Richard Ouedraogo is supported by a grant from the Minist&#232;re de la Sant&#233; (PHRC 2010). We thank Laurent Gorvel, Christophe Flaudrops and Nicolas Amstrong for technical assistance.

In the present protocol, the whole-cell MALDI-TOF technique is used to obtain a mass spectrum considered as a fingerprint of the sample. A bioinformatic analysis allowed the comparison and the classification of these fingerprints. There were three main parts in this protocol:
<ol>
	<li>The preparation of the biological samples: control macrophages and macrophages stimulated with different agonists.</li>
	<li>The analysis of each type of sample with technical replicates by whole-cell MALDI-TOF MS.</li>
	<li>The bioinformatics analysis of raw data.</li>
</ol>
Prepare sterile solutions for cell isolation and culture. Prepare and store all reagents at 4 &#176;C
1. Preparation of Human Monocytes
<ol>
	<li>Prepare cell culture medium. Add 55 ml&#160;of human serum AB+ or fetal bovine serum (FBS) and 5 ml&#160;of the antibiotic solution (penicillin at 10,000 UI/ml and streptomycin at 10,000 &#956;g/ml; final concentration of 100 UI/ml&#160;for penicillin and 100 &#956;g/ml&#160;for streptomycin) to RPMI 1640 medium (500 ml).
	<ol>
		<li>Isolate peripheral blood mononuclear cells (PBMCs) from leukopacks (leukocyte concentrates).
		<ol>
			<li>Prepare 50&#160;ml&#160;tubes containing 15 ml&#160;Ficoll. Dilute the blood in saline (vol/vol, 1/10). Deposit 30 ml&#160;diluted PBMCs on Ficoll as previously described26.</li>
			<li>Centrifuge at 700 x g for 20 min. Recover PBMCs at the interface between Ficoll (density of 1.077 g/ml) and diluted plasma. Dilute PBMCs in culture medium and centrifuge at 300 x g for 5 min.</li>
		</ol>
		</li>
		<li>Prepare CD14+ monocytes from PBMCs using magnetic beads coated with anti-CD14 antibodies. 
		Note: Keep products and cells at 4 &#176;C until monocyte obtention.
		<ol>
			<li>Prepare running buffer consisting of phosphate-buffered saline (PBS) pH 7.2, 0.5% bovine serum albumin (BSA) and 2 mM ethylenediaminetetraacetic acid (EDTA).</li>
			<li>Gently dissociate pelleted PBMCs (107 cells per assay) into 80 &#956;l&#160;of running buffer.</li>
			<li>Add 20 &#956;l&#160;CD14 MicroBeads to PBMCs. Mix and incubate PBMCs for 15 min. Wash PBMCs with 5 ml&#160;of running buffer and centrifuge at 300 x g for 5 min. Gently dissociate pelleted PBMCs into 500 &#956;l&#160;of running buffer for 108 PBMCs. 
			Note: use 500 &#956;l&#160;of running buffer for PBMC concentrations lower than 108 PBMCs.</li>
			<li>Proceed to magnetic separation. 
			Note: for less than 2 x 108 PBMCs, use MS column; for more than 2 x 108 PBMCs and less than 2 x 109 PBMCs, use LS column.</li>
			<li>Rinse precolumn and column with running buffer (500 &#956;l&#160;for MS column or 3 ml&#160;for LS column). Add PBMCs into the precolumn (wait for unlabeled cells to pass through the column). Rinse 3 times with running buffer (500 &#956;l&#160;for MS column or 3 ml&#160;for LS column). Remove the precolumn.</li>
			<li>Place the column on 15&#160;ml&#160;tubes. Add running buffer (1 ml&#160;for MS column or 5 ml for LS column) on the column and elute CD14+ cells by applying a pressure on the column.</li>
			<li>Centrifuge the eluate at 300 x g for 5 min. Discard the supernatant. Wash monocyte pellet with 10 ml&#160;of culture medium. 
			Note: Analyze the purity of monocyte preparation using anti-CD14 antibodies and flow cytometry (classically higher than 95%).</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Differentiation of monocytes into macrophages.
	<ol>
		<li>Incubate monocytes (106 monocytes per well in 6&#160;well plates) in 3 ml&#160;of culture medium containing 10% human serum AB+ at 37 &#176;C. After 4 days, replace the culture medium containing human serum by 3 ml&#160;culture medium containing 10% FBS for 3 additional days.</li>
		<li>Identify the obtained cell population as monocyte-derived macrophages (MDMs) by flow cytometry (see Figure 1).
		<ol>
			<li>Replace the culture medium by 3 ml&#160;PBS. Scrape MDMs with a rubber policeman and collect MDM suspensions. Centrifuge at 400 x g for 5 min. Add PBS containing 2% BSA to pelleted MDMs and gently agitate cell suspension. Adjust the cell concentration (106 MDMs in 200 ml&#160;PBS) and incubate at 4 &#176;C.</li>
			<li>Add 10 ml&#160;of anti-CD14 antibodies and 10 ml&#160;of anti-CD68 antibodies to MDM suspension and incubate at 4 &#176;C for 20 min in the dark. 
