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Open Access Research article

Cytokine signaling-1 suppressor is inducible by IL-1beta and inhibits the catabolic effects of IL-1beta in chondrocytes: its implication in the paradoxical joint-protective role of IL-1beta

Yong Seok Choi1, Jin Kyun Park23, Eun Ha Kang1, Young-Kyun Lee4, Tae Kyun Kim4, Jin-Haeng Chung5, Jason M Zimmerer6, William E Carson6, Yeong Wook Song237 and Yun Jong Lee17*

Author Affiliations

1 Department of Internal Medicine, Seoul National University Bundang Hospital, 166 Gumi-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, Korea

2 Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea

3 WCU Department of Molecular Medicine and Biopharmaceutical Sciences, Medical Research Institute, Seoul National University College of Medicine, Seoul, Korea

4 Department of Orthopedic Surgery, Seoul National University Bundang Hospital, Seongnam-si, Korea

5 Department of Pathology, Seoul National University Bundang Hospital, Seongnam-si, Korea

6 Department of Surgery Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, The Ohio State University, Columbus, OH 43210, USA

7 Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea

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Arthritis Research & Therapy 2013, 15:R191  doi:10.1186/ar4381

Published: 18 November 2013

Abstract

Introduction

Although IL-1β is believed to be crucial in the pathogenesis of osteoarthritis (OA), the IL-1β blockade brings no therapeutic benefit in human OA and results in OA aggravation in several animal models. We explored the role of a cytokine signaling 1 (SOCS1) suppressor as a regulatory modulator of IL-1β signaling in chondrocytes.

Methods

Cartilage samples were obtained from patients with knee OA and those without OA who underwent surgery for femur-neck fracture. SOCS1 expression in cartilage was assessed with immunohistochemistry. IL-1β-induced SOCS1 expression in chondrocytes was analyzed with quantitative polymerase chain reaction and immunoblot. The effect of SOCS1 on IL-1β signaling pathways and the synthesis of matrix metalloproteinases (MMPs) and aggrecanase-1 was investigated in SOCS1-overexpressing or -knockdown chondrocytes.

Results

SOCS1 expression was significantly increased in OA cartilage, especially in areas of severe damage (P < 0.01). IL-1β stimulated SOCS1 mRNA expression in a dose-dependent pattern (P < 0.01). The IL-1β-induced production of MMP-1, MMP-3, MMP-13, and ADAMTS-4 (aggrecanase-1, a disintegrin and metalloproteinase with thrombospondin motifs 4) was affected by SOCS1 overexpression or knockdown in both SW1353 cells and primary human articular chondrocytes (all P values < 0.05). The inhibitory effects of SOCS1 were mediated by blocking p38, c-Jun N-terminal kinase (JNK), and nuclear factor κB (NF-κB) activation, and by downregulating transforming growth factor-β-activated kinase 1 (TAK1) expression.

Conclusions

Our results show that SOCS1 is induced by IL1-β in OA chondrocytes and suppresses the IL-1β-induced synthesis of matrix-degrading enzymes by inhibiting IL-1β signaling at multiple levels. It suggests that the IL-1β-inducible SOCS1 acts as a negative regulator of the IL-1β response in OA cartilage.