TLR9 Polymorphisms Are Associated with Altered IFN-γ Levels in Children with Cerebral Malaria

Toll-like receptor (TLR) polymorphisms have been associated with disease severity in malaria infection, but mechanisms for this association have not been characterized. The TLR2, 4, and 9 single nucleotide polymorphism (SNP) frequencies and serum interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) levels were assessed in Ugandan children with cerebral malaria (CM, N = 65) and uncomplicated malaria (UM, N = 52). The TLR9 C allele at 1237 and G allele at 1174 were strongly linked, and among children with CM, those with the C allele at 1237 or the G allele at 1174 had higher levels of IFN-gamma than those without these alleles (P = 0.03 and 0.008, respectively). The TLR9 SNPs were not associated with altered IFN-gamma levels in children with UM or altered TNF-alpha levels in either group. We present the first human data that TLR SNPs are associated with altered cytokine production in parasitic infection.