			Note: these antibodies must be labeled with two different fluorochromes consistent with flow cytometry analysis. For example, anti-CD14 antibodies may be conjugated with phycoerythrin coupled (for monocytes staining) and anti-CD68 antibodies with Alexa Fluor 647 coupled (for macrophages staining).</li>
			<li>Centrifuge MDMs at 400 x g for 5 min. Remove supernatants. Gently dissociate the cell pellet and incubate MDMs in 250 ml&#160;3% paraformaldehyde (PFA) for 15 min at room temperature. Centrifuge PFA-fixed MDMs at 400 x g for 5 min. Wash MDMs with 3 ml&#160;PBS and centrifuge MDMs at 400 x g for 5 min. Gently dissociate MDM pellet in 400 ml&#160;PBS.</li>
			<li>Analyze the differentiation of monocytes (that express CD14 but not CD68) into monocytes (that express CD68 but not CD14). Note: classically more than 95% of cells are MDM.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>18 hr&#160;stimulation of MDMs.
	<ol>
		<li>Replace the culture medium of adherent MDMs by fresh 3 ml&#160;culture medium (containing 10% FBS).</li>
		<li>To induce a M1 or M2 polarization, use the following human recombinant cytokines: IFN-&#947; and TNF for M1 polarization, and IL-4 for M2 polarization. M1 macrophages are also obtained by stimulation with LPS. Note that stock-solutions of cytokines are conserved at -80 &#176;C and that the stock-solution of LPS is conserved at -20 &#176;C.
		<ol>
			<li>Dilute the stock-solution of IFN-g&#947; (1 mg/ml) at 1/100 in culture medium to obtain a dilution of 10 ng/ml. Add 6 &#956;l of this IFN-&#947; dilution to MDMs to obtain a final IFN-&#947; concentration of 20 ng/ml.</li>
			<li>Dilute the stock-solution of TNF (1 mg/ml) at 1/100 in culture medium to obtain a dilution of 10 ng/ml. Add 6 &#956;l of this TNF dilution to MDMs to obtain a final TNF concentration of 20 ng/ml.</li>
			<li>Dilute the stock-solution of IL-4 (1 mg/ml) at 1/100 in culture medium to obtain a dilution of 10 ng/ml. Add 6 &#956;l of this IL-4 dilution to MDMs to obtain a final IL-4 concentration of 20 ng/ml.</li>
			<li>Add 3 &#956;l of the stock-solution of LPS (1 mg/ml) to MDMs to obtain a final LPS concentration of 1 &#956;g/ml.</li>
		</ol>
		</li>
		<li>To stimulate MDMs with bacteria, use heat-killed bacteria. Wash living bacteria with PBS and heat them at 95 &#176;C for 1 hr. Use Orientia tsutsugamushi (strain Kato (CSUR R163), Mycobacterium bovis (Bacillus Calmette-Gu&#233;rin, BCG CIP strain 671203) and Coxiella burnetii (Nine Mile in phase I) were because these pathogens are known to infect macrophages. Thus, prepare a O. tsutsugamushi suspension at 109 bacteria/ml. Add 50 &#956;l to MDMs . Repeat the same step for M. bovis and C. burnetii.</li>
	</ol>
	</li>
	<li>Preparation of biological samples for MALDI-TOF MS.
	<ol>
		<li>Wash stimulated MDMs with PBS without Ca2+ or Mg2+ (cells may agglutinate in the presence of Ca2+ or Mg2+). Scrape MDMs with a rubber policeman and collect MDM suspensions. Centrifuge MDMs. Wash again MDMs in PBS without Ca2+ or Mg2+ at 400 x g for 5 min to discard FBS contamination.</li>
		<li>Adjust the cell concentration (2 x 106 MDMs per assay). Centrifuge MDMs at 400 x g for 5 min and discard supernatants. Collect cell pellets in 20 &#956;l of PBS without Ca2+ or Mg2+.</li>
		<li>Analyze samples immediately or store them in PBS at -80 &#176;C before analysis.</li>
	</ol>
	</li>
</ol>
2. Analysis of Macrophages by Whole-Cell Maldi-TOF MS
<ol>
	<li>Preparation of CHCA matrix.
	<ol>
		<li>Add 500 &#956;l of acetonitrile, 250 &#956;l 10% trifluoroacetic acid, and 250 &#956;l of high-performance liquid chromatography (HPLC) water to a vial. Dilute 10 mg of CHCA in this solution to a final concentration of 10 mg/ml. Mix and sonicate for at least 20 min. 
		Note: sonication will improve the saturation of the matrix but this step is not mandatory.</li>
		<li>Centrifuge at 13,000 x g for 5 min. Discard the pellet and keep the supernatant. 
		Note: prepare the matrix solution just before use. A matrix solution that contains crystals does not allow a good ionization of sample molecules, and this may affect the quality of the spectra.</li>
	</ol>
	</li>
	<li>Preparation of MALDI steel target.
	<ol>
		<li>Moisten the polished steel target with hot tap water. Rub with precision wipe paper. Add 70% ethanol and rub. Rinse with water by rubbing. Add 70% ethanol and rub with precision paper.</li>
