Identifying the properties of LLO required for MHC class I presentation

确定 MHC I 类呈现所需的 LLO 的特性

• 批准号: 7426430
• 负责人: JODY A. MELTON-WITT
• 金额: $ 5.29万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-06-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7426430
• 关键词: Affect; Animal Cancer Model; Animals; Antigen Presentation Pathway; Biochemical; Biological; Biological Assay; CD4 Positive T Lymphocytes; CD8B1 gene; Cancer Vaccines; Cell surface; Cells; Cytosol; Defect; Depth; Disease regression; Engineering; Epitopes; Generations; Goals; Heterophile Antigens; Histocompatibility Antigens Class I; Immune; Immune response; Immune system; Immunity; Immunodominant Epitopes; In Vitro; Lead; Length; Listeria monocytogenes; Listeria monocytogenes hlyA protein; Location; MHC Class I Genes; Mediating; Metabolic; Modeling; Monitor; Mus; Mutagenesis; Mutation; Organism; Pathogenesis; Pathway interactions; Peptides; Phagosomes; Phosphorylation; Play; Process; Production; Property; Proteins; Regulation; Role; Series; T-Lymphocyte; Testing; Toxin; Tumor Antigens; Ubiquitination; Vaccines; antigen processing; base; cell mediated immune response; design; in vivo; multicatalytic endopeptidase complex; mutant; novel; pathogen; response; tumor; vector vaccine

DESCRIPTION (provided by applicant): Project Summary: Listeria monocytogenes (Lm) is a model intracellular pathogen that has been studied intensively to understand various aspects of the host's innate and cell-mediated immune responses. The induction of and acquired CD4 T cell response is crucial for protective immunity against this pathogen. A prerequisite for the induction of this protective immune response is escape from the primary phagosome into the cytosol where various components can be processed and presented in MHC class I molecules on the cell surface. Listeriolysin O (LLO) is a pore-forming toxin secreted by Lm and is required for escape from the phagosome. LLO also happens to be the protein from which the immunodominant epitope presented on MHC class I molecules is generated. Due to its intracellular location, the use of Lm as a vaccine vector for the delivery of tumor antigens to the cytosol where they can be processed and presented via MHC class I molecules is being heavily studied. Some of these studies have shown that fusion of LLO to the heterologous antigen will lead to the induction of a robust immune response that is otherwise not produced. It is the goal of this proposal to ascertain the properties of LLO that lead it through the MHC class I processing pathway and centers on the hypothesis that the natural properties of LLO that make it metabolically unstable and are essential for pathogenesis lead to its entry into the MHC class I processing pathway. To this end we will carry out the following two aims: 1) In vivo identification of residues that are essential for an immune response to LLO, and 2) In vitro characterization of the properties of LLO necessary for the generation of immunodominant epitopes. Relevance: Using Lm to deliver tumor antigens to the cytosol of host cells, it has been shown that the best immune response to established tumors is obtained when the tumor antigens are fused directly to LLO. Defining the properties of LLO that lead to such a strong immune response is the goal of this proposal with the hopes of using the information obtained in the design of more effective vaccines.

项目概述：单核增生李斯特菌（Listeria monocytogenes, Lm）是一种细胞内病原体模型，人们对其进行了深入研究，以了解宿主先天和细胞介导的免疫反应的各个方面。CD4 T细胞反应的诱导和获得性对于抵抗这种病原体的保护性免疫至关重要。诱导这种保护性免疫反应的先决条件是从初级吞噬体逃逸到细胞质中，在那里各种成分可以被加工并以细胞表面的MHC I类分子呈现。李斯特菌溶素O （LLO）是由Lm分泌的一种成孔毒素，是脱离吞噬体所必需的。LLO也恰好是MHC I类分子上呈现的免疫显性表位产生的蛋白质。由于其位于细胞内，使用Lm作为疫苗载体将肿瘤抗原递送到细胞质中，在细胞质中它们可以通过MHC I类分子进行加工和呈递，目前正在进行大量研究。其中一些研究表明，LLO与异源抗原的融合将导致诱导强大的免疫反应，否则不会产生。本提案的目标是确定LLO通过MHC I类加工途径的特性，并以LLO使其代谢不稳定且对发病至关重要的天然特性导致其进入MHC I类加工途径的假设为中心。为此，我们将开展以下两个目标：1)体内鉴定对LLO免疫应答至关重要的残基；2)体外鉴定产生免疫优势表位所需的LLO特性。相关性：利用Lm将肿瘤抗原传递到宿主细胞的细胞质中，研究表明，当肿瘤抗原直接与LLO融合时，对已建立的肿瘤获得最佳的免疫应答。确定导致如此强烈免疫反应的LLO的特性是本提案的目标，希望利用所获得的信息设计更有效的疫苗。