Transient receptor potential vanilloid‐1 regulates osteoprotegerin/RANKL homeostasis in human periodontal ligament cells

Background and Objective: Increasing evidence has shown the presence of transient receptor potential vanilloid‐1 (TRPV1) in a variety of nonneuronal tissues; however, the function of TRPV1 in these cells is not well understood. In this study, we aimed to investigate the expression and function of TRPV1 in human periodontal ligament (HPDL) cells. As HPDL cells are known to play an important role in the bone‐remodeling process, we hypothesized that TRPV1 might be implicated in the regulation of osteoprotegerin (OPG) and RANKL expression. Material and Methods: TRPV1 expression was examined by western blot analysis. The function of TRPV1 was studied using capsaicin, a well‐known TRPV1 agonist. RT‐PCR was performed to study the expression of OPG and RANKL mRNAs. The expression of OPG and RANKL proteins was analyzed by ELISA and western blotting, respectively. The mechanisms of capsaicin‐induced OPG expression in HPDL cells were studied using inhibitors. Results: In this study we found that TRPV1 was present in HPDL cells. Treatment with capsaicin induced OPG expression in a dose‐dependent manner but did not affect the expression of RANKL. The increase of the OPG/RANKL ratio was also found in human osteoblasts, but not in MC3T3‐E1 cells, a mouse osteoblastic cell line, suggesting species specificity. Capsazepine, the competitive TRPV1 antagonist, significantly abolished the effect of capsaicin on OPG expression in HPDL cells. In addition, studies investigating the effects of a calcium chelator and a phospholipase C inhibitor indicated that calcium ions and phospholipase C were required for the induction. Interestingly, capsaicin was able to increase the OPG/RANKL ratio, even in the presence of prostaglandin E2, a potent inducer of RANKL. Conclusion: Our study demonstrates that activation of TRPV1 leads to an increase of the OPG/RANKL ratio in HPDL cells. These findings suggest the novel function of TRPV1 in periodontal tissues, at least, as the regulator of the OPG/RANKL axis.     

Expression of receptor activator of NF-kappa B ligand and osteoprotegerin in culture of human periodontal ligament cells

The receptor activator of NF-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG), are the important proteins implicated in osteoclastogenesis. In this study, we investigated the expressions of RANKL and OPG in cultured human periodontal ligament (PDL) cells and their roles in osteoclastogenesis. Northern blotting revealed that the OPG mRNA was down-regulated remarkably by application of 10-8 m one-alpha, 25-dihydroxyvitamin D3[1,25-(OH)2D3] and 10-7 m dexamethasone (Dex). In contrast, RANKL mRNA was up-regulated by the same treatment. Western blotting demonstrated decrease of OPG by the application of 1,25-(OH)2D3 and Dex. Tartrate-resistant acid phosphatase-positive multinuclear cells were markedly induced when the PDL cells were cocultured with mouse bone marrow cells in the presence of an anti-OPG antibody together with 1,25-(OH)2D3 and Dex. These results indicate that PDL cells synthesize both RANKL and OPG and that inactivation of OPG may play a key role in the differentiation of osteoclasts.     

1,25-(OH)2D3作用下人牙周膜细胞破骨细胞分化因子及破骨细胞发生抑制因子的表达及意义

目的观察1,25-二羟基维生素D3[1,25-(OH)2D3]对体外人牙周膜细胞(HPDLC)破骨细胞分化因子(ODF)mRNA及破骨细胞发生抑制因子(OCIF)mRNA表达的影响,探讨正畸牙周组织改建的分子机制。方法以不同浓度的1,25-(OH)2D3(0、1×10-10、1×10-8、1×10-6mol/L)作用于体外培养的人牙周膜细胞,利用原位杂交染色及RT-PCR检测技术,检测不同浓度的1,25-(OH)2D3作用于体外培养人牙周膜细胞ODF、OCIFmRNA表达的强度变化。结果随1,25-(OH)2D3浓度的升高,人牙周膜细胞ODFmRNA的表达升高,而OCIFmRNA的表达降低。结论1,25-(OH)2D3在体外可影响人牙周膜细胞ODFmRNA和OCIFmRNA的表达,从而通过调节ODF和OCIF相对含量的变化,影响牙周组织改建过程。     

Mitogen-activated protein kinases mediate interleukin-1beta-induced receptor activator of nuclear factor-kappaB ligand expression in human periodontal ligament cells

