核转录因子-κB受体活化因子及其配体和骨保护蛋白系统在骨构建与骨改建中的作用

核转录因子-κB受体活化因子配体(RANKL)-核转录因子-κB受体活化因子(RANK)-骨保护蛋白(OPG)系统是近年发现的调节骨吸收的关键信号通路.RANKL与RANK结合在正常骨构建与骨改建中调节破骨细胞生成、活化和存留,在多种病理状况下增加骨吸收.OPG与RANK竞争性地结合RANKL,以防止骨组织的过度吸收.笔者分别就RANKL、RANK和OPG及其在骨构建与骨改建中的作用作一综述.     

牙周炎症状态下不同B细胞亚群对破骨细胞调控作用的研究进展

牙槽骨吸收是牙周炎的重要临床表现,持续性骨丧失最终会引起牙齿的松动和脱落,影响患者的生活质量。破骨细胞形成增多及活性增强是牙槽骨吸收的前提,由菌斑微生物所引起的宿主免疫反应对破骨细胞的调控作用是牙槽骨吸收的主要影响因素。B细胞是牙周炎症状态下主要的免疫效应细胞,在炎性牙周组织中占据主导地位。研究表明,牙周炎症状态下不同B细胞亚群对破骨细胞的调控作用不尽相同。文章就浆细胞、记忆B细胞、B-1细胞和调节性B细胞等不同B细胞亚群对破骨细胞的调控作用及其机制予以综述,为牙周炎患者免疫治疗提供有利的线索。     

OPG/RANKL对骨改建的调控作用

通过破骨细胞对旧骨的吸收和成骨细胞的新骨形成,骨组织发生空间形态的改变,这种新骨替代旧骨的过程称为骨改建.绝经后的骨质疏松症和许多病变中骨改建率增加,但新骨形成不足,骨量减少,骨折几率增加.骨吸收依赖于被称为RANKL的细胞因子,而OPG与RANKL结合后,可阻止其单一同源受体RANK的活化.大量的体内和体外实验表明,RANKL与OPG的比例是影响骨吸收和骨改建的重要决定因素之一.     

骨保护蛋白在牙周组织再生中的应用

核因子-KB受体活化因子配体(RANKL)/核因子-κB受体活化因子(RANK)/骨保护蛋白(OPG)是调节破骨细胞分化和成熟以及骨吸收功能的关键因子,在牙周炎发病中起重要的调节作用.OPG可抑制破骨细胞的分化,抑制成熟破骨细胞的骨吸收活性并诱导其程序性死亡.本文就RANKL/OPG调节系统、RANKL/OPG调节系统...     

抑制核因子-κB受体活化因子及其配体通路治疗牙周炎的研究进展

核因子-κB受体活化因子(RANK)及其配体(RANKL)在牙周炎患者的牙槽骨吸收中具有重要的作用,抑制RANKL/RANK通路,可有效抑制破骨细胞的分化和激活,从而抑制牙槽骨的吸收。骨保护蛋白(OPG)可和RANKL结合,干扰RANKL和RANK的结合,从而防止骨组织的过度破坏。本文就RANKL/RANK/OPG轴、RANKL/RANK/OPG与牙周炎、抑制RANKL/RANK通路治疗牙周炎的可行性等研究进展作一综述。     

抑制核因子-κB受体活化因子及其配体通路治疗牙周炎的研究进展

核因子-κB受体活化因子（RANK）及其配体（RANKL）在牙周炎患者的牙槽骨吸收中具有重要的作用,抑制RANKL／RANK通路,可有效抑制破骨细胞的分化和激活,从而抑制牙槽骨的吸收。骨保护蛋白（OPG）和RANKL结合,干扰RANKL和RANK的结合,从而防止骨组织的过度破坏。本文就RANKL／RANK／OPG轴、RANKL／RANK／OPG与牙周炎、抑制RANKL／RANK通路治疗牙周炎的可行性等研究进展作一综述。     

骨保护蛋白-核因子-κB受体活化因子配体-核因子-κB受体活化因子系统与牙萌出

牙萌出是一个复杂而且被严密调控的生理现象,需要分化成熟的破骨细胞作用于牙胚方向的牙槽骨使之形成萌出通道,而骨保护蛋白-核因子-κB受体活化因子配体-核因子-κB受体活化因子系统则可通过调节破骨细胞来调节骨的代谢。巨噬细胞集落刺激因子-1和甲状旁腺激素相关蛋白则可使核因子-κB受体活化因子配体蛋白更好地发挥促破骨细胞的分化和激活作用,以保证牙萌出时牙槽骨能被正常吸收。     

