A respiratory story: mould that causes asthma grows inside asthma patients' lungs
Asthma is one of the commonest long-term medical conditions, affecting one in twelve adults and one in eleven children. The precise cause is not known but the triggers certainly are: tobacco smoke, pollen, dust mites, animal fur and mould spores are among the chief culprits.
One of the commonest asthma-inducing moulds, found in soil, rotting matter and, frankly, pretty much anywhere that hasn't had a good scrub, is Aspergillus fumigatus. And trying to avoid it isn't easy because once it gets into your lungs, it can actually grow there.
Warning: from hereon, there will be frequent use of the word 'sputum'.
Now a study by researchers from the Institute of Lung Health, hosted here at the University of Leicester, has indicated for the first time a clear relationship between levels of A fumigatus in sputum and lung health as measured using a thing called FEV1.* Their research has shown that mould growth within lungs is much more common than previously thought.
Professor Andrew Wardlaw and his team, in collaboration with colleagues at Glenfield Hospital in Leicester, examined 79 patients who presented with asthma, half of whom were sensitive to A fumigatus, indicated in raised levels of immunoglobulin E (IgE).
Although a relationship between A fumigatus in lungs (as evidenced by its presence in sputum) and airway restriction was known to exist, it was thought to be a specific characteristic of a particular type of asthmatic condition, allergic bronchopulmonary aspergillosis (ABPA), found in about 8% of asthma patients and about 13% of cystic fibrosis patients.
The Leicester team's research, published this month in the American Journal of Respiratory and Critical Care Medicine, found significant levels of the mould in sputum from 60% of the A fumigatus-IgE sensitive patients, even though only four patients were classified as having ABPA. Consequently Wardlaw et al suggest that A fumigatus in sputum should be considered indicative not of ABPA but of AFAA or A fumigatus-associated asthma.
(The results also suggest that detection of the mould in sputum may be dependent to some extent simply on the method of analysis. Conventional analysis uses a small sample mixing sputum and saliva whereas this research studied larger volumes of sputum which had been separated from the patients' saliva.)
This is just one example of the medical research going on all the time at the University of Leicester. While something as apparently simple as formalising a relationship between a substance in a bodily fluid and a related health condition might not sound earth-shattering, it is another step in the global progress towards understanding and effectively combatting a condition which affects 5.4 million people in the UK alone.
- University press release
- IgE Sensitization to Aspergillus fumigatus is associated with reduced lung function in asthma (doi: 10.1164/rccm.201001-0087OC)
*Actually it's measured using a thing called a spirometer which gives a reading of FEV1 or Fixed Expiration Volume in One Second.