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Vidal-Calvo EE, Martin-Salazar A, Choudhary S, Dagil R, Raghavan SSR, Duvnjak L, Nordmaj MA, Clausen TM, Skafte A, Oberkofler J, Wang K, Agerbæk MØ, Løppke C, Jørgensen AM, Ropac D, Mujollari J, Willis S, Garcias López A, Miller RL, Karlsson RTG, Goerdeler F, Chen YH, Colaço AR, Wang Y, Lavstsen T, Martowicz A, Nelepcu I, Marzban M, Oo HZ, Ørum-Madsen MS, Wang Y, Nielsen MA, Clausen H, Wierer M, Wolf D, Gögenur I, Theander TG, Al-Nakouzi N, Gustavsson T, Daugaard M, Salanti A. Tumor-agnostic cancer therapy using antibodies targeting oncofetal chondroitin sulfate. Nat Commun 2024; 15:7553. [PMID: 39215044 PMCID: PMC11364678 DOI: 10.1038/s41467-024-51781-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 08/16/2024] [Indexed: 09/04/2024] Open
Abstract
Molecular similarities between embryonic and malignant cells can be exploited to target tumors through specific signatures absent in healthy adult tissues. One such embryonic signature tumors express is oncofetal chondroitin sulfate (ofCS), which supports disease progression and dissemination in cancer. Here, we report the identification and characterization of phage display-derived antibody fragments recognizing two distinct ofCS epitopes. These antibody fragments show binding affinity to ofCS in the low nanomolar range across a broad selection of solid tumor types in vitro and in vivo with minimal binding to normal, inflamed, or benign tumor tissues. Anti-ofCS antibody drug conjugates and bispecific immune cell engagers based on these targeting moieties disrupt tumor progression in animal models of human and murine cancers. Thus, anti-ofCS antibody fragments hold promise for the development of broadly effective therapeutic and diagnostic applications targeting human malignancies.
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Affiliation(s)
- Elena Ethel Vidal-Calvo
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark.
- VAR2 Pharmaceuticals ApS, Copenhagen, Denmark.
| | - Anne Martin-Salazar
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
| | - Swati Choudhary
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
- VAR2 Pharmaceuticals ApS, Copenhagen, Denmark
| | - Robert Dagil
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
- VAR2 Pharmaceuticals ApS, Copenhagen, Denmark
| | - Sai Sundar Rajan Raghavan
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
| | - Lara Duvnjak
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
- VAR2 Pharmaceuticals ApS, Copenhagen, Denmark
| | - Mie Anemone Nordmaj
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
| | | | - Ann Skafte
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
- VAR2 Pharmaceuticals ApS, Copenhagen, Denmark
| | - Jan Oberkofler
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
| | - Kaituo Wang
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mette Ø Agerbæk
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
- VARCT Diagnostics, Copenhagen, Denmark
| | - Caroline Løppke
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
| | - Amalie Mundt Jørgensen
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
- VARCT Diagnostics, Copenhagen, Denmark
| | - Daria Ropac
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
| | - Joana Mujollari
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
| | - Shona Willis
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
| | - Agnès Garcias López
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
| | - Rebecca Louise Miller
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Richard Torbjörn Gustav Karlsson
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Felix Goerdeler
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Ana R Colaço
- Proteomics Research Infrastructure, University of Copenhagen, Copenhagen, Denmark
| | - Yong Wang
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Thomas Lavstsen
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
| | - Agnieszka Martowicz
- Department of Internal Medicine V, Haematology & Oncology, Comprehensive Cancer Center Innsbruck (CCCI) and Tyrolean Cancer Research Institute (TKFI), Medical University of Innsbruck, Innsbruck, Austria
| | - Irina Nelepcu
- Vancouver Prostate Centre, Vancouver Coastal Health Research Institutes, Vancouver, BC, Canada
- Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Mona Marzban
- Vancouver Prostate Centre, Vancouver Coastal Health Research Institutes, Vancouver, BC, Canada
- Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Htoo Zarni Oo
- Vancouver Prostate Centre, Vancouver Coastal Health Research Institutes, Vancouver, BC, Canada
- Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Maj Sofie Ørum-Madsen
- Vancouver Prostate Centre, Vancouver Coastal Health Research Institutes, Vancouver, BC, Canada
- Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Yuzhuo Wang
- Vancouver Prostate Centre, Vancouver Coastal Health Research Institutes, Vancouver, BC, Canada
| | - Morten A Nielsen
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
- VAR2 Pharmaceuticals ApS, Copenhagen, Denmark
| | - Henrik Clausen
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael Wierer
- Proteomics Research Infrastructure, University of Copenhagen, Copenhagen, Denmark
| | - Dominik Wolf
- Department of Internal Medicine V, Haematology & Oncology, Comprehensive Cancer Center Innsbruck (CCCI) and Tyrolean Cancer Research Institute (TKFI), Medical University of Innsbruck, Innsbruck, Austria
| | - Ismail Gögenur
- Center for Surgical Science, Department of Surgery, Zealand University Hospital Køge, Køge, Denmark
| | - Thor G Theander
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
- VAR2 Pharmaceuticals ApS, Copenhagen, Denmark
| | - Nader Al-Nakouzi
- VAR2 Pharmaceuticals ApS, Copenhagen, Denmark
- Vancouver Prostate Centre, Vancouver Coastal Health Research Institutes, Vancouver, BC, Canada
- Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Tobias Gustavsson
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
- VAR2 Pharmaceuticals ApS, Copenhagen, Denmark
| | - Mads Daugaard
- VAR2 Pharmaceuticals ApS, Copenhagen, Denmark.
