We would like to thank the Flow Cytometry Core Facility at The Pennsylvania State University Millennium Science Complex.

<ol>
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Authors have no conflict of interests to disclose.

Diet-induced metabolic disorder models that mimic co-morbidities such as atherosclerosis, simple steatosis, steatohepatitis and type 2 diabetes are extensively used to better understand the underlying molecular mechanisms of disease progression. Collagenase dependent digestion is often used to dissociate tissues to liberate cells from the extracellular matrix (ECM)16,27. Enzymes such as collagenase disrupt collagen which provides structural support for neighborin...

Mouse models have been extensively used to study the dynamics of human diseases. Proper isolation of tissue resident cells from mice in a diseased state can provide a platform for understanding the molecular and cellular contributions to the pathogenesis of a disease1. One disorder that is of critical importance is obesity. The incidence of obesity continues to rise worldwide in parallel with insulin resistance and type 2 diabetes mellitus, cardiovascular disease, and fatty liver disease2,3. Excessive nutrient consumption is further skewed by decreased physical activity triggering altered signals emanating from adipose tissue, which can alter the cellular milieu of other peripheral tissues such as the aorta and liver4. Such disruption of metabolic homeostasis results in a chronic low grade systemic inflammation5.
Classical activation of macrophages resident to the aorta and liver as well as their recruitment to white adipose tissue (WAT) has been shown to not only initiate dysregulation of metabolic signals but also sustain inflammation6,7. The phenotypic and functional heterogeneity of macrophages is strongly associated with the pathogenesis of obesity related co-morbidities7. The dynamic plasticity in macrophage polarization allows for these cells to exhibit a range of activated phenotypes that coordinate the progression and resolution of inflammation8. While classically activated (M1) macrophages are implicated in the propagation of inflammation, alternatively activated (M2) macrophages have been associated with resolution and tissue repair9,10.
As the body undergoes metabolic stress, white adipose tissue abnormally accumulates. The expanded adipose tissue attracts and retains inflammatory cells that profoundly alter normal adipocyte function to promote insulin resistance, hyperglycemia and ultimately type 2 diabetes mellitus, insulin resistance or hyperglycemia11,12. In parallel, white adipose tissue remodels in response to inflammatory signals released by infiltrated classically activated (M1) adipose tissue macrophages (ATMs)13,14. This multi-cellular organ exerts a cascade of signals that derails the normal function of other body organs such as the aorta and liver4.
The liver is a metabolic powerhouse that adapts in response to stimuli originating from nearby dysregulated WAT15. Hepatic macrophages or Kupffer cells, in response to metabolic changes, secrete inflammatory cytokines that transform both parenchymal and non-parenchymal cell phenotype and promote tissue remodeling. Hepatic lipid accumulation, inflammation, excessive extracellular matrix deposits, necrosis and eventual function loss follows the inflammatory insults contributing to the wide spectrum of liver damage associated with non-alcoholic fatty liver disease16,17,18.
In parallel to compromised WAT and liver function, large arteries accumulate lipids within the arterial wall as the body undergoes chronic metabolic stress19. Arterial lipid accumulation triggers the secretion of chemokines by activated endothelial cells and subsequent recruitment of monocytes20. Once recruited, monocytes proliferate, differentiate, ingest lipoproteins and become foam cells. Atherogenesis is initiated and sustained by the pro-inflammatory activity of recruited and tissue resident lipid-laden macrophages. Succumbing to the extracellular and intracellular stress signals relayed in this atherogenic microenvironment, these macrophages then engage in an apoptotic signaling cascade. As these foam cells die, they contribute their lipid filled contents to the necrotic core of the lesion, which then leads to plaque rupture, myocardial infarction, and stroke.
Collectively, the heterogeneity of macrophage phenotypes in part orchestrates the obesity induced by inflammatory changes observed in dysregulated tissues such as WAT, liver and aorta8,21. Characterization of recruited and tissue resident macrophages could provide insight into potential molecular targets that manipulate macrophage phenotype1. To effectively characterize macrophages from obesity-induced inflamed tissues, a single-cell suspension can be obtained through enzymatic digestion. Such dissociation protocols must be effective in sufficiently degrading connective tissue while minimizing immune cell death and providing optimal cell yield. The enzyme mixture is dependent on the type of tissue and its structural make up. Resilient tissues such as the aorta requires stronger enzymatic activity, as compared to the liver and WAT, to achieve tissue dissociation. From the single cell suspension, tissue resident macrophages can be unambiguously characterized or isolated for further downstream analyses such as transcriptional profiling.
Here a tissue-specific protocol is described that uses collagenase-dependent tissue digestion and polychromatic flow cytometry to effectively isolate and characterize tissue-resident macrophages obtained from traditional diet induced obesity, atherosclerosis, simple steatosis and steatohepatitis mouse models. Simultaneous staining of cell surface markers with antibodies against leukocyte- (CD45 and/or CD11b) and macrophage- (F4/80) specific antigens is often used to identify macrophage populations22. Fluorescence-activated cell sorting (FACS) is a powerful strategy used to sort these identified populations at high purity. The sorted population can then be evaluated for phenotype specific gene profiles using downstream molecular analysis (such as quantitative real time polymerase chain reaction)23. Although standard flow cytometry and flow cytometry-based cell sorting are powerful tools in distinguishing macrophages within a vastly heterogeneous cell suspension, the former protocols must be optimized to ensure successful output. In this study, protocols that effectively isolate and characterize viable tissue specific macrophages are described; more importantly, this study provides crucial insight into technical issues that often arise, as well as proactive and trouble-shooting strategies to prevent and/or resolve them.

