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Sökning: WFRF:(Behr Charlotte)

  • Resultat 1-6 av 6
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  • Costa, Giulia, et al. (författare)
  • Control of Plasmodium falciparum erythrocytic cycle : gamma-delta T cells target the red blood cell-invasive merozoites
  • 2011
  • Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 118:26, s. 6952--6962
  • Tidskriftsartikel (refereegranskat)abstract
    • The control of Plasmodium falciparum erythrocytic parasite density is essential for protection against malaria, as it prevents pathogenesis and progression towards severe disease. P.falciparum blood-stage parasite cultures are inhibited by human Vγ9Vδ2 gamma-delta T cells, but the underlying mechanism remains poorly understood. Here, we show that both intra-erythrocytic parasites and the extracellular red blood cell-invasive merozoites specifically activate Vγ9Vδ2 T cells in a γδ T cell receptor dependent manner and trigger their degranulation. In contrast, the γδ T cell-mediated anti-parasitic activity only targets the extracellular merozoites. Using perforin-deficient and granulysin-silenced T cell lines, we demonstrate that granulysin is essential for the in vitro anti-plasmodial process, whereas perforin is dispensable. Patients infected with P.falciparum exhibited elevated granulysin plasma levels associated with high levels of granulysin-expressing Vδ2(+) T cells endowed with parasite-specific degranulation capacity. This indicates in vivo activation of Vγ9Vδ2 T cells along with granulysin triggering and discharge during primary acute falciparum malaria. Altogether, this work identifies Vγ9Vδ2 T cells as unconventional immune effectors targeting the red blood cell-invasive extracellular P.falciparum merozoites and opens novel perspectives for immune interventions harnessing the anti-parasitic activity of Vγ9Vδ2 T cells to control parasite density in malaria patients.
  • Guenot, Marianne, et al. (författare)
  • Phosphoantigen Burst upon Plasmodium falciparum Schizont Rupture Can Distantly Activate V gamma 9V delta 2 T Cells
  • 2015
  • Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 83:10, s. 3816-3824
  • Tidskriftsartikel (refereegranskat)abstract
    • Malaria induces potent activation and expansion of the V gamma 9V delta 2 subpopulation of gamma delta T cells, which inhibit the Plasmodium falciparum blood cycle through soluble cytotoxic mediators, abrogating merozoite invasion capacity. Intraerythrocytic stages efficiently trigger V gamma 9V delta 2 T-cell activation and degranulation through poorly understood mechanisms. P. falciparum blood-stage extracts are known to contain phosphoantigens able to stimulate V gamma 9V delta 2 T cells, but how these are presented by intact infected red blood cells (iRBCs) remains elusive. Here we show that, unlike activation by phosphoantigen-expressing cells, V gamma 9V delta 2 T-cell activation by intact iRBCs is independent of butyrophilin expression by the iRBC, and contact with an intact iRBC is not required. Moreover, blood-stage culture supernatants proved to be as potent activators of V gamma 9V delta 2 T cells as iRBCs. Bioactivity in the microenvironment is attributable to phosphoantigens, as it is dependent on the parasite DOXP pathway, on V gamma 9V delta 2 TCR signaling, and on butyrophilin expression by V gamma 9V delta 2 T cells. Kinetic studies showed that the phosphoantigens were released at the end of the intraerythrocytic cycle at the time of parasite egress. We document exquisite sensitivity of V gamma 9V delta 2 T cells, which respond to a few thousand parasites. These data unravel a novel framework, whereby release of phosphoantigens into the extracellular milieu by sequestered parasites likely promotes activation of distant V gamma 9V delta 2 T cells that in turn exert remote antiparasitic functions.
  • Howard, Jennifer, et al. (författare)
  • The Antigen-Presenting Potential of V gamma 9V delta 2 T Cells During Plasmodium falciparum Blood-Stage Infection
  • 2017
  • Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 215:10, s. 1569-1579
  • Tidskriftsartikel (refereegranskat)abstract
    • During Plasmodium falciparum infections, erythrocyte-stage parasites inhibit dendritic cell maturation and function, compromising effective antimalarial adaptive immunity. Human V gamma 9V delta 2 T cells can act in vitro as antigen-presenting cells (APCs) and induce alpha beta T-cell activation. However, the relevance of this activity in vivo has remained elusive. Because V gamma 9V delta 2 T cells are activated during the early immune response against P. falciparum infection, we investigated whether they could contribute to the instruction of adaptive immune responses toward malaria parasites. In P. falciparum-infected patients, V gamma 9V delta 2 T cells presented increased surface expression of APC-associated markers HLA-DR and CD86. In response to infected red blood cells in vitro, V gamma 9V delta 2 T cells upregulated surface expression of HLA-DR, HLA-ABC, CD40, CD80, CD83, and CD86, induced naive alpha beta T-cell responses, and cross-presented soluble prototypical protein to antigen-specific CD8(+) T cells. Our findings qualify V gamma 9V delta 2 T cells as alternative APCs, which could be harnessed for therapeutic interventions and vaccine design.
