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Thomson R, Molina-Portela P, Mott H, Carrington M, Raper J. Hydrodynamic gene delivery of baboon trypanosome lytic factor eliminates both animal and human-infective African trypanosomes. Proc Natl Acad Sci U S A 2009; 106:19509-14. [PMID: 19858474 PMCID: PMC2780755 DOI: 10.1073/pnas.0905669106] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Indexed: 11/18/2022] Open
Abstract
Several species of African trypanosomes cause fatal disease in livestock, but most cannot infect humans due to innate trypanosome lytic factors (TLFs). Human TLFs are pore forming high-density lipoprotein (HDL) particles that contain apolipoprotein L-I (apoL-I) the trypanolytic component, and haptoglobin-related protein (Hpr), which binds free hemoglobin (Hb) in blood and facilitates the uptake of TLF via a trypanosome haptoglobin-hemoglobin receptor. The human-infective Trypanosoma brucei rhodesiense escapes lysis by TLF by expression of serum resistance-associated (SRA) protein, which binds and neutralizes apoL-I. Unlike humans, baboons are not susceptible to infection by T. b. rhodesiense due to previously unidentified serum factors. Here, we show that baboons have a TLF complex that contains orthologs of Hpr and apoL-I and that full-length baboon apoL-I confers trypanolytic activity to mice and when expressed together with baboon Hpr and human apoA-I, provides protection against both animal infective and the human-infective T. brucei rhodesiense in vivo. We further define two critical lysines near the C terminus of baboon apoL-1 that are necessary and sufficient to prevent binding to SRA and thereby confer resistance to human-infective trypanosomes. These findings form the basis for the creation of TLF transgenic livestock that would be resistant to animal and human-infective trypanosomes, which would result in the reduction of disease and the zoonotic transmission of human infective trypanosomes.
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Affiliation(s)
- Russell Thomson
- Department of Medical Parasitology, New York University Langone School of Medicine, 341, East 25th Street, New York, NY, 10010; and
| | - Pilar Molina-Portela
- Department of Medical Parasitology, New York University Langone School of Medicine, 341, East 25th Street, New York, NY, 10010; and
| | - Helen Mott
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom
| | - Jayne Raper
- Department of Medical Parasitology, New York University Langone School of Medicine, 341, East 25th Street, New York, NY, 10010; and
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102
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Thomson R, Samanovic M, Raper J. Activity of trypanosome lytic factor: a novel component of innate immunity. Future Microbiol 2009; 4:789-96. [PMID: 19722834 DOI: 10.2217/fmb.09.57] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Trypanosome lytic factors (TLFs) are high-density lipoproteins and components of primate innate immunity. TLFs are characterized by their ability to kill extracellular protozoon parasites of the genus Trypanosoma. Two subspecies of Trypanosoma brucei have evolved resistance to TLFs and can consequently infect humans, resulting in the disease African sleeping sickness. The unique protein components of TLFs are a hemoglobin-binding protein, haptoglobin-related protein and a pore-forming protein, apoL-I. The recent advances in our understanding of the roles that these proteins play in the mechanism of TLF-mediated lysis are highlighted in this article. In light of recent data, which demonstrate that TLFs can ameliorate infection by the intracellular pathogen Leishmania, we also discuss the broader function of TLFs as components of innate immunity.
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Affiliation(s)
- Russell Thomson
- Medical Parasitology, New York University Langone Medical Center, 341 East 25th Street, New York, NY 10010, USA.
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103
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104
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Armengol L, Villatoro S, González JR, Pantano L, García-Aragonés M, Rabionet R, Cáceres M, Estivill X. Identification of copy number variants defining genomic differences among major human groups. PLoS One 2009; 4:e7230. [PMID: 19789632 PMCID: PMC2747275 DOI: 10.1371/journal.pone.0007230] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Accepted: 08/20/2009] [Indexed: 12/14/2022] Open
Abstract
Background Understanding the genetic contribution to phenotype variation of human groups is necessary to elucidate differences in disease predisposition and response to pharmaceutical treatments in different human populations. Methodology/Principal Findings We have investigated the genome-wide profile of structural variation on pooled samples from the three populations studied in the HapMap project by comparative genome hybridization (CGH) in different array platforms. We have identified and experimentally validated 33 genomic loci that show significant copy number differences from one population to the other. Interestingly, we found an enrichment of genes related to environment adaptation (immune response, lipid metabolism and extracellular space) within these regions and the study of expression data revealed that more than half of the copy number variants (CNVs) translate into gene-expression differences among populations, suggesting that they could have functional consequences. In addition, the identification of single nucleotide polymorphisms (SNPs) that are in linkage disequilibrium with the copy number alleles allowed us to detect evidences of population differentiation and recent selection at the nucleotide variation level. Conclusions Overall, our results provide a comprehensive view of relevant copy number changes that might play a role in phenotypic differences among major human populations, and generate a list of interesting candidates for future studies.
