Revealing the Biophysics of the Germinal Center Microenvironment

揭示生发中心微环境的生物物理学

• 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
• 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

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 HIV疫苗是否可能？疫苗是过去最成功的公共卫生干预措施之一 世纪。几乎所有疫苗都通过诱导保护性抗体起作用。但是，我们对细胞的理解 免疫反应的动力学对疫苗，特别是围绕B细胞竞争的生物学的动力学 对复杂疫苗抗原的生发中心（GC）受到限制。缺乏对基本B细胞的了解 生物学导致无法开发有效的HIV疫苗。有希望的是，少数人口 艾滋病毒+个体已经开发出广泛中和抗体（BNABS），使人们对艾滋病毒的希望有了新的希望 疫苗是可能的。最近的工作发现，许多HIV负面健康的人类捐助者都有VRC01级 BNAB前体B细胞。但是，这些研究的工作表明这些潜在的BNAB前体B细胞 在异常罕见的频率上发现。这表明后，这些B细胞可能是 被更常见的非中和B细胞胜过。回答围绕此的免疫学问题 问题，我使用含有人类基因的小鼠进行种系的VRC01开发了一个模型系统 BNAB（VRC01GHL）。通过此B细胞转移模型，我们发现抗原亲和力，亲和力和前体 频率均在GC中稀有VRC01GHL B细胞的竞争成功中起着相互依存的作用。批判性，我们 发现具有物理亲和力的稀有VRC01GHL B细胞可以在 GCS。但是，这些反应仅限于特定的“ GC”岛，表明B细胞竞争与种子 除了GC内部的竞争外，单个GC也至关重要。综上所述，这些观察表明 GC微环境（GCME）中的B细胞免疫率是克服的主要障碍 开发成功的HIV疫苗。但是，与 B细胞竞争进入GC并在GCME中竞争的生理条件。开始，什么 我们知道GCME的生物物理和代谢特征吗？我们假设并发现 GC形成低氧微环境。我假设其他生物物理限制可能正在行动 GC选择事件由于许多途径已被证明在低氧肿瘤微环境中都活跃 （TME）和低氧GCME。我假设在与TME的进一步相关时，GCME可能包含 较高的刀酸水平，诱导多种代谢GPCR，pH值降低，温度升高和细胞压力。 我指出，GC的这些生物物理参数可以并且确实会影响B细胞选择事件到复杂 抗原。在此DP2提案中，我将通过多种 Phototon针对直接测量并定义了限制VRC01-成功的生物物理约束 B类细胞反应。然后，我们将应用我们从研究GCME中学到的知识来操纵B单元 GCME中的免疫主持，有利于选择VRC01级B细胞的竞争选择。