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Immunosuppression in Malaria: Do Plasmodium falciparum Parasites Hijack the Host? Pathogens 2021; 10:pathogens10101277. [PMID: 34684226 PMCID: PMC8536967 DOI: 10.3390/pathogens10101277] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 12/13/2022] Open
Abstract
Malaria reflects not only a state of immune activation, but also a state of general immune defect or immunosuppression, of complex etiology that can last longer than the actual episode. Inhabitants of malaria-endemic regions with lifelong exposure to the parasite show an exhausted or immune regulatory profile compared to non- or minimally exposed subjects. Several studies and experiments to identify and characterize the cause of this malaria-related immunosuppression have shown that malaria suppresses humoral and cellular responses to both homologous (Plasmodium) and heterologous antigens (e.g., vaccines). However, neither the underlying mechanisms nor the relative involvement of different types of immune cells in immunosuppression during malaria is well understood. Moreover, the implication of the parasite during the different stages of the modulation of immunity has not been addressed in detail. There is growing evidence of a role of immune regulators and cellular components in malaria that may lead to immunosuppression that needs further research. In this review, we summarize the current evidence on how malaria parasites may directly and indirectly induce immunosuppression and investigate the potential role of specific cell types, effector molecules and other immunoregulatory factors.
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2
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Feeney ME. The immune response to malaria in utero. Immunol Rev 2019; 293:216-229. [PMID: 31553066 DOI: 10.1111/imr.12806] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 09/03/2019] [Indexed: 12/13/2022]
Abstract
Malaria causes tremendous early childhood morbidity and mortality, providing an urgent impetus for the development of a vaccine that is effective in neonates. However, the infant immune response to malaria may be influenced by events that occur well before birth. Placental malaria infection complicates one quarter of all pregnancies in Africa and frequently results in exposure of the fetus to malaria antigens in utero, while the immune system is still developing. Some data suggest that in utero exposure to malaria may induce immunologic tolerance that interferes with the development of protective immunity during childhood. More recently, however, a growing body of evidence suggests that fetal malaria exposure can prime highly functional malaria-specific T- and B-cells, which may contribute to postnatal protection from malaria. In utero exposure to malaria also impacts the activation and maturation of fetal antigen presenting cells and innate lymphocytes, which could have implications for global immunity in the infant. Here, we review recent advances in our understanding of how various components of the fetal immune system are altered by in utero exposure to malaria, discuss factors that may tilt the critical balance between tolerance and adaptive immunity, and consider the implications of these findings for malaria prevention strategies.
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Affiliation(s)
- Margaret E Feeney
- Departments of Pediatrics and Medicine, University of California, San Francisco, San Francisco, CA, USA
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3
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Natama HM, Rovira-Vallbona E, Sorgho H, Somé MA, Traoré-Coulibaly M, Scott S, Zango SH, Sawadogo O, Zongo SC, Valéa I, Mens PF, Schallig HDFH, Kestens L, Tinto H, Rosanas-Urgell A. Additional Screening and Treatment of Malaria During Pregnancy Provides Further Protection Against Malaria and Nonmalarial Fevers During the First Year of Life. J Infect Dis 2019; 217:1967-1976. [PMID: 29659897 DOI: 10.1093/infdis/jiy140] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 03/14/2018] [Indexed: 11/14/2022] Open
Abstract
Background Although consensus exists that malaria in pregnancy (MiP) increases the risk of malaria in infancy, and eventually nonmalarial fevers (NMFs), there is a lack of conclusive evidence of benefits of MiP preventive strategies in infants. Methods In Burkina Faso, a birth cohort study was nested to a clinical trial assessing the effectiveness of a community-based scheduled screening and treatment of malaria in combination with intermittent preventive treatment with sulfadoxine-pyrimethamine (CSST/IPTp-SP) to prevent placental malaria. Clinical episodes and asymptomatic infections were monitored over 1 year of follow-up to compare the effect of CSST/IPTp-SP and standard IPTp-SP on malaria and NMFs. Results Infants born during low-transmission season from mothers receiving CSST/IPTp-SP had a 26% decreased risk of experiencing a first clinical episode (hazard ratio, 0.74 [95% confidence interval, .55-0.99]; P = .047). CSST/IPTp-SP interacted with birth season and gravidity to reduce the incidence of NMFs. No significant effects of CSST/IPTp-SP on the incidence of clinical episodes, parasite density, and Plasmodium falciparum infections were observed. Conclusions Our findings indicate that CSST/IPTp-SP strategy may provide additional protection against both malaria and NMFs in infants during the first year of life, and suggest that malaria control interventions during pregnancy could have long-term benefits in infants.
