This work was supported by Inserm. Marion Bouvet is a fellow of the French Ministry for Research and Technology. Annie Turkieh is a fellow granted by European Union FP7 HOMAGE (305507).

The protocol follows the guidelines of our institutions human research ethics committee. Buffy coat from healthy human donors were obtained from the Regional Blood Transfusion Center (Lille, France). Samples obtained from the buffy coats are declared as an Inserm collection (n&#176;DC2010-1209).
1. Material and Culture Media Preparation
<ol>
	<li>Dilute 10x Phosphate Buffer Saline (PBS) in sterile distilled water to obtain 1x PBS.</li>
	<li>Make RPMI 1640 medium supplemented with gentamicin (40 &#956;g/ml) and L-glutamine (2 mM), with and without 10% pooled human serum.</li>
</ol>
2. Primary Cultures of Monocyte-derived Macrophages (MDM)
<ol>
	<li>Dilute buffycoat (25 ml) with 1x PBS. Carefully load on a Ficoll/leucosep tube and centrifuge at 1,600 x g for 20 min, at room temperature.</li>
	<li>Collect monocytes at the interface into a new tube. Wash 3x with 10 ml 1x PBS containing 0.1% ethylenediaminetetraacetic acid (EDTA) by successive centrifugations at 1,000 x g, 370 x g and 160 x g for 10 min each, and then once in 1x PBS alone at 160 x g for 10 min.</li>
	<li>Resuspend the cell pellet in 5 ml RPMI-1640 medium without serum and seed the cells in 35 mm dishes at a density of 1 x 106 cells per dish.</li>
	<li>After sedimentation for 90 min in the incubator, discard the supernatant containing the non-adherent cells. Wash the adherent cells, consisting of monocytes, 3x with 1 ml PBS; then add 1 ml of fresh medium containing 10% (v/v) human serum to the previously serum free cells.</li>
	<li>After 6 days of culture, to yield alternative differentiated macrophages (M2), add recombinant human IL-4 (15 ng/ml) and maintain for 6 days. Then, treat differentiated macrophages with lipopolysaccharide (100 ng/ml) at day 12 for 4 hr to obtain M1 macrophages.</li>
</ol>
3. Extraction of M1 and M2 Macrophage Proteins for 2D Electrophoresis
<ol>
	<li>Wash macrophages three times with 25 mM Tris, pH 7.4, and scrap in buffer containing 30 mM Tris pH 8, 4% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), 2 M thiourea and 7 M urea.</li>
	<li>Lyse cells using a mixer suitable for 1.5 ml microcentrifuge tubes for 5 min in ice and store at -20 &#176;C.</li>
	<li>Determine protein concentration using a commercial Bradford reagent. Store 100 &#181;l aliquots of the proteins at -20 &#176;C until use.</li>
</ol>
4. Isoelectrofocusing
NOTE: Perform all labelling procedures in the dark.
<ol>
	<li>Reduce 5 &#181;g of each sample (M1 and M2 macrophages) adjusted to 9 &#956;l with lysis buffer with 2 mM Tris(2-carboxyethyl)phosphine (TCEP) for 1 hr at 37 &#176;C.</li>
	<li>Add cyanine 3 (Cy3) to M1 extract and M2 sulfhydryl-reactive dye extract at a concentration of 0.8 nM/&#956;g protein. Add cyanine 5 (Cy5) to M1 and M2 extracts at a concentration of 0.8 nM/&#956;g protein and incubate for 30 min at 37 &#176;C.</li>
	<li>Stop the reaction with the addition of an equal volume of sample buffer containing 7 M urea, 2 M thiourea, 4% CHAPS, 130 mM dithiothreitol (DTT) and 2% pharmalytes.</li>
	<li>Mix Cy3-labeled M1 samples with Cy5-labeled M2 samples in one hand and Cy3-labeled M2 samples with Cy5-labeled M1 samples in another hand.</li>
	<li>Rehydrate an Immobilized pH gradient (IPG) strip (240 mm, pH 3-10 linear gradient) with 450 &#956;l of labelled mixed samples in buffer containing 7 M urea, 2 M thiourea and 4% CHAPS on a isoelectric focusing (IEF) cell system for 24 hr without applying any current.</li>
	<li>Perform focusing at 300 volts (V) for 3 hr, and then at a gradient to 1,000 V for 6 hr, at a gradient to 8,000 V for 3 hr and finally at 8,000 V for 3 hr.</li>
</ol>
5. Second Dimension
NOTE: Perform all electrophoresis procedures in the dark.
<ol>
	<li>Incubate the IPG strips in equilibration buffer containing 0.1 mM Tris-HCl (pH 8), 6 M urea, 2% (w/v) sodium dodecyl sulfate (SDS) and 30% (v/v) glycerol for 10 min.</li>
	<li>Transfer the equilibrated IPG strips for the second dimension (SDS-polyacrylamide gel electrophoresis (PAGE)) onto 12.5% PAGE gels and seal with low-melting agarose.</li>
	<li>Carry out electrophoresis at 20 &#176;C using an Ettan-Daltsix system at a constant voltage of 70 V overnight followed by 300 V until the bromophenol blue front reaches the bottom of the gel.</li>
</ol>
6. Image Acquisition and Bioinformatic Analysis
<ol>
	<li>Scan gels cast between the two low-fluorescence glass plates with a DIGE Imager scanner at excitation/emission wavelengths of 532/580 nm for Cy3 and 633/670 nm for Cy5 to yield images with a pixel size of 100 &#956;m.</li>
	<li>Perform image analysis with commercial software as previously detailed12.</li>
	<li>Calculate and normalize spot volumes in each image. Assign a normalized spot volume as a proportion of the total value of each spot detected in the gel.</li>
	<li>Analyse the differences in protein spot volumes for each type of macrophages by comparing the normalized spot volume value between the two groups (M1 and M2). Consider the difference between the spot volumes to be significant if the change is 1.5 fold (p &#60;0.05, one-way ANOVA analysis).</li>
</ol>

