Beyond PECAM: Mechanisms of Transendothelial Migration

描述（由申请人提供）：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，以便开发更好的治疗方法，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，如动脉粥样硬化、类风湿关节炎和其他自身免疫性疾病、感染性休克、哮喘和移植排斥等炎症性疾病。炎症反应的一个关键步骤是白细胞从血流中迁移到炎症部位。我们一直在研究渗透的分子和机制，渗透是白细胞穿过毛细血管后小静脉内皮细胞的过程。在该基金的第一个资助期，我们发现了一种分子（CD99）和一种机制（从内部结周室靶向回收膜），在渗滤中发挥重要作用。下一个资助期的目标是确定CD99在妊娠中的作用。具体来说，我们将研究CD99是否存在于这个周膜室中，以及它是否控制渗出过程中围绕迁移的白细胞靶向再循环的一个独特步骤。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。我们将利用这些工具在小鼠急性炎症模型中干扰CD99，研究小鼠CD99在体内炎症反应中的作用。虽然大多数浸润发生在内皮细胞边界（侧结），但在某些情况下，白细胞通过内皮细胞体迁移，这一过程被称为浸润。这其中的分子基础尚不清楚。我们已经设计了一个体外系统，我们可以可靠地刺激皮肤。我们将研究细胞迁移的分子基础，并验证假设，它像在连接处的迁移一样，涉及到膜从结膜周围隔室的靶向再循环。因此，我们将更多地了解两种形式的跨内皮迁移的调控。

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.