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Affiliation(s)
- Hamtandi Magloire Natama
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.,Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso.,Department of Biomedical Sciences, University of Antwerp, Belgium
| | | | - Hermann Sorgho
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | - M Athanase Somé
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | - Maminata Traoré-Coulibaly
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | - Susana Scott
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Serge Henri Zango
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso.,Centre Muraz, Bobo Dioulasso, Burkina Faso
| | - Ousséni Sawadogo
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | - Sibiri Claude Zongo
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | - Innocent Valéa
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | - Petra F Mens
- Department of Medical Microbiology, Parasitology Unit, Academic Medical Centre, Amsterdam, The Netherlands
| | - Henk D F H Schallig
- Department of Medical Microbiology, Parasitology Unit, Academic Medical Centre, Amsterdam, The Netherlands
| | - Luc Kestens
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.,Department of Biomedical Sciences, University of Antwerp, Belgium
| | - Halidou Tinto
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso.,Centre Muraz, Bobo Dioulasso, Burkina Faso
| | - Anna Rosanas-Urgell
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
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4
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Yap XZ, Lundie RJ, Beeson JG, O'Keeffe M. Dendritic Cell Responses and Function in Malaria. Front Immunol 2019; 10:357. [PMID: 30886619 PMCID: PMC6409297 DOI: 10.3389/fimmu.2019.00357] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 02/12/2019] [Indexed: 12/24/2022] Open
Abstract
Malaria remains a serious threat to global health. Sustained malaria control and, eventually, eradication will only be achieved with a broadly effective malaria vaccine. Yet a fundamental lack of knowledge about how antimalarial immunity is acquired has hindered vaccine development efforts to date. Understanding how malaria-causing parasites modulate the host immune system, specifically dendritic cells (DCs), key initiators of adaptive and vaccine antigen-based immune responses, is vital for effective vaccine design. This review comprehensively summarizes how exposure to Plasmodium spp. impacts human DC function in vivo and in vitro. We have highlighted the heterogeneity of the data observed in these studies, compared and critiqued the models used to generate our current understanding of DC function in malaria, and examined the mechanisms by which Plasmodium spp. mediate these effects. This review highlights potential research directions which could lead to improved efficacy of existing vaccines, and outlines novel targets for next-generation vaccine strategies to target malaria.
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Affiliation(s)
- Xi Zen Yap
- Burnet Institute, Melbourne, VIC, Australia.,Department of Medicine, Dentistry, and Health Sciences, The University of Melbourne, Parkville, VIC, Australia
| | - Rachel J Lundie
- Burnet Institute, Melbourne, VIC, Australia.,Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - James G Beeson
- Burnet Institute, Melbourne, VIC, Australia.,Department of Medicine, Dentistry, and Health Sciences, The University of Melbourne, Parkville, VIC, Australia.,Department of Microbiology and Central Clinical School, Monash University, Clayton, VIC, Australia
| | - Meredith O'Keeffe
- Burnet Institute, Melbourne, VIC, Australia.,Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
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Yap XZ, Lundie RJ, Feng G, Pooley J, Beeson JG, O'Keeffe M. Different Life Cycle Stages of Plasmodium falciparum Induce Contrasting Responses in Dendritic Cells. Front Immunol 2019; 10:32. [PMID: 30766530 PMCID: PMC6365426 DOI: 10.3389/fimmu.2019.00032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/08/2019] [Indexed: 12/02/2022] Open
Abstract
Dendritic cells are key linkers of innate and adaptive immunity. Efficient dendritic cell activation is central to the acquisition of immunity and the efficacy of vaccines. Understanding how dendritic cells are affected by Plasmodium falciparum blood-stage parasites will help to understand how immunity is acquired and maintained, and how vaccine responses may be impacted by malaria infection or exposure. This study investigates the response of dendritic cells to two different life stages of the malaria parasite, parasitized red blood cells and merozoites, using a murine model. We demonstrate that the dendritic cell responses to merozoites are robust whereas dendritic cell activation, particularly CD40 and pro-inflammatory cytokine expression, is compromised in the presence of freshly isolated parasitized red blood cells. The mechanism of dendritic cell suppression by parasitized red blood cells is host red cell membrane-independent. Furthermore, we show that cryopreserved parasitized red blood cells have a substantially reduced capacity for dendritic cell activation.
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Affiliation(s)
- Xi Zen Yap
- Burnet Institute, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia
| | - Rachel J Lundie
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Gaoqian Feng
- Burnet Institute, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia
| | - Joanne Pooley
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - James G Beeson
- Burnet Institute, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia.,Department of Microbiology, Monash University, Clayton, VIC, Australia.,Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Meredith O'Keeffe
- Burnet Institute, Melbourne, VIC, Australia.,Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
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Abstract
Malaria in pregnancy not only exerts profound negative consequences on the health of the mother and developing fetus, but may also alter the risk of malaria during infancy. Although mechanisms driving this altered risk remain unclear, in utero exposure to malaria antigens may impact the development of fetal and infant innate immunity. In an article in BMC Medicine, Natama et al. describe an ambitious analysis of basal and TLR-stimulated cord blood responses among a birth cohort in Burkina Faso. Basal levels of several cytokines, chemokines, and growth factors were shown to be significantly lower in cord blood with histopathologic evidence of placental malaria. Additionally, following TLR7/8 stimulation, samples obtained from infants of mothers with placental malaria were hyper-responsive compared to those without evidence of prenatal malaria exposure. Furthermore, several responses impacted by placental malaria were associated with differential malaria risk in infancy. Understanding how malaria in pregnancy shapes immune responses in infants will provide critical insight into the rational design of malaria control strategies during pregnancy, including intermittent preventative treatment in pregnancy and vaccines.Please see related article: https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-018-1187-3.
