1
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Wu PC, Lee YQ, Möller M, Storry JR, Olsson ML. Elucidation of the low-expressing erythroid CR1 phenotype by bioinformatic mining of the GATA1-driven blood-group regulome. Nat Commun 2023; 14:5001. [PMID: 37591894 PMCID: PMC10435571 DOI: 10.1038/s41467-023-40708-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 08/08/2023] [Indexed: 08/19/2023] Open
Abstract
Genetic determinants underlying most human blood groups are now clarified but variation in expression levels remains largely unexplored. By developing a bioinformatics pipeline analyzing GATA1/Chromatin immunoprecipitation followed by sequencing (ChIP-seq) datasets, we identify 193 potential regulatory sites in 33 blood-group genes. As proof-of-concept, we aimed to delineate the low-expressing complement receptor 1 (CR1) Helgeson phenotype on erythrocytes, which is correlated with several diseases and protects against severe malaria. We demonstrate that two candidate CR1 enhancer motifs in intron 4 bind GATA1 and drive transcription. Both are functionally abolished by naturally-occurring SNVs. Erythrocyte CR1-mRNA and CR1 levels correlate dose-dependently with genotype of one SNV (rs11117991) in two healthy donor cohorts. Haplotype analysis of rs11117991 with previously proposed markers for Helgeson shows high linkage disequilibrium in Europeans but explains the poor prediction reported for Africans. These data resolve the longstanding debate on the genetic basis of inherited low CR1 and form a systematic starting point to investigate the blood group regulome.
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Affiliation(s)
- Ping Chun Wu
- Division of Hematology and Transfusion Medicine, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Yan Quan Lee
- Division of Hematology and Transfusion Medicine, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Mattias Möller
- Division of Hematology and Transfusion Medicine, Department of Laboratory Medicine, Lund University, Lund, Sweden
- Department of Clinical Genetics and Pathology, Office for Medical Services, Region Skåne, Lund, Sweden
| | - Jill R Storry
- Division of Hematology and Transfusion Medicine, Department of Laboratory Medicine, Lund University, Lund, Sweden
- Department of Clinical Immunology and Transfusion Medicine, Office for Medical Services, Region Skåne, Lund, Sweden
| | - Martin L Olsson
- Division of Hematology and Transfusion Medicine, Department of Laboratory Medicine, Lund University, Lund, Sweden.
- Department of Clinical Immunology and Transfusion Medicine, Office for Medical Services, Region Skåne, Lund, Sweden.
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2
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Nain M, Sharma A. Linkages between blood groups and malaria susceptibility. J Vector Borne Dis 2022; 59:193-197. [PMID: 36511034 DOI: 10.4103/0972-9062.345177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Blood typing has revolutionized the field of medical science since its discovery about a century ago. Besides its established role in life-saving blood transfusions, researchers have always been curious about the relationship between blood groups and human ailments. The effect of blood groups on disease outcomes, susceptibility, and mortality has been widely explored. According to a particular school of thought, the endemicity of diseases shapes the distribution of blood group frequency in human populations and exert selection pressure favoring one blood type over another. Here we discuss the scope and association of different blood groups in the context of malaria.
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Affiliation(s)
- Minu Nain
- ICMR-National Institute of Malaria Research, New Delhi 110077, India
| | - Amit Sharma
- ICMR-National Institute of Malaria Research, New Delhi 110077; Molecular Medicine Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India
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3
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Rosetting revisited: a critical look at the evidence for host erythrocyte receptors in Plasmodium falciparum rosetting. Parasitology 2019; 147:1-11. [PMID: 31455446 PMCID: PMC7050047 DOI: 10.1017/s0031182019001288] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Malaria remains a major cause of mortality in African children, with no adjunctive treatments currently available to ameliorate the severe clinical forms of the disease. Rosetting, the adhesion of infected erythrocytes (IEs) to uninfected erythrocytes, is a parasite phenotype strongly associated with severe malaria, and hence is a potential therapeutic target. However, the molecular mechanisms of rosetting are complex and involve multiple distinct receptor–ligand interactions, with some similarities to the diverse pathways involved in P. falciparum erythrocyte invasion. This review summarizes the current understanding of the molecular interactions that lead to rosette formation, with a particular focus on host uninfected erythrocyte receptors including the A and B blood group trisaccharides, complement receptor one, heparan sulphate, glycophorin A and glycophorin C. There is strong evidence supporting blood group A trisaccharides as rosetting receptors, but evidence for other molecules is incomplete and requires further study. It is likely that additional host erythrocyte rosetting receptors remain to be discovered. A rosette-disrupting low anti-coagulant heparin derivative is being investigated as an adjunctive therapy for severe malaria, and further research into the receptor–ligand interactions underlying rosetting may reveal additional therapeutic approaches to reduce the unacceptably high mortality rate of severe malaria.
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4
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Opi DH, Swann O, Macharia A, Uyoga S, Band G, Ndila CM, Harrison EM, Thera MA, Kone AK, Diallo DA, Doumbo OK, Lyke KE, Plowe CV, Moulds JM, Shebbe M, Mturi N, Peshu N, Maitland K, Raza A, Kwiatkowski DP, Rockett KA, Williams TN, Rowe JA. Two complement receptor one alleles have opposing associations with cerebral malaria and interact with α +thalassaemia. eLife 2018; 7:e31579. [PMID: 29690995 PMCID: PMC5953541 DOI: 10.7554/elife.31579] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Accepted: 04/01/2018] [Indexed: 12/13/2022] Open
Abstract
Malaria has been a major driving force in the evolution of the human genome. In sub-Saharan African populations, two neighbouring polymorphisms in the Complement Receptor One (CR1) gene, named Sl2 and McCb, occur at high frequencies, consistent with selection by malaria. Previous studies have been inconclusive. Using a large case-control study of severe malaria in Kenyan children and statistical models adjusted for confounders, we estimate the relationship between Sl2 and McCb and malaria phenotypes, and find they have opposing associations. The Sl2 polymorphism is associated with markedly reduced odds of cerebral malaria and death, while the McCb polymorphism is associated with increased odds of cerebral malaria. We also identify an apparent interaction between Sl2 and α+thalassaemia, with the protective association of Sl2 greatest in children with normal α-globin. The complex relationship between these three mutations may explain previous conflicting findings, highlighting the importance of considering genetic interactions in disease-association studies.
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Affiliation(s)
- D Herbert Opi
- Kenya Medical Research Institute-Wellcome Trust Research ProgrammeKilifiKenya
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Olivia Swann
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Alexander Macharia
- Kenya Medical Research Institute-Wellcome Trust Research ProgrammeKilifiKenya
| | - Sophie Uyoga
- Kenya Medical Research Institute-Wellcome Trust Research ProgrammeKilifiKenya
| | - Gavin Band
- Wellcome Trust Centre for Human GeneticsUniversity of OxfordOxfordUnited Kingdom
| | - Carolyne M Ndila
- Kenya Medical Research Institute-Wellcome Trust Research ProgrammeKilifiKenya
| | - Ewen M Harrison
- Centre for Medical InfomaticsUsher Insitute of Population Health Sciences and Informatics, University of EdinburghEdinburghUnited Kingdom
| | - Mahamadou A Thera
- Malaria Research and Training Centre, Faculty of Medicine, Pharmacy, and DentistryUniversity of BamakoBamakoMali
| | - Abdoulaye K Kone
- Malaria Research and Training Centre, Faculty of Medicine, Pharmacy, and DentistryUniversity of BamakoBamakoMali
| | - Dapa A Diallo
- Malaria Research and Training Centre, Faculty of Medicine, Pharmacy, and DentistryUniversity of BamakoBamakoMali
| | - Ogobara K Doumbo
- Malaria Research and Training Centre, Faculty of Medicine, Pharmacy, and DentistryUniversity of BamakoBamakoMali
| | - Kirsten E Lyke
- Division of Malaria Research, Institute for Global HealthUniversity of Maryland School of MedicineBaltimoreUnited States
| | - Christopher V Plowe
- Division of Malaria Research, Institute for Global HealthUniversity of Maryland School of MedicineBaltimoreUnited States
| | | | - Mohammed Shebbe
- Kenya Medical Research Institute-Wellcome Trust Research ProgrammeKilifiKenya
| | - Neema Mturi
- Kenya Medical Research Institute-Wellcome Trust Research ProgrammeKilifiKenya
| | - Norbert Peshu
- Kenya Medical Research Institute-Wellcome Trust Research ProgrammeKilifiKenya
| | - Kathryn Maitland
- Kenya Medical Research Institute-Wellcome Trust Research ProgrammeKilifiKenya
- Department of MedicineImperial CollegeLondonUnited Kingdom
| | - Ahmed Raza
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Dominic P Kwiatkowski
- Wellcome Trust Centre for Human GeneticsUniversity of OxfordOxfordUnited Kingdom
- Wellcome Trust Sanger InstituteCambridgeUnited Kingdom
| | - Kirk A Rockett
- Wellcome Trust Centre for Human GeneticsUniversity of OxfordOxfordUnited Kingdom
| | - Thomas N Williams
- Kenya Medical Research Institute-Wellcome Trust Research ProgrammeKilifiKenya
- Department of MedicineImperial CollegeLondonUnited Kingdom
| | - J Alexandra Rowe
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
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5
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Consequences of dysregulated complement regulators on red blood cells. Blood Rev 2018; 32:280-288. [PMID: 29397262 DOI: 10.1016/j.blre.2018.01.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 12/07/2017] [Accepted: 01/25/2018] [Indexed: 02/07/2023]
Abstract
The complement system represents the first line of defense that is involved in the clearance of pathogens, dying cells and immune complexes via opsonization, induction of an inflammatory response and the formation of a lytic pore. Red blood cells (RBCs) are very important for the delivery of oxygen to tissues and are continuously in contact with complement proteins in the blood plasma. To prevent complement activation on RBCs, various complement regulatory proteins can be found in plasma and on the cell membrane. RBCs are special cells without a nucleus and having a slightly different make-up of complement regulators than nucleated cells, as membrane cofactor protein (MCP) is not expressed and complement receptor 1 (CR1) is highly expressed. Decreased expression and/or function of complement regulatory proteins may result in unwanted complement activation and accelerated removal of RBCs. This review describes complement regulation on RBCs and the consequences when this regulation is out of balance.
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6
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Swann OV, Harrison EM, Opi DH, Nyatichi E, Macharia A, Uyoga S, Williams TN, Rowe JA. No Evidence that Knops Blood Group Polymorphisms Affect Complement Receptor 1 Clustering on Erythrocytes. Sci Rep 2017; 7:17825. [PMID: 29259218 PMCID: PMC5736761 DOI: 10.1038/s41598-017-17664-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 11/29/2017] [Indexed: 01/17/2023] Open
Abstract
Clustering of Complement Receptor 1 (CR1) in the erythrocyte membrane is important for immune-complex transfer and clearance. CR1 contains the Knops blood group antigens, including the antithetical pairs Swain-Langley 1 and 2 (Sl1 and Sl2) and McCoy a and b (McCa and McCb), whose functional effects are unknown. We tested the hypothesis that the Sl and McC polymorphisms might influence CR1 clustering on erythrocyte membranes. Blood samples from 125 healthy Kenyan children were analysed by immunofluorescence and confocal microscopy to determine CR1 cluster number and volume. In agreement with previous reports, CR1 cluster number and volume were positively associated with CR1 copy number (mean number of CR1 molecules per erythrocyte). Individuals with the McCb/McCb genotype had more clusters per cell than McCa/McCa individuals. However, this association was lost when the strong effect of CR1 copy number was included in the model. No association was observed between Sl genotype, sickle cell genotype, α+thalassaemia genotype, gender or age and CR1 cluster number or volume. Therefore, after correction for CR1 copy number, the Sl and McCoy polymorphisms did not influence erythrocyte CR1 clustering, and the effects of the Knops polymorphisms on CR1 function remains unknown.
