Out of the shadow of interleukin-17A: the role of interleukin-17F and other interleukin-17 family cytokines in spondyloarthritis

Purpose of review The last decade has witnessed tremendous advances in revealing an important role for the interleukin (IL)-17 cytokine family in the pathogenesis of spondyloarthritis (SpA). Although most attention has been focused on IL-17A, a potential role of other IL-17 family members in inflammation and tissue remodelling is emerging. Herein, I review recent studies covering the role of IL-17B-F cytokines in the pathogenesis of SpA. Recent findings Several recent studies provided new insights into the cellular source, regulation and function of IL-17F. IL-17F/IL-17A expression ratio is higher in psoriatic skin compared to SpA synovitis. IL-17F-expressing T cells produce different proinflammatory mediators than IL-17A-expressing cells, and IL-17F and IL-17A signal through different receptor complex. Dual IL-17A and IL-17F neutralization resulted in greater suppression of downstream inflammatory and tissue remodelling responses. Furthermore, there is additional evidence of IL-23-independent IL-17 production. In contrast to IL-17A, IL-17F and IL-17C, which play proinflammatory roles in skin and joint inflammation, an anti-inflammatory function is proposed for IL-17D. An increase in IL-17E is associated with subclinical gut microbiome alterations after anti-IL-17A therapy in SpA patients. Summary IL-17 family cytokines may act as agonists or antagonists to IL-17A contributing in concert to local inflammatory responses. Understanding their function and ident...
Source: Current Opinion in Rheumatology - Category: Rheumatology Tags: SPONDYLOARTHROPATHIES INCLUDING PSORIATIC ARTHRITIS: Edited by Joerg Ermann Source Type: research