Clearance of Dead Hepatocytes by Liver Macrophages in NASH

NASH 中肝脏巨噬细胞清除死亡肝细胞

• 批准号: 10723933
• 负责人: Hongxue Shi
• 金额: $ 9.15万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10723933
• 关键词: Acceleration; Address; Affect; Apoptotic; Area; CD47 gene; CD47-SIRPα; Cells; Data; Diabetes Mellitus; Disease; Disease Progression; Erinaceidae; Etiology; FDA approved; Failure; Fibrosis; Functional disorder; Hepatic Stellate Cell; Hepatocyte; Human; Immune; Impairment; Knockout Mice; Knowledge; Kupffer Cells; Liver; Liver Fibrosis; Liver diseases; Macrophage; Mediating; Mediator; Mentors; Modeling; Mus; Obesity Epidemic; PTPNS1 gene; Pathway interactions; Pharmaceutical Preparations; Phase; Phenotype; Process; Protein Secretion; Proteins; Proteomics; Publishing; Repression; Research; Resolution; Role; Structure; TREM2 gene; Testing; Text; Therapeutic; Tissues; Training; Up-Regulation; Work; career; chronic liver disease; design; improved; insight; knowledge base; mouse model; nonalcoholic steatohepatitis; novel; p38 Mitogen Activated Protein Kinase; programs; receptor; restoration; single-cell RNA sequencing; uptake

Non-alcoholic steatohepatitis (NASH) is a major cause of liver disease. However, there are no FDA-approved drugs to treat NASH, due in large part to an incomplete understanding of NASH mechanisms, particularly those involved in NASH-induced liver fibrosis. A key feature of NASH is the accumulation of dead hepatocytes (HCs), particularly apoptotic HCs (apHCs) and necroptotic HCs (necHCs). In other diseases, the impact of dead cells is largely determined by their fate, i.e., clearance by macrophages (Mφs), but surprisingly little is known about this in NASH. This proposal aims to address this fundamental gap and thereby gain new insights into potentially druggable and human-relevant NASH mechanisms, particularly those involving cellular cross-talk. A key concept is that the Mφ clearance of apoptotic cells ("efferocytosis") vs. necroptotic cells are distinct in terms of mecha- nisms and consequences, and I have shown the Mφ clearance of both apHC and necHCs is impaired in human and mouse NASH. Based on extensive preliminary data, my proposal addresses specific hypotheses on apHC efferocytosis in Aim 1 (K99) and necHC clearance in Aim 2 (R00). In Aim 1, I will test the hypothesis that loss of the efferocytosis receptor TIM4 in NASH Mφs causes defective apHC clearance and contributes to NASH pro- gression. I will ask if deletion of Mφ-TIM4 in NASH mice accelerates the progression to impaired efferocytosis and liver fibrosis in early NASH. Conversely, I will use an inducible model to restore Mφ-TIM4 during NASH. I have shown this restores apHC efferocytosis, and I will test the prediction that it will decrease HSC activation and liver fibrosis. I will next explore a mechanism-based therapeutic idea to restore Mφ-TIM4 in NASH, asking if this drug can improve efferocytosis and dampen NASH progression. Finally, I will conduct scRNA-seq analyses of the livers of the Mφ-TIM4-restoration model to probe the hypothesis that apHC efferocytosis leads to the secretion Mφ molecules that promote a pro-resolving Mφ phenotype and maintain HSCs in a quiescent state. In Aim 2, I will study a new pathway in NASH in which upregulation of the CD47-SIRPα axis impairs necHC clear- ance. I propose that Mφ necHC uptake induces Mφs to secrete protein(s) that down-regulate HC-TAZ, thereby suppressing the TAZ-IHH-HSC pathway involved in fibrotic NASH. I will seek proof for this idea in complementary models of NASH by testing the effect of combining HC-TAZ-silencing and SIRPα blockade. I will then use a Mφ- specific "secretome" mouse model and proteomics to identify the Mφ protein(s) induced by necHC uptake that lower HC-TAZ. Finally, I will address 2 fundamental questions: (1) How is SIRPα up-regulated in NASH Mφs?; and (2) Is Mφ uptake of necHCs in the setting of CD47/SIRPα-axis blockade receptor-mediated? My preliminary data in these areas have highlighted new roles for two Mφ proteins in NASH, TREM2 and LRP1. Through these Aims, I hope to gain new insights into NASH mechanisms and therapeutic concepts. My K99 project will allow me to receive invaluable knowledge-based and technical mentoring and career advice as I transition to inde- pendence, and the R00 encompasses an exciting research program that will help launch my independent career.

