Passive Smoking Weakens Children’s Response to Asthma Treatment, Study

A study shows how secondhand smoke exposure can dramatically affect response to inhaled steroid medication in asthmatic kids.

It is known that passive smoking worsens asthma symptoms in kids and also weakens their responses to inhaled steroid treatment.  But it was not known how. In the current study, researchers at Imperial College London found that exposure to secondhand smoke at home leads to lower levels of an enzyme in kids. These enzymes help kids respond to the asthma treatment.

The scientists observed that asthmatic kids that had one smoker parent at home tended to have lower levels of enzyme HDAC2 when compared to those whose parents didn't smoke. This enzyme helps the steroids apply their beneficial anti-inflammatory effects on asthma.

Professor Peter Barnes FRS, from the National Heart and Lung Institute at Imperial College London, said, "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. These findings underline the importance of legislation aimed at protecting children from being exposed to cigarette smoke. Restricting smoking in cars is a positive step, but the same should be applied in homes."

The current study included 19 kids with severe asthma and seeking treatment at the Royal Brompton Hospital, London.  Of 19, nine had parents who smoked at home and 10 belonged to non smoking households.

The researchers noticed that cells from lungs of these kids exposed to secondhand smoke had nearly half the levels of HDAC2 enzymes when compared to those who came from non smoking households.

Children with asthma who are passively exposed to cigarette smoke have the same molecular abnormalities that lead to steroid resistance in adult chain smokers," said Professor Barnes. "The mechanism we've identified will be a target for new treatments to help children with severe asthma."

Asthma, a chronic inflammation of the airways, continues to be a serious public health issue. According to the U.S. National Library of Medicine (NIH) National Institutes of Health, over 20 million people in the United States have asthma of which 9 million are children.

In order to prevent an asthma attack, the patient is given steroid treatment in the form of inhalers. But in many they aren't completely effective.

The study was published in CHEST Journal.