Distribution of Knop blood group antigens and association of Triggering receptor expressed on myeloid cells 1 (TREM-1) gene variants in Ghanaian children with malaria

Distribution of Knop blood group antigens and association of Triggering receptor expressed on myeloid cells 1 (TREM-1) gene variants in Ghanaian children with malaria Durch die Konfrontation mit verschieden Pathogenen unterliegt das menschliche Immunsystem einer stetigen Weiterentwicklung, dabei ist die angeborene Immunantwort der initiale Abwehrmechanismus gegen alle Erreger. In dieser Dissertation habe ich Proben aus Ghana, ein Malaria-endemisches Land, benutzt. Die Host-angeborenen Immunfaktoren werden untersucht, die möglicherweise die Malaria-Anfälligkeit verändern könnten. Meine Untersuchungen sind in zwei unabhängige Kapitel gegliedert, die als wissenschaftliche Artikel veröffentlicht wurden. Im ersten Kapitel meiner Dissertation habe ich die Verteilung der Knops-Blutgruppenantigene auf dem Komplementrezeptor 1 (CR1, CD35) in der ghanaischen Bevölkerung untersucht und diese Verteilung mit anderen Weltpopulationen verglichen, welche nicht in Malaria endemischen Gebieten leben. Die Verteilung der CR1-Allele, Genotypen und Haplotypen unterscheiden sich signifikant unter den verschiedenen geographischen Standpunkten und bestimmte CR1-genetische Varianten waren in afrikanischen Populationen spezifischer, was auf einen potentiellem durch den Malariaparasiten ausgelösten, Selektionsdruck hindeuten kann. Im zweiten Kapitel meiner Arbeit konzentrietre ich mich auf die fragetsellung, ob es einen Zusammenhang zwischen genvarianten des angeborenen Immunsystems und Zytokinen in einer klinisch klassifizierten Malaria-Kohorte gibt. Insbesondere wurden die Untersuchungen durchgeführt, um die Rolle der auslösenden/triggernden Rezeptoren (TREM)-1 und TREM-artigem (TLT-1), welche auf myleoiden Zellen exprimiert werden, des endothelialen Protein C-Rezeptors und der Interleukine (IL)-8 und IL-18 Varianten, auf den Ausgang einer Malariaerkrankung, zu analysieren.. Bei Kindern mit schwerer Malaria wurden im Vergleich zu denen mit unkomplizierter Malaria höhere STREM-1-Spiegel beobachtet. Niedrige TREM-1 zu TREML-1-Verhältnisse wurden mit unkomplizierter Malaria assoziiert. Die TREM-1 rs2234237T-Variante, die den Aminosäureaustausch Thr25Ser verursacht, welche mit einem höheren TREM-1-Plasmaspiegel assoziiert wurde, war bei Patienten mit schwerer Malaria signifikant häufiger als bei Patienten mit unkomplizierter Malaria. Das Vorhandensein des TREM-1 rs2234237T-Allels, scheint ein Risikofaktor für die Entwicklung einer kompl. Malaria zu sein. Zusammenfassend, hat diese Dissertation zu einem tieferen Verständnis von Wirtsfakotren, welche eine entscheidende Rolle für die veränderte Zugänglichkeit für eine Krankheit spielen könnten, beigetragen

Fc Gamma Receptor IIIB (FcɣRIIIB) Polymorphisms Are Associated with Clinical Malaria in Ghanaian Children