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Affiliation(s)
- O V Swann
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - E M Harrison
- Clinical Surgery, University of Edinburgh, Edinburgh, UK
| | - D H Opi
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.,Wellcome Trust Research Laboratories/Kenya Medical Research Institute, Centre for Geographic Medicine Research, Kilifi, Kenya.,Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, 3004, Australia
| | - E Nyatichi
- Wellcome Trust Research Laboratories/Kenya Medical Research Institute, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - A Macharia
- Wellcome Trust Research Laboratories/Kenya Medical Research Institute, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - S Uyoga
- Wellcome Trust Research Laboratories/Kenya Medical Research Institute, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - T N Williams
- Wellcome Trust Research Laboratories/Kenya Medical Research Institute, Centre for Geographic Medicine Research, Kilifi, Kenya.,Department of Medicine, Imperial College, London, UK
| | - J A Rowe
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
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7
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Schroeder JH, McCarthy D, Szestak T, Cook DA, Taylor MJ, Craig AG, Lawson C, Lawrence RA. Brugia malayi microfilariae adhere to human vascular endothelial cells in a C3-dependent manner. PLoS Negl Trop Dis 2017; 11:e0005592. [PMID: 28481947 PMCID: PMC5436873 DOI: 10.1371/journal.pntd.0005592] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 05/18/2017] [Accepted: 04/23/2017] [Indexed: 01/17/2023] Open
Abstract
Brugia malayi causes the human tropical disease, lymphatic filariasis. Microfilariae (Mf) of this nematode live in the bloodstream and are ingested by a feeding mosquito vector. Interestingly, in a remarkable co-evolutionary adaptation, Mf appearance in the peripheral blood follows a circadian periodicity and reaches a peak when the mosquito is most likely to feed. For the remaining hours, the majority of Mf sequester in the lung capillaries. This circadian phenomenon has been widely reported and is likely to maximise parasite fitness and optimise transmission potential. However, the mechanism of Mf sequestration in the lungs remains largely unresolved. In this study, we demonstrate that B. malayi Mf can, directly adhere to vascular endothelial cells under static conditions and under flow conditions, they can bind at high (but not low) flow rates. High flow rates are more likely to be experienced diurnally. Furthermore, a non-periodic nematode adheres less efficiently to endothelial cells. Strikingly C3, the central component of complement, plays a crucial role in the adherence interaction. These novel results show that microfilariae have the ability to bind to endothelial cells, which may explain their sequestration in the lungs, and this binding is increased in the presence of inflammatory mediators.
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Affiliation(s)
- Jan-Hendrik Schroeder
- Royal Veterinary College, Department of Comparative Biomedical Sciences, Royal College Street, London, United Kingdom
| | | | - Tadge Szestak
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Darren A. Cook
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Mark J. Taylor
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Alister G. Craig
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Charlotte Lawson
- Royal Veterinary College, Department of Comparative Biomedical Sciences, Royal College Street, London, United Kingdom
| | - Rachel A. Lawrence
- Royal Veterinary College, Department of Comparative Biomedical Sciences, Royal College Street, London, United Kingdom
- * E-mail:
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8
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The Rheopathobiology of Plasmodium vivax and Other Important Primate Malaria Parasites. Trends Parasitol 2016; 33:321-334. [PMID: 28040374 DOI: 10.1016/j.pt.2016.11.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 11/17/2016] [Accepted: 11/28/2016] [Indexed: 12/11/2022]
Abstract
Our current understanding of how malaria parasites remodel their host red blood cells (RBCs) and ultimately cause disease is largely based on studies of Plasmodium falciparum. In this review, we expand our knowledge to include what is currently known about pathophysiological changes to RBCs that are infected by non-falciparum malaria parasites. We highlight the potential folly of making generalizations about the rheology of malaria infection, and emphasize the need for more systematic studies into the erythrocytic biology of non-falciparum malaria parasites. We propose that a better understanding of the mechanisms that underlie the changes to RBCs induced by malaria parasites other than P. falciparum may be highly informative for the development of therapeutics that specifically disrupt the altered rheological profile of RBCs infected with either sexual- or asexual-stage parasites, resulting in drugs that block transmission, reduce disease severity, and help delay the onset of resistance to current and future anti-malaria drugs.
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9
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Erythrogene: a database for in-depth analysis of the extensive variation in 36 blood group systems in the 1000 Genomes Project. Blood Adv 2016; 1:240-249. [PMID: 29296939 DOI: 10.1182/bloodadvances.2016001867] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/11/2016] [Indexed: 01/22/2023] Open
Abstract
Blood group genotyping has recently developed into a clinical tool to improve compatibility of blood transfusions and management of pregnancies. Next-generation sequencing (NGS) is rapidly moving toward routine practice for patient and donor typing and has the potential to remedy some of the limitations of currently used platforms. However, a large-scale investigation into the blood group genotypes obtained by NGS in a multiethnic cohort is lacking. The 1000 Genomes Project provides information on genome variation among 2504 individuals representing 26 populations worldwide. We extracted their NGS data for all 36 blood group systems to a custom-designed database. In total, 210 412 alleles from 43 blood group-related genes were imported and curated. Matching algorithms were developed to compare them to blood group variants identified to date. Of the 1241 non-synonymous variants identified in the coding regions, 241 are known blood group polymorphisms. Interestingly, 357 of the remaining 1000 variants are predicted to occur on extracellular portions of 31 different blood group-carrying proteins and some may represent undiscovered antigens. Of the alleles analyzed, 1504 were not previously described. The ABO/GBGT1/FUT2/FUT3 and GYPB/GYPC genes showed the highest degree of variation per kilobase coding sequence, and ACKR1 variants had the most skewed distribution across 5 continental superpopulations in the dataset. Results were exported to an online search engine, www.erythrogene.com, which presents data according to the allele nomenclature developed for clinical reporting by the International Society of Blood Transfusion. The established database deepens our knowledge on blood group polymorphism globally and provides a long-sought platform for future research.
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10
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Red blood cell complement receptor one level varies with Knops blood group, α(+)thalassaemia and age among Kenyan children. Genes Immun 2016; 17:171-8. [PMID: 26844958 PMCID: PMC4842007 DOI: 10.1038/gene.2016.2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 11/06/2015] [Accepted: 11/11/2015] [Indexed: 12/25/2022]
Abstract
Both the invasion of red blood cells (RBCs) by Plasmodium falciparum parasites and the sequestration of parasite-infected RBCs in the microvasculature are mediated in part by complement receptor one (CR1). RBC surface CR1 level can vary between individuals by more than 20-fold and may be associated with the risk of severe malaria. The factors that influence RBC CR1 level variation are poorly understood, particularly in African populations. We studied 3535 child residents of a malaria-endemic region of coastal Kenya and report, for the first time, that the CR1 Knops blood group alleles Sl2 and McC(b), and homozygous HbSS are positively associated with RBC CR1 level. Sickle cell trait and ABO blood group did not influence RBC CR1 level. We also confirm the previous observation that α(+)thalassaemia is associated with reduced RBC CR1 level, possibly due to small RBC volume, and that age-related changes in RBC CR1 expression occur throughout childhood. RBC CR1 level in malaria-endemic African populations is a complex phenotype influenced by multiple factors that should be taken into account in the design and interpretation of future studies on CR1 and malaria susceptibility.
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11
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Global selection of Plasmodium falciparum virulence antigen expression by host antibodies. Sci Rep 2016; 6:19882. [PMID: 26804201 PMCID: PMC4726288 DOI: 10.1038/srep19882] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 12/21/2015] [Indexed: 12/22/2022] Open
Abstract
Parasite proteins called PfEMP1 that are inserted on the surface of infected erythrocytes, play a key role in the severe pathology associated with infection by the Plasmodium falciparum malaria parasite. These proteins mediate binding of infected cells to the endothelial lining of blood vessels as a strategy to avoid clearance by the spleen and are major targets of naturally acquired immunity. PfEMP1 is encoded by a large multi-gene family called var. Mutually-exclusive transcriptional switching between var genes allows parasites to escape host antibodies. This study examined in detail the patterns of expression of var in a well-characterized sample of parasites from Kenyan Children. Instead of observing clear inverse relationships between the expression of broad sub-classes of PfEMP1, we found that expression of different PfEMP1 groups vary relatively independently. Parasite adaptation to host antibodies also appears to involve a general reduction in detectable var gene expression. We suggest that parasites switch both between different PfEMP1 variants and between high and low expression states. Such a strategy could provide a means of avoiding immunological detection and promoting survival under high levels of host immunity.
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12
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Architecture of Human IgM in Complex with P. falciparum Erythrocyte Membrane Protein 1. Cell Rep 2016; 14:723-736. [PMID: 26776517 DOI: 10.1016/j.celrep.2015.12.067] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 09/30/2015] [Accepted: 12/11/2015] [Indexed: 11/23/2022] Open
Abstract
Plasmodium falciparum virulence is associated with sequestration of infected erythrocytes. Microvascular binding mediated by PfEMP1 in complex with non-immune immunoglobulin M (IgM) is common among parasites that cause both severe childhood malaria and pregnancy-associated malaria. Here, we present cryo-molecular electron tomography structures of human IgM, PfEMP1 and their complex. Three-dimensional reconstructions of IgM reveal that it has a dome-like core, randomly oriented Fab2s units, and the overall shape of a turtle. PfEMP1 is a C- shaped molecule with a flexible N terminus followed by an arc-shaped backbone and a bulky C terminus that interacts with IgM. Our data demonstrate that the PfEMP1 binding pockets on IgM overlap with those of C1q, and the bulkiness of PfEMP1 limits the capacity of IgM to interact with PfEMP1. We suggest that P. falciparum exploits IgM to cluster PfEMP1 into an organized matrix to augment its affinity to host cell receptors.
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13
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Niang M, Bei AK, Madnani KG, Pelly S, Dankwa S, Kanjee U, Gunalan K, Amaladoss A, Yeo KP, Bob NS, Malleret B, Duraisingh MT, Preiser PR. STEVOR is a Plasmodium falciparum erythrocyte binding protein that mediates merozoite invasion and rosetting. Cell Host Microbe 2015; 16:81-93. [PMID: 25011110 DOI: 10.1016/j.chom.2014.06.004] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Revised: 05/06/2014] [Accepted: 06/03/2014] [Indexed: 10/25/2022]
Abstract
Variant surface antigens play an important role in Plasmodium falciparum malaria pathogenesis and in immune evasion by the parasite. Although most work to date has focused on P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1), two other multigene families encoding STEVOR and RIFIN are expressed in invasive merozoites and on the infected erythrocyte surface. However, their role during parasite infection remains to be clarified. Here we report that STEVOR functions as an erythrocyte-binding protein that recognizes Glycophorin C (GPC) on the red blood cell (RBC) surface and that its binding correlates with the level of GPC on the RBC surface. STEVOR expression on the RBC leads to PfEMP1-independent binding of infected RBCs to uninfected RBCs (rosette formation), while antibodies targeting STEVOR in the merozoite can effectively inhibit invasion. Our results suggest a PfEMP1-independent role for STEVOR in enabling infected erythrocytes at the schizont stage to form rosettes and in promoting merozoite invasion.
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Affiliation(s)
- Makhtar Niang
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Amy Kristine Bei
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Kripa Gopal Madnani
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Shaaretha Pelly
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Selasi Dankwa
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Usheer Kanjee
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Karthigayan Gunalan
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Anburaj Amaladoss
- Singapore-MIT Alliance for Research and Technology (SMART)-Interdisciplinary Research Group in Infectious Diseases, Singapore 117456, Singapore
| | - Kim Pin Yeo
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Ndeye Sakha Bob
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Benoit Malleret
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore 117545, Singapore; Singapore Immunology Network, A(∗)STAR, Singapore 138648, Singapore
| | - Manoj Theodore Duraisingh
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Peter Rainer Preiser
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore.
