BACKGROUND Chronic alcohol consumption is a significant cause of liver disease worldwide. Several biochemical mechanisms have been linked to the initiation and progression of alcoholic liver disease (ALD) such as oxidative stress, inflammation, and metabolic dysregulation, including the disruption of NAD+/NADH. Indeed, an ethanol-mediated reduction in hepatic NAD+ levels is thought to be one factor underlying ethanol-induced steatosis, oxidative stress, steatohepatitis, insulin resistance, and inhibition of gluconeogenesis. Therefore, we applied a NAD+ boosting supplement to investigate alterations in the pathogenesis of early-stage ALD. METHODS To examine the impact of NAD+ therapy on the early stages of ALD, we utilized nicotinamide mononucleotide (NMN) at 500 mg/kg intraperitoneal injection every other day, for the duration of a Lieber-DeCarli 6-week chronic ethanol model in mice. Numerous strategies were employed to characterize the effect of NMN therapy, including the integration of RNA-seq, immunoblotting, and metabolomics analysis. RESULTS Our findings reveal that NMN therapy increased hepatic NAD+ levels, prevented an ethanol-induced increase in plasma ALT and AST, and changed the expression of 25% of the genes that were modulated by ethanol metabolism. These genes were associated with a number of pathways including the MAPK pathway. Interestingly, our analysis revealed that NMN treatment normalized Erk1/2 signaling and prevented an induction of Atf3 overexpression. CONCLUSIONS These findings reveal previously unreported mechanisms by which NMN supplementation alters hepatic gene expression and protein pathways to impact ethanol hepatotoxicity in an early-stage murine model of ALD. Overall, our data suggest further research is needed to fully characterize treatment paradigms and biochemical implications of NAD+-based interventions.

中文翻译：

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在酒精性肝病的慢性模型中研究烟酰胺单核苷酸疗法改变的RNA表达谱。

背景技术长期饮酒是全世界范围内肝脏疾病的重要原因。几种生化机制与酒精性肝病（ALD）的发生和发展有关，例如氧化应激，炎症和代谢失调，包括NAD + / NADH的破坏。实际上，乙醇介导的肝脏NAD +水平的降低被认为是乙醇诱导的脂肪变性，氧化应激，脂肪性肝炎，胰岛素抵抗和糖异生的抑制因素之一。因此，我们应用了NAD +强化补充剂来研究早期ALD发病机理的变化。方法为了检查NAD +治疗对ALD早期的影响，我们每隔一天腹膜内注射烟酰胺单核苷酸（NMN），剂量为500 mg / kg，小鼠的Lieber-DeCarli 6周慢性乙醇模型的持续时间。许多方法用于表征NMN治疗的效果，包括RNA序列，免疫印迹和代谢组学分析的整合。结果我们的发现表明，NMN治疗可提高肝脏NAD +水平，防止乙醇诱导的血浆ALT和AST升高，并改变了25％受乙醇代谢调节的基因的表达。这些基因与包括MAPK途径在内的许多途径相关。有趣的是，我们的分析显示NMN治疗可正常化Erk1 / 2信号传导并防止Atf3过表达的诱导。结论这些发现揭示了以前未报道的机制，通过补充NMN可以改变ALD早期小鼠模型中的肝基因表达和蛋白质途径，从而影响乙醇的肝毒性。总体而言，我们的数据表明需要进一步研究以充分表征基于NAD +的干预措施的治疗范式和生化意义。