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7
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Natama HM, Moncunill G, Rovira-Vallbona E, Sanz H, Sorgho H, Aguilar R, Coulibaly-Traoré M, Somé MA, Scott S, Valéa I, Mens PF, Schallig HDFH, Kestens L, Tinto H, Dobaño C, Rosanas-Urgell A. Modulation of innate immune responses at birth by prenatal malaria exposure and association with malaria risk during the first year of life. BMC Med 2018; 16:198. [PMID: 30384846 PMCID: PMC6214168 DOI: 10.1186/s12916-018-1187-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 10/05/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Factors driving inter-individual differences in immune responses upon different types of prenatal malaria exposure (PME) and subsequent risk of malaria in infancy remain poorly understood. In this study, we examined the impact of four types of PME (i.e., maternal peripheral infection and placental acute, chronic, and past infections) on both spontaneous and toll-like receptors (TLRs)-mediated cytokine production in cord blood and how these innate immune responses modulate the risk of malaria during the first year of life. METHODS We conducted a birth cohort study of 313 mother-child pairs nested within the COSMIC clinical trial (NCT01941264), which was assessing malaria preventive interventions during pregnancy in Burkina Faso. Malaria infections during pregnancy and infants' clinical malaria episodes detected during the first year of life were recorded. Supernatant concentrations of 30 cytokines, chemokines, and growth factors induced by stimulation of cord blood with agonists of TLRs 3, 7/8, and 9 were measured by quantitative suspension array technology. Crude concentrations and ratios of TLR-mediated cytokine responses relative to background control were analyzed. RESULTS Spontaneous production of innate immune biomarkers was significantly reduced in cord blood of infants exposed to malaria, with variation among PME groups, as compared to those from the non-exposed control group. However, following TLR7/8 stimulation, which showed higher induction of cytokines/chemokines/growth factors than TLRs 3 and 9, cord blood cells of infants with evidence of past placental malaria were hyper-responsive in comparison to those of infants not-exposed. In addition, certain biomarkers, which levels were significantly modified depending on the PME category, were independent predictors of either malaria risk (GM-CSF TLR7/8 crude) or protection (IL-12 TLR7/8 ratio and IP-10 TLR3 crude, IL-1RA TLR7/8 ratio) during the first year of life. CONCLUSIONS These findings indicate that past placental malaria has a profound effect on fetal immune system and that the differential alterations of innate immune responses by PME categories might drive heterogeneity between individuals to clinical malaria susceptibility during the first year of life.
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Affiliation(s)
- Hamtandi Magloire Natama
- Department of Biomedical Sciences, Institute of Tropical Medicine, B 2000, Antwerp, Belgium.,Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, BP218, Nanoro, Burkina Faso.,Department of Biomedical Sciences, University of Antwerp, B 2610, Antwerp, Belgium
| | - Gemma Moncunill
- Barcelona Institute for Global Health (ISGlobal), Hospital Clinic - Universitat de Barcelona, Carrer Rossello 132, E-08036, Barcelona, Catalonia, Spain
| | - Eduard Rovira-Vallbona
- Department of Biomedical Sciences, Institute of Tropical Medicine, B 2000, Antwerp, Belgium
| | - Héctor Sanz
- Barcelona Institute for Global Health (ISGlobal), Hospital Clinic - Universitat de Barcelona, Carrer Rossello 132, E-08036, Barcelona, Catalonia, Spain
| | - Hermann Sorgho
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, BP218, Nanoro, Burkina Faso
| | - Ruth Aguilar
- Barcelona Institute for Global Health (ISGlobal), Hospital Clinic - Universitat de Barcelona, Carrer Rossello 132, E-08036, Barcelona, Catalonia, Spain
| | - Maminata Coulibaly-Traoré
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, BP218, Nanoro, Burkina Faso
| | - M Athanase Somé
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, BP218, Nanoro, Burkina Faso
| | - Susana Scott
- Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, WC1E7HT, UK
| | - Innocent Valéa
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, BP218, Nanoro, Burkina Faso
| | - Petra F Mens
- Department of Medical Microbiology - Parasitology Unit, Academic Medical Centre, Amsterdam, 1105, AZ, The Netherlands
| | - Henk D F H Schallig
- Department of Medical Microbiology - Parasitology Unit, Academic Medical Centre, Amsterdam, 1105, AZ, The Netherlands
| | - Luc Kestens
- Department of Biomedical Sciences, Institute of Tropical Medicine, B 2000, Antwerp, Belgium.,Department of Biomedical Sciences, University of Antwerp, B 2610, Antwerp, Belgium
| | - Halidou Tinto
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, BP218, Nanoro, Burkina Faso.,Centre Muraz, BP390, Bobo Dioulasso, Burkina Faso
| | - Carlota Dobaño
- Barcelona Institute for Global Health (ISGlobal), Hospital Clinic - Universitat de Barcelona, Carrer Rossello 132, E-08036, Barcelona, Catalonia, Spain
| | - Anna Rosanas-Urgell
- Department of Biomedical Sciences, Institute of Tropical Medicine, B 2000, Antwerp, Belgium.
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Harrington WE, Kakuru A, Jagannathan P. Malaria in pregnancy shapes the development of foetal and infant immunity. Parasite Immunol 2018; 41:e12573. [PMID: 30019470 DOI: 10.1111/pim.12573] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 05/21/2018] [Accepted: 07/10/2018] [Indexed: 12/11/2022]
Abstract
Malaria, particularly Plasmodium falciparum, continues to disproportionately affect pregnant women. In addition to the profoundly deleterious impact of maternal malaria on the health of the mother and foetus, malaria infection in pregnancy has been shown to affect the development of the foetal and infant immune system and may alter the risk of malaria and nonmalarial outcomes during infancy. This review summarizes our current understanding of how malaria infection in pregnancy shapes the protective components of the maternal immune system transferred to the foetus and how foetal exposure to parasite antigens impacts the development of foetal and infant immunity. It also reviews existing evidence linking malaria infection in pregnancy to malaria and nonmalarial outcomes in infancy and how preventing malaria in pregnancy may alter these outcomes. A better understanding of the consequences of malaria infection in pregnancy on the development of foetal and infant immunity will inform control strategies, including intermittent preventive treatment in pregnancy and vaccine development.
