依降钙素干预膝骨关节炎模型大鼠软骨下骨的变化

文题释义： 依降钙素：为人工合成的鳗鱼降钙素多肽衍生物，其主要作用是抑制破骨细胞活性，减少骨的吸收，防止骨钙丢失，同时可降低正常动物和高钙血症动物血清钙，对实验性骨质疏松有改善骨强度、骨皮质厚度、骨钙质含量、骨密度等作用。 p38丝裂原活化蛋白激酶(p38 MAPK)：p38 MAPK是MAPK亚族中的一员，它以转录因子为作用目标，通过对转录因子的磷酸化来调节许多转录因子的活性，进而介导炎症反应和细胞凋亡，参与体内细胞的应激反应。研究认为p38 MAPK是调节膝关节骨关节炎发病机制中炎症产生的关键上游信号，影响骨关节炎的发生与发展，是近年来研究的热点。 背景：骨关节炎存在软骨下骨吸收和骨形成失去平衡，课题组前期研究发现膝骨关节炎大鼠关节软骨改变前软骨下骨就已经发生改变。 目的：通过观察膝骨关节炎大鼠膝关节软骨下骨的变化，探讨依降钙素对软骨下骨p38 MAPK表达及软骨下骨吸收的影响。 方法：雌性3月龄SD大鼠随机分为3组：假手术组(n=6)不切除卵巢，切除同卵巢等体积大小的脂肪组织，切开双侧膝关节，但不损伤交叉韧带；模型组(n=6)切除双侧卵巢后，再切断双侧膝关节前交叉韧带，建立卵巢切除+前交叉韧带切断模型，不进行药物干预；依降钙素组(n=6)建立卵巢切除+前交叉韧带切断模型后，依降钙素5 IU/kg，每周2次肌肉注射。12周后分析软骨下骨的骨密度、软骨下骨p38蛋白表达水平以及血清Ⅰ型胶原交联C-末端肽、Ⅱ型胶原交联C-末端肽、白细胞介素1、白细胞介素6、骨特异性碱性磷酸酶、抗酒石酸酸性磷酸酶5b水平。实验方案经南华大学动物实验伦理委员会批准。 结果与结论：①依降钙素组软骨下骨的骨体积分数、骨小梁数量显著高于模型组(P < 0.05)，骨小梁分离度显著低于模型组(P < 0.05)；②模型组的骨体积分数、骨小梁数量、骨小梁厚度显著低于假手术组(P < 0.01或< 0.05)、骨小梁分离度显著高于假手术组(P < 0.01)；③依降钙素组血清Ⅰ型胶原交联C-末端肽、白细胞介素1、白细胞介素6、抗酒石酸酸性磷酸酶5b显著低于模型组(P < 0.05)，模型组Ⅰ型胶原交联C-末端肽、Ⅱ型胶原交联C-末端肽、白细胞介素1、白细胞介素6、抗酒石酸酸性磷酸酶5b明显高于假手术组(P < 0.05)；④软骨下骨p38蛋白表达水平依降钙素组显著低于模型组(P < 0.01)、模型组显著高于假手术组(P < 0.01)；⑤结果说明，依降钙素可能通过下调p38 MAPK表达，抑制骨关节炎促炎因子分泌及软骨下骨吸收。 ORCID: 0000-0002-2108-9820(伍琦) 中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

Changes of subchondral bone in rat models of knee osteoarthritis treated by elcatonin

BACKGROUND:Imbalance between subchondral bone resorption and bone formation occurs in osteoarthritis.Our preliminary study has found that the subchondral bone changes precede the articular cartilage changes in knee osteoarthritis rats.OBJECTIVE:To observe the changes of subchondral bone in knee osteoarthritis rats,and to explore the effect of elcatonin on the expression of p38 MAPK and absorption of subchondral bone.METHODS:Female Sprague-Dawley rats,3 months of age,were randomly divided into three groups:sham operation group(n=6,the adipose tissue of the same size as the ovary was removed without ovariectomy,the bilateral knee joints were opened,but without cruciate ligament injury);model group(n=6,bilateral ovariectomy plus bilateral cruciate ligament injury,no treatment);elcatonin group(n=6,ovariectomy plus cruciate ligament injury,intramuscular injection of 5 IU/kg elcatonin,twice weekly).The bone mineral density and p38 protein expression levels in subchondral bone were detected at 12 weeks.The serum levels of C-terminal crosslinking telopeptides of type I collagen,C-terminal crosslinking telopeptides of type Ⅱ collagen,interleukin-1,interleukin-6 and bone-specific alkaline phosphatase,tartrate resistant acid phosphatase 5 b were detected.RESULTS AND CONCLUSION:(1) The bone volume fraction and trabecular bone number in the elcatonin group were significantly higher than those in the model group(P <0.05),and the trabecular separation in the elcatonin group was lower than that in the model group(P <0.05).(2) The bone volume fraction,trabecular bone number and trabecular thickness in the model group were lower than those in the sham operation group(P<0.01 or P<0.05),and the trabecular separation was higher than that in the sham operation group(P<0.01).(3) The serum levels of C-terminal crosslinking telopeptides of type I collagen,C-terminal crosslinking telopeptides of type Ⅱ collagen,interleukin-1,interleukin-6 and tartrate resistant acid phosphatase 5 b in the elcatonin group was significantly lower than those the model group(P<0.05),and the above levels in the model group were significantly higher than those in the sham operation group(P<0.05).(4) The p38 expression level in subchondral bone in the elcatonin group was significantly lower than that in the model group(P<0.01),and the level in the model group was significantly higher than that in the sham operation group(P<0.01).(5) These results indicate that elcatonin may inhibit the secretion of osteoarthritis pro-inflammatory factors and subchondral bone resorption by down-regulating the expression level of p38 MAPK.