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14
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Abstract
Blood group antigens represent polymorphic traits inherited among individuals and populations. At present, there are 34 recognized human blood groups and hundreds of individual blood group antigens and alleles. Differences in blood group antigen expression can increase or decrease host susceptibility to many infections. Blood groups can play a direct role in infection by serving as receptors and/or coreceptors for microorganisms, parasites, and viruses. In addition, many blood group antigens facilitate intracellular uptake, signal transduction, or adhesion through the organization of membrane microdomains. Several blood groups can modify the innate immune response to infection. Several distinct phenotypes associated with increased host resistance to malaria are overrepresented in populations living in areas where malaria is endemic, as a result of evolutionary pressures. Microorganisms can also stimulate antibodies against blood group antigens, including ABO, T, and Kell. Finally, there is a symbiotic relationship between blood group expression and maturation of the gastrointestinal microbiome.
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Affiliation(s)
- Laura Cooling
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA
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15
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Tettey R, Ayeh-Kumi P, Tettey P, Adjei GO, Asmah RH, Dodoo D. Severity of malaria in relation to a complement receptor 1 polymorphism: a case-control study. Pathog Glob Health 2015; 109:247-52. [PMID: 25916414 DOI: 10.1179/2047773215y.0000000011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
BACKGROUND Studies on the relationship between complement receptor 1 (CR1) polymorphisms in exon 29 encoding the Knops blood group antigens (Swain-Langley (Sl) and McCoy (McC)) and outcome of clinical malaria have produced inconsistent results. METHODS Blood samples from Ghanaian children (n = 150) aged 1-12 years with complicated and uncomplicated malaria were genotyped for the Sl and McC blood group alleles by polymerase chain reaction and restriction fragment length polymorphism. Effect of Sl and McC genotypes on the clinical outcome of malaria was evaluated using logistic regression. RESULTS McCa/b genotype was significantly associated with more than two-fold increased susceptibility for severe malaria (OR = 2.31; 95% CI: 1.03-5.20, P = 0.043). However, McCb/b was associated with an 88% reduced risk of severe malaria (OR = 0.12; 95% CI: 0.02-0.64, P = 0.013). In contrast, there was no significant association between severe malaria and Sl1/1, Sl1/2, Sl2/and McCa/a genotypes. There was a trend towards decreased susceptibility to both cerebral malaria (CM) (OR = 0.13; 95% CI: 0.02-1.15, P = 0.07) and severe malarial anaemia (SA) (OR = 0.14; 95% CI: 0.02-1.19, P = 0.07) for McCb/b genotype when compared with the McCa/a genotype. There were no significant associations between Sl1/2 or Sl2/2 genotype and CM or SA when compared with Sl1/1 genotype. CONCLUSIONS McCa/b was associated with increased susceptibility to severe malaria and McCb/b associated with reduced risk of severe malaria. Further studies with large sample size in other malaria endemic regions in Africa are warranted to confirm these findings.
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Schmidt CQ, Kennedy AT, Tham WH. More than just immune evasion: Hijacking complement by Plasmodium falciparum. Mol Immunol 2015; 67:71-84. [PMID: 25816986 DOI: 10.1016/j.molimm.2015.03.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Revised: 03/04/2015] [Accepted: 03/04/2015] [Indexed: 12/24/2022]
Abstract
Malaria remains one of the world's deadliest diseases. Plasmodium falciparum is responsible for the most severe and lethal form of human malaria. P. falciparum's life cycle involves two obligate hosts: human and mosquito. From initial entry into these hosts, malaria parasites face the onslaught of the first line of host defence, the complement system. In this review, we discuss the complex interaction between complement and malaria infection in terms of hosts immune responses, parasite survival and pathogenesis of severe forms of malaria. We will focus on the role of complement receptor 1 and its associated polymorphisms in malaria immune complex clearance, as a mediator of parasite rosetting and as an entry receptor for P. falciparum invasion. Complement evasion strategies of P. falciparum parasites will also be highlighted. The sexual forms of the malaria parasites recruit the soluble human complement regulator Factor H to evade complement-mediated killing within the mosquito host. A novel evasion strategy is the deployment of parasite organelles to divert complement attack from infective blood stage parasites. Finally we outline the future challenge to understand the implications of these exploitation mechanisms in the interplay between successful infection of the host and pathogenesis observed in severe malaria.
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Affiliation(s)
- Christoph Q Schmidt
- Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, Helmholtzstraße 20, Ulm, Germany.
| | - Alexander T Kennedy
- Department of Medical Biology, University of Melbourne and Division of Infection and Immunity, The Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia
| | - Wai-Hong Tham
- Department of Medical Biology, University of Melbourne and Division of Infection and Immunity, The Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia.
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Duru KC, Noble JA, Guindo A, Yi L, Imumorin IG, Diallo DA, Thomas BN. Extensive genomic variability of knops blood group polymorphisms is associated with sickle cell disease in Africa. Evol Bioinform Online 2015; 11:25-33. [PMID: 25788827 PMCID: PMC4357628 DOI: 10.4137/ebo.s23132] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 01/27/2015] [Accepted: 02/02/2015] [Indexed: 01/21/2023] Open
Abstract
Sickle cell disease (SCD) is a multisystem disorder characterized by chronic hemolytic anemia, vaso-occlusive crises, and marked variability in disease severity. Patients require transfusions to manage disease complications, with complements, directed by complement regulatory genes (CR1) and its polymorphisms, implicated in the development of alloantibodies. We hypothesize that CR1 polymorphisms affect complement regulation and function, leading to adverse outcome in SCD. To this end, we determined the genomic diversity of complement regulatory genes by examining single nucleotide polymorphisms associated with Knops blood group antigens. Genomic DNA samples from 130 SCD cases and 356 control Africans, 331 SCD cases and 497 control African Americans, and 254 Caucasians were obtained and analyzed, utilizing a PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) assay. Analyzing for ethnic diversity, we found significant differences in the genotypic and allelic frequencies of Sl1/Sl2 (rs17047661) and McCa/b (rs17047660) polymorphisms between Africans, African Americans, and Caucasians (P < 0.05). The homozygote mutant variants had significantly higher frequencies in Africans and African Americans but were insignificant in Caucasians (80.2% and 59.6% vs 5.9% for Sl1/2; and 36% and 24% vs 1.8% for McCa/b). With SCD, we did not detect any difference among cases and controls either in Africa or in the United States. However, we found significant difference in genotypic (P < 0.0001) and allelic frequencies (P < 0.0001) of Sl1/Sl2 (rs17047661) and McCa/b (rs17047660) polymorphisms between SCD groups from Africa and the United States. There was no difference in haplotype frequencies of these polymorphisms among or between groups. The higher frequency of CR1 homozygote mutant variants in Africa but not United States indicates a potential pathogenic role, possibly associated with complicated disease pathophysiology in the former and potentially protective in the latter. The difference between sickle cell groups suggests potential genetic drift or founder effect imposed on the disease in the United States, but not in Africa, and a possible confirmation of the ancestral susceptibility hypothesis. The lower haplotype frequencies among sickle cell and control populations in the United States may be due to the admixture and the dilution of African genetic ancestry in the African American population.
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Affiliation(s)
- Kimberley C Duru
- Department of Biomedical Sciences, College of Health Sciences and Technology, Rochester Institute of Technology, Rochester, NY, USA
| | - Jenelle A Noble
- Department of Biomedical Sciences, College of Health Sciences and Technology, Rochester Institute of Technology, Rochester, NY, USA
| | - Aldiouma Guindo
- Centre de Recherche et de Lutte contre la Drepanocytose (CRLD), Bamako, Mali
| | - Li Yi
- School of Statistics, Shanxi University of Finance and Economics, Shanxi, China
| | - Ikhide G Imumorin
- Animal Genetics and Genomics Lab, Office of International Programs, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, USA
| | - Dapa A Diallo
- Centre de Recherche et de Lutte contre la Drepanocytose (CRLD), Bamako, Mali
| | - Bolaji N Thomas
- Department of Biomedical Sciences, College of Health Sciences and Technology, Rochester Institute of Technology, Rochester, NY, USA
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Binding of subdomains 1/2 of PfEMP1-DBL1α to heparan sulfate or heparin mediates Plasmodium falciparum rosetting. PLoS One 2015; 10:e0118898. [PMID: 25742651 PMCID: PMC4351205 DOI: 10.1371/journal.pone.0118898] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 01/20/2015] [Indexed: 11/24/2022] Open
Abstract
The capacity of Plasmodium falciparum parasitized erythrocytes (pRBC) to adhere to the endothelial lining in the microvasculature and to red blood cells (RBC) is associated with the virulence of the parasite, the pathogenesis and development of severe malaria. Rosetting, the binding of uninfected RBC to pRBC, is frequently observed in individuals with severe malaria and is mediated by the N-terminal NTS-DBL1α domain of the adhesin Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) expressed at the surface of the pRBC. Heparan sulfate has been suggested to be an important receptor for the NTS-DBL1α variant IT4var60 expressed by the parasite FCR3S1.2. Here, we have determined the binding site of NTS-DBL1α (IT4var60) to the RBC and heparin using a set of recombinant, mutated proteins expressed in and purified from E. coli. All the variants were studied for their ability to bind to RBC, their capacities to disrupt FCR3S1.2 rosettes, their affinities for heparin and their binding to rosette-disruptive mAbs. Our results suggest that NTS-DBL1α mediates binding to RBC through a limited number of basic amino acid residues localized on the surface of subdomains 1 (SD1) and 2 (SD2). The SD2-binding site is localized in close proximity to one of two previously identified binding sites in the rosetting PfEMP1 of the parasite PaloAlto-varO. The binding site in SD2 of NTS-DBL1α could represent a template for the development of anti-rosetting drugs.
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Lan Y, Wei CD, Chen WC, Wang JL, Wang CF, Pan GG, Wei YS, Nong LG. Association of the single-nucleotide polymorphism and haplotype of the complement receptor 1 gene with malaria. Yonsei Med J 2015; 56:332-9. [PMID: 25683978 PMCID: PMC4329341 DOI: 10.3349/ymj.2015.56.2.332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
PURPOSE Although the polymorphisms of erythrocyte complement receptor type 1 (CR1) in patients with malaria have been extensively studied, a question of whether the polymorphisms of CR1 are associated with severe malaria remains controversial. Furthermore, no study has examined the association of CR1 polymorphisms with malaria in Chinese population. Therefore, we investigated the relationship of CR1 gene polymorphism and malaria in Chinese population. MATERIALS AND METHODS We analyzed polymorphisms of CR1 gene rs2274567 G/A, rs4844600 G/A, and rs2296160 C/T in 509 patients with malaria and 503 controls, using the Taqman genotyping assay and PCR-direct sequencing. RESULTS There were no significant differences in the genotype, allele and haplotype frequencies of CR1 gene rs2274567 G/A, rs4844600 G/A, and rs2296160 C/T polymorphisms between patients with malaria and controls. Furthermore, there was no association of polymorphisms in the CR1 gene with the severity of malaria in Chinese population. CONCLUSION These findings suggest that CR1 gene rs2274567 G/A, rs4844600 G/A, and rs2296160 C/T polymorphisms may not be involved in susceptibility to malaria in Chinese population.
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Affiliation(s)
- Yan Lan
- Department of Dermatology, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, P. R. China
| | - Chuan-Dong Wei
- Department of Laboratory Medicine, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, P. R. China
| | - Wen-Cheng Chen
- Department of Laboratory Medicine, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, P. R. China
| | - Jun-Li Wang
- Department of Laboratory Medicine, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, P. R. China
| | - Chun-Fang Wang
- Department of Laboratory Medicine, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, P. R. China
| | - Guo-Gang Pan
- Department of Laboratory Medicine, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, P. R. China
| | - Ye-Sheng Wei
- Department of Laboratory Medicine, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, P. R. China.
| | - Le-Gen Nong
- Institute of Medical Laboratory, Youjiang Medical University for Nationalities, Baise, Guangxi, P. R. China.
