This work was supported by grants from FIS/FEDER (Programa Miguel Servet: CP10/00479, PI13/00802 and PI14/00883), Spanish Society of Atherosclerosis, Spanish Society of Nephrology and Fundaci&#242;n Renal I&#241;igo Alvarez de Toledo (FRIAT) to Juan Antonio Moreno. FIS/FEDER funds PI14/00386 and Instituto Reina Sof&#236;a de Investigaci&#242;n Nefrol&#242;gica to Jes&#250;s Egido. Fundaci&#242;n Conchita Rabago to Melania Guerrero Hue. Fundaci&#242;n Renal I&#241;igo Alvarez de Toledo (FRIAT) to Alfonso Rubio Navarro.

This protocol was approved by local Institutional Animal Care and Use Committees following the Directive 2010/63/EU of the European Parliament and the National Guideline 53/2013.
1. Preparation of Reagents and Solutions
<ol>
	<li>Prepare all the reagents and solutions under sterile conditions and use under a laminar flow hood. Keep solutions at 4 &#176;C.</li>
	<li>Prepare staining buffer (2% Fetal Bovine Serum (FBS) in 1x Dulbecco&#39;s PBS).</li>
	<li>Prepare collagenase solution by adding 0.5 mg of collagenase to each ml of saline.</li>
	<li>Prepare anesthesia solution of ketamine/xylazine (2:1 v/v).</li>
</ol>
2. Kidney Perfusion and Extraction
<ol>
	<li>Anesthetize rats by intraperitoneal injection of ketamine/xylazine (75 mg/12 mg/kg weight). Carefully pinch a small fold of skin, to check that the animal is sufficiently anesthetized. Then, cover eyes with vet ointment to prevent dryness while under anesthesia. Note: 4-month-old Wistar rats are used in this assay.</li>
	<li>Once the rat is totally anesthetized, place it on a surgical table in a supine position.</li>
	<li>Apply 70% ethanol to the abdomen.</li>
	<li>Make a central incision through the abdominal skin and peritoneum, from the pubis to the rib cage, to expose the pleural and abdominal cavities.</li>
	<li>Inject saline solution (0.9%) into the abdominal aorta to perfuse kidneys using a perfusion system until all blood is removed from kidneys. Cut the aorta at the abdominal level to help release the blood.</li>
	<li>Remove both kidneys from the rat by cutting from the renal hilum (renal vein, artery and ureter). To decapsulate the kidney, press the edge of the kidney using fingers, carefully separating the capsule11.</li>
	<li>Place the kidney into Hanks&#39; balanced salt solution.</li>
</ol>
3. Kidney Digestion and Cell Suspension
<ol>
	<li>Cut half of a kidney with scissors into small pieces and put the pieces into a 1.5 ml tube. 
	Note: All the following concentrations are calculated for 1 sample (1/2 rat&#39;s kidney).</li>
	<li>Add 1 ml of the collagenase solution and incubate at 37 &#176;C for 30 min. Mix by inversion every 5 min to make sure that the collagenase solution accesses the entire tissue.</li>
	<li>Collect the solution and pass it through a strainer (40 &#181;m) with the aid of a plunger, and resuspend it in 10 ml of staining buffer.</li>
	<li>Centrifuge at 400 x g for 15 min.</li>
	<li>Re-suspend the pellet in 1 ml ACK (Ammonium-Chloride-Potassium) Lysing Buffer. After 1 min 30 sec at room temperature, add 10 ml of staining buffer to stop the reaction.</li>
	<li>Centrifuge at 400 x g for 10 min.</li>
	<li>Re-suspend the pellet in an adequate volume of staining buffer (1 ml) and filter the cell suspension using a strainer (30 &#181;m).</li>
	<li>Count the number of cells using trypan blue exclusion on a hemocytometer and add 2 million cells to a 1.5 ml tube for staining.</li>
</ol>
4. Cell Staining and Flow Cytometry Analysis
<ol>
	<li>Centrifuge cells at 100 x g for 5 min.</li>
	<li>Re-suspend the pellet in 100 &#181;l of rat serum (diluted 1:100) for 10 min at 4 &#176;C to block Fc receptors.</li>
	<li>Wash by adding 1 ml of staining buffer and centrifuge 100 x g for 5 min.</li>
	<li>Mix the antibodies for cell surface staining in 100 &#181;l of staining buffer for each condition: CD45 APC-Cy7 (1:100), CD163 A647(4:100) and solution to detect live cells (3:1,000).</li>
	<li>Re-suspend the cell pellet in the antibody mix for 20 min at 4 &#176;C in the dark.</li>
	<li>Wash by adding 1 ml of staining buffer and centrifuge at 100 x g for 5 min. Repeat this step.</li>
	<li>Add 600 &#181;l of Fixation/Permeabilization solution for 20 min at 4 &#176;C in the dark.</li>
	<li>Wash 2 times with 1 ml Permeabilization/Wash buffer and centrifuge at 170 x g for 5 min.</li>
	<li>Add the CD68 FITC antibody (35:1,000) for the intracellular staining to 100 &#181;l of Permeabilization/Wash buffer for each condition.</li>
	<li>Re-suspend the pellet in the CD68-antibody solution and incubate 50 min at 4 &#176;C in the dark.</li>
	<li>Wash with 1 ml Permeabilization/Wash buffer and centrifuge at 170 x g for 5 min.</li>
	<li>Re-suspend the pellet in 100 &#181;l of Permeabilization/Wash buffer, add CD86PE antibody (35:1,000) and incubate for 20 min at 4 &#176;C in the dark.</li>
	<li>Wash by adding 1 ml of Permeabilization/Wash buffer and centrifuge at 100 x g for 5 min.</li>
	<li>Re-suspend the pellet in 100 &#181;l of Permeabilization/Wash buffer and pass it to a flow cytometry tube.</li>
	<li>Analyze samples by flow cytometry. Determine CD45 staining in live cells gated in the Side-scattered light/forward-scattered light (SSC/FSC) window. In a second step, analyze CD86 and CD163 expression in CD68+ cells.</li>
</ol>

