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A Smoking Gun for Emphysema

A new blood test may detect signs of the disease before symptoms appear.
March 21, 2011

Researchers at Weill Cornell Medical College have developed a blood test that may detect early signs of emphysema. The test measures levels of tiny endothelial microparticles that slough off from capillary walls into the bloodstream. Scientists found that these circulating fragments are higher than normal in smokers who have evidence of lung destruction but who have yet to develop symptoms of emphysema. The new blood test may be a cost-effective way to catch the disease early.

“It’s easier to get people to stop smoking if they know they’re developing a disease,” says Ronald Crystal, chairman and professor of genetic medicine at the medical school, and lead author of the study. “This test tells people you are developing early emphysema, and it’s like a smoke alarm—when it goes off, it doesn’t necessarily tell you there’s a fire, but you have to pay attention to it.”

Fifteen to 20 percent of smokers develop emphysema, and the longer one smokes, the higher their risk of developing the disease. There is no cure for the disease, which, along with chronic bronchitis, contributes to chronic obstructive pulmonary disease, the fourth leading cause of death in the United States. The most effective way to halt emphysema’s progress is to stop smoking early on.

As the disease develops, it causes destruction to alveoli, the many air sacs that branch out from the lungs. These air sacs are the sites of vital gas exchange. When the lungs take in oxygen, it travels to the air sacs, into surrounding capillaries, which supply the rest of the body. Simultaneously, carbon dioxide flows from capillaries to the air sacs, and is expelled through the lungs. In emphysema, this gas exchange is severely cut off, making it difficult to breathe.

Recently, researchers found that in addition to the destruction of alveoli, emphysema may damage the surrounding network of capillaries, causing fragments of the inner lining to shed and get swept up in the bloodstream. “There have been attempts for 30 years to develop a biomarker for emphysema, but with not much success,” says Crystal. “Endothelial microparticles have been looked at for other diseases, like diabetes and heart disease, but no one has ever looked at it for emphysema.”

The findings suggest that the blood test could catch early signs of emphysema that would otherwise go unnoticed. Crystal’s group is planning to perform more tests on larger groups of participants to verify the results.

Steven Shapiro, chairman of the department of medicine at the University of Pittsburgh, says that the blood test may one day be easily integrated into a doctor’s office. “We’ve been wanting general practitioners to screen for emphysema, and it’s getting easier, but lots of patients go undiagnosed and untreated, and we don’t have any treatments that are disease-modifying yet,” says Shapiro. “Part of the reason is because we don’t have good biomarkers. So having a biomarker like this would really be beneficial.”