LncRNA MEG3靶向调节miR-17-5p对缺氧缺血性脑损伤新生小鼠血-脑屏障的影响

Effect of LncRNA MEG3 on blood⁃brain barrier in neonatal mice with hypoxic⁃ischemic brain injury by targeting miR⁃17⁃5p

目的探讨LncRNA MEG3通过调节miR-17-5p对缺氧缺血性脑损伤(HIBD)新生小鼠血-脑屏障的影响。方法90只C57BL小鼠按照随机数字表法分为对照组、模型组、si-NC组、si-LncRNA MEG3组、si-LncRNA MEG3+anti-miR-NC组、si-LncRNA MEG3+anti-miR-17-5p组,每组15只。除对照组外,其余组小鼠构建HIBD模型,并采用Longa评分评估小鼠神经损伤情况;电镜观察脑组织周围血管内皮细胞超微结构;EB法测定小鼠血-脑屏障通透性;qRT-PCR法测定各组小鼠脑组织LncRNA MEG3、miR-17-5p水平;Western blotting法测定小鼠脑组织ZO-1、Occludin蛋白水平。结果与对照组相比,模型组小鼠血管内皮薄厚不均、多处呈现水肿状态;与模型组相比,si-LncRNA MEG3组小鼠血管内皮细胞逐渐连接紧密、薄厚较为均匀,水肿减少;与si-LncRNA MEG3组相比,si-LncRNA MEG3+anti-miR-17-5p组血管内皮细胞损伤加剧。与对照组相比,模型组小鼠神经功能缺损评分、脑含水量、EB含量、LncRNA MEG3水平显著升高,miR-17-5p水平、ZO-1及Occludin蛋白表达显著降低(均P<0.05)。与模型组相比,si-NC组小鼠神经功能缺损评分、脑含水量、EB含量、LncRNA MEG3水平、miR-17-5p水平、ZO-1及Occludin蛋白表达差异无统计学意义(均P>0.05),si-LncRNA MEG3组小鼠神经功能缺损评分、脑含水量、EB含量、LncRNA MEG3水平显著降低,miR-17-5p水平、ZO-1及Occludin蛋白表达显著升高(均P<0.05)。与si-LncRNA MEG3组相比,si-LncRNA MEG3+anti-miR-NC组小鼠神经功能缺损评分、脑含水量、EB含量、LncRNA MEG3水平、miR-17-5p水平、ZO-1及Occludin蛋白表达差异无统计学意义(均P>0.05),si-LncRNA MEG3+anti-miR-17-5p组小鼠神经功能缺损评分、脑含水量、EB含量显著升高,miR-17-5p水平、ZO-1及Occludin蛋白表达显著降低(均P<0.05)。结论LncRNA MEG3沉默可能通过上调miR-17-5p,降低HIBD新生小鼠血-脑屏障通透性,维持血-脑屏障对大脑的保护作用,保护脑组织。

Objective To analyze the effect of LncRNA MEG3 on the blood⁃brain barrier in neonatal mice with hypoxic⁃ischemic brain injury(HIBD)by regulating miR⁃17⁃5p.Methods A total of 90 C57BL mice were randomly grouped into control group,model group,si⁃NC group,si⁃LncRNA MEG3 group,si⁃LncRNA MEG3+anti⁃miR⁃NC group and si⁃LncRNA MEG3+anti⁃miR⁃17⁃5p group,with 15 mice in each group.Except for the control group,the rest of the mice were constructed with HIBD model,and the Longa score was used to evaluate the nerve damage of mice.The ultrastructure of vascular endothelial cells around brain tissue was observed by electron microscope.The permeability of blood⁃brain barrier in mice was measured by EB method.The levels of LncRNA MEG3 and miR⁃17⁃5p in the brain tissue of mice in each group were determined by qRT⁃PCR.The levels of ZO⁃1 and Occludin protein in the brain tissue of mice were determined by Western blotting.Results Compared with control group,the vascular endothelium of mice in model group was unevenly thin and thick,and showed edema in many places.Compared with model group,the vascular endothelial cells in the si⁃LncRNA MEG3 group were gradually tightly connected,the thickness was more uniform,and the edema was reduced.Compared with the si⁃LncRNA MEG3 group,vascular endothelial cell damage was intensified in the si⁃LncRNA MEG3+anti⁃miR⁃17⁃5p group.Compared with those in the control group,the neurological deficit score,brain water content,EB content,and LncRNA MEG 3 level in the model group were significantly increased,miR⁃17⁃5 p level,ZO⁃1 and Occludin expression were significantly decreased(all P<0.05).Compared with those in model group,there were no significant differences in neural function deficit score,brain water content,EB content,lncRNA MEG3 level,miR⁃17⁃5p level,ZO⁃1 and Occludin expression in si⁃NC group(all P>0.05);the neurological deficit score,brain water content,EB content and LncRNA MEG3 level in si⁃LncRNA MEG3 group were significantly decreased,miR⁃17⁃5p level,ZO⁃1,and Occludin expression were significantly increased(all P<0.05).Compared with those in si⁃LncRNA MEG3 group,there were no significant differences in neural function deficit score,brain water content,EB content,LncRNA MEG3 level,miR⁃17⁃5p level,ZO⁃1 and Occludin expression in si⁃LncRNA MEG3+anti⁃miR⁃NC group(all P>0.05);the neurological deficit score,brain water content and EB content in si⁃LncRNA MEG3+anti⁃miR⁃17⁃5p group were significantly increased,miR⁃17⁃5p level,ZO⁃1 and Occludin expression were significantly decreased(all P<0.05).Conclusion LncRNA MEG3 silencing may reduce the permeability of the blood⁃brain barrier in neonatal mice with HIBD by up⁃regulating miR⁃17⁃5p,maintaining the protective effect of the blood⁃brain barrier on the brain,and protecting brain tissue.