		<li>Immerse the target in 70% ethanol and sonicate for at least 15 min. Cover the target with 500 &#956;l to 1 ml&#160;of trifluoroacetic acid at 80%. Rub and wipe with precision paper. Rinse with HPLC water without rubbing. Dry the target at room temperature. 
		Note: an improperly cleaned target may affect the quality of the spectra.</li>
	</ol>
	</li>
	<li>Preparation of deposits.
	<ol>
		<li>Place the clean target on a horizontal and level support to obtain uniform deposits.</li>
		<li>Gently thaw MDM samples on ice. Note: rapid and vigorous thawing may alter samples, thus affecting the quality of the spectra. Homogenize MDMs (by pipetting back and forth the cell suspension) before deposition of 1 &#956;l (containing approximately 1 x 105 cells) on the MALDI target. Add 1 &#956;l of the MALDI matrix solution on the sample. Avoid mixing spot with the pipette. Mixing spots with pipettes alters the quality of the spectra. Depose 12-16 samples/assay (technical replicates).</li>
		<li>Evaporate spontaneously at room temperature. Note: evaporation takes place gradually and leads to the formation of matrix/sample crystals. The deposits may be immediately analyzed or stored in the dark for several days before analysis (up to 2 weeks).</li>
		<li>User should control that the cytokines or heat-killed bacteria used in the experiment do not provide peaks within the range of stimulated macrophages&#39; spectra. Here, we checked that the cytokines and heat-killed bacteria alone did not provide any signal within the studied range (0-20 kDa).</li>
	</ol>
	</li>
	<li>Mass spectrometer tuning and data acquisition.
	<ol>
		<li>Insert the steel target containing samples in the mass spectrometer.</li>
		<li>Configure the mass spectrometer and run data acquisition. Use the default configuration for automated acquisition of the data.</li>
		<li>Note: a detailed view of the configuration of flexControl software is given in the appendix/Table 1. This may vary according to mass spectrometer and software used.</li>
	</ol>
	</li>
</ol>
3. Bioinformatic Analysis
Note: the bioinformatic analysis was performed using the free and open source statistical analysis software R, along with specific analysis libraries (MALDIquant). R can be downloaded freely from its website <a href="http://cran.r-project.org/">http://cran.r-project.org/</a>. A detailed description of the script is provided as supplementary material.
<ol>
	<li>Loading and pretreatment of raw data.
	<ol>
		<li>Store raw data on the computer associated with the mass spectrometer in multiple files and folders. Retrieve the root folder of the experiment with all subfolders. Copy root folder to personal computer for analysis.</li>
		<li>Use readBrukerFlexData and MALDIquant libraries to load and analyze raw data. 
		Note: readBrukerFlexData allows the loading of raw data from the mass spectrometer into a specific object in R for further analysis. See MALDIquant description for further information27.</li>
		<li>Analyze generated spectra. 
		Note: each spectrum consists of a list of peaks with their respective masses and intensities (relative abundance). Use the square root of the intensities to enhance the graphical visualization of the spectra. Correct the background using a statistic-sensitive nonlinear peak-clipping algorithm for baseline estimation27. Use a signal-to-noise ratio of 6 to detect peaks. Consider that the detected peaks are similar across spectra when the mass/charge (m/z) values are within a 2,000 ppm window.</li>
	</ol>
	</li>
	<li>Score definition and computation. Classify the spectra using a hierarchical clustering with a ward algorithm for agglomeration and a dissimilarity matrix based on the Jaccard distance. 
	Note: the Jaccard index measures the similarity between Boolean sample sets (i.e. the presence/absence of a list of peaks).</li>
	<li>Comparison of spectra and viewing.
	<ol>
		<li>Analyze raw spectra plots. Note: x-axis represents the m/z ratio (in Daltons) and the y-axis represents the intensity (relative abundance).</li>
		<li>Assess the similarity between spectra by hierarchical clustering. Represent similarity (or divergence) as dendrogram.</li>
		<li>Assess the reproducibility by the mean of virtual gel-view representation. Note: virtual gel-view representation is a modified heatmap plot where relative abundance is color-coded with increasing intensities of blue.</li>
	</ol>
	</li>
</ol>

