Adipokines, Nutrition, and Obesity

Abstract

The traditional view of white adipose tissue (WAT) existing solely as an energy reservoir is no longer true. Although predominantly consisting of adipocytes, WAT is also composed of preadipocytes, endothelial cells, fibroblasts, and macrophages located in the stromovascular fraction. As a result, WAT is a complex and highly active secretory organ capable of modulating appetite, energy expenditure, insulin sensitivity, endocrine and reproductive systems, bone metabolism, inflammation, and immunity. The release of adipokines and cytokines by WAT is one of the most important ways this tissue influences physiological and pathological processes throughout the body. Adipokines are biologically active mediators released from adipocytes and include proteins such as leptin, adiponectin (APN), resistin, adipsin, and visfatin, as well as factors traditionally considered as cytokines such as interleukin (IL)-6, tumor necrosis factor (TNF)-α, and others. Obesity is characterized by an increase in fat mass, which is associated with a state of chronic inflammation with macrophage infiltration of WAT and abnormal production of adipokines and cytokines. Leptin, APN, resistin, visfatin, IL-6, and TNF-α help provide a link between obesity and development of insulin resistance, impaired glucose tolerance, and Type 2 diabetes (T2D) commonly associated with obesity. How specific nutrients affect production and secretion of adipokines and WAT-derived cytokines is currentlycontroversial