Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada.
Human Metabolome Technologies, Tsuruoka, Yamagata 997-0052, Japan.
J Proteome Res. 2020 Jul 2;19(7):2689-2699. doi: 10.1021/acs.jproteome.9b00405. Epub 2019 Sep 26.
Nonalcoholic fatty liver disease (NAFLD) is the most common preventable chronic liver disorder in developed countries, the prevalence of which is increasing worldwide due to its association with obesity and type 2 diabetes. However, the exact mechanisms of NAFLD pathophysiology remain poorly understood including its progression to the more severe nonalcoholic steatohepatitis (NASH). New advances for early detection and monitoring of NASH progression are limited due to the lack of specific blood biomarkers, thus requiring invasive liver biopsies for histopathology. Herein, multisegment injection-capillary electrophoresis-tandem mass spectrometry (MSI-CE-MS/MS) is validated as a high throughput, robust, and quantitative platform for targeted analysis of a panel of 16 serum γ-glutamyl dipeptides from a cohort of NASH adult patients from Japan (median age = 53 years, median BMI = 27 kg/m, = 116). Multiplexed separations based on MSI-CE-MS/MS enable the design of unique data workflows that rely on customizable serial sample injection formats for accurate determination of γ-glutamyl dipeptides with quality control. Also, the introduction of a liquid coolant device to the capillary outlet improves long-term migration time stability in CE. Unsupervised pattern recognition methods revealed two distinctive NASH subgroups based on their contrasting γ-glutamyl dipeptide status despite patients having similar clinical phenotypes and NASH activity scores (median NAS ≈ 6.0). There was an inverse correlation between serum γ-glutamyl dipeptide concentrations and γ-glutamyltransferease (GGT) enzyme activity ( = -0.46; = 2.5 × 10), which was indicative of a low-risk ( = 64) as compared to a high-risk ( = 52) patient subgroup with impaired glutathione salvage pathway and likely poor clinical prognosis. Our findings highlight the key role of defects in the γ-glutamyl cycle for differentiation of NASH patients, which may enable better risk assessment of long-term survivorship as a complement to standard liver enzyme screens and histopathology.
非酒精性脂肪性肝病 (NAFLD) 是发达国家最常见的可预防的慢性肝病，由于其与肥胖和 2 型糖尿病相关，因此全球患病率正在上升。然而，NAFLD 病理生理学的确切机制仍知之甚少，包括其进展为更严重的非酒精性脂肪性肝炎 (NASH)。由于缺乏特异性血液生物标志物，用于早期检测和监测 NASH 进展的新进展受到限制，因此需要进行肝活检以进行组织病理学检查。在此，多段注射-毛细管电泳-串联质谱法 (MSI-CE-MS/MS) 经过验证，可作为一种高通量、稳健且定量的平台，用于对来自日本 NASH 成年患者队列的 16 种血清 γ-谷氨酰二肽进行靶向分析（中位数年龄= 53 岁，中位数 BMI= 27 kg/m，= 116）。基于 MSI-CE-MS/MS 的多复用分离能够设计独特的数据工作流程，该流程依赖于可定制的串行样品注入格式，以准确确定具有质量控制的 γ-谷氨酰二肽。此外，在毛细管出口处引入液体冷却装置可提高 CE 中的长期迁移时间稳定性。无监督模式识别方法揭示了两个截然不同的 NASH 亚组，尽管患者具有相似的临床表型和 NASH 活性评分（中位数 NAS≈6.0），但其 γ-谷氨酰二肽状态却截然不同。血清 γ-谷氨酰二肽浓度与 γ-谷氨酰转移酶 (GGT) 酶活性呈负相关（= -0.46；= 2.5×10），与谷胱甘肽补救途径受损和可能预后不良的低风险（= 64）相比，具有较高风险（= 52）的患者亚组相比，具有较低风险。我们的研究结果强调了 γ-谷氨酰循环缺陷在 NASH 患者中的关键作用，这可能使我们能够更好地评估长期生存风险，作为对标准肝酶筛查和组织病理学的补充。
