CLINICAL Review #: the role of receptor activator of nuclear factor-kappaB (RANK)/RANK ligand/osteoprotegerin: clinical implications

CONTEXT: Receptor activator of nuclear factor-kappaB ligand (RANKL), receptor activator of nuclear factor-kappaB (RANK), and osteoprotegerin (OPG) play a central role in bone remodeling and disorders of mineral metabolism. EVIDENCE ACQUISITION: A PubMed search was conducted from January 1992 until 2007 for basic, observational, and clinical studies in subjects with disorders related to imbalances in the RANK/RANKL/OPG system. EVIDENCE SYNTHESIS: RANK, RANKL, and OPG are members of the TNF receptor superfamily. The pathways involving them in conjunction with various cytokines and calciotropic hormones play a pivotal role in bone remodeling. Several studies involving mutations in the genes encoding RANK and OPG concluded in the discovery of a number of inherited skeletal disorders. In addition, basic and clinical studies established a consistent relationship between the RANK/RANKL/OPG pathway and skeletal lesions related to disorders of mineral metabolism. These studies were a stepping stone in further defining the role of the RANK/RANKL/OPG pathway in osteoporosis, rheumatoid arthritis, bone loss associated with malignancy-related skeletal diseases, and its relationship to vascular calcifications. Subsequently, the further understanding of this pathway led to the development of new therapeutic modalities including the human monoclonal antibody to RANKL and recombinant OPG as a target for treatment of postmenopausal osteoporosis and multiple myeloma. CONCLUSIONS: The RANK/RANKL/OPG system mediates the effects of calciotropic hormones and, consequently, alterations in their ratio are key in the development of several clinical conditions. New agents with the potential to block effects of RANKL have emerged for treatment of postmenopausal osteoporosis and malignancy-related skeletal disease.     

OPG/RANK/RANKL系统与骨折和类风湿性关节炎

骨保护素(OPG)、细胞核因子-κB受体活化因子(RANK)和RANK配体(RANKL)是偶联成骨细胞、基质细胞和破骨细胞分化、活化及生物活性的3种主要细胞因子,其形成的局部调节体系在骨代谢中起十分重要的作用。本文简要介绍了OPG/RANK/RANKL系统及该系统在骨质疏松性骨折发生中的作用,RANKL/OPG比值与骨折的关系,OPG和RANKL对骨折愈合的作用,血清OPG或RAN-KL水平与骨折的联系,OPG基因多态性与骨折关系的研究结果。另外还介绍其在类风湿性关节炎发病机制中的作用,OPG/RANK/RANKL与滑膜组织的联系,OPG治疗的相关实验进展。     

Cross-talk between the interleukin-6 and prostaglandin E(2) signaling systems results in enhancement of osteoclastogenesis through effects on the osteoprotegerin/receptor activator of nuclear factor-{kappa}B (RANK) ligand/RANK system

The osteoprotegerin (OPG)/receptor activator of nuclear factor-kappaB ligand (RANKL)/receptor activator of nuclear factor-kappaB (RANK) system is the dominant and final mediator of osteoclastogenesis. Abnormalities of this system have been implicated in the pathogenesis of many skeletal diseases. Cyclooxygenase (COX)-2 and prostaglandin (PG)E(2), a major eicosanoid product of the COX-2-catalyzed pathway, play key roles in normal bone tissue remodeling. PGE(2) exerts its actions by binding and activating the E series of prostaglandin (EP) receptor. Activation of EP(2) and EP(4) receptors is associated with PGE(2)-induced osteoclast differentiation. IL-6, a major proinflammatory cytokine, has also been reported to induce osteoclast differentiation. Although interactions between the COX-2/PGE(2) and IL-6 systems have been described in bone cells, the mechanisms underlying these cooperative signaling pathways and the possible involvement of the OPG/RANKL/RANK system have not been fully elucidated. We demonstrate that COX-2, PGE(2), and IL-6 stimulate osteoblast growth and osteoclast differentiation. Effects on osteoclast differentiation, particularly with IL-6, were most marked when osteoclast precursor cells were grown in coculture with osteoblasts, indicating a possible role of the RANK/RANKL/OPG system. COX-2 and PGE(2) stimulated osteoclastogenesis through inhibition of OPG secretion, stimulation of RANKL production by osteoblasts, and up-regulation of RANK expression in osteoclasts. PGE(2) stimulated IL-6 secretion by bone cells, whereas COX-2 inhibitors decreased this same parameter. IL-6, in turn, increased PGE(2) secretion, COX-2, and EP receptor subtype expression in bone cells. Finally, IL-6 was the mediator of PGE(2)-induced suppression of OPG production by osteoblasts. These findings provide evidence for cross-talk between the PGE(2) and IL-6 signaling enhance osteoclast differentiation via effects on the OPG/RANKL/RANK system in bone cells.     