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Affiliation(s)
- Whitney E Harrington
- Department of Pediatrics, University of Washington/Seattle Children's Hospital, Seattle, Washington
| | - Abel Kakuru
- Infectious Diseases Research Collaboration, Kampala, Uganda
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Timing of in utero malaria exposure influences fetal CD4 T cell regulatory versus effector differentiation. Malar J 2016; 15:497. [PMID: 27717402 PMCID: PMC5055709 DOI: 10.1186/s12936-016-1545-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Accepted: 10/04/2016] [Indexed: 11/26/2022] Open
Abstract
Background In malaria-endemic areas, the first exposure to malaria antigens often occurs in utero when the fetal immune system is poised towards the development of tolerance. Children exposed to placental malaria have an increased risk of clinical malaria in the first few years of life compared to unexposed children. Recent work has suggested the potential of pregnancy-associated malaria to induce immune tolerance in children living in malaria-endemic areas. A study was completed to evaluate the effect of malaria exposure during pregnancy on fetal immune tolerance and effector responses. Methods Using cord blood samples from a cohort of mother-infant pairs followed from early in pregnancy until delivery, flow cytometry analysis was completed to assess the relationship between pregnancy-associated malaria and fetal cord blood CD4 and dendritic cell phenotypes. Results Cord blood FoxP3+ Treg counts were higher in infants born to mothers with Plasmodium parasitaemia early in pregnancy (12–20 weeks of gestation; p = 0.048), but there was no association between Treg counts and the presence of parasites in the placenta at the time of delivery (by loop-mediated isothermal amplification (LAMP); p = 0.810). In contrast, higher frequencies of activated CD4 T cells (CD25+FoxP3−CD127+) were observed in the cord blood of neonates with active placental Plasmodium infection at the time of delivery (p = 0.035). This population exhibited evidence of effector memory differentiation, suggesting priming of effector T cells in utero. Lastly, myeloid dendritic cells were higher in the cord blood of infants with histopathologic evidence of placental malaria (p < 0.0001). Conclusion Together, these data indicate that in utero exposure to malaria drives expansion of both regulatory and effector T cells in the fetus, and that the timing of this exposure has a pivotal role in determining the polarization of the fetal immune response.
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Ateba-Ngoa U, Mombo-Ngoma G, Zettlmeissl E, van der Vlugt LEPM, de Jong S, Matsiegui PB, Ramharter M, Kremsner PG, Yazdanbakhsh M, Adegnika AA. CD4+CD25hiFOXP3+ cells in cord blood of neonates born from filaria infected mother are negatively associated with CD4+Tbet+ and CD4+RORγt+ T cells. PLoS One 2014; 9:e114630. [PMID: 25531674 PMCID: PMC4273973 DOI: 10.1371/journal.pone.0114630] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 11/11/2014] [Indexed: 11/18/2022] Open
Abstract
Background Children who have been exposed in utero to maternal filarial infection are immunologically less responsive to filarial antigens, have less pathology, and are more susceptible to acquire infection than offspring of uninfected mothers. Moreover children from filaria infected mothers have been shown to be less responsive to vaccination as a consequence of an impairment of their immune response. However, it is not well known how in utero exposure to parasite antigens affects cellular immune responses. Methodology Here, 30 pregnant women were examined for the presence of microfilaria of Loa loa and Mansonella perstans in peripheral blood. At delivery, cord blood mononuclear cells (CBMC) were obtained and the CD4+T cells were phenotyped by expression of the transcription factors Tbet, RORγt, and FOXP3. Results No significant difference was observed between newborns from infected versus uninfected mothers in the frequencies of total CD4+T cells and CD4+T cells subsets including CD4+Tbet+, CD4+RORγt+ T and CD4+CD25hiFOXP3+ T cells. However, there was a negative association between CD4+CD25hiFOXP3+T cells and CD4+Tbet+ as well as CD4+RORγt+ T cells in the infected group only (B = −0.242, P = 0.002; B = −0.178, P = 0.013 respectively). Conclusion Our results suggest that filarial infection during pregnancy leads to an expansion of functionally active regulatory T cells that keep TH1 and TH17 in check.
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Affiliation(s)
- Ulysse Ateba-Ngoa
- Centre de Recherches Médicales de Lambaréné, BP 118, Lambaréné, Gabon
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2 2333 ZA Leiden, The Netherlands
- Institut für Tropenmedizin, Universität Tübingen, Wilhelmstraβe 27 D-72074 Tübingen, Germany
| | - Ghyslain Mombo-Ngoma
- Centre de Recherches Médicales de Lambaréné, BP 118, Lambaréné, Gabon
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2 2333 ZA Leiden, The Netherlands
- Institut für Tropenmedizin, Universität Tübingen, Wilhelmstraβe 27 D-72074 Tübingen, Germany
- Département de Parasitologie-Mycologie, Université des Sciences de la Santé, BP 4009, Libreville, Gabon
| | - Eva Zettlmeissl
- Institut für Tropenmedizin, Universität Tübingen, Wilhelmstraβe 27 D-72074 Tübingen, Germany
| | | | - Sanne de Jong
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2 2333 ZA Leiden, The Netherlands
| | - Pierre-Blaise Matsiegui
- Centre de Recherches Médicales de Lambaréné, BP 118, Lambaréné, Gabon
- Centre de Recherches Médicales de la Ngounié, Fougamou, Gabon
| | - Michael Ramharter
