AM is funded by the Young Group Leader Program (ATIP/Avenir Inserm-CNRS), by la Ligue Nationale contre le Cancer and la Fondation ARC pour la recherche sur le Cancer. We thank Mariette Matondo from the Mass Spectrometry for Biology platform (UTECHS MSBIO, Pasteur Institute, Paris). We thank Lauren Anderson for her reading of the manuscript.

Human blood samples (LRSC) from healthy, de-identified donors were obtained from EFS (French National Blood Service) as part of an authorized protocol (CODECOH DC-2018&#8211;3114). Donors gave signed consent for the use of blood.
1. Media and Buffer Preparation
<ol>
	<li>Prepare the macrophage medium [RPMI glutamax + 10 mM HEPES + 1x non-essential amino acids (NEAA)] and warm it to 37 &#176;C.</li>
	<li>Prepare the macrophage medium + 10% human serum from AB plasma (SAB), filter it (0.22 &#1...

<ol>
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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macrophage+Polarization.">Macrophage Polarization.</a> Annual Review of Physiology. 79, 541-566 (2017).</li><li>Chinetti-Gbaguidi, G., Staels, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macrophage+polarization+in+metabolic+disorders:+functions+and+regulation.">Macrophage polarization in metabolic disorders: functions and regulation.</a> Current Opinion in Lipidology. 22 (5), 365-372 (2011).</li><li>Chow, A., Brown, B. D., Merad, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studying+the+mononuclear+phagocyte+system+in+the+molecular+age.">Studying the mononuclear phagocyte system in the molecular age.</a> Nature Reviews Immunology. 11 (11), 788-798 (2011).</li><li>Mosser, D. M., Edwards, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploring+the+full+spectrum+of+macrophage+activation.">Exploring the full spectrum of macrophage activation.</a> Nature Reviews Immunology. 8 (12), 958-969 (2008).</li><li>Murray, P. J., Wynn, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protective+and+pathogenic+functions+of+macrophage+subsets.">Protective and pathogenic functions of macrophage subsets.</a> Nature Reviews Immunology. 11 (11), 723-737 (2011).</li><li>Ginhoux, F., Schultze, J. L., Murray, P. J., Ochando, J., Biswas, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+insights+into+the+multidimensional+concept+of+macrophage+ontogeny,+activation+and+function.">New insights into the multidimensional concept of macrophage ontogeny, activation and function.</a> Nature Immunology. 17 (1), 34-40 (2016).</li><li>Xue, 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=Transcriptome-based+network+analysis+reveals+a+spectrum+model+of+human+macrophage+activation.">Transcriptome-based network analysis reveals a spectrum model of human macrophage activation.</a> Immunity. 40 (2), 274-288 (2014).</li><li>Csete, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxygen+in+the+cultivation+of+stem+cells.">Oxygen in the cultivation of stem cells.</a> Annals of the New York Academy of Sciences. 1049, 1-8 (2005).</li><li>Johansson, 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=Functional,+morphological,+and+phenotypical+differences+between+rat+alveolar+and+interstitial+macrophages.">Functional, morphological, and phenotypical differences between rat alveolar and interstitial macrophages.</a> American Journal of Respiratory Cell and Molecular Biology. 16 (5), 582-588 (1997).</li><li>Pfau, J. C., Schneider, J. C., Archer, A. J., Sentissi, J., Leyva, F. J., Cramton, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Environmental+oxygen+tension+affects+phenotype+in+cultured+bone+marrow-derived+macrophages.">Environmental oxygen tension affects phenotype in cultured bone marrow-derived macrophages.</a> American Journal of Physiology. Lung Cellular and Molecular Physiology. 286 (2), L354-L362 (2004).</li><li>Grodzki, A. C. G., Giulivi, C., Lein, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxygen+tension+modulates+differentiation+and+primary+macrophage+functions+in+the+human+monocytic+THP-1+cell+line.">Oxygen tension modulates differentiation and primary macrophage functions in the human monocytic THP-1 cell line.</a> PLoS One. 8 (1), e54926 (2013).</li><li>Court, M., Petre, G., Atifi, M. E., Millet, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteomic+Signature+Reveals+Modulation+of+Human+Macrophage+Polarization+and+Functions+Under+Differing+Environmental+Oxygen+Conditions.">Proteomic Signature Reveals Modulation of Human Macrophage Polarization and Functions Under Differing Environmental Oxygen Conditions.