肝X受体α在小胶质细胞激活致神经元损伤中的作用研究

Role of liver X receptor α in neuronal damage induced by microglia activation

[目的]研究肝X受体alpha(LXRα)在小胶质细胞激活致神经元损伤中的作用.[方法]小鼠小胶质细胞株(BV2细胞)置于6孔培养板培养,分为对照组、Aβ组、干扰组、干扰+Aβ组、假干扰+Aβ组.应用倒置显微镜观察各组BV2细胞的形态学变化,Western blot方法检测LXRα蛋白表达变化,ELISA检测各组上清液中COX-2、iNOS的表达水平.收取BV2细胞上清液作为条件培养基用来培养人神经母细胞瘤细胞(SH-SY5Y细胞),并通过CCK-8和免疫荧光法检测SH-SY5Y细胞的存活率和凋亡蛋白Bax表达情况.[结果]与对照组相比,Aβ组及干扰组的BV2细胞表现为胞体变圆变大,细胞突起减少,呈阿米巴样活化状态,LXRα蛋白水平明显下调(P<0.05),细胞上清液COX-2,iNOS的表达含量明显升高(P<0.05),Aβ处理组和干扰组的细胞上清液明显引起SH-SY5Y细胞存活率降低、凋亡蛋白Bax表达增加(P<0.05).与假干扰+Aβ组相比,干扰+Aβ组的细胞胞体变大,突起减少,LXRα蛋白表达减少,COX-2,iNOS的表达增加,干扰+Aβ组的细胞上清液导致SH-SY5Y细胞存活率降低,Bax表达增加(P<0.05).[结论]LXRα参与调控Aβ诱导的小胶质细胞激活及炎症因子的释放,在AD的炎症机制中发挥重要作用.

[Objective]To study the role of LXRαin neuronal damage induced by microglia activation.[Methods]BV2 mouse microglial cell line was cultured in six hole culture plate.LXRα was knocked down by transfection of LXRα-siRNA and stimulated by Aβ25-35 for 4 hours.BV2 cells were divided into the following groups,control group:Aβ group,siRNA group,siRNA+Aβ group and sham siRNA+Aβ group.The morphological changes of BV2 cells in each group were observed by inverted microscope,the expression of LXRαprotein in BV2 cells in each group was detected by Western blot,and the expression of COX-2 and iNOS in supernatant of each group was detected by ELISA.The supernatant of BV2 cells was used as conditioned medium to culture SH-SY5Y cells,and the survival rate and expression of Bax were detected by CCK-8 and immunofluorescence.[Results]Compared with the control group,BV2 cells in the Aβ group and the siRNA group showed round and large cell bodies,reduced cell processes and amebic activation,LXRα protein level decreased significantly(P<0.05),the expression of COX-2 and iNOS in supernatant increased significantly(P<0.05),and the supernatant of Aβ treated group and siRNA group significantly reduced the survival rate of SH-SY5Y cells and increased the expression of apoptosis protein Bax.Compared with sham siRNA+Aβ group,the cell body of siRNA+Aβgroup became larger,protuberance decreased,LXRα protein expression decreased,COX-2,iNOS expression increased,and the supernatant of siRNA+Aβ group resulted in the decrease of SH-SY5Y cell survival rate and the increase of Bax expression.[Conclusion]LXRαis involved in the regulation of Aβ25-35-induced release of microglial inflammatory factors and plays an important role in the inflammatory mechanism of AD.