Interleukin-4 and interleukin-13 pathway genetics affect disease susceptibility, serum immunoglobulin E levels, and gene expression in asthma.

BACKGROUND

Asthma is a common immune disorder characterized by increased IgE levels. The interleukin (IL)-4 and IL-13 pathway is central for IgE regulation, and previous studies have reported many genetic variants of IL-4/IL-13 signaling in relation to asthma, but few have focused on the gene-to-gene interactions that are likely to contribute to disease complexity.

OBJECTIVE

To assess the combined effects of 7 functional single-nucleotide polymorphisms (SNPs) on asthma susceptibility, total serum IgE levels, and gene expression in children.

METHODS

Seven SNPs (rs2243250, rs1800925, rs1805010, rs324011, rs2251746, rs2494262, and rs2427837) were genotyped children with asthma (n = 500) and a control group (n = 523), and total serum IgE levels and gene expressions were measured in children with asthma.

RESULTS

Children with asthma had a likelier possibility of carrying more risk genotypes. Mean IgE levels increased from the minimum of 71.07 KU/L in children with no tested polymorphisms to a maximum of 901.7 KU/L in children carrying 7 risk genotypes. Gene expression analysis showed that patients with 4 SNPs (rs2243250, rs1800925, rs1805010, and rs3224011) had higher expression levels of IL-4, IL-13, and STAT6. Moreover, serum IgE level generally correlated well with IL-4 (r = 0.236, P = .011) and IL-13 (r = 0.211, P = .021) expressions; IL-4 expression correlated positively with IL-13 (r = 0.962, P = .000) and STAT6 (r = 0.190, P = .022) expressions, and STAT6 expression correlated with IL-4RA expression (r = 0.904, P = .000).

CONCLUSION

These data suggest that combinations of multiple SNPs might magnify the impact on disease risk. Only a combined analysis of the variants in the IL-4/IL-13 pathway could show the functional interplay of multiple genes in asthma.