OPG/RANKL/RANK信号通路在非酒精性脂肪性肝病进展中的作用

非酒精性脂肪性肝病(NAFLD)已成为全球范围内最常见的肝脏疾病,在现有基础上更好诊断、治疗NAFLD也愈发迫切。骨保护素(OPG)/NF-κB受体活化因子(RANKL)/NF-κB受体活化因子受体(RANK)信号通路是参与骨代谢平衡的重要信号通路。分别介绍了OPG、RANKL、RANK及OPG/RANKL/RANK系统,简述了OPG/RANKL/RANK信号通路通过激活NF-κB调节炎症因子生成,促使NAFLD发展的研究现状。指出OPG/RANKL/RANK系统可作为NAFLD治疗的潜在新靶点。     

OPG/RANKL/RANK系统在风湿性疾病中的研究进展

OPG/RANKL/RANK系统是近年来发现的在破骨细胞(osteoclast,OC)分化过程中的一个重要信号传导通路,包括:RANKL(ligand of receptor-activator of NF-KB),或称为破骨细胞分化因子(osteoclast differentiatioc factor, ODF);其受体是位于破骨细胞细胞膜上的RANK(receptor activator of NF-KB);骨保护素(osteoprotegerin,OPG)是RANKL的假性受体.     

川芎嗪对类风湿关节炎模型大鼠关节滑液RANK/RANKL/OPG表达的影响

目的 探讨川芎嗪对类风湿关节炎(RA)大鼠关节滑液核因子κB活化受体(RANK)、RANK配体(RANKL)和骨保护素(OPG)表达的影响,以及在RA骨破坏和炎症过程中的作用机制.方法 建立大鼠佐剂性关节炎模型,并分为5组,模型对照组、阳性对照组、川芎嗪高、低剂量组和正常对照组,造模15 d后,连续给药7 d,应用间接免疫荧光标记、流式细胞术检测关节滑液中RANK/RANKL/OPG表达水平和平均荧光强度.结果 与正常对照组相比,模型组CD3+T细胞OPG表达明显降低,RANK,RANKL升高,差异有显著性(P＜0.05),中性粒细胞和单核细胞上变化不明显;经过川芎嗪高剂量治疗后,CD3+T细胞上OPG表达增强,RANK、RANKL减弱,平均荧光强度降低,差异有显著性(P＜0.05),中性粒细胞和单核细胞治疗前后RANK、RANKL、OPG表达变化不明显;低剂量组各指标变化无统计学意义.结论 高剂量川芎嗪主要通过调节关节滑液中CD3+T细胞上RANK/RANKL/OPG表达起到缓解RA骨损伤和关节炎症的作用.     

骨保护素与骨质疏松

肿瘤坏死因子家族新成员骨保护素(OPG)通过与细胞核因子κB受体活化因子(RANK)配体(RANKL)结合,抑制RANKL/RANK对破骨细胞信号转导的活化,发挥抗骨质疏松作用。OPG基因多态性与骨质疏松也存在相关性。OPG受多种激素、细胞因子和转录因子的调控,骨OPG/RANKL比率的改变在各型骨质疏松的发病中起重要作用。目前OPG已成为新的骨转换指标,但其在血清中的浓度变化和临床意义尚存在争论。由于在动物实验中利用OPG基因和蛋白治疗骨质疏松已取得一定进展,故OPG有望成为新一代的抗骨质疏松药物。     

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.     

RANK RANKL和骨保护素在类风湿关节炎患者外周血和滑液中表达的研究

目的研究骨保护素(OPG)和核因子κB受体活化因子(RANK)及其配体(RANKL)在类风湿关节炎(RA)患者外周血和滑液中的表达,探讨RANKL、RANK和OPG在RA骨破坏中的意义。方法收集活动期RA患者治疗前后外周血、滑液和健康对照,以间接免疫荧光标记,流式细胞术检测RANK、RANKL和OPG在外周血和滑液中CD3+T淋巴细胞、中性粒细胞和CD14+单核细胞的表达率及平均荧光强度。结果①RA组治疗前后外周血RANK、RANKL和OPG在CD3+T淋巴细胞、中性粒细胞和CD14+单核细胞上的表达率差异无统计学意义(P>0.01);RANK的表达强度治疗后高于治疗前(P<0.01)。②RA组外周血CD3+T淋巴细胞上RANKL及RANK的表达率和表达强度明显低于滑液,OPG的表达则高于滑液(P<0.01),RANKL/OPG比率明显增高(P<0.01)。结论RANK表达强度的改变提示其可能与RA炎症的发展和转归有关,而活化的CD3+T淋巴细胞可能通过上调RANK、RANKL的表达,下调OPG表达参与RA破骨细胞的分化和骨损伤的调节机制。     