Minireview: the OPG/RANKL/RANK system.

The identification of the OPG/RANKL/RANK system as the dominant, final mediator of osteoclastogenesis represents a major advance in bone biology. It ended a long-standing search for the specific factor produced by preosteoblastic/stromal cells that was both necessary and sufficient for osteoclast development. The initial cloning and characterization of OPG as a soluble, decoy receptor belonging to the TNF receptor superfamily was the first step that eventually led to an unraveling of this system. Soon thereafter, the molecule blocked by OPG, initially called OPG-ligand/osteoclast differentiating factor (ODF) and subsequently RANKL, was identified as the key mediator of osteoclastogenesis in both a membrane-bound form expressed on preosteoblastic/stromal cells as well as a soluble form. RANKL, in turn, was shown to bind its receptor, RANK, on osteoclast lineage cells. The decisive role played by these factors in regulating bone metabolism was demonstrated by the findings of extremes of skeletal phenotypes (osteoporosis vs. osteopetrosis) in mice with altered expression of these molecules. Over the past several years, work has focused on identifying the factors regulating this system, the signaling mechanisms involved in the RANKL/RANK pathway, and finally, potential alterations in this system in metabolic bone disorders, from the extremely common (i.e. postmenopausal osteoporosis) to the rare (i.e. familial expansile osteolysis).     

Skeletal and extraskeletal actions of denosumab

Osteoclasts and osteoblasts define skeletal mass, structure and strength through their respective actions in resorbing and forming bone. This remodeling process is orchestrated by the actions of hormones and growth factors, which regulate a cytokine system comprising the receptor activator of nuclear factor κB ligand (RANKL), its receptor RANK and the soluble decoy receptor osteoprotegerin (OPG). Bone resorption depends on RANKL, which determines osteoclast formation, activity and survival. Importantly, cells of the osteoblastic lineage mainly provide RANKL and therefore, are central in the regulation of osteoclast functions. Catabolic effects of RANKL are inhibited by OPG, a TNF receptor family member that binds RANKL, thereby preventing the activation of its receptor RANK, which is expressed by osteoclast precursors. Because this cytokine network is pivotal for the regulation of bone mass in health and diseases, including osteoporosis, rheumatoid arthritis and malignant bone conditions, it has been successfully used for the generation of a targeted therapy to block osteoclast actions. The clinical approval of denosumab, a fully monoclonal antibody against RANKL, provides a novel option to treat bone diseases with a potent, targeted and reversible inhibitor of bone resorption. Although RANKL is also expressed by endothelial cells, T lymphocytes, synovial fibroblasts and various tumor cells, no meaningful clinical extraskeletal effects have been reported after administration of denosumab. This article summarizes the molecular and cellular basis of the RANKL/RANK/OPG system and presents preclinical and clinical studies on the skeletal actions of denosumab.     

Circulating osteoprotegerin and receptor activator for nuclear factor kappaB ligand: clinical utility in metabolic bone disease assessment

CONTEXT: The discovery of the receptor activator for nuclear factor kappaB (RANK) ligand (RANKL)/RANK signaling pathway has marked a major advance in our understanding of the mechanisms controlling osteoclastogenesis. RANKL, expressed by preosteoblasts and stromal cells, binds to RANK, expressed by cells of the osteoclast lineage, inducing a signaling cascade leading to the differentiation and fusion of osteoclast precursor cells and stimulating the activity of the mature osteoclast. The effects of RANKL are counteracted by osteoprotegerin (OPG), a soluble neutralizing decoy receptor. EVIDENCE: This paper reviews the literature surrounding the use of circulating OPG and soluble RANKL (sRANKL) measurements and assesses their potential as markers of bone disease. Original clinical and basic research articles and reviews were identified using a Pubmed search strategy (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) and cover the time period up until January 2005. Search terms osteoprotegerin, OPG, RANK, RANKL, and RANK ligand were used alone and in combination with bone, osteoporosis, and disease. EVIDENCE SYNTHESIS: Assays for detecting OPG and sRANKL in the circulation in humans have been developed, and differences in the circulating concentrations of OPG and sRANKL have been observed in different disease states. There are, however, some inconsistencies in study outcome. These may relate to differences in study design, methodology, and other unknown factors influencing the variability of these measurements. CONCLUSIONS: The clinical utility of serum OPG and sRANKL measurements as markers of disease activity requires additional investigation. In particular, rigorous testing of assays and identification of the sources of measurement variability are required.     