非酒精性脂肪性肝炎（NASH）是肝病的主要原因。但是，没有FDA批准 治疗纳什的药物，很大程度上是由于对纳什机制的不完全了解，尤其是那些 参与NASH诱导的肝纤维化。纳什的一个关键特征是死去的肝细胞（HCS）的积累， 在其他疾病中，死细胞的影响 在很大程度上取决于他们的命运，即巨噬细胞的清除（mφs），但令人惊讶的是对 这在纳什。该建议旨在解决这一基本差距，从而获得新的见解 可吸毒和与人与人相关的纳什机制，尤其是涉及细胞串扰的机制。一个关键概念 是凋亡细胞的Mφ清除率（“吞噬作用”）与坏死细胞的MECHA-与死灵细胞的清除率不同。 nism和后果，我已经显示了人类APHC和NECHC的Mφ清除率。 和鼠标纳什。基于广泛的初步数据，我的提案解决了有关APHC的特定假设 AIM 1（K99）和AIM 2（R00）中的NECHC清除中的肿瘤细胞增多症。在AIM 1中，我将检验以下假设 NASHMφS中的胚细胞增多症受体TIM4导致APHC清除率有缺陷，并有助于NASH Pro- 我会询问纳什小鼠中Mφ-TIM4是否会加速进展，从 和早期纳什的肝纤维化。相反，我将使用诱导模型在NASH期间恢复Mφ-TIM4。我 已经显示这恢复了APHC的肿瘤病，我将测试它将减少HSC激活的预测 和肝纤维化。接下来，我将探索基于机制的理论思想，以恢复NASH中的Mφ-TIM4，询问是否是否 这种药物可以改善鼻塞性和该死的纳什进展。最后，我将进行SCRNA-SEQ分析 Mφ-TIM4恢复模型的生命，以探测APHC肿瘤病导致的假设 分泌的Mφ分子，促进了促进的Mφ表型并将HSC保持在静止状态。在 AIM 2，我将研究NASH的新途径，其中CD47-SIRPα轴的上调会损害NECHC CLEAR- 恩斯。我建议MφNECHC摄取诱导MφS向秘密蛋白质，从而下调HC-TAZ，从而 抑制与纤维化NASH有关的TAZ-IHH-HSC途径。我将在完善中寻求这个想法的证据 NASH模型通过测试将HC-TAZ-SiLencing和SIRPα阻断结合的效果。然后，我将使用mφ- 特定的“分泌”小鼠模型和蛋白质组学，以识别由NECHC摄取诱导的Mφ蛋白 下HC-TAZ。最后，我将解决2个基本问题：（1）在NASHMφS中如何上调SIRPα？ （2）在CD47/SIRPα轴阻滞受体介导的情况下，NECHC是否吸收了NECHC？我的初步 这些领域的数据突出了NASH，TREM2和LRP1中两个Mφ蛋白的新作用。通过这些 目的，我希望能对NASH机制和治疗概念获得新的见解。我的K99项目将允许 在我过渡到inde时，我要获得宝贵的基于知识和技术的心理和职业建议 Pendence和R00涵盖了一项令人兴奋的研究计划，这将有助于启动我的独立职业。