351
|
Abstract
Almost 20 years after the development of models of malaria pathogenesis began, we are beyond the 'proof-of-concept' phase and these models are no longer abstract mathematical exercises. They have refined our knowledge of within-host processes, and have brought insights that could not easily have been obtained from experimentation alone. There is much potential that remains to be realized, however, both in terms of informing the design of interventions and health policy, and in terms of addressing lingering questions about the basic biology of malaria. Recent research has begun to iterate theory and data in a much more comprehensive way, and the use of statistical techniques for model fitting and comparison offers a promising approach for providing a quantitative understanding of the pathogenesis of such a complex disease.
Collapse
Affiliation(s)
- Nicole Mideo
- Department of Biology, Queen's University, Kingston, ON, Canada.
| | | | | |
Collapse
|
352
|
Langhorne J, Ndungu FM, Sponaas AM, Marsh K. Immunity to malaria: more questions than answers. Nat Immunol 2008; 9:725-32. [PMID: 18563083 DOI: 10.1038/ni.f.205] [Citation(s) in RCA: 621] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Malaria is one of the main health problems facing developing countries today. At present, preventative and treatment strategies are continuously hampered by the issues of the ever-emerging parasite resistance to newly introduced drugs, considerable costs and logistical problems. The main hope for changing this situation would be the development of effective malaria vaccines. An important part of this process is understanding the mechanisms of naturally acquired immunity to malaria. This review will highlight key aspects of immunity to malaria, about which surprisingly little is known and which will prove critical in the search for effective malaria vaccines.
Collapse
Affiliation(s)
- Jean Langhorne
- Division of Parasitology, National Institute for Medical Research, London NW7 1AA, UK.
| | | | | | | |
Collapse
|
353
|
Togbe D, Loureiro de Sousa P, Fauconnier M, Boissay V, Fick L, Scheu S, Pfeffer K, Menard R, Grau GE, Doan BT, Beloeil JC, Renia L, Hansen AM, Ball HJ, Hunt NH, Ryffel B, Quesniaux VFJ. Both functional LTbeta receptor and TNF receptor 2 are required for the development of experimental cerebral malaria. PLoS One 2008; 3:e2608. [PMID: 18612394 PMCID: PMC2442868 DOI: 10.1371/journal.pone.0002608] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Accepted: 06/04/2008] [Indexed: 12/19/2022] Open
Abstract
Background TNF-related lymphotoxin α (LTα) is essential for the development of Plasmodium berghei ANKA (PbA)-induced experimental cerebral malaria (ECM). The pathway involved has been attributed to TNFR2. Here we show a second arm of LTα-signaling essential for ECM development through LTβ-R, receptor of LTα1β2 heterotrimer. Methodology/Principal Findings LTβR deficient mice did not develop the neurological signs seen in PbA induced ECM but died at three weeks with high parasitaemia and severe anemia like LTαβ deficient mice. Resistance of LTαβ or LTβR deficient mice correlated with unaltered cerebral microcirculation and absence of ischemia, as documented by magnetic resonance imaging and angiography, associated with lack of microvascular obstruction, while wild-type mice developed distinct microvascular pathology. Recruitment and activation of perforin+ CD8+ T cells, and their ICAM-1 expression were clearly attenuated in the brain of resistant mice. An essential contribution of LIGHT, another LTβR ligand, could be excluded, as LIGHT deficient mice rapidly succumbed to ECM. Conclusions/Significance LTβR expressed on radioresistant resident stromal, probably endothelial cells, rather than hematopoietic cells, are essential for the development of ECM, as assessed by hematopoietic reconstitution experiment. Therefore, the data suggest that both functional LTβR and TNFR2 signaling are required and non-redundant for the development of microvascular pathology resulting in fatal ECM.
Collapse
Affiliation(s)
- Dieudonnée Togbe
- University of Orléans and CNRS, Molecular Immunology and Embryology UMR6218, Orleans, France
| | | | - Mathilde Fauconnier
- University of Orléans and CNRS, Molecular Immunology and Embryology UMR6218, Orleans, France
| | - Victorine Boissay
- University of Orléans and CNRS, Molecular Immunology and Embryology UMR6218, Orleans, France
| | - Lizette Fick
- Institute of Infectious Disease and Molecular Medicine, Cape Town, South Africa
| | | | | | | | - Georges E. Grau
- The University of Sydney, Department of Pathology, Camperdown, Australia
| | - Bich-Thuy Doan
- CNRS CBM (Centre de Biophysique Moléculaire), Orleans, France
| | | | - Laurent Renia
- The University of Sydney, Department of Pathology, Camperdown, Australia
- Inserm, U567, Paris, France
| | - Anna M. Hansen
- The University of Sydney, Department of Pathology, Camperdown, Australia
| | - Helen J. Ball
- The University of Sydney, Department of Pathology, Camperdown, Australia
| | - Nicholas H. Hunt
- The University of Sydney, Department of Pathology, Camperdown, Australia
| | - Bernhard Ryffel
- University of Orléans and CNRS, Molecular Immunology and Embryology UMR6218, Orleans, France
- * E-mail: (BR); (VQ)
| | - Valerie F. J. Quesniaux
- University of Orléans and CNRS, Molecular Immunology and Embryology UMR6218, Orleans, France
- * E-mail: (BR); (VQ)
| |
Collapse
|
354
|
Mwangoka GW, Kimera SI, Mboera LEG. Congenital Plasmodium falciparum infection in neonates in Muheza District, Tanzania. Malar J 2008; 7:117. [PMID: 18598342 PMCID: PMC2474641 DOI: 10.1186/1475-2875-7-117] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Accepted: 07/03/2008] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Although recent reports on congenital malaria suggest that the incidence is increasing, it is difficult to determine whether the clinical disease is due to parasites acquired before delivery or as a result of contamination by maternal blood at birth. Understanding of the method of parasite acquisition is important for estimating the time incidence of congenital malaria and design of preventive measures. The aim of this study was to determine whether the first Plasmodium falciparum malaria disease in infants is due to same parasites present on the placenta at birth. METHODS Babies born to mothers with P. falciparum parasites on the placenta detected by PCR were followed up to two years and observed for malaria episodes. Paired placental and infant peripheral blood samples at first malaria episode within first three months of life were genotyped (msp2) to determine genetic relatedness. Selected amplifications from nested PCR were sequenced and compared between pairs. RESULTS Eighteen (19.1%) out of 95 infants who were followed up developed clinical malaria within the first three months of age. Eight pairs (60%) out of 14 pairs of sequenced placental and cord samples were genetically related while six (40%) were genetically unrelated. One pair (14.3%) out of seven pairs of sequenced placental and infants samples were genetically related. In addition, infants born from primigravidae mothers were more likely to be infected with P. falciparum (P < 0.001) as compared to infants from secundigravidae and multigravidae mothers during the two years of follow up. Infants from multigravidae mothers got the first P. falciparum infection earlier than those from secundigravidae and primigravidae mothers (RR = 1.43). CONCLUSION Plasmodium falciparum malaria parasites present on the placenta as detected by PCR are more likely to result in clinical disease (congenital malaria) in the infant during the first three months of life. However, sequencing data seem to question the validity of this likelihood. Therefore, the relationship between placental parasites and first clinical disease need to be confirmed in larger studies.
Collapse
MESH Headings
- Adolescent
- Adult
- Animals
- Antigens, Protozoan/genetics
- Female
- Fetal Blood/parasitology
- Humans
- Infant, Newborn
- Infant, Premature
- Infant, Premature, Diseases/epidemiology
- Infant, Premature, Diseases/parasitology
- Infectious Disease Transmission, Vertical
- Malaria, Falciparum/congenital
- Malaria, Falciparum/epidemiology
- Malaria, Falciparum/parasitology
- Malaria, Falciparum/transmission
- Middle Aged
- Parasitemia/congenital
- Parasitemia/epidemiology
- Parasitemia/parasitology
- Parasitemia/transmission
- Placenta/parasitology
- Plasmodium falciparum/classification
- Plasmodium falciparum/genetics
- Plasmodium falciparum/isolation & purification
- Polymerase Chain Reaction
- Pregnancy
- Pregnancy Complications, Parasitic/epidemiology
- Pregnancy Complications, Parasitic/parasitology
- Prevalence
- Protozoan Proteins/genetics
- Tanzania/epidemiology
Collapse
Affiliation(s)
- Grace W Mwangoka
- Ifakara Health Research and Development Centre, Bagamoyo Research and Training Unit, Bagamoyo, Tanzania
| | - Sharadhuli I Kimera
- Sokoine University of Agriculture, Department of Veterinary Medicine and Public Health, P.O. Box 3021, Chuo Kikuu, Morogoro, Tanzania
| | - Leonard EG Mboera
- National Institute for Medical Research, Ocean Road, P.O. Box 9653, Dar es salaam, Tanzania
| |
Collapse
|
355
|
Patel SN, Berghout J, Lovegrove FE, Ayi K, Conroy A, Serghides L, Min-oo G, Gowda DC, Sarma JV, Rittirsch D, Ward PA, Liles WC, Gros P, Kain KC. C5 deficiency and C5a or C5aR blockade protects against cerebral malaria. J Exp Med 2008; 205:1133-43. [PMID: 18426986 PMCID: PMC2373845 DOI: 10.1084/jem.20072248] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Accepted: 04/02/2008] [Indexed: 12/13/2022] Open
Abstract
Experimental infection of mice with Plasmodium berghei ANKA (PbA) provides a powerful model to define genetic determinants that regulate the development of cerebral malaria (CM). Based on the hypothesis that excessive activation of the complement system may confer susceptibility to CM, we investigated the role of C5/C5a in the development of CM. We show a spectrum of susceptibility to PbA in a panel of inbred mice; all CM-susceptible mice examined were found to be C5 sufficient, whereas all C5-deficient strains were resistant to CM. Transfer of the C5-defective allele from an A/J (CM resistant) onto a C57BL/6 (CM-susceptible) genetic background in a congenic strain conferred increased resistance to CM; conversely, transfer of the C5-sufficient allele from the C57BL/6 onto the A/J background recapitulated the CM-susceptible phenotype. The role of C5 was further explored in B10.D2 mice, which are identical for all loci other than C5. C5-deficient B10.D2 mice were protected from CM, whereas C5-sufficient B10.D2 mice were susceptible. Antibody blockade of C5a or C5a receptor (C5aR) rescued susceptible mice from CM. In vitro studies showed that C5a-potentiated cytokine secretion induced by the malaria product P. falciparum glycosylphosphatidylinositol and C5aR blockade abrogated these amplified responses. These data provide evidence implicating C5/C5a in the pathogenesis of CM.
