Activated synovial macrophages as targets for osteoarthritis drug therapy.

The great success of targeted biologic therapy against rheumatoid arthritis (RA) in recent years has meant that much research has been devoted to investigating the pathophysiology of osteoarthritis (OA) in the hope of defining novel therapeutic targets. In contrast to RA, with its pannus and erosions, OA has long been thought of as a degenerative disease of cartilage, with secondary bony damage and osteophytes. But in recent years, the importance of the synovium, and in particular the synovial macrophages, in OA, has been highlighted in both in vitro and in vivo studies. This review will discuss the potential of synovial macrophages and their mediators, in particular the proinflammatory cytokines tumour necrosis factor alpha and interleukin-1, as potential therapeutic targets in OA.