- Centre de Recherches Médicales de Lambaréné, BP 118, Lambaréné, Gabon
- Institut für Tropenmedizin, Universität Tübingen, Wilhelmstraβe 27 D-72074 Tübingen, Germany
- Department of Medicine I, Division of Infectious Diseases and Tropical Medicine, Medical University of Vienna, Währinger Gürtel 18–20, 1090 Vienna, Austria
| | - Peter G. Kremsner
- Centre de Recherches Médicales de Lambaréné, BP 118, Lambaréné, Gabon
- Institut für Tropenmedizin, Universität Tübingen, Wilhelmstraβe 27 D-72074 Tübingen, Germany
| | - Maria Yazdanbakhsh
- Centre de Recherches Médicales de Lambaréné, BP 118, Lambaréné, Gabon
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2 2333 ZA Leiden, The Netherlands
| | - Ayola Akim Adegnika
- Centre de Recherches Médicales de Lambaréné, BP 118, Lambaréné, Gabon
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2 2333 ZA Leiden, The Netherlands
- Institut für Tropenmedizin, Universität Tübingen, Wilhelmstraβe 27 D-72074 Tübingen, Germany
- * E-mail:
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11
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Malaria modifies neonatal and early-life toll-like receptor cytokine responses. Infect Immun 2013; 81:2686-96. [PMID: 23690399 DOI: 10.1128/iai.00237-13] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Protection from infections in early life relies extensively on innate immunity, but it is unknown whether and how maternal infections modulate infants' innate immune responses, thereby altering susceptibility to infections. Plasmodium falciparum causes pregnancy-associated malaria (PAM), and epidemiological studies have shown that PAM enhances infants' susceptibility to infection with P. falciparum. We investigated how PAM-mediated exposures in utero affect innate immune responses and their relationship with infection in infancy. In a prospective study of mothers and their babies in Benin, we investigated changes in Toll-like receptor (TLR)-mediated cytokine responses related to P. falciparum infections. Whole-blood samples from 134 infants at birth and at 3, 6, and 12 months of age were stimulated with agonists specific for TLR3, TLR4, TLR7/8, and TLR9. TLR-mediated interleukin 6 (IL-6) and IL-10 production was robust at birth and then stabilized, whereas tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ) responses were weak at birth and then increased. In multivariate analyses, maternal P. falciparum infections at delivery were associated with significantly higher TLR3-mediated IL-6 and IL-10 responses in the first 3 months of life (P < 0.05) and with significantly higher TLR3-, TLR7/8-, and TLR9-mediated TNF-α responses between 6 and 12 months of age (P < 0.05). Prospective analyses showed that higher TLR3- and TLR7/8-mediated IL-10 responses at birth were associated with a significantly higher risk of P. falciparum infection in infancy (P < 0.05). Neonatal and infant intracellular TLR-mediated cytokine responses are conditioned by in utero exposure through PAM late in pregnancy. Enhanced TLR-mediated IL-10 responses at birth are associated with an increased risk of P. falciparum infection, suggesting a compromised ability to combat infection in early life.
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12
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Donkor ON, Ravikumar M, Proudfoot O, Day SL, Apostolopoulos V, Paukovics G, Vasiljevic T, Nutt SL, Gill H. Cytokine profile and induction of T helper type 17 and regulatory T cells by human peripheral mononuclear cells after microbial exposure. Clin Exp Immunol 2012; 167:282-95. [PMID: 22236005 DOI: 10.1111/j.1365-2249.2011.04496.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The immunomodulatory effects of probiotics were assessed following exposure of normal peripheral blood mononuclear cells (PBMC), cord blood cells and the spleen-derived monocyte/macrophage cell line CRL-9850 to Lactobacillus acidophilus LAVRI-A1, Lb. rhamnosus GG, exopolysaccharides (EPS)-producing Streptococcus thermophilus St1275, Bifidobacteriun longum BL536, B. lactis B94 and Escherichia coli TG1 strains. The production of a panel of pro- and anti-inflammatory cytokines by PBMC following bacterial stimulation was measured, using live, heat-killed or mock gastrointestinal tract (GIT)-exposed bacteria, and results show that (i) all bacterial strains investigated induced significant secretion of pro- and anti-inflammatory cytokines from PBMC-derived monocytes/macrophages; and (ii) cytokine levels increased relative to the expansion of bacterial cell numbers over time for cells exposed to live cultures. Bifidobacteria and S. thermophilus stimulated significant concentrations of transforming growth factor (TGF)-β, an interleukin necessary for the differentiation of regulatory T cells (T(reg) )/T helper type 17 (Th17) cells and, as such, the study further examined the induction of Th17 and T(reg) cells after PBMC exposure to selected bacteria for 96 h. Data show a significant increase in the numbers of both cell types in the exposed populations, measured by cell surface marker expression and by cytokine production. Probiotics have been shown to induce cytokines from a range of immune cells following ingestion of these organisms. These studies suggest that probiotics' interaction with immune-competent cells produces a cytokine milieu, exerting immunomodulatory effects on local effector cells, as well as potently inducing differentiation of Th17 and T(reg) cells.
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Affiliation(s)
- O N Donkor
- School of Biomedical and Health Sciences, Victoria University, Werribee Campus, Werribee, Vic, Australia.