<ol>
	<li>van Ginderachter, J. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Classical+and+alternative+activation+of+mononuclear+phagocytes:+picking+the+best+of+both+worlds+for+tumor+promotion.">Classical and alternative activation of mononuclear phagocytes: picking the best of both worlds for tumor promotion.</a> Immunobiology. 211, (2006).</li><li>Porcheray, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macrophage+activation+switching:+an+asset+for+the+resolution+of+inflammation.">Macrophage activation switching: an asset for the resolution of inflammation.</a> Clin. Exp. Immunol. 142, 481-489 (2005).</li><li>Gordon, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alternative+activation+of+macrophages.">Alternative activation of macrophages.</a> Nat. Rev. Immunol. 3, 23-35 (2003).</li><li>Mantovani, A., Locati, M., Vecchi, A., Sozzani, S., Allavena, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Decoy+receptors:+a+strategy+to+regulate+inflammatory+cytokines+and+chemokines.">Decoy receptors: a strategy to regulate inflammatory cytokines and chemokines.</a> Trends Immunol. 22, 328-336 (2001).</li><li>Pinet, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphology,+homogeneity+and+functionality+of+human+monocytes-derived+macrophages.">Morphology, homogeneity and functionality of human monocytes-derived macrophages.</a> Cell. Mol. Biol. 49, 899-905 (2003).</li><li>Boyum, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+mononuclear+cells+and+granulocytes+from+human+blood.">Isolation of mononuclear cells and granulocytes from human blood.</a> Isolation of monuclear cells by one centrifugation, and of granulocytes by combining centrifugation and sedimentation at 1. 97, 77-89 (1968).</li><li>Chinetti-Gbaguidi, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+atherosclerotic+plaque+alternative+macrophages+display+low+cholesterol+handling+but+high+phagocytosis+because+of+distinct+activities+of+the+PPAR&#947;+and+LXR&#945;+pathways.">Human atherosclerotic plaque alternative macrophages display low cholesterol handling but high phagocytosis because of distinct activities of the PPAR&#947; and LXR&#945; pathways.</a> Circ. Res. 108, 985-995 (2011).</li><li>Tonge, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Validation+and+development+of+fluorescence+two-dimensional+differential+gel+electrophoresis+proteomics+technology.">Validation and development of fluorescence two-dimensional differential gel electrophoresis proteomics technology.</a> Proteomics. 1, 377-396 (2001).</li><li>Shaw, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+saturation+labelling+two-dimensional+difference+gel+electrophoresis+fluorescent+dyes.">Evaluation of saturation labelling two-dimensional difference gel electrophoresis fluorescent dyes.</a> Proteomics. 3, 1181-1195 (2003).</li><li>Dupont, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+saturation+dye+2D+DIGE+proteomics+to+characterize+proteins+modulated+by+oxidized+low+density+lipoprotein+treatment+of+human+macrophages.">Application of saturation dye 2D DIGE proteomics to characterize proteins modulated by oxidized low density lipoprotein treatment of human macrophages.</a> J. Proteome Res. 7, 3572-3582 (2008).</li><li>Dupont, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two-dimensional+maps+and+databases+of+the+human+macrophage+proteome+and+secretome.">Two-dimensional maps and databases of the human macrophage proteome and secretome.</a> Proteomics. 4, 1761-1778 (2004).</li><li>Acosta-Martin, A. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+incomplete+DNase+I+treatment+on+human+macrophage+analysis.">Impact of incomplete DNase I treatment on human macrophage analysis.</a> Proteomics Clin. Appl. 3, 1236-1246 (2009).</li><li>Acosta-Martin, A. E., Lane, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combining+bioinformatics+and+MS-based+proteomics:+clinical+implications.">Combining bioinformatics and MS-based proteomics: clinical implications.</a> Expert Rev Proteomics. , (2014).</li><li>Boytard, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+proinflammatory+CD68+MR-+macrophages+in+peroxiredoxin-1+expression+and+in+abdominal+aortic+aneurysms+in+humans.">Role of proinflammatory CD68+MR- macrophages in peroxiredoxin-1 expression and in abdominal aortic aneurysms in humans.</a> Arterioscler. Thromb. Vasc. Biol. 33, 431-438 (2013).</li></ol>

