Impaired T cell immunity in the Elderly via enhanced N-glycosylation.

描述（由申请人提供）：T细胞免疫力受损以及对感染和免疫的反应是老年人的常见特征。我们以前已经表明，天冬酰胺（N）连接的蛋白质糖基化作为一个关键的负调节T细胞免疫在小鼠和人类。事实上，动物细胞中所有的细胞表面和分泌蛋白质都通过在ER/高尔基体分泌途径中添加复合碳水化合物来修饰，提供基因组中未编码的分子信息。每个蛋白质分子的N-聚糖的分支和数量协同调节与半乳糖凝集素的结合，形成以可预测的方式控制表面糖蛋白的分布、聚集和内吞作用以影响细胞生长和分化的分子晶格。N-甘聚糖分支的遗传和代谢控制负调节T细胞受体聚集/信号传导，增强抗炎受体细胞毒性T淋巴细胞抗原4（CTLA-4）和转化生长因子β受体（TR）的表面保留，抑制促炎性TH 1和TH 17，同时促进抗炎性TH 2和诱导的T调节细胞（iTreg）分化。通过补充单糖N-乙酰葡萄糖胺（GlcNAc）代谢增加高尔基体酶的底物供应，在体外和体内增加T细胞中的N-聚糖分支，抑制T细胞生长，增强CTLA-4和TGF-β RI/II表面表达，阻断TH 1/TH 17分化并抑制自身免疫。初步分析表明，人类和小鼠的衰老与血清GlcNAc水平和T细胞（包括幼稚、中枢和效应记忆T细胞）中N-聚糖分支的增加有关。事实上，通过使用小分子高尔基体抑制剂下调N-聚糖分支来挽救老年小鼠和人T细胞中的低增殖体外应答。我们推测，年龄依赖性增加的N-聚糖分支显着有助于受损的T细胞免疫和低反应性感染/免疫在老年人。为了证实和扩展这一假设，提出了以下目标。目的1将证实老年人T细胞亚群中N-聚糖分支增加。目标2将证实，N-聚糖分支的遗传和小分子抑制使老年人的T细胞应答恢复活力。目的3研究N-聚糖分支的年龄依赖性增加的机制，研究遗传和代谢调节。阳性结果将表明下调N-聚糖分支作为恢复老年人T细胞应答的治疗策略。

DESCRIPTION (provided by applicant): Impaired T cell immunity and response to infection and immunization is a common feature in the elderly. We have previously shown that Asparagine (N) - linked protein glycosylation serves as a critical negative regulator of T cell immunity in both mice and humans. Virtually all cell surface and secreted proteins in animal cells are modified by the addition of complex carbohydrates in the ER/Golgi secretory pathway, providing molecular information not encoded in the genome. The branching and number of N-glycans per protein molecule cooperate to regulate binding to galectins, forming a molecular lattice that controls the distribution, clustering and endocytosis of surface glycoproteins in a predictable manner to affect cell growth and differentiation. Genetic and metabolic control of N-glyan branching negatively regulates T cell receptor clustering/signaling, enhances surface retention of the anti-inflammatory receptors Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4) and Transforming Growth Factor - � receptor (T�R) and inhibits pro-inflammatory TH1 and TH17 while promoting anti-inflammatory TH2 and induced T regulatory cell (iTreg) differentiation. Increasing N-glycan branching in T cells in vitro and in vivo by metabolically increasing substrate supply to Golgi enzymes via supplementation with the simple sugar N-acetylglucosamine (GlcNAc) suppresses T cell growth, enhances CTLA-4 and TGF-�RI/II surface expression, blocks TH1/TH17 differentiation and inhibits autoimmunity. Preliminary analysis suggests aging in humans and mice is associated with increases in serum GlcNAc levels and N-glycan branching in T cells, including na�ve, central and effector memory T cells. Indeed, hypo-proliferative in vitro responses in aged mouse and human T cells is rescued by down-regulating N-glycan branching using a small molecule Golgi inhibitor. We hypothesize that age-dependent increases in N-glycan branching significantly contributes to impaired T cell immunity and hypo-responsiveness to infection/immunization in the elderly. To confirm and expand on this hypothesis, the following aims are proposed. Aim 1 will confirm increased N-glycan branching in human T cell subsets of the elderly. Aim 2 will confirm that genetic and small molecule inhibition of N-glycan branching rejuvenates T cell responses in the elderly. Aim 3 examines the mechanism for age dependent increases in N-glycan branching, examining both genetic and metabolic regulation. Positive results will suggest down-regulation of N-glycan branching as a therapeutic strategy to rejuvenate T cell responses in the elderly.