The role of macrophages in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a common autoimmune chronic inflammatory joint disease, characterized by macrophage and lymphocyte infiltration, proliferation of synovial fibroblasts, and joint destruction. Macrophages are critically involved in the pathogenesis of RA. Not only do they produce a variety of pro-inflammatory cytokines and chemokines, but they also contribute to the cartilage and bone destruction in RA through multiple mechanisms. Macrophage activation by several distinct mechanisms is crucial for their function. This review will discuss several aspects of macrophage function in RA, including the mechanisms for macrophage activation, the signaling pathways in activated macrophages, and the mechanisms that inhibit apoptosis in macrophages in the rheumatoid joints.