Possible role of TLR4 and TLR9 SNPs in protection against congenital toxoplasmosis.

W Wujcicka,J Wilczyński,D Nowakowska,Z Gaj

doi:10.1007/s10096-015-2461-3

Abstract

The purpose of this investigation was the determination of the distribution of genotypes at single nucleotide polymorphisms (SNPs) of the toll-like receptor 4 (TLR4) and the toll-like receptor 9 (TLR9) in fetuses and newborns congenitally infected with Toxoplasma gondii and the identification of genetic changes predisposing to infection development. The study involved 20 fetuses and newborns with congenital toxoplasmosis and 50 uninfected controls. The levels of IgG and IgM antibodies against T. gondii, as well as IgG avidity, were estimated by enzyme-linked fluorescent assay (ELFA) tests. T. gondii DNA loads in amniotic fluids were assayed by the real-time (RT) quantitative polymerase chain reaction (Q PCR) technique for parasitic B1 gene. TLR4 and TLR9 SNPs were identified using a self-designed multiplex nested PCR-restriction fragment length polymorphism (RFLP) assay. Randomly selected genotypes at SNPs were confirmed by sequencing. All the genotypes were tested for Hardy–Weinberg equilibrium and TLR4 genotypes were analyzed for linkage disequilibrium. A correlation was studied between the genotypes or haplotypes and the development of congenital toxoplasmosis using a logistic regression model. Single SNP analysis showed no statistically significant differences in the distribution of distinct genotypes at the analyzed TLR4 and TLR9 SNPs between T. gondii-infected fetuses and newborns and the controls. Taking into account the prevalence of alleles residing within polymorphic sites, similar prevalence rates were observed in both of the studied groups. The multiple SNP analysis indicated GTG variants at the TLR4 and TLR9 SNPs to be significantly less frequent in offspring with congenital toxoplasmosis than in uninfected offspring (p ≤ 0.0001). TLR4 and TLR9 SNPs seem to be involved in protection against congenital toxoplasmosis.

Highlights

Intrauterine infections are among the major causes of perinatal morbidity and mortality
The toll-like receptor 4 (TLR4) 896 A>G and 1196 C>T single nucleotide polymorphism (SNP) were seen in linkage disequilibrium among both the infected and the control offspring (p≤0.050)
No study had ever shown any simultaneous contribution of TLR4 and toll-like receptor 9 (TLR9) SNPs to the occurrence of T. gondii infection

Summary

Introduction

Intrauterine infections are among the major causes of perinatal morbidity and mortality. 40 % of pregnant Polish women are infected with Toxoplasma gondii [1,2,3]. Dangerous are primary infections in pregnant women, which are usually asymptomatic and, in approximately 30– 50 % of patients, result in transplacental transmission of T. gondii to the fetus [4]. Toll-like receptor (TLR)/MyD88 signaling has been reported as the key pathway in a non-specific antimicrobial response against T. gondii [6, 7]. T. gondii infection induced the production of interferon (IFN)-β through TLR4 and MyD88 signaling [11]. TLR9 might have an important role in the immunity against T. gondii, since TLR9-deficient mice, infected with the parasite, were comparatively resistant to the ileitis, revealing a decreased Th1 immune response [12, 13]

Methods

Results

Conclusion