Hepatic Transcriptome Profiling of A Multiethnic Cohort of Pediatric Non-Alcoholic Fatty Liver Disease Patients Reveals Novel Genes and Pathways Associated With Disease Stages

Non-alcoholic Fatty Liver Disease (NAFLD) is the most common type of chronic liver disease in children. The mechanisms that drive NAFLD disease progression in this specific patient population remains poorly defined. In this study, we gathered liver biopsy samples from a multiethnic cohort (71% Hispanic) of pediatric NAFLD patients (n=52, mean age=13.6 years) plus healthy liver controls (n=5). We analyzed transcriptomic changes associated with NAFLD disease progression using high-throughput RNA-sequencing. Unsupervised clustering as well as pairwise transcriptome comparison distinguished NAFLD from healthy livers. We identified perturbations in calcium and insulin/glucose signaling occurring early in NAFLD disease, prior to the presence of histopathologic evidence of advanced disease. Transcriptomic comparisons between low and advanced fibrosis identified a 25-gene signature associated with pediatric fibrotic liver progression. We also identified expression of the IGFBP gene family (1/2/3/7) as correlating with disease progression and it has the potential to be used as a peripheral biomarker in NAFLD. Comparing our dataset with publicly available adult transcriptomic data, we identified similarities and differences in pathway enrichment and gene expression profiles between adult and pediatric NAFLD patients. Regulation of genes including IL32, IGFBP1, IGFBP2, IGFBP7 was consistently found in both NAFLD populations, while IGFBP3 was specific to pediatric NAFLD. Conclusions: This paper expands our knowledge on the molecular mechanisms driving NAFLD and fibrosis in the pediatric population and aids future biomarker and therapeutics discovery. Overall design: In this study, we gathered liver biopsy samples from a multiethnic cohort (71% Hispanic) of pediatric NAFLD patients (n=52, mean age=13.6 years) plus healthy liver controls (n=5). We analyzed transcriptomic changes associated with NAFLD disease progression using high-throughput RNA-sequencing.

非酒精性脂肪性肝病（Non-alcoholic Fatty Liver Disease，NAFLD）是儿童群体中最为常见的慢性肝病类型。针对这一特定患者群体，驱动非酒精性脂肪性肝病进展的分子机制仍未被充分阐明。
本研究收集了多民族队列（71%为西班牙裔）的儿童非酒精性脂肪性肝病患者（n=52，平均年龄13.6岁）的肝活检样本，同时纳入5例健康肝脏对照样本。本研究采用高通量RNA测序技术，分析了与非酒精性脂肪性肝病进展相关的转录组变化。无监督聚类及成对转录组比较分析可将非酒精性脂肪性肝病肝脏与健康肝脏区分开来。研究团队发现，在组织病理学证实存在进展期疾病证据之前，非酒精性脂肪性肝病早期即出现钙信号通路与胰岛素/葡萄糖信号通路的紊乱。通过对轻度纤维化与进展期纤维化样本开展转录组比较，本研究鉴定出与儿童肝纤维化进展相关的25基因特征谱。本研究同时发现，胰岛素样生长因子结合蛋白（IGFBP）基因家族（1/2/3/7亚型）的表达水平与疾病进展相关，有望作为非酒精性脂肪性肝病的外周生物标志物。将本研究数据集与公开可用的成人转录组数据进行比对后，研究团队发现了成人与儿童非酒精性脂肪性肝病患者在通路富集及基因表达谱方面的异同之处。白细胞介素32（IL32）、IGFBP1、IGFBP2、IGFBP7等基因的表达调控在两类非酒精性脂肪性肝病群体中均存在一致性变化，而IGFBP3仅在儿童非酒精性脂肪性肝病中具有特异性。
结论：本研究拓展了我们对儿童群体中非酒精性脂肪性肝病及肝纤维化进展相关分子机制的认知，可为后续生物标志物与治疗靶点的开发提供助力。
研究设计概述：本研究收集了多民族队列（71%为西班牙裔）的儿童非酒精性脂肪性肝病患者（n=52，平均年龄13.6岁）的肝活检样本，同时纳入5例健康肝脏对照样本。本研究采用高通量RNA测序技术，分析了与非酒精性脂肪性肝病进展相关的转录组变化。