Osteoprotegerin induces morphological and functional alterations in mouse pancreatic islets

Although serum osteoprotegerin (OPG) is significantly increased in diabetic subjects, its potential role in beta cell dysfunction has not been investigated. This study aimed to assess the effect of full-length OPG administered in vivo in mice on pancreatic islet structure and function and its interaction with the renin–angiotensin system (RAS).     

Effects of coumestrol on expression of bone markers during primary osteoblastic cells differentiation

目的 观察植物雌激素香豆雌酚对成骨细胞增殖分化的作用并探讨其作用机制.方法 从小鼠颅盖骨获得成骨细胞并用0,10-9～10-5 M香豆雌酚孵育48 h,以17β雌二醇为阳性对照,用酶消化法测定碱性磷酸酶及Ⅰ型胶原含量,放免法测定骨钙素含量,RT-PCR法测定OPG及RANKL mRNA表达情况,Western Blot测定OPG蛋白含量.结果 干预48 h,不同浓度香豆雌酚呈剂量依赖性增加碱性磷酸酶及Ⅰ型胶原含量,10-6 M时达到最大效应(P<0.05),但10-5 M效应有所降低,香豆雌酚轻度增加成骨细胞骨钙素含量,各组间无统计学差异.香豆雌酚呈剂量依赖性增加OPG基因及蛋白的表达(P<0.05),轻度降低RANKL基因的表达.结论 香豆雌酚能增加成骨细胞增殖及分化,可能其部分通过OPG/RANKL发挥作用.     

流体剪切力对MC3T3-E1细胞OPG、RANKL蛋白表达的实验研究

目的探讨流体剪切力(fluid shear stress,FSS)作用下,两种调节骨骼重建的重要分子骨保护素(osteoprotegerin,OPG)和细胞核因子κB受体活化因子配体(receptor activator of NF-κB ligand,RANKL)的蛋白表达情况。方法采用体外模型对MC3T3-E1细胞加载流体剪切力,细胞经不同时间加力后(0,30,60,90,120min),对细胞分别进行染色和裂解,运用免疫荧光和蛋白印迹法对OPG和RANKL的蛋白表达水平进行定量分析。结果 FSS作用30,60,90,120min后能够显著增加OPG的蛋白表达(P0.05),减少RANKL的蛋白表达(P0.05)。两者共同作用使得OPG/RANKL值显著增高(P0.05)。结论流体剪切力刺激提示OPG/RANKL的比值可能在成骨细胞和破骨细胞联合调节骨骼形成和吸收的过程中起着重要的调节作用。     

RANKL和OPG在不同骨移植材料拔牙位点保存区的表达

目的 通过观察破骨细胞核因子kB受体活化因子配体(receptor activator nuclear factor kappa B ligand,RANKL)和骨保护因子(osteoprotegerin,OPG)在不同骨移植材料拔牙位点保存时骨构建过程中表达变化,探讨破骨细胞对不同骨移植材料植入拔牙窝内在引导骨再生中的作用.方法 选取6只12月龄雄性beagle犬,微创拔除上下颌双侧第一侧切牙,将4个位点随机做不同处理,A组填人富血小板纤维蛋白(platelet-rich fibrin,PRF),B组填入骨诱导活性材料(osteoinduction active material,OAM),C组填入羟基磷灰石生物陶瓷(coralline hydroxyapatite,CHA),D组空置(对照).6只犬随机分别于术后4周和12周各处死3只,制作牙槽骨标本.免疫组化检测24个拔牙位点保存制作的犬牙槽骨标本中RANKL与OPG的表达变化.结果 术后4周骨组织中OPG的表达A组高于B组、C组和D组(P＜0.05),RANKL的表达D组高于C组、B组和A组(P＜0.05).术后12周骨组织中OPG的表达D组高于C组、B组和A组(P＜0.05),RANKL的表达C组高于B组、A组和D组(P＜0.05).结论 骨移植材料在骨改建过程中通过促进成骨细胞分化成熟而刺激OPG表达升高,抑制破骨细胞.提示骨移植材料通过调控RANKL和OPG在拔牙窝新骨形成过程中发挥作用.     

