Asthma is one of the most common chronic diseases in childhood and one of the leading causes of morbidity in children. Its incidence has been growing, especially in the Western, highly industrialized nations. Glucocorticoids are used for the treatment of many inflammatory and autoimmune diseases, among them asthma, because they can switch off genes that code for pro- inflammatory cytokines and chemokines. Unfortunately, there is a substantial group of severe asthma patients that are steroid resistant. In addition, they suffer from the long term side effects of systemic steroid use.