Role of the immunoglobulin DQ52 DH gene segment in fetal immunosuppression

免疫球蛋白 DQ52 DH 基因片段在胎儿免疫抑制中的作用

基本信息

批准号：
10451016
负责人：
Harry William Schroeder
金额：
$ 22.28万
依托单位：
UNIVERSITY OF ALABAMA AT BIRMINGHAM
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10451016
关键词：
Address Adult Affinity Age Amino Acid Sequence Amino Acids Antibodies Antibody Formation Antigens Autoantibodies Autoantigens Autoimmune Diseases Autoimmunity B-Cell Development B-Lymphocytes Birth CAR T cell therapy CRISPR/Cas technology Complementary RNA Complex Consensus Development Disease Elements Embryo Embryonic and Fetal Development Enterobacter cloacae Epitopes Equilibrium Exhibits Fetal Development Fetal Liver Flow Cytometry Generations Genes Genetic Recombination Glycine Goals Growth Growth and Development function Guide RNA Heavy-Chain Immunoglobulins Hen Egg Lysozyme Host resistance Human Immune Immune response Immune system Immunoglobulin Variable Region Immunoglobulins Immunosuppression Inbred BALB C Mice Infection Infectious Agent Knowledge Leucine Life Light Lymphoid Tissue Mature B-Lymphocyte Modeling Mus Neonatal Nucleotides Oocytes Organ Pathogenicity Pattern Peptide/MHC Complex Population Pregnancy Premature Infant Production Reading Frames Regulation Reporting Research Resistance to infection Rest Risk Role Site T-Cell Receptor T-Lymphocyte T-cell receptor repertoire Terminator Codon Testing Tissues Tyrosine V(D)J Recombination autoreactive B cell autoreactivity base cell type combinatorial complementarity-determining region 3 design embryo/fetus fetal immunoglobulin receptor in utero infection risk lymphoid organ mouse model neoantigens preference prenatal progenitor receptor function response secondary lymphoid organ sensor stem cells theories vaccination strategy virtual

项目摘要

Project Summary Our goal is to address the mechanisms that control the humoral immune response during embryonic and fetal development. During ontogeny, the B cells that are needed to populate the various lymphoid tissues and organs sequentially encounter an increasingly complex array of self-antigens as new cell types and non-lymphoid tissues and organs appear. There is a significant risk that embryonic B cells producing potentially pathogenic autoreactive immunoglobulins (Igs) could pass essential developmental checkpoints and thus survive to be activated after these `neo' antigens are ultimately expressed. Unsurprisingly, there is strong evidence that the humoral immune response is selectively suppressed in mammalian embryos and fetuses. Thus, although in theory Ig and T cell receptor (TCR) repertoires appear to be generated in a strictly stochastic fashion through random VDJ rearrangement and N addition; in practice both VDJ rearrangement and N addition are regulated in utero to restrict Ig and TCR diversity. There are 27 functional DH gene segments in humans and 13 in BALB/c mice. We previously showed that VDJ joins from both human and mouse embryonic B cell progenitors were enriched for use of the DQ52 gene segment (D7-27 in human and D4-01 in mouse). After birth, however, both species use DQ52 sparingly. Consequently, regulation of complementarity-determining region 3 of the Ig heavy (H) chain (CDR-H3), which contains the DQ52 gene segment, does not occur by chance and must be a major element of embryonic and early fetal repertoire control. Our prior research has shown that the sequence of the diversity (D) gene segment both delimits the range of CDR diversity and directs, or even dictates, patterns of epitope recognition and antibody production, thereby influencing host resistance to infection and autoimmune disease. DQ52 is the most highly conserved DH between human in mouse. Interestingly, DQ52 differs dramatically in amino acid content from the rest of the Ds, the most striking difference being the absence of tyrosine and enrichment for glycine. In this regard, DQ52 is more similar to TCR Dβ than the other Ig DH, making the in utero DQ52 CDR-H3 repertoire more like TCRβ CDR-B3 than adult Ig CDR-H3. TCRs function more like polyreactive sensors than monospecific effectors. Thus, using DQ52 in CDR-H3 could have the effect of reducing monospecificity and affinity for antigen, and reducing antibody production. These fundamental observations led us to our hypothesis that the role of Ig DQ52 during ontogeny is to promote the production of B cells while simultaneously serving as an immune suppressant DH. To test this hypothesis and to provide proof-of-concept, we propose to (a) use CRISPR/Cas9 technology to create a mouse whose DH locus contains only DQ52 (ΔD-DQ52), (b) test whether use of DQ52 facilitates B cell production, and (c) test whether use of DQ52 results in reduced antibody production. These studies will fill a major gap in our knowledge about the mechanisms that underlie immune suppression of the fetal humoral immune response, which is a major factor in the increased risk of infection in premature infants and in developing in utero vaccination strategies.

项目概要我们的目标是解决胚胎和胎儿时期控制体液免疫反应的机制在个体发育过程中，B 细胞需要填充各种淋巴组织和器官。依次遇到一系列日益复杂的自身抗原作为新的细胞类型和非淋巴细胞胚胎 B 细胞产生潜在致病性的风险很大。自身反应性免疫球蛋白（Igs）可以通过重要的发育检查点，从而存活下来不出所料，有强有力的证据表明这些“新”抗原最终表达后被激活。因此，尽管在哺乳动物胚胎和胎儿中，体液免疫反应被选择性抑制。理论上 Ig 和 T 细胞受体 (TCR) 库似乎是通过严格随机的方式生成的随机VDJ重排和N添加；实际上，VDJ重排和N添加都在子宫内限制 Ig 和 TCR 多样性。人类中有 27 个功能性 DH 基因片段，BALB/c 中有 13 个。我们之前表明，来自人类和小鼠胚胎 B 细胞祖细胞的 VDJ 连接是然而，在出生后，DQ52 基因片段（人类中的 D7-27 和小鼠中的 D4-01）的使用被富集。物种很少使用 DQ52，对 Ig 重链的互补性决定区 3 进行调节。 (H)链(CDR-H3)，含有DQ52基因片段，不是偶然出现的，一定是一个主要的我们之前的研究表明，胚胎和早期胎儿指令的序列控制。多样性 (D) 基因片段既界定了 CDR 多样性的范围，又指导甚至决定了 CDR 多样性的模式。表位识别和抗体产生，从而影响宿主对感染和自身免疫的抵抗力 DQ52 是人类与小鼠之间最高度保守的 DH。与其他 D 相比，氨基酸含量有显着差异，最显着的差异是缺乏酪氨酸和甘氨酸富集在这方面，DQ52 比其他 Ig DH 更类似于 TCR Dβ。与成人 Ig CDR-H3 相比，子宫内 DQ52 CDR-H3 的功能更像 TCRβ CDR-B3。多反应传感器比单特异性效应器因此，在 CDR-H3 中使用 DQ52 可能具有以下效果：降低对抗原的单特异性和亲和力，并减少抗体的产生。观察结果使我们得出这样的假设：Ig DQ52 在个体发育过程中的作用是促进生产 B 细胞同时充当免疫抑制剂 DH 来检验这一假设并进行验证。提供概念验证，我们建议 (a) 使用 CRISPR/Cas9 技术创建 DH 基因座的小鼠仅包含 DQ52 (ΔD-DQ52)，(b) 测试使用 DQ52 是否促进 B 细胞产生，以及 (c) 测试是否使用 DQ52 会导致抗体产生减少，这些研究将填补我们在这方面的知识空白。胎儿体液免疫反应的免疫抑制机制，这是一个主要的早产儿感染风险增加和制定子宫内疫苗接种策略的因素。