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Affiliation(s)
- Lluís Armengol
- Genetic Causes of Disease Group, Genes and Disease Program, Center for Genomic Regulation (CRG-UPF) and CIBERESP, Barcelona, Catalonia, Spain
- Quantitative Genomic Medicine Laboratories (qGenomics), Barcelona, Catalonia, Spain
| | - Sergi Villatoro
- Genetic Causes of Disease Group, Genes and Disease Program, Center for Genomic Regulation (CRG-UPF) and CIBERESP, Barcelona, Catalonia, Spain
| | - Juan R. González
- Center for Research in Environmental Epidemiology (CREAL), Barcelona, Catalonia, Spain
| | - Lorena Pantano
- Genetic Causes of Disease Group, Genes and Disease Program, Center for Genomic Regulation (CRG-UPF) and CIBERESP, Barcelona, Catalonia, Spain
| | - Manel García-Aragonés
- Genetic Causes of Disease Group, Genes and Disease Program, Center for Genomic Regulation (CRG-UPF) and CIBERESP, Barcelona, Catalonia, Spain
| | - Raquel Rabionet
- Genetic Causes of Disease Group, Genes and Disease Program, Center for Genomic Regulation (CRG-UPF) and CIBERESP, Barcelona, Catalonia, Spain
| | - Mario Cáceres
- Genetic Causes of Disease Group, Genes and Disease Program, Center for Genomic Regulation (CRG-UPF) and CIBERESP, Barcelona, Catalonia, Spain
| | - Xavier Estivill
- Genetic Causes of Disease Group, Genes and Disease Program, Center for Genomic Regulation (CRG-UPF) and CIBERESP, Barcelona, Catalonia, Spain
- Genetics Unit, Department of Health and Experimental Life Sciences, Pompeu Fabra University (UPF), Barcelona, Catalonia, Spain
- National Genotyping Center (CeGen) Barcelona Genotyping Node, Center for Genomic Regulation (CRG-UPF), Barcelona, Catalonia, Spain
- * E-mail:
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105
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Pays E, Vanhollebeke B. Human innate immunity against African trypanosomes. Curr Opin Immunol 2009; 21:493-8. [PMID: 19559585 DOI: 10.1016/j.coi.2009.05.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 05/22/2009] [Accepted: 05/25/2009] [Indexed: 10/20/2022]
Abstract
Humans are naturally resistant to infection by the African trypanosome prototype Trypanosoma brucei brucei, and only two variant clones of this parasite can avoid this innate immunity and cause sleeping sickness. The resistance to T. brucei is due to serum complexes associating apolipoprotein A-1 (apoA1) with two primate-specific proteins, apolipoprotein L-1 (apoL1) and haptoglobin-related protein (Hpr). We discuss recent advances on the respective functions of apoL1 and Hpr in this system. ApoL1 was found to share structural and functional similarities with proteins of the apoptotic Bcl2 family, and to kill trypanosomes through anionic pore formation in the lysosomal membrane of the parasite. In association with hemoglobin (Hb), Hpr was found to promote the binding of the trypanolytic complexes to a haptoglobin (Hp)-Hb receptor of the trypanosome surface, hereby facilitating the internalization of apoL1. Hpr or apoL1 deficiency respectively leads to the reduction or abolishment of human protection against T. brucei.
