Molecular mechanism of Sickle Cell Hepatic Crisis

镰状细胞性肝危象的分子机制

基本信息

批准号：
10614998
负责人：
Tirthadipa Pradhan-Sundd
金额：
$ 7.21万
依托单位：
UNIVERSITY OF PITTSBURGH AT PITTSBURGH
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-15 至 2023-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10614998
关键词：
Affect Age Agonist American Apical Area Award Bile Acids Bile fluid Biochemical Biochemistry Cholestasis Chronic Complement Experimental Models Future Genes Genetic Genetic Diseases Goals Hematology Hemoglobin Hemolysis Hemolysis Induction Hepatic Hepatobiliary Hepatocyte Hepatomegaly Hospitalization Human Hyperbilirubinemia Immunohistochemistry Impairment In Vitro Incidence Inflammation Inflammatory Injury Institution Intrahepatic Cholestasis Ischemia Liver Liver Failure Liver Fibrosis Liver diseases Longevity Mendelian disorder Mentors Mentorship Modeling Molecular Mus NF-kappa B Nuclear Receptors Oncology Outcome Oxidative Stress Pathway interactions Patients Persons Preventive therapy Proteins Reperfusion Injury Reporting Research Research Personnel Research Training Role Sampling Scientist Secondary to Serum Sickle Cell Sickle Cell Anemia Signal Pathway Signal Transduction Sterility Testing Therapeutic Time Tissues Toxic effect Training Transgenic Organisms United States National Institutes of Health Universities apical membrane autosome bile acid transporter career chronic liver injury faculty research human disease humanized mouse improved in vivo in vivo imaging liver biopsy liver injury medical schools meetings mouse model multi-photon novel prognostic recessive genetic trait sex sickling therapeutic target tissue injury transcriptome sequencing

项目摘要

Project Summary/Abstract The goal of this proposal is to extend my training as an independent scientist in the field of hepatic manifestations of Sickle cell disease (SCD). To this end, I have selected the division of Hematology-Oncology at University of Pittsburgh to continue my transition to become an independent investigator at an academic institution. This proposal outlines an extensive Research Strategy that is complemented by several areas of training, which includes several courses directly related to my studies in Specific Aims, meeting with my junior faculty research committee, and attendance and participation of multiple seminars throughout the University Of Pittsburgh Medical School. My Research Strategy will determine the molecular mechanisms of SCD induced hepatic crisis. SCD is an autosomal-recessive monogenic disorder that affects approximately 100,000 Americans and millions of people worldwide. Sinusoidal vaso-occlusion and hemolysis are considered as chief contributors of sickle hepatic crisis. Hepatic crisis affects 10-40% of hospitalized SCD patients which is characterized by liver injury and sickle cell intrahepatic cholestasis (SCIC) that can progress to fatal liver failure. The current treatment for hepatic crisis is primarily supportive, and the molecular mechanism is unknown, suggesting that preventive therapies based on the improved understanding of the molecular pathways that enable SCIC are needed. In this study, we have used a transgenic, humanized mouse model of SCD that exclusively expresses sickle human hemoglobin. Preliminary findings reveal that SCD mice developed chronic liver injury with age, which was manifested by sustained inflammation, hyperbilirubinemia and cholestasis. Using our recently developed real-time in vivo imaging of the intact liver of live mice, we discovered the presence of sinusoidal ischemia and impaired bile transport across the apical membrane of hepatocytes in SCD mice. The impaired bile transport was associated with loss of apical bile transporters (BSEP, ABCG5 and ABCG8) from hepatocytes. RNA-seq analysis identified dysregulation of genes encoding proteins responsible for inflammation and bile secretion in the liver of SCD mice. Furthermore, we observed NF-κB activation in the liver of SCD mice inhibited FXR signaling and its downstream targets, leading to impaired bile secretion. These findings form the basis for my overarching hypothesis that ischemia and hemolysis induced inflammation, tissue injury and oxidative stress promotes NF-kB activation in sickle hepatocytes which inhibits FXR signaling leading to impaired bile secretion in SCD, and activating FXR or rescuing bile secretion can ameliorate SCIC. This hypothesis will be tested in the following aims: 1) To determine whether ischemia-reperfusion injury and hemolysis promotes hepatocyte specific activation of NF-kB in SCD and 2) To determine whether hepatocyte-specific activation of NF-kB promotes loss of FXR-signaling leading to impaired bile secretion and cholestasis in SCD. The successful completion of this NIH-K01 training award will set the stage for an RO1 proposal aimed at elucidating how the manipulation of inflammatory pathways, FXR signalling and bile secretion can rescue SCIC and progressive liver injury in SCD.

项目概要/摘要该提案的目标是扩展我作为肝脏表现领域独立科学家的培训为此，我选择了镰状细胞病（SCD）的血液肿瘤科。匹兹堡继续我的过渡，成为学术机构的独立调查员。提案概述了一项广泛的研究战略，并辅以多个培训领域，其中包括与我在特定目标中的研究直接相关的几门课程，与我的初级教师研究会面委员会，以及出席和参与整个匹兹堡大学的多个研讨会医学院。我的研究策略将确定 SCD 诱发肝危象的分子机制。 SCD 是一种常染色体隐性单基因疾病，影响大约 100,000 名美国人和数百万人世界各地的人认为正弦血管闭塞和溶血是镰状细胞病的主要原因。肝危象影响 10-40% 的住院 SCD 患者，其特点是肝损伤。和镰状细胞性肝内胆汁淤积 (SCIC)，可发展为致命的肝功能衰竭。肝危象主要是支持性的，分子机制尚不清楚，提示预防性治疗需要基于对实现 SCIC 的分子途径的更好理解的治疗方法。在这项研究中，我们使用了一种转基因、人源化的 SCD 小鼠模型，该模型专门表达镰状细胞人类血红蛋白的初步研究结果表明，SCD 小鼠随着年龄的增长会出现慢性肝损伤。表现为持续炎症、高胆红素血症和胆汁淤积。对活体小鼠完整肝脏的实时体内成像，我们发现存在肝窦缺血和 SCD 小鼠肝细胞顶膜的胆汁运输受损。与肝细胞 RNA-seq 中顶端胆汁转运蛋白（BSEP、ABCG5 和 ABCG8）的丢失有关。分析发现编码负责炎症和胆汁分泌的蛋白质的基因失调此外，我们观察到 SCD 小鼠肝脏中 NF-κB 的激活抑制了 FXR。信号及其下游目标，导致回肠分泌受损。这些发现构成了我的基础。总体假设是缺血和溶血引起炎症、组织损伤和氧化应激促进镰状肝细胞中 NF-kB 的激活，抑制 FXR 信号传导，导致胆汁分泌受损在 SCD 中，激活 FXR 或挽救胆汁分泌可以改善 SCIC。这一假设将在 SCD 中得到检验。以下目的：1) 确定缺血再灌注损伤和溶血是否促进肝细胞特异性 SCD 中 NF-kB 的激活以及 2) 确定肝细胞特异性激活 NF-kB 是否会促进损失 FXR 信号传导导致 SCD 中胆汁分泌受损和胆汁淤积。 NIH-K01 培训奖将为 RO1 提案奠定基础，该提案旨在阐明如何操纵炎症通路、FXR 信号传导和胆汁分泌可以挽救 SCD 中的 SCIC 和进行性肝损伤。