New hope for asthma sufferers as genetic cause is discovered
A cure for asthma is on the horizon after scientists discovered a genetic switch that prevents the condition.
The research, carried out at the University of Southampton, discovered that the gene ADAM33 plays a crucial role in causing the twitchiness and inflammation of airways that trigger an attack.
The gene makes an enzyme that attaches to the muscles in the airways. But the enzyme can become detached and 'go rogue', travelling around the lung and sparking the unnecessary production of new muscles and blood vessels - known as airway remodelling - which makes breathing difficult when coupled with an allergen such as pollen or dust.
Studies in human tissue samples and mice show that if the gene is switched off the enzyme stops being a problem.
Professor Hans Michel Haitchi, associate professor in respiratory medicine, said: "This finding radically alters our understanding of the field, to say the least. For years we have thought that airway remodelling is the result of the inflammation caused by an allergic reaction, but our research tells us otherwise."
The new study suggests that a drug to knock out the effects of the ADAM33 gene could prevent attacks.
The scientists found that on its own, rogue human ADAM33 causes airway remodelling, resulting in more muscle and blood vessels around the airways of developing lungs, but does not cause problems.
However, when scientists introduced a house dust mite, both airway remodelling and allergic airway inflammation were significantly enhanced.
In another study, remodelling of the airways was shown in mice that had ADAM33 switched on in utero.
The gene was then switched off and the airway remodelling was reversed.
They also studied the impact of the house dust mite allergen on asthma in mice that had the ADAM33 gene removed. Airway remodelling and twitchiness as well as airway inflammation rates were reduced by 50pc and 35pc in mice that did not have the rogue gene.
Prof Haitchi said: "Our studies have challenged the common paradigm that airway remodelling in asthma is a consequence of inflammation.
"Instead, we have shown that rogue human ADAM33 initiates airway remodelling that promotes allergic inflammation and twitchiness of the airways in the presence of allergen.
"More importantly, we believe that if you block ADAM33 from going rogue or you stop its activity if it does go rogue, asthma could be prevented.
"ADAM33-initiated airway remodelling reduces the ability of the lungs to function normally, which is not prevented by current anti-inflammatory steroid therapy. Therefore, stopping this ADAM33-induced process would prevent a harmful effect that promotes the development of allergic asthma." (©Daily Telegraph, London)