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Affiliation(s)
- Etienne Pays
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 12, rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium
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106
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Abstract
Haptoglobin, the haptoglobin-hemoglobin receptor CD163, and the heme oxygenase-1 are proteins with a well-established function in the clearance and metabolism of "free" hemoglobin released during intravascular hemolysis. This scavenging system counteracts the potentially harmful oxidative and NO-scavenging effects associated with "free" hemoglobin, and, furthermore, elicits an anti-inflammatory response. In the late primate evolution, haptoglobin variants with distinct functions have arisen, including haptoglobin polymers and the haptoglobin-related protein. The latter associates with a subspecies of high-density lipoprotein (HDL) particles playing a crucial role in the innate immunity against certain trypanosome parasites. Recent studies have elucidated this fairly sophisticated immune defense mechanism that takes advantage of a trypanosomal haptoglobin-hemoglobin receptor evolved to supply the parasite with heme. Because of the high resemblance between haptoglobin and haptoglobin-related protein, the receptor also takes up the complex of hemoglobin and the HDL-bound haptoglobin-related protein. This tricks the parasite into internalizing another HDL-associated protein and toxin, apolipoprotein L-I, that kills the parasite. In conclusion, variant human homologous hemoglobin-binding proteins that collectively may be designated the haptoglobins have diverted from the haptoglobin gene. On hemoglobin and receptor interaction, these haptoglobins contribute to different biologic events that go beyond simple removal from plasma of the toxic hemoglobin.
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107
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108
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Lacomble S, Vaughan S, Gadelha C, Morphew MK, Shaw MK, McIntosh JR, Gull K. Three-dimensional cellular architecture of the flagellar pocket and associated cytoskeleton in trypanosomes revealed by electron microscope tomography. J Cell Sci 2009; 122:1081-90. [PMID: 19299460 DOI: 10.1242/jcs.045740] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
This study uses electron tomography linked to a variety of other EM methods to provide an integrated view of the flagellar pocket and basal body area of the African trypanosome procyclic trypomastigote. We reveal the pocket as an asymmetric membranous 'balloon' with two boundary structures. One of these - the collar - defines the flagellum exit point. The other defines the entry point of the flagellum into the pocket and consists of both an internal transitional fibre array and an external membrane collarette. A novel set of nine radial fibres is described in the basal body proximal zone. The pocket asymmetry is invariably correlated with the position of the probasal body and Golgi. The neck region, just distal to the flagellum exit site, is a specialised area of membrane associated with the start of the flagellum attachment zone and signifies the point where a special set of four microtubules, nucleated close to the basal bodies, joins the subpellicular array. The neck region is also associated with the single Golgi apparatus of the cell. The flagellar exit point interrupts the subpellicular microtubule array with discrete endings of microtubules at the posterior side. Overall, our studies reveal a highly organised, yet dynamic, area of cytoplasm and will be informative in understanding its function.
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Affiliation(s)
- Sylvain Lacomble
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
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109
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Hernandez SM, Kolliker-Frers RA, Sanchez MS, Razzitte G, Britos RD, Fuentes ME, Schwarcz de Tarlovsky MN. Antiproliferative effect of sera from chagasic patients on Trypanosoma cruzi epimastigotes. Involvement of xanthine oxidase. Acta Trop 2009; 109:219-25. [PMID: 19073131 DOI: 10.1016/j.actatropica.2008.11.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 11/10/2008] [Accepted: 11/14/2008] [Indexed: 11/26/2022]
Abstract
Serum from asymptomatic or symptomatic (with cardiovascular manifestations) chagasic patients depleted of the complement system displayed an antiproliferative effect on Trypanosoma cruzi epimastigotes, RA strain, when added to the growth medium. This effect was also observed when patient's serum was depleted of specific antibodies. The antiproliferative effect was both time and concentration dependent. It was confined to the non-dialyzable, high molecular weight, fraction of the serum. This effect was abrogated by allopurinol and catalase, and enhanced by N-ethylmaleimide. Xanthine oxidoreductase and xanthine oxidase activities were increased in the chagasic sera, while catalase activity remained unchanged. Parasites exposed to chagasic sera showed a decrease in Fe/superoxide dismutase activity as well as an increase in membrane lipoperoxidation. Our data provides evidence to support the idea that the antiproliferative activity observed in sera from chagasic patients may be due, at least partially, to a direct effect of hydrogen peroxide on the epimastigotes of T. cruzi. The increase of hydrogen peroxide to antiproliferative levels might result from an increase in xanthine oxidase activity in the serum of patients infected with the parasite.
