Immunomodulatory treatment strategies for allergic diseases

Over the last decades the prevalence of allergic disorders, such as hayfever and asthma has increased worldwide, mostly in westernised countries where up to 20 % of the population are affected. The "hygiene hypothesis" suggests that modernised lifestyles such as improved housing conditions, altered dietary habits and smaller family sizes may be responsible for the decrease in infectious and the increase in allergic diseases. Childhood atopic diseases, like eczema, food allergies and recurrent wheezy bronchitis represent a considerable health problem and a major socioeconomic burden due to the chronicity of these disorders. In recent years, a better understanding of the immunopathogenesis of allergic diseases has evolved, which has contributed to the development of novel more targeted forms of therapy. Allergen injection immunotherapy is the only treatment in current use with the potential for modifying the course of allergic disease. In order to better target mucosal allergies, new approaches of administering allergen, via the sublingual or intranasal route, are being developed. The use of modified allergens, allergen peptides, DNA immunization and the use of novel adjuvants represent alternatives to conventional immunotherapy with potential for improved efficacy with less side effects. For atopic asthma, novel treatment strategies aim at locally targeting inflamed airways. Nebulized monoclonal blocking antibodies and soluble interleukin receptors against "Th(2)-type" cytokines have been designed. An alternative approach has been the administration of "Th(1) -type" cytokines. Although, immunomodulatory strategies provide a promising outlook for the treatment of allergic patients, more studies are needed in the future to address issues of efficacy, safety and long-term effects of altered immune responses.