Fresh Science

Researchers have discovered an underlying cause of asthma-the muscle cells surrounding the airways of people with asthma grow twice as fast as those of non-asthmatics, leading to more muscle tissue.

During an asthma attack the muscle tissue which surrounds the airways contracts. The new study suggests that this contraction is severe in people with asthma because of the extra muscle tissue present.

Dr Peter Johnson and his colleagues, at the University of Sydney and the Institute of Respiratory Medicine at Royal Prince Alfred Hospital, wanted to know why asthmatics grew more muscle tissue around their airways than non-asthmatics. In order to find out, the researchers collected donated samples of smooth muscle cells from the airways of 12 asthmatics and compared their growth with cells collected from 10 non-asthmatics.

“What I found is that when you grow airway muscle cells from asthmatics in a dish, they grow twice a fast as cells from people who don’t have asthma,” Dr Johnson said. “This would suggest that people with asthma have genes which are ‘switched on’ to make the muscle grow faster. It is likely that the interaction between these genes and the environment plays a major role in what makes a person asthmatic.”

At present, the drugs used to treat asthma concentrate either on relaxing the airway constriction or stopping inflammation. Sufferers, however, have to keep taking these drugs.

“Researchers have got a pretty good grip on what occurs in an asthma attack and we have good medication to treat it,” says Dr Johnson.

“Our work is the first step to the design of new drugs to prevent and possibly even reverse this excessive growth of airway cells. It opens a whole new avenue for reducing the incidence of asthma in the population.