- Vancouver Prostate Centre, Vancouver Coastal Health Research Institutes, Vancouver, BC, Canada.
- Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
| | - Ali Salanti
- Centre for Translational Medicine and Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark.
- VAR2 Pharmaceuticals ApS, Copenhagen, Denmark.
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2
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Keitany GJ, Jenkins BJ, Obiakor HT, Daniel S, Muehlenbachs A, Semblat JP, Gamain B, Doritchamou JYA, Desai SA, MacDonald NJ, Narum DL, Morrison R, Saveria T, Vignali M, Oleinikov AV, Fried M, Duffy PE. An invariant protein that co-localizes with VAR2CSA on Plasmodium falciparum-infected red cells binds to chondroitin sulfate A. J Infect Dis 2021; 225:2011-2022. [PMID: 34718641 DOI: 10.1093/infdis/jiab550] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 10/25/2021] [Indexed: 11/14/2022] Open
Abstract
Plasmodium falciparum-infected red blood cells (iRBCs) bind and sequester in deep vascular beds, causing malaria-related disease and death. In pregnant women, VAR2CSA binds to chondroitin sulfate A (CSA) and mediates placental sequestration, making it the major placental malaria (PM) vaccine target. Here, we characterize an invariant protein associated with PM called Plasmodium falciparum chondroitin sulfate A ligand (PfCSA-L). Recombinant PfCSA-L binds both placental CSA and VAR2CSA with nanomolar affinity, and is coexpressed on the iRBC surface with VAR2CSA. Unlike VAR2CSA, which is anchored by a transmembrane domain, PfCSA-L is peripherally associated with the outer surface of knobs through high affinity protein-protein interactions with VAR2CSA. This suggests iRBC sequestration involves complexes of invariant and variant surface proteins, allowing parasites to maintain both diversity and function at the iRBC surface. PfCSA-L is a promising target for intervention because it is well conserved, exposed on infected cells, and expressed and localized with VAR2CSA.
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Affiliation(s)
- Gladys J Keitany
- Center for Infectious Disease Research, Seattle, WA, USA.,University of Washington, Department of Pathobiology, Seattle, WA, USA
| | - Bethany J Jenkins
- Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Bethesda, MD, USA
| | - Harold T Obiakor
- Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Bethesda, MD, USA
| | - Shaji Daniel
- Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Bethesda, MD, USA
| | - Atis Muehlenbachs
- University of Washington Medical Center, Anatomic Pathology, Seattle, WA, USA
| | - Jean-Philippe Semblat
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, Inserm, F-75015, Paris, France
| | - Benoit Gamain
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, Inserm, F-75015, Paris, France
| | | | - Sanjay A Desai
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD
| | | | - David L Narum
- Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Bethesda, MD, USA
| | | | - Tracy Saveria
- Center for Infectious Disease Research, Seattle, WA, USA
| | | | | | - Michal Fried
- Center for Infectious Disease Research, Seattle, WA, USA.,University of Washington, Department of Pathobiology, Seattle, WA, USA.,Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Bethesda, MD, USA
| | - Patrick E Duffy
- Center for Infectious Disease Research, Seattle, WA, USA.,University of Washington, Department of Pathobiology, Seattle, WA, USA.,Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Bethesda, MD, USA
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3
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Structural diversity and biological importance of ABO, H, Lewis and secretor histo-blood group carbohydrates. Rev Bras Hematol Hemoter 2016; 38:331-340. [PMID: 27863762 PMCID: PMC5119663 DOI: 10.1016/j.bjhh.2016.07.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/08/2016] [Accepted: 07/21/2016] [Indexed: 12/20/2022] Open
Abstract
ABO, H, secretor and Lewis histo-blood system genes control the expression of part of the carbohydrate repertoire present in areas of the body occupied by microorganisms. These carbohydrates, besides having great structural diversity, act as potential receptors for pathogenic and non-pathogenic microorganisms influencing susceptibility and resistance to infection and illness. Despite the knowledge of some structural variability of these carbohydrate antigens and their polymorphic levels of expression in tissue and exocrine secretions, little is known about their biological importance and potential applications in medicine. This review highlights the structural diversity, the biological importance and potential applications of ABO, H, Lewis and secretor histo-blood carbohydrates.
