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，具有明显的 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。以诱导CPS- 特异性获得性免疫反应(即T细胞介导的B细胞反应)、CPSS与载体偶联 蛋白质，结合产物称为糖结合疫苗。由于对……认识不足 它们的免疫激活机制，目前的糖结合疫苗策略已经达到饱和和 在很大程度上是对过去经验共轭方法的修改。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亟需新的视角。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 CD4+T细胞谱系包含一组识别糖结合物的碳水化合物表位的T细胞 疫苗，被称为TCars。在我们以前机械化工作的基础上，我们建议建立一个平台来 设计和开发结构明确的糖结合疫苗，优化其免疫原性和 抗原性成分，以持续有效地诱导保护性免疫。这项提案还涉及 控制结合疫苗免疫原性的另一个关键参数是识别免疫 糖结合疫苗免疫保护作用的相关因素。在临床实践中，改进 检测CPS特异性抗体效价和体外吞噬细胞活性作为免疫相关性研究 预防是实现临床疗效可靠预测的一个重要里程碑。我们建议 识别对疫苗效力至关重要的关键辅助性T细胞群作为新的免疫相关性 保护。从两种高致病性肺炎链球菌(Spn)血清型Spn3中提取CPSS 和Spn14-在我们已发表和未发表的初步研究的基础上，我们将建立一个新的和 广泛适用结合疫苗平台以及由这些平台产生的免疫反应的特征 通过两个具体目标接种疫苗。目标1：建立基于知识的结合疫苗平台 由内酶体可裂解的多肽链与CPSS化学酶结合而成。目标2： 人Tcarb克隆的分离及其诱导保护性体液免疫能力的功能鉴定

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 have distinct structures. These two features make them easily accessible and distinctly recognizable by immune surveillance, therefore resulting in the 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 on 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 T cells that recognize carbohydrate epitopes of glycoconjugate vaccines, called Tcarbs. Building on our previous mechanistic work, we propose establishing a platform to design and develop structurally defined glycoconjugate vaccines optimized for their immunogenic and antigenic components to elicit protective immunity consistently and effectively. This proposal also addresses another key parameter controlling the immunogenicity of conjugate vaccines, which is to identify the immune correlates of protection induced by glycoconjugate vaccine immunization. In clinical practice, improving on measuring CPS-specific antibody titers and the in vitro opsonophagocytic activity as immune correlates of protection is an essential milestone to achieve for the reliable prediction of clinical efficacy. We propose to identify key helper T cell populations that are essential for vaccine efficacy as a new immune correlate of protection. Exploiting CPSs from two highly pathogenic Streptococcus pneumoniae (Spn) serotypes—Spn3 and Spn14—and building on our published and unpublished preliminary studies, we will establish a new and broadly applicable conjugate vaccine platform and characterize immune responses that result from these vaccines through two specific aims. Aim 1: Establish a knowledge-based conjugate vaccine platform composed of endolysosome-cleavable polypeptide chains chemoenzymatically conjugated with CPSs. Aim 2: Isolate and functionally characterize human Tcarb clones for their ability to induce protective humoral immunity