Hepatotoxic effects of perfluoroalkyl substances: a new epidemiological approach for studying environmental fatty liver disease

摘要 非酒精性脂肪性肝病(NAFLD)在儿童中的患病率在过去20年中几乎增加了两倍。 NAFLD目前影响着美国8%-12%的普通儿科人口和超过30%的肥胖者 孩子们。它与发展为晚期肝病的风险增加以及 心血管和代谢性疾病。越来越多的证据表明，早期生命环境的暴露 对NAFLD的病因学有贡献。全氟辛烷磺酸是广泛用于防水纺织品的持久性化合物， 不粘涂料和食品包装产品，在人体内有很长的半衰期(长达十年)。几乎所有的 美国儿童和青少年的血液中可检测到全氟辛烷磺酸的水平。即使是低剂量的PFAS暴露也会导致 动物模型的肝毒性作用。尽管实验研究提供了大量证据，但流行病学研究 仅限于对成人进行的几项横断面研究。因此，我们提出了一种新的研究设计 全氟辛烷磺酸对人体的肝脏毒性作用。我们将利用Teen的临床和肝脏组织病理学数据- 减肥手术纵向评估(青少年实验室)研究，这是最大的国家多中心 对青少年进行减肥手术的纵向、前瞻性研究，并提供了独特的肝脏档案 组织和血液样本。我们假设较高的PFAS浓度将与NAFLD和 手术时的非酒精性脂肪性肝炎(NASH，更严重的NAFLD)；此外， 减肥手术“自然实验”后的代谢变化将放大PFAS的效果 暴露，导致术后肝脏损伤的改善减弱。为了检验这一假设，我们将使用 手术时收集的存档样本以测量血浆和肝脏中的PFAS浓度 评估手术时肝组织病理学与肝损伤的改善之间的关系 跟进(目标1和2)。然后，我们将根据高分辨率确定受PFAS暴露改变的途径 肝组织和血浆样本的代谢组学概况，使用分层建模方法(目标3)。 最后，我们将使用一种新的潜变量模型来整合来自PFAS-组学分析的结果 框架，以确定减肥手术后肝脏损伤改善较少的青少年亚组， 根据他们的全氟辛烷磺酸暴露和代谢组学概况(目标4)。这项拟议中的研究将是第一个人类 以疾病肝活检为金标准检测PFAS暴露对NAFLD影响的研究 用于检测生物机制关联的诊断和肝脏特异性及血浆代谢组学方法 暴露在疾病中。一支强大的跨学科调查团队带来了环境方面的专业知识 流行病学、儿科肝病、减肥外科、代谢组学和生物统计学。学习、利用 现有的数据和生物样本来自一个表型良好的青少年减肥手术临床队列，是一个 创新、经济高效的方法来促进我们对环境对儿童肝脏的贡献的理解 疾病可能确定新的预防和干预目标，从生命早期开始。

ABSTRACT The prevalence of non-alcoholic fatty liver disease (NAFLD) in children has almost tripled over the past 20 years. NAFLD currently affects 8-12% of the general pediatric population in the U.S. and more that 30% of obese children. It is associated with an increased risk of developing advance stages of liver disease as well as cardiovascular and metabolic diseases. Mounting evidence suggests that early life environmental exposures contribute to the etiology of NAFLD. PFAS are persistent compounds widely used in water repellant textiles, nonstick coatings, and food packaging products, and have long half-lives (up to a decade) in humans. Almost all U.S. children and adolescents have detectable PFAS blood levels. Even low dose exposure to PFAS induces hepatotoxic effects in animal models. Despite abundant evidence from experimental studies, epidemiologic study is limited to a few cross-sectional studies in adults. We therefore propose a novel study design for investigating PFAS hepatotoxic effects in humans. We will leverage clinical and liver histopathological data from the Teen- Longitudinal Assessment of Bariatric Surgery (Teen-LABS) study, which is the largest national multi-center longitudinal, prospective study on teenagers undergoing bariatric surgery, and offers a unique archive of liver tissue and blood samples. We hypothesize that higher PFAS concentrations will be associated with NAFLD and non-alcoholic steatohepatitis (NASH, more severe NAFLD) at the time of surgery; furthermore, the large metabolic changes occurring after the bariatric surgery “natural experiment” will magnify effects of PFAS exposures, resulting in attenuated improvement in liver injury after surgery. To test this hypothesis, we will use archived samples collected at the time of surgery to measure PFAS concentrations in plasma and liver and assess associations with liver histopathology at the time of surgery and with improvement in liver injury during follow up (Aims1&2). We will then identify pathways altered by PFAS exposure based on high resolution metabolomics profiles in liver tissue and plasma samples, using a hierarchical modeling approach (Aim 3). Finally, we will integrate results from the PFAS-omics analyses, using a novel latent variable modeling framework, to identify subgroups of adolescents who have less improvement in liver injury after bariatric surgery, based on their PFAS exposure and metabolomics profiles (Aim 4). The proposed research will be the first human study to examine the effects of PFAS exposure on NAFLD using the gold standard of liver biopsies for disease diagnosis and liver-specific and plasma metabolomic measures for examining biological mechanisms linking exposure to disease. A strong interdisciplinary team of investigators brings expertise in environmental epidemiology, pediatric hepatology, bariatric surgery, metabolomics, and biostatistics. The study, utilizing existing data and biosamples from a well-phenotyped clinical adolescent bariatric surgery cohort, is an innovative, cost-effective approach to advance our understanding of environmental contributions to pediatric liver disease that may identify new targets for prevention and intervention starting early in life.