Research Project 1 - Hepatocellular Genetic Epidemiology of Fatty Liver Disease in Hispanics

项目摘要 脂肪肝（FLD）是一个影响全球数百万人的主要公共卫生问题。两大 FLD的亚型包括酒精性FLD（AFLD）和非酒精性FLD（NAFLD）， 为分舱而征收土地是有争议的。FLD的定义是肝脏脂肪过多，并可能导致更严重的疾病 脂肪性肝炎（SH）的疾病状态，其中肝脏炎症/损伤可能反映在肝脏 纤维化SH可导致肝衰竭或肝细胞癌。使个人易患 FLD的发展包括生物学因素（肥胖、胰岛素抵抗、2型糖尿病）人口统计学 特性（例如，性别、年龄和种族），行为和生活方式相关的变量（例如，酒精摄入， 饮食行为和身体活动），以及其它环境因素（例如，传染性病原体，如肝炎 病毒、微生物组变异性、暴露于污染物/污染物/毒素）。西班牙裔受到严重影响 在世界上观察到的NAFLD患病率最高。 NAFLD的风险是由于遗传和环境因素及其相互作用的复杂混合物， 仍然大部分身份不明。定量内表型（即，生物标志物与基因相关， 疾病风险）具有重要的特性，可以加速发现疾病相关的遗传因果因素 并有助于个人水平的风险评估。在这里，我们提出了一种新的深层细胞表型评估， 诱导的多能干细胞（iPSC）衍生的肝细胞对实验性脂质过载攻击的应答， 模拟饮食中的脂质过量。这项实验性流行病学研究将使我们能够严格测试 基因型与环境的相互作用（GEI），以更好地了解NAFLD风险的病因/机制 并加强早期发现和阻止进展。具体来说，我们将鉴定新的iPSC衍生的 在墨西哥裔美国人中涉及NAFLD风险的肝细胞内表型，健康差异人群， 使用高通量多组学方法。这项研究将使用现有的数据和细胞生物样本，从900 参与我们的纵向墨西哥裔美国人家庭研究（MAFS），谁已经广泛的表型 （包括肝脏MRI）和遗传特征。我们的具体目标包括：1）发现新的肝细胞 通过定量全基因组RNA测序和功能评估确定NAFLD风险的细胞内表型 400名受试者中源自现有iPSC的肝细胞;（2）发现多变量肝细胞 使用单细胞测序的转录一致性内表型;和（3）确认最高的转录一致性内表型。 使用来自另外500名MAFS受试者的MRI衍生的肝脏脂肪测量对NAFLD内在表型进行排名 来自同一个家庭 非酒精性脂肪性肝病（NAFLD）是慢性肝病最常见的原因之一， 严重影响少数民族人口，西班牙裔是风险最高的人群之一。通过识别 基因决定的细胞内表型，我们希望能加快识别潜在的致病基因， 在NAFLD风险和用于识别NAFLD遗传风险的非侵入性早期生物标志物。

PROJECT SUMMARY Fatty liver disease (FLD) is a major public health issue that affects millions of people worldwide. The two major subtypes of FLD include alcoholic FLD (AFLD) and nonalcoholic FLD (NAFLD) although the threshold of alcohol intake for subdivision is controversial. FLD is defined by excess fat in the liver and can lead to a more profound disease state of steatohepatitis (SH) in which there is liver inflammation/damage that may be reflected in hepatic fibrosis. SH can lead to liver failure or hepatocellular carcinoma. Major risk factors predisposing individuals to the development of FLD include biological factors (obesity, insulin resistance, type 2 diabetes) demographic characteristics (e.g., sex, age and ethnicity), behavioral and lifestyle-related variables (e.g., alcohol intake, dietary behavior and physical activity), and other environmental factors (e.g., infectious agents such as hepatitis viruses, microbiome variability, exposure to pollutants/contaminants/toxins). Hispanics are disparately impacted by NAFLD with the highest observed prevalence of NAFLD in the world. Risk for NAFLD is due to a complex mixture of genetic and environmental factors and their interactions that are still largely unidentified. Quantitative endophenotypes (i.e., biomarkers that are genetically correlated with disease risk) have important properties that can speed the discovery of disease-related genetic causal factors and aid in individual-level risk estimation. Here we propose a novel deep cellular phenotyping assessment of induced pluripotent stem cell (iPSC)-derived hepatocyte response to experimental lipid overload challenge, which mimics dietary lipid overfeeding. This experimental epidemiological study will allow us to rigorously test for genotype-by-environment interactions (GEI) to better understand the etiology/mechanisms of NAFLD risk and to enhance early detection and halt progression. Specifically, we will identify novel iPSC-derived hepatocellular endophenotypes involved in NAFLD risk in Mexican Americans, a health disparity population, using a high-throughput multiomic approach. The study will use existing data and cellular biosamples from 900 participants in our longitudinal Mexican American Family Study (MAFS), who have been extensively phenotyped (including liver MRI) and genetically characterized. Our specific aims include: 1) discovery of novel hepatocellular cellular endophenotypes for NAFLD risk by quantitative genome-wide RNA sequencing and functional evaluation of hepatocytes derived from existing iPSCs in 400 subjects; (2) discovery of multivariate hepatocellular transcriptional coherence endophenotypes using single-cell sequencing; and (3) confirmation of the highest ranking NAFLD endophenotypes using MRI-derived liver fat measures from an additional 500 MAFS subjects from the same families. Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease and it disparately affects minority populations, with Hispanics being one of the highest at-risk populations. By identifying genetically determined cellular endophenotypes, we hope to speed the identification of potential causal genes in NAFLD risk and for identifying non-invasive early biomarkers of genetic risk for NAFLD.