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H., 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+depletion+ameliorates+glycerol-induced+acute+kidney+injury+in+mice.">Macrophage depletion ameliorates glycerol-induced acute kidney injury in mice.</a> Nephron Exp. Nephrol. 128, 21-29 (2014).</li><li>Belliere, 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=Specific+macrophage+subtypes+influence+the+progression+of+rhabdomyolysis-induced+kidney+injury.">Specific macrophage subtypes influence the progression of rhabdomyolysis-induced kidney injury.</a> J. Am. Soc. Nephrol. 26, 1363-1377 (2015).</li><li>Kinsey, G. 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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=Macrophage+activation+and+polarization:+nomenclature+and+experimental+guidelines.">Macrophage activation and polarization: nomenclature and experimental guidelines.</a> Immunity. 41, 14-20 (2014).</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>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> Nat. Rev. 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The authors have nothing to disclose.

Macrophages are heterogeneous cells that play an important role in different inflammatory diseases, including renal disorders. There is increasing interest in the characterization of macrophages subsets in renal disease because each macrophage subpopulation contributes in a different way to the development of kidney injury, as reported in glomerulonephritis, diabetic nephropathy and kidney cancer14-16. In the early stages of acute renal injury, a predominance of M1 macrophages is observed, promoting tubular ne...

