Scientists Find Asthma-Obesity Hormone Link

LONDON ~ British scientists said this week they had found a link that could explain why obese people are up to twice as likely to have asthma.

And the possible answer is not simply that people with asthma have more trouble exercising, according to the researchers.

Experts from King’s College and Imperial College, London, have discovered a protein which increases appetite in cells closely associated with asthma.

“We know that people who are obese often find it harder to manage their asthma symptoms and may even respond less well to their asthma treatments,” said Jenny Versnel, Asthma UK’s executive director of research and policy.

“This research is important because it could potentially help some people with asthma to gain more effective control of their condition.”

Both asthma and obesity are on the increase in the West, raising interest in possible connections between the conditions.

The new study pinpoints the link as lying in the molecules produced by so-called Th2 immune system cells.

Th2 cells, reacting to irritants like grass pollen, house dust mites and pet allergens, cause inflammation in the lungs and produce proteins which contribute to the development of asthma.

And the researchers demonstrated, for the first time, that Th2 cells also produce a protein, encoded by the gene PMCH (pro-melanin-concentrating hormone), which is known to increase appetite.

“Our study provides evidence for a possible mechanism linking obesity and asthma,” said the lead researcher, Dr David Cousins of King’s College.

“However, as people with asthma aren’t always obese, we now plan to look at possible genetic polymorphisms, or variations, of PMCH to see the role they play.”

Professor Tak Lee, director of the MRC-Asthma UK Centre, added: “Obesity and asthma are major health problems and clarifying the mechanisms responsible for their linkage provides important potential new opportunities for management of both conditions.”

Since 1980, obesity rates in Britain had risen from six percent in men and eight percent in women to 23 percent in both sexes by 2004, The Guardian newspaper reported.

The number of people with allergies in Britain has risen approximately three-fold in the last 20 years and the country has one of the highest rates of asthma in Europe, said the researchers.

There is a person with asthma in one in five households in Britain, the Asthma UK charity said.

The report was published by the journal Proceedings of the National Academy of Sciences.

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