Inflammatory Mechanisms in Arterioles and Venules

描述(由申请人提供)： 急性炎症表现为微血管的两个主要反应：1)白细胞-内皮细胞(EC)相互作用增加，最终导致白细胞从血管腔中迁移；2)微血管壁对溶质和水的通透性增加，导致组织水肿。中性粒细胞与血管壁的相互作用是炎症过程中发生的一系列事件的中心，最终导致微血管屏障功能的改变，并参与启动溶质通透性的变化。因此，本申请中提出的研究的总体目标是检验这一普遍假设，即小动脉和小静脉炎症反应的潜在机制是根本不同的，无论是就白细胞在调节溶质通透性变化中的作用而言，还是关于这两个关键的血管屏障功能方面是否共享基本的共同信号机制(特别是那些依赖于钙的信号机制)。一般的目标将在啮齿动物骨骼肌的完整小动脉和小静脉中实现，实现以下目标。我们将使用直接测量完整的、自灌流的啮齿动物(小鼠、大鼠)原位骨骼肌小动脉和小静脉的白细胞-EC相互作用、通透性和EC钙变化，以确定中性粒细胞激活通透性变化的机制，并确定这些在小动脉和小静脉中的差异。假设1：ICAM-1结扎足以增加小动脉和小静脉的溶质通透性并诱导白细胞渗出。假设1A：通过中性粒细胞释放的旁分泌产物(CAP37)单独连接ICAM-1可以增加微血管对溶质和白细胞的渗透性。假设2：内皮细胞内钙离子的增加足以增加溶质的通透性，并诱导小动脉和小静脉中的白细胞渗出。假设2A：选择素和ICAM-1结扎都与EC钙离子增加和通透性增加有关。在相同条件下对两种骨骼肌微血管的研究将使我们能够在单一的、定义良好的完整血管模型中识别调节屏障功能的主要机制和重要的一般原则。了解微血管屏障功能的调节机制及其在小动脉和小静脉系统之间的潜在变化对于理解炎症性疾病的进展具有直接的意义。

DESCRIPTION (provided by applicant): Acute inflammation is typified by two principal responses in microvessels: 1) an increase in leukocyte-endothelial cell (EC) interactions culminating in leukocyte emigration from the vascular lumen; and 2) increased permeability of the microvascular wall to solutes and water, resulting in tissue edema. Neutrophil interactions with the vessel wall are central to the cascade of events that occurs in inflammation to ultimately result in the alteration in microvascular barrier function, and have been implicated in initiation of solute permeability changes. The overall goal of the studies proposed in this application is therefore to test the general hypothesis that mechanisms underlying inflammatory responses in arterioles and venules are fundamentally different, both with respect to the role of leukocytes in regulation of solute permeability changes, and with respect to whether these two critical aspects of vascular barrier function share essential common signaling mechanisms (specifically those that are Ca2+ dependent). The general goal will be approached in intact arterioles and venules of rodent skeletal muscle, by undertaking the following aims. We will use direct measurements of leukocyte-EC interactions, permeability and EC Ca2+ changes in intact, autoperfused in situ rodent (mice, rats) skeletal muscle arterioles and venules, to define the mechanisms for neutrophil activation of permeability changes, and determine how these differ in arterioles vs. venules. Hypothesis 1: ICAM-1 ligation is sufficient to increase solute permeability and to induce leukocyte diapedesis in both arterioles and venules. Hypothesis 1A: Microvessel permeability to solutes and leukocytes can be increased above that due to ICAM-1 ligation alone by a paracrine product (CAP37) release from neutrophils. Hypothesis 2: An increase in EC Ca2+ is sufficient to increase solute permeability and to induce leukocyte diapedesis in both arterioles and venules. Hypothesis 2A: Both Selectin and ICAM-1 ligation are associated with increased EC Ca2+ and with increased permeability. The study of both skeletal muscle microvasculatures under the same conditions will enable the major mechanisms and important general principles governing regulation of barrier function to be identified in a single, well defined intact vessel model. Understanding mechanisms for regulation of microvascular barrier function, and their potential variation between arteriolar and venular system is of immediate relevance to understanding the progress of inflammatory diseases.