Genetic Variants of the Receptors for Thromboxane A2 and IL-4 in Atopic Dermatitis

Thromboxane A2 (TXA2) is an arachidonate metabolite which is considered to relate to chronic inflammation in atopic diseases characterized by elevated immunoglobulin E productivity. The elevation of immunoglobulin E levels involves many molecules including interleukin-4 (IL-4) and interleukin-4 receptor alpha chain (IL-4Rα). To assess whether genetic variants of TXA2 receptor, IL-4 and IL-4Rα genes relate to the elevation of serum immunoglobulin E levels in patients with atopic dermatitis (AD), we conducted an association study of genetic polymorphisms of TXA2 receptor (795C/T), IL-4 (−589C/T), and IL-4Rα (Ile50Val) in a Japanese population (n = 789). The TXA2 receptor 795TT genotype strongly related to AD with high serum immunoglobulin E concentrations. AD patients with both TXA2 receptor 795TT genotype and the IL-4Rα Ile50/Ile50 genotype showed the greatest immunoglobulin E concentrations. These results suggest TXA2 receptor polymorphism strongly interacts with IL-4Rα polymorphism as a major determinant of high serum immunoglobulin E levels in AD.