Disease-related defects in dendritic cell processing of bacterial antigens

树突状细胞处理细菌抗原的疾病相关缺陷

• 批准号: 8190963
• 负责人: Michael S Marks
• 金额: $ 24万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8190963
• 关键词: Acids; Affect; Antigen Presentation; Antigen Presentation Pathway; Antigens; Bacteria; Bacterial Antigens; Bacterial Infections; Biogenesis; Bone Marrow; CD4 Positive T Lymphocytes; CD8B1 gene; Cell Culture Techniques; Cell physiology; Cells; Chronic Granulomatous Disease; Complex; Coxiella; Cross Presentation; Cytosol; Cytotoxic T-Lymphocytes; Data; Defect; Dendritic Cells; Disease; Early Endosome; Endocytosis; Environment; Event; Failure; Functional disorder; Generations; Genes; Genetic; Griscelli Syndrome; Hemorrhage; Hereditary Disease; Hermanski-Pudlak Syndrome; Hydrolase; Immune; Immune response; Immunocompromised Host; Immunologic Deficiency Syndromes; In Vitro; Infection; Integral Membrane Protein; Kinetics; Link; Listeria; Listeria monocytogenes; Lung; Lysosomes; Major Histocompatibility Complex; Mediating; Melanosomes; Membrane; Membrane Fusion; Modeling; Modification; Monomeric GTP-Binding Proteins; Mycobacterium tuberculosis; NADPH Oxidase; Natural Immunity; Neutropenia; Nitrogen; Oculocutaneous Albinism; Organelles; Organism; Oxygen; Particulate; Pathway interactions; Patients; Peptides; Phagocytes; Phagocytosis; Phagolysosome; Phagosomes; Process; Protein Subunits; Proteins; Protons; Puerto Rico; Reactive Oxygen Species; Recombinants; Relative (related person); Series; Signal Transduction; Sorting - Cell Movement; Symptoms; System; T-Lymphocyte; T-Lymphocyte Subsets; Testing; Tissues; Toll-like receptors; Wild Type Mouse; acquired immunity; adaptive immunity; antigen processing; base; cell type; immune function; in vivo; killings; macrophage; mouse model; neutrophil; novel; particle; pathogen; prevent; programs; protein complex; response; therapeutic target

DESCRIPTION (provided by applicant): Bacterial infections are largely cleared by phagocytosis within specialized phagocytic cell types. Engulfed bacteria are subjected to increasingly harsh conditions and eventually killed as the phagosome in which they are sequestered matures through an ordered series of membrane fusion and fission events, leading to acidification, consequent activation of hydrolases, and synthesis of reactive oxygen and nitrogen species. In conventional dendritic cells (DCs), antigens from phagocytosed bacteria - such as Listeria monocytogenes - are processed and presented by major histocompatibility complex (MHC) class I (MHC-I) and class II (MHC-II) molecules to activate naove pathogen-specific CD8+ and CD4+ T cells, respectively. These functions require modifications to the normal phagosome maturation program in which antigens are rapidly destroyed. As such, defects in DC phagosome maturation, arising either from bacterial evasion strategies or from host genetic deficiencies, can restrict the adaptive immune response by limiting antigen processing and presentation. Our preliminary results suggest that phagosome maturation and consequent MHC-II antigen presentation are altered in DCs from a mouse model of the genetic disease, Hermansky-Pudlak syndrome (HPS) type 2 (HPS2). HPS is a group of multi-system disorders characterized by oculocutaneous albinism, excessive bleeding, and other symptoms resulting form the failure to properly form tissue-specific intracellular compartments known collectively as lysosome-related organelles (LROs). HPS2 patients, who lack the endosomal protein sorting complex AP-3, additionally suffer from immunodeficiency and neutropenia. HPS7 and HPS8 patients lack a different complex, BLOC-1, that mediates different transport steps in other LRO- producing cell types; these patients are not immunodeficient. This suggests that AP-3 is specifically required for LRO function in immune cells. Notably, LROs in DCs have been implicated in several functions, including fusion with phagosomes to neutralize phagosomal pH and thereby promote antigen survival to allow for escape and presentation by MHC-I. Subsequent acidification is necessary to promote peptide generation for presentation by MHC II. Based on our preliminary data, we hypothesize that AP-3, but not BLOC-1, regulates phagosome maturation steps in DCs that are required for optimal presentation of phagocytosed bacterial antigens by MHC-II. We will test this hypothesis in the following Specific Aims: 1. To determine whether BLOC-1 or AP-3 are required for (a) optimal DC presentation of antigens following phagocytosis or other forms of endocytosis in vitro and (b) T cell immune responses upon challenge with a bacterial pathogen (L. monocytogenes) in vivo. 2. To test whether LRO biogenesis and/or phagosome maturation in bone marrow-derived DCs (BMDCs) is altered in HPS mouse models lacking BLOC-1 or AP-3. PUBLIC HEALTH RELEVANCE: Hermansky-Pudlak syndrome (HPS) is a group of genetic diseases that is unusually prevalent in Puerto Rico and in which patients suffer from a number of symptoms, including excessive bleeding, oculocutaneous albinism, and lung dysfunction. In one class of the disease (HPS type 2), patients also suffer from a mild immunodeficiency that has been linked to defects in one type of immune cell, the cytotoxic T lymphocyte. In this proposal, we will use a mouse model of HPS type 2 to test whether there are also defects in a different type of immune cell, the dendritic cell, and whether this malfunction is responsible for immunodeficiency against bacterial pathogens such as Listeria monocytogenes.

