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Mazzone F, Hoeppner A, Reiners J, Gertzen CG, Applegate V, Abdullaziz MA, Gottstein J, Degrandi D, Wesemann M, Kurz T, Smits SH, Pfeffer K. 1-Deoxy-d-xylulose 5-phosphate reductoisomerase as target for anti Toxoplasma gondii agents: crystal structure, biochemical characterization and biological evaluation of inhibitors. Biochem J 2024; 481:1075-1096. [PMID: 39105673 PMCID: PMC11346426 DOI: 10.1042/bcj20240110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 07/27/2024] [Accepted: 08/06/2024] [Indexed: 08/07/2024]
Abstract
Toxoplasma gondii is a widely distributed apicomplexan parasite causing toxoplasmosis, a critical health issue for immunocompromised individuals and for congenitally infected foetuses. Current treatment options are limited in number and associated with severe side effects. Thus, novel anti-toxoplasma agents need to be identified and developed. 1-Deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) is considered the rate-limiting enzyme in the non-mevalonate pathway for the biosynthesis of the isoprenoid precursors isopentenyl pyrophosphate and dimethylallyl pyrophosphate in the parasite, and has been previously investigated for its key role as a novel drug target in some species, encompassing Plasmodia, Mycobacteria and Escherichia coli. In this study, we present the first crystal structure of T. gondii DXR (TgDXR) in a tertiary complex with the inhibitor fosmidomycin and the cofactor NADPH in dimeric conformation at 2.5 Å resolution revealing the inhibitor binding mode. In addition, we biologically characterize reverse α-phenyl-β-thia and β-oxa fosmidomycin analogues and show that some derivatives are strong inhibitors of TgDXR which also, in contrast with fosmidomycin, inhibit the growth of T. gondii in vitro. Here, ((3,4-dichlorophenyl)((2-(hydroxy(methyl)amino)-2-oxoethyl)thio)methyl)phosphonic acid was identified as the most potent anti T. gondii compound. These findings will enable the future design and development of more potent anti-toxoplasma DXR inhibitors.
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Affiliation(s)
- Flaminia Mazzone
- Institute of Medical Microbiology and Hospital Hygiene, Heinrich Heine University, Düsseldorf, Germany
- University Hospital Düsseldorf, Düsseldorf, Germany
| | - Astrid Hoeppner
- Center for Structural Studies, Heinrich Heine University, Düsseldorf, Germany
| | - Jens Reiners
- Center for Structural Studies, Heinrich Heine University, Düsseldorf, Germany
| | - Christoph G.W. Gertzen
- Center for Structural Studies, Heinrich Heine University, Düsseldorf, Germany
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University, Düsseldorf, Germany
| | - Violetta Applegate
- Center for Structural Studies, Heinrich Heine University, Düsseldorf, Germany
| | - Mona A. Abdullaziz
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University, Düsseldorf, Germany
- National Research Centre (NRC), Dokki, Cairo, Egypt
| | - Julia Gottstein
- Institute of Biochemistry, Heinrich Heine University, Düsseldorf, Germany
| | - Daniel Degrandi
- Institute of Medical Microbiology and Hospital Hygiene, Heinrich Heine University, Düsseldorf, Germany
- University Hospital Düsseldorf, Düsseldorf, Germany
| | - Martina Wesemann
- Institute of Biochemistry, Heinrich Heine University, Düsseldorf, Germany
| | - Thomas Kurz
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University, Düsseldorf, Germany
| | - Sander H.J. Smits
- Center for Structural Studies, Heinrich Heine University, Düsseldorf, Germany
- Institute of Biochemistry, Heinrich Heine University, Düsseldorf, Germany
| | - Klaus Pfeffer
- Institute of Medical Microbiology and Hospital Hygiene, Heinrich Heine University, Düsseldorf, Germany
- University Hospital Düsseldorf, Düsseldorf, Germany
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Nayeri T, Sarvi S, Daryani A. Effective factors in the pathogenesis of Toxoplasmagondii. Heliyon 2024; 10:e31558. [PMID: 38818168 PMCID: PMC11137575 DOI: 10.1016/j.heliyon.2024.e31558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 05/11/2024] [Accepted: 05/17/2024] [Indexed: 06/01/2024] Open
Abstract
Toxoplasma gondii (T. gondii) is a cosmopolitan protozoan parasite in humans and animals. It infects about 30 % of the human population worldwide and causes potentially fatal diseases in immunocompromised hosts and neonates. For this study, five English-language databases (ScienceDirect, ProQuest, Web of Science, PubMed, and Scopus) and the internet search engine Google Scholar were searched. This review was accomplished to draw a global perspective of what is known about the pathogenesis of T. gondii and various factors affecting it. Virulence and immune responses can influence the mechanisms of parasite pathogenesis and these factors are in turn influenced by other factors. In addition to the host's genetic background, the type of Toxoplasma strain, the routes of transmission of infection, the number of passages, and different phases of parasite life affect virulence. The identification of virulence factors of the parasite could provide promising insights into the pathogenesis of this parasite. The results of this study can be an incentive to conduct more intensive research to design and develop new anti-Toxoplasma agents (drugs and vaccines) to treat or prevent this infection. In addition, further studies are needed to better understand the key agents in the pathogenesis of T. gondii.
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Affiliation(s)
- Tooran Nayeri
- Infectious and Tropical Diseases Research Center, Dezful University of Medical Sciences, Dezful, Iran
- Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran
| | - Shahabeddin Sarvi
- Department of Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Ahmad Daryani
- Department of Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
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Kong L, Jiang D, He C, Xia J, Wei H, Zhou L, Peng H. TgROP18 targets IL20RB for host-defense-related-STAT3 activation during Toxoplasma gondii infection. Parasit Vectors 2020; 13:400. [PMID: 32767999 PMCID: PMC7412674 DOI: 10.1186/s13071-020-04251-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 07/20/2020] [Indexed: 11/17/2022] Open
Abstract
Background Toxoplasma gondii is an opportunistic protozoan infecting almost one-third of the world’s population. Toxoplasma gondii rhoptry protein 18 (TgROP18) is a key virulence factor determining the parasite’s acute virulence and is secreted into host cells during infection. We previously identified the interaction of TgROP18 and host cell immune-related receptor protein IL20RB, and observed the activation of STAT3 in human keratinocytes (HaCaT) cells infected by the rop16 knockout RH strain, though TgROP16 is regarded as being responsible for host STAT3 activation during T. gondii invasion. Therefore, we hypothesize TgROP18 can activate host STAT3 through binding to IL20RB. Methods CRISPR-CAS9 technology was used to generate the ROP16 and ROP18 double knockout RH strain, RH-∆rop16∆rop18. SDS-PAGE and western blot were used to detect STAT3 activation in different HaCaT cells with high endogenous IL20RB expression treated with T. gondii tachyzoites infection, recombinant ROP18, or IL-20. FRET and co-immunoprecipitation (Co-IP) was used to detect the protein-protein interaction. Results We observed that TgROP18 was involved in a synergic activation of the host JAK/STAT3 pathway together with TgROP16 in human HaCaT cells infected with T. gondii or treated with recombinant TgROP18 protein, stimulating host proinflammatory immune responses such as expression of TNF-α. The effect of recombinant ROP18 on STAT3 phosphorylation was presented in a dose-dependent manner. Additionally, TgROP18 was identified to target IL20RB on its extracellular domain. When we treated different cell lines with the recombinant ROP18, STAT3 phosphorylation could only be observed in the cells with endogenous IL20RB expression, such as HaCaT cells. Conclusions These findings indicate that TgROP18-IL20RB interaction upon T. gondii invasion was involved in STAT3 activation, which is associated with host cell defense.![]()
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Affiliation(s)
- Ling Kong
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, Guangdong Province, China
| | - Dan Jiang
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, Guangdong Province, China
| | - Cheng He
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, Guangdong Province, China
| | - Jing Xia
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, Guangdong Province, China
| | - Haixia Wei
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, Guangdong Province, China
| | - Lijuan Zhou
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, Guangdong Province, China
| | - Hongjuan Peng
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, Guangdong Province, China.
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Rousseau A, La Carbona S, Dumètre A, Robertson LJ, Gargala G, Escotte-Binet S, Favennec L, Villena I, Gérard C, Aubert D. Assessing viability and infectivity of foodborne and waterborne stages (cysts/oocysts) of Giardia duodenalis, Cryptosporidium spp., and Toxoplasma gondii: a review of methods. ACTA ACUST UNITED AC 2018; 25:14. [PMID: 29553366 PMCID: PMC5858526 DOI: 10.1051/parasite/2018009] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 02/09/2018] [Indexed: 11/14/2022]
Abstract
Giardia duodenalis, Cryptosporidium spp. and Toxoplasma gondii are protozoan parasites that have been highlighted as emerging foodborne pathogens by the Food and Agriculture Organization of the United Nations and the World Health Organization. According to the European Food Safety Authority, 4786 foodborne and waterborne outbreaks were reported in Europe in 2016, of which 0.4% were attributed to parasites including Cryptosporidium, Giardia and Trichinella. Until 2016, no standardized methods were available to detect Giardia, Cryptosporidium and Toxoplasma (oo)cysts in food. Therefore, no regulation exists regarding these biohazards. Nevertheless, considering their low infective dose, ingestion of foodstuffs contaminated by low quantities of these three parasites can lead to human infection. To evaluate the risk of protozoan parasites in food, efforts must be made towards exposure assessment to estimate the contamination along the food chain, from raw products to consumers. This requires determining: (i) the occurrence of infective protozoan (oo)cysts in foods, and (ii) the efficacy of control measures to eliminate this contamination. In order to conduct such assessments, methods for identification of viable (i.e. live) and infective parasites are required. This review describes the methods currently available to evaluate infectivity and viability of G. duodenalis cysts, Cryptosporidium spp. and T. gondii oocysts, and their potential for application in exposure assessment to determine the presence of the infective protozoa and/or to characterize the efficacy of control measures. Advantages and limits of each method are highlighted and an analytical strategy is proposed to assess exposure to these protozoa.
