Regulatory Mechanisms for Adipose Tissue M1 and M2 Macrophages in Diet-Induced Obese Mice

OBJECTIVE—To characterize the phenotypic changes of adi-pose tissue macrophages (ATMs) under different conditions of insulin sensitivity. RESEARCH DESIGN AND METHODS—The number and the expressions of marker genes for M1 and M2 macrophages from mouse epididymal fat tissue were analyzed using flow cytometry after the mice had been subjected to a high-fat diet (HFD) and pioglitazone treatment. RESULTS—Most of the CD11c-positive M1 macrophages and the CD206-positive M2 macrophages in the epididymal fat tissue were clearly separated using flow cytometry. The M1 and M2 macrophages exhibited completely different gene expression patterns. Not only the numbers of M1 ATMs and the expression of M1 marker genes, such as tumor necrosis factor- and monocyte chemoattractant protein-1, but also the M1-to-M2 rati