Metabolic reprogramming is a characteristic and prerequisite for M1 and M2 macrophage polarization. This manuscript describes an assay for the measurement of fundamental parameters of glycolysis and mitochondrial function in mouse bone marrow-derived macrophages. This tool can be applied to investigate how particular factors affect the macrophage’s metabolism and phenotype.
Specific metabolic pathways are increasingly being recognized as critical hallmarks of macrophage subsets. While LPS-induced classically activated M1 or M(LPS) macrophages are pro-inflammatory, IL-4 induces alternative macrophage activation and these so-called M2 or M(IL-4) support resolution of inflammation and wound healing. Recent evidence shows the crucial role of metabolic reprogramming in the regulation of M1 and M2 macrophage polarization.
In this manuscript, an extracellular flux analyzer is applied to assess the metabolic characteristics of naive, M1 and M2 polarized mouse bone marrow-derived macrophages. This instrument uses pH and oxygen sensors to measure the extracellular acidification rate (ECAR) and oxygen consumption rate (OCR), which can be related to glycolytic and mitochondrial oxidative metabolism. As such, both glycolysis and mitochondrial oxidative metabolism can be measured in real-time in one single assay.
Using this technique, we demonstrate here that inflammatory M1 macrophages display enhanced glycolytic metabolism and reduced mitochondrial activity. Conversely, anti-inflammatory M2 macrophages show high mitochondrial oxidative phosphorylation (OXPHOS) and are characterized by an enhanced spare respiratory capacity (SRC).
The presented functional assay serves as a framework to investigate how particular cytokines, pharmacological compounds, gene knock outs or other interventions affect the macrophage’s metabolic phenotype and inflammatory status.
虽然巨噬细胞发挥在几乎所有的疾病中发挥核心作用,调节其表型的分子机制还没有完全拆开的。巨噬细胞显示出高的异质性,并响应于微环境采用不同的表型1。 LPS(+IFNγ)诱导激活经典的M1或M(LPS),巨噬细胞促进炎症,并防止不同类型的微生物威胁2的主机。其他使用IFNγ单独或与肿瘤坏死因子的刺激诱发M1两极分化。 IL-4和/或IL-13诱导的替代巨噬细胞活化和这些M 2 或M(IL-4)细胞是有效的抑制剂和正在进行的免疫反应3控制器。偏光巨噬细胞显示细胞代谢的独特调控脂多糖激活的巨噬细胞M1进行代谢开关增强糖酵解4-6。相反,增强脂肪酸氧化(FAO)和线粒体oxidativë磷酸化(OXPHOS)提供持续的能量中的IL-4诱导的巨噬细胞的M2 7-9。因此,改变的代谢不仅是偏振光巨噬细胞子集的特性的同时,还进行适当的极化和炎症调节的先决条件。重要的是,糖酵解或OXPHOS的抑制/ FAO已经证明削弱M1或M2激活,分别8,10。这样,在巨噬细胞识别代谢变化可作为一种工具,以评估它们的极化状态和炎性电位施加。
一致的测定法,其测量细胞巨噬细胞代谢因此可以用于预测药物,基因是否击倒或其他处理的影响巨噬细胞极化和功能。在此视频,一个细胞外通量分析仪用于表征幼稚,M1和M2巨噬细胞的生物能学概况。
这份手稿详细介绍了优化的协议,允许测量所有相关的参数酵解(糖酵解,最大糖酵解和糖的储备)和线粒体功能特点(共呼吸,基础线粒体呼吸,ATP的产生,质子漏,最大呼吸和备用呼吸能力)在一个单一的检测。使用该实验装置,生物能可以控制和'改变'之间进行比较( 如基因敲除,转基因过表达或药物治疗)的细胞。
我们实验室的目的是了解如何巨噬细胞极化和功能可以与最终目标,以改善动脉粥样硬化和其它炎性病症12的结果的影响。为了评估偏振巨噬细胞,人们通常测量LPS(+IFNγ)诱导和IL-4诱导的M1和M2的标记基因(定量PCR)的基因表达,确定IL-6,IL-12,TNF和分泌NO(通过ELISA和格里斯反应),检验IL-4诱导的CD71,CD206,CD273和CD301的表面表达(通过流式细胞术)和精氨酸酶的活性3,13。此外,细胞凋亡测定(通过膜联蛋白V / PI染色),吞噬作用测定法(用荧光胶乳珠和/或pHrodo 大肠杆菌 )和泡沫细胞形成测定法(由的DiI-脂蛋白摄取,LipidTOX中性脂质染色)可被执行以评估巨噬细胞的功能14。此外,细胞外通量分析可以被执行以测量生物能极化的mac型材噬细胞作为一种新的和替代的功能读出。
这份手稿表明,巨噬细胞极化导致代谢重新编程与LPS诱导巨噬细胞切换到糖酵解增加它们的能量来源。相反,IL-4诱导的巨噬细胞的M2使用线粒体氧化磷酸作为ATP的主要来源。重要的是,代谢重新编程不仅提供能量的M1和M2极化巨噬细胞的特殊要求。事实上,代谢变化影响代谢物浓度是巨噬细胞的表型10,15,16的直接监管。因此,巨噬细胞的新陈代谢,不仅是特性(如图这里在图2中),而且也鲜明的巨噬细胞的偏振状态的驱动器,这新的知识支持immunometabolism研究领域的快速发展,在过去的几年。
然而,在宏代谢概况健壮测量噬菌体依然严峻,有其局限性。在这项研究中,细胞外磁通分析器被施加到鲁棒测量糖酵解,糖酵解储备,最大糖酵解容量,非糖酵解酸化,基底和最大呼吸,ATP产生,备用呼吸容量,质子泄漏和非线粒体呼吸实时在巨噬细胞的一个最小量。
因此,我们修改和改进制造商的协议如下。标准美图压力测试(#103015-100)建议使用中葡萄糖和丙酮酸和3次注射(OM,FCCP,AA / ROT)的协议。我们选择开始与葡萄糖/丙酮酸的培养基的测定中,添加葡萄糖作为第一注射口A(象在糖酵解压力测试#103020-100)中,用所述FCCP解偶联剂在端口C以这种方式添加丙酮酸一起,所有相关的糖酵解参数从ECAR测量1-9和有关mitochondri所有相关信息来源人的功能从OCR测量4-15。