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4
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Shioiri T, Tsuchimoto J, Watanabe H, Sugiura N. Sequence determination of synthesized chondroitin sulfate dodecasaccharides. Glycobiology 2016; 26:592-606. [PMID: 26791444 DOI: 10.1093/glycob/cww008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 01/15/2016] [Indexed: 11/14/2022] Open
Abstract
Chondroitin sulfate (CS) is a linear acidic polysaccharide composed of repeating disaccharide units of glucuronic acid and N-acetyl-d-galactosamine. The polysaccharide is modified with sulfate groups at different positions by a variety of sulfotransferases. CS chains exhibit various biological and pathological functions by interacting with cytokines and growth factors and regulating their signal transduction. The fine structure of the CS chain defines its specific biological roles. However, structural analysis of CS has been restricted to disaccharide analysis, hampering the understanding of the structure-function relationship of CS chains. Here, we chemo-enzymatically synthesized CS dodecasaccharides having various sulfate modifications using a bioreactor system of bacterial chondroitin polymerase mutants and various CS sulfotransferases. We developed a sequencing method for CS chains using the CS dodecasaccharides. The method consists of (i) labeling a reducing end with 2-aminopyridine (PA), (ii) partial digestion of CS with testicular hyaluronidase, followed by separation of PA-conjugated oligosaccharides with different chain lengths, (iii) limited digestion of these oligosaccharides with chondroitin lyase AC II into disaccharides, followed by labeling with 2-aminobenzamide, (iv) CS disaccharide analysis using a dual-fluorescence HPLC system (reversed-phase ion-pair and ion-exchange chromatography), and (v) estimation of the composition by calculating individual disaccharide ratios. This CS chain sequencing allows characterization of CS-modifying enzymes and provides a useful tool toward understanding the structure-function relationship of CS chains.
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Affiliation(s)
- Tatsumasa Shioiri
- Institute for Molecular Science of Medicine, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Aichi 480-1195, Japan
| | - Jun Tsuchimoto
- Institute for Molecular Science of Medicine, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Aichi 480-1195, Japan
| | - Hideto Watanabe
- Institute for Molecular Science of Medicine, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Aichi 480-1195, Japan
| | - Nobuo Sugiura
- Institute for Molecular Science of Medicine, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Aichi 480-1195, Japan
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Abstract
INTRODUCTION Placental malaria (PM) is a major public health problem that constitutes a significant health concern for the mother, and especially for the developing fetus and offspring. Current means of prevention have limitations, including a restricted window of intervention that excludes the first trimester of pregnancy, and the fact that very few drugs can be used for this purpose. The identification of the VAR2CSA antigen, specific to PM parasites, offers an excellent opportunity to develop a vaccine against this disease. Proof of concept of a first-generation vaccine is nearing completion, and two clinical trials are underway. AREAS COVERED This review focuses on PM, which is mainly caused by Plasmodium falciparum. The review highlights recent advances and the key milestones that led to the identification of the optimal vaccine target within the large VAR2CSA protein. The paper also points out how future improvements can strengthen this process to achieve an effective vaccine in the field. EXPERT OPINION The approach taken to develop a P. falciparum erythrocyte membrane protein 1-based vaccine to protect pregnant women is very promising in view of the current difficulties of achieving a sterilizing vaccine against malaria parasite. This approach could help us to control the deleterious effect of malaria infections that characterize severe clinical forms.
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Goel S, Muthusamy A, Miao J, Cui L, Salanti A, Winzeler EA, Gowda DC. Targeted disruption of a ring-infected erythrocyte surface antigen (RESA)-like export protein gene in Plasmodium falciparum confers stable chondroitin 4-sulfate cytoadherence capacity. J Biol Chem 2014; 289:34408-21. [PMID: 25342752 DOI: 10.1074/jbc.m114.615393] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family proteins mediate the adherence of infected erythrocytes to microvascular endothelia of various organs, including the placenta, thereby contributing to cerebral, placental, and other severe malaria pathogenesis. Several parasite proteins, including KAHRP and PfEMP3, play important roles in the cytoadherence by mediating the clustering of PfEMP1 in rigid knoblike structures on the infected erythrocyte surface. The lack of a subtelomeric region of chromosome 2 that contains kahrp and pfemp3 causes reduced cytoadherence. In this study, microarray transcriptome analysis showed that the absence of a gene cluster, comprising kahrp, pfemp3, and four other genes, results in the loss of parasitized erythrocytes adhering to chondroitin 4-sulfate (C4S). The role of one of these genes, PF3D7_0201600/PFB0080c, which encodes PHISTb (Plasmodium helical interspersed subtelomeric b) domain-containing RESA-like protein 1 expressed on the infected erythrocyte surface, was investigated. Disruption of PFB0080c resulted in increased var2csa transcription and VAR2CSA surface expression, leading to higher C4S-binding capacity of infected erythrocytes. Further, PFB0080c-knock-out parasites stably maintained the C4S adherence through many generations of growth. Although the majority of PFB0080c-knock-out parasites bound to C4S even after culturing for 6 months, a minor population bound to both C4S and CD36. These results strongly suggest that the loss of PFB0080c markedly compromises the var gene switching process, leading to a marked reduction in the switching rate and additional PfEMP1 expression by a minor population of parasites. PFB0080c interacts with VAR2CSA and modulates knob-associated Hsp40 expression. Thus, PFB0080c may regulate VAR2CSA expression through these processes. Overall, we conclude that PFB0080c regulates PfEMP1 expression and the parasite's cytoadherence.
