敲除Nrf2促进高脂饮食诱导小鼠肝脏NF-kB的活化

目的：氧化应激和炎症反应是NASH进展的关键因素,同时二者之间存在着密切关系,而转录因子Nrf2和NF-kB分别是氧化应激和炎症信号通路的关键调控靶点,因此,研究Nrf2对高脂饮食诱导小鼠肝脏NF-kB信号通路的影响,对探讨NASH进展具有重要的意义。方法：雄性野生型（WT）和Nrf2基因敲除（Nrf2-/-）ICR小鼠各10只,随机分为WT对照组（Control）、Nrf2-/-对照组（KO）、WT高脂饮食组（HFD）和Nrf2-/-高脂饮食组（KOHFD）（n=5）。喂养8周后,观察肝脏光镜下改变,检测肝脏GSH、MDA、TNFα和IL-6水平。Western-Blot检测肝脏NF-kB蛋白表达水平,观察敲除Nrf2对肝脏NF-kB活性作用的影响。结果：1.光镜下观察,Control组与KO组小鼠肝脏结构无明显变化,HFD组小鼠肝脏呈现大片脂肪沉积和炎症细胞浸润,KOHFD组小鼠肝脏则呈现明显的大泡性变性,且炎症细胞浸润较HFD组明显加重;2.与Control组相比,KO组小鼠肝脏MDA轻度升高,GSH轻度降低,但无明显差异,而HFD组和KOHFD组小鼠肝脏MDA显著升高（P〈0.05）,GSH显著降低（P〈0.05）,且KOHFD组MDA明显高于HFD组（P〈0.05）,GSH明显低于HFD组（P〈0.05）。3.ELISA结果显示,与Control组相比,KO组小鼠肝脏TNFα和IL-6分泌轻度增加,而HFD组和KOHFD组小鼠肝脏TNFα与IL-6水平显著升高（P〈0.05）,且KOHFD组小鼠肝脏TNFα与IL-6显著高于HFD组（P〈0.05）;4.Western-Blot结果显示,Control组和KO组之间无明显差异,而KOHFD组和HFD组小鼠肝脏胞核NF-kB蛋白表达水平显著升高,且KOHFD组高于HFD组。结论：敲除Nrf2可以显著加重高脂饮食诱导的小鼠肝脏氧化应激水平,进而促进NF-kB的活化,从而为通过以Nrf2为靶点治疗NASH提供重要的实验依据。

Loss of Nrf2 Promotes the Activation of Liver NF-kB in High-fat Diet Fed Mice

Objective： To investigate the effect of loss of Nrf2 on the activation of liver NF-kB in high fat diet fed mice. Methods：Male wild type（WT） mice（n=10） and Nrf2-null mice（n=10） on ICR background were fed a normal diet or a high fat diet for 8 weeks.Then the changes of pathology of liver were observed. The levels of hepatic methane dicarboxylic aldehyde（MDA）,glutathione（GSH）,TNFα and IL-6 were examined. The expression of liver NF-kB were determined by western-blot. Results： 1.Compared with control group, HFD feeding at week 8 increased the hepatic MDA concentrations in both HFD and KOHFD mice. Also the magnitude of the increase was greater in the KOHFD mice than in the HFD mice. In contrast, HFD feeding for 8 weeks, the levels of hepatic GSH decreased significantly in both HFD and KOHFD mice, and the decrease was greater in KOHFD mice than in HFD mice. 2. Compared with Control and KO group, the levels of liver TNFα and IL-6 in HFD group increased significantly. Moreover, the levels of liver TNF and IL-6 in KOHFD group were significantly higher than in HFD group. 3.The western-blot results showed that the expression of nuclear NF-kB were not significantly different in control and KO group. However, feeding HFD for 8 weeks significantly increased the protein expression of nuclear NF-kB in both HFD and KOHFD mice, and the increase was greater in KOHFD mice. Conclusion：Loss of Nrf2markedly aggravated oxidative stress in liver, subsequently leading to promote the activation of liver NF-kB in high fat diet fed mice.