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Affiliation(s)
- Angélique Rousseau
- EA 3800, Protozooses transmises par l'alimentation, Laboratoire de Parasitologie Mycologie, Université de Reims Champagne Ardenne, Faculté de Médecine, SFR Cap Santé Fed 4231, 51 Rue Cognacq Jay, 51096 Reims, France - ACTALIA Food Safety Department, 310 Rue Popielujko, 50000 Saint-Lô, France - EA 3800, Protozooses transmises par l'alimentation, Laboratoire de Parasitologie Mycologie, Université de Rouen, 76183 Rouen Cedex, France
| | | | - Aurélien Dumètre
- Aix Marseille Univ, IRD (Dakar, Marseille, Papeete), AP-HM, IHU-Méditerranée Infection, UMR Vecteurs - Infections Tropicales et Méditerranéennes (VITROME), Marseille, France
| | - Lucy J Robertson
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, PO Box 8146 Dep., 0033, Oslo, Norway
| | - Gilles Gargala
- EA 3800, Protozooses transmises par l'alimentation, Laboratoire de Parasitologie Mycologie, Université de Rouen, 76183 Rouen Cedex, France
| | - Sandie Escotte-Binet
- EA 3800, Protozooses transmises par l'alimentation, Laboratoire de Parasitologie Mycologie, Université de Reims Champagne Ardenne, Faculté de Médecine, SFR Cap Santé Fed 4231, 51 Rue Cognacq Jay, 51096 Reims, France
| | - Loïc Favennec
- EA 3800, Protozooses transmises par l'alimentation, Laboratoire de Parasitologie Mycologie, Université de Rouen, 76183 Rouen Cedex, France
| | - Isabelle Villena
- EA 3800, Protozooses transmises par l'alimentation, Laboratoire de Parasitologie Mycologie, Université de Reims Champagne Ardenne, Faculté de Médecine, SFR Cap Santé Fed 4231, 51 Rue Cognacq Jay, 51096 Reims, France
| | - Cédric Gérard
- Food Safety Microbiology, Nestlé Research Center, PO Box 44, CH-1000 Lausanne 26, Switzerland
| | - Dominique Aubert
- EA 3800, Protozooses transmises par l'alimentation, Laboratoire de Parasitologie Mycologie, Université de Reims Champagne Ardenne, Faculté de Médecine, SFR Cap Santé Fed 4231, 51 Rue Cognacq Jay, 51096 Reims, France
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5
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Chen XQ, Zhou CX, Elsheikha HM, He S, Hu GX, Zhu XQ. Profiling of the perturbed metabolomic state of mouse spleen during acute and chronic toxoplasmosis. Parasit Vectors 2017; 10:339. [PMID: 28720125 PMCID: PMC5516376 DOI: 10.1186/s13071-017-2282-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 07/10/2017] [Indexed: 01/13/2023] Open
Abstract
Background Toxoplasma gondii, a common opportunistic protozoan, is a leading cause of illness and mortality among immunosuppressed individuals and during congenital infections. Current therapeutic strategies for toxoplasmosis are not fully effective at curtailing disease progression in these cases. Given the parasite ability to influence host immunity and metabolism, understanding of the metabolic alterations in the host’s immune organs during T. gondii infection may enhance the understanding of the molecular mechanisms that define the pathophysiology of T. gondii infection. Methods We investigated the global metabolic changes in the spleen of BALB/c mice at early and late stage of infection with T. gondii using LC-MS/MS-based metabolomics. Multivariate data analysis methods, principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA), were used to identify metabolites that are influenced by T. gondii infection. Results Multivariate analyses clearly separated the metabolites of spleen of infected and control mice. A total of 132 differential metabolites were identified, 23 metabolites from acutely infected versus control mice and 109 metabolites from chronically infected versus control mice. Lipids, hormones, lactones, acids, peptides, antibiotics, alkaloids and natural toxins were the most influenced chemical groups. There were 12 shared differential metabolites between acutely infected versus control mice and chronically infected versus control mice, of which 4,4-Dimethyl-5alpha-cholesta-8,14,24-trien-3beta-ol was significantly upregulated and ubiquinone-8 was significantly downregulated. Major perturbed metabolic pathways included primary bile acid biosynthesis, steroid hormone biosynthesis, biotin metabolism, and steroid biosynthesis, with arachidonic acid metabolism being the most significantly impacted pathway. These metabolic changes suggest a multifactorial nature of the immunometabolic responses of mouse spleen to T. gondii infection. Conclusions This study demonstrated that T. gondii infection can cause significant metabolomic alterations in the spleen of infected mice. These findings provide new insights into the molecular mechanisms that underpin the pathogenesis of T. gondii infection. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2282-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiao-Qing Chen
- Department of Veterinary Medicine, College of Animal Science and Technology, Jilin Agricultural University, Changchun, Jilin Province, 130118, People's Republic of China.,State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, 730046, People's Republic of China
| | - Chun-Xue Zhou
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, 730046, People's Republic of China.,Department of Parasitology, Shandong University School of Basic Medicine, Jinan, Shandong Province, 250012, People's Republic of China
| | - Hany M Elsheikha
- Faculty of Medicine and Health Sciences, School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
| | - Shuai He
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, 730046, People's Republic of China.,College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui Province, 230036, People's Republic of China
| | - Gui-Xue Hu
- Department of Veterinary Medicine, College of Animal Science and Technology, Jilin Agricultural University, Changchun, Jilin Province, 130118, People's Republic of China.
| | - Xing-Quan Zhu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, 730046, People's Republic of China.
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6
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Mokua Mose J, Muchina Kamau D, Kagira JM, Maina N, Ngotho M, Njuguna A, Karanja SM. Development of Neurological Mouse Model for Toxoplasmosis Using Toxoplasma gondii Isolated from Chicken in Kenya. PATHOLOGY RESEARCH INTERNATIONAL 2017; 2017:4302459. [PMID: 28630781 PMCID: PMC5463144 DOI: 10.1155/2017/4302459] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 04/19/2017] [Indexed: 11/17/2022]
Abstract
Animal models for the toxoplasmosis are scarce and have limitations. In this study, a neurological mouse model was developed in BALB/c mice infected intraperitoneally with 15 cysts of a Toxoplasma gondii isolate. The mice were monitored for 42 days and euthanized at different time points. Another group of mice were orally treated with dexamethasone (DXM: 2.66 mg/kg daily, 5.32 mg/kg daily) at 42 days after infection and monitored for a further 42 days. A mortality rate of 15% and 28.6% was observed in mice given 2.66 mg/kg/day and 5.32 mg/kg/day of DXM, respectively. The mean cyst numbers in the brain of DXM treated mice increased up to twofold compared with chronically infected untreated mice. Infections up to 42 days were associated with an increase in both IgM and IgG levels but following dexamethasone treatment, IgM levels declined but IgG levels continued on rising. The brain of toxoplasmosis infected mice showed mononuclear cellular infiltrations, neuronal necrosis, and cuffing. The severity of pathology was higher in mice treated with dexamethasone compared to the positive control groups. The findings of this study demonstrate that DXM-induced reactivation of chronic toxoplasmosis may be a useful development of laboratory animal model in outbred mice used for in vivo studies.
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Affiliation(s)
- John Mokua Mose
- Department of Medical Laboratory Science, School of Medicine and Health Sciences, Kenya Methodist University, P.O. Box 45240-00100, Nairobi, Kenya
- Department of Public Health, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000-00200, Nairobi, Kenya
| | - David Muchina Kamau
- Department of Public Health, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000-00200, Nairobi, Kenya
| | - John Maina Kagira
- Department of Animal Sciences, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000-00200, Nairobi, Kenya
| | - Naomi Maina
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000-00200, Nairobi, Kenya
| | - Maina Ngotho
- Department of Animal Health & Production, Mount Kenya University, P.O. Box 342-01000, Thika 342-01000, Kenya
| | - Adele Njuguna
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000-00200, Nairobi, Kenya
| | - Simon Muturi Karanja
- Department of Public Health, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000-00200, Nairobi, Kenya
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Abstract
Report of the Working Group on Hygiene of the Gesellschaft für Versuchstierkunde–Society for Laboratory Animal Science (GV-SOLAS) GV-SOLAS Working Group on Hygiene: Werner Nicklas (Chairman), Felix R. Homberger, Brunhilde Illgen-Wilcke, Karin Jacobi, Volker Kraft, Ivo Kunstyr, Michael Mähler, Herbert Meyer & Gabi Pohlmeyer-Esch
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Almería S, López-Gatius F. Bovine neosporosis: clinical and practical aspects. Res Vet Sci 2013; 95:303-9. [PMID: 23659742 DOI: 10.1016/j.rvsc.2013.04.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 03/30/2013] [Accepted: 04/02/2013] [Indexed: 11/16/2022]
Abstract
Neospora caninum is a protozoan parasite with a wide host range but with a preference for cattle and dogs. Since the description of N. caninum as a new genus and species in 1988, bovine neosporosis has become a disease of international concern as it is among the main causes of abortion in cattle. At present there is no effective treatment or vaccine. This review focuses on the epidemiology of the disease and on prospects for its control in cattle. Finally, based on the implications of clinical findings reported to date, a set of recommendations is provided for veterinarians and cattle farmers.
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Affiliation(s)
- S Almería
- Departament de Sanitat i Anatomia Animals and Centre de Recerca en Sanitat Animal (CreSA), Universitat Autònoma de Barcelona-IRTA, Bellaterra, Barcelona, Spain.
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Hunter CA, Sibley LD. Modulation of innate immunity by Toxoplasma gondii virulence effectors. Nat Rev Microbiol 2013; 10:766-78. [PMID: 23070557 DOI: 10.1038/nrmicro2858] [Citation(s) in RCA: 365] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Toxoplasma gondii is a common parasite of animals and humans and can cause serious opportunistic infections. However, the majority of infections are asymptomatic, possibly because the organism has co-evolved with its many vertebrate hosts and has developed multiple strategies to persist asymptomatically for the lifetime of the host. Over the past two decades, infection studies in the mouse, combined with forward-genetics approaches aimed at unravelling the molecular basis of infection, have revealed that T. gondii virulence is mediated, in part, by secretion of effector proteins into the host cell during invasion. Here, we review recent advances that illustrate how these virulence factors disarm innate immunity and promote survival of the parasite.
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Affiliation(s)
- Christopher A Hunter
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104, USA.
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10
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Immune response and immunopathology during toxoplasmosis. Semin Immunopathol 2012; 34:793-813. [PMID: 22955326 DOI: 10.1007/s00281-012-0339-3] [Citation(s) in RCA: 229] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Accepted: 08/21/2012] [Indexed: 12/18/2022]
Abstract
Toxoplasma gondii is a protozoan parasite of medical and veterinary significance that is able to infect any warm-blooded vertebrate host. In addition to its importance to public health, several inherent features of the biology of T. gondii have made it an important model organism to study host-pathogen interactions. One factor is the genetic tractability of the parasite, which allows studies on the microbial factors that affect virulence and allows the development of tools that facilitate immune studies. Additionally, mice are natural hosts for T. gondii, and the availability of numerous reagents to study the murine immune system makes this an ideal experimental system to understand the functions of cytokines and effector mechanisms involved in immunity to intracellular microorganisms. In this article, we will review current knowledge of the innate and adaptive immune responses required for resistance to toxoplasmosis, the events that lead to the development of immunopathology, and the natural regulatory mechanisms that limit excessive inflammation during this infection.
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Subauste C. Animal models for Toxoplasma gondii infection. CURRENT PROTOCOLS IN IMMUNOLOGY 2012; Chapter 19:19.3.1-19.3.23. [PMID: 22314833 DOI: 10.1002/0471142735.im1903s96] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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.