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The authors have no conflict of interest to declare. RO, JLM and CC are inventors of an international patent WO 2011/154650, named "Proc&#233;d&#233; d&#39;identification de cellules de mammif&#232;res par spectrom&#233;trie de masse MALDI-TOF".

This protocol describes the use of MALDI-TOF-MS on eukaryotic whole cells. Here, we illustrate the accuracy of the method by analyzing the multiple activation states of macrophages in response to their microenvironment.
The success of the protocol relies on few critical steps. First, any solution contaminant may alter the spectra. For example, it is important to wash cells in PBS to remove culture medium and serum proteins before deposition on the target. A cell concentration of 1 x 105</...

Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) is a popular mass spectrometry technique to study biological samples. Using a laser beam and an energy-absorbing matrix allows a soft ionization process: the evaporation and genesis of large mostly single-charged biomolecules. This process is called desorption/ionization, justifying the acronym MALDI. These ions are then accelerated by application of voltage and enter a TOF analyzer that allows the separation of these ions and the quantification of their respective masses1.
MALDI-TOF MS has been extensively used in biology, chemistry, and medicine to identify molecules and biomarkers2-4&#160;or to monitor post-translational modifications on&#160;proteins5,6. Recently, several groups applied MALDI-TOF MS to the identification of microorganisms from clinical samples7,8. This microbiological application is now used routinely in the clinical settings. Whole cell MALDI-TOF has many advantages compared to classical applications of MALDI-TOF MS. Samples containing whole cells are directly processed, avoiding time consuming steps to fractionate or separate large amounts of material. Moreover, no characterization of the various peaks is needed: the whole spectrum is considered as a fingerprint of the sample, and matching algorithms compare the tested spectrum with a database of reference spectra.
We and others have applied this whole-cell analysis technique to eukaryotic cells. Many applications may be derived from this technique: (1) identify the main cell types from a mixed sample9-11; (2) assess the viability of cell cultures over time (including quality control industrial applications)12; (3) monitor activation states of a single cell type13; (4) assess the malignant transformation of a clinical sample14,15.
Here, we describe the use of whole-cell MALDI-TOF MS to explore the various polarization phenotypes of macrophages in response to cytokines or heat-killed bacteria. Macrophages play a pivotal role in the immune response to microbial pathogens. They detect infectious agents in the tissues through pattern recognition receptors able to detect conserved microbial patterns, such as lipopolysaccharide (LPS)16. Macrophages are professional antigen-presenting cells that interact with T cells to mount the adaptive immune response. T cells influence macrophages by releasing cytokines that either reinforce or regulate the microbicidal activity of macrophages. By analogy to the Th1/Th2 lymphocyte polarization, inflammatory, microbicidal, and tumoricidal macrophages have been classified into M1 macrophages and immunoregulator macrophages as M2 macrophages17-19. The term M1 refers to the classical activation of macrophages by type I cytokines, such as interferon (IFN)-&#947; and tumor necrosis factor (TNF), or bacterial products, such as LPS18,20-23, whereas macrophages activated by alternative pathways (interleukin (IL)-4, IL-10, Transforming Growth Factor-&#946;1 are considered M2 macrophages19,24,25. The high phenotypic and functional plasticity of macrophages in response to their microenvironment renders these macrophages useful to analyze subtle changes by a MALDI-TOF MS approach.

whole-cell maldi-tof mass spectrometry is an accurate and rapid method to analyze different modes of macrophage activation

