CD24在蛛网膜下腔出血后神经修复中的作用机制研究

Neuronal repair is a key regulator of prognosis in patients with subarachnoid hemorrhage (SAH), however, the specific mechanisms have not been well elucidated. We previously found that cortical CD24 could be elevated following SAH. Meanwhile, we occasionally found that CD24 was upregulated not only in glial cells but also in neurons. Accordingly, we speculated that CD24 might play an important role in some others fields as well as in inflammatory response. Therefore, we performed our pre-experiments and found that CD24 was upregulated much earlier in neurogenesis areas (hippocampal dentate gyrus and subventricular zone) than that in temporal cortex. Based on the related research in the world, we raised a hypothesis that the neurogenesis could be activated after SAH, and neural stem cells had an increased proliferation, differentiation and immigration. CD24, as a marker of these cells, could be elevated in the brain, thus contributing to the neuronal repair following SAH. In this study, we are planning to apply RNA interference and gene overexpression aiming at CD24 to investigate the mechanisms of CD24 in neuronal repair following SAH, which will be validated through neuronal regenerative pattern both in vivo and in vitro. From this research, we expect to better understand the specific pattern and mechanisms of neuronal repair after SAH, thereby providing a novel therapeutic target for SAH.

蛛网膜下腔出血（SAH）后神经修复是影响患者预后的重要因素，但其具体机制仍不明确。我们研究发现：SAH后颞叶皮层负向调控炎性反应的CD24表达增高，同时发现除胶质细胞外，神经元中CD24也明显上调。我们推测CD24在SAH后可能不只是参与调控炎性反应，同时具有其他重要功能。对此，我们预实验发现SAH后神经发生区域（海马齿状回和室管膜下区）内CD24同样被上调，且表达时相明显早于颞叶皮层。结合国际相关研究，我们提出假说：SAH后脑内神经发生区域中的神经干细胞发生增殖、分化和迁移，而CD24作为其潜在标志物可在脑内各区域全面上调，最终在神经修复中发挥重要作用。本课题拟通过体内、体外实验，针对CD24运用RNA干扰及基因过表达技术，立足神经再生模式，探讨CD24在SAH后神经修复中的作用机制。通过此项研究，将有助于深入理解SAH后神经修复的具体模式与机制，为SAH临床治疗与康复提供新的靶点。

蛛网膜下腔出血（SAH）是一种严重的出血性卒中，具有高死亡率、高致残率、高伤残调整寿命年以及高社会负担的四高特点，被称为“中壮年杀手”。SAH后神经修复是影响患者预后的重要因素，但其具体模式仍不清楚。CD24是一种潜在的干细胞标志物，发挥着促进组织修复的重要作用。在神经系统中，CD24对细胞迁移、轴突生长、突触成成熟、髓鞘形成及损伤后修复都非常重要。.课题组通过构建大鼠SAH模型，发现SAH后脑内CD24表达明显增高，免疫荧光定位分析显示神经元中CD24上调尤为明显；采用慢病毒技术干预大鼠脑内CD24表达后，SAH大鼠海马区域DCX（未成熟神经元标记物）阳性细胞的数量显著减少，提示其参与神经元再生过程。同时，大鼠SAH模型中CD24的下调可显著抑制细胞内SHP2的磷酸化水平，表明SAH 后CD24的高表达可能通过促进SHP2的磷酸化从而增强神经再生过程。.体外实验采用氧合血红蛋白分别刺激原代神经元及星形胶质细胞模拟SAH，刺激后能够显著增加细胞中CD24的mRNA与蛋白表达水平，结果与体内实验相一致。并且CD24的下调可显著抑制星形胶质细胞的活化以及SHP-2、ERK蛋白的磷酸化，表明CD24参与SAH后神经修复的过程可能与SHP-2/Erk信号通路密切相关。另外，在原代星形胶质细胞和海马神经元共培养的模型中，课题组发现氧合血红蛋白刺激可同时显著增加原代星形胶质细胞中CD24的表达；慢病毒下调星形胶质细胞内CD24的表达后，星形胶质细胞来源的脑神经营养因子BDNF下降，提示星形胶质细胞内的CD24可能是通过增加BDNF的释放来参与SAH后的神经元再生。.本研究进一步明确了SAH后神经元及星形胶质细胞中CD24的潜在功能，为SAH临床疗效的提升提供了新的思路和靶点。