Parasite virulence, co-infections and cytokine balance in malaria

Gonçalves, Roberto Martins; Lima, Nathália F.; Ferreira, Marcelo Urbano

doi:10.1179/2047773214y.0000000139

Cited by 32 publications

(34 citation statements)

References 95 publications

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“…Immune responses are complex traits and vaccine development requires extensive knowledge of the processes and of the determinants that modulate immune responses in human populations. The effect of age, genetic factors, pathogen co-infection, and nutritional status have been more intensively explored and are recognized to influence anti-Plasmodium Ab responses and to have some association with malaria clinical protection [13][14][15].…”

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confidence: 99%

Pattern of antibody responses to Plasmodium falciparum antigens in individuals differentially exposed to Anopheles bites

Aka

Traoré

Sagna

et al. 2020

Malar J

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Background: In malaria-endemic areas, human populations are frequently exposed to immunomodulatory salivary components injected during mosquito blood feeding. The consequences on pathogen-specific immune responses are not well known. This study evaluated and compared the humoral responses specific to merozoite stage vaccine candidates of Plasmodium falciparum, in children differentially exposed to Anopheles bites in a natural setting. Methods:The cross-sectional study was carried out in Bouaké (Côte d'Ivoire) where entomological data and blood samples from children (0-14 years) were collected in two sites with similar malaria prevalence. Antibody (IgG, IgG1, IgG3) responses to PfAMA1 and PfMSP1 were evaluated by ELISA. Univariate and multivariate analysis were performed to assess the relationship between the immune responses to P. falciparum antigens and exposure to Anopheles bites in the total cohort and in each site, separately. The individual level of exposure to Anopheles bites was evaluated by quantifying specific IgG response to the Anopheles gSG6-P1 salivary peptide, which represents a proxy of Anopheles exposure.

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confidence: 99%

Pattern of antibody responses to Plasmodium falciparum antigens in individuals differentially exposed to Anopheles bites

Aka

Traoré

Sagna

et al. 2020

Malar J

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“…Induction of heme oxygenase-1 (HO-1) production following parasite-induced hemolysis is one of the putative mechanisms that impair neutrophil function and resistance to bacteria during acute malaria. 38 The induction of HO-1 is, indeed, essential to reduce heme-mediated tissue damage in hemolytic diseases such as malaria, but inhibits oxidative burst in granulocytes and favors bacterial survival within these cells; 3) malaria can increase the iron content in macrophages as a result of enhanced erythrophagocytosis, thus favoring the survival of iron-dependent bacteria such as non-typhi Salmonella within these cells. It can also increase the response to inflammatory stimuli from bacteria, contributing to overall disease severity 38 ; 4) accumulation of the hemozoin pigment in monocytes impairs the function of various macrophages, inhibiting expression of adhesion molecules-1, integrin CD11C, and major histocompatibility complex class II antigens and delaying differentiation into functional antigen-presenting cells and stimulatory proinflammatory cytokines and chemokines; each of these functions plays a significant role in antibacterial immunity 39 ; 5) finally, those children who are homozygous for β s -globin genes (HbSS) are common in malaria-endemic areas and are predisposed to bacterial invasive diseases.…”

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confidence: 99%

Co-circulation of Plasmodium and Bacterial DNAs in Blood of Febrile and Afebrile Children from Urban and Rural Areas in Gabon

