Relação entre polimorfismos de IL-8 e a gravidade da bronquiolite viral aguda

Abstract

Introduction : almost all infants present infection by respiratory syncytial virus (RSV) up to 2 years of age. However, the severity of acute viral bronchiolitis (AVB) can vary significantly. This variability may be caused by genetic and immunological factors. Previous studies have shown that RSV-infected airway contains high levels of interleukin 8 (IL-8). The knowledge of genetic polymorphisms associated with severe AVB may have clinical relevance, identifying patients with high-risk for severe AVB. Methods : We included infants admitted to the pediatric emergency of Hospital Sao Lucas (HSL) da PUCRS with AVB, aged less than 12 months, in the period between september 2009 to september 2011; and infants of the same age who did not have had AVB, recruited from the primary care center Bom Jesus. Samples were collected from capillary blood. DNA was extracted for genotyping of two polymorphisms (SNPs rs2227543 and rs2227307) in the IL-8 gene. Results : In the final genetic association sample, we included 115 cases and 64 controls. There was no significant deviation from Hardy-Weinberg equilibrium. The SNP rs2227543 showed significant protection for AVB, with lower frequency of homozygous TT patients in the control group (OR 0.25: CI 0.10 to 0.65). However, rs2227307 showed no association with AVB. Conclusion : This finding, together with the analysis of previous studies, suggests that the IL-8 polymorphism rs2227543 is associated with protection of the AVB and directly influences the severity of AVB in these infants