Transcardial gradient of adiponectin, interleukin-6 and tumor necrosis factor-α in overweight coronary artery disease patients

Background: Obesity is associated with coronary artery disease (CAD), where epicardial adipose tissue (EAT) express proatherogenic cytokines (i.e., interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α)) and decreases production of beneficial adiponectin. Studies on endocrine role of EAT are mostly based on assessing cytokines' mRNAs, whereas cytokine blood levels might not readily correlate. In order to get better insight into the endocrine role of thickened EAT in CAD, we assessed transcardial gradient of adiponectin, IL-6 and TNF-α.

Methods: We assessed anthropometric and ultrasound measures in cohort of fifty nondiabetic subjects (21 CAD and 29 non-CAD). Blood sampled from aortic root and coronary sinus was assayed for adiponectin, IL-6 and TNF-α, using ELISA.

Results: Except thicker EAT in CAD subjects, anthropometric measures were similar (overweight), with higher adiponectin in coronary sinus than in aortic root (p<0.001) in both groups. CAD subjects had lower adiponectin in aortic root (p<0.001) and higher levels of TNF-α in coronary sinus than in aortic root (p=0.05). EAT thickness positively correlated with hip circumference (p=0.038) and negatively correlated with adiponectin levels (for both p<0.05).

Conclusions: Transcardial gradient of adiponectin in non-CAD and CAD overweight subjects was similar, while latter had lower systemic adiponectin level and thicker EAT. EAT with thickening reaches the threshold level of near-maximal down-regulation of adiponectin and its further thickening is not associated with continued decrease of adiponectin production. In CAD patients levels of TNF-α were higher, but IL-6 were not, and these cytokines might be flush out by lymphatic route.