膜粘连蛋白Ⅱ通过保护血脑屏障促进小鼠颅脑创伤后早期神经功能的恢复

目的 评估外源性重组膜粘连蛋白Ⅱ(annexin 2,A2)对创伤性颅脑损伤后血脑屏障以及早期神经功能预后的影响,探讨A2蛋白作为脑创伤治疗靶点的可能性.方法 在成年雄性小鼠上建立控制性皮质损伤模型(controlled cortical impact,CCI),检测伤前与伤后不同时间点伤侧半球脑组织中内源性A2蛋白的表达.随后,小鼠CCI伤后通过尾静脉注射重组人源性A2蛋白,并检测血脑屏障通透性、大脑半球组织含水量、紧密连接蛋白表达量、海马区神经元数量、伤灶体积及早期行为学改变.结果 从CCI后3d起,A2蛋白表达明显增高,并在7d时达到高峰(P＜0.05),此后蛋白表达逐渐下降,21 d恢复到基值;伤前内皮细胞几乎不表达A2蛋白,伤后在伤侧部分内皮细胞表达A2蛋白.在伤后2h给予重组A2蛋白能显著降低血脑屏障通透性从而降低脑组织中Evans蓝(Evans blue,EB)渗出量(P＜0.05),增加ZO-1蛋白表达(P＜0.05),减少伤后CA1和CA3区神经元丢失,CA1区和CA3区平均神经元存活数量分别为159.5和131,6,均显著高于对照组(P＜0.05),并促进伤后7d内运动功能康复(P＜0.05).能够减少致伤后脑组织含水量,但不具有统计学差异(P＞0.05),两组间伤灶体积也无统计学差异(P＞0.05).结论 在创伤性颅脑损伤早期,给予重组人A2蛋白能提高内皮细胞ZO-1合成,保护血脑屏障,减轻神经组织继发性损伤,促进伤后神经功能恢复.

Recombinant annexin A2 improves early neurological function through blood-brain barrier protection in mice after controlled cortical impact

Objective To determine the effect of exogenous annexin A2 (A2) on the permeability of blood-brain barrier (BBB) and early neurological prognosis following traumatic brain injury (TBI) in order to investigate the possibility of A2 as the target for brain traumatic treatment.Methods After the controlled cortical impact (CCI)model was established on adult male mice,the temporal and spatial profile of endogenous A2 protein expression in injured hemisphere was examined before and after TBI.Evans blue extravasation,water content,expression of tight junctional proteins were quantified to evaluate the BBB function after the mice were treated with recombinant-human A2 (rA2,1 mg/kg,tail vein injection) or saline in 2 h post-CCI.Then neuron counts,lesion size and behavior tests were performed to investigate the neuroprotective effects of rA2.Results After CCI,endogenous A2 expression was increased since day 3,reached the summit at day 7 (P ＜ 0.05),and then was decreased till day 21 to baseline level.A2 was not expressed in the endothelial cells before CCI,but was expressed in the some endothelial cells in injured hemisphere.rA2 treatment significantly reduced the BBB permeability and thus decreased the amount of evans blue extravasation (P ＜ 0.05),enhanced the ZO-1 expression (P ＜ 0.05),reduced neuronal loss in hippocampal areas CA1 and CA3,with the numbers of survival neurons of 159.5 and 134.6 respectively,significantly high than those in the control (P ＜ 0.05),improved the rehabilitation of motor function within 7 d after injury,and decreased water content and lesion volume,though having no statistical differences when compared with the control (P ＞ 0.05).Conclusion In the early stage after TBI,rA2 treatment can improve the synthesis of ZO-1,protect BBB,attenuate secondary brain injury,and contribute neuronal functional recovery.