There are no declared conflict of interest.

The protocol described herein details a method to analyse the impact of various stimuli of the two subtypes of macrophages, M1 (pro-inflammatory) and M2 (anti-inflammatory). Primary cultures of M1 and M2 macrophages were obtained from the differentiation of monocytes as previously published7.
The procedure of 2D DIGE gel electrophoresis requires specialized materials and equipment, such as IEF cell for isoelectrofocusing, low-fluorescence plates for the SDS-PAGE in order to scan twi...

Macrophages are heterogeneous and plastic cells that are able to acquire distinct functional phenotypes. In vivo, these cells respond to a large variety of micro environmental signalssuch as microbial products, cytokines, etc.1. In vitro, the pro-inflammatory phenotype (M1) of macrophage can be induced by lipopolysaccharide (LPS) and the anti-inflammatory phenotype (M2) by some cytokines such as interleukin-4 (IL-4). Moreover, macrophages can switch from an activated M1 to M2 phenotype, and conversely, upon specific signals2.
Depending on the phenotype, macrophages will have different functions. M1 macrophages are cells that produce pro-inflammatory cytokines, such as tumor necrosis factor &#945; (TNF-&#945;), to kill microorganisms or tumor cells3. In contrast, M2 macrophages prevent these inflammatory response like in wound healing and fibrosis by producing anti-inflammatory factors such as TGF-&#946;3,4.
Human peripheral blood mononuclear cells from healthy donors were isolated by Ficoll density gradient centrifugation as previously described5 using a technique adapted from Boyum6. Macrophages in culture can be differentiated into M1 or M2 phenotype after 6 days of primary culture7.
Analysis of protein expression or protein changes between the two subtypes of macrophages under various controlled stimuli, such as host pathogenicity or microbial toxins, will be helpful to decipher the functionality of the pro- and anti-inflammatory macrophages.
Proteomics are unique tools for direct monitoring of proteins that are specifically up- or down-regulated in human cultured macrophages under various stimuli. Fluorescent dyes have resolved some of the limitations of 2D gel electrophoresis, such as low sensitivity and image analysis8. The dyes reacting with cysteine residues have increased the detection sensitivity compared to those reacting with lysine residues9. In a previous study, we demonstrated the usefulness of DIGE saturation labelling for the analysis of scarce samples10 compared to the classical silver-stained 2D electrophoresis11. This technology is helpful in rapidly analysing protein modifications between the two subtypes of macrophages or between untreated and treated macrophages from the same subtype.
The advantages of this proteomic technique are having access to the information of protein size and post-translational modifications by analysing the 2D gel12. It should be taken into account that this is not a high throughput technique, limiting the number of samples that can be analysed. The development of high throughput assays based on mass spectrometry as reviewed recently13 can improve this.
Here we present how to perform 2D DIGE analysis from the protein extraction of cultured macrophages through the processes of electrophoresis, isoelectrofocusing, and SDS-PAGE as well as information on the usefulness of adequate 2D software.

