Inability to handle environmental exposures may cause asthma

 Inability to handle environmental exposures may cause asthmaWashington, May 17: A new study by the Shanghai Women''s Health Asthma and Allergy has suggested that an impaired ability to handle oxidative stress that arises from exposure to secondhand smoke and other environmental triggers may contribute to the development of asthma.

The results suggest regulating the body''s antioxidant defense system may play an important role in asthma prevention.

"We found that the host antioxidant defense system is compromised among those destined to develop asthma, and therefore these individuals may be less able to handle environmental exposures that may cause asthma," said study author Emma Larkin, research assistant professor at Vanderbilt University Medical Center.

The researchers collected data from 65,732 women with no history of asthma who completed standardized questionnaires about asthma diagnoses and symptoms on two occasions following enrollment.

From this group, the researchers selected 150 women with confirmed new development of asthma and 294 healthy controls. Levels of antioxidants and other enzymes associated with oxidative stress were measured from blood and urine samples prior to asthma development.

Questionnaire data indicated 96 percent of the women were never-smokers and 44 percent were exposed to secondhand smoke through husbands or workplace exposure.

"Exposure to secondhand smoke increases the risk of asthma, and we believe that our ability to combat the detrimental effects of environmental exposures such as secondhand smoke through antioxidant enzyme defense is very important," Larkin said.

The researchers found that increased host antioxidant defense enzyme activity measured prior to disease onset was associated with a reduction in risk of asthma. Specifically, high levels of an enzyme that prevents the formation of platelet-aggregating factor (PAF), which is linked with asthma, were associated with a decreased risk of asthma.

The study will be presented at the ATS 2011 International Conference. (ANI)