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Rosetting Plasmodium falciparum-infected erythrocytes bind to human brain microvascular endothelial cells in vitro, demonstrating a dual adhesion phenotype mediated by distinct P. falciparum erythrocyte membrane protein 1 domains. Infect Immun 2013; 82:949-59. [PMID: 24343658 PMCID: PMC3958005 DOI: 10.1128/iai.01233-13] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adhesion interactions between Plasmodium falciparum-infected erythrocytes (IE) and human cells underlie the pathology of severe malaria. IE cytoadhere to microvascular endothelium or form rosettes with uninfected erythrocytes to survive in vivo by sequestering IE in the microvasculature and avoiding splenic clearance mechanisms. Both rosetting and cytoadherence are mediated by the parasite-derived IE surface protein family Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). Rosetting and cytoadherence have been widely studied as separate entities; however, the ability of rosetting P. falciparum strains to cytoadhere has received little attention. Here, we show that IE of the IT/R29 strain expressing a rosette-mediating PfEMP1 variant (IT4var09) cytoadhere in vitro to a human brain microvascular endothelial cell line (HBEC-5i). Cytoadherence was inhibited by heparin and by treatment of HBEC-5i with heparinase III, suggesting that the endothelial receptors for IE binding are heparan sulfate proteoglycans. Antibodies to the N-terminal regions of the IT4var09 PfEMP1 variant (NTS-DBL1α and DBL2γ domains) specifically inhibited and reversed cytoadherence down to low concentrations (<10 μg/ml of total IgG). Surface plasmon resonance experiments showed that the NTS-DBLα and DBL2γ domains bind strongly to heparin, with half-maximal binding at a concentration of ∼0.5 μM in both cases. Therefore, cytoadherence of IT/R29 IE is distinct from rosetting, which is primarily mediated by NTS-DBL1α interactions with complement receptor 1. These data show that IT4var09-expressing parasites are capable of dual interactions with both endothelial cells and uninfected erythrocytes via distinct receptor-ligand interactions.
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Hansson HH, Kurtzhals JA, Goka BQ, Rodriques OP, Nkrumah FN, Theander TG, Bygbjerg IC, Alifrangis M. Human genetic polymorphisms in the Knops blood group are not associated with a protective advantage against Plasmodium falciparum malaria in Southern Ghana. Malar J 2013; 12:400. [PMID: 24200236 PMCID: PMC4226212 DOI: 10.1186/1475-2875-12-400] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 10/23/2013] [Indexed: 11/25/2022] Open
Abstract
Background The complex interactions between the human host and the Plasmodium falciparum parasite and the factors influencing severity of disease are still not fully understood. Human single nucleotide polymorphisms SNPs associated with Knops blood group system; carried by complement receptor 1 may be associated with the pathology of P. falciparum malaria, and susceptibility to disease. Methods The objective of this study was to determine the genotype and haplotype frequencies of the SNPs defining the Knops blood group antigens; Kna/b, McCoya/b, Swain-Langley1/2 and KCAM+/- in Ghanaian patients with malaria and determine possible associations between these polymorphisms and the severity of the disease. Study participants were patients (n = 267) admitted to the emergency room at the Department of Child Health, Korle-Bu Teaching Hospital, Accra, Ghana during the malaria season from June to August in 1995, 1996 and 1997, classified as uncomplicated malaria (n = 89), severe anaemia (n = 57) and cerebral malaria (n = 121) and controls who did not have a detectable Plasmodium infection or were symptomless carriers of the parasite (n = 275). The frequencies were determined using a post-PCR ligation detection reaction-fluorescent microsphere assay, developed to detect the SNPs defining the antigens. Chi-square/Fisher’s exact test and logistic regression models were used to analyse the data. Results As expected, high frequencies of the alleles Kna, McCb, Sl2 and KCAM- were found in the Ghanaian population. Apart from small significant differences between the groups at the Sl locus, no significant allelic or genotypic differences were found between the controls and the disease groups or between the disease groups. The polymorphisms define eight different haplotypes H1(2.4%), H2(9.4%), H3(59.8%), H4(0%), H5(25.2%), H6(0.33%), H7(2.8%) and H8(0%). Investigating these haplotypes, no significant differences between any of the groups were found. Conclusion The results confirm earlier findings of high frequencies of certain CR1 alleles in Africa; and shed more light on earlier conflicting findings; the alleles McCb, Sl2, Knb and KCAM- or combined haplotypes do not seem to confer any protective advantage against malaria infection or resulting disease severity. Based on these findings, in a very well-characterized population, malaria does not seem to be the selective force on these alleles.
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Affiliation(s)
- Helle H Hansson
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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The effect of anti-rosetting agents against malaria parasites under physiological flow conditions. PLoS One 2013; 8:e73999. [PMID: 24066091 PMCID: PMC3774797 DOI: 10.1371/journal.pone.0073999] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 07/29/2013] [Indexed: 12/17/2022] Open
Abstract
Rosetting remains the dominant malaria parasite adhesion phenotype associated with severe disease and pathogenicity in Africa. The formation of rosettes, whereby a Plasmodium falciparum infected erythrocyte (IE) adheres to two or more non-IEs, is thought to facilitate the occlusion of microvascular blood vessels by adhering to host endothelial cells and other bound IEs. Current methods of determining the rosette-disrupting capabilities of antibodies/drugs have focused on static assays. As IEs in vivo are exposed to shear stresses within the microvasculature, the effect of flow conditions on rosetting requires further examination. This study establishes a new rosetting flow assay using a closed perfusion system together with inverted fluorescence microscopy and image analysis, and confirms previous reports that rosettes exist under shear stresses equivalent to those present in the microvasculature (0.5–1.0 dyn/cm2). Furthermore, we tested the effectiveness of rosette-disrupting PfEMP1 antibodies, heparin and fucoidan over a range of concentrations on two P. falciparum strains, and found no statistically significant differences between the results of static and flow assays. The new flow assay is a valuable addition to the tools available to study rosetting. However, the static assay has good predictive value and remains useful as the standard screening test for rosette-disrupting interventions.
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Jacquet M, Lacroix M, Ancelet S, Gout E, Gaboriaud C, Thielens NM, Rossi V. Deciphering complement receptor type 1 interactions with recognition proteins of the lectin complement pathway. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2013; 190:3721-31. [PMID: 23460739 DOI: 10.4049/jimmunol.1202451] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Complement receptor type 1 (CR1) is a membrane receptor expressed on a wide range of cells. It is involved in immune complex clearance, phagocytosis, and complement regulation. Its ectodomain is composed of 30 complement control protein (CCP) modules, organized into four long homologous repeats (A-D). In addition to its main ligands C3b and C4b, CR1 was reported to interact with C1q and mannan-binding lectin (MBL) likely through its C-terminal region (CCP22-30). To decipher the interaction of human CR1 with the recognition proteins of the lectin complement pathway, a recombinant fragment encompassing CCP22-30 was expressed in eukaryotic cells, and its interaction with human MBL and ficolins was investigated using surface plasmon resonance spectroscopy. MBL and L-ficolin were shown to interact with immobilized soluble CR1 and CR1 CCP22-30 with apparent dissociation constants in the nanomolar range, indicative of high affinity. The binding site for CR1 was located at or near the MBL-associated serine protease (MASP) binding site in the collagen stalks of MBL and L-ficolin, as shown by competition experiments with MASP-3. Accordingly, the mutation of an MBL conserved lysine residue essential for MASP binding (K55) abolished binding to soluble CR1 and CCP22-30. The CR1 binding site for MBL/ficolins was mapped to CCP24-25 of long homologous repeat D using deletion mutants. In conclusion, we show that ficolins are new CR1 ligands and propose that MBL/L-ficolin binding involves major ionic interactions between conserved lysine residues of their collagen stalks and surface exposed acidic residues located in CR1 CCP24 and/or CCP25.
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Affiliation(s)
- Mickaël Jacquet
- Commissariat à l'Energie Atomique, Institut de Biologie Structurale Jean-Pierre Ebel, 38027 Grenoble Cedex 1, France
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Analysis of antibody induction upon immunization with distinct NTS-DBL1α-domains of PfEMP1 from rosetting Plasmodium falciparum parasites. Malar J 2013; 12:32. [PMID: 23347690 PMCID: PMC3599323 DOI: 10.1186/1475-2875-12-32] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 01/22/2013] [Indexed: 11/15/2022] Open
Abstract
Background Rosette-formation of Plasmodium falciparum parasitized erythrocytes is of importance in the development of severe malaria. The parasite-derived molecule PfEMP1 (Plasmodium falciparum erythrocyte membrane protein 1), central to rosetting, is suggested to be included in a multimeric vaccine targeting severe disease. Methods Three recombinant NTS-DBL1α-domains of PfEMP1 were generated in Escherichia coli, purified and used for immunization of rats and goats. Antibody titres were determined in ELISA assays and responses were compared in-between different individual animals and species. Reactivity with the parasites was tested in live pRBC using FACS. B-cell epitopes prediction was carried out in silico and compared to the results obtained by peptide microarray. Screening for serological cross-reactivity with heterologous NTS-DBL1α variants was carried out by ELISA, peptide array and FACS on pRBC of different laboratory strains and patient isolates. Results All three NTS-DBL1α-domains induced high titres of antibodies that were biologically active with no apparent difference between constructs covering slightly different parts of the DBL1α-sequence. The different animal species showed comparable titres of antibodies, while variations within individuals of the species could be observed. Mapping of the recognized epitopes revealed that most parts of the molecule were able to induce an antibody response with a tendency for the N and C terminal parts of the molecule for slightly higher recognition. Important differences to the epitopes predicted were found as some of the most conserved parts of the DBL1α-domain contained the main epitopes for antibody reactivity. ELISA assays and peptide microarray demonstrated substantial cross-reactivity to heterologous variants, while binding to native PfEMP1 was observed only in few combinations on the pRBC surface, underlining that mainly internal, conserved and not surface exposed parts of the DBL1α-domain are responsible for this observation. Conclusion Biologically active antibodies can be induced consistently, with high titres, in different animal species and the antibodies elicited by different constructs react with similar epitopes. Induced antibodies recognize epitopes localized in all subdomains of the DBL1α-sequence. Cross-reactivity between NTS-DBL1α-variants is common in ELISA, but rare with live pRBC emphasizing that also internal, conserved areas of PfEMP1 carry important highly immunogenic epitopes of the molecule.
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The host genetic diversity in malaria infection. J Trop Med 2012; 2012:940616. [PMID: 23316245 PMCID: PMC3532872 DOI: 10.1155/2012/940616] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 11/06/2012] [Accepted: 11/19/2012] [Indexed: 02/06/2023] Open
Abstract
Populations exposed to Plasmodium infection develop genetic mechanisms of protection against severe disease. The clinical manifestation of malaria results primarily from the lysis of infected erythrocytes and subsequent immune and inflammatory responses. Herein, we review the genetic alterations associated with erythrocytes or mediators of the immune system, which might influence malaria outcome. Moreover, polymorphisms in genes related to molecules involved in mechanisms of cytoadherence and their influence on malaria pathology are also discussed. The results of some studies have suggested that the combinatorial effects of a set of genetic factors in the erythrocyte-immunology pathway might be relevant to host resistance or susceptibility against Plasmodium infection. However, these results must be interpreted with caution because of the differences observed in the functionality and frequency of polymorphisms within different populations. With the recent advances in molecular biology techniques, more robust studies with reliable data have been reported, and the results of these studies have identified individual genetic factors for consideration in preventing severe disease and the individual response to treatment.
