Uncovering a Predictive Molecular Signature for the Onset of NASH-Related Fibrosis in a Translational NASH Mouse Model

SUMMARY: This article presents a predictive molecular signature that marks the early onset of fibrosis in a translational nonalcoholic steatohepatitis mouse model. Overlap of genes and processes with human nonalcoholic steatohepatitis and a list of top candidate biomarkers for early fibrosis are described. BACKGROUND & AIMS: The incidence of nonalcoholic steatohepatitis (NASH) is increasing. The pathophysiological mechanisms of NASH and the sequence of events leading to hepatic fibrosis are incompletely understood. The aim of this study was to gain insight into the dynamics of key molecular processes involved in NASH and to rank early markers for hepatic fibrosis. METHODS: A time-course study in low-density lipoprotein–receptor knockout. Leiden mice on a high-fat diet was performed to identify the temporal dynamics of key processes contributing to NASH and fibrosis. An integrative systems biology approach was used to elucidate candidate markers linked to the active fibrosis process by combining transcriptomics, dynamic proteomics, and histopathology. The translational value of these findings were confirmed using human NASH data sets. RESULTS: High-fat-diet feeding resulted in obesity, hyperlipidemia, insulin resistance, and NASH with fibrosis in a time-dependent manner. Temporal dynamics of key molecular processes involved in the development of NASH were identified, including lipid metabolism, inflammation, oxidative stress, and fibrosis. A data-integrative approach enabled identification of the active fibrotic process preceding histopathologic detection using a novel molecular fibrosis signature. Human studies were used to identify overlap of genes and processes and to perform a network biology-based prioritization to rank top candidate markers representing the early manifestation of fibrosis. CONCLUSIONS: An early predictive molecular signature was identified that marked the active profibrotic process before histopathologic fibrosis becomes manifest. Early detection of the onset of NASH and fibrosis enables identification of novel blood-based biomarkers to stratify patients at risk, development of new therapeutics, and help shorten (pre)clinical experimental time frames. Keywords: Systems Biology; Metabolic Syndrome; Liver Disease; Diagnosis. In total 9 treatment groups: 5 Control groups (chow = standard diet; t=0, 6, 12, 18, 24 weeks), 4 Treatment groups (HFD = High Fat diet; 6, 12, 18, 24 weeks).

【摘要】本文报道了一种可标记转化性非酒精性脂肪性肝炎（nonalcoholic steatohepatitis, NASH）小鼠模型中纤维化早期发作的预测性分子特征。本文同时描述了与人类非酒精性脂肪性肝炎相关的基因、生物学过程的重叠特征，以及针对早期纤维化的顶级候选生物标志物排序结果。

【背景与目的】非酒精性脂肪性肝炎（NASH）的发病率正逐年攀升。目前学界对NASH的病理生理机制以及引发肝纤维化的事件序列尚未完全阐明。本研究旨在深入解析NASH发生进程中关键分子过程的动态变化，并对肝纤维化早期标志物开展优先级排序与筛选。

【方法】本研究针对高脂饲料喂养的莱顿低密度脂蛋白受体敲除小鼠开展时序实验，以明确参与NASH及纤维化发生的关键过程的时间动态特征。研究采用整合系统生物学策略，结合转录组学、动态蛋白质组学与组织病理学技术，阐明与活跃纤维化过程相关的候选标志物。本研究通过人类NASH数据集验证了上述发现的转化应用价值。

【结果】高脂饲料喂养可诱导小鼠出现时间依赖性的肥胖、高脂血症、胰岛素抵抗以及伴纤维化的NASH。研究明确了参与NASH发生发展的关键分子过程的时间动态变化，涵盖脂质代谢、炎症反应、氧化应激与纤维化进程。通过数据整合分析方法，本研究成功鉴定出一种新型分子纤维化特征，可在组织病理学检测到纤维化之前识别活跃的促纤维化进程。借助人类研究数据，本研究确认了相关基因与生物学过程的重叠情况，并通过基于网络生物学的优先级排序方法，筛选出代表纤维化早期表现的顶级候选标志物。

【结论】本研究鉴定出一种早期预测性分子特征，可在组织病理学纤维化显现之前标记活跃的促纤维化进程。早期检测NASH与纤维化的发作，有助于鉴定新型血液生物标志物以对高危患者进行风险分层，助力新型治疗药物的开发，并有望缩短（预）临床实验的周期。

关键词：系统生物学；代谢综合征；肝脏疾病；诊断

本研究共设9个处理组：5个对照组（普通饲料组，即标准饮食；时间点分别为t=0、6、12、18、24周），4个实验组（高脂饮食组，HFD；时间点分别为6、12、18、24周）。