<table border="0" cellpadding="0" cellspacing="0" width="940">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">26G x 5/8 in Needles</td>
			<td style="width:151px;">BD</td>
			<td style="width:119px;">305115</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:321px;">23G x 0.75 in needle x 12 in. tubing Blood Collection Set</td>
			<td style="width:151px;">BD</td>
			<td style="width:119px;">367297</td>
			<td style="width:349px;">Used for cannulation of subhepatic IVC during liver perfusion</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">21G 1 1/2 in. Needles</td>
			<td style="width:151px;">BD</td>
			<td style="width:119px;">305156</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">1mL syringe with rubber stops</td>
			<td style="width:151px;">BD</td>
			<td style="width:119px;">309659</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">10mL Syringes</td>
			<td style="width:151px;">BD</td>
			<td style="width:119px;">309604</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">1mL Syringe</td>
			<td style="width:151px;">BD</td>
			<td style="width:119px;">309659</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">F4/80 PE</td>
			<td style="width:151px;">Biolegend</td>
			<td style="width:119px;">123110</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">CD11c PE/Cy7</td>
			<td style="width:151px;">Biolegend</td>
			<td style="width:119px;">117318</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">CD11b PE/Cy5</td>
			<td style="width:151px;">eBioscience</td>
			<td style="width:119px;">15-0112-81</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Anti-mouse CD16/32 Fc Block&#160;</td>
			<td style="width:151px;">Biolegend</td>
			<td style="width:119px;">101320</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">CD45 Pacific Blue</td>
			<td style="width:151px;">Biolegend</td>
			<td style="width:119px;">103126</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">PE Rat IgG2a</td>
			<td style="width:151px;">Biolegend</td>
			<td style="width:119px;">400508</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">PE/Cy7 Armenian Hamster IgG</td>
			<td style="width:151px;">Biolegend</td>
			<td style="width:119px;">400922</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">PE/Cy5 Rat IgG2b</td>
			<td style="width:151px;">Biolegend</td>
			<td style="width:119px;">400610</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Pacific Blue Rat IgG2c</td>
			<td style="width:151px;">Biolegend</td>
			<td style="width:119px;">400717</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Dulbecco&#8217;s Modified Eagle Medium (DMEM)&#160;</td>
			<td style="width:151px;">Cellgro</td>
			<td style="width:119px;">15-017-CV</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">1X Phosphate Buffered Saline (PBS)</td>
			<td style="width:151px;">Cellgro</td>
			<td style="width:119px;">21-031-CV</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">70 micron cell strainers</td>
			<td style="width:151px;">Corning, Inc.</td>
			<td style="width:119px;">352350</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">&#160;1.7 mL microcentrifuge tube&#160;</td>
			<td style="width:151px;">Denville</td>
			<td style="width:119px;">C2170</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:321px;">Paraformaldehyde Aqueous Solution -16X</td>
			<td style="width:151px;">Electron Microscopy Sciences</td>
			<td style="width:119px;">CAS #30525-89-4</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:321px;">Micro Dissecting Scissors, 3.5 inch, Straight, 23mm, Sharp&#160;</td>
			<td>Stoelting</td>
			<td>52132-10P</td>
			<td style="width:349px;">Used for general dissecting purposes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Micro Forceps, 4in, full curve, 0.8mm</td>
			<td>Stoelting</td>
			<td>52102-37P&#160;</td>
			<td style="width:349px;">Used for general dissecting purposes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Spring dissection scissors &#8211; 3 mm Cutting edge&#160;</td>
			<td style="width:151px;">Fine Science Tool</td>
			<td style="width:119px;">15000-10</td>
			<td style="width:349px;">Used for aorta dissection Steps 1.3.3.17 to 1.3.3.28</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Curved 0.07 x 0.04 mm Tip Forceps&#160;</td>
			<td style="width:151px;">Fine Science Tool</td>
			<td style="width:119px;">11297-10</td>
			<td style="width:349px;">Used for aorta dissection Steps 1.3.3.17 to 1.3.3.28</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Hemostatic Forceps (Curved)</td>
