AB0065 N-cadherin is down-regulated by decoy receptor 3 in specifically rheumatoid synovial fibroblasts
Authors: K. Fukuda, Y. Miura, S. Hayashi, T. Maeda, R. Kuroda
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Decoy receptor 3 (DcR3) is a secreted decoy tumour necrosis factor receptor and competitively binds and inhibits the TNF family including Fas-ligand, LIGHT, and TL1A. We previously reported that DcR3 overexpressed in rheumatoid synovial fibroblasts (RA-FLS) stimulated by TNFα protects the cells from Fas-induced apoptosis.<sup>1</sup> We recently reported that DcR3 binds to TL1A expressed on RA-FLS resulting in the negative regulation of cell proliferation induced by inflammatory cytokines.<sup>2</sup> Further, we newly revealed the gene expression profiles in RA-FLS regulated by DcR3 by using microarray data analysis.<sup>3</sup> Among the genes in the profile, we demonstrated the possible involvement of tryptophan hydroxylase 1 down-regulated,<sup>4</sup> interleukin 12B up-regulated by DcR3<sup>5</sup> and centrosomal protein 70 kDa<sup>6</sup> in the pathogenesis of RA. The profiles also indicated that Cadherin 2/type 1/N-cadherin (CDH2) was up-regulated by DcR3 (fold change 1.93).<sup>3</sup> CDH2 has been reported to be associated with cell attachment and migration,<sup>7</sup> osteoblast differentiation,<sup>8</sup> and the proliferation of RA-FLS.<sup>9</sup> The hemophilic interaction of CDH2 suppresses the proliferation of RA-FLS through increasing the P27<sup>Kip1</sup> that inhibit cell-cycle progression.<sup>9</sup> <h3>Objectives</h3> In this study, we analysed CDH2 expression in RA-FLS stimulated with DcR3 in detail to reveal the involvement of CDH2 and DcR3 in the pathogenesis of RA. <h3>Methods</h3> <i>Real-time polymerase chain reaction (real-time PCR).</i> RA-FLS were stimulated with various concentration of DcR3-Fc or 1,000 ng/ml of IgG1, or left untreated in serum-free Opti-MEM for 12 hour. The relative expression levels of CDH2 mRNA were quantified by real-time PCR. <i>Immunohistochemistry.</i> Anti-CDH2 antibody was applied to frozen sections of synovial tissues from patients with RA or OA for overnight. After that, the expression of CDH2 protein was evaluated by immunohistochemical analysis. <h3>Results</h3> Real-time PCR demonstrated that DcR3-Fc significantly increased the expression of CDH2 mRNA in RA-FLS (104% with 10 ng/ml, 112% with 100 ng/ml, and 200% with 1000 ng/ml). Immunohistochemistry revealed that CDH2 was expressed more in the sublining layer of rheumatoid synovium than OA synovium. <h3>Conclusions</h3> In the gene expression profiles, we focused on CDH2 as the gene was highly up-regulated and belonged to major functional clustering categories; protein complex assembly, cell motility, regulation of transcription, cell membrane and glycosylation. In this study, we showed that the expression of CDH2 mRNA in RA-FLS was induced by DcR3 and that CDH2 was increased in the sublining layer of rheumatoid synovium. In this study, we demonstrated that DcR3 significantly induced CDH2 expression in RA-FLS. Considering the fact that CDH2 inhibits RA-FLS proliferation, DcR3 signalling may control the hyperplasia of RA synovium. <h3>References</h3> [1] Hayashi S, et al. Arthritis Rheum. 2007;56:1067–1074. [2] Takahashi M, et al. Int J Mol Med. 2011;28:423–427. [3] Fukuda K, et al. Int J Mol Med. 2013;32:910–916. [4] Maeda T, et al. Mol Med Rep. 2015;12:5191–5196. [5] Fukuda K, et al., Mol Med Rep. 2016;13:3647–3652. [6] Fukuda K, et al. Mod Rheumatol in press. [7] Akitaya T, et al. Dev Dyn. 1992;194:12–20. [8] Marie P. J Cell Physiol2002;190:297–305. [9] Nonomura Y, et al. J Rheumatol2009;36:698–705. <h3>Disclosure of Interest</h3> None declared