破骨细胞伪足小体的结构和功能

破骨细胞是一种由造血干细胞分化而来的具有骨吸收功能的多核细胞。破骨细胞的骨吸收功能与其肌动蛋白骨架的完整性有关。研究表明,破骨细胞肌动蛋白骨架的基本结构为伪足小体（podosome）。在破骨细胞分化的不同阶段,伪足小体呈现不同的形态结构。伪足小体的形成过程及结构完整性直接影响着破骨细胞的分化及其骨吸收活性。深入研究伪足小体的结构和功能可为探索破骨细胞的骨吸收机制和寻找骨骼疾病药物作用靶点提供新的思路。该文将围绕破骨细胞伪足小体的结构、功能及其调节机制进行综述。     

人破骨细胞的原代培养和生物学特性

维持骨体积是骨吸收与骨形成相对平衡的结果,如失去这种稳定,则发生病理性变化,骨吸收破坏是主要现象之一,但关于骨吸收机理还不清楚。近些年来随着骨细胞培养技术的发展,使人们对骨吸收有了进一步认识,目前公认破骨细胞是骨吸收作用的主要承担者。为此,大多数学者从破骨细胞入手,对破骨细胞的结构和功能等进行研究。目前已从多种动物骨组织中分离出破骨细胞。本实验是通过建立人的破骨细胞分离、培养方法,为进一步开展骨吸收机理的研究奠定基础。     

机械应力对破骨细胞影响的研究进展

破骨细胞是骨组织成分的一种,由多核巨细胞组成,是人体内唯一行使分解吸收骨质功能的细胞。它与成骨细胞在功能上相对应,在维持骨细胞动态平衡中具有重要作用。机械应力具有促进成骨细胞的增殖与分化、减少骨细胞凋亡并提高骨细胞的生存能力等作用。已有研究表明,机械应力作用于破骨细胞能够降低破骨细胞活性、抑制骨吸收。破骨前体细胞与未成熟的破骨细胞在机械应力刺激下分化为成熟破骨细胞的能力有所不同,机械应力强度与作用时间对破骨细胞的活化能力影响与有差异。该文就常见的微重力、压应力、牵张力与流体剪切力对破骨细胞分化能力的影响进行综述。     

RANKL在成釉细胞瘤骨吸收机制中的作用

目的:检测RANKL在成釉细胞瘤(ameloblastoma,AM)组织中的表达情况及探讨RANKL在AM骨吸收机制中的作用.方法:通过免疫组化方法检测RANKL在AM组织中的表达情况;通过建立AM细胞/新生大鼠骨细胞共培养体系,观察AM细胞诱导破骨细胞形成的活性,再以OPG(RANKL的抑制剂)进行干预,观察OPG对AM细胞诱导破骨细胞形成活性的影响.结果:RANKL在AM组织中有恒定的表达;AM细胞能够诱导新生大鼠骨细胞分化为成熟的破骨细胞,但此活性可被OPG明显抑制.结论:AM细胞诱导破骨细胞形成可能是AM骨吸收过程中局部破骨细胞形成的重要来源和机制,而RANKL在此过程中发挥重要作用.     

从人骨巨细胞瘤组织中纯化破骨细胞的简单方法

利用破骨细胞贴壁快以及耐胰蛋白酶地特性,采用0.25%胰蛋白酶和0.2%I型胶原酶来分离纯化骨巨细胞中的破骨细胞,即得到破骨细胞,并进行细胞学和分子生物学鉴定,包括抗酒石酸酸性磷酸酶染色和HE染色,并采用RT-PCR反应方法检测降钙素受体、组织蛋白酶K和破骨细胞分化因子受体的表达。该方法所得细胞纯度可达79.7%,具有破骨细胞表型特征。可用于生化和分子生物学研究,是进行骨细胞学研究的破骨细胞来源。     

miRNAs在破骨细胞中的研究进展

破骨细胞起源于造血干细胞,是体内一种负责骨吸收的骨特异性多核细胞,在骨代谢平衡的调控中起着重要作用。破骨细胞的分化形成及功能活性异常可引起一系列临床疾病,而其分化形成过程受到多种因子的调控,近年来越来越多研究聚焦于miRNAs对破骨细胞分化形成过程的调控作用。因此,本文主要对影响破骨细胞分化形成的相关miRNAs进行综述,为后续相关研究提供参考。     

