[Clarification of the pathogenesis and development of clinical examination for allergic diseases]

The incidence of allergic diseases has dramatically increased in recent decades in Japan; therefore, it is important to establish ways to diagnose allergic patients based on their pathogenesis and to treat them. Allergic diseases are complicated and diverse disorders in which various cells and mediators are involved; however, it is widely accepted that they are Th2-type inflammations triggered by the invasion of allergens. It is known that either IL-4 or IL-13, particularly the latter, has an important role in the pathogenesis of bronchial asthma among Th-2 type cytokines; however, it is unclear how IL-4 or IL-13 causes asthmatic phenotypes. We have been trying to address this question by using microarray analysis. We have recently found that periostin, identified as an IL-4/IL-13-inducible gene by microarray analysis, is a novel component of subepithelial fibrosis of bronchial asthma. This finding is important to demonstrate the significance of IL-4 and/or IL-13 as a therapeutic target to inhibit fibrosis in bronchial asthma. Furthermore, it is also important to establish a way to diagnose allergic patients in which IL-4 or IL-13 is dominantly involved, and to apply the developing IL-4/IL-13 inhibitors to these patients. In this article, we show how we are addressing this issue.