RODALE NEWS, EMMAUS, PA—On Wednesday, the Environmental Protection Agency announced new rules that will require coal-burning power plants to limit emissions of toxic air pollutants that are known to exacerbate asthma. That's great news for the 8 percent of Americans who suffer from the breathing disorder. And according to a new study being presented at this week's annual meeting of the American Academy of Allergy, Asthma and Immunology, it could lead to fewer rates of other inflammatory diseases. The authors of the study found that people with asthma are more likely to suffer from cardiovascular disease, diabetes, irritable bowel disease (IBS), and rheumatoid arthritis than people with healthy lungs.
THE DETAILS: The authors used data from 2,392 people enrolled in an asthma study in Rochester, Minnesota, half of whom had asthma and the other half did not. They compared the incidence of irritable bowel disease, rheumatoid arthritis, diabetes, and coronary artery disease among those with asthma and those without, and found that with each disease, people with asthma had higher rates. The relationship was strongest with coronary artery disease, in which people with asthma had a 59 percent higher incidence, and with diabetes, in which people with diabetes had a 68 percent higher incidence. Rates of irritable bowel disease and rheumatoid arthritis also increased in asthma patients, but, says lead author Young J. Juhn, MD, pediatrician at the Mayo Clinic in Rochester, the associations weren't as strong.
WHAT IT MEANS: Though it may seem logical to think that an inflammatory condition like asthma would be accompanied by other inflammatory conditions, such as diabetes and cardiovascular disease, Dr. Juhn says his results came as somewhat of a surprise, based on the way our immune systems work. "Our immune systems have something called T-helper cells. T-helper 1 cells determine pro-inflammatory conditions, such as coronary artery disease, irritable bowel disease, rheumatoid arthritis, and diabetes, while T-helper 2 cells are considered to play a very important role in determining allergic disorders, such as asthma," he says. Because our immune systems work to maintain a balance between the two types, he adds, it would stand to reason that people with asthma would actually have lower rates of those diseases. But that's not what his study found. "At this point, we think there may be some common immune mechanisms underlying this association," he says, most likely something genetic or environmental.
Dr. Juhn's study is one of very few analyzing the relationship between asthma and other inflammatory diseases, so he says that doctors are still in the early stages of understanding what all this means, especially when it comes to solving the problem. "If we find that the association isn't genetic, then, potentially, controlling your asthma may be helpful in reducing your risk of these other pro-inflammatory conditions," Dr. Juhn says. "But if it the underlying mechanism is genetic, the association may be independent from asthma control."
Published on: March 18, 2011