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Affiliation(s)
- Suchi Goel
- From the Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033,
| | - Arivalagan Muthusamy
- From the Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Jun Miao
- the Department of Entomology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Liwang Cui
- the Department of Entomology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Ali Salanti
- the Centre for Medical Parasitology at the Department of International Health, Immunology, and Microbiology, Copenhagen University Hospital, DK 2014 Copenhagen, Denmark, and
| | - Elizabeth A Winzeler
- the Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, California 92093
| | - D Channe Gowda
- From the Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033,
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7
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Duffy PE, Fried M. Pregnancy malaria: cryptic disease, apparent solution. Mem Inst Oswaldo Cruz 2012; 106 Suppl 1:64-9. [PMID: 21881758 DOI: 10.1590/s0074-02762011000900008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 06/01/2011] [Indexed: 11/21/2022] Open
Abstract
Malaria during pregnancy can be severe in non-immune women, but in areas of stable transmission, where women are semi-immune and often asymptomatic during infection, malaria is an insidious cause of disease and death for mothers and their offspring. Sequelae, such as severe anaemia and hypertension in the mother and low birth weight and infant mortality in the offspring, are often not recognised as consequences of infection. Pregnancy malaria, caused by Plasmodium falciparum, is mediated by infected erythrocytes (IEs) that bind to chondroitin sulphate A and are sequestered in the placenta. These parasites have a unique adhesion phenotype and distinct antigenicity, which indicates that novel targets may be required for development of an effective vaccine. Women become resistant to malaria as they acquire antibodies against placental IE, which leads to higher haemoglobin levels and heavier babies. Proteins exported from the placental parasites have been identified, including both variant and conserved antigens, and some of these are in preclinical development for vaccines. A vaccine that prevents P. falciparum malaria in pregnant mothers is feasible and would potentially save hundreds of thousands of lives each year.
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Affiliation(s)
- Patrick Emmet Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.
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8
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Hviid L. The case for PfEMP1-based vaccines to protect pregnant women against Plasmodium falciparum malaria. Expert Rev Vaccines 2012; 10:1405-14. [PMID: 21988306 DOI: 10.1586/erv.11.113] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Vaccines are very cost-effective tools in combating infectious disease mortality and morbidity. Unfortunately, vaccines efficiently protecting against infection with malaria parasites are not available and are not likely to appear in the near future. An alternative strategy would be vaccines protecting against the disease and its consequences rather than against infection per se, by accelerating the development of the protective immunity that is normally acquired after years of exposure to malaria parasites in areas of stable transmission. This latter strategy is being energetically pursued to develop a vaccine protecting pregnant women and their offspring against mortality and morbidity caused by the accumulation of Plasmodium falciparum-infected erythrocytes in the placenta. It is based on a detailed understanding of the parasite antigen and the host receptor involved in this accumulation, as well as knowledge regarding the protective immune response that is acquired in response to placental P. falciparum infection. Nevertheless, it remains controversial in some quarters whether such a vaccine would have the desired impact, or indeed whether the strategy is meaningful. This article critically examines the relevance of several perceived obstacles to development of a vaccine against placental malaria.
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Affiliation(s)
- Lars Hviid
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
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9
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Goel S, Gowda DC. How specific is Plasmodium falciparum adherence to chondroitin 4-sulfate? Trends Parasitol 2011; 27:375-81. [PMID: 21507719 DOI: 10.1016/j.pt.2011.03.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 03/16/2011] [Accepted: 03/19/2011] [Indexed: 11/16/2022]
Abstract
Plasmodium falciparum infection during pregnancy results in the sequestration of infected red blood cells (IRBCs) in the placenta, contributing to pregnancy associated malaria (PAM). IRBC adherence is mediated by the binding of a variant Plasmodium falciparum erythrocyte binding protein 1 named VAR2CSA to the low sulfated chondroitin 4-sulfate (C4S) proteoglycan (CSPG) present predominantly in the intervillous space of the placenta. IRBC binding is highly specific to the level and distribution of 4-sulfate groups in C4S. Given the strict specificity of IRBC-C4S interactions, it is better to use either placental CSPG or CSPGs bearing structurally similar C4S chains in defining VAR2CSA structural architecture that interact with C4S, evaluating VAR2CSA constructs for vaccine development or studying structure-based inhibitors as therapeutics for PAM.
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Affiliation(s)
- Suchi Goel
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, USA
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10
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Ndam NT, Deloron P. Molecular aspects of Plasmodium falciparum Infection during pregnancy. J Biomed Biotechnol 2010; 2007:43785. [PMID: 17641725 PMCID: PMC1906705 DOI: 10.1155/2007/43785] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Accepted: 03/21/2007] [Indexed: 11/17/2022] Open
Abstract
Cytoadherence of Plasmodium-falciparum-parasitized red blood cells (PRBCs) to host receptors is the key phenomenon in the pathological process of the malaria disease. Some of these interactions can originate poor outcomes responsible for 1 to 3 million annual deaths mostly occurring among children in sub-Saharan Africa. Pregnancy-associated malaria (PAM) represents an important exception of the disease occurring at adulthood in malaria endemic settings. Consequences of this are shared between the mother (maternal anemia) and the baby (low birth weight and infant mortality). Demonstrating that parasites causing PAM express specific variant surface antigens (VSA(PAM)), including the P. falciparum erythrocyte membrane protein 1 (P f EMP1) variant VAR2CSA, that are targets for protective immunity has strengthened the possibility for the development of PAM-specific vaccine. In this paper, we review the molecular basis of malaria pathogenesis attributable to the erythrocyte stages of the parasites, and findings supporting potential anti-PAM vaccine components evidenced in PAM.
