The synthetic cannabinoid WIN55,212-2 mesylate decreases the production of inflammatory mediators in rheumatoid arthritis synovial fibroblasts by activating CB2, TRPV1, TRPA1 and yet unidentified receptor targets

In rheumatoid arthritis (RA), synovial fibroblasts (SF) secrete large amounts of IL-6, IL-8 and matrix metalloproteinases (MMPs) which are crucial for cartilage destruction. RASFs are sensitive to the action of cannabinoids and they not only express cannabinoid receptors type I and II (CB1 and CB2) but also transient receptor potential channels type vanilloid (TRPV1) and ankyrin (TRPA1). The synthetic cannabinoid WIN55,212-2 mesylate (WIN) demonstrated strong anti-inflammatory effects in monocytes and synovial fibroblasts only in high concentrations in a non-cannabinoid receptor dependent manner. In this study we assessed the ability of WIN to modulate cytokine and MMP-3 production in SFs over a wide concentration range and identified specific receptor targets that mediate the effects of this synthetic cannabinoid. MMP-3, IL-6 and IL-8 were determined by ELISA. Adhesion was measured by the XCELLigence system. Proliferation was assessed by cell titer blue assays. WIN significantly reduced TNF-induced IL-6, IL-8 and MMP-3 production in concentrations below 2 μM, while higher concentrations completely inhibited production of IL-6 and IL-8 but increased extracellular MMP-3 levels. The inhibitory effect at low concentrations (