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）是肝脏疾病的主要原因。但目前尚无 FDA 批准的 治疗 NASH 的药物，很大程度上是由于对 NASH 机制的不完全了解，特别是那些 参与 NASH 诱导的肝纤维化。 NASH 的一个关键特征是死亡肝细胞 (HC) 的积累， 特别是凋亡 HC (apHC) 和坏死性 HC (necHC)。在其他疾病中，死亡细胞的影响 很大程度上取决于它们的命运，即被巨噬细胞（Mφs）清除，但令人惊讶的是我们对 这在 NASH 中。该提案旨在解决这一根本性差距，从而对潜在的问题获得新的见解 可药物化和与人类相关的 NASH 机制，特别是那些涉及细胞串扰的机制。一个关键概念 是凋亡细胞（“胞吞作用”）与坏死性细胞的 Mφ 清除在机械方面是不同的 nisms 和后果，我已经表明 apHC 和 necHC 的 Mφ 清除率在人类中受到损害 和小鼠 NASH。基于广泛的初步数据，我的提案提出了有关 apHC 的具体假设 目标 1 (K99) 中的胞吞作用和目标 2 (R00) 中的 necHC 清除。在目标 1 中，我将检验以下假设： NASH Mφs 中的胞吞作用受体 TIM4 会导致 apHC 清除缺陷并导致 NASH pro- 侵略。我想问 NASH 小鼠中 Mφ-TIM4 的缺失是否会加速胞吞作用受损的进展 以及早期 NASH 中的肝纤维化。相反，我将使用诱导模型在 NASH 期间恢复 Mφ-TIM4。我 已经表明这可以恢复 apHC 胞吞作用，我将测试它会减少 HSC 激活的预测 和肝纤维化。接下来我将探索一种基于机制的治疗思路来恢复 NASH 中的 Mφ-TIM4，询问是否 该药物可以改善胞吞作用并抑制 NASH 进展。最后，我将进行 scRNA-seq 分析 Mφ-TIM4-恢复模型的肝脏，以探讨 apHC 胞吞作用导致 分泌 Mφ 分子，促进促解析 Mφ 表型并维持 HSC 处于静止状态。在 目标 2，我将研究 NASH 中的一条新途径，其中 CD47-SIRPα 轴的上调会损害 necHC 清除- 安斯。我认为 Mφ necHC 摄取会诱导 Mφs 分泌下调 HC-TAZ 的蛋白质，从而 抑制参与纤维化 NASH 的 TAZ-IHH-HSC 通路。我将在补充中寻找这个想法的证据 通过测试 HC-TAZ 沉默和 SIRPα 阻断相结合的效果来建立 NASH 模型。然后我将使用 Mφ- 特定的“分泌组”小鼠模型和蛋白质组学，以鉴定由 necHC 摄取诱导的 Mφ 蛋白 降低 HC-TAZ。最后，我将解决 2 个基本问题：（1）SIRPα 在 NASH Mφs 中如何上调？ (2) 在 CD47/SIRPα 轴阻断受体介导的情况下，necHC 的 Mφ 摄取是否是介导的？我的初步 这些领域的数据强调了两种 Mφ 蛋白在 NASH 中的新作用：TREM2 和 LRP1。通过这些 目标，我希望对 NASH 机制和治疗概念有新的见解。我的 K99 项目将允许 当我过渡到独立时，我将获得宝贵的基于知识和技术的指导以及职业建议 Pendence，R00 包含一个令人兴奋的研究项目，它将帮助我开启独立职业生涯。