Detection of circulating Chlamydophila pneumoniae in patients with coronary artery disease and healthy control subjects

Abstract

Background: There is a long history of research suggesting that Chlamydophila pneumoniae is associated with coronary artery disease (CAD). C. pneumoniae in peripheral blood mononuclear cells (PBMCs) could serve as a risk factor for CAD if respiratory infection with C. pneumoniae spreads to atherosclerotic plaques through PBMCs or if infected plaques shed C. pneumoniae-laden PBMCs into the circulation.

Methods: PBMCs were collected from 86 case patients with abnormal coronary angiogram findings and from 91 age- and gender-matched healthy control subjects. The healthy control subjects were strictly defined as not having atherosclerosis on the basis of absence of both clinical atherosclerotic disease and traditional risk factors for CAD. PBMCs were probed for the presence of C. pneumoniae nucleic acid by 2 separate real-time polymerase chain reaction (PCR) assays that used primers for outer membrane protein A (ompA) and 16S ribosomal RNA. C. pneumoniae serologic findings were determined for both case patients and control subjects.

Results: Despite serologic findings indicating past exposure to C. pneumoniae (immunoglobulin G titer, >or=1:16) in 74% of case patients with CAD and control subjects, no C. pneumoniae DNA or RNA was detected in PBMCs from any of the case patients or control subjects, including a subset of 42 participants (18 with CAD) who had samples obtained serially over 8 months. Multiple laboratory controls, including controls for inhibition of PCR, produced expected results.

Conclusions: The uniformly negative results with use of highly sensitive methods are in contrast to much of the published literature. Probing of PBMCs for the genes of C. pneumoniae does not appear useful as a noninvasive way of detecting the presence of C. pneumoniae in atheromatous lesions.