Regulation of Hepatobiliary Bile Acid Homeostasis in Neonatal Obstructive Cholestasis

新生儿梗阻性胆汁淤积肝胆胆汁酸稳态的调节

基本信息

批准号：
10283551
负责人：
Gregory Guthrie
金额：
$ 15.44万
依托单位：
BAYLOR COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-07-15 至 2026-04-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10283551
关键词：
Affinity Agonist Bile Acid Biosynthesis Pathway Bile Acids Bile fluid Biliary Atresia Binding Birth Blood CYP7A1 gene Cells Child Nutrition Childhood Cholestasis Cholesterol 7-alpha-Monooxygenase Clinical Conflict (Psychology)Digestive System Disorders Disease Doctor of Philosophy Dose Enteral Environment Enzymes Extrahepatic Bile Ducts FGF19 gene FGFR4 gene Faculty Family suidae Feedback Fibroblast Growth Factor Receptors Financial compensation Future Gene Expression Profile Goals Growth Hepatic Hepatobiliary Hepatocyte Homeostasis Hormones Human Impairment Infant Inflammation Infusion procedures Injury Intestines Knowledge Life Ligation Liver Liver diseases Mass Spectrum Analysis Mediating Medicine Mentorship Mitochondria Modeling Molecular Molecular Target National Institute of Diabetes and Digestive and Kidney Diseases Neonatal Nuclear Hormone Receptors Nutritional Study Organoids Oxidative Stress Pathology Pathway interactions Pharmacologic Substance Physiological Population Procedures Proteins Receptor Activation Receptor Cell Receptor Signaling Regulation Reporting Research Research Personnel Serum Signal Pathway Signal Transduction Site Source Testing Therapeutic Intervention Time Training Visualization analysis pipeline bile duct career career development cell type cholangiocyte cholestatic injury clinically relevant college fexaramine hepatocellular injury ileum kinetic model laser capture microdissection liver injury liver transplantation neonate porcine model receptor sham surgery skills stable isotope success transcriptome sequencing transcriptomics translational model

项目摘要

PROJECT SUMMARY Biliary atresia (BA) results in severe disruption of bile acid homeostasis and is the predominant disease causing neonatal obstructive cholestasis. Bile acid homeostasis in regulated by the nuclear hormone receptor Farnesoid X Receptor (FXR) by activation of the intestinal and hepatic hormone, fibroblast growth factor 19 (FGF19). FGF19 suppresses bile acid synthesis of hepatic cytochrome P450 7a1 (Cyp7a1), the key enzyme for classical bile acid synthesis. In healthy infants, the FGF19 expression is mainly in the intestine and low in the liver. In contrast, hepatic FGF19 is elevated in BA infants to compensate for loss of intestinal bile acid-induced FGF19 secretion. The increase in hepatic FGF19 and bile acid accumulation in BA infants suggests an uncoupling of FGF19 signaling that normally suppresses hepatic Cyp7a1 and bile acid synthesis. A secondary source of bile acid synthesis in hepatocytes and cholangiocytes is the alternative pathway via Cyp27a1. There is a gap in our knowledge of how the regulation of Cyp7a1 and Cyp27a1 via FXR-FGF19 signaling contributes to bile acid homeostasis during neonatal obstructive cholestasis. This proposal aims to understand the adaptive, time- dependent mechanism by which the liver compensates for altered intestinal bile acid signaling and how this compensation effects bile acid synthesis via the classical and alternative pathways. Our central hypothesis is that hepatic adaptation to obstructive cholestasis leads to increased hepatocyte FXR-FGF19 signaling, but with impaired suppression of Cyp7a1 or compensation by Cyp27a1 to sustain bile acid accumulation. In Aim 1a we will characterize the ontogeny of cholestatic liver injury, bile acid homeostasis, and cell-specific hepatocyte and cholangiocyte gene expression signatures in a newly developed neonatal pig model of bile duct ligation (BDL). In Aim 1b, we will quantify the molecular mechanisms of FXR and FGF19 signaling pathways involved in bile acid synthesis during long-term bile acid exposure using human cultured hepatocyte and cholangiocyte organoids. In Aim 2a, we will test whether FGF19 infusion dose-dependently suppresses Cyp7a1 expression at early and late time points after BDL. In Aim 2b, we will test if early activation of FXR-FGF19 signaling protects against BDL induced cholestasis. This study will provide understanding of the mechanism that regulate bile acid homeostasis in the context of neonatal obstructive cholestasis and test potential therapeutic interventions. Career development and environment: To enhance my potential for future success as an independent researcher I will receive mentorship from Dr. Douglas Burrin, PhD and training in use of stable isotope kinetics modeling, mass spectrometry analysis, RNA-seq pipeline analysis and visualization, and hepatic organoid culturing. This training will be conducted in an outstanding research environment of the Children’s Nutrition Research Center (CNRC) with support of NIDDK Digestive Disease Center technical cores and an expert faculty oversight committee at Baylor College of Medicine. This project will give me the scientific expertise and research skills to launch an independent research career in the field of pediatric liver diseases.

