A new study has found that children exposed to cigarette smoke at home have lower levels of an enzyme that helps them respond to asthma treatment.
Passive smoking is known to worsen asthma symptoms in children and impair their response to inhaled steroid treatment, but how this effect occurs was not known.
Researchers at Imperial College London found that children with severe asthma with a parent who smokes at home have lower levels of the enzyme HDAC2 compared with those whose parents don't smoke.
HDAC2 is required for steroids to exert their beneficial anti-inflammatory effects in asthma.
"The mechanism we've identified makes children less sensitive to inhaled steroid treatment, so they suffer more symptoms and might have to take higher doses of steroids, which may lead to side effects," professor Peter Barnes FRS, from the National Heart and Lung Institute at Imperial College London, said.
The study was published in the journal Chest.
