Revealing the Biophysics of the Germinal Center Microenvironment

揭示生发中心微环境的生物物理学

基本信息

批准号：
10543399
负责人：
Robert Koehler Abbott
金额：
$ 48万
依托单位：
UNIVERSITY OF TEXAS MED BR GALVESTON
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-12-22 至 2026-11-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10543399
关键词：
ADORA2A gene Achievement Address Adenosine Affect Affinity Animal Model Antibodies Antibody Response Antigens Autoimmunity Avidity B-Cell Activation B-Cell Antigen Receptor B-Lymphocytes Biological Models Biology Biophysics Cell Culture Techniques Cell model Cellular biology Characteristics Clone Cells Coin Complex Cues Engineering Epitopes Event Extracellular Space Frequencies Future G-Protein-Coupled Receptors Generations Genes Goals HIV HIV Seronegativity HIV envelope protein HIV vaccine Helper-Inducer T-Lymphocyte Human Hypoxia Immune response Immunization Immunoglobulin Somatic Hypermutation Immunologics In Vitro Individual Influenza Hemagglutinin Intervention Island Knowledge Learning Licensing Measurement Measures Metabolic Metabolic Pathway Microdialysis Microscopic Modeling Mus Mutate Nature Outcome Pathway interactions Phase Phylogenetic Analysis Physiological Play Population Purinergic P1 Receptors Reaction Role Series Signal Transduction Specialized Center Structure Structure of germinal center of lymph node System Temperature Vaccination Vaccine Antigen Vaccine Design Vaccines Vascular Endothelial Growth Factors Virus Work biophysical properties design extracellular fitness immunoregulation improved insight interest multi-photon neutralizing antibody novel pharmacologic pressure public health intervention recruit response small molecule success tumor hypoxia tumor microenvironment

项目摘要

Abstract Is an HIV vaccine possible? Vaccines are one of the most successful public health interventions over the past century. Nearly all vaccines work by induction of protective antibodies. However, our understanding of the cellular dynamics of immune responses to vaccines, particularly the biology surrounding B cell competition within germinal centers (GC) to complex vaccine antigens is limited. This lack of understanding of fundamental B cell biology has contributed to the inability to develop an effective HIV vaccine. Promisingly, a small population of HIV+ individuals have developed broadly neutralizing antibodies (bnAbs), giving renewed hope that an HIV vaccine is possible. Recent work has found that many HIV negative healthy human donors have VRC01-class bnAb precursor B cells. However, work from these studies revealed that these potential bnAb precursor B cells are found at an unusually rare frequency. This suggested that following immunization these B cells may be outcompeted by more frequent non-neutralizing B cells. To answer immunological questions surrounding this problem, I developed a model system utilizing mice containing human genes for the germline-reverted VRC01 bnAb (VRC01gHL). Through this B cell transfer model, we found that antigen affinity, avidity, and precursor frequency all played interdependent roles in competitive success of rare VRC01gHL B cells in GCs. Critically, we found that rare VRC01gHL B cells with physiological affinities could be primed to successfully compete within GCs. However, these responses were limited to specific “GC” islands suggesting B cell competition to seed individual GCs is critical in addition to competition within the GC. Taken together, these observations suggest that B cell immunodominance in the GC microenvironment (GCME) is a major obstacle to overcome in developing a successful HIV vaccine. However, there are significant knowledge gaps pertaining to the physiological conditions in which B cells compete to enter GCs, and compete within the GCME. To start, what do we know about the biophysical and metabolic characteristics of the GCME? We hypothesized and found that GCs form a hypoxic microenvironment. I hypothesize that other biophysical constraints may be acting to control GC selection events as many pathways have been shown to be both active in hypoxic tumor microenvironments (TMEs) and in the hypoxic GCME. I hypothesize that in further correlation with TMEs, the GCME may contain high lactate levels, induce multiple metabolic GPCRs, reduced pH, increased temperature, and cellular pressure. I posit that these biophysical parameters of the GC can and do influence B cell selection events to complex antigens. In this DP2 proposal I will investigate the nature of the extracellular milieu of the GCME through multi- photon targeted direct measurements and define the biophysical constraints that limit the success of VRC01- class B cell responses. We will then apply what we learn from studying the GCME to manipulate B cell immunodominance in the GCME to favor competitive selection of VRC01-class B cells.

抽象的艾滋病疫苗可能是过去最成功的公共卫生干预措施之一吗？几乎所有疫苗都是通过诱导保护性抗体起作用的。然而，我们对细胞的理解还不够。对疫苗的免疫反应的动态，特别是围绕 B 细胞竞争的生物学生发中心 (GC) 对复杂疫苗抗原的了解是有限的。生物学因素导致无法开发出有效的艾滋病毒疫苗，但有希望的是，少数人群。 HIV+ 个体已经产生了广泛的中和抗体 (bnAb)，这给 HIV 感染者带来了新的希望最近的工作发现，许多 HIV 阴性的健康人类捐赠者具有 VRC01 级。 bnAb 前体 B 细胞然而，这些研究表明这些潜在的 bnAb 前体 B 细胞。的发现频率异常罕见，这表明免疫后这些 B 细胞可能会被破坏。被更频繁的非中和 B 细胞击败回答围绕这一点的免疫学问题。为了解决这个问题，我开发了一个模型系统，利用含有人类生殖系恢复 VRC01 基因的小鼠通过这个 B 细胞转移模型，我们发现了 bnAb (VRC01gHL) 的抗原亲和力、亲合力和前体。频率都在 GC 中罕见 VRC01gHL B 细胞的竞争成功中发挥着相互依赖的作用。发现具有生理亲和力的罕见 VRC01gHL B 细胞可以准备好在体内成功竞争然而，这些反应仅限于特定的“GC”岛，表明 B 细胞竞争种子。综合来看，这些观察结果表明，除了 GC 内部的竞争之外，单个 GC 也至关重要。 GC 微环境 (GCME) 中的 B 细胞免疫优势是需要克服的主要障碍然而，在开发成功的艾滋病毒疫苗方面存在重大知识差距。 B 细胞竞争进入 GC 并在 GCME 内竞争的生理条件首先，什么是？我们了解 GCME 的生物物理和代谢特征吗？我认为其他生物物理约束可能会起到控制作用。 GC 选择事件，因为许多途径已被证明在缺氧肿瘤微环境中都很活跃（TME）并且在缺氧 GCME 中，我勇敢地说，与 TME 进一步相关，GCME 可能包含。高乳酸水平会诱导多种代谢性 GPCR、pH 值降低、温度升高和细胞压力升高。我认为 GC 的这些生物物理参数可以并且确实影响 B 细胞选择事件以复杂化在这个 DP2 提案中，我将通过多种方式研究 GCME 细胞外环境的性质。光子定向直接测量并定义限制 VRC01-成功的生物物理约束然后，我们将应用从 GCME 研究中学到的知识来操纵 B 细胞。 GCME 中的免疫优势有利于 VRC01 类 B 细胞的竞争选择。