项目摘要胆道闭锁（BA）导致胆汁酸稳态严重中断，是导致疾病的主要疾病新生儿阻塞性胆汁淤积。胆汁酸稳态受到核马酮受体Farnesoid的调节 X受体（FXR）通过激活肠道和肝马酮，成纤维细胞生长因子19（FGF19）。 FGF19抑制肝酸合成肝细胞色素P450 7A1（CYP7A1），这是经典的关键酶胆汁酸合成。在健康的婴儿中，FGF19表达主要在肠道中，肝脏中的表达低。对比，BA婴儿中肝FGF19升高，以补偿肠道胆汁酸诱导的FGF19的损失分泌。 BA婴儿中肝FGF19和胆汁酸积累的增加表明， FGF19通常抑制肝CYP7A1和胆汁酸合成的信号传导。胆汁的次要来源肝细胞和胆管细胞中的酸合成是通过CYP27A1的替代途径。我们有差距了解CYP7A1和CYP27A1通过FXR-FGF19信号的调节如何有助于胆汁酸新生儿阻塞性胆汁淤积期间的稳态。该建议旨在了解适应性的时间 - 肝脏弥补肠胆汁酸信号改变的依赖机制，以及如何补偿通过经典和替代途径影响胆汁酸合成。我们的中心假设是对阻塞性胆汁淤积的肝适应导致肝细胞FXR-FGF19信号增加，但有 CYP7A1抑制或CYP27A1补偿以维持胆汁酸的积累而受损。在目标1a中将表征胆固性肝损伤，胆汁酸稳态和细胞特异性肝细胞的个体发育新开发的胆管结扎的新生儿猪模型（BDL）中的胆管细胞基因表达特征。在AIM 1B中，我们将量化FXR和FGF19信号通路的分子机制使用人培养的肝细胞和胆管细胞的长期胆汁酸暴露期间的酸合成器官。在AIM 2A中，我们将测试FGF19输注剂量是否依赖于抑制CYP7A1表达 BDL之后的早期和晚期点。在AIM 2B中，我们将测试FXR-FGF19信号的早期激活是否保护反对BDL诱导的胆汁淤积。这项研究将提供对调节胆汁酸的机制的理解在新生儿阻塞性胆汁淤积和测试潜在的治疗干预措施的背景下进行体内平衡。职业发展和环境：增强我作为独立的未来成功的潜力研究人员我将获得Douglas Burrin博士博士的指导和使用稳定同位素动力学的培训建模，质谱分析，RNA-Seq管道分析和可视化以及肝癌培养。该培训将在儿童营养的杰出研究环境中进行研究中心（CNRC）在NIDDK消化疾病中心技术核心和专业教师的支持下贝勒医学院的监督委员会。这个项目将为我提供科学专业知识和研究在小儿肝病领域开展独立研究职业的技能。