Osteoblasts and bone formation

Bone is constantly being remodelled in a dynamic process where osteoblasts are responsible for bone formation and osteoclasts for its resorption. Osteoblasts are specialized mesenchymal cells that undergo a process of maturation where genes like core-binding factor alpha1 (Cbfa1) and osterix (Osx) play a very important role. Moreover, it was found recently that Wnt/ beta-catenin pathway plays a part on osteoblast differentiation and proliferation. In fact, mutations on some of the proteins involved in this pathway, like the low-density lipoprotein receptor related protein 5/6 (LRP5/6) lead to bone diseases. Osteoblast have also a role in regulation of bone resorption through receptor activator of nuclear factor-kappaB (RANK) ligand (RANKL), that links to its receptor, RANK, on the surface of pre-osteoblast cells, inducing their differentiation and fusion. On the other hand, osteoblasts secrete a soluble decoy receptor (osteoprotegerin, OPG) that blocks RANK/RANKL interaction by binding to RANKL and, thus, prevents osteoclast differentiation and activation. Therefore, the balance between RANKL and OPG determines the formation and activity of osteoclasts. Another factor that influences bone mass is leptin, a hormone produced by adipocytes that have a dual effect. It can act through the central nervous system and diminish osteoblasts activity, or can have an osteogenic effect by binding directly to its receptors on the surface of osteoblast cells.     

RANKL and RANK as novel therapeutic targets for arthritis

The TNF-family molecule receptor activator of nuclear factor kappa B (NFkappaB) ligand (RANKL) (OPGL, TRANCE, ODF) and its receptor activator of NFkappaB (RANK) are key regulators of bone remodeling and regulate T cell/dendritic cell communications, and lymph node formation. Moreover, RANKL and RANK are expressed in mammary gland epithelial cells and control the development of a lactating mammary gland during pregnancy. Genetically, RANKL and RANK are essential for the development and activation of osteoclasts and bone loss in response to virtually all triggers tested. Inhibition of RANKL function via the natural decoy receptor osteoprotegerin (OPG, TNFRSF11B) prevents bone loss in postmenopausal osteoporosis and cancer metastases. Importantly, RANKL appears to be the pathogenetic principle that causes bone and cartilage destruction in arthritis, and OPG treatment prevents bone loss at inflamed joints and has partially beneficial effects on cartilage destruction in all arthritis models studied so far. Modulation of these systems provides a unique opportunity to design novel therapeutics to inhibit bone loss and crippling in arthritis.     

Pathophysiological significance and clinical utility of circulating osteoprotegerin

Osteoprotegerin (OPG) belongs to the tumor necrosis factor receptor superfamily and acts as a decoy receptor for the receptor activator of NF-kappaB ligand (RANKL), preventing its binding to RANK. Since 1997, the RANKL/RANK/OPG system has been intensively investigated in the fields of bone, immune and cardiovascular system pathophysiology. Specific anti-OPG antibodies have been developed, allowing for the measurement of OPG and, more recently, of soluble RANKL in both physiological and pathological conditions, often yielding unexpected results. When considering circulating OPG measurements, it should be borne in mind that this receptor is ubiquitously expressed, and that circulating levels do reflect the production by a number of tissues. Moreover, strikingly different values of circulating OPG have been reported. The aim of this paper is to summarize the available data on circulating OPG levels in a number of conditions; the pathophysiological significance and potential clinical utility will be emphasized.     

Osteoprotegerin inhibits the development of osteolytic bone disease in multiple myeloma.

