Evolution of antibody affinity modification in fishes

鱼类抗体亲和力修饰的演变

• 批准号: RGPIN-2020-05979
• 负责人: Magor, Bradley
• 金额: $ 2.62万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=718139
• 关键词: Evolution; antibody; affinity; modification; fishes

Two desired outcomes of vaccination are: 1) immunologic memory, whereby there is a large increase in the number of long-lived immune memory cells that will be able to recognize the disease that you were vaccinated against. 2) improved recognition of disease organism by tweaking the genes of the molecules used to recognize the pathogen. This latter process termed antibody affinity maturation involves the intentional mutation of a select part of our genome in the hopes of improving the design of the antibodies that it encodes, so they can better bind to a pathogen that the organism has been exposed to. Mutation of the genome is a delicate business that must be tightly regulated so that unintended mutation doesn't lead to cancers or autoimmune diseases. Our research studies the conditions in which the mutation process takes place. Specifically we study how this system operates in the most primitive of organisms that are able to make antibodies the fishes. Sharks and fishes seem to have a very simplified method of altering their antibody genes. By studying the simpler system (compared to mammals) we hope to understand the most basic cellular and molecular necessities for how the system works, and what can cause it to go wrong as it does in many autoimmune diseases. In autoimmune diseases the antibody genes are altered so they mistake our own tissues for that of a pathogen. The conditions under which this happens in mammals look similar to how fish drive the mutation process. It is possible that what occurs normally in fish parallels what happens in some mammalian diseases, and studying fish may open windows to understanding the development of auto-immunity in humans. Specifically we are studying a mutational system that tweaks existing antibodies and makes them a better fit for the pathogen that they recognize. Our first goal is to verify that fish have the same sort of mutational system as mammals (i.e. that fish are a model system to study mammalian mutational systems). This involves studying the mutations that accumulate in the antibody genes from tissues in which we believe the process is happening. Our second goal is to study how cells that have undergone mutations are checked to make sure they are not making antibodies to self i.e. autoimmune antibodies. At this point they have been sentenced to death and if they can't still recognize the pathogen then they will die. Some of the cells involved in the 'checking' appear to be different in fish and we are verifying that point. Lastly we are developing transgenic cells and fish that can be used to study other components of the antibody affinity maturation. The cells and fish are genetically engineered to 'light-up' all cells in which AID is active thereby allowing us to observe the cells involved in the mutational system as they exist in translucent zebrafish.

疫苗接种的两个预期结果是：1）免疫记忆，即长寿命免疫记忆细胞的数量大幅增加，这些细胞将能够识别您所接种疫苗所针对的疾病。 2）通过调整用于识别病原体的分子的基因来提高对疾病生物体的识别。后一个过程称为抗体亲和力成熟，涉及对我们基因组的选定部分进行有意突变，以期改进其编码的抗体的设计，以便它们能够更好地与生物体所接触的病原体结合。基因组突变是一项微妙的事情，必须受到严格监管，以免意外突变导致癌症或自身免疫性疾病。我们的研究研究突变过程发生的条件。具体来说，我们研究了这个系统如何在能够产生抗体的最原始的生物体（鱼类）中运作。鲨鱼和鱼类似乎有一种非常简单的改变抗体基因的方法。通过研究更简单的系统（与哺乳动物相比），我们希望了解该系统如何工作的最基本的细胞和分子必要性，以及是什么导致它在许多自身免疫性疾病中出现问题。在自身免疫性疾病中，抗体基因发生改变，因此它们将我们自己的组织误认为是病原体的组织。哺乳动物中发生这种情况的条件看起来与鱼类驱动突变过程的方式相似。鱼类中正常发生的情况可能与某些哺乳动物疾病中发生的情况相似，研究鱼类可能为了解人类自身免疫的发展打开一扇窗户。具体来说，我们正在研究一种突变系统，该系统可以调整现有的抗体，使它们更适合它们识别的病原体。我们的第一个目标是验证鱼类具有与哺乳动物相同的突变系统（即鱼类是研究哺乳动物突变系统的模型系统）。这涉及研究我们认为正在发生该过程的组织中抗体基因中积累的突变。我们的第二个目标是研究如何检查发生突变的细胞，以确保它们不会产生针对自身的抗体，即自身免疫抗体。此时他们已经被宣判了死刑，如果他们还不能识别病原体，那么他们就会死。参与“检查”的一些细胞在鱼类中似乎有所不同，我们正在验证这一点。最后，我们正在开发转基因细胞和鱼，可用于研究抗体亲和力成熟的其他成分。这些细胞和鱼经过基因工程改造，可以“点亮”所有 AID 活跃的细胞，从而使我们能够观察存在于半透明斑马鱼中的参与突变系统的细胞。