</a> Molecular &amp; Cellular Proteomics. 16 (12), 2153-2168 (2017).</li><li>Cox, 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=Accurate+proteome-wide+label-free+quantification+by+delayed+normalization+and+maximal+peptide+ratio+extraction,+termed+MaxLFQ.">Accurate proteome-wide label-free quantification by delayed normalization and maximal peptide ratio extraction, termed MaxLFQ.</a> Molecular &amp; Cellular Proteomics. 13 (9), 2513-2526 (2014).</li><li>Cox, J., Neuhauser, N., Michalski, A., Scheltema, R. A., Olsen, J. V., Mann, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Andromeda:+a+peptide+search+engine+integrated+into+the+MaxQuant+environment.">Andromeda: a peptide search engine integrated into the MaxQuant environment.</a> Journal of Proteome Research. 10 (4), 1794-1805 (2011).</li><li>Shevchenko, A., Tomas, H., Havlis, J., Olsen, J. V., Mann, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In-gel+digestion+for+mass+spectrometric+characterization+of+proteins+and+proteomes.">In-gel digestion for mass spectrometric characterization of proteins and proteomes.</a> Nature Protocols. 1 (6), 2856-2860 (2006).</li><li>Court, M., 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=Toward+a+standardized+urine+proteome+analysis+methodology.">Toward a standardized urine proteome analysis methodology.</a> Proteomics. 11 (6), 1160-1171 (2011).</li><li>Wi&#347;niewski, J. R., Zougman, A., Nagaraj, N., Mann, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Universal+sample+preparation+method+for+proteome+analysis.">Universal sample preparation method for proteome analysis.</a> Nature Methods. 6 (5), 359-362 (2009).</li><li>Liebler, D. C., Ham, A. -. J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spin+filter-based+sample+preparation+for+shotgun+proteomics.">Spin filter-based sample preparation for shotgun proteomics.</a> Nature Methods. 6 (11), 785-786 (2009).</li><li>Hubner, N. C., Ren, S., Mann, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peptide+separation+with+immobilized+pI+strips+is+an+attractive+alternative+to+in-gel+protein+digestion+for+proteome+analysis.">Peptide separation with immobilized pI strips is an attractive alternative to in-gel protein digestion for proteome analysis.</a> Proteomics. 8 (23-24), 4862-4872 (2008).</li><li>Park, 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=Informed-Proteomics:+open-source+software+package+for+top-down+proteomics.">Informed-Proteomics: open-source software package for top-down proteomics.</a> Nature Methods. 14 (9), 909-914 (2017).</li><li>Richter, A., Sanford, K. K., Evans, V. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+oxygen+and+culture+media+on+plating+efficiency+of+some+mammalian+tissue+cells.">Influence of oxygen and culture media on plating efficiency of some mammalian tissue cells.</a> Journal of the National Cancer Institute. 49 (6), 1705-1712 (1972).</li><li>Packer, L., Fuehr, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low+oxygen+concentration+extends+the+lifespan+of+cultured+human+diploid+cells.">Low oxygen concentration extends the lifespan of cultured human diploid cells.</a> Nature. 267 (5610), 423-425 (1977).</li><li>Lengner, C. 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=Derivation+of+pre-X+inactivation+human+embryonic+stem+cells+under+physiological+oxygen+concentrations.">Derivation of pre-X inactivation human embryonic stem cells under physiological oxygen concentrations.</a> Cell. 141 (5), 872-883 (2010).</li><li>Sidoli, S., Kulej, K., Garcia, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Why+proteomics+is+not+the+new+genomics+and+the+future+of+mass+spectrometry+in+cell+biology.">Why proteomics is not the new genomics and the future of mass spectrometry in cell biology.</a> Journal of Cell Biology. 216 (1), 21-24 (2017).</li></ol>

The authors declare no conflicts of interest.

Because proteomics is a powerful tool to study the expression of different proteins from a whole cell or subcellular compartments, optimization of the cell lysis protocol and digestion of proteins has been addressed by a number of studies. There are three main classes of methods, which include in-gel digestion (digestion of proteins in polyacrylamide gel matrix)17, digestion in solution18 and filter-aided sample preparation19. This last method, at fi...

