THU0024 Anti-Inflammatory Inhibitors Targeting Jak and Ikk Have An Anabolic Effect on Type II Collagen Turnover ex Vivo

BackgroundRheumatoid arthritis (RA) and a subpopulation of osteoarthritis, inflammatory OA (iOA) are degenerative joint diseases with an inflammatory component. However, the degree of inflammation is much higher in RA than iOA. There are many signaling pathways involved with the inflammation-driven extracellular matrix (ECM) degradation in RA and iOA cartilage that have been suggested as anti-inflammatory targets. However, the results on joint structure in clinical trials have been varying. A better understanding of the intracellular signaling pathways and the downstream effect on ECM turnover could be beneficial for the selection of novel anti-inflammatory treatments for RA and iOA.ObjectivesThe aim of this study was to investigate the direct effect of the anti-inflammatory inhibitors R406 (the active metabolite of Fostamatinib), Tofacitinib, TPCA-1 and SB203580 on the cartilage ECM turnover.MethodsFull depth bovine cartilage ex vivo cultures were cultured for 3 weeks with OSM [10 ng/mL] and TNFα [2 ng/mL] (O+T) or together with R406, Tofacitinib or TPCA-1 at 10 μM and a two-fold dilution to 0.16 μM. SB203580 was tested at 3 μM, 1 μM and 0.3 μM. As negative control, untreated explants were included. The ECM turnover of the cartilage was assessed with the biomarkers; C2M, ProC2, AGNx1 and/or ARGS. Additionally, histology of the explants was examined with Safranin O and fast green staining.ResultsAggrecanase mediated degradation of aggrecan was assessed with ARGS or AGNx1. The Syk inhibitor R406, the Jak inhibitor Tofacitinib, and the IKK inhibitor TPCA-1 inhibited the release of ARGS or AGNx1, while the p38 inhibitor, SB203580, had no effect. The turnover of type II collagen was measured by the formation of type II collagen (ProC2) and MMP-mediated degradation of type II collagen (C2M). The ratio between ProC2 and C2M was calculated for week 1–3. Tofacitinib and TPCA-1 increased the area under the curve (AUC) of ProC2/C2M significantly compared to O+T (p