Cholesterol regulation of Macrophage Inflammation and Vascular Diseases

巨噬细胞炎症和血管疾病的胆固醇调节

• 批准号: 8917663
• 负责人: SHOBHA GHOSH
• 金额: --
• 依托单位: VA VETERANS ADMINISTRATION HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8917663
• 关键词: ATP binding cassette transporter 1; Affect; Anti-Inflammatory Agents; Anti-inflammatory; Atherosclerosis; Attenuated; Bacterial Toxins; CASP1 gene; Cardiovascular Diseases; Cell Surface Proteins; Cell Surface Receptors; Cell surface; Cellular Membrane; Characteristics; Cholesterol; Cholesterol Esters; Cholesterol Homeostasis; Chronic; Coronary Arteriosclerosis; Development; Diabetes Mellitus; Disease; Enzymes; Foam Cells; Future; Generations; Genetic Transcription; Homeostasis; Immune; Infection; Inflammation; Inflammatory; Injury; Interferon Type I; Interleukin-1; Interleukin-10; Ion Channel; Link; Lipids; Macrophage Activation; Mediating; Membrane; Membrane Lipids; Membrane Microdomains; Metabolic; Metabolic Diseases; Molecular; Nature; Non-Insulin-Dependent Diabetes Mellitus; Nutrient; Obesity; Pathway interactions; Pattern; Plasma; Population; Potassium Channel; Prevalence; Prevention; Process; Production; Regulation; Research Design; Role; Sentinel; Signal Transduction; Sterility; Syndrome; TLR4 gene; Testing; Transcriptional Activation; Transgenic Mice; Transgenic Organisms; Vascular Diseases; Veterans; attenuation; base; burden of illness; clinically relevant; cytokine; esterase; extracellular; in vivo; lipid metabolism; macrophage; novel; overexpression; pathogen; public health relevance; restoration; sterol esterase; targeted treatment; therapeutic target; western diet

 DESCRIPTION (provided by applicant): Low grade chronic inflammation associated with obesity is the underlying cause of the development of metabolic diseases including Type 2 diabetes (T2DM) and atherosclerosis. The most important characteristics of chronic inflammation are its persistence and inability to resolve resulting in lack of restoration of homeostasis and development of metabolic diseases. In contrast to classical inflammation which is triggered by an injury or infection, this low grade chronic inflammation is "sterile" in nature without a direct involvement of a pathogen and is often triggered by nutrients and metabolic surplus and hence also referred to as metaflammation meaning metabolically triggered inflammation. Metaflammation is characterized by abnormal cytokine production especially Interleukin-1 (IL-1) and persistent activation of a network of inflammatory pathways. Chronic activation of innate immune sentinels or macrophages underlies this abnormal cytokine production however the cellular mechanisms involved are not completely defined. The production and secretion of IL-1 from macrophages is under very tight regulation which requires coordination of two Signals, namely Signal 1: cellular priming required for inducing transcription (via NF-B), and Signal 2: activation of NLRP3 inflammasome for proteolytic cleavage of pro-IL-1 by active Caspase-1 and secretion of mature IL-1. Increase in cellular lipid accumulation is one of the prominent features of obesity and intracellular lipid metabolism, especially cholesterol metabolism, is tightly linked to the inflammatory status of macrophages. For example, inability to efficiently efflux excess cholesterol due to deficiency of ABCA1 transporter increases cytokine production from macrophages and increase inflammation. Consistently, we have demonstrated that reduction in macrophage cholesterol content by macrophage-specific transgenic over-expression of cholesterylester (CE) hydrolase (CEH, an enzyme that hydrolyzes intracellular stored CE and rate-limits cholesterol efflux) leads to a dramatic (>20 fold) reduction in plasma IL-1 levels. However, the mechanisms underlying the "crosstalk" between cellular cholesterol homeostasis and inflammatory pathways have not been established as yet. Both signals required for activation of inflammatory pathways depend on cell surface proteins: signaling via cell surface receptors (e.g., TLR4) associated with membrane lipid rafts or cholesterol- enriched membrane micro-domains is required for Signal 1 and Signal 2 or NLRP3 activation is triggered by K+ efflux regulated by cell surface-associated ion channels. Since the presence/function of these cell surface receptors and channels depends on the cellular/membrane cholesterol or lipid-raft levels, We hypothesize that CEH-mediated reduction in cellular cholesterol content attenuates 1) the "priming" of macrophages by modulating TLR4 signaling and 2) the "activation" of the inflammasome via changes in cellular K+ efflux and thereby beneficially modulates macrophage function. We propose the following Aims to test the hypothesis: Aim 1: To delineate the mechanisms by which CEH-mediated changes in cellular cholesterol content can modulate macrophage "priming" or Signal 1. Aim 2: To delineate the mechanisms underlying CEH-mediated modulation of "inflammasome activation" or Signal 2 via cellular cholesterol depletion. Aim 3: To evaluate the role of CEH-mediated attenuation of Signal 1 and Signal 2-dependent macrophage activation in modulating inflammation in vivo. These studies will establish that targeted reduction in macrophage cholesterol content would simultaneously attenuate multiple metabolic diseases including Type 2 Diabetes and Coronary Artery Disease (CAD). In addition, the comprehensive approach used will define the pathways by which hydrophobic cholesterol "communicates" with the inflammatory machinery and identify molecular mechanisms that can be explored as potential therapeutic targets in future (e.g., regulating K+ efflux) to modulate other sterile inflammation based diseases.

