SAT0023 THE ROLE OF ADAM12 UPREGULATED PROLIFERATION OF SYNOVIAL MEMBRANE IN RHEUMATOID ARTHRITIS
Authors: M. Watanabe, K. Nishida, Y. Nasu, R. Nakahara, M. Matsuhashi, Y. Hotta, T. Ozaki
Journal: Annals of the Rheumatic Diseases (2020)

Background: ADAM12 is a member of a disintegrin and metalloproteinase family and has been reported to participate in the development of a variety of tumors by degrading ECM and shed precursors, thus promoting cell proliferation, invasion, and metastasis 1) . Additionally, ADAM12 is involved in chondrocyte differentiation from osteoarthritis (OA) patients by regulation of TGFβ1-induced IGF-1 and RUNX-2 expressions 2) . However, there is no report on the role of ADAM12 for rheumatoid arthritis (RA). Objectives: To investigate the expression and role of ADAM12 in the synovial tissue of RA. Methods: (1) The expression of ADAM12 in synovial tissues from RA (18 cases), OA (5 cases) and healthy control (HC) (3 cases) was examined by immunohistochemistry. The synovial tissues of HC were obtained during surgery of hemiarthroplasty for bone tumors. Three researchers evaluated the positive cell ratio. The samples were scored according to the percentage of positive staining: 0 points (weak positive, positive expression was less than 5%), 1 point (moderate positive, positive expression was between 5% and 50%) and 2 points (strong positive, positive expression was greater than 50%). In addition, the samples were scored according to the staining intensity: 0 points (weak intensity), 1 point (moderate intensity) and 2 points (high intensity). (2) The cultured synovial fibroblasts obtained from RA patients at the surgery (RASF) were stimulated by TNFα (1, 5, 10 ng/mL), TGFβ1 (1, 5, 10 ng/mL), PDGF-BB (1, 5, 10 ng/mL) and TNFα+TGFβ1+PDGF-BB (all 10 ng/mL), and the expression levels of ADAM12 relative mRNA was examined by real-time PCR. (3) siADAM12 was transfected in RASF, and the proliferation was examined by WST-1 assay, and the expression of ADAM12 protein was examined by western blotting. Results: (1) ADAM12 positive cells were found in synovial lining cells, plasma cells, and vascular endothelial cells. ADAM12 was highly expressed in RA synovial tissues. The immunostaining scores of RA, OA, and HC were 3.9±0.01, 1.9±0.27, and 0.8±0.18, respectively. (2) Stimulation by TNFα, TGFβ1, and PDGF-BB resulted in the upregulation of the expression of ADAM12 relative mRNA in RASF, and TGFβ1 stimulation notably tended to increase the expression by about 5 to 6 times. (3) siADAM12 successfully suppressed the expression of ADAM12 protein and simultaneously suppressed the proliferation of RASF. Conclusion: ADAM12 might be involved in the pathogenesis of RA, promoting the cell proliferation of RASF. References: [1] Kyeiborg M, Albrechtsen R, Couchman J, et al., Cellular roles of ADAM12 in health and disease, Int J Biochem Cell Biol, 2008 [2] Masahiro H, Keiichiro N, Joe H, et al., Involvement of ADAM12 in Chondrocyte Differentiation by Regulation of TGF-beta1-Induced IGF-1 and RUNX-2 Expressions, Calcif Tissue Int, 2019 Disclosure of Interests: Masahito Watanabe: None declared, Keiichiro Nishida Grant/research support from: K. Nishida has received scholarship donation from CHUGAI PHARMACEUTICAL Co., Eisai Co., Mitsubishi Tanabe Pharma and AbbVie GK., Speakers bureau: K. Nishida has received speaking fees from CHUGAI PHARMACEUTICAL Co., Eli Lilly, Janssen Pharmaceutical K.K., Eisai Co. and AYUMI Pharmaceutical Corporation., Yoshihisa Nasu: None declared, Ryuichi Nakahara: None declared, Minami Matsuhashi: None declared, Yoshifumi Hotta: None declared, Toshifumi Ozaki: None declared