<table border="0" cellpadding="0" cellspacing="0" width="472">
	<tbody>
		<tr height="17">
			<td height="17" style="height:17px;width:208px;"><a name="RANGE!A1:C43">Name</a></td>
			<td style="width:155px;">Company</td>
			<td style="width:111px;">Catalog number</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">RPMI 1640</td>
			<td>Invitrogen</td>
			<td>31870-074</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">PBX 10 X</td>
			<td>Invitrogen</td>
			<td>14200-083</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">L-glutamine-200mM-100X</td>
			<td>Invitrogen</td>
			<td>25030-024</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">gentamycin 10 mg/mL</td>
			<td>Invitrogen</td>
			<td>15710-049</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">human serum</td>
			<td>Invitrogen</td>
			<td>34005100</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Ficoll d=1,077</td>
			<td>ATGC</td>
			<td>L6115</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Leucosep</td>
			<td>Dutscher</td>
			<td>16760</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">&#160;6-wells plate PRIMARIA&#160;</td>
			<td>Becton Dickinson</td>
			<td>353846</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">IL-4</td>
			<td>Promocell</td>
			<td>B-61410</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">lipopolysaccharide</td>
			<td>Sigma-Aldrich</td>
			<td>L-2654</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Giemsa</td>
			<td>Fluka</td>
			<td>48900</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">EDTA MM372,2</td>
			<td>Research Organics&#160;</td>
			<td>3.00E+01</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Filter 0,22&#181;m</td>
			<td>Millipore</td>
			<td>SCGPTORE</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">100 mL cylinder</td>
			<td>Corning</td>
			<td>430182</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">TCEP</td>
			<td>Interchim</td>
			<td>UP242214</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Bradford reagent</td>
			<td>Bio-Rad</td>
			<td>5000006</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Cy3+Cy5-reactive dye</td>
			<td>GE Healthcare</td>
			<td>25-8009-83</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">IPG strip 3-10 24cm</td>
			<td>GE Healthcare</td>
			<td>17-6002-44</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Protean IEF cell</td>
			<td>Bio-Rad</td>
			<td>165-4000</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Low-melting agarose</td>
			<td>Invitrogen</td>
			<td>15517-014</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Ettan-Daltsix system</td>
			<td>GE Healthcare</td>
			<td>80-6485-08</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Ettan DIGE Imager scanner</td>
			<td>GE Healthcare</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Progenesis Samespot</td>
			<td>Non linear dynamics</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">50 ml tubes</td>
			<td>any supplier</td>
			<td>n/a</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">15 ml tubes</td>
			<td>any supplier</td>
			<td>n/a</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">CHAPS</td>
			<td>Sigma-Aldrich</td>
			<td>C5070</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Ur&#233;e</td>
			<td>Merk</td>
			<td>108484-500</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Thiour&#233;e</td>
			<td>Sigma-Aldrich</td>
			<td>T7875</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">DTT</td>
			<td>Bio-Rad</td>
			<td>1610611</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">APS</td>
			<td>Sigma-Aldrich</td>
			<td>A3678</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">TEMED</td>
			<td>Sigma-Aldrich</td>
			<td>T9281</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Tris Base</td>
			<td>Sigma-Aldrich</td>
			<td>T1503</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Tris HCl</td>
			<td>Sigma-Aldrich</td>
			<td>T3253</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Pharmalytes 3-10</td>
			<td>GE Healthcare</td>
			<td>17-0456-01</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">SDS</td>
			<td>Sigma-Aldrich</td>
			<td>L3773</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Bromophenol blue</td>
			<td>Sigma-Aldrich</td>
			<td>114391</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Glycerol</td>
			<td>Sigma-Aldrich</td>
			<td>G6279</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Acrylamide 40%</td>
			<td>Bio-Rad</td>
			<td>161-0148</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">2D clean Up</td>
			<td>GE Healthcare</td>
			<td>80-6454-51</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Glycine</td>
			<td>Sigma-Aldrich</td>
			<td>G7126</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Dim&#233;thylformamide</td>
			<td>Sigma-Aldrich</td>
			<td>22705-6</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">electrode wicks</td>
			<td>Bio-Rad</td>
			<td>165-4071</td>
		</tr>
	</tbody>
</table>