Collapse
Affiliation(s)
- Samir N Patel
- Tropical Disease Unit, Department of Medicine, McLaughlin-Rotman Centre for Global Health, Toronto General Hospital, Toronto, Ontario M5G 2C4, Canada
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
356
|
Long GH, Chan BHK, Allen JE, Read AF, Graham AL. Experimental manipulation of immune-mediated disease and its fitness costs for rodent malaria parasites. BMC Evol Biol 2008; 8:128. [PMID: 18447949 PMCID: PMC2391164 DOI: 10.1186/1471-2148-8-128] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Accepted: 04/30/2008] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Explaining parasite virulence (harm to the host) represents a major challenge for evolutionary and biomedical scientists alike. Most theoretical models of virulence evolution assume that virulence arises as a direct consequence of host exploitation, the process whereby parasites convert host resources into transmission opportunities. However, infection-induced disease can be immune-mediated (immunopathology). Little is known about how immunopathology affects parasite fitness, or how it will affect the evolution of parasite virulence. Here we studied the effects of immunopathology on infection-induced host mortality rate and lifetime transmission potential - key components of parasite fitness - using the rodent malaria model, Plasmodium chabaudi chabaudi. RESULTS Neutralizing interleukin [IL]-10, an important regulator of inflammation, allowed us to experimentally increase the proportion of virulence due to immunopathology for eight parasite clones. In vivo blockade of the IL-10 receptor (IL-10R) with a neutralizing antibody resulted in a shorter time to death that was independent of parasite density and was particularly marked for normally avirulent clones. This suggests that IL-10 induction may provide a pathway to avirulence for P. c. chabaudi. Despite the increased investment in transmission-stage parasites observed for some clones in response to IL-10R blockade, experimental enhancement of immunopathology incurred a uniform fitness cost to all parasite clones by reducing lifetime transmission potential. CONCLUSION This is the first experimental study to demonstrate that infection-induced immunopathology and parasite genetic variability may together have the potential to shape virulence evolution. In accord with recent theory, the data show that some forms of immunopathology may select for parasites that make hosts less sick.
Collapse
Affiliation(s)
- Gráinne H Long
- Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3JT, UK.
| | | | | | | | | |
Collapse
|
357
|
Leisewitz AL, Rockett K, Kwiatkowski D. BCG-malaria co-Infection has paradoxical effects on C57BL/6 and A/J mouse strains. Parasite Immunol 2008; 30:1-12. [PMID: 18086011 DOI: 10.1111/j.1365-3024.2007.00983.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bacillus Calmette-Guérin (BCG) infection of the spleen is a potent modifier of splenic function. Prior to malaria infection, we infected two mouse strains of differing susceptibility to Plasmodium chabaudi AS (C57BL/6 and A/J) with this mycobacterium. We then evaluated aspects of spleen cell composition, architecture and cytokine expression, and correlated these with the outcome. BCG preinfection resulted in protection of the A/J mice but paradoxically resulted in mortality of the C57BL/6 mice. The latter developed higher parasitaemias that peaked earlier than the A/J mice rendered resistant by BCG. BCG infection induced remarkable changes to splenic histology examined by H&E staining, but there were no consistent differences between mouse strains. C57BL/6 mice had higher absolute numbers of all immune cell phenotypes than did A/J mice, and higher macrophage and dendritic cell proportions. BCG-induced resistance in A/J mice was associated with an increased CD4+ expression of IFN-gamma whilst induced death in C57BL/6 mice was associated with excessive IFN-gamma expression. A moderate TH1 response in the A/J model may have been responsible for the improved survival, and an excessive TH1 response in the C57BL/6 model may have contributed to their death.
Collapse
Affiliation(s)
- A L Leisewitz
- Department of Veterinary Tropical Diseases, Onderstepoort, South Africa.
| | | | | |
Collapse
|
358
|
Miyazaki Y, Bunting M, Stafforini DM, Harris ES, McIntyre TM, Prescott SM, Frutuoso VS, Amendoeira FC, de Oliveira Nascimento D, Vieira-de-Abreu A, Weyrich AS, Castro-Faria-Neto HC, Zimmerman GA. Integrin alphaDbeta2 is dynamically expressed by inflamed macrophages and alters the natural history of lethal systemic infections. THE JOURNAL OF IMMUNOLOGY 2008; 180:590-600. [PMID: 18097061 DOI: 10.4049/jimmunol.180.1.590] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The leukocyte integrins have critical roles in host defense and inflammatory tissue injury. We found that integrin alphaDbeta2, a novel but largely uncharacterized member of this family, is restricted to subsets of macrophages and a small population of circulating leukocytes in wild-type mice in the absence of inflammatory challenge and is expressed in regulated fashion during cytokine-induced macrophage differentiation in vitro. alphaDbeta2 is highly displayed on splenic red pulp macrophages and mediates their adhesion to local targets, identifying key functional activity. In response to challenge with Plasmodium berghei, a malarial pathogen that models systemic infection and inflammatory injury, new populations of alphaD+ macrophages evolved in the spleen and liver. Unexpectedly, targeted deletion of alphaD conferred a survival advantage in P. berghei infection over a 30-day observation period. Mechanistic studies demonstrated that the increased survival of alphaD-/- animals at these time points is not attributed to differences in magnitude of anemia or parasitemia or to alterations in splenic microanatomy, each of which is a key variable in the natural history of P. berghei infection, and indicated that an altered pattern of inflammatory cytokines may contribute to the difference in mortality. In contrast to the outcome in malarial challenge, death of alphaD-/- animals was accelerated in a model of Salmonella sepsis, demonstrating differential rather than stereotyped roles for alphaDbeta2 in systemic infection. These studies identify previously unrecognized and unique activities of alphaDbeta2, and macrophages that express it, in host defense and injury.
Collapse
Affiliation(s)
- Yasunari Miyazaki
- Program in Human Molecular Biology and Genetics, Huntsman Cancer Institute, Department of Internal Medicine, University of Utah, Salt Lake City 84112, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
359
|
Wong KA, Rodriguez A. Plasmodium infection and endotoxic shock induce the expansion of regulatory dendritic cells. THE JOURNAL OF IMMUNOLOGY 2008; 180:716-26. [PMID: 18178809 DOI: 10.4049/jimmunol.180.2.716] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
During an acute Plasmodium infection, uncontrolled proinflammatory responses can cause morbidity and mortality. Regulation of this response is required to prevent immunopathology. We therefore decided to investigate a recently characterized subset of regulatory dendritic cells (DCs) that expresses low levels of CD11c and high levels of CD45RB. During a Plasmodium yoelii infection, these regulatory CD11clowCD45RBhigh DCs become the prevalent CD11c-expressing cells in the spleen, overtaking the conventional CD11chigh DCs. Furthermore, the regulatory CD11clowCD45RBhigh DCs induce IL-10-expressing CD4 T cells. A similar change in splenic DC subsets is seen when mice are injected with sublethal doses of LPS, suggesting that shifting the splenic DC subsets in favor of regulatory CD11clowCD45RBhigh DCs can be triggered solely by a high inflammatory stimulus. This is the first time regulatory DCs have been observed in a natural immune response to an infectious disease or endotoxic shock.
Collapse
Affiliation(s)
- Kurt A Wong
- Department of Medical Parasitology, New York University School of Medicine, New York, NY 10010, USA
| | | |
Collapse
|
360
|
Baker VS, Imade GE, Molta NB, Tawde P, Pam SD, Obadofin MO, Sagay SA, Egah DZ, Iya D, Afolabi BB, Baker M, Ford K, Ford R, Roux KH, Keller TC. Cytokine-associated neutrophil extracellular traps and antinuclear antibodies in Plasmodium falciparum infected children under six years of age. Malar J 2008; 7:41. [PMID: 18312656 PMCID: PMC2275287 DOI: 10.1186/1475-2875-7-41] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Accepted: 02/29/2008] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND In Plasmodium falciparum-infected children, the relationships between blood cell histopathology, blood plasma components, development of immunocompetence and disease severity remain poorly understood. Blood from Nigerian children with uncomplicated malaria was analysed to gain insight into these relationships. This investigation presents evidence for circulating neutrophil extracellular traps (NETs) and antinuclear IgG antibodies (ANA). The presence of NETs and ANA to double-stranded DNA along with the cytokine profiles found suggests autoimmune mechanisms that could produce pathogenesis in children, but immunoprotection in adults. METHODS Peripheral blood smear slides and blood samples obtained from 21 Nigerian children under six years of age, presenting with uncomplicated malaria before and seven days after initiation of sulphadoxine-pyrimethamine (SP) treatment were analysed. The slides were stained with Giemsa and with DAPI. Levels of the pro-inflammatory cytokines IFN-gamma, IL-2, TNF, CRP, and IL-6, select anti-inflammatory cytokines TGF-beta and IL-10, and ANA were determined by immunoassay. RESULTS The children exhibited circulating NETs with adherent parasites and erythrocytes, elevated ANA levels, a Th2 dominated cytokine profile, and left-shifted leukocyte differential counts. Nonspecific ANA levels were significant in 86% of the children pretreatment and in 100% of the children seven days after SP treatment, but in only 33% of age-matched control samples collected during the season of low parasite transmission. Levels of ANA specific for dsDNA were significant in 81% of the children both pre-treatment and post treatment. CONCLUSION The results of this investigation suggest that NET formation and ANA to dsDNA may induce pathology in falciparum-infected children, but activate a protective mechanism against falciparum malaria in adults. The significance of in vivo circulating chromatin in NETs and dsDNA ANA as a causative factor in the hyporesponsiveness of CpG oligonucleotide-based malaria vaccines is discussed.
