基于OPG/RANK/RANKL信号轴探讨中医“瘀证”与骨质疏松症之间的关系

近年来,随着中医学的不断发展,中医药在治疗骨质疏松症(osteoporosis,OP)中的应用愈加广泛,然而由于只有单纯的中医理论指导,而缺乏现代科学依据的支撑,故而广受争议。与此同时,OPG/RANK/RANKL信号轴的发现又是现代分子生物学的一大突破。因此,笔者立足于中西医结合的角度,基于中医脏腑亏虚立论,从OPG/RANK/RANKL信号调控机制探讨中医学从"瘀证"论治骨质疏松症的合理性,从而为中医从"瘀"辨治OP以及临床研究提供科学理论依据。     

OPG/RANKL/RANK信号通路在运动与骨免疫学中的研究进展

自Arron在Nature上首次提出“骨免疫学”的概念以来,关于免疫系统与骨骼系统的研究逐渐成为国内外学者研究的热点。在骨免疫学研究中,OPG/RANKL/RANK信号通路作为免疫系统参与骨代谢调节的主要通路一直备受关注。当机体运动时,运动所产生的机械应力以及运动诱导的免疫功能变化均能通过OPG/RANKL/RANK信号通路影响骨代谢。适宜的运动能上调OPG基因表达,抑制RANKL分泌及其基因表达,促进IL -2、IL-18、IFN等保护性免疫细胞因子的分泌,有助于骨形成, 使骨代谢趋向正平衡。而长时间大强度运动以及过度训练则上调RANKL基因表达,下调OPG基因表达,促使破骨细胞活性增强,同时又诱导IL-6、TNF、IL-17等炎症性细胞因子分泌增多,间接促进骨吸收,使骨代谢趋向负平衡。为了更深人地了解运动、免疫以及骨代谢之间的关系,本文综述了国内外关于运动、免疫与骨代谢的报道,旨在探讨运动对骨代谢及OPG/ RANKL/RANK信号通路的调节机制以及运动应激下免疫细胞因子对OPG/RANKL/RANK信号通路的影响,为运动与骨免疫 学的研究及骨代谢疾病的预防提供理论基础。     

骨质疏松相关信号通路研究进展

骨代谢过程包括骨形成及骨吸收,当两者间的平衡被打破后便会出现骨硬化或者骨量减少甚至骨质疏松,其具体的分子调节通路不明。现代研究表明,在骨代谢过程中至少存在RANKL/RANK/OPG信号通路、Wnt/β-catenin信号通路、PTH信号通路、PPAR-γ信号通路等,各个通路间还存在交叉。通过分子信号通路,可有效促进骨代谢研究,并开发具有治疗骨质疏松的新药。     

从脾肾论治骨质疏松症的OPG/RANK/RANKL信号调控机制

中医处方遣药传承"辨证论治"之道,强调机体的整体性和时空性,但往往缺乏客观的分子生物学依据解释其作用机理;OPG/RANK/RANKL系统是骨代谢史上里程碑式的发现,对骨质疏松的中医药防治及研究开创新的纪元,从脾肾论治的效应最终可通过该系统对骨代谢调控的微观信息来表达,可以说OPG/RANKL/RANK系统是广大学者热衷于探究中药机理的切入点和共通点。基于此,本文就骨质疏松症的病因病机及治则方药结合OPG/RANK/RANKL系统对骨代谢的调控机制做一综述,旨在为原发性骨质疏松症的中医药防治提供客观的分子生物学依据。     

OPG/RANKL/RANK系统与软骨及软骨下骨

OPG/RANKL/RANK系统在调节骨代谢和骨重塑方面具有重要作用。成骨细胞表达的核因子-κB受体活化因子配体(RANKL)与破骨细胞表面的核因子-κB受体活化因子(RANK)结合促进破骨细胞分化成熟,骨保护素(OPG)则结合RANKL而抑制这一功能。研究表明,OPG/RANKL/RANK系统在软骨及软骨下骨内也有表达,可能成为类风湿关节炎及骨关节炎的治疗靶点。该文就OPG/RANKL/RANK系统在软骨及软骨下骨内表达及其作用研究进展作一综述。     

