title: IL-4 inhibits TNF-α-mediated osteoclast formation by inhibition of RANKL expression in TNF-α-activated stromal cells and direct inhibition of TNF-α-activated osteoclast precursors via a T-cell-independent mechanism in vivo.
abstract: It has been reported that osteoclastogenesis is induced by tumor necrosis factor (TNF)-α. Interleukin (IL)-4 is the most important cytokine involved in humoral immunity. However, no studies have investigated the effect of IL-4 on TNF-α-mediated osteoclast formation in vivo. In this study, we investigated the effect of IL-4 on TNF-α-mediated osteoclast formation in vivo. TNF-α was administered with and without IL-4 into the supracalvariae of mice. The number of osteoclasts and the levels of mRNA for cathepsin K and tartrate-resistant acid phosphate, both osteoclast markers, in mice administered TNF-α and IL-4 were lower than those in mice administered TNF-α alone. The level of tartrate-resistant acid phosphatase form 5b (TRACP5b) as a marker of bone resorption in mice administered both TNF-α and IL-4 was also lower. We showed that IL-4 inhibited TNF-α-mediated osteoclast formation in osteoclast precursors in vitro. Expression of receptor activator of NF-κB ligand (RANKL) in TNF-α-activated stromal cells was also inhibited. Furthermore, we investigated whether IL-4 had effects on both stromal cells and osteoclast precursors in TNF-α-mediated osteoclast formation in vivo. Using mice whose stromal cells and osteoclast precursors were chimeric for the presence of TNF receptors, IL-4 inhibited TNF-α-mediated osteoclast formation in the presence of TNF-α-responsive stromal cells, and TNF-α-responsive osteoclast precursors in vivo. IL-4 also inhibited TNF-α-induced RANKL expression in the presence of TNF-α-responsive stromal cells in vivo. This event is dependent on p38 inhibition in vitro. Additionally, IL-4 inhibited TNF-α-mediated osteoclast formation in T cell-depleted mice. In summary, we conclude that IL-4 inhibited TNF-α-mediated osteoclast formation by inhibiting expression of RANKL in TNF-α-activated stromal cells, and directly inhibited TNF-α-activated osteoclast precursors in vivo via a T cell-independent mechanism.
authors: Division of Orthodontics and Dentofacial Orthopedics, Tohoku University Graduate School of Dentistry, 4‐1 Seiryo-machi, Aoba-ku, Sendai 980‐8575, Japan.
authors: Toshiya
authors: T
authors: Fujii
authors: Hideki
authors: H
authors: Kitaura
authors: Keisuke
authors: K
authors: Kimura
authors: Zaki Weli
authors: ZW
authors: Hakami
authors: Teruko
authors: T
authors: Takano-Yamamoto
mesh_terms: D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D015847:Interleukin-4 / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism; D053245:RANK Ligand / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
chemical_list: D017931:DNA Primers; D053245:RANK Ligand; C505689:Tnfsf11 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4