Renal disease is a global health problem, with increased prevalence, and associated with elevated morbidity and mortality1. One of the most important mechanisms involved in the progression and development of renal injury is inflammation, mainly triggered by macrophages. Macrophages play a pivotal role in many inflammatory diseases, including renal disorders2. Thus, an elevated presence of infiltrating macrophages has been reported in biopsies from patients with acute kidney injury (AKI) or chronic kidney disease (CKD)3,4. Recent studies suggest that the long-term outcome of renal disease could be controlled by macrophages5,6. In response to the local microenvironment, macrophages may differentiate into different phenotypes that play diverse biological functions7. Two well differentiated macrophage phenotypes have been established: classically activated macrophages (M1 macrophages) and alternatively activated macrophages (M2)8. M1 macrophages promote inflammation, whereas M2 macrophages have an anti-inflammatory role and are involved in tissue repair9. Therefore, a better knowledge of macrophage heterogeneity is necessary to understand their regulation and contribution to renal pathology and develop novel therapeutic approaches. 
Both, murine and rats models have been widely used to understand the molecular and cellular mechanism involved in renal injury10. However, there are substantial differences in the diverse markers used to identify macrophages phenotypes between these rodents. Hence, several murine markers, such as F4/80 or Ly6C are not used in rats, thus limiting the extrapolation of findings between these species. Moreover, there is a limited number of markers describing macrophage phenotypes in rats, explaining the scarce studies analyzing macrophage heterogeneity in these animals as compared with mice. Therefore, new strategies for macrophage subset characterization are necessary to understand the role of macrophages in renal disease models in rats. 
This manuscript describes a protocol for the phenotypic and quantitative analysis of macrophages from rat kidneys by flow cytometry. This technique can be further followed by several assays, including cell sorting and mRNA or protein expression studies to allow in-depth characterization of the role of macrophages in renal disease.

<table><tbody><tr><td>Laminar flow hood</td><td>Faster</td><td></td><td>Or equivalent equipment</td></tr><tr><td>Centrifuge</td><td>Hettich</td><td></td><td>Or equivalent equipment</td></tr><tr><td>Flow cytometer (FACSAria)</td><td>BD Biosciences</td><td></td><td></td></tr><tr><td>Fetal bovine serum</td><td>BioWest</td><td>S1820-500</td><td></td></tr><tr><td>PBS 10x</td><td>LONZA</td><td>BE17-515Q</td><td></td></tr><tr><td>Collagenase</td><td>Sigma-Aldrich</td><td>12/1/9001</td><td></td></tr><tr><td>ACK Lysing Buffer</td><td>Thermo Fisher Scientific</td><td>A10492-01</td><td></td></tr><tr><td>Flow cytometry strainers</td><td>BD Biosciences</td><td>340626</td><td></td></tr><tr><td>Falcon cell strainers</td><td>Thermo Fisher Scientific</td><td>352340</td><td></td></tr><tr><td>Flow cytometry tubes</td><td>Falcon</td><td>352052</td><td>5 ml Polystyrene Round-Bottom Tube</td></tr><tr><td>Centrifuge tubes</td><td>Corning centristar</td><td>430791</td><td></td></tr><tr><td>Water bath</td><td>Memmert GmbH + Co. KG</td><td>WNE 7</td><td>37 &amp;#176;C</td></tr><tr><td>Fixation/Permeabilization Solution or Permeabilization/Wash Buffer</td><td>BD Biosciences</td><td>554714</td><td></td></tr><tr><td>Rompum (Xylazine)</td><td>Bayer</td><td></td><td>Or equivalent</td></tr><tr><td>Ketalar (Ketamine)</td><td>Pfizer</td><td></td><td>Or equivalent</td></tr><tr><td>Hanks&amp;rsquo; balanced salt solution</td><td>Sigma-Aldrich</td><td>H8264-500ML</td><td></td></tr><tr><td>Saline solution</td><td>Braun</td><td>622415</td><td></td></tr><tr><td>Anti-CD45 (clone:OX-1) APC-Cy7</td><td>Biolegend</td><td>202216</td><td>Diluted 1:100</td></tr><tr><td>Anti-CD68 (clone: ED1) FITC</td><td>Bio-RAD</td><td>MCA341F</td><td>Diluted 35:1,000</td></tr><tr><td>anti-CD86 (clone: 24F) PE</td><td>Biolegend</td><td>200307</td><td>Diluted 35:1,000</td></tr><tr><td>anti-CD163 (clone: ED2) Alexa Fluor 647</td><td>Bio-RAD</td><td>MCA342R</td><td>Diluted 4:100</td></tr><tr><td>Live/dead stain&amp;nbsp;</td><td>Molecular Probes</td><td>L34955</td><td>Diluted 3:1,000</td></tr></tbody></table>

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.