Mourembou

Nzondo

Ndjoyi-Mbiguino

et al. 2016

The American Society of Tropical Medicine and Hygiene

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Abstract. Malaria is considered to be the most common etiology of fever in sub-Saharan Africa while bacteremias exist but are under assessed. This study aimed to assess bacteremias and malaria in children from urban and rural areas in Gabon. DNA extracts from blood samples of 410 febrile and 60 afebrile children were analyzed using quantitative polymerase chain reaction. Plasmodium spp. was the microorganism most frequently detected in febrile (78.8%, 323/410) and afebrile (13.3%, 8/60) children, (P < 0.001). DNA from one or several bacteria were detected in 15 febrile patients (3.7%) but not in the controls (P = 0.1). This DNA was more frequently detected as co-infections among febrile children tested positive for Plasmodium (4.6%, 15/323) than in those tested negative for Plasmodium (0%, 0/87; P = 0.04). The bacteria detected were Streptococcus pneumoniae 2.4% (10/410), Staphylococcus aureus 1.7% (7/410), Salmonella spp. 0.7% (3/410), Streptococcus pyogenes 0.2% (1/410) and Tropheryma whipplei 0.2% (1/410) only in febrile children. Coxiella burnetii, Borrelia spp., Bartonella spp., Leptospira spp., and Mycobacterium tuberculosis were not observed. This paper reports the first detection of bacteremia related to T. whipplei in Gabon and shows that malaria decreases in urban areas but not in rural areas. Co-infections in febrile patients are common, highlighting the need to improve fever management strategies in Gabon.

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“…Following infection, a Th1dependent immune response can develop in the mammalian host, aiding clearance of parasites via IFNc-dependent mechanisms. 14,15 IFNc production by antigen-specific CD4 + T cells during P. chabaudi chabaudi AS (PcAS) infection in mice has been reported, 16 and increased parasite growth was observed following IFNc neutralisation. 17 The relationship between IFNc production and control of parasite growth has also been reported in humans during blood stage Plasmodium falciparum (Pf) infection.…”

Section: Introductionmentioning

confidence: 99%

Rapid loss of group 1 innate lymphoid cells during blood stage Plasmodium infection

Souza-Fonseca-Guimarães

Rivera

et al. 2018

Clin & Trans Imm

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ObjectivesInnate lymphoid cells (ILCs) share many characteristics with CD4+ T cells, and group 1 ILCs share a requirement for T‐bet and the ability to produce IFNγ with T helper 1 (Th1) cells. Given this similarity, and the importance of Th1 cells for protection against intracellular protozoan parasites, we aimed to characterise the role of group 1 ILCs during Plasmodium infection.MethodsWe quantified group 1 ILCs in peripheral blood collected from subjects infected with with Plasmodium falciparum 3D7 as part of a controlled human malaria infection study, and in the liver and spleens of Pc AS‐infected mice. We used genetically‐modified mouse models, as well as cell‐depletion methods in mice to characterise the role of group 1 ILCs during Pc AS infection.ResultsIn a controlled human malaria infection study, we found that the frequencies of circulating ILC1s and NK cells decreased as infection progressed but recovered after volunteers were treated with antiparasitic drug. A similar observation was made for liver and splenic ILC1s in P. chabaudi chabaudi AS (Pc AS)‐infected mice. The decrease in mouse liver ILC1 frequencies was associated with increased apoptosis. We also identified a population of cells within the liver and spleen that expressed both ILC1 and NK cell markers, indicative of plasticity between these two cell lineages. Studies using genetic and cell‐depletion approaches indicated that group 1 ILCs have a limited role in antiparasitic immunity during Pc AS infection in mice.DiscussionOur results are consistent with a previous study indicating a limited role for natural killer (NK) cells during Plasmodium chabaudi infection in mice. Additionally, a recent study reported the redundancy of ILCs in humans with competent B and T cells. Nonetheless, our results do not rule out a role for group 1 ILCs in human malaria in endemic settings given that blood stage infection was initiated intravenously in our experimental models, and thus bypassed the liver stage of infection, which may influence the immune response during the blood stage.ConclusionOur results show that ILC1s are lost early during mouse and human malaria, and this observation may help to explain the limited role for these cells in controlling blood stage infection.

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Parasite virulence, co-infections and cytokine balance in malaria

Cited by 32 publications

References 95 publications

Pattern of antibody responses to Plasmodium falciparum antigens in individuals differentially exposed to Anopheles bites

Pattern of antibody responses to Plasmodium falciparum antigens in individuals differentially exposed to Anopheles bites

Co-circulation of Plasmodium and Bacterial DNAs in Blood of Febrile and Afebrile Children from Urban and Rural Areas in Gabon

Rapid loss of group 1 innate lymphoid cells during blood stage Plasmodium infection

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