破骨细胞活化因子及其在牙周炎发病中的作用

破骨细胞活化因子是一组具有诱导破骨细胞形成、刺激其活性,引起破骨吸收的生物活性因子,包括IL-(?)β,IL-1α,TNFα和TNFβ等。本文简述了这些细胞因子的产生及生物活性,重点讨论了这些细胞因子对骨吸收的调节作用,并就其与牙周病的关系作一论述。     

Identification of the osteoprotegerin/receptor activator of nuclear factor-kappa B ligand system in gingival crevicular fluid and tissue of patients with chronic periodontitis

BACKGROUND AND OBJECTIVE: Recent findings have suggested that osteoclastogenesis is directly regulated by receptor activator of nuclear factor-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG). However, no studies have described interactions of OPG/RANKL and the gp130 cytokine family in periodontal disease. This study aimed to identify and quantify OPG/RANKL in the gingival crevicular fluid (GCF) and connective tissue of patients with periodontitis, and to clarify possible correlations with disease severity and interleukin-6 (IL-6) cytokines. MATERIAL AND METHODS: Ninety-five sites in 20 patients with generalized chronic periodontitis were divided into four groups by site based on probing depth (PD) and bleeding on probing (BOP). In periodontitis patients, GCF was obtained using sterile paper strips from clinically healthy sites (PD 6 mm with BOP, n = 27). Fourteen clinically healthy sites from four periodontally healthy individuals were used as the control group. The levels of OPG, RANKL and two gp130 cytokines - IL-6 and oncostatin M (OSM) - in the GCF were determined by an enzyme-linked immunosorbent assay (ELISA) and are expressed as total amounts (pg/site). Immunohistochemical localization of OPG- and RANKL-positive cells was also performed on gingival connective tissues harvested from patients with periodontitis (inflammatory group, n = 8 biopsies) and from non-diseased individuals (healthy group, n = 8 biopsies). RESULTS: GCF RANKL, but not OPG, was elevated in diseased sites of patients with periodontitis. However, the expressions of OPG and RANKL showed no correlation with disease severity (r = 0.174 and 0.056, respectively), but the content of RANKL in the GCF was significantly positively correlated with those of IL-6 (r = 0.207) and OSM (r = 0.231) (p < 0.01). Immunohistochemical staining showed that RANKL-positive cells were significantly distributed in the inflammatory connective tissue zone of diseased gingiva, compared with those of samples from non-diseased persons (p < 0.01). However, few OPG-positive cells were found in connective tissue zones of either the diseased gingiva or healthy biopsies. CONCLUSION: These findings imply that in this cross-sectional study of GCF, RANKL, IL-6 and OSM were all prominent in periodontitis sites, whereas OPG was inconsistently found in a few samples of diseased sites but was undetectable in any of the control sites. The results also imply that the expression of RANKL was positively correlated with IL-6 and OSM in the GCF.     

Expression of receptor activator of nuclear factor κB ligand in ligature-induced periodontitis in osteoporotic and non-osteoporotic rats

Allam E, Draz A, Hassan A, Neamat A, Galal M, Windsor LJ. Expression of receptor activator of nuclear factor κB ligand in ligature‐induced periodontitis in osteoporotic and non‐osteoporotic rats. J Periodont Res 2009; doi: 10.1111/j.1600‐0765.2009.01210.x. © 2009 The Authors. Journal compilation © 2009 Blackwell Munksgaard Background and Objective: This study investigated the expression of a key mediator that regulates differentiation of osteoclasts, receptor activator of nuclear factor κB ligand (RANKL), in rats with or without osteoporosis and periodontitis, to provide a better understanding of the association between these two diseases. Material and Methods: Forty adult Albino rats were divided into four groups: (1) control group; (2) experimentally induced periodontitis group; (3) experimentally induced osteoporosis group; and (4) experimentally induced osteoporosis and periodontitis group. At the end of the experimental period, blood samples were obtained and animals were sacrificed. Serum alkaline phosphatase (ALP) activity levels were measured. Histological evaluation and immunohistochemical detection of RANKL in the periodontal ligament and bone tissues were performed. Results: There were significantly higher ALP levels in all of the experimental groups than in the control group. The pathology observed in the histological sections from group 4 was more severe than in either group 2 or group 3. The percentage of RANKL‐immunoreactive cells in both the periodontal ligament and bone tissues in group 4 (16.8 ± 5.1 and 11.2 ± 5.2%, respectively) was significantly higher (p < 0.001) than in the other groups. In the periodontal ligament, the percentage of RANKL‐immunoreactive cells in group 2 (10.1 ± 1.9%) was significantly higher (p < 0.001) than in group 3 (5.3 ± 2.7%) and the control group (4.12 ± 1.5%). Conclusion: The increased bone loss observed in group 4 compared with either group 2 or group 3 supports the existence of an additive pathological effect of the two disease conditions. This is consistent with the increased RANKL expression observed in group 4.     