BACKGROUND AND OBJECTIVE: Interleukin-1beta-stimulated receptor activator of nuclear factor-kappaB ligand (RANKL) expression in human periodontal ligament cells is partially mediated by endogenous prostaglandin E2, whereas mitogen-activated protein kinases (MAPKs) are implicated in regulating various interleukin-1-responsive genes. We investigated herein the involvement of MAPKs in interleukin-1beta-stimulated RANKL expression in human periodontal ligament cells. MATERIAL AND METHODS: Human periodontal ligament cells were pretreated separately with specific inhibitors of MAPKs, including extracellular signal-regulated kinase, p38 MAPK and c-Jun N-terminal kinase, and subsequently treated with interleukin-1beta. Following each treatment, the phosphorylation of each MAPK, the expression of RANKL, and the production of prostaglandin E2 were determined. RANKL activity was evaluated using an assay to determine the survival of prefusion osteoclasts. RESULTS: Interleukin-1beta induced RANKL expression at the mRNA and protein levels, as well as RANKL activity in human periodontal ligament cells. Interleukin-1beta also activated extracellular signal-regulated kinase, p38 MAPK, and c-Jun N-terminal kinase. Pretreatment with each MAPK inhibitor partially, but significantly, suppressed interleukin-1beta-induced RANKL expression and its activity, as well as prostaglandin E2 production. CONCLUSION: In human periodontal ligament cells, three types of MAPK inhibitor may abrogate RANKL expression and activity induced by interleukin-1beta, directly or indirectly through partial suppression of prostaglandin E2 synthesis. In addition, extracellular signal-regulated kinase, p38 MAPK, and c-Jun N-terminal kinase signals may co-operatively mediate interleukin-1beta-stimulated RANKL expression and its activity in those cells.     

骨化三醇对人牙周膜细胞维生素D受体、RANKL和骨保护因子表达的调节

目的 探讨骨化三醇(又称1α,25-二羟维生素D3,以下简称VD3)对人牙周膜细胞(human periodontal ligament cells,hPDLC)维生素D受体(vitamin D receptor,VDR)、核因子κB受体活化因子配体(receptor activator of nuclear factor-kappa B ligand,RANKL)和骨保护因子(osteoprotegerin,OPG)表达的调节作用及相关机制.方法 原代培养12个供体来源的hPDLC群,传代培养至第3代,分别以10-8 mol/L VD3(VD,组)和0.1%无水乙醇处理(对照组),6 d后用实时荧光定量反转录聚合酶链反应(RT-PCR)法检测VDR、RANKL和OPG mRNA的表达水平.分析12个细胞群RANKL基因转录起始位点上游调控区DNA碱基序列.结果 VD3组与对照组相比,VDR mRNA表达水平显著上调(P=0.003),为对照组的(3.04±1.06)倍;RANKL mRNA表达水平显著升高(P=0.001),为对照组的9.82(0.75～119.18)倍;OPG mRNA表达水平为对照组的(94.48±39.15)%,P=0.136;OPG/RANKL比值显著下调(P=0.003),为对照组的10.36%(1.01%～138.00%).未发现RANKL基因上游调控区序列突变位点;-1832(m7984870,C/G)多态性位点基因型与RANKL mRNA的表达和调节之间无显著相关性.结论 在hPDLC中,VD3可以促进VDR mRNA的表达;VD3可显著上调RANKL mRNA的表达从而降低OPG/RANKL比值,而对OPG mRNA的表达水平影响较小.在VD3作用下,细胞群间RANKL mRNA表达的差异性可能与RANKL基因上游调控区碱基序列无关.     

Osteogenic induction and 1,25-dihydroxyvitamin D3 oppositely regulate the proliferation and expression of RANKL and the vitamin D receptor of human periodontal ligament cells

Objective

Human periodontal ligament cells (hPDLCs) may play an important role in osteoclastogenesis in alveolar bone by expressing the receptor activator of NF-KappaB ligand (RANKL) and osteoprotegerin (OPG). The present study aimed to investigate the differences between the effects of osteogenic induction and 1,25-dihydroxyvitamin D₃ (VD₃) on hPDLC proliferation and the expression of RANKL, osteoprotegerin, and the vitamin D receptor (VDR) in hPDLCs.

Methods

Primary cultures of 11 hPDLC populations from 11 donors were obtained. Three samples of each hPDLC population from passage 3 were, respectively, treated with osteogenic induction medium, 10⁻⁸ M VD₃, or vehicle as a control. Cell proliferation at days 0, 1, 3, 5, and 7 was estimated with the MTT method. At day 6, the mRNA levels of RANKL, OPG and VDR were determined with real-time RT-PCR.