Collapse
Affiliation(s)
- Virginia S Baker
- Department of Biological Science, Florida State University, Tallahassee, Florida, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
361
|
|
362
|
Bueno LL, Fujiwara RT, Soares IS, Braga EM. Direct effect of Plasmodium vivax recombinant vaccine candidates AMA-1 and MSP-119 on the innate immune response. Vaccine 2008; 26:1204-13. [PMID: 18242795 DOI: 10.1016/j.vaccine.2007.12.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Revised: 12/15/2007] [Accepted: 12/19/2007] [Indexed: 10/22/2022]
Abstract
The recombinant apical membrane antigen 1 (AMA-1) and 19-kDa fragment of merozoite surface protein (MSP-1(19)) are the lead candidates for inclusion in a vaccine against blood stages of malaria due to encouraging protective studies in humans and animals. Despite the importance of an efficacious malaria vaccine, vaccine-related research has focused on identifying antigens that result in protective immunity rather than determining the nature of anti-malarial immune effector mechanisms. Moreover, emphasis has been placed on adaptive rather than innate immune responses. In this study, we investigated the effect of Plasmodium vivax vaccine candidates Pv-AMA-1 and Pv-MSP-1(19) on the immune response of malaria-naïve donors. Maturation of dendritic cells is altered by Pv-AMA-1 but not Pv-MSP-1(19), as observed by differential expression of cell surface markers. In addition, Pv-AMA-1 induced an increased production of MIP-1alpha/CCL3 and decreased production of TARC/CCL17 levels in both dendritic cells (DCs) and peripheral blood mononuclear cells (PBMCs). Finally, a significant pro-inflammatory response was elicited by Pv-AMA-1-stimulated PBMCs. These results suggest that the recombinant vaccine candidate Pv-AMA-1 may play a direct role on innate immune response and might be involved in parasite destruction.
Collapse
Affiliation(s)
- Lilian Lacerda Bueno
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, 31270-901 Belo Horizonte (MG), Brazil
| | | | | | | |
Collapse
|
363
|
Čokić VP, Schechter AN. Chapter 7 Effects of Nitric Oxide on Red Blood Cell Development and Phenotype. Curr Top Dev Biol 2008; 82:169-215. [DOI: 10.1016/s0070-2153(07)00007-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
364
|
Long GH, Chan BHK, Allen JE, Read AF, Graham AL. Blockade of TNF receptor 1 reduces disease severity but increases parasite transmission during Plasmodium chabaudi chabaudi infection. Int J Parasitol 2007; 38:1073-81. [PMID: 18226816 DOI: 10.1016/j.ijpara.2007.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 11/21/2007] [Accepted: 12/06/2007] [Indexed: 11/28/2022]
Abstract
Reducing host carriage of transmission-stage malaria parasites (gametocytes) is expected to decrease the population-wide burden of malaria. Some malaria disease severity is attributed to the induction of the pro-inflammatory cytokines TNF-alpha and lymphotoxin-alpha (LT-alpha), and we are interested in whether anti-malaria interventions which ameliorate the symptoms induced by those cytokines may have the capacity to alter malaria transmission. As many functions of TNF-alpha and LT-alpha are exerted through TNF receptor 1 (TNFR1), we investigated the effect TNFR1 blockade exerted on parasite transmission using the rodent malaria Plasmodium chabaudi chabaudi. We found that blocking TNFR1 simultaneously increased gametocyte density and infectivity to mosquitoes, whilst reducing disease severity (weight loss). These transmission-enhancing and severity-reducing effects of TNFR1 blockade were independent of asexual parasite load and were observed for several P. c. chabaudi genotypes. These results suggest that the effects of candidate malaria interventions on infectivity should be examined alongside effects on disease severity so that the epidemiological consequences of such interventions can be evaluated.
Collapse
Affiliation(s)
- Gráinne H Long
- Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, Scotland, UK.
| | | | | | | | | |
Collapse
|
365
|
Role of TLRs/MyD88 in host resistance and pathogenesis during protozoan infection: lessons from malaria. Semin Immunopathol 2007; 30:41-51. [PMID: 18071705 DOI: 10.1007/s00281-007-0103-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 11/07/2007] [Indexed: 01/23/2023]
Abstract
Toll-like receptors (TLRs) are important to initiate the innate immune response to a wide variety of pathogens. The protective role of TLRs during infection with protozoan parasites has been established. In this regard, malaria represents an exception where activation of TLRs seems to be deleterious to the host. In this article, we review the recent findings indicating the contrasting role of Myeloid Differentiation Primary-Response gene 88 (MyD88) and TLRs during malaria and infection with other protozoa. These findings suggest that MyD88 may represent an Achilles' heel during Plasmodium infection.
Collapse
|
366
|
Finney CA, Liles WC, Kain KC. Severe malaria and host response: time for a paradigm shift in therapeutic strategies to improve clinical outcome. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.ddmec.2008.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
367
|
TLR-mediated cell signaling by malaria GPIs. Trends Parasitol 2007; 23:596-604. [DOI: 10.1016/j.pt.2007.09.003] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Revised: 09/05/2007] [Accepted: 09/05/2007] [Indexed: 11/18/2022]
|
368
|
Achtman AH, Stephens R, Cadman ET, Harrison V, Langhorne J. Malaria-specific antibody responses and parasite persistence after infection of mice with Plasmodium chabaudi chabaudi. Parasite Immunol 2007; 29:435-44. [PMID: 17727567 DOI: 10.1111/j.1365-3024.2007.00960.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
While it is known that antibodies are critical for clearance of malaria infections, it is not clear whether adequate antibody responses are maintained and what effect chronic infection has on this response. Here we show that mice with low-grade chronic primary infections of Plasmodium chabaudi or infections very recently eliminated have reduced second infections when compared with the second infection of parasite-free mice. We also show that parasite-specific antibody responses induced by infection of mice with Plasmodium chabaudi contain both short- and long-lived components as well as memory B cells responsible for a faster antibody response during re-infection. Furthermore, parasite-specific antibodies to the C-terminal fragment of merozoite surface protein-1 (MSP-1) undergo avidity maturation. However, antibodies with both low and high avidity persist throughout infection and after re-infection, suggesting repeated rounds of activation and maturation of memory B cells. Neither the avidity profile of the antibody response, nor its maintenance is affected by persisting live parasites. Therefore, differences in parasitemia in re-infection cannot be explained solely by higher levels of antibody or greater affinity maturation of malaria-specific antibodies. These data suggest that there may be an antibody-independent component to the early control of secondary infections in mice that are chronically infected.
Collapse
Affiliation(s)
- A H Achtman
- Division of Parasitology, National Institute for Medical Research, The Ridgeway, Mill Hill, London, UK
| | | | | | | | | |
Collapse
|
369
|
Raberg L, Sim D, Read AF. Disentangling Genetic Variation for Resistance and Tolerance to Infectious Diseases in Animals. Science 2007; 318:812-4. [DOI: 10.1126/science.1148526] [Citation(s) in RCA: 552] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
370
|
Hernandez-Valladares M, Naessens J, Iraqi FA. Gene-knockout mice in malaria research: useful or misleading? Trends Parasitol 2007; 23:522-6. [PMID: 17951110 DOI: 10.1016/j.pt.2007.08.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Revised: 08/22/2007] [Accepted: 08/22/2007] [Indexed: 10/22/2022]
Abstract
Gene-knockout mice have been extensively used in the study of several malaria-induced pathologies. Some investigators believe that the deficient, infected mice mimic disease aspects produced in the absence of the target gene, but others believe that the deficient mice models mainly explain the effects of compensatory, related molecules. Comparison of some of the most relevant knockout mouse studies for understanding cerebral malaria and parasitemia and their related human reports shows that gene-knockout mice are useful tools that support conclusions from human genetic studies. These mice have helped to indicate new resistance genes against human malaria and have provided valuable information about mechanisms of malaria resistance in mice.
Collapse
|
371
|
Turcotte K, Gauthier S, Malo D, Tam M, Stevenson MM, Gros P. Icsbp1/IRF-8 is required for innate and adaptive immune responses against intracellular pathogens. THE JOURNAL OF IMMUNOLOGY 2007; 179:2467-76. [PMID: 17675508 DOI: 10.4049/jimmunol.179.4.2467] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The chronic myeloid leukemia syndrome of the BXH-2 mouse strain (Mus musculus) is caused by a recessive mutation (R294C) in the transcriptional regulator Icsbp1/IRF-8. In trans activation assays using an IL-12p40 gene reporter construct introduced in RAW 264.7 mouse macrophages, we show that the Icsbp1(C294) isoform behaves as a partial loss-of-function. The Icsbp1(C294) hypomorph allele appears to have a threshold effect on IL-12 production, with pleiotropic consequences on resistance to different types of infections in vivo. Despite the presence of a resistance Nramp1(G169) allele, BXH-2 mice (Icsbp1(C294)) show impaired control of Mycobacterium bovis (bacille Calmette-Guérin) multiplication both early and late during infection, with uncontrolled replication linked to inability to form granulomas in infected liver and spleen. Studies in informative (BXH-2 x BALB/cJ)F(2) mice show that homozygosity for Icsbp1(C294) causes susceptibility to Salmonella enterica serovar Typhimurium to a level comparable to that seen for mice lacking functional Nramp1 or TLR4. Finally, impaired Icsbp1(C294) function is associated with the following: 1) increased replication of the Plasmodium chabaudi AS malarial parasite during the first burst of blood parasitemia, and 2) recurring waves of high blood parasitemia late during infection. These results show that Icsbp1 is required for orchestrating early innate responses and also long-term immune protection against unrelated intracellular pathogens.
