T-Type Calcium Channels and Neutrophil Transmigration

进入肺泡的病原体和有毒物质引发炎症反应， 其特征在于中性粒细胞从循环中募集并进入静脉。中性粒 最初穿过毛细血管内皮进入肺泡，因此，这些 微血管内皮细胞具有看门人功能。而在正常情况下， 毛细血管内皮不损害中性粒细胞通过毛细血管的运动， 毛细血管内皮对炎症的反应迅速诱导表面表达P- 选择素，其与嗜中性粒细胞相互作用并启动它们向肺泡的迁移。增加 内皮细胞胞浆钙离子可促进含有P-选择素的囊泡从内皮细胞中转位， 从胞质溶胶到质膜。我们最近的证据表明QIG T型钙通道 提供了这种P-选择素表面表达所需的细胞溶质钙源;因为这 钙通道仅在毛细血管内皮中表达，而在肺动脉或 静脉内皮，它似乎在肺微循环中发挥高度专门化的作用。的确， 我们的初步数据显示，铜绿假单胞菌引起严重的中性粒细胞募集， 在QIG和P-选择素敲除小鼠中被消除的作用。目前该 调节P-选择素表面表达和中性粒细胞的钙应答事件 轮回仍然知之甚少。值得注意的是，我们的初步数据表明，QIG T 型钙通道与内皮细胞一氧化氮合酶（NOS 3）相互作用。钙 通过QIG通道的渗透激活NOS 3，其产生一氧化氮，对抗P 选择素表面表达，具有反馈调节的特点。因此，这一具体目标 本课题将检验以下假设：在肺泡毛细血管内皮中：[1] QIG与N 0 S3相关 并控制其激活; [2] NOS 3衍生的一氧化氮抑制P-选择素胞吐;[3] QIG 诱导的NOS 3活化限制了内皮向促炎表型的转变 总的来说，本项目将确定QIG T型钙通道和NOS 3是否代表 急性肺损伤中性粒细胞运输调控的新治疗靶点。 相关性（参见说明）： 中性粒细胞是抵抗感染所需的白色血细胞。当病原体，比如细菌， 当进入主动脉时，中性粒细胞从血液中迁移到主动脉中。这个中性粒细胞 反应受到高度调节，以确保招募的细胞既不太多也不太少 对中性粒细胞气道募集的机制知之甚少， 我们的研究。

Pathogens and noxious agents that access the alveoli initiate an inflammatory response that is characterized by neutrophil recruitment out of the circulation and into the ainways. Neutrophils initially transmigrate across capillary endothelium to access the alveoli, and hence, these microvascular endothelial cells possess a gatekeeper function. Whereas under normal, un-lnflamed conditions capillary endothelium does not Impair neutrophil movement through capillaries, in response to inflammation capillary endothelium promptly induces the surface expression of P- selectin, which interacts with neutrophils and initiates their transmigration into alveoli. An increase in endothelial cell cytosolic calcium promotes the translocation of vesicles containing P-selectin from the cytosol to the plasma membrane. Our recent evidence indicates the QIG T-type calcium channel provides the cytosolic calcium source that is needed for such P-selectin surface expression; as this calcium channel Is only expressed in capillary endothelium, and not in either pulmonary artery or vein endothelium, it appears to fulfill a highly specialized role in the lung microcirculation. Indeed, our preliminary data reveal that Pseudomonas aeruginosa causes profound neutrophil recruitment to the ainways, an effect that is abolished in QIG and P-selectin knockout mice. At present, the calcium responsive events that modulate P-selectin surface expression and neutrophil transmigration remain poorly understood. Notably, our preliminary data demonstrate that the QIG T type calcium channel interacts with endothelial cell nitric oxide synthase (N0S3). Calcium permeation through the QIG channel activates N0S3, which produces nitric oxide that opposes P selectin surface expression, characteristic of feedback regulation. Hence, the Specific Aims of this project will test the hypotheses that in alveolar capillary endothelium: [1] QIG associates with N0S3 and controls its activation; [2] N0S3-derived nitric oxide inhibits P-selectin exocytosis; and [3] QIG induced N0S3 activation limits the endothelial transition to a proinflammatory phenotype Collectively, this project will determine whether the QIG T-type calcium channel and N0S3 represent novel therapeutic targets for the regulation of neutrophil trafficking in acute lung injury. RELEVANCE (See instructions): Neutrophils are white blood cells that are needed to fight infection. When pathogens, like bacteria, access the ainways, neutrophils migrate out of the blood and into the ainways. This neutrophil response is highly regulated, to ensure that neither too many nor too few cells are recruited Mechanisms responsible for neutrophil airway recruitment are poorly understood, and are the focus of our studies.