基于“肝主筋、肾主骨”理论探讨OPG/RANKL/RANK信号轴与绝经后骨质疏松症症的筋骨相关性

中医基础理论素有“肝主筋，肾主骨”之说，肝藏血主筋，筋束骨利关节，肾为先天之本，主骨而生髓，肝肾精血同源、筋骨相关，互资互生，二者共同介导机体器官、脏腑的发育、生长与衰退过程，尤其与骨细胞生长代谢机制关系密切。随着中医药分子生物学研究的深入，发现骨保护蛋白（OPG）/核因子-kB受体活化因子（RANK）/核因子-kB受体活化因子配体（RANKL）信号轴在骨代谢中发挥关键作用。本文基于“肝主筋，肾主骨”理论，从绝经后骨质疏松症症的病因病机出发，从“肝肾论治，筋骨并重”角度将OPG/RANKL/RANK信号转导系统与骨代谢内环境稳态相结合，为中医药柔肝补肾、调筋养骨机制提供分子生物学、筋骨力学依据支撑，以期进一步指导临床论治。     

从OPG/RANK/RANKL信号转导系统探讨老年性骨质疏松的发病机制

骨质疏松症属于骨科临床常见的慢性、增龄性疾患,随着全球老龄化的加剧,老年人已成为骨质疏松症的高发人群,后期并发脊柱、四肢及骨盆等重要部位的疏松性骨折是致残、致死的主要原因,严重威胁老年群体的身心健康。在我国,老年性骨质疏松症及其并发症防治方面的医疗投入逐年增长,使得社会经济负担越发繁重。近年来随着研究技术与水平的不断提升,在骨分子生物学领域有了不少突破,发现一些细胞因子和信号通路与骨质疏松症的发生、发展密切相关,其中OPG/RANK/RANKL信号转导系统也在骨代谢中起着关键的调控作用。笔者针对老年性骨质疏松症的发病特点,围绕OPG/RANK/RANKL信号通路在该病发生中的作用机制展开综述,以期拓宽老年性骨质疏松症的防治思路。     

基于“肝主筋、肾主骨”理论探讨OPG/RANKL/RANK信号轴与绝经后骨质疏松症的筋骨相关性

中医基础理论素有"肝主筋,肾主骨"之说,肝藏血主筋,筋束骨利关节,肾为先天之本,主骨而生髓,肝肾精血同源、筋骨相关,互资互生,二者共同介导机体器官、脏腑的发育、生长与衰退过程,尤其与骨细胞生长代谢机制关系密切。随着中医药分子生物学研究的深入,发现骨保护蛋白(OPG)/核因子-k B受体活化因子(RANK)/核因子-k B受体活化因子配体(RANKL)信号轴在骨代谢中发挥关键作用。本文基于"肝主筋,肾主骨"理论,从绝经后骨质疏松症的病因病机出发,从"肝肾论治,筋骨并重"角度将OPG/RANKL/RANK信号转导系统与骨代谢内环境稳态相结合,为中医药柔肝补肾、调筋养骨机制提供分子生物学、筋骨力学依据支撑,以期进一步指导临床论治。     

骨重建过程中降钙素基因相关肽与RANK/RANKL/OPG作用机制的研究进展

目的总结骨重建过程中降钙素基因相关肽(calcitonin gene-related peptide,CGRP)与核因子κB受体活化因子(receptor activator of nuclear factorκB,RANK)/核因子κB受体活化因子配体(receptor activator of nuclear factorκB ligand,RANKL)/骨保护蛋白(osteoprotegerin,OPG)信号系统作用机制的研究进展,为进一步研究骨相关疾病的预防及治疗提供理论依据。方法广泛查阅国内外近年来骨重建过程中CGRP与RANK/RANKL/OPG信号系统相关文献,并加以分析总结。结果骨重建过程中,CGRP与RANK/RANKL/OPG信号系统发挥着重要调控作用。结论目前对于骨重建过程中CGRP与RANK/RANKL/OPG信号系统的作用机制研究仍不够深入,需进一步研究二者在骨重建过程中的具体作用方式、相互联系,明确作用机制,为临床上骨相关疾病的治疗带来新思路、新方法。     

基于“脾主肉、肾主骨”理论探讨绝经后骨质疏松症的OPG/RANK/RANKL信号调控机制

中医理论传承"辨证论治"之道,强调人作为机体的整体性与统一性,肾主骨生髓为先天之本,脾主肌肉充四肢为后天之源,先后二天互资互生,共同维持人体正常的生理机能,但缺乏客观的分子生物学依据阐明其作用机理。OPG/RANK/RANKL信号转导系统的发现在骨代谢史上具有里程碑的意义,开创了中医药防治和研究绝经后骨质疏松症的新纪元,骨微观信息的改变就是从脾肾论治对骨代谢调控机制的效应表达。本文基于"脾主肉、肾主骨"理论,就绝经后骨质疏松症的病因病机及治法方药结合OPG/RANK/RANKL信号转导系统在骨代谢中的作用展开综述,旨在为绝经后骨质疏松症的中医药防治从分子生物学水平提供科学依据,以期更好地指导临床。     