Collapse
MESH Headings
- Amino Acid Substitution
- Animals
- Cation Transport Proteins/genetics
- Cation Transport Proteins/immunology
- Cell Line
- Genes, Recessive
- Immunity, Innate/genetics
- Interferon Regulatory Factors/genetics
- Interferon Regulatory Factors/immunology
- Interleukin-12 Subunit p40/immunology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/immunology
- Macrophages/immunology
- Macrophages/microbiology
- Macrophages/parasitology
- Malaria/genetics
- Malaria/immunology
- Malaria/veterinary
- Mice
- Mice, Inbred BALB C
- Mice, Mutant Strains
- Mutation, Missense
- Mycobacterium bovis/immunology
- Parasitemia/genetics
- Parasitemia/immunology
- Plasmodium chabaudi/immunology
- Salmonella Infections/genetics
- Salmonella Infections/immunology
- Salmonella typhimurium/immunology
- Syndrome
- Toll-Like Receptor 4/genetics
- Toll-Like Receptor 4/immunology
- Tuberculosis/genetics
- Tuberculosis/immunology
- Tuberculosis/veterinary
Collapse
Affiliation(s)
- Karine Turcotte
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | | | | | | | | | | |
Collapse
|
372
|
Martin-Blondel G, Barry M, Porte L, Busato F, Massip P, Benoit-Vical F, Berry A, Marchou B. Impact de l'infection VIH sur l'infection palustre chez l'adulte. Med Mal Infect 2007; 37:629-36. [PMID: 17628374 DOI: 10.1016/j.medmal.2007.03.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2007] [Accepted: 03/29/2007] [Indexed: 11/26/2022]
Abstract
Malaria and HIV are two major public health issues, especially in sub-Saharan Africa. The impact of HIV infection on malaria depends on the patient's immune status: immunodepression level but also immunity against Plasmodium. HIV infection increases the incidence of clinical malaria, inversely correlated with the degree of immunodepression, but the severity and mortality are increased only in areas of unstable malaria. In severe malaria the level of parasitemia is similar in HIV-positive and HIV-negative patients. During pregnancy, HIV infection increases the incidence of clinical malaria, maternal morbidity, and fetal and neonatal morbi-mortality. Sulfa-based therapies reduce the risk of malaria, most importantly in pregnancy. HIV infection increases the risk of treatment failure, mainly with sulfa-based therapies, due to re-infection or parasitic recrudescence. Further studies are needed to determine the pathophysiological interactions between HIV infection and malaria.
Collapse
Affiliation(s)
- G Martin-Blondel
- Service des maladies infectieuses et tropicales, hôpital Purpan, place du Docteur-Baylac, TSA 40031, 31059 Toulouse cedex 09, France
| | | | | | | | | | | | | | | |
Collapse
|
373
|
D'Ombrain MC, Hansen DS, Simpson KM, Schofield L. gammadelta-T cells expressing NK receptors predominate over NK cells and conventional T cells in the innate IFN-gamma response to Plasmodium falciparum malaria. Eur J Immunol 2007; 37:1864-73. [PMID: 17557374 DOI: 10.1002/eji.200636889] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Rapid production of interferon-gamma (IFN-gamma) in response to malaria by the innate immune system may determine resistance to infection, or inflammatory disease. However, conflicting reports exist regarding the identity of IFN-gamma-producing cells that rapidly respond to Plasmodium falciparum. To clarify this area, we undertook detailed phenotyping of IFN-gamma-producing cells across a panel of naive human donors following 24-h exposure to live schizont-infected red blood cells (iRBC). Here, we show that NK cells comprise only a small proportion of IFN-gamma-responding cells and that IFN-gamma production is unaffected by NK cell depletion. Instead, gammadelta-T cells represent the predominant source of innate IFN-gamma, with the majority of responding gammadelta-T cells expressing NK receptors. Malaria-responsive gammadelta-T cells more frequently expressed NKG2A compared to non-responding gammadelta-T cells, while non-responding gammadelta-T cells more frequently expressed CD158a/KIR2DL1. Unlike long-term gammadelta-T cell responses to iRBC, alphabeta-T cell help was not required for innate gammadelta-T cell responses. Diversity was observed among donors in total IFN-gamma output. This was positively associated with CD94 expression on IFN-gamma(+) NK-like gammadelta-T cells. Applied to longitudinal cohort studies in endemic regions, similar comparative phenotyping should allow assessment of the contribution of diverse cell populations and regulatory receptors to risk of infection and disease.
Collapse
MESH Headings
- Enzyme-Linked Immunosorbent Assay
- Flow Cytometry
- Humans
- Interferon-gamma/biosynthesis
- Interferon-gamma/immunology
- Killer Cells, Natural/immunology
- Lymphocyte Activation/immunology
- Malaria, Falciparum/immunology
- NK Cell Lectin-Like Receptor Subfamily C
- NK Cell Lectin-Like Receptor Subfamily D/immunology
- Phenotype
- Receptors, Antigen, T-Cell, gamma-delta/immunology
- Receptors, Antigen, T-Cell, gamma-delta/metabolism
- Receptors, Immunologic/immunology
- Receptors, KIR
- Receptors, KIR2DL1
- Receptors, Natural Killer Cell
- T-Lymphocyte Subsets/immunology
Collapse
Affiliation(s)
- Marthe C D'Ombrain
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | | | | | | |
Collapse
|
374
|
Ocaña-Morgner C, Wong KA, Lega F, Dotor J, Borras-Cuesta F, Rodriguez A. Role of TGF-beta and PGE2 in T cell responses during Plasmodium yoelii infection. Eur J Immunol 2007; 37:1562-74. [PMID: 17474154 DOI: 10.1002/eji.200737068] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
During an acute blood-stage malaria infection, T cell responses to malaria and other bystander antigens are inhibited. Plasmodium infection induces strong cytokine responses that facilitate parasite clearance but may interfere with T cell functions, as some of the soluble immune mediators induced are also general inhibitors of T cell responses. Using a malaria mouse model, we have analyzed the cytokines produced by dendritic cells in response to P. yoelii infection that have potential T cell inhibitory activity. We found that during acute infection DC migrate to the spleen and secrete TGF-beta, prostaglandin E2 (PGE2) and IL-10. We have analyzed the role of these general T cell inhibitors in a particular T cell response of evident importance in malaria infections: the CD8+ T cells generated against the liver-stage of the disease. During blood-stage infection, inhibition of the activity of TGF-beta and PGE2 restores the CD8+ T cell responses generated by sporozoites, increasing protection against re-infection. Our findings suggest that the strong cytokine response induced by blood-stage P. yoelii infection affects host T cell responses, inhibiting protective CD8+ T cells against the liver-stage of the disease.
Collapse
Affiliation(s)
- Carlos Ocaña-Morgner
- New York University School of Medicine, Department of Medical Parasitology, New York, NY 10010, USA
| | | | | | | | | | | |
Collapse
|
375
|
Chiyaka C, Garira W, Dube S. Transmission model of endemic human malaria in a partially immune population. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.mcm.2006.12.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
376
|
Hansen DS, D'Ombrain MC, Schofield L. The role of leukocytes bearing Natural Killer Complex receptors and Killer Immunoglobulin-like Receptors in the immunology of malaria. Curr Opin Immunol 2007; 19:416-23. [PMID: 17702559 DOI: 10.1016/j.coi.2007.07.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Accepted: 07/05/2007] [Indexed: 10/22/2022]
Abstract
The biology of Natural Killer (NK) cells and other NK Receptor (NKR)(+) leukocytes has largely been elucidated in viral or cancer systems, and involvement in other diseases or infectious states is less clearly defined. Recently, however, clear evidence has emerged for a role in malaria. NK cells and NKR(+) leukocytes significantly control susceptibility and resistance to both malaria infection and severe disease syndromes in murine models, in dependence upon receptors encoded within the Natural Killer Complex (NKC). Plasmodium falciparum can rapidly activate human NKR(+) gammadelta T cells and NK cells in vitro, and these responses are controlled partly by NKR loci encoded within the human syntenic NKC and Killer Immunoglobulin-like Receptor (KIR) genomic regions. Neither erythrocytes nor malaria parasites express HLA or MHC Class I-like homologues, or obvious stress-type ligands, suggesting the possibility of novel NKR recognition mechanisms. Parasite-derived ligands such as P. falciparum Erythrocyte Membrane Protein-1 (PfEMP-1) and glycosylphosphatidylinositol (GPI) regulate some of these diverse responses. Population-based immunogenetic analyses should allow the identification of NKC and KIR loci controlling innate and adaptive immune responses to malaria and associated with altered risk of infection and disease.
Collapse
Affiliation(s)
- Diana S Hansen
- The Walter and Eliza Hall Institute of Medical Research, 1G, Royal Parade, Parkville 3050, Victoria, Australia
| | | | | |
Collapse
|
377
|
Aponte JJ, Menendez C, Schellenberg D, Kahigwa E, Mshinda H, Vountasou P, Tanner M, Alonso PL. Age interactions in the development of naturally acquired immunity to Plasmodium falciparum and its clinical presentation. PLoS Med 2007; 4:e242. [PMID: 17676985 PMCID: PMC1950208 DOI: 10.1371/journal.pmed.0040242] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Accepted: 06/14/2007] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Naturally acquired malaria immunity has many determinants and, in the absence of immunological markers of protection, studies assessing malaria incidence through clinical endpoints remain an approach to defining immunity acquisition. We investigated the role of age in disease incidence and the effects of chemoprophylaxis on clinical immunity development to Plasmodium falciparum during a randomised controlled trial. METHODS AND FINDINGS A total of 415 Tanzanian infants were randomly assigned to receive weekly malaria prophylaxis with Deltaprim (3.125 mg of pyrimethamine plus 25 mg of dapsone) or placebo between the ages of 2 and 12 mo. Children were followed up until 4 y of age. Uncomplicated febrile malaria, severe malaria, and anaemia morbidity were assessed through hospital-based passive surveillance. Compared with the group of control participants, there was a marked reduction in the incidence of clinical malaria, severe malaria, and anaemia in the group of children who had received chemoprophylaxis during the first year of life. After discontinuing the intervention, there was a significant increase in the incidence of clinical malaria for 2 y. The cumulative rates of clinical malaria, by age 4 y, were slightly higher in the group of children who had previously received chemoprophylaxis: 3.22 episodes versus 3.02 episodes in the group of control participants; rate difference 0.20 (95% confidence interval [CI]: -0.21 to 0.59). By age 4 y, the cumulative rates of severe malaria, however, were slightly lower in chemosuppressed children (0.47 versus 0.59) (rate difference -0.12 [95% CI: -0.27 to 0.03]). The number of episodes of anaemia was also slightly lower in chemosuppressed children by age 4 y: 0.93 episodes (95% CI: 0.79 to 0.97) versus 1.12 episodes in the group of control participants (95% CI: 0.97 to 1.28) (rate difference -0.19 [95% CI: -0.40 to 0.01]), respectively. CONCLUSIONS Reducing exposure to P. falciparum antigens through chemoprophylaxis early in life can delay immunity acquisition. Infants appear to acquire immunity faster than older children, but have a higher risk of developing severe forms of malaria and anaemia. These findings provide insight on the interplay between immunity and exposure-reduction interventions.
