Bio-Mechanics of Directional Migration of Leukocytes

 产品说明：先天性和适应性免疫反应涉及白细胞从血流中募集到感染和炎症部位。到达该位置后，白细胞清除入侵者并开始消化和修复受损组织的过程。然而，当身体不能适当调节白细胞的募集时，炎症可能会变成慢性的，导致不可逆的组织损伤和功能丧失。 风湿性关节炎、炎症性肠病、1型糖尿病和多发性硬化症都是由白细胞不受控制的募集引起的自身免疫性疾病的例子。虽然许多研究致力于识别白细胞募集中涉及的特定生化过程的级联，但对驱动它们迁移的机械事件，特别是它们如何产生必要的牵引力以穿过血管壁并进一步穿过三维（3-D）血管外空间，知之甚少。因此，本研究的主要目的是提供连接特定细胞分子过程（即，粘附动力学、肌动蛋白周转和肌球蛋白II收缩）与细胞力的产生有关，所述细胞力通过使用新的3D傅立叶牵引力显微镜（3DFTFM）技术以及遗传和药理学操作来调节白细胞外渗及其随后在3-D血管外组织中的定向迁移。为了实现这一目标，我们提出了三个具体目标。我们将首先描述白细胞在平坦表面上爬行所施加的三维牵引力的时间和空间生成（目标1）;然后研究调节穿过血管内皮单层和基底膜的机械过程（目标2）;最后，我们将开发一种新的弹性成像3DTFM来确定牵引应力和非牵引应力，细胞外基质的线性材料特性，以阐明在3-D环境中调节白细胞趋化性迁移机制的分子机制（目标3）。所提出的体外方法克服了测量驱动白细胞外渗和迁移的3-D牵引力的许多现有挑战，并建立在我们的多学科生物学家和工程师团队积累的丰富经验的基础上，他们在过去七年中一直在研究阿米巴细胞迁移的机制。这项研究的结果将导致对白细胞运动机制的更全面的理解，而不是迄今为止的理解，并有可能帮助开发新的方法，这些方法可以针对特定的机械过程来抑制（或减缓）白细胞运动，并帮助设计补充方案来治疗炎症性疾病。

 DESCRIPTION: The innate and adaptive immune response involves the recruitment of leukocytes from the blood stream to the site of infection and inflammation. Upon reaching the location, leukocytes clear invaders and begin the process of digesting and repairing damaged tissues. However, when the body fails to properly regulate the recruitment of leukocytes, the inflammation can become chronic, resulting in irreversible tissue injury and loss of functionality. Rheumatoid arthritis, inflammatory bowel disease, type-1 diabetes, and multiple sclerosis are all examples of autoimmune diseases caused by the uncontrolled recruitment of leukocytes. While much research has been dedicated to the identification of the cascade of specific biochemical processes involved in the recruitment of leukocytes, much less is known about the mechanical events driving their migration, in particular how they generate the necessary traction forces to cross the vascular wall and further traverse the three- dimensional (3-D) extravascular space. Thus, the main objective of this study is to provide the much needed complementary information connecting specific cell molecular processes (i.e., adhesion dynamics, actin turnover, and myosin II contraction) to the generation of cellular forces that regulate leukocyte extravasation and their subsequent directional migration in 3-D extravascular tissues through the use of novel 3D Fourier Traction Force Microscopy (3DFTFM) techniques and genetic and pharmacological manipulations. To achieve this objective, we propose three Specific Aims. We will first characterize the temporal and spatial generation of 3-D traction forces exerted by leukocytes crawling on flat surfaces (Aim 1); we will then investigate the mechanical processes regulating transmigration across the vascular endothelial monolayer and the basement membrane (Aim 2); and finally, we will develop a novel Elastographic 3DTFM to determine both traction stresses and the non-linear material properties of the Extra Cellular Matrix to elucidate the molecular mechanisms regulating the mechanics of leukocytes' chemotactic migration in 3-D environments (Aim 3). The proposed in vitro approach overcomes a number of existing challenges to measuring the 3-D traction forces driving leukocyte extravasation and migration and builds on the extensive experience accumulated by our multidisciplinary team of biologists and engineers who have been studying the mechanics of amoeboid cell migration for the last seven years. The outcome of this research will result in a far more comprehensive understanding of the mechanics of leukocyte motility than that available to date and will have the potential to aid the development of new approaches that could target specific mechanical processes to inhibit (or slow down) leukocyte motility and help in the design of complementary regimens to treat inflammatory diseases.