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.

To perform appropriate differential proteomic analysis, the processing of samples to be analysed should be verified.
In the example presented, the cell culture quality of macrophages is required for morphological and molecular aspects as previously published5. The differentiation of monocytes into macrophages and the homogeneity of the culture was followed by phase-microscopy. Figure 1 showed an example of primary cultures of M1 and M2 macrophages. As shown, we veri...

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Proteomic Profiling of Macrophages by 2D Electrophoresis

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.

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

proteomic-profiling-of-macrophages-by-2d-electrophoresis

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Immunology and Infection

12.5K Views.  University Lille Nord de France. 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.

Video: Proteomic Profiling of Macrophages by 2D Electrophoresis

Depletion and Reconstitution of Macrophages in Mice

Macrophages are critical players in the innate immune response to infectious challenge or injury, initiating the innate immune response and directing the acquired immune response. Macrophage dysfunction can lead to an inability to mount an appropriate immune response and as such, has been implicated in many disease processes, including inflammatory bowel diseases. Macrophages display polarized phenotypes that are broadly divided into two categories. Classically activated macrophages, activated by stimulation with IFN&gamma; or LPS, play an essential role in response to bacterial challenge whereas alternatively activated macrophages, activated by IL-4 or IL-13, participate in debris scavenging and tissue remodeling and have been implicated in the resolution phase of inflammation. During an inflammatory response in vivo, macrophages are found amid a complex mixture of infiltrating immune cells and may participate by exacerbating or resolving inflammation. To define the role of macrophages in situ in a whole animal model, it is necessary to examine the effect of depleting macrophages from the complex environment. To ask questions about the role of macrophage phenotype in situ, phenotypically defined polarized macrophages can be derived ex vivo, from bone marrow aspirates and added back to mice, with or without prior depletion of macrophages. In the protocol presented here clodronate-containing liposomes, versus PBS injected controls, were used to deplete colonic macrophages during dextran sodium sulfate (DSS)-induced colitis in mice. In addition, polarized macrophages were derived ex vivo and transferred to mice by intravenous injection. A caveat to this approach is that clodronate-containing liposomes deplete all professional phagocytes, including both dendritic cells and macrophages so to ensure the effect observed by depletion is macrophage-specific, reconstitution of phenotype by adoptive transfer of macrophages is necessary. Systemic macrophage depletion in mice can also be achieved by backcrossing mice onto a CD11b-DTR background, which is an excellent complementary approach. The advantage of clodronate-containing liposome-mediated depletion is that it does not require the time and expense involved in backcrossing mice and it can be used in mice regardless of the background of the mice (C57BL/6, BALB/c, or mixed background).

Macrophages play a central role in homeostasis and pathology in many tissues. The protocol presented here describes methods for depleting macrophages in vivo, deriving polarized macrophages from bone marrow aspirates, and adoptively transferring macrophages into mice. These techniques allow determination of the role that polarized macrophages play in health and disease.

