Wnt/β-catenin基因对骨髓瘤患者间充质干细胞成骨潜能的影响

目的:探讨Wnt/β-catenin基因和多发性骨髓瘤骨病的关系。方法:分离培养多发性骨髓瘤患者和正常人的骨髓间充质干细胞(MSCs),体外诱导分化成骨细胞,茜素红实验检测矿化物沉积、荧光定量RT-PCR方法检成骨指标(OPN、OC、ALP、Cbfal)和Wnt/β-catenin mRNA表达,分析MSCs细胞成骨能力变化及两组间Wnt/β-catenin mRNA表达差异。结果:骨髓MSCs体外成骨诱导后,茜素红染色阳性,呈现明显红色钙化结节;MSCs体外诱导成骨细胞,试验组与对照组比较,成骨指标OPN、OC、ALP、Cbfαl mRNA表达降低(P<0.05);骨髓MSCs体外成骨诱导后β-catenin mRNA表达降低(P<0.05)。结论:骨髓MSCs体外可成功诱导分化为成骨细胞;多发性骨髓瘤患者MSCs向成骨细胞分化潜能比正常人降低,Wnt/β-catenin可作为多发性骨髓瘤骨病潜在治疗靶点。     

破骨样细胞中骨保护素和NF-κB配体受体的表达及其意义

目的探讨破骨样细胞中骨保护素(OPG)和NF-κB配体受体(RANKL)表达情况。方法单独培养骨髓单核细胞前体,用巨噬细胞集落刺激因子(M-CSF)和维生素D诱导其转化为破骨样细胞,在0、5、10、15 d用光镜观察和TRAP染色(抗酒石酸染色)评估破骨样细胞的转化程度,用RT-PCR检测OPG和RANKL的表达情况;然后构建主动脉中膜平滑肌细胞(SMC)与骨髓单核细胞前体共培养的模型,用维生素C和β-磷酸甘油诱导SMC转化为成骨样细胞,并在0、5、10、15 d用同样方法再次检测共培养中破骨样细胞转化的情况,以及两种细胞中OPG和RANKL的表达情况。结果不管是单独培养、还是共培养,破骨样细胞中始终没有OPG和RANKL的表达。结论破骨样细胞的转化可能主要受成骨样细胞分泌的OPG和RANKL调控,本身并没有分泌OPG和RANKL进行自身调节的机制存在。     

白三烯B4对骨髓细胞及成骨细胞骨代谢相关基因mRNA表达的影响

目的观察不同浓度白三烯B4(LTB4)干预后大鼠骨髓细胞及成骨细胞过氧化物酶体增生物激活受体γ2(PPARγ2)及骨代谢相关基因核因子-KB活化受体配体(RANKL)、碱性磷酸酶(ALP)、骨保护素(OPG)、核因子-KB活化受体(RANK)和抗酒石酸酸性磷酸酶(TRAP)mRNA表达水平的变化,探讨PPARγ2内源性配体LTB4在骨代谢中的作用。方法体外培养大鼠骨髓细胞及成骨细胞,分别加入不同浓度LTB4(0、0.1、1.0、10.0μmol/L)干预24 h,采用逆转录PCR(RT-PCR)法检测骨髓细胞PPARγ2、RANKL、ALP、OPG、RANK、TRAP mRNA表达水平及成骨细胞PPARγ2、RANKL、ALP、OPG mRNA表达水平,比较不同浓度LTB4对上述基因表达的影响。结果 (1)不同浓度LTB4呈剂量依赖性下调骨髓细胞RANKL、ALP、OPG mRNA的表达水平,同时呈剂量依赖性上调PPARγ2、RANK、TRAP mRNA的表达水平,组间比较差异均有统计学意义(P0.05,P0.01);(2)不同浓度LTB4呈剂量依赖性下调成骨细胞RANKL、ALP、OPG mRNA的表达水平,同时呈剂量依赖性上调PPARγ2mRNA的表达水平,组间比较差异有统计学意义(P0.05,P0.01)。结论 LTB4可能通过激活PPARγ2转录活性抑制骨髓细胞及成骨细胞成骨标记物基因的表达,促进骨髓细胞破骨标记物基因的表达,从而参与与增龄相关的骨质疏松的发病过程。     

