Leptin linked to asthma in women

By Anthony J. Brown, MD

NEW YORK (Reuters Health) - High levels of leptin, an inflammatory compound produced by body fat, may raise the risk of asthma in premenopausal women, new research suggests.

However, levels of leptin have little to do with the well-described association between obesity and asthma.

Because previous reports have linked leptin levels with asthma in children, Dr. Akshay Sood, from Southern Illinois University School of Medicine in Springfield, and colleagues decided to see if it held true in adults as well.

Using data from 5876 participants in the Third National Health and Nutrition Examination Survey, the researchers found that elevated leptin levels did, in fact, correlate with doctor-diagnosed asthma in adults. This association was stronger in women than in men and stronger in premenopausal women than in postmenopausal women.

Consistent with earlier reports, body mass index (BMI) -- a measure of weight in relation to height -- was directly linked to asthma risk. Taking leptin levels into account had very little effect on this association, according to the team's report in the medical journal Thorax.

"The results support an association between leptin levels and asthma in women," but the study cannot prove cause-and-effect, Sood told Reuters Health. Still, "there is evidence from animal studies that leptin plays a pro-inflammatory role in the airways."

The investigator explained that the "mechanical effects of obesity seem to play a big role in asthma, so we weren't surprised that leptin levels had very little effect on the association."

Sood said his group is now planning to investigate the roles of other fat-produced compounds in the development of asthma. A prime focus will be on adiponectin, an anti-inflammatory protein that may counter the effects of leptin, he added.

SOURCE: Thorax, April 2006.