Collapse
Affiliation(s)
- John J Aponte
- Barcelona Centre for International Health Research, Hospital Clinic/IDIBAPS, Universitat de Barcelona, Barcelona, Spain.
| | | | | | | | | | | | | | | |
Collapse
|
378
|
Newman KC, Korbel DS, Hafalla JC, Riley EM. Cross-talk with myeloid accessory cells regulates human natural killer cell interferon-gamma responses to malaria. PLoS Pathog 2007; 2:e118. [PMID: 17154717 PMCID: PMC1687207 DOI: 10.1371/journal.ppat.0020118] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Accepted: 09/21/2006] [Indexed: 11/19/2022] Open
Abstract
Data from a variety of experimental models suggest that natural killer (NK) cells require signals from accessory cells in order to respond optimally to pathogens, but the precise identity of the cells able to provide such signals depends upon the nature of the infectious organism. Here we show that the ability of human NK cells to produce interferon-γ in response to stimulation by Plasmodium falciparum–infected red blood cells (iRBCs) is strictly dependent upon multiple, contact-dependent and cytokine-mediated signals derived from both monocytes and myeloid dendritic cells (mDCs). Contrary to some previous reports, we find that both monocytes and mDCs express an activated phenotype following short-term incubation with iRBCs and secrete pro-inflammatory cytokines. The magnitude of the NK cell response (and of the KIR− CD56bright NK cell population in particular) is tightly correlated with resting levels of accessory cell maturation, indicating that heterogeneity of the NK response to malaria is a reflection of deep-rooted heterogeneity in the human innate immune system. Moreover, we show that NK cells are required to maintain the maturation status of resting mDCs and monocytes, providing additional evidence for reciprocal regulation of NK cells and accessory cells. However, NK cell–derived signals are not required for activation of accessory cells by either iRBCs or bacterial lipolysaccharide. Together, these data suggest that there may be differences in the sequence of events required for activation of NK cells by non-viral pathogens compared to the classical model of NK activation by virus-infected or major histocompatibility complex–deficient cells. These findings have far-reaching implications for the study of immunity to infection in human populations. The outcome of infection is determined both by the ability to limit the initial phase of pathogen colonisation and by the ability to mount an effective adaptive immune response. Both of these processes are influenced by innate immune responses, of which a crucial component can be the ability of natural killer (NK) cells to secrete pro-inflammatory cytokines. Studies in both humans and mice indicate that the magnitude of the early (innate) interferon (IFN)–γ response is a crucial determinant of the outcome of malaria infection. In this study, Newman et al. show that activation of human NK cells by Plasmodium falciparum–infected red blood cells to produce IFN-γ is strictly dependent upon, and regulated by, contact-mediated and soluble (cytokine) signals from two accessory cell populations (myeloid dendritic cells and monocytes). Furthermore, the magnitude of the human NK cell IFN-γ response to P. falciparum–infected red blood cells is highly correlated with levels of expression of co-stimulatory molecules on resting accessory cells. These findings suggest that it might be possible to predict the magnitude of the innate cytokine response, and possibly even susceptibility to malarial disease, from the phenotype of resting monocytes. In addition, these data contribute to the development of a new model of NK activation by non-viral pathogens in which activation of accessory cells precedes, rather than follows, NK activation.
Collapse
Affiliation(s)
- Kirsty C Newman
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Daniel S Korbel
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Julius C Hafalla
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Eleanor M Riley
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
379
|
Cytokine responses of CD4+ T cells during a Plasmodium chabaudi chabaudi (ER) blood-stage infection in mice initiated by the natural route of infection. Malar J 2007; 6:77. [PMID: 17555592 PMCID: PMC1904224 DOI: 10.1186/1475-2875-6-77] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Accepted: 06/07/2007] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Investigation of host responses to blood stages of Plasmodium spp, and the immunopathology associated with this phase of the life cycle are often performed on mice infected directly with infected red blood cells. Thus, the effects of mosquito bites and the pre-erythrocytic stages of the parasite, which would be present in natural infection, are ignored In this paper, Plasmodium chabaudi chabaudi infections of mice injected directly with infected red blood cells were compared with those of mice infected by the bites of infected mosquitoes, in order to determine whether the courses of primary infection and splenic CD4 T cell responses are similar. METHODS C57Bl/6 mice were injected with red blood cells infected with P. chabaudi (ER) or infected via the bite of Anopheles stephensi mosquitoes. Parasitaemia were monitored by Giemsa-stained thin blood films. Total spleen cells, CD4+ T cells, and cytokine production (IFN-gamma, IL-2, IL-4, IL-10) were analysed by flow cytometry. In some experiments, mice were subjected to bites of uninfected mosquitoes prior to infectious bites in order to determine whether mosquito bites per se could affect a subsequent P. chabaudi infection. RESULTS P. chabaudi (ER) infections initiated by mosquito bite were characterized by lower parasitaemia of shorter duration than those observed after direct blood challenge. However, splenomegaly was comparable suggesting that parasitaemia alone does not account for the increase in spleen size. Total numbers of CD4 T cells and those producing IFN-gamma, IL-10 and IL-2 were reduced in comparison to direct blood challenge. By contrast, the reduction in IL-4 producing cells was less marked suggesting that there is a proportionally lower Th1-like response in mice infected via infectious mosquitoes. Strikingly, pre-exposure to bites of uninfected mosquitoes reduced the magnitude and duration of the subsequent mosquito-transmitted infection still further, but enhanced the response of CD4 T cells producing IFN-gamma and IL-4. CONCLUSION The data in this paper suggest that studying early host responses in blood stage malaria infections measured after direct blood challenge of mice may not completely reflect the natural situation, and more detailed investigations of blood-stage immunity after mosquito transmission in experimental models should be considered.
Collapse
|
380
|
Patel SN, Lu Z, Ayi K, Serghides L, Gowda DC, Kain KC. Disruption of CD36 impairs cytokine response to Plasmodium falciparum glycosylphosphatidylinositol and confers susceptibility to severe and fatal malaria in vivo. THE JOURNAL OF IMMUNOLOGY 2007; 178:3954-61. [PMID: 17339496 DOI: 10.4049/jimmunol.178.6.3954] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
CD36 is a scavenger receptor that has been implicated in malaria pathogenesis as well as innate defense against blood-stage infection. Inflammatory responses to Plasmodium falciparum GPI (pfGPI) anchors are believed to play an important role in innate immune response to malaria. We investigated the role of CD36 in pfGPI-induced MAPK activation and proinflammatory cytokine secretion. Furthermore, we explored the role of this receptor in an experimental model of acute malaria in vivo. We demonstrate that ERK1/2, JNK, p38, and c-Jun became phosphorylated in pfGPI-stimulated macrophages. In contrast, pfGPI-induced phosphorylation of JNK, ERK1/2, and c-Jun was reduced in Cd36(-/-) macrophages and Cd36(-/-) macrophages secreted significantly less TNF-alpha in response to pfGPI than their wild-type counterparts. In addition, we demonstrate a role for CD36 in innate immune response to malaria in vivo. Compared with wild-type mice, Cd36(-/-) mice experienced more severe and fatal malaria when challenged with Plasmodium chabaudi chabaudi AS. Cd36(-/-) mice displayed a combined defect in cytokine induction and parasite clearance with a dysregulated cytokine response to infection, earlier peak parasitemias, higher parasite densities, and higher mortality rates than wild-type mice. These results provide direct evidence that pfGPI induces TNF-alpha secretion in a CD36-dependent manner and support a role for CD36 in modulating host cytokine response and innate control of acute blood-stage malaria infection in vivo.
Collapse
Affiliation(s)
- Samir N Patel
- McLaughlin-Rotman Centre, University Health Network-Toronto General Hospital, McLaughlin Centre for Molecular Medicine, University of Toronto, 200 Elizabeth Street, Toronto, Ontario, Canada
| | | | | | | | | | | |
Collapse
|
381
|
Togbe D, Schofield L, Grau GE, Schnyder B, Boissay V, Charron S, Rose S, Beutler B, Quesniaux VFJ, Ryffel B. Murine cerebral malaria development is independent of toll-like receptor signaling. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 170:1640-8. [PMID: 17456769 PMCID: PMC1854958 DOI: 10.2353/ajpath.2007.060889] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/26/2007] [Indexed: 11/20/2022]
Abstract
Malaria pigment hemozoin was reported to activate the innate immunity by Toll-like receptor (TLR)-9 engagement. However, the role of TLR activation for the development of cerebral malaria (CM), a lethal complication of malaria infection in humans, is unknown. Using Plasmodium berghei ANKA (PbA) infection in mice as a model of CM, we report here that TLR9-deficient mice are not protected from CM. To exclude the role of other members of the TLR family in PbA recognition, we infected mice deficient for single TLR1, -2, -3, -4, -6, -7, or -9 and their adapter proteins MyD88, TIRAP, and TRIF. In contrast to lymphotoxin alpha-deficient mice, which are resistant to CM, all TLR-deficient mice were as sensitive to fatal CM development as wild-type control mice and developed typical microvascular damage with vascular leak and hemorrhage in the brain and lung, together with comparable parasitemia, thrombocytopenia, neutrophilia, and lymphopenia. In conclusion, the present data do not exclude the possibility that malarial molecular motifs may activate the innate immune system. However, TLR-dependent activation of innate immunity is unlikely to contribute significantly to the proinflammatory response to PbA infection and the development of fatal CM.
Collapse
Affiliation(s)
- Dieudonnée Togbe
- Molecular Immunology and Embryology, Centre National de la Recherche Scientifique, and University of Orleans, Transgenose Institute, Orleans, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
382
|
Clatworthy MR, Willcocks L, Urban B, Langhorne J, Williams TN, Peshu N, Watkins NA, Floto RA, Smith KGC. Systemic lupus erythematosus-associated defects in the inhibitory receptor FcgammaRIIb reduce susceptibility to malaria. Proc Natl Acad Sci U S A 2007; 104:7169-74. [PMID: 17435165 PMCID: PMC1855357 DOI: 10.1073/pnas.0608889104] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Polygenic autoimmune diseases, such as systemic lupus erythematosus (SLE), are a significant cause of morbidity and mortality worldwide. In recent years, functionally important genetic polymorphisms conferring susceptibility to SLE have been identified, but the evolutionary pressures driving their retention in the gene pool remain elusive. A defunctioning, SLE-associated polymorphism of the inhibitory receptor FcgammaRIIb is found at an increased frequency in African and Asian populations, broadly corresponding to areas where malaria is endemic. Here, we show that FcgammaRIIb-deficient mice have increased clearance of malarial parasites (Plasmodium chabaudi chabaudi) and develop less severe disease. In vitro, the human lupus associated FcgammaRIIb polymorphism enhances phagocytosis of Plasmodium falciparum-infected erythrocytes. These results demonstrate that FcgammaRIIb is important in controlling the immune response to malarial parasites and suggests that the higher frequency of human FcgammaRIIb polymorphisms predisposing to SLE in Asians and Africans may be maintained because these variants reduce susceptibility to malaria.
