骨桥蛋白多肽A与αvβ3整合素结合活化的通路在血管新生中的作用

Stroke is one of the major diseases which cause very high mortality and disability. Most of stroke patients can not receive thrombolytic therapy within therapeutic window. Some neuroprotective drugs that had been proved by animal experiments did not achieve clinical benefit for treatment of acute stroke, for ignoring the the reconstruction of the vascular structure and function after cerebral ischemia. Our previous study showed that osteopontin peptide A not only has neuroprotective effects, but also promotes angiogenesis. However, its mechanism is still unclear. We propose osteopontin peptide A promotes angiogenesis through its RGD sequence binding with αvβ3 receptor and regulate PI3K/AKT/eNOS signaling pathways. This study was undertaken to examine the receptor of osteopontin peptide A and angiogenisis signal pathway in the post-ischemic rat brain through the establishment of rat model of brain ischemia and cell culture, and using neurological severity score、immunohistochemistry staining、western blot and pull down assay experiment. This project will enrich and perfect the molecular mechanism of osteopontin peptide A in treating ischemic stroke and provide experimental support for theoretical connection between “cerebral angiogenesis” and “neurovascular unit protection”.

脑卒中是具有极高的病死率和致残率的重大疾病之一。大多数脑卒中患者未能在“时间窗”内得到及时溶栓治疗。一些经动物实验证明有效的单一靶点神经保护剂也因为忽视了脑缺血后血管结构与功能的重建，结果导致临床试验失败。本项目组前期研究发现骨桥蛋白多肽A不仅在大鼠脑缺血中具有神经保护的作用，还可以促进血管新生，但是其促进血管新生的机制尚不清楚。我们提出骨桥蛋白多肽A通过自身RGD模序与αvβ3 受体结合，调控PI3K/AKT/eNOS信号通路，促进血管新生的假设。本项目拟通过建立脑缺血大鼠模型和细胞培养，利用神经损伤评分、免疫组化染色，免疫蛋白印记、蛋白质体外结合等实验方法，研究证明骨桥蛋白多肽A促进脑缺血大鼠血管新生的受体及信号通路。本课题将充实并完善骨桥蛋白多肽治疗缺血性脑卒中的作用及分子机制，为 “脑血管新生”、“神经血管单元保护”理论之间的衔接提供实验支持。

经动物实验证明有效的单一靶点神经保护剂常常导致临床试验失败，一个非常重要的原因就是因为忽视了脑缺血后血管结构与功能的重建，调节和诱导血管新生被认为是脑卒中后潜在的治疗靶点。项目组以人脐静脉血管内皮细胞(HUMEC)为研究对象，发现骨桥蛋白多肽A促进HUMEC的增值、迁移和管腔形成，并促进VEGF、MMP-9、SMA等血管相关因子的表达，且其促进血管新生的作用是通过RGD模序与αvβ3 受体结合，进而调控PI3K/AKT/ERK信号通路诱导的。骨桥蛋白多肽A的促血管新生作用在脑缺血大鼠模型中也得到了证实。同时，我们也发现了含有9个氨基酸序列的骨桥蛋白衍生肽也具有促血管新生作用。以上研究成果充实并完善了骨桥蛋白多肽治疗缺血性脑卒中的作用及分子机制，为 “脑血管新生”、“神经血管单元保护”理论之间的衔接提供实验支持。