Scientists identify how gastric reflux may trig...( DURHAM N.C. Researchers at Duke Uni...),Health

DURHAM, N.C. Researchers at Duke University Medical Center appear to have solved at least a piece of a puzzle that has mystified physicians for years: why so many patients with asthma also suffer from GERD, or gastroesophageal reflux disease.

Clinicians first noted a relationship between the two diseases in the mid-1970s. Since then, studies have shown that anywhere from 50 to 90 percent of patients with asthma experience some aspect of GERD. But can GERD cause asthma, or, is it the other way around? Perhaps there is some shared mechanism at the root of both disorders causing them to arise together. Physicians could make a case for each scenario, but until now, the exact nature of the relationship was not clear.

Working in laboratory experiments with mice, Dr. Shu Lin, an assistant professor of surgery and immunology at Duke, discovered that inhaling tiny amounts of stomach fluid that back up into the esophagus a hallmark of GERD produces changes in the immune system that can drive the development of asthma.

In the experiments, researchers inserted miniscule amounts of gastric fluid into the lungs of mice (mimicking the human process of micro-aspiration, or breathing in tiny amounts) over a period of eight weeks. They compared these animals' immune systems with those of mice that were exposed to allergens but not the gastric fluid.

The immune systems of the two sets of mice responded very differently. Those that had the gastric fluid in their lungs developed what researchers call a T-helper type 2 response, a type of immune system reaction characteristic of asthma. The other mice responded in a more balanced manner, mounting an immune reaction consisting of both T-helper type 1 and T-helper type 2 responses.

"This is the first experimental evidence in a controlled, laboratory setting linking these two very common conditions in humans," says Lin, the senior author of the study published online in the European
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