lncRNAs调控破骨细胞分化的研究进展

长链非编码RNA (long noncoding RNAs, lncRNA)是一类长度大于200个核苷酸的非编码RNA,调控转录和转录后的基因表达,在各种生命活动过程中都起着重要的作用。破骨细胞是一种组织特异性的多核巨噬细胞,受多种信号因子和信号通路的调控,作为人体唯一的骨吸收细胞对维持骨代谢平衡具有非常重要的作用,当平衡被打破时则会引起一系列骨代谢疾病,如骨质疏松症、骨硬化症等。近些年研究发现,lncRNAs在破骨细胞分化过程中呈现差异化表达,且在其增殖、分化、凋亡过程中具有多重调控作用。该文就lncRNAs调控破骨细胞分化和功能的机制进行归纳总结,为破骨细胞功能异常所造成的骨代谢疾病提供新的研究靶点和诊疗思路。     

自噬对骨疾病调控作用的研究进展

骨疾病是指机体因先天或后天性因素破坏正常骨代谢,导致骨代谢障碍而发生的一类疾病。骨主要由负责骨吸收的破骨细胞和负责骨重建的成骨细胞以及骨细胞构成。正常成人的骨形成量基本等于骨吸收量,两者处于动态平衡状态,保证了骨结构和功能的完整性。自噬是一种重要的细胞内清除机制,通过形成自噬溶酶体降解其所包裹的受损细胞器或蛋白质,实现细胞代谢和细胞器的更新。自噬相关基因的缺失能够抑制破骨细胞的骨吸收和成骨细胞的骨重建,而药物、肿瘤坏死因子等能够使自噬相关基因过表达导致骨吸收异常增加,造成骨吸收和骨形成之间的动态平衡失调,从而引起骨代谢障碍,形成骨疾病。该文分别就自噬与破骨细胞、成骨细胞以及骨疾病之间的研究进展进行综述,希望可以为骨疾病的靶向治疗提供新的思路。     

RANKL与骨重建

骨是一种动态更新的组织,它不断进行骨吸收（bone resorption）与骨形成（bone formation）的平衡,这个过程称之为骨重建（bone remodeling）．核因子κB受体活化因子配体（receptor activator of nuclear factor κB ligand,RANKL）是骨吸收和骨形成耦联的关键,具有诱导破骨细胞（osteoclast, OC）生成、活化,抑制破骨细胞凋亡的作用．RANKL最初发现于活化的T细胞,但骨重建过程中RANKL主要来源于骨细胞、成骨细胞和骨髓基质细胞．RANKL/核因子κB受体活化因子（receptor activator of nuclear factor κB,RANK）/骨保护素（osteoprotegerin, OPG）信号通路在成骨细胞调控破骨细胞生成的过程中起着重要的调节作用,是维持骨重建平衡的关键．本文就RANKL及其在骨中的分子作用机制作一综述.     

巨噬细胞源性破骨细胞在血管钙化中的作用

血管钙化是一种细胞介导的主动生物学过程，类似于骨重塑，在急慢性心脑血管事件的发生与演进过程中发挥了重要的推动作用。近年来有关血管钙化的机制与防治研究逐渐受到广大学者的关注，但遗憾的是，精准的分子与细胞靶向治疗尤其是能在临床推广应用的成果却罕有出现。新近的研究显示，糖尿病动脉粥样硬化斑块中存在成骨细胞表型和功能失调的破骨细胞表型，成骨细胞与破骨细胞调控的失衡可能是动脉粥样硬化斑块内钙化形成的关键环节。已知由巨噬细胞分化而来的破骨细胞是机体内唯一有骨吸收特性的细胞，具备促钙化消退的潜能。因此，探索促斑块内巨噬细胞源性破骨细胞骨吸收活性的研究是一个有望为钙化防治带来新突破的方向。然而，目前关于破骨细胞在血管钙化中的作用和相关调控机制仍存在争议。基于该领域的研究进展和本课题组的实验结果，本文凝练出了羧甲基赖氨酸（CML）通过STAT3调控NFATc1-GNPTAB信号介导斑块内巨噬细胞破骨化吸收障碍的假说，并从血管钙化的概念与机制、破骨细胞与血管钙化间的关系、血管钙化中破骨细胞的调控机制以及破骨细胞作为血管钙化治疗靶点4个方面进行简要阐述，希望为后续血管钙化的精准防治提供新的切入点。     

