We describe here a simple protocol to isolate murine peritoneal macrophages. This procedure is followed by RNA extraction to carry out gene expression analysis upon Toll-like receptors stimulation.
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Method Article
Isolation of Murine Peritoneal Macrophages to Carry Out Gene Expression Analysis Upon Toll-like Receptors Stimulation
In This Article
Summary
Abstract
During infection and inflammation, circulating monocytes leave the bloodstream and migrate into tissues, where they differentiate into macrophages. Macrophages express surface Toll-like receptors (TLRs), which recognize molecular patterns conserved through evolution in a wide range of microorganisms. TLRs play a central role in macrophage activation which is usually associated with gene expression alteration. Macrophages are critical in many diseases and have emerged as attractive targets for therapy. In the following protocol, we describe a procedure to isolate murine peritoneal macrophages using Brewer’s thioglycollate medium. The latter will boost monocyte migration into the peritoneum, accordingly this will raise macrophage yield by 10-fold. Several studies have been carried out using bone marrow, spleen or peritoneal derived macrophages. However, peritoneal macrophages were shown to be more mature upon isolation and are more stable in their functionality and phenotype. Thus, macrophages isolated from murine peritoneal cavity present an important cell population that can serve in different immunological and metabolic studies. Once isolated, macrophages were stimulated with different TLR ligands and consequently gene expression was evaluated.
Introduction
The reticuloendothelial phagocytic system is composed of cells in various tissues and organs such as bone marrow, blood, liver and spleen. Macrophages are extensively distributed around the body, where they notably participate in innate and adaptive immune responses to control and clear infections. In addition to their role in host defense, macrophages also play an important role in wound healing and in maintaining tissue homeostasis1,2. Furthermore, macrophages are not only important to immune function but also actively participate in iron homeostasis3. In the body, approximately 80% of iron is present in hemoglobin within erythrocytes, which wh....
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Protocol
All procedures were performed in accordance with the Canadian Council on Animal Care guidelines after approval by the institutional Animal Care Committee of the Centre de recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM).
1. Isolation, Identification, and Culture of Murine Peritoneal Macrophages
- Prepare 3.8% brewer’s thioglycollate medium. To do so, suspend 38 g of thioglycollate medium in 1,000 ml of distilled water. Bring solution to boil to dissolve the medium completely. Sterilize by autoclaving at 121 °C for 15 min. Store up to 3 months in the dark, at RT18.
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Results
We first characterized the isolated murine peritoneal macrophages by flow cytometry. To do so, we used (F4/80) antibodies that specifically recognize markers only expressed by macrophages. This characterization is required to determine the percentage of isolated macrophage and to distinguish them among cells obtained during the isolation process. As shown in (Figure 1), the percentage of cells expressing the antigen F4/80 was consistently found to be above 95%. Next, to study gene expression in macrophag.......
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Discussion
Macrophages are crucial for survival and provide a tempting target to manipulate the host for immunological objectives. The discovery of TLRs and other recognition molecules have conducted the macrophages to the centre of immunological debate. Macrophages respond to a variety of stimuli, including cytokines, damage-associated molecular pattern molecules (DAMPs)20 and molecules associated with groups of pathogens (PAMPs)21. These different stimuli responses represent the course of macrophages activat.......
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Disclosures
The authors have no competing financial interests.
Acknowledgements
This work was supported by a grant from the Natural Sciences and Engineering Research Council of Canada (NSERC, grant no 298515-2011). AL is the recipient of a Ph.D. scholarship from the Natural Sciences and Engineering Research Council of Canada (NSERC), and MS was supported from a grant from the Canadian Institutes of Health Research (CIHR, grant no. MOP123246).
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| C57BL/6 mice | Charles River Laboratories, Inc. (Wilmington, MA, USA) | 475 | |
| Thioglycollate | Sigma-Aldrich, (St. Louis, MO) | 19032-500G | |
| 70% ethanol | |||
| 10% sodium pentobarbital (Used for mice anesthesia (80 mg/kg, i.p.)) | |||
| Dulbecco’s phosphate-buffered saline (DPBS), placed on ice and will serve to harvest macrophages | WISENT INC Canada (QC) | 311-425-CL | |
| RPMI medium 1640 (Supplement with penicillin, streptomycin, L-glutamine, and 10 % fetal calf serum). | WISENT INC Canada (QC) | 350-000-CL | |
| 1 and 5 ml syringes | BD USA (NJ) | 309659 | |
| 6-well plates | Corning Incorporated (NY, USA) | MCT-150-C | |
| Bacterial lipoprotein Pam3CSK4 (0.5 mg/ml) | InvivoGen (San Diego, USA) | TLRL-pm25 | |
| Polyionosine–polycytidylic acid (Poly(I:C)) (10 mg/ml) | InvivoGen (San Diego, USA) | TLRL-PIC | |
| LPS from Escherichia coli 055:B5 (100 ng/ml) | InvivoGen (San Diego, USA) | L2880 | |
| Purified flagellin from Salmonella typhimurium (100 ng/ml) | InvivoGen (San Diego, USA) | TLR-FLIC-10 | |
| Lipoprotein synthetic FSL1 (100 ng/ml) | InvivoGen (San Diego, USA) | TLR-FSL | |
| ssRNA derived from the HIV-1 long terminal repeat ssRNA40 (1 μg/ml) | InvivoGen (San Diego, USA) | TLR-LRNA-40 | |
| Type B CpG oligonucleotide ODN1826 (1 μM) | InvivoGen (San Diego, USA) | 11B16-MM | |
| TRIzol | Invitrogen, (Burlington, ON, Canada) | 15596-026 | |
| 20 G and 23 G needles | BD USA (NJ) | 305175 | |
| Scissor | |||
| Forceps | |||
| 50 ml conical tubes placed on ice | Sarstedt (Newton, MA, USA) | 62.547.205 | |
| Red Blood Cells Lysis Buffer | Sigma-Aldrich, (St. Louis, MO) | R7757-100ML | |
| Refrigerated centrifuge | |||
| Hemocytometer | |||
| F4/80 antibody | BIO-RAD ( CA, USA) | MCA497APC | |
| CD16/CD32 antibodies | Pharmingen, {Mississauga, ON, CA) | 553141 | |
| Flow cytometer | Coulter Epics Elite counter, Coulter, (Hialeah, FL,USA) | ||
| 1.5 ml Eppendorf tubes | Axygen Scietific (CA,USA) | 3516 | |
| Chloroform | Fisher Scientific (ON, Canada) | UN1888 | |
| Isopropyl alcohol | JT Baker (PA, USA) | 70566 | |
| 75% ethanol (in DEPC treated water) | Commercial Alchohols (QC, Canada) | 17394 | |
| 0.01% diethyl pyrocarbonate (DEPC) treated water (let stand overnight and autoclave) | Sigma-Aldrich, (St. Louis, MO) | 216.542.8 | |
| Omniscript RT-PCR system | Qiagen, (Mississauga, ON, Canada) | 205113 | |
| Rotor Gene 3000 | Montreal Biotech, (Kirkland, QC, Canada) | ||
| QuantiTect SYBR Green I PCR kits | Qiagen, (Mississauga, ON, Canada) | 204141 |
References
- Pollard, J. W. Trophic macrophages in development and disease. Nat Rev Immunol. 9 (4), 259-270 (2009).
- Gordon, S. Alternative activation of macrophages. Nat Rev Immunol. 3 (1), 23-35 (2003).
- Koury, M. J., Ponka, P.
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