Administration of cyclooxygenase-2 inhibitor reduces joint inflammation but exacerbates osteopenia in IL-1α transgenic mice due to GM-CSF overproduction

Yasuo Niki, Hironari Takaishi, Jiro Takito, Takeshi Miyamoto, Naoto Kosaki, Hideo Matsumoto, Yoshiaki Toyama, Norihiro Tada

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

IL-1α transgenic (Tg) mice exhibit chronic inflammatory arthritis and subsequent osteopenia, with IL-1-induced GM-CSF playing an important role in the pathogenesis. This study analyzed the mechanisms underlying osteopenia in Tg mice, and the therapeutic effects of the cyclooxygenase-2 inhibitor celecoxib on such osteopenia. Inhibited osteoclast formation was observed in RANKL-treated bone marrow cell (BMC) cultures from Tg mice and coculture of Tg-derived BMCs and wild-type-derived primary osteoblasts (POBs). FACS analysis indicated that this inhibition was attributable to a decreased number of osteoclast precursors within Tg-derived BMCs. Moreover, in coculture of Tg-derived POBs and either Tg- or wild-type-derived BMCs, osteoclast formation was markedly inhibited because Tg-derived POBs produced abundant GM-CSF, known as a potent inhibitor of osteoclast differentiation. Histomorphometric analysis of Tg mice revealed that both bone formation and resorption were decreased, with bone formation decreased more prominently. Interestingly, administration of celecoxib resulted in further deterioration of osteopenia where bone formation was markedly suppressed, whereas bone resorption remained unchanged. These results were explained by our in vitro observation that celecoxib dose-dependently and dramatically decreased osteogenesis by Tg mouse-derived POBs in culture, whereas mRNA expressions of GM-CSF and M-CSF remained unchanged. Consequently, blockade of PGE2 may exert positive effects on excessively enhanced bone resorption observed in inflammatory bone disease, whereas negative effects may occur mainly through reduced bone formation, when bone resorption is constitutively down-regulated as seen in Tg mice.

Original languageEnglish
Pages (from-to)639-646
Number of pages8
JournalJournal of Immunology
Volume179
Issue number1
DOIs
Publication statusPublished - 2007 Jul 1

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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