阿司匹林抑制Eph-Ephrin通路促进少突胶质前体细胞分化与成熟的作用研究

Cerebral white matter lesion induced by chronic cerebral ischemia is one of the important factors leading to cognitive function impairment in elderly patients, during which the main pathological changes aredemyelination and oligodendrocyte loss. Our latest study showed that aspirin, a traditional nonsteroidal anti-inflammatory drug, can promote oligodendrocyte precursor cell proliferation, differentiation and maturation in the corpus callosum through ERK and RhoA pathwaysina rat white matter lesion model, but underlying mechanism(s) is still uncovered. Aspirin can reduce the production of prostaglandin by inhibiting cyclooxygenase-1. Prostaglandin was reported to activate the interaction of Ephrin ligand and Eph receptor, one of members of receptor tyrosine kinase family, consequently triggering inflammatory reaction. Additionally, Eph-Ephrin is a joint upstream molecule for regulating ERK and RhoA pathways. Based on these facts, we hypothesize that aspirin may promote oligodendrocyte precursor cell proliferation, differentiation and maturation through inhibiting Eph-Ephrin signaling pathway. Therefore, in this project we will use the morphological and molecular biological methods to study the expression of various Eph and Ephrin molecules on OLs and their precursors, and employ drug intervention and virus infection techniques to investigate whether aspirin can inhibit Eph-Ephrin signal pathway andconsequentlypromote oligodendrocyte precursor cell proliferation, differentiation and myelination in vivo and in vitro. Our results are expected toprovide a theoretical basis for the application of aspirin in the treatment of cerebral white matter lesion.

慢性脑缺血诱发的脑白质损伤是导致老年患者认知功能下降的重要因素之一，其主要病理改变之一为少突胶质细胞（OLs）的变性死亡。我们研究发现，传统非甾体抗炎药物阿司匹林可通过ERK及RhoA通路促进脑白质损伤大鼠胼胝体内OLs前体细胞的增殖、分化及成熟，但其调控机制尚不清楚。阿司匹林可抑制前列腺素产生，后者可激活Eph-Ephrin通路引发炎性反应，而Eph-Ephrin是调控ERK及RhoA的共同上游分子。据此我们提出假说，阿司匹林可能通过抑制Eph-Ephrin信号通路促进OLs前体细胞的增殖、分化及成熟。为此本项目拟通过形态学和分子生物学方法，观察多种Eph和Ephrin分子在OLs及其前体细胞中的表达情况；利用药物干预和病毒载体感染手段，体内与体外研究阿司匹林是否可抑制Eph-Ephrin促进OLs前体细胞的增殖、分化及髓鞘形成，预期研究结果可为阿司匹林应用于脑白质损伤治疗提供理论依据。

背景：慢性脑缺血诱发的脑白质损伤是导致老年患者认知功能下降的重要因素之一，其主要病理改变之一为少突胶质细胞（OLs）的变性死亡。我们研究发现，传统非甾体抗炎药物阿司匹林可通过ERK 及RhoA 通路促进脑白质损伤大鼠胼胝体内OLs 前体细胞的增殖、分化及成熟，但其调控机制尚不清楚。阿司匹林可抑制前列腺素产生，后者可激活Eph-Ephrin通路引发炎性反应，而Eph-Ephrin 是调控ERK 及RhoA 的共同上游分子。据此我们展开实验，研究内容：观察多种Eph 和Ephrin 分子在OLs 及其前体细胞中的表达情况；利用药物干预和病毒载体感染手段，体内与体外研究阿司匹林是否可抑制Eph-Ephrin 促进OLs 前体细胞的增殖、分化及髓鞘形成。重要结果：在正常大鼠胼胝体部14种Eph受体当中以EphA4的mRNA表达水平最高。EphA4受体在OPC、成熟少突胶质细胞及星形胶质细胞上均有表达。脑白质损伤后EphA4表达明显上调，OPC细胞数量明显增多，而成熟的OLs细胞数量明显减少。使用ASA后可显著降低EphA4的表达，对于低剂量ASA可引起OPC数量增高，高剂量ASA则未见OLs数量有明显改变。在细胞水平上，应用ASA同样可引起OPC数量增高，应用ASA +EphA4-Fc后OPC数量增高更明显，提示EphA4确实影响了OPC的增殖。ASA对EphA4受体的作用是一种间接作用，而非直接结合作用，所以ASA是通过间接途径作用于EphA4受体保护缺血造成的脑白质损伤。科学意义： 整个研究结果为ASA保护缺血造成的WML提供理论依据，同时为脑损伤后神经的再生、修复提供新思路。