血小板源性生长因子-D在创伤性脑损伤后继发性脑损伤中的作用机制研究

The mechanisms of secondary brain injury after traumatic brain injury (TBI) are various, the phenotype switching of vascular smooth muscle cell (VSMC) and the disruption of the blood brain barrier play important roles. Platelet-derived growth factor-D (PDGF-D) signal pathway was involved in the process of vascular smooth muscle cell phenotype switching of cardiovascular system. Our preliminary experimental results show that PDGF-D were probably involved in the process of smooth muscle cell phenotype switching and blood brain barrier disruption after TBI. So, we propose the hypothesis: the interaction of PDGF-D and its receptor activate smooth muscle cell phenotype switching signal pathway, which was involved in the pathological process of TBI induced secondary brain injury. To test our hypothesis, we determine the phenotype switching of vascular smooth muscle cell and the disruption of the blood brain barrier by immunofluorescence staining, western blot, vessel painting, myography and India ink angiogram after TBI. We apply the siRNA，recombinant PDGF-D and PDGF-D receptor inhibitor, after verifying the effect of interference, then we observe the exprssion or activation of key factors in the signal path, to analyze the potential molecular mechanisms, and observe the effection of vascular smooth muscle phenotype switching and blood brain barrier disruption. It will provide us new ideas and theoretical basis to improvethe prognosis of TBI patients.

创伤性脑损伤（TBI）后继发性脑损伤的机制较多，其中脑血管平滑肌细胞表型转换以及血脑屏障破坏起着重要作用。我们前期的研究基础及预实验结果提示TBI后脑血管平滑肌细胞发生表型转换，并且血小板源性生长因子-D（PDGF-D）可能参与该过程。因此，我们提出假说：TBI后，PDGF-D与其受体结合，激活脑血管平滑肌细胞表型转换信号通路，加重继发性脑损伤。为了验证假说，我们使用大鼠TBI模型，应用免疫荧光、western blot，vessel painting，肌动描记图和印度墨汁造影术等检测TBI后脑血管平滑肌细胞表型转换及血脑屏障破坏的情况；应用siRNA技术、重组PDGF-D及PDGF-D受体抑制剂等干预PDGF-D的作用，检测信号通路关键因子的表达和激活情况，探讨其可能的分子作用机制，观察其调节脑血管平滑肌细胞表型转换及血脑屏障破坏的情况，为改善TBI预后提供新的思路和理论依据。

创伤性脑损伤（TBI）后继发性脑损伤的机制较多，其中脑血管平滑肌细胞表型转换以及血脑屏障破坏起着重要作用。本课题通过使用大鼠TBI模型，应用免疫荧光、western blot、脑水肿测定、行为学评分等检测创伤性脑损伤后脑血管平滑肌细胞表型转换及血脑屏障破坏的情况；应用siRNA技术、重组PDGF-D等干预PDGF-D的作用，检测信号通路关键因子的表达和激活情况，探讨其可能的分子作用机制。我们发现：大鼠TBI后，PDGF-D的水平在伤后6小时即开始升高，一直到3天仍保持较高水平；p-PDGFR-β的水平在伤后12小时开始升高，一直到3天仍保持较高水平。PDGF-D激活在血管平滑肌细胞上表达的PDGFR-β，使PDGFR-β磷酸化，进而激活p38 MAPK-MK2信号传导通路，加重脑挫伤周围血管平滑肌细胞的表型向分泌型转换，进而加重炎症反应，加重大鼠TBI后的脑损伤。同时，抑制PDGF-D能够减轻脑挫伤周围血管平滑肌细胞的表型向分泌型转换，进而减轻炎症反应，减轻TBI后的脑损伤。相关研究结果为创伤性脑损伤的基础和临床研究提供新的思路和理论依据。