Collapse
Affiliation(s)
| | - Lisa Willcocks
- *Cambridge Institute for Medical Research and Department of Medicine and
| | - Britta Urban
- Centre for Clinical Vaccinology and Tropical Medicine, Nuffield Department of Clinical Medicine, Oxford University, Oxford OX1 2JD, United Kingdom
| | - Jean Langhorne
- Division of Parasitology, National Institute for Medical Research, London, London NW7 1AA, United Kingdom; and
| | - Tom N. Williams
- Centre for Geographic Medicine Research, P.O. Box 230, Coast, Kenya
| | - Norbert Peshu
- Centre for Geographic Medicine Research, P.O. Box 230, Coast, Kenya
| | - Nicholas A. Watkins
- Department of Haematology, University of Cambridge, Cambridge CB2 1TN, United Kingdom
| | - R. Andres Floto
- *Cambridge Institute for Medical Research and Department of Medicine and
| | - Kenneth G. C. Smith
- *Cambridge Institute for Medical Research and Department of Medicine and
- To whom correspondence should be addressed. E-mail:
| |
Collapse
|
383
|
Franklin BS, Rodrigues SO, Antonelli LR, Oliveira RV, Goncalves AM, Sales-Junior PA, Valente EP, Alvarez-Leite JI, Ropert C, Golenbock DT, Gazzinelli RT. MyD88-dependent activation of dendritic cells and CD4(+) T lymphocytes mediates symptoms, but is not required for the immunological control of parasites during rodent malaria. Microbes Infect 2007; 9:881-90. [PMID: 17537666 DOI: 10.1016/j.micinf.2007.03.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 03/10/2007] [Accepted: 03/12/2007] [Indexed: 12/14/2022]
Abstract
We investigated the role of different TLRs and MyD88 in host resistance to infection and malaria pathogenesis. TLR2(-/-), TLR4(-/-), TLR6(-/-), TLR9(-/-) or CD14(-/-) mice showed no change in phenotypes (parasitemia, body weight and temperature) when infected with Plasmodium chabaudi chabaudi (AS). MyD88(-/-) mice displayed comparable ability to wild type animals in controlling and clearing parasitemia. Importantly, MyD88(-/-) mice exhibited impaired production of TNF-alpha and IFN-gamma as well as attenuated symptoms, as indicated by changes in body weight and temperature during parasitemia. Consistently, CD11b(+) monocytes and CD11c(+) dendritic cells from infected MyD88(-/-) mice were shown impaired for production of pro-inflammatory cytokines, and in initiating CD4(+) T cell responses. Importantly, the inhibition of T cell activation with anti-CD134L, mostly inhibited IFN-gamma, partially inhibited TNF-alpha production, and protected the animals from malaria symptoms. Our findings suggest that MyD88 and possibly its associated TLRs expressed by dendritic cells play an important role in pro-inflammatory responses, T cell activation, and pathogenesis of malaria, but are not critical for the immunological control of the erythrocytic stage of P. chabaudi.
Collapse
|
384
|
Sharma SK, Gupta C, Dwivedi V, Misra-Bhattacharya S, Mohammad O. Prophylactic potential of liposomized integral membrane protein of Plasmodium yoelii nigeriensis against blood stage infection in BALB/c mice. Vaccine 2007; 25:2103-11. [PMID: 17241709 DOI: 10.1016/j.vaccine.2006.11.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 11/12/2006] [Accepted: 11/13/2006] [Indexed: 10/23/2022]
Abstract
Triton X-114 phase separated integral membrane proteins (IMPs) of a multidrug resistant strain of Plasmodium yoelii nigeriensis (P. yoelii) were screened for their potential to impart protection against malaria infection in BALB/c mice. As revealed by immunoblotting, antibodies present in parasite specific sera from convalescent (protected) as well as immunized (partially protected) animals recognized different membrane proteins. A thorough investigation reveals that P. yoelii specific convalescent sera recognized IMPs with molecular masses ranging from 21 to 81 kDa. Among various membrane proteins, the IMPs corresponding to 81 and 66 kDa molecular weight were highly prominent in the immunoblots probed with the sera from convalescent animals, whereas sera from immunized animals failed to produce impressive band pattern. Immunofluorescence assay revealed that the 66-kDa IMP specific antibodies reacted with fixed smears of mature schizonts and merozoites. Further immunization with 66 kDa IMP (PyIMP) purified through polyclonal IgG sepharose 4B affinity did not impart effective immune response (in its free form) and could provided partial protection only. On the other hand, animals immunized with 66 kDa PyIMP entrapped in phosphatidyl-choline/cholesterol (PC/chol) liposomes protected BALB/c mice against lethal P. yoelii challenge.
Collapse
Affiliation(s)
- Sharad Kumar Sharma
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, India
| | | | | | | | | |
Collapse
|
385
|
Min-Oo G, Fortin A, Pitari G, Tam M, Stevenson MM, Gros P. Complex genetic control of susceptibility to malaria: positional cloning of the Char9 locus. ACTA ACUST UNITED AC 2007; 204:511-24. [PMID: 17312006 PMCID: PMC2137903 DOI: 10.1084/jem.20061252] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mouse strains AcB55 and AcB61 are resistant to malaria by virtue of a mutation in erythrocyte pyruvate kinase (PklrI90N). Linkage analysis in [AcB55 × A/J] F2 mice detected a second locus (Char9; logarithm of odds = 4.74) that regulates the blood-stage replication of Plasmodium chabaudi AS independently of Pklr. We characterized the 77 genes of the Char9 locus for tissue-specific expression, strain-specific alterations in gene expression, and polymorphic variants that are possibly associated with differential susceptibility. We identified Vnn1/Vnn3 as the likely candidates responsible for Char9. Vnn3/Vnn1 map within a conserved haplotype block and show expression levels that are strictly cis-regulated by this haplotype. The absence of Vnn messenger RNA expression and lack of pantetheinase protein activity in tissues are associated with susceptibility to malaria and are linked to a complex rearrangement in the Vnn3 promoter region. The A/J strain also carries a unique nonsense mutation that leads to a truncated protein. Vanin genes code for a pantetheinase involved in the production of cysteamine, a key regulator of host responses to inflammatory stimuli. Administration of cystamine in vivo partially corrects susceptibility to malaria in A/J mice, as measured by reduced blood parasitemia and decreased mortality. These studies suggest that pantetheinase is critical for the host response to malaria.
Collapse
Affiliation(s)
- Gundula Min-Oo
- Department of Biochemistry, The Research Institute of McGill University Health Centre, McGill University, Montreal H3G-1Y6, Quebec, Canada
| | | | | | | | | | | |
Collapse
|
386
|
Soulard V, Roland J, Sellier C, Gruner AC, Leite-de-Moraes M, Franetich JF, Rénia L, Cazenave PA, Pied S. Primary infection of C57BL/6 mice with Plasmodium yoelii induces a heterogeneous response of NKT cells. Infect Immun 2007; 75:2511-22. [PMID: 17307938 PMCID: PMC1865793 DOI: 10.1128/iai.01818-06] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
NKT cells are a population of innate-like lymphocytes that display effector functions and immunoregulatory properties. We characterized the NKT cell response induced in C57BL/6 mice during a primary infection with Plasmodium yoelii sporozoites. We observed a heterogeneous NKT cell response that differed between liver and spleen. Hepatic NKT cells found in infected livers consisted mainly of CD1d-dependent CD4+ and double-negative (DN) NKT cells, whereas CD1d-independent NKT cells exhibiting a TCR(high) CD4(high) phenotype were prominent among splenic NKT cells during the infection. Hepatic and splenic NKT cells isolated from infected mice were activated and secreted mainly gamma interferon and tumor necrosis factor alpha in response to stimulation. Finally, P. yoelii-activated hepatic DN NKT cells inhibited the parasite's liver stage in a CD1d-dependent manner in vitro. However, experiments using B6.CD1d-deficient mice showed that CD1d and CD1d-restricted NKT cells are not necessary to control the parasite's development in vivo during neither the preerythrocytic stage nor the erythrocytic stage. Thus, our results show that a primary P. yoelii infection induces a heterogeneous and organ-specific response of NKT cells and that CD1d-dependent NKT cells play a minor role in the control of the development of Plasmodium in vivo in our model.
Collapse
Affiliation(s)
- Valérie Soulard
- Unité d'Immunophysiopathologie Infectieuse, Institut Pasteur, 25-28 rue du Docteur Roux, 75724 Paris Cedex 15, France
| | | | | | | | | | | | | | | | | |
Collapse
|
387
|
Delahaye NF, Barbier M, Fumoux F, Rihet P. Association analyses of NCR3 polymorphisms with P. falciparum mild malaria. Microbes Infect 2007; 9:160-6. [PMID: 17208487 DOI: 10.1016/j.micinf.2006.11.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 11/01/2006] [Accepted: 11/07/2006] [Indexed: 11/28/2022]
Abstract
Plasmodium falciparum malaria is a major cause of morbidity and mortality in many developing countries especially in sub-Saharan Africa. A susceptibility locus for mild malaria has been mapped to the MHC region, and TNF polymorphisms have been associated with mild malaria. The Natural Cytotoxicity-triggering Receptor 3 (NCR3) gene is located in the peak region of linkage, and is 15kb distal to TNF. In this study, we considered NCR3 as a candidate gene, and we genotyped ten NCR3 single nucleotide polymorphisms (SNPs). Here, we report evidence of an association between mild malaria and NCR3 -412G>C polymorphism located within the promoter. Population-based association analysis showed that NCR3 -412C carriers had more frequent mild malaria attacks than NCR3 -412GG individuals (P=0.001). Using the family-based association test (FBAT) program and its phenotype (PBAT) option, we further found that NCR3 -412C (P=0.0009) and a haplotype containing NCR3 -412C (P=0.008) were significantly associated with increased risk of mild malaria, and that the association was not due to the association of TNF with mild malaria. These observations suggest that there are at least two genes located on the central region of MHC involved in genetic control of human malaria. The association of NCR3 with malaria should provide new insights into the role of Natural Killer cells in this common disease.
