BACKGROUND AND OBJECTIVE:
Urinary tract infection (UTI) in children is characterized by a variety of clinical manifestations. A potential cause of different phenotypic responses is a genetically heterogeneous immune response. In view of the central role of interleukin-8 (IL-8) in the pathogenesis of UTI, the IL-8 gene polymorphism may be an important factor in determining the UTI phenotype. The objective was to study the frequency of polymorphic variants of the gene encoding IL-8 in children with UTI and the impact of polymorphism of IL-8 on the pathology.
The study included 60 patients aged 3 to 18 years with UTIs. The control group consisted of 30 children without clinical symptoms of UTI and without anamnestic data about renal dysfunction. Materials for molecular genetic analysis were DNA samples, which were isolated from the urine. Nucleotide polymorphism detection estimated the carrier alleles of IL-8-251A, followed by determination of genotype A/A, A/T, and T/T. We performed statistical data processing by using the program package Statistica 6.0 (StatSoft, Tulsa, OK).
Nosologic groups were formed: 15 children with acute cystitis, 24 with acute pyelonephritis, and 21 with chronic pyelonephritis. Analysis of the distribution of genotypes demonstrated that the normal genotype of IL-8-251 TT was found in 36.6% ± 6.2% of patients and the heterozygous phenotype of IL-8-251 AT was found in 60.0% ± 6.3%. Compared with the control group, we detected a significant difference (P < .0005) in the distribution of genotypes: Genotype IL-8 251 TT was found in 66.6% ± 12.1% of children in the control group, IL-8-251 AT in 33.4% ± 12.1%. A positive association between the genotype IL-8-251 AT and UTI occurrence was established: RR = 2.8; χ2 = 9.6, P < 0002. Analysis of gene polymorphisms of IL-8 (251 AT) based on the clinical forms of UTI showed that the most common (71.4% ± 9.8%) was found in patients with chronic pyelonephritis (P < .0005), whereas in patients with cystitis it was found in 46.6% ± 12.8%.
Heterozygous genotype IL8-125 AT can be used as a criterion for the onset and course of UTI. Identification of prognostic criteria of UTI phenotypes in children, taking into account the genotypic polymorphism of IL-8, requires additional study.
- Copyright © 2015 by the American Academy of Pediatrics