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Mediators of Inflammation
Volume 2009, Article ID 308596, 9 pages
http://dx.doi.org/10.1155/2009/308596
Research Article

IL-1β Suppresses the Formation of Osteoclasts by Increasing OPG Production via an Autocrine Mechanism Involving Celecoxib-Related Prostaglandins in Chondrocytes

1Nihon University Graduate School of Dentistry, Tokyo 101-8310, Japan
2Department of Fixed Prosthodontics, Nihon University School of Dentistry, 1-8-13, Kanda Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan
3Division of Advanced Dental Treatment, Dental Research Center, Nihon University School of Dentistry, Tokyo 101-8310, Japan
4Department of Oral Health Sciences, Nihon University School of Dentistry, Tokyo 101-8310, Japan
5Department of Biochemistry, Nihon University School of Dentistry, Tokyo 101-8310, Japan
6Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo 101-8310, Japan

Received 25 June 2009; Revised 28 August 2009; Accepted 1 December 2009

Academic Editor: Muzamil Ahmad

Copyright © 2009 Yusuke Watanabe et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Elevated interleukin (IL)-1 concentrations in synovial fluid have been implicated in joint bone and cartilage destruction. Previously, we showed that IL-1 stimulated the expression of prostaglandin (PG) receptor EP4 via increased production. However, the effect of IL-1 on osteoclast formation via chondrocytes is unclear. Therefore, we examined the effect of IL-1 and/or celecoxib on the expression of macrophage colony-stimulating factor (M-CSF), receptor activator of NF- B ligand (RANKL), and osteoprotegerin (OPG) in human chondrocytes, and the indirect effect of IL-1 on osteoclast-like cell formation using RAW264.7 cells. OPG and RANKL expression increased with IL-1 ; whereas M-CSF expression decreased. Celecoxib blocked the stimulatory effect of IL-1 . Conditioned medium from IL-1 -treated chondrocytes decreased TRAP staining in RAW264.7 cells. These results suggest that IL-1 suppresses the formation of osteoclast-like cells via increased OPG production and decreased M-CSF production in chondrocytes, and OPG production may increase through an autocrine mechanism involving celecoxib-related PGs.