This new effort follows nine other studies conducted by UW researchers looking at the relationship between C. pneumoniae and heart disease. They have found the organism in the diseased parts of arteries of people of different ages and ethnic backgrounds. Results have been confirmed by scientific investigators worldwide.

Professor J. Thomas Grayston. Photo by Kathy Sauber.

But it is much too early to assume C. pneumoniae is the killer, says Grayston, the founding dean of the UW School of Public Health and Community Medicine. A scientist all of his working life, Grayston remains ever skeptical and detached.

"We know that everybody has arteriosclerosis by the late teens, and we also know that C. pneumoniae is frequently found in arteriosclerotic lesions, but we don't know that it isn't coincidence," he observes.

Grayston and colleagues' early research revealed that C. pneumoniae is a kissin' cousin to the strain of Chlamydia that causes sexually transmitted disease. By culturing the throats of UW students coming to Hall Health with flu-like symptoms, Grayston found that C. pneumoniae causes nasty respiratory problems such as bronchitis and stuffed-up sinuses. It can lead to acute respiratory problems like pneumonia. The bacterium is transmitted from person to person via sneezing and coughing. Most people in the world have antibodies to C. pneumoniae, which means that most people have encountered the microbe at some time during their lives.

When C. pneumoniae settles in the body, the immune system dispatches special cells called macrophages to attack the invaders. Grayston thinks the bacteria may survive even after being "consumed" by the attacking macrophages. They may hide inside the cells and "hitch a ride" around the body, initiating damage and inflammation in the arteries or making it worse.

"We don't know how it all develops, but we do know that an arteriosclerotic lesion is an inflammatory process. The body's white blood cells are attracted to these lesions and the bacteria may travel with them. On the other hand, the bacteria may be an innocent bystander," says Grayston.

Illustration of diseased heart by Patsy Bryan. © 1996 Emory University.

The most extensive series of studies with tissue from heart arteries was done in Seattle after a South African pathologist noticed the odd, pear-shaped organism on slides of diseased heart arteries he was examining with an electron microscope. The pathologist sent the slides to Grayston, who confirmed that the organism was his old friend, C. pneumoniae. Then, Grayston studied artery tissue from 362 people, from autopsies and heart surgeries. Overall, the bacterium was found in 55 percent of patients' tissue.

Despite the potential magnitude of this discovery, getting the tissue samples so they could look at plaque in arteries wasn't always easy, says Epidemiology Professor Lisa Jackson, deputy director of the antibiotic heart study.

"Initially, there wasn't a lot of interest from potential collaborators and there was a fair bit of skepticism. But now I think the feeling is that, while we certainly haven't established the link between infection and heart disease, that it is a very active and interesting area of research," says Jackson.

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