需要注意的是它为丙酮酸连同FCCP注入后解偶联到燃料最大呼吸是至关重要的。使用这种组合的协议之前,人们也应该验证-2-脱氧-D-葡萄糖(2-DG)降低该测定的基础值(1-3)后ECAR水平,且录制ECAR率4-6是确因以糖酵解。此外,应该理解,在该手稿中使用的化合物的浓度和细胞数是有效的骨髓来源的巨噬细胞和巨噬细胞的Raw264.7细胞系和其它细胞类型应优化。而且,应该注意的是M-CSF,用来产生骨髓来源的巨噬细胞促进一个M2状抗炎表型。因此所呈现的结果从骨髓衍生的巨噬细胞可以是不完全与用主组织驻留的巨噬细胞或巨噬细胞的细胞系的测量不期间细胞culturi需要M-CSFNG。
相比于现有的方法,该协议要求的巨噬细胞的最小量,并迅速提供了几乎所有的基础代谢细胞特征。这导致足够剩余细胞以执行其它免疫学测定法,甚至用于生物能量谱的细胞仍然可以用于其它的测定后旨意。此外,特定的96孔板格式允许评估实时多个条件在同一时间。然而,各个孔之间的变化可以是相当大的,因此,每个条件使用至少4个孔的通常需要。采取这种限制考虑在内,所描述的外磁通分析仍然允许运行超过10的实验条件(6)一次,这比传统技术更。
总体而言,本文提供了一个简单的和可重复的功能测定,使测量所有相关的糖酵解和线粒体参数ETERS在极化巨噬细胞亚群。这种技术可以作为未来应用以评估巨噬细胞功能,并评价不同的操作上的巨噬细胞的(代谢)的表型的影响 (例如基因敲除,新药物等 )。因此,细胞外通量数据可以结合使用其他测定,以允许深入表征的巨噬细胞激活状态。
The authors have nothing to disclose.
Jan Van den Bossche received a Junior Postdoc grant from the Netherlands Heart Foundation (2013T003) and a VENI grant from ZonMW (91615052). Menno de Winther is an Established Investigator of the Netherlands Heart Foundation (2007T067), is supported by a Netherlands Heart Foundation grant (2010B022) and holds an AMC-fellowship. We also acknowledge the support from the Netherlands Cardiovascular Research Initiative, Dutch Federation of University Medical Centers, the Netherlands Organization for Health Research and Development and the Royal Netherlands Academy of Sciences for the GENIUS project “Generating the best evidence-based pharmaceutical targets for atherosclerosis” (CVON2011-19). We acknowledge Seahorse Bioscience for making open access publication possible. The authors thank Riekelt Houtkooper and Vincent de Boer (Laboratory Genetic Metabolic Diseases, Academic Medical Center, Amsterdam, The Netherlands) for all previous assistance with the Seahorse analyzer.
23G and 25G needles | Becton Dickinson | #300800 and #300600 | To flushed bone marrow |
10 ml syringes | Becton Dickinson | #307736 | To flushed bone marrow |
Petri dishes | Greiner | #639161 | To culture bone marrow cells |
CyQUANT Cell Proliferation Assay kit | Molecular Probes | #C7026 | For cell quantification at a later time point (works only for adherent cells) |
CyQUANT Direct Cell Proliferation Assay kit | Molecular Probes | #35011 | For cell quantification immediately after assay (non-adherent cells) |
XFe96 cell culture microplate | Seahorse Bioscience | #101085-004 | 96 well plate in which cells are cultured and in which assay is done |
recombinant mouse interleukin-4 (IL-4) | Peprotech | #214-14-B | Used to induced alternative macrophage activation |
lipopolysaccharide (LPS) | Sigma | #L2637 | Pro-inflammatory stimulus |
Seahorse Sensor Cartridge | Seahorse Bioscience | #102416-100 | Contains the probes for pH and O2 measurement |
Seahorse XF Calibrant | Seahorse Bioscience | #100840-000 | Needed to hydrate the probes overnight |
XF base medium | Seahorse Bioscience | #102353-100 | Buffer-free medium that allows efficient measurement of pH changes |
L-glutamine | Life Technologies | #25030-081 | |
D-(+)-Glucose | Sigma | #G8769 | Fuels glycolysis once added to the cells |
oligomycin A | Sigma | #75351 | Inhibits mitochondrial ATP synthase |
FCCP( Carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone) | Sigma | #C2920 | Uncouples mitochondrial respiration |
100 mM Sodium Pyruvate solution | Lonza | #BE13-115E | Allows maximal mitochondrial respiration without the need for glycolysis |
Antimycin A | Sigma | #BE13-115EA8674 | Inhibits complex III of the mitochondria |
Rotenone | Sigma | #BE13-115EA8674R8875 | Inhibits complex I of the mitochondria |
Casy Cell Counter | Roche Diagnostics | #05 651 697 001 | Instrument to count cells |
anti-CD16/CD32 | eBioscience | #14-0161 | Fc receptor block flow cytometry |
anti-F4/80-APC-eFluor780 | eBioscience | #47-4801 | Antibody to stain macrophages |
anti-CD11b-FITC | eBioscience | #11-0112 | Antibody to stain macrophages |