Adenosine and adenosine receptors in rheumatoid arthritis

Rheumatoid arthritis is one of the most important chronic, progressive and disabling inflammatory diseases characterized by joint destructive process associated with synovial proliferation and secretion of high levels of proinflammatory mediators including cytokines and growth factors. Early diagnosis and effective therapy are crucial in order to prevent unfavorable outcome with joint deterioration and functional disability. Treatment of rheumatoid arthritis has progressed thanks to the advent of biologic drugs targeting different specific molecules and pathways involved in the inflammation. Considerable advances could be achieved in the identification of novel inflammatory biomarkers, good predictors of outcome. Adenosine, a well-known purine nucleoside interacting with A1, A2A, A2B and A3 adenosine receptors, is a potent endogenous inhibitor of inflammatory processes involved in the pathophysiology of a variety of CNS and peripheral diseases. As a consequence, selective agonists and/or antagonists of adenosine receptors could be useful in the treatment of chronic inflammatory diseases such as rheumatoid arthritis, as they are already in other disorders in which inflammatory status is a clinical feature.