Differential contribution of interleukin-10 promoter variants in malaria and schistosomiasis mono- and co-infections among Nigerian children

Objective Interleukin-10 (IL-10) is an anti-inflammatory cytokine produced by Th1 cells and macrophages. The rationale of this study was to examine and validate possible contributions of IL-10 promoter polymorphisms in sub-Saharan Africa in children infected with either Plasmodium falciparum or Schistosoma haematobium and in children co-infected with both parasites. Materials and Methods 309 Nigerian children aged 4 to 15 years were recruited. The study group consisted of individuals infected either with P. falciparum (n=76) or S. haematobium (n=94) in mono-infections, a group of children co-infected with both P. falciparum and S. haematobium (n=62) and matched healthy controls (n=77). The IL10 promoter polymorphisms -1082G/A, -819C/T, and -592C/A were genotyped by direct sequencing. Results The frequencies of the IL10 -1082GG genotype, the -1082G allele and haplotype GCC (positions -1082, -819, and -592) were higher in children infected with P. falciparum than in healthy controls, indicating that the -1082GG genotype and the -1082G allele and the GCC haplotype are associated with increased susceptibility to malaria infection (OR=3.4, 95% CI=1.2-10.8, P=0.02; OR=2.5, 95% CI=1.1-3.4, P=0.02; OR=3.8, 95% CI=2.0-7.2, P=0.0001, respectively). Children with the -1082GG genotype had a higher parasitaemia than children with the -1082AA or -1082AG genotypes (P=0.0017). Haplotype GCC occurred more frequently in children infected with S. haematobium, while haplotype GTA was less frequent than in controls (OR=2.2, 95% CI=1.2-4.4, P=0.017 and OR=0.1, 95%CI=0.02-0.5, P=0.0004, respectively). No differences in the frequencies of IL10 promoter polymorphisms were observed between children with P. falciparum-S. haematobium co-infections and healthy controls. Conclusion Although IL10 promoter polymorphisms are not associated with P. falciparum and S. haematobium co-infection, variant -1082G/A and haplotype GCC are associated with malaria, whereas the IL10 haplotypes GCC and GTA are associated with schistosomiasis. This article is protected by copyright. All rights reserved.