Wong D, Prameya R, Dorovini-Zis K
Department of Pathology, Vancouver General Hospital and the University of British Columbia, Canada.
J Neuropathol Exp Neurol. 1999 Feb;58(2):138-52. doi: 10.1097/00005072-199902000-00004.
Increased lymphocyte traffic across an altered blood-brain barrier (BBB) is a prominent and early event in inflammatory and immune-mediated CNS diseases. The factors that control the entry of lymphocytes into the brain have not been fully elucidated. In this study, primary cultures of human brain microvessel endothelial cells (HBMEC) were used to investigate the role of endothelial cell (EC) adhesion molecules in the adhesion and migration of peripheral blood T lymphocytes across TNF-alpha treated and untreated monolayers. Adhesion of T cells to unstimulated HBMEC was minimal and few of the adherent cells migrated across the monolayers. Treatment of HBMEC with TNF-alpha augmented adhesion by 5-fold. The binding to activated EC was significantly, but not completely, inhibited by monoclonal antibodies (mAbs) to ICAM-1 and VCAM-1, whereas adhesion to unstimulated EC was blocked by mAb to ICAM-1 but not VCAM-1. Transendothelial migration of lymphocytes increased by up to 30-fold following treatment of HBMEC with TNF-alpha. Migration across activated monolayers, but not across untreated EC, was almost completely blocked by Ab to ICAM-1 and significantly inhibited by Abs to PECAM-1 and E-selectin. VCAM-1 was not utilized during transendothelial migration. Ultrastructurally, pseudopodia from lymphocytes contacted finger-like cytoplasmic projections on EC and eventually penetrated the EC cytoplasm at focal points along the apical surface. Migrating lymphocytes moved either through the EC cytoplasm or between adjacent EC across intercellular contacts. The overlying monolayers showed no evidence of disruption and intercellular junctions appeared intact over the migrated T cells. These studies indicate that adhesion and migration of T lymphocytes across the cerebral endothelial barrier are distinct processes that depend upon the activation state of EC and are controlled by diverse receptor-ligand interactions.
在炎症和免疫介导的中枢神经系统疾病中，淋巴细胞穿越改变的血脑屏障（BBB）的流量增加是一个突出且早期的事件。控制淋巴细胞进入大脑的因素尚未完全阐明。在本研究中，使用人脑微血管内皮细胞（HBMEC）的原代培养物来研究内皮细胞（EC）粘附分子在TNF-α处理和未处理的单层细胞中外周血T淋巴细胞粘附和迁移中的作用。T细胞与未刺激的HBMEC的粘附极少，且很少有粘附细胞穿过单层细胞迁移。用TNF-α处理HBMEC可使粘附增加5倍。与活化EC的结合被抗ICAM-1和VCAM-1的单克隆抗体（mAb）显著但未完全抑制，而与未刺激EC的粘附被抗ICAM-1的mAb阻断，但未被抗VCAM-1的mAb阻断。用TNF-α处理HBMEC后，淋巴细胞的跨内皮迁移增加了多达30倍。穿过活化单层细胞的迁移，但不穿过未处理的EC，几乎完全被抗ICAM-1的抗体阻断，并被抗PECAM-1和E-选择素的抗体显著抑制。跨内皮迁移过程中未利用VCAM-1。在超微结构上，淋巴细胞的伪足接触EC上的指状细胞质突起，并最终在沿顶端表面的焦点处穿透EC细胞质。迁移的淋巴细胞要么穿过EC细胞质，要么通过相邻EC之间的细胞间接触迁移。上层单层细胞没有破坏的迹象，并且在迁移的T细胞上方细胞间连接似乎完整。这些研究表明，T淋巴细胞穿越脑内皮屏障的粘附和迁移是不同的过程，取决于EC的活化状态，并由多种受体-配体相互作用控制。