MALDI-TOF is an extensively used mass spectrometry technique in chemistry and biochemistry. It has been also applied in medicine to identify molecules and biomarkers. Recently, it has been used in microbiology for the routine identification of bacteria grown from clinical samples, without preparation or fractionation steps. We and others have applied this whole-cell MALDI-TOF mass spectrometry technique successfully to eukaryotic cells. Current applications range from cell type identification to quality control assessment of cell culture and diagnostic applications. Here, we describe its use to explore the various polarization phenotypes of macrophages in response to cytokines or heat-killed bacteria. It allowed the identification of macrophage-specific fingerprints that are representative of the diversity of proteomic responses of macrophages. This application illustrates the accuracy and simplicity of the method. The protocol we described here may be useful for studying the immune host response in pathological conditions or may be extended to wider diagnostic applications.

The aim of the present protocol is to demonstrate the accuracy of whole-cell MALDI-TOF MS to assess the responsiveness of macrophages to their microenvironment.
Figure 1 describe preparation of stimulated macrophages from blood samples. Figure 2 represents the analysis of monocytes and MDMs by flow cytometry. Note that monocytes expressed CD14 but not CD68 (Figure 1A). Conversely, MDMs expressed CD68 but not CD14 (Figure 1B).<...

Watch this Scientific Journal Video about Whole-cell MALDI-TOF Mass Spectrometry is an Accurate and Rapid Method to Analyze Different Modes of Macrophage Activation at JoVE.com

Whole-cell MALDI-TOF Mass Spectrometry is an Accurate and Rapid Method to Analyze Different Modes of Macrophage Activation

This protocol describes the use of whole-cell MALDI-TOF mass spectrometry on eukaryotic cells. Here, we illustrate the accuracy of this technique by analyzing the multiple activation states of macrophages in response to their microenvironment.

전체 셀 MALDI-TOF 질량 분석은 대 식세포의 활성화의 다양한 모드를 분석 할 수있는 정확하고 빠른 방법입니다

MALDI-TOF is an extensively used mass spectrometry technique in chemistry and biochemistry. It has been also applied in medicine to identify molecules and ...

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Immunology and Infection

8.8K 조회수.  Aix Marseille Université. This protocol describes the use of whole-cell MALDI-TOF mass spectrometry on eukaryotic cells. Here, we illustrate the accuracy of this technique by analyzing the multiple activation states of macrophages in response to their microenvironment.

비디오: Whole-cell MALDI-TOF Mass Spectrometry is an Accurate and Rapid Method to Analyze Different Modes of Macrophage Activation

Proteomic Analysis of Human Macrophage Polarization Under a Low Oxygen Environment

Macrophages are innate immune cells involved in a number of physiological functions ranging from responses to infectious pathogens to tissue homeostasis. The various functions of these cells are related to their activation states, which is also called polarization. The precise molecular description of these various polarizations is a priority in the field of macrophage biology. It is currently acknowledged that a multidimensional approach is necessary to describe how polarization is controlled by environmental signals. In this report, we describe a protocol designed to obtain the proteomic signature of various polarizations in human macrophages. This protocol is based on a label-free quantification of macrophage protein expression obtained from in-gel fractionated and Lys C/trypsin-digested cellular lysis content. We also provide a protocol based on in-solution digestion and isoelectric focusing fractionation to use as an alternative. Because oxygen concentration is a relevant environmental parameter in tissues, we use this protocol to explore how atmospheric composition or a low oxygen environment affects the classification of macrophage polarization.

We present a protocol to obtain proteomic signatures of human macrophages and apply this to determination of the impact of a low oxygen environment on macrophage polarization.

낮은 산소 환경에서 인간 대 식 세포 분극의 Proteomic 분석

Macrophages are innate immune cells involved in a number of physiological functions ranging from responses to infectious pathogens to tissue homeostasis. ...

연구

생화학

Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways.

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways.

골수 유래 대 식세포를 사용하여 대식 세포 분극 조사

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic ...