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Mugasa J, Qi W, Rusch S, Rottmann M, Beck HP. Genetic diversity of expressed Plasmodium falciparum var genes from Tanzanian children with severe malaria. Malar J 2012; 11:230. [PMID: 22799500 PMCID: PMC3488018 DOI: 10.1186/1475-2875-11-230] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 07/02/2012] [Indexed: 11/17/2022] Open
Abstract
Background Severe malaria has been attributed to the expression of a restricted subset of the var multi-gene family, which encodes for Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). PfEMP1 mediates cytoadherence and sequestration of infected erythrocytes into the post-capillary venules of vital organs such as the brain, lung or placenta. var genes are highly diverse and can be classified in three major groups (ups A, B and C) and two intermediate groups (B/A and B/C) based on the genomic location, gene orientation and upstream sequences. The genetic diversity of expressed var genes in relation to severity of disease in Tanzanian children was analysed. Methods Children with defined severe (SM) and asymptomatic malaria (AM) were recruited. Full-length var mRNA was isolated and reversed transcribed into var cDNA. Subsequently, the DBL and N-terminal domains, and up-stream sequences were PCR amplified, cloned and sequenced. Sequences derived from SM and AM isolates were compared and analysed. Results The analysis confirmed that the var family is highly diverse in natural Plasmodium falciparum populations. Sequence diversity of amplified var DBL-1α and upstream regions showed minimal overlap among isolates, implying that the var gene repertoire is vast and most probably indefinite in endemic areas. var DBL-1α sequences from AM isolates were more diverse with more singletons found (p<0.05) than those from SM infections. Furthermore, few var DBL-1α sequences from SM patients were rare and restricted suggesting that certain PfEMP1 variants might induce severe disease. Conclusions The genetic sequence diversity of var genes of P. falciparum isolates from Tanzanian children is large and its relationship to disease severity has been studied. Observed differences suggest that different var genes might have fundamentally different roles in the host-parasite interaction. Further research is required to examine clear disease-associations of var gene subsets in different geographical settings. The importance of very strict clinical definitions and appropriate large control groups needs to be emphasized for future studies on disease associations of PfEMP1.
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Structural basis for the ABO blood-group dependence of Plasmodium falciparum rosetting. PLoS Pathog 2012; 8:e1002781. [PMID: 22807674 PMCID: PMC3395597 DOI: 10.1371/journal.ppat.1002781] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 05/15/2012] [Indexed: 11/29/2022] Open
Abstract
The ABO blood group influences susceptibility to severe Plasmodium falciparum malaria. Recent evidence indicates that the protective effect of group O operates by virtue of reduced rosetting of infected red blood cells (iRBCs) with uninfected RBCs. Rosetting is mediated by a subgroup of PfEMP1 adhesins, with RBC binding being assigned to the N-terminal DBL1α1 domain. Here, we identify the ABO blood group as the main receptor for VarO rosetting, with a marked preference for group A over group B, which in turn is preferred to group O RBCs. We show that recombinant NTS-DBL1α1 and NTS-DBL1α1-CIDR1γ reproduce the VarO-iRBC blood group preference and document direct binding to blood group trisaccharides by surface plasmon resonance. More detailed RBC subgroup analysis showed preferred binding to group A1, weaker binding to groups A2 and B, and least binding to groups Ax and O. The 2.8 Å resolution crystal structure of the PfEMP1-VarO Head region, NTS-DBL1α1-CIDR1γ, reveals extensive contacts between the DBL1α1 and CIDR1γ and shows that the NTS-DBL1α1 hinge region is essential for RBC binding. Computer docking of the blood group trisaccharides and subsequent site-directed mutagenesis localized the RBC-binding site to the face opposite to the heparin-binding site of NTS-DBLα1. RBC binding involves residues that are conserved between rosette-forming PfEMP1 adhesins, opening novel opportunities for intervention against severe malaria. By deciphering the structural basis of blood group preferences in rosetting, we provide a link between ABO blood grouppolymorphisms and rosette-forming adhesins, consistent with the selective role of falciparum malaria on human genetic makeup. Rosetting, the capacity of infected red blood cells (RBCs) to bind uninfected RBCs, is a Plasmodium falciparum virulence factor. Rosetting is influenced by the ABO blood group, being less efficient with O RBCs. Although this preference may account for protection against severe malaria afforded by the O blood group, its understanding is fragmentary. We identify the ABO blood group as the main receptor for the rosetting Palo Alto VarO parasites, which display a marked preference for blood group A. Rosetting is caused by a sub-group of PfEMP1 adhesins. PfEMP1-VarO shares with other rosetting lines a specific NTS-DBL1α1-CIDR1γ Head region. We show that the Head region binds RBCs more efficiently than NTS-DBL1α1 and that ABO blood group polymorphisms influence binding of both domains. The 2.8 Å resolution crystal structure of the Head region reveals extensive contacts between the DBL1α1 and CIDR1γ domains, and shows structural features of the NTS-DBL1α1 hinge region essential for RBC binding. We localize the RBC-binding site to the face opposite to the heparin-binding site of NTS-DBL1α1 and document direct binding of the Head region to A and B trisaccharides These findings provide novel insights into the interactions established by malaria parasites with a prominent human blood group.
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Tetteh-Quarcoo PB, Schmidt CQ, Tham WH, Hauhart R, Mertens HDT, Rowe A, Atkinson JP, Cowman AF, Rowe JA, Barlow PN. Lack of evidence from studies of soluble protein fragments that Knops blood group polymorphisms in complement receptor-type 1 are driven by malaria. PLoS One 2012; 7:e34820. [PMID: 22506052 PMCID: PMC3323580 DOI: 10.1371/journal.pone.0034820] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 03/05/2012] [Indexed: 12/31/2022] Open
Abstract
Complement receptor-type 1 (CR1, CD35) is the immune-adherence receptor, a complement regulator, and an erythroid receptor for Plasmodium falciparum during merozoite invasion and subsequent rosette formation involving parasitized and non-infected erythrocytes. The non-uniform geographical distribution of Knops blood group CR1 alleles Sl1/2 and McCa/b may result from selective pressures exerted by differential exposure to infectious hazards. Here, four variant short recombinant versions of CR1 were produced and analyzed, focusing on complement control protein modules (CCPs) 15–25 of its ectodomain. These eleven modules encompass a region (CCPs 15–17) key to rosetting, opsonin recognition and complement regulation, as well as the Knops blood group polymorphisms in CCPs 24–25. All four CR1 15–25 variants were monomeric and had similar axial ratios. Modules 21 and 22, despite their double-length inter-modular linker, did not lie side-by-side so as to stabilize a bent-back architecture that would facilitate cooperation between key functional modules and Knops blood group antigens. Indeed, the four CR1 15–25 variants had virtually indistinguishable affinities for immobilized complement fragments C3b (KD = 0.8–1.1 µM) and C4b (KD = 5.0–5.3 µM). They were all equally good co-factors for factor I-catalysed cleavage of C3b and C4b, and they bound equally within a narrow affinity range, to immobilized C1q. No differences between the variants were observed in assays for inhibition of erythrocyte invasion by P. falciparum or for rosette disruption. Neither differences in complement-regulatory functionality, nor interactions with P. falciparum proteins tested here, appear to have driven the non-uniform geographic distribution of these alleles.
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Affiliation(s)
| | - Christoph Q. Schmidt
- The Institute of Structural and Molecular Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Wai-Hong Tham
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Richard Hauhart
- Division of Rheumatology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | | | - Arthur Rowe
- School of Biosciences, University of Nottingham, Sutton Bonington, Leicester, United Kingdom
| | - John P. Atkinson
- Division of Rheumatology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Alan F. Cowman
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - J. Alexandra Rowe
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Paul N. Barlow
- The Institute of Structural and Molecular Biology, University of Edinburgh, Edinburgh, United Kingdom
- School of Chemistry, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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Gandhi M. Complement receptor 1 and the molecular pathogenesis of malaria. INDIAN JOURNAL OF HUMAN GENETICS 2011; 13:39-47. [PMID: 21957343 PMCID: PMC3168156 DOI: 10.4103/0971-6866.34704] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Malaria is a pathogenic infection caused by protozoa of the genus plasmodium. It is mainly confined to sub-Saharan Africa, Asia and South America. This disease claims the life of over 1.5 to 2.7 million people per year. Owing to such a high incidence of malarial infections, there is an urgent need for the development of suitable vaccines. For the development of ideal vaccines, it is essential to understand the molecular mechanisms of malarial pathogenesis and the factors that lead to malaria infection. Genetic factors have been proposed to play an important role in malarial pathogenesis. Complement receptor 1 (CR1) is an important host red blood cell protein involved in interaction with malarial parasite. Various polymorphic forms of CR1 have been found to be involved in conferring protection or increasing susceptibility to malaria infections. Low-density allele (L) of CR1 gave contradictory results in different set of studies. In addition, Knops polymorphic forms Sl (a+) and McC (a) have been found to contribute more towards the occurrence of cerebral malaria in malaria endemic regions compared to individuals with Sl (a-) / McC (a/b) genotype. This article reviews the research currently going on in this area and throws light on as yet unresolved mysteries of the role of CR1 in malarial pathogenesis
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Affiliation(s)
- Monika Gandhi
- Guru Gobind Singh Indraprastha University, University School of Biotechnology, Kashmere Gate, Delhi - 110 006, India
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Fontes AM, Kashima S, Bonfim-Silva R, Azevedo R, Abraham KJ, Albuquerque SRL, Bordin JO, Júnior DML, Covas DT. Association between Knops blood group polymorphisms and susceptibility to malaria in an endemic area of the Brazilian Amazon. Genet Mol Biol 2011; 34:539-45. [PMID: 22215954 PMCID: PMC3229105 DOI: 10.1590/s1415-47572011005000051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 07/14/2011] [Indexed: 11/25/2022] Open
Abstract
Complement receptor 1 (CR1) gene polymorphisms that are associated with Knops blood group antigens may influence the binding of Plasmodium parasites to erythrocytes, thereby affecting susceptibility to malaria. The aim of this study was to evaluate the genotype and allele and haplotype frequencies of single-nucleotide polymorphisms (SNPs) of Knops blood group antigens and examine their association with susceptibility to malaria in an endemic area of Brazil. One hundred and twenty-six individuals from the Brazilian Amazon were studied. The CR1-genomic fragment was amplified by PCR and six SNPs and haplotypes were identified after DNA sequence analysis. Allele and haplotype frequencies revealed that the Kn(b) allele and H8 haplotype were possibly associated with susceptibility to Plasmodium falciparum. The odds ratios were reasonably high, suggesting a potentially important association between two Knops blood antigens (Kn(b) and KAM(+)) that confer susceptibility to P. falciparum in individuals from the Brazilian Amazon.
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Affiliation(s)
- Aparecida Maria Fontes
- Hemocentro de Ribeirão Preto, Instituto Nacional de Ciência e Tecnologia em Células Tronco e Terapia Celular, Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
- Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Simone Kashima
- Hemocentro de Ribeirão Preto, Instituto Nacional de Ciência e Tecnologia em Células Tronco e Terapia Celular, Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Ricardo Bonfim-Silva
- Hemocentro de Ribeirão Preto, Instituto Nacional de Ciência e Tecnologia em Células Tronco e Terapia Celular, Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
- Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Rochele Azevedo
- Hemocentro de Ribeirão Preto, Instituto Nacional de Ciência e Tecnologia em Células Tronco e Terapia Celular, Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | | | | | | | | | - Dimas Tadeu Covas
- Hemocentro de Ribeirão Preto, Instituto Nacional de Ciência e Tecnologia em Células Tronco e Terapia Celular, Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
- Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
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Claessens A, Ghumra A, Gupta AP, Mok S, Bozdech Z, Rowe JA. Design of a variant surface antigen-supplemented microarray chip for whole transcriptome analysis of multiple Plasmodium falciparum cytoadherent strains, and identification of strain-transcendent rif and stevor genes. Malar J 2011; 10:180. [PMID: 21718533 PMCID: PMC3155837 DOI: 10.1186/1475-2875-10-180] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 06/30/2011] [Indexed: 12/02/2022] Open
Abstract
Background The cytoadherence of Plasmodium falciparum is thought to be mediated by variant surface antigens (VSA), encoded by var, rif, stevor and pfmc-2tm genes. The last three families have rarely been studied in the context of cytoadherence. As most VSA genes are unique, the variability among sequences has impeded the functional study of VSA across different P. falciparum strains. However, many P. falciparum genomes have recently been sequenced, allowing the development of specific microarray probes for each VSA gene. Methods All VSA sequences from the HB3, Dd2 and IT/FCR3 genomes were extracted using HMMer software. Oligonucleotide probes were designed with OligoRankPick and added to the 3D7-based microarray chip. As a proof of concept, IT/R29 parasites were selected for and against rosette formation and the transcriptomes of isogenic rosetting and non-rosetting parasites were compared by microarray. Results From each parasite strain 50-56 var genes, 125-132 rif genes, 26-33 stevor genes and 3-8 pfmc-2tm genes were identified. Bioinformatic analysis of the new VSA sequences showed that 13 rif genes and five stevor genes were well-conserved across at least three strains (83-100% amino acid identity). The ability of the VSA-supplemented microarray chip to detect cytoadherence-related genes was assessed using P. falciparum clone IT/R29, in which rosetting is known to be mediated by PfEMP1 encoded by ITvar9. Whole transcriptome analysis showed that the most highly up-regulated gene in rosetting parasites was ITvar9 (19 to 429-fold up-regulated over six time points). Only one rif gene (IT4rifA_042) was up-regulated by more than four fold (five fold at 12 hours post-invasion), and no stevor or pfmc-2tm genes were up-regulated by more than two fold. 377 non-VSA genes were differentially expressed by three fold or more in rosetting parasites, although none was as markedly or consistently up-regulated as ITvar9. Conclusions Probes for the VSA of newly sequenced P. falciparum strains can be added to the 3D7-based microarray chip, allowing the analysis of the entire transcriptome of multiple strains. For the rosetting clone IT/R29, the striking transcriptional upregulation of ITvar9 was confirmed, and the data did not support the involvement of other VSA families in rosette formation.