Macrophages are critical players in the innate  immune response to infectious challenge or injury, initiating the innate immune  response and directing ...

Isolation of Human Monocytes by Double Gradient Centrifugation and Their Differentiation to Macrophages in Teflon-coated Cell Culture Bags

Human macrophages are involved in a plethora of pathologic processes ranging from infectious diseases to cancer. Thus they pose a valuable tool to understand the underlying mechanisms of these diseases. We therefore present a straightforward protocol for the isolation of human monocytes from buffy coats, followed by a differentiation procedure which results in high macrophage yields. The technique relies mostly on commonly available lab equipment and thus provides a cost and time effective way to obtain large quantities of human macrophages. Briefly, buffy coats from healthy blood donors are subjected to a double density gradient centrifugation to harvest monocytes from the peripheral blood. These monocytes are then cultured in fluorinated ethylene propylene (FEP) Teflon-coated cell culture bags in the presence of macrophage colony-stimulating factor (M-CSF). The differentiated macrophages can be easily harvested and used for subsequent studies and functional assays. Important methods for quality control and validation of the isolation and differentiation steps will be highlighted within the protocol. In summary, the protocol described here enables scientists to routinely and reproducibly isolate human macrophages without the need for cost intensive tools. Furthermore, disease models can be studied in a syngeneic human system circumventing the use of murine macrophages.

We present a simple and efficient protocol for the generation of human macrophages. Buffy coats are processed by double density gradient centrifugation and isolated monocytes are then differentiated to macrophages in Teflon-coated cell culture bags. This maximizes macrophage yields and facilitates cell harvesting for subsequent experiments.

Human macrophages are involved in a plethora of pathologic processes ranging from infectious diseases to cancer. Thus they pose a valuable tool to ...

Use of Shigella flexneri to Study Autophagy-Cytoskeleton Interactions

Shigella flexneri is an intracellular pathogen that can escape from phagosomes to reach the cytosol, and polymerize the host actin cytoskeleton to promote its motility and dissemination. New work has shown that proteins involved in actin-based motility are also linked to autophagy, an intracellular degradation process crucial for cell autonomous immunity. Strikingly, host cells may prevent actin-based motility of S. flexneri by compartmentalizing bacteria inside &#8216;septin cages&#8217; and targeting them to autophagy. These observations indicate that a more complete understanding of septins, a family of filamentous GTP-binding proteins, will provide new insights into the process of autophagy. This report describes protocols to monitor autophagy-cytoskeleton interactions caused by S. flexneri in vitro using tissue culture cells and in vivo using zebrafish larvae. These protocols enable investigation of intracellular mechanisms that control bacterial dissemination at the molecular, cellular, and whole organism level.

Use of Shigella flexneri to Study Autophagy-Cytoskeleton Interactions

To counteract pathogen dissemination, host cells reorganize their cytoskeleton to compartmentalize bacteria and induce autophagy. Using Shigella infection of tissue culture cells, host and pathogen determinants underlying this process are identified and characterized. Using zebrafish models of Shigella infection, the role of discovered molecules and mechanisms are investigated in vivo.

Shigella flexneri is an intracellular pathogen that can escape from phagosomes to reach the cytosol, and polymerize the host actin cytoskeleton to promote ...

Assessing Anti-fungal Activity of Isolated Alveolar Macrophages by Confocal Microscopy

The lung is an interface where host cells are routinely exposed to microbes and microbial products. Alveolar macrophages are the first-line phagocytic cells that encounter inhaled fungi and other microbes. Macrophages and other immune cells recognize Aspergillus motifs by pathogen recognition receptors and initiate downstream inflammatory responses. The phagocyte NADPH oxidase generates reactive oxygen intermediates (ROIs) and is critical for host defense. Although NADPH oxidase is critical for neutrophil-mediated host defense1-3, the importance of NADPH oxidase in macrophages is not well defined. The goal of this study was to delineate the specific role of NADPH oxidase in macrophages in mediating host defense against A. fumigatus. We found that NADPH oxidase in alveolar macrophages controls the growth of phagocytosed A. fumigatus spores4. Here, we describe a method for assessing the ability of mouse alveolar macrophages (AMs) to control the growth of phagocytosed Aspergillus spores (conidia). Alveolar macrophages are stained in vivo and ten days later isolated from mice by bronchoalveolar lavage (BAL). Macrophages are plated onto glass coverslips, then seeded with green fluorescent protein (GFP)-expressing A. fumigatus spores. At specified times, cells are fixed and the number of intact macrophages with phagocytosed spores is assessed by confocal microscopy.

