Enhanced inflammation in epicardial fat in patients with coronary artery disease

It has been hypothesized that epicardial fat, a local visceral fat depot with close proximity to coronary arteries, may serve as a source of inflammatory cytokines and cells in coronary atherosclerotic lesions. Here, we characterized infiltration of inflammatory cells and expression of adipocytokines in epicardial adipose tissue in patients with and without coronary artery disease (CAD). Pare samples were obtained from epicardial and subcutaneous adipose tissue during elective cardiac surgery (CAD, n = 8; non-CAD, n = 9). Inflammatory cell infiltration was investigated by immunohistochemical staining using antibodies against CD3, CD4, CD8 and CD68. Expression of adipocytokines was evaluated by real-time quantitative reverse transcription-polymerase chain reaction. Infiltration of macrophages and CD8-positive T cells in the epicardial adipose tissue in the CAD group was greater than that in the non-CAD group. In contrast, there was no significant difference between the two groups in the number of inflammatory cells in subcutaneous adipose tissue. No statistical difference could be found between the CAD group and the non-CAD group in the expression levels of adiponectin and inflammatory cytokines in epicardial adipose tissue. Our findings suggest that inflammatory cell infiltration is enhanced in epicardial adipose tissue, but not in subcutaneous fat, in patients with coronary artery disease. Chronic inflammation in epicardial fat may influence the pathogenesis of coronary atherosclerosis.