CXCL12 通过激活 JAK/STAT 通路促进中枢神经系统髓鞘修复的机制研究

Neuromyelitis optica(NMO) is a blinding demyelinating disease in central nervous system. Approximately 50% patients attack with optic neuritis initially. Our team previously found that CXCL12 level was associated with NMO, affecting remyelination of optic nerve sheath, and the papers had been published. Our cell experiment showed that CXCL12 could promote differentiation and maturation of oligodendrocyte precursor cells(OPCs) prominently. And we improved the method of building NMO animal model, which indicated that supplement of CXCL12 could protect the central nervous system effectively. Thus, how did CXCL12 promote the remyelination and protect it specifically? Paper on Stem Cell magazine showed JAK/STAT signal pathway could be activated by CXCL12 and plays an important role in differentiation of nerve cell. Therefore we hypothesized that, CXCL12 could promote differentiation of OPCs by activating JAK/STAT signal pathway, and increase the number of oligodendroglia cells to promote the repair and regeneration of myelin sheath. Our research would further verify the hypothesis by observing in vivo and vitro, trying to reveal the mechanism partially and provide new scientific evidence to promote the remyelination and improve prognosis.

视神经脊髓炎（NMO）是一种致盲性中枢神经系统脱髓鞘疾病，约50%患者以视神经炎首发。本团队前期研究创新性发现CXCL12水平与NMO疾病及视神经髓鞘的修复再生有关，两篇相关文章已发表。本团队通过细胞实验表明CXCL12可明显促进少突胶质前体细胞（OPCs）的成熟分化；且我们改良了NMO动物模型构建方法，并证实补充CXCL12对中枢神经系统有明显保护作用。那么，CXCL12具体是如何促进髓鞘修复并保护的？Stem Cell杂志有文献表明JAK/STAT信号通路可被CXCL12激活并在神经细胞的分化过程中发挥了重要作用。因此我们提出假设，CXCL12可以通过激活JAK/STAT通路促进OPCs分化，使少突胶质细胞数量增加促使髓鞘修复。本课题拟通过体内和体外实验进一步验证该假说，从而揭示CXCL12促髓鞘修复的部分调控机制，为探索促髓鞘再生、提高患者视力预后的可能途径积累新的科学依据。

背景：趋化因子12（CXCL12）是一种具有多种功能的趋化因子。有研究表明，CXCL12能够加重中枢神经系统（CNS）的炎症症状；但也有证据表明，CXCL12可以促进实验性自身免疫性脑脊髓炎（EAE）中枢神经系统髓鞘的修复。在本课题中，我们通过先上调脊髓中的CXCL12表达，再诱导EAE模型的技术路线，研究了CXCL12的表达上调在EAE模型中的相关作用。方法：脊髓鞘内导管植入后，注射腺相关病毒9（AAV9）/eGFP-P2A-CXCL12诱导Lewis大鼠脊髓中CXCL12表达的上调。并于注射AAV后21天，诱导EAE疾病模型；采用行为学试验和免疫荧光染色法评价CXCL12上调对EAE模型的影响。在体外研究中，收集少突胶质细胞前体细胞（OPCs）与CXCL12和AMD3100共培养，通过免疫荧光染色以进行功能评估。结果：在EAE模型中，通过上调CXCL12的表达，能够以抑制白细胞浸润和保护髓鞘的方式显著降低EAE模型的临床评分。与之相反，在加入CXCR4拮抗剂AMD3100后，CXCL12的保护作用显著降低。在体外，浓度为10 ng/ml CXCL12即可促进OPCs向少突胶质细胞分化。结论：AAV介导的中枢神经系统CXCL12的表达上调，可缓解EAE模型的临床表征，显著减少EAE高峰期白细胞浸润。CXCL12可促进OPCs细胞向少突胶质细胞分化。在中枢神经系统上调CXCL12的表达，能够有效保护脊髓白质，缓解EAE模型的表征。