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Affiliation(s)
- Nicaise Tuikue Ndam
- UR 010, Laboratoire de Parasitologie, Institut de Recherche pour le Développement, Université Paris Descartes, IFR 71, 4 avenue de l'Observatoire, 75006 Paris, France
- *Nicaise Tuikue Ndam:
| | - Philippe Deloron
- UR 010, Laboratoire de Parasitologie, Institut de Recherche pour le Développement, Université Paris Descartes, IFR 71, 4 avenue de l'Observatoire, 75006 Paris, France
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11
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Can any lessons be learned from the ambiguous glycan binding of PfEMP1 domains? Trends Parasitol 2010; 26:230-5. [PMID: 20189879 DOI: 10.1016/j.pt.2010.02.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 12/18/2009] [Accepted: 02/04/2010] [Indexed: 11/22/2022]
Abstract
Pregnancy-associated malaria (PAM) is caused by Plasmodium falciparum-infected erythrocytes (IEs) accumulating in the placenta and has dire consequences for both mother and child. The multi-domain antigen VAR2CSA confers specific adhesion of IEs to chondroitin sulphate A (CSA) in the placenta, and is the leading PAM vaccine candidate. Recent data from different laboratories show that the binding properties of individual VAR2CSA domains do not reflect the native CSA-specific adhesion of IEs, which questions the relevance of the information obtained from single domain binding assays and co-crystallization experiments. Here, we discuss the implications of these findings for VAR2CSA vaccine development and highlight the need for studying the native structure of this protein.
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12
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Sander AF, Salanti A, Lavstsen T, Nielsen MA, Magistrado P, Lusingu J, Ndam NT, Arnot DE. Multiple var2csa-type PfEMP1 genes located at different chromosomal loci occur in many Plasmodium falciparum isolates. PLoS One 2009; 4:e6667. [PMID: 19690615 PMCID: PMC2723927 DOI: 10.1371/journal.pone.0006667] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 07/13/2009] [Indexed: 12/03/2022] Open
Abstract
Background The var2csa gene encodes a Plasmodium falciparum adhesion receptor which binds chondroitin sulfate A (CSA). This var gene is more conserved than other PfEMP1/var genes and is found in all P. falciparum isolates. In isolates 3D7, FCR3/It4 and HB3, var2csa is transcribed from a sub-telomeric position on the left arm of chromosome 12, but it is not known if this location is conserved in all parasites. Genome sequencing indicates that the var2csa gene is duplicated in HB3, but whether this is true in natural populations is uncertain. Methodology/Principal Findings To assess global variation in the VAR2CSA protein, sequence variation in the DBL2X region of var2csa genes in 54 P.falciparum samples was analyzed. Chromosome mapping of var2csa loci was carried out and a quantitative PCR assay was developed to estimate the number of var2csa genes in P.falciparum isolates from the placenta of pregnant women and from the peripheral circulation of other malaria patients. Sequence analysis, gene mapping and copy number quantitation in P.falciparum isolates indicate that there are at least two loci and that both var2csa-like genes can be transcribed. All VAR2CSA DBL2X domains fall into one of two distinct phylogenetic groups possessing one or the other variant of a large (∼26 amino acid) dimorphic motif, but whether either motif variant is linked to a specific locus is not known. Conclusions/Significance Two or more related but distinct var2csa-type PfEMP1/var genes exist in many P. falciparum isolates. One gene is on chromosome 12 but additional var2csa-type genes are on different chromosomes in different isolates. Multiplicity of var2csa genes appears more common in infected placentae than in samples from non-pregnant donors indicating a possible advantage of this genotype in pregnancy associated malaria.
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Affiliation(s)
- Adam F. Sander
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Thomas Lavstsen
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Morten A. Nielsen
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Pamela Magistrado
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- JMP-ENRICA Project, National Institute for Medical Research, Korogwe Laboratory, Tanga, Tanzania
| | - John Lusingu
- JMP-ENRICA Project, National Institute for Medical Research, Korogwe Laboratory, Tanga, Tanzania
| | - Nicaise Tuikue Ndam
- Institut de Recherche pour le Developpment, UR010, Universite Paris Descartes, Paris, France
| | - David E. Arnot
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- Institute of Immunology & Infection Research, School of Biology, University of Edinburgh, Edinburgh, Scotland, United Kingdom
- * E-mail:
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Achur RN, Kakizaki I, Goel S, Kojima K, Madhunapantula SV, Goyal A, Ohta M, Kumar S, Takagaki K, Gowda DC. Structural interactions in chondroitin 4-sulfate mediated adherence of Plasmodium falciparum infected erythrocytes in human placenta during pregnancy-associated malaria. Biochemistry 2009; 47:12635-43. [PMID: 18975976 DOI: 10.1021/bi801643m] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Infection with Plasmodium falciparum during pregnancy results in the adherence of infected red blood cells (IRBCs) in placenta, causing pregnancy-associated malaria with severe health complications in mothers and fetuses. The chondroitin 4-sulfate (C4S) chains of very low sulfated chondroitin sulfate proteoglycans (CSPGs) in placenta mediate the IRBC adherence. While it is known that partially sulfated but not fully sulfated C4S effectively binds IRBCs, structural interactions involved remain unclear and are incompletely understood. In this study, structurally defined C4S oligosaccharides of varying sulfate contents and sizes were evaluated for their ability to inhibit the binding of IRBCs from different P. falciparum strains to CSPG purified from placenta. The results clearly show that, with all parasite strains studied, dodecasaccharide is the minimal chain length required for the efficient adherence of IRBCs to CSPG and two 4-sulfated disaccharides within this minimal structural motif are sufficient for maximal binding. Together, these data demonstrate for the first time that the C4S structural requirement for IRBC adherence is parasite strain-independent. We also show that the carboxyl group on nonreducing end glucuronic acid in dodecasaccharide motif is important for IRBC binding. Thus, in oligosaccharides containing terminal 4,5-unsaturated glucuronic acid, the nonreducing end disaccharide moiety does not interact with IRBCs due to the altered spatial orientation of carboxyl group. In such C4S oligosaccharides, 14-mer but not 12-mer constitutes the minimal motif for inhibition of IRBC binding to placental CSPG. These data have important implications for the development and evaluation of therapeutics and vaccine for placental malaria.