A method to evaluate the ability of isolated mouse alveolar macrophages to control the growth of phagocytosed Aspergillus spores by confocal microscopy.

The lung is an interface where host cells are routinely exposed to microbes and microbial products. Alveolar macrophages are the first-line phagocytic ...

Highly Efficient Transfection of Human THP-1 Macrophages by Nucleofection

Macrophages, as key players of the innate immune response, are at the focus of research dealing with tissue homeostasis or various pathologies. Transfection with siRNA and plasmid DNA is an efficient tool for studying their function, but transfection of macrophages is not a trivial matter. Although many different approaches for transfection of eukaryotic cells are available, only few allow reliable and efficient transfection of macrophages, but reduced cell vitality and severely altered cell behavior like diminished capability for differentiation or polarization are frequently observed. Therefore a transfection protocol is required that is capable of transferring siRNA and plasmid DNA into macrophages without causing serious side-effects thus allowing the investigation of the effect of the siRNA or plasmid in the context of normal cell behavior. The protocol presented here provides a method for reliably and efficiently transfecting human THP-1 macrophages and monocytes with high cell vitality, high transfection efficiency, and minimal effects on cell behavior. This approach is based on Nucleofection and the protocol has been optimized to maintain maximum capability for cell activation after transfection. The protocol is adequate for adherent cells after detachment as well as cells in suspension, and can be used for small to medium sample numbers. Thus, the method presented is useful for investigating gene regulatory effects during macrophage differentiation and polarization. Apart from presenting results characterizing macrophages transfected according to this protocol in comparison to an alternative chemical method, the impact of cell culture medium selection after transfection on cell behavior is also discussed. The presented data indicate the importance of validating the selection for different experimental settings.

This protocol presents an efficient and reliable method to transfect human THP-1 macrophages with siRNA or plasmid DNA by electroporation with high transfection efficiency while maintaining high cell vitality and full macrophage capacity for differentiation and polarization.

Macrophages, as key players of the innate immune response, are at the focus of research dealing with tissue homeostasis or various pathologies. ...

Quantification of Cytosolic vs. Vacuolar Salmonella in Primary Macrophages by Differential Permeabilization

Intracellular bacterial pathogens can replicate in the cytosol or in specialized pathogen-containing vacuoles (PCVs). To reach the cytosol, bacteria like Shigella flexneri and Francisella novicida need to induce the rupture of the phagosome. In contrast, Salmonella typhimurium replicates in a vacuolar compartment, known as Salmonella-containing vacuole (SCV). However certain mutants of Salmonella fail to maintain SCV integrity and are thus released into the cytosol. The percentage of cytosolic vs. vacuolar bacteria on the level of single bacteria can be measured by differential permeabilization, also known as phagosome-protection assay. The approach makes use of the property of detergent digitonin to selectively bind cholesterol. Since the plasma membrane contains more cholesterol than other cellular membranes, digitonin can be used to selectively permeabilize the plasma membrane while leaving intracellular membranes intact. In brief, following infection with the pathogen expressing a fluorescent marker protein (e.g. mCherry among others), the plasma membrane of host cells is permeabilized with a short incubation in digitonin containing buffer. Cells are then washed and incubated with a primary antibody (coupled to a fluorophore of choice) directed against the bacterium of choice (e.g. anti-Salmonella-FITC) and washed again. If unmarked bacteria are used, an additional step can be done, in which all membranes are permeabilized and all bacteria stained with a corresponding antibody. Following the staining, the percentage of vacuolar and cytosolic bacteria can be quantified by FACS or microscopy by counting single or double-positive events. Here we provide experimental details for use of this technique with the bacterium Salmonella typhimurium. The advantage of this assay is that, in contrast to other assay, it provides a quantification on the level of single bacteria, and if analyzed by microscopy provides the exact number of cytosolic and vacuolar bacteria in a given cell.

