Neutrophil Migration in Three Dimensions

描述（由申请方提供）：中性粒细胞对于先天性宿主防御至关重要，因此外周血中这些细胞数量的减少会增加对危及生命的感染的易感性。除了产生足够的数量外，宿主防御还取决于中性粒细胞有效发挥作用的能力。白细胞粘附缺陷患者的中性粒细胞数量正常，但他们在整合素表达方面存在遗传缺陷。慢性肉芽肿病患者的中性粒细胞不能产生足够水平的杀微生物氧化物质。在这两种情况下，这些功能缺陷使患者易于感染机会性病原体、复发性感染发作和损伤伤口愈合。或者，过度的嗜中性粒细胞反应可导致以附带组织损伤为特征的疾病状态，例如呼吸窘迫综合征、哮喘、炎性肠病、缺血/再灌注损伤、血管炎和类风湿性关节炎。因此，中性粒细胞必须对感染或损伤执行充分但精细调节的反应，以促进恢复稳态。 中性粒细胞浸润身体中的任何受损组织以引发炎症反应，而不管不同身体组织在组成和结构上提供实质性变化的事实。像所有细胞一样，中性粒细胞表达一组特异性细胞表面受体，其引发对微环境中的生物元素的功能性反应。很明显，物理 微环境的性质，例如其相对刚度，也是功能的重要调节器。中性粒细胞用于响应物理线索的机制并不像受体-配体诱导的反应那样清楚。我们实验室以前的工作假设，软的，弹性的组织，如大脑，可能会影响中性粒细胞功能不同的硬组织，如皮肤或肌肉。事实上，中性粒细胞的粘附，牵引力和迁移的生产显着不同的纤维连接蛋白涂层的基质，仅在僵硬。硬度均在体内组织硬度的生理范围内。尽管该模型提供了比刚性材料如塑料和玻璃更相关的生理基质，但其局限性在于炎性中性粒细胞在三维组织环境中发挥作用。 这是一个建议，工程师可调的3D体外系统，将允许中性粒细胞进行研究的条件下，更密切地模拟组织微环境。此外，我们的系统的新奇在于，一个给定的细胞可以在2维，然后在3维，从而隔离作为一个单一的实验变量的尺寸跟踪。实验还将确定与2D系统相比，整合素是否介导3D系统中牵引力的产生并控制中性粒细胞的迁移。考虑器官和组织的显著机械特征的3D体外系统将提供更好的手段来预测用于控制炎症的治疗剂的有效性。

DESCRIPTION (provided by applicant): Neutrophils are essential to innate host defense such that a decrease in the number of these cells in the peripheral blood presents heightened susceptibility to life threatening infections. In addition to being produced in adequate number, host defense also depends on the ability of neutrophils to function effectively. Patients with Leukocyte Adhesion Deficiency have normal numbers of neutrophils but they are genetically deficient in expression of integrins. Neutrophils in patients with Chronic Granulomatous Disease fail to produce adequate levels of microbiocidal oxidative species. In both cases, these functional deficits predispose patients to infections with opportunistic pathogens, recurrent infectious episodes and impairment of wound healing. Alternatively, an excessive neutrophil response can result in disease states characterized by collateral tissue damage such as respiratory distress syndrome, asthma, inflammatory bowel disease, ischemia/reperfusion injury, vasculitis and rheumatoid arthritis. Therefore, neutrophils must execute a sufficient but finely regulated response to infection or injury to promote a return to homeostasis. Neutrophils infiltrate any compromised tissue in the body in order to initiate an inflammatory response regardless of the fact that different bodily tissues offer substantial variations in composition an structure. Like all cells, neutrophils express a set of specific cell surface receptors that elicita functional response to biological elements within a microenvironment. It is clear that the physical nature of a microenvironment, such as its relative stiffness, is also an important regulator of function. The mechanisms that neutrophils use to respond to physical cues are not as clear as they are for receptor-ligand induced responses. Prior work from our laboratory hypothesized that soft, elastic tissues such as brain, may affect neutrophil function differently than stiffer tissues such as skin or muscle. Indeed, neutrophil adhesion, production of traction forces and migration were significantly different on fibronectin-coated matricies that varied only in stiffnes. The stiffnesses were all within the physiological range of tissue stiffnesses found in the body. Although this model provided a more relevant physiologic substrate than rigid materials such as plastic and glass, it is limited in that inflammatory neutrophils function within a 3-dimensional tissue environment. This is a proposal to engineer a tunable 3D in vitro system that will permit neutrophils to be studied under conditions that more closely model a tissue microenvironment. Moreover, the novelty of our system lies in that a given cell can be tracked in 2-dimensions and then in 3-dimensions thereby isolating dimension as a single experimental variable. Experiments will also determine whether integrins mediate the generation of traction forces and control migration of neutrophils in 3D as compared to 2D systems. A 3D in vitro system that accounts for the salient mechanical features of organs and tissues will provide a better means to predict effectiveness of therapeutics indicated for control of inflammation.