中低强度运动干预高脂饲养小鼠膝关节损伤软骨细胞LncRNA HOTAIR的表达

Medium to low intensity exercise interferes with the expression of LncRNA HOTAIR in chondrocytes in high-fat-fed mice with knee joint damage

背景:中低强度有氧运动对膝关节软骨具有一定保护作用。长链非编码RNA对基因调节具有重要作用,其中,HOTAIR可以动员多个转录共同抑制因子,抑制某些基因表达。目的:检测HOTAIR及相关因子在高脂饲养小鼠及中低强度运动干预后膝关节软骨细胞中表达水平,探讨其在软骨损伤及运动康复中的作用。方法:C57BL/6雄性小鼠30只,随机分为对照组(正常饲养)、高脂静养组和高脂运动组,每组10只。高脂运动组进行8周中低强度跑台运动,对照组和高脂静养组笼中饲养,期间每周日称体质量。8周跑台结束后取材双下肢,采用Micro CT扫描膝关节,股骨髁成3D图像,获取相关参数;膝关节苏木精-伊红和番红固绿染色进行关节Mankin和OARSI评分;RT-PCR检测相关软骨代谢指标Ⅱ型胶原、基质金属蛋白酶13、白细胞介素1,脂代谢指标低密度脂蛋白受体相关蛋白5(LRP5),HOTAIR及其下游因子赖氨酸特异性去甲基化酶1(LSD1)mRNA表达。结果与结论:①高脂静养组和高脂运动组体质量均高于对照组(P<0.01),高脂运动组体质量低于高脂静养组(P<0.05);②高脂静养组和高脂运动组骨小梁连接密度均高于对照组(P<0.01);③高脂静养组Mankin和OARSI评分高于对照组(P<0.01)和高脂运动组(P<0.05);④对照组Ⅱ型胶原mRNA表达高于高脂运动组(P<0.05)和高脂静养组(P<0.01),高脂运动组Ⅱ型胶原mRNA表达高于高脂静养组(P<0.01);⑤高脂静养组基质金属蛋白酶13、白细胞介素1、低密度脂蛋白受体相关蛋白5、HOTAIR和赖氨酸特异性去甲基化酶1 mRNA表达高于对照组和高脂运动组(P<0.01);⑥结论:高脂饲养造成小鼠股骨髁骨质增加、膝关节软骨磨损,软骨细胞代谢紊乱,这一过程中HOTAIR的表达增加。8周中低强度跑台可减轻小鼠体质量、减缓膝关节软骨磨损、改善软骨细胞功能和下调HOTAIR表达。

BACKGROUND:Low to moderate intensity aerobic exercise can help protect knee cartilage.Long-chain non-coding RNAs are crucial for gene regulation.Among them,HOTAIR can activate numerous transcriptional co-repressors to repress the activation of certain genes.OBJECTIVE:To detect the expression levels of HOX transcript antisense RNA(HOTAIR)and other related factors in chondrocytes of high fat-fed mice and after low to moderate intensity exercise intervention,and to investigate their role in cartilage injury and sports rehabilitation.METHODS:Thirty C57BL/6 male mice were randomly divided into control group(normal feeding),high fat feeding group and high fat feeding plus treadmill exercise group,with 10 mice in each group.The mice in the high fat feeding plus treadmill exercise group were subjected to an 8-week low to middle intensity treadmill exercise,and the mice in the other two groups were caged.During this period,body mass was weighed every week on Sunday.After the 8-week exercise,both lower extremities of mice were taken,and the knee joint was scanned using Micro CT to make a 3D femoral condyle image to obtain relevant parameters.Hematoxylin-eosin and safranin O-fast green staining of the knee joint were performed for Mankin and Osteoarthritis Research Society International(OARSI)scoring.RT-PCR was performed to detect the mRNA levels of cartilage metabolic indicators and lipid metabolism indicators,including type II collagen,matrix metalloproteinase 13,interleukin 1,low-density lipoprotein receptor-related protein 5,HOTAIR and its downstream factor lysine specific demethylase 1.RESULTS AND CONCLUSION:The body mass of high fat-fed mice were higher than that of the control group(P<0.01),and the body mass of the high fat feeding plus treadmill exercise group was lower than that of the high fat feeding group(P<0.05).The connectivity density of high fat-fed mice was higher than that of the control group(P<0.01).Mankin and OARSI scores of the high fat feeding were higher than those of the control group(P<0.01)and high fat feeding plus treadmill exercise group(P<0.05).The mRNA level of type II collagen was higher in the control group than the high fat feeding plus treadmill exercise group(P<0.05)and high fat feeding group(P<0.01)as well as higher in the high fat feeding plus treadmill exercise group than the high fat feeding group(P<0.01).The mRNA levels of matrix metalloproteinase 13,interleukin 1,low-density lipoprotein receptor-related protein 5,HOTAIR and lysine specific demethylase 1 were higher in the high fat feed group than the control group and high fat feeding plus treadmill exercise group(P<0.01).To conclude,high fat feeding can increase the bone substance of the femoral condyle,lead to knee cartilage wear,and cause chondrocyte metabolism disorder.HOTAIR is highly expressed in this process.An 8-week low to middle intensity treadmill exercise can reduce body mass,alleviate knee cartilage wear,improve chondrocyte function and down-regulate HOTAIR expression in mice.