We analyzed macrophage heterogeneity in an inflammatory experimental model of renal injury associated with increased presence of infiltrating macrophages in the kidney. In this model, renal damage was induced by administration of aldosterone (1 mg-1kg-1day) plus salt (NaCl 1%) in drinking water for 3 weeks in Wistar rats, as previously reported12.
The schedule of our experiments is shown in <stro...

Watch this Scientific Journal Video about Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry at JoVE.com

Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry

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 ...

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Immunology and Infection

14.7K Views.  Autonoma University. 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.

Video: Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry

A Simple and Efficient Method to Isolate Macrophages from Mixed Primary Cultures of Adult Liver Cells

Kupffer cells are liver-specific resident macrophages and play an important role in the physiological and pathological functions of the liver1-3. Although the isolation methods of liver macrophages have been well-described4-6, most of these methods require sophisticated equipment, such as a centrifugal elutriator and technical skills. Here, we provide a novel method to obtain liver macrophages in sufficient number and purity from mixed primary cultures of adult rat liver cells, as schematically illustrated in Figure 1.
After dissociation of the liver cells by two-step perfusion method7,8,a fraction mostly composed of parenchymal hepatocytes is prepared and seeded into T75 tissue culture flasks with culture medium composed of DMEM and 10% FCS.Parenchymal hepatocytes lose the epithelial cell morphology within a few days in culture, degenerate or transform into fibroblast-like cells (Figure 2). As the culture proceeds, around day 6, phase contrast-bright, round macrophage-like cells start to proliferate on the fibroblastic cell sheet (Figure 2). The growth of the macrophage-like cells continue and reach to maximum levels around day 12, covering the cell sheet on the flask surface. By shaking of the culture flasks, macrophages are readily suspended into the culture medium. Subsequent transfer and short incubation in plastic dishes result in selective adhesion of macrophages(Figure 3), where as other contaminating cells remain suspended. After several rinses with PBS, attached macrophages are harvested. More than 106 cells can be harvested repeatedly from the same T75 tissue culture flask at two to three day intervals for more than two weeks(Figure 3).The purities of the isolated macrophages were 95 to 99%, as evaluated by flow cytometry or immunocytochemistry with rat macrophage-specific antibodies (Figure 4).The isolated cells show active phagocytosis of polystylene beads (Figure 5), proliferative response to recombinant GM-CSF, secretion of inflammatory/anti-inflammatory cytokines upon stimulation with LPS, and formation of multinucleated giant cells9.
In conclusion, we provide a simple and efficient method to obtain liver macrophages in sufficient number and purity without complex equipment and skills.This method might be applicable to other mammalian species.

A novel method to obtain macrophages from primary culture of rat liver cells is described. This method utilizes the proliferation of macrophages in the culture, followed by shaking of culture flasks and purification by selective attachment to plastic dishes. This technique efficiently provides liver macrophages without complex equipment and skills.

Kupffer cells are liver-specific resident macrophages and play an important role in the physiological and pathological functions of the liver1-3. Although ...

