The contribution of endothelial basement membrane laminins and immune cells to functional integrity of the neurovascular unit

内皮基底膜层粘连蛋白和免疫细胞对神经血管单元功能完整性的贡献

• 批准号: 275953122
• 负责人: Professorin Dr. Lydia Sorokin
• 金额: --
• 依托单位: Institut für Physiologische Chemie und Pathobiochemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/275953122?language=en
• 关键词: contribution; endothelial; basement; membrane; laminins

The functional connection between blood vessels in the brain and the surrounding neurons is illustrated by the rapid response of neurons to focal ischemia, and is manifested by endothelial cells, astrocytes and neurons, but also two distinct basement membranes (BMs) that underlie the endothelium and marker the border to the CNS parenchyma (known as the endothelial and parenchymal BMs, respectively). These cellular and acellular layers collectively form a structural continuum between blood vessel and neurons that is now commonly referred to as the neurovascular unit (NVU). While the cellular constituents of the NVU are common topics of research, the BMs of the NVU and their contribution to its structural and functional integrity are poorly understood. We have shown that the endothelial and parenchymal BMs are biochemically distinct, varying principally in their laminin isoforms composition, with laminin alpha4 and alpha5 characterising the endothelial BM and laminin alpha2 and alpha1 characterizing the parenchymal BM. Neuroinflammation studies in our lab have also shown that the two BMs impact differently on leukocyte extravasation across CNS postcapillary venules, with laminin alpha5 and alpha4 acting as migration cues for infiltrating leukocytes and the parenchymal BM acting as the effective barrier to the CNS parenchyma. More recent studies using laminin alpha4 knockout (KO) mice (Lama4-/-), and endothelial cell specific laminin alpha5 conditional KO mice in transient middle cerebral artery occlusion (MCAO), an ischemic stroke model, have further implicated specifically laminin alpha5 in endothelial cell barrier properties. In addition, the MCAO studies revealed an unexpected accumulation of immune cells within vessel lumens and between BMs layers, in an as yet undefined manner, suggesting that immune cells within the vessel lumen and/or perivascular zone can communicate with the surrounding CNS parenchyma. We here propose to focus on the endothelial portion of the NVU, with emphasis on the endothelial cell BM laminins, laminin alpha4 and alpha5, and how they influence the functional integrity of the NVU. In addition, we will investigate the molecular mechanism/s of immune cell interaction with cerebral vessels following ischemic stroke. These studies will contribute to the understanding of factors important for normal NVU function and are likely to open new avenues for the development of more effective therapies to minimize brain damage after ischemic stroke.

脑内血管和周围神经元之间的功能联系可以通过神经元对局灶性缺血的快速反应来说明，这种联系可以通过内皮细胞、星形胶质细胞和神经元来表现，但也可以通过内皮下面的两种不同的基底膜（BMs）来表现，这些基底膜标志着中枢神经系统实质的边界（分别称为内皮和实质BMs）。这些细胞层和非细胞层共同形成血管和神经元之间的结构连续体，现在通常称为神经血管单元（NVU）。虽然NVU的细胞成分是研究的共同主题，但NVU的脑转移及其对其结构和功能完整性的贡献却知之甚少。我们已经证明内皮和实质脑转移在生化上是不同的，主要是它们的层粘连蛋白同种异构体组成不同，层粘连蛋白α 4和α 5是内皮脑转移的特征，层粘连蛋白α 2和α 1是实质脑转移的特征。我们实验室的神经炎症研究也表明，两种脑转移对白细胞在中枢神经系统毛细血管后小静脉外渗的影响不同，层粘连蛋白α 5和α 4是浸润白细胞的迁移线索，而实质脑转移是中枢神经系统实质的有效屏障。最近的研究使用层粘连蛋白α 4敲除（KO）小鼠（Lama4-/-）和内皮细胞特异性层粘连蛋白α 5条件型KO小鼠进行短暂性大脑中动脉闭塞（MCAO）（缺血性卒中模型），进一步明确了层粘连蛋白α 5与内皮细胞屏障特性的关系。此外，MCAO研究揭示了免疫细胞在血管腔内和脑转移瘤层之间以一种尚未明确的方式意想不到地积聚，这表明血管腔内和/或血管周围区的免疫细胞可以与周围的中枢神经系统实质沟通。我们建议关注NVU的内皮部分，重点关注内皮细胞BM层粘连蛋白、层粘连蛋白α 4和α 5，以及它们如何影响NVU的功能完整性。此外，我们将研究缺血性脑卒中后免疫细胞与脑血管相互作用的分子机制。这些研究将有助于了解影响NVU正常功能的重要因素，并可能为开发更有效的治疗方法开辟新的途径，以最大限度地减少缺血性卒中后的脑损伤。