Advances in osteoclast biology resulting from the study of osteopetrotic mutations

Osteopetrosis is the result of mutations affecting osteoclast function. Careful analyses of osteopetrosis have provided instrumental information on bone remodeling, including the coupling of bone formation to bone resorption. Based on a range of novel genetic mutations and the resulting osteoclast phenotypes, we discuss how osteopetrosis models have clarified the function of the coupling of bone formation to bone resorption, and the pivotal role of the osteoclast and their function in this phenomenon. We highlight the distinct possibility that osteoclast activities can be divided into two separate avenues: bone resorption and control of bone formation.     

Dehydrocostus lactone attenuates osteoclastogenesis and osteoclast‐induced bone loss by modulating NF‐κB signalling pathway

Osteolysis is characterized by overactivated osteoclast formation and potent bone resorption. It is enhanced in many osteoclast‐related diseases including osteoporosis and periprosthetic osteolysis. The shortage of effective treatments for these pathological processes emphasizes the importance of screening and identifying potential regimens that could attenuate the formation and function of osteoclasts. Dehydrocostus lactone (DHE) is a natural sesquiterpene lactone containing anti‐inflammatory properties. Here, we showed that DHE suppressed receptor activator of nuclear factor‐κB ligand (RANKL)‐induced osteoclast formation and osteoclast marker gene expression. It also inhibited F‐actin ring formation and bone resorption in a dose‐dependent manner in vitro. Moreover, DHE inhibited the RANKL‐induced phosphorylation of NF‐κB, mitigated bone erosion in vivo in lipopolysaccharide‐induced inflammatory bone loss model and particle‐induced calvarial osteolysis model. Together, these results suggest that DHE reduces osteoclast‐related bone loss via the modulation of NF‐κB activation during osteoclastogenesis indicating that it might be a useful treatment for osteoclast‐related skeletal disorders.     

Inhibition of receptor activator of nuclear factor kappa-B ligand-mediated osteoclast differentiation and bone resorption by Gryllus bimaculatus extract: An in vitro study

Excessive bone-resorbing osteoclast activity during bone remodeling is a major feature of bone diseases, such as osteoporosis. Therefore, the inhibition of osteoclast formation and bone resorption can be an effective therapeutic target for various bone diseases. Gryllus biomaculatus (GB) has recently been approved as an alternative food source because of its high nutritional value and environmental sustainability. Traditionally, GB has been known to have various pharmacological properties, including antipyretic and blood pressure-lowering activity, and it has recently been reported to have various biological activities, including protective effects against inflammation, oxidative stress, insulin resistance, and alcohol-induced liver injury. However, the effect of GB on osteoclast differentiation and bone metabolism has not yet been demonstrated. In this study, we confirmed the inhibitory effect of GB extract (GBE) on the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation. To determine the effect of GBE on RANKL-induced osteoclast differentiation and function, we performed TRAP and F-actin staining, as well as a bone-resorbing assay. The intracellular mechanisms of GBE responsible for the regulation of osteoclastogenesis were revealed by Western blot analysis and quantitative real-time polymerase chain reaction. We investigated the relationship between GBE and expression of osteoclast-specific molecules to further elucidate the underlying mechanisms. It was found that GBE significantly suppressed osteoclastogenesis by decreasing the phosphorylation of Akt, p38, JNK, and ERK, as well as Btk-PLCγ2 signaling, in pathways involved in early osteoclastogenesis as well as through the subsequent suppression of c-Fos, NFATc1, and osteoclastogenesis-specific marker genes. Additionally, GBE inhibited the formation of F-actin ring-positive osteoclasts and bone resorption activity of mature osteoclasts. Our findings suggest that GBE is a potential functional food and therapeutic candidate for bone diseases involving osteoclasts.     

