Molecular mechanism of Sickle Cell Hepatic Crisis

镰状细胞性肝危象的分子机制

• 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
• 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

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.

项目总结/摘要 这个建议的目的是扩大我的培训作为一个独立的科学家在该领域的肝脏表现 镰状细胞病（SCD）为此，我选择了血液肿瘤科在大学 匹兹堡继续我的过渡，成为一个学术机构的独立调查员。这 该提案概述了一项广泛的研究战略，并辅之以几个培训领域， 包括几门与我的具体目标研究直接相关的课程， 委员会，并出席和参与多个研讨会在匹兹堡大学 医学院我的研究策略将确定SCD诱导肝危象的分子机制。 SCD是一种常染色体隐性单基因疾病，影响大约10万美国人和数百万人。 世界各地的人们。窦状隙血管闭塞和溶血被认为是镰状的主要原因 肝危象肝危象影响10-40%的住院SCD患者，其特征在于肝损伤 和镰状细胞肝内胆汁淤积症（SCIC），其可发展为致命的肝衰竭。目前治疗 肝危象主要是支持性的，分子机制尚不清楚，这表明预防性 需要基于对能够实现SCIC的分子途径的改进理解的疗法。 在这项研究中，我们使用了一种转基因的，人源化的SCD小鼠模型， 人血红蛋白。初步研究结果显示，SCD小鼠随着年龄的增长而发生慢性肝损伤， 表现为持续炎症、高胆红素血症和胆汁淤积。利用我们最近开发的 通过对活体小鼠的完整肝脏进行实时体内成像，我们发现存在肝窦缺血， SCD小鼠肝细胞顶膜胆汁转运受损。受损的胆汁转运 与肝细胞顶端胆汁转运蛋白（BSEP、ABCG 5和ABCG 8）的丢失相关。RNA-seq 一项分析发现，编码负责炎症和胆汁分泌的蛋白质的基因失调， SCD小鼠的肝脏。此外，我们观察到SCD小鼠肝脏中NF-κB活化抑制FXR 信号及其下游靶点，导致胆汁分泌受损。这些发现构成了我 缺血和溶血诱导炎症、组织损伤和氧化应激的总体假设 促进镰状肝细胞中的NF-κ B活化，抑制FXR信号传导，导致胆汁分泌受损 激活FXR或拯救胆汁分泌可改善SCIC。这一假设将在 目的：1）研究缺血再灌注损伤和溶血是否促进肝细胞特异性 SCD中NF-κ B的活化和2）确定NF-κ B的肝细胞特异性活化是否促进损失 FXR信号传导导致SCD中胆汁分泌受损和胆汁淤积。成功完成本 NIH-K 01培训奖将为RO 1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SCIC和SCD中的进行性肝损伤。