VEGF-C/VEGFR-3信号通路在FCD少突胶质前体细胞成熟障碍中的作用机制研究

Eighty-three percent patients with focal cortical dysplasia (FCD) suffer from generalized tonic-clonic seizure. This evidence indicates that the neural circuit is abnormal in FCD, and is involved in the dissemination of epileptic discharge. It is well known that myelinization is the central component in the neural circuit, which is closely related to the matured oligodendrocyte. A recent study found a well-marked hyperplasia of oligodendrocyte precursor cells (OPCs) in lesions of FCD. However, the number of matured oligodendroglia is significantly decreased, and a remarkable hypomyelination was detected in the same areas. These results indicate that there is a dysmaturation of OPCs in FCD. Our previous study showed the up-regulated expression of VEGF-C and its receptor VEGFR-3 in the FCD, and the myelination level of FCD was increased when VEGFR-E signaling was blocked. Moreover, VEGF-C signal pathway selectively modulates the development of OPCs. Therefore, we hypothesize that VEGF-C/VEGFR-3 signaling inhibits the maturation process of OPCs into oligodendroglia by down-regulating the activity of GABAA system and Olig1. Hence, we will deeply explore the mechanism, by which of VEGF-C/VEGFR-3 signal pathway inhibits the maturation process of OPCs into oligodendroglia in the animal models of FCD and brain tissues from FCD patients. The present study will help us deeply understand the mechanism of intractable epilepsy induced by FCD.

83%的局灶性皮质发育不良（FCD）所致癫痫表现为全面性发作，表明FCD内介导痫性放电播散的神经环路存在异常。已知成熟少突胶质细胞介导的神经纤维髓鞘化是正常神经环路的构成要素。新近发现FCD脑区少突胶质前体细胞（OPCs）异常增生，但成熟少突胶质细胞减少、神经纤维呈低髓鞘化，表明FCD脑区OPCs成熟障碍。我们前期研究发现FCD脑区VEGF-C及其受体VEGFR-3表达显著上调，阻断VEGFR-3后FCD脑区髓鞘化水平升高，结合VEGF-C信号通路高选择性地调控OPCs发育的事实，我们推测：FCD中VEGF-C/VEGFR-3信号抑制OPCs终末成熟及髓鞘化。为此，本课题拟利用FCD临床标本和动物模型，以GABAA受体及Olig1为切入点，深入探讨VEGF-C/VEGFR-3抑制OPCs向成熟少突胶质细胞分化的分子机制及其对神经网络髓鞘化的影响，深化我们对FCD所致癫痫“难治性”的理解。

83%的局灶性皮质发育不良（FCD）所致癫痫表现为全面性发作，表明FCD内介导痫性放电播散的神经环路存在异常。我们课题组在前期研究发现FCD脑区VEGF-C及其受体VEGFR-3表达显著上调，阻断VEGFR-3后FCD脑区髓鞘化水平升高，结合VEGF-C信号通路高选择性地调控OPCs发育的事实，我们在立项时提出：FCD中VEGF-C/VEGFR-3信号抑制OPCs终末成熟及髓鞘化。为此，本课题利用FCD临床标本和动物模型，采用免疫组化/荧光、细胞培养、膜片钳、EEG记录等技术，从整体和分子水平探讨VEGF-C/VEGFR-3抑制OPCs向成熟少突胶质细胞分化的分子机制及其对神经网络髓鞘化的影响。我们的研究结果显示：1. 少突胶质细胞标记物Olig2，少突胶质前体细胞标记物PDGFα在FCD不同亚型（FCD I, FCD IIa和FCD IIb）临床标本表达显著升高，而成熟少突胶质细胞标记物CC1则显著减少。2. 在FCD皮质发育不良小鼠模型皮层病灶，Olig2，PDGFα的表达也显著增加，而CC1的表达则显著减少。3. 外源性VEGF-C诱导后，可促进培养的少突胶质细胞分化成熟，具体表现为Olig2和PDGFα的表达量增加，而对CC1无明显影响。4. 少突胶质细胞介导的神经纤维网络对调节突触可塑性有重要作用，睡眠慢波振荡(Slow-wave oscillations, SWO，0.5 Hz)可通过突触传递显著显著影响皮层锥体神经元的兴奋性。5. 与VEGF-C/VEGFR-3信号通路相关的炎症分子LILRB2、SHP-2、NLRP3、FGF13在癫痫病灶神经元或胶质细胞异常表达，可能是潜在的抗癫痫靶点。6. 在本项目的支持下，我们解析了与神经免疫和神经发生密切相关的Rev-Erbα，以及电压门控性氯通道(ClC)在颞叶癫痫（TLE）患者和动物模型癫痫病灶中的异常表达模式和功能。. 通过本项目我们明确了FCD病灶中少突胶质前体细胞成熟障碍这一重要病理特征，并初步探讨了VEGF-C通过调节GABA受体功能或神经炎症等调节少突胶质前体细胞成熟过程的具体机制，进一步深化了我们对“VEGF-C/VEGFR-3信号通路促进FCD病理发生”的理解。目前本项目发表基金标注文章11篇，其中SCI论文10篇，中文核心论文1篇；依托本项目，培养博士研究生2名。