T cells are able to promote lipopolysaccharide-induced bone resorption in mice in the absence of B cells

Background and Objective:  T cells and their cytokines are believed to be key factors in periodontal disease and bone resorption. We previously showed that T cells transferred to nude mice were related to inflammatory bone resorption in vivo . However, it has not been clarified whether T cells can induce bone resorption in the absence of B cells. In this study, we therefore investigated the ability of T cells to induce bone resorption without B cells, using both T cell- and B cell-deficient mice with severe combined immune deficiency (SCID).
Material and Methods:  Escherichia coli lipopolysaccharide (LPS) was injected into the gingivae of SCID mice reconstituted by T cells (SCID + T mice). Wild-type C.B-17 mice and SCID mice were used as control animals. Alveolar bone resorption and production of cytokines in the gingivae were then compared histopathologically and immunohistologically.
Results:  The degree of bone resorption in SCID + T mice was significantly greater than that in SCID mice but less than that in wild-type mice. The same tendency was found for expression of receptor activator of nuclear factor κB ligand. The number of interferon-γ-positive cells in SCID + T mice was the highest of the three groups. In contrast, interleukin-4-positive cells were detected in wild-type mice but not in SCID + T and SCID mice.
Conclusion:  The results suggest that T cells are able to promote LPS-induced bone resorption in the absence of B cells. The expressions of cytokines in the presence of B cells are quite different.     

Experimental periodontitis in mice selected for maximal or minimal inflammatory reactions: increased inflammatory immune responsiveness drives increased alveolar bone loss without enhancing the control of periodontal infection

Background and Objective: Inflammatory immune reactions that occur in response to periodontopathogens are thought to protect the host against infection, but may trigger periodontal destruction. However, the molecular and genetic mechanisms underlying host susceptibility to periodontal infection and to periodontitis development have still not been established in detail. Material and Methods: In this study, we examined the mechanisms that modulate the outcome of Aggregatibacter (Actinobacillus) actinomycetemcomitans‐induced periodontal disease in mice mouse strains selected for maximal (AIRmax) or minimal (AIRmin) inflammatory reactions. Results: Our results showed that AIRmax mice developed a more severe periodontitis than AIRmin mice in response to A. actinomycetemcomitans infection, and this periodontitis was characterized by increased alveolar bone loss and inflammatory cell migration to periodontal tissues. In addition, enzyme‐linked immunosorbent assays demonstrated that the levels of the cytokines interleukin‐1β, tumor necrosis factor‐α and interleukin‐17 were higher in AIRmax mice, as were the levels of matrix metalloproteinase (MMP)‐2, MMP‐13 and receptor activator of nuclear factor‐κB ligand (RANKL) mRNA levels. However, the more intense inflammatory immune reaction raised by the AIRmax strain, in spite of the higher levels of antimicrobial mediators myeloperoxidase and inducible nitric oxide synthase, did not enhance the protective immunity to A. actinomycetemcomitans infection, because both AIRmax and AIRmin strains presented similar bacterial loads in periodontal tissues. In addition, the AIRmax strain presented a trend towards higher levels of serum C‐reactive protein during the course of disease. Conclusion: Our results demonstrate that the intensity of the inflammatory immune reaction is associated with the severity of experimental periodontitis, but not with the control of A. actinomycetemcomitans periodontal infection, suggesting that the occurrence of hyperinflammatory genotypes may not be an evolutionary advantage in the complex host–pathogen interaction observed in periodontal diseases.     

