Chlamydia pneumoniae and atherosclerosis.

Chlamydia pneumoniae is the third species of the genus Chlamydia and has been known to cause respiratory tract infections. Since the association between the seropositivity of C. pneumoniae and ischemic heart diseases was reported in 1988, the association between C. pneumoniae and atherosclerosis has been noteworthy. Positive findings of the association between C. pneumoniae and atherosclerosis have been reported as the result of seroepidemiological surveys, histological studies to detect C. pneumoniae in human atherosclerotic tissues, and animal infection models. These data supported that C. pneumoniae infection occurs in human vascular walls and may accelerate the foam cell formation of macrophage and smooth muscle cells, and may play a causative role in atherosclerosis. Several large-scale studies of the antimicrobial prevention of secondary cardiac events are in progress. The genome projects for C. pneumoniae have recently been reported. A number of issues remain unclear, however, and further intensive research is necessary.