The human innate B cell niche and role in efferocytosis

人类先天 B 细胞生态位及其在胞吞作用中的作用

• 批准号: 8875362
• 负责人: Emmanuel Zorn
• 金额: $ 24万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-02-01 至 2016-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8875362
• 关键词: Address; Anti-Inflammatory Agents; Anti-inflammatory; Antibodies; Antigens; Apoptotic; Atherosclerosis; Autoimmune Diseases; B-Lymphocyte Subsets; B-Lymphocytes; Binding; Blood; Blood specimen; Brain Death; Carbohydrates; Cell Fraction; Cell surface; Cells; Characteristics; Collaborations; Collection; Complement; Consensus; Deposition; Development; Disease; Drug or chemical Tissue Distribution; Fingerprint; Flow Cytometry; Frequencies; Greater sac of peritoneum; Health; Human; Human body; IgG1; Immune response; Immunoglobulin A; Immunoglobulin Class Switching; Immunoglobulin G; Immunoglobulin M; Immunoglobulin Somatic Hypermutation; Immunoglobulin Switch Recombination; Immunoglobulins; In Situ; In Vitro; Infectious Agent; Inflammation; Inflammatory; Kidney Transplantation; Knowledge; Letters; Maps; Mediating; Memory; Memory B-Lymphocyte; Mus; Mutate; Natural Immunity; New York; Opsonin; Organ Donor; Outcome; Pathology; Pattern; Phagocytes; Phagocytosis; Phenotype; Physiological; Play; Population; Production; Property; Reaction; Regulation; Resolution; Retrospective Studies; Role; Sampling; Serum; Site; Solid; Somatic Mutation; Source; Specimen; Tissues; Transplant Recipients; Work; base; cytokine; deep sequencing; human tissue; in vivo; innate immune function; kidney allograft; peripheral blood; public health relevance; research study; response

DESCRIPTION (provided by applicant): B-1 cells are a distinct B cell subset in mice characterized by expression of CD19highCD43+IgMhighIgDlowCD5+/-, and by secretion of polyreactive IgM natural antibodies (NAb). Under steady state conditions, IgM NAb play a critical homeostatic function by enhancing efferocytosis and suppressing inflammation in response to apoptotic cells. Due to this innate immune function, these cells are also referred to as "innate" B cells. In contrast, there is still little consensus on how to define innate B cells i humans. In preliminary experiments, we generated human innate B cell clones secreting polyreactive NAb that react to apoptotic cells from human blood samples. Remarkably, we found that a fraction of these cells were memory B cells, which had undergone somatic hypermutation in vivo. Because their frequency in peripheral blood was relatively low (~1/20-100,000), we hypothesized that innate B cells reside primarily in tissue and do not often recirculate. Our proposed studies will make use of a collection of human tissue specimens collected from brain dead solid organ donors to investigate the distribution of innate B cells in the human body. We will also phenotype these cells in their anatomical niches. Our experiments will particularly examine the clonal composition of innate B cells through a deep sequencing based analysis of their IgH repertoire. Functionally, innate B cells participate in efferocytosis through the production of IgM Nab. We propose that upon activation, these cells undergo class-switch recombination resulting in the secretion of IgG and IgA Nab. Our studies will address compare the modulatory effect of different classes of Nabs on efferocytosis. Experiments will be carried out in 2 specific aims: Aim-1. To characterize human innate B cells and map their anatomical niches. Innate B cell clones reactive to apoptotic cells will be generated in vitro from a variety of human tissue specimens collected from brain dead solid organ donors. Their Ig heavy chain (IgH) rearranged CDR3 sequences will then be identified and used to assess their frequency in the various tissues using a deep sequencing strategy. The IgH sequences will also indicate whether these clones have accumulated different somatic mutations at different sites and have undergone class switch recombination (CSR) in situ. Lastly, we use flow cytometry to profile innate B cell surface markers in various tissues and blood. Aim-2. To determine the function of NAb produced by innate B cells in efferocytosis. We will first determine the classes and subclasses of Nabs produced by innate B cell clones derived from the various tissue specimens. In relation to their capacity to bind apoptotic cells, we will then examine the capacity of the different types classes (IgM, IgG and IgA) and subclasses (IgG1-4) of Nabs to 1) activate complement leading to the deposition complement opsonins on target apoptotic cells, 2) enhance or block efferocytosis by most common phagocytes and 3) trigger different cytokine secretion pattern by scavenger cells upon phagocytosis.

描述（由申请人提供）：B-1细胞是小鼠中的一个独特的B细胞子群，其特征是CD19HighCD43+Igmhighiggdlowcd5 +/-，并且通过分泌多反应IgM天然抗体（NAB）。在稳态条件下，IgM NAB通过增强吞噬作用和抑制凋亡细胞的炎症来起到关键的稳态功能。由于这种先天的免疫功能，这些细胞也称为“先天” B细胞。相比之下，如何定义我人类的先天B细胞几乎没有共识。在初步实验中，我们产生了人类先天B细胞克隆，分泌多反应性NAB，对人类血液样本的凋亡细胞反应。值得注意的是，我们发现这些细胞的一部分是记忆B细胞，在体内经历了体细胞超数。由于它们在外周血中的频率相对较低（〜1/20-100,000），因此我们假设先天B细胞主要存在于组织中，并且经常不再循环。我们提出的研究将利用从脑死亡的固体器官供体中收集的人类组织标本的集合来研究人体先天B细胞的分布。我们还将在它们的解剖壁ches中表型。我们的实验将通过基于深度测序的IGH曲目分析来特别检查先天B细胞的克隆组成。从功能上讲，先天B细胞通过生产IgM NAB参与胚细胞增多症。我们提出激活后，这些细胞会经历类别切换重组，导致IgG和IgA NAB分泌。我们的研究将解决不同类别NABS对胚细胞增多症的调节作用。实验将以2个特定目的进行：AIM-1。表征人类先天B细胞并绘制其解剖壁ni。先天B细胞克隆对凋亡细胞的反应性将在体外产生 从脑死亡的固体器官供体收集的各种人体组织标本。然后，将确定其Ig重链（IGH）重排的CDR3序列，并使用深层测序策略来评估其在各种组织中的频率。 IGH序列还将指示这些克隆是否在不同位点积累了不同的体细胞突变，并在原位进行了类开关重组（CSR）。最后，我们使用流式细胞术来介绍各种组织和血液中的先天B细胞表面标记。 AIM-2。确定先天B细胞在胚细胞增多症中产生的NAB的功能。我们将首先确定由源自各种组织标本的先天B细胞克隆产生的NAB的类和子类。关于它们结合凋亡细胞的能力，我们将检查能力 在不同类型的类别（IgM，IgG和IgA）和Nabs的子类（IgG1-4）中，1）激活补体，导致对靶凋亡细胞上的沉积补体，2）增强或阻断大多数常见的吞噬细胞和3）触发不同细胞的吞噬细胞的phagerion phagecocy phagerts phagerion phagertion phagocyte phagocytes and phagocytes和3）触发了phagerion phagertion。