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Affiliation(s)
- Carlos Subauste
- Case Western Reserve University School of Medicine, Cleveland, Ohio
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12
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Ware MW, Augustine SAJ, Erisman DO, See MJ, Wymer L, Hayes SL, Dubey JP, Villegas EN. Determining UV inactivation of Toxoplasma gondii oocysts by using cell culture and a mouse bioassay. Appl Environ Microbiol 2010; 76:5140-7. [PMID: 20543052 PMCID: PMC2916465 DOI: 10.1128/aem.00153-10] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Accepted: 05/30/2010] [Indexed: 01/06/2023] Open
Abstract
The effect of UV exposure on Toxoplasma gondii oocysts has not been completely defined for use in water disinfection. This study evaluated UV-irradiated oocysts by three assays: a SCID mouse bioassay, an in vitro T. gondii oocyst plaque (TOP) assay, and a quantitative reverse transcriptase real-time PCR (RT-qPCR) assay. The results from the animal bioassay show that 1- and 3-log(10) inactivation is achieved with 4 mJ/cm(2) UV and 10 mJ/cm(2) low-pressure UV, respectively. TOP assay results, but not RT-qPCR results, correlate well with bioassay results. In conclusion, a 3-log(10) inactivation of T. gondii oocysts is achieved by 10-mJ/cm(2) low-pressure UV, and the in vitro TOP assay is a promising alternative to the mouse bioassay.
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Affiliation(s)
- Michael W. Ware
- National Exposure Research Laboratory, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, Department of Biological Sciences, McMicken College of Arts and Sciences, University of Cincinnati, Cincinnati, Ohio 45220, Animal Parasitic Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705
| | - Swinburne A. J. Augustine
- National Exposure Research Laboratory, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, Department of Biological Sciences, McMicken College of Arts and Sciences, University of Cincinnati, Cincinnati, Ohio 45220, Animal Parasitic Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705
| | - David O. Erisman
- National Exposure Research Laboratory, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, Department of Biological Sciences, McMicken College of Arts and Sciences, University of Cincinnati, Cincinnati, Ohio 45220, Animal Parasitic Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705
| | - Mary Jean See
- National Exposure Research Laboratory, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, Department of Biological Sciences, McMicken College of Arts and Sciences, University of Cincinnati, Cincinnati, Ohio 45220, Animal Parasitic Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705
| | - Larry Wymer
- National Exposure Research Laboratory, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, Department of Biological Sciences, McMicken College of Arts and Sciences, University of Cincinnati, Cincinnati, Ohio 45220, Animal Parasitic Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705
| | - Samuel L. Hayes
- National Exposure Research Laboratory, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, Department of Biological Sciences, McMicken College of Arts and Sciences, University of Cincinnati, Cincinnati, Ohio 45220, Animal Parasitic Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705
| | - J. P. Dubey
- National Exposure Research Laboratory, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, Department of Biological Sciences, McMicken College of Arts and Sciences, University of Cincinnati, Cincinnati, Ohio 45220, Animal Parasitic Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705
| | - Eric N. Villegas
- National Exposure Research Laboratory, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, Department of Biological Sciences, McMicken College of Arts and Sciences, University of Cincinnati, Cincinnati, Ohio 45220, Animal Parasitic Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705
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13
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Couper KN, Lanthier PA, Perona-Wright G, Kummer LW, Chen W, Smiley ST, Mohrs M, Johnson LL. Anti-CD25 antibody-mediated depletion of effector T cell populations enhances susceptibility of mice to acute but not chronic Toxoplasma gondii infection. THE JOURNAL OF IMMUNOLOGY 2009; 182:3985-94. [PMID: 19299696 DOI: 10.4049/jimmunol.0803053] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Natural regulatory T cells (Tregs) constitutively express the IL-2R alpha-chain (CD25) on their surface. Consequently, administration of anti-CD25 Abs is a commonly used technique to deplete Treg populations in vivo. However, activated effector T cells may also transiently express CD25, and are thus also potential targets for anti-CD25 Abs. In this study using Toxoplasma gondii as a model proinflammatory infection, we have examined the capacity of anti-CD25 Abs to target effector T cell populations during an inflammatory episode, to determine to what extent that this action may modulate the outcome of disease. Anti-CD25 Ab-treated C57BL/6 mice displayed significantly reduced CD4(+) T cell IFN-gamma production during acute T. gondii infection and exhibited reduced weight loss and liver pathology during early acute infection; aspects of infection previously associated with effector CD4(+) T cell responses. In agreement, anti-CD25 Ab administration impaired parasite control and caused mice to succumb to infection during late acute/early chronic stages of infection with elevated tissue parasite burdens. In contrast, anti-CD25 Ab treatment of mice with established chronic infections did not markedly affect brain parasite burdens, suggesting that protective T cell populations do not express CD25 during chronic stages of T. gondii infection. In summary, we have demonstrated that anti-CD25 Abs may directly abrogate effector T cell responses during an inflammatory episode, highlighting important limitations of the use of anti-CD25 Ab administration to examine Treg function during inflammatory settings.
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14
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Sweeney E, Campbell M, Watkins K, Hunter CA, Jacenko O. Altered endochondral ossification in collagen X mouse models leads to impaired immune responses. Dev Dyn 2008; 237:2693-704. [PMID: 18629872 DOI: 10.1002/dvdy.21594] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Disruption of collagen X function in hypertrophic cartilage undergoing endochondral ossification was previously linked to altered hematopoiesis in collagen X transgenic (Tg) and null (KO) mice (Jacenko et al., [2002] Am J Pathol 160:2019-2034). Mice displayed altered growth plates, diminished trabecular bone, and marrow hypoplasia with an aberrant lymphocyte profile throughout life. This study identifies altered B220+, CD4+, and CD8+ lymphocyte numbers, as well as CD4+/fox3P+ T regulatory cells in the collagen X mice. Additionally, diminished in vitro splenocyte responses to mitogens and an inability of mice to survive a challenge with Toxoplasma gondii, confirm impaired immune responses. In concert, ELISA and protein arrays identify aberrant levels of inflammatory, chemo-attractant, and matrix binding cytokines in collagen X mouse sera. These data link the disruption of collagen X function in the chondro-osseous junction to an altered hematopoietic stem cell niche in the marrow, resulting in impaired immune function.
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Affiliation(s)
- E Sweeney
- Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania 19104-6046, USA
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15
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16
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Subauste C, Remington J. Animal models for Toxoplasma gondii infection. CURRENT PROTOCOLS IN IMMUNOLOGY 2008; Chapter 19:Unit 19.3. [PMID: 18432754 DOI: 10.1002/0471142735.im1903s28] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Toxoplasma gondii is an obligate intracellular protozoan that commonly infects mammals and birds throughout the world. This unit describes murine models of acute T. gondii infection and toxoplasmic encephalitis. T. gondii infection in severe combined immunodeficient (SCID) mice, which lack T and B cells, has allowed for the study of T cell-independent mechanisms of defense against intracellular organisms, as described here. The establishment of temperature-sensitive mutant strains of T. gondii has allowed adoptive-transfer experiments without the concern for the transfer of the parasite at the same time. The temperature-sensitive mutant ts-4 strain disappears from tissues of immunocompetent mice without forming tissue cysts and induces protection against challenge with virulent strains of the parasite, and a protocol is provided for infection with this mutant strain. Support protocols present methodology for evaluation of progression of infection and immune response to the parasite, maintenance of T. gondii tissue cysts and tachyzoites, as well as preparation of T. gondii lysate antigens.
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Affiliation(s)
- C Subauste
- University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
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17
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Khan IA, Thomas SY, Moretto MM, Lee FS, Islam SA, Combe C, Schwartzman JD, Luster AD. CCR5 is essential for NK cell trafficking and host survival following Toxoplasma gondii infection. PLoS Pathog 2006; 2:e49. [PMID: 16789839 PMCID: PMC1475660 DOI: 10.1371/journal.ppat.0020049] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Accepted: 04/12/2006] [Indexed: 11/18/2022] Open
Abstract
The host response to intracellular pathogens requires the coordinated action of both the innate and acquired immune systems. Chemokines play a critical role in the trafficking of immune cells and transitioning an innate immune response into an acquired response. We analyzed the host response of mice deficient in the chemokine receptor CCR5 following infection with the intracellular protozoan parasite Toxoplasma gondii. We found that CCR5 controls recruitment of natural killer (NK) cells into infected tissues. Without this influx of NK cells, tissues from CCR5-deficient (CCR5-/-) mice were less able to generate an inflammatory response, had decreased chemokine and interferon gamma production, and had higher parasite burden. As a result, CCR5-/- mice were more susceptible to infection with T. gondii but were less susceptible to the immune-mediated tissue injury seen in certain inbred strains. Adoptive transfer of CCR5+/+ NK cells into CCR5-/- mice restored their ability to survive lethal T. gondii infection and demonstrated that CCR5 is required for NK cell homing into infected liver and spleen. This study establishes CCR5 as a critical receptor guiding NK cell trafficking in host defense.
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Affiliation(s)
- Imtiaz A Khan
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Medical Center, New Orleans, Louisiana, United States of America
- * To whom correspondence should be addressed. E-mail: (IAK); (ADL)
| | - Seddon Y Thomas
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy, and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Magali M Moretto
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Medical Center, New Orleans, Louisiana, United States of America
| | - Frederick S Lee
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy, and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Sabina A Islam
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy, and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Crescent Combe
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Medical Center, New Orleans, Louisiana, United States of America
| | - Joseph D Schwartzman
- Department of Pathology, Dartmouth Medical School, Lebanon, New Hampshire, United States of America
| | - Andrew D Luster
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy, and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- * To whom correspondence should be addressed. E-mail: (IAK); (ADL)
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18
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Subauste CS, Wessendarp M. CD40 restrains in vivo growth of Toxoplasma gondii independently of gamma interferon. Infect Immun 2006; 74:1573-9. [PMID: 16495528 PMCID: PMC1418638 DOI: 10.1128/iai.74.3.1573-1579.2006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD40-CD154 interaction is pivotal for resistance against numerous pathogens. However, it is not known if this pathway can also enhance in vivo resistance in gamma interferon (IFN-gamma)-deficient hosts. This is an important question because patients and mice with defects in type 1 cytokine response can control a variety of pathogens. While blockade of endogenous CD154 resulted in a remarkable increase in parasite load in IFN-gamma-/- mice infected with Toxoplasma gondii, in vivo administration of a stimulatory anti-CD40 monoclonal antibody markedly reduced parasite load. This latter effect took place even in T-cell-depleted mice and was accompanied by induction of macrophage toxoplasmacidal activity. CD40 stimulation restricted T. gondii replication independently of STAT1, p47 GTPases, and nitric oxide. In vivo CD40 ligation enhanced tumor necrosis factor alpha (TNF-alpha) production by T. gondii-infected macrophages. In addition, CD40 stimulation required the presence of TNF receptor 2 to reduce parasite load in vivo. These results suggest that CD40-CD154 interaction regulates IFN-gamma-independent mechanisms of host protection through induction of macrophage antimicrobial activity and modulation of TNF-alpha signaling.
