The purpose of this report was to assess the link between macrophage polarization in epicardial adipose tissue and atherosclerosis in patients with coronary artery disease (CAD).

Macrophage accumulation enhances chronic inflammation in adipose tissue, but macrophage phenotypic change in human epicardial adipose tissue and its role in atherogenesis are unknown.

Samples were obtained from epicardial and subcutaneous adipose tissue during elective cardiac surgery (CAD, n = 38; non-CAD, n = 40). Infiltration of M1/M2 macrophages was investigated by immunohistochemical staining with antibodies against CD11c and CD206, respectively. Expression of pro- and anti-inflammatory adipocytokines in adipose tissue was evaluated by real-time quantitative polymerase chain reaction.

Infiltration of macrophages and expression of pro- and anti-inflammatory cytokines were enhanced in epicardial fat of patients with CAD compared with that in non-CAD patients (p < 0.05). The ratio of M1/M2 macrophages was positively correlated with the severity of CAD (r = 0.312, p = 0.039). Furthermore, the expression of pro-inflammatory cytokines was positively correlated, and the expression of anti-inflammatory cytokines was negatively correlated with the ratio of M1/M2 macrophages in epicardial adipose tissue of CAD patients. By contrast, there was no significant difference in macrophage infiltration and cytokine expression in subcutaneous adipose tissue between the CAD and non-CAD groups.

The ratio of M1/M2 macrophages in epicardial adipose tissue of CAD patients is changed compared with that in non-CAD patients. Human coronary atherosclerosis is associated with macrophage polarization in epicardial adipose tissue.