| First Author | Fujii T | Year | 2012 |
| Journal | Bone | Volume | 51 |
| Issue | 4 | Pages | 771-80 |
| PubMed ID | 22776139 | Mgi Jnum | J:192396 |
| Mgi Id | MGI:5465040 | Doi | 10.1016/j.bone.2012.06.024 |
| Citation | Fujii T, et al. (2012) IL-4 inhibits TNF-alpha-mediated osteoclast formation by inhibition of RANKL expression in TNF-alpha-activated stromal cells and direct inhibition of TNF-alpha-activated osteoclast precursors via a T-cell-independent mechanism in vivo. Bone 51(4):771-80 |
| abstractText | It has been reported that osteoclastogenesis is induced by tumor necrosis factor (TNF)-alpha. Interleukin (IL)-4 is the most important cytokine involved in humoral immunity. However, no studies have investigated the effect of IL-4 on TNF-alpha-mediated osteoclast formation in vivo. In this study, we investigated the effect of IL-4 on TNF-alpha-mediated osteoclast formation in vivo. TNF-alpha 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-alpha and IL-4 were lower than those in mice administered TNF-alpha alone. The level of tartrate-resistant acid phosphatase form 5b (TRACP5b) as a marker of bone resorption in mice administered both TNF-alpha and IL-4 was also lower. We showed that IL-4 inhibited TNF-alpha-mediated osteoclast formation in osteoclast precursors in vitro. Expression of receptor activator of NF-kappaB ligand (RANKL) in TNF-alpha-activated stromal cells was also inhibited. Furthermore, we investigated whether IL-4 had effects on both stromal cells and osteoclast precursors in TNF-alpha-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-alpha-mediated osteoclast formation in the presence of TNF-alpha-responsive stromal cells, and TNF-alpha-responsive osteoclast precursors in vivo. IL-4 also inhibited TNF-alpha-induced RANKL expression in the presence of TNF-alpha-responsive stromal cells in vivo. This event is dependent on p38 inhibition in vitro. Additionally, IL-4 inhibited TNF-alpha-mediated osteoclast formation in T cell-depleted mice. In summary, we conclude that IL-4 inhibited TNF-alpha-mediated osteoclast formation by inhibiting expression of RANKL in TNF-alpha-activated stromal cells, and directly inhibited TNF-alpha-activated osteoclast precursors in vivo via a T cell-independent mechanism. |
