Adipocytokines: Unravelling the Missing Link in Diabetes and Metabolic Syndrome

Adipose tissue composed of adipocytes, fibroblasts, immune cells, and various other cell types, once known as passive reservoir is now considered an endocrine organ secreting bioactive molecules including hormones now termed adipokines with various known and unknown endocrine functions in addition to regulating fat mass and nutrient homeostasis. Due to the dramatic rise in obesity and its metabolic sequelae during the past decades, adipose tissue gained tremendous scientific interest. Adipose tissue secretes variety of products known as ‘adipokines’, including leptin, adiponectin, resistin and visfatin, as well as cytokines and chemokines such as tumor necrosis factorAlpha (TNF-α), interleukin-6 and monocyte chemoattractant protein-1. These adipokines helps in the regulation of hemostasis, blood pressure, lipid and glucose metabolism, inflammation, and atherosclerosis. The release of these cytokines causes a chronic sub inflammatory state that could play a central role in the development of insulin resistance and type 2 diabetes, and the increased risk of cardiovascular disease associated with obesity, together referred as metabolic syndrome [4]. This chronic low-grade inflammation causes increase in macrophage infiltration, leads to increased adipocyte secretion of pro-inflammatory molecules such as resistin, tumor necrosis factorAlpha, and interleukin-6 (IL-6) [4]. These adipocytokines can act as key regulators of response to insulin in peripheral tissues [5]. Their role in causing insulin resistance via various mechanisms involving the flux of in prooxidant and antioxidant state has been seen [6,7]. Adipokines have a great potential for clinical use as potential therapeutics for obesity, obesity related metabolic, cardiovascular and other diseases [8]. Several extracellular factors cause obesity, related adipocyte metabolism and macrophage infiltration. Interestingly, recent research provides increasing evidence of the importance of regulating adipocyte function, adipose tissue metabolism and inflammation. In this mini review, we will briefly highlight roles of various adipokines (adiponectin, leptin, resistin, TNF-α, and IL-6) in regulating insulin sensitivity and resistance. Main Body