Mapping antibody class switch mechanisms and function

抗体是由一种特殊的免疫细胞(B细胞)产生的，是重要的免疫媒介，在病原体和效应细胞之间架起桥梁，保护我们免受感染。抗体分子也可以结合在B细胞表面，在那里它们充当检测目标分子(抗原)的受体。抗体的一部分(可变区)负责与抗原结合，分子的另一端负责激活/调节免疫系统中的不同功能。独一无二的是，抗体可变区可以在短时间内在有机体内进化，以响应感染或疫苗接种，以改善其与抗原的结合。恒定区不会进化，但它可以改变为9个不同类别或亚类中的一个，以便在称为类切换重组(CSR)的遗传过程中改变抗体的功能。抗体的(亚)类在基因组中的排列顺序为：IgM-IGD-IgG3-IgG1-IgA1-IgG2-IgG4-IgE-IgA2；B细胞以IgM和IGD开始生命，激活后切换到另一(亚)类。直到最近，人们还认为CSR对可变区的结合能力没有影响。最近在不同领域(老龄化、埃博拉病毒、艾滋病毒感染、癌症)的研究表明，我们还不完全了解控制将使用哪个(子)类的过程，子类之间的CSR对免疫反应结果的差异，或者CSR可能对可变区域结合属性产生的确切分子影响。治疗性抗体是一种关键的药物资源，是增长最快的药物类别，目前有数千种药物正在开发中。目前获得监管批准/正在接受监管审查的产品大多是IgG1，没有一种是IgA或IgE。随着我们对这些类别的功能了解得更多，我们可能会发现抗体的潜在效用可以增加，例如皮肤癌中的IgE或肠道相关疾病中的IgA。在这个项目中，我们建议利用一个生物信息学家和免疫学家团队的独特专业知识来确定什么因素，无论是细胞外的还是细胞内的，控制CSR。我们将在流感疫苗挑战后的两周内每天监测CSR的进展情况，并将使用抗体结构的计算机模拟来研究抗体分子一侧的变化如何影响另一侧。这三个主要目标中的每一个都将产生一系列结果，其中一些将有助于理解其他目标中的工作，尽管这对它们的成功不是关键。方案的所有部分都需要所有团队在不同程度上提供投入。我们将使用和开发的方法是开创性的，在我们的初步数据中，我们展示了在单细胞基础上细胞培养中类别切换到不同类型抗体的途径。我们将改变这些实验的条件，记录由此产生的变化，并绘制蛋白质-蛋白质和基因相互作用的图谱，以推断控制CSR的分子。这些方法将适用于所有细胞生物科学学科，并将改变细胞生物学研究。人类CSR的图谱和抗体结构的分子建模也将产生供其他人使用的新工具，我们以前已经成功地做到了这一点，并在几个领域拥有庞大的全球用户群体。我们团队的跨学科性质意味着我们对如何设计用户友好和灵活的工具具有洞察力，所有数据和工具都将在集体资源“BHIVE”中公开提供。我们还将以这样一种方式运行我们的项目，即最大限度地提高我们所有团队的跨学科熟悉度，并确保我们的ECR有一个跳板，进入他们未来的职业生涯。

Antibodies are produced by a specialised immune cell (B cell) and act as important immune mediators, bridging between pathogens and effector cells to protect us from infection. Antibody molecules can also exist bound to the B cell surface where they act as receptor for detecting target molecules (antigens). Their versatility is immense, they are used to make diagnostics, research tools and therapeutics.One part of the antibody (variable region) is responsible for binding to the antigen, the other end of the molecule is responsible for activating/mediating different functions in the immune system. Uniquely, the antibody variable region can evolve within the organism within a short timescale, in response to infection or vaccination, to improve its binding to the antigen. The constant region does not evolve, but it can be changed to one of 9 different classes or subclasses in order to change the function of the antibody in a genetic process known as Class Switch Recombination (CSR). The (sub)classes of antibody are arranged in the genome in this order: IgM-IgD-IgG3-IgG1-IgA1-IgG2-IgG4-IgE-IgA2; a B cell starts life with IgM and IgD and after activation switches to another (sub)class. Until very recently it was thought that CSR had no effect on the binding abilities of the Variable region. Recent research in different areas (Ageing, Ebola, HIV infection, Cancer) indicates that we don't fully understand the processes that control which (sub)class will be used, the difference that CSR between subclasses makes to the outcome of an immune response or the exact molecular effects that CSR might have on the variable region binding properties. Therapeutic antibodies are a critical pharmaceutical resource, being the fastest growing class of pharmaceuticals, with thousands now in the development pipeline. Current products with regulatory approval/undergoing regulatory review are mostly IgG1 whilst none are IgA or IgE. As we understand more about the functions of these classes, we may find that the potential utility of antibodies can be increased, such as IgE in skin cancers or IgA in gut-related disorders.In this programme we propose to harness the unique expertise of a team of bioinformaticians and immunologists to determine what factors, both outside the cell and inside the cell, control CSR. We will monitor how CSR progresses with time on a daily basis for a fortnight after challenge with the flu vaccine and we will use computer modelling of antibody structures to investigate how changing one side of the antibody molecule may affect the other. Each of these three main objectives will produce a range of results, some of which will help to understand the work in the other objectives, although would not be critical for their success. All parts of the programme require input from all the team to varying levels. The methods we will use and develop are ground-breaking, in our preliminary data, we show pathways of class switching to different types of antibody in cell culture on a single cell basis. We will alter the conditions of these experiments, note the resulting changes and map the protein-protein and gene interactions to deduce what molecules are controlling CSR. These methods will be applicable in all cellular Bioscience disciplines and will transform cell biology research. The mapping of human CSR and the molecular modelling of antibody structure will also result in new tools for others to use, we have successfully done this before and have large global user groups in several areas. The interdisciplinary nature of our team means that we have insight into how to design tools that are user friendly and flexible, all data and tools will be made publicly available in a collective resource "BHive". We will also run our programme in such a way as to maximise the interdisciplinary familiarisation across all our teams and ensure our ECRs have a springboard into their future careers.