Adipose Tissue and Immuno-Metabolic Regulation

Evolution has given rise to a variety of ways to store energy ranging from small intracellular lipid droplets to specialized tissue called adipose, which is composed of adipocytes, endothelial cells, and immune cells. In this chapter we will discuss two types of adipose tissue: brown adipose tissue (BAT) and white adipose tissue (WAT). For decades adipose tissue was credited as store of lipids, however more recent studies identified other functions, including the production of heat by BAT or the regulation of total body energy balance by WAT. As the incidence of obesity increased to a worldwide epidemic, the state of adipose tissue during weight gain became a topic of increased interest. It has become clear that the increase in the number and size of adipocytes during obesity is accompanied by a constellation of changes to other cell types that compose the adipose tissue environment. These changes lead to elevated inflammation and an increased risk for heart disease and type 2 diabetes. Here we will discuss the role of adipose tissue as an endocrine organ and its dysfunction during obesity. We will investigate the effect of inflammation and the different immune cells within the adipose tissue, with particular attention to macrophages. We finish with a discussion of human trials that have been applied to treat patients with type 2 diabetes and obesity.