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Affiliation(s)
- Carlos S Subauste
- Department of Internal Medicine, University of Cincinnati College of Medicine, P.O. Box 670560, Cincinnati, OH 45267-0560, USA.
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19
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Couper KN, Roberts CW, Brombacher F, Alexander J, Johnson LL. Toxoplasma gondii-specific immunoglobulin M limits parasite dissemination by preventing host cell invasion. Infect Immun 2006; 73:8060-8. [PMID: 16299300 PMCID: PMC1307022 DOI: 10.1128/iai.73.12.8060-8068.2005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An important role for immunoglobulin M (IgM) during early acute virulent Toxoplasma gondii infection was identified using IgM-/- mice that lack surface and secretory IgM but maintain normal B-cell functionality and isotype class switching. Following intraperitoneal inoculation with the virulent RH strain, IgM-/- mice displayed significantly fewer peritoneal parasites than wild-type (WT) mice, which correlated with increased tachyzoite dissemination to the liver, lung, and spleen in IgM-/- mice compared with WT mice. Early splenic T-cell activation, as measured by CD69 expression, was augmented in IgM-/- mice, and serum and peritoneal cavity gamma interferon levels were also elevated in IgM-/- mice compared with WT controls. Consequently, the difference in parasite dissemination was not attributable to an impaired proinflammatory immune response in the IgM-/- mice. Specific IgM was found to bind to tachyzoites in vivo in WT mice, and this correlated with an increased ability of antiserum collected from WT mice at day 6 postinfection to block tachyzoite cell invasion, compared with comparable serum collected from IgM-/- mice at the same time point. Tachyzoite invasion of host cells was similar if parasites were incubated with WT or IgM-/- nonimmune serum, suggesting that natural IgM does not function to limit parasite dissemination during early T. gondii infection. Our results highlight an important role for parasite-specific IgM in limiting systemic dissemination of tachyzoites during early acute T. gondii infection.
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Affiliation(s)
- Kevin N Couper
- Department of Immunology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, United Kingdom
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20
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Smiley ST, Lanthier PA, Couper KN, Szaba FM, Boyson JE, Chen W, Johnson LL. Exacerbated susceptibility to infection-stimulated immunopathology in CD1d-deficient mice. THE JOURNAL OF IMMUNOLOGY 2005; 174:7904-11. [PMID: 15944296 PMCID: PMC3010175 DOI: 10.4049/jimmunol.174.12.7904] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mice lacking functional CD1d genes were used to study mechanisms of resistance to the protozoan parasite Toxoplasma gondii. Wild-type (WT) BALB/c mice, CD1d-deficient BALB/c mice, and WT C57BL/6 mice all survived an acute oral infection with a low dose of mildly virulent strain ME49 T. gondii cysts. In contrast, most CD1d-deficient C57BL/6 mice died within 2 wk of infection. Despite having parasite burdens that were only slightly higher than WT mice, CD1d-deficient C57BL/6 mice displayed greater weight loss and intestinal pathology. In C57BL/6 mice, CD4(+) cells can cause intestinal pathology during T. gondii infection. Compared with WT mice, infected CD1d-deficient C57BL/6 mice had higher frequencies and numbers of activated (CD44(high)) CD4(+) cells in mesenteric lymph nodes. Depletion of CD4(+) cells from CD1d-deficient mice reduced weight loss and prolonged survival, demonstrating a functional role for CD4(+) cells in their increased susceptibility to T. gondii infection. CD1d-deficient mice are deficient in Valpha14(+) T cells, a major population of NKT cells. Involvement of these cells in resistance to T. gondii was investigated using gene-targeted Jalpha18-deficient C57BL/6 mice, which are deficient in Valpha14(+) T cells. These mice did not succumb to acute infection, but experienced greater weight loss and more deaths than B6 mice during chronic infection, indicating that Valpha14(+) cells contribute to resistance to T. gondii. The data identify CD4(+) cells as a significant component of the marked susceptibility to T. gondii infection observed in CD1d-deficient C57BL/6 mice, and establish T. gondii as a valuable tool for deciphering CD1d-dependent protective mechanisms.
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MESH Headings
- Acute Disease
- Administration, Oral
- Animals
- Antibodies, Monoclonal/administration & dosage
- Antibodies, Monoclonal/therapeutic use
- Antigens, CD1/biosynthesis
- Antigens, CD1/genetics
- Antigens, CD1/physiology
- Antigens, CD1d
- Antigens, Protozoan/administration & dosage
- Antigens, Protozoan/immunology
- CD4 Antigens/immunology
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CD4-Positive T-Lymphocytes/parasitology
- Genetic Predisposition to Disease/genetics
- Immunity, Innate/genetics
- Intestinal Diseases, Parasitic/genetics
- Intestinal Diseases, Parasitic/immunology
- Intestinal Diseases, Parasitic/pathology
- Intestinal Mucosa/immunology
- Intestinal Mucosa/pathology
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Receptors, Antigen, T-Cell, alpha-beta/deficiency
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Toxoplasma/growth & development
- Toxoplasma/immunology
- Toxoplasma/pathogenicity
- Toxoplasmosis, Animal/genetics
- Toxoplasmosis, Animal/immunology
- Toxoplasmosis, Animal/pathology
- Toxoplasmosis, Animal/therapy
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Affiliation(s)
| | | | - Kevin N. Couper
- Trudeau Institute, Inc. 154 Algonquin Ave. Saranac Lake, NY 12983
| | - Frank M. Szaba
- Trudeau Institute, Inc. 154 Algonquin Ave. Saranac Lake, NY 12983
| | - Jonathan E. Boyson
- Department of Surgery, Division of Transplantation Surgery and Immunology, University of Vermont, Burlington, VT, 05405
| | - Wangxue Chen
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, ON K1A0RG, Canada
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21
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Combe CL, Curiel TJ, Moretto MM, Khan IA. NK cells help to induce CD8(+)-T-cell immunity against Toxoplasma gondii in the absence of CD4(+) T cells. Infect Immun 2005; 73:4913-21. [PMID: 16041005 PMCID: PMC1201207 DOI: 10.1128/iai.73.8.4913-4921.2005] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD8(+) T-cell immunity plays an important role in protection against intracellular infections. Earlier studies have shown that CD4(+) T-cell help was needed for launching in vivo CD8(+) T-cell activity against these pathogens and tumors. However, recently CD4(+) T-cell-independent CD8 responses during several microbial infections including those with Toxoplasma gondii have been described, although the mechanism is not understood. We now demonstrate that, in the absence of CD4(+) T cells, T. gondii-infected mice exhibit an extended NK cell response, which is mediated by continued interleukin-12 (IL-12) secretion. This prolonged NK cell response is critical for priming parasite-specific CD8(+) T-cell immunity. Depletion of NK cells inhibited the generation of CD8(+) T-cell immunity in CD4(-/-) mice. Similarly neutralization of IL-12 reduces NK cell numbers in infected animals and leads to the down-regulation of CD8(+) T-cell immunity against T. gondii. Adoptive transfer of NK cells into the IL-12-depleted animals restored their CD8(+) T-cell immune response, and animals exhibited reduced mortality. NK cell gamma interferon was essential for cytotoxic T-lymphocyte priming. Our studies for the first time demonstrate that, in the absence of CD4(+) T cells, NK cells can play an important role in induction of primary CD8(+) T-cell immunity against an intracellular infection. These observations have therapeutic implications for immunocompromised individuals, including those with human immunodeficiency virus infection.
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Affiliation(s)
- Crescent L Combe
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, 1901 Perdido Street, New Orleans, LA 70112, USA
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22
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López-Gatius F, García-Ispierto I, Santolaria P, Yániz JL, López-Béjar M, Nogareda C, Almería S. Relationship between rainfall and Neospora caninum-associated abortion in two dairy herds in a dry environment. ACTA ACUST UNITED AC 2005; 52:147-52. [PMID: 15876229 DOI: 10.1111/j.1439-0450.2005.00831.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The possible direct relationship between climate variations and abortion in Neospora caninum-infected cows has not been studied. The objective of this study was to determine whether climate changes could be a risk factor for abortion in N. caninum-infected cows, and was based on yearly serological screening for neosporosis and on the confirmation of N. caninum infection on aborted fetuses in two high-producing dairy herds with a mean 27% seroprevalence of N. caninum antibodies. The final population study was comprised of 357 pregnancies in seropositive animals. Logistic regression analysis indicated no significant effects of herd, N. caninum antibody titre, climate variables during the first and third trimesters of gestation, mean and maximum temperature-humidity index values during the second trimester of gestation, and previous abortion on the abortion rate. Based on the odds ratio, a 1-unit increase in lactation number yielded a 0.85-fold decrease in the abortion rate. The likelihood of abortion was 1.9 times (1/0.54) lower for pregnant cows inseminated with beef bull semen compared with Holstein-Friesian bull semen. The likelihood of abortion decreased significant and progressively by factors of 0.5, 0.41 and 0.3 for the respective classes 40-49, 30-39 and <30 rainfall mm during the second trimester of gestation (using the class >or=60 rainfall mm as reference). As a general conclusion, it seems that increased rainfall in a dry environment can compromise the success of gestation in N. caninum-infected cows. Attempts should therefore be made to reduce environment effects during the second trimester of gestation, a period in which the immune response of cows is diminished.
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Affiliation(s)
- F López-Gatius
- Department of Animal Production, University of Lleida, Escuela Técnica Superior de Ingeniería Agraria, Avda. Rovira Roure 177, 25198 Lleida, Spain.
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23
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Pepper M, Dzierszinski F, Crawford A, Hunter CA, Roos D. Development of a system to study CD4+-T-cell responses to transgenic ovalbumin-expressing Toxoplasma gondii during toxoplasmosis. Infect Immun 2004; 72:7240-6. [PMID: 15557649 PMCID: PMC529136 DOI: 10.1128/iai.72.12.7240-7246.2004] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The study of the immune response to Toxoplasma gondii has provided numerous insights into the role of T cells in resistance to intracellular infections. However, the complexity of this eukaryote pathogen has made it difficult to characterize immunodominant epitopes that would allow the identification of T cells with a known specificity for parasite antigens. As a consequence, analysis of T-cell responses to T. gondii has been based on characterization of the percentage of T cells that express an activated phenotype during infection and on the ability of these cells to produce cytokines in response to complex mixtures of parasite antigens. In order to study specific CD4(+) T cells responses to T. gondii, recombinant parasites that express a truncated ovalbumin (OVA) protein, in either a cytosolic or a secreted form, were engineered. In vitro and in vivo studies reveal that transgenic parasites expressing secreted OVA are able to stimulate T-cell receptor-transgenic OVA-specific CD4(+) T cells to proliferate, express an activated phenotype, and produce gamma interferon (IFN-gamma). Furthermore, the adoptive transfer of OVA-specific T cells into IFN-gamma(-/-) mice provided enhanced protection against infection with the OVA-transgenic (but not parental) parasites. Together, these studies establish the utility of this transgenic system to study CD4(+)-T-cell responses during toxoplasmosis.