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Affiliation(s)
- Antoine Claessens
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, West Mains Rd, Edinburgh, EH9 3JT, UK
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Plasmodium falciparum uses a key functional site in complement receptor type-1 for invasion of human erythrocytes. Blood 2011; 118:1923-33. [PMID: 21685372 DOI: 10.1182/blood-2011-03-341305] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Plasmodium falciparum adhesin PfRh4 binds to complement receptor type-1 (CR1) on human erythrocytes and mediates a glycophorin-independent invasion pathway. CR1 is a complement regulator and immune-adherence receptor on erythrocytes required for shuttling of C3b/C4b-opsonized particles to liver and spleen for phagocytosis. Using recombinant CR1 constructs, we mapped the recognition site for PfRh4 to complement control protein modules 1 to 3 (CCP1-3) at the membrane-distal amino terminus of CR1. This region of CR1 binds to C4b and C3b and accelerates decay of both classic pathway and alternative pathway C3 and C5 convertases. CCP1-3 competed for PfRh4 binding to erythroid CR1 and inhibited the PfRh4-CR1 invasion pathways across a wide range of P falciparum strains. PfRh4 did not bind significantly to other CR1 constructs, including CCP15-17, which is 85% identical to CCP1-3. PfRh4 binding to CR1 did not affect its C3b/C4b binding capability, and we show evidence for a ternary complex between CCP1-3, C4b, and PfRh4. PfRh4 binding specifically inhibited CR1's convertase decay-accelerating activity, whereas there was no effect on factor H-mediated decay-accelerating activity. These results increase our understanding of the functional implications of CR1 engagement with PfRh4 and highlight the interplay between complement regulation and infection.
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Kosoy R, Ransom M, Chen H, Marconi M, Macciardi F, Glorioso N, Gregersen PK, Cusi D, Seldin MF. Evidence for malaria selection of a CR1 haplotype in Sardinia. Genes Immun 2011; 12:582-8. [PMID: 21593778 DOI: 10.1038/gene.2011.33] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Complement receptor 1 (CR1) levels have been associated with malarial susceptibility and/or severity of the disease in different population groups, and CR1 is a receptor for Plasmodium falciparum. In this study, multiple CR1 single-nucleotide polymorphisms (SNPs) showed strong evidence of population differentiation between Sardinian and other European ethnic groups. Cross population algorithms comparing haplotype structure and differences in haplotype and allele frequency distribution provided additional support for natural selection of CR1 in Sardinia. The predominant Sardinian CR1 haplotype included SNPs that are associated with decreased CR1 levels in Europeans and other population groups. Previous studies have shown that the SNPs within the dominant Sardinian haplotype have a significantly higher frequency in a malaria endemic compared with non-endemic regions in India. Together with the historical evidence of the prevalence of malaria in Sardinia, these data support the role of malaria leading to positive selection of this CR1 haplotype in Sardinia.
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Affiliation(s)
- R Kosoy
- Department of Biochemistry and Molecular Medicine, Rowe Program in Human Genetics, University of California, Davis, CA 95616, USA
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Noumsi GT, Tounkara A, Diallo H, Billingsley K, Moulds JJ, Moulds JM. Knops blood group polymorphism and susceptibility to Mycobacterium tuberculosis infection. Transfusion 2011; 51:2462-9. [PMID: 21569042 DOI: 10.1111/j.1537-2995.2011.03161.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Complement receptor 1 (CR1) protein carries the Knops blood group antigens and is the receptor for the major ligand involved in Mycobacterium tuberculosis (Mtb) adhesion to macrophages. Erythrocyte CR1 binds immune complexes (ICs) formed during Mtb invasion, facilitating their clearance by the host immune system. The occurrence of specific Knops blood group genotypes among African populations was investigated to evaluate their impact on resistance or susceptibility to Mtb infection. STUDY DESIGN AND METHODS The distribution of the Knops blood group genotypes (McC and Sl) was compared between tuberculosis (TB) patients with confirmed diagnosis of Mtb in isolates and negative controls. Conditional logistic regression was used to access the association between genotypes distribution and susceptibility to Mtb infection. RESULTS At the McC locus, individuals heterozygous (McC(a) /McC(b) ) were more resistant to Mtb infection (odds ratio [OR], 0.42; 95% confidence interval [CI], 0.22-0.81; p = 0.007). Although less significant, a similar effect was conferred by Sl1/Sl2 genotype (OR, 0.05; 95% CI, 0.28-0.9; p = 0.02). This protective effect was maintained among individuals presenting the McC(b) /Sl2 haplotype (OR, 0.25; 95% CI, 0.08-0.74; p = 0.008). CONCLUSION Acquisition of McC(b) and Sl2 alleles among African population is correlated with resistance to Mtb infection, adding this bacterium to the list of mechanisms underlying the selection of the Knops blood group polymorphism among these populations.
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Affiliation(s)
- Ghislain T Noumsi
- Scientific Support Services, LifeShare Blood Centers, Shreveport, Louisiana 71106, USA.
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35
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Ochola LB, Siddondo BR, Ocholla H, Nkya S, Kimani EN, Williams TN, Makale JO, Liljander A, Urban BC, Bull PC, Szestak T, Marsh K, Craig AG. Specific receptor usage in Plasmodium falciparum cytoadherence is associated with disease outcome. PLoS One 2011; 6:e14741. [PMID: 21390226 PMCID: PMC3048392 DOI: 10.1371/journal.pone.0014741] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 01/07/2011] [Indexed: 12/22/2022] Open
Abstract
Our understanding of the basis of severe disease in malaria is incomplete. It is clear that pathology is in part related to the pro-inflammatory nature of the host response but a number of other factors are also thought to be involved, including the interaction between infected erythrocytes and endothelium. This is a complex system involving several host receptors and a major parasite-derived variant antigen (PfEMP1) expressed on the surface of the infected erythrocyte membrane. Previous studies have suggested a role for ICAM-1 in the pathology of cerebral malaria, although these have been inconclusive. In this study we have examined the cytoadherence patterns of 101 patient isolates from varying clinical syndromes to CD36 and ICAM-1, and have used variant ICAM-1 proteins to further characterise this adhesive phenotype. Our results show that increased binding to CD36 is associated with uncomplicated malaria while ICAM-1 adhesion is raised in parasites from cerebral malaria cases.
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Affiliation(s)
- Lucy B Ochola
- KEMRI/Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya.
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Ghumra A, Khunrae P, Ataide R, Raza A, Rogerson SJ, Higgins MK, Rowe JA. Immunisation with recombinant PfEMP1 domains elicits functional rosette-inhibiting and phagocytosis-inducing antibodies to Plasmodium falciparum. PLoS One 2011; 6:e16414. [PMID: 21305024 PMCID: PMC3031562 DOI: 10.1371/journal.pone.0016414] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Accepted: 12/14/2010] [Indexed: 11/24/2022] Open
Abstract
Background Rosetting is a Plasmodium falciparum virulence factor implicated in the pathogenesis of life-threatening malaria. Rosetting occurs when parasite–derived P. falciparum Erythrocyte Membrane Protein One (PfEMP1) on the surface of infected erythrocytes binds to human receptors on uninfected erythrocytes. PfEMP1 is a possible target for a vaccine to induce antibodies to inhibit rosetting and prevent severe malaria. Methodology/Findings We examined the vaccine potential of the six extracellular domains of a rosette-mediating PfEMP1 variant (ITvar9/R29var1 from the R29 parasite strain) by immunizing rabbits with recombinant proteins expressed in E. coli. Antibodies raised to each domain were tested for surface fluorescence with live infected erythrocytes, rosette inhibition and phagocytosis-induction. Antibodies to all PfEMP1 domains recognized the surface of live infected erythrocytes down to low concentrations (0.02–1.56 µg/ml of total IgG). Antibodies to all PfEMP1 domains except for the second Duffy-Binding-Like region inhibited rosetting (50% inhibitory concentration 0.04–4 µg/ml) and were able to opsonize and induce phagocytosis of infected erythrocytes at low concentrations (1.56–6.25 µg/ml). Antibodies to the N-terminal region (NTS-DBL1α) were the most effective in all assays. All antibodies were specific for the R29 parasite strain, and showed no functional activity against five other rosetting strains. Conclusions/Significance These results are encouraging for vaccine development as they show that potent antibodies can be generated to recombinant PfEMP1 domains that will inhibit rosetting and induce phagocytosis of infected erythrocytes. However, further work is needed on rosetting mechanisms and cross-reactivity in field isolates to define a set of PfEMP1 variants that could induce functional antibodies against a broad range of P. falciparum rosetting parasites.
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Affiliation(s)
- Ashfaq Ghumra
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Pongsak Khunrae
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Ricardo Ataide
- Department of Medicine, University of Melbourne, Post Office Royal Melbourne Hospital, Melbourne, Australia
- Graduate Program in Areas of Basic and Applied Biology, Universidade do Porto, Porto, Portugal
| | - Ahmed Raza
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Stephen J. Rogerson
- Department of Medicine, University of Melbourne, Post Office Royal Melbourne Hospital, Melbourne, Australia
| | - Matthew K. Higgins
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - J. Alexandra Rowe
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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Complement receptor 1 is the host erythrocyte receptor for Plasmodium falciparum PfRh4 invasion ligand. Proc Natl Acad Sci U S A 2010; 107:17327-32. [PMID: 20855594 DOI: 10.1073/pnas.1008151107] [Citation(s) in RCA: 161] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Plasmodium falciparum is responsible for the most severe form of malaria disease in humans, causing more than 1 million deaths each year. As an obligate intracellular parasite, P. falciparum's ability to invade erythrocytes is essential for its survival within the human host. P. falciparum invades erythrocytes using multiple host receptor-parasite ligand interactions known as invasion pathways. Here we show that CR1 is the host erythrocyte receptor for PfRh4, a major P. falciparum ligand essential for sialic acid-independent invasion. PfRh4 and CR1 interact directly, with a K(d) of 2.9 μM. PfRh4 binding is strongly correlated with the CR1 level on the erythrocyte surface. Parasite invasion via sialic acid-independent pathways is reduced in low-CR1 erythrocytes due to limited availability of this receptor on the surface. Furthermore, soluble CR1 can competitively block binding of PfRh4 to the erythrocyte surface and specifically inhibit sialic acid-independent parasite invasion. These results demonstrate that CR1 is an erythrocyte receptor used by the parasite ligand PfRh4 for P. falciparum invasion.
