Reporting in the Nov. 15 issue of the New England Journal of Medicine, Yale University researchers believe that a protein that may have evolved to protect airways may be a biomarker for severe asthma.
Researchers found that people with severe asthma were more likely to have elevated levels of a protein called YKL-40 when compared to people without asthma.
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We believe that it's a marker of the inflammatory response associated with asthma," said the study's lead author, Dr. Geoffrey Chupp, an associate professor of medicine at Yale University School of Medicine. And, he added, "These new novel family of molecules could be very important in asthma pathogenesis. Down the road, there could be new treatments and new ways to characterize asthma."
HealthDay reports that:
YKL-40 is what's known as a chitinase-like protein. It attaches itself to chitin, an abundant substance found in fungi, crustaceans and in insects like dust mites and cockroaches. It's also present in the pharynx and eggs of parasitic worms called helminths. Infection with helminths used to be common but is now rare in developed countries, according to the author of an accompanying editorial in the same issue of the journal, Dr. Burton Dickey, chairman of pulmonary medicine at M.D. Anderson Cancer Center in Houston. These worms migrate through the skin into the bloodstream and travel through the lungs to get into the gastrointestinal tract, he said.
Humans don't manufacture chitin but do produce chitinases (enzymes that break down chitin) and chitinase-like enzymes (enzymes that bind to chitin, but don't break it down). The presence of chitin in the lungs may make the body believe that it has a helminth infection that it needs to defend against, Dickey said. Unfortunately, he pointed out, this defense mechanism may now be reacting to harmless dust mites instead.
The study recruited 253 adults, some with and some without asthma, and their blood samples were tested for levels of YKL-40. Results showed that those with asthma had higher levels of YKL-40 than those without. These findings could result in tests that would allow doctors to more readily diagnose asthma and potential find new ways of preventing or treating the illness.
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