Transgenic plants for allergen-specific immunotherapy

Abstract

Allergen-specific immunotherapy (IT) is an effective treatment for allergic diseases. Although subcutaneous and sublingual ITs are currently used, safer, easier, and more effective IT is under development. Induction of immune tolerance by oral administration of allergen has been proven, though oral IT has not been applied clinically. It is mainly because a large amount of purified allergen is required to induce oral tolerance. To overcome this problem, plants, peculiarly rice, have been investigated as allergen vehicles for oral IT. Rice can store a considerable amount of expressed allergen in its seeds and the accumulated allergen is stable and resistant to gastrointestinal digestion. Therefore, we have developed transgenic rice seeds (Tg rice) in which major epitopes of cedar pollen or house dust mites are expressed. We are establishing Tg rice with demonstrated efficacy in murine models of allergic rhinitis and bronchial asthma by oral administration at practical doses. In addition, the amount, distribution, and allergenicity of the expressed allergen have been improved in our Tg rice. Rice-based oral IT is a promising new concept in IT for the treatment of allergic diseases.

Keywords: Allergic disease; Asthma; Oral immunotherapy; Rhinitis; Transgenic rice

Core tip: We aim to establish clinically applicable oral immunotherapy by employing transgenic rice seeds (Tg rice) in which allergen epitopes are expressed. We have identified a suitable allergen packaging system, modified allergens to reduce their allergenicity, selected high allergen-producing lines, and evaluated their efficacy in allergic disease models. We are thus nearly ready to start clinical trials of our Tg rice for the treatment of Japanese cedar pollinosis.