橙皮苷对去卵巢骨质疏松症大鼠骨质流失和机制的影响

目的研究橙皮苷对去卵巢骨质疏松大鼠骨质流失和骨保护素(osteoprotegerin,OPG)/核因子kappa B配体的受体激活物(receptor activator of nuclear factor kappa B ligand,RANKL)/RANK通路的影响。方法将48只雌性Sprague-Dawley(SD)大鼠随机分为假手术组、去卵巢骨质疏松组、橙皮苷低剂量组、橙皮苷中剂量、橙皮苷高剂量组和雌激素组。检测骨组织骨体积分数(bone volume fraction,BV/TV)、骨小梁厚度(trabecular thickness,Tb.Th)、骨密度(bone mineral density,BMD)、骨小梁数量(trabecular number,Tb.N)、骨小梁分离度(trabecular separation,Tb.Sp),通过HE染色观察骨组织病理损伤,采用酶联免疫吸附法(enzyme linked immunosorbent assay,ELISA)检测人Ⅰ型胶原C端肽(C-terminal peptide collagen typeⅠ,CTX-Ⅰ)和血清骨钙素(bone glaprotein,BGP)的表达量。运用qRT-PCR和Western bolt分别检测骨组织OPG、RANKL、RANK的mRNA和蛋白表达。结果在橙皮苷治疗后,与去卵巢骨质疏松组相比,骨质疏松标志物BV/TV、BMD、Tb.Th和Tb.N水平升高,Tb.Sp水平降低;大鼠骨小梁数量明显增加,且骨小梁连接更为紧密;骨吸收标志物CTX-Ⅰ水平降低;骨形成标志物BGP水平升高。OPG mRNA相对表达量和蛋白的表达量升高,RANKL和RANK mRNA相对表达量和蛋白的表达量降低。结论橙皮苷能缓解去卵巢骨质疏松大鼠骨质流失并调节OPG/RANKL/RANK信号通路。     

RANKL,a necessary chance for clinical application to osteoporosis and cancer-related bone diseases

Osteoporosis is a common bone disease characterized by reduced bone and increased risk of fracture. In postmenopausal women, osteoporosis results from bone loss attributable to estrogen deficiency. Osteoclast differentiation and activation is mediated by receptor activator of nuclear factor-κB ligand (RANKL), its receptor receptor activator of nuclear factor-κB (RANK), and a decoy receptor for RANKL, osteoprotegerin (OPG). The OPG/RANKL/RANK system plays a pivotal role in osteoclast biology. Currently, a fully human anti-RANKL monoclonal antibody named denosumab is being clinically used for the treatment of osteoporosis and cancer-related bone disorders. This review describes recent advances in RANKL-related research, a story from bench to bedside. First, the discovery of the key factors, OPG/RANKL/RANK, revealed the molecular mechanism of osteoclastogenesis. Second, we established three animal models: (1) a novel and rapid bone loss model by administration of glutathione-S transferase-RANKL fusion protein to mice; (2) a novel mouse model of hypercalcemia with anorexia by overexpression of soluble RANKL using an adenovirus vector; and (3) a novel mouse model of osteopetrosis by administration of a denosumab-like anti-mouse RANKL neutralizing monoclonal antibody. Lastly, anti-human RANKL monoclonal antibody has been successfully applied to the treatment of osteoporosis and cancer-related bone disorders in many countries. This is a real example of applying basic science to clinical practice.     

The RANKL/RANK/OPG pathway

Understanding of osteoclast formation and activation has advanced considerably since the discovery of the RANKL/RANK/OPG system in the mid 1990s. Osteoblasts and stromal stem cells express receptor activator of NF-jB ligand (RANKL), which binds to its receptor, RANK, on the surface of osteoclasts and their precursors. This regulates the differentiation of precursors into multinucleated osteoclasts and osteoclast activation and survival both normally and in most pathologic conditions associated with increased bone resorption. Osteoprotegerin (OPG) is secreted by osteoblasts and osteogenic stromal stem cells and protects the skeleton from excessive bone resorption by binding to RANKL and preventing it from interacting with RANK. The RANKL/OPG ratio in bone marrow is thus an important determinant of bone mass in normal and disease states. RANKL/RANK signaling also regulates lymph node formation and mammary gland lactational hyperplasia in mice, and OPG protects large arteries of mice from medial calcification. This article reviews the roles of the RANKL/RANK/OPG system in bone and other tissues.     