면역학 및 감염병학

Proteomic Profiling of Macrophages by 2D Electrophoresis

The goal of the two-dimensional (2D) electrophoresis protocol described here is to show how to analyse the phenotype of human cultured macrophages. The key role of macrophages has been shown in various pathological disorders such as inflammatory, immunological, and infectious diseases. In this protocol, we use primary cultures of human monocyte-derived macrophages that can be differentiated into the M1 (pro-inflammatory) or the M2 (anti-inflammatory) phenotype. This in vitro model is reliable for studying the biological activities of M1 and M2 macrophages and also for a proteomic approach. Proteomic techniques are useful for comparing the phenotype and behaviour of M1 and M2 macrophages during host pathogenicity. 2D gel electrophoresis is a powerful proteomic technique for mapping large numbers of proteins or polypeptides simultaneously. We describe the protocol of 2D electrophoresis using fluorescent dyes, named 2D Differential Gel Electrophoresis (DIGE). The M1 and M2 macrophages proteins are labelled with cyanine dyes before separation by isoelectric focusing, according to their isoelectric point in the first dimension, and their molecular mass, in the second dimension. Separated protein or polypeptidic spots are then used to detect differences in protein or polypeptide expression levels. The proteomic approaches described here allows the investigation of the macrophage protein changes associated with various disorders like host pathogenicity or microbial toxins.

Macrophages are the key cells involved in host pathogenicity. Macrophages display phenotypic and functional diversity that can be analysed and detected by proteomic analysis. This article describes how to perform 2D electrophoresis of primary cultures of human macrophages differentiated into M1 or M2 phenotype.

2D 전기 영동에 의한 대 식세포의 프로테옴 프로파일 링

The goal of the two-dimensional (2D) electrophoresis protocol described here is to show how to analyse the phenotype of human cultured macrophages. The ...

Metabolic Characterization of Polarized M1 and M2 Bone Marrow-derived Macrophages Using Real-time Extracellular Flux Analysis

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&#8217;s metabolic phenotype and inflammatory status.

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&#8217;s metabolism and phenotype.

실시간 세포 외 유출 분석을 사용하여 편광 M1과 M2 골수 유래 대 식세포의 대사 특성

Specific metabolic pathways are increasingly being recognized as critical hallmarks of macrophage subsets. While LPS-induced classically activated M1 or ...

Isolation, Characterization, and Purification of Macrophages from Tissues Affected by Obesity-related Inflammation

Obesity promotes a chronic inflammatory state that is largely mediated by tissue-resident macrophages as well as monocyte-derived macrophages. Diet-induced obesity (DIO) is a valuable model in studying the role of macrophage heterogeneity; however, adequate macrophage isolations are difficult to acquire from inflamed tissues. In this protocol, we outline the isolation steps and necessary troubleshooting guidelines derived from our studies for obtaining a suitable population of tissue-resident macrophages from mice following 18 weeks of high-fat (HFD) or high-fat/high-cholesterol (HFHCD) diet intervention. This protocol focuses on three hallmark tissues studied in obesity and atherosclerosis including the liver, white adipose tissues (WAT), and the aorta. We highlight how dualistic usage of flow cytometry can achieve a new dimension of isolation and characterization of tissue-resident macrophages. A fundamental section of this protocol addresses the intricacies underlying tissue-specific enzymatic digestions and macrophage isolation, and subsequent cell-surface antibody staining for flow cytometric analysis. This protocol addresses existing complexities underlying fluorescent-activated cell sorting (FACS) and presents clarifications to these complexities so as to obtain broad range characterization from adequately sorted cell populations. Alternate enrichment methods are included for sorting cells, such as the dense liver, allowing for flexibility and time management when working with FACS. In brief, this protocol aids the researcher to evaluate macrophage heterogeneity from a multitude of inflamed tissues in a given study and provides insightful troubleshooting tips that have been successful for favorable cellular isolation and characterization of immune cells in DIO-mediated inflammation.

This protocol allows a researcher to isolate and characterize tissue-resident macrophages in various hallmark inflamed tissues extracted from diet-induced models of metabolic disorders.

절연, 특성화 및 비만 관련 염증에 의해 영향을 받는 조직에서 세포의 정화

Obesity promotes a chronic inflammatory state that is largely mediated by tissue-resident macrophages as well as monocyte-derived macrophages. ...

Analysis of Microglia and Monocyte-derived Macrophages from the Central Nervous System by Flow Cytometry

Numerous studies have demonstrated the role of immune cells, in particular macrophages, in central nervous system (CNS) pathologies. There are two main macrophage populations in the CNS: (i) the microglia, which are the resident macrophages of the CNS and are derived from yolk sac progenitors during embryogenesis, and (ii) the monocyte-derived macrophages (MDM), which can infiltrate the CNS during disease and are derived from bone marrow progenitors. The roles of each macrophage subpopulation differ depending on the pathology being studied. Furthermore, there is no consensus on the histological markers or the distinguishing criteria used for these macrophage subpopulations. However, the analysis of the expression profiles of the CD11b and CD45 markers by flow cytometry allows us to distinguish the microglia (CD11b+CD45med) from the MDM (CD11b+CD45high). In this protocol, we show that the density gradient centrifugation and the flow cytometry analysis can be used to characterize these CNS macrophage subpopulations, and to study several markers of interest expressed by these cells as we recently published. Thus, this technique can further our understanding of the role of macrophages in mouse models of neurological diseases and can also be used to evaluate drug effects on these cells.

