26 Feb 1999

In the mid-1980s, Finnish researchers reported that 68 percent of heart attack patients and 50 percent of those with coronary heart disease had antibodies to the bacterium Chlamydia pneumoniae, as compared to 17 percent of healthy controls. A few years later, others discovered the pear-shaped organism in the plaque-clogged coronary arteries of heart-attack victims. And recently, a team of pathologists in Philadelphia found the bacterium in the autopsied brains of late-onset Alzheimer's disease patients. While this study needs to be replicated, it is intriguing in light of a growing body of evidence linking Alzheimer's and cardiovascular disease. In today's issue of Science, Bachmaier et al. report that Chlamydia bears on its surface a protein that closely mimics myosin, found in heart muscle. The finding suggests that a local immune response triggered by a Chlamydia infection could later spawn an autoimmune attack on the host's heart muscle. Whether a similar scenario occurs in other forms of Chlamydia infection is not yet known.—June Kinoshita