基于OPG/RANKL/RANK轴观察加味阳和汤及其拆方对去卵巢骨质疏松大鼠的影响

目的观察加味阳和汤及其拆方对OPG、RANKL、RANK含量的影响,探讨其防治绝经后骨质疏松症可能的作用机制及组方配伍的合理性。方法选取48只雌性SD大鼠,加味阳和汤按君臣佐使关系拆方,将大鼠等量随机分为假手术组(SHAM)、模型组(OVX)、君药+臣药组(A组)、君药+臣药+佐药组(B组)、君药+臣药+佐药+使药组(C组)、戊酸雌二醇组(E2V)。除SHAM组外,均采用去卵巢骨质疏松大鼠模型,干预给药后(灌胃90 d),处死动物后取右侧股骨及胫骨通过双能X射线骨密度仪检测骨密度(bone mineral density,BMD)及骨矿含量(bone mineral content,BMC),取左侧股骨行HE染色观察骨显微结构,检测血清中骨代谢指标ALP、Ca~(2+)、P~(3-)、E2及血清OPG、RANKL、RANK含量。结果与SHAM组相比,OVX组大鼠股骨及胫骨BMD、BMC降低(P0.05),骨小梁变细、间隙增大、结构缺失,血清Ca~(2+)、P~(3-)、E2、OPG水平下降(P0.05),血清ALP、RANKL、RANK水平上升(P0.05);与OVX组比较,除A组大鼠股骨及胫骨BMD、BMC、血清Ca~(2+)、P~(3-)、E2、OPG、RANKL及B组P~(3-)水平无显著差异外(P0.05),各给药组大鼠股骨及胫骨BMD、BMC均显著升高(P0.05),骨小梁增多、间隙减小、结构趋向完整,血清Ca~(2+)、P~(3-)、E2、OPG水平上升(P0.05),血清ALP、RANKL、RANK水平下降(P0.05)。结论加味阳和汤及其拆方通过提高去卵巢骨质疏松大鼠BMD、BMC,降低骨代谢,改善骨显微结构从而发挥治疗作用,调节OPG/RANKL/RANK轴是可能的机制。     

The Role of RANK/RANKL/OPG Signalling Pathways in Osteoclastogenesis in Odontogenic Keratocysts, Radicular Cysts, and Ameloblastomas

The aim of this study was to evaluate the immunohistochemical expression of molecules involved in osteoclastogenesis, including the receptor activator of nuclear factor kappa B (RANK), RANK ligand (RANKL) and osteoprotegerin (OPG) in odontogenic keratocysts (OKCs), which has been named as a keratocystic odontogenic tumour by the WHO, and compare their expression with radicular cysts and ameloblastomas. RANK is a member of tumour necrosis factor receptor family and it is activated by RANK ligand. OPG binds to RANKL and inactivates it. The imbalance of these factors could cause the differential bone resorption activity in some diseases and tumours. The expression of these molecules was evaluated in ameloblastomas (n = 20), OKCs (n = 20), and radicular cysts (n = 20) by immunohistochemistry. Immunohistochemical reactivity for RANK, RANKL, and OPG was detected in neoplastic and nonneoplastic epithelium and connective tissue cells. RANK showed the greatest expression in OKCs followed by ameloblastomas, with the lowest expression seen in radicular cysts. Expression of RANKL was detected in all lesions and no significant differences were observed between groups. OPG was expressed very low in all groups. In the stroma, the number of RANK positive cells was higher in OKCs when compared with ameloblastomas and radicular cysts but radicular cyst had higher numbers of RANKL positive cells in the stroma than ameloblastomas. The molecular system of RANK/RANKL/OPG is variably expressed in OKCs, radicular cysts, and ameloblastomas and this system may be involved in the osteoclastogenic mechanisms in OKCs and ameloblastomas. Advanced studies could further clarify the role of RANK, RANKL, and OPG in mediating tumour associated bone osteolysis.     

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.