Adipokines: Linking metabolic syndrome, the immune system, and arthritic diseases

Metabolic syndrome (MetS) represents a cluster of metabolic and cardiovascular complications, including obesity and visceral adiposity, insulin resistance, dyslipidemia, hyperglycemia and hypertension, which directly increase the risk of cardiovascular diseases (CVD) and diabetes mellitus type 2 (DM2). Patients with arthritic diseases, such as rheumatoid arthritis and osteoarthritis, have a higher incidence of CVD. Although recent advances in the treatment of arthritic diseases, the incidence of CVD remains elevated, and MetS has been identified as a possible link between CVD and arthritic diseases. Chronic low-grade inflammation associated with obesity has been established as a significant contributing factor to the increased prevalence of MetS. Adipokines, which play important physiological roles in metabolic activities contributing to the pathogenesis of MetS, are also involved in the regulation of autoimmune and/or inflammatory processes associated with arthritic diseases. Therefore, MetS and dysregulated secretion of pro-inflammatory adipokines have been recognized as a molecular link between CVD and arthritis diseases. In the present paper, we review recent evidence supporting the role played by adipokines, in particular leptin, adiponectin, and lipocalin-2, in the modulation of the immune system, MetS and arthritic diseases. The underlying cellular and molecular mechanisms are discussed, as well as potential new therapeutic strategies.