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Spadafora C, Awandare GA, Kopydlowski KM, Czege J, Moch JK, Finberg RW, Tsokos GC, Stoute JA. Complement receptor 1 is a sialic acid-independent erythrocyte receptor of Plasmodium falciparum. PLoS Pathog 2010; 6:e1000968. [PMID: 20585558 PMCID: PMC2887475 DOI: 10.1371/journal.ppat.1000968] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 05/26/2010] [Indexed: 11/18/2022] Open
Abstract
Plasmodium falciparum is a highly lethal malaria parasite of humans. A major portion of its life cycle is dedicated to invading and multiplying inside erythrocytes. The molecular mechanisms of erythrocyte invasion are incompletely understood. P. falciparum depends heavily on sialic acid present on glycophorins to invade erythrocytes. However, a significant proportion of laboratory and field isolates are also able to invade erythrocytes in a sialic acid-independent manner. The identity of the erythrocyte sialic acid-independent receptor has been a mystery for decades. We report here that the complement receptor 1 (CR1) is a sialic acid-independent receptor for the invasion of erythrocytes by P. falciparum. We show that soluble CR1 (sCR1) as well as polyclonal and monoclonal antibodies against CR1 inhibit sialic acid-independent invasion in a variety of laboratory strains and wild isolates, and that merozoites interact directly with CR1 on the erythrocyte surface and with sCR1-coated microspheres. Also, the invasion of neuraminidase-treated erythrocytes correlates with the level of CR1 expression. Finally, both sialic acid-independent and dependent strains invade CR1 transgenic mouse erythrocytes preferentially over wild-type erythrocytes but invasion by the latter is more sensitive to neuraminidase. These results suggest that both sialic acid-dependent and independent strains interact with CR1 in the normal red cell during the invasion process. However, only sialic acid-independent strains can do so without the presence of glycophorin sialic acid. Our results close a longstanding and important gap in the understanding of the mechanism of erythrocyte invasion by P. falciparum that will eventually make possible the development of an effective blood stage vaccine. Plasmodium falciparum malaria is a blood parasite that lives for the most part inside red cells. It is responsible for the death of 1-2 million people every year. The mechanisms by which the parasite invades red cells are complex and not completely understood. For many years it has been known that proteins called glycophorins are used by the parasite to gain entry into the red cell. However, the existence of another protein that allows entry independent of glycophorins has been suspected for nearly as long. The identity of the alternative protein has been a mystery difficult to solve. In this article we present strong evidence that the alternative protein is the complement receptor 1. The complement receptor 1 is a well-studied protein that is known to be important in protecting red cells from attack by the host immune system as well as suspected of having other roles in the development of malaria complications. The recognition of the additional role of complement receptor 1 in red cell invasion will allow the definitive identification of malaria proteins that interact with it and that could be used in a future vaccine cocktail to block red cell invasion.
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Affiliation(s)
- Carmenza Spadafora
- Department of Medicine, the Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
- Department of Cellular Injury, Division of Military Casualty Research, the Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Instituto de Investigaciones Científicas y Servicios de Alta Tecnología-AIP (INDICASAT-AIP), Ciudad del Saber, Clayton, Panamá
| | - Gordon A. Awandare
- Division of Malaria Vaccine Development, the Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Karen M. Kopydlowski
- Department of Parasitology, Division of Experimental Therapeutics, the Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Jozsef Czege
- Biomedical Instrumentation Center, the Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - J. Kathleen Moch
- Department of Parasitology, Division of Experimental Therapeutics, the Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Robert W. Finberg
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - George C. Tsokos
- Department of Medicine, the Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
- Department of Cellular Injury, Division of Military Casualty Research, the Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - José A. Stoute
- Department of Medicine, the Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
- Department of Cellular Injury, Division of Military Casualty Research, the Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Department of Medicine, Division of Infectious Diseases and Epidemiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
- * E-mail:
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Eid NA, Hussein AA, Elzein AM, Mohamed HS, Rockett KA, Kwiatkowski DP, Ibrahim ME. Candidate malaria susceptibility/protective SNPs in hospital and population-based studies: the effect of sub-structuring. Malar J 2010; 9:119. [PMID: 20459687 PMCID: PMC2877684 DOI: 10.1186/1475-2875-9-119] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 05/08/2010] [Indexed: 11/10/2022] Open
Abstract
Background Populations of East Africa including Sudan, exhibit some of the highest indices of genetic diversity in the continent and worldwide. The current study aims to address the possible impact of population structure and population stratification on the outcome of case-control association-analysis of malaria candidate-genes in different Sudanese populations, where the pronounced genetic heterogeneity becomes a source of concern for the potential effect on the studies outcome. Methods A total of 72 SNPs were genotyped using the Sequenom® iPLEX Gold assay in 449 DNA samples that included; cases and controls from two village populations, malaria patients and out-patients from the area of Sinnar and additional controls consisting of healthy Nilo-Saharan speaking individuals. The population substructure was estimated using the Structure 2.2 programme. Results & Discussion The Hardy-Weinberg Equilibrium values were generally within expectation in Hausa and Massalit. However, in the Sinnar area there was a notable excess of homozygosity, which was attributed to the Whalund effect arising from population amalgamation within the sample. The programme STRUCTURE revealed a division of both Hausa and Massalit into two substructures with the partition in Hausa more pronounced than in Massalit; In Sinnar there was no defined substructure. More than 25 of the 72 SNPs assayed were informative in all areas. Some important SNPs were not differentially distributed between malaria cases and controls, including SNPs in CD36 and NOS2. A number of SNPs showed significant p-values for differences in distribution of genotypes between cases and controls including: rs1805015 (in IL4R1) (P = 0.001), rs17047661 (in CR1) (P = 0.02) and rs1800750 (TNF-376)(P = 0.01) in the hospital samples; rs1050828 (G6PD+202) (P = 0.02) and rs1800896 (IL10-1082) (P = 0.04) in Massalit and rs2243250 (IL4-589) (P = 0.04) in Hausa. Conclusions The difference in population structure partly accounts for some of these significant associations, and the strength of association proved to be sensitive to all levels of sub-structuring whether in the hospital or population-based study.
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Affiliation(s)
- Nahid A Eid
- Department of Molecular Biology, Institute of Endemic Diseases, Medical Campus, Qasser Street, University of Khartoum, Khartoum, Sudan
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Blood groups and malaria: fresh insights into pathogenesis and identification of targets for intervention. Curr Opin Hematol 2010; 16:480-7. [PMID: 19812491 DOI: 10.1097/moh.0b013e3283313de0] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW This review summarizes recent advances in our understanding of the interaction between malaria parasites and blood group antigens and discusses how the knowledge gleaned can be used to target the development of new antimalarial treatments and vaccines. RECENT FINDINGS Studies of the interaction between Plasmodium vivax and the Duffy antigen provide the clearest example of the potential for basic research on blood groups and malaria to be translated into a vaccine that could have a major impact on global health. Progress is also being made in understanding the effects of other blood group antigens on malaria. After years of controversy, the effect of ABO blood groups on falciparum malaria has been clarified, with the non-O blood groups emerging as significant risk factors for life-threatening malaria, through the mechanism of enhanced rosette formation. The Knops blood group system may also influence malaria susceptibility, although conflicting results from different countries mean that further research is required. Unanswered questions remain about the interactions between malaria parasites and other blood group antigens, including the Gerbich, MNS and Rhesus systems. SUMMARY The interplay between malaria parasites and blood group antigens remains a fascinating subject with potential to contribute to the development of new interventions to reduce the global burden of malaria.
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Juillerat A, Igonet S, Vigan-Womas I, Guillotte M, Gangnard S, Faure G, Baron B, Raynal B, Mercereau-Puijalon O, Bentley GA. Biochemical and biophysical characterisation of DBL1alpha1-varO, the rosetting domain of PfEMP1 from the VarO line of Plasmodium falciparum. Mol Biochem Parasitol 2010; 170:84-92. [PMID: 20045435 DOI: 10.1016/j.molbiopara.2009.12.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 12/15/2009] [Accepted: 12/22/2009] [Indexed: 10/20/2022]
Abstract
Rosetting of erythrocytes infected with Plasmodium falciparum is frequently observed in children with severe malaria. This adhesion phenomenon has been linked to the DBL1alpha domain of P. falciparum erythrocyte membrane protein 1 (PfEMP1) in three laboratory clones: FCR3S1.2, IT4R29 and Palo Alto varO. Here, we compare the soluble recombinant NTS-DBL1alpha(1)-varO domain (NTS: N-terminal segment) obtained from E. coli, Pichia pastoris and baculovirus/insect cell expression systems. In each case, the presence of NTS was necessary for obtaining a soluble product. Successful expression in E. coli required maltose-binding protein as an N-terminal fusion partner. Each expression system produced an identical, correctly folded protein, as judged by biochemical and biophysical characterisations, and by the capacity to elicit antibodies that react with the surface of VarO-infected erythrocytes and disrupt VarO rosettes. Binding studies using surface plasmon resonance (SPR) techniques showed that NTS-DBL1alpha(1) produced in E. coli binds to heparin with micromolar affinity. IC(50) constants for other sulphated oligosaccharides were determined using SPR by measuring their competitive binding to the soluble protein in the presence of immobilized heparin. The affinity to NTS-DBL1alpha(1) was related to the degree of sulphation of the oligosaccharide, although the position of the sulphate groups on the sugar rings was also important. VarO rosettes could be disrupted by sulphated oligosaccharides with an efficacy that correlated with their binding affinity to recombinant NTS-DBL1alpha(1). Thus high yields of soluble NTS-DBL1alpha(1) with native conformation have been produced, opening novel perspectives for both structure-function studies and vaccine development.
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Affiliation(s)
- Alexandre Juillerat
- Unité d'Immunologie Structurale, CNRS URA 2185, Institut Pasteur, 25-28 rue du Dr. Roux, F-75015 Paris, France
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Adhesion of Plasmodium falciparum-infected erythrocytes to human cells: molecular mechanisms and therapeutic implications. Expert Rev Mol Med 2009; 11:e16. [PMID: 19467172 PMCID: PMC2878476 DOI: 10.1017/s1462399409001082] [Citation(s) in RCA: 249] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Severe malaria has a high mortality rate (15–20%) despite treatment with
effective antimalarial drugs. Adjunctive therapies for severe malaria that target the
underlying disease process are therefore urgently required. Adhesion of erythrocytes
infected with Plasmodium falciparum to human cells has a key role in the
pathogenesis of life-threatening malaria and could be targeted with antiadhesion therapy.
Parasite adhesion interactions include binding to endothelial cells (cytoadherence),
rosetting with uninfected erythrocytes and platelet-mediated clumping of infected
erythrocytes. Recent research has started to define the molecular mechanisms of parasite
adhesion, and antiadhesion therapies are being explored. However, many fundamental
questions regarding the role of parasite adhesion in severe malaria remain unanswered.
There is strong evidence that rosetting contributes to severe malaria in sub-Saharan
Africa; however, the identity of other parasite adhesion phenotypes that are implicated in
disease pathogenesis remains unclear. In addition, the possibility of geographic variation
in adhesion phenotypes causing severe malaria, linked to differences in malaria
transmission levels and host immunity, has been neglected. Further research is needed to
realise the untapped potential of antiadhesion adjunctive therapies, which could
revolutionise the treatment of severe malaria and reduce the high mortality rate of the
disease.
