Association of serum interleukin-33 level and the interleukin-33 genetic variant with Japanese cedar pollinosis

IL-33, an IL-1-like cytokine, is a ligand for IL1RL1, which is an important effector molecule of type 2 T helper responses. Although IL-33/IL1RL1 interaction has been suggested to be important in induction of allergic airway inflammation, serum levels of IL-33 and the genetic influences of the polymorphisms of IL-33 in human allergic diseases are unclear. The aim of this study was to examine whether the serum IL-33 level and polymorphisms in IL-33 are associated with Japanese cedar (JC) pollinosis, the most common form of allergic rhinitis, and a major public health problem, in Japan. We performed linkage disequilibrium (LD) mapping of the gene using the HapMap database, and two selected tag single nucleotide polymorphisms were genotyped. We conducted an association study of IL-33 (JC pollinosis, n=170; normal controls, n=100) and measured the IL-33 levels in sera of the 270 subjects by ELISA. Serum levels of IL-33 were significantly higher in patients with JC pollinosis (P=0.0018) than in controls. In genetic association analysis, we found a positive association between the polymorphism and JC pollinosis (P=0.048). Our results support a role for IL-33 in the pathogenesis of JC pollinosis. Cite this as: M. Sakashita, T. Yoshimoto, T. Hirota, M. Harada, K. Okubo, Y. Osawa, S. Fujieda, Y. Nakamura, K. Yasuda, K. Nakanishi and M. Tamari, Clinical and Experimental Allergy, 2008 (38) 1875-1881.