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: 9206076
• 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/9206076
• 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 physiology; Cell surface; Cellular Membrane; Characteristics; Chemicals; Cholesterol; Cholesterol Esters; Cholesterol Homeostasis; Chronic; Coronary Arteriosclerosis; Development; Disease; Enzymes; Foam Cells; Future; Generations; Genetic Transcription; Homeostasis; Hydrophobicity; Immune; Infection; Inflammasome; Inflammation; Inflammatory; Injury; Interferon Type I; Interleukin-1; Interleukin-10; Ion Channel; Link; Lipids; Macrophage Activation; Mediating; Membrane Lipids; Membrane Microdomains; Metabolic; Metabolic Diseases; Molecular; Nature; Non-Insulin-Dependent Diabetes Mellitus; Nutrient; Obesity; Pathway interactions; Pattern; Periodicity; Plasma; Population; Potassium Channel; Prevalence; Prevention; Production; Regulation; Role; Sentinel; Signal Transduction; Signaling Protein; Sterility; Syndrome; TLR4 gene; Testing; Transgenic Mice; Transgenic Organisms; Vascular Diseases; Veterans; attenuation; base; burden of illness; clinically relevant; cytokine; design; 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)： 与肥胖相关的低级别慢性炎症是包括2型糖尿病(T2 DM)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久性和无法消退 导致动态平衡的缺乏恢复和代谢性疾病的发展。与由损伤或感染引发的经典炎症不同，这种低级别的慢性炎症本质上是无菌的，没有病原体的直接参与，而且通常 由营养和代谢过剩引发，因此也被称为代谢反应，意思是新陈代谢引发的炎症。细胞因子的异常产生，尤其是白介素1(IL-1)的产生和一系列细胞因子的持续激活是其特征。 炎症途径。先天性免疫哨兵或巨噬细胞的慢性激活是这种异常细胞因子产生的基础，然而涉及的细胞机制尚不完全清楚。 巨噬细胞IL-1的产生和分泌受到非常严格的调控，这需要两个信号的协调，即信号1：诱导转录所需的细胞启动(通过核因子-B)和信号2：激活NLRP3炎症体，使活化的Caspase-1蛋白水解酶裂解原-IL-1，并分泌成熟的IL-1。细胞内脂质蓄积增加是肥胖的显著特征之一，细胞内脂代谢，尤其是胆固醇代谢与巨噬细胞的炎症状态密切相关。例如，由于ABCA1转运体缺乏而无法有效地排出过量的胆固醇，会增加巨噬细胞产生的细胞因子，并增加炎症。我们一直证明，通过巨噬细胞特异性转基因过表达胆固醇水解酶(CEH，一种降解细胞内储存的CE并限制胆固醇外流的酶)来降低巨噬细胞胆固醇含量，会导致血浆IL-1水平显著降低(&gt；20倍)。然而，细胞胆固醇稳态和炎症途径之间的“串扰”机制还没有建立起来。激活炎症通路所需的两种信号都依赖于细胞表面蛋白：信号1需要通过与膜脂筏或高胆固醇膜微域相关的细胞表面受体(例如TLR4)传递信号，而信号2或NLRP3的激活是由细胞表面相关离子通道调节的K+外流触发的。由于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，我们假设CEH介导的细胞胆固醇含量的降低可以减弱1)通过调节TLR4信号对巨噬细胞的“启动”，以及2)通过改变细胞K+流出而对炎症小体的“激活”，从而有益地调节巨噬细胞的功能。目的1：阐明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。目的2：阐明CEH通过细胞胆固醇耗竭调节“炎症体激活”或信号2的机制。目的：探讨CEH介导的信号1减弱和信号2依赖的巨噬细胞激活在体内炎症调控中的作用。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性疾病，包括2型糖尿病和冠状动脉疾病(CAD)。此外，所使用的综合方法将确定疏水性胆固醇与炎症机制进行“交流”的途径，并确定未来可作为潜在治疗靶点探索的分子机制(例如，调节K+外流)以调节其他基于无菌炎症的疾病。