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- Bolad, Ahmed, et al.
(författare)
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Distinct interethnic differences in IgG class/subclass and IgM antibody responses to malaria antigens but not in IgG responses to non-malarial antigens in sympatric tribes living in West Africa
- 2005
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 61:4, s. 380-386
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Tidskriftsartikel (refereegranskat)abstract
- The well-established relative resistance to malaria observed in the Fulani ascompared with other sympatric tribes in West Africa has been attributed totheir higher levels of serum immunoglobulin (Ig) G antibodies to malarialantigens. In this study, we confirm and extend the previous findings by analysesof the levels of IgM, IgG and IgG subclasses of anti-malarial antibodies inasymptomatic individuals of different sympatric tribes in Burkina Faso(Fulani/Mossi) and Mali (Fulani/Dogon). The Fulani showed significantlyhigher median concentrations of anti-malarial IgG and IgM antibodies thanthe sympatric tribes at both locations. Although the overall subclass pattern ofantibodies did not differ between the tribes, with IgG1 and IgG3 as dominant,the Fulani showed consistently significantly higher levels of these subclasses ascompared with those of the non-Fulani individuals. No significant differenceswere seen in the levels of total IgG between the tribes, but the Fulani showedsignificantly higher levels of total IgM than their neighbours in both countries.While the antibody levels to some nonmalarial antigens showed the same patternof differences seen for antibody levels to malaria antigens, no significant suchdifferences were seen with antibodies to other nonmalarial antigens. In conclusion,our results show that the Fulani in two different countries show higherlevels of anti-malarial antibodies than sympatric tribes, and this appears not tobe a reflection of a general hyper-reactivity in the Fulani.
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| 2. |
- Giha, Hayder A, et al.
(författare)
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Association of a single nucleotide polymorphism in the C-reactive protein gene (-286) with susceptibility to Plasmodium falciparum malaria
- 2010
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Ingår i: Molecular Medicine. - : Springer Science and Business Media LLC. - 1076-1551 .- 1528-3658. ; 16:1-2, s. 27-33
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Tidskriftsartikel (refereegranskat)abstract
- The role of inflammation in malaria pathogenesis is not fully understood, although C-reactive protein (CRP) may have a negative influence on host immunity to infections. An upstream polymorphism, -286 (C > T > A), in the CRP gene is known to influence CRP levels. In this study, a cohort of 192 Sudanese donors, followed for malaria infection for 9 years, had their CRP -286 gene locus genotyped by pyrosequencing. The number of malaria episodes experienced by each individual over the study period was used as an index for malaria susceptibility. The prevalence of the CRP alleles A, C and T were 21%, 52% and 27%, respectively. Importantly, the A-allele, unlike the C- and T-alleles or CRP genotypes, was significantly associated with an increased number of malaria episodes, P = 0.007. The proportion of A-allele carriers among donors not known to have had malaria during the study period was 18%, whereas it was 43% and 63% among donors who had experienced 1-4 and > or =5 malaria episodes, respectively, over the same period (P = 0.002). Furthermore, the A-allele was associated with higher parasite counts. In conclusion, the CRP -286 A-allele was associated with an increased susceptibility to uncomplicated Plasmodium falciparum malaria.
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| 3. |
- Hjorton, Karin, et al.
(författare)
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Cytokine production by activated plasmacytoid dendritic cells and natural killer cells is suppressed by an IRAK4 inhibitor
- 2018
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Ingår i: Arthritis Research & Therapy. - : Springer Science and Business Media LLC. - 1478-6362. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Background: In systemic lupus erythematosus (SLE), immune complexes (ICs) containing self-derived nucleic acids trigger the synthesis of proinflammatory cytokines by immune cells. We asked how an interleukin (IL)-1 receptor-associated kinase 4 small molecule inhibitor (IRAK4i) affects RNA-IC-induced cytokine production compared with hydroxychloroquine (HCQ).Methods: Plasmacytoid dendritic cells (pDCs) and natural killer (NK) cells were isolated from peripheral blood mononuclear cells (PBMCs) of healthy individuals. PBMCs from SLE patients and healthy individuals were depleted of monocytes. Cells were stimulated with RNA-containing IC (RNA-IC) in the presence or absence of IRAK4i I92 or HCQ, and cytokines were measured by immunoassay or flow cytometry. Transcriptome sequencing was performed on RNA-IC-stimulated pDCs from healthy individuals to assess the effect of IRAK4i and HCQ.Results: In healthy individuals, RNA-IC induced interferon (IFN)-α, tumor necrosis factor (TNF)-α, IL-6, IL-8, IFN-γ, macrophage inflammatory protein (MIP)1-α, and MIP1-β production in pDC and NK cell cocultures. IFN-α production was selective for pDCs, whereas both pDCs and NK cells produced TNF-α. IRAK4i reduced the pDC and NK cell-derived cytokine production by 74–95%. HCQ interfered with cytokine production in pDCs but not in NK cells. In monocyte-depleted PBMCs, IRAK4i blocked cytokine production more efficiently than HCQ. Following RNA-IC activation of pDCs, 975 differentially expressed genes were observed (false discovery rate (FDR) < 0.05), with many connected to cytokine pathways, cell regulation, and apoptosis. IRAK4i altered the expression of a larger number of RNA-IC-induced genes than did HCQ (492 versus 65 genes).Conclusions: The IRAK4i I92 exhibits a broader inhibitory effect than HCQ on proinflammatory pathways triggered by RNA-IC, suggesting IRAK4 inhibition as a therapeutic option in SLE.