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Affiliation(s)
- Rajeshwara N Achur
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA
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14
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Lekostaj JK, Natarajan JK, Paguio MF, Wolf C, Roepe PD. Photoaffinity labeling of the Plasmodium falciparum chloroquine resistance transporter with a novel perfluorophenylazido chloroquine. Biochemistry 2008; 47:10394-406. [PMID: 18767816 DOI: 10.1021/bi8010658] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Several models describing how amino acid substitutions in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) confer resistance to chloroquine (CQ) and other antimalarial drugs have been proposed. Further progress requires molecular analysis of interactions between purified reconstituted PfCRT protein and these drugs. We have thus designed and synthesized several perfluorophenyl azido (pfpa) CQ analogues for PfCRT photolabeling studies. One particularly useful probe (AzBCQ) places the pfpa group at the terminal aliphatic N of CQ via a flexible four-carbon ester linker and includes a convenient biotin tag. This probe photolabels PfCRT in situ with high specificity. Using reconstituted proteoliposomes harboring partially purified recombinant PfCRT, we analyze AzBCQ photolabeling versus competition with CQ and other drugs to probe the nature of the CQ binding site. We also inspect how pH, the chemoreversal agent verapamil (VPL), and various amino acid mutations in PfCRT that cause CQ resistance (CQR) affect the efficiency of AzBCQ photolabeling. Upon gel isolation of AzBCQ-labeled PfCRT followed by trypsin digestion and mass spectrometry analysis, we are able to define a single AzBCQ covalent attachment site lying within the digestive vacuolar-disposed loop between putative helices 9 and 10 of PfCRT. Taken together, the data provide important new insight into PfCRT function and, along with previous results, allow us to propose a model for a single CQ binding site in the PfCRT protein.
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15
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Tuikue Ndam N, Bischoff E, Proux C, Lavstsen T, Salanti A, Guitard J, Nielsen MA, Coppée JY, Gaye A, Theander T, David PH, Deloron P. Plasmodium falciparum transcriptome analysis reveals pregnancy malaria associated gene expression. PLoS One 2008; 3:e1855. [PMID: 18365010 PMCID: PMC2267001 DOI: 10.1371/journal.pone.0001855] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 02/20/2008] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Pregnancy-associated malaria (PAM) causing maternal anemia and low birth weight is among the multiple manifestations of Plasmodium falciparum malaria. Infected erythrocytes (iEs) can acquire various adhesive properties that mediate the clinical severity of malaria. Recent advances on the molecular basis of virulence and immune evasion have helped identify var2csa as a PAM-specific var gene. METHODOLOGY/PRINCIPAL FINDINGS The present study presents a genome-wide microarray transcript analysis of 18 P. falciparum parasite isolates freshly collected from the placenta. The proportion of PAM over-expressed genes located in subtelomeric regions as well as that of PAM over-expressed genes predicted to be exported were higher than expected compared to the whole genome. The identification of novel parasite molecules with specificity to PAM and which are likely involved in host-pathogen interactions and placental tropism is described. One of these proteins, PFI1785w, was further characterized as the product of a two-exon PHIST gene, and was more often recognized by serum samples from P. falciparum-exposed women than from men. CONCLUSIONS/SIGNIFICANCE These findings suggest that other parasite proteins, such as PFI1785w, may contribute beside VAR2CSA to the pathogenesis of PAM. These data may be very valuable for future vaccine development.
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Affiliation(s)
- Nicaise Tuikue Ndam
- Institut de Recherche pour le Développement, UR010 at Université Paris Descartes, Mother and Child Health in the Tropics, Faculté de Pharmacie, Paris, France.
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16
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Achur RN, Muthusamy A, Madhunapantula SV, Gowda DC. Binding affinity of Plasmodium falciparum-infected erythrocytes from infected placentas and laboratory selected strains to chondroitin 4-sulfate. Mol Biochem Parasitol 2008; 159:79-84. [PMID: 18359524 DOI: 10.1016/j.molbiopara.2008.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 02/05/2008] [Accepted: 02/07/2008] [Indexed: 11/26/2022]
Abstract
The adherence of Plasmodium falciparum-infected red blood cells (IRBCs) in human placenta is mediated by chondroitin 4-sulfate (C4S). The C4S-adherent parasites selected from laboratory strains have been widely used for determining the C4S structural elements involved in IRBC binding and for the identification of parasite adhesive protein(s). However, as far as we know, the relative binding strength of the placental versus laboratory-selected parasites has not been reported. In this study, we show that IRBCs from the infected placentas bind to C4S about 3-fold higher than those selected for C4S adherence from laboratory strains. Although adherent parasites selected from several laboratory strains have comparable binding strengths, the one obtained from 3D7 parasites designated as 3D7N61 used for malaria genome sequencing, exhibits markedly lower binding strength. Furthermore, 3D7N61-CSA parasites lose most of the binding capacity by tenth generation in continuous culture.
