Polymorphism of the rs1800896 IL10 promoter gene protects children from post-bronchiolitis asthma.

Viral bronchiolitis is a major cause of hospitalization in infancy, with increased asthma risk in later childhood. However, the principal mechanisms behind post-bronchiolitic asthma have remained unclear. Previously, different cytokine polymorphisms have been associated with asthma occurrence, but no previous follow-up study has investigated cytokine polymorphisms in relation to post-bronchiolitic asthma. We hypothesized that former bronchiolitis patients with cytokine gene variants associating with Th2 cell up-regulation are at asthma risk at preschool age. Our emphasis was in IL10 rs1800896, since IL-10 has an important role in immune tolerance, and lower production of IL-10 has been associated with Th2-type immunology, and accordingly, with increased asthma risk. IL10 rs1800896, IFNG rs2430561, and IL18 rs1872387 polymorphims and their associations with asthma and allergy were studied in 135 preschool-aged children hospitalized for bronchiolitis at age 0-6 months. Parents were interviewed to record asthma and allergy from infancy to present. At age 6.4 years (mean), asthma was present in 17(12.6%), atopic eczema in 47(34.8%) and allergic rhinitis in 36(26.7%) children. IL10 rs1800896 SNP associated significantly with asthma; only 1/32 (3.1%) of those with G/G genotype had asthma (P = 0.04). In logistic regression adjusted for gender, age and atopy, the carriage of allele A (rs1800896) was a significant risk factor for preschool asthma. IFNG rs2430561 or IL18 rs1872387 SNP's had no associations with asthma or allergy. In conclusion, IL10 rs1800896 SNP was significantly associated with preschool asthma after severe lower respiratory tract infection in early infancy.