CD44对体外培养的成骨细胞及破骨样细胞形成过程中的影响

目的 通过体外细胞培养探讨粘附分子CD44在成骨细胞及破骨样细胞形成过程中的作用.方法 在体外培养的骨髓间充质干细胞向成骨细胞分化过程中,用免疫细胞化学方法来检测其细胞CIM4的表达及其意义;并在细胞核因子kB受体活化因子配基(receptor activator of nuclear factor-k B ligand,RANKL)和巨噬细胞集落刺激因子(Macrophage-colony stimulating factor,M-CSF)诱导的破骨样细胞培养体系中加入CD44抗体,通过抗酒石酸酸性磷酸酶(TRAP)染色鉴定破骨样细胞的形成.结果 成骨细胞培养体系中,空白组及地塞米松干预组间细胞CD44的表达没有显著性差异,但是指数增长期,地塞米松干预组的CD44的表达上升慢;破骨样细胞培养体系中,第6和9天,CD44抗体干预组的TRAP阳性细胞率明显低于对照组.结论 CD44在成骨细胞形成、增殖、成熟过程没有促进作用,但在破骨样细胞形成过程中起着一定的促进作用,它与单个核细胞的融合有一定的关系.     

补骨脂素对成骨细胞核因子-κB受体激活配体和骨保护素表达的影响

目的研究补骨脂素(psoralen,PSO)对体外培养的小鼠成骨细胞(OB)分化及核因子-κB受体激活配体(receptor activator of nuclearfactor-κB ligand,RANKL)和骨保护素(osteoprotegerin,OPG)表达的影响。方法取第1代BALB/c小鼠颅盖骨成骨细胞,将PSO以0.1、1、10μmol/L3种浓度分别加入新生大鼠颅骨成骨细胞培养液中,MTT法观察各组药物对成骨细胞的增殖作用并绘制细胞生长曲线;用PNPP法测定成骨细胞内碱性磷酸酶(alkaline phosphatase,ALP)活性;RT-PCR法检测成骨细胞OPG和RANKL的转录水平。结果细胞生长曲线显示各组成骨细胞数量均随时间延长而增加,中、高浓度PSO能显著提高成骨细胞的ALP活性,促进OPG、RANKL的表达(P<0.05),OPG/RANKL升高(P<0.05)。结论低浓度PSO(0.1μmol/L)对骨更新作用不明显,而中、高浓度PSO(1、10μmol/L)能通过上调OPG、RANKL mRNA表达及OPG/RANKL比例,促进成骨细胞的生成功能,增强骨更新。     

17β-雌二醇对新生大鼠成骨细胞护骨素和破骨细胞分化因子表达的调节

体外培养成骨细胞，用不同浓度（10^-11～10^-6mol／L）17β-雌二醇干预，RT—PCR测定护骨素、破骨细胞分化因子（ODF）mRNA的表达水平。雌二醇作用后，成骨细胞护骨素表达上调（P〈0．05），以10^-8mol／L最显著；ODF表达无明显变化。雌激素治疗骨质疏松症的作用可能与其在生理浓度时促进成骨细胞护骨素表达有关。     

BMP-4与17β-雌二醇对MBA-1细胞护骨素表达的影响

目的 探讨骨形态生成蛋白-4（BMP-4）与17β-雌二醇对小鼠骨髓基质细胞株MBA-1细胞护骨素表达的影响.方法 用BMP-4及17β-雌二醇干预MBA-1细胞后,用R T-PCR和Western印迹检测护骨素表达的变化.结果 在无BMP-4或17 β-雌二醇干预的情况下,MBA-1细胞在自身分化成熟过程中伴有护骨素的表达增加;经BM P-4与17β-雌二醇干预后可上调MBA-1细胞护骨素表达增加.结论 B MP-4 与17β-雌二醇可上调MBA-1细胞护骨素表达,从而诱导MBA-1细胞向成骨细胞方向分化.     