强直性脊柱炎继发骨质疏松及相关因素分析

目的 测定强直性脊柱炎(AS)患者骨密度(BMD)、血清骨保护素(OPG)、可溶性核因子κB受体活化因子配体(sRANKL)等骨代谢指标及外周血T细胞表面RANKL表达情况,研究RANKI/RANK/OPG系统在AS骨代谢中的作用.方法 双能X线吸收法(DEXA)测定AS患者BMD;酶联免疫吸附试验(ELISA)法检测血清OPG、sRANKL、抗酒石酸酸性磷酸酶异构体5b(TRACP-5b)、骨特异性碱性磷酸酶(BALP)水平;分析BMD、上述骨代谢指标及临床指标间相关性;流式细胞术(FC)检测外周血CD4+/RANKL+及CD8+/RANKL+细胞表达率;分析它们与红细胞沉降率(ESR)、C反应蛋白(CRP)相关性.计量资料采用成组设计的t检验,计数资料采用x2检验,相关性采用直线相关分析.结果 ①AS患者骨量减少、骨质疏松(OP)发生率分别为47%、37%.②AS组血清sRANKL、TRACP-5b水平及sRANKL/OPG比值均高于对照组(P<0.05);2组血清OPG、BALP水平差异无统计学意义.③AS组血清sRANKL水平与OPG呈正相关,两者均与TRACP-5b呈正相关(P<0.01.④AS组外周血CD4+/RANKL+细胞表达率高于对照组(P<0.05).结论 AS存在较高的骨量丢失率,其骨代谢特点以骨吸收增强为主,RANKL/RANK/OPG系统在其中起着重要作用,该系统失衡可能是AS骨量丢失机制之一;CD4+T细胞可能通过上调RANKL表达参与AS破骨细胞分化成熟及骨吸收机制.     

骨保护素与骨质疏松

肿瘤坏死因子家族新成员骨保护素(OPG)通过与细胞核因子kB受体活化因子(RANK)配体(RANKL)结合，抑制RANKL／RANK对破骨细胞信号转导的活化，发挥抗骨质疏松作用。OPG基因多态性与骨质疏松也存在相关性。OPG受多种激素、细胞因子和转录因子的调控，骨OPG／RANKL比率的改变在各型骨质疏松的发病中起重要作用。目前OPG已成为新的骨转换指标，但其在血清中的浓度变化和临床意义尚存在争论。由于在动物实验中利用OPG基因和蛋白治疗骨质疏松已取得一定进展，故OPG有望成为新一代的抗骨质疏松药物。     

氟中毒大鼠骨组织中OPG、RANKL和RANK的表达及丹蓝仙硼疗氟胶囊的拮抗作用

目的观察骨保护素（OPG）、骨保护素配体（RANKL）、细胞核因子κB受体活化因子（RANK）在饮水型氟中毒大鼠骨组织中mRNA表达水平,探讨丹蓝仙硼疗氟胶囊对饮水型氟中毒大＂鼠OPG/RANKL/RANK系统表达的影响。方法以SD大鼠为研究对象,按体重均衡随机分为6组（组内雌雄各半）：对照组、氟中毒组、高剂量药物组、中剂量药物组、低剂量药物组、硼砂治疗组。在饮用水中加入氟化钠使水中氟含量为50 mg/L,复制氟中毒动物模型。提取骨组织总RNA,通过逆转录-聚合酶链式反应（RT-PCR）方法,观察骨组织中OPG、RANKL和RANK mRNA表达的变化。结果氟中毒时,骨组织中的OPG、RANKLmRNA的表达呈上升趋势,RANKmRNA表达呈下降趋势。用药后,骨组织中的OPG、RANKLmRNA的表达呈下降趋势,RANKmRNA表达呈上升趋势。结论过量氟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系统表达提高骨吸收的活性。丹蓝仙硼疗氟胶囊能拮抗过量氟对大鼠骨组织的作用,通过0PG/RANKL/RANK系统影响骨重建。     

