An model of adipose tissue-associated macrophages.

Obesity-related chronic low-grade inflammation plays a central role in the development of insulin resistance. Macrophages are key players in adipose tissue homeostasis, and their phenotypic shift from the anti-inflammatory or alternatively activated (M2) form to the pro-inflammatory, classically activated (M1) form is a hallmark of insulin resistance. However, adipose tissue macrophages (ATMs) have been identified as a distinct subpopulation of macrophages in several recent studies.