Collapse
Affiliation(s)
- Nicolas F Delahaye
- Université de la Méditerranée, IFR 48, Faculté de Pharmacie, Laboratoire de Pharmacogénétique des Maladies Parasitaires-EA 864, 27 Bd Jean Moulin 13385 Marseille, France
| | | | | | | |
Collapse
|
388
|
Parroche P, Lauw FN, Goutagny N, Latz E, Monks BG, Visintin A, Halmen KA, Lamphier M, Olivier M, Bartholomeu DC, Gazzinelli RT, Golenbock DT. Malaria hemozoin is immunologically inert but radically enhances innate responses by presenting malaria DNA to Toll-like receptor 9. Proc Natl Acad Sci U S A 2007; 104:1919-24. [PMID: 17261807 PMCID: PMC1794278 DOI: 10.1073/pnas.0608745104] [Citation(s) in RCA: 398] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Hemozoin (HZ) is an insoluble crystal formed in the food vacuole of malaria parasites. HZ has been reported to induce inflammation by directly engaging Toll-like receptor (TLR) 9, an endosomal receptor. "Synthetic" HZ (beta-hematin), typically generated from partially purified extracts of bovine hemin, is structurally identical to natural HZ. When HPLC-purified hemin was used to synthesize the crystal, beta-hematin had no inflammatory activity. In contrast, natural HZ from Plasmodium falciparum cultures was a potent TLR9 inducer. Natural HZ bound recombinant TLR9 ectodomain, but not TLR2. Both TLR9 stimulation and TLR9 binding of HZ were abolished by nuclease treatment. PCR analysis demonstrated that natural HZ is coated with malarial but not human DNA. Purified malarial DNA activated TLR9 but only when DNA was targeted directly to the endosome with a transfection reagent. Stimulatory quantities of natural HZ contain <1 microg of malarial DNA; its potency in activating immune responses was even greater than transfecting malarial DNA. Thus, although the malarial genome is extremely AT-rich, its DNA is highly proinflammatory, with the potential to induce cytokinemia and fever during disease. However, its activity depends on being bound to HZ, which we propose amplifies the biological responses to malaria DNA by targeting it to a TLR9(+) intracellular compartment.
Collapse
Affiliation(s)
- Peggy Parroche
- *Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Fanny N. Lauw
- *Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Nadege Goutagny
- *Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Eicke Latz
- *Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Brian G. Monks
- *Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Alberto Visintin
- *Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Kristen A. Halmen
- *Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Marc Lamphier
- Eisai Research Institute, 4 Corporate Drive, Andover, MA 01810
| | - Martin Olivier
- Department of Microbiology/Immunology, McGill University, Montreal, Quebec, Canada H3A 2T8; and
| | - Daniella C. Bartholomeu
- Department of Biochemistry and Immunology and Department of Parasitology, Biological Sciences Institute, Federal University of Minas Gerais, 6627 Belo Horizonte, Brazil
| | - Ricardo T. Gazzinelli
- *Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
- Centro de Pesquisas René Rachou, FIOCRUZ, 1715 Belo Horizonte, Brazil
- Department of Biochemistry and Immunology and Department of Parasitology, Biological Sciences Institute, Federal University of Minas Gerais, 6627 Belo Horizonte, Brazil
| | - Douglas T. Golenbock
- *Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
- To whom correspondence should be addressed at:
Division of Infectious Diseases and Immunology, University of Massachusetts Medical School; LRB 308, 364 Plantation Street, Worcester, MA 01605. E-mail:
| |
Collapse
|
389
|
Abstract
Malaria, caused by the infection with parasites of the germs Plasmodium, is one of the three most important infectious diseases worldwide, along with tuberculosis and infection with human immunodeficiency virus. Natural killer (NK) cells are lymphocytes classically involved in the early defense against viral infections and intracytoplasmic bacterial infections and are also implicated during the course of tumor development and allogeneic transplantation. These cells display important cytotoxic activity and produce high levels of proinflammatory cytokines. In both mouse and human models of malaria, NK cells appear to be a major source of interferon-gamma during the early phase of infection. In humans, indirect signaling through monocytes/macrophages required to optimally stimulate NK cell activity. However, the in vivo functions of NK cells during malaria are still enigmatic, and many issues remain to be dissected, such as the molecular basis of the direct recognition of iRBCs by NK cells.
Collapse
Affiliation(s)
- Sophie Roetynck
- Centre d'Immunologie de Marseille-Luminy, Université de la Méditerranée, Marseille, France
| | | | | | | | | | | |
Collapse
|
390
|
Abstract
Severe falciparum malaria is an acute systemic disease that can affect multiple organs, including those in which few parasites are found. The acute disease bears many similarities both clinically and, potentially, mechanistically, to the systemic diseases caused by bacteria, rickettsia, and viruses. Traditionally the morbidity and mortality associated with severe malarial disease has been explained in terms of mechanical obstruction to vascular flow by adherence to endothelium (termed sequestration) of erythrocytes containing mature-stage parasites. However, over the past few decades an alternative ‘cytokine theory of disease’ has also evolved, where malarial pathology is explained in terms of a balance between the pro- and anti-inflammatory cytokines. The final common pathway for this pro-inflammatory imbalance is believed to be a limitation in the supply and mitochondrial utilisation of energy to cells. Different patterns of ensuing energy depletion (both temporal and spatial) throughout the cells in the body present as different clinical syndromes. This chapter draws attention to the over-arching position that inflammatory cytokines are beginning to occupy in the pathogenesis of acute malaria and other acute infections. The influence of inflammatory cytokines on cellular function offers a molecular framework to explain the multiple clinical syndromes that are observed during acute malarial illness, and provides a fresh avenue of investigation for adjunct therapies to ameliorate the malarial disease process.
Collapse
|
391
|
Abstract
Besides bacteriae and viruses, parasite infections can be transmitted by blood as a consequence of blood transfusion. To be transmitted by blood transfusion, parasites must: -i) circulate in the blood stream of donors, -ii) comprise of certain physical characteristics and resist processing steps leading to the preparation of labile blood products (packed red blood cells, therapeutic frozen plasma, or platelet concentrates), -iii) survive conservation; further, to generate infection in the blood receiver, such parasites must retain infectivity. In this Forum, the main characteristics of parasites-with respect to transmissibility by blood exposure-are recalled. This forum will further discuss each of these topics and try to make an issue with possible risks in transfusion, in countries that are either non-endemic for the given parasite or which can afford implementation of preventive measures.
Collapse
Affiliation(s)
- O Garraud
- Etablissement français du sang Auvergne-Loire, 25, boulevard Pasteur, 42023 Saint-Etienne-cedex, France; EA-3064, faculté de médecine, université Jean-Monnet de Saint-Etienne, France.
| |
Collapse
|
392
|
Abstract
Innate immune response against Plasmodium falciparum (Pf), a causative agent of human malaria, is the result of several thousand years of co-evolution between the parasite and his host. An early IFN-gamma production during infection is associated with a better evolution of the disease. Natural killer (NK) cells are among the first cells in peripheral blood to produce IFN-gamma in response to Pf-infected erythrocytes (Pf-E). NK cells are found in blood, in secondary lymphoid organs as well as in peripheral non-lymphoid tissues. They participate in host innate responses that occur upon viral and intracytoplasmic bacterial infections, but also during the course of tumor development and allogeneic transplantation. These lymphocytes are not only important players of innate effector responses, but also participate in the initiation and development of adaptive immune responses. In addition, direct sensing of Pf infection by NK cells induces their production of the proinflammatory chemokine IL-8, suggesting a role for NK cells in the recruitment and the activation of other cells during malaria infection. Several other cell subsets are involved in the innate immune response to Pf. Dendritic cells, macrophages, gamma delta T cells, NKT cells are able to sense the presence of the parasite. Along this line, the presence of IL-12 is necessary to NK cell IFN-gamma production and a functional cooperation takes place between macrophages and NK cells in the context of this parasitic infection. In particular, IL-18 produced by macrophages is a key factor for this NK response. However, the molecular basis of Pf-E recognition by NK cells as well as the functional role of NK cell responses during the course of the disease remain to be adressed.
Collapse
Affiliation(s)
- Sophie Roetynck
- Centre d'Immunologie de Marseille-Luminy, Inserm-CNRS, Université de la Méditerranée, Parc Scientifique et Technologique de Luminy, Case 906, 13288 Marseille Cedex 09, France
| | | | | | | |
Collapse
|
393
|
Lu Z, Serghides L, Patel SN, Degousee N, Rubin BB, Krishnegowda G, Gowda DC, Karin M, Kain KC. Disruption of JNK2 decreases the cytokine response to Plasmodium falciparum glycosylphosphatidylinositol in vitro and confers protection in a cerebral malaria model. THE JOURNAL OF IMMUNOLOGY 2006; 177:6344-52. [PMID: 17056565 DOI: 10.4049/jimmunol.177.9.6344] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Host inflammatory responses to Plasmodium falciparum GPI (pfGPI) anchors are believed to play an important role in the pathophysiology of severe malaria. However, relatively little is known about the signal transduction pathways involved in pfGPI-stimulated inflammatory response and its potential contribution to severe malaria syndromes. In this study, we investigated the role of MAPK activation in pfGPI-induced cytokine secretion and examined the role of selected MAPKs in a model of cerebral malaria in vivo. We demonstrate that ERK1/2, JNK, p38, c-Jun, and activating transcription factor-2 became phosphorylated in pfGPI-stimulated macrophages. A JNK inhibitor (1,9-pyrazoloanthrone) inhibited pfGPI-induced phosphorylation of JNK, c-Jun, and activating transcription factor-2 and significantly decreased pfGPI-induced TNF-alpha secretion. pfGPI-stimulated JNK and c-Jun phosphorylation was absent in Jnk2(-/-) macrophages but unchanged in Jnk1(-/-) and Jnk3(-/-) macrophages compared with wild-type macrophages. Jnk2(-/-) macrophages secreted significantly less TNF-alpha in response to pfGPI than macrophages from Jnk1(-/-), Jnk3(-/-), and wild-type counterparts. Furthermore, we demonstrate a role for JNK2 in mediating inflammatory responses and severe malaria in vivo. In contrast to wild-type or Jnk1(-/-) mice, Jnk2(-/-) mice had lower levels of TNF-alpha in vivo and exhibited significantly higher survival rates when challenged with Plasmodium berghei ANKA. These results provide direct evidence that pfGPI induces TNF-alpha secretion through activation of MAPK pathways, including JNK2. These results suggest that JNK2 is a potential target for therapeutic interventions in severe malaria.
