Mitogen-activated protein kinases as therapeutic targets for rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease in which imbalances in pro- and anti-inflammatory cytokines promote the induction of autoimmunity, inflammation and joint destruction. Methotrexate, the standard disease-modifying anti-rheumatic drug (DMARD), has shown a gradual loss of efficacy in a significant proportion of patients, probably due to the onset of drug resistance, and thus it was hoped that the development of biologics would revolutionise RA management. Even though biologics have improved the therapy of patients refractive to DMARDs, they require parenteral administration and may leave patients open to serious infection and cancer. Therefore, attention has also been focused on inhibitors of mitogen-activated protein kinases (MAPKs), signalling enzymes that play key roles in pathogenic cytokine production, and their downstream effector pathways, in order to create safe and effective oral drugs. This article therefore provides an overview of the structure and function of MAPKs and their role in the pathogenesis of RA as context to describing the advances in the development of specific, druggable MAPK inhibitors. Their potential as therapies in the management of RA is also discussed.