Chlamydophila pneumoniae infection in abdominal aortic aneurysm (AAA) patients: the immunological aspect and clinical consequences

The aim of the study was to evaluate the frequency of C. pneumoniae infection in AAA patients (by measuring C. pneumoniae specific serum antibody levels), its association with the course and severity of the disease and the patients' immunological status (by measuring the concentration of IL-10, IL-12 and IFN-gamma and TNF in their sera). 52 patients operated for AAA and 30 control subjot matched for age and sex without clinical signs and symptoms of cardiovascular and pulmonary disease took part in our study. The microimmunofluorescence method was applied to evaluate the level of anti-C. pneumoniae IgG, IgA and IgM. The concentrations of cytokines were evaluated using the ELISA method. To a. significant degree serological markers indicating chronic or active C. pneumoniae infection were present-more frequently in AAA patients in comparison with healthy controls. Significant differences of IFN gamma and IL-10 levels were observed in these patients in comparison with healthy controls (decreased level of INF-gamma, increased level of IL-10); no differences of TNF and IL-12 were noted. Among AAA patients, a strong negative correlation was detected between titers of anti-C. pneumoniae antibodies and the concentrations of IL-10, IL-12, IFN-gamma and TNF. The levels of all examined cytokines were significantly lower in the active infection group in comparison with the rest of the patients. In the contact and chronic infection groups the distributions of cytokines' concentrations were similar. The significant relationship was assessed between the presence of active infection and symptomatic aneurysm. All patients in the active infection group were diagnosed as having symptomatic AAA. Active C. pneumoniae infection is associated with increased degradation of the aortic wall in AAA patients. The evaluation of anti-C pneumoniae antibodies in AAA patients can be useful in predicting the risk of aneurysm rupture.