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| 4. |
- Israelsson, Elisabeth, et al.
(författare)
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Cytokine gene haplotypes with a potential effect on susceptibility to malaria in sympatric ethnic groups in Mali
- 2011
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Ingår i: Infection, Genetics and Evolution. - : Elsevier BV. - 1567-1348 .- 1567-7257. ; 11:7, s. 1608-1615
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Tidskriftsartikel (refereegranskat)abstract
- Cytokines are important players in the immune responses, and an unbalance in pro- and anti-inflammatory cytokine responses may affect parasitemia and pathology in a Plasmodium falciparum infection. Polymorphisms in cytokine genes may affect not only the levels of the protein, but many down-stream functions, such as production of C-reactive protein and immunoglobulin isotype switching. Susceptibility to malaria has been shown to differ between individuals with different genetic backgrounds, as indicated by studies in Fulani and non-Fulani ethnic groups. The aim of this study was to investigate possible interethnic differences in totally twelve single nucleotide polymorphisms (SNPs) in the genes encoding the cytokines IL-1β, IL-6, IL-10 and TNF. These SNPs are present in the promoter region of the genes, and have previously been associated with cytokine expression and with disease outcome in malaria. The results from the present study suggest that the Fulani ethnic group has a more pro-inflammatory response, due to high frequencies of high-producing alleles of IL1β and low-producing alleles of IL10. IL-6 could potentially also contribute to the relatively lower susceptibility to malaria in the Fulani ethnic group, whereas the TNF polymorphisms analysed in this study rather seem to associate with the severity of the infection and not the susceptibility for the infection itself. We therefore suggest that the polymorphisms analysed in this study all show a potential to influence the relatively lower susceptibility to malaria seen in the Fulani ethnic group as compared to the other sympatric ethnic groups.
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| 7. |
- Israelsson, Elisabeth, 1979-
(författare)
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Host genetic factors and antibody responses with potential involvement in the susceptibility to malaria
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The relatively lower susceptibility to malaria seen in the Fulani ethnic group in Africa, as compared to other sympatric ethnic groups, has been related to genetic regulation of the immune responses. This thesis aimed to describe important pathways related to the regulation of antibodies in the immune responses during a malaria infection. Our results suggest that the higher anti-malarial immune responses seen in the Fulani are not a general hyper-responsiveness in this group, but neither a malaria specific response. Fcγ receptors are important structures in the immune responses, and polymorphisms in these genes were associated with IgG subclass levels, P. falciparum parasitemia and haemoglobin levels, suggesting that these polymorphisms may be a contributing factor to the differential susceptibility to malaria. C-reactive protein levels rise immediately in response to inflammatory stimuli, and the -286 CRP polymorphism was indicated to influence parasite levels, suggesting a possible involvement in the lower susceptibility to malaria seen in the Fulani ethnic group. Several cytokines are important in maintaining the optimal parasite-neutralizing milieu in the host, and we investigated polymorphisms in some of these cytokine genes, in order to establish a possible influence of these on malaria susceptibility. Several of these polymorphisms showed associations with haemoglobin levels, IgG subclass antibody levels and parasitemia, suggesting that IL-1β, IL-6, IL-10 and TNF could affect the susceptibility to malaria and the severity of the malaria infection.Taken together, these data suggest that genetic factors have the ability to affect the antibody responses, and that several pathways can be affected. Moreover, the Fulani have a genetic predisposition for a higher inflammatory response during a malaria infection, which could lower their susceptibility to the disease. However, the control measures for this inflammation still have to be established and evaluated.
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| 8. |
- Israelsson, Elisabeth, et al.
(författare)
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Marked differences in CRP genotype frequencies between the Fulani and sympatric ethnic groups in Africa
- 2009
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875. ; 8:136
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Tidskriftsartikel (refereegranskat)abstract
- Background C-reactive protein (CRP) is an acute phase protein that can activate various immune cells and bind to certain Fcγ receptors. The latter may compete with the binding of IgG antibodies to these receptors and could thereby interfere with the antigen-specific immune response. Polymorphisms in the promoter region of the CRP gene have been strongly associated with the plasma concentration of CRP. The known lower susceptibility to malaria in the Fulani ethnic group, as compared to their sympatric neighbours in Africa, has been linked to different genetic backgrounds. The present study was performed to investigate if polymorphisms in the CRP gene could contribute to the lower susceptibility to malaria seen in the Fulani ethnic group. Methods The CRP -717 T>C, -286 C>T>A, and +1444 C>T polymorphisms were analysed in asymptomatic Fulani and non-Fulani individuals from Mali and Sudan using Pyrosequencing T and TaqMan r MGB probes. Results The rare -286 A allele, previously shown to be associated with increased CRP expression and plasma levels, was shown to be more frequent in the non-Fulani ethnic groups as compared to the sympatric Fulani ethnic group both in Mali and Sudan. The common -717 T allele was more prevalent in the non-Fulani ethnic group compared to the sympatric Fulani ethnic group, but only in Mali. The parasite prevalence was increased for the -286 A allele, but not for the -717 T allele. No differences regarding genotype frequency or parasite prevalence were seen for +1444 C>T. Conclusion This study indicate that CRP may play an important role in the immune responses to malaria, and that the -286 C/T/A CRP polymorphism may be a contributing factor to the lower susceptibility to malaria seen in the Fulani.
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