Interleukin-17 is a potent pro-inflammatory cytokine produced by activated memory T cells. There are at least six members of the IL-17 family in humans and in mice. As IL-17 shares properties with IL-1 and TNF-alpha, it may induce joint inflammation and bone and cartilage destruction. This cytokine is found in synovial fluids of patients with rheumatoid arthritis, and produced by rheumatoid arthritis synovium. It increases IL-6 production, induces collagen degradation and decreases collagen synthesis by synovium and cartilage and proteoglycan synthesis in cartilage. IL-17 is also able to increase bone destruction and reduce its formation. Blocking of interleukin-17 with specific inhibitors provides a protective inhibition of cartilage and bone degradation.

CLEC9A expression was significantly higher in psoriatic skin compared with healthy donor. In psoriatic skin and PsA ST, CLEC9A() cells were in close proximity to TUNEL() cells. SF CLEC9A levels were significantly lower compared with paired PsA serum. Adalimumab treatment did not affect CLEC9A serum level and skin expression. The downregulation of synovial CLEC9A might be associated with a novel mechanism by which anti-TNF therapy might reduce CD8-mediated inflammation in PsA patients.

Interleukin-17 is a potent pro-inflammatory cytokine produced by activated memory T cells. There are at least six members of the IL-17 family in humans and in mice. Mature mouse IL-17A shares 61% and 89% amino acid sequence identity with human and rat IL-17A, respectively. As IL-17 shares properties with IL-1 and TNF-alpha, it may induce joint inflammation and bone and cartilage destruction. This cytokine is found in synovial fluids of patients with rheumatoid arthritis, and produced by rheumatoid arthritis synovium. It increases IL-6 production, induces collagen degradation and decreases collagen synthesis by synovium and cartilage and proteoglycan synthesis in cartilage. IL-17 is also able to increase bone destruction and reduce its formation. Blocking of interleukin-17 with specific inhibitors provides a protective inhibition of cartilage and bone degradation.