Unbalanced M1/M2 Phenotype of Peripheral Blood Monocytes in Obese Diabetic Patients

The monocyte-macrophage system exists in at least two distinct phenotypes of differentiation: proinflammatory (M1) and anti-inflammatory (M2) (1,2). Macrophages, when infiltrated into obese adipose tissue, exhibit a phenotypic switch from M2 to M1 polarization, thereby contributing to obesity-induced adipose tissue inflammation and insulin resistance (1). Expression of both M1 and M2 markers is detected in circulating peripheral blood mononuclear cells as well as in atherosclerotic plaques (3). However, there have been no detailed studies on the M1/M2 phenotype of monocytes and their association with cardiovascular risks in obese subjects with type 2 diabetes. On the other hand, we demonstrated that pioglitazone, a thiazolidinedione class of insulin sensitizer, exerts an antiatherogenic effect independent of its antidiabetic effect …