Tumor necrosis factor receptor-associated factor 6 is required to inhibit foreign body giant cell formation and activate osteoclasts under inflammatory and infectious conditions

Akihito Oya, Eri Katsuyama, Mayu Morita, Yuiko Sato, Tami Kobayashi, Kana Miyamoto, Toru Nishiwaki, Atsushi Funayama, Yoshinari Fujita, Takashi Kobayashi, Morio Matsumoto, Masaya Nakamura, Arihiko Kanaji, Takeshi Miyamoto

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Osteoclasts and foreign body giant cells (FBGCs) are derived from common progenitors and share properties such as multi-nucleation capacity induced by cell–cell fusion; however, mechanisms underlying lineage determination between these cells remain unclear. Here we show that, under inflammatory conditions, osteoclasts are stimulated in a manner similar to M1 macrophages, while formation of FBGCs, which exhibit M2-like phenotypes, is inhibited in a manner similar to that seen in M1/M2 macrophage polarization. FBGC/osteoclast polarization was inhibited by conditional knockout of tumor necrosis factor receptor associated factor 6 (Traf6) in adults in vivo and in vitro. Traf6-null mice were previously reported to die soon after birth, but we found that Traf6 deletion in adults did not cause lethality but rather inhibited osteoclast activation and prevented FBGC inhibition under inflammatory conditions. Accordingly, basal osteoclastogenesis was significantly inhibited by Traf6 deletion in vivo and in vitro and accompanied by increased bone mass. Lipopolysaccharide-induced osteoclast formation and osteolysis were significantly inhibited in Traf6 conditional knockout mice. Our results suggest that Traf6 plays a crucial role in regulating M1 osteoclast and M2 FBGC polarization and is a potential therapeutic target in blocking FBGC inhibition, antagonizing osteolysis in inflammatory conditions, and increasing bone mass without adverse effects in adults.

Original languageEnglish
Pages (from-to)679-690
Number of pages12
JournalJournal of Bone and Mineral Metabolism
Volume36
Issue number6
DOIs
Publication statusPublished - 2018 Nov 1

Keywords

  • Adult
  • Foreign body giant cells
  • Foreign body reaction
  • Osteoclasts
  • Tumor necrosis factor receptor associated factor 6

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine
  • Endocrinology

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