Multiple myeloma is a B-cell malignancy characterized by the accumulation of plasma cells in the bone marrow and the development of osteolytic bone disease. The present study demonstrates that myeloma cells express the critical osteoclastogenic factor RANKL (the ligand for receptor activator of NF-kappa B). Injection of 5T2MM myeloma cells into C57BL/KaLwRij mice resulted in the development of bone disease characterized by a significant decrease in cancellous bone volume in the tibial and femoral metaphyses, an increase in osteoclast formation, and radiologic evidence of osteolytic bone lesions. Dual-energy x-ray absorptiometry demonstrated a decrease in bone mineral density (BMD) at each of these sites. Treatment of mice with established myeloma with recombinant osteoprotegerin (OPG) protein, the soluble decoy receptor for RANKL, prevented the development of lytic bone lesions. OPG treatment was associated with preservation of cancellous bone volume and inhibition of osteoclast formation. OPG also promoted an increase in femoral, tibial, and vertebral BMD. These data suggest that the RANKL/RANK/OPG system may play a critical role in the development of osteolytic bone disease in multiple myeloma and that targeting this system may have therapeutic potential.     

Receptor activator of nuclear factor kappaB ligand and osteoprotegerin regulation of bone remodeling in health and disease

Osteoclasts and osteoblasts dictate skeletal mass, structure, and strength via their respective roles in resorbing and forming bone. Bone remodeling is a spatially coordinated lifelong process whereby old bone is removed by osteoclasts and replaced by bone-forming osteoblasts. The refilling of resorption cavities is incomplete in many pathological states, which leads to a net loss of bone mass with each remodeling cycle. Postmenopausal osteoporosis and other conditions are associated with an increased rate of bone remodeling, which leads to accelerated bone loss and increased risk of fracture. Bone resorption is dependent on a cytokine known as RANKL (receptor activator of nuclear factor kappaB ligand), a TNF family member that is essential for osteoclast formation, activity, and survival in normal and pathological states of bone remodeling. The catabolic effects of RANKL are prevented by osteoprotegerin (OPG), a TNF receptor family member that binds RANKL and thereby prevents activation of its single cognate receptor called RANK. Osteoclast activity is likely to depend, at least in part, on the relative balance of RANKL and OPG. Studies in numerous animal models of bone disease show that RANKL inhibition leads to marked suppression of bone resorption and increases in cortical and cancellous bone volume, density, and strength. RANKL inhibitors also prevent focal bone loss that occurs in animal models of rheumatoid arthritis and bone metastasis. Clinical trials are exploring the effects of denosumab, a fully human anti-RANKL antibody, on bone loss in patients with osteoporosis, bone metastasis, myeloma, and rheumatoid arthritis.     

Soluble Receptor Activator of Nuclear Factor-κB Ligand (sRANKL)/Osteoprotegerin Balance in Ageing and Age-Associated Diseases

Recently, novel members of the TNF/TNF receptor superfamily, receptor activator of nuclear factor- kappa B ligand (RANKL), its receptor RANK, and the decoy receptor osteoprotegerin (OPG), have been identified as paracrine mediators of both the immune system and bone functions. The balance of RANK/RANK-L and OPG is critical for osteoclastogenesis modulation and physiological bone remodeling. In order to evaluate whether RANKL/OPG balance is modified by ageing, we analyzed, by imunoassay, systemic levels of OPG and sRANKL in healthy elderly subjects (age range from 70 to over 90 years) and in patients affected by two age-related diseases, osteoarthritis (OA) and polymyalgia rheumatica (PMR), characterized by bone metabolism alteration and involvement of the immune system. We demonstrated that (a) plasma concentrations of OPG increased significantly with age; (b) conversely, sRANKL significantly declined in the group of subjects aged between 81 and 90 years, being similar to the young controls in the other age groups; (c) in OA and PMR, circulating OPG did not differ from plasma levels found in age-matched control groups, while sRANKL concentration was significantly increased compared to controls. Hence, in ageing, the sRANKL/OPG system appears to be modified, with prominent changes in circulating OPG levels; in OA and PMR, the sRANKL/OPG balance alteration was shown to be mainly due to the increase of plasma sRANKL concentration.     

Entzündung und Knochenmetabolismus

A finely balanced relationship between bone resorption and bone formation is characteristic for a healthy bone metabolism. Osteoblasts are responsible for bone formation and osteoclasts for bone resorption. In general inflammatory and in particular chronic inflammatory processes influence osteoblast and osteoclast function directly or via indirect mechanisms. Bone metabolism can be influenced by the interaction of cytokines, hormones and growth factors with bone cells. A central factor involved in bone metabolism is the receptor activator of nuclear factor-κB (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system, which is influenced by different inflammatory processes. Usually, (chronic) inflammation results in increased bone loss. The molecular mechanisms and pathophysiological pathways of bone metabolism under the influence of inflammation are summarized in this review.     

