Association of Chlamydia pneumoniae infection and carotid intima-media wall thickness in Japanese Americans.

BACKGROUND: Chlamydia pneumoniae (Cp) infection has been proposed as a risk factor for coronary artery disease (CAD), but it remains unclear whether Cp plays a role in the progression of early stage carotid atherosclerosis.

METHODS AND RESULTS: The associations among Cp IgG/IgA antibodies, inflammation markers such as C-reactive protein (CRP) and interleukin (IL)-6, and the maximal progression of carotid intima-media wall thickness (max IMT) were evaluated using ultrasonography in 259 Japanese Americans. The presence of Cp IgG or IgA antibodies itself did not show significant correlation with max IMT after adjustment for age and sex. However, in the Cp IgG seropositive group, the subjects with high IL-6 levels showed more pronounced max IMT progression than those with low IL-6 levels after adjustment of the other CAD risk factors. Moreover, in the Cp IgA seropositive group, the subjects with high CRP or IL-6 levels had significantly higher levels of max IMT compared with those with low CRP or IL-6.

CONCLUSIONS: The results support the hypothesis that a chronic latent Cp infection with inflammation might accelerate the development of early stage atherosclerotic lesions.