IL-17A gene polymorphism rs2275913 is associated with the development of asthma after bronchiolitis in infancy

Background Interleukin-17 (IL-17A) is a mainly pro-inflammatory cytokine, and IL-17 signaling implicates in the development of allergic asthma. The polymorphism rs2275913 in the promoter region of the IL-17A gene has in previous studies been associated with asthma susceptibility. The objective was to evaluate the association between IL-17A rs2275913 (-197G>A) polymorphism and post-bronchiolitis asthma and/or allergic rhinitis in a prospective 11–13 years post-bronchiolitis follow-up. Methods 166 previously healthy full-term infants, hospitalized for bronchiolitis at age less than 6 months, were invited to follow-up visits at the ages of 5–7 years and 11–13 years. Asthma diagnoses and presumptive symptoms, allergic rhinitis and use of inhaled corticosteroids (ICS) were registered. Blood samples for IL-17A rs2275913 (-197G>A) polymorphism were obtained during hospitalization or at the 5–7 years control visit. Results There were no significant differences between children with the wild GG and variant GA or AA genotype in the severity of bronchiolitis during hospitalization or in the outcomes until the age 5–7 years. At 11–13 years of age, children with the variant GA or AA genotype had significantly less often current asthma, use of ICSs during last 12 months or allergic rhinitis than those with the wild GG genotype. The ICS use during last 12 months retained the statistical significance in adjusted analyses (adjusted OR 0.25), whereas current asthma and allergic rhinitis marginally lost it. Conclusions The IL-17A rs2275913 (-197G>A) polymorphism decreased the risk of post-bronchiolitis asthma at 11–13 years of age, but not earlier in life, in the present prospective, long-term follow-up study.