Collapse
Affiliation(s)
- Ziyue Lu
- Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, University Health Network-Toronto General Hospital, 200 Elizabeth Street, Toronto, Ontario, Canada
| | | | | | | | | | | | | | | | | |
Collapse
|
394
|
Abstract
Human immunodeficiency virus (HIV) and Plasmodium parasites are pathogens that induce significant perturbation and activation of the immune system. Due to their geographical overlap, there have been concerns that co-infection with the two pathogens may be a factor in the modification of their development, and in the severity and rate of disease progression that they induce. In this article, we have reviewed some of the studies that have addressed this topic and we have tried to provide immunological mechanisms to explain these potential interactions.
Collapse
Affiliation(s)
- L Rénia
- Institut Cochin, Département d'Immunologie, 75014 Paris, France.
| | | |
Collapse
|
395
|
BERTRAND S, CRISCUOLO F, FAIVRE B, SORCI G. Immune activation increases susceptibility to oxidative tissue damage in Zebra Finches. Funct Ecol 2006. [DOI: 10.1111/j.1365-2435.2006.01191.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
396
|
Wedekind C, Walker M, Little TJ. The separate and combined effects of MHC genotype, parasite clone, and host gender on the course of malaria in mice. BMC Genet 2006; 7:55. [PMID: 17118203 PMCID: PMC1664581 DOI: 10.1186/1471-2156-7-55] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Accepted: 11/21/2006] [Indexed: 11/25/2022] Open
Abstract
Background The link between host MHC (major histocompatibility complex) genotype and malaria is largely based on correlative data with little or no experimental control of potential confounding factors. We used an experimental mouse model to test for main effects of MHC-haplotypes, MHC heterozygosity, and MHC × parasite clone interactions. We experimentally infected MHC-congenic mice (F2 segregants, homo- and heterozygotes, males and females) with one of two clones of Plasmodium chabaudi and recorded disease progression. Results We found that MHC haplotype and parasite clone each have a significant influence on the course of the disease, but there was no significant host genotype by parasite genotype interaction. We found no evidence for overdominance nor any other sort of heterozygote advantage or disadvantage. Conclusion When tested under experimental conditions, variation in the MHC can significantly influence the course of malaria. However, MHC heterozygote advantage through overdominance or dominance of resistance cannot be assumed in the case of single-strain infections. Future studies might focus on the interaction between MHC heterozygosity and multiple-clone infections.
Collapse
Affiliation(s)
- Claus Wedekind
- Department of Ecology and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, Scotland, UK
| | - Mirjam Walker
- Institute of Zoo and Wildlife Biology, 10252 Berlin, Germany
- Natural History Museum Bern, 3005 Bern, Switzerland
- ZLB Behring AG, Wankdorfstr. 10, 3022 Bern, Switzerland
| | - Tom J Little
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, Scotland, UK
| |
Collapse
|
397
|
Gazzinelli RT, Denkers EY. Protozoan encounters with Toll-like receptor signalling pathways: implications for host parasitism. Nat Rev Immunol 2006; 6:895-906. [PMID: 17110955 DOI: 10.1038/nri1978] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Toll-like receptors (TLRs) have emerged as a major receptor family involved in non-self recognition. They have a vital role in triggering innate immunity and orchestrate the acquired immune response during bacterial and viral infection. However, the role of TLRs during infection with protozoan pathogens is less clear. Nevertheless, our understanding of how these parasitic microorganisms engage the host TLR signalling system has now entered a phase of rapid expansion. This Review describes recent insights into how parasitic protozoans are sensed by TLR molecules, and how the TLR system itself can be targeted by these microbial pathogens for their own survival.
Collapse
Affiliation(s)
- Ricardo T Gazzinelli
- Department of Biochemistry and Immunology, Federal University of Minas Gerais, 31270-901 Belo Horizonte, Brazil.
| | | |
Collapse
|
398
|
Gramaglia I, Sobolewski P, Meays D, Contreras R, Nolan JP, Frangos JA, Intaglietta M, van der Heyde HC. Low nitric oxide bioavailability contributes to the genesis of experimental cerebral malaria. Nat Med 2006; 12:1417-22. [PMID: 17099710 DOI: 10.1038/nm1499] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Accepted: 10/02/2006] [Indexed: 11/09/2022]
Abstract
The role of nitric oxide (NO) in the genesis of cerebral malaria is controversial. Most investigators propose that the unfortunate consequence of the high concentrations of NO produced to kill the parasite is the development of cerebral malaria. Here we have tested this high NO bioavailability hypothesis in the setting of experimental cerebral malaria (ECM), but find instead that low NO bioavailability contributes to the genesis of ECM. Specifically, mice deficient in vascular NO synthase showed parasitemia and mortality similar to that observed in control mice. Exogenous NO did not affect parasitemia but provided marked protection against ECM; in fact, mice treated with exogenous NO were clinically indistinguishable from uninfected mice at a stage when control infected mice were moribund. Administration of exogenous NO restored NO-mediated signaling in the brain, decreased proinflammatory biomarkers in the blood, and markedly reduced vascular leak and petechial hemorrhage into the brain. Low NO bioavailability in the vasculature during ECM was caused in part by an increase in NO-scavenging free hemoglobin in the blood, by hypoargininemia, and by low blood and erythrocyte nitrite concentrations. Exogenous NO inactivated NO-scavenging free hemoglobin in the plasma and restored nitrite to concentrations observed in uninfected mice. We therefore conclude that low rather than high NO bioavailability contributes to the genesis of ECM.
Collapse
Affiliation(s)
- Irene Gramaglia
- La Jolla Bioengineering Institute, 505 Coast Boulevard, La Jolla, California 92037, USA
| | | | | | | | | | | | | | | |
Collapse
|
399
|
Keller CC, Yamo O, Ouma C, Ong'echa JM, Ounah D, Hittner JB, Vulule JM, Perkins DJ. Acquisition of hemozoin by monocytes down-regulates interleukin-12 p40 (IL-12p40) transcripts and circulating IL-12p70 through an IL-10-dependent mechanism: in vivo and in vitro findings in severe malarial anemia. Infect Immun 2006; 74:5249-60. [PMID: 16926419 PMCID: PMC1594872 DOI: 10.1128/iai.00843-06] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Severe malarial anemia (SMA) is a primary cause of morbidity and mortality in immune-naïve infants and young children residing in areas of holoendemic Plasmodium falciparum transmission. Although the immunopathogenesis of SMA is largely undefined, we have previously shown that systemic interleukin-12 (IL-12) production is suppressed during childhood blood-stage malaria. Since IL-10 and tumor necrosis factor alpha (TNF-alpha) are known to decrease IL-12 synthesis in a number of infectious diseases, altered transcriptional regulation of these inflammatory mediators was investigated as a potential mechanism for IL-12 down-regulation. Ingestion of naturally acquired malarial pigment (hemozoin [PfHz]) by monocytes promoted the overproduction of IL-10 and TNF-alpha relative to the production of IL-12, which correlated with an enhanced severity of malarial anemia. Experiments with cultured peripheral blood mononuclear cells (PBMC) and CD14(+) cells from malaria-naïve donors revealed that physiological concentrations of PfHz suppressed IL-12 and augmented IL-10 and TNF-alpha by altering the transcriptional kinetics of IL-12p40, IL-10, and TNF-alpha, respectively. IL-10 neutralizing antibodies, but not TNF-alpha antibodies, restored PfHz-induced suppression of IL-12. Blockade of IL-10 and the addition of recombinant IL-10 to cultured PBMC from children with SMA confirmed that IL-10 was responsible for malaria-induced suppression of IL-12. Taken together, these results demonstrate that PfHz-induced up-regulation of IL-10 is responsible for the suppression of IL-12 during malaria.
Collapse
Affiliation(s)
- Christopher C Keller
- University of Pittsburgh Graduate School of Public Health, Department of Infectious Diseases and Microbiology, 130 DeSoto Street, 603 Parran Hall, Pittsburgh, PA 15261, USA
| | | | | | | | | | | | | | | |
Collapse
|
400
|
Long GH, Chan BHK, Allen JE, Read AF, Graham AL. Parasite genetic diversity does not influence TNF-mediated effects on the virulence of primary rodent malaria infections. Parasitology 2006; 133:673-84. [PMID: 16978451 DOI: 10.1017/s003118200600117x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 06/17/2006] [Accepted: 06/21/2006] [Indexed: 12/20/2022]
Abstract
The pro-inflammatory cytokine tumour necrosis factor alpha (TNF-alpha) is associated with malaria virulence (disease severity) in both rodents and humans. We are interested in whether parasite genetic diversity influences TNF-mediated effects on malaria virulence. Here, primary infections with genetically distinct Plasmodium chabaudi chabaudi (P.c.c.) clones varied in the virulence and cytokine responses induced in female C57BL/6 mice. Even when parasitaemia was controlled for, a greater day 7 TNF-alpha response was induced by infection with more virulent P.c.c. clones. Since many functions of TNF-alpha are exerted through TNF receptor 1 (TNFR1), a TNFR-1 fusion protein (TNFR-Ig) was used to investigate whether TNFR1 blockade eliminated clone virulence differences. We found that TNFR-1 blockade ameliorated the weight loss but not the anaemia induced by malaria infection, regardless of P.c.c. clone. We show that distinct P.c.c. infections induced significantly different plasma interferon gamma (IFN-gamma), interleukin 6 (IL-6) and interleukin 10 (IL-10) levels. Our results demonstrate that regardless of P.c.c. genotype, blocking TNFR1 signalling protected against weight loss, but had negligible effects on both anaemia and asexual parasite kinetics. Thus, during P.c.c. infection, TNF-alpha is a key mediator of weight loss, independent of parasite load and across parasite genotypes.
Collapse
Affiliation(s)
- G H Long
- Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3JT, Scotland.
| | | | | | | | | |
Collapse
|