Macrophages are innate immune cells involved in a number of physiological functions ranging from responses to infectious pathogens to tissue homeostasis, including removal of apoptotic cells and remodelling of the extracellular matrix1. These cells are characterized by a strong phenotypic plasticity2 that translates into a many possible activation states, which are also called polarizations. The precise molecular description of these various polarizations is a priority in the field of macrophage biology3. It has been proposed to classify these polarizations using the so-called M1/M2 dichotomy, in which M1 represents pro-inflammatory and M2 represents anti-inflammatory macrophages. This model fits well in various pathological situations like acute infections, allergy, and obesity4. However, in chronically inflamed tissues and cancer, it has been demonstrated that this classification is unable to grasp the broad phenotypic repertoire that macrophages present in certain cellular environments5,6,7. The current consensus is that macrophage polarization is better described using a multidimensional model to integrate specific microenvironmental signals8. This conclusion has been confirmed through transcriptomic analysis of human macrophages showing that the M1/M2 model is inefficient in describing the obtained polarizations9.
The study presented aims to provide a protocol to obtain proteomic signatures of various polarizations in human macrophages. We describe how to differentiate human macrophages in environments of various oxygen levels and obtain peptides from the whole macrophage proteome to perform a label-free quantification. This quantification allows the comparison of expression levels of various proteins. As research on stem cells has revealed the importance of oxygen as an environmental key parameter10, we seek to understand how this tissue parameter can influence macrophage polarization in humans. The partial pressure of oxygen has been found to range from 3 to 20% (of total atmospheric pressure) in the human body, where 20% corresponds roughly to what is commonly used in a cell culture incubator (the exact value is around 18.6% while taking the presence of water into account).
Previous work has shown that alveolar differ from interstitial macrophages from functional and morphological point of views11 and that these differences are probably partially due to the different oxygen levels to which they are exposed12. Furthermore, bone marrow-derived macrophages show an increased ability to phagocytize bacteria when exposed to a low oxygen environment12. The opposite effect has been found for THP1-differentiated human macrophages13, but these results support the idea that oxygen is a regulator of macrophage biology and that it is necessary to clarify this role at the molecular level in human macrophages. In a previous study, we have applied a proteomics approach to address these issues. By measuring expression levels for thousands of proteins simultaneously, we highlighted the impact of oxygen on polarization and provided a list of new molecular markers. We were also able to relate these findings to some macrophages functions. Notably, we found that the rate of phagocytosis of apoptotic cells was increased in IL4/IL13-polarized macrophages, which was linked to the upregulation of ALOX15 as revealed by the proteomic analysis14. In the present study, we describe how to perform such an analysis.

