TNF-α (-308 G/A) and CD14(-159T/C) polymorphisms in the bronchial responsiveness of Korean children with asthma

Background: TNF-alpha is a pivotal proinflammatory cytokine increased in asthmatic airways. The TNF-alpha gene family might be linked to asthma or bronchial hyperresponsiveness (BHR), and TNF-alpha production might be modulated by CD14(+) cells. Objective: We investigated the association between asthma susceptibility or asthma-related phenotypes and TNF-alpha (-308G/A) polymorphism and examined the combined effect with CD14 (-159T/C) polymorphism in Korean children. Methods: Asthmatic (n = 788) and control (n = 153) children were evaluated for asthma phenotypes. Genotypes were determined by using the single-base extension method and PCR-restriction fragment length polymorphism. Results: There was no difference between asthmatic children and control subjects in terms of the allele frequencies of TNF-alpha (-308G/A) and CD14 (-159T/C). Significantly lower PC20 values were seen in asthmatic (P = .016) children with the TNF-a risk allele (-308A). Higher frequencies of 1 or 2 copies of the risk allele were found in asthmatic children with moderate-to-severe BHR to methacholine and exercise compared with control children (adjusted odds ratio of 2.57 [95% CI, 1.30-5.08] and adjusted odds ratio of 2.04 [95% CI 0.99-4.20], respectively). In addition, asthmatic children with risk alleles at both loci had significantly greater BHR than those homozygous for the common alleles (P = .018). Conclusion: The TNF-alpha promoter polymorphism (-308GIA) might be associated with severe BHR in Korean children with asthma. In addition, these children show a synergistic effect between the TNF-a promoter (-308A) and CD14 promoter (-159C) polymorphisms in terms of BHR. Clinical implications: The TNF-alpha polymorphism might be a disease-modifying gene in asthma and modulated by the CD14 gene.