Brief exposure to triamcinolone acetonide, but not its continous presence, strongly inhibits cartilage regeneration by chondrocytes

Abstract

s / Osteoarthritis and Cartilage 24 (2016) S63eS534 S337 synovium-conditioned medium (OA-CM) or TNFa to determine IL37 expression in an inflammatory environment. The function of IL37 was investigated via overexpression of IL37 by using an adenoviral vector (Ad-IL37) and subsequent stimulation with IL-1b for 24 h to create an inflammatory environment. An adenovirus overexpressing luciferase was used as control (Ad-Luc). Gene and protein expression of the proinflammatory cytokines IL-1b, IL-6 and IL-8 and catabolic enzymes MMP1, MMP3, MMP13, ADAMTS4 and ADAMTS5 were analyzed by qPCR, Western Blot and Luminex. Results: Immunohistochemistry and qPCR analysis showed that IL37 was expressed in chondrocytes from human OA joints. Furthermore, we found increased expression of IL37 after IL-1b stimulation, both on protein and gene expression level (6.8 fold), whereas OA-CM and TNFa stimulation did not significantly induce IL37 expression. Next, we investigated the anti-inflammatory effect of IL37 in chondrocytes (n1⁄48) via overexpression of IL37 and stimulationwith IL-1b. Twenty-four hours after IL-1b stimulation, IL37 significantly reduced IL-1b (42%), IL-6 (29%) and IL-8 (49%) gene expression (Fig. 1A). In addition to gene expression analysis, Western blot analysis showed that IL37 reduced IL-1b protein expression, and Luminex analysis showed that IL37 significantly decreased IL-8 protein levels (59%), and demonstrated a trend towards a decrease in IL-6 protein expression (25%). Next, we investigated the effect of IL37 on cartilage degrading enzymes, including MMPs and ADAMTSs. Significant downregulation was found on MMP1 (35%), MMP3 (31%), MMP13 (29%) and ADAMTS5 (27%) gene expressionafter IL-1b stimulation (Fig. 1B), whereas ADATMS4 expression was not affected. Also on protein level, MMP3 and MMP13 expression were both reduced (42%) and a trend towards decreased MMP1 expression (32%) was observed. Conclusions: Pro-inflammatory cytokines and catabolic enzymes negatively affect cartilage integrity by inducing matrix loss and chondrocyte death. Blocking the production of these catabolic factors is a promising therapy for OA. In this study we show for the first time that IL37 is expressed in osteoarthritic cartilage and that IL37 expression is regulated by IL-1b in primary OA chondrocytes. Furthermore, we demonstrated that IL37 potently reduces the production and secretion of pro-inflammatory cytokines and catabolic enzymes in an inflammatory environment. These data position IL37 as a potential therapeutic agent to inhibit cartilage degradation. Figure 1. IL37 reduces IL-lb-induced pro-inflammatory cytokine and catabolic enzyme production in human OA chondrocytes. (A) IL37 significantly downregulates IL-1b (42%), IL-6 (29%) and IL-8 (48%) gene expression compared to control (Ad-Luc). (B) IL37 significantly reduced MMP1 (35%), MMP3 (31%) and MMP13 (29%) gene expression compared to control (Ad-Luc). 553 BRIEF EXPOSURE TO TRIAMCINOLONE ACETONIDE, BUT NOT ITS CONTINOUS PRESENCE, STRONGLY INHIBITS CARTILAGE REGENERATION BY CHONDROCYTES I. Jansen y, A. Tellegen z, M. Tryfonidou z, C. € Oner y, D. Saris y, N. Woike x, J. Berard x, K. Messier x, L. Creemers y. yUniv. Med. Ctr. Utrecht, Utrecht, Netherlands; zUtrecht Univ., Utrecht, Netherlands; xDSM BioMed.,