成骨细胞Toll样受体4信号通路研究进展

Toll样受体4(TLR4)为天然免疫的关键模式识别受体,在骨丢失发病机制中发挥重要作用。TLR4通路与影响成骨细胞的其他通路如Wnt/β-catenin、TGF-β/BMP、Notch通路间存在密切联系。TLR4通路通过抑制NF-κB配体受体活化剂(RANKL)、骨保护素(OPG)、碱性磷酸酶(ALP)等成骨相关标志物表达抑制成骨细胞的分化、增殖、矿化等。TLR4通路还能促进成骨细胞凋亡、降低骨密度。本文就TLR4结构、功能及其对成骨细胞的作用进行综述。     

鼠成骨细胞诱导兔BMSCs成骨的实验观察

目的观察乳鼠成骨细胞诱导乳兔骨髓间充质干细胞（BMSCs）的成骨情况。方法取SD大鼠乳鼠颅盖骨,采用组织块培养法培养成骨细胞;取乳兔长骨,采用全骨髓培养法培养BMSCs;用Transwell双层细胞培养板共育,实验组于培养上室接种成骨细胞,对照组培养上室不接种细胞,两组培养下室均接种BMSCs。观察BMSCs形态变化,用酶标仪检测诱导分化后BMSCs的ALP活性,RT—PCR检测BMSCs中的骨钙素、骨形态发生蛋白-2（BMP-2）、Ⅰ型胶原基因。结果共培养后实验组BMSCs形态逐渐向成骨样细胞转化,对照组无明显变化;实验组BMSCs中ALP活性高于对照组,实验组的BMSCs的骨钙素、BMP-2、Ⅰ型胶原基因有所表达,对照组无表达。结论乳鼠成骨能够诱导乳兔BMSCs向成骨细胞分化。     

PI3K／Akt信号通路在骨髓间充质干细胞增殖及成骨分化调控中的作用

目的：研究PI3K/Akt信号通路抑制剂LY294002对骨髓间充质干细胞（mesenchymal stem cells,MSCs）增殖及分化的影响。方法采用贴壁法体外分离人骨髓间充质干细胞（hMSCs）,加入PI3K抑制剂LY294002（1、10μmol/L）,应用MTT法测定细胞增殖,常规成骨诱导分化培养3或7d,采用碱性磷酸酶（ALP）染色观察成骨分化水平,化学比色法测定ALP活性,茜素红染色后观察矿化钙结节数量并定量分析,Westernblot检测磷酸化Akt蛋白表达,应用Realtime-PCR检测各组细胞BMP2、Runx2、OPN及Osterix等成骨分化标记物的基因表达水平。结果从24至72h,LY294002对hMSCs增殖均产生显著抑制,随时间推延,可见抑制增殖效果增强（P＜0.05）。ALP染色和定量测定提示10μmol/L的ALP活性最强,在不同时间显著高于对照组和1μmol/L组（P＜0.05）。成骨诱导培养3和7d,1、10μmol/L组矿化量都显著高于对照组（P＜0.05）。10μmol/L组矿化量在成骨诱导7d也显著高于1μmol/L组（P＜0.05）。Westernblot检测结果证实成骨诱导可激活Akt磷酸化蛋白表达,但LY294002可抑制该蛋白磷酸化。成骨诱导分化7d,1、10μmol/L均明显促进BMP2、Runx2、OPN、Osterix4种基因mRNA表达（均P＜0.05）。结论PI3K/Akt信号通路参与hMSCs增殖和分化过程。成骨分化伴随下游Akt蛋白表达。PI3K抑制剂可抑制hMSCs增殖,但同时促进其向成骨分化和矿化。     

Regulatory Effect of Parathyroid Hormone on sRANKL-Osteoprotegerin in Hemodialysis Patients With Renal Bone Disease

