Longitudinal Study of Early NAFLD Progression and the Gut Microbiome in Asian Americans, Native Hawaiians and Whites

项目总结 非酒精性脂肪性肝病(NAFLD)影响着美国35%的老年人。它现在是主要的病原学 这是慢性肝病和肝癌的致病原因，也是这些致命性疾病近期上升趋势的驱动因素。一个 肠道微生物群失调与NAFLD有关，但大多发生在小规模、横断面或临床- 基础研究。需要以人群为基础的纵向研究来为时间上的 肠道微生物群与非酒精性脂肪肝进展的关系在横截面的多民族队列中 (MEC)脂肪表型研究(APS；P01 CA168530)，我们发现肠道微生物有显著差异 NAFLD状态的组成和推断的微生物功能，包括富集梭杆菌和 内毒素产生菌与胆汁酸和简单碳水化合物代谢微生物途径的改变 在NAFLD。我们现在假设特定的肠道细菌特征(属、代谢途径和血液 内毒素生物标志物脂多糖结合蛋白(LBP)与肝脏脂肪和肝脏的增加有关 随着时间的推移会导致纤维化。我们还假设有几个饮食因素与NAFLD的进展有关 而这种促进纤维化的肠道细菌特征介导了这些联系。我们提出了一个纵向的 通过在300名MEC-APS参与者中有效地增加~10年的跟踪评估进行调查， 基线年龄60-77岁，三个种族/民族(日裔美国人、夏威夷原住民或 白色)，覆盖了大范围的基线肝脏脂肪。我们将使用MRI重新评估肝脏脂肪，并测量肝脏 硬度使用磁共振弹性成像，非侵入性量化肝脏脂肪和肝脏的金标准方法 并进行16S rRNA基因测序(随访粪便样本)和后基因组学 测序(基线和后续粪便样本)。具体目标是：1)评估特定肠道的变化 细菌特性(属的丰度、代谢途径和LBP)随时间的变化与 肝脏脂肪；2)评估肠道细菌特征随时间的变化与(2a)随访时肝脏僵硬的关系 和(2b)肝纤维化血液生物标志物小组的变化(增强肝纤维化(ELF)评分)，以及(2c) 使用ddPCR验证与肝脏僵硬相关的前两个细菌特征；以及3)评估 饮食(总体饮食质量的3个饮食模式得分和7个关键成分)与基于ELF的关系 肝纤维化的变化及目标2促纤维化肠道细菌特性的探讨 按肝脏脂肪水平分层。我们的结果将确定与早期非酒精性脂肪肝相关的肠道微生物特征 进步，同时具体解决研究不足的亚裔美国人和夏威夷原住民的需求 (非HL-23-001)，两个非酒精性脂肪肝和肝癌的高危人群。建议的优势 纵向设计、严格的成像和实验室方法将有助于理解NAFLD的进展 牵涉到肠道微生物群。这些发现可以用来为新的有针对性的干预策略提供信息 预防非酒精性脂肪肝的进展，并最终减轻多种族/民族人群中的肝癌负担。

PROJECT SUMMARY Non-alcoholic fatty liver disease (NAFLD) affects >35% of older adults in the US. It is now the primary etiology of chronic liver disease and liver cancer, and the driver of the recent upward trend in these lethal diseases. A dysbiotic gut microbiome has been associated with NAFLD, but mostly in small-scale, cross-sectional or clinic- based studies. Population-based longitudinal studies are needed to provide evidence for the temporal relationship of the gut microbiome with the progression of NAFLD. In the cross-sectional Multiethnic Cohort (MEC) Adiposity Phenotype Study (APS; P01 CA168530), we showed a significant difference in gut microbial composition and inferred microbial function by NAFLD status, including enrichment of Fusobacterium and endotoxin-producing bacteria and altered microbial pathways for bile acid and simple carbohydrate metabolism in NAFLD. We now hypothesize that specific gut bacterial features (genera, metabolic pathways and blood endotoxin biomarker lipopolysaccharide binding protein (LBP)) are associated with increase in liver fat and liver fibrosis over time. We also hypothesize that several dietary factors are associated with NAFLD progression and that fibrosis-promoting gut bacterial features mediate these associations. We propose a longitudinal investigation by efficiently adding a ~10-year follow-up assessment among 300 of the MEC-APS participants, aged 60-77 years at baseline and of three racial/ethnic groups (Japanese American, Native Hawaiian or White), across a wide range of baseline liver fat. We will re-assess liver fat using MRI and measure liver stiffness using MR elastography, gold-standard methods for non-invasive quantification of liver fat and liver stiffness, respectively, and perform 16S rRNA gene sequencing (follow-up stool samples) and metagenomic sequencing (baseline and follow-up stool samples). Specific Aims are to: 1) evaluate the change in specific gut bacterial features (abundance of genera, metabolic pathways, and LBP) over time in relation to the change in liver fat; 2) evaluate the change in gut bacterial features over time in relation to (2a) liver stiffness at follow-up and (2b) change in a blood biomarker panel for liver fibrosis (Enhanced Liver Fibrosis (ELF) score), and (2c) validate the top two bacterial features associated with liver stiffness using ddPCR; and 3) assess the association of diet (3 dietary pattern scores for overall diet quality and 7 key components) with ELF-based change in liver fibrosis and explore the mediation by fibrosis-promoting gut bacterial features from Aim 2, stratified by liver fat level. Our results will identify gut microbial features associated with early NAFLD progression, while specifically addressing the needs of understudied Asian Americans and Native Hawaiians (NOT-HL-23-001), two high-risk populations for NAFLD and liver cancer. The strengths of the proposed longitudinal design and rigorous imaging and laboratory methods will aid in understanding NAFLD progression involving the gut microbiome. These findings may be used to inform novel targeted intervention strategies to prevent NAFLD progression and, ultimately, reduce liver cancer burden in multiple racial/ethnic populations.