Laboratory of Glycobiology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República, 2780-157, Oeiras, Portugal.
GlycoThera GmbH, Feodor-Lynen Strasse 35, 30625, Hannover, Germany.
Mol Neurobiol. 2019 Aug;56(8):5729-5739. doi: 10.1007/s12035-019-1482-9. Epub 2019 Jan 23.
Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease for which the existing candidate biomarkers (neurofilaments) have low specificity. Changes in blood IgG N-glycosylation have been observed in several diseases, including ALS, whereas cerebrospinal fluid (CSF) IgG has been less studied. Here, we characterized N-glycans of CSF IgG from ALS patients in comparison with a control group of other neurological diseases. Cerebrospinal fluid was collected from patients with ALS (n = 26) and other neurological diseases (n = 10). N-Glycans were released from CSF purified IgG with peptide N-glycosidase F, labeled with 2-aminobenzamide and analyzed by NP-HPLC chromatography in combination with exoglycosidase digestion and MALDI-TOF mass spectrometry. The N-glycosylation profile of ALS CSF IgG consisted of diantennary N-glycans predominantly with proximal fucose and some bisecting GlcNAc; agalacto-, mono-, and digalactosylated as well as α2,6-sialylated structures were detected. Differences between ALS and control patients were observed; most relevant was the increase in ALS CSF IgG of the level of galactosylated structures defined here as Gal-index (median 46.87 and 40.50% for ALS and controls, respectively; p = 0.006). The predictive value of the Gal-index (AUC = 0.792, p = 0.007) considering ROC analysis had potential utility as a diagnostic test for ALS and was comparable to that of phosphoneurofilament heavy chain (AUC = 0.777, p = 0.011), which was used as benchmark marker for our group of patients. The results provide the basis to further explore the potential of IgG N-glycan galactosylation as biomarker for ALS by using larger cohorts of patients and controls.
肌萎缩侧索硬化症（ALS）是一种致命的运动神经元疾病，其现有候选生物标志物（神经丝）特异性较低。在包括 ALS 在内的几种疾病中，已经观察到血液 IgG N-糖基化的变化，而脑脊液（CSF）IgG 的研究较少。在这里，我们比较了 ALS 患者与其他神经系统疾病对照组的 CSF IgG 的 N-糖基化特征。从 ALS 患者（n=26）和其他神经系统疾病患者（n=10）收集 CSF。用肽 N-糖苷酶 F 从 CSF 纯化 IgG 中释放 N-聚糖，用 2-氨基苯甲酰胺标记，并通过 NP-HPLC 色谱分析与外糖苷酶消化和 MALDI-TOF 质谱联用。ALS CSF IgG 的 N-糖基化谱由二天线 N-聚糖组成，主要带有近端岩藻糖，有些带有双分支 GlcNAc；检测到agalacto、mono 和 digalactosylated 以及α2,6-唾液酸化结构。在 ALS 和对照组患者之间观察到差异；最相关的是 ALS CSF IgG 中 galactosylated 结构水平的增加，这里定义为 Gal-index（中位数分别为 46.87%和 40.50%；p=0.006）。考虑到 ROC 分析，Gal-index（AUC=0.792，p=0.007）的预测值作为 ALS 的诊断测试具有潜在的效用，并且与我们组患者中使用的磷酸神经丝重链（AUC=0.777，p=0.011）相当。该结果为进一步探索 IgG N-聚糖半乳糖基化作为 ALS 生物标志物的潜力提供了基础，方法是使用更大的患者和对照组队列。