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110
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Field MC, Lumb JH, Adung'a VO, Jones NG, Engstler M. Chapter 1 Macromolecular Trafficking and Immune Evasion in African Trypanosomes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 278:1-67. [DOI: 10.1016/s1937-6448(09)78001-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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111
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Checchi F, Filipe JAN, Barrett MP, Chandramohan D. The natural progression of Gambiense sleeping sickness: what is the evidence? PLoS Negl Trop Dis 2008; 2:e303. [PMID: 19104656 PMCID: PMC2602732 DOI: 10.1371/journal.pntd.0000303] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Gambiense human African trypanosomiasis (HAT, sleeping sickness) is widely assumed to be 100% pathogenic and fatal. However, reports to the contrary exist, and human trypano-tolerance has been postulated. Furthermore, there is uncertainty about the actual duration of both stage 1 and stage 2 infection, particularly with respect to how long a patient remains infectious. Understanding such basic parameters of HAT infection is essential for optimising control strategies based on case detection. We considered the potential existence and relevance of human trypano-tolerance, and explored the duration of infectiousness, through a review of published evidence on the natural progression of gambiense HAT in the absence of treatment, and biological considerations. Published reports indicate that most gambiense HAT cases are fatal if untreated. Self-resolving and asymptomatic chronic infections probably constitute a minority if they do indeed exist. Chronic carriage, however, deserves further study, as it could seed renewed epidemics after control programmes cease.
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Affiliation(s)
- Francesco Checchi
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.
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112
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Perry GH, Yang F, Marques-Bonet T, Murphy C, Fitzgerald T, Lee AS, Hyland C, Stone AC, Hurles ME, Tyler-Smith C, Eichler EE, Carter NP, Lee C, Redon R. Copy number variation and evolution in humans and chimpanzees. Genome Res 2008; 18:1698-710. [PMID: 18775914 DOI: 10.1101/gr.082016.108] [Citation(s) in RCA: 180] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Copy number variants (CNVs) underlie many aspects of human phenotypic diversity and provide the raw material for gene duplication and gene family expansion. However, our understanding of their evolutionary significance remains limited. We performed comparative genomic hybridization on a single human microarray platform to identify CNVs among the genomes of 30 humans and 30 chimpanzees as well as fixed copy number differences between species. We found that human and chimpanzee CNVs occur in orthologous genomic regions far more often than expected by chance and are strongly associated with the presence of highly homologous intrachromosomal segmental duplications. By adapting population genetic analyses for use with copy number data, we identified functional categories of genes that have likely evolved under purifying or positive selection for copy number changes. In particular, duplications and deletions of genes with inflammatory response and cell proliferation functions may have been fixed by positive selection and involved in the adaptive phenotypic differentiation of humans and chimpanzees.
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Affiliation(s)
- George H Perry
- School of Human Evolution & Social Change, Arizona State University, Tempe, Arizona 85287, USA
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113
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114
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Vanhollebeke B, De Muylder G, Nielsen MJ, Pays A, Tebabi P, Dieu M, Raes M, Moestrup SK, Pays E. A haptoglobin-hemoglobin receptor conveys innate immunity to Trypanosoma brucei in humans. Science 2008; 320:677-81. [PMID: 18451305 DOI: 10.1126/science.1156296] [Citation(s) in RCA: 186] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The protozoan parasite Trypanosoma brucei is lysed by apolipoprotein L-I, a component of human high-density lipoprotein (HDL) particles that are also characterized by the presence of haptoglobin-related protein. We report that this process is mediated by a parasite glycoprotein receptor, which binds the haptoglobin-hemoglobin complex with high affinity for the uptake and incorporation of heme into intracellular hemoproteins. In mice, this receptor was required for optimal parasite growth and the resistance of parasites to the oxidative burst by host macrophages. In humans, the trypanosome receptor also recognized the complex between hemoglobin and haptoglobin-related protein, which explains its ability to capture trypanolytic HDLs. Thus, in humans the presence of haptoglobin-related protein has diverted the function of the trypanosome haptoglobin-hemoglobin receptor to elicit innate host immunity against the parasite.
