Scopoletin suppresses IL-6 production from fibroblast-like synoviocytes of adjuvant arthritis rats induced by IL-1β stimulation.

Scopoletin, a coumarin compound naturally occurring in many medicinal plants, has previously been demonstrated to ameliorate synovial inflammation and destruction of cartilage and bone in adjuvant arthritis (AA) rats. As interleukin (IL)-6 is critically involved in the initiation and development of rheumatoid arthritis (RA), the present study was performed to investigate the effect of scopoletin on IL-6 production from fibroblast-like synoviocytes (FLS) to get insight into its anti-RA mechanisms. FLS were isolated from synovial membrane tissues of AA rats, and stimulated with IL-1β (10 ng/mL). Scopoletin, at concentrations of 15, 30, and 60 μM, was shown to only moderately inhibit FLS proliferation, but dramatically reduce IL-6 production at both mRNA and protein levels. It also inhibited the phosphorylation of p38 mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK), protein kinase C (PKC) and cAMP response element binding protein (CREB). These findings suggest that scopoletin exerts anti-RA action probably through suppressing IL-6 production from FLS via MAPK/PKC/CREB pathways.