Molecular Mechanisms for Carbohydrate Presentation to CD4+ T cells by MHCII Pathway

项目摘要/摘要 大多数致病菌表达表面碳水化合物，称为衣壳多糖(CPSS)。CPSS是 重要的候选疫苗，因为它们位于细菌的最外表面，而且它们有 不同的结构。这两个特征使得它们很容易被免疫系统访问和识别 从而导致B细胞产生CPS特异性抗体。诱导CPS特异性 获得性免疫反应(即T细胞介导的B细胞反应)，CPSS与载体蛋白偶联， 这种结合产物被称为糖结合疫苗。由于对他们的了解不够 免疫激活机制，目前的糖结合疫苗策略已经达到饱和，并 对过去的经验共轭方法进行了很大的修改。这一代人的生产 糖结合疫苗是基于试验和错误的，不利用特定的科学知识来 最大限度地刺激与产生保护性免疫球蛋白有关的关键免疫细胞(即辅助T细胞) 抗体。以碳水化合物为基础的疫苗研究急需一个新的视角。具有…的潜力 建立一个新的范式，我们之前的发现和初步数据表明，哺乳动物 CD4T细胞谱系包含一组碳水化合物特异性T细胞(即Tabs)，它们识别 碳水化合物表位。在这里，我们建议扩展我们以前的发现，并定义分子 模型糖结合疫苗碳水化合物表位激活Tcarb的机制。在目标1中 这项建议我们将阐明碳水化合物呈递的主要组织相容性的结构要求 抗原提呈细胞(APC)表面或纯化的MHCII蛋白 蛋白质通过相互作用研究。在目标2中，我们将从结构和功能上描述T细胞受体(TCR) 糖链抗原表位的识别。我们相信，我们提出的研究将创造一个新的平台 开发富含Tcarb功能表位的基于知识的糖结合疫苗。使用 Tcarb激活机制和糖链表位结构的发现，我们可以设计和开发 新一代糖结合疫苗将引发强大和持久的免疫反应以保护 不受细菌感染。

Project Summary/Abstract Most pathogenic bacteria express surface carbohydrates called capsular polysaccharides (CPSs). CPSs are important vaccine candidates given that they are located on the outermost surface of bacteria and they have distinct structures. These two features make them easily accessible and distinctly recognizable by immune surveillance, therefore resulting in production of CPS specific antibodies by B cells. To induce a CPS specific adaptive immune response (i.e., T cell-mediated B cell response), CPSs are conjugated with carrier proteins, and the conjugation products are called glycoconjugate vaccines. Due to insufficient understanding of their immune activation mechanisms, current glycoconjugate vaccine strategies have reached saturation and are largely modifications of past empirical conjugation methods. The production of the current generation of glycoconjugate vaccines is based on trial and error and does not make use of specific scientific knowledge to maximize stimulation of critical immune cells (i.e., helper T cells) involved in producing protective IgG antibodies. A new perspective to carbohydrate-based vaccine research is much needed. With the potential of establishing a new paradigm, our previous discovery and preliminary data demonstrate that the mammalian CD4+ T cell repertoire contains a population of carbohydrate-specific T cells (i.e., Tcarbs) that recognize carbohydrate epitopes. Here, we propose to expand on our previous discovery and define the molecular mechanisms for Tcarb activation by carbohydrate epitopes from a model glycoconjugate vaccine. In Aim 1 of this proposal we will elucidate structural requirements for carbohydrate presentation by major histocompatibility complex class II (MHCII) proteins on the surface of antigen presenting cells (APCs) or as purified MHCII proteins via interaction studies. In Aim 2 we will structurally and functionally characterize T cell receptor (TCR) recognition of glycan epitopes by Tcarbs. We believe our proposed studies will create a new platform to develop knowledge-based glycoconjugate vaccines that are enriched for functional Tcarb epitopes. Using the discovery of Tcarb activation mechanisms and of structures of glycan epitopes, we can design and develop new-generation glycoconjugate vaccines that will elicit strong and long lasting immune response to protect from bacterial infections.