BMAL1基因对骨髓间充质干细胞成骨分化的调控作用

牙周炎是以牙周组织破坏为特征的感染性疾病,作为重要的牙周组织再生种子细胞,骨髓间充质干细胞在重构牙周组织结构和功能、促进牙周病好转乃至愈合方面具有重要作用,因此骨髓间充质干细胞的特性尤其是其成骨分化的相关调控机制是目前研究热点之一。BMAL1基因与骨髓间充质干细胞成骨分化等诸多生理行为的调控关系密切,有望成为牙周疾病新的治疗靶点。本文对BMAL1基因的特性以及调控骨髓间充质干细胞成骨分化的机制作一综述。     

Lack of Toll‐like receptor 4 decreases lipopolysaccharide‐induced bone resorption in C3H/HeJ mice in vivo

Introduction: Few in vivo studies have demonstrated whether Toll‐like receptor 4 (TLR4) is indispensable for lipopolysaccharide (LPS)‐induced bone resorption and little is known about the receptor activator of nuclear factor‐κB ligand (RANKL) and osteoprotegerin (OPG) expression induced by LPS under conditions of lack of TLR4. Methods: We compared bone resorption histomorphometrically in C3H/HeN and C3H/HeJ mice that were repeatedly injected with Actinobacillus actionmycetemcomitans LPS into their gingiva every 48 h. RANKL‐, interleukin‐1β‐ and OPG‐positive cells in the connective tissue were also compared immunohistochemically. Results: Bone resorption in C3H/HeJ mice in the fourth, seventh, and tenth injection groups was significantly less than that C3H/HeN mice (P < 0.05). The number of RANKL‐positive cells in C3H/HeJ mice in the 10th injection group was significantly smaller than that in C3H/HeN mice (P < 0.05). The numbers of interleukin‐1β‐positive cells in C3H/HeJ mice in the seventh and tenth injection groups were significantly decreased compared with those in C3H/HeN mice (P < 0.05). The numbers of OPG‐positive cells in C3H/HeN and C3H/HeJ mice gradually increased, but there was no significant difference between the two strains of mice. Conclusion: TLR4 is indispensable for LPS‐induced bone resorption in vivo.     

Involvement of toll‐like receptor 4 in alveolar bone loss and glucose homeostasis in experimental periodontitis

Watanabe K, Iizuka T, Adeleke A, Pham L, Shlimon AE, Yasin M, Horvath P, Unterman TG. Involvement of toll‐like receptor 4 in alveolar bone loss and glucose homeostasis in experimental periodontitis. J Periodont Res 2011; 46: 21–30. © 2010 John Wiley & Sons A/S Background and Objective: There is general agreement that certain fatty acids and lipopolysaccharides (LPS) promote inflammation through toll‐like receptor 4 (TLR4), and that inflammation promotes insulin resistance. We therefore hypothesized that mice with periodontitis and a TLR4 loss‐of‐function (LOF) mutation fed a high‐fat (HF) diet would develop improved glucose homeostasis compared with wild‐type (WT) animals with periodontitis fed a HF diet. Material and Methods: Wild‐type and TLR4 mutant mice fed a HF diet were divided into four groups (n = 6/group): WT; WT with periodontitis (WT/P); mutant (Mut); and mutant with periodontitis (Mut/P). Periodontitis was induced by placing LPS soaked ligatures around maxillary second molars. Fasting insulin and glucose levels were measured weekly for 10 wk. Glucose tolerance was evaluated at baseline (week 1) and at 9 wk. Insulin signaling (phosphorylation of Akt) and tumor necrosis factor‐α (TNF‐α) mRNA levels in liver were determined when the mice were killed at week 10. Results: Mut/P mice developed less alveolar bone loss compared with WT/P mice (p < 0.05). Fasting glucose levels were improved after 8 wk of feeding a HF diet (weeks 9 and 10) in Mut/P mice compared with Mut, WT and WT/P mice (p < 0.05). Glucose tolerance was impaired in all groups compared with baseline (p < 0.05), except for the Mut/P group. Insulin signaling was improved (p < 0.05), and expression of TNF‐α was decreased (p < 0.05) in the liver of Mut/P mice compared with the liver of WT/P mice. Conclusion: The TLR4 LOF mutation partially protects against alveolar bone loss and improves glucose homeostasis in mice with periodontitis fed a HF diet.     