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Affiliation(s)
- Benoit Vanhollebeke
- Laboratory of Molecular Parasitology, Institute for Molecular Biology and Medicine, Université Libre de Bruxelles, 12 rue des Profs Jeener et Brachet, B6041 Gosselies, Belgium
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115
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Peck RF, Shiflett AM, Schwartz KJ, McCann A, Hajduk SL, Bangs JD. The LAMP-like protein p67 plays an essential role in the lysosome of African trypanosomes. Mol Microbiol 2008; 68:933-46. [PMID: 18430083 DOI: 10.1111/j.1365-2958.2008.06195.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
RNAi knockdown was employed to study the function of p67, a lysosome-associated membrane protein (LAMP)-like type I transmembrane lysosomal glycoprotein in African trypanosomes. Conditional induction of p67 dsRNA resulted in specific approximately 90% reductions in de novo p67 synthesis in both mammalian bloodstream and procyclic insect-stage parasites. Bloodstream cell growth was severely retarded with extensive death after > 24 h of induction. Biosynthetic trafficking of residual p67, and of the soluble lysosomal protease trypanopain, were unimpaired. Endocytosis of tomato lectin, a surrogate receptor-mediated cargo, was only mildly impaired (approximately 20%), but proper lysosomal targeting was unaffected. p67 ablation had dramatic effects on lysosomal morphology with gross enlargement (four- to fivefold) and internal membrane profiles reminiscent of autophagic vacuoles. Ablation of p67 expression rendered bloodstream trypanosomes refractory to lysis by human trypanolytic factor (TLF), a lysosomally activated host innate immune mediator. Similar effects on lysosomal morphology and TLF sensitivity were also obtained by two pharmacological agents that neutralize lysosomal pH--chloroquine and bafilomycin A1. Surprisingly, however, lysosomal pH was not affected in ablated cells suggesting that other physiological alterations must account for increased resistance to TLF. These results indicate p67 plays an essential role in maintenance of normal lysosomal structure and physiology in bloodstream-stage African trypanosomes.
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Affiliation(s)
- Ronald F Peck
- Department of Medical Microbiology & Immunology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
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116
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Dacks JB, Walker G, Field MC. Implications of the new eukaryotic systematics for parasitologists. Parasitol Int 2007; 57:97-104. [PMID: 18180199 DOI: 10.1016/j.parint.2007.11.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Revised: 11/15/2007] [Accepted: 11/16/2007] [Indexed: 11/24/2022]
Abstract
An accurate understanding of evolutionary relationships is central in biology. For parasitologists, understanding the relationships among eukaryotic organisms allows the prediction of virulence mechanisms, reconstruction of metabolic pathways, identification of potential drug targets, elucidation of parasite-specific cellular processes and understanding of interactions with the host or vector. Here we consider the impact of major recent revisions of eukaryotic systematics and taxonomy on parasitology. The previous, ladder-like model placed some protists as early diverging, with the remaining eukaryotes "progressing" towards a "crown radiation" of animals, plants, Fungi and some additional protistan lineages. This model has been robustly disproven. The new model is based on vastly increased amounts of molecular sequence data, integration with morphological information and the rigorous application of phylogenetic methods to those data. It now divides eukaryotes into six major supergroups; the relationships between those groups and the order of branching remain unknown. This new eukaryotic phylogeny emphasizes that organisms including Giardia, Trypanosoma and Trichomonas are not primitive, but instead highly evolved and specialised for their specific environments. The wealth of newly available comparative genomic data has also allowed the reconstruction of ancient suites of characteristics and mapping of character evolution in diverse parasites. For example, the last common eukaryotic ancestor was apparently complex, suggesting that lineage-specific adaptations and secondary losses have been important in the evolution of protistan parasites. Referring to the best evidence-based models for eukaryotic evolution will allow parasitologists to make more accurate and reliable inferences about pathogens that cause significant morbidity and mortality.
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Affiliation(s)
- Joel B Dacks
- The Molteno Building, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
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117
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Widener J, Nielsen MJ, Shiflett A, Moestrup SK, Hajduk S. Hemoglobin is a co-factor of human trypanosome lytic factor. PLoS Pathog 2007; 3:1250-61. [PMID: 17845074 PMCID: PMC1971115 DOI: 10.1371/journal.ppat.0030129] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Accepted: 07/18/2007] [Indexed: 11/18/2022] Open
Abstract
Trypanosome lytic factor (TLF) is a high-density lipoprotein (HDL) subclass providing innate protection to humans against infection by the protozoan parasite Trypanosoma brucei brucei. Two primate-specific plasma proteins, haptoglobin-related protein (Hpr) and apolipoprotein L-1 (ApoL-1), have been proposed to kill T. b. brucei both singularly or when co-assembled into the same HDL. To better understand the mechanism of T. b. brucei killing by TLF, the protein composition of TLF was investigated using a gentle immunoaffinity purification technique that avoids the loss of weakly associated proteins. HDL particles recovered by immunoaffinity absorption, with either anti-Hpr or anti-ApoL-1, were identical in protein composition and specific activity for T. b. brucei killing. Here, we show that TLF-bound Hpr strongly binds Hb and that addition of Hb stimulates TLF killing of T. b. brucei by increasing the affinity of TLF for its receptor, and by inducing Fenton chemistry within the trypanosome lysosome. These findings suggest that TLF in uninfected humans may be inactive against T. b. brucei prior to initiation of infection. We propose that infection of humans by T. b. brucei causes hemolysis that triggers the activation of TLF by the formation of Hpr-Hb complexes, leading to enhanced binding, trypanolytic activity, and clearance of parasites.
