Beyond PECAM: Mechanisms of Transendothelial Migration

描述(申请人提供)：本研究申请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、类风湿性关节炎和其他自身免疫性疾病、败血症休克、哮喘和移植排斥反应。炎症反应中的一个关键步骤是白细胞从血液中迁移到炎症部位。我们一直在研究负责汇合的分子和机制--在这个过程中，白细胞穿过白细胞流出部位的毛细血管后小静脉内皮细胞。在这笔赠款的第一个资助期，我们发现了一种分子(CD99)和一种机制(从内部交界处回收膜)，它们在发育术中发挥着重要作用。下一个资助期的目标是确定CD99如何在糖尿病中发挥作用。具体地说，我们将检查CD99是否在这个周围室中，以及它是否控制着在发育期围绕迁移的白细胞的这个室的靶向循环的不同步骤。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，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(侧连接)，但在某些情况下，白细胞通过内皮细胞体内迁移，这一过程称为内皮化。这其中的分子基础还不清楚。我们已经设计了一种体外系统，在其中我们可以可靠地刺激黄褐斑。我们将研究黄褐斑的分子基础，并检验这一假设，即它就像在交界处的迁移一样，涉及到从周边室中有针对性地回收膜。因此，我们将更多地了解这两种形式的跨内皮细胞迁移的调节。

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.