Adipose tissue-resident macrophages and obesity

Type 2 diabetes and insulin resistance are one of the major consequences of obesity as a result of inflammation in adipose tissues. Adipose tissue-resident macrophages (ATMs) have a primary role in tissue remodeling and maintenance of homeostasis within adipose tissue. Two different types of macrophages are present in adipose tissue i.e. M1 and M2-type. Obesity is associated phenotypic transformation of macrophages, from anti-inflammatory M2 to pro-inflammatory M1 macrophages. M1-type macrophages increases in obesity and contribute to the development of type 2 diabetes and insulin resistacne. In contrast, M2 ATMs secretes anti-inflammatory cytokines and are involved in maintaining insulin sensitivity. However, little is known about the role of M2 macrophages in adipose tissue. Literature related to the role of M1 and M2 macrophages in metabolism have been reviewed in this article with emphasis on the macrophages associated with adipose tissues. Role of M2 macrophages in adipose tissues have also been highlighted in this article to enhance our knowledge and understanding of macrophages homogeneity.