Lipotoxicity and Liver Inflammation

脂毒性和肝脏炎症

• 批准号: 10337075
• 负责人: Samar Ibrahim
• 金额: $ 35.78万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-04-15 至 2024-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10337075
• 关键词: Adhesions; Adoptive Transfer; Affinity; Anti-Inflammatory Agents; Attenuated; Binding; Biochemical; Biogenesis; Biological; Biology; Cell Adhesion Inhibition; Cell Adhesion Molecules; Cell Communication; Cell model; Cell surface; Cells; Childhood; Choline; Cytoskeleton; Data; Development; Diet; Disease; Encapsulated; Endothelial Cells; Endothelium; Exposure to; Flow Cytometry; Functional disorder; GTPase-Activating Proteins; Goals; Hepatic; Hepatocyte; Home; Human; In Vitro; Infiltration; Inflammation; Inflammatory Response; Injury; Integrin Inhibition; Integrins; Isotope Labeling; Leukocytes; Ligands; Link; Lipids; Liver; Liver diseases; Mediating; Mediator of activation protein; Modeling; Molecular; Molecular Conformation; Molecular Profiling; Mus; Nonesterified Fatty Acids; Obesity; Pathogenesis; Pathway interactions; Pharmacology; Positron-Emission Tomography; Proteome; Public Health; Publishing; Research; Role; Scaffolding Protein; Signal Pathway; Signal Transduction; Sterility; Stress; Surface; Testing; Therapeutic Intervention; Vascular Cell Adhesion Molecule-1; base; experimental study; extracellular vesicles; hepatocyte injury; inhibitor; innovation; insight; liver inflammation; liver injury; macrophage; member; microfluidic technology; monocyte; mouse model; nanomedicine; nanoscale; non-alcoholic fatty liver disease; nonalcoholic steatohepatitis; novel; novel therapeutic intervention; p38 Mitogen Activated Protein Kinase; prevent; recruit; therapeutic target; trafficking; vesicular release

PROJECT SUMMARY Overall Objectives of this proposal are to define mechanisms linking hepatocyte injury during lipotoxicity with hepatic inflammation in nonalcoholic steatohepatitis (NASH). NASH is the most common pediatric liver disease characterized by abundant circulating saturated free fatty acids (SFAs), along with hepatocyte lipotoxicity and monocyte-derived macrophage mediated liver inflammation. Hepatocyte lipotoxicity and liver injury are, in part, induced by SFAs and their intracellular metabolite lysophosphatidyl choline (LPC). However, cellular and molecular mechanisms linking hepatocyte lipotoxicity to liver inflammation are not completely understood. Emerging data implicate extracellular vesicles (EVs) released during hepatocyte lipotoxic stress in liver inflammation. In published and preliminary experiments, we have discovered that, lipotoxic hepatocytes release a large number of proinflammatory EVs; these EVs are enriched with the adhesion molecule integrin β1 (ITGβ1) and promote monocytes adhesion to liver sinusoidal endothelial cells (LSECs) in vitro. We also demonstrated that the expression of ITGβ1 ligand, vascular cell adhesion molecule (VCAM) 1, on LSECs is increased during lipotoxicity. Based on these novel observations, we have formulated the CENTRAL HYPOTHESIS that lipotoxic hepatocytes release ITGβ1-enriched EVs that recruit and retain monocyte in the liver promoting inflammation. We will employ current biochemical and cell biological approaches that include microfluidic technology, Nanoscale flow cytometry, and 89Zirconium isotopically labelled EVs visualized with positron emission tomography (PET) scan to test this hypothesis. Our independent SPECIFIC AIMS will test three integrated hypotheses. First, we will demonstrate that hepatocyte lipotoxicity induces an active conformation switch of ITGβ1, enhancing its endocytic trafficking and release into EVs. Second, we will define the mechanism of increased VCAM1 expression during lipotoxicity. We will also directly test the hypothesis that lipotoxic hepatocyte-derived EVs mediate monocytes adhesion to LSECs, through ITGβ1-VCAM1 binding interaction, in vitro by using microfluidic technology. Third, using a mouse model of NASH, we will test the hypothesis that pharmacological inhibition of integrin β1 or conditional deletion of endothelial VCAM1 is protective against liver inflammation. We will also demonstrate that adoptively-transferred lipotoxic hepatocyte- derived EVs home to the LSECs of recipient mice through their high affinity integrin β1cargo. We have established the requisite cell and mouse models to study lipotoxicity, integrin signaling and EV biology. This proposal is technically and conceptually innovative, as it seeks to integrate the molecular mechanisms underlying hepatocyte injury, integrin activation and trafficking with liver inflammation, and links hepatic pathophysiology with nanomedicine. This research has the potential to identify new therapeutic strategies, namely integrin and VCAM1 inhibitors, to prevent or reverse liver injury and inflammation in human NASH.

项目概要 该提案的总体目标是确定脂毒性过程中肝细胞损伤与肝细胞损伤之间的联系机制。 非酒精性脂肪性肝炎 (NASH) 中的肝脏炎症是最常见的小儿肝脏疾病。 其特点是富含循环饱和游离脂肪酸 (SFA)，以及肝细胞脂毒性和 单核细胞源性巨噬细胞介导的肝脏炎症在一定程度上是肝细胞脂毒性和肝损伤。 然而，SFAs 及其细胞内代谢物溶血磷脂酰胆碱 (LPC) 诱导的。 将肝细胞脂毒性与肝脏炎症联系起来的分子机制尚不完全清楚。 新数据表明肝脏肝细胞脂毒性应激期间释放细胞外囊泡（EV） 在已发表的和初步的实验中，我们发现，脂毒性肝细胞。 释放大量促炎性 EV；这些 EV 富含粘附分子整合素 β1 (ITGβ1) 并在体外促进单核细胞与肝窦内皮细胞 (LSEC) 的粘附。 证明 ITGβ1 配体、血管细胞粘附分子 (VCAM) 1 在 LSEC 上的表达是 基于这些新的观察结果，我们制定了 CENTRAL。 假设脂毒性肝细胞释放富含 ITGβ1 的 EV，这些 EV 在肝细胞中募集并保留单核细胞 我们将采用当前的生化和细胞生物学方法，包括 微流体技术、纳米级流式细胞术和 89Zirconium 同位素标记的 EV 可视化 我们独立的 SPECIFIC AIMS 将通过正电子发射断层扫描 (PET) 扫描来检验这一假设。 首先，我们将证明肝细胞脂毒性会诱导活性。 ITGβ1 的构象转换，增强其内吞运输和释放到 EVs 其次，我们将定义。 我们还将直接检验该假设。 脂毒性肝细胞来源的 EV 通过 ITGβ1-VCAM1 结合介导单核细胞与 LSEC 的粘附 第三，我们将使用 NASH 小鼠模型来测试。 假设整合素 β1 的药理学抑制或内皮 VCAM1 的条件性缺失是 我们还将证明过继转移的脂毒性肝细胞 - 衍生的 EV 通过其高亲和力整合素 β1cargo 归巢于受体小鼠的 LSEC。 建立了研究脂毒性、整合素信号传导和 EV 生物学所需的细胞和小鼠模型。 该提案在技术和概念上都具有创新性，因为它寻求整合分子机制 潜在的肝细胞损伤、整合素激活和运输与肝脏炎症有关，并将肝脏 这项研究有可能确定新的治疗策略， 即整合素和 VCAM1 抑制剂，可预防或逆转人类 NASH 的肝损伤和炎症。