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

描述（由申请人提供）：T细胞免疫功能受损以及对感染和免疫的反应是老年人的共同特征。我们之前已经证明，在小鼠和人类中，天冬酰胺(N)连接蛋白糖基化是T细胞免疫的关键负调节因子。在动物细胞中，几乎所有的细胞表面和分泌蛋白都可以通过在内质网/高尔基体分泌通路中添加复合碳水化合物来修饰，从而提供基因组中未编码的分子信息。每个蛋白质分子的分支和n -聚糖的数量协同调节与凝集素的结合，形成分子晶格，以可预测的方式控制表面糖蛋白的分布、聚集和内吞作用，从而影响细胞的生长和分化。N-glyan分支的遗传和代谢控制负调控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-受体（T¿R）的表面保留，抑制促炎TH1和TH17，同时促进抗炎TH2和诱导T调节细胞（iTreg）分化。通过补充单糖n -乙酰氨基葡萄糖（GlcNAc）代谢增加高尔基酶的底物供应，从而增加T细胞内n -聚糖分支，抑制T细胞生长，增强CTLA-4和TGF-¿RI/II表面表达，阻断TH1/TH17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na - ve、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抑制剂下调n-聚糖分支，老年小鼠和人类T细胞的体外低增殖反应得以恢复。我们假设，年龄依赖性的n -聚糖分支增加显著有助于老年人T细胞免疫功能受损和对感染/免疫反应低下。为了证实和扩展这一假设，提出了以下目标。目的1将证实老年人类T细胞亚群中n -聚糖分支增加。目的2将证实遗传和小分子抑制n -聚糖分支使老年人的T细胞反应恢复活力。目的3研究年龄依赖性n -聚糖分支增加的机制，检查遗传和代谢调节。阳性结果将提示下调n-聚糖分支作为一种治疗策略来恢复老年人的T细胞反应。

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.