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Quelhas D, Puyol L, Quintó L, Nhampossa T, Serra-Casas E, Macete E, Aide P, Sanz S, Aponte JJ, Doolan DL, Alonso PL, Menéndez C, Dobaño C. Intermittent preventive treatment with sulfadoxine-pyrimethamine does not modify plasma cytokines and chemokines or intracellular cytokine responses to Plasmodium falciparum in Mozambican children. BMC Immunol 2012; 13:5. [PMID: 22280502 PMCID: PMC3398260 DOI: 10.1186/1471-2172-13-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 01/26/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cytokines and chemokines are key mediators of anti-malarial immunity. We evaluated whether Intermittent Preventive Treatment in infants with Sulfadoxine-Pyrimethamine (IPTi-SP) had an effect on the acquisition of these cellular immune responses in Mozambican children. Multiple cytokines and chemokines were quantified in plasma by luminex, and antigen-specific cytokine production in whole blood was determined by intracellular cytokine staining and flow cytometry, at ages 5, 9, 12 and 24 months. RESULTS IPTi-SP did not significantly affect the proportion of CD3+ cells producing IFN-γ, IL-4 or IL-10. Overall, plasma cytokine or chemokine concentrations did not differ between treatment groups. Th1 and pro-inflammatory responses were higher than Th2 and anti-inflammatory responses, respectively, and IFN-γ:IL-4 ratios were higher for placebo than for SP recipients. Levels of cytokines and chemokines varied according to age, declining from 5 to 9 months. Plasma concentrations of IL-10, IL-12 and IL-13 were associated with current infection or prior malaria episodes. Higher frequencies of IFN-γ and IL-10 producing CD3+ cells and elevated IL-10, IFN-γ, MCP-1 and IL-13 in plasma were individually associated with increased malaria incidence, at different time points. When all markers were analyzed together, only higher IL-17 at 12 months was associated with lower incidence of malaria up to 24 months. CONCLUSIONS Our work has confirmed that IPTi-SP does not negatively affect the development of cellular immune response during early childhood. This study has also provided new insights as to how these cytokine responses are acquired upon age and exposure to P. falciparum, as well as their associations with malaria susceptibility. TRIAL REGISTRATION ClinicalTrials.gov: NCT00209795.
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Affiliation(s)
- Diana Quelhas
- Centro de Investigação em Saúde da Manhiça, Manhiça, Mozambique
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Hodyl NA, Stark MJ, Osei-Kumah A, Clifton VL. Prenatal programming of the innate immune response following in utero exposure to inflammation: a sexually dimorphic process? Expert Rev Clin Immunol 2011; 7:579-92. [PMID: 21895471 DOI: 10.1586/eci.11.51] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Maternal infection and inflammation are common events during pregnancy. This article documents evidence that suggests such inflammation compromises the development of the fetal innate immune response, in support of an in utero origins hypothesis of neonatal and childhood inflammatory disease. The potential for this response to exhibit sex specificity is also explored, based on evidence of sexually dimorphic placental responses to maternal inflammation.
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Affiliation(s)
- Nicolette A Hodyl
- The Robinson Institute, Obstetrics and Gynaecology, University of Adelaide, Adelaide, Australia
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Köhler C, Adegnika AA, van der Linden R, Luty AJF, Kremsner PG. Phenotypic characterization of mononuclear blood cells from pregnant Gabonese and their newborns. Trop Med Int Health 2011; 16:1061-9. [DOI: 10.1111/j.1365-3156.2011.02812.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Lisciandro JG, van den Biggelaar AHJ. Neonatal immune function and inflammatory illnesses in later life: lessons to be learnt from the developing world? Clin Exp Allergy 2010; 40:1719-31. [PMID: 20964742 DOI: 10.1111/j.1365-2222.2010.03629.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
With the emergence of allergic and autoimmune diseases in populations that have started to transit to a western lifestyle, there has been an increasing interest in the role of environmental factors modulating early immune function. Yet, most of the information concerning neonatal immune function has been derived from studies in westernized countries. We postulate that comparative studies of early immune development in children born under conditions that are typical for a westernized vs. that of a still more traditional setting will provide a crucial insight into the environmental-driven immunological mechanisms that are responsible for the world-wide rise in inflammatory disorders. In this review, we summarize the current understanding of early-life immune function in humans in general and the literature on some major lifestyle factors that may influence neonatal immune function and potentially the risk for disease in later life. An understanding of the mechanisms of 'prenatal/early-life programming' in populations living in traditional compared with modern societies is crucial to develop strategies to prevent a further rise in 'western diseases' such as allergic disorders. Indications exist that prenatal conditioning of the innate immune system by low-grade inflammatory responses is key to inducing more tightly regulated postnatal adaptive immune responses.
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Affiliation(s)
- J G Lisciandro
- Centre for Child Health Research, Telethon Institute for Child Health Research, The University of Western Australia, Perth, Australia.
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CD4+ CD25+ Foxp3+ regulatory T cells, dendritic cells, and circulating cytokines in uncomplicated malaria: do different parasite species elicit similar host responses? Infect Immun 2010; 78:4763-72. [PMID: 20713627 DOI: 10.1128/iai.00578-10] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Clearing blood-stage malaria parasites without inducing major host pathology requires a finely tuned balance between pro- and anti-inflammatory responses. The interplay between regulatory T (Treg) cells and dendritic cells (DCs) is one of the key determinants of this balance. Although experimental models have revealed various patterns of Treg cell expansion, DC maturation, and cytokine production according to the infecting malaria parasite species, no studies have compared all of these parameters in human infections with Plasmodium falciparum and P. vivax in the same setting of endemicity. Here we show that during uncomplicated acute malaria, both species induced a significant expansion of CD4(+) CD25(+) Foxp3(+) Treg cells expressing the key immunomodulatory molecule CTLA-4 and a significant increase in the proportion of DCs that were plasmacytoid (CD123(+)), with a decrease in the myeloid/plasmacytoid DC ratio. These changes were proportional to parasite loads but correlated neither with the intensity of clinical symptoms nor with circulating cytokine levels. One-third of P. vivax-infected patients, but no P. falciparum-infected subjects, showed impaired maturation of circulating DCs, with low surface expression of CD86. Although vivax malaria patients overall had a less inflammatory cytokine response, with a higher interleukin-10 (IL-10)/tumor necrosis factor alpha (TNF-α) ratio, this finding did not translate to milder clinical manifestations than those of falciparum malaria patients. We discuss the potential implications of these findings for species-specific pathogenesis and long-lasting protective immunity to malaria.
