阻断硫酸软骨素蛋白多糖对未成熟脑损伤髓鞘形成的保护作用

Dysmyelination after cerebral white matter injury in premature infants is closely related to cerebral palsy and cognitive deficits. However, the mechanism of dysmelination remains unclear, and there is no effective therapy for this. Our team found that chondroitin sulfate proteoglycans (CSPGs) expression increased after hypoxic-ischemic (HI) brain injury, which may lead to myelination deficiency. Cell and animal models of HI brain injury as well as some molecular biological technologies, pathological techniques, and behavior monitoring platform will be employed in this study. This study will focus on the spatial and temporal expression of CSPGs and its primary members before and after HI injury, identifying the major cell source of CSPGs and the members working in dysmyelination. We will observe the relationship of CSPGs with HIF-1α and dysmyelination, conforming that CSPGs is the major reason for dysmyelination in premature brain and HIF-1α is the key factor to induce CSPGs expression. Interruption of CSPGs through four targets, we focus on the promotion effect on myelination of interruption of CSPGs in premature brain injury. This finding will provide new sight for the mechanism of CSPGs on dysmyelination, and provide sufficient scientific evidence for exploring new treatment for premature white matter injury.

早产儿脑白质损伤后发生的髓鞘化障碍与脑瘫和认知缺陷密切相关，但髓鞘化障碍的机制仍不清楚，且缺乏有效干预措施。本项目组前期研究发现缺氧缺血（HI）脑损伤后硫酸软骨素蛋白多糖（CSPGs）表达增加，可能与髓鞘化障碍相关。本项目拟建立未成熟鼠HI脑损伤的细胞和动物模型，应用分子生物学、病理学及神经行为学等技术，研究CSPGs及主要成员生理状态下的分布及HI脑损伤后表达的动态变化，确定HI脑损伤后CSPGs的细胞来源及可能起作用的CSPGs成员；观察CSPGs与缺氧诱导因子（HIF-1α）、髓鞘化障碍的相关性，确定CSPGs是未成熟脑髓鞘化障碍的主要原因，HIF-1α是诱导CSPGs表达的关键信号。然后选择4个靶点阻断CSPGs，观察阻断CSPGs对未成熟脑HI损伤后髓鞘形成的保护作用。通过本研究进一步阐明CSPGs在未成熟脑髓鞘化障碍中的作用机制，为发掘早产儿脑白质损伤治疗策略提供科学依据。

早产儿脑白质损伤后髓鞘化障碍与脑瘫和认知缺陷密切相关，但髓鞘化障碍的机制仍不清楚，且缺乏有效干预措施。本项目组前期研究发现未成熟大鼠缺氧缺血（HI）脑损伤后硫酸软骨素蛋白多糖（CSPGs）表达增加，可能与髓鞘化障碍相关。本项目首先检测生理状态下CSPGs在未成熟鼠脑中的表达情况，发现CSPGs各成员的表达水平在不同发育时期不同区域存在动态变化，提示CSPGs在未成熟脑发育中具有重要作用。通过建立未成熟大鼠HI脑损伤模型，发现损伤后胼胝体区域CSPGs明显增多，并主要来源于活化的星形胶质细胞，损伤后立刻木糖苷抑制CSPGs合成无改善作用并加重脑损伤，损伤后3天抑制CSPGs可以促进髓鞘形成，改善大鼠脑功能。体外研究发现CSPGs可通过β1整合蛋白抑制少突胶质前体细胞（OPCs）的迁移和分化成熟。本项目还发现未成熟大鼠HI脑损伤后胼胝体区域HIF-1α在损伤后24小时和7天存在两次明显升高，7天时升高主要来源于星形胶质细胞，通过抑制剂2-ME干预延迟性HIF-1α升高可以减少损伤区域星形胶质细胞活化和CSPGs表达，改善髓鞘形成和脑功能。此外，HI脑损伤后胼胝体区域P2X7表达升高，抑制P2X7可以减少损伤后7天 HIF-1α表达和星形胶质细胞活化。本研究证实了未成熟大鼠HI脑损伤后CSPGs表达增多，会抑制OPCs分化成熟，导致髓鞘形成和脑功能发育障碍；发现CSPGs增多可能与星形胶质细胞延迟性HIF-1α升高和P2X7升高有关；有助于深入了解脑白质损伤机制，并提供潜在治疗靶点。