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Tumor necrosis factor-α (TNF-α) directly and indirectly plays a crucial role in osteoclastogenesis. However, the indirect effects of TNF-α on colony-stimulating factor-1 receptor (CSF-1R)-mediated osteoclastogenesis achieved via periodontal ligament (PDL) cells are not fully understood. We herein examined the potency of osteoclast differentiation and maturation induced by fivefold supernatants in the stimulated human PDL cells with a physiologically high concentration (10 ng/mL) of recombinant TNF-α to human peripheral blood monocytes/macrophages in the simultaneous presence of the receptor activator of nuclear factor kappa-B ligand. The number of tartrate-resistant acid phosphatase-positive cells with multiple nuclei, but not those with a single nucleus, was decreased by approximately 50% by neutralization with rabbit IgG against either interleukin-34 (IL-34) or CSF-1. Small and large amounts of IL34 and CSF1 transcripts were measured in the stimulated PDL cells using real-time polymerase chain reaction. The corresponding amounts of proteins to IL34 and CSF1 transcripts were observed in the stimulated PDL cells on immunohistochemical staining or Western blotting. Moreover, 0.13 ng/mL of IL-34 and 5.0 ng/mL of CSF-1 were measured in the supernatants of the stimulated PDL cells using an enzyme-linked immunosorbent assay. IL-34 derived from the stimulated PDL cells with TNF-α appeared to synergistically function with CSF-1 in the CSF-1R-mediated maturation of osteoclastogenesis.

Objectives: Interleukin (IL)-22 acts on non-immune cells to induce anti-microbial responses, protection from tissue damage, and enhance cell regeneration. However, little is known about the involvement of IL-22 in periodontal biology. This study investigated the biological effects of IL-22 on periodontal ligament (PDL) cells as part of studies to assess the involvement of IL-22 in periodontal disease., Materials and Methods: Gene expression levels of IL-22 and its receptors in PDL cells and gingival tissue samples were evaluated by real-time PCR. Proliferative responses and mineralized-matrix forming activities of PDL cells were examined in the presence and absence of IL-22., Results: In contrast to the expression of IL-22 receptors detected in PDL tissues and their cell lines, gingival tissues showed modest or no gene expressions of IL-22. The production of several cytokines including IL-11, IL-8 and CCL2 was upregulated by IL-22 treatment of PDL cells in a dose-dependent manner. IL-22 treatment had no effect on the proliferative response in PDL cells. Meanwhile, IL-22 precipitated mineralized nodule formation and induced gene expressions of RUNX2, MSX2 and osteocalcin in PDL cells, suggesting that IL-22 enhances the mineralized matrix-forming activities of PDL cells., Conclusion: IL-22 has the potential to promote mineralizing activity in PDL cells and to develop appropriate regenerative therapy., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The effect of interleukin-18 (IL-18) on metastasis of highly metastatic LM8 mouse osteosarcoma cells was investigated using nude mice treated with anti-asialo GM1 serum to exclude anti-tumor actions of IL-18 through activation of T and natural killer cells. Injection of LM8 cells which do not express IL-18 receptor β into a tail vain resulted in the formation of pulmonary and hepatic metastatic foci. Daily injection of mice with IL-18 starting the fifth day from the cell injection had no significant effect on the number of metastatic foci, while five daily injections of IL-18 before and after the cell injection resulted in marked decreases. Culture of LM8 cells with IL-18 for 5 days before the injection into mice produced no significant effect on the number of pulmonary and hepatic metastatic foci. In contrast, pretreatment of mice with IL-18 for 5 days before the cell injection markedly decreased metastatic foci. The retention of LM8 cells in the lung 24 h after their injection was also reduced by the pretreatment of mice with IL-18. Serum obtained from mice pretreated with IL-18 for 5 days suppressed mobility of LM8 cells but IL-18 itself did not. These results suggest that IL-18 inhibits metastasis of LM8 cells partly by inducing a factor(s) in the host which suppresses cell mobility. [ABSTRACT FROM AUTHOR]