Unexpected cause of asthma in childhood

It’s one of asthma’s biggest causes and can begin in babies, but doctors did not know why – and therefore how to prevent it – until now.

A crucial link between antibiotics and developing asthma has been unveiled, after Melbourne scientists found the answer to a decades-long mystery.

The unexpected discovery could pave the way for lifesaving, preventive treatments, with antibiotic exposure as a baby or toddler one of the biggest risk factors for asthma.

A Monash University preclinical study found the drug sets off a series of events that ultimately damage some of babies’ key lung cells, after beginning in their gut.

Antibiotics have been linked to asthma — which impacts 2.7 million Australians — and gut health for years, but researchers had no idea why patients were predisposed to asthma until now.

Asthma impacts 2.7 million Aussies.

Research lead Professor Benjamin Marsland said they discovered a type of bacteria in our gut was responsible for producing a special molecule which protects babies’ airways.

“Antibiotics deplete certain types of ‘good’ bacteria’,” he said.

He said when this molecule-making bacteria was killed by antibiotics, important cells found in the lining of our airways were left unprotected and “critically changed” for life.

“That was really surprising to us, and something we never could have predicted,” he said.

“This molecule, IPA, turns out to protect … these cells in the lungs as they are developing.”

He said the damage was in the cells’ “powerhouses” and did not go away once the bacteria returned to normal levels.

“That’s why it’s more prone to driving inflammation throughout the rest of the life,” he said.

“Everything else looks normal.”

He said they had spent “years trying to find” the culprit behind the antibiotic-asthma link and believed a dietary supplement containing IPA – and given alongside antibiotics to young children – could now be a potential fix.

“We’ve identified a natural product, which we know is safe, that’s produced by certain types of bacteria,” he said.

Any fix would not eliminate all cases of asthma, as there have been other risk factors, but Dr Marshland said this was “one of the strongest” causes and hoped to secure philanthropic funding for human trials.

He said while more research on the subject was needed, he suspected antibiotics’ biggest impact on the lungs was in the first year of life, and preventive treatments would likely not be needed after the age of three.

Their preclinical trials, published in Immunity journal on Tuesday, found asthma-susceptible young mice were protected when given IPA dietary supplements alongside antibiotics.

Prof Marsland said this research absolutely did not mean that babies should avoid antibiotics.

“Antibiotics are one of the most important advances in healthcare that we’ve ever had and they’ve saved so many lives,” he said.

National Asthma Council Australia director and respiratory physician Professor Peter Wark said the study suggested “even short term use” of antibiotics in babies “alters the bacteria within the gut”.

“We still know relatively little about what causes people to develop asthma,” he said.

“This important work from investigators at Monash University helps us better understand.”