			<td style="width:151px;">Fine Science Tool</td>
			<td style="width:119px;">13021-12</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Heparin Sodium Salt</td>
			<td style="width:151px;">Fischer Scientific</td>
			<td style="width:119px;">9041-08-1</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:321px;">35mm Cell Culture/Petri Dishes</td>
			<td style="width:151px;">Fischer Scientific</td>
			<td style="width:119px;">12-565-90</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Polystyrene Petri Dishes (10 cm) w/lid</td>
			<td style="width:151px;">Fischer Scientific</td>
			<td style="width:119px;">08-757-100D</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">15mL Conical Centrifuge Tubes (Polypropylene)</td>
			<td style="width:151px;">Fischer Scientific</td>
			<td style="width:119px;">14-959-53A</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">50mL Conical Centrifuge Tubes&#160;(Polypropylene)</td>
			<td style="width:151px;">Fischer Scientific</td>
			<td style="width:119px;">14-432-22</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">5mL Round-Bottom Polystyrene Tubes&#160;</td>
			<td style="width:151px;">Fischer Scientific</td>
			<td style="width:119px;">14-959-5</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Fetal Bovine Serum</td>
			<td style="width:151px;">Gemini Bio-Products</td>
			<td style="width:119px;">100-106</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:321px;">Ethanol (Stock Ethyl Alcohol Denatured, Anyhydrous)</td>
			<td style="width:151px;">Millipore</td>
			<td style="width:119px;">EX0285-1</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Bovine Serum Albumin</td>
			<td style="width:151px;">Rockland</td>
			<td style="width:119px;">BSA-50</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">HEPES</td>
			<td style="width:151px;">Sigma-Aldrich</td>
			<td style="width:119px;">H3375</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Collagenase Type II</td>
			<td style="width:151px;">Sigma-Aldrich</td>
			<td style="width:119px;">C6885</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Collagenasse Type XI</td>
			<td style="width:151px;">Sigma-Aldrich</td>
			<td style="width:119px;">C7657</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Hyaluronidase Type I</td>
			<td style="width:151px;">Sigma-Aldrich</td>
			<td style="width:119px;">H3506</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">DNAse</td>
			<td style="width:151px;">Sigma-Aldrich</td>
			<td style="width:119px;">DN25</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Collagenase Type I</td>
			<td style="width:151px;">Sigma-Aldrich</td>
			<td style="width:119px;">C0130</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">NaOH</td>
			<td style="width:151px;">Sigma Aldrich</td>
			<td style="width:119px;">1310-73-2&#160;</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:321px;">CaCl2</td>
			<td style="width:151px;">Sigma Aldrich</td>
			<td style="width:119px;">449709-10G</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">500mL beaker&#160;</td>
			<td style="width:151px;">Sigma Aldrich</td>
			<td style="width:119px;">02-540M</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">4 cm Hemostatic clamp</td>
			<td style="width:151px;">Stoelting</td>
			<td style="width:119px;">52120-40</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Toothed forceps</td>
			<td style="width:151px;">Stoelting</td>
			<td style="width:119px;">52104-33P</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">50 micron Disposable filters</td>
			<td style="width:151px;">Systemex</td>
			<td style="width:119px;">04-0042-2317</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:321px;">Collagenase Type IV</td>
			<td style="width:151px;">ThermoFischer Scientific</td>
			<td style="width:119px;">17104019</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:321px;">Ammonium Chloride Potassium (ACK)</td>
			<td style="width:151px;">ThermoFischer Scientific&#160;</td>
			<td style="width:119px;">A1049201</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Razors (0.22 mm (0.009&#34;))</td>
			<td style="width:151px;">VWR International</td>
			<td style="width:119px;">55411-050</td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Texas Red Live/Dead stain</td>
			<td style="width:151px;"></td>
			<td style="width:119px;"></td>
			<td style="width:349px;">Red viability stain (in Figure 1A)</td>
		</tr>
	</tbody>
</table>

