白藜芦醇调节星形胶质细胞的活化促进脊髓损伤修复的研究

After spinal cord injury (SCI), reactive astrocytes and glial scar make the injured microenvironment change to hamper the injured spinal cord recovery. Our previous study reveals that the astrocytes reactivated after SCI secrete BMP2 and inhibit the co-cultured OPCs to differentiate into OLs. It has been reported that the activation of the STAT3 is necessary to activate the astrocytes after SCI . BMP2 is the downstream target gene in the pathway of STAT3 during the astrocytogenesis. Based on this evidence, we hypothesize that STAT3 would increase the secretion of the BMP2. Therefore, the inhibition of STAT3 may provide a way to regulate the secretion of BMP2 that is produced by reactive astrocytes. Resveratrol (Res) , wildely found in natural plants, has a variety of biological activity and is capable of inhibiting the activation of STAT3. This proposal is designed to use Res to treat the reactive astrocytes to regulate the activation of STAT3/BMP2 pathway, which may further affect the proliferation and differentiation of OPCs. Hence, this proposal attempts to establish a mechanism with key factors involved in a pathway for SCI recovery. The ultimate goal of this proposal is to provide a strategy with sound hypothesis that will be experimentally proved through molecular biology approach.

脊髓损伤(SCI)后，活化的星形胶质细胞和胶质瘢痕可改变受损部位的微环境，并分泌骨形态发生蛋白２(BMP2), 抑制少突胶质前体细胞(OPCs)分化为少突胶质细胞(OLs)，阻碍脊髓再生和修复。已有研究证实STAT3通路激活是SCI后星形胶质细胞活化的必要条件。而在星形胶质细胞发育过程中，BMP2是STAT3通路的下游靶基因。据此我们推测，SCI后星形胶质细胞中的STAT3被激活, 导致BMP2分泌增加。因此，抑制STAT3的活性可抑制星形胶质细胞的活化和增生，减少BMP2的分泌,进而促进OPCs分化为OLs，最终利于脊髓再生和功能恢复。白藜芦醇(Res) 广泛存在于天然植物中,具有多种有益的生物学活性,是STAT3的抑制子。本项目拟用Res，通过抑制STAT3/BMP2通路的活性，观察其对SCI修复的影响,为探讨脊髓再生修复的机制和寻找新策略提供理论和实验依据。

星形胶质细胞(astrocyte, ASC) 广泛分布于中枢神经系统各个区域，是中枢神经系统内最主要的细胞组成部分，对维持中枢神经系统的结构和功能，以及在多种神经系统疾病中发挥重要的作用。在脊髓损伤(SCI)后，ASC发生数量、形态和功能等方面的变化，转化成活化的星形胶质细胞，不仅可形成胶质瘢痕，而且通过分泌一些活性因子，改变受损部位的微环境，阻碍脊髓再生和修复。STAT3是信号转导和转录激活因子家族的重要成员，与细胞的增殖、分化及凋亡密切相关。近来研究发现，STAT3通路激活与SCI后星形胶质细胞的活化有直接关系。白藜芦醇(Res)是一种生物活性很强的多酚类物质， 广泛存在于天然植物中,具有抗氧化和抗肿瘤等多种有益的生物学活性。近年来，白藜芦醇的神经保护作用越来越受到关注。在脊髓损伤中，白藜芦醇的修复机制主要集中于其抗氧化损伤的作用，有关白藜芦醇对星形胶质细胞增殖和活化的作用研究尚未见报告。本研究结果表明，大鼠脊髓损伤1周后，损伤区域内GFAP和STAT3的表达增加。利用不同的星形胶质细胞培养模型，首次提出白藜芦醇对星形胶质细胞的增殖具有显著的抑制作用。流式细胞检测结果显示，白藜芦醇可诱导G0/G1期细胞周期阻滞。Western blot和免疫化学实验结果表明白藜芦醇降低GFAP、STAT3和BMP2等蛋白的表达。这些结果提示，白藜芦醇可通过抑制STAT3信号通路，减低反应性星形胶质细胞的活性，进而促进损伤脊髓的修复，为探讨脊髓再生修复的机制和寻找新的治疗策略提供理论和实验依据。