory of Experimental Immunology, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA; Immunobiology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Dendritic cells (DCs), monocytes, and/or macrophages initiate host-protective immune responses to intracellular pathogens in part through interleukin-12 (IL-12) production, although the relative contribution of tissue resident versus recruited cells has been unclear. Here, we showed that after intraperitoneal infection with Toxoplasma gondii cysts, resident mononuclear phagocytes are replaced by circulating monocytes that differentiate in situ into inflammatory DCs (moDCs) and F4/80(+) macrophages. Importantly, NK cell-derived interferon-γ (IFN-γ) was required for both the loss of resident mononuclear phagocytes and the local differentiation of monocytes into macrophages and moDCs. This newly generated moDC population and not the resident DCs (or macrophages) served as the major source of IL-12 at the site of infection. Thus, NK cell-derived IFN-γ is important in both regulating inflammatory cell dynamics and in driving the local differentiation of monocytes into the cells required for initiating the immune response to an important intracellular pathogen.
PMID: 22749354 [PubMed - in process]
NK Cell-Derived Interferon-γ Orchestrates Cellular Dynamics and the Differentiation of Monocytes into Dendritic Cells at the Site of Infection
Goldszmid RS, Caspar P, Rivollier A, White S, Dzutsev A, Hieny S, Kelsall B, Trinchieri G, Sher A.
Laboratory of Experimental Immunology, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA; Immunobiology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Dendritic cells (DCs), monocytes, and/or macrophages initiate host-protective immune responses to intracellular pathogens in part through interleukin-12 (IL-12) production, although the relative contribution of tissue resident versus recruited cells has been unclear. Here, we showed that after intraperitoneal infection with Toxoplasma gondii cysts, resident mononuclear phagocytes are replaced by circulating monocytes that differentiate in situ into inflammatory DCs (moDCs) and F4/80(+) macrophages. Importantly, NK cell-derived interferon-γ (IFN-γ) was required for both the loss of resident mononuclear phagocytes and the local differentiation of monocytes into macrophages and moDCs. This newly generated moDC population and not the resident DCs (or macrophages) served as the major source of IL-12 at the site of infection. Thus, NK cell-derived IFN-γ is important in both regulating inflammatory cell dynamics and in driving the local differentiation of monocytes into the cells required for initiating the immune response to an important intracellular pathogen.
PMID: 22749354 [PubMed - in process]
Purification, crystallization and preliminary X-ray diffraction analysis of inner membrane complex (IMC) subcompartment protein 1 (ISP1) from Toxoplasma gondii
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2012 Jul 1;68(Pt 7):832-4. Epub 2012 Jun 28.
Purification, crystallization and preliminary X-ray diffraction analysis of inner membrane complex (IMC) subcompartment protein 1 (ISP1) from Toxoplasma gondii
Tonkin ML, Brown S, Beck JR, Bradley PJ, Boulanger MJ.
Department of Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada.
The protozoan parasites of the Apicomplexa phylum are devastating global pathogens. Their success is largely due to phylum-specific proteins found in specialized organelles and cellular structures. The inner membrane complex (IMC) is a unique apicomplexan structure that is essential for motility, invasion and replication. The IMC subcompartment proteins (ISP) have recently been identified in Toxoplasma gondii and shown to be critical for replication, although their specific mechanisms are unknown. Structural characterization of TgISP1 was pursued in order to identify the fold adopted by the ISPs and to generate detailed insight into how this family of proteins functions during replication. An N-terminally truncated form of TgISP1 was purified from Escherichia coli, crystallized and subjected to X-ray diffraction analysis. Two crystal forms of TgISP1 belonging to space groups P4(1)32 or P4(3)32 and P2(1)2(1)2(1) diffracted to 2.05 and 2.1 Å resolution, respectively.