Abstract: Receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin are newly identified molecules that contribute to the modulation of bone remodeling. RANKL activates osteoclast function by binding to RANK in either a soluble or membrane-bound form, whereas osteoprotegerin (OPG) neutralizes its effects. The aim of this study is the evaluation of soluble RANKL (sRANKL)-OPG in cohorts of hemodialysis patients and the establishment of possible correlations between their serum levels and those of other biochemical markers. We measured intact parathyroid hormone (iPTH), osteocalcin (OC), OPG, alkaline phosphatase (ALP), tartrate-resistant acid phosphatase (TRAP) and sRANKL in 104 hemodialysis patients. The patients were studied as a whole and in two subgroups according to their bone turnover state. In patients with low serum levels of bone turnover markers (intact parathyroid hormone [iPTH] < 100 pg/mL, ALP < 100 U/L, TRAP < 4U/L; 33 patients), the following correlations were found: (i) positive correlations of iPTH with RANKL (r = 0.394, P = 0.023) and RANKL/OPG ratio (r = 0.49, P = 0.004); (ii) a negative correlation between iPTH and OPG (r = −0.365, P = 0.037). The subgroup of patients with normal or high serum levels of bone turnover markers (iPTH ≥ 150 pg/mL, ALP ≥ 100U/L, OC ≥ 40 ng/mL; 19 patients) exhibited the following significant correlations: (i) a positive correlation between OPG and iPTH serum level (r = 0.649, P = 0.003); and (ii) a negative correlation between RANKL/OPG ratio and iPTH (r = −0.464, P = 0.045). In conclusion, the observation that PTH favors RANKL and inhibits OPG production was only demonstrated in the serum of hemodialysis patients in a low turnover state. The positive correlation between serum OPG and iPTH in normal or high turnover rates implies a homeostatic mechanism to limit bone resorption, probably associated with skeletal resistance to PTH.     

Implication of bone regulatory factors in human coronary artery calcification

Background

Although emerging evidence suggests that vascular calcification constitutes an active process sharing common features with bone formation, several aspects of this process in human coronary artery calcification are still poorly understood. We therefore investigated the expression of key bone regulatory factors in human atherosclerotic coronary arteries.

Methods – Results

Formalin, fixed-paraffin embedded tissue samples of human atherosclerotic coronary arteries (n = 41) and normal arteries as controls (n = 9) were studied immunohistochemically for the expression of osteoprotegerin (OPG), RANKL, RANK, Runx2, Sox9, NFATc1 and Osterix (Osx). All factors where expressed in atherosclerotic lesions while absent in normal arteries, with the exception of OPG. While expression of NFATc1 and Osx was confined to tunica intima of diseased arteries, the others factors were expressed in both tunica intima and tunica media. Most factors were expressed in smooth muscle-like cells of tunica intima while NFATc1 and the OPG/RANKL/RANK system were also expressed in inflammatory cells. Wheareas expression of OPG and RANKL was invariable, expression of RANK, Runx2, Sox9, Osx and NFATc1 was significantly higher in advanced calcified lesions. Significant correlations were also observed among the bone regulatory factors in atherosclerotic arteries.

Conclusions

Our results confirm the hypothesis that highly regulated osteogenic processes are involved in the mineralization of human coronary arteries and implicate the bone regulatory factors Osx and NFATc1 in coronary artery calcification.     

类风湿关节炎中白三烯B4间接分化破骨细胞的实验研究

目的探讨在类风湿关节炎（RA）中,白三烯B4（LTB4）能否通过促进核因子Kappa B受体激活剂配体（RANKL）的表达,起到间接分化破骨细胞的作用.方法利用RA滑膜成纤维细胞（RAFLs）和人外周血单核细胞的共培养体系,对照组2.5 ng/ml巨噬细胞集落刺激因子（M-CSF）刺激、实验a组2.5 ng/ml M-CSF＋10-8mol/L LTB4刺激、实验b组2.5 ng/ml M-CSF＋10-8 mol/L LTB4＋100 ng/ml骨保护素（OPG）刺激,培养3周后行抗酒石酸酸性磷酸酶（TRAP）细胞化学染色,通过计数多核性TRAP酶染色阳性的破骨细胞样细胞,比较各组的分化破骨细胞作用.结果对照组几乎没有破骨细胞样细胞,而实验a组则出现较多的破骨细胞样细胞,实验b组则与对照组相似,几乎没有破骨细胞样细胞.结论在RA中,LTB4能够通过促进RAFLs细胞RANKL的表达来间接分化破骨细胞.     

