小胶质细胞活化诱导少突胶质前体细胞Tau蛋白变化在HIBD后髓鞘形成障碍中的作用机制

Neonatal hypoxic ischemic brain damage (hypoxia - ischemia brain damage, HIBD) is a serious disease that could threat to life in neonatal babies，and survivors are often concerned by long-term sequels like aphasia and functional relevant limb paresis, caused by hypomyelination, resulting in an enormous personal and socio-economic burden. Furthermore, with the opening up of the Two-Child policy in China, the elder women were faced high risk of pregnancy, and this will greatly increase the numbers of pathological obstetrics. Therefore, the in-depth study of HIBD mechanism is more and more attention to this. Oligodendrocytes are the main cells for myelination, they are extremely vulnerable to damage then become dysfunction. However, the mechanism focus on microglia and oligodendrocyte in such ischemia damage of myelination dysfunction is limited. Our previous studies suggested that the value of fraction anisotropy reduced after HIBD, the pathological expression of tau protein induced by HIBD also changed and has positive correlation with myelin basic protein, but the directly relationship and its possible mechanisms between tau pathological phosphorylation and oligodendrocyte are not clear. In this study, we choose the activation of MC as the breakthrough point, focus on OPCs differentiation and migration process to discuss those change after HIBD induced by MC activation. By using immune magnetic beads direct extraction activated MC and OPCs in HIBD animal model, then co-cultivation with MC and OPCs to analyse the change of proliferation and migration in OPCs, we also using in utero electrical transduction cell transfection technique, laser confocal technique, Western blotting technique to observe the role of F - actin and tau protein phosphorylation in OLs differentiation and migration, and then to discuss the mechenism of MC activation during in OPCs maturation and remyelination, and the role of tau in these process, it will provide OPCs as a new basis to elucidate the mechanism of demyelination induced by HIBD.

新生儿缺氧缺血性脑损伤（HIBD）是威胁新生儿生命及致神经后遗症的严重疾病。随着我国二胎政策的开放，高龄孕妇妊娠风险增大，病理产科数量增加，由此导致HIBD患儿潜在风险亦增加。少突胶质前体细胞（OPCs）为中枢神经系统形成髓鞘的主要细胞，其较易受损而导致功能障碍。然而，在髓鞘形成异常的研究中，活化的小胶质细胞（MC）对少突胶质前体细胞的影响知之甚少。我们的前期研究提示，HIBD后髓鞘方向性降低、tau蛋白病理性表达增加，但具体机制不清。本项目以MC活化为切入点，着眼于OPCs的分化、迁移过程，重点研究HIBD后MC活化对此过程的影响。拟采用免疫磁珠提取MC和OPCs共培养，并结合宫内电转导细胞转染、激光共聚焦、Western blotting等技术，研究MC活化对OPCs分化、髓鞘形成的影响和tau及其磷酸化蛋白在其中的作用，为髓鞘化障碍的治疗提供新思路。

新生儿缺氧缺血性脑损伤（HIBD）是威胁新生儿生命及致神经后遗症的严重疾病。随着我国二胎政策的开放，高龄孕妇妊娠风险增大，病理产科数量增加，由此导致HIBD患儿潜在风险亦增加。目前的研究支持，髓鞘化障碍是导致HIBD患儿远期行为异常的核心机制之一。少突胶质细胞为中枢神经系统髓鞘形成的主要细胞，其较易受损而导致功能障碍。然而，在髓鞘形成异常的研究中，活化的小胶质细胞对少突胶质细胞的影响知之甚少。Tau蛋白是微管结合蛋白家族中的一种细胞骨架蛋白，其主要功能除了调节、维持微管稳定性、辅助神经元轴突的运输功能外，近年研究发现其也可参与髓鞘化过程。我们的前期研究提示，HIBD后髓鞘方向性降低、Tau蛋白病理性表达增加，但具体机制不清。在本项目中，通过复制新生小鼠HIBD动物模型，我们观察到，HIBD后小鼠髓鞘形成异常、行为学和学习记忆功能出现障碍；免疫荧光和蛋白印迹技术发现HIBD后不仅小胶质细胞形态出现阿米巴样改变、数量增加，少突胶质细胞数量也出现反应性增生，且活化的小胶质细胞吞噬少突胶质细胞数量增多，这些结果提示HIBD后小胶质细胞参与了少突胶质细胞髓鞘形成。进一步研究发现，HIBD后可见Tau及其磷酸化蛋白主要表达于胼胝体区少突胶质细胞，表明少突胶质细胞Tau蛋白参与了HIBD后髓鞘形成异常。