PMID: 22750877 [PubMed - in process]
Purification, crystallization and preliminary X-ray diffraction analysis of inner membrane complex (IMC) subcompartment protein 1 (ISP1) from Toxoplasma gondii
Tonkin ML, Brown S, Beck JR, Bradley PJ, Boulanger MJ.
Department of Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada.
The protozoan parasites of the Apicomplexa phylum are devastating global pathogens. Their success is largely due to phylum-specific proteins found in specialized organelles and cellular structures. The inner membrane complex (IMC) is a unique apicomplexan structure that is essential for motility, invasion and replication. The IMC subcompartment proteins (ISP) have recently been identified in Toxoplasma gondii and shown to be critical for replication, although their specific mechanisms are unknown. Structural characterization of TgISP1 was pursued in order to identify the fold adopted by the ISPs and to generate detailed insight into how this family of proteins functions during replication. An N-terminally truncated form of TgISP1 was purified from Escherichia coli, crystallized and subjected to X-ray diffraction analysis. Two crystal forms of TgISP1 belonging to space groups P4(1)32 or P4(3)32 and P2(1)2(1)2(1) diffracted to 2.05 and 2.1 Å resolution, respectively.
PMID: 22750877 [PubMed - in process]
Toxoplasma gondii Infection and Self-directed Violence in MothersToxoplasma Gondii and Self-directed Violence
Arch Gen Psychiatry. 2012 Jul 2:1-8. doi: 10.1001/archgenpsychiatry.2012.668. [Epub ahead of print]
Toxoplasma gondii Infection and Self-directed Violence in MothersToxoplasma Gondii and Self-directed Violence
Pedersen MG, Mortensen PB, Norgaard-Pedersen B, Postolache TT.
CONTEXT Two studies based on clinical samples have found an association between Toxoplasma gondii infection and history of suicide attempt. To our knowledge, these findings have never been replicated in a prospective cohort study. OBJECTIVE To examine whether T gondii-infected mothers have an increased risk of self-directed violence, violent suicide attempts, and suicide and whether the risk depends on the level of T gondii IgG antibodies. DESIGN Register-based prospective cohort study. Women were followed up from the date of delivery, 1992 to 1995 until 2006. SETTING Denmark. PARTICIPANTS A cohort of 45 788 women born in Denmark whose level of Toxoplasma-specific IgG antibodies was measured in connection with child birth between 1992 and 1995. MAIN OUTCOME MEASURES Incidence rates of self-directed violence, violent suicide attempts, and suicide in relation to T gondii seropositivity and serointensity. RESULTS T gondii-infected mothers had a relative risk of self-directed violence of 1.53 (95% CI, 1.27-1.85) compared with noninfected mothers, and the risk seemed to increase with increasing IgG antibody level. For violent suicide attempts, the relative risk was 1.81 (95% CI, 1.13-2.84) and for suicide, 2.05 (95% CI, 0.78-5.20). A similar association was found for repetition of self-directed violence, with a relative risk of 1.54 (95% CI, 0.98-2.39). CONCLUSION Women with a T gondii infection have an increased risk of self-directed violence.
PMID: 22752117 [PubMed - as supplied by publisher]
Toxoplasma gondii Infection and Self-directed Violence in MothersToxoplasma Gondii and Self-directed Violence
Pedersen MG, Mortensen PB, Norgaard-Pedersen B, Postolache TT.
