Koletzko Leandra, Mahli Abdo, Hellerbrand Claus
Department of Medicine II, University Hospital, LMU Munich, Germany; Department of Internal Medicine I, University Hospital Regensburg, Germany.
Institute of Biochemistry, Emil-Fischer-Zentrum, Friedrich-Alexander-University Erlangen-Nürnberg, Germany.
Pathol Res Pract. 2018 Oct;214(10):1700-1706. doi: 10.1016/j.prp.2018.08.013. Epub 2018 Aug 19.
Hepatic steatosis is common in patients infected with hepatitis C virus (HCV). Particularly in patients infected with non-genotype 3 HCV, hepatic steatosis is closely related to factors of the metabolic syndrome such as hyperlipidemia. However, the molecular mechanisms involved in this "metabolic" steatosis in non-3 genotype HCV infections are not well understood. Here, we aimed to develop an in vitro model to study the effect of genotype 1 HCV infection on hepatic lipotoxicity and lipid metabolism. Cellular lipid accumulation was induced in Huh-7 hepatoma cells transfected with HCV genotype 1b replicon (HCV) by incubation with increasing doses of palmitic acid (C16:0) or oleic acid (C18:1 n-9) complexed to albumin mimicking hyperlipidemic conditions. Mock transfected hepatoma cells (HCV) were used as controls. Incubation with oleic acid concentrations as high as 0.5 mM did not induce toxic effects in HCV or HCV cells. In contrast, incubation with palmitic acid caused dose-dependently cytotoxic effects which were more pronounced in HCV compared to HCV cells. Further analysis with subtoxic palmitic and oleic acid concentrations revealed a higher uptake of fatty acids and intracellular triglyceride accumulation in HCV compared to HCV cells. Carnitine palmitoyltransferase I (CPT1) expression, indicative of mitochondrial beta-oxidation, was markedly stimulated by lipid exposure in HCV but not in HCV cells. Furthermore, heme oxygenase 1 (HMOX1) expression levels increased in FA stimulated cells, and this increase was significantly higher in HCV compared to HCV cells. In contrast, expression of the key enzymes of hepatic de novo lipogenesis fatty acid synthase (FASN) and stearoyl-CoA desaturase (SCD-1) was significantly reduced upon oleate exposure in HCV but not in HCV cells. In summary, our newly developed cell culture model revealed effects of HCV genotype 1b infection on metabolic susceptibility to lipid accumulation and toxicity particularly to saturated lipids. These results may indicate that HCV (genotype 1b) infected individuals with hyperlipidemia may benefit from dietary or pharmacological intervention.
肝脂肪变性在丙型肝炎病毒（HCV）感染患者中很常见。特别是在非3型HCV感染患者中，肝脂肪变性与代谢综合征因素如高脂血症密切相关。然而，非3型基因型HCV感染中这种“代谢性”脂肪变性所涉及的分子机制尚未完全清楚。在此，我们旨在建立一种体外模型，以研究1型HCV感染对肝脂毒性和脂质代谢的影响。通过与增加剂量的与白蛋白复合的棕榈酸（C16:0）或油酸（C18:1 n-9）孵育，模拟高脂血症条件，在转染了HCV 1b基因型复制子（HCV）的Huh-7肝癌细胞中诱导细胞脂质积累。mock转染的肝癌细胞（HCV）用作对照。用高达0.5 mM的油酸浓度孵育对HCV或HCV细胞未诱导毒性作用。相反，用棕榈酸孵育引起剂量依赖性细胞毒性作用，与HCV细胞相比，在HCV中更明显。用亚毒性棕榈酸和油酸浓度进行的进一步分析显示，与HCV细胞相比，HCV中脂肪酸摄取更高且细胞内甘油三酯积累更多。肉碱棕榈酰转移酶I（CPT1）的表达，指示线粒体β-氧化，在HCV中受脂质暴露明显刺激，但在HCV细胞中未受刺激。此外，血红素加氧酶1（HMOX1）表达水平在脂肪酸刺激的细胞中增加，并且与HCV细胞相比，在HCV中这种增加明显更高。相反，在HCV中，油酸暴露后肝脏从头脂肪生成关键酶脂肪酸合酶（FASN）和硬脂酰辅酶A去饱和酶（SCD-1）的表达显著降低，但在HCV细胞中未降低。总之，我们新开发的细胞培养模型揭示了HCV 1b基因型感染对脂质积累和毒性特别是对饱和脂质的代谢易感性的影响。这些结果可能表明，HCV（1b基因型）感染的高脂血症个体可能从饮食或药物干预中受益。
