低密度脂蛋白在2型糖尿病骨质疏松中的作用研究进展

2型糖尿病及骨质疏松已成为我国最主要的慢性代谢性疾病。2型糖尿病常伴有血脂紊乱，常表现为低密度脂蛋白升高，而越来越多的研究表明血脂通过不同的方式影响骨代谢，其机制可能是通过抑制骨髓间充质干细胞成骨分化，通过RANK/RNAKL/OPG信号通路及炎症反应调节破骨细胞等方式调节骨代谢。     

Identifying early osteoclastic resorptive lesions in feline teeth: a model for understanding the origin of multiple idiopathic root resorption

Background and Objective:  Domestic cats commonly suffer from external osteoclastic tooth resorption, a disease with many similarities to human multiple idiopathic root resorption. In both diseases, it is unclear whether anatomical features of the tooth surface are associated with a predisposition for resorptive lesions. The aim of the present study was to investigate the origin and progression of early feline osteoclastic resorptive lesions in teeth exhibiting no clinical signs of disease.
Material and Methods:  The entire surfaces of 138 teeth from 13 adult cats were analysed using back-scattered electron microscopy. The distribution of lesions was assessed by tooth type, location and between individuals.
Results:  Seventy-three (53%) teeth showed at least one resorptive lesion. Eleven (85%) cats had lesions, and there was a significant association between increasing age and incidence of resorptive lesions. The highest frequency occurred in mandibular molars (82%). On average, there were 3.5 lesions per tooth. Fifty-two (38%) teeth featured resorptive lesions at the cemento–enamel junction. Twenty-three per cent of teeth with resorptive lesions showed evidence of repair of lesions that was limited to the root surface. There was no evidence of repair of resorptive lesions at the cemento–enamel junction.
Conclusion:  Resorption is prevalent without evidence of clinical disease, and occured at younger ages than previously reported. It can initiate anywhere on the root surface, but lack of repair of lesions at the cemento–enamel junction indicates that mechanisms of replacement are absent or compromised in this region. Whereas resorption of the root may undergo repair, resorption at the cervix may progress to clinically evident lesions.     

F-spondin inhibits migration and differentiation of osteoclastic precursors

Background: Clinically, severe cemental resorption is a rare consequence of periodontitis, although alveolar bone resorption by osteoclasts is one of the main pathologic changes. F‐spondin is a secreted neuronal glycoprotein that localizes to the cementum. F‐spondin is among the cementum‐specific factors in periodontal tissue that have been reported. However, the effects of F‐spondin on osteoclastogenesis have not yet been established. We examined the effects of F‐spondin on stages of osteoclastogenesis, migration, and differentiation in a mouse osteoclastic precursor model, RAW 264 cells. Methods: RAW 264 cells were treated with recombinant F‐spondin. Macrophage colony stimulating factor (M‐CSF)–induced cell migration was examined by migration assay performed with cell culture inserts. Osteoclastic differentiation was measured by counting tartrate‐resistant acid phosphatase (TRAP)–positive multinucleated cells. Results: In a transmigration assay, F‐spondin significantly downregulated M‐CSF–induced cell migration. Further, F‐spondin significantly reduced the number of receptor activator of nuclear factor‐kappa B ligand–induced TRAP‐positive multinucleated cells. The receptor‐associated protein, an antagonist of the low‐density lipoprotein (LDL) receptor family, blocked the effects of F‐spondin on M‐CSF–induced migration. The suppressive effect of F‐spondin on M‐CSF–induced cell migration was blocked by knockdown of LDL receptor–related protein 8 (LRP8), a member of the LDL receptor family. Conclusions: Our findings suggest that F‐spondin downregulates recruitment to the root side of periodontal tissue via LRP8 and inhibits differentiation of osteoclastic precursors. It is suggested that F‐spondin is essential to protect the root surface from resorption.     

MicroRNA-21与骨质疏松症相关性的研究进展

骨质疏松症(osteoporosis,OP)是一种以易骨折为特点的全身代谢性骨骼疾病。在老龄化程度不断加剧的当今社会,其发病率逐年呈现显著上升趋势,尤其是骨质疏松性骨折导致的后遗症、副损伤给社会及患者带来极大的经济和生活负担。近年来诸多研究发现microRNA具有明确的抗骨质疏松作用,随着基因疗法应用的推广,microRNA在临床治疗骨质疏松起到了很好的靶向作用,同时相关文献阐释,尤其是其家族成员microRNA-21可通过调控成骨细胞和破骨细胞的分化与功能,在OP等骨疾病的发生发展过程中起着重要作用。本文将通过对microRNA-21在骨质疏松中的相关作用机制进行综述,旨在为OP靶向治疗及相关分子机制研究提供理论依据和新的思路。     

微重力引起的骨质丢失研究进展

人类对太空的探索日益频繁,然而太空微重力会引起航天员骨质丢失,对航天员的健康造成损害。因此,有研究者通过航天实验及模拟微重力实验研究微重力下骨质丢失的发生机制及解决措施。微重力会引起成骨细胞和破骨细胞代谢活动改变,并引起机体对钙离子新陈代谢的改变。航天微重力导致的骨质丢失是微重力和太空射线共同作用的结果。本文将对微重力所致骨质丢失的发生机制和治疗对策加以概述。     

