Relation of chlamydia pneumoniae IgG antibodies to serum interleukin-6 levels in patients with unstable angina and acute myocardial infarction

The aim of this study was to confirm the role of Chalmydia pneumoniae [C pneumoniae] infection in acute myocardial infarction [AMI] and unstable angina, to find possible relations between high levels of interleukin-6 [IL-6], C-reactive protein [CRP], lipid profile and C pneumoniae, and to interrelate these data with the pathogenesis of acute coronary syndromes. A group of 25 patients with AMI, a group of 25 patients with unstable angina, and 13 members of a healthy control group matched for age, sex, and main coronary risk factors were included in the study. In this study, sera were examined by an enzyme-linked immunosorbent assay [ELISA] for IgG antibodies to C pneumoniae. Also, we measured the levels of IL-6 by ELISA. Patients with AMI had highly significant increase in IL-6 levels and CRP levels compared with unstable angina patients [P < 0.001]. Patients seropositive to C pneumoniae had highly significant atherogenic changes in different parameters of lipid profile compared with patients seronegative to C pneumoniae [P < 0.001]. A very high significant linear correlation was found between IL-6 levels and CRP, high density lipoprotein-cholesterol [HDL-c], low density lipoprotein-cholesterol [LDL-C] levels in the AMI and unstable angina patients [tb = 0.649, - 0.466, 0.474 respectively]. A high significant linear correlation was found between IL-6 levels and triglyceride [TG] levels in AMI and unstable angina patients [tb = 0.326]. A good significant linear correlation was also found between IL-6 levels and total cholesterol in the AMI and unstable angina patients [tb = 0.269]. Patients seropositive to C pneumoniae had highly significant increase in CRP and IL-6 [P < 0.001] compared with patients seronegative to C pneumoniae. IL-6, a proinflammatory and prothrombotic cytokine, was significantly elevated in AMI and unstable angina particularly in patients with serological evidence of C pneumoniae. Also patients with C pneumoniae had an atherogenic lipid profiles with significantly elevated CRP levels as a part of acute phase response. These effects appear to be mediated by cytokines like IL-6, since a significant linear correlation was found between IL-6 and measured lipid parameters in this work