Regulation of B cell function in demyelinating disease by N-glycan branching

N-聚糖分支调节脱髓鞘疾病中的 B 细胞功能

基本信息

批准号：
10311524
负责人：
MICHAEL DEMETRIOU
金额：
$ 50.05万
依托单位：
UNIVERSITY OF CALIFORNIA-IRVINE
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-01-14 至 2023-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10311524
关键词：
Anti-Inflammatory Agents Antibody Formation Antigen-Presenting Cells Antigens Autoimmune Diseases Autoimmunity B cell therapy B-Cell Antigen Receptor B-Lymphocytes Binding Binding Proteins CD19 gene CTLA4 gene Cell Count Cell Differentiation process Cell physiology Cell surface Cells Cerebrospinal Fluid Data Demyelinating Diseases Demyelinations Disease Endocytosis Environment Family member Galactose Binding Lectin Genetic Genetic Variation Growth Inhibitors Human Human Genetics Hyperactivity Immune Immune system Individual Inflammatory Interleukin-10 Ligands Mediating Membrane Glycoproteins Metabolic Mixed Lymphocyte Culture Test Monoclonal Antibody CD20 Multiple Sclerosis Mus Nerve Degeneration PL/J Mouse PLCgamma2 Pathway interactions Phenotype Plasma Cells Play Polysaccharides Predisposition Production Protein Glycosylation Proteins Publishing Receptor Signaling Regulation Role Signal Transduction Surface T cell response T-Cell Receptor T-Lymphocyte TLR2 gene TLR4 gene TNF gene Testing Th1 Cells Th2 Cells Toll-like receptors Work adaptive immune response anti-CD20 axon injury immune function immunological synapse link protein multiple sclerosis patient neuron loss receptor receptor function response sugar virtual

项目摘要

Abstract Our published work has revealed that deficiencies in Asn (N)-linked protein glycosylation reduce inflammatory demyelination in mice and are associated with Multiple Sclerosis (MS). Deficiency in the branching of N-glycan's attached to proteins, either induced experimentally in mice or via natural genetic variation in humans, promotes T-cell mediated inflammatory demyelination and neurodegeneration. For example, branching deficiency induces a spontaneous and slowly progressive MS-like disease in PL/J mice, characterized by inflammatory demyelination, axonal damage and neuronal death. Mechanistically, the branching and number of N-glycans per protein molecule cooperate to regulate binding to galectins, a 14- member family of sugar binding proteins. Galectin binding to cell surface glycoproteins, via their attached N- glycans, forms a macro-molecular lattice at the cell surface that controls the distribution, clustering and endocytosis of surface glycoproteins in a coordinated and predictable manner. N-glycan branching markedly inhibits T cell activity in mice and humans by reducing T cell receptor clustering/signaling at the immune synapse, promoting surface retention of the growth inhibitor CTLA-4 and inhibiting differentiation into pro- inflammatory TH1 and TH17 cells while promoting anti-inflammatory iTreg and TH2 cell differentiation. Although these T cell phenotypes are important regulators of inflammatory demyelination, it has become increasing clear that B cells also play a critical role in MS. This is best exemplified by the potent activity of B cell depleting therapies in MS, such as the anti-CD20 monoclonal antibody ocrelizumab. B cells are unique in the immune system by having both innate and adaptive immune activity; the former exemplified by activation via Toll-like receptors (TLR) and antigen-presenting cell (APC) functions that trigger T cell responses. The mechanism of action of ocrelizumab appears to primarily result from reduced innate immune activity rather than altering antibody production, as ocrelizumab reduces T cell number but not antibody or plasma cell levels in the cerebral spinal fluid of treated MS patients. Here we test the hypothesis that N-glycan branching serves as a critical negative regulator of pro-inflammatory innate immune activity in B cells to suppress pro- inflammatory T cell responses and inflammatory demyelination. To evaluate this hypothesis, the following Aims are proposed. Aim 1 examines regulation of TLR4 and TLR2 responses by N-glycan branching in B cells. Aim 2 examines regulation of B cell receptor signaling by N-glycan branching. Aim 3 examines whether N- glycan branching in B cells suppresses inflammatory demyelination. Positive results will identify N-glycan branching as a major contributor to B cell mediated regulation of inflammatory demyelination and has implications for understanding the mechanism of action of B cell depleting therapies in MS.

抽象的我们发表的工作揭示了 Asn (N) 连接蛋白糖基化的缺陷减少小鼠炎症性脱髓鞘，并与多发性硬化症 (MS) 相关。不足在与蛋白质相连的 N-聚糖的分支中，通过小鼠实验诱导或通过自然遗传诱导人类的变异，促进 T 细胞介导的炎症脱髓鞘和神经变性。为了例如，分支缺陷会在 PL/J 小鼠中诱发自发且缓慢进展的 MS 样疾病，其特征是炎症性脱髓鞘、轴突损伤和神经元死亡。从机械上来说，每个蛋白质分子的 N-聚糖分支和数量共同调节与半乳糖凝集素的结合，半乳糖凝集素是一种 14- 糖结合蛋白的成员家族。半乳糖凝集素通过其附着的 N- 与细胞表面糖蛋白结合聚糖，在细胞表面形成大分子晶格，控制分布、聚集和以协调和可预测的方式进行表面糖蛋白的内吞作用。 N-聚糖分支明显通过减少免疫系统中 T 细胞受体聚集/信号传导来抑制小鼠和人类的 T 细胞活性突触，促进生长抑制剂 CTLA-4 的表面保留并抑制分化为亲细胞炎症TH1和TH17细胞，同时促进抗炎iTreg和TH2细胞分化。虽然这些T细胞表型是炎症脱髓鞘的重要调节因子，这一点已经变得越来越清楚 B 细胞在 MS 中也发挥着关键作用。 B 细胞消耗的有效活性就是最好的例证 MS 疗法，例如抗 CD20 单克隆抗体 ocrelizumab。 B细胞在免疫系统中具有独特的作用具有先天性和适应性免疫活性的系统；前者通过类似 Toll 的激活为例受体 (TLR) 和抗原呈递细胞 (APC) 具有触发 T 细胞反应的功能。其机制为 ocrelizumab 的作用似乎主要是由于先天免疫活性降低而不是改变抗体的产生，因为 ocrelizumab 会减少 T 细胞数量，但不会减少体内抗体或浆细胞水平接受治疗的多发性硬化症患者的脑脊液。在这里，我们测试 N-聚糖分支充当的假设 B 细胞中促炎先天免疫活性的关键负调节因子，可抑制促炎性先天免疫活性炎症 T 细胞反应和炎症脱髓鞘。为了评估这个假设，以下提出了目标。目标 1 检查 B 细胞中 N 聚糖分支对 TLR4 和 TLR2 反应的调节。目标 2 检查 N-聚糖分支对 B 细胞受体信号传导的调节。目标 3 检查是否 N- B 细胞中的聚糖分支可抑制炎症脱髓鞘。阳性结果将识别 N-聚糖分支是 B 细胞介导的炎症脱髓鞘调节的主要贡献者对理解 B 细胞耗竭疗法在多发性硬化症中的作用机制的意义。