Harvesting Murine Alveolar Macrophages and Evaluating Cellular Activation Induced by Polyanhydride Nanoparticles

Biodegradable nanoparticles have emerged as a versatile platform for the design and implementation of new intranasal vaccines against respiratory infectious diseases. Specifically, polyanhydride nanoparticles composed of the aliphatic sebacic acid (SA), the aromatic 1,6-bis(p-carboxyphenoxy)hexane (CPH), or the amphiphilic 1,8-bis(p-carboxyphenoxy)-3,6-dioxaoctane (CPTEG) display unique bulk and surface erosion kinetics1,2 and can be exploited to slowly release functional biomolecules (e.g., protein antigens, immunoglobulins, etc.) in vivo3,4,5. These nanoparticles also possess intrinsic adjuvant activity, making them an excellent choice for a vaccine delivery platform6,7,8.
	In order to elucidate the mechanisms governing the activation of innate immunity following intranasal mucosal vaccination, one must evaluate the molecular and cellular responses of the antigen presenting cells (APCs) responsible for initiating immune responses. Dendritic cells are the principal APCs found in conducting airways, while alveolar macrophages (AM&#632;) predominate in the lung parenchyma9,10,11. AM&#632; are highly efficient in clearing the lungs of microbial pathogens and cell debris12,13. In addition, this cell type plays a valuable role in the transport of microbial antigens to the draining lymph nodes, which is an important first step in the initiation of an adaptive immune response9. AM&#632; also express elevated levels of innate pattern recognition and scavenger receptors, secrete pro-inflammatory mediators, and prime na&iuml;ve T cells12,14. A relatively pure population of AM&#632; (e.g., greater than 80%) can easily be obtained via lung lavage for study in the laboratory. Resident AM&#632; harvested from immune competent animals provide a representative phenotype of the macrophages that will encounter the particle-based vaccine in vivo. Herein, we describe the protocols used to harvest and culture AM&#632; from mice and examine the activation phenotype of the macrophages following treatment with polyanhydride nanoparticles in vitro.

Herein, we describe protocols for harvesting murine alveolar macrophages, which are resident innate immune cells in the lung, and examining their activation in response to co-culture with polyanhydride nanoparticles.

Biodegradable nanoparticles have emerged as a  versatile platform for the design and implementation of new intranasal vaccines  against respiratory ...

Bioengineering

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 ...

Reliable and High Efficiency Extraction of Kidney Immune Cells

Immune system activation occurs in multiple kidney diseases and pathophysiological processes. The immune system consists of both adaptive and innate components and multiple cell types. Sometimes, the cell type of interest is present in very low numbers among the large numbers of total cells isolated from the kidney. Hence, reliable and efficient isolation of kidney mononuclear cell populations is important in order to study the immunological problems associated with kidney diseases. Traditionally, tissue isolation of kidney mononuclear cells have been performed via enzymatic digestions using different varieties and strengths of collagenases/DNAses yielding varying numbers of viable immune cells. Recently, with the development of the mechanical tissue disruptors for single cell isolation, the collagenase digestion step is avoided and replaced by a simple mechanical disruption of the kidneys after extraction from the mouse. Herein, we demonstrate a simple yet efficient method for the isolation of kidney mononuclear cells for every day immune cell extractions. We further demonstrate an example of subset analysis of immune cells in the kidney. Importantly, this technique can be adapted to other soft and non-fibrous tissues such as the liver and brain.

Techniques that are reliable and efficient for the isolation of kidney immune cells are needed for downstream applications. This requires surface antibody labeling of a small number of kidney immune cells. Herein, we describe a concise method for isolation of kidney immune cells that seemingly achieves this goal.

Immune system activation occurs in multiple kidney diseases and pathophysiological processes.  The immune system consists of both adaptive and innate ...

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 ...