The original publication is available at http://www.plosone.orgPlasmodium falciparum malaria kills nearly a million people annually. Over 90% of these deaths occur in children under five years of age in sub-Saharan Africa. A neutrophil mediated mechanism, the antibody dependent respiratory burst (ADRB), was recently shown to correlate with protection from clinical malaria. Human neutrophils constitutively express Fc gamma receptor-FcɣRIIA and FcɣRIIIB by which they interact with immunoglobulin (Ig) G (IgG)-subclass antibodies. Polymorphisms in exon 4 of FCGR2A and exon 3 of FCGR3B genes encoding FcɣRIIA and FcɣRIIIB respectively have been described to alter the affinities of both receptors for IgG. Here, associations between specific polymorphisms, encoding FcɣRIIA p.H166R and FcɣRIIIB-NA1/NA2/SH variants with clinical malaria were investigated in a longitudinal malaria cohort study. FcɣRIIA-p.166H/R was genotyped by gene specific polymerase chain reaction followed by allele specific restriction enzyme digestion. FCGR3B-exon 3 was sequenced in 585 children, aged 1 to 12 years living in a malaria endemic region of Ghana. Multivariate logistic regression analysis found no association between FcɣRIIA-166H/R polymorphism and clinical malaria. The A-allele of FCGR3B-c.233C>A (rs5030738) was significantly associated with protection from clinical malaria under two out of three genetic models (additive: p = 0.0061; recessive: p = 0.097; dominant: p = 0.0076) of inheritance. The FcɣRIIIB-SH allotype (CTGAAA) containing the 233A-allele (in bold) was associated with protection from malaria (p = 0.049). The FcɣRIIIB-NA2*03 allotype (CTGCGA), a variant of the classical FcɣRIIIB-NA2 (CTGCAA) was associated with susceptibility to clinical malaria (p = 0.0092). The present study is the first to report an association between a variant of FcɣRIIIB-NA2 and susceptibility to clinical malaria and provides justification for further functional characterization of variants of the classical FcɣRIIIB allotypes. This would be crucial to the improvement of neutrophil mediated functional assays such as the ADRB assay aimed at assessing the functionality of antibodies induced by candidate malaria vaccines.European and Developing Countries Clinical Trials Partnership (www.edctp.org) (TA.2007.40200.012)European Vaccine Initiative (www.euvaccine.eu) (08-2007)African Malaria Network Trust (www.amanet-trust.org) (008/2008AIA)Publisher's versio

Polymorphisms in the RNASE3 Gene Are Associated with Susceptibility to Cerebral Malaria in Ghanaian Children

BACKGROUND: Cerebral malaria (CM) is the most severe outcome of Plasmodium falciparum infection and a major cause of death in children from 2 to 4 years of age. A hospital based study in Ghana showed that P. falciparum induces eosinophilia and found a significantly higher serum level of eosinophil cationic protein (ECP) in CM patients than in uncomplicated malaria (UM) and severe malaria anemia (SA) patients. Single nucleotide polymorphisms (SNPs) have been described in the ECP encoding-gene (RNASE3) of which the c.371G>C polymorphism (rs2073342) results in an arginine to threonine amino acid substitution p.R124T in the polypeptide and abolishes the cytotoxicity of ECP. The present study aimed to investigate the potential association between polymorphisms in RNASE3 and CM. METHODOLOGY/PRINCIPAL FINDINGS: The RNASE3 gene and flanking regions were sequenced in 206 Ghanaian children enrolled in a hospital based malaria study. An association study was carried out to assess the significance of five SNPs in CM (n=45) and SA (n=56) cases, respectively. The two severe case groups (CM and SA) were compared with the non-severe control group comprising children suffering from UM (n=105). The 371G allele was significantly associated with CM (p=0.00945, OR=2.29, 95% CI=1.22-4.32) but not with SA. Linkage disequilibrium analysis demonstrated significant linkage between three SNPs and the haplotype combination 371G/*16G/*94A was strongly associated with susceptibility to CM (p=0.000913, OR=4.14, 95% CI=1.79-9.56), thus, defining a risk haplotype. The RNASE3 371GG genotype was found to be under frequency-dependent selection. CONCLUSIONS/SIGNIFICANCE: The 371G allele of RNASE3 is associated with susceptibility to CM and forms part of a risk associated haplotype GGA defined by the markers: rs2073342 (G-allele), rs2233860 (G-allele) and rs8019343 (A-allele) respectively. Collectively, these results suggest a hitherto unrecognized role for eosinophils in CM pathogenesis

Sub-microscopic Plasmodium falciparum infections in matched peripheral, placental and umbilical cord blood samples from asymptomatic Congolese women at delivery