 描述（由申请人提供）： 与肥胖相关的低度慢性炎症是包括 2 型糖尿病 (T2DM) 和动脉粥样硬化在内的代谢性疾病发展的根本原因，慢性炎症最重要的特征是其持续存在且无法消退。 导致体内平衡恢复不足和代谢疾病的发生与由损伤或感染引发的经典炎症相比，这种低度慢性炎症本质上是“无菌的”，没有病原体的直接参与，并且通常是“无菌”的。 由营养物质和代谢过剩引发，因此也称为代谢性炎症，即代谢引发的炎症，其特征是细胞因子的异常产生，特别是白细胞介素 1 (IL-1) 和细胞网络的持续激活。 先天免疫哨兵或巨噬细胞的慢性激活是细胞因子产生异常的基础，但所涉及的细胞机制尚未完全确定。 巨噬细胞产生和分泌 IL-1 受到非常严格的调节，需要两个信号的协调，即信号 1：诱导转录所需的细胞启动（通过 NF-B），以及信号 2：激活 NLRP3 炎症小体活性 Caspase-1 对 pro-IL-1 的蛋白水解和成熟 IL-1 的分泌是细胞脂质积累增加的原因之一。肥胖和细胞内脂质代谢，特别是胆固醇代谢的显着特征与巨噬细胞的炎症状态密切相关，例如，由于ABCA1转运蛋白的缺乏而无法有效地排出过量的胆固醇，从而增加了巨噬细胞的细胞因子产生并增加了炎症。我们已经证明，通过巨噬细胞特异性转基因过度表达胆固醇酯（CE）水解酶（CEH，一种水解细胞内储存的 CE 和速率限制胆固醇流出）导致血浆 IL-1 水平显着降低（>20 倍）。然而，细胞胆固醇稳态和炎症途径之间“串扰”的机制尚未确定。炎症通路的激活依赖于细胞表面蛋白：信号 1 和信号 2 需要通过与膜脂筏或富含胆固醇的膜微域相关的细胞表面受体（例如 TLR4）进行信号传导或 NLRP3 激活是由细胞表面相关离子通道调节的 K+ 外流触发的，因为这些细胞表面受体和通道的存在/功能取决于细胞/膜胆固醇或脂筏水平，我们追求 CEH 介导的减少。细胞胆固醇含量减弱：1) 通过调节 TLR4 信号传导来“启动”巨噬细胞，2) 通过改变细胞 K+ 流出来“激活”炎症小体，从而有益我们提出以下目标来检验这一假设： 目标 1：描述 CEH 介导的细胞胆固醇含量变化调节巨噬细胞“启动”或信号 1 的机制。 目标 2：描述 CEH 的潜在机制。通过细胞胆固醇消耗介导的“炎症体激活”或信号 2 的调节 目标 3：评估 CEH 介导的减弱作用。信号 1 和信号 2 依赖性巨噬细胞激活调节体内炎症，这些研究将确定有针对性地降低巨噬细胞胆固醇含量将同时减轻多种代谢疾病，包括 2 型糖尿病和冠状动脉疾病 (CAD)。所使用的方法将定义疏水性胆固醇与炎症机制“沟通”的途径，并确定可作为未来潜在治疗靶点探索的分子机制（例如，调节 K+ 流出）以调节其他基于无菌性炎症的疾病。