IL-17 in spondyloarthritis: is the T-party over?

The past decade has witnessed significant progress in revealing an important role for IL-17 in the pathogenesis of several immune-mediated inflammatory diseases. Recent studies have provided new insights into the cellular source of IL-17, originally identified as the signature cytokine of a distinct CD4(+) T-cell subset known as Th17. Accumulating evidence suggests that the majority of the IL-17 released in inflammatory arthritis is produced by innate immune cells rather than T cells. Understanding molecular mechanisms behind these early innate immune responses will be the key to designing rational therapies targeting these important inflammatory pathways.