Adipose Tissue: The New Endocrine Organ? A Review Article

Fat is either white or brown, the latter being found principally in neonates. White fat, which comprises adipocytes, pre-adipocytes, macrophages, endothelial cells, fibroblasts, and leukocytes, actively participates in hormonal and inflammatory systems. Adipokines include hormones such as leptin, adiponectin, visfatin, apelin, vaspin, hepcidine, chemerin, omentin, and inflammatory cytokines, including tumor necrosis factor alpha (TNF), monocyte chemoattractant protein-1 (MCP-1), and plasminogen activator protein (PAI). Multiple roles in metabolic and inflammatory responses have been assigned to adipokines; this review describes the molecular actions and clinical significance of the more important adipokines. The array of adipokines evidences diverse roles for adipose tissue, which looms large in the mediators of inflammation and metabolism. For this reason, treating obesity is more than a reduction of excess fat; it is also the treatment of obesity's comorbidities, many of which will some day be treated by drugs that counteract derangements induced by adipokine excesses.