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）：细菌感染很大程度上通过专门的吞噬细胞类型内的吞噬作用被清除。被吞噬的细菌受到越来越恶劣的条件的影响，并最终被杀死，因为它们被隔离的吞噬体通过一系列有序的膜融合和裂变事件成熟，导致酸化，随后激活水解酶，并合成活性氧和氮物种。在传统的树突细胞 (DC) 中，来自吞噬细菌（例如单核细胞增生李斯特氏菌）的抗原由主要组织相容性复合体 (MHC) I 类 (MHC-I) 和 II 类 (MHC-II) 分子加工和呈递，分别激活幼稚病原体特异性 CD8+ 和 CD4+ T 细胞。这些功能需要对正常的吞噬体成熟程序进行修改，在该程序中抗原被迅速破坏。因此，由细菌逃避策略或宿主遗传缺陷引起的 DC 吞噬体成熟缺陷可以通过限制抗原加工和呈递来限制适应性免疫反应。我们的初步结果表明，来自遗传性疾病赫曼斯基-普德拉克综合征 (HPS) 2 型 (HPS2) 小鼠模型的 DC 中，吞噬体成熟和随后的 MHC-II 抗原呈递发生了改变。 HPS 是一组多系统疾病，其特征是眼皮肤白化病、过度出血以及因未能正确形成组织特异性细胞内区室（统称为溶酶体相关细胞器 (LRO)）而导致的其他症状。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，该复合物在其他产生LRO的细胞类型中介导不同的转运步骤；这些患者并不存在免疫缺陷。这表明 AP-3 是免疫细胞中 LRO 功能所特别需要的。值得注意的是，DC 中的 LRO 涉及多种功能，包括与吞噬体融合以中和吞噬体 pH 值，从而促进抗原存活，从而允许 MHC-I 逃逸和呈递。随后的酸化对于促进 MHC II 呈递的肽生成是必要的。根据我们的初步数据，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 吞噬细菌抗原最佳呈递所必需的。我们将在以下具体目标中检验这一假设： 1. 确定 BLOC-1 或 AP-3 是否需要 (a) 体外吞噬作用或其他形式的内吞作用后 DC 最佳呈递抗原，以及 (b) 体内细菌病原体（单核细胞增生利斯特氏菌）攻击后 T 细胞免疫反应。 2. 测试缺乏 BLOC-1 或 AP-3 的 HPS 小鼠模型中骨髓源性 DC (BMDC) 中的 LRO 生物发生和/或吞噬体成熟是否发生改变。 公共卫生相关性：赫曼斯基-普德拉克综合征 (HPS) 是一组遗传性疾病，在波多黎各异常流行，患者会出现多种症状，包括出血过多、眼皮肤白化病和肺功能障碍。在一类疾病（HPS 2 型）中，患者还患有轻度免疫缺陷，这种缺陷与一种免疫细胞（细胞毒性 T 淋巴细胞）的缺陷有关。在本提案中，我们将使用 HPS 2 型小鼠模型来测试另一种类型的免疫细胞（树突状细胞）是否也存在缺陷，以及这种功能障碍是否导致针对单核细胞增生李斯特菌等细菌病原体的免疫缺陷。