von Loeffelholz Christian, Döcke Stephanie, Lock Johan F, Lieske Stefanie, Horn Paul, Kriebel Jennifer, Wahl Simone, Singmann Paula, de Las Heras Gala Tonia, Grallert Harald, Raschzok Nathaniel, Sauer Igor M, Heller Regine, Jahreis Gerhard, Claus Ralf A, Bauer Michael, Stockmann Martin, Birkenfeld Andreas L, Pfeiffer Andreas F H
Department of Clinical Nutrition, German Institute of Human Nutrition, Potsdam-Rehbruecke, Germany.
Department of Anaesthesiology and Intensive Care, Jena University Hospital, and Integrated Research and Treatment Center, Center for Sepsis Control and Care (CSCC), Friedrich Schiller University, Jena, Germany.
Hepatol Res. 2017 Aug;47(9):890-901. doi: 10.1111/hepr.12825. Epub 2016 Nov 18.
Molecular adaptations in human non-alcoholic fatty liver disease (NAFLD) are incompletely understood. This study investigated the main gene categories related to hepatic de novo lipogenesis and lipid oxidation capacity.
Liver specimens of 48 subjects were histologically classified according to steatosis severity. In-depth analyses were undertaken using real-time polymerase chain reaction, immunoblotting, and immunohistochemistry. Lipid profiles were analyzed by gas chromatography/flame ionization detection, and effects of key fatty acids were studied in primary human hepatocytes.
Real-time polymerase chain reaction, immunoblotting, and immunohistochemistry indicated 5'AMP-activated protein kinase (AMPK) to be increased with steatosis score ≥ 2 (all P < 0.05), including various markers of de novo lipogenesis and lipid degradation (all P < 0.05). Regarding endoplasmic reticulum stress, X-Box binding protein-1 (XBP1) was upregulated in steatosis score ≥ 2 (P = 0.029) and correlated with plasma palmitate (r = 0.34; P = 0.035). Palmitate incubation of primary human hepatocytes increased XBP1 and downstream stearoyl CoA desaturase-1 mRNA expression (both P < 0.05). Moreover, plasma and liver tissue exposed a NAFLD-related lipid profile with reduced polyunsaturated/saturated fatty acid ratio, increased palmitate and palmitoleate, and elevated lipogenesis and desaturation indices with steatosis score ≥ 2 (all P < 0.05).
In humans with advanced fatty liver disease, hepatic AMPK protein is upregulated, potentially in a compensatory manner. Moreover, pathways of lipid synthesis and degradation are co-activated in subjects with advanced steatosis. Palmitate may drive lipogenesis by activating XBP1-mediated endoplasmic reticulum stress and represent a target for future dietary or pharmacological intervention.
人类非酒精性脂肪性肝病（NAFLD）中的分子适应性变化尚未完全明确。本研究调查了与肝脏从头脂肪生成和脂质氧化能力相关的主要基因类别。
根据脂肪变性严重程度对48名受试者的肝脏标本进行组织学分类。采用实时聚合酶链反应、免疫印迹和免疫组织化学进行深入分析。通过气相色谱/火焰离子化检测分析脂质谱，并在原代人肝细胞中研究关键脂肪酸的作用。
实时聚合酶链反应、免疫印迹和免疫组织化学表明，脂肪变性评分≥2时，5'AMP激活蛋白激酶（AMPK）增加（所有P<0.05），包括从头脂肪生成和脂质降解的各种标志物（所有P<0.05）。关于内质网应激，X盒结合蛋白1（XBP1）在脂肪变性评分≥2时上调（P = 0.029），并与血浆棕榈酸酯相关（r = 0.34；P = 0.035）。原代人肝细胞经棕榈酸酯孵育后，XBP1和下游硬脂酰辅酶A去饱和酶-1 mRNA表达增加（均P<0.05）。此外，血浆和肝组织呈现出与NAFLD相关的脂质谱，多不饱和/饱和脂肪酸比值降低，棕榈酸酯和棕榈油酸酯增加，脂肪生成和去饱和指数在脂肪变性评分≥2时升高（所有P<0.05）。
在晚期脂肪性肝病患者中，肝脏AMPK蛋白上调，可能是一种代偿方式。此外，在晚期脂肪变性患者中，脂质合成和降解途径共同激活。棕榈酸酯可能通过激活XBP1介导的内质网应激来驱动脂肪生成，是未来饮食或药物干预的一个靶点。