<table>
	<tbody>
		<tr>
			<td>Hypoxia Working Station</td>
			<td>Oxford Optronix</td>
			<td>Hypoxylab</td>
			<td></td>
		</tr>
		<tr>
			<td>C6 Flow cytometer</td>
			<td>BD</td>
			<td>Accuri C6</td>
			<td></td>
		</tr>
		<tr>
			<td>Urea</td>
			<td>Agilent Technologies</td>
			<td>5188-6435</td>
			<td></td>
		</tr>
		<tr>
			<td>Formic acid (FA)</td>
			<td>ARISTAR</td>
			<td>450122M</td>
			<td></td>
		</tr>
		<tr>
			<td>R-250 Coomassie blue</td>
			<td>Biorad</td>
			<td>1,610,436</td>
			<td></td>
		</tr>
		<tr>
			<td>Lipopolysaccharide, E.Coli (LPS)</td>
			<td>Calbiochem</td>
			<td>437627</td>
			<td></td>
		</tr>
		<tr>
			<td>2D clean-up kit</td>
			<td>GE Healthcare</td>
			<td>80-6484-51</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI 1640 medium, glutamax supplement</td>
			<td>Gibco</td>
			<td>61870044</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES 1 M</td>
			<td>Gibco</td>
			<td>15630-080</td>
			<td></td>
		</tr>
		<tr>
			<td>MEM Non-Essential Amino Acids (NEAA) Solution 100X</td>
			<td>Gibco</td>
			<td>11140-035</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS) 1X</td>
			<td>Gibco</td>
			<td>14190-094</td>
			<td></td>
		</tr>
		<tr>
			<td>Harvard Apparatus column Reverse C18 micro spin column</td>
			<td>Harvard Apparatus</td>
			<td>74-4601</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA 0.5 M, pH 8.0</td>
			<td>Invitrogen</td>
			<td>AM9260G</td>
			<td></td>
		</tr>
		<tr>
			<td>NuPAGE Bis-Tris 4-12%</td>
			<td>Life Technologies SAS</td>
			<td>NP0321 BOX</td>
			<td></td>
		</tr>
		<tr>
			<td>CD14 Microbeads human</td>
			<td>Miltenyi Biotec</td>
			<td>130-050-201</td>
			<td></td>
		</tr>
		<tr>
			<td>MACS separation column LS</td>
			<td>Miltenyi Biotec</td>
			<td>130-042-401</td>
			<td></td>
		</tr>
		<tr>
			<td>Macrophage colony-stimulating factor (M-CSF)</td>
			<td>Miltenyi Biotec</td>
			<td>130-096-485</td>
			<td></td>
		</tr>
		<tr>
			<td>Interleukin 4 (IL4)</td>
			<td>Miltenyi Biotec</td>
			<td>130-093-917</td>
			<td></td>
		</tr>
		<tr>
			<td>Interleukin 13 (IL13)</td>
			<td>Miltenyi Biotec</td>
			<td>130-112-410</td>
			<td></td>
		</tr>
		<tr>
			<td>Interferon gamma (INF&#947;)</td>
			<td>Miltenyi Biotec</td>
			<td>130-096-482</td>
			<td></td>
		</tr>
		<tr>
			<td>CD14-FITC (clone T&#220;K4)</td>
			<td>Miltenyi Biotec</td>
			<td>130-080-701</td>
			<td></td>
		</tr>
		<tr>
			<td>MACSmix Tube Rotator</td>
			<td>Miltenyi Biotec</td>
			<td>130-090-753</td>
			<td></td>
		</tr>
		<tr>
			<td>Trifluoroacetic Acid (TFA)</td>
			<td>Pierce</td>
			<td>28904</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin/Lys-C Mix</td>
			<td>PROMEGA</td>
			<td>V5073</td>
			<td></td>
		</tr>
		<tr>
			<td>Complete Mini, EDTA-free Protease Inhibitor cocktail</td>
			<td>Roche</td>
			<td>11836170001</td>
			<td></td>
		</tr>
		<tr>
			<td>Density Gradient Solution (Histopaque 1077)</td>
			<td>Sigma Aldrich</td>
			<td>10771-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Accumax</td>
			<td>Sigma Aldrich</td>
			<td>A7089-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Human Serum from human male AB plasma (SAB)</td>
			<td>Sigma Aldrich</td>
			<td>H4522-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin (BSA) solution 30%</td>
			<td>Sigma Aldrich</td>
			<td>A9576-50ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Trisma-base</td>
			<td>Sigma Aldrich</td>
			<td>T1503</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sigma Aldrich</td>
			<td>49767</td>
			<td></td>
		</tr>
		<tr>
			<td>&#946;-Mercaptoethanol</td>
			<td>Sigma Aldrich</td>
			<td>M3148</td>
			<td></td>
		</tr>
		<tr>
			<td>Bromophenol blue</td>
			<td>Sigma Aldrich</td>
			<td>114405</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Dodecyl Sulfate (SDS) 20%</td>
			<td>Sigma Aldrich</td>
			<td>5030</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium bicarbonate</td>
			<td>Sigma Aldrich</td>
			<td>9830</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetonitrile</td>
			<td>Sigma Aldrich</td>
			<td>34888</td>
			<td></td>
		</tr>
		<tr>
			<td>Dithiothreitol</td>
			<td>Sigma Aldrich</td>
			<td>43819</td>
			<td></td>
		</tr>
		<tr>
			<td>Iodoacetamide</td>
			<td>Sigma Aldrich</td>
			<td>57670</td>
			<td></td>
		</tr>
		<tr>
			<td>Thiourea</td>
			<td>Sigma Aldrich</td>
			<td>T8656</td>
			<td></td>
		</tr>
		<tr>
			<td>CHAPS</td>
			<td>Sigma Aldrich</td>
			<td>C9426</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro BCA Assay Kit</td>
			<td>ThermoFisher</td>
			<td>23235</td>
			<td></td>
		</tr>
		<tr>
			<td>5 mL sterile plastic pipette</td>
			<td>VWR</td>
			<td>612-1685</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermomixer C Eppendorf</td>
			<td>VWR</td>
			<td>460-0223</td>
			<td></td>
		</tr>
		<tr>
			<td>Sep-Pak tC18 reverse phase cartridges, 100 mg</td>
			<td>Waters</td>
			<td>WAT036820</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Starting from peripheral blood mononuclear cells (PBMCs) obtained by differential centrifugation, the protocol permits the obtaining of a population of CD14+ monocytes with an assessed purity of more than 98% by flow cytometry (Figure 1). These monocytes are secondarily differentiated toward various polarizations (Figure 2). When a fractionation on gel is chosen, the migration on SDS-page gels is adapted to obtain the ...