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.

When using apolipoprotein E deficient (ApoE KO) C57BL/6 (BL6) mice maintained on a high fat high cholesterol diet (HCHFD or HCD) for 18 weeks, 1 x 104 - 2 x 104 CD45+F4/80+ aortic macrophages can be isolated when two samples are pooled. Livers dissected from HFHCD-fed ApoE KO mice, produced greater than 5 x 105 sorted Kupffer cells (which depends on available sorting time). When using high fat diet (HFD) fed wild type (WT) C57BL/6 mic...

Watch this Scientific Journal Video about Isolation, Characterization, and Purification of Macrophages from Tissues Affected by Obesity-related Inflammation at JoVE.com

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

isolation-characterization-purification-macrophages-from-tissues

Research

JoVE Journal

Immunology and Infection

25.0K Views.  The Pennsylvania State University. 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.

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

Isolation and Characterization of Dendritic Cells and Macrophages from the Mouse Intestine

Within the intestine reside unique populations of innate and adaptive immune cells that are involved in promoting tolerance towards commensal flora and food antigens while concomitantly remaining poised to mount inflammatory responses toward invasive pathogens1,2. Antigen presenting cells, particularly DCs and macrophages, play critical roles in maintaining intestinal immune homeostasis via their ability to sense and appropriately respond to the microbiota3-14. Efficient isolation of intestinal DCs and macrophages is a critical step in characterizing the phenotype and function of these cells. While many effective methods of isolating intestinal immune cells, including DCs and macrophages, have been described6,10,15-24, many rely upon long digestions times that may negatively influence cell surface antigen expression, cell viability, and/or cell yield. Here, we detail a methodology for the rapid isolation of large numbers of viable, intestinal DCs and macrophages. Phenotypic characterization of intestinal DCs and macrophages is carried out by directly staining isolated intestinal cells with specific fluorescence-labeled monoclonal antibodies for multi-color flow cytometric analysis. Furthermore, highly pure DC and macrophage populations are isolated for functional studies utilizing CD11c and CD11b magnetic-activated cell sorting beads followed by cell sorting.

Here, we detail a methodology for the rapid isolation of mouse intestinal dendritic cells (DCs) and macrophages. Phenotypic characterization of intestinal DCs and macrophages is performed using multi-color flow cytometric analysis while magnetic bead enrichment followed by cell sorting is used to yield highly pure populations for functional studies.

Within the intestine reside unique populations of innate and adaptive immune cells that are involved in promoting tolerance towards commensal flora and ...

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.

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

Isolation of Leukocytes from the Murine Tissues at the Maternal-Fetal Interface

Immune tolerance in pregnancy requires that the immune system of the mother undergoes distinctive changes in order to accept and nurture the developing fetus. This tolerance is initiated during coitus, established during fecundation and implantation, and maintained throughout pregnancy. Active cellular and molecular mediators of maternal-fetal tolerance are enriched at the site of contact between fetal and maternal tissues, known as the maternal-fetal interface, which includes the placenta and the uterine and decidual tissues. This interface is comprised of stromal cells and infiltrating leukocytes, and their abundance and phenotypic characteristics change over the course of pregnancy. Infiltrating leukocytes at the maternal-fetal interface include neutrophils, macrophages, dendritic cells, mast cells, T cells, B cells, NK cells, and NKT cells that together create the local micro-environment that sustains pregnancy. An imbalance among these cells or any inappropriate alteration in their phenotypes is considered a mechanism of disease in pregnancy. Therefore, the study of leukocytes that infiltrate the maternal-fetal interface is essential in order to elucidate the immune mechanisms that lead to pregnancy-related complications. Described herein is a protocol that uses a combination of gentle mechanical dissociation followed by a robust enzymatic disaggregation with a proteolytic and collagenolytic enzymatic cocktail to isolate the infiltrating leukocytes from the murine tissues at the maternal-fetal interface. This protocol allows for the isolation of high numbers of viable leukocytes (&#62;70%) with sufficiently conserved antigenic and functional properties. Isolated leukocytes can then be analyzed by several techniques, including immunophenotyping, cell sorting, imaging, immunoblotting, mRNA expression, cell culture, and in vitro functional assays such as mixed leukocyte reactions, proliferation, or cytotoxicity assays.

