The role of adenosine receptors in rheumatoid arthritis.

Rheumatoid arthritis (RA), is the most common inflammatory musculoskeletal disease inducing diminished quality-of-life in the affected individuals and having major impact on society due to decrease work ability. Early diagnosis and immediate, effective therapy are crucial in order to prevent unfavorable outcome. Treatment of RA has progressed during the past two decades thanks to the advent of a large number of new agents targeting different specific molecules and pathways involved in the modulation of the inflammation. In this scenario an important role is covered by adenosine, a purine nucleoside released from a variety of cells in response to metabolic and inflammatory stress, which is considered to be a potent endogenous regulator acting through its interaction with 4 cell surface receptors named as A(1), A(2A), A(2B) and A(3). Adenosine receptor stimulation has complex effects on the release of pro-inflammatory cytokines depending on selective receptor engagement. Recent data show the involvement of adenosine pathways in RA and its potential therapeutic implications.