LAUSR

Inflammatory joint diseases, such as psoriatic arthritis (PsA), are frequently treated by biologics. Assessment of treatment efficacy is based upon change in clinical activity scores and in tender and swollen joint counts. Although the response to these agents may be attributed to their central anti-inflammatory effects, synovial response may be operating in parallel. The potential beneficial role of intra-articular injection of tumor necrosis factor (TNF) blockers compared to glucocorticoids (GCs) in reducing synovitis was shown by means of clinical and instrumental validated measures (1). The inflamed synovial fluid is rich in mononuclear cells, however, the different mode of action of the in vitro response of these cells to drugs may contribute to the understanding of cellular response to therapeutic agents in central as opposed to peripheral compartments.To evaluate the effect of biologics used in the management of PsA on synovial fluid mononuclear cells (SFMCs) in vitro, and to compare their modes of action to GCs that are used to locally alleviate synovial inflammation.SFMCs were obtained from PsA patients (n=11) during therapeutic knee arthrocentesis. The cells were cultured in vitro for 7 days in the presence of biologics (adalimumab, infliximab, secukinumab and ustekinumab, 10ug/ml) and GCs (betamethasone and methylprednisolone, 1 ug/ml and 10ug/ml) or medium as control. Levels of the secreted TNF were measured by ELISA. Changes in %CD14+CD16+ monocytes were analyzed by flow cytometry.Both TNF inhibitors (adalimumab p<0.01, infliximab p=0.0003) and GCs (betamethasone and methylprednisolone at 1ug/ml p<0.01 and at 10ug/ml p<0.04) significantly reduced TNF levels in cultured media derived from SFMCs of PsA patients (n=8) compared to medium. None of the other biologics reduced TNF levels in culture (Fig. 1A). Additionally, %CD14+CD16+ SFMCs derived from PsA patients (n=11) were significantly reduced by TNF inhibitors (p=0.0003) compared to medium, however, other biologics and GCs did not display similar activity (Fig. 1B).Figure 1.Both TNF inhibitors and GCs block TNF secretion but exhibit different activity on inflammatory CD14+CD16+ monocytes derived from SFMCs of PsA patients. SFMCs were co-cultured for 7 days in the presence of adalimumab, infliximab, secukinumab and ustekinumab at 10ug/ml or with betamethasone and methylprednisolone at 1ug/ml and 10ug/ml. Medium alone was used as a control. (A) Culture supernatants were analyzed for TNF levels by ELISA (n=8). (B) Cells were analyzed for %CD14+CD16+ monocytes by flow cytometry (n=11). All p values were calculated by the non-parametric one-way ANOVA Kruskal-Wallis test and Dunn’s multiple comparison test, *p<0.04, **p<0.01 and ***p=0.0003.Our data demonstrated marked activity mediated by TNF inhibitors in comparison with other biologics tested for their ability to suppress TNF secretion and inflammatory CD14+CD16+ monocytes. In contrast, GCs suppressed TNF secretion but did not significantly change the proportion of inflammatory CD14+CD16+ monocytes. These findings suggest an additional mechanism of action exerted directly by TNF inhibitors on synovial monocytes and which differs from that of GCs. These results warrant further studies of the therapeutic potential of local peripheral activity of TNF inhibitors for clinical application.[1]Carubbi F, Zugaro L, Cipriani P, Conchiglia A, Gregori L, Danniballe C, et al. Safety and efficacy of intra-articular anti-tumor necrosis factor alpha agents compared to corticosteroids in a treat-to-target strategy in patients with inflammatory arthritis and monoarthritis flare. Int J Immunopathol Pharmacol. 2016;29:252-66.None declared