Ozone in Arteries Could be Danger Signal

Might serve as early warning of heart attack, study finds

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By
HealthDay Reporter

THURSDAY, Nov. 6, 2003 (HealthDayNews) -- Researchers say they have discovered ozone-related molecules within the fatty plaques that clog blood vessels, and their presence could warn of an impending heart attack or stroke.

The finding, reported in the Nov. 7 issue of Science by scientists at the Scripps Research Institute in California, is another indicator of the growing importance of inflammation in cardiovascular disease.

It is now believed that a heart attack or stroke can happen when an inflammatory process causes a plaque to explode, blocking and damaging an artery. The Scripps researchers have been looking at this phenomenon for years. Now they say they have detected unusual steroid compounds produced when cholesterol in plaques is attacked by immune system cells, with ozone produced as a byproduct.

The study used blood samples from eight patients whose arteries were so severely blocked by fatty plaques that they had endarterectomies, operations that increase blood flow by removing fatty deposits.

Sophisticated laboratory tests detected the ozone-related steroid molecules in six of the eight patients, the researchers report. These molecules can damage a number of different cell types found in plaque-plagued arteries, they say. The steroid molecules, which the Scripps researchers are calling "atheronals," can interact with LDL cholesterol, the "bad" kind found in plaque, to trigger cell damage in other ways, they say.

The finding "could lead to the discovery of new reaction pathways and products that are of critical importance in normal and pathological systems," they write.

"The importance of the atheronals may be as a biomarker for the severity of the disease," says Paul W. Wentworth, a senior scientist at Scripps. "As the levels of the atheronals increase, so does the risk of a serious cardiovascular event, such as a heart attack.

Dr. Richard A. Stein, associate chairman of medicine at Beth Israel Medical Center in New York City and a spokesman for the American Heart Association, calls the research interesting but early work.

The inflammation-related chemical reaction at the center of the study, the oxidation of LDL cholesterol, is "a major mechanism" in cardiovascular disease, Stein says. "The degree of the inflammatory process determines plaque stability. They are making an interesting argument that ozone may be a player in this process."

Right now, "we don't have markers of this oxidative process," Stein says. "If we could isolate byproducts of this process, they might be a very good indicator of inflammation, but we don't know if we can."

The newly reported results came from tissue scraped out of arteries by endarterectomy, Stein notes. It's not clear yet whether the same markers can be found with an ordinary blood test, he says.

"This is an important piece of information," Stein says. "But its real importance will be evident only a number of years down the road."

More information

A summary of the role of inflammation in heart disease is given by the American Heart Association. More information on cholesterol can be found at the National Library of Medicine.

SOURCES: Paul W. Wentworth, Ph.D., senior scientist, Scripps Research Institute, La Jolla, Calif.; Richard A. Stein, M.D., assistant chairman, medicine, Beth Israel Medical Center, New York City; Nov. 7, 2003, Science

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