Chlamydia pneumoniae IgA and elevated level of IL-6 may synergize to accelerate coronary artery disease

SummaryObjectivesA strong association of cytokines [interleukin (IL)-6, IL-2 and tumor necrosis factor (TNF)-α] with atherosclerosis is well documented. However, their role in Chlamydia pneumoniae (Cp)-associated progression of coronary artery disease (CAD) is not well studied. Hence we evaluated the presence of these cytokines in CAD patients positive for Cp immunoglobulin (Ig) A (low, medium, and high levels) CAD and compared with controls. Also the physiological and baseline characteristics in IL-6 positive CAD patients were studied.MethodsDuring the period from March 2005 to June 2007, 192 CAD patients and controls attending the cardiology clinic of Safdarjung Hospital, New Delhi, India were enrolled. ELISA was performed for the estimation of Cp IgA, high sensitive C-reactive protein (hsCRP), and cytokines IL-6, IL-2, and TNF-α in CAD patients and controls.ResultsIL-6 was significantly higher in CAD patents with medium and higher Cp IgA levels (35 vs. 10 and 32 vs. 4) compared to controls. Physiological features and baseline characteristics of CAD were significantly higher in IL-6 positive CAD patients.Additionally, in CAD patients IL-6 was significantly correlated with hsCRP (p < 0.001, r = 0.42).ConclusionsOur results lead us to hypothesize the role of IL-6 in the pathogenesis of CAD, which may subsequently get accelerated through Cp infection.