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Affiliation(s)
- Justin Widener
- Program in Pathobiology, Brown University, Providence, Rhode Island, United States of America
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | | | - April Shiflett
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | | | - Stephen Hajduk
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
- * To whom correspondence should be addressed. E-mail:
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118
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Natesan SKA, Peacock L, Matthews K, Gibson W, Field MC. Activation of endocytosis as an adaptation to the mammalian host by trypanosomes. EUKARYOTIC CELL 2007; 6:2029-37. [PMID: 17905918 PMCID: PMC2168407 DOI: 10.1128/ec.00213-07] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Immune evasion in African trypanosomes is principally mediated by antigenic variation, but rapid internalization of surface-bound immune factors may contribute to survival. Endocytosis is upregulated approximately 10-fold in bloodstream compared to procyclic forms, and surface coat remodeling accompanies transition between these life stages. Here we examined expression of endocytosis markers in tsetse fly stages in vivo and monitored modulation during transition from bloodstream to procyclic forms in vitro. Among bloodstream stages nonproliferative stumpy forms have endocytic activity similar to that seen with rapidly dividing slender forms, while differentiation of stumpy forms to procyclic forms is accompanied by rapid down-regulation of Rab11 and clathrin, suggesting that modulation of endocytic and recycling systems accompanies this differentiation event. Significantly, rapid down-regulation of endocytic markers occurs upon entering the insect midgut and expression of Rab11 and clathrin remains low throughout subsequent development, which suggests that high endocytic activity is not required for remodeling the parasite surface or for survival within the fly. However, salivary gland metacyclic forms dramatically increase expression of clathrin and Rab11, indicating that emergence of mammalian infective forms is coupled to reacquisition of a high-activity endocytic-recycling system. These data suggest that high-level endocytosis in Trypanosoma brucei is an adaptation required for viability in the mammalian host.
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Affiliation(s)
- Senthil Kumar A Natesan
- The Molteno Building, Department of Pathology, Tennis Court Road, University of Cambridge, Cambridge CB2 1QP, United Kingdom
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119
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Vanhollebeke B, Lecordier L, Perez-Morga D, Amiguet-Vercher A, Pays E. Human Serum Lyses Trypanosoma brucei by Triggering Uncontrolled Swelling of the Parasite Lysosome. J Eukaryot Microbiol 2007; 54:448-51. [PMID: 17910690 DOI: 10.1111/j.1550-7408.2007.00285.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Trypanosoma brucei brucei infects a wide range of mammals, but is unable to infect humans because this subspecies is lysed by normal human serum (NHS). The phenotype of cellular lysis is debated. For some authors the lysosome undergoes osmotic swelling due to massive influx of chloride ions from the cytoplasmic compartment, but others describe multiple small cytoplasmic vacuoles and general swelling of the cellular body. Using population-level imaging of live immobilized trypanosomes throughout the lysis process, we report that specific swelling of the lysosome is a genuine and major characteristic of NHS-mediated lysis and that this phenotype is independent of the strain of trypanosomes and of NHS aging or damaging. Thus, irrespective of experimental conditions NHS reproducibly induced the swelling of the parasite lysosome.
