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,"
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
"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
"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,"