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

项目概要/摘要 大多数病原菌表达称为荚膜多糖（CPS）的表面碳水化合物。CPS是 重要的候选疫苗，因为它们位于细菌的最外表面， 不同的结构。这两个特征使它们很容易被免疫系统访问和识别。 监视，因此导致由B细胞产生CPS特异性抗体。诱导一种CPS特异性的 适应性免疫应答（即，T细胞介导的B细胞应答），CPS与载体蛋白缀合， 结合产物称为糖结合疫苗。由于对自己的认识不足， 免疫激活机制，目前的糖缀合物疫苗策略已经达到饱和， 很大程度上是对过去经验共轭方法的修改。当前一代的生产 糖缀合物疫苗是基于试验和错误，不利用特定的科学知识， 使关键免疫细胞的刺激最大化（即，辅助性T细胞）参与产生保护性IgG 抗体的一个新的视角，以碳水化合物为基础的疫苗研究是非常必要的。发生可能 建立一个新的范例，我们以前的发现和初步数据表明，哺乳动物 CD 4 + T细胞库包含碳水化合物特异性T细胞群（即，Tcarbs）， 碳水化合物表位。在这里，我们建议扩大我们以前的发现，并定义分子 通过来自模型糖缀合物疫苗的碳水化合物表位激活Tcarb的机制。目标1， 本建议我们将通过主要组织相容性阐明碳水化合物呈递的结构要求 抗原呈递细胞（APC）表面上的II类复合物（MHCII）蛋白或纯化的MHCII 蛋白质相互作用研究。在目标2中，我们将在结构和功能上表征T细胞受体（TCR） Tcarbs对聚糖表位的识别。我们相信，我们提出的研究将创造一个新的平台， 开发基于知识的糖缀合物疫苗，其富含功能性Tcarb表位。使用 发现Tcarb激活机制和聚糖表位的结构，我们可以设计和开发 新一代糖缀合物疫苗，将引起强烈和持久的免疫应答， 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.