蛇床子素/壳聚糖衍生物胶束对去卵巢骨质疏松大鼠骨微结构和骨吸收的影响

目的观察蛇床子素/壳聚糖衍生物胶束(Osthole-loaded N-octyl-O-sulfonyl chitosan micelles,NSC-OST)对去卵巢骨质疏松大鼠骨微结构和骨吸收的影响,初步探讨其抗骨质疏松的分子机制。方法将40只雌性SD大鼠按照随机原则分为5组:假手术组(Sham)、模型组(Ovx)、尼尔雌醇组(Nil)、蛇床子素(OST)、蛇床子素/壳聚糖衍生物胶束组(NSC-OST),除了假手术组以外均通过摘除双侧卵巢形成骨质疏松模型,连续给药12周后,通过HE染色和Micro-CT检测分别从二维、三维形态学角度观察药物对骨微结构的影响;通过抗酒石酸酸性磷酸酶染色观察药物对体内破骨细胞生成和分化的影响;通过免疫组化手段检测药物对破骨特异分子NFATc1、c-fos、CTSK表达的影响。结果 HE染色结果显示药物组均能明显改善造模引起的组织骨质疏松样改变,其中Nil组改善骨微结构的效果最明显,其次为NSC-OST组,最后是OST组;通过Micro-CT分析发现NSC-OST可显著提高大鼠股骨的BMD和BV/TV(P0.05),并明显改善Tb.N、Tb.Sp、Tb.Th三项指标(P0.05),效果要优于OST组,但略逊于Nil组; TRAP染色提示NSC-OST可以明显抑制N.Oc/BS和Oc.S/BS两项破骨生成参数(P0.05),效果要优于OST组,但略逊于Nil组;免疫组化实验提示:NSC-OST可以抑制大鼠骨组织中的破骨特异分子NFATc1、c-fos、CTSK的表达,前两项指标NSC-OST与Nil抑制作用相当,抑制CTSK时NSC-OST的作用要弱于Nil,均强于OST。结论 NSC-OST可以显著改善去卵巢大鼠的骨微结构,其抗骨质疏松作用的发挥可能与其抑制破骨细胞的生成和分化相关。     

低浓度唑来膦酸对成骨细胞和破骨细胞影响的体外实验

目的：观察低浓度(10-6 mol/L)唑来膦酸(zoledronate acid,ZA)对体外大鼠破骨细胞及成骨细胞的影响。方法体外分别培养大鼠来源的成骨细胞和破骨细胞,将两种细胞各分为两组：空白对照组及低浓度(10-6 mol/L)ZA组。应用抗酒石酸酸性磷酸酶染色、图像分析计算骨吸收陷窝面积,检测破骨细胞形态及骨吸收情况。碱性磷酸酶(alkaline phosphatase, ALP)染色、四甲基偶氮唑盐比色法了解成骨细胞的形态及增殖情况。结果培养1周后破骨细胞具有典型的形态特征,并在骨片上形成了吸收陷窝;ZA组与对照组相比,破骨细胞数量及生成吸收陷窝的数目和面积减少,差异有统计学意义(P＜0.05)。成骨细胞有典型的梭形、ALP染色阳性特征,培养至第7天ZA组成骨细胞光吸收值(3.37±0.11)高于对照组(2.87±0.12),差异有统计学意义(P＜0.05)。结论低浓度(10-6 mol/L)的ZA能够抑制破骨细胞的增殖和活性,促进成骨细胞的增殖,选择恰当给药方式和剂量能够在抑制破骨的同时促进成骨。     

Dual Effects of Liquiritigenin on the Proliferation of Bone Cells: Promotion of Osteoblast Differentiation and Inhibition of Osteoclast Differentiation

Bone is constantly controlled by a balance between osteoblastic bone formation and osteoclastic bone resorption. Liquiritigenin is a plant‐derived flavonoid and has various pharmacological effects, such as antioxidative, antitumor, and antiinflammatory effects. Here, we show that liquiritigenin has dual effects on the proliferation of bone cells, regarding the promotion of osteoblast differentiation and the inhibition of osteoclast differentiation. Liquiritigenin‐treated murine osteoblastic MC3T3‐E1 cells showed an increased alkaline phosphatase activity and enhanced phosphorylation of Smad1/5 compared with untreated cells. Moreover, liquiritigenin inhibited osteoclast differentiation, its bone‐resorption activity through slightly decreased the phosphorylation of extracellular signal‐regulated kinase, c‐Jun N‐terminal kinase, and inhibitor of nuclear factor kappa Bα; however, the phosphorylation of Akt and p38 slightly increased in bone marrow‐derived osteoclasts. The expression levels of the osteoclast marker proteins nuclear factor of activated T‐cell cytoplasmic‐1, Src, and cathepsin K diminished. These results suggest that liquiritigenin may be useful as a therapeutic and/or preventive agent for osteoporosis or inflammatory bone diseases. Copyright © 2015 John Wiley & Sons, Ltd.