How do corticosteroids work in asthma?

Corticosteroids (or glucocorticosteroids) are widely used to treat various inflammatory and immune diseases. The most common use of corticosteroids today is in the treatment of asthma, and inhaled corticosteroids have become established as first-line treatment in adults and children with persistent asthma, the most common chronic inflammatory disease. Recent developments in understanding the fundamental mechanisms of gene transcription (see Glossary) have led to major advances in understanding the molecular mechanisms by which corticosteroids suppress inflammation. This may have important clinical implications, as it will lead to a better understanding of the inflammatory mechanisms of many diseases and may signal the future development of new anti-inflammatory treatments. The new understanding of these new molecular mechanisms also helps explain how corticosteroids switch off multiple inflammatory pathways; in addition, it provides insights into why corticosteroids fail to work in patients with steroid-resistant asthma and in patients with chronic obstructive pulmonary disease (COPD).