慢阻肺合并骨质疏松患者血清IL-31、IL-33水平与OPG/RANK/RANKL系统相关性研究

目的 探讨血清白细胞介素31(IL-31)、白细胞介素33(IL-33)在慢性阻塞性肺疾病(COPD)合并骨质疏松患者中的表达情况及与骨保护素(OPG)/核因子κB受体活化因子(RANK)/RANK配体(RANKL)系统的关联性。方法 收集2019年6月～2023年1月于惠州市第一人民医院就诊的男性稳定期COPD患者90例为COPD组,并纳入同期健康体检者45例为对照组。COPD组患者根据骨密度检测结果,分为非骨质疏松组(n=49)和骨质疏松组(n=41)。测定病例组、对照组入组当天血清IL-31、IL-33、OPG及RANKL水平。结果 (1)相比正常对照组,COPD组患者血清IL-31、RANKL水平及RANKL/OPG比值明显升高,而血清IL-33水平明显下降(均P<0.05);(2)与COPD非骨质疏松组患者相比,骨质疏松组血清IL-31、RANKL水平及RANKL/OPG比值显著升高,而血清IL-33水平、体重指数(BMI)、骨密度及FEV₁(%)、FEV₁/FVC(%)明显降低(均P<0.05);(3) COPD患者骨...     

Rank/Rankl/opg: literature review

The discovery of the receptor activator of nuclear factor-kB (RANK)/RANK Ligand (RANKL)/osteoprotegerin (OPG) pathway contributed to the understanding of how bone formation and resorption were processed and regulated. RANKL and OPG are members of the tumor necrosis factor (TNF) and TNF receptor (TNFr) superfamilies, respectively, and binding to receptor activator of NF-kB (RANK) not only regulate osteoclast formation, activation and survival in normal bone modeling and remode-ling, but also in several other pathologic conditions characterized by increased bone turnover. There is accumulating evidence of the potential role of OPG and RANKL in other tissues. Looking beyond the RANK/RANKL/OPG axis, Wingless (Wnt) pathway emerged as the osteoblast differentiation way, and also as a bone mass regulator. Researchers have been discovering new molecules and cytokines interactions. Altogether, data suggest that RANK/RANKL/OPG system could be targeted as a new treatment strategy in bone conditions. FREEDOM is the more recently published clinical trial about a RANKL-specific recombinant fully human monoclonal antibody (denosumab). OPG is also a potential innovative therapeutic option to be investigated.     

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.     

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.     

Circulating RANKL/OPG in polymyalgia rheumatica

OBJECTIVE: To evaluate whether RANKL/OPG balance is modified in PMR patients, either in the active phase of the disease or during corticosteroid treatment. METHODS: Circulating levels of RANKL and OPG were assayed by enzyme-linked immunosorbent assay in PMR patients with active untreated disease and in patients treated by corticosteroids over a 12-month follow-up period. RESULTS: We found no statistically significant differences in circulating levels of OPG between PMR patients either in the active phase of the disease or during all follow-up period compared to normal controls. On the other hand, systemic production of sRANKL is increased and is not modulated by corticosteroid treatment. CONCLUSION: In PMR increased levels of sRANKL may be related to bone osteoporosis. Further investigations are necessary to evaluate the relationship between the RANK/RANKL/OPG system and bone turnover in PMR patients.     

Differential profile of the OPG/RANKL/RANK-system in degenerative aortic native and bioprosthetic valves

BACKGROUND AND AIM OF THE STUDY: Although degenerative calcific aortic valve stenosis is the most common valvular disease among the elderly, neither the etiology underlying the condition nor degeneration of the bioprostheses is yet fully understood. The study aim was to assess the expression profile of those OPG/RANKL/RANK-system determinants known to act as key regulators of bone metabolism and the immune system in calcific aortic valve stenosis and porcine aortic bioprostheses. METHODS: Valve probes from a total of 69 patients (41 with end-stage aortic stenosis, 11 with mild-to-moderate aortic sclerosis, 17 with degenerative porcine aortic bioprostheses) were explanted either during surgery or at autopsy. The presence and localization of OPG, RANKL, RANK and NF-kappaB were analyzed by immunostaining and morphometry. RESULTS: The majority of stenotic and sclerotic valves exhibited cell-bound signals of OPG, RANKL, RANK and NF-kappaB, while bioprostheses showed only sparse signaling. As key findings, the percentage of cells labeled by OPG, RANK and NF-kappaB was increased in sclerotic valves compared with stenotic valves (each p < 0.001), whereas the frequency of RANKL was higher in stenotic compared to sclerotic valves (p < 0.001). As a consequence, the OPG/RANKL ratio was decreased in stenotic (0.83) compared to sclerotic valves (20.2). CONCLUSION: The differential expression profile of specific members of the OPG/RANKL/RANK axis suggests an involvement of their determinants in native valve calcification, but not in the degeneration of porcine bioprostheses. Thus, these mediators of bone homeostasis may represent new targets for a more specified prevention and/or therapy of native aortic stenosis.     

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).     

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.     

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.