Rapid Depletion of Renal Macrophages using Human CD59/Intermedilysin Cell Ablation Tool

Renal macrophages (RMs) are essential for kidney health, orchestrating immune surveillance, tissue homeostasis, and responses to injury. Previously, we reported the use of a human CD59 (hCD59)/intermedilysin (ILY) cell ablation tool to study the distinct fate, dynamics, and niches of RMs of bone marrow or embryonic origin. RMs originate from yolk sac-derived macrophages, fetal liver monocytes, and bone marrow-derived monocytes and are maintained in adulthood through local proliferation and recruitment of circulating monocytes. Here, we report a detailed protocol for the selective ablation of RMs to study their regeneration, including 1) generation and characterization of the Cre-inducible expression of hCD59 in mouse RMs, 2) purification of ILY and characterization of ILY activity, 3) induction of hCD59 expression on RMs in compound mice, and 4) characterization of regeneration after ILY-mediated RM ablation. ILY specifically and rapidly depletes RMs in compound mice, with efficient macrophage ablation within 1 day of ILY administration. Renal macrophage regeneration began by day 3 post-ablation, with ~88% recovery by day 7. This model offers a powerful tool for studying macrophage biology and can be used for selectively ablating other cell populations in the kidney, liver, and fatty tissues to investigate their function and regeneration.

A protocol is reported here for the selective ablation of renal macrophages to study their regeneration using the human CD59/intermedilysin cell ablation tool. This method is also applicable for studying the function and regeneration of the other cell populations in the kidney, liver, and fatty tissue.

Renal macrophages (RMs) are essential for kidney health, orchestrating immune surveillance, tissue homeostasis, and responses to injury. Previously, we ...

Developmental Biology

Flow Cytometric Measurement Of ROS Production In Macrophages In Response To Fc&#947;R Cross-linking

The oxidative or respiratory burst is used to describe the rapid consumption of oxygen and generation of reactive oxygen species (ROS) by phagocytes in response to various immune stimuli. ROS generated during immune activation exerts potent antimicrobial activity primarily through the ability of ROS to damage DNA and proteins, causing death of microorganisms. Being able to measure ROS production reproducibly and with ease is necessary in order to assess the contribution of various pathways and molecules to this mechanism of host defense. In this paper, we demonstrate the use of fluorescent probes and flow cytometry to detect ROS production. Although widely used, fluorescent measurement of ROS is notoriously problematic, especially with regards to measurement of ROS induced by specific and not mitogenic stimuli. We present a detailed methodology to detect ROS generated as a result of specific Fc&#947;R stimulation beginning with macrophage generation, priming, staining, Fc&#947;R cross-linking, and ending with flow cytometric analysis.

This study demonstrates the use of flow cytometry to detect reactive oxygen species (ROS) production resulting from activation of the Fc&#947;R. This method can be used to assess changes in the antimicrobial and redox signaling function of phagocytes in response to immune complexes, opsonized microorganisms, or direct Fc&#947;R cross-linking.

The oxidative or respiratory burst is used to describe the rapid consumption of oxygen and generation of reactive oxygen species (ROS) by phagocytes in ...

Characterization of Immune Cells in Human Adipose Tissue by Using Flow Cytometry

Infiltration of immune cells in the subcutaneous and visceral adipose tissue (AT) deposits leads to a low-grade inflammation contributing to the development of obesity-associated complications such as type 2 diabetes. To quantitatively and qualitatively investigate the immune cell subsets in human AT deposits, we have developed a flow cytometry approach. The stromal vascular fraction (SVF), containing the immune cells, is isolated from subcutaneous and visceral AT biopsies by collagenase digestion. Adipocytes are removed after centrifugation. The SVF cells are stained for multiple membrane-bound markers selected to differentiate between immune cell subsets and analyzed using flow cytometry. As a result of this approach, pro- and anti-inflammatory macrophage subsets, dendritic cells (DCs), B-cells, CD4+ and CD8+ T-cells, and NK cells can be detected and quantified. This method gives detailed information about immune cells in AT and the amount of each specific subset. Since there are numerous fluorescent antibodies available, our flow cytometry approach can be adjusted to measure various other cellular and intracellular markers of interest.

This article describes a method to analyze immune cell content of adipose tissue by isolation of immune cells from adipose tissue and subsequent analysis using flow cytometry.

Infiltration of immune cells in the subcutaneous and visceral adipose tissue (AT) deposits leads to a low-grade inflammation contributing to the ...

