One in eight children in the UK has asthma

Tests on mice who had asthma showed giving them a protein stopped the build-up of mucus in airways.

Writing in Nature Medicine, North Carolina State University researchers say the treatment could help asthmatics and others with respiratory diseases

More than 100 million people around the world have asthma, and around 18,000 die from the condition each year.

The treatment may well have clinical benefits in the future Dr Duncan Rogers, Imperial College

Asthmatics experience recurrent attacks of wheezing and breathlessness as their airways narrow and secrete large amounts of mucus when they are exposed to an allergen, such as pollen or dust mites.

The mucus can damage the airway lining, making patients more susceptible to bacterial infection and respiratory failure.

Reactions

A team led by Dr Kenneth Adler found a key molecule in mucus-making cells in the wall of the airways.

They developed a protein called a MANS peptide which could block the action of the key molecule

They tested the peptide on mice suffering from asthma-like symptoms - when they were exposed to an allergen, their airways swelled and the production of mucus increased fivefold.

But it was found that giving the mice a single dose of the drug 15 minutes before an induced asthma attack, prevented the build-up of mucus.

Asthmatics already use drugs that help relax the airways, but there are no medications for reducing mucus.

But scientists are uncertain why the treatment was effective.

It could work because the cells are no longer secreting mucus, and they shrivel and disappear.

But there is a possibility the treatment stops the secretion of mucus and not its production, which could lead to mucus building up inside cells and eventually push them to bursting point.

Therapy hope

Dr Joe Garcia, head of pulmonary and critical-care medicine at the Johns Hopkins University in Baltimore, Maryland, said: "The peptide is potentially useful in the clinic. This would complement, not replace standard therapies."

But Dr Garcia warned further tests were needed to ensure the molecule does produce unwanted effects on other cells.

Dr Matt Hallsworth of the National Asthma Campaign. said: "Excessive production of mucus can be a prominent feature of asthma and this contributes to the narrowing of the airways, causing wheezing and shortness of breath.

"Unfortunately there is currently no effective therapy that specifically targets this process.

"The next exciting step is to see whether this discovery will translate into an effective therapy in humans."

'Potentially beneficial'

Scientists believe the drug could also be useful in treating patients with cystic fibrosis or chronic obstructive pulmonary disease, who are also affected by mucus build-up.

Respiratory disease specialist Dr Duncan Rogers of Imperial College, London, told BBC News Online: "The treatment may well have clinical benefits in the future.

"Inhaled steroids are very effective in patients with asthma.

"But they are not so effective in patients with chronic obstructive pulmonary disorder, so people are looking for alternative therapies.

"Anything that could have an effect would be good to look at."

Dr Rogers said it was possible that there could be a build-up of mucus in cells.

But he added: "The possible positives far outweigh the potential negatives."