金雀异黄素对类风湿关节炎患者成纤维样滑膜细胞骨保护素／细胞核因子κB受体活化因子／细胞核因子κB受体活化因子配体通路的影响

目的研究金雀异黄素（genistein,Gen）对人类风湿关节炎（rheumatoid arthritis,RA）成纤维样滑膜细胞（fibroblast—like synoviocytes,FLS）骨保护素（osteoprotegerin,OPG）／细胞核因子KB受体活化因子（receptor—activator of nuclear factor kappa bata,RANK）／细胞核因子KB受体活化因子配体（receptor—activator of nuclear factor kappa bata ligand,RANKL）通路的影响及机制。方法培养人RA—FLS,并分为对照组（RA—FLS细胞）、TNF—α组（RA—FLS细胞＋TNF-α 10ng／ml）、TNF—α＋Gen组（RA—FLS细胞＋TNF—α 10ng／ml＋Gen 50μM）、Gen组（RA—FLS细胞＋Gen 50μM）。应用免疫印迹检测Gen作用RA—FLS的RANK、RANKL、OPG、雌激素受体（estrogen receptora,ERa）表达情况,免疫荧光检测ERα细胞内分布情况。结果Gen组、TNF-α组及TNF—α＋Gen组细胞内RANK蛋白表达量较对照组无明显差异（P〉0．05）,但OPG及RANKL蛋白表达明显高于对照组（均P〈0．05）。Gen组OPG／RANKL较对照组增高（P〈0．05）。Gen组、TNF-α组及TNF-α＋Gen组细胞内ERa蛋白表达量与对照组比较,差异无统计学意义（P〉0．05）。免疫荧光结果显示核内ERα表达量增加。结论Gen可能通过与雌激素受体结合,转入核内发挥免疫调节作用,从而调节0PG／RANKI／RANK通路,发挥抑制骨破坏的作用。Gen可以上调人RA—FLS中OPG及RANKL,且对OPG的上调作用更强。     

Breast cancer cells interact with osteoblasts to support osteoclast formation.

Breast cancers commonly cause osteolytic metastases in bone, a process that is dependent upon osteoclast-mediated bone resorption. Recently the osteoclast differentiation factor (ODF), better termed RANKL (receptor activator of NF-kappaB ligand), expressed by osteoblasts has been cloned as well as its cognate signaling receptor, receptor activator of NFkappaB (RANK), and a secreted decoy receptor osteoprotegerin (OPG) that limits RANKL's biological action. We determined that the breast cancer cell lines MDA-MB-231, MCF-7, and T47D as well as primary breast cancers do not express RANKL but express OPG and RANK. MCF-7, MDA-MB-231, and T47D cells did not act as surrogate osteoblasts to support osteoclast formation in coculture experiments, a result consistent with the fact that they do not express RANKL. When MCF-7 cells overexpressing PTH-related protein (PTHrP) were added to cocultures of murine osteoblasts and hematopoietic cells, osteoclast formation resulted without the addition of any osteotropic agents; cocultures with MCF-7 or MCF-7 cells transfected with pcDNAIneo required exogenous agents for osteoclast formation. When MCF-7 cells overexpressing PTHrP were cultured with murine osteoblasts, osteoblastic RANKL messenger RNA (mRNA) levels were enhanced and osteoblastic OPG mRNA levels diminished; MCF-7 parental cells had no effect on RANKL or OPG mRNA levels when cultured with osteoblastic cells. Using a murine model of breast cancer metastasis to bone, we established that MCF-7 cells that overexpress PTHrP caused significantly more bone metastases, which were associated with increased osteoclast formation, elevated plasma PTHrP concentrations and hypercalcaemia compared with parental or empty vector controls.     

Modulation of osteoclast differentiation and function by the new members of the tumor necrosis factor receptor and ligand families.