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Fievet N, Varani S, Ibitokou S, Briand V, Louis S, Perrin RX, Massougbogji A, Hosmalin A, Troye-Blomberg M, Deloron P. Plasmodium falciparum exposure in utero, maternal age and parity influence the innate activation of foetal antigen presenting cells. Malar J 2009; 8:251. [PMID: 19889240 PMCID: PMC2780449 DOI: 10.1186/1475-2875-8-251] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Accepted: 11/05/2009] [Indexed: 12/14/2022] Open
Abstract
Background Malaria in pregnancy is associated with immunological abnormalities in the newborns, such as hampered T-helper 1 responses and increased T-regulatory responses, while the effect of maternal Plasmodium falciparum infection on foetal innate immunity is still controversial. Materials and methods The immunophenotype and cytokine release by dendritic cells (DC) and monocytes were evaluated in cord blood from 59 Beninese women with or without malaria infection by using flow cytometry. Results Accumulation of malaria pigment in placenta was associated with a partial maturation of cord blood myeloid and plasmacytoid DC, as reflected by an up-regulated expression of the major histocompatibility complex class II molecules, but not CD86 molecules. Cells of newborns of mothers with malaria pigment in their placenta also exhibited significantly increased cytokine responses upon TLR9 stimulation. In addition, maternal age and parity influenced the absolute numbers and activation status of cord blood antigen-presenting cells. Lastly, maternal age, but not parity, influenced TLR3, 4 and 9 responses in cord blood cells. Discussion Our findings support the view that placental parasitization, as indicated by the presence of malaria pigment in placental leukocytes, is significantly associated with partial maturation of different DC subsets and also to slightly increased responses to TLR9 ligand in cord blood. Additionally, other factors, such as maternal age and parity should be taken into consideration when analysing foetal/neonatal innate immune responses. Conclusion These data advocate a possible mechanism by which PAM may modulate foetal/neonatal innate immunity.
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Affiliation(s)
- Nadine Fievet
- UR010, Mother and Child Health in the Tropics, Institut de Recherche pour le Développement (IRD), Cotonou, Benin
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Agrawal T, Vats V, Wallace P, Singh A, Salhan S, Mittal A. Recruitment of myeloid and plasmacytoid dendritic cells in cervical mucosa during Chlamydia trachomatis infection. Clin Microbiol Infect 2009; 15:50-9. [DOI: 10.1111/j.1469-0691.2008.02113.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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20
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Köhler C, Adegnika AA, Van der Linden R, Agnandji ST, Chai SK, Luty AJF, Szepfalusi Z, Kremsner PG, Yazdanbakhsh M. Comparison of immunological status of African and European cord blood mononuclear cells. Pediatr Res 2008; 64:631-6. [PMID: 18679157 DOI: 10.1203/pdr.0b013e31818718ba] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The cellular aspects of the immunologic development of the fetus during pregnancy have been studied mainly in populations living in economically well developed countries, and there is no data concerning variation of the neonatal cellular immune system in geographically distinct areas with different environments. Here, we report a comparative immunologic marker analysis of the circulating mononuclear cell subsets in unstimulated cord blood of newborns from Gabon and Austria, assessing the activation and maturation status of T and B lymphocytes as well as antigen-presenting cells. Cells and markers hypothesized to be modulated by frequent exposure to microorganisms and parasites such as regulatory T cells and the expression of toll-like receptor 2 on antigen-presenting cells were also studied. We found marked differences in terms of expression of immunologic markers between the two populations, pointing to a comparatively enhanced maturation status of the neonatal immune system in general in the African setting. The observations suggest that environmental factors, including differential exposure to pathogens as well as nutritional differences, may have substantial impact on the development of the fetal immune system.
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Affiliation(s)
- Carsten Köhler
- Department of Parasitology, University of Tübingen, Tübingen 72074, Germany.
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Adegnika AA, Köhler C, Agnandji ST, Chai SK, Labuda L, Breitling LP, Schonkeren D, Weerdenburg E, Issifou S, Luty AJF, Kremsner PG, Yazdanbakhsh M. Pregnancy-associated malaria affects toll-like receptor ligand-induced cytokine responses in cord blood. J Infect Dis 2008; 198:928-36. [PMID: 18684097 DOI: 10.1086/591057] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Pregnancy-associated malaria is known to modify fetal immunity. Most previous studies have been cross-sectional in nature and have focused on the priming of acquired immune responses in utero. In this context, the influence of the timing and/or duration of placental infection with Plasmodium falciparum are unknown, and changes to innate immune responses have not been studied extensively. METHODS Pregnant women in Gabon, where P. falciparum infection is endemic, were followed up through monthly clinical and parasitological examinations from the second trimester to delivery. Cells of neonates born to mothers who had acquired P. falciparum infection <or=1 month before delivery had significantly altered interferon-gamma and tumor necrosis factor-alpha responses after stimulation with the Toll-like receptor (TLR) ligands lipopolysaccharide and polyinosine-polycytidylic acid, compared with cells of neonates born either to mothers free of P. falciparum infection or to mothers who were successfully treated for malaria during pregnancy. An independent association between parity and neonatal TLR responsiveness was also discerned in our study. CONCLUSION P. falciparum infection history during pregnancy appears to have a pronounced effect on neonatal innate immune responses. The observed effects may have profound implications for the outcome of newly encountered infections in early life.
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Affiliation(s)
- Ayôla A Adegnika
- Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon.
