Rao Anuradha, van de Peppel Ivo P, Gumber Sanjeev, Karpen Saul J, Dawson Paul A
Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States.
Section of Molecular Metabolism and Nutrition, Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.
Front Med (Lausanne). 2020 Feb 25;7:60. doi: 10.3389/fmed.2020.00060. eCollection 2020.
Non-alcoholic fatty liver disease (NAFLD) is a major growing worldwide health problem. We previously reported that interruption of the enterohepatic circulation of bile acids using a non-absorbable apical sodium-dependent bile acid transporter inhibitor (ASBTi; SC-435) reduced the development of NAFLD in high fat diet fed mice. However, the ability of ASBTi treatment to impact the progression of NAFLD to non-alcoholic steatohepatitis (NASH) and fibrosis in a diet-induced mouse model remains untested. In the current study, we assessed whether ASBTi treatment is hepatoprotective in the choline-deficient, L-amino acid-defined (CDAA) diet model of NASH-induced fibrosis. Male C57Bl/6 mice were fed with: (A) choline-sufficient L-amino acid-defined diet (CSAA) (31 kcal% fat), (B) CSAA diet plus ASBTi (SC-435; 60 ppm), (C) CDAA diet, or (D) CDAA diet plus ASBTi. Body weight and food intake were monitored. After 22 weeks on diet, liver histology, cholesterol and triglyceride levels, and gene expression were measured. Fecal bile acid and fat excretion were measured, and intestinal fat absorption was determined using the sucrose polybehenate method. ASBTi treatment reduced bodyweight gain in mice fed either the CSAA or CDAA diet, and prevented the increase in liver to body weight ratio observed in CDAA-fed mice. ASBTi significantly reduced hepatic total cholesterol levels in both CSAA and CDAA-fed mice. ASBTi-associated significant reductions in hepatic triglyceride levels and histological scoring for NAFLD activity were observed in CSAA but not CDAA-fed mice. These changes correlated with measurements of intestinal fat absorption, which was significantly reduced in ASBTi-treated mice fed the CSAA (85 vs. 94%, < 0.001) but not CDAA diet (93 vs. 93%). As scored by Ishak staging of Sirius red stained liver sections, no hepatic fibrosis was evident in the CSAA diet mice. The CDAA diet-fed mice developed hepatic fibrosis, which was increased by the ASBTi. ASBT inhibition reduced intestinal fat absorption, bodyweight gain and hepatic steatosis in CSAA diet-fed mice. The effects of the ASBTi on steatosis and fat absorption were attenuated in the context of dietary choline-deficiency. Inhibition of intestinal absorption of fatty acids may be involved in the therapeutic effects of ASBTi treatment.
非酒精性脂肪性肝病（NAFLD）是一个在全球范围内日益严重的主要健康问题。我们之前报道过，使用一种不可吸收的顶端钠依赖性胆汁酸转运体抑制剂（ASBTi；SC-435）中断胆汁酸的肠肝循环可减少高脂饮食喂养小鼠中NAFLD的发展。然而，在饮食诱导的小鼠模型中，ASBTi治疗对NAFLD进展为非酒精性脂肪性肝炎（NASH）和肝纤维化的影响仍未得到测试。在当前研究中，我们评估了在胆碱缺乏、L-氨基酸限定（CDAA）饮食诱导的肝纤维化模型中，ASBTi治疗是否具有肝脏保护作用。雄性C57Bl/6小鼠被喂食：（A）胆碱充足的L-氨基酸限定饮食（CSAA）（31千卡%脂肪），（B）CSAA饮食加ASBTi（SC-435；60 ppm），（C）CDAA饮食，或（D）CDAA饮食加ASBTi。监测体重和食物摄入量。饮食22周后，测量肝脏组织学、胆固醇和甘油三酯水平以及基因表达。测量粪便胆汁酸和脂肪排泄，并使用蔗糖聚山嵛酸酯法测定肠道脂肪吸收。ASBTi治疗降低了喂食CSAA或CDAA饮食小鼠的体重增加，并防止了CDAA喂养小鼠肝脏与体重比的增加。ASBTi显著降低了CSAA和CDAA喂养小鼠的肝脏总胆固醇水平。在CSAA喂养但非CDAA喂养的小鼠中观察到ASBTi相关的肝脏甘油三酯水平显著降低以及NAFLD活动的组织学评分降低。这些变化与肠道脂肪吸收的测量结果相关，在喂食CSAA的ASBTi治疗小鼠中肠道脂肪吸收显著降低（85%对94%，<0.001），但在喂食CDAA饮食的小鼠中未降低（93%对93%）。根据天狼星红染色肝脏切片的Ishak分期评分，CSAA饮食小鼠中未发现明显的肝纤维化。CDAA饮食喂养的小鼠出现了肝纤维化，而ASBTi使其加重。ASBT抑制降低了CSAA饮食喂养小鼠的肠道脂肪吸收、体重增加和肝脏脂肪变性。在饮食胆碱缺乏的情况下，ASBTi对脂肪变性和脂肪吸收的影响减弱。脂肪酸肠道吸收的抑制可能参与了ASBTi治疗的治疗效果。
