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WASHINGTON (AP) - Vaccine used to prevent pneumonia may also have benefits for the heart, new research indicates.

Mice vaccinated using a bacteria that is a common cause of pneumonia developed high levels of an antibody that slows or halts the progression of heart disease, researchers working in California and Finland found.

Trials are under discussion to see if the same response occurs in larger animals, says Gregg J. Silverman of the University of California, San Diego, a co-author of the study.

"If we can harness this potential, we may have new ways to treat patients with heart disease, as well as the possibility of developing a vaccine for our children to prevent this disease from ever developing in their later years," Silverman said.

But the situation is far more complicated in humans than mice, said university colleague Joseph J. Witztum, a co-author of the paper.

Immunizing mice with pneumococcus leads to the generation of antibodies that the researchers believe lead to the protection from heart disease, he said. "We do not yet know if such a dominant and important response occurs in people."

The mouse vaccine is not the same as that used in humans. It was designed to increase production of particular antibodies that can affect the heart.

"New formulations for (human) clinical use would be required," Silverman said, "but such a vaccine should be straightforward to develop and test."

Dr. William Schaffner, head of preventive medicine at Vanderbilt University School of Medicine, welcomed the findings.

"Is this provocative? Yes," said Schaffner, who was not involved in the research. "This is exceedingly provocative and I hope it stimulates all kinds of work, not only by this group but also by industry.

"Wouldn't it be marvelous if one could develop a vaccine that not only protected against pneumococcus but also offered, simply by biological chance or fluke, the added advantage of offering some protection against atherosclerosis."

The findings, reported in Monday's online issue of the journal Nature Medicine, come a month after other researchers reported that, among 286,000 older people, hospital stays for heart disease or stroke during two flu seasons were substantially reduced for those who got flu shots.

Mice and humans with atherosclerosis - in which deposits build up inside blood vessels - often have high levels of antibodies that target the diseased areas in their blood vessels, Silverman said.

When researchers analyzed the antibodies, they "were surprised to discover that some of these antibodies were exactly identical to antibodies that were known to also protect mice from bacterial infections," Silverman said.

"This led us to wonder whether the same antibodies might be important for defense from common infections, and for defense from what is now the most common lethal disease" in the United States, heart disease.

So the team fed mice a high-cholesterol diet for 24 weeks and then checked their arteries for the development of deposits.

Mice getting repeated injections of the pneumonia vaccine showed a 21 percent reduction in the atherosclerosis in their aortas, compared with mice not vaccinated.

"We believe that the pneumococcal vaccinations in our studies induced antibodies that removed the lipids and cell breakdown products, preventing their deposition in the critical arteries," Silverman said.

He said the body's immune system is probably always working to protect against this disease and the vaccinations may be a way to boost the efficiency of this natural defense.

Copyright 2003 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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