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Affiliation(s)
- Marion Pepper
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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24
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Alfonzo M, Blanc D, Troadec C, Huerre M, Eliaszewicz M, Gónzalez G, Koyanagi Y, Scott-Algara D. Temporary restoration of immune response against Toxoplasma gondii in HIV-infected individuals after HAART, as studied in the hu-PBMC-SCID mouse model. Clin Exp Immunol 2002; 129:411-9. [PMID: 12197881 PMCID: PMC1906477 DOI: 10.1046/j.1365-2249.2002.01941.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We studied immune reconstitution against the parasite T. gondii in HIV-infected patients treated for 1 years with highly active antiretroviral therapy (HAART). We used SCID mice, humanized with peripheral blood mononuclear cells (PBMC) from patients, which were then infected with T. gondii cysts. Mice humanized with PBMC from patients before the start of HAART were highly susceptible to infection. In contrast, mice humanized with PBMC from patients who had received HAART for 6 months displayed higher survival rates, correlating with lower intracerebral parasite loads. However, this resistance was lost during follow up because mice humanized with PBMC from patients treated with HAART for 12 months survived for no longer than mice that had not been humanized. Specific lymphocyte proliferation assays showed that the increase in proliferative response depended on treatment duration and that HAART induced changes in IFN-gamma secretion in the presence of Toxoplasma antigens. Thus, our results indicate partial immune reconstitution against T. gondii in HIV-infected patients following HAART, possibly due to changes in the patterns of specific IFN-gamma production and redistribution of functional memory CD4+ cells.
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Affiliation(s)
- M Alfonzo
- Unité d'Immuno-Hématologie et d'Immunopathologie, Institut Pasteur, Paris, France
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25
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Casciotti L, Ely KH, Williams ME, Khan IA. CD8(+)-T-cell immunity against Toxoplasma gondii can be induced but not maintained in mice lacking conventional CD4(+) T cells. Infect Immun 2002; 70:434-43. [PMID: 11796568 PMCID: PMC127655 DOI: 10.1128/iai.70.2.434-443.2002] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
T-cell immunity is critical for survival of hosts infected with Toxoplasma gondii. Among the cells in the T-cell population, CD8(+) T cells are considered the major effector cells against this parasite. It is believed that CD4(+) T cells may be crucial for induction of the CD8(+)-T-cell response against T. gondii. In the present study, CD4(-/-) mice were used to evaluate the role of conventional CD4(+) T cells in the immune response against T. gondii infection. CD4(-/-) mice infected with T. gondii exhibited lower gamma interferon (IFN-gamma) messages in the majority of their tissues. As a result, mortality due to a hyperinflammatory response was prevented in these animals. Interestingly, T. gondii infection induced a normal antigen-specific CD8(+)-T-cell immune response in CD4(-/-) mice. No difference in generation of precursor cytotoxic T lymphocytes (pCTL) or in IFN-gamma production by the CD8(+)-T-cell populations from the knockout and wild-type animals was observed. However, the mutant mice were not able to sustain CD8(+)-T-cell immunity. At 180 days after infection, the CD8(+)-T-cell response in the knockout mice was depressed, as determined by pCTL and IFN-gamma assays. Loss of CD8(+)-T-cell immunity at this time was confirmed by adoptive transfer experiments. Purified CD8(+) T cells from CD4(-/-) donors that had been immunized 180 days earlier failed to protect the recipient mice against a lethal infection. Our study demonstrated that although CD8(+)-T-cell immunity can be induced in the absence of conventional CD4(+) T cells, it cannot be maintained without such cells.
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Affiliation(s)
- Lori Casciotti
- Department of Medicine, Dartmouth Medical School, Lebanon, New Hampshire 03756, USA
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26
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Khan IA, Murphy PM, Casciotti L, Schwartzman JD, Collins J, Gao JL, Yeaman GR. Mice lacking the chemokine receptor CCR1 show increased susceptibility to Toxoplasma gondii infection. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:1930-7. [PMID: 11160241 DOI: 10.4049/jimmunol.166.3.1930] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Chemokines are critical for the recruitment of effector immune cells to sites of infection. Mice lacking the chemokine receptor CCR1 have defects in neutrophil trafficking and proliferation. In the present study, we tested the susceptibility of CCR1 knockout mice to infection with the obligate intracellular protozoan parasite Toxoplasma gondii. In comparison with parental wild-type mice, CCR1(-/-) mice exhibited dramatically increased mortality to T. gondii in association with an increased tissue parasite load. No differences were observed in Ag-specific T cell proliferation or in cytokine responses between mutant and wild-type mice. However, the influx of PMNs to the peripheral blood and to the liver were reduced in CCR1(-/-) mice during early infection. Our results suggest that CCR1-dependent migration of neutrophils to the blood and tissues may have a significant impact in controlling parasite replication.
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MESH Headings
- Animals
- Chemokines, CC/metabolism
- Down-Regulation/genetics
- Down-Regulation/immunology
- Female
- Genetic Predisposition to Disease
- Hepatocytes/parasitology
- Hepatocytes/pathology
- Humans
- Immune Tolerance/genetics
- Immunity, Cellular/genetics
- Leukocyte Count
- Liver/parasitology
- Liver/pathology
- Mice
- Mice, Knockout
- Necrosis
- Neutrophils/pathology
- Nitric Oxide/physiology
- Organ Specificity/genetics
- Organ Specificity/immunology
- Receptors, CCR1
- Receptors, Chemokine/deficiency
- Receptors, Chemokine/genetics
- Toxoplasma/immunology
- Toxoplasmosis, Animal/genetics
- Toxoplasmosis, Animal/immunology
- Toxoplasmosis, Animal/mortality
- Toxoplasmosis, Animal/parasitology
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Affiliation(s)
- I A Khan
- Department of Medicine, Dartmouth Medical School, Lebanon, NH 03756, USA.
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27
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Harris DP, Haynes L, Sayles PC, Duso DK, Eaton SM, Lepak NM, Johnson LL, Swain SL, Lund FE. Reciprocal regulation of polarized cytokine production by effector B and T cells. Nat Immunol 2000; 1:475-82. [PMID: 11101868 DOI: 10.1038/82717] [Citation(s) in RCA: 618] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Although B cells produce cytokines it is not known whether B cells can differentiate into effector subsets that secrete polarized arrays of cytokines. We have identified two populations of "effector" B cells (Be1 and Be2) that produce distinct patterns of cytokines depending on the cytokine environment in which the cells were stimulated during their primary encounter with antigen and T cells. These effector B cell subsets subsequently regulate the differentiation of naïve CD4+ T cells to TH1 and TH2 cells through production of polarizing cytokines such as interleukin 4 and interferon gamma. In addition, Be1 and Be2 cells could be identified in animals that were infected with pathogens that preferentially induce a Type 1 and Type 2 immune response. Together these results suggest that, in addition to their well defined role in antibody production, B cells may regulate immune responses to infectious pathogens through their production of cytokines.
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Affiliation(s)
- D P Harris
- Trudeau Institute, Saranac Lake, NY 12983, USA
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28
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Abstract
Reactivation of cerebral toxoplasmosis occurs in approximately 30% of acquired immune deficiency syndrome (AIDS) patients who are seropositive for Toxoplasma gondii and a change in the levels of cytokines during this relapse is observed. Several cytokines are able to initiate meningeal inflammation and may play a role in the immunopathogenesis of the disease. The induction of a type 1 inflammatory cytokine response is a key event in the initiation of immunity to T. gondii. Interleukin (IL)-10 production in infected brain facilitates the persistence of parasites by down-regulating the intracerebral immune response. The in vivo and in vitro models are very numerous and this may explain the heterogeneity of the results. The role of gamma interferon is important because it is the principal mediator inducing a host resistance against T. gondii. Several cytokines stimulating or decreasing interferon (IFN)-gamma levels are reported. The particular case of AIDS patients whose humoral response is altered, is studied.
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Affiliation(s)
- M E Sarciron
- Pharmaceutical Department of Parasitology and Medical Mycology, Claude-Bernard University, 8 Avenue Rockefeller, 69373 Lyon Cedex 08, France.
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29
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Khan IA, MacLean JA, Lee FS, Casciotti L, DeHaan E, Schwartzman JD, Luster AD. IP-10 is critical for effector T cell trafficking and host survival in Toxoplasma gondii infection. Immunity 2000; 12:483-94. [PMID: 10843381 DOI: 10.1016/s1074-7613(00)80200-9] [Citation(s) in RCA: 230] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The generation of an adaptive immune response against intracellular pathogens requires the recruitment of effector T cells to sites of infection. Here we show that the chemokine IP-10, a specific chemoattractant for activated T cells, controls this process in mice naturally infected with Toxoplasma gondii. Neutralization of IP-10 in infected mice inhibited the massive influx of T cells into tissues and impaired antigen-specific T cell effector functions. This resulted in >1000-fold increase in tissue parasite burden and a marked increase in mortality compared to control antibody-treated mice. These observations suggest that IP-10 may play a broader role in the localization and function of effector T cells at sites of Th1 inflammation.
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Affiliation(s)
- I A Khan
- Department of Medicine, Dartmouth Medical Center, Hanover, New Hampshire 03755, USA
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30
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Khan IA, Casciotti L. IL-15 Prolongs the Duration of CD8+ T Cell-Mediated Immunity in Mice Infected with a Vaccine Strain of Toxoplasma gondii. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.8.4503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Immunization of mice with a vaccine (ts-4) strain of Toxoplasma gondii is known to induce complete protection against subsequent lethal infection. Ts-4-mediated protection has been reported to be primarily dependent on IFN-γ-producing CD8+ T cells. However, duration of CD8+ T cell-mediated immunity in the ts-4-vaccinated animals is not known. In the present study, the kinetics of the CD8+ T cell response in mice immunized with the ts-4 strain of T. gondii was evaluated. Optimal CD8+ T cell immunity persisted at least 6 mo after vaccination, and mice at this time point continued to overcome lethal challenge with a more virulent strain. However, at 9 mo postimmunization, CD8+ T cell immunity was severely diminished and the mice succumbed to Toxoplasma challenge. Pretreatment of animals, vaccinated 9 mo earlier, with rIL-15 prevented the mortality induced by Toxoplasma challenge. The protective effect of IL-15 treatment was due to a rise in the frequency of Ag-specific CD8+ T cells. CD8+ T cells from IL-15-administered animals showed increased proliferation and IFN-γ production in response to antigenic restimulation. These findings suggest that rIL-15 can reverse the decline in the long-term CD8+ T cell immune response in mice immunized with vaccine strain of T. gondii.
