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THU0029 FAS LIGAND REGULATES THE GENE EXPRESSIONS OF VARIOUS KEY MOLECULES IN RHEUMATOID SYNOVIAL FIBROBLASTS

Background Fas ligand (FasL) is a member of tumor necrosis factor superfamily (TNFSF6) and reported to contribute to synovial hyperplasia of rheumatoid arthritis (RA). Apoptosis of RA synovial cells through Fas/FasL pathway was inhibited by pro-inflammatory cytokines present within the synovium [1]. We previously reported that decoy receptor 3 overexpressed in rheumatoid synovial fibroblasts (RA-FLS) stimulated by TNFα protects the cells from Fas-induced apoptosis [2]. Objectives In this study, we investigated the gene expression profiles regulated by FasL in RA-FLS to reveal how FasL is involved in the pathogenesis of RA. Methods RA-FLS were obtained during total knee replacement surgery from patients with RA. Four individual lines of primary cultured RA-FLS were incubated either with 1000 ng/ml of recombinant human FasL protein or the same volume of phosphate buffered saline as unstimulated control in reduced serum medium for 12h. Gene expressions were detected by microarray assay (Human Genome U133 Plus 2.0, GeneChip® 3’ Expression Array; Thermo Fisher Scientific). Results Microarray data analysis revealed that FasL up-regulated or down-regulated the expression of various genes in RA-FLS. The function of regulated genes included transcriptional activator activity, positive regulation of metabolic process, positive regulation of cellular metabolic process, positive regulation of macromolecule metabolic process, positive regulation of nitrogen compound metabolic process, regulation of phosphorylation, positive regulation of biological process, regulation of phosphate metabolic process, regulation of MAPK cascade, and regulation of multicellular organismal process. The most up-regulated 3 genes by FasL were dual specificity phosphatase 6 (DUSP6), epiregulin (EREG) and interleukin11 (IL-11). The most down-regulated 3 genes by FasL were angiopoietin-like 7 (ANGPTL7), protein inhibitor of activated STAT2 (PIAS2) and growth differentiation factor 5 (GDF5). Conclusion DUSP6 regulates CD4+ T-cell activation and differentiation by inhibiting the T-cell receptor-dependent extracellular signal-regulated kinases 1 and 2 activations [3]. EREG is increased in patients with RA and associated with the development of cytokine-induced arthritis [4]. IL-11 regulates the growth and development of hematopoietic stem cells and decreases the pro-inflammatory cytokines and nitric oxide productions [5]. ANGPTL7 is pro-angiogenic factor [6] and promotes pro-inflammatory responses through the P38 signaling pathway [7]. PIAS proteins inhibit the activated STAT and are involved in the pathogenesis of RA [8]. GDF5 is associated with joint destruction of patients with OA and RA [9]. FasL regulates the expression of various genes in RA-FLS. Therefore, FasL may affect the pathogenesis of RA by regulating gene expressions of these molecules in RA-FLS. References [1] Wakisaka S. et al., Clin Exp Immunol. 1998;114:119-128. [2] Hayashi S. et al., Arthritis Rheum. 2007;56:1067-1074. [3] Bertin S. et al., Mucosal Immunol. 2015;8:505-515. [4] Harada M. et al., J Immunol. 2015;194:1039-1046. [5] Moreland L. et al., Arthritis Res. 2001;3:247-252. [6] Katoh Y, et al., Int J Mol Med. 2006;17:1145-1149. [7] Quian T, et al., Inflammation. 2016;39:974-985. [8] Lao M. et al., J Immunol. 2016;196:596-606. [9] Martinez A. et al., Ann Rheum Dis. 2008;67:1352-1353. Disclosure of Interests None declared