Results

Osteogenic induction significantly promoted hPDLC proliferation, while VD₃ inhibited proliferation. Osteogenic induction significantly down-regulated the mRNA level of RANKL by 1.61-fold (P = 0.033) and decreased the level of VDR by 2.13-fold (P = 0.003), while there was no change in the level of OPG and OPG/RANKL ratio with osteogenic induction. On the contrary, VD₃ significantly up-regulated the level of RANKL by 9.58-fold (P = 0.001) and increased the level of VDR by 3.15-fold (P = 0.004), while down-regulating the OPG/RANKL ratio by 7.14-fold (P = 0.004).

Conclusion

Osteogenic induction and VD₃ exert opposite effects in regulating hPDLC proliferation and mRNA expression of RANKL and VDR. This may induce hPDLCs to play different roles in alveolar bone metabolism.     

Effect of smoking on concentrations of receptor activator of nuclear factor κ B ligand and osteoprotegerin in human gingival crevicular fluid

Aim: To compare the levels of the soluble receptor activator of nuclear factor κ B ligand (sRANKL), osteoprotegerin (OPG) and their relative ratio in gingival crevicular fluid (GCF) among periodontitis patients with varying smoking histories.
Material and Methods: GCF samples were collected from 149 periodontitis patients who were never smokers ( n =58), former smokers ( n =39) and current smokers ( n =52). sRANKL and OPG concentrations in GCF were measured by enzyme-linked immunosorbent assays.
Results: sRANKL, OPG and their relative ratio were not statistically significant among the never smokers, former smokers and current smokers. However, OPG was significantly reduced and subsequently the sRANKL:OPG ratio was significantly increased in the high pack-years group as compared with never smokers. The positive correlation between pack-years and the sRANKL:OPG ratio remained statistically significant after adjusting for age and current smoking status.
Conclusion: Increased lifetime exposure to cigarette smoking above a minimum threshold suppresses OPG production and leads to increased sRANKL:OPG. This may partially explain increased bone loss in smoking-related periodontitis.     

人牙周膜细胞在弹性牵张力作用下核心结合因子mRNA的表达

目的 探讨人牙周膜细胞在应力作用下的成骨特性及核心结合因子(corebinding factor a 1，cbfal)在正畸成骨和正畸牙齿移动中的作用机制。方法 体外原代培养新生SD大鼠颅骨成骨细胞，进行大鼠cbfal cDNA片段的克隆和序列测定，制备大鼠cbfal cDNA探针。人牙周膜细胞在弹性膜上体外培养，采用体外培养细胞加载系统加载弹性牵张力。用原位杂交方法检测cbfal mRNA的表达。结果 正常对照组不加力的人牙周膜细胞未检测到cbfal mRNA阳性表达，实验组加载弹性牵张力的人牙周膜细胞出现cbfal mRNA阳性表达。结论 弹性牵张力可以诱导人牙周膜细胞向成骨样细胞分化；cbfal作为转录因子是正畸成骨的调控途径之一。     

周期性牵张力对人牙周膜细胞MMP-3及TIMP-1表达的影响

目的 :探讨周期性牵张力对人牙周膜细胞MMP -3及TIMP -1蛋白表达的影响 ,进一步阐明正畸牙牙周组织改建过程中ECM代谢调节的分子机制 .方法 :通过体外细胞培养加载系统 ,选择频率为 6周 /min ,弹性基底膜发生 12 %形变率的周期性牵张力 ,利用免疫组化及夹心ELISA检测技术 ,观察HPDLC表达MMP -3及TIMP -1的相对强度。结果 :HPDLC在体外表达MMP -3及TIMP -1。加载 3d后 ,MMP -3表达明显增强 ,与对照组相比具有显著性差异。而TIMP -1对机械力无应答。结论 :在一定条件下 ,周期性牵张力可显著影响HPDLCMMP -3蛋白的表达。为机械力作用下MMP -3参与牙周组织ECM代谢提供了直接证据     

