Obesity, adipose tissue and rheumatoid arthritis: coincidence or more complex relationship?

In the last two decades we have witnessed a boost in scientific interest and knowledge of adipose tissue biology to such an extent that it was promoted to an active endocrine organ. Adipose tissue is not just related to body weight and appetite regulation. It is also implicated in obesity, a low-grade inflammatory state, as well as inflammatory conditions including rheumatoid arthritis (RA), an autoimmune disease where anti- and pro-inflammatory cytokine balance is critical. All major adipose derived products, simply termed adipokines, like leptin, adiponectin, visfatin and resistin, reportedly participate in inflammation and immunity. In this review we explore in depth the relationship between adipose tissue and RA, with focus on possible mechanisms, beyond observations about circulating or synovial levels, and special reference to future perspectives and clinical implications.