Lung Endothelium in Vaso-Occlusion

急性胸部综合征是由肺部炎症引起的，导致镰状红细胞与肺微血管内皮细胞黏附增加。越来越多的证据表明，红细胞与内皮细胞之间的相互作用是动态的。在非炎症状态下，血管内皮细胞表面表达的抗黏附蛋白促进了血管的灌流，而在炎症状态下，血管闭塞的部分原因是P-选择素等黏附蛋白的上调和微血管内皮细胞释放von Willebrand因子(VWf)。内皮细胞中的分泌细胞器是韦贝帕莱德小体，这是这种细胞类型所特有的结构。在炎症循环中，凝血酶和其他GQ相关的神经体液炎症介质增加内皮细胞胞浆钙，这种胞浆钙的升高足以导致韦贝帕拉德小体迅速移位到质膜，以促进v Wf分泌和P-选择素上调。刺激vWf分泌和P-选择素上调的特定钙进入途径仍不完全清楚，尤其是在血管闭塞显著部位获得的微血管内皮细胞。初步研究表明，肺微血管内皮细胞表达T型电压激活的钙通道，在炎症过程中促进促凝血内皮细胞表型。在这项提案中，我们将检验通过T型钙通道进入钙是释放VWF和上调肺微血管内皮细胞P-选择素以促进病态红细胞滞留的重要放大步骤的总体假设。这一假说将利用培养的肺微血管内皮细胞和一个分离的大鼠肺模型进行探索，在该模型中，可以在流动条件下评估T通道对红细胞滞留的作用。[1]肺微血管内皮细胞表达由Gq连接的神经体液炎症介质激活的T型钙通道，[2]T型钙通道的激活促进肺微血管内皮细胞释放vWf和上调P-选择素，对血管闭塞具有重要作用。希望这些研究的完成将提高我们对调节红细胞-内皮黏附的机制的理解，以便开发有效的治疗方法来治疗镰状细胞贫血和其他血管血栓形成障碍。

The acute chest syndrome is initiated by lung inflammation that induces increased adhesion of sickled red blood cells to pulmonary microvascular endothelium. Emerging evidence indicates the interaction between red blood cells and endothelium is dynamic. While in the non-inflamed state perfusion is facilitated by anti-adhesive proteins expressed on the endothelial surface, in the inflamed state vaso-occlusion is partly caused by upregulation of adhesive proteins such as P-selectin and release of von Willebrand factor (v W f) from microvascular endothelium. The secretory organelle in endothelium is the WeibeI-Palade body, a structure unique to this cell type. In the inflamed circulation thrombin and other Gq-linked neurohumoral inflammatory mediators increase endothelial cell cytosolic calcium, and this rise in cytosolic calcium is sufficient to cause rapid translocation of WeibeI-Palade bodies to the plasmalemma for v W f secretion and P-selectin up-regulation. Specific calcium entry pathways that stimulate v W f secretion and P-selectin up-regulation remain incompletely understood, particularly in microvascular endothelial cells obtained from the prominent site of vaso-occlusion. Preliminary studies suggest that lung microvascular endothelial cells express T-type, voltage-activated calcium channels which promote a pro-coagulant endothelial phenotype during inflammation. In this proposal, we will test the overall HYPOTHESIS that calcium entry through T-type calcium channels is an important amplification step in release of vWf and up-regulation of P-selectin from lung microvascular endothelium that promotes the retention of sickled red blood cells. The hypothesis will be explored using lung microvascular endothelial cells in culture and an isolated rat lung model, in which the role of the T channel to red blood cell retention can be assessed under flow conditions. The SPECIFIC AIMS test the hypotheses that: [1] Lung microvascular endothelial cells express a T-type calcium channel that is activated by Gq-linked neurohumoral inflammatory mediators, and [2] Activation of T-type calcium channels promotes the release of v W f and up-regulation of P-selectin from lung microvascular endothelial cells important for vaso-occlusion. It is hoped completion of these studies will improve our understanding of mechanisms that regulate erythrocyte-endothelial adherence so that effective therapies can be developed for treatment of sickle cell anemia, as well as other vascular thrombosis disorders.