From the, Institute of Hepatology, (EP, AR, RW, SC), Foundation for Liver Research, London, UK.
Faculty of Life Sciences and Medicine, (EP, AR, RW, SC), King's College London, London, UK.
Alcohol Clin Exp Res. 2020 Apr;44(4):856-865. doi: 10.1111/acer.14299. Epub 2020 Feb 25.
Mitochondria play a fundamental role in the pathogenesis of alcoholic liver disease (ALD). The preservation of functional mitochondria during toxic alcohol insults is essential for cell survival and is maintained by key processes known as mitochondrial dynamics, including fragmentation and fusion, which are regulated by mitochondria-shaping proteins (MSP). We have shown mitochondrial dynamics to be distorted by alcohol in cellular and animal models, but the effect in humans remains unknown.
Hepatic gene expression of the main MSP involved in the mitochondrial fusion and fragmentation pathways was evaluated in patients with alcoholic hepatitis (AH) by DNA microarray (n = 15) and Reverse Transcription Polymerase Chain Reaction (n = 32). The activation of dynamin-1-like protein (Drp1) was also investigated in mitochondria isolated from liver biopsies of ALD patients (n = 8). The effects of alcohol on mitochondrial dynamics and on MSP protein expression were studied in human precision-cut liver slices (PCLS) exposed for 24 hours to increasing doses of ethanol (EtOH; 50 to 250 mM).
A profound hyperactivation of the fragmentation pathway was observed in AH patients, with a significant increase in the expression of Drp1 and its adapters/receptors. The translocation of Drp1 to the mitochondria was also induced in patients with severe ALD and was affected in the PCLS with short-term exposure to EtOH but only mildly. The fusion pathway was not altered in ALD, and this was confirmed in the PCLS model.
The present study reveals the role of mitochondrial dynamics in human ALD, confirming our previous observations in animal and cell culture models of ALD. Taken together, we show that alcohol has a significant impact on the fragmentation pathway, and we confirm Drp1 as a potential therapeutic target in severe ALD.
线粒体在酒精性肝病 (ALD) 的发病机制中起着至关重要的作用。在有毒酒精刺激下，功能性线粒体的保存对于细胞存活至关重要，这是通过称为线粒体动力学的关键过程来维持的，包括分裂和融合，这些过程由线粒体成形蛋白 (MSP) 调节。我们已经在细胞和动物模型中证明了酒精对线粒体动力学的扭曲，但在人类中的影响仍不清楚。
通过 DNA 微阵列（n=15）和逆转录聚合酶链反应（n=32）评估酒精性肝炎 (AH) 患者肝脏中主要参与线粒体融合和分裂途径的 MSP 的基因表达。还研究了从 ALD 患者肝活检中分离的线粒体中分裂蛋白-1 样蛋白 (Drp1) 的激活情况（n=8）。通过将人精密切割肝切片（PCLS）暴露于 50 至 250mM 的乙醇（EtOH）中 24 小时来研究乙醇对线粒体动力学和 MSP 蛋白表达的影响。
在 AH 患者中观察到分裂途径的深刻超激活，Drp1 及其衔接子/受体的表达显著增加。在严重 ALD 患者中也诱导了 Drp1 向线粒体的易位，并且在 PCLS 中短期暴露于 EtOH 时受到影响，但仅轻度影响。ALD 中融合途径没有改变，这在 PCLS 模型中得到了证实。
本研究揭示了线粒体动力学在人类 ALD 中的作用，证实了我们之前在 ALD 的动物和细胞培养模型中的观察结果。总之，我们表明酒精对分裂途径有重大影响，并证实 Drp1 是严重 ALD 的潜在治疗靶点。