CONTEXT Two studies based on clinical samples have found an association between Toxoplasma gondii infection and history of suicide attempt. To our knowledge, these findings have never been replicated in a prospective cohort study. OBJECTIVE To examine whether T gondii-infected mothers have an increased risk of self-directed violence, violent suicide attempts, and suicide and whether the risk depends on the level of T gondii IgG antibodies. DESIGN Register-based prospective cohort study. Women were followed up from the date of delivery, 1992 to 1995 until 2006. SETTING Denmark. PARTICIPANTS A cohort of 45 788 women born in Denmark whose level of Toxoplasma-specific IgG antibodies was measured in connection with child birth between 1992 and 1995. MAIN OUTCOME MEASURES Incidence rates of self-directed violence, violent suicide attempts, and suicide in relation to T gondii seropositivity and serointensity. RESULTS T gondii-infected mothers had a relative risk of self-directed violence of 1.53 (95% CI, 1.27-1.85) compared with noninfected mothers, and the risk seemed to increase with increasing IgG antibody level. For violent suicide attempts, the relative risk was 1.81 (95% CI, 1.13-2.84) and for suicide, 2.05 (95% CI, 0.78-5.20). A similar association was found for repetition of self-directed violence, with a relative risk of 1.54 (95% CI, 0.98-2.39). CONCLUSION Women with a T gondii infection have an increased risk of self-directed violence.
PMID: 22752117 [PubMed - as supplied by publisher]
Dissection of minimal sequence requirements for rhoptry membrane targeting in the malaria parasite
Traffic. 2012 Jul 3;9999(999A). doi: 10.1111/j.1600-0854.2012.01394.x. [Epub ahead of print]
Dissection of minimal sequence requirements for rhoptry membrane targeting in the malaria parasite
Cabrera A, Herrmann S, Warszta D, Santos JM, John Peter AT, Kono M, Debrouver S, Jacobs T, Spielmann T, Ungermann C, Soldati-Favre D, Gilberger TW.
M.G. DeGroote Institute for Infectious Disease Research, Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.
Rhoptries are specialized secretory organelles characteristic of single cell organisms belonging to the clade Apicomplexa. These organelles play a key role in the invasion process of host cells by accumulating and subsequently secreting an unknown number of proteins mediating host cell entry. Despite their essential role, little is known about their biogenesis, components and targeting determinants. Here we report on a conserved apicomplexan protein termed Armadillo Repeats-Only (ARO) protein that we localized to the cytosolic face of Plasmodium falciparum and Toxoplasma gondii rhoptries. We show that the first 20 N-terminal amino acids are sufficient for rhoptry membrane targeting. This protein relies on both - myristoylation and palmitoylation motifs - for membrane attachment. Although these lipid modifications are essential they are not sufficient to direct ARO to the rhoptry membranes. Mutational analysis revealed additional residues within the first 20 amino acids of ARO that play an important role for rhoptry membrane attachment: the positively charged residues R9 and K14. Interestingly, the exchange of R9 with a negative charge entirely abolishes membrane attachment, whereas the exchange of K14 (and to a lesser extent K16) alters only its membrane specificity. Additionally, 17 proteins predicted to be myristoylated and palmitoylated in the first 20 N-terminal amino acids were identified in the genome of the malaria parasite. While most of the corresponding GFP fusion proteins were trafficked to the parasite plasma membrane, two were sorted to the apical organelles. Interestingly, these proteins have a similar motif identified for ARO.
PMID: 22759070
Dissection of minimal sequence requirements for rhoptry membrane targeting in the malaria parasite
Cabrera A, Herrmann S, Warszta D, Santos JM, John Peter AT, Kono M, Debrouver S, Jacobs T, Spielmann T, Ungermann C, Soldati-Favre D, Gilberger TW.
M.G. DeGroote Institute for Infectious Disease Research, Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.
Rhoptries are specialized secretory organelles characteristic of single cell organisms belonging to the clade Apicomplexa. These organelles play a key role in the invasion process of host cells by accumulating and subsequently secreting an unknown number of proteins mediating host cell entry. Despite their essential role, little is known about their biogenesis, components and targeting determinants. Here we report on a conserved apicomplexan protein termed Armadillo Repeats-Only (ARO) protein that we localized to the cytosolic face of Plasmodium falciparum and Toxoplasma gondii rhoptries. We show that the first 20 N-terminal amino acids are sufficient for rhoptry membrane targeting. This protein relies on both - myristoylation and palmitoylation motifs - for membrane attachment. Although these lipid modifications are essential they are not sufficient to direct ARO to the rhoptry membranes. Mutational analysis revealed additional residues within the first 20 amino acids of ARO that play an important role for rhoptry membrane attachment: the positively charged residues R9 and K14. Interestingly, the exchange of R9 with a negative charge entirely abolishes membrane attachment, whereas the exchange of K14 (and to a lesser extent K16) alters only its membrane specificity. Additionally, 17 proteins predicted to be myristoylated and palmitoylated in the first 20 N-terminal amino acids were identified in the genome of the malaria parasite. While most of the corresponding GFP fusion proteins were trafficked to the parasite plasma membrane, two were sorted to the apical organelles. Interestingly, these proteins have a similar motif identified for ARO.
