Investigating the involvement of small intestine in metformin's effect on hepatic lipid metabolism

项目摘要 尽管非酒精性脂肪性肝病(NAFLD)的发病率很高，但目前还没有批准的 治疗非酒精性脂肪肝的药物。二甲双胍经常被认为是治疗非酒精性脂肪肝的一种有前景的疗法，但有报道称 关于二甲双胍对NAFLD患者的疗效并不一致。因此，二甲双胍对肝脏脂质的影响 新陈代谢和潜在的机制值得进一步研究。二甲双胍被认为可以直接调节 肝脏脂质代谢通过激活肝脏AMP激活的蛋白激酶(AMPK)，随后 抑制新生脂肪生成，促进肝脏中的脂肪酸氧化。然而，目前还缺乏量化的 评估体内二甲双胍对肝脏脂肪生成或脂肪酸氧化的影响程度。在……里面 此外，由于二甲双胍在肠道中的浓度很高，肠道已成为重要的 二甲双胍的作用部位。黄博士培育了肠上皮特异性AMPKα1基因敲除小鼠和 观察到二甲双胍在这些小鼠中的有益作用减弱(自然通讯2022)， 提示二甲双胍在肠道中的作用是纠正饮食引起的代谢紊乱所必需的。 由于二甲双胍的多效性，代谢组学、脂质组学和13C同位素等组学分析 将需要追踪以定量和系统地评估二甲双胍在不同组织中的代谢影响。 器官。在一项初步研究中，我使用液相色谱联用进行了代谢组学和脂类组学分析 高分辨质谱仪(LC-HRMS)。初步数据表明，代谢物的数量 而二甲双胍改变的血脂与这些组织中二甲双胍的浓度呈正相关，并且 二甲双胍引起的代谢和脂体改变在肠道中更为深刻，因为 在肠道中的浓度。我们还合成了一种含有炔基的二甲双胍探针，它将被 用于识别二甲双胍的分子靶点。在接下来的五年里，我将结合我在组学方面的专业知识 用二甲双胍探针和黄博士开发的转基因小鼠进行分析，以验证假设 二甲双胍诱导肠道中有益的代谢和脂肪改变，增强肠道功能(例如， 糖分清除)，从而保护肝脏免受饮食损伤。这样做的直接目标是 该项目旨在阐明二甲双胍保护肝脏的作用部位和潜在机制。 对抗高果糖引起的代谢损伤。长期目标是1)制定战略，以加强 肠上皮细胞的代谢能力对减轻肝脏脂肪变性和2)提供洞察 确定可能受益于二甲双胍单一疗法的非酒精性脂肪肝患者，并制定最佳策略 预防或治疗非酒精性脂肪肝。尽管这项拟议的研究集中在饮食方面的二甲双胍- 这项研究中的诱导性肝病、方法和发现有望对疾病产生广泛的影响 新陈代谢失调。

Project Summary Despite the high prevalence of nonalcoholic fatty liver disease (NAFLD), there are currently no approved medications to treat NAFLD. Metformin is frequently discussed as a promising treatment for NAFLD but reports on the efficacy of metformin in NAFLD patients are not consistent. Hence, the effect of metformin on hepatic lipid metabolism and the underlying mechanisms warrant further research. Metformin is thought to directly regulate hepatic lipid metabolism via activating hepatic AMP-activated protein kinase (AMPK), which subsequently inhibits de novo lipogenesis and promotes fatty acid oxidation in liver. However, there is a lack of quantitative assessment of to what extent hepatic lipogenesis or fatty acid oxidation is affected by metformin in vivo. In addition, due to high concentrations of metformin in the intestine, the intestine has emerged as an important action site of metformin. Dr. Huang generated intestinal epithelium-specific AMPK alpha 1 knockout mice and observed that the beneficial effect of metformin was attenuated in these mice (Nature Communications 2022), suggesting that the action of metformin in intestine is required for correcting dietary-induced metabolic disorders. Due to the pleiotropic effects of metformin, omics analysis such as metabolomics, lipidomics, and 13C isotope tracing will be required to quantitively and systemically assess the metabolic effects of metformin in different organs. In a pilot study, I performed metabolomics and lipidomics analysis using liquid chromatography coupled to high resolution mass spectrometer (LC-HRMS). The preliminary data suggest that the number of metabolites and lipids altered by metformin positively correlated with concentrations of metformin in these tissues, and metformin-induced metabolic and lipidomic changes were more profound in intestine due to the high concentration in intestine. We also synthesized a metformin probe containing an alkyne group, which will be used to identify the molecular target of metformin. In the next five years, I will combine my expertise in omics analysis with metformin probe and genetically modified mice developed by Dr. Huang to test the hypothesis that metformin induces beneficial metabolic and lipidomic alterations in intestine, enhances intestinal functions (e.g., sugar clearance) and subsequently shields liver from dietary-induced damage. The immediate goal of this project is to elucidate the action site and underlying mechanisms through which metformin protects the liver against high fructose-induced metabolic damage. The long-term goal is to 1) develop strategies to enhance the metabolic capacity of intestinal epithelial cells for alleviating liver steatosis and 2) to provide insights into identifying NAFLD patients who likely benefit from metformin monotherapy and developing optimal strategies to prevent or treat NAFLD. Even though this proposed study is focused on metformin in the context of dietary- induced liver disease, methods and discoveries in this study are expected to make a broad impact in diseases with dysregulated metabolism.