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Affiliation(s)
- Imtiaz A. Khan
- Department of Medicine, Dartmouth Medical School, Lebanon, NH 03756
| | - Lori Casciotti
- Department of Medicine, Dartmouth Medical School, Lebanon, NH 03756
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31
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Dreier KJ, Stewarter LW, Kerlin RL, Ritter DM, Brake DA. Phenotypic characterisation of a Neospora caninum temperature-sensitive strain in normal and immunodeficient mice. Int J Parasitol 1999; 29:1627-34. [PMID: 10608449 DOI: 10.1016/s0020-7519(99)00100-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The in vivo persistence, immunogenicity and pathogenicity of a recently described temperature-sensitive (ts) strain from Neospora caninum, NCts-8, was investigated in normal and immunodeficient mice. Groups of BALB/c and SCID/Bg mice were infected s.c. with 5 x 10(6) wild-type NC-1, control NCts-8 (pass 0) or NCts-8 tachyzoites prepared at four in vitro passage levels (pass 7, 13, 21 and 28). For persistence and immunogenicity studies, BALB/c mice were bled and sacrificed at 4, 6 or 8 weeks p.i. Sera were analysed by IFAT and brain tissues examined for lesions by histology and tested for parasite presence by PCR. For pathogenicity studies, SCID/Bg mice were monitored by clinical signs and survival time. Results from parasite persistence experiments demonstrated microscopic lesions and PCR positive brain tissues in NC-1 infected mice. In contrast, brain tissues from NCts8-infected groups were consistently negative by histology and PCR. Based on IFAT titres, all parasite strains were immunogenic, although parasite-specific IgG levels were lower in the NCts-8 infected groups. Results from pathogenicity studies in SCID/Bg mice demonstrated a significantly (P < 0.0001) longer mean survival time in NCts-8 vs NC-1 infected groups. In addition, there was no significant difference in mean survival time between control NCts-8 and experimental passage NCts-8 infected mice. Collectively, these studies demonstrate that the NCts-8 strain maintains a stable phenotype following multiple passages in vitro, and possesses an attenuated, shorter persistence phenotype in vivo compared with the parental wild-type NC-1.
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Affiliation(s)
- K J Dreier
- Animal Health Biological Discovery and Drug Safety Evaluation (RLK), Pfizer Central Research, Pfizer Inc., Groton, CT 06340, USA
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32
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Alexander J, Jebbari H, Bluethmann H, Brombacher F, Roberts CW. The role of IL-4 in adult acquired and congenital toxoplasmosis. Int J Parasitol 1998; 28:113-20. [PMID: 9504339 DOI: 10.1016/s0020-7519(97)00168-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The course of Toxoplasma gondii infection was studied in IL-4-deficient mice from three genetic backgrounds and their wild-type counterparts following peroral inoculation of tissue cysts. Survival rates were significantly reduced in disease-susceptible C57 BL/6 mice and F1 (C57BL/6 x 129Sv) mice deficient in IL-4 compared with wild-type controls. In contrast, this difference was not observed in T. gondii-resistant BALB/c mice. However, brain tissue cyst burdens in IL-4-deficient mice were either equivalent to (C57BL/6 and BALB/c mice) or significantly less (B6/129 mice) than similarly infected wild-type mice. Thus strain-specific differences in the course of T. gondii were demonstrated in the absence of IL-4. The course of T. gondii infection was also compared between B6/129 IL-4-deficient mice and their wild-type counterparts following peroral challenge with 20 tissue cysts on day 12 of pregnancy. Age-matched non-pregnant IL-4-/- and IL-4+/+ mice were also infected to assess the role of IL-4 on T. gondii infection during pregnancy. Disease phenotypes, as measured by mortality, were reversed if infections were initiated during pregnancy compared with non-pregnant infection. Thus significant mortality occurred immediately post partum in IL-4+/+ mothers, while all IL-4-/- mothers survived. Cyst burdens 28 days p.i. were significantly lower in IL-4-/- mothers than IL-4+/+ mothers and both IL-4-/- and IL-4+/+ non-pregnant mice. Congenital disease transmission as measured by foetal death or vertical disease transmission was independent of the presence or absence of IL-4. These studies demonstrate a role for IL-4 in pregnancy-induced immunosuppression and the associated increased susceptibility to T. gondii infection.
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Affiliation(s)
- J Alexander
- Department of Immunology, University of Strathclyde, Glasgow, UK.
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33
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Alexander J, Scharton-Kersten TM, Yap G, Roberts CW, Liew FY, Sher A. Mechanisms of innate resistance to Toxoplasma gondii infection. Philos Trans R Soc Lond B Biol Sci 1997; 352:1355-9. [PMID: 9355127 PMCID: PMC1692026 DOI: 10.1098/rstb.1997.0120] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The interaction of protozoan parasites with innate host defences is critical in determining the character of the subsequent infection. The initial steps in the encounter of Toxoplasma gondii with the vertebrate immune system provide a striking example of this important aspect of the host-parasite relationship. In immuno-competent individuals this intracellular protozoan produces an asymptomatic chronic infection as part of its strategy for transmission. Nevertheless, T. gondii is inherently a highly virulent pathogen. The rapid induction by the parasite of a potent cell-mediated immune response that both limits its growth and drives conversion to a dormant cyst stage explains this apparent paradox. Studies with gene-deficient mice have demonstrated the interleukin-12 (IL-12)-dependent production of interferon gamma (IFN-gamma) to be of paramount importance in controlling early parasite growth. However, this seems to be independent of nitric oxide production as mice deficient in inducible nitric oxide synthase (iNOS) and tumour necrosis factor receptor were able to control early growth of T. gondii, although, they later succumbed to infection. Nitric oxide does, however, seem to be important in controlling persistent infection; treating chronic infection with iNOS metabolic inhibitors results in disease reactivation. Preliminary evidence implicates neutrophils in effector pathways against this parasite distinct from that described for macrophages. Once initiated, IL-12-dependent IFN-gamma production in synergy with other proinflammatory cytokines can positively feed back on itself to induce 'cytokine shock'. Regulatory cytokines, particularly IL-10, are essential to down-regulate inflammation and limit host pathology.
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Affiliation(s)
- J Alexander
- Department of Immunology, University of Strathclyde, Glasgow, UK
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34
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Neyer LE, Grunig G, Fort M, Remington JS, Rennick D, Hunter CA. Role of interleukin-10 in regulation of T-cell-dependent and T-cell-independent mechanisms of resistance to Toxoplasma gondii. Infect Immun 1997; 65:1675-82. [PMID: 9125546 PMCID: PMC175195 DOI: 10.1128/iai.65.5.1675-1682.1997] [Citation(s) in RCA: 151] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Interleukin-10 (IL-10) is a cytokine which can inhibit T-cell and natural killer (NK) cell functions associated with cell-mediated immunity to intracellular infections. The production of IL-10 by mice infected with Toxoplasma gondii has been implicated in the suppression of lymphocyte proliferation observed during acute toxoplasmosis, as well as susceptibility to infection with this parasite. We have used C57BL/6 mice which lack a functional IL-10 gene (IL-10(-/-) mice) to investigate the role of IL-10 in acute toxoplasmosis. Intraperitoneal infection of IL-10(-/-) mice with T. gondii resulted in 100% mortality by day 13, whereas wild-type C57BL/6 (WT) mice survived acute infection. IL-10(-/-) mice infected with T. gondii had significantly higher serum levels of IL-12 and gamma interferon (IFN-gamma) than WT mice. Early mortality of infected IL-10(-/-) mice was prevented by treatment with IL-10 and significantly delayed by neutralizing antibodies to IL-12 and IFN-gamma. Further studies revealed that SCID/IL-10(-/-) mice infected with T. gondii had delayed time to death compared to IL-10(-/-) mice, indicating that lymphocytes contributed to death of IL-10(-/-) mice. In addition, infected SCID/IL-10(-/-) mice survived longer than infected SCID mice. These latter data indicate that in mice lacking lymphocytes, endogenous IL-10 is associated with increased susceptibility to T. gondii. However, the lack of IL-10 does not alter the infection-induced suppression of T cell and NK cell functions. Our experiments reveal that IL-10 is associated with protection or increased susceptibility to infection with T. gondii, depending on whether mice possess lymphocytes, and demonstrate the important roles of IL-12 and IFN-gamma in the early infection-induced mortality observed in the IL-10(-/-) mice.
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Affiliation(s)
- L E Neyer
- Department of Immunology and Infectious Diseases, Research Institute, Palo Alto Medical Foundation, California 94301, USA
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35
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Venturini MC, Quiroga MA, Risso MA, Lorenzo CD, Omata Y, Venturini L, Godoy H. Mycotoxin T-2 and aflatoxin B1 as immunosuppressors in mice chronically infected with Toxoplasma gondii. J Comp Pathol 1996; 115:229-37. [PMID: 8923234 DOI: 10.1016/s0021-9975(96)80081-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The aim of this study was to determine whether repeated ingestion of mycotoxin T-2 (T2) or aflatoxin B1 (AFL) at low doses could contribute to the activation of toxoplasmosis in experimentally infected mice. Mice were divided into two groups: Control (C) and Infected (I). The cyst-forming Beverley strain of Toxoplasma gondii was used to produce the infection one month before treatment with mycotoxins. Mycotoxins were given intragastrically for a 50-day period. The average weight gain was reduced in the groups treated with mycotoxins. Mice developed specific IgG to T. gondii. Histopathological studies showed severe encephalitis in all groups infected. The number of unruptured and ruptured cysts was established and the severity of the lesions was evaluated, the groups treated with mycotoxins being the most severely affected. Immunohistochemical studies of the brain showed free antigen in tissues surrounding ruptured cysts. It is suggested that low and repeated doses of mycotoxins, necessary to produce a subclinical intoxication, precipitate Toxoplasma cyst rupture and consequently the activation of chronic toxoplasmosis.
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Affiliation(s)
- M C Venturini
- Department of Parasitology, Faculty of Veterinary Science, National University of La Plata, Argentina
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36
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Himeno K, Hisaeda H. Contribution of 65-kDa heat shock protein induced by gamma and delta T cells to protection against Toxoplasma gondii infection. Immunol Res 1996; 15:258-64. [PMID: 8902580 DOI: 10.1007/bf02918253] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Heat shock proteins (HSPs) are evolutionarily highly conserved polypeptides synthesized by many cells to preserve cellular functions under a variety of stressful conditions including infections. We have investigated the involvement of 65-kDa HSP (HSP65) in host protection against an intracellular protozoan parasite, Toxoplasma gondii, in mice. Experiments using low and highly virulent strains of Tox. gondii revealed that induction of murine HSP65 on macrophages closely correlates with protection against infection with this protozoan. Furthermore, we clarified that T cells, especially gamma delta T cells, are indispensable for HSP65 expression. A similar relationship between the expression of HSP65 on host macrophages and protective immunity was observed in mice infected with Leishmania major and Trypanosoma cruzi, both of which are obligate intracellular protozoa as is Tox. gondii.
