IL-33 gene variants and protein expression in pediatric Tunisian asthmatic patients

Interleukin-33 (IL-33) is one of the last discovered members of the human IL-1 family. It is involved in the pathogenesis of many inflammatory diseases. This study investigates the relationship between IL33 gene variants and serum protein levels with the development of childhood asthma. We analyzed in this case-control study the distribution of two IL33 polymorphisms, rs7044343 and rs1342326, within 200 Tunisian children, using pre-defined Taqman genotyping assays. IL-33 serum levels were assessed by commercial sandwich Enzyme-linked immunosorbent assay (ELISA). The presence of rs1342326 polymorphism was significantly associated with a lower risk of asthma development. The CC [OR = 0.20, CI (0.08-0.50)] and AC [OR = 0.24, CI (0.11-0.49)] genotypes, as well as the C-allele [OR = 0.40; CI: 0.26-0.61, P = 0.00001] were associated significantly with a decreased asthma risk. However, the C-allele was more frequent in severe asthma patients than in milder ones. No association was found between rs7044343 variant and asthma. The level of IL-33 in sera was significantly increased in asthmatic children [1.48 +/- 0.47 pg/mL] compared to controls [0.70 +/- 0.18 pg/mL; P < 0.001]. Furthermore, this increase of IL-33 was associated with the presence of rs1342326 C allele. The 7133 rs1342326 polymorphism was associated with a lower childhood asthma risk in the Tunisian population and a higher IL-33 protein expression.