This protocol provides an analysis of the macrophage subpopulations in the adult mouse central nervous system by flow cytometry and is helpful for the study of multiple markers expressed by these cells.

유동 세포 계측법에 의한 중추 신경계에서 유래 된 대장 세포 및 단구 세포 유래 대 식세포의 분석

Numerous studies have demonstrated the role of immune cells, in particular macrophages, in central nervous system (CNS) pathologies. There are two main ...

Detection of Inflammasome Activation and Pyroptotic Cell Death in Murine Bone Marrow-derived Macrophages

Inflammasomes are innate immune signaling platforms that are required for the successful control of many pathogenic organisms, but also promote inflammatory and autoinflammatory diseases. Inflammasomes are activated by cytosolic pattern recognition receptors, including members of the NOD-like receptor (NLR) family. These receptors oligomerize upon the detection of microbial or damage-associated stimuli. Subsequent recruitment of the adaptor protein ASC forms a microscopically visible inflammasome complex, which activates caspase-1 through proximity-induced auto-activation. Following the activation, caspase-1 cleaves pro-IL-1&#946; and pro-IL-18, leading to the activation and secretion of these pro-inflammatory cytokines. Caspase-1 also mediates the inflammatory form of cell death termed pyroptosis, which features the loss of membrane integrity and cell lysis. Caspase-1 cleaves gasdermin D, releasing the N-terminal fragment which forms plasma membrane pores, leading to osmotic lysis.
In vitro, the activation of caspase-1 can be determined by labeling bone marrow-derived macrophages with the caspase-1 activity probe FAM-YVAD-FMK and by labeling the cells with antibodies against the adaptor protein ASC. This technique allows the identification of inflammasome formation and caspase-1 activation in individual cells using fluorescence microscopy. Pyroptotic cell death can be detected by measuring the release of cytosolic lactate dehydrogenase into the medium. This procedure is simple, cost effective and performed in a 96-well plate format, allowing adaptation for screening. In this manuscript, we show that activation of the NLRP3 inflammasome by nigericin leads to the co-localization of the adaptor protein ASC and active caspase-1, leading to pyroptosis.

We describe the detection of NLRP3 inflammasome activation on cellular basis using fluorescence microscopy and staining for active caspase-1 and the adaptor, ASC. A lactate dehydrogenase release assay is presented to detect pyroptotic lysis on a population basis. These techniques can be adapted to study many aspects of inflammasome biology.

Inflammasome 활성화 및 Pyroptotic 세포 죽음 Murine 골 수 유래 세포에서의 검출

Inflammasomes are innate immune signaling platforms that are required for the successful control of many pathogenic organisms, but also promote ...

Fluorescence-mediated Tomography for the Detection and Quantification of Macrophage-related Murine Intestinal Inflammation

Murine models of disease are indispensable to scientific research. However, many diagnostic tools such as endoscopy or tomographic imaging are not routinely employed in animal models. Conventional experimental readouts often rely on post mortem and ex vivo analyses, which prevent intra-individual follow-up examinations and increase the number of study animals needed. Fluorescence-mediated tomography enables the non-invasive, repetitive, quantitative, three-dimensional assessment of fluorescent probes. It is highly sensitive and permits the use of molecular makers, which allows for the specific detection and characterization of distinct molecular targets. In particular, targeted probes represent an innovative tool for analyzing gene activation and protein expression in inflammation, autoimmune disease, infection, vascular disease, cell migration, tumorigenesis, etc. In this article, we provide step-by-step instructions on this sophisticated imaging technology for the in vivo detection and characterization of inflammation (i.e., F4/80-positive macrophage infiltration) in a widely used murine model of intestinal inflammation. This technique might also be used in other research areas, such as immune cell or stem cell tracking.

Target-specific probes represent an innovative tool for analyzing molecular mechanisms, such as protein expression in various types of disease (e.g., inflammation, infection, and tumorigenesis). In this study, we describe a quantitative three-dimensional tomographic assessment of intestinal macrophage infiltration in a murine model of colitis using F4/80-specific fluorescence-mediated tomography.

