TNFRSF11B and synovitis: We found that PTX decreased the expression of IL-6, IL-8, and inhibited TNF-α-induced production of IL-1β, IL-8, MMP8, and MMP9; moreover, PTX upregulated the expression of OPG, while down-regulating RANKL expression, which suggests that it may alleviate not only synovitis but also cartilage destruction.