Macrophage Subsets in Immune-Mediated Inflammatory Disease: Lessons from Rheumatoid Arthritis, Spondyloarthritis, Osteoarthitis, Behets Disease and Gout

Macrophages are a major cell population in most of the tissues, and their numbers increase massively in in- flammation, in wound healing and in tumors. In particular, macrophages contribute to autoimmune events in rheumatic diseases, such as rheumatoid arthritis (RA) or spondyloarthritis (SpA), mainly acting as antigen-presenting cells and also as the major source of inflammatory mediators that are important in joint inflammation. In this respect, macrophages re- lease a variety of pro-inflammatory cytokines and chemokines and events downstream of this cytokine cascade will con- tribute to cartilage and bone destruction. It is becoming clear that differential macrophage activation by distinct mecha- nisms is crucial for their function. This review will discuss several aspects of macrophage function in immune-mediated inflammatory disease with particular emphasis in RA, SpA, osteoarthitis, Behcet's disease and gout.