Watch this Scientific Journal Video about Proteomic Analysis of Human Macrophage Polarization Under a Low Oxygen Environment at JoVE.com

Proteomic Analysis of Human Macrophage Polarization Under a Low Oxygen Environment

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.

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

So this method can help to answer key questions in the macrophage biology field, such as how to characterize the state of activation under various environment at the protein level. The main advantage of this technique is that it provides the opportunity to obtain differing expression of many proteins in human macrophages using label-free quantification method. Demonstrating the procedure will be Marie Malier and Magali Court from my laboratory.To begin, add 15 milliliters of density gradient cell separation solution into each of two 50 milliliter centrifugation tubes so that the solution can warm to room temperature before receiving the LRSC. This is essential as density depends on temperature. Empty the LRSC into a 50 milliliter centrifugation tube.Add 1x PBS up to 50 milliliters and mix. Then, very slowly, add 25 milliliters of the mix on top of 15 milliliters of equilibrated density gradient solution. Be careful not to mix the phases during this step.The blood must be added on the density gradient solution without any disturbance of this phase. Centrifuge both centrifugation tubes for 25 minutes at 700 G without breaks. At the end of density gradient centrifugation, the layers from the bottom to top are the erythrocytes and granulocytes, forming the pellet, the density gradient solution phase, a layer of PBMCs, and the diluted plasma.With a pipette, pass through the plasma phase without aspirating it. Then, collect the PBMC layer into a new 50 milliliter centrifugation tube. Add up to 50 milliliters of 1x PBS to the PBMCs as a washing setup and centrifuge for 10 minutes at 300 G.Aspirate the supernatant and re-suspend the pellet in 40 milliliters of macrophage medium.After couching the PBMCs in a Malassez chamber, transfer the amount of PBMCs necessary for conducting the experiment to a centrifugation tube. Centrifuge the cells for 10 minutes at 300 G.Aspirate the supernatant and re-suspend the pellet in 80 microliters of the sorting buffer per 10 million PBMCs. Then, add 20 microliters of CD14 microbeads per 10 million PBMCs.Mix well, and incubate for 15 minutes at 4 degrees Celsius under constant agitation. Following incubation, add one milliliter of sorting buffer per 10 million PBMCs as a washing step, and centrifuge as before. Then, aspirate the supernatant and re-suspend the pellet in 500 microliters of sorting buffer per 100 million PBMCs.Now, place a column in the magnetic field of the separator. Prepare the column by rinsing it with three milliliters of sorting buffer. Apply the cell suspension onto the column.Then collect the flow through containing unlabeled cells for subsequent staining, if necessary. Wash the column three times with three milliliters of sorting buffer. Be careful not to dry your column.Then, place a collection tube under the column and remove it from the separator. Following the wash, pipette five milliliters of sorting buffer into the column. Immediately flush out the magnetically-labeled cells by firmly pushing the plunger into the column.Finally, repeat these steps with a new column before plating the monocytes and performing the macrophage polarization as described in the text protocol. Maintain the monocytes and the macrophages in an oxygen-controlled environment to perform hypoxic condition analysis. Use a hypoxia working station in order to maintain cells under the desired oxygen partial pressure during the experiment.When working under low oxygen pressure, it is important to prepare all media and washing buffers under the station, and wait sufficiently to obtain the correct partial pressure in the liquid. Perform cell lysis in a buffer under an adapted hood. Load the protein equivalent of 