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Sinha S, Jha GN, Anand P, Qidwai T, Pati SS, Mohanty S, Mishra SK, Tyagi PK, Sharma SK, Venkatesh V, Habib S. CR1 levels and gene polymorphisms exhibit differential association with falciparum malaria in regions of varying disease endemicity. Hum Immunol 2009; 70:244-50. [DOI: 10.1016/j.humimm.2009.02.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 01/13/2009] [Accepted: 02/04/2009] [Indexed: 02/07/2023]
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Teeranaipong P, Ohashi J, Patarapotikul J, Kimura R, Nuchnoi P, Hananantachai H, Naka I, Putaporntip C, Jongwutiwes S, Tokunaga K. A functional single-nucleotide polymorphism in the CR1 promoter region contributes to protection against cerebral malaria. J Infect Dis 2009; 198:1880-91. [PMID: 18954261 DOI: 10.1086/593338] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Although the level of erythrocyte complement receptor type 1 (E-CR1) expression in patients with malaria has been extensively studied, whether the level of expression of E-CR1 is associated with severe malaria remains controversial. The present study examined a possible association of polymorphisms in the CR1 gene with the severity of malaria, and it evaluated the influence of the associated polymorphism on expression of E-CR1. METHODS Seventeen single-nucleotide polymorphisms in CR1 were genotyped in 477 Thai patients who had Plasmodium falciparum malaria (203 had mild malaria, 165 had noncerebral severe malaria, and 109 had cerebral malaria). The E-CR1 expression level was measured by flow cytometry in 24 healthy Thai subjects. RESULTS The T allele of the reference single-nucleotide polymorphism rs9429942 in the CR1 promoter region was strongly associated with protection against cerebral malaria (2.2% of patients with mild malaria vs. 7.8% of patients with cerebral malaria; P = .0009; Bonferroni-adjusted Pc = .0306. The E-CR1 expression level was significantly higher in individuals with the TT genotype of rs9429942 than in individuals with the TC genotype of rs9429942 (P = .0282). CONCLUSIONS We identified a CR1 promoter allele, associated with higher E-CR1 expression, that conferred protection against cerebral malaria. Previous studies have shown that the rate of clearance of immune complexes (ICs) from the circulation is related to the E-CR1 level. These results lead to the hypothesis that the clearance of ICs regulated by E-CR1 therefore plays a crucial role in the pathogenesis of cerebral malaria.
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Affiliation(s)
- Phairote Teeranaipong
- Department of Human Genetics, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
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Khera R, Das N. Complement Receptor 1: disease associations and therapeutic implications. Mol Immunol 2008; 46:761-72. [PMID: 19004497 PMCID: PMC7125513 DOI: 10.1016/j.molimm.2008.09.026] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Revised: 09/15/2008] [Accepted: 09/15/2008] [Indexed: 11/17/2022]
Abstract
Exaggerated complement activation is a key event in the pathogenesis of a range of autoimmune and inflammatory diseases. Complement Receptor 1 (CR1) has emerged as a molecule of immense interest in gaining insight to the susceptibility, pathophysiology, diagnosis, prognosis and therapy of such diseases. This review brings forth a composite view of the current understanding on the structure, functions, genetics, disease associations and therapeutic implications of CR1.
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Affiliation(s)
- Rohan Khera
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India
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An in vivo and in vitro model of Plasmodium falciparum rosetting and autoagglutination mediated by varO, a group A var gene encoding a frequent serotype. Infect Immun 2008; 76:5565-80. [PMID: 18809668 DOI: 10.1128/iai.00901-08] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the Saimiri sciureus monkey, erythrocytes infected with the varO antigenic variant of the Plasmodium falciparum Palo Alto 89F5 clone bind uninfected red blood cells (rosetting), form autoagglutinates, and have a high multiplication rate, three phenotypic characteristics that are associated with severe malaria in human patients. We report here that varO parasites express a var gene having the characteristics of group A var genes, and we show that the varO Duffy binding-like 1alpha(1) (DBL1alpha(1)) domain is implicated in the rosetting of both S. sciureus and human erythrocytes. The soluble varO N-terminal sequence (NTS)-DBL1alpha(1) recombinant domain, produced in a baculovirus-insect cell system, induced high titers of antibodies that reacted with varO-infected red blood cells and disrupted varO rosettes. varO parasites were culture adapted in vitro using human erythrocytes. They formed rosettes and autoagglutinates, and they had the same surface serotype and expressed the same varO gene as the monkey-propagated parasites. To develop an in vitro model with highly homogeneous varO parasites, rosette purification was combined with positive selection by panning with a varO NTS-DBL1alpha(1)-specific mouse monoclonal antibody. The single-variant, clonal parasites were used to analyze seroprevalence for varO at the village level in a setting where malaria is holoendemic (Dielmo, Senegal). We found 93.6% (95% confidence interval, 89.7 to 96.4%) seroprevalence for varO surface-reacting antibodies and 86.7% (95% confidence interval, 82.8 to 91.6%) seroprevalence for the recombinant NTS-DBL1alpha(1) domain, and virtually all permanent residents had seroconverted by the age of 5 years. These data imply that the varO model is a relevant in vivo and in vitro model for rosetting and autoagglutination that can be used for rational development of vaccine candidates and therapeutic strategies aimed at preventing malaria pathology.
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Ghumra A, Semblat JP, McIntosh RS, Raza A, Rasmussen IB, Braathen R, Johansen FE, Sandlie I, Mongini PK, Rowe JA, Pleass RJ. Identification of residues in the Cmu4 domain of polymeric IgM essential for interaction with Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). THE JOURNAL OF IMMUNOLOGY 2008; 181:1988-2000. [PMID: 18641336 DOI: 10.4049/jimmunol.181.3.1988] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The binding of nonspecific human IgM to the surface of infected erythrocytes is important in rosetting, a major virulence factor in the pathogenesis of severe malaria due to Plasmodium falciparum, and IgM binding has also been implicated in placental malaria. Herein we have identified the IgM-binding parasite ligand from a virulent P. falciparum strain as PfEMP1 (TM284var1 variant), and localized the region within this PfEMP1 variant that binds IgM (DBL4beta domain). We have used this parasite IgM-binding protein to investigate the interaction with human IgM. Interaction studies with domain-swapped Abs, IgM mutants, and anti-IgM mAbs showed that PfEMP1 binds to the Fc portion of the human IgM H chain and requires the IgM Cmu4 domain. Polymerization of IgM was shown to be crucial for the interaction because PfEMP1 binding did not occur with mutant monomeric IgM molecules. These results with PfEMP1 protein have physiological relevance because infected erythrocytes from strain TM284 and four other IgM-binding P. falciparum strains showed analogous results to those seen with the DBL4beta domain. Detailed investigation of the PfEMP1 binding site on IgM showed that some of the critical amino acids in the IgM Cmu4 domain are equivalent to those regions of IgG and IgA recognized by Fc-binding proteins from bacteria, suggesting that this region of Ig molecules may be of major functional significance in host-microbe interactions. We have therefore shown that PfEMP1 is an Fc-binding protein of malaria parasites specific for polymeric human IgM, and that it shows functional similarities with Fc-binding proteins from pathogenic bacteria.
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Affiliation(s)
- Ashfaq Ghumra
- Institute of Genetics, Queens Medical Centre, University of Nottingham, Nottingham, England, United Kingdom
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Rosetting in Plasmodium falciparum: a cytoadherence phenotype with multiple actors. Transfus Clin Biol 2008; 15:62-71. [PMID: 18514562 DOI: 10.1016/j.tracli.2008.04.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Accepted: 04/08/2008] [Indexed: 11/22/2022]
Abstract
The capacity of Plasmodium falciparum-infected red blood cells to bind uninfected red blood cells ("rosetting") has been associated with high parasite density in numerous geographic areas and with severe malaria in African children. We summarize here the associations that have emerged from field studies and describe the various experimental models of rosetting that have been developed. A variety of erythrocyte receptors, several serum factors and a number of rosette-mediating PfEMP1 adhesins have been identified. Several var genes code for rosette-forming PfEMP1 adhesins in each P. falciparum genome, so that each clonal line has the capacity to generate distinct types of rosettes. To clarify their respective role in malaria pathogenesis, each of the multiple ligand/receptor interactions should be further studied for fine specificity, binding affinity and the impact of the large population polymorphism of the parasite variant repertoires should be assessed. Interestingly, some major human erythrocyte surface polymorphisms have been identified as affecting rosette formation, consistent with a role for rosetting in life-threatening falciparum malaria.
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Hot, sweet and sticky: the glycobiology of Plasmodium falciparum. Trends Parasitol 2008; 24:210-8. [DOI: 10.1016/j.pt.2008.02.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Revised: 02/02/2008] [Accepted: 02/05/2008] [Indexed: 11/22/2022]
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Normark J, Nilsson D, Ribacke U, Winter G, Moll K, Wheelock CE, Bayarugaba J, Kironde F, Egwang TG, Chen Q, Andersson B, Wahlgren M. PfEMP1-DBL1alpha amino acid motifs in severe disease states of Plasmodium falciparum malaria. Proc Natl Acad Sci U S A 2007; 104:15835-40. [PMID: 17895392 PMCID: PMC1994139 DOI: 10.1073/pnas.0610485104] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2006] [Indexed: 11/18/2022] Open
Abstract
An infection with Plasmodium falciparum may lead to severe malaria as a result of excessive binding of infected erythrocytes in the microvasculature. Vascular adhesion is mediated by P. falciparum erythrocyte membrane protein-1 (PfEMP1), which is encoded for by highly polymorphic members of the var-gene family. Here, we profile var gene transcription in fresh P. falciparum trophozoites from Ugandan children with malaria through var-specific DBL1alpha-PCR amplification and sequencing. A method for subsectioning region alignments into homology areas (MOTIFF) was developed to examine collected sequences. Specific PfEMP1-DBL1alpha amino acid motifs correlated with rosetting and severe malaria, with motif location corresponding to distinct regions of receptor interaction. The method is potentially applicable to other families of variant proteins and may be useful in identifying sequence-phenotype relationships. The results suggest that certain PfEMP1 sequences are predisposed to inducing severe malaria.
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Affiliation(s)
- Johan Normark
- Department of Microbiology and Tumor and Cell Biology (MTC), Karolinska Institutet and
- Swedish Institute for Infectious Diseases Control (SMI), Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
| | - Daniel Nilsson
- Department of Microbiology and Tumor and Cell Biology (MTC), Karolinska Institutet and
- Swedish Institute for Infectious Diseases Control (SMI), Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
- Programme for Genomics and Bioinformatics, Department of Cell and Molecular Biology, Karolinska Institutet, Berzeliusväg 35, SE-17177 Stockholm, Sweden
| | - Ulf Ribacke
- Department of Microbiology and Tumor and Cell Biology (MTC), Karolinska Institutet and
- Swedish Institute for Infectious Diseases Control (SMI), Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
| | - Gerhard Winter
- Department of Microbiology and Tumor and Cell Biology (MTC), Karolinska Institutet and
- Swedish Institute for Infectious Diseases Control (SMI), Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
| | - Kirsten Moll
- Department of Microbiology and Tumor and Cell Biology (MTC), Karolinska Institutet and
- Swedish Institute for Infectious Diseases Control (SMI), Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
| | - Craig E. Wheelock
- Department of Microbiology and Tumor and Cell Biology (MTC), Karolinska Institutet and
- Swedish Institute for Infectious Diseases Control (SMI), Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
| | - Justus Bayarugaba
- Departments of Paediatrics and
- Biochemistry, Mulago Hospital, Kampala, Uganda
| | - Fred Kironde
- University of Makerere, Box 7072, Kampala, Uganda; and
| | - Thomas G. Egwang
- Medical Biotech Laboratories, Ssekindi Close, Tank Hill Bypass, Box 9364, Kampala, Uganda
| | - Qijun Chen
- Department of Microbiology and Tumor and Cell Biology (MTC), Karolinska Institutet and
- Swedish Institute for Infectious Diseases Control (SMI), Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
| | - Björn Andersson
- Programme for Genomics and Bioinformatics, Department of Cell and Molecular Biology, Karolinska Institutet, Berzeliusväg 35, SE-17177 Stockholm, Sweden
| | - Mats Wahlgren
- Department of Microbiology and Tumor and Cell Biology (MTC), Karolinska Institutet and
- Swedish Institute for Infectious Diseases Control (SMI), Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
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