Association of Interleukin-4 Receptor α Chain I50V Gene Variant (rs1805010) and Asthma in Iranian Population: A Case-control Study

Background

Asthma is one of the respiratory disorders caused by chronic airway inflammation. IL-4 has been identified as one of the participating interleukins in the severity of asthma.

Objective

A case-control study was conducted to determine the association of rs1805010, a single nucleotide polymorphism in the interleukin 4 receptor α chain, with asthma and immunoglobulin E and IL-17A serum levels in Iranian populations.

Methods

ELISA was used to investigate the relationship between three different varieties of SNP I50V and serum IL-17A levels, as well as total IgE levels. Based on GINA criteria, patients were classified into mild, moderate, and severe groups based on the association between SNP I50V, IL-17A, and total IgE. In order to analyze the data, the student-t-test and the one-way ANOVA were used.

Results

The SNP I50V was associated with asthma in a significant way (p = 0.001). IL-17A and total IgE levels were significantly higher in asthmatic patients than in control participants (p 0.05 and p 0.021, respectively), but neither showed any association with SNP I50V in the asthmatic patients.

Conclusion

Asthma patients have a higher prevalence of the I allele, reflecting the significance of Th2 cells. Although total IgE and IL-17A levels increased in both disease subgroups, total IgE level augmentation correlates directly with disease severity, while IL-17A level enhancement does not.

Cutting Edge: Effects of an Allergy-Associated Mutation in the Human IL-4Rα (Q576R) on Human IL-4-Induced Signal Transduction

A mutation in the human (hu) IL-4Rα, Q576R, has been linked with allergy in humans. Increased sensitivity of patients cells with this mutation to IL-4 suggest that a Q576R change enhances IL-4 signaling. To directly test this hypothesis, we analyzed the ability of huIL-4Rα cDNA bearing the Q576R and Y575F mutations to signal tyrosine phosphorylation, DNA-binding activity, proliferation, protection from apoptosis, and CD23 induction in response to huIL-4 in murine cells. Responses generated by the Q576R and Y575F mutants were similar to those of the wild-type receptor, using various concentrations of huIL-4 and times of stimulation. These results indicate that neither the Q576R nor the Y575F mutations have a significant direct effect on IL-4 signal transduction, and that hypersensitive induction of CD23 in cells derived from human allergy patients may be due to different and/or additional alterations in the IL-4 signaling pathway.