Pathogenic Autoantibodies with Specificity for Aberrant Glycoproteins: Assessment of a Therapeutic Target in an Autoimmune Disease

具有异常糖蛋白特异性的致病性自身抗体：自身免疫性疾病治疗靶点的评估

• 批准号: 10359090
• 负责人: Todd Jason Green
• 金额: $ 51.58万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-03-01 至 2025-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10359090
• 关键词: Address; Affinity; Age; Amino Acid Sequence; Amino Acids; Antibody-Producing Cells; Antigen-Antibody Complex; Antigens; Autoantibodies; Autoantigens; Autoimmune Diseases; Automobile Driving; Binding; Binding Sites; Biochemical; Clinical; Clinical Research; Cloning; Complement; Complex; Coupled; Cryoelectron Microscopy; DNA Sequence Alteration; Data; Defect; Deposition; Development; Diagnosis; Disease; Disease Progression; Docking; Drug Design; Elements; End stage renal failure; Epitopes; Ethnic Origin; Galactose; Generations; Genes; Glomerulonephritis; Glycopeptides; Glycoproteins; Goals; IGA Glomerulonephritis; IgA1; IgG autoantibodies; Immunoglobulin G; Immunoglobulin Somatic Hypermutation; Immunoglobulins; Immunologics; Individual; Injury to Kidney; Kidney; Kidney Failure; Laboratories; Lead; Libraries; Life Expectancy; Methods; Minor; Modeling; Molecular; Pathogenesis; Pathogenicity; Patient-Focused Outcomes; Patients; Phenotype; Polysaccharides; Population; Process; Production; Reagent; Recombinants; Research Personnel; Resolution; Sampling; Serine; Serum; Severity of illness; Site; Site-Directed Mutagenesis; Specificity; Structure; Surface; Surface Plasmon Resonance; Techniques; Testing; United States; X-Ray Crystallography; base; biobank; chronic autoimmune disease; design; drug development; high throughput screening; improved outcome; in silico; inhibitor; multidisciplinary; pathogenic autoantibodies; prevent; screening; small molecule; therapeutic target; tool

IgA nephropathy (IgAN), the most common glomerulonephritis worldwide, leads to end-stage renal disease in 20-40% of patients and can reduce life expectancy by up to 10 years, as there is no known cure or disease- specific treatment. Most IgAN patients, regardless of age and ethnicity, have immunologic defects resulting in generation of pathogenic IgA1-containing immune complexes, which ultimately deposit in the kidneys to induce renal injury. These renal immunodeposits likely originate from circulating immune complexes consisting of IgA1 with hinge-region galactose-deficient O-glycans (Gd-IgA1) bound by Gd-IgA1-specific IgG autoantibodies. The long-term goal of this project is to define the underlying mechanisms that lead to the formation of pathogenic immune complexes, so that IgAN-specific treatments can be developed. Our hypothesis is that a molecular- level characterization of Gd-IgA1-specific IgG autoantibodies from IgAN patients coupled with an atomic-level characterization of autoantibodies in immune complexes will significantly advance our understanding of immune-complex formation in IgAN. This information will in-turn provide a basis for development of new disease-specific treatments. Over the past three years, the laboratories of the investigators have utilized biochemical, molecular, structural, and clinical studies to begin characterization of IgAN-specific autoantibodies. We have shown that IgG autoantibodies from patients with IgAN harbor a sequence (amino acids YCSR/K) at the junction of framework 3 and the CDR3 in the variable part of the heavy chain (VH), wherein the serine residue is essential for Gd-IgA1 binding. This serine residue originates from a somatic hypermutation (Ala->Ser) and not from a genetic mutation of a VH germline gene. Our crystallographic studies with an IgAN-derived (YCSK) and a germline-reverted (YCAK) recombinant IgG autoantibody revealed that this seemingly minor difference in the amino-acid sequence had allosteric effects on elements surrounding the serine residue, generating a new surface juxtaposed to the CDR loops. This surface is a potential binding site for part of the Gd-IgA1 hinge-region glycopeptide and is a potential target for the design of IgG autoantibody inhibitors. In this proposal, we will determine the population- and individual-level variability of IgG autoantibodies in IgAN based on VH/VL sequences and Gd-IgA1 binding (Aim 1), determine the structural features of representative IgG autoantibodies and the molecular mechanism of Gd-IgA1 recognition (Aim 2), and develop approaches to block the binding of IgG autoantibodies to Gd-IgA1 (Aim 3). By leveraging our access to biobanked clinical samples, new patients, the new high-throughput approaches for cloning and expression of IgG autoantibodies specific Gd-IgA1, high-resolution methods for structural analyses, and high- throughput testing of inhibitors, our studies have progressed to a stage where molecular-level assessments of the autoantibodies will advance our understanding of the mechanisms that drive IgAN disease. The results of our studies will define disease-specific targets to prevent pathogenic immune-complex formation in IgAN.

IGA肾病（IGAN）是全球最常见的肾小球肾炎，导致终末期肾脏疾病 20-40％的患者可以将预期寿命降低长达10年，因为没有已知的治愈或疾病 - 具体处理。大多数IGAN患者，无论年龄和种族如何，都有免疫缺陷，导致 致病性IGA1免疫复合物的产生，最终沉积在肾脏中以诱导 肾脏受伤。这些肾脏免疫原子可能源自由IGA1组成的循环免疫复合物 与GD-IGA1特异性IgG自身抗体结合的铰链区域缺陷型O-Glycans（GD-IGA1）。这 该项目的长期目标是定义导致致病形成的基本机制 免疫复合物，以便可以开发出Igan特异性治疗。我们的假设是分子 Igan患者的GD-IGA特异性IgG自身抗体的水平表征与原子级相结合 免疫复合物中自身抗体的表征将显着提高我们对 Igan中的免疫复合形成。这些信息将为开发新的基础提供基础 疾病特异性治疗。在过去的三年中，调查人员的实验室使用了 生化，分子，结构和临床研究开始表征Igan特异性 自动抗体。我们已经表明，Igan Harbor A序列患者的IgG自身抗体（氨基） 在框架3的连接处的酸YCSR/K）和重链变量（VH）的CDR3， 其中所述丝氨酸残基对于GD-Iga1结合至关重要。该丝氨酸残留物起源于躯体 超代（ala-> ser），而不是来自VH种系基因的遗传突变。我们的晶体学研究 与Igan衍生（YCSK）和种系重组IgG自动抗体的相结合（YCAK）揭示了 在氨基酸序列中，这种看似较小的差异对周围元素具有变构影响 丝氨酸残留物，产生与CDR环并置的新表面。该表面是一个潜在的结合位点 对于GD-IGA1铰链区域糖肽的一部分，是设计IgG自身抗体的潜在目标 抑制剂。在此提案中，我们将确定IgG的人口和个人级别的变异性 基于VH/VL序列和GD-IGA1结合的IGAN自身抗体（AIM 1），确定结构性 代表性IgG自身抗体的特征和GD-IGA1识别的分子机制（AIM 2）， 并开发方法来阻止IgG自身抗体与GD-IGA1的结合（AIM 3）。通过利用我们的 访问生物循环的临床样本，新患者，新的高通量方法，用于克隆和 IgG自身抗体特定GD-IGA1的表达，结构分析的高分辨率方法和高分辨率 抑制剂的吞吐量测试，我们的研究已发展到分子级评估的阶段 自身抗体将提高我们对驱动Igan疾病的机制的理解。结果 我们的研究将定义疾病特异性靶标，以防止Igan中的致病性免疫复合形成。