Inhibitory Effect of Mechanical Load on IL-1 Induced Cartilage Degradation Is Mediated by Interferon-Gamma and IL-1 Receptor 1

Matrix remodeling in articular cartilage is regulated by the elevation and activation of aggrecanases (ADAMTS-4 and ADAMTS-5) and matrix metalloproteinases (MMPs) [2–4, 7–9, 10]. Several recent studies from our and other groups have shown that mechanical loading can counteract interleukin 1 (IL-1) induced pro-inflammatory and catabolic events by down-regulating aggrecanases, MMPs, and pro-inflammatory genes [1, 3, 5, 6], but the molecular mechanism is not clear. Many previous studies have shown that the regulation of pro-inflammatory effect of IL-1 come from several aspects: anti-inflammatory cytokines (TGF-β, IL-10, IL-6 and interferon γ), IL-1 receptor related proteins (IL-1R1, IL-1R2, and IL-1Ra) as well as a family of intracellular inhibitory protein called Suppressor Of Cytokine Signaling (SOCS.) SOCS1 and SOCS3 are especially important, since they can inhibit both MAPK and NF-κB pathways induced by IL-1 [12]. The objective of this study was to determine whether mechanical load affected anti-inflammatory mediators along with anti-catabolic events.