Multiple infections in carotid atherosclerotic plaques

Background Chlamydia pneumoniae, cytomegalovirus, herpes simplex virus, and recently, periodontal disease, have been associated with human atheroscler osis. Porphyromonas gingivalis and Streptococcus sanguis are major pathogen s associated with periodontitis, a common chronic inflammatory condition in adults. investigators have found that these infectious agents may influenc e vascular cell functions by inducing thrombus formation, vascular cell pro liferation, apoptosis, and cell death. Methods and Results The main purpose of our study was to investigate the re lation between the presence of multiple infectious agents in human carotid endarterectomy specimens and pathoanatomic features of the corresponding ca rotid plaques. Histologically, plaque rupture of the fibrous cap and commun ication of the luminal thrombus with the central necrotic lipid core was se en in or at proximity to the macrophage-rich shoulder (unstable plaque regi on). Thrombus within the lipid core without plaque rupture was occasionally found near the internal elastic lamina, associated with increased vascular ity and lymphocytic infiltrate. Apoptosis, as detected by both the immunohi stochemical staining of apoptosis-related proteins and in situ labeling of internucleosomally degraded DNA, was common in atherosclerotic plaques. Imm unostainings for C pneumoniae, cytomegalovirus, herpes simplex virus-1, P g ingivalis; and S sanguis were positive in the carotid plaques. From 1 to 4 organisms were found in the same specimen. The micro-organisms were immunol ocalized in plaque shoulders and lymphohistiocytic infiltrate, associated w ith ulcer and thrombus formation, and adjacent to areas of strong labeling for apoptotic bodies. Conclusions Our data provide evidence that multiple infectious agents may b e found in atherosclerotic plaques, and sometimes in the same specimen; The current study is the first to report the detection of 2 major odontopathog ens, P gingivalis and S sanguis, in atherosclerotic plaques. The immunoloca lization of these micro-organisms within unstable plaque regions and their association with plaque ulceration, thrombosis, and apoptosis in vascular c ells are intriguing. Multiple infectious agents may alter vascular cell fun ction and provide a "trigger" for acute ischemic stroke events. Further evi dence from human studies and animal models will be needed.