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

• 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
• 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

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.

摘要 我们发表的工作揭示了ASN(N)连接蛋白糖基化的缺陷 减少小鼠的炎性脱髓鞘，并与多发性硬化(MS)相关。缺憾 在附着在蛋白质上的N-糖链的分支中，无论是在小鼠身上实验诱导的还是通过自然遗传诱导的 在人类中的变异，促进T细胞介导的炎性脱髓鞘和神经变性。为 例如，分支缺陷会在PL/J小鼠中诱导一种自发的、进展缓慢的类似MS的疾病， 以炎症性脱髓鞘、轴突损伤和神经元死亡为特征。从机械上讲， 分支和每个蛋白质分子的N-糖链数量协同调节与Galectins的结合，A 14- 糖结合蛋白家族成员。半乳糖凝集素通过其附着的N-糖蛋白与细胞表面糖蛋白结合 多聚糖，在细胞表面形成一个大分子晶格，控制着分布，聚集和 以协调和可预测的方式内吞表面糖蛋白。N-葡聚糖显著分枝 通过减少T细胞受体聚集/免疫信号转导来抑制小鼠和人类的T细胞活性 突触，促进生长抑制因子CTLA-4的表面滞留，抑制分化为前体细胞 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细胞表型是炎性脱髓鞘的重要调节因子，这一点已经变得越来越清楚 B细胞在多发性硬化症中也起着关键作用，这一点最好的例证是B细胞耗尽的强大活性 治疗多发性硬化症，如抗CD20单抗奥曲珠单抗。B细胞在免疫系统中是独一无二的 既有先天免疫活性又有获得性免疫活性的系统；前者的例子是通过类Toll激活 受体(TLR)和抗原提呈细胞(APC)具有触发T细胞反应的功能。它的作用机制 Ocriszumab的作用似乎主要是由于先天免疫活性降低而不是改变 抗体产生，因为ocriszumab降低了T细胞数量，但不能降低抗体或血浆细胞水平 治疗后多发性硬化症患者的脑脊液。在这里，我们检验了N-葡聚糖分支作为 B细胞中促炎症天然免疫活性的关键负调节因子抑制促炎症反应 炎性T细胞反应和炎性脱髓鞘。要评估这一假设，请看以下内容 提出了目标。目的1研究B细胞中N-糖链分支对TLR4和TLR2反应的调节。 目的2研究N-糖链分支对B细胞受体信号的调节。目标3检查N- B细胞中的葡聚糖分支抑制炎性脱髓鞘。阳性结果将确定N-糖链 分支作为B细胞介导的炎性脱髓鞘调节的主要贡献者 了解B细胞去除疗法在多发性硬化中的作用机制