Cytokine pathways driving diverse tissue pathologies in rheumatoid arthritis.

Rheumatoid arthritis is a complex systemic disorder characterised primarily by articular inflammation and destruction with associated functional loss and reduced quality of life. RA is also associated with extra-articular disease e.g. of the lung with potentially devastating clinical consequences. The critical importance of co-morbidities, and consequent multi-morbidity, in determining outcomes in RA has now been recognised, not least as novel therapeutics have emerged with attendant increased life expectancy. The primary role of cytokine networks in mediating RA pathogenesis was established in extensive pre-clinical and clinical trials and in the adoption of cytokine targeted therapeutics in clinical care over three decades. Herein we briefly review those pivotal cytokine pathways that are associated with RA articular disease, and extend these insights to include extra-articular RA and its common co-morbidities.