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Affiliation(s)
- Rajeshwara N Achur
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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17
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Ueyama M, Takemae H, Ohmae Y, Yoshida H, Toyoda H, Ueda R, Nishihara S. Functional analysis of proteoglycan galactosyltransferase II RNA interference mutant flies. J Biol Chem 2007; 283:6076-84. [PMID: 18165227 DOI: 10.1074/jbc.m709189200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Heparan sulfate proteoglycan plays an important role in developmental processes by modulating the distribution and stability of the morphogens Wingless, Hedgehog, and Decapentaplegic. Heparan and chondroitin sulfates share a common linkage tetrasaccharide structure, GlcAbeta1,3Galbeta1,3Galbeta1,4Xylbeta-O-Ser. In the present study, we identified Drosophila proteoglycan galactosyltransferase II (dbeta3GalTII), determined its substrate specificity, and performed its functional analysis by using RNA interference (RNAi) mutant flies. The enzyme transferred a galactose to Galbeta1,4Xyl-pMph, confirming that it is the Drosophila ortholog of human proteoglycan galactosyltransferase II. Real-time PCR analyses revealed that dbeta3GalTII is expressed in various tissues and throughout development. The dbeta3GalTII RNAi mutant flies showed decreased amounts of heparan sulfate proteoglycans. A genetic interaction of dbeta3GalTII with Drosophila beta1,4-galactoslyltransferase 7 (dbeta4GalT7) or with six genes that encode enzymes contributing to the synthesis of glycosaminoglycans indicated that dbeta3GalTII is involved in heparan sulfate synthesis for wing and eye development. Moreover, dbeta3GalTII knock-down caused a decrease in extracellular Wingless in the wing imaginal disc of the third instar larvae. These results demonstrated that dbeta3GalTII contributes to heparan sulfate proteoglycan synthesis in vitro and in vivo and also modulates Wingless distribution.
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Affiliation(s)
- Morio Ueyama
- Laboratory of Cell Biology, Department of Bioinformatics, Faculty of Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo
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18
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Francis SE, Malkov VA, Oleinikov AV, Rossnagle E, Wendler JP, Mutabingwa TK, Fried M, Duffy PE. Six genes are preferentially transcribed by the circulating and sequestered forms of Plasmodium falciparum parasites that infect pregnant women. Infect Immun 2007; 75:4838-50. [PMID: 17698567 PMCID: PMC2044550 DOI: 10.1128/iai.00635-07] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In areas of stable malaria transmission, susceptibility to Plasmodium falciparum malaria increases during first pregnancy. Women become resistant to pregnancy malaria over successive pregnancies as they acquire antibodies against the parasite forms that sequester in the placenta, suggesting that a vaccine is feasible. Placental parasites are antigenically distinct and bind receptors, like chondroitin sulfate A (CSA), that are not commonly bound by other parasites. We used whole-genome-expression analysis to find transcripts that distinguish parasites of pregnant women from other parasites and employed a novel approach to define and adjust for cell cycle timing of parasites. Transcription of six genes was substantially higher in both placental parasites and peripheral parasites from pregnant women, and each gene encodes a protein with a putative export sequence and/or transmembrane domain. This cohort of genes includes var2csa, a member of the variant PfEMP1 gene family previously implicated in pregnancy malaria, as well as five conserved genes of unknown functions. Women in East Africa acquire antibodies over successive pregnancies against a protein encoded by one of these genes, PFD1140w, and this protein shows seroreactivity similar to that of VAR2CSA domains. These findings suggest that a suite of genes may be important for the genesis of the placental binding phenotype of P. falciparum and may provide novel targets for therapeutic intervention.
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Affiliation(s)
- Susan E Francis
- Seattle Biomedical Research Institute, 307 Westlake Ave. N, Seattle, WA 98109-5219, USA
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19
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Beeson JG, Andrews KT, Boyle M, Duffy MF, Choong EK, Byrne TJ, Chesson JM, Lawson AM, Chai W. Structural Basis for Binding of Plasmodium falciparum Erythrocyte Membrane Protein 1 to Chondroitin Sulfate and Placental Tissue and the Influence of Protein Polymorphisms on Binding Specificity. J Biol Chem 2007; 282:22426-36. [PMID: 17562715 DOI: 10.1074/jbc.m700231200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chondroitin sulfate (CS) A is a key receptor for adhesion of Plasmodium falciparum-infected erythrocytes (IEs) in the placenta and can also mediate adhesion to microvascular endothelial cells. IEs that adhere to CSA express var2csa-type genes, which encode specific variants of the IE surface antigen P. falciparum erythrocyte membrane protein 1 (PfEMP1). We report direct binding of native PfEMP1, isolated from IEs and encoded by var2csa, to immobilized CSA. Binding of PfEMP1 was dependent on 4-O-sulfated disaccharides and glucuronic acid rather than iduronic acid, consistent with the specificity of intact IEs. Using immobilized CS oligosaccharides as neoglycolipid probes, the minimum chain length for direct binding of PfEMP1 was eight monosaccharide units. Similarly for IE adhesion to placental tissue there was a requirement for 4-O-sulfated GalNAc and glucuronic acid mixed with non-sulfated disaccharides; 6-O-sulfation interfered with the interaction between placental CSA and IEs. The minimum chain length for maximal inhibition of adhesion was 10 monosaccharide residues. Partially 4-O-sulfated CS oligosaccharides (45-55% sulfation) were highly effective inhibitors of placental adhesion (IC(50), 0.15 microg/ml) and may have potential for therapeutic development. We used defined P. falciparum isolates expressing different variants of var2csa in adhesion assays and found that there were isolate-specific differences in the preferred structural motifs for adhesion to CSA that correlated with polymorphisms in PfEMP1 encoded by var2csa-type genes. This may influence sites of IE sequestration or parasite virulence. These findings have significant implications for understanding the pathogenesis and biology of malaria, particularly during pregnancy, and the development of targeted interventions.
