Indexed on: 01 Jan '07Published on: 01 Jan '07Published in: Expert review of clinical immunology
Metabolic syndrome is a highly atherogenic state in which hyperglycemia, dyslipidemia and hypertension cluster in one individual. Intra-abdominal visceral fat accumulation plays a key role in the development of these disorders and the occurrence of metabolic syndrome. We have investigated adipocyte functions intensively in the past 10 years and have revealed that these cells act as endocrine cells secreting a variety of bioactive substances, termed adipocytokines. Among adipocytokines, tumor necrosis factor-alpha, plasminogen activator inhibitor type 1 and heparin-binding epidermal growth factor-like growth factor are produced in adipocytes as well as other organs and may contribute to the development of vascular diseases. Visfatin was identified recently as a visceral-fat-specific protein that might be involved in the development of obesity-related diseases, such as diabetes mellitus and cardiovascular disease. In contrast to these adipocytokines, adiponectin, an adipose tissue-specific, collagen-like protein, has been noted as an important antiatherogenic and antidiabetic protein or as an anti-inflammatory protein. The functions of adipocytokine secretion might be regulated dynamically by nutritional state. Visceral fat accumulation causes dysregulation of adipocyte functions, including oversecretion of tumor necrosis factor-alpha, plasminogen activator inhibitor type 1, heparin-binding epidermal growth factor-like growth factor and visfatin and hyposecretion of adiponectin simultaneously, which results in the development of a variety of metabolic and circulatory diseases. In this article, the importance of adipocytokines, focusing particularly on adiponectin, is discussed with respect to lifestyle-related diseases, such as diabetes mellitus and cardiovascular disease.