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Front Immunol. 2016 Jan 5;6:637. doi: 10.3389/fimmu.2015.00637. eCollection 2015.

The Macrophage Switch in Obesity Development.

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Department of Immunology, Institute of Biomedical Science, University of São Paulo , São Paulo , Brazil.
Department of Immunology, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil; Division of Nephrology, Department of Medicine, Federal University of São Paulo, São Paulo, Brazil; Laboratory of Renal Physiology (LIM 16), Department of Medicine, University of São Paulo, São Paulo, Brazil.
Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School , Boston, MA , USA.


Immune cell infiltration in (white) adipose tissue (AT) during obesity is associated with the development of insulin resistance. In AT, the main population of leukocytes are macrophages. Macrophages can be classified into two major populations: M1, classically activated macrophages, and M2, alternatively activated macrophages, although recent studies have identified a broad range of macrophage subsets. During obesity, AT M1 macrophage numbers increase and correlate with AT inflammation and insulin resistance. Upon activation, pro-inflammatory M1 macrophages induce aerobic glycolysis. By contrast, in lean humans and mice, the number of M2 macrophages predominates. M2 macrophages secrete anti-inflammatory cytokines and utilize oxidative metabolism to maintain AT homeostasis. Here, we review the immunologic and metabolic functions of AT macrophages and their different facets in obesity and the metabolic syndrome.


adipokines; adipose tissue; adipose tissue inflammation; insulin resistance; macrophage; macrophage polarization; obesity

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