白细胞介素-21和核因子κB受体活化因子配体在人根尖囊肿和肉芽肿中的表达及临床意义

目的 检测白细胞介素-21（IL-21）和破骨细胞核因子κB受体活化因子配体（RANKL）在根尖囊肿和根尖肉芽肿中的表达,分析两者在根尖周病中的关系,探讨IL-21在根尖周炎发病机制中的作用。方法 收集根尖囊肿23例和根尖肉芽肿32例作为实验组,记录相关病例的病损大小及有无叩痛表现;10例健康牙龈组织为对照组。利用免疫组织化学法检测所有样本中IL-21和RANKL蛋白的表达水平,分析IL-21的表达水平与RANKL表达、根尖病灶大小及叩痛的相关性。结果 所有病变组织均可检测到IL-21阳性细胞,而健康牙龈组织则未检测到IL-21的表达。根尖囊肿和肉芽肿中IL-21的表达强度分别为59.92±6.57和36.80±6.81,RANKL的表达强度分别为68.81±18.59和36.12±14.87。根尖囊肿组两种蛋白的表达水平均高于肉芽肿组（P<0.05）。相关性分析表明,IL-21的表达水平与RANKL及根尖病灶大小均呈正相关关系（P<0.05）。结论 IL-21存在于人慢性根尖周炎病损组织中,其表达水平与RANKL的表达量及病损大小呈正相关关系;IL-21可能通过促进RANKL蛋白的表达参与慢性根尖周炎的发病机制。     

Notch信号促进核因子κB受体活化因子配体诱导的破骨细胞分化的体外研究

目的 探讨Notch信号抑制对核因子κB受体活化因子配体（RANKL）诱导的小鼠RAW264.7细胞向破骨细胞分化的影响。方法 建立RANKL诱导的小鼠RAW264.7细胞体外分化模型,实时定量聚合酶链反应（real-time PCR）检测Notch信号成分（Notch1、Notch2、Delta1、Jagged1）、下游靶基因Hes1以及破骨细胞标志基因抗酒石酸酸性磷酸酶（TRAP）和Cathepsin K在诱导前后mRNA的表达。在诱导体系中加入不同浓度的γ分泌酶抑制剂（GSI）,抑制Notch受体的表达,TRAP染色检测破骨细胞分化的变化情况。结果 50 ng•mL-1 RANKL诱导小鼠RAW264.7细胞3 d,Notch1、Notch2、Delta1、Jagged1及Hes1的mRNA表达均有不同程度的提高,其中以Notch2、Jagged1增高最明显;破骨细胞标志基因表达显著增高。在RANKL诱导的同时加入不同浓度GSI,抑制Notch的表达,可致Notch下游靶基因Hes1表达下降,同时TRAP阳性细胞计数显著减少,且呈剂量依赖性。结论 Notch信号可促进RANKL诱导的RAW264.7细胞向破骨细胞分化。     

Receptor activator NF kappaB ligand (RANKL) and osteoprotegerin (OPG) protein expression in periodontitis

OBJECTIVES AND BACKGROUND: This study investigated the expression of key mediators that regulate differentiation of osteoclasts, receptor activator of nuclear factor kappaB ligand (RANKL), and its natural inhibitor, osteoprotegerin (OPG), in periodontitis. We aimed to compare the levels of the RANKL and OPG in the granulomatous tissue adjacent to areas of alveolar bone loss from patients with periodontitis to that present in tissue from patients without periodontitis. In addition, we aimed to determine the types of cells expressing these factors in these tissues and to demonstrate the expression of the osteoclastic markers, RANK and tartrate-resistant acid phosphatase (TRAP), in periodontitis. MATERIALS AND METHODS: Frozen biopsy specimens were analysed using specific monoclonal antibodies and were evaluated by semiquantitative analysis and digital image analysis to compare levels of RANKL and OPG protein expression. Double labelling of frozen sections with antibodies to different cell lineage specific markers was used to determine the types of cells expressing these proteins. In situ hybridization was used to detect cells expressing RANK mRNA. RESULTS: Semiquantitative image analysis demonstrated that significantly higher levels of RANKL protein (P < 0.05) were expressed in the periodontitis tissue. Conversely, OPG protein was significantly lower (P < 0.05) in the periodontitis tissues. RANKL protein was associated with lymphocytes and macrophages. OPG protein was associated with endothelial cells in both tissues. Many leukocytes expressing RANK mRNA and TRAP were observed in periodontitis tissues. CONCLUSION: The change in the levels of these key regulators of osteoclast differentiation may play a major role in the bone loss seen in periodontitis.