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Affiliation(s)
- Benoit Vanhollebeke
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (U.L.B.), 12, rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium
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120
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Human African trypanosomiasis: pharmacological re-engagement with a neglected disease. Br J Pharmacol 2007; 152:1155-71. [PMID: 17618313 DOI: 10.1038/sj.bjp.0707354] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
This review discusses the challenges of chemotherapy for human African trypanosomiasis (HAT). The few drugs registered for use against the disease are unsatisfactory for a number of reasons. HAT has two stages. In stage 1 the parasites proliferate in the haemolymphatic system. In stage 2 they invade the central nervous system and brain provoking progressive neurological dysfunction leading to symptoms that include the disrupted sleep wake patterns that give HAT its more common name of sleeping sickness. Targeting drugs to the central nervous system offers many challenges. However, it is the cost of drug development for diseases like HAT, that afflict exclusively people of the world's poorest populations, that has been the principal barrier to new drug development and has led to them becoming neglected. Here we review drugs currently registered for HAT, and also discuss the few compounds progressing through clinical trials. Finally we report on new initiatives that might allow progress to be made in developing new and satisfactory drugs for this terrible disease.
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Abstract
Trypanosomes are members of the kinetoplastida, a group of divergent protozoan parasites responsible for considerable morbidity and mortality worldwide. These organisms have highly complex life cycles requiring modification of their cell surface together with engagement of immune evasion systems to effect survival; both processes intimately involve the membrane trafficking system. The completion of three trypanosomatid and several additional protist genomes in the last few years is providing an exciting opportunity to evaluate, at the molecular level, the evolution and diversity of membrane trafficking across deep evolutionary time as well as to analyse in unprecedented detail the membrane trafficking systems of trypanosomes.
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Affiliation(s)
- Mark C Field
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
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122
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Lee SH, Stephens JL, Englund PT. A fatty-acid synthesis mechanism specialized for parasitism. Nat Rev Microbiol 2007; 5:287-97. [PMID: 17363967 DOI: 10.1038/nrmicro1617] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Most cells use either a type I or type II synthase to make fatty acids. Trypanosoma brucei, the sleeping sickness parasite, provides the first example of a third mechanism for this process. Trypanosomes use microsomal elongases to synthesize fatty acids de novo, whereas other cells use elongases to make long-chain fatty acids even longer. The modular nature of the pathway allows synthesis of different fatty-acid end products, which have important roles in trypanosome biology. Indeed, this newly discovered mechanism seems ideally suited for the parasitic lifestyle.
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Affiliation(s)
- Soo Hee Lee
- Department of Biological Chemistry, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205, USA
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123
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Vanhollebeke B, Nielsen MJ, Watanabe Y, Truc P, Vanhamme L, Nakajima K, Moestrup SK, Pays E. Distinct roles of haptoglobin-related protein and apolipoprotein L-I in trypanolysis by human serum. Proc Natl Acad Sci U S A 2007; 104:4118-23. [PMID: 17360487 PMCID: PMC1820718 DOI: 10.1073/pnas.0609902104] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Indexed: 11/18/2022] Open
Abstract
Apolipoprotein L-I (apoL-I) is a human high-density lipoprotein (HDL) component able to kill Trypanosoma brucei brucei by forming anion-selective pores in the lysosomal membrane of the parasite. Another HDL component, haptoglobin-related protein (Hpr), has been suggested as an additional toxin required for full trypanolytic activity of normal human serum. We recently reported the case of a human lacking apoL-I (apoL-I(-/-)HS) as the result of frameshift mutations in both apoL-I alleles. Here, we show that this serum, devoid of any trypanolytic activity, exhibits normal concentrations of HDL-bound Hpr. Conversely, the serum of individuals with normal HDL-bound apoL-I but who lack Hpr and haptoglobin [Hp(r)(-/-)HS] as the result of gene deletion (anhaptoglobinemia) exhibited phenotypically normal but delayed trypanolytic activity. The trypanolytic properties of Hp(r)(-/-)HS were mimicked by free recombinant apoL-I, whereas recombinant Hpr did not affect trypanosomes. The lysis delay observed with either Hp(r)(-/-)HS or recombinant apoL-I could entirely be attributed to a defect in the uptake of the lytic components. Thus, apoL-I is responsible for the trypanolytic activity of normal human serum, whereas Hpr allows fast uptake of the carrier HDL particles, presumably through their binding to an Hp/Hpr surface receptor of the parasite.