AMP-activated protein kinase (AMPK) regulates autophagy,inflammation and immunity and contributes to osteoclast differentiation and functionabs

Osteoclasts are multinucleated giant cells, responsible for bone resorption. Osteoclast differentiation and function requires a series of cytokines to remove the old bone, which coordinates with the induction of bone remodelling by osteoblast-mediated bone formation. Studies have demonstrated that AMP-activated protein kinase (AMPK) play a negative regulatory role in osteoclast differentiation and function. Research involving AMPK, a nutrient and energy sensor, has primarily focused on osteoclast differentiation and function; thus, its role in autophagy, inflammation and immunity remains poorly understood. Autophagy is a conservative homoeostatic mechanism of eukaryotic cells, and response to osteoclast differentiation and function; however, how it interacts with inflammation remains unclear. Additionally, based on the regulatory function of different AMPK subunits for osteoclast differentiation and function, its activation is regulated by upstream factors to perform bone metabolism. This review summarises the critical role of AMPK-mediated autophagy, inflammation and immunity by upstream and downstream signalling during receptor activator of nuclear factor kappa-B ligand-induced osteoclast differentiation and function. This pathway may provide therapeutic targets for bone-related diseases, as well as function as a biomarker for bone homoeostasis.     

Stachydrine prevents LPS‐induced bone loss by inhibiting osteoclastogenesis via NF‐κB and Akt signalling

Osteoclast overactivation‐induced imbalance in bone remodelling leads to pathological bone destruction, which is a characteristic of many osteolytic diseases such as rheumatoid arthritis, osteoporosis, periprosthetic osteolysis and periodontitis. Natural compounds that suppress osteoclast formation and function have therapeutic potential for treating these diseases. Stachydrine (STA) is a bioactive alkaloid isolated from Leonurus heterophyllus Sweet and possesses antioxidant, anti‐inflammatory, anticancer and cardioprotective properties. However, its effects on osteoclast formation and function have been rarely described. In the present study, we found that STA suppressed receptor activator of nuclear factor‐κB (NF‐κB) ligand (RANKL)‐induced osteoclast formation and bone resorption, and reduced osteoclast‐related gene expression in vitro. Mechanistically, STA inhibited RANKL‐induced activation of NF‐κB and Akt signalling, thus suppressing nuclear factor of activated T cells c1 induction and nuclear translocation. In addition, STA alleviated bone loss and reduced osteoclast number in a murine model of LPS‐induced inflammatory bone loss. STA also inhibited the activities of NF‐κB and NFATc1 in vivo. Together, these results suggest that STA effectively inhibits osteoclastogenesis both in vitro and in vivo and therefore is a potential option for treating osteoclast‐related diseases.     

Nitric oxide synthase I mediates osteoclast activity in vitro and in vivo

Bone resorption is responsible for the morbidity associated with a number of inflammatory diseases such as rheumatoid arthritis, orthopedic implant osteolysis, periodontitis and aural cholesteatoma. Previous studies have established nitric oxide (NO) as a potentially important mediator of bone resorption. NO is a unique intercellular and intracellular signaling molecule involved in many physiologic and pathologic pathways. NO is generated from L-arginine by the enzyme nitric oxide synthase (NOS). There are three known isoforms of NOS with distinct cellular distributions. In this study, we have used mice with targeted deletions in each of these isoforms to establish a role for these enzymes in the regulation of bone resorption in vivo and in vitro. In a murine model of particle induced osteolysis, NOS I-/- mice demonstrated a significantly reduced osteoclast response. In vitro, osteoclasts derived from NOS I-/- mice were larger than wild type controls but demonstrated decreased resorption. Although NOS I has been demonstrated in osteoblasts and osteocytes as a mediator of adaptive bone remodeling, it has not previously been identified in osteoclasts. These results demonstrate a critical role for NOS I in inflammatory bone resorption and osteoclast function in vitro.