Beyond PECAM: Mechanisms of Transendothelial Migration

描述（申请人提供）：这项研究应用的长期目标是更好地了解炎症反应的细胞和分子基础，以便开发更好的疗法，在宿主免疫反应受损的情况下增强炎症反应，并在反应适得其反的情况下抑制炎症反应，例如动脉粥样硬化等炎症性疾病，类风湿性关节炎和其它自身免疫性疾病、败血性休克、哮喘和移植排斥。炎症反应的关键步骤是白细胞从血流中迁移到炎症部位。我们一直在研究导致腹膜透析的分子和机制，腹膜透析是白细胞穿过毛细血管后小静脉内皮细胞的过程中的一个步骤。在该资助的第一个资助期内，我们发现了一种分子（CD99）和一种机制（从内部连接区室中靶向回收膜），它们在渗出中发挥重要作用。下一个资助期的目标是确定CD99如何在渗出中发挥作用。具体来说，我们将研究是否CD99是在这个连接周围的车厢，它是否控制一个独特的步骤，在有针对性的回收这个车厢周围的迁移白细胞在渗出。我们已经克隆了小鼠版本的CD99，并正在开发阻断其功能的试剂。我们将使用这些工具来干扰急性炎症小鼠模型中的CD99，以研究小鼠CD99在体内炎症反应中的作用。虽然大多数渗出发生在内皮细胞边界（横向连接），但在某些情况下，白细胞在称为emperipolesis的过程中通过内皮细胞体迁移。其分子基础尚不清楚。我们已经设计了一个体外系统，在其中我们可以可靠地刺激empipolesis。我们将研究empipolesis的分子基础和测试的假设，它一样，在交界处的迁移，涉及有针对性的回收膜从交界区隔室。因此，我们将更多地了解这两种形式的跨内皮迁移的调节。

DESCRIPTION (provided by applicant): The long-term objectives of this research application is to better understand the cellular and molecular basis of the inflammatory response in order to develop better therapies to augment it in conditions where the host's immune response is compromised, and to inhibit it under conditions where the response is counterproductive, such as in inflammatory diseases like atherosclerosis, rheumatoid arthritis and other autoimmune diseases, septic shock, asthma, and transplant rejection. A critical step in the inflammatory response is the migration of leukocytes out of the bloodstream to the site of inflammation. We have been studying the molecules and mechanisms responsible for diapedesis-the step in this process in which leukocytes pass across the endothelial cells lining postcapillary venules at sites of leukocyte egress. In the first funding period of this grant, we discovered a molecule (CD99) and a mechanism (targeted recycling of membrane from an internal perijunctional compartment) that play significant roles in diapedesis. The aims for the next funding period are to determine how CD99 functions in diapedesis. Specifically, we will examine whether CD99 is in this perijunctional compartment and whether it controls a distinct step in targeted recycling of this compartment around the migrating leukocyte during diapedesis. We have cloned the murine version of CD99 and are developing reagents to block its function. We will use these tools to interfere with CD99 in murine models of acute inflammation to study the role of murine CD99 in the inflammatory response in vivo. While most diapedesis takes place at endothelial cell borders (lateral junctions), under some circumstances leukocytes migrate through the bodies of endothelial cells in a process called emperipolesis. The molecular basis of this is not understood. We have designed an in vitro system in which we can reliably stimulate emperipolesis. We will study the molecular basis of emperipolesis and test the hypothesis that it, like migration at the junctions, involves the targeted recycling of membrane from the perijunctional compartment. We will thus learn more about the regulation of both forms of transendothelial migration.