Cytokines in rheumatoid arthritis - shaping the immunological landscape.

Cytokine-mediated pathways are central to the pathogenesis of rheumatoid arthritis (RA). The purpose of this short Opinion article is to briefly overview the roles of cytokine families in the various phases and tissue compartments of this disease. In particular, we consider the combinatorial role played by cytokines in mediating the overlapping innate and adaptive immune responses associated with disease onset and persistence, and also those cytokine pathways that, in turn, drive the stromal response that is critical for tissue localization and associated articular damage. The success of cytokine inhibition in the clinic is also considerable, not only in offering remarkable therapeutic advances, but also in defining the hierarchical position of distinct cytokines in RA pathogenesis, especially IL-6 and TNF. This hierarchy, in turn, promises to lead to the description of meaningful clinical endotypes and the consequent possibility of therapeutic stratification in future.