组蛋白去乙酰化酶4在大鼠骨关节炎软骨退变中的变化趋势及作用

The change trend and role of HDAC4 in cartilage degeneration of rat OA model

目的 探讨组蛋白去乙酰化酶4(HDAC4)及其下游分子Runx-2在大鼠骨关节炎(osteoarthritis, OA)发生发展中的变化及对关节软骨退变的影响。方法 大鼠实验组肋软骨细胞添加10 ng/mL的IL-1β,对照组添加等体积的无菌PBS,48 h后行Western blot检测HDAC4和Runx-2的表达;构建ACLT大鼠OA模型,于术后2、4、8周通过番红固绿染色检测关节软骨退变情况,关节软骨损伤程度采用OARSI评分;同时,通过免疫组织化学染色和RT-qPCR检测HDAC4和Runx-2的表达量。结果体外OA模型中,和对照组比,HDAC4的表达降低,Runx-2的表达升高(P<0.05);大鼠前交叉韧带切断组,番红固绿染色显示,大鼠术后时间的增加伴随着膝软骨破坏程度的增加,OARSI评分升高(P<0.05);免疫组化可见,术后的时间不断增加,HDAC4的表达逐渐降低,而Runx-2的表达逐渐升高(P<0.05)。实时荧光定量PCR(RT-qPCR)显示,HDAC4 mRNA的表达随造模时间延长,其表达降低,而Runx-2 mRNA的表达逐渐升高(P<0.05)。结论 在OA发生和进展过程中,HDAC4含量的不断降低,而其下游Runx-2的表达逐渐增加,可能和OA关节软骨退变相关。

Objective To investigate the changes of HDAC4 and its downstream Runx-2 in the development of osteoarthritis(OA) in rats and their effects on articular cartilage degeneration. Methods Rat costal chondrocytes were cultured and divided into experimental group and control group. IL-1β with a final concentration of 10 ng/mL was added to the experimental group. The control group was added with sterile PBS. The expressions of HDAC4 and Runx-2 were detected with Western blotting 48 hours later. The OA model of anterior cruciate ligament transection in rats was established. The degeneration of articular cartilage was detected with Safranin O Fast green staining at 2, 4, and 8 weeks after operation. The articular cartilage injury was scored with OARSI. The expressions of HDAC4 and Runx-2 were detected using immunohistochemical staining and RT-qPCR. Results In the in vitro OA model, the HDAC4 expression decreased in experimental group, and the expression of Runx-2 increased(P<0.05). In rat ACLT OA model, Safranin O Fast green staining result showed that with extension of time after operation, the severity of cartilage degeneration increased and the OARSI score increased(P<0.05). Immunohistochemical staining result showed that with extension of time after operation, HDAC4 expression decreased gradually, and Runx-2 expression increased gradually(P<0.05). RT-qPCR result showed that the expression of HDAC4 mRNA decreased with extension of time after operation, while the Runx-2 mRNA expression increased gradually(P<0.05). Conclusion During the progression of OA, the decrease of HDAC4 and increase of Runx2 lead to the degeneration of OA cartilage.