It may be possible to treat severe asthma now by blocking a chemical in the immune system. This chemical is present in huge quantity in the immune system of the patients with severe asthma. The study appears in the online edition of the journal Thorax.
Around one in 10 asthmatics have the severe form of the disease, which frequently requires progressively higher doses of steroids in a bid to control symptoms.
Severe asthma is also associated with a much higher risk of illness and death than milder forms and accounts for almost a third of health service costs for asthma.
The research team investigated tumor necrosis factor alpha (TNF alpha), which is found in a range of chronic inflammatory conditions, including rheumatoid arthritis, Crohn's disease, and psoriasis.
Included in the study were 26 healthy people, 67 mild asthmatics, and 51 severe asthmatics. Bronchial fluid and lung tissue samples were taken from the participants to discover their levels of TNF alpha.
Levels were significantly higher in those with severe disease and concentrated in one particular type of immune cell (mast cells), which are recognized components of the inflammatory reaction in asthma.
TNF alpha levels were low and similar in those with no asthma or who only had mild symptoms.
This suggests that the high levels of TNF alpha in severe disease are characteristic of more chronic disease that is resistant to steroid treatment, rather than a feature of the disease itself.