Laboratory of Food and Regulation Biology, Graduate School of Bioscience, Tokai University, Kumamoto, Japan.
Department of Metabolic Medicine, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
J Biol Chem. 2024 Jul;300(7):107479. doi: 10.1016/j.jbc.2024.107479. Epub 2024 Jun 13.
Glucoselysine (GL) is an unique advanced glycation end-product derived from fructose. The main source of fructose in vivo is the polyol pathway, and an increase in its activity leads to diabetic complications. Here, we aimed to demonstrate that GL can serve as an indicator of the polyol pathway activity. Additionally, we propose a novel approach for detecting GL in peripheral blood samples using liquid chromatography-tandem mass spectrometry and evaluate its clinical usefulness. We successfully circumvent interference from fructoselysine, which shares the same molecular weight as GL, by performing ultrafiltration and hydrolysis without reduction, successfully generating adequate peaks for quantification in serum. Furthermore, using immortalized aldose reductase KO mouse Schwann cells, we demonstrate that GL reflects the downstream activity of the polyol pathway and that GL produced intracellularly is released into the extracellular space. Clinical studies reveal that GL levels in patients with type 2 diabetes are significantly higher than those in healthy participants, while N-(5-hydro-5-methyl-4-imidazolon-2-yl)ornithine (MG-H1) levels are significantly lower. Both GL and MG-H1 show higher values among patients with vascular complications; however, GL varies more markedly than MG-H1 as well as hemoglobin A1c, fasting plasma glucose, and estimated glomerular filtration rate. Furthermore, GL remains consistently stable under various existing drug treatments for type 2 diabetes, whereas MG-H1 is impacted. To the best of our knowledge, we provide important insights in predicting diabetic complications caused by enhanced polyol pathway activity via assessment of GL levels in peripheral blood samples from patients.
葡糖赖氨酸（GL）是一种独特的糖基化终产物，源自果糖。体内果糖的主要来源是多元醇途径，其活性增加会导致糖尿病并发症。在这里，我们旨在证明 GL 可以作为多元醇途径活性的指标。此外，我们提出了一种使用液相色谱-串联质谱法检测外周血样本中 GL 的新方法，并评估了其临床应用价值。我们通过超滤和水解（无需还原）成功避免了与 GL 分子量相同的果糖赖氨酸的干扰，成功生成了足够的血清定量峰。此外，我们使用永生化醛糖还原酶 KO 小鼠雪旺细胞证明，GL 反映了多元醇途径的下游活性，并且细胞内产生的 GL 被释放到细胞外空间。临床研究表明，2 型糖尿病患者的 GL 水平明显高于健康参与者，而 N-（5-羟-5-甲基-4-咪唑啉-2-基）鸟氨酸（MG-H1）水平明显降低。GL 和 MG-H1 在有血管并发症的患者中均显示出更高的值；然而，GL 的变化幅度比 MG-H1 以及糖化血红蛋白、空腹血糖和估计肾小球滤过率更为显著。此外，GL 在 2 型糖尿病的各种现有药物治疗下保持稳定，而 MG-H1 则受到影响。据我们所知，我们通过评估患者外周血样本中的 GL 水平，为预测由增强的多元醇途径活性引起的糖尿病并发症提供了重要的见解。
