Force spectroscopy in immunological studies

从历史上看，免疫学研究一直是以蛋白质为中心的奋进，信号事件通常被定义为多肽的生化变化。生物物理因素如何影响这一计划大多被忽视。由我们最后的NSERC资助，我们已经使用原子力显微镜（AFM）为基础的单细胞力光谱（SCFS）来阐明几个重要的免疫学事件，这些事件是由细胞膜的生物物理变化驱动的。我们已经发现，固体物质与表面脂质结合的强度很大，导致双层膜的重排。这种脂质分选招募信号分子并触发吞噬作用和树突细胞活化。因此，我们先前的工作将力和物理干扰的概念引入免疫激活领域。在本提案中，我们实质性地推进了这一概念。我们提供的证据表明，调节性T细胞，一组控制自身免疫必不可少的CD4+ T细胞，强烈结合树突状细胞，并抑制后者的能力，安装不必要的免疫激活。 此外，我们已经发现，吞噬作用可以通过受体独立的膜脂质起源的信号传导启动，作为固体颗粒摄取的通用平台。我们建议使用原子力显微镜耦合到成像仪器，以进一步研究这些相互作用的基本参数和与这些生物物理变化相关的信号事件。这项工作的成果将在免疫学研究中打开新的一页，并将生物物理学作为免疫调节的一个重要方面。这项工作将帮助我们了解膜生物学的几个基本方面，以及细胞膜脂质如何影响免疫信号转导。这将进一步导致我们更好地控制免疫细胞激活，这是加拿大人口健康的核心。

Historically, immunological research has been a protein-centric endeavor, with signaling events often defined as biochemical changes of polypeptides. How biophysical factors play into this scheme has been mostly overlooked. Funded by our last NSERC grant, we have used atomic force microscopy (AFM)-based single cell force spectroscopy (SCFS) to elucidate several important immunological events that are driven by biophysical changes at the cell membrane. We have found that solid substances engage surface lipids with substantial intensity, causing rearrangement of the bilayer membrane. This lipid sorting recruits signaling molecules and triggers phagocytosis and dendritic cell activation. Our previous work therefore introduces the concept of force and physical disturbance into the realm of immune activation. In this proposal, we substantially move this concept forward. We provide evidence that regulatory T cells, a group of CD4+ T cells essential to control autoimmunity, bind strongly to dendritic cells and suppress the latter's ability to mount unwanted immune activation. In addition, we have found that phagocytosis can be initiated via a receptor independent, membrane lipid originated signaling, serving as a generic platform for solid particle uptake. We propose to use AFM coupled to imaging instrument to further study the essential parameters of these interactions and signaling events associated with these biophysical changes. The outcomes of this work will open a new page in immunological research, and introduce biophysics as an essential aspect of immune regulation. The proposed work will help us understand several fundamental aspects of membrane biology and how cell membrane lipids impact immune signal transduction. This will further lead to our better control of immune cell activation that is at the centre of population health in Canada.