脂联素调控人成骨细胞OPG/RANKL表达的信号转导机制

目的 研究脂联素调控人成骨细胞护骨素(OPG)和NF-кB受体活化凶子配体(RANKL)表达的作用机制.方法 人成骨细胞OPG和RANKL mRNA的表达以实时PCR检测,p38丝裂原活化蛋白激酶(p38 MAPK)、细胞外信号调节激酶(ERK1/2)、c-Jun氨基端激酶(JNK)的磷酸化水平用Western印迹法检测.廊用小分子RNA干扰技术(siRNA)阻断脂联素受体(AdR)表达,并以p38 MAPK抑制剂(SB203580)和JNK抑制剂(SP600125)干预,以观察脂联素对人成骨细胞OPG/RANKL作用的调节机制.结果 用siRNA沉默AdRl的表达可消除脂联素促进人成骨细胞RANKL表达和抑制OPG表达的作用;脂联素干预前予SB203580阻断p38 MAPK后,也可消除脂联素对成骨细胞RANKL和OPG的作用,而SP600125并无作用.结论 在人成骨细胞中,脂联素通过AdR1/p38 MARK途径促进RANKL表达和抑制OPG的表达.     

Proteasome inhibitors and bone disease

Bone disease in patients with multiple myeloma (MM) is characterized by increase in the numbers and activity of bone-resorpting osteoclasts and decrease in the number and function of bone-formation osteoblasts. MM-triggered inhibition of bone formation may stem from suppression of Wnt/β-catenin signaling, a pivotal pathway in the differentiation of mesenchymal stem cells (MSC) into osteoblasts, and regulating production of receptor activator of nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG) axis by osteoblasts. Proteasome inhibitors (PIs), such as bortezomib (Bz), induce activation of Wnt/β-catenin pathway and MSC differentiation toward osteoblasts. PIs also suppress osteoclastogenesis, possibly through regulating multiple pathways including NF-κB, Bim, and the ratio of RANKL/OPG. The critical role of PI in increasing osteoblast function and suppression of osteoclast activity is highlighted by clinical evidence of increases in bone formation and decreases in bone resorption makers. This review will discuss the function of PIs in stimulating bone formation and suppression of bone resorption, and the mechanism underlying this process that leads to inhibition bone disease in MM patients.     

Tigogenin inhibits adipocytic differentiation and induces osteoblastic differentiation in mouse bone marrow stromal cells

We investigated the effect of tigogenin on adipocytic and osteoblastic differentiation in mouse bone marrow stromal cells (BMSCs). Tigogenin enhanced the proliferation of BMSCs significantly. Tigogenin treatment reduced the adipogenic induction of lipid accumulation, visfatin secretion, and the expressions of peroxisome proliferation-activated receptor (PPAR)γ2 and adipocyte fatty acid-binding protein (ap)2. Moreover, tigogenin had no effect on the mitotic clonal expansion. On the other hand, tigogenin significantly elevated alkaline phosphatase (ALP) activity and the expressions of Cbfa1, collagen type I (COL I) and osteocalcin (OCN), as well as the content of matrix calcium in BMSCs. Further, SB-203580 antagonized the tigogenin-promoted osteogenesis. These observations suggested that tigogenin may modulate differentiation of BMSCs to cause a lineage shift away from the adipocytes and toward the osteoblasts, which is at least mediated by inhibition of PPARγ and via p38 MAPK pathway, and is a potential drug preventing the development of osteoporosis and the related disorders.