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Schwarz NG, Adegnika AA, Breitling LP, Gabor J, Agnandji ST, Newman RD, Lell B, Issifou S, Yazdanbakhsh M, Luty AJF, Kremsner PG, Grobusch MP. Placental malaria increases malaria risk in the first 30 months of life. Clin Infect Dis 2008; 47:1017-25. [PMID: 18781874 DOI: 10.1086/591968] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Plasmodium falciparum infection during pregnancy is associated with stillbirth, fetal growth restriction, and low birth weight. An additional consequence may be increased risk of malaria in early life, although the epidemiological evidence of this consequence is limited. METHODS A cohort of 527 children were observed actively every month for 30 months after delivery. Offspring of mothers with microscopically detectable placental P. falciparum infection at the time of delivery were defined as exposed. The outcome measure was malaria (parasitemia and fever). Analyses were performed using Cox proportional hazard models and were stratified by gravidity. RESULTS Overall, offspring of mothers with placental P. falciparum infection had a significantly higher risk of clinical malaria during the first 30 months of life (adjusted hazard ratio, 2.1; 95% confidence interval [CI], 1.2-3.7). The adjusted hazard ratio for offspring of multigravidae was 2.6 (95% CI, 1.3-5.3), and that for primigravidae was 1.5 (95% CI, 0.6-3.8). The offspring of placenta-infected primigravidae had no episodes of malaria during the first year of life. CONCLUSIONS Our findings show that active placental P. falciparum infection detected at delivery is associated with an approximately 2-fold greater risk of malaria during early life, compared with noninfection. The fact that persons born to infected multigravidae rather than primigravidae appear to be at greater risk emphasizes the importance of preventing malaria in mothers of all gravidities.
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Affiliation(s)
- Norbert G Schwarz
- Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon, South Africa
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Diallo M, Aldebert D, Moreau JC, Ndiaye M, Jambou R. Decrease of lymphoid dendritic cells in blood from malaria-infected pregnant women. Int J Parasitol 2008; 38:1557-65. [PMID: 18606411 DOI: 10.1016/j.ijpara.2008.04.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 04/23/2008] [Accepted: 04/27/2008] [Indexed: 10/22/2022]
Abstract
Activation of dendritic cells (DCs) during malaria is poorly documented and has mainly been studied in rodent models. We conducted studies in Senegal to better understand the relationship between DC subset activation and susceptibility of pregnant women to malaria. For each woman, samples were collected at delivery from peripheral (WB), placental (PB) and cord blood (CB). The ex vivo phenotypes of DCs were assessed using flow cytometry on whole blood. The percentage of total DCs was the same for malaria-infected or non-infected pregnant women, except for PB where a decrease in DCs was observed during infection. Lymphoid dendritic cells (LDC) also decreased in the three blood compartments of infected pregnant women and less differentiated DCs (ldDCs) increased. During infection, Human Leucocyte Antigen DR (HLA-DR) expression decreased on LDCs, myeloid DCs (MDCs) and ldDCs. IL-10 increased in the three blood compartments. These data demonstrate a modulation of DC sub-populations during placental malaria. A decrease in LDCs during placental malaria could trigger major alterations in the immune response and a change in the Th1/Th2 balance. However, elevated IL-10 observed during infection substantiates a normal micro-environment triggering normal production of DCs. The decrease in LDCs could thus be due to their migration towards spleen or other lymphoid organs.
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Affiliation(s)
- Mamadou Diallo
- Department of Clinical and Parasite Immunology, Institut Pasteur, Dakar, Senegal
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Broen K, Brustoski K, Engelmann I, Luty AJF. Placental Plasmodium falciparum infection: causes and consequences of in utero sensitization to parasite antigens. Mol Biochem Parasitol 2006; 151:1-8. [PMID: 17081634 DOI: 10.1016/j.molbiopara.2006.10.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Accepted: 10/02/2006] [Indexed: 11/26/2022]
Abstract
Available evidence suggests that, in African populations, systemic blood-dwelling parasitoses of mothers are associated with enhanced susceptibility to infection of their offspring. Thus, children born to mothers with filariasis or schistosomiasis are infected earlier, and offspring of mothers with placental Plasmodium falciparum at delivery, commonly referred to as pregnancy-associated malaria or PAM, are themselves at higher risk of developing parasitaemia during infancy. Since foetal/neonatal antigen-presenting cells (APC) are either immature or provide insufficient costimulatory signals to T cells, thus favouring tolerance induction, it is commonly assumed that soluble parasite components [protein antigens], transferred transplacentally and inducing foetal immune tolerance, are largely, if not exclusively, responsible for these outcomes. Plasmodial asexual blood stage antigen-specific T cells are detectable in as many as two-thirds of all cord blood samples in malaria-endemic countries of sub-Saharan Africa, indicating that in utero sensitization may be a common phenomenon during pregnancy in these populations. Parasite antigen-specific T cell responses of neonates born to helminth-infected mothers display a highly skewed Th2-type cytokine pattern, with a prominent role for the regulatory cytokine interleukin (IL)-10. Similarly, the cord blood immune response of those born to mothers identified with on-going PAM is characterised by inducible parasite antigen-specific IL-10-producing regulatory T cells that can inhibit both APC HLA expression and Th1-type T cell responses. In contrast, plasmodial antigen-specific Th1-type responses, characterised by IFN-gamma production, predominate in cord blood of those born to mothers successfully treated for Pf malaria during gestation, suggesting that the duration and/or the nature of antigen exposure in utero governs the outcome with respect to neonatal immune responses. Aspects of APC function in the context of these differentially modulated responses, whether and how the latter translate into altered susceptibility to Pf infection during infancy, as well as the possible implications for vaccination in early life, are aspects that are discussed in this review.
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Affiliation(s)
- Kelly Broen
- Department of Medical Microbiology 268, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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