Wnt和Notch通路在老龄个体骨髓间充质干细胞成骨中的调控

社会老龄化的加剧使老年个体骨损伤修复问题愈发突出,骨髓间充质干细胞(BMSC)是一种与骨代谢再生密切相关的骨髓细胞,其生物学特性(形态、表面特征、细胞周期、端粒酶以及细胞内活性氧簇水平等)以及增殖分化能力在生物体年龄影响下均发生了改变,成骨能力下降,影响了骨损伤的修复速度和质量.探索其中分子机制对改善老龄个体骨损伤康复有至关重要作用.参与调控的信号中,Wnt和Notch近年日益受到关注,二者对老龄BMSC成骨的调控有交互作用.老龄机体的氧化应激反应增加而生长因子生成减少,Wnt通路的转录因子β-catenin与叉头家族转录因子的亲和力增加,不再与T细胞因子和淋巴增强因子结合,故BMSC成骨减弱.同时老龄个体骨髓中BMSC数量减少,Notch抑制BMSC成骨来维持祖细胞池中BMSC的数量.Wnt和Notch之间还存在相互作用,如Notch过表达能够削弱Wnt的影响等.此外,BMP-Smad转录因子活性下降,Hedgehog信号通路下调,亦影响着BMSC的成骨分化.本文对老龄个体BMSC生物学性能变化及其成骨分化过程中信号通路的调控作用进行综述,为老龄个体骨相关性疾病的治疗提供新思路.     

神经肽P物质及骨形态发生蛋白信号通路在ST2细胞成骨分化过程中的作用

目的 探讨神经肽P物质（SP）在ST2细胞（小鼠骨髓间充质干细胞）成骨分化过程中的作用及机制,以期为颞下颌关节骨关节炎的治疗提供依据。方法 对第3代ST2细胞分别用0、10^-10、10^-8 、10^-6、10^-5 mol·L^-1 SP培养,24、48、72 h后采用CCK-8实验检测细胞增殖情况。以10^-6 mol·L^-1 SP培养第3代ST2细胞1、3、5、7 d后,采用酶联免疫吸附试验（ELISA）检测上清液中碱性磷酸酶（ALP）、Ⅰ型胶原蛋白（CollaⅠ）和骨钙素（OCN）的表达,免疫荧光染色检测细胞ALP活性。分别用SP、Noggin（骨形态发生蛋白信号通路抑制剂）、SP+Noggin和2%胎牛血清培养ST2细胞,采用ELISA法检测上清液中ALP、CollaⅠ和OCN的表达。结果 CCK-8结果显示,24、48、72 h时均以10^-6 mol·L^-1 SP促进ST2细胞增殖活性最为明显（P<0.01）。ELISA结果显示,ALP表达在5 d时较对照组差异最为明显（P<0.01）,CollaⅠ和OCN的表达在7 d时较对照组差异最为明显（P<0.05）;免疫荧光结果显示,ALP活性在5 d时最强;加入抑制剂Noggin后,ALP、CollaⅠ和OCN表达量均降低。结论 SP可促进ST2细胞增殖和成骨分化,骨形态发生蛋白信号通路可能参与了此过程。     