PMID: 22759070
Monday, July 02, 2012
T Cells Hunt Like Sharks in Our Body: Penn Study
A cross-disciplinary team at the University of Pennsylvania has arrived at a surprising finding: T cells, a key part of the immune system, use a movement strategy to track down parasites that is similar to strategies that predators such as monkeys, sharks and blue-fin tuna use to hunt their prey.
The research, published in the journal Nature, involved a unique collaboration between the laboratories of senior authors Christopher Hunter, professor and chair of the Pathobiology Department in Penn's School of Veterinary Medicine, and Andrea Liu, the Hepburn Professor of Physics in the Department of Physics and Astronomy. Penn Vet postdoctoral researcher Tajie Harris and physics graduate student Edward Banigan also played leading roles in the research.
The study, published in the journal Nature, was conducted in mice infected with the parasite Toxoplasma gondii. Using a refine yet powerful microscope that can display living tissues in three dimensions in real time, the researchers tracked the movements of T cells.
Contrary to their expectations, the T cells did not move directly toward the parasite. But their movements were not entirely random, either. Instead, their paths tended to have many short "steps" and occasional long "runs," with long and short pauses in between.
T cells aren't the only ones that move this way to find their targets. This strategy —many short-distance movements interspersed with occasional longer-distance moves — seems particularly common among hunting marine predators, including tuna, sharks, zooplankton, sea turtles and penguins, though terrestrial species like spider monkeys and honeybees may use the same approach to locate rare resources.
This parallel with animal predators also makes sense because parasites, like prey species, have evolved to evade detection.
"Many pathogens know how to hide, so T cells are not able to move directly to their target," Hunter said. "The T cell actually needs to go into an area and then see if there's anything there."
Video by Kurtis Sensenig
kurtiss@upenn.edu
Text by Katherine Unger Baillie
The research, published in the journal Nature, involved a unique collaboration between the laboratories of senior authors Christopher Hunter, professor and chair of the Pathobiology Department in Penn's School of Veterinary Medicine, and Andrea Liu, the Hepburn Professor of Physics in the Department of Physics and Astronomy. Penn Vet postdoctoral researcher Tajie Harris and physics graduate student Edward Banigan also played leading roles in the research.
The study, published in the journal Nature, was conducted in mice infected with the parasite Toxoplasma gondii. Using a refine yet powerful microscope that can display living tissues in three dimensions in real time, the researchers tracked the movements of T cells.
Contrary to their expectations, the T cells did not move directly toward the parasite. But their movements were not entirely random, either. Instead, their paths tended to have many short "steps" and occasional long "runs," with long and short pauses in between.
T cells aren't the only ones that move this way to find their targets. This strategy —many short-distance movements interspersed with occasional longer-distance moves — seems particularly common among hunting marine predators, including tuna, sharks, zooplankton, sea turtles and penguins, though terrestrial species like spider monkeys and honeybees may use the same approach to locate rare resources.
This parallel with animal predators also makes sense because parasites, like prey species, have evolved to evade detection.
"Many pathogens know how to hide, so T cells are not able to move directly to their target," Hunter said. "The T cell actually needs to go into an area and then see if there's anything there."
Video by Kurtis Sensenig
kurtiss@upenn.edu
Text by Katherine Unger Baillie
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