Recently, synoviolin, a novel E3 ubiquitin ligase, was identified in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) and synovial tissue, where it may contribute to the dysregulated proliferation and apoptosis seen in RA.1 2 Synoviolin expression is also associated with arthritis development in mice.1 The exact mechanism of synoviolin regulation and expression remains to be elucidated, but recently a role for tumour necrosis factor α (TNFα) and interleukin 1b was suggested as these cytokines increased the expression of synoviolin in RA FLS.3 Another interesting observation is that high level sustained expression of synoviolin in whole peripheral blood was related to decreased clinical response in RA patients treated with TNF blockade.4 Therefore, we investigated synoviolin expression in synovium and its relationship to later response to TNF blockade in patients with RA compared with psoriatic arthritis (PsA) and osteoarthritis (OA).

Synovial tissue samples were obtained …