13C asymmetry in blood glucose as a marker for oxidative stress in liver

描述(申请人提供)：肝脏氧化还原状态的调节在正常生理和高冲击性疾病中发挥核心作用，包括非酒精性脂肪性肝病和许多药物引起的肝毒性。对于有这些问题的患者，建议进行肝活检，以监测肝脏氧化应激和其他疾病的进展，但它是侵入性的。需要一种简单、侵入性较小的方法来监测许多肝病的氧化还原破坏。开发一种方法来评估参与氧化应激反应和保护肝脏氧化还原状态的关键反应的通量将是有益的。磷酸戊糖途径(PPP)产生NADPH还原当量，这是抗氧化防御所必需的，它与肝脏葡萄糖的产生具有复杂的相互作用。最近我们发现，给予[U-13C3]甘油的肝脏在血糖的1-3和4-6碳之间产生了独特的13C不对称性，这对PPP和转醛醇酶活性很敏感。转醛醇酶是PPP非氧化阶段的关键酶，被认为在氧化应激下具有作用。在这里，我们假设在给予[U-13C3]甘油的情况下，肝脏产生和释放的13C葡萄糖同位素异构体对肝脏的氧化应激很敏感。为了测试这一点，我们将确定以下事件的相关性：对乙酰氨基酚压力或脂肪肝-&GT；肝脏氧化应激-GT；改变肝脏PPP和转醛醇酶活性--&GT；改变肝脏释放的葡萄糖的13C不对称性。将对啮齿动物模型和脂肪肝受试者进行研究，以确定慢性氧化应激导致的葡萄糖13C不对称。我们将确定非酒精性脂肪性肝炎患者的不对称是否能与单纯性脂肪变性区分开来。此外，我们将研究扑热息痛引起的肝脏毒性的啮齿动物模型，以及如果13C葡萄糖不对称对药物敏感的健康受试者给予治疗剂量的对乙酰氨基酚。结果将与基因表达数据和氧化应激测量的标准方法进行比较。整个过程很简单：[U-13C3]甘油摄取、抽血和13C核磁共振血糖分析。我们的目标是开发一种简单的方法，通过观察血糖中的13C不对称来识别和监测肝脏氧化应激，这种不对称很容易从单个血液样本中确定。

DESCRIPTION (provided by applicant): Regulation of hepatic redox state plays a central role in normal physiology and high-impact diseases including non-alcoholic fatty liver disease and hepatotoxicity induced by many drugs. Liver biopsy is recommended for patients with those problems to monitor hepatic oxidative stress and other progress of the diseases, but it is invasive. There is a demand for a simple, less invasive method to monitor redox disruption in many hepatic diseases. It would benefit to develop a method to assess flux in key reactions involved in the response to oxidative stress and protection of the redox state of the liver. The pentose phosphate pathway (PPP) produces NADPH reducing equivalent that is essential for antioxidant defense and it has intricate interactions with hepatic glucose production. Recently we found that the liver given [U- 13C3]glycerol produced unique 13C asymmetry between carbons 1-3 and 4-6 of blood glucose, which was sensitive to the PPP and transaldolase activity. Transaldolase, a key enzyme in the non-oxidative phase of the PPP, is considered to have roles under oxidative stress. Here we hypothesize that the amounts of 13C glucose isotopomers produced and released from the liver given [U-13C3]glycerol are sensitive to hepatic oxidative stress. To test this, we will determine correlations in the following events: acetaminophen stressed or fatty liver -> hepatic oxidative stress -> altered hepatic PPP and transaldolase activity -> altered 13C asymmetry of glucose released from the liver. Both rodent models and human subjects with fatty liver will be studied to determine 13C asymmetry of glucose caused by chronic oxidative stress. We will determine if the asymmetry from patients with nonalcoholic steatohepatitis can be distinguished from simple steatosis. In addition, we will study rodent models of acetaminophen-induced hepatotoxicity and healthy subjects given therapeutic doses of acetaminophen if 13C asymmetry of glucose is sensitive to the drug. The results will be compared with gene expression data and standard methods for oxidative stress measurement. The overall procedures are simple: [U-13C3]glycerol ingestion, blood draw and blood glucose analysis by 13C NMR. Liver fat content in human subjects will be measured using 1H MRS. Our goal is to develop a simple method to identify and monitor hepatic oxidative stress by observing 13C asymmetry in blood glucose, which is readily determined from a single blood sample.