  • Lanktree, Matthew B., et al. (författare)
  • Meta-analysis of Dense Genecentric Association Studies Reveals Common and Uncommon Variants Associated with Height
  • 2011
  • Ingår i: American Journal of Human Genetics. - : Cell Press. - 0002-9297 .- 1537-6605. ; 88:1, s. 41443-41443
  • Tidskriftsartikel (refereegranskat)abstract
    • Height is a classic complex trait with common variants in a growing list of genes known to contribute to the phenotype. Using a genecentric genotyping array targeted toward cardiovascular-related loci, comprising 49,320 SNPs across approximately 2000 loci, we evaluated the association of common and uncommon SNPs with adult height in 114,223 individuals from 47 studies and six ethnicities. A total of 64 loci contained a SNP associated with height at array-wide significance (p < 2.4 x 10(-6)), with 42 loci surpassing the conventional genome-wide significance threshold (p < 5 x 10(-8)). Common variants with minor allele frequencies greater than 5% were observed to be associated with height in 37 previously reported loci. In individuals of European ancestry, uncommon SNPs in IL11 and SMAD3, which would not be genotyped with the use of standard genome-wide genotyping arrays, were strongly associated with height (p < 3 x 10(-11)). Conditional analysis within associated regions revealed five additional variants associated with height independent of lead SNPs within the locus, suggesting allelic heterogeneity. Although underpowered to replicate findings from individuals of European ancestry, the direction of effect of associated variants was largely consistent in African American, South Asian, and Hispanic populations. Overall, we show that dense coverage of genes for uncommon SNPs, coupled with large-scale meta-analysis, can successfully identify additional variants associated with a common complex trait.
  • Sanou, Guillaume S, et al. (författare)
  • Haematological parameters, natural regulatory CD4 + CD25 + FOXP3+ T cells and γδ T cells among two sympatric ethnic groups having different susceptibility to malaria in Burkina Faso.
  • 2012
  • Ingår i: BMC Research Notes. - : Springer Science and Business Media LLC. - 1756-0500 .- 1756-0500. ; 5, s. 76-(12 pp)
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Fulani ethnic group individuals are less susceptible than sympatric Mossi ethnic group, in term of malaria infection severity, and differ in antibody production against malaria antigens. The differences in susceptibility to malaria between Fulani and Mossi ethnic groups are thought to be regulated by different genetic backgrounds and offer the opportunity to compare haematological parameters, Tregs and γδT cell profiles in seasonal and stable malaria transmission settings in Burkina Faso. The study was conducted at two different time points i.e. during the high and low malaria transmission period.RESULTS: Two cross-sectional surveys were undertaken in adults above 20 years belonging either to the Fulani or the Mossi ethnic groups 1) at the peak of the malaria transmission season and 2) during the middle of the low malaria transmission season. Full blood counts, proportions of Tregs and γδ T cells were measured at both time-points.As previously shown the Fulani and Mossi ethnic groups showed a consistent difference in P. falciparum infection rates and parasite load. Differential white blood cell counts showed that the absolute lymphocyte counts were higher in the Mossi than in the Fulani ethnic group at both time points. While the proportion of CD4+CD25high was higher in the Fulani ethnic group at the peak of malaria transmission season (p = 0.03), no clear pattern emerged for T regulatory cells expressing FoxP3+ and CD127low. However CD3+γδ+ subpopulations were found to be higher in the Fulani compared to the Mossi ethnic group, and this difference was statistically significant at both time-points (p = 0.004 at low transmission season and p = 0.04 at peak of transmission).CONCLUSION: Our findings on regulatory T cell phenotypes suggest an interesting role for immune regulatory mechanisms in response to malaria. The study also suggests that TCRγδ + cells might contribute to the protection against malaria in the Fulani ethnic group involving their reported parasite inhibitory activities.
  • Walsh, Roddy, et al. (författare)
  • Enhancing rare variant interpretation in inherited arrhythmias through quantitative analysis of consortium disease cohorts and population controls
  • 2021
  • Ingår i: Genetics in Medicine. - : Nature Publishing Group. - 1098-3600 .- 1530-0366. ; 23:1, s. 47-58
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: Stringent variant interpretation guidelines can lead to high rates of variants of uncertain significance (VUS) for genetically heterogeneous disease like long QT syndrome (LQTS) and Brugada syndrome (BrS). Quantitative and disease-specific customization of American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines can address this false negative rate.Methods: We compared rare variant frequencies from 1847 LQTS (KCNQ1/KCNH2/SCN5A) and 3335 BrS (SCN5A) cases from the International LQTS/BrS Genetics Consortia to population-specific gnomAD data and developed disease-specific criteria for ACMG/AMP evidence classes-rarity (PM2/BS1 rules) and case enrichment of individual (PS4) and domain-specific (PM1) variants.Results: Rare SCN5A variant prevalence differed between European (20.8%) and Japanese (8.9%) BrS patients (p = 5.7 x 10(-18)) and diagnosis with spontaneous (28.7%) versus induced (15.8%) Brugada type 1 electrocardiogram (ECG) (p = 1.3 x 10(-13)). Ion channel transmembrane regions and specific N-terminus (KCNH2) and C-terminus (KCNQ1/KCNH2) domains were characterized by high enrichment of case variants and >95% probability of pathogenicity. Applying the customized rules, 17.4% of European BrS and 74.8% of European LQTS cases had (likely) pathogenic variants, compared with estimated diagnostic yields (case excess over gnomAD) of 19.2%/82.1%, reducing VUS prevalence to close to background rare variant frequency.Conclusion: Large case-control data sets enable quantitative implementation of ACMG/AMP guidelines and increased sensitivity for inherited arrhythmia genetic testing.
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  • Resultat 1-6 av 6

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