Department of Medicine II, Section Molecular Hepatology, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.
Miltenyi Biotec GmbH, Friedrich-Ebert-Straße 68, 51429, Bergisch Gladbach, Germany.
Cell Death Dis. 2018 Jan 19;9(2):51. doi: 10.1038/s41419-017-0071-y.
Alcohol abuse is a global health problem causing a substantial fraction of chronic liver diseases. Abundant TGF-β-a potent pro-fibrogenic cytokine-leads to disease progression. Our aim was to elucidate the crosstalk of TGF-β and alcohol on hepatocytes. Primary murine hepatocytes were challenged with ethanol and TGF-β and cell fate was determined. Fluidigm RNA analyses revealed transcriptional effects that regulate survival and apoptosis. Mechanistic insights were derived from enzyme/pathway inhibition experiments and modulation of oxidative stress levels. To substantiate findings, animal model specimens and human liver tissue cultures were investigated.
On its own, ethanol had no effect on hepatocyte apoptosis, whereas TGF-β increased cell death. Combined treatment led to massive hepatocyte apoptosis, which could also be recapitulated in human HCC liver tissue treated ex vivo. Alcohol boosted the TGF-β pro-apoptotic gene signature. The underlying mechanism of pathway crosstalk involves SMAD and non-SMAD/AKT signaling. Blunting CYP2E1 and ADH activities did not prevent this effect, implying that it was not a consequence of alcohol metabolism. In line with this, the ethanol metabolite acetaldehyde did not mimic the effect and glutathione supplementation did not prevent the super-induction of cell death. In contrast, blocking GSK-3β activity, a downstream mediator of AKT signaling, rescued the strong apoptotic response triggered by ethanol and TGF-β. This study provides novel information on the crosstalk between ethanol and TGF-β. We give evidence that ethanol directly leads to a boost of TGF-β's pro-apoptotic function in hepatocytes, which may have implications for patients with chronic alcoholic liver disease.
酗酒是一个全球性的健康问题，导致大量慢性肝病。大量的 TGF-β-一种有效的促纤维化细胞因子-导致疾病进展。我们的目的是阐明 TGF-β 和酒精对肝细胞的相互作用。原代鼠肝细胞用乙醇和 TGF-β 刺激，并确定细胞命运。Fluidigm RNA 分析显示了调节存活和凋亡的转录效应。从酶/途径抑制实验和氧化应激水平的调节中得出了机制见解。为了证实这些发现，研究了动物模型标本和人肝组织培养物。
单独的乙醇对肝细胞凋亡没有影响，而 TGF-β 则增加了细胞死亡。联合治疗导致大量肝细胞凋亡，这在体外处理的人 HCC 肝组织中也可以重现。酒精增强了 TGF-β 的促凋亡基因特征。途径相互作用的潜在机制涉及 SMAD 和非 SMAD/AKT 信号。抑制 CYP2E1 和 ADH 活性并不能阻止这种效应，这表明这不是酒精代谢的结果。与此一致的是，乙醇代谢物乙醛不能模拟这种效应，谷胱甘肽补充也不能防止细胞死亡的超强诱导。相反，阻断 AKT 信号下游介质 GSK-3β 的活性可以挽救乙醇和 TGF-β 引发的强烈凋亡反应。这项研究提供了关于乙醇和 TGF-β 相互作用的新信息。我们提供的证据表明，乙醇直接导致 TGF-β 在肝细胞中促凋亡功能的增强，这可能对慢性酒精性肝病患者有影响。
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