검색 및 대 식 세포 관련 Murine 창 자 염증의 정량화에 대 한 단층 형광 중재

Murine models of disease are indispensable to scientific research. However, many diagnostic tools such as endoscopy or tomographic imaging are not ...

의학

Polarization of M1 and M2 Human Monocyte-Derived Cells and Analysis with Flow Cytometry upon Mycobacterium tuberculosis Infection

Human macrophages are primary host cells of intracellular Mycobacterium tuberculosis (Mtb) infection and thus have a central role in immune control of tuberculosis (TB). We have established an experimental protocol to follow immune polarization of myeloid-derived cells into M1 (classically activated) or M2 (alternatively activated) macrophage-like cells through assessment with a 10-color flow cytometry panel that allows visualization and deep-characterization of green-fluorescent-protein (GFP)-labeled Mtb in diverse macrophages subsets. Monocytes obtained from healthy blood donors were polarized into M1 or M2 cells using differentiation with granulocyte macrophage-colony-stimulating factor (GM-CSF) or macrophage-colony stimulating factor (M-CSF) followed by polarization with IFN-&#947; and lipopolysaccharide (LPS) or IL-4, respectively. Fully polarized M1 and M2 cells were infected with Mtb-GFP for 4 hours before detached Mtb-infected macrophages were stained with flow cytometry at 4- or 24-hours post-infection. Sample acquisition was performed with flow cytometry and the data was analyzed using a flow cytometry analysis software. Manual gating as well as dimensionality reduction with Uniform Manifold Approximation and Projection (UMAP) and phenograph analysis was performed. This protocol resulted in effective M1/M2 polarization characterized by elevated levels of CD64, CD86, TLR2, HLA-DR and CCR7 on uninfected M1 cells, while uninfected M2 cells exhibited a strong up-regulation of the M2 phenotype markers CD163, CD200R, CD206 and CD80. M1-polarized cells typically contained fewer bacteria compared to M2-polarized cells. Several M1/M2 markers were downregulated after Mtb infection, which suggests that Mtb can modulate macrophage polarization. In addition, 24 different cell clusters of different sizes were found to be uniquely distributed among the M1 and M2 uninfected and Mtb-infected cells at 24-hours post-infection. This M1/M2 flow cytometry protocol could be used as a backbone in Mtb-macrophage research and be adopted for special needs in different areas of research.

Polarization of M1 and M2 Human Monocyte-Derived Cells and Analysis with Flow Cytometry upon Mycobacterium tuberculosis Infection

This protocol provides a method to study Mycobacterium tuberculosis infection in human M1- or M2-polarized macrophages based on differentiation of peripheral-blood-monocytes to macrophage-like cells that are infected with the GFP-labeled virulent strain H37Rv, and analyzed with flow cytometry using a 10-color panel including expression of selected M1/M2 markers.

M1 및 M2 인간 단세포 유래 세포의 편광 및 진균 결핵 감염에 대한 유동 세포측정을 분석

Human macrophages are primary host cells of intracellular Mycobacterium tuberculosis (Mtb) infection and thus have a central role in immune control of ...

Analyzing Ex Vivo Metabolic Flux in Splenic and Cardiac Macrophages and Bone Marrow Monocytes

Metabolic reprogramming is a hallmark of monocyte/macrophage activation and polarization between pro- and anti-inflammatory states. For example, pro-inflammatory (i.e., M1-like) monocytes/macrophages display more reliance on anaerobic glycolysis and less reliance on mitochondrial oxidative phosphorylation, whereas anti-inflammatory (M2-like) macrophages display more reliance on glucose and fatty acid oxidation in the mitochondria. Here, we describe in-depth protocols for extracting macrophages from the two major monocyte/macrophage reservoirs in the body, the spleen and bone marrow, as well as injured tissues such as the heart following myocardial infarction.
Macrophages or monocytes are extracted by immunomagnetic sorting by using antibody-tagged microbeads, which easily bind to cells without compromising their phenotypes. The extracted cells are then cultured in 96-well plates, followed by extracellular flux analysis using a metabolic flux analyzer. Both glycolysis and mitochondrial oxidative phosphorylation can be measured simultaneously in small numbers of cells (as little as 2-3 &#215; 105 cells). This method can easily be performed in 1 day and produces reliable and repeatable results. Ultimately, these methods help to enhance our understanding of metabolic changes during immune and inflammatory responses to injury and disease, which could lead to the development of novel therapeutic targets for immunometabolic pathways.

Here, we describe in detail methods for extracting macrophages from the bone marrow, spleen, and infarcted heart, and subsequently assessing metabolic flux in live cells.