The Polymorphism of IL-17 G-152A was Associated with Childhood Asthma and Bacterial Colonization of the Hypopharynx in Bronchiolitis

Interleukin (IL)-17 plays an important role in the pathogenesis of asthma. We investigated the association between single-nucleotide polymorphism (SNP) of IL-17 (rs2275913, IL-17 G-152A) and asthma-related traits. Its effect on IL-17 production was also attractive. One hundred and sixty eight childhood asthmatic patients, 144 bronchiolitis patients, and 205 healthy controls were recruited in this study. SNP rs2275913 was genotyped by polymerase chain reaction-restriction fragment length polymorphism. Peripheral blood mononuclear cells (PBMCs) from parts of healthy controls with different genotype were isolated and cultured with phytohaemagglutinin (PHA) for detection of IL-17 in the supernatants. SNP rs2275913 was associated with asthma (P = 0.03) in genotype frequency test. Children with homozygous A were 2.29 times more likely to have asthma than others (95% confidence interval 1.39-3.78, P = 0.001). The strength of associations was moderately higher by allergy comorbidity. Furthermore, SNP rs2275913 A allele was associated with abnormal lung function and serum total IgE in asthmatics, although the production of IL-17 by PHA-induced PBMC seemed to be not different among individuals with different genotypes. The distribution of SNP rs2275913 in bronchiolitis was marginally statistically different with controls and demonstrated a tendency close to that in asthma. Higher Streptococcus pneumoniae and Moraxella catarrhalis detection rates were shown in bronchiolitis patients with homozygous A allele than those with other genotypes (20.8% vs. 3.7%, P < 0.01 and 20.8% vs. 6.2%, P = 0.03). The preliminary results demonstrate that IL-17 SNP rs2275913 was associated with several asthma-related traits and confers genetic susceptibility to childhood asthma. It may be used to develop markers to assess the risk of asthma, especially in the bronchiolitis population. It may be a potential bridge to connect the bacterial colonization and the onset of asthma.