Adipose-Tissue Macrophage Diversity and Functions

Macrophages are the predominant immune cell type found in adipose tissue (AT). They play a critical role in tissue homeostasis and participate in metabolic regulation. In white adipose tissue (WAT), studies show that multiple macrophage subsets co-exist in the very same microenvironment. Yet these cells express selective membrane markers, allowing for identifying several well-distinguished populations. In the present review we discuss the diversity and functions of white-adipose-tissue macrophages. We summarize current knowledge regarding the intratissue distribution of macrophage populations and their specific association with stromal cells and discuss the mechanisms governing adipose-tissue macrophage generation and survival. We emphasize the central role of adipose-tissue macrophages in handling local lipid levels. A particular focus is placed on the recently described population of lipid-associated macrophages (LAMs), particularly abundant in adipose tissue during obesity development.