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Affiliation(s)
- Benoit Vanhollebeke
- *Laboratory of Molecular Parasitology, Institut de Biologie et de Médecine Moléculaires, Université Libre de Bruxelles, 12, Rue des Profs Jeener et Brachet, B6041 Gosselies, Belgium
| | - Marianne J. Nielsen
- Department of Medical Biochemistry, University of Aarhus, DK-8000 Aarhus, Denmark
| | | | - Philippe Truc
- Institut de Recherche pour le Développement, Unité de Recherche 117 Trypanosomoses Africaines, Instituto de Combate e Controlo das Tripanosossomiases, CP 2657 Luanda, Angola; and
| | - Luc Vanhamme
- *Laboratory of Molecular Parasitology, Institut de Biologie et de Médecine Moléculaires, Université Libre de Bruxelles, 12, Rue des Profs Jeener et Brachet, B6041 Gosselies, Belgium
| | | | - Soren K. Moestrup
- Department of Medical Biochemistry, University of Aarhus, DK-8000 Aarhus, Denmark
| | - Etienne Pays
- *Laboratory of Molecular Parasitology, Institut de Biologie et de Médecine Moléculaires, Université Libre de Bruxelles, 12, Rue des Profs Jeener et Brachet, B6041 Gosselies, Belgium
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124
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Vanhollebeke B, Truc P, Poelvoorde P, Pays A, Joshi PP, Katti R, Jannin JG, Pays E. Human Trypanosoma evansi infection linked to a lack of apolipoprotein L-I. N Engl J Med 2006; 355:2752-6. [PMID: 17192540 DOI: 10.1056/nejmoa063265] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Humans have innate immunity against Trypanosoma brucei brucei that is known to involve apolipoprotein L-I (APOL1). Recently, a case of T. evansi infection in a human was identified in India. We investigated whether the APOL1 pathway was involved in this occurrence. The serum of the infected patient was found to have no trypanolytic activity, and the finding was linked to the lack of APOL1, which was due to frameshift mutations in both APOL1 alleles. Trypanolytic activity was restored by the addition of recombinant APOL1. The lack of APOL1 explained the patient's infection with T. evansi.
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Affiliation(s)
- Benoit Vanhollebeke
- Laboratory of Molecular Parasitology, Institut de Biologie et de Médecine Moléculaires, Université Libre de Bruxelles, Gosselies, Belgium
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125
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Abstract
Telomeres are specialized DNA-protein complexes that stabilize chromosome ends, protecting them from nucleolytic degradation and illegitimate recombination. Telomeres form a heterochromatic structure that can suppress the transcription of adjacent genes. These structures might have additional roles in Trypanosoma brucei, as the major surface antigens of this parasite are expressed during its infectious stages from subtelomeric loci. We propose that the telomere protein complexes of trypanosomes and vertebrates are conserved and offer the hypothesis that growth and breakage of telomeric repeats has an important role in regulating parasite antigenic variation in trypanosomes.
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Affiliation(s)
- Oliver Dreesen
- The Rockefeller University, 1230 York Avenue, New York, New York 10021, USA
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126
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Jensby Nielsen M, Bo Nielsen L, Moestrup SK. High-density lipoprotein and innate immunity. ACTA ACUST UNITED AC 2006. [DOI: 10.2217/17460875.1.6.729] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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127
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Baral TN, Magez S, Stijlemans B, Conrath K, Vanhollebeke B, Pays E, Muyldermans S, De Baetselier P. [Experimental therapy of African trypanosomiasis with a nanobody-conjugated human trypanolytic factor]. Med Sci (Paris) 2006; 22:914-6. [PMID: 17101086 DOI: 10.1051/medsci/20062211914] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Toya Nath Baral
- Département des Interactions cellulaires et moléculaires, Vlaams Interuniversitair Instituut voor Biotechnologie, Laboratorium voor Cellulaire en Moleculaire Immunologie, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Bruxelles, Belgique.
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Kramer S, Klöckner T, Selmayr M, Boshart M. Interstrain sequence comparison, transcript map and clonal genomic rearrangement of a 28 kb locus on chromosome 9 of Trypanosoma brucei. Mol Biochem Parasitol 2006; 151:129-32. [PMID: 17112605 DOI: 10.1016/j.molbiopara.2006.10.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Revised: 09/27/2006] [Accepted: 10/10/2006] [Indexed: 11/23/2022]
Affiliation(s)
- Susanne Kramer
- Ludwig-Maximilians-Universität München, Department of Biology, Section Genetics, Maria-Ward-Str. 1a, D-80638 München, Germany
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