Adipogenic changes of hepatocytes in a high-fat diet-induced fatty liver mice model and non-alcoholic fatty liver disease patients
Adipogenic changes of hepatocytes in a high-fat diet-induced fatty liver mice model and non-alcoholic fatty liver disease patients
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高脂饮食诱导的脂肪肝小鼠模型和非酒精性脂肪肝患者肝细胞的成脂变化
DOI：
10.1007/s12020-014-0384-x
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发表时间：
2015-04-01
期刊：
影响因子：
3.7
通讯作者：
Hou, Xiaohua
中科院分区：
文献类型：
--
作者：
Pan, Xiaoli;Wang, Pei;Hou, Xiaohua
非酒精性脂肪性肝病（NAFLD）的特征是与肝脏炎症相关的脂肪变性。随着NAFLD的进展，肝细胞内甘油三酯增加，导致类似脂肪细胞的典型空泡。然而，肝细胞的这些形态学变化是否表明潜在的功能改变尚不清楚。C57BL/6J小鼠饲喂脂肪含量为42%的高脂日粮。采用实时PCR、Western blot和双重免疫荧光标记法测定肝脏脂肪细胞标志物。ELISA法定量细胞培养上清中的细胞因子。为了确定巨噬细胞表型，分析肝脏经典M1标记物和替代M2标记物。饲喂24周后，hfd喂养小鼠肝脏脂肪细胞标志物aP2和PPARγ mRNA和蛋白水平均升高。共聚焦激光扫描显微镜下，脂肪变性肝细胞胞浆中均可见fitc标记的aP2和罗丹明标记的白蛋白。与对照组相比，脂肪变性肝细胞中细胞膜结合的e-钙粘蛋白和白蛋白表达减少。然而，肝脏脂联素和脂联素受体-2的表达随着肝脏CD36的上调而下降，表明脂联素活性在喂食hfd的小鼠肝脏中受损。此外，脂肪变性原代肝细胞在体外共培养时不仅能释放TNFα、MCP-1、IL-6、IL-18等促炎细胞因子，还能激活巨噬细胞。在体内，饲喂hfd的小鼠肝脏中iNOS和TNFα等M1基因的表达显著增加。相反，M2基因如Arg1和CD206的肝脏表达明显降低。具体来说，hfd喂养小鼠中TNFα与CD206的比例明显上调。脂肪细胞特异性基因在肝细胞中的过度表达及其分泌功能和NAFLD的上皮表型损害导致脂肪变性肝细胞除形态学改变外的功能改变。这表明肝细胞的脂肪生成改变参与了NAFLD的发病机制。
Non-alcoholic fatty liver disease (NAFLD) is characterized by steatosis associated with liver inflammation. As NAFLD progresses, triglycerides increase within hepatocytes, causing typical vacuoles that resemble adipocytes. However, whether these morphological changes in hepatocytes indicate potential functional changes is unclear. C57BL/6J mice were fed a high-fat diet (HFD) containing 42 % fat. Markers for adipocytes in the liver were measured using real-time PCR, Western blot, and double immunofluorescent labeling. Cytokines in cell culture supernatants were quantified with ELISA. To determine the macrophage phenotype, hepatic classical M1 markers and alternative M2 markers were analyzed. After a 24-week feeding period, adipocyte markers aP2 and PPARγ increased at both the mRNA and protein level in the liver of HFD-fed mice. FITC-labeled aP2 and rhodamine-labeled albumin were both stained in the cytoplasm of steatotic hepatocytes as observed under confocal laser scanning microscopy. Cell membrane-bound E-cadherin and albumin expression were reduced in steatotic hepatocytes compared to controls. However, hepatic adiponectin and adiponectin receptor-2 expression decreased with upregulation of hepatic CD36, suggesting impaired adiponectin activity in livers of HFD-fed mice. Moreover, steatotic primary hepatocytes not only released pro-inflammatory cytokines such as TNFα, MCP-1, IL-6, and IL-18, but also could activate macrophages when co-cultured in vitro. In vivo, hepatic expression of M1 genes such as iNOS and TNFα was markedly increased in HFD-fed mice. In contrast, hepatic expression of M2 genes such as Arg1 and CD206 was significantly reduced. Specifically, the ratio of TNFα to CD206 in HFD-fed mice was notably upregulated. Overexpression of adipocyte-specific genes in hepatocytes and their secretory function and epithelial phenotype impairment in NAFLD cause functional changes in steatotic hepatocytes aside from morphological changes. This suggests that adipogenic changes in hepatocytes are involved in pathogenesis of NAFLD.