Níveis séricos e polimorfismos genéticos das interleucinas IL-6 E IL-10 em indivíduos com síndrome de down

Abstract

Down syndrome (DS) is the most frequent human chromosomopathy with approximate incidence of the 1 to 850 live births, nearly 90-95% of these cases are characterized by the presence of three copies of chromosome 21 as a result of the meiotic nondisjunction. DS individuals present many clinic features, including immunological changes that result in altered inflammatory response. The immune response is modulated by pro- and anti-inflammatory cytokines whose expression could be influenced by genetic polymorphisms in the coding or promoter region within the gene. Objectives: The study aimed to evaluate the frequencies of the -174G/C, -572G/C e -597G/A polymorphisms in the interleukin (IL) 6 gene promoter region and of the -592C/A, -1082A/G e -819C/T polymorphisms in the IL-10 gene promoter region in individuals with DS, and a control group without 21 trisomy, as well as to investigate the impact of the studied genotypes in the interleukins serum levels. Material and Methods: DNA samples of 200 DS individuals and 200 controls without DS were submitted to Polymerase Chain Reaction – Restriction Fragment Length Polymorphism (PCR-RFLP) or real time PCR for evaluate to presence of the -174G>C, -572G>C, and -597G>A IL-6 and -592C>A, -1082A>G, and -819C>T IL-10 polymorphisms. The serum measurement of IL-6 and IL-10 was performed in a subgroup (54 cases and 54 controls) by ELISA essay. The genotypic distribution between groups was performed by multiple logistic regression by SNPStats, program, and the linkage disequilibrium evaluation and haplotype frequency was performed by Haploview program. The comparison of IL-6 and IL-10 serum level between the groups was performed by Mann Whitney test, the interleukins concentrations analyze in relation to genotypes was performed by Kruskal-Wallis test, using the GraphPad Prism version 6.0 software. The standard error of 5% was accept. Result: Either the frequency of IL-6 and IL-10 polymorphisms or their haplotypes did not show differences between the case and control groups. There was no association between the IL-6 and IL-10 serum levels and the IL-6 and IL-10 polymorphisms. IL-10 serum levels were increased in the case group in relation to control group. Conclusion: The frequencies of the polymorphisms and haplotypes evaluated are not different between individuals with and without DS. Genotypes show no effect on the IL-6 and IL-10 serum levels. The IL-10 serum levels are increased in DS individuals, but the IL-10 polymorphisms are not the main factors that influence in higher expression of the IL-10 in DS.