Search for the bioactive molecules implicated in the regulation of human periodontal ligament cell functions

点击翻译按钮获取中文摘要

The periodontal ligament (PDL) has a critical role of keeping the tooth root intact. We found that cultured human PDL cells (hPDL cells) spontaneously produced nitric oxide (NO). This NO production was not affected by culturing the cells with interleukin-1 β(IL-1 β), However, the NO production was enhanced by stimulating the cells with cyclic tension forces. In an unstimulated hPDL cell culture, concentration of NOィイD22-ィエD2 and NOィイD23-ィエD2 (NOィイD22-ィエD2/NOィイD23-ィエD2), the oxidized products of NO, increased to 140% of the initial value during the first 12 h in newly exchanged medium. In contrast, NOィイD22-ィエD2/NOィイD23-ィエD2 showed a 3-fold increase when the cells had been subjected to cyclic tension forces for 12 h.We employed RT-PCR method for the detection of NO synthase mRNA in the Hpdl cells. Endothelial NO synthase (ecNOS) mRNA was expressed in both stimulated and unstimulated Hpdl cells whereas inducible NO synthase (iNOS) mRNA was detected in neither culturing condition. Furthermore, we found strong ecNOS but not iNOS immunoreactivity in the stimulated Hpdl cells. Mechanically stimulated Hpdl cells were suggested to modulate the functions of periodontal tissue by the upregulated NO production.Expression of receptor activator of NF-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG) was investigated in cultures of hPDL cells. Both RANKL and OPG mRNAs were expressed in the hPDL cells and Northern blot analysis revealed that the OPG mRNA expression was down-regulated remarkably by an application of 1 alpha, 25(OH)ィイD22ィエD2 vitamin D3 (1,25-(OH)ィイD22ィエD2DィイD23ィエD2) and dexamethasone (Dex). In contrast, RANKL mRNA expression was up-regulated by the same treatment. Tartrate-resistant acid phosphatase-positive multinuclear cells were markedly induced when the hPDL cells were co-cultured with bone marrow cells in the presence of an anti-OPG antibody together with 1,25-(OH)ィイD22ィエD2DィイD23ィエD2 and Dex.