[Effect of steroid therapy on the clinical course of bronchial asthma].

Although only some 5% of the asthmatic population develop severe disease, such cases eat up more than half of the spendings for the management of asthma and they are poorly controlled by the currently available therapies. Most of these patients undergo long-term treatment with various steroid formulations that exert selective action in the airways eliminating one cell type and supporting the growth of another. For this reason, inflammation patterns in severe, as opposed to mild, asthma resemble those in COPD, with a high neutrophil count in the sputum, increased oxidative stress, and poor response to corticosteroids. Such differences in asthma pathogenesis may be due to the accumulation of two CD4+ cell subsets (regulatory T cells and Th17 cells) in the lungs. It is believed that the use of alkylating drugs in low (non-cytotoxic) doses selectively inactivating Tregs and Th17 cells is a promising method for the treatment of severe asthma.