BackgroundSeveral studies suggest that celecoxib has beneficial effects on degenerated cartilage (1, 2). Together with effects on synovial tissue and bone, celecoxib was postulated to have disease modifying osteoarthritic drug (DMOAD) activity.ObjectivesThis study evaluated the DMOAD activity of celecoxib, a selective cyclooxygenase 2 (COX-2) inhibitor compared to no treatment and naproxen, treating end-stage knee osteoarthritis (OA), after in vivo exposure using detailed ex vivo tissue analyses.Methods172 patients with end-stage knee OA were randomized to 4 groups and treated for 4 weeks prior to knee replacement surgery: celecoxib 2dd200g, naproxen 3dd250mg, celecoxib 2dd200mg stopped 3 days prior to surgery, or no treatment. To determine if treatment had reached the joint, intra-articular COX-2 expression was determined by Western Blot analysis in the celecoxib until surgery and no treatment group, considering these as most extremes. Proteoglycan release, as primary outcome and content were determined by staining and precipitation of glycosaminoglycans (GAGs) with Alcian Blue. Release of newly formed proteogylcans, as a measure of proteoglycan retention, was determined by loss of 35SO42-labeled GAGs in culture medium by precipitation of GAGs and subsequent liquid scintillation analysis. Synovial tissue inflammation markers interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were determined by Enzyme Linked Immuno Sorbet Assay (ELISA) and nitric oxide (NO) production by standard Griess reaction. Western Ontario and McMaster University (WOMAC) questionnaire was used to evaluate clinical parameters.ResultsIntra-articular COX-2 expression was significantly decreased in both cartilage and synovial tissue (figure 1) indicating proper in vivo exposure of the treatment.Despite this reduction, no significant effect on proteoglycan release, retention or content was found for none of the treatment groups (table 1). Synovial tissue showed only a small decrease in nitric oxide levels in celecoxib treated patients. No clear clinical effects could be observed as indicated by the WOMAC scores.ConclusionsNo effect of a 4-week in vivo celecoxib treatment on joint tissue in knee OA patients could be detected, although decreased expression of COX-2 confirmed its intra-articular availability. Effects on synovial inflammatory mediators and clinical outcome were very limited. No adverse effects were found either. As such the previous reported disease modifying effects of celecoxib in in vitro and pilot clinical studies could not unambiguously be confirmed in this randomized trial.References de Boer TN, Huisman AM, Polak AA, Niehoff AG, van Rinsum AC, Saris D, et al. The chondroprotective effect of selective COX-2 inhibition in osteoarthritis: ex vivo evaluation of human cartilage tissue after in vivo treatment. Osteoarthritis and cartilage/OARS, Osteoarthritis Research Society. 2009;17(4):482–8.Mastbergen SC, Jansen NW, Bijlsma JW, Lafeber FP. Differential direct effects of cyclo-oxygenase-1/2 inhibition on proteoglycan turnov...

BackgroundIdeally a disease modifying osteoarthritis drug (DMOAD) combines treatment for pain, tissue damage and inflammation, all in one molecule. Intra-articular application of a DMOAD brings additional value to treatment for two reasons, (i) lower risk of systemic side effects and (ii) higher drug concentration and potentially improved penetration of non-vascularized articular cartilage. Interleukin-4 (IL-4) and Interleukin-10 (IL-10) have been shown to prevent joint degeneration and can work synergistically1.ObjectivesThis study evaluates the DMOAD activity of repetitive intra-articular injections with a human fusion protein of IL-4 and IL-10 (hIL4–10FP) in the canine Groove model of osteoarthritis (OA).MethodsIn 8 dogs joint degeneration was induced according to the Groove model. Six weeks after surgery dogs were treated with ten weekly intra-articular injections of either hIL4–10FP (n=4) or PBS (n=4). Subsequently, dogs were euthanized and cartilage and synovium were harvested. Cartilage damage and synovial inflammation were macroscopically evaluated. Proteoglycan release and content were determined ex vivo by staining of glycosaminoglycans (GAGs) with Alcian Blue. Proteoglycan synthesis was measured by 35SO42– incorporation and precipitation with cetylpyridium chloride and liquid scintillation analysis of 35SO42–-labeled GAGs. Potential antibody formation against hIL4–10FP was evaluated with ELISA and a cell based assay. Immunohistochemistry of CD79α and CD10 was used to evaluate the presence of B-cells in synovium.ResultsAffected knees of PBS treated dogs showed enhanced macroscopic cartilage damage compared to their controls (0.31 vs 2.44, p=0.068). Also differences in proteoglycan release, content and synthesis indicated a degenerative state in the affected knees.Unexpectedly, enhanced synovial inflammation was observed in hIL4–10FP treated joints compared to PBS treated joints, demonstrated by enhanced macroscopic (3.5 vs 2.3 out of 5) and histologic (2.5 vs 1.8 out of 6) scores. CD79α and CD10 showed enhanced expression in synovium of the hIL4–10FP group compared to the PBS group, although not statistically significant (fig 1). Additional analyzes showed that hIL4–10FP was immunogenic in dogs after multiple injections. Formation of neutralizing antibodies was shown in a cell based assay where the activity of hIL4–10FP was inhibited in the presence of serum of hIL4–10FP treated dogs (fig 2). Despite the enhanced inflammatory response in hIL4–10FP group there was no enhanced cartilage degeneration detected compared to the PBS group (fig 3).ConclusionsRepetitive intra-articular injection of human IL4–10FP led to antibody formation in a non-inflammatory canine model of OA. Despite the immune response, proteoglycan turnover parameters were comparable between the two treatment groups, suggesting a beneficial effect of hIL4–10FP. This study also shows that it is not evident to use a human protein in a (canine) animal model, although this is often done. Instead, a species specific protein is warranted. Therefo...