Chlamydia pneumoniae infection in abdominal aortic aneurysm patients

Abstract

Introduction. Infection with Chlamydia pneumoniae, a common human respiratory pathogen, has been recently associated with cardiovascular syndromes, such as myocardial infarction, stroke, atherosclerosis and abdominal aortic aneurysm (AAA). According to the literature data significantly high percentage of AAA patients exhibited serological markers of persistent C. pneumoniae infection. Chronic infection with intracellular pathogen such as C. pneumoniae may indicate down-regulated cell-mediated immune response. Objectives. The aim of our study was to evaluate the frequency of C. pneumoniae infection in AAA patients by measuring C. pneumoniae specific serum IgG, IgM and IgA levels and their cell-mediated response by measuring the concentrations of IL-12 and IFN-g in patients' sera.
Material and methods. 28 patients operated for AAA (5F, 23M, mean age 68.5 years) and 20 control subjects matched for age and sex (4F, 16M) without clinical signs and symptoms of cardiovascular and pulmonary disease took part in our study. Microimmunofluorescence method has been applied to evaluate the level of anti-C. pneumoniae IgG, IgA and IgM. Chlamydia pneumoniae micro-IF test (Labsystem) has been used. The concentration of cytokines was evaluated using ELISA method by OptEIA set (Pharmingen). The results were evaluated by means of STATISTICA programme and considered statistically significant when p < 0.05.
Results. Serologic markers of persistent C. pneumoniae infection were detected in 25/28 (89.3%) patients and in 6/20 (30%) healthy controls. In 40% (10/25) of patients with serologic markers of persistent C. pneumoniae infection we have observed high titers of specific IgG and IgA. Mean concentrations of IL-12 and IFN-g were significantly decreased in this group of patients.
Conclusions. Our study confirms that persistent C. pneumoniae infection occurs significantly more frequently in AAA patients than in healthy controls. In 40% of patients, high titers of specific IgG and IgA may indicate active infection. Simultaneous low concentrations of cytokines promoting Th1 type response, namely IL-12 and IFN-g, in this group can indicate lack of protection against intracelluar pathogens such as C. pneumoniae. Interestingly, all patients in this group were diagnosed as having symptomatic AAA.