低氧调控大鼠骨髓间充质干细胞OPG/RANKL mRNA的表达

目的:探讨低氧处理对大鼠骨髓间充质干细胞(rat bone marrow derived mesenchymal stem cells,rBMSCs)骨保护素(osteoprotegerin,OPG)和核因子κb受体活化因子配体(receptor activator of NF-κb ligand,RANKL)mRNA表达的影响.方法:采用全骨髓细胞贴壁法分离、培养rBMSCs,应用化学低氧剂氯化钴(CoCl2)建立低氧模型,分别以0、50、100、200、400μmol/L浓度的CoCl2孵育细胞,首先采用MTT法检测CoCl2对细胞增殖的影响;利用实时荧光定量PCR及Western免疫印迹检测低氧诱导因子1 α(hypoxia inducible factor-1α,HIF-1α)的表达情况.rBMSCs经低氧处理0、12、24、48、72、96 h,实时荧光定量PCR检测OPG、RANKL mRNA的表达.采用SPSS18.0软件包对数据进行统计学分析.结果:与对照组相比,200、400 μmol/L的CoGl2抑制rBMSCs增殖(P＜0.05),而50、100 μmol/L CoCl2实验组的增殖并未产生显著影响(P＞0.05).在50、100 μmol/L CoCl2实验组,rBMSCs表达HIF-1α的mRNA和蛋白水平均高于对照组,100 μmol/L CoCl2组较50 μmol/L CoCl2组高.100 μmol/L CoCl2孵育12h时,低氧组和对照组rBMSCs的OPG、RANKL mRNA的表达无变化(P＞0.05);24、48、72、96 h时,与常氧组相比,低氧组OPG mRNA表达水平升高,RANKL mRNA表达水平下降,OPG/RANKL的比值显著升高(P＜0.05).结论:100 μmol/L CoCl2低氧处理可通过调控rBMSCs OPG、RANKL mRNA的表达,从而促进成骨分化.     

Uncovering the role of brain‐derived neurotrophic factor/tyrosine kinase receptor B signaling in head and neck malignancies

Brain‐derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors that was first known as responsible for sustain the growth, function, and plasticity of neural cells. BDNF exerts its effects by binding to the tyrosine kinase receptor B (TrkB). The BDNF/TrkB axis has been reported to be overexpressed in several neurogenic and non‐neurogenic tumors. Its higher expression was associated with a poor prognosis to patients affected by different human malignancies, tumor growth, invasion, and metastasis; epithelial‐mesenchymal transition and resistance to chemotherapy. BDNF/TrkB represent promising targets to the development of novel anticancer therapies. Some clinical trials are currently evaluating the efficacy of Trk protein‐target drugs in different types of solid tumors. To date, few groups have evaluated the DNF/TrkB pathway in head and neck malignancies. The aims of this study were to review the literature concerning the role of BDNF/TrkB activation in head and neck squamous cell carcinoma and malignant salivary gland tumors and to discuss future perspectives of BDNF/TrkB‐target therapy.     

调节Lnk/干细胞因子-干细胞因子受体通路对糖尿病状态骨髓间充质干细胞成骨功能的影响

目的 探讨调节Lnk/干细胞因子（SCF）-干细胞因子受体（cKit）通路对糖尿病状态大鼠骨髓间充质干细胞（BMSCs）成骨功能的影响。方法 分离糖尿病大鼠BMSCs,免疫细胞化学染色鉴定后,将细胞分为空白对照组、阴性对照组、RNA干扰组,并用免疫印迹实验检测干扰效果。体外模拟糖尿病状态下诱导BMSCs成骨分化,并检测Lnk/SCF-cKit通路主要蛋白Lnk、SCF、cKit及成骨相关蛋白碱性磷酸酶（ALP）、骨钙素（OCN）、Ⅰ型胶原蛋白a1（ColⅠa1）的表达。结果 分离培养的细胞表达CD₄₄、CD₉₀,不表达CD_11b、CD₄₅,符合BMSCs表面标记物特征。与其他糖尿病状态BMSCs相比,RNA干扰组Lnk表达降低,SCF、cKit表达增加（P<0.05）。成骨诱导分化28 d,与其他糖尿病状态BMSCs相比,RNA干扰组细胞Lnk表达降低,SCF、cKit、ALP、OCN、ColⅠa1表达增加（P<0.05）。结论 抑制Lnk表达、激活SCF-cKit通路可改善糖尿病状态大鼠BMSCs的成骨功能。