[小鼠载脂蛋白E基因敲除（ApoE-/-）模型中的骨量变化及其可能机制]

[Bone mass change and its possible mechanisms in murine knockout apolipoprotein E(ApoE-/-)].

作者信息

Wang Min, Li Xian-ping, Zhao Li-ling, Liao Er-yuan, Luo Xiang-hang

机构信息

Department of Clinical Laboratory, Second Xiangya Hospital of Central South University, Changsha, China.

出版信息

Zhonghua Yi Xue Za Zhi. 2009 Nov 17;89(42):2963-7.

PMID:20137704

Abstract

OBJECTIVE

To study bone mass changes and its mechanisms in murine knockout apolipoprotein E (ApoE-/-).

METHODS

Both 28-week-old male ApoE-/- mice (n = 6) and wild-type (WT) mice (n = 10) were euthanized. The trabecular and cortical bone microarchitecture were assessed by micro-CT (microCT) in right distal femur. The total body BMD (bone mineral density) of left femur was determined by dual-energy X-ray absorptiometry (DXA). The serum concentrations of osteoprotegerin (OPG) and receptor activator of nuclear factor kappaB ligand (RANKL) were analyzed using enzyme-linked immunosorbent assay (ELISA). The left tibias were dissected and fixed in 4% paraformaldehyde after decalcified in 0.15M EDTA buffer for 30 days. And the expressions of OPG and RANKL were detected by immunohistochemical staining.

RESULTS

Compared with WT mice, the ApoE-/- mice showed an increased volumetric BMD (294 +/- 38) mg/mm(3), tissue BMD (627 +/- 23) mg/mm(3), BMC (bone mineral content) (0.57 +/- 0.08) mg, bone volume fraction (20.38 +/- 4.74)%, trabecular number (6.67 +/- 0.78) mm(-1), trabecular thickness (0.03 +/- 0.01) mm with an decreased bone surface fraction (69 +/- 18) mm(-1), trabecular separation (0.12 +/- 0.01) and structure mode index (1.73 +/- 0.24). The total body BMD was higher in ApoE-/- mice than WT mice [(0.063 +/- 0.004) g/cm(2) vs (0.056 +/- 0.004) g/cm(2)]. The serum level of OPG was significantly higher in ApoE-/- mice than WT mice [(4.98 +/- 0.97) ng/ml vs (3.54 +/- 0.65) ng/ml]. The results of immunohistochemical staining showed that the OPG expression was at a higher level in bone cell of ApoE-/- mice and RANKL showed no obvious change in either sera or bone cells.

CONCLUSION

A decreased bone resorption causes an increased bone mass in ApoE-/- mice and leads to an imbalanced ratio of OPG/ RANKL.

摘要

目的

研究小鼠载脂蛋白E基因敲除（ApoE-/-）模型的骨量变化及其机制。

方法

对28周龄雄性ApoE-/-小鼠（n = 6）和野生型（WT）小鼠（n = 10）实施安乐死。采用显微CT（microCT）评估右侧股骨远端的小梁骨和皮质骨微结构。使用双能X线吸收法（DXA）测定左侧股骨的全身骨密度（BMD）。采用酶联免疫吸附测定（ELISA）分析血清骨保护素（OPG）和核因子κB受体活化因子配体（RANKL）的浓度。解剖左侧胫骨，在0.15M EDTA缓冲液中脱钙30天后，用4%多聚甲醛固定。通过免疫组织化学染色检测OPG和RANKL的表达。

结果

与WT小鼠相比，ApoE-/-小鼠的骨体积密度（294±38）mg/mm³、组织骨密度（627±23）mg/mm³、骨矿物质含量（BMC）（0.57±0.08）mg、骨体积分数（20.38±4.74）%、小梁数量（6.67±0.78）mm⁻¹、小梁厚度（0.03±0.01）mm增加，而骨表面分数（69±18）mm⁻¹、小梁间距（0.12±0.01）和结构模式指数（1.73±0.24）降低。ApoE-/-小鼠的全身骨密度高于WT小鼠[（0.063±0.004）g/cm²对（0.056±0.004）g/cm²]。ApoE-/-小鼠血清中OPG水平显著高于WT小鼠[（4.98±0.97）ng/ml对（3.54±0.65）ng/ml]。免疫组织化学染色结果显示，ApoE-/-小鼠骨细胞中OPG表达水平较高，而血清和骨细胞中的RANKL均无明显变化。