描述（由申请人提供）：细菌感染在很大程度上被专门的吞噬细胞类型中的吞噬作用清除。被吞噬的细菌受到越来越严峻的条件，并最终通过一系列有序的膜融合和裂变事件而被杀死，其中将其隔离成熟，从而导致酸化，导致水解酶的激活以及反应性氧和氮种的合成。在常规的树突状细胞（DC）中，来自吞噬细菌的抗原（例如单核细胞增生李斯特菌）由主要的组织相容性复合物（MHC）I类（MHC-I）和II类（MHC-II）（MHC-II）分子（MHC-I类）（MHC-I）分子进行处理和提出。这些功能需要修改正常的吞噬体成熟程序，其中抗原迅速破坏。因此，DC吞噬体成熟的缺陷，是由细菌逃避策略或宿主遗传缺陷引起的，可以通过限制抗原加工和表现来限制适应性免疫反应。我们的初步结果表明，吞噬体成熟和随之而来的MHC-II抗原表现在DC中从遗传疾病的小鼠模型Hermansky-Pudlak综合征（HPS）2型（HPS2）中改变了。 HPS是一组多系统疾病，其特征是具有眼皮白化病，过度出血和其他症状的特征，导致未能正确形成组织特异性的细胞内室，统称为溶酶体相关的细胞器（LROS）。缺乏内体蛋白分选复合物AP-3的HPS2患者还患有免疫缺陷和中性粒细胞减少症。 HPS7和HPS8患者缺乏不同的复合物BLOC-1，该复合物介导其他LRO生产细胞类型的不同传输步骤。这些患者不是免疫缺陷的。这表明AP-3是免疫细胞中LRO功能特别需要的。值得注意的是，DC中的LRO与多种功能有关，包括与吞噬体融合以中和吞噬体pH，从而促进抗原存活，以允许MHC-I逃脱和表现。随后的酸化对于促进MHC II呈现肽的产生是必要的。基于我们的初步数据，我们假设AP-3而不是BLOC-1调节DC中的吞噬体成熟步骤，这是MHC-II最佳表现出最佳吞噬细胞细菌抗原所必需的。我们将在以下特定目的中检验该假设：1。确定（a）（a）在吞噬作用或其他形式的内吞作用后，是否需要（a）抗原的最佳DC表现，并在体外的其他形式的内吞作用和（b）T细胞免疫反应在细菌病原体（L. l. l. nocytogenes）中挑战。 2。在缺乏BLOC-1或AP-3的HPS小鼠模型中，骨髓衍生的DC（BMDC）中的LRO生物发生和/或吞噬体成熟是否改变。 公共卫生相关性：Hermansky-Pudlak综合征（HPS）是一组遗传疾病，在波多黎各中异常普遍，患者患有多种症状，包括出血过多，眼胶质性白化病和肺部功能障碍。在该疾病的一类（HPS 2型）中，患者还患有轻度免疫缺陷，这与一种免疫细胞中的缺陷有关，细胞毒性T淋巴细胞。在此提案中，我们将使用HPS 2类型的小鼠模型来测试是否存在不同类型的免疫细胞，树突状细胞中的缺陷，以及该故障是否负责针对细菌病原体（如李斯特氏菌单核细胞增生）的免疫缺陷。