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Affiliation(s)
- K Himeno
- Department of Parasitology and Immunology, School of Medicine, University of Tokushima, Japan
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37
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Sayles PC, Johnson LL. Intact immune defenses are required for mice to resist the ts-4 vaccine strain of Toxoplasma gondii. Infect Immun 1996; 64:3088-92. [PMID: 8757838 PMCID: PMC174192 DOI: 10.1128/iai.64.8.3088-3092.1996] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The ts-4 strain of Toxoplasma gondii is a temperature-sensitive mutant that fails to grow at 40 degrees C in vitro. Unlike mildly virulent cyst-forming strains, which can cause fatal chronic infections in certain mouse strains, ts-4 has been widely used to vaccinate mice against virulent T. gondii and is a valuable tool with which to investigate mechanisms of acquired resistance to this parasite. In this report, the basis for the avirulence of ts-4 is analyzed. It is shown that ts-4 is able to persist long-term in vivo in mildly immunocompromised mice, which rules out an intrinsic growth defect as a reason for avirulence. ts-4 does not induce body temperatures in mice as high as that needed to kill it in vitro. Moreover, the mild fevers elicited in resistant B6 mice are also seen in susceptible C57BL/6 scid/scid mice. However, ts-4 elicits strong preimmune defenses, dependent on gamma interferon, which are needed by mice to survive acute infection. Furthermore, CD4+ and CD8+ T-cell-dependent acquired immunity is essential for long-term survival of ts-4-infected mice.
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MESH Headings
- Animals
- Ascitic Fluid/immunology
- Disease Susceptibility
- Female
- Immunity
- Immunity, Innate
- Immunocompromised Host
- Interferon-gamma/analysis
- Interferon-gamma/pharmacology
- Killer Cells, Natural/immunology
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, SCID
- Peritoneal Lavage
- Protozoan Vaccines/adverse effects
- Protozoan Vaccines/genetics
- Protozoan Vaccines/immunology
- Survival Analysis
- Toxoplasma/genetics
- Toxoplasma/pathogenicity
- Toxoplasmosis, Animal/immunology
- Toxoplasmosis, Animal/mortality
- Toxoplasmosis, Animal/prevention & control
- Vaccines, Attenuated/adverse effects
- Vaccines, Attenuated/genetics
- Vaccines, Attenuated/immunology
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Affiliation(s)
- P C Sayles
- Trudeau Institute, Inc., Saranac Lake, New York 12983, USA
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38
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Affiliation(s)
- K B Seydel
- Department of Medicine and Molecular Microbiology, Washington University, St. Louis, Missouri 63110, USA
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39
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Odaert H, Soête M, Fortier B, Camus D, Dubremetz JF. Stage conversion of Toxoplasma gondii in mouse brain during infection and immunodepression. Parasitol Res 1996; 82:28-31. [PMID: 8825441 DOI: 10.1007/bf03035408] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The kinetics and pattern of expression of bradyzoite-specific proteins were studied in mouse brain during infection with Toxoplasma gondii. Parasites found in the brain 6 days after ingestion of cysts were expressing only tachyzoite-specific proteins (anti-SAG1 antibodies being used as a marker). Bradyzoite-specific protein (Pb36) expression was first found after 9 days in vacuoles containing mixed parasites simultaneously expressing SAG1 and Pb36 or cysts containing parasites expressing only the bradyzoite marker. Reactivation of toxoplasmosis was studied in mouse brain using corticosteroids for immunosuppression. Parasites expressing SAG1 were first found 6 days after the beginning of treatment, but a very heterogeneous pattern was found throughout the study. We simultaneously found vacuoles containing parasites expressing only SAG1 or containing intermediate stages or cysts containing parasites expressing only bradyzoite proteins. A striking observation was the multiplication of cysts in foci, suggesting that the immune suppression triggered the release of parasites from preexisting cysts but that the factors inducing bradyzoite development remained fully effective in driving parasites into this pathway.
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Affiliation(s)
- H Odaert
- INSERM Unité 42, Villeneuve d' Ascq, France
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40
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de Diego JA, Penin P, Arribas JR, Vázquez E, Vázquez JJ. A clinical-parasitological monotherapy cure in the treatment of experimental infection by a highly virulent strain of Toxoplasma gondii. Folia Microbiol (Praha) 1996; 41:513-6. [PMID: 9131805 DOI: 10.1007/bf02814670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Toxoplasmic encephalitis in patients with the acquired immunodeficiency syndrome (AIDS) is treated classically with pyrimethamine plus sulfadiazine. Unfortunately, up to 40% of these patients are unable to complete the course of therapy because of adverse reactions to sulfonamides. This study considers the possible usefulness of monotherapies in the treatment of acute toxoplasmosis, producing parasitological cures 2-3 months after the date of infection. With this therapy, the main adverse effects are suppressed. Groups of mice infected with the RH strain of Toxoplasma gondii were treated with pyrimethamine alone, sulfadiazine alone, and pyrimethamine plus sulfadiazine for 7 d. Treatment with pyrimethamine plus sulfadiazine produced clinical cures in 100% of the infected mice 1 month after infection. Treatment with pyrimethamine gave a 60% survival rate (clinical cure) at 1 month postinfection. Finally, treatment with sulfadiazine produced a 60% survival rate at 1 month postinfection. Although the antitoxoplasmic regimen with pyrimethamine plus sulfadiazine has proven to be effective in intensive treatment of toxoplasmic encephalitis, relapses occur in more than 80% of cases after cessation of antitoxoplasmic therapy, making secondary prophylaxis mandatory. In this study the efficacy of treatment was also evaluated in terms of parasitological cure. None of the three therapies showed parasitological cure after 1 month of treatment. When the intervals were extended to a 3-month observation, monotherapy with pyrimethamine and sulfadiazine alone produced a parasitological cure.
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Affiliation(s)
- J A de Diego
- Department of Preventive Medicine and Public Health, Autonomous University, School of Medicine, Madrid, Spain
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41
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Affiliation(s)
- C A Hunter
- Department of Immunology and Infectious Disease, Palo Alto Medical Foundation, CA 94301, USA
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42
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Scharton-Kersten T, Denkers EY, Gazzinelli R, Sher A. Role of IL12 in induction of cell-mediated immunity to Toxoplasma gondii. RESEARCH IN IMMUNOLOGY 1995; 146:539-45. [PMID: 8839159 DOI: 10.1016/0923-2494(96)83029-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- T Scharton-Kersten
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892, USA
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43
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Hunter CA, Bermudez L, Beernink H, Waegell W, Remington JS. Transforming growth factor-beta inhibits interleukin-12-induced production of interferon-gamma by natural killer cells: a role for transforming growth factor-beta in the regulation of T cell-independent resistance to Toxoplasma gondii. Eur J Immunol 1995; 25:994-1000. [PMID: 7737303 DOI: 10.1002/eji.1830250420] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Severe-combined immune deficient (SCID) mice have been found to resist infection with the intracellular protozoan parasite Toxoplasma gondii via interleukin (IL)-12 stimulation of interferon (IFN)-gamma production by natural killer (NK) cells. Previously, we demonstrated the presence of increased levels of transcripts for transforming growth factor-beta (TGF-beta) in the brains and lungs of SCID mice infected with T. gondii, leading us to investigate the role of TGF-beta in the mechanism of resistance to T. gondii in these mice. Stimulation of splenocytes from SCID mice with heat-killed T. gondii resulted in production of low levels of IFN-gamma and a two to threefold increase in levels of TGF-beta in the culture supernatants. Production of IFN-gamma in these cultures was increased three to fourfold by addition of anti-TGF-beta antibody. Stimulation of splenocytes from SCID mice with IL-12 in combination with either TNF-alpha or IL-1 beta resulted in production of high levels of IFN-gamma. Addition of TGF-beta to these cultures inhibited production of IFN-gamma in a dose-dependent manner. Immunohistochemical studies revealed increased levels of TGF-beta protein in the spleens of SCID mice 5 days after oral infection with the ME49 strain of T gondii, and brains of SCID mice at 18 days post-infection. However, no difference was detected in the levels of TGF-beta transcripts in the spleens of uninfected mice or mice infected for 5 days. To test whether TGF-beta could antagonize IL-12 mediated resistance to T. gondii in vivo, we administered TGF-beta to SCID mice infected with T. gondii. This treatment resulted in earlier mortality of infected mice and significantly reduced the ability of exogenous IL-12 to delay time-to-death. Administration of anti-TGF-beta to SCID mice, beginning 24 h prior to infection and every 2 days thereafter, delayed significantly time-to-death. Together, our data demonstrate that TGF-beta antagonizes the ability of IL-12 to stimulate production of IFN-gamma by splenocytes from SCID mice, and suggest a role for TGF-beta in regulation of T cell-independent resistance to T. gondii.
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Affiliation(s)
- C A Hunter
- Department of Immunology and Infectious Diseases, Palo Alto Medical Foundation, California, USA
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44
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Hunter CA, Subauste CS, Remington JS. The role of cytokines in toxoplasmosis. BIOTHERAPY (DORDRECHT, NETHERLANDS) 1994; 7:237-47. [PMID: 7865354 DOI: 10.1007/bf01878489] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Infection with Toxoplasma gondii is normally asymptomatic, but as a consequence of the AIDS epidemic the incidence of symptomatic disease and especially toxoplasmic encephalitis (TE) has grown in frequency. The high frequency of adverse reactions to conventional therapeutic regimens for toxoplasmosis highlight the need to develop new strategies for the management of this disease. The importance of cytokines in resistance against T. gondii has been shown primarily in murine models of toxoplasmosis and a number of cytokines (e.g., IFN-gamma, TNF-alpha, IL-2 and IL-12) have been proposed for trials in patients with TE. One mechanism by which these cytokines produce their effects is through stimulation of macrophages and/or NK cells. However, there are problems with immunological intervention in immunocompromised patients with TE since the infection is present primarily in the central nervous system (CNS), an immunoprivileged site, and because certain cytokines may down regulate the immune response. While much valuable information has been obtained from studies conducted in immunocompetent strains of mice their relevance to an immunocompromised host is unknown. The development of genetically altered mice with immune deficiencies offers promising new models that may allow for more rational development of new treatment regimens.
