Alternative Mechanisms of Monocyte Transendothelial Migration in Inflammation

项目摘要 炎症在体内起保护作用，以对抗感染并介导伤口愈合; 然而，如果不加控制或未解决，炎症反应可能变得有害。大多数病理学， 包括动脉粥样硬化、血管炎和缺血/再灌注损伤--这可能加剧潜在的 并发症如心肌梗塞和中风-是由于功能失调的炎症。靶向 因此，炎症可以提供对抗炎性疾病的手段。这一目标可以通过以下方式实现： 针对所有炎症的共同过程：白色血细胞的定向运动 白细胞（WBC）从循环进入受影响的组织。在这个过程中，跨内皮迁移（TEM），白细胞迁移 内皮细胞（EC）内衬血管的横向边界之间进入炎症部位。TEM是一个 这是炎症反应中的关键步骤，因为它是WBC进入炎症组织之前的最终步骤。 TEM的成功阻断将排除炎症背景下的组织损伤，因此是一种有效的方法。 治疗目标 TEM由WBC和EC上的表面粘附分子之间的相互作用介导， 在从EC侧缘再循环室（LBRC）运输膜的EC内信号传导中， 血管周围的囊泡管状结构，TEM的网站。这提供了所需的额外表面积， 相邻EC之间的WBC迁移。贩运LBRC是TEM的最终共同途径， WBC类型或炎症刺激。阻断关键粘附分子或下游EC信号传导 在体外和体内，通路阻断WBC的TEM达80-90%。然而，残留的迁移率仍然存在， 10- 20%，提出了WBC的特定亚群是否对TEM阻断具有抗性的问题 以及未阻断的WBC是否使用替代信号传导途径来募集LBRC以进行迁移。 目的：我将对克服TEM阻断的单核细胞进行表型表征，以确定它们是否 代表一个独特的单核细胞亚群。我将探究这些细胞在一个 体外TEM模型和鼠炎症模型。这将允许识别表面 受体/信号传导途径，可以靶向阻断所有循环单核细胞从细胞中退出。 在阻断100%炎症的情况下，血管是至关重要的。AIM II将询问机制 允许这些单核细胞使用替代的迁移途径。我会利用引导式体外筛选 方法和体内真实的时间活体共聚焦显微镜检查，以验证我的体外结果， 在TEM步骤中直接起作用的机制。该项目将揭示替代TEM途径， 在某些病理条件下可能是重要的，并提醒我们身体可以补偿的方式 传统TEM通路的慢性阻塞。

Project Summary Inflammation serves a protective role in the body to fight infection and mediate wound healing; however, the inflammatory response can become deleterious if left uncontrolled or unresolved. Most pathology, including atherosclerosis, vasculitis, and ischemia/reperfusion injury—which can exacerbate potential comorbidities such as myocardial infarcts and stroke—is due to dysfunctional inflammation. Targeting inflammation could thus provide the means to combat inflammatory disease. This objective can be realized by targeting a common process that underlies all inflammation: the directed movement of white blood cells (WBCs) from circulation into affected tissue. In this process, transendothelial migration (TEM), WBCs migrate between lateral borders of endothelial cells (ECs) lining blood vessels to enter sites of inflammation. TEM is a critical step in the inflammatory response as it is the ultimate step preceding WBC access to inflamed tissue. Successful blocking of TEM would preclude tissue damage in an inflammatory context and is thus a therapeutic goal. TEM is mediated by interactions between surface adhesion molecules on the WBC and ECs, resulting in signaling within ECs that traffics membrane from the EC lateral border recycling compartment (LBRC), a perivascular vesiculotubular structure, to the site of TEM. This provides additional surface area required for WBC migration between adjacent ECs. Trafficking of LBRC is the final common pathway for TEM regardless of WBC type or inflammatory stimulus. Blocking critical adhesion molecules or downstream EC signaling pathways blocks TEM of WBC by 80-90% in vitro and in vivo. However, residual transmigration rate remains 10-20%, raising the question as to whether specific subpopulation(s) of WBC are resistant to TEM blockade and whether non-blocked WBCs use alternative signaling pathways to recruit the LBRC to transmigrate. AIM I will phenotypically characterize monocytes that overcome TEM blockade to determine if they represent a distinct monocyte subset. I will interrogate the mechanism by which these cells transmigrate in an in vitro TEM model and in murine models of inflammation. This will allow for the identification of surface receptors/signaling pathways that can be targeted to block the exit of all circulating monocytes from the vasculature in situations in which blocking 100% of inflammation is critical. AIM II will interrogate mechanisms that allow these monocytes to use alternative transmigration pathways. I will utilize a guided in vitro screening approach and in vivo real time intravital confocal microscopy to validate my in vitro results by inspecting mechanisms functioning at the TEM step directly. The project will shed light on alternative TEM pathways that may be important under some pathologic conditions and alert us to ways in which the body may compensate for the chronic blockade of traditional TEM pathways.