London - Scientists believe they have found the root cause of asthma in a breakthrough which could pave the way for a new treatment within five years.
Their excitement has been caused by the discovery of a protein within the airways which they think triggers all asthma attacks.
And, remarkably, a drug already exists which could deactivate the protein, raising hopes for a treatment which may be effective for all asthma patients.
The researchers have already shown that the drug works in mice and in human tissue samples in the laboratory.
Now the team, led by Cardiff University, has designed the first clinical trials, which could start within two years. Lead investigator Professor Daniela Riccardi said: “Our findings are incredibly exciting.”
The discovery came by chance when Professor Riccardi, formerly a bones specialist, switched from studying osteoporosis to the study of the lungs five years ago.
She realised that a protein which triggers the growth of calcium within bones also plays a role in the airways.
Further tests revealed that asthmatics had far higher levels of this protein – called a calcium sensing receptor or CaSR – than healthy people. When an asthmatic breathes in triggers such as dust, smoke, or pollen, the CaSR molecules cause a rapid increase of calcium within the cells of the lung tissue. The added calcium makes the cells contract, making the airways spasm, triggering an asthma attack.
Professor Riccardi said: “For the first time we have found a link between airways inflammation, which can be caused by environmental triggers – such as allergens, cigarette smoke and car fumes – and airways twitchiness in allergic asthma.
“It makes the cells much more sensitive to the asthma triggers – which then make an attack much more likely.” What is more, a drug already exists that can disable the CaSR protein, meaning it could be available to patients as soon as clinical trials are complete.
The medication – called a calcilytic – was developed 15 years ago to knock out the same protein in osteoporosis. Although it was shown to be safe, it was not effective for osteoporosis patients.
But early tests in mice and human tissue showed promising results as an asthma treatment.
About 5.4million people suffer from asthma in Britain. Most are able to regulate their symptoms with inhalers, but a minority – about five percent of patients – do not respond to any treatment. The team, which includes scientists from King’s College London and the Mayo Clinic in the US, hopes to use the drug in a nebuliser, in which it is turned into a mist and inhaled.
A few courses of treatment would be enough to stop asthma attacks from recurring, it is hoped.
The experts think it could also play a role in tackling chronic obstructive pulmonary disease and chronic bronchitis, for which there is no effective treatment.
Professor Riccardi said: “If we can prove that calcilytics are safe when administered directly to the lung in people, then in five years we could be in a position to treat patients and potentially stop asthma from happening in the first place.”
Dr Samantha Walker, of Asthma UK, which helped fund the research, said the breakthrough “could be life changing for hundreds of thousands of people”.
Daily Mail