Spondyloarthritis and rheumatoid arthritis: different clinical manifestations, similar cytokine network

Background The reasons for the phenotypic differences between spondyloarthritis (SpA) and rheumatoid arthritis (RA) are still unclear. Slight divergences in cytokine networks driving the pathologies might contribute to the distinct clinical manifestations and may represent new treatment opportunities. Objectives The main goal of this work was to compare serum and synovial cytokines in established SpA and RA patients. Materials and methods The concentration of a panel of cytokines was measured in the serum of SpA and RA patients, as well as in synovial fluid from SpA, RA and osteoarthritis patients. Results The authors found that SpA and RA patients shared a similar pattern of cytokine concentration, with the exception of higher levels of interleukin-21 in the synovial fluid of RA patients. Conclusions Our results suggest that although SpA and RA are chronic inflammatory diseases with clearly distinct clinical manifestations, both pathologies share a similar cytokine profile, including Th17-related cytokines.