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Affiliation(s)
- C A Hunter
- Department of Medicine, Stanford University School of Medicine, California
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Abstract
Mice were exposed to the protozoan parasite Toxoplasma gondii in utero or were infected as neonates in order to identify and characterize resistance mechanisms that function protectively during the first weeks after birth. About one-half of the mice born of mothers fed T. gondii cysts at 11 days of gestation survived to weaning age or beyond. No effect of major histocompatibility complex (MHC) haplotype on early survival was observed in a group of backcross progeny; however, long-term survival was strongly dependent on MHC haplotype. The ability of mice infected as neonates to survive until weaning was found to depend on gamma interferon and on Thy-1+ cells but not on CD4+ or CD8+ cells. Mice that survived to maturity after infection as neonates were slightly more resistant to challenge with virulent T. gondii parasites than were sham-infected controls but were less resistant than were mice infected as adults. Together the results indicate the following. (i) Mice congenitally infected with T. gondii have a gamma interferon-dependent mechanism of early resistance that involves Thy-1+ cells but not CD4+ or CD8+ cells. (ii) This mechanism is not under MHC-linked genetic control. (iii) Mice that exhibit long-term survival after congenital infection acquire a modest degree of protection against reinfection with virulent organisms. (iv) The extent of long-term survival of congenitally infected neonates, like that in mice infected as adults, is influenced by MHC genes, presumably via MHC-restricted CD4+ and/or CD8+ cells.
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Affiliation(s)
- L L Johnson
- Trudeau Institute Inc., Saranac Lake, New York 12983
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Hunter CA, Subauste CS, Van Cleave VH, Remington JS. Production of gamma interferon by natural killer cells from Toxoplasma gondii-infected SCID mice: regulation by interleukin-10, interleukin-12, and tumor necrosis factor alpha. Infect Immun 1994; 62:2818-24. [PMID: 7911785 PMCID: PMC302887 DOI: 10.1128/iai.62.7.2818-2824.1994] [Citation(s) in RCA: 241] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Previous studies of mice have implicated natural killer (NK) cells as mediators of protective activity against Toxoplasma gondii through their production of gamma interferon (IFN-gamma). In the present study, we have compared NK-cell activity in infected and uninfected SCID mice. Our data reveal that infection results in increased levels of IFN-gamma in serum and elevated NK-cell activity but that these NK cells were not cytotoxic for T. gondii-infected P815 cells. Treatment with anti-IFN-gamma antibody abrogated the increase in NK-cell activity and resulted in earlier mortality of infected mice. In vivo treatment with anti-asialo GM1 antiserum reduced NK cell activity and levels of IFN-gamma in serum but did not alter time to death. Spleen cells from infected mice produced higher levels of IFN-gamma than those from uninfected mice when stimulated in vitro with live T. gondii or parasite antigen preparations. Further analysis revealed that interleukin 10 (IL-10) inhibited, whereas tumor necrosis factor alpha (TNF-alpha) and IL-12 enhanced, IFN-gamma production by spleen cells from infected or uninfected mice. The combination of IL-12 and TNF-alpha induced higher levels of IFN-gamma from whole spleen cells of infected mice than from those of uninfected mice. Depletion of the adherent cell population from the spleen cells of infected mice led to a significant reduction in the levels of IFN-gamma produced after stimulation with IL-12 plus TNF-alpha. Similar results did not occur with cells from uninfected mice. These data indicate that other cytokines produced by the adherent cell population from infected mice may be involved in maximal production of IFN-gamma by NK cells stimulated with IL-12 and TNF-alpha. To assess the importance of endogenous IL-12, a polyclonal anti-IL-12 was administered to infected SCID mice. This treatment led to earlier mortality, indicating that endogenous IL-12 mediates resistance to T. gondii.
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Affiliation(s)
- C A Hunter
- Department of Immunology and Infectious Disease, Palo Alto Medical Foundation, California
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Johnson LL, VanderVegt FP, Havell EA. Gamma interferon-dependent temporary resistance to acute Toxoplasma gondii infection independent of CD4+ or CD8+ lymphocytes. Infect Immun 1993; 61:5174-80. [PMID: 7901163 PMCID: PMC281298 DOI: 10.1128/iai.61.12.5174-5180.1993] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
It is well established that resistance to acute primary Toxoplasma gondii infection is mediated by a gamma interferon (IFN-gamma)-dependent mechanism. The present in vivo experiments were undertaken to investigate the cellular basis for this resistance. We show here that immunocompetent T. gondii-infected C57BL/6 (B6) mice treated with anti-IFN-gamma or with anti-Thy-1 or anti-asialo-GM1 antibodies die sooner than infected mice treated with antibodies that deplete both CD4+ and CD8+ T lymphocytes. Thy-1+ CD4- CD8- cells accumulated in the peritoneal cavities of B6 mice during the early stages of an intraperitoneal infection but did not accumulate in sham-infected control mice, and substantial numbers of Thy-1+ CD4- CD8- cells were recovered from the peritoneal cavities of infected B6 mice treated with antibodies that depleted CD4+ and CD8+ lymphocytes. Depletion of Thy-1+ cells reduced IFN-gamma to undetectable levels, whereas depletion of CD4+ and CD8+ cells did not reduce IFN-gamma levels. Thus T. gondii infection in immunocompetent B6 mice elicits Thy-1+ CD4- CD8- cells which either produce protective IFN-gamma themselves or control its production by other cells. It is likely that the function of these Thy-1+ CD4- CD8- cells is to control T. gondii tachyzoites during the early stages of primary infection before specific CD4(+)- and/or CD8(+)-dependent immunity develops.
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Affiliation(s)
- L L Johnson
- Trudeau Institute, Inc., Saranac Lake, New York 12983
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Abstract
Mice with severe combined immunodeficiency (SCID mice) have become a favored model system for the study of many parasitic diseases. In this review, Samuel Stanley Jr and Herbert Virgin IV provide a brief overview of the biology of the SCID mouse, and review some examples of how the SCID mouse model has been applied to the study of the immunology of a number of different parasitic diseases.
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Affiliation(s)
- S L Stanley
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110, USA
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Davidson MG, Rottman JB, English RV, Lappin MR, Tompkins MB. Feline immunodeficiency virus predisposes cats to acute generalized toxoplasmosis. THE AMERICAN JOURNAL OF PATHOLOGY 1993; 143:1486-97. [PMID: 8238262 PMCID: PMC1887187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
This study was designed to examine the effects of a pre-existing, clinically asymptomatic feline immunodeficiency virus (FIV) infection on a primary challenge with Toxoplasma gondii. Parenteral challenge of FIV-infected cats with tachyzoites of the ME49 strain of T. gondii caused a precipitous drop in all lymphocytes (CD4+, CD8+, and B cells) and generalized severe toxoplasmosis. The predominant postmortem lesions included acute and often fatal interstitial pneumonia, dominated histologically by macrophages, and multifocal to coalescing hepatic necrosis. Immunohistochemistry revealed numerous T. gondii antigen and tachyzoites in macrophages and other cell types in the lung lesions. The proliferative response of peripheral blood mononuclear cells to specific (T. gondii antigen) and nonspecific (Concanavalin A) mitogens was defective in the dually infected cats, suggesting marked immunosuppression. In contrast to the dually infected cats, cats infected only with T. gondii developed a transient, mild clinical disease characterized by anorexia, lethargy, and multifocal chorioretinitis. Lymphocyte changes in T. gondii-infected cats included an early pan-lymphopenia followed by reestablishment of all lymphocyte subset profiles. These cats also showed a reduced proliferative response to Concanavalin A at 1 week after challenge, but a measurable in vivo response to T. gondii antigens, as evidenced by in vitro lymphocyte proliferation in the absence of a mitogenic stimulus. These results show that infection of cats with FIV-NCSU, markedly enhances their susceptibility to a primary T. gondii infection and provides a model to study the mechanisms of the underlying immunological defect(s) occurring early after HIV infection that may predispose individuals to development of acquired immunodeficiency syndrome and associated diseases.
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MESH Headings
- Animals
- CD4-CD8 Ratio
- Cat Diseases/parasitology
- Cat Diseases/pathology
- Cats
- Disease Models, Animal
- Feline Acquired Immunodeficiency Syndrome/complications
- Feline Acquired Immunodeficiency Syndrome/immunology
- Feline Acquired Immunodeficiency Syndrome/pathology
- Immunodeficiency Virus, Feline
- Immunoglobulin M/blood
- Liver/pathology
- Lung/parasitology
- Lung/pathology
- Lung Diseases, Interstitial/complications
- Lung Diseases, Interstitial/parasitology
- Lung Diseases, Interstitial/pathology
- Lung Diseases, Interstitial/veterinary
- Specific Pathogen-Free Organisms
- Time Factors
- Toxoplasma
- Toxoplasmosis, Animal/complications
- Toxoplasmosis, Animal/immunology
- Toxoplasmosis, Animal/parasitology
- Toxoplasmosis, Animal/pathology
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Affiliation(s)
- M G Davidson
- Department of Companion Animal and Special Species Medicine, North Carolina State University, Raleigh
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Hunter CA, Abrams JS, Beaman MH, Remington JS. Cytokine mRNA in the central nervous system of SCID mice infected with Toxoplasma gondii: importance of T-cell-independent regulation of resistance to T. gondii. Infect Immun 1993; 61:4038-44. [PMID: 8406791 PMCID: PMC281121 DOI: 10.1128/iai.61.10.4038-4044.1993] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Levels of cytokine mRNA were studied in the central nervous system (CNS) of SCID mice infected with Toxoplasma gondii. This infection led to 100% mortality by day 23 postinfection. Inflammation was observed in the lungs on day 7 and in the heart, liver, and kidneys on days 14 and 18 of infection. In the CNS, necrotic, acellular lesions that contained numerous parasites, accompanied by a localized astrocyte activation, were evident on day 14. Polymerase chain reaction-assisted amplification of RNA revealed that, although transcripts for interleukin-1 alpha (IL-1 alpha) and IL-1 beta were present in the brains of uninfected mice, increased levels of these transcripts were detected on day 7 of infection. Transcripts for macrophage inflammatory protein 1 and transforming growth factor beta were also detected in brains of infected mice at this time point. On days 14 and 18, levels of these transcripts had increased and transcripts for IL-6, IL-10, gamma interferon (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), and granulocyte-macrophage colony-stimulating factor (GM-CSF) were also detected. Transcripts for IL-2 or IL-4 were not detected at any of the time points. Detection of locally produced cytokine transcripts may reflect involvement of the cytokines in the immunopathogenesis of this infection or involvement in mediating antitoxoplasma activity. To assess the possible role of endogenous IFN-gamma, TNF-alpha, IL-10, IL-6, and GM-CSF, cytokine-neutralizing monoclonal antibodies were administered to infected SCID mice. Neutralization of IFN-gamma or TNF-alpha led to earlier mortality than that in controls. In contrast, treatment with antibody to IL-10 and IL-6 increased survival time. Treatment with anti-GM-CSF did not alter the time to death. These results indicate that TNF-alpha and IFN-gamma are both involved in T-cell-independent mechanisms of resistance to T. gondii in SCID mice and that IL-10 and IL-6 may downregulate the immune response to this pathogen.
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Affiliation(s)
- C A Hunter
- Department of Medicine, Stanford University School of Medicine, California 94305
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