Osteoblasts/stromal cells are essentially involved in osteoclast differentiation and function through cell-to-cell contact (Fig. 8). Although many attempts have been made to elucidate the mechanism of the so-called "microenvironment provided by osteoblasts/stromal cells," (5-8) it has remained an open question until OPG and its binding molecule were cloned. The serial discovery of the new members of the TNF receptor-ligand family members has confirmed the idea that osteoclast differentiation and function are regulated by osteoblasts/stromal cells. RANKL, which has also been called ODF, TRANCE, or OPGL, is a member of the TNF ligand family. Expression of RANKL mRNA in osteoblasts/stromal cells is up-regulated by osteotropic factors such as 1 alpha, 25(OH)2D3, PTH, and IL-11. Osteoclast precursors express RANK, a TNF receptor family member, recognize RANKL through cell-to-cell interaction with osteoblasts/stromal cells, and differentiate into pOCs in the presence of M-CSF. RANKL is also involved in the survival and fusion of pOCs and activation of mature osteoclasts. OPG, which has also been called OCIF or TR1, is a soluble receptor for RANKL and acts as a decoy receptor in the RANK-RANKL signaling system (Fig. 8). In conclusion, osteoblasts/stromal cells are involved in all of the processes of osteoclast development, such as differentiation, survival, fusion, and activation of osteoclasts (Fig. 8). Osteoblasts/stromal cells can now be replaced with RANKL and M-CSF in dealing with the whole life of osteoclasts. RANKL, RANK, and OPG are three key molecules that regulate osteoclast recruitment and function. Further studies on these key molecules will elucidate the molecular mechanism of the regulation of osteoclastic bone resorption. This line of studies will establish new ways to treat several metabolic bone diseases caused by abnormal osteoclast recruitment and functions such as osteopetrosis, osteoporosis, metastatic bone disease, Paget's disease, rheumatoid arthritis, and periodontal bone disease.     

丹蓝仙硼疗氟胶囊对氟中毒大鼠骨保护素/核因子κβ受体活化因子配体/核因子κβ受体活化因子系统表达水平的影响

目的 观察慢性氟中毒大鼠骨组织中骨保护素(OPG)、核因子κβ受体活化因子配体(RANKL)、核因子κβ受体活化因子(RANK)蛋白表达水平,探讨OPG/RAN KL/RANK系统与慢性氟中毒大鼠骨骼损伤的关系及丹蓝仙硼疗氟胶囊的拮抗作用.方法 将SD大鼠按体质量随机分为6组(组内雌雄各半):氟中毒组、高剂量药物组、中剂量药物组、低剂量药物组、对照组、硼砂(阳性药物对照)组,每组12只.对照组饮用自来水,其余5个实验组饮用含氟水(50 mg/L),而高、中、低剂量药物组另摄入丹蓝仙硼疗氟胶囊,剂量分别为0.8、O.4、O.2 g/kg,硼砂组另摄入硼砂,剂量为0.8 g/kg.6个月时用免疫组织化学方法检测OPG、RANKL、RANK蛋白在大鼠股骨干骺端的表达.结果 与对照组(173.79±5.23、174.17±5.O1、155.63±7.11)比较,氟中毒组大鼠股骨干骺端OPG、RANKL(156.83±5.80、157.74±6.70)表达增高,RANK(173.92±4.37)表达降低,差异有统计学意义(P均＜0.05).与氟中毒组比较,高、中剂量药物组OPG、RANKL(169.67±5.07、168.08±5.05,170.78±5.01、168.41±7.19)表达降低,RANK(162.12±4.24、166.69±5.78)表达增高,差异有统计学意义(P均＜O.05).与硼砂组(167.27±4.08、167.85±5.O1、166.14±3.95)比较,低剂量药物组OPG、RANKL(163.40±4.11、159.49±5.78)表达增高,RANK(171.54±8.06)表达降低,而高剂量药物组RANK(162.12±4.24)表达增高,差异有统计学意义(P均＜0.05).结论 慢性氟中毒可引起成骨与破骨活动均增强的骨转换增高状态,并可通过改变OPG/RANKL/RANK系统表达影响骨吸收的程度.丹蓝仙硼疗氟胶囊能通过OPG/RANKL/RANK系统影响骨重建,对氟致骨损伤有拮抗作用.     

Osteoprotegerin as a potential therapy for osteoporosis

The discovery and characterization of the RANKL/RANK/ OPG signaling pathway and the identification of its role in the pathogenesis of bone loss have provided the rationale for the development of drugs with the ability to modulate RANK-induced osteoclastogenesis. In vivo studies have identified interfering with the RANKL/RANK interaction as a potential therapeutic target in the management of osteoporosis. Two agents capable of blocking the binding of RANKL to RANK have been so far tested in clinical studies—osteoprotegerin (Fc-OPG fusion molecule) and the RANKL-antibody (AMG 162). Both have been found to have profound inhibitory effects on bone resorption, with AMG 162 appearing to be overall superior to OPG. Data are still very scarce, however, and much remains to be uncovered before novel strategies capable of modulating the RANKL/OPG signaling pathway could be safely and effectively used in the management of osteoporosis.