不同浓度1,25-二羟基维生素D3对大鼠正畸牙移动速度的影响

目的 研究牙周局部注射3种浓度的1,25-二羟基维生素D3[1,25-(OH)2D3]对大鼠正畸牙移动速度的影响.方法 成年健康雄性Wistar大鼠96只,随机分为对照组、A组、B组和C组,每组24只.在大鼠上颌左侧第一磨牙与上颌中切牙之间安放加力装置,每隔3 d注射药物10 μL.对照组注射生理盐水,A组注射10-10 mol/L的1,25-(OH)2D3,B组注射10-8 mol/L的1,25-(OH)2D3,C组注射10-6 mol/L的1,25-(OH)2D3,分别于加力后的第1、 3、 7和14天各组处死6只大鼠.制取标本后测量第一磨牙移动距离.结果 对照组、A组和C组大鼠在正畸牙移动过程中均存在明显的正畸牙移动减慢时期,B组大鼠观察到持续的牙移动而没有移动减慢时期.结论 在大鼠正畸牙移动过程中,应用一定浓度的1,25-(OH)2D3能促进正畸牙的移动. 10-8 mol/L的1,25-(OH)2D3能更有效地促进大鼠正畸牙的移动,避免正畸牙移动过程中缓慢时相的发生.     

Expression of receptors for basic fibroblast growth factor on human periodontal ligament cells

Basic fibroblast growth factor (FGF-2; bFGF) is a major mitogen for connective tissue cells, and participates in the healing process. It has already been reported that FGF-2 could be applicable to enhance periodontal regeneration. In the present study, we examined FGF receptor (FGFR) expression on human periodontal ligament (PDL) cells. The binding of [¹²⁵I]-labeled FGF-2 to human PDL cells was studied by radioreceptor assay. The binding of [¹²⁵I]-FGF-2 to PDL cells reached a plateau after 2.5 h incubation at 4°C and was inhibited by the addition of unlabeled FGF-2 and acidic FGF (FGF-1; aFGF), but not insulin-like growth factor-I, platelet-derived growth factor and transforming growth factor-β₁. Scatchard analysis revealed the presence of approximately 1.0 × 10⁵ FGF-2 binding sites per cell with an apparent Kd of 1.2 × 10⁻¹⁰ M. Interestingly, the binding of [¹²⁵I]-FGF-2 on PDL cells reached its maximum at d 6 of the culture and then gradually decreased. Scatchard analysis also demonstrated that the number of FGFRs on a PDL cell was altered during the course of the culture, while the affinity between FGF-2 and its receptor was not. The responsiveness of PDL cells to FGF-2, which was monitored by the inhibitory effect on alkaline phosphatase activity, was reduced in proportion to the decrease in the number of FGFRs on the PDL cells. The present study suggests that PDL cells alter the responsiveness to FGF-2 during the course of the culture by changing the density of its receptor, and that the density of FGFR expression might be a marker of the cytodifferentiation of PDL cells into mineralized tissue forming cells.     

茶多酚对脂多糖介导下人牙周膜成纤维细胞 MMP-1、MMP-2表达的影响

目的：观察茶多酚（TP）在脂多糖（LPS）介导下对人牙周膜成纤维细胞（HPDLCs）MMP-1、MMP-2表达的影响。方法：体外培养 HPDLCs,在培养液中添加 TP（200μg/ml）作用于脂多糖（100μg/ml）介导的 HPDLCs,培养24、48、72 h,ELISA法检测 HPDLCs 分泌 MMP-1和 MMP-2的量。荧光实时定量 PCR 法检测 HPDLCs 中 MMP-1和 MMP-2 mRNA 的表达。结果：在 LPS 介导下 HPDLCs MMP-1和 MMP-2分泌量和基因表达升高,TP 可抑制 LPS 介导下 HPDLCs MMP-1和 MMP-2表达。结论：TP 可抑制 LPS 介导的人牙周膜细胞的胶原降解。     

乳铁蛋白对人牙周膜细胞增殖迁移分化的影响

目的：观察乳铁蛋白（lactoferrin,LF）对体外培养的人牙周膜细胞（HPDLCs）增殖、迁移和成骨分化的影响。方法：原代培养并鉴定人牙周膜细胞,稳定传代后用 MTT 比色法、Transwell 法及划痕试验检测浓度分别为0、10、20μg／ml 的乳铁蛋白对牙周膜细胞增殖和迁移的影响;矿化条件下,0、10、20μg／ml 的乳铁蛋白作用牙周膜细胞后,茜素红染色法和实时荧光定量 PCR 检测矿化能力及成骨相关基因的表达。结果：10、20μg／ml 乳铁蛋白均能促进 HPDLCs 增殖、迁移（P ＜0．05）。10、20μg／ml 乳铁蛋白组矿化结节数量增多（P ＜0．05）,碱性磷酸酶（ALP）、骨钙蛋白（OCN）、骨桥蛋白（OPN）表达量均有升高（P ＜0．05）。结论：乳铁蛋白能够促进人牙周膜细胞增殖、迁移与成骨分化。     

