Background and Objective
IL-20 is a novel cytokine that is involved in skin inflammation, in part by serving as an autocrine factor for keratinocytes. The aim of this study was to investigate the expression of IL-20 in the inflamed synovium of patients with psoriatic arthritis (PsA) and rheumatoid arthritis (RA) to provide more insight into the possible role of this cytokine in inflammatory joint disease. To further assess the regulation of IL-20 expression, in vitro experiments were conducted to determine the effects of IL-1β and TNF-α on the expression of IL-20 by RA fibroblast-like synoviocytes (FLS).