Medicine

Digestion of Whole Mouse Eyes for Multi-Parameter Flow Cytometric Analysis of Mononuclear Phagocytes

The innate immune system plays important roles in ocular pathophysiology including uveitis, diabetic retinopathy, and age-related macular degeneration. Innate immune cells, specifically mononuclear phagocytes, express overlapping cell surface markers, which makes identifying these populations a challenge. Multi-parameter flow cytometry allows for the simultaneous, quantitative analysis of multiple cell surface markers in order to differentiate monocytes, macrophages, microglia, and dendritic cells in mouse eyes. This protocol describes the enucleation of whole mouse eyes, ocular dissection, digestion into a single cell suspension, and staining of the single cell suspension for myeloid cell markers. Additionally, we explain the proper methods for determining voltages using single color controls and for delineating positive gates using fluorescence minus one controls. The major limitation of multi-parameter flow cytometry is the absence of tissue architecture. This limitation can be overcome by multi-parameter flow cytometry of individual ocular compartments or complimentary immunofluorescence staining. However, immunofluorescence is limited by its lack of quantitative analysis and reduced number of fluorophores on most microscopes. We describe the use of multi-parametric flow cytometry to provide highly quantitative analysis of mononuclear phagocytes in laser-induced choroidal neovascularization. Additionally, multi-parameter flow cytometry can be used for the identification of macrophage subsets, fate mapping, and cell sorting for transcriptomic or proteomic studies.

This protocol provides a method to digest whole eyes into a single cell suspension for the purpose of multi-parameter flow cytometric analysis in order to identify specific ocular mononuclear phagocytic populations, including monocytes, microglia, macrophages, and dendritic cells.

The innate immune system plays important roles in ocular pathophysiology including uveitis, diabetic retinopathy, and age-related macular degeneration. ...

Flow Cytometry Approach to Characterize Phagocytic Properties of Acutely-Isolated Adult Microglia and Brain Macrophages In Vitro

Microglia and central nervous system (CNS)-infiltrating macrophages, collectively called CNS mononuclear phagocytes (CNS-MPs), play central roles in neurological diseases including neurodegeneration and stroke. CNS-MPs are involved in phagocytic clearance of pathological proteins, debris and neuronal synapses, each with distinct underlying molecular pathways. Characterizing these phagocytic properties can provide a functional readout that compliments molecular profiling of microglia using traditional flow cytometry, transcriptomics and proteomics approaches. Phagocytic profiling of microglia has relied on microscopic visualization and in vitro cultures of mouse neonatal microglia. The former approach suffers from limited sampling while the latter approach is inherently poorly reflective of the true in vivo state of adult CNS-MPs. This paper describes optimized protocols to phenotype phagocytic properties of acutely-isolated mouse CNS-MPs by flow cytometry. CNS-MPs are acutely isolated from adult mouse brain using mechanical dissociation followed by density gradient centrifugation, incubated with fluorescent microspheres or fluorescent A&#946; fibrils, washed, and then labeled with panels of antibodies against surface markers (CD11b, CD45). Using this approach, it is possible to compare phagocytic properties of brain-resident microglia with CNS-infiltrating macrophages and then assess the effect of aging and disease pathology on these phagocytic phenotypes. This rapid method also holds potential to functionally phenotype acutely-isolated human CNS-MPs from post-mortem or surgical brain specimens. Additionally, specific mechanisms of phagocytosis by CNS-MP subsets can be investigated by inhibiting select phagocytic pathways.

Assessment of phagocytic properties of microglia and brain macrophages can provide a valuable functional dimension to molecular profiling studies. We describe a validated protocol that uses flow cytometry to rapidly and reliably quantify phagocytosis of fluorescent microspheres and amyloid beta fibrils by acutely-isolated microglia and brain macrophages from mouse models.

Microglia and central nervous system (CNS)-infiltrating macrophages, collectively called CNS mononuclear phagocytes (CNS-MPs), play central roles in ...