Quantification of Cytosolic vs. Vacuolar Salmonella in Primary Macrophages by Differential Permeabilization

We describe the quantification of cytosolic and vacuolar Salmonella typhimurium in bone-marrow derived macrophages using differential digitonin permeabilization.

Intracellular bacterial pathogens can replicate in the cytosol or in specialized pathogen-containing vacuoles (PCVs). To reach the cytosol, bacteria like ...

Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry

There is increasing evidence suggesting the important role of inflammation and, subsequently, macrophages in the development and progression of renal disease. Macrophages are heterogeneous cells that have been implicated in kidney injury. Macrophages may be classified into two different phenotypes: classically activated macrophages (M1 macrophages), that release pro-inflammatory cytokines and promote fibrosis; and alternatively activated macrophages (M2 macrophages) that are associated with immunoregulatory and tissue-remodeling functions. These macrophage phenotypes need to be discriminated and analyzed to determine their contribution to renal injury. However, there are scarce studies reporting consistent phenotypic and functional information about macrophage subtypes in inflammatory renal disease models, especially in rats. This fact may be related to the limited macrophage markers used in rats, contrary to mice. Therefore, novel strategies are necessary to quantify and characterize the renal content of these infiltrating cells in a reliable way. This manuscript details a protocol for kidney digestion and further phenotypic and quantitative analysis of macrophages from rat kidneys by flow cytometry. Briefly, kidneys were incubated with collagenase and total macrophages were identified according to the dual presence of CD45 (leukocytes common antigen) and CD68 (PAN macrophage marker) in live cells.This was followed by surface staining of CD86 (M1 marker) and CD163 (M2 marker). Rat peritoneal macrophages were used as positive control for macrophage marker detection by flow cytometry. Our protocol resulted in low cellular mortality and allowed characterization of different intracellular and surface protein markers, thus limiting the loss of cellular integrity observed in other protocols. Moreover, this procedure allows the use of macrophages for further techniques, including cell sorting and mRNA or protein expression studies, among others.

This manuscript describes a detailed protocol for phenotypic and quantitative analysis of resident macrophages from rat kidneys by flow cytometry. The resulting stained cells can be also used for other applications, including cell sorting, gene expression analysis or functional studies, thus increasing the information obtained in the experimental model.

There is increasing evidence suggesting the important role of inflammation and, subsequently, macrophages in the development and progression of renal ...

SILAC Based Proteomic Characterization of Exosomes from HIV-1 Infected Cells

Proteomics is the large-scale analysis of proteins. Proteomic techniques, such as liquid chromatography tandem mass spectroscopy (LC-MS/MS), can characterize thousands of proteins at a time. These powerful techniques allow us to have a systemic understanding of cellular changes, especially when cells are subjected to various stimuli, such as infections, stresses, and specific test conditions. Even with recent developments, analyzing the exosomal proteome is time-consuming and often involves complex methodologies. In addition, the resultant large dataset often needs robust and streamlined analysis in order for researchers to perform further downstream studies. Here, we describe a SILAC-based protocol for characterizing the exosomal proteome when cells are infected with HIV-1. The method is based on simple isotope labeling, isolation of exosomes from differentially labeled cells, and mass spectrometry analysis. This is followed by detailed data mining and bioinformatics analysis of the proteomic hits. The resultant datasets and candidates are easy to understand and often offer a wealth of information that is useful for downstream analysis. This protocol is applicable to other subcellular compartments and a wide range of test conditions.

Here, we describe a quantitative proteomics method using the technique of stable isotope labeling by amino acids in cell culture (SILAC) to analyze the effects of HIV-1 infection on host exosomal proteomes. This protocol can be easily adapted to cells under different stress or infection conditions.

Proteomics is the large-scale analysis of proteins. Proteomic techniques, such as liquid chromatography tandem mass spectroscopy (LC-MS/MS), can ...

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.

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.

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