International audienceIn malaria-endemic areas, most pregnant women are susceptible to asymptomatic Plasmodium falciparum infections. We present here the results of a cross-sectional study conducted in Madibou, a southern district of Brazzaville in the Republic of Congo, between March 2014 and April 2015. The main aim was to characterize P. falciparum infections. Blood samples corresponding to peripheral, placental and cord from 370 asymptomatic malaria women at delivery were diagnosed for plasmodium infection by thick blood smears (microscopic infection). Sub-microscopic infection was detected by PCR, using the MSP-2 gene as marker. Microscopic infections were detected in peripheral, placental and cord blood samples with a prevalence of respectively 7.3% (27/370), 2.7% (10/370) and 0%. The negative samples were submitted to sub-microscopic detection, with respective prevalence of 25.4% (87/343), 16.7% (60/360) and 9.4% (35/370) (P < 0.001). We further investigated the genetic diversity of the parasite by characterizing MSP2 allelic families 3D7 (24 distinct alleles) and FC27 (20 distinct alleles). The total number of alleles for these two families were 31, 25 and 19 in peripheral, placental and cord samples respectively. The 3D7 MSP-2 was the predominant allelic family. The multiplicity of infections (MOI) in peripheral (mean 1.4 ± 0.01; range 1–4), placental (mean 1.2 ± 0.01; range 1–3) and cord samples (1.4 ± 0.01; range 1–3) were similar (P = 0.9) and are unaffected by age, gravidity or sulfadoxine-pyrimethamine. These results shown a high prevalence of sub-microscopic infection and a high genetic diversity of Plasmodium falciparum strains in Congo. Age, gravidity and doses of preventive treatment based on sulfadoxine-pyrimethamine do not interfere with the multiplicity of infections

Antiplasmodial and Genotoxic Study of Selected Ghanaian Medicinal Plants

Ethnopharmacological Relevance. Development of resistance to antimalarial drugs by Plasmodium falciparum is still rampant, and there is an urgent need for novel drugs to either standalone or to partner artemisinin for treatment of malaria. Traditionally, plants have, over the years, been a good source of antimalarial drugs. Efficacy and safety of such plants need to be scientifically authenticated. Aims, Materials, and Method. This study investigated the in vitro antiplasmodial activity, cytotoxicity, and genotoxicity of aqueous extracts of Acanthospermum hispidum DC, Alstonia boone (De Wild), Cocos nucifera L, Cymbopogon citratus (DC.) Stapf, Morinda lucida Benth, Psidium guajava, Phyllanthus niruri L, and Senna siamea Lam. Results. Five out of the eight plants, A. boonei stem bark, S; siamea Lam root, M. lucida Benth leaves, P. niruri, and A. hispidum DC whole plants, showed varying degrees of antiplasmodial activity against the asexual stage of the parasite. The most active extract against chloroquine-sensitive (3D7) and chloroquine-resistant (Dd2) P. falciparum strains is the A. hispidum extract which yielded a mean inhibitory concentration at 50% (IC50) of 3.66 µg/ml and 3.71 µg/ml for 3D7 and Dd2, respectively. This was followed by S. siamea Lam with 3.95 µg/ml for 3D7 and 4.47 µg/ml for Dd2. The IC50 values of the A. boonei extract against 3D7 and Dd2 P. falciparum parasites were 5.13 µg/ml and 3.62 µg/ml, respectively. For the M. lucida Benth extract, the least IC50 value was 6.46 µg/ml. All five extracts exhibited dose-dependent antiplasmodial activity. Assessment of the genotoxic effects the A. hispidum extract by the comet assay revealed substantial damage to P. falciparum DNA. Conclusion. This study demonstrates that the crude extract of A. hispidum DC, one of the plants used traditionally to treat malaria, inhibits the growth of P. falciparum in vitro and could be a potential source of antimalarial drug. The report has highlighted genotoxic and cytotoxic effects of the selected plant extracts on human leukocytes as well

<i>RNASE3</i> haplotypes, c.371G>C genotypes and alleles distribution in malaria endemic (Ghanaian) versus non-malaria (Danish) populations.

<p><b>A</b>) Distribution of haplotypes defined by the three SNPs (rs2073342, rs2233860 and rs8019343) as from block 1 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029465#pone-0029465-g001" target="_blank">Figure 1A</a> in the two populations. <b>B</b>) c.371G>C genotype distribution in all Ghanaian subjects compared to Danes. <b>C</b>) c.371G>C allelic distribution in the two populations.</p