300, 000 cells for each sample on 4-12%bis-tris acrylamide gels.Control the duration of the electrophoretic migration to allow each protein sample to split into six gel bands as shown here. After fixing and staining as described in the text protocol, excise the protein bands with a clean scalpel. Dice each excised band before placing them into 500 microliter tubes.Now, wash the gel slices three times in 200 microliters of 25 millimolar ammonium bicarbonate for 20 minutes at 37 degrees Celsius, discarding the ammonium bicarbonate between each step. Follow this with one wash in 25 millimolar ammonium bicarbonate and acetonitrile. Then, dehydrate the gel pieces with 200 microliters of 100%acetonitrile for 10 minutes.Incubate each gel piece with 10 millimolar DTT and 25 millimolar ammonium bicarbonate for 45 minutes at 56 degrees Celsius. Then, discard the DTT and incubate the gel piece with 55 millimolar iodoacetamide in 25 millimolar ammonium bicarbonate for 35 minutes in the dark at room temperature. To stop alkylation, discard the used solution and incubate each gel piece with 200 microliters of 10 millimolar DTT in 25 millimolar ammonium bicarbonate for 10 minutes at room temperature.Wash the gel pieces in 200 microliters of 25 millimolar ammonium bicarbonate. Then, dehydrate with 200 microliters of 100%acetonitrile for 10 minutes. Digest the proteins overnight at 37 degrees Celsius with Trypsin/Lys-C Mix according the manufacturer's instructions.Extract the resulting peptides from gel pieces by adding 50 microliters of 50%acetonitrile for 15 minutes in low-absorption tubes. After adding 50 microliters of 5%formic acid for 15 minutes, add 50 microliters of 100%acetonitrile for 15 minutes. Pull and dry each fraction in low-absorption tubes to limit absorption of peptides and sample loss.Store the samples at 80 degrees Celsius until further analysis as detailed in the text protocol. Shown here is the representative purity assessed by flow cytometry following magnetic bead selection of CD14 positive monocytes. Phase contrast imaging of differentiated human macrophages show heterogeneity of obtained morphologies for two different polarizations after nine days of culture.An example of an off-gel digestion using silver-stained SDS page gels is shown. Evaluation of protein from cell lysis and after in-solution digestion shows the absence of degradation during lysis and the efficiency of the digestion. Shown here is an example of a collision-induced dissociation spectrum of a peptide found at mass-to-charge ratio of 597.29 on the MS spectrum with an electric charge of positive two.From this spectrum, the corresponding sequence was determined. The final result after analysis is a heat map representing the hierarchical clustering of all polarization states using differentially-expressed proteins. Analysis reveals a cluster of proteins over-expressed in all polarizations in the 3%oxygen condition.While attempting this procedure, it is important to remember that you have to decide first what kind of fractionation you will perform on new samples to adapt your protocol accordingly. The proteomic approach using this work is complementary to genomic approaches that have been used during the last years in the field of the macrophage biology polarization studies. After its development, this technique paves the way for researcher in the field of immunology to explore the various states of activation of immune cells in humans and also in other mammals.Don't forget that working with DTT could be hazardous so you need to work under an adapted hood to do this procedure.

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Research

JoVE Journal

Biochemistry

7.9K 조회수.  Team Mechanobiology, Immunity and Cancer, Institute for Advanced Biosciences, INSERM U1209, CNRS UMR5309. 따라서 이 방법은 단백질 수준에서 다양한 환경에서 활성화 상태를 특성화하는 방법과 같은 대식세포 생물학 분야의 주요 질문에 답하는 데 도움이 될 수 있습니다. 이 기술의 주요 장점은 라벨이 없는 정량화 방법을 사용하여 인간 대식세포에서 많은 단백질의 다른 발현을 얻을 수 있는 기회를 제공한다는 것입니다. 절차를 시연하는 것은 내 실험실에서 마리 말리어와 마갈...