Lung Endothelium in Vaso-Occlusion

急性胸综合征是由肺部炎症引起镰状红细胞与肺微血管内皮黏附增加引起的。新的证据表明，红细胞和内皮细胞之间的相互作用是动态的。在非炎症状态下，内皮表面表达的抗粘附蛋白促进了灌注，而在炎症状态下，血管闭塞部分是由粘附蛋白（如p -选择素）的上调和血管性血友病因子（vwf）从微血管内皮的释放引起的。内皮细胞的分泌细胞器为微囊-叶体，是这种细胞所特有的结构。在炎症循环中凝血酶等与gq相关的神经体液性炎症介质增加内皮细胞的胞质钙，而胞质钙的增加足以引起微北-帕拉德小体快速易位至质膜，导致vw - f分泌和p-选择素上调。刺激vw - f分泌和p-选择素上调的特定钙进入途径仍不完全清楚，特别是在血管闭塞的突出部位获得的微血管内皮细胞中。初步研究表明，肺微血管内皮细胞表达t型，电压激活钙通道，在炎症期间促进促凝内皮表型。在本提案中，我们将验证通过t型钙通道的钙进入是肺微血管内皮中vWf释放和p-选择素上调的重要放大步骤，从而促进镰状红细胞的保留。这一假设将通过培养的肺微血管内皮细胞和分离的大鼠肺模型进行探索，其中T通道在血流条件下对红细胞保留的作用可以进行评估。SPECIFIC AIMS验证了以下假设：[1]肺微血管内皮细胞表达一种t型钙通道，该通道被gq相关的神经体液炎症介质激活；[2]t型钙通道的激活促进了肺微血管内皮细胞vw f的释放和p-选择素的上调，这对血管闭塞很重要。希望这些研究的完成将提高我们对调节红细胞内皮粘附机制的理解，从而开发出治疗镰状细胞性贫血以及其他血管血栓形成疾病的有效疗法。

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.