Described herein is a protocol to isolate and analyze the infiltrating leukocytes of tissues at the maternal-fetal interface (uterus, decidua, and placenta) of mice. This protocol maintains the integrity of most cell surface markers and yields enough viable cells for downstream applications including flow cytometry analysis.

Immune tolerance in pregnancy requires that the immune system of the mother undergoes distinctive changes in order to accept and nurture the developing ...

An Optimized Method for Isolating and Expanding Invariant Natural Killer T Cells from Mouse Spleen

The ability to rapidly secrete cytokines upon stimulation is a functional characteristic of the invariant natural killer T (iNKT) cell lineage. iNKT cells are therefore characterized as an innate T cell population capable of activating and steering adaptive immune responses. The development of improved techniques for the culture and expansion of murine iNKT cells facilitates the study of iNKT cell biology in in vitro and in vivo model systems. Here we describe an optimized procedure for the isolation and expansion of murine splenic iNKT cells.
Spleens from C57Bl/6 mice are removed, dissected and strained and the resulting cellular suspension is layered over density gradient media. Following centrifugation, splenic mononuclear cells (MNCs) are collected and CD5-positive (CD5+) lymphocytes are enriched for using magnetic beads. iNKT cells within the CD5+ fraction are subsequently stained with &#945;GalCer-loaded CD1d tetramer and purified by fluorescence activated cell sorting (FACS). FACS sorted iNKT cells are then initially cultured in vitro using a combination of recombinant murine cytokines and plate-bound T cell receptor (TCR) stimuli before being expanded in the presence of murine recombinant IL-7. Using this technique, approximately 108 iNKT cells can be generated within 18-20 days of culture, after which they can be used for functional assays in vitro, or for in vivo transfer experiments in mice.

Here we present an adapted protocol that can be used to generate a large number of murine invariant natural killer T cells from mouse spleen. The protocol outlines an approach by which splenic iNKT cells can be enriched for, isolated and expanded in vitro using a limited number of animals and reagents.

The ability to rapidly secrete cytokines upon stimulation is a functional characteristic of the invariant natural killer T (iNKT) cell lineage. iNKT cells ...

Isolation, Characterization and Functional Examination of the Gingival Immune Cell Network

Immune cell networks in tissues play a vital role in mediating local immunity and maintaining tissue homeostasis, yet little is known of the resident immune cell populations in the oral mucosa and gingiva. We have established a technique for the isolation and study of immune cells from murine gingival tissues, an area of constant microbial exposure and a vulnerable site to a common inflammatory disease, periodontitis. Our protocol allows for a detailed phenotypic characterization of the immune cell populations resident in the gingiva, even at steady state. Our procedure also yields sufficient cells with high viability for use in functional studies, such as the assessment of cytokine secretion ex vivo. This combination of phenotypic and functional characterization of the gingival immune cell network should aid towards investigating the mechanisms involved in oral immunity and periodontal homeostasis, but will also advance our understanding of the mechanisms involved in local immunopathology.

We have established a technique for the isolation, phenotypic characterization and functional analysis of immune cells from murine gingiva.

Immune cell networks in tissues play a vital role in mediating local immunity and maintaining tissue homeostasis, yet little is known of the resident ...

Functional Characterization of Regulatory Macrophages That Inhibit Graft-reactive Immunity

Macrophage accumulation in transplanted organs has long been recognized as a feature of allograft rejection1. Immunogenic monocytes infiltrate the allograft early after transplantation, mount a graft reactive response against the transplanted organ, and initiate organ rejection2. Recent data suggest that suppressive macrophages facilitate successful long-term transplantation3 and are required for the induction of transplantation tolerance4. This suggests a multidimensional concept of macrophage ontogeny, activation, and function, which demands a new roadmap for the isolation and analysis of macrophage function5. Due to the plasticity of macrophages, it is necessary to provide a methodology to isolate and characterize macrophages, depending on the tissue environment, and to define their functions according to different scenarios. Here, we describe a protocol for immune characterization of graft-infiltrating macrophages and the methods we used to functionally evaluate their capacity to inhibit CD8+ T proliferation and to promote CD4+Foxp3+ Treg expansion in vitro.

Macrophages are plastic cells of the hematopoietic system that have a crucial role in protective immunity and homeostasis. In this report, we describe optimized in vitro techniques to phenotypically and functionally characterize graft-infiltrating regulatory macrophages that accumulate in the transplanted organ under tolerogenic conditions.

