Upsala Journal of Medical Sciences. 2010; 115: 181–186 ORIGINAL ARTICLE Persistent Chlamydophila pneumoniae infection in thoracic aortic aneurysm and aortic dissection? MARIE EDVINSSON1, STEFAN THELIN2, EVA HJELM3, GÖRAN FRIMAN1 & CHRISTINA NYSTRÖM-ROSANDER1 1Department of Medical Sciences, Infectious Diseases, Uppsala University Hospital, Uppsala University, Uppsala, Sweden, 2Department of Surgical Sciences, Thoracic Surgery, Uppsala University Hospital, Uppsala University, Uppsala, Sweden, and 3Department of Medical Sciences, Clinical Bacteriology, Uppsala University Hospital, Uppsala University, Uppsala, Sweden Abstract Objectives. Chlamydophila pneumoniae (C. pneumoniae) has been associated with atherosclerosis and abdominal aortic aneurysm and is probably disseminated by peripheral blood mononuclear cells (PBMC). Viable and metabolically active bacteria can be demonstrated by the presence of bacterial mRNA and on-going dissemination by the presence of bacteria in PBMC. The aim of this study was to determine the prevalence of C. pneumoniae DNA and mRNA in aortic biopsies and C. pneumoniae DNA in PBMC in thoracic aortic aneurysm and aortic dissection patients. Design. Real-time PCR was used to detect C. pneumoniae DNA and mRNA in biopsies and C. pneumoniae DNA in PBMC. Results. C. pneumoniae DNA was found in biopsies in 26% (6/23) of aneurysm patients and 11% (2/18) of dissection patients but in none of the forensic autopsy controls. C. pneumoniae mRNA was not found in any biopsy, and all PBMC were C. pneumoniae-negative. Conclusions. Presence of C. pneumoniae DNA but not mRNA in aortic biopsies and no evidence of C. pneumoniae in PBMC suggest that the infection in the aorta has passed into a state of persistence. Key words: Aortic dissection, Chlamydia pneumoniae, Chlamydophila pneumoniae, inﬂammation, thoracic aortic aneurysm Introduction Thoracic aortic aneurysm and aortic dissection are two major diseases affecting the thoracic aorta, both of which may cause aortic rupture. In an aortic aneu- rysm there is a dilatation of all three layers of the vessel wall, compared to aortic dissection where there is a splitting of the wall layers. The pathogenesis of most cases of thoracic aortic aneurysm and dissection is unknown, but in both diseases it is believed to involve medial degeneration leading to a weakening of the aortic wall (1). Known risk factors associated with thoracic aortic aneurysms are bicuspid aortic valve, Turner’s syndrome, and aortic arteritis (e.g. Takayashu’s arteritis and giant cell arteritis) (1). The most common associated risk factors for the development of aortic dissection are hypertension and advanced age; other risk factors are smoking, dyslipidemia, diabetes mellitus, and Turner’s syn- drome (2). Previously, a common cause of aneurysm of the ascending aorta was syphilis, which today, with declining incidence, is a rare cause. In abdominal aortic aneurysm the main factor in the pathogenesis is believed to be atherosclerosis, in contrast to thoracic aortic aneurysm where athero- sclerosis is found less often. The medial degenera- tion of thoracic aortic aneurysms has previously been described as a non-inﬂammatory disease; however, Correspondence: Marie Edvinsson, Department of Medical Sciences, Infectious Diseases, Uppsala University Hospital, S-75185 Uppsala, Sweden. Fax: +4618557301. E-mail: marie.edvinsson@medsci.uu.se (Received 10 March 2010; accepted 12 March 2010) ISSN 0300-9734 print/ISSN 2000-1967 online DOI: 10.3109/03009731003778719 2010 Informa UK Ltd. (Informa Healthcare, Taylor & Francis AS)