ADIPOKINES – Significance for insulin Resistance and the Metabolic Syndrome

Until recently, adipose tissue has been considered to be a mere storage compartment of triglycerides. It is now clear that adipocytes are highly active endocrine cells that play a central role in overall energy homeostasis and are important contributors to some aspects of the immune system. They do so by influencing systemic lipid homeostasis, but also through the production and release of a host of adipocyte‐specific and adipocyte‐enriched hormonal factors, cytokines and extracellular matrix components (commonly referred to as “adipokines”). Adiponectin and resistin are adipokines implicated in affecting insulin sensitivity. Adiponectin and resistin have complex quartenary structures. In the context of cardiovascular disease, major anti‐inflammatory and anti‐atherogenic properties have been attributed to adiponectin. Adiponectin circulates in at least three distinct forms in plasma, a trimer, a low molecular weight hexamer (LMW) and a high molecular weight form (HMW). Mounting evidence highlights the HMW form as the most bioactive physiological form of the protein. The most potent pharmacological intervention that results in an increase of adiponectin levels in vivo found to date is the treatment with PPAR□amma agonists. Secretion and clearance of these different complexes are highly regulated. Supported by R01‐ DK55758