Macrophage accumulation in transplanted organs has long been recognized as a feature of allograft rejection1. Immunogenic monocytes infiltrate the ...

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 ...

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

Salmonella typhimurium is a facultative intracellular bacterium that causes gastroenteritis in humans. After invasion of the lamina propria, S. typhimurium bacteria are quickly detected and phagocytized by macrophages, and contained in vesicles known as phagosomes in order to be degraded. Isolation of S. typhimurium-containing phagosomes have been widely used to study how S. typhimurium infection alters the process of phagosome maturation to prevent bacterial degradation. Classically, the isolation of bacteria-containing phagosomes has been performed by sucrose gradient centrifugation. However, this process is time-consuming, and requires specialized equipment and a certain degree of dexterity. Described here is a simple and quick method for the isolation of S. typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin-streptavidin-conjugated magnetic beads. Phagosomes obtained by this method can be suspended in any buffer of choice, allowing the utilization of isolated phagosomes for a broad range of assays, such as protein, metabolite, and lipid analysis. In summary, this method for the isolation of S. typhimurium-containing phagosomes is specific, efficient, rapid, requires minimum equipment, and is more versatile than the classical method of isolation by sucrose gradient-ultracentrifugation.

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

We describe here a simple and quick method for the isolation of Salmonella typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin and streptavidin.

Salmonella typhimurium is a facultative intracellular bacterium that causes gastroenteritis in humans. After invasion of the lamina propria, S. ...

Isolation and Characterization of Extracellular Vesicles from Adult Schistosoma japonicum

Extracellular vesicles (EVs) are membranous vesicles released by a variety of cells into the extracellular microenvironment. EVs represent a population of heterogeneous vesicles, whose size range between 40 and 1,000 nm. Accumulated evidence indicated that EVs play important regulatory roles in pathogen-host interactions. A deep understanding of schistosome EVs should provide insights into the mechanisms underlying schistosome-host interactions, enabling development of novel strategies against schistosomiasis. Here, we aim to further study EVs functions in schistosomes by presenting a protocol for the isolation and characterization of EVs from adult Schistosoma japonicum (S. japonicum). EVs were isolated from in vitro culture medium using centrifugation combined with a commercial exosome isolation kit. The isolated S. japonicum EVs (SjEVs) typically possess a diameter of 100 - 400 nm, and are characterized by transmission electronic microscopy and western blotting. The usage of PKH67 dye-labeled SjEVs has demonstrated that SjEVs are internalized by the recipient cells. Overall, our protocol provides an alternative method for isolating EVs from adult schistosomes; the isolated SjEVs may be suitable for functional analysis.

Isolation and Characterization of Extracellular Vesicles from Adult Schistosoma japonicum

Here, we present a protocol to describe extracellular vesicles (EVs) isolation in in vitro cultured medium from adult Schistosoma japonicum.

Extracellular vesicles (EVs) are membranous vesicles released by a variety of cells into the extracellular microenvironment. EVs represent a population of ...

Experimental Analysis of Apoptotic Thymocyte Engulfment by Macrophages

Cell apoptosis is a natural process and plays a critical role in embryonic development, homeostatic regulation, immune tolerance induction, and resolution of inflammation. Accumulation of apoptotic debris in the body may trigger chronic inflammatory responses that lead to systemic autoimmune diseases over time. Impaired apoptotic cell clearance has been implicated in a variety of autoimmune diseases. Apoptotic clearance is a complex process rarely detected under physiological conditions. It involves abundant surface receptors and signaling molecules. Studying the process of apoptotic cell clearance provides insightful molecular mechanisms and subsequent biological responses, which may lead to the development of new therapeutics. Here, we describe protocols for the induction of apoptotic thymocytes, the preparation of peritoneal macrophages, and the analysis of apoptotic cell clearance by flow cytometry and microscopy. All cells will undergo apoptosis at a certain stage, and many residential and circulating cells can uptake apoptotic debris. Therefore, the protocol described here can be used in many applications to characterize apoptotic cell binding and ingestion by many other cell types.

Here, we present a protocol to prepare apoptotic thymocytes and peritoneal macrophages and analyze the efficiency of efferocytosis and the specific inhibitor-mediated blocking of apoptotic thymocytes engulfment. This protocol has a broad application in cell-mediated clearance of other particles including artificial beads and bacteria.

Cell apoptosis is a natural process and plays a critical role in embryonic development, homeostatic regulation, immune tolerance induction, and resolution ...