[Chlamydophila pneumoniae: from its proteomics to arteriosclerosis]

Chlamydophila pneumoniae is a highly prevalent intracellular human pathogen with a unique biphasic life cycle. It is a common cause of upper respiratory infection and pneumonia, and is currently being studied as a potential risk factor for the development of atherosclerotic cardiovascular disease. The outer membrane surface antigens of C. pneumoniae are highly complex: some, such as the major outer membrane protein, are specific, but poorly immunodominant, whereas others have stronger immunogenicity, but are cross-reactive among Chlamydia species. Therefore, new, highly immunodominant, species-specific antigens should be sought. In this regard, the polymorphic membrane proteins (PMPs) are a) unique to Chlamydiae, b) often exposed on the surface of the bacteria, and c) highly immunogenic; these factors make them potential candidates for application in laboratory assays. Other chlamydial antigens, such as heat shock protein (HSP) 60, have been associated with atherosclerotic lesions because of their ability to induce an immunological attack on the endothelial wall. Over the last decade, several studies have suggested a potential role of chronic C. pneumoniae infection in human atherosclerosis. Nevertheless, prospective studies with sufficiently large samples and a healthy comparison group, using a combination of direct and indirect microbiological techniques in the same subject and sample, are needed to establish a relationship between the infection and disease activity.