Transendothelial Migration of Leukocytes: Developing New Paradigms in Health and Disease

项目总结/摘要 经内皮细胞迁移（TEM），或渗出，是白细胞在紧密的细胞间挤压的步骤。 排列在炎症部位毛细血管后小静脉上的并置内皮细胞。大多数好的坏的 而炎症则是在白细胞穿过血管后发生的。的透彻理解 因此，调节TEM的分子和机制应该增强我们控制这一过程的能力。 治疗上因此，我的实验室已经研究这个过程30年了。我们做了一些 在该领域的开创性发现，包括鉴定和发现：1.血小板/内皮细胞粘附 分子-1（PECAM）和CD99作为TEM和2.其下游信号传导 3.侧缘循环室（LBRC），一个相互连接的网状结构， 4.内皮细胞表面的分子是一种小泡状的膜，它沿着内皮细胞的边界局部扩张; 参与TEM（PECAM、CD99等）当白细胞通过 TEM的作用促进了某些单核细胞向树突状细胞的分化; 白细胞的旁细胞和跨细胞TEM使用相同的机器和机制。 无论我们是从白细胞还是内皮细胞的角度来看待TEM， 粘附/信号分子、细胞内信号通路、膜动力学或内皮细胞 超微结构，我们一致和独立地聚集在一个最终的共同机制，无论 无论我们研究的是中性粒细胞、单核细胞还是T细胞， 研究的模型：TEM要求LBRC沿着微管有针对性地移动到 白细胞迁移。我们研究的所有分子都是为了激活这个机制。的任何东西 抑制这种"LBRC的靶向再循环"在体外和体内抑制TEM 80 - 90%。 现有抗炎疗法的最大缺点是，它们也会阻断有益的炎症反应。 炎症我们已经开发了生物化学和遗传工具，以选择性地阻止有针对性的循环， LBRC和因此TEM在炎症性疾病的多种体内模型中的应用。由于这些试剂和诱导剂 EC选择性基因敲除小鼠只影响EC，先天性和适应性炎症反应的所有其他方面 保持完整由于我们只能阻断TEM的80 - 90%，因此10 - 20%的白细胞逃脱了阻断， 进入能够引起正常炎症反应的组织。我们的初步数据显示， 适应不良炎症的强度，而不干扰宿主的能力， 炎症反应和保持健康。我们将在一些急性和慢性炎症模型中检验这一假设。 慢性炎症我们还将利用我们的能力，选择性地阻止TEM在选定的时间点，以研究的作用 TEM在疾病的发生、发展和消退中的作用。调节细胞生长的分子和机制 肺血管床中的TEM未知。我们将识别它们并与体循环进行比较。

Project Summary/Abstract Transendothelial migration (TEM), or diapedesis, is the step in which leukocytes squeeze between tightly apposed endothelial cells that line the post-capillary venules at sites of inflammation. Most of the good, the bad, and the ugly of inflammation occurs after leukocytes cross blood vessels. A thorough understanding of the molecules and mechanisms that regulate TEM should therefore enhance our ability to control the process therapeutically. Therefore, my lab has been studying this process for 30 years. We have made some of the seminal discoveries in the field, including the identification and discovery of: 1.Platelet/endothelial cell adhesion molecule-1 (PECAM) and CD99 as major selective regulators of TEM and 2. their downstream signaling pathways leading to TEM; 3.The lateral border recycling compartment (LBRC), an interconnected reticulum of tubule-vesicular membrane that recycles locally along the endothelial cell borders; 4.That the surface molecules involved in TEM (PECAM, CD99, etc.) work sequentially in the process as the leukocyte passes through the endothelial cell border; 5.That the act of TEM promotes differentiation of some monocytes into dendritic cells; 6. That paracellular and transcellular TEM of leukocytes use the same machinery and mechanisms. Whether we approached TEM from the standpoint of the leukocyte or the endothelial cell, the surface adhesion/signaling molecules, the intracellular signaling pathways, membrane dynamics, or endothelial cell ultrastructure, we consistently and independently converged on a final common mechanism regardless of whether we were studying neutrophils, monocytes, or T cells; regardless of the inflammatory conditions or models studied: TEM required the targeted movement of the LBRC along microtubules to the site at which the leukocyte was migrating. All of the molecules that we studied worked to activate this mechanism. Anything that inhibited this “targeted recycling of the LBRC” inhibited TEM by 80-90% in vitro and in vivo. The biggest shortcoming of existing anti-inflammatory therapies is that they also block beneficial inflammation. We have developed biochemical and genetic tools to selectively block targeted recycling of the LBRC and hence TEM in multiple in vivo models of inflammatory disease. Since these reagents and inducible EC-selective knockout mice only affect EC, all other aspects of the innate and adaptive inflammatory responses remain intact. Since we are only able to block TEM by 80–90%, the 10–20% of leukocytes that escape blockade enter the tissues able to mount a normal inflammatory response. Our preliminary data show that we can diminish the intensity of maladaptive inflammation without interfering with the ability of the host to mount desirable inflammatory responses and remain healthy. We will test this hypothesis in a number of models of acute and chronic inflammation. We will also use our ability to selective block TEM at selected time points to study the role of TEM in the initiation, progression, and resolution of disease. The molecules and mechanisms that regulate TEM in the pulmonary vascular bed are unknown. We will identify them and compare to the systemic circulation.