FGF2基因转染对人牙周膜细胞生物学性状的影响

目的:探讨碱性成纤维细胞生长因子(Fibroblast Growth Factor 2,FGF2)基因转染对人牙周膜细胞(Periodontalligament cells,PDLCs)生物学性状的影响.方法:将FGF2基因转入PDLCs,通过免疫组化SABC及免疫印记法检测其稳定表达,并检测转基因细胞增殖活力及碱性磷酸酶合成情况.结果:免疫细胞化学证实转染与未转染细胞均在胞浆内表达FGF2,但转染FGF2细胞较未转染组染色深,免疫印迹杂交结果显示转染前后均表达17KD FGF2,但转染后表达量增高.FGF2基因转染可增强细胞增殖能力,但碱性磷酸酶活性未见明显变化(P＞0.05).结论:FGF2基因能被转入PDLCs并得到稳定表达,转基因细胞增殖与合成明显增强,但转染FGF2基因不能促进细胞分化.     

SPARC stimulates the synthesis of OPG/OCIF, MMP-2 and DNA in human periodontal ligament cells

BACKGROUND: Osteonectin/secreted protein, acidic and rich in cysteine (SPARC) is expressed in periodontal ligaments. Therefore, a better understanding of the action of SPARC on periodontal ligament cells could help to elucidate remodelling and repair mechanisms in periodontal tissue. In the present study, we examined the effects of human platelet-derived SPARC (hp-SPARC) on the expressions of SPARC and osteoprotegerin/osteoclastogenesis inhibitory factor (OPG/OCIF), alkaline phosphatase (ALPase) activity, matrix metalloproteinase-2 (MMP-2) production and DNA synthesis in cultures of human periodontal ligament (HPL) cells. METHODS: HPL cells at the sixth passage were exposed to hp-SPARC. The expression of OPG/OCIF and SPARC mRNAs was examined by Northern blot analysis. The protein levels for OPG/OCIF and MMP-2 were determined by Western blot analysis. ALPase activity was measured by the method of Bessey et al. DNA synthesis was estimated by incorporation of [3H] thymidine. RESULTS: Hp-SPARC enhanced OPG/OCIF synthesis at the protein and mRNA levels. Hp-SPARC also enhanced DNA and MMP-2 synthesis dose-dependently, but had little effect on ALPase activity and SPARC mRNA expression. CONCLUSION: SPARC may play a role in remodelling and repair of periodontal tissue by promoting proliferation and MMP-2 production. It may also regulate osteoclast formation through OPG/OCIF in periodontal ligament cells.     

Toll样受体2和4在脂多糖诱导人牙周膜成纤维细胞表达细胞核因子-κB受体活化因子配基中的作用

目的 观察在脂多糖（LPS）刺激下,人牙周膜成纤维细胞（HPDLFs）中Toll样受体2（TLR2）和Toll样受体4（TLR4）表达水平的抑制对其表达细胞核因子-κB受体活化因子配基（RANKL）的影响。方法 选用100 ng·mL-1、1 μg·mL-1、10 μg·mL-1大肠杆菌LPS分别刺激HPDLFs,刺激6、12、24、48 h后,采用酶联免疫吸附试验（ELISA）检测HPDLFs表达RANKL的水平。分别运用不同滴度的anti-TLR2+anti-TLR4、anti-TLR2、anti-TLR4抗体预处理HPDLFs,观察
1 μg·mL-1 LPS刺激下,其RANKL表达水平的变化。结果 LPS刺激HPDLFs 6 h后,即可检测到RANKL的表达,24 h达到顶峰,然后逐渐下降;各LPS质量浓度组的规律基本一致。分别用anti-TLR2+anti-TLR4、anti-TLR2、anti-TLR4抗体预处理HPDLFs,在1 μg·mL-1 LPS刺激下,其产生RANKL的水平明显下降（P<0.05）;3组中,RANKL的表达水平有明显差异（P<0.05）,其中anti-TLR2+anti-TLR4抗体处理组RANKL表达量最少,anti-TLR4抗体处理组次之,anti-TLR2
抗体处理组RANKL的表达量最高。结论TLR2、TLR4均参与了LPS诱导HPDLFs表达RANKL的过程;与anti-TLR2抗体相比,anti-TLR4抗体能更有效地抑制LPS刺激后HPDLFs表达RANKL的能力。