Molecular Regulation of Germinal Center B Lymphocytes

生发中心 B 淋巴细胞的分子调控

• 批准号: 8649227
• 负责人: Alexander Gitlin
• 金额: $ 4.77万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8649227
• 关键词: Address; Adoptive Transfer; Affinity; Amino Acids; Animals; Antibodies; Antibody Affinity; Antigen-Antibody Complex; Antigens; Area; B-Lymphocytes; Binding; Biology; CD4 Positive T Lymphocytes; Cell Count; Cells; Complex; Cytoplasmic Tail; Endocytosis; Event; Flow Cytometry; Follicular Dendritic Cells; Germinal Center B-Lymphocyte; Goals; Humoral Immunities; IgG1; Immune response; Immunization; Immunoglobulin Class Switching; Immunoglobulin G; Immunoglobulin M; Immunoglobulin Somatic Hypermutation; Immunoglobulin Switch Recombination; Immunoglobulin Variable Region; Immunoglobulins; Immunology; Infection; Institutes; Knock-in Mouse; Life; Light; Lymphoid; Major Histocompatibility Complex; Measures; Memory; Molecular; Molecular Genetics; Mus; Mutate; Organ; Peptides; Plasma Cells; Play; Process; Proliferating; Property; Protocols documentation; Public Health; Reaction; Receptor Signaling; Receptors, Antigen, B-Cell; Regulation; Research; Role; Signal Transduction; Structure of germinal center of lymph node; System; T-Lymphocyte; Techniques; Time; Transgenic Mice; Vaccine Design; Vaccines; activation-induced cytidine deaminase; antigen binding; base; chimeric antibody; insight; intravital imaging; migration; mouse model; mutant; novel; novel vaccines; pathogen; public health relevance; recombinase; response; vaccine development

DESCRIPTION (provided by applicant): Germinal centers (GCs) form transiently in secondary lymphoid organs following immunization or infection and are central in providing humoral immunity. Within the GC, antigen-specific B lymphocytes express activation-induced cytidine deaminase (AID), inducing somatic hypermutation (SMH) and class switch recombination (CSR). These processes randomly mutate the immunoglobulin locus and switch antibody isotype, respectively. Competitive selection ensues among mutant GC B cells, with high affinity B cells undergoing selective expansion and differentiating into memory or plasma cells. Although the GC has long been studied, the events controlling selection of high affinity B cells remain obscure. The GC is subdivided into two anatomically and functionally distinct regions, the light (LZ) and dark zones (DZ). In the LZ, B cells bind antigen, retained as immune complexes on follicular dendritic cells (FDCs), in proportion to their affinity and process it for presentation to CD4+ T cells as peptide bound to major histocompatibility complex II (pMHCII). In this manner, high affinity GC B cells are selected based on pMHCII and T cell help, but the mechanisms by which this occurs are not known. Furthermore, a direct role for the B cell receptor (BCR) in GC selection, in addition to endocytosing antigen, has been suggested but never elucidated. This issue is further complicated by ongoing isotype switching in the GC, which changes the BCR signaling capacity. This proposal seeks to analyze how pMHCII levels and isotype-specific BCR signal transduction regulate GC B cell selection mechanisms. Toward the first goal, an antigen delivery system will be used that can modulate pMHCII levels on a subset of GC B cells in a temporally controlled manner. Toward the second goal, novel mice will be generated in which the isotype of the BCR can be switched through cre recombinase, independently of antibody affinity and somatic hypermutation. These problems, central to GC biology and the humoral immune response, will be addressed through a combination of mouse molecular genetics, traditional immunology techniques, flow cytometry, and multiphoton intravital imaging of live animals undergoing GC responses.

描述（由申请人提供）：生发中心（GC）在免疫或感染后在次级淋巴器官中短暂形成，并且是提供体液免疫的核心。在 GC 内，抗原特异性 B 淋巴细胞表达激活诱导的胞苷脱氨酶 (AID)，诱导体细胞超突变 (SMH) 和类别转换重组 (CSR)。这些过程分别随机突变免疫球蛋白基因座并转换抗体同种型。突变型 GC B 细胞之间会发生竞争性选择，高亲和力 B 细胞会选择性扩增并分化为记忆细胞或浆细胞。尽管 GC 长期以来一直被研究，但控制高亲和力 B 细胞选择的事件仍然不清楚。 GC 被细分为两个解剖学和功能上不同的区域：亮区 (LZ) 和暗区 (DZ)。在 LZ 中，B 细胞与抗原结合，作为免疫复合物保留在滤泡树突状细胞 (FDC) 上，与其亲和力成比例，并将其加工成与主要组织相容性复合物 II (pMHCII) 结合的肽呈递给 CD4+ T 细胞。以这种方式，基于 pMHCII 和 T 细胞的帮助选择高亲和力 GC B 细胞，但发生这种情况的机制尚不清楚。此外，除了内吞抗原之外，B 细胞受体 (BCR) 在 GC 选择中的直接作用已被提出，但从未得到阐明。 GC 中正在进行的同型转换会改变 BCR 信号传输能力，从而使这个问题变得更加复杂。该提案旨在分析 pMHCII 水平和同种型特异性 BCR 信号转导如何调节 GC B 细胞选择机制。为了实现第一个目标，将使用一种抗原递送系统，该系统可以以时间受控的方式调节 GC B 细胞子集上的 pMHCII 水平。为了实现第二个目标，将产生新型小鼠，其中 BCR 的同种型可以通过 cre 重组酶进行转换，而与抗体亲和力和体细胞超突变无关。这些对于GC生物学和体液免疫反应至关重要的问题将通过结合小鼠分子遗传学、传统免疫学技术、流式细胞术和经历GC反应的活体动物的多光子活体成像来解决。