Department of Biological and Medical Sciences, Faculty of Pharmacy in Hradec Kralove, Charles University, 500 05 Hradec Kralove, Czech Republic.
Department of Biochemistry, Faculty of Medicine in Hradec Kralove, Charles University, 500 03 Hradec Kralove, Czech Republic.
Int J Mol Sci. 2020 Nov 27;21(23):9021. doi: 10.3390/ijms21239021.
Nonalcoholic steatohepatitis (NASH) is characterized by hepatic steatosis with inflammation and fibrosis. Membrane endoglin (Eng) expression is shown to participate in fibrosis, and plasma concentrations of soluble endoglin (sEng) are increased in patients with hypercholesterolemia and type 2 diabetes mellitus. We hypothesize that NASH increases both hepatic Eng expression and sEng in blood and that high levels of sEng modulate cholesterol and bile acid (BA) metabolism and affect NASH progression. Three-month-old transgenic male mice overexpressing human sEng and their wild type littermates are fed for six months with either a high-saturated fat, high-fructose high-cholesterol (FFC) diet or a chow diet. Evaluation of NASH, Liquid chromatography-mass spectrometry (LC/MS) analysis of BA, hepatic expression of Eng, inflammation, fibrosis markers, enzymes and transporters involved in hepatic cholesterol and BA metabolism are assessed using Real-Time Quantitative Reverse Transcription Polymerase Chain reaction (qRT-PCR) and Western blot. The FFC diet significantly increases mouse sEng levels and increases hepatic expression of Eng. High levels of human sEng results in increased hepatic deposition of cholesterol due to reduced conversion into BA, as well as redirects the metabolism of triglycerides (TAG) to its accumulation in the liver, via reduced TAG elimination by β-oxidation combined with reduced hepatic efflux. We propose that sEng might be a biomarker of NASH development, and the presence of high levels of sEng might support NASH aggravation by impairing the essential defensive mechanism protecting NASH liver against excessive TAG and cholesterol accumulation, suggesting the importance of high sEng levels in patients prone to develop NASH.
非酒精性脂肪性肝炎(NASH)的特征是肝脂肪变性伴炎症和纤维化。已有研究表明,膜内皮糖蛋白(Eng)的表达参与纤维化,并且高胆固醇血症和 2 型糖尿病患者的血浆可溶性内皮糖蛋白(sEng)浓度升高。我们假设 NASH 会增加肝脏中 Eng 的表达和血液中的 sEng,并且高水平的 sEng 会调节胆固醇和胆汁酸(BA)代谢,影响 NASH 的进展。我们用高饱和脂肪、高果糖、高胆固醇(FFC)饮食或标准饮食喂养 3 个月大的过表达人 sEng 的转基因雄性小鼠及其野生型同窝仔鼠 6 个月,评估 NASH、BA 的液相色谱-质谱(LC/MS)分析、Eng 的肝表达、炎症、纤维化标志物、参与胆固醇和 BA 代谢的肝脏酶和转运蛋白,使用实时定量逆转录聚合酶链反应(qRT-PCR)和 Western blot 进行评估。FFC 饮食显著增加了小鼠 sEng 水平,并增加了 Eng 的肝表达。高水平的人 sEng 导致胆固醇在肝脏中的沉积增加,这是由于转化为 BA 的减少,以及由于β-氧化的减少和肝内流出的减少,导致甘油三酯(TAG)的代谢被重定向到其在肝脏中的积累。我们提出 sEng 可能是 NASH 发展的生物标志物,高水平的 sEng 可能通过损害保护 NASH 肝脏免受过量 TAG 和胆固醇积累的必要防御机制来支持 NASH 的恶化,这表明在易发生 NASH 的患者中 sEng 水平的重要性。