目的:非酒精性脂肪性肝炎(NASH)与氧化应激有关。我们推测,使用炔属三环双(氰基烯酮)TBE-31的NF-E2p45相关因子2(Nrf2)的药理激活会抑制NASH,因为Nrf2是细胞内氧化还原稳态的转录主调节因子。
方法:Nrf2+/+和Nrf2-/-C57BL/6小鼠饲喂高脂肪加果糖(HFFr)或常规饮食16周或30周,然后治疗最后6周,虽然仍然喂相同的HFFr或常规饮食,与TBE-31或二甲基亚砜载体控制。全身葡萄糖稳态的测量,肝脏的组织学评估,以及脂肪变性的生化和分子测量,内质网(ER)应激,炎症,凋亡,纤维化,氧化应激在这些动物的肝脏中进行。
结果:TBE-31治疗逆转HFFr饲喂野生型小鼠的胰岛素抵抗,但不是在HFFr喂养的Nrf2-null小鼠中。TBE-31治疗HFFr喂养的野生型小鼠显著降低肝脏脂肪变性和脂质合成基因的表达,同时增加肝脏脂肪酸氧化和脂蛋白组装基因的表达。此外,TBE-31治疗减少内质网应激,炎症基因的表达,和细胞凋亡的标志物,纤维化,HFFr喂养的野生型小鼠肝脏中的氧化应激。相比之下,TBE-31不能减少脂肪变性,ER压力,脂肪生成,炎症,纤维化,或HFFr喂养的Nrf2-null小鼠肝脏中的氧化应激。
结论:Nrf2在已经出现肥胖和胰岛素抵抗的小鼠中的药理激活逆转了胰岛素抵抗,抑制肝脏脂肪变性,并缓解NASH和肝纤维化,我们主要归因于抑制ER的影响,炎症,和氧化应激。
OBJECTIVE: Nonalcoholic steatohepatitis (NASH) is associated with oxidative stress. We surmised that pharmacologic activation of NF-E2 p45-related factor 2 (Nrf2) using the acetylenic tricyclic bis(cyano enone) TBE-31 would suppress NASH because Nrf2 is a transcriptional master regulator of intracellular redox homeostasis.
METHODS: Nrf2+/+ and Nrf2-/- C57BL/6 mice were fed a high-fat plus fructose (HFFr) or regular chow diet for 16 weeks or 30 weeks, and then treated for the final 6 weeks, while still being fed the same HFFr or regular chow diets, with either TBE-31 or dimethyl sulfoxide vehicle control. Measures of whole-body glucose homeostasis, histologic assessment of liver, and biochemical and molecular measurements of steatosis, endoplasmic reticulum (ER) stress, inflammation, apoptosis, fibrosis, and oxidative stress were performed in livers from these animals.
RESULTS: TBE-31 treatment reversed insulin resistance in HFFr-fed wild-type mice, but not in HFFr-fed Nrf2-null mice. TBE-31 treatment of HFFr-fed wild-type mice substantially decreased liver steatosis and expression of lipid synthesis genes, while increasing hepatic expression of fatty acid oxidation and lipoprotein assembly genes. Also, TBE-31 treatment decreased ER stress, expression of inflammation genes, and markers of apoptosis, fibrosis, and oxidative stress in the livers of HFFr-fed wild-type mice. By comparison, TBE-31 did not decrease steatosis, ER stress, lipogenesis, inflammation, fibrosis, or oxidative stress in livers of HFFr-fed Nrf2-null mice.
CONCLUSIONS: Pharmacologic activation of Nrf2 in mice that had already been rendered obese and insulin resistant reversed insulin resistance, suppressed hepatic steatosis, and mitigated against NASH and liver fibrosis, effects that we principally attribute to inhibition of ER, inflammatory, and oxidative stress.