不同氧浓度对小鼠骨髓细胞形成破骨样细胞的影响

目的观察不同氧浓度对小鼠骨髓细胞形成破骨样细胞的影响,探讨低氧对破骨细胞生成影响的分子机制。方法取6～9周龄KM小鼠骨髓细胞,用含1α,25(OH)_2D_3(10~(-8)mol/L)、地塞米松(10~(-8)mol/L)和10%胎牛血清的α-MEM培养基分别在氧浓度为20%(常氧组)、6%、3%和1%(均为低氧组)条件下培养。骨髓细胞纯化后加入第3～5代成骨细胞进行共培养,根据培养时间分组,每组样本数为4,在缺氧第5天进行实验,每项实验重复3次。用Trizol提取细胞总RNA;用半定量反转录PCR(RT-PCR)检测OPG、RANK及RANKL mRNA的表达;用Western blotting检测RANK蛋白的表达。结果与常氧组相比,3个低氧组OPG mRNA的表达均随氧浓度的降低而降低,RANK mRNA和RANK蛋白表达随氧浓度的降低而升高,RANKL mRNA的表达随氧浓度的降低而升高。结论低氧可促进破骨样细胞的生成,氧浓度为3%时破骨细胞生成达高峰。     

Expression of receptor activator of NF‐κB ligand and osteoprotegerin in peripheral giant cell granulomas of the jaws

J Oral Pathol Med (2010) 39 : 687–689 Background: Peripheral giant cell granuloma is a tumor of the jaw characterized by the presence of multinucleated giant cells and mononuclear cells within a fibrous stroma. These lesions are considered to be of a reactive nature rather than neoplastic. Although peripheral giant cell granulomas is a well‐described clinical entity, little is known on its pathogenesis. The aim of this study was to investigate the receptor activator of NF‐κB ligand (RANKL) and osteoprotegerin (OPG) expression and immunolocalization in giant cell granulomas. Methods: RANKL and OPG protein expression was evaluated in 22 peripheral giant cell granulomas samples, by means of immunohistochemistry. Staining was evaluated semi‐quantitatively, according to the extent and intensity of the stain. Results: RANKL was expressed in all cases with a cytoplasmic staining pattern, whereas OPG expression was detected in 21 of the 22 cases examined. Active multinucleated giant cells exhibited intense immunoreactivity for both proteins. Conclusion: RANKL and OPG are expressed in peripheral giant cell granulomas of the jaw in a manner supporting the osteoclastic nature of giant cells whereas the possible osteoclastic lineage of stromal monocytes remains ambiguous.     

Immunohistochemical expression of RANKL, RANK, and OPG in human oral squamous cell carcinoma

Background:  The mechanism of oral squamous cell carcinoma (SCC) invading jawbone remains controversial. Interactions between receptor activator of NF-κB (RANK) and its ligand (RANKL) are required for osteoclastogenesis. The binding of RANK and RANKL induces differentiation of osteoclasts, leading to bony destruction. Osteoprotegerin (OPG), a decoy receptor for RANKL, also binds to RANKL by competing with RANK, and this could protect against osseous destruction.
Materials and methods:  Immunoexpression of RANKL, RANK, and OPG in 25 cases of human buccal SCCs without bony invasion and 15 cases of gingival SCCs with mandibular bony invasion was investigated. Normal oral mucosa from five individuals without betel-quid chewing or cigarette smoking was used as a control. The scores are designated as percentage of positive staining × intensity of staining for each section.
Results:  Strong cytoplasmic staining of RANKL proteins is detected in cancer cells of both buccal and gingival SCCs. The same protein is identified in cytoplasm of osteoclasts for all cases involving bony invasion. Strong cytoplasmic staining of RANKL is confined to basal layer for all normal mucosa. A similar staining pattern is noted for RANK protein in all buccal and gingival SCCs. An absence of staining of RANK protein is noted for all normal tissues. Weak to negative cytoplasmic stained OPG protein is present in all buccal and gingival SCCs, but is absent in all normal tissues.
Conclusion:  These findings suggest the potential value of the RANK/RANKL/OPG pathway as biomarkers in human oral SCCs.