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Affiliation(s)
- James G Beeson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia.
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Hviid L. Adhesion specificities of Plasmodium falciparum-infected erythrocytes involved in the pathogenesis of pregnancy-associated malaria. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 170:1817-9. [PMID: 17525250 PMCID: PMC1899449 DOI: 10.2353/ajpath.2007.070246] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Lars Hviid
- Department of International Health, Immunology, and Microbiology, Center for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital, CSS Building 22, Øster Farimagsgade 5, PO Box 2099, 1014 Copenhagen K, Denmark.
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21
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Madhunapantula SV, Achur RN, Bhavanandan VP, Gowda DC. The effect of substitution of the N-acetyl groups of N-acetylgalactosamine residues in chondroitin sulfate on its degradation by chondroitinase ABC. Glycoconj J 2007; 24:465-73. [PMID: 17533514 DOI: 10.1007/s10719-007-9039-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 03/05/2007] [Accepted: 04/11/2007] [Indexed: 10/23/2022]
Abstract
Chondroitinase ABC is a lyase that degrades chondroitin sulfate, dermatan sulfate and hyaluronic acid into disaccharides. The purpose of this study was to determine the ability of chondroitinase ABC to degrade chondroitin sulfate in which the N-acetyl groups are substituted with different acyl groups. The bovine tracheal chondroitin sulfate A (bCSA) was N-deacetylated by hydrazinolysis, and the free amino groups derivatized into N-formyl, N-propionyl, N-butyryl, N-hexanoyl or N-benzoyl amides. Treatment of the N-acyl or N-benzoyl derivatives of bCSA with chondroitinase ABC and analysis of the products showed that the N-formyl, N-hexanoyl and N-benzoyl derivatives are completely resistant to the enzyme. In contrast, the N-propionyl or N-butyryl derivatives were degraded into disaccharides with slower kinetics compared to that of unmodified bCSA. The rate of degradation of bCSA derivatives by the enzyme was found to be in the order of N-acetyl>N-propionyl>>N-butyryl bCSA. These results have important implications for understanding the interaction of N-acetyl groups of glycosaminoglycans with chondroitinase ABC.
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Affiliation(s)
- Subbarao V Madhunapantula
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA
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Nielsen MA, Resende M, Alifrangis M, Turner L, Hviid L, Theander TG, Salanti A. Plasmodium falciparum: VAR2CSA expressed during pregnancy-associated malaria is partially resistant to proteolytic cleavage by trypsin. Exp Parasitol 2007; 117:1-8. [PMID: 17442305 DOI: 10.1016/j.exppara.2007.03.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 03/01/2007] [Accepted: 03/02/2007] [Indexed: 10/23/2022]
Abstract
In areas of high Plasmodium falciparum transmission, immunity to malaria is acquired during childhood, so that adults in general are clinically immune. One exception is that first-time pregnant women are susceptible to pregnancy-associated malaria caused by accumulation of parasites in the placenta. Pregnancy-associated variant surface antigens (VSAPAM) mediate binding of the infected erythrocyte to chondroitin sulphate proteoglycans in the placental intervillous space. Several lines of evidence indicate that the molecular identity of VSAPAM is VAR2CSA, a relatively conserved member of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family. While native PfEMP1 molecules expressed on the infected erythrocyte surface generally are sensitive to mild trypsinization, some VSAPAM expressing parasite lines are resistant. This finding has led to the suggestion that molecules other than PfEMP1, or at least several different PfEMP1 families mediate the VSAPAM phenotype. To address this issue we incubated three different VAR2CSA expressing parasite lines with trypsin and found that polymorphic VAR2CSA variants can be both protease resistant and sensitive. Trypsin treatment resulted in loss of ability to adhere to CSA and loss of sex-specific antibody recognition of the surface of the infected erythrocyte in one sensitive isolate, whereas CSA binding and sex-specific recognition were largely unaffected by trypsin treatment in two resistant isolates. These results support the hypothesis that VAR2CSA mediates the adhesive and antigenic phenotypes shown by parasites causing placental malaria.
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Affiliation(s)
- Morten A Nielsen
- Centre for Medical Parasitology, Department of Infectious Diseases M4701, Copenhagen University Hospital (Rigshospitalet), Blegdamsvej 9, 2100 Copenhagen Ø, Denmark.
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