Generation and characterization of murine alternatively activated macrophages

The chapter, "Generation and characterization of murine alternatively activated macrophages" was written by the listed authors including Shelley B. Weisser (Douglas College Faculty). Part of the "Methods in Molecular Biology (Methods and Protocols)" book series (MIMB, volume 946): For over 35 years, biological scientists have come to rely on the research protocols and methodologies in the critically acclaimed Methods in Molecular Biology series. The series was the first to introduce the step-by-step protocols approach that has become the standard in all biomedical protocol publishing. Each protocol is provided in readily-reproducible step-by step fashion, opening with an introductory overview, a list of the materials and reagents needed to complete the experiment, and followed by a detailed procedure that is supported with a helpful notes section offering tips and tricks of the trade as well as troubleshooting advice. These hallmark features were introduced by series editor Dr. John Walker and constitute the key ingredient in each and every volume of the Methods in Molecular Biology series. Tested and trusted, comprehensive and reliable, all protocols from the series are indexed in PubMed. <p> <p> Book "Basic Cell Culture Protocols": At some point in their careers, virtually every scientist and technician, as well as many medical professionals, regardless of their area of specialization have a need to utilize cell culture systems. Updating and significantly expanding upon the previous editions, Basic Cell Culture Protocols, Fourth Edition provides the novice cell culturist with sufficient information to perform the basic techniques, to ensure the health and identity of their cell lines, and to be able to isolate and culture specialized primary cell types. The intent of this extensive volume is to generate a valuable resource containing clear methodologies pertinent to current areas of investigation, rather than attempting to educate cell culturists on specific cell types or organ systems. Written in the highly successful Methods in Molecular Biology™, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Comprehensive and up-to-date, Basic Cell Culture Protocols, Fourth Edition compiles the essential techniques needed to approach this vital laboratory activity with full success. <p>Book Chapter: Macrophages play a key role in the innate immune response and help to direct the acquired immune response. Early in the innate immune response, they produce reactive oxygen species and pro-inflammatory cytokines and chemokines to drive inflammation and are referred to as “classically activated” or “killer” macrophages (M1). During the resolution phase of inflammation, they switch to what is known as an “alternatively activated” phenotype or “healer” macrophage (M2) and contribute to debris scavenging, angiogenesis, and wound healing. M1 macrophages are activated by treatment with IFNγ or LPS and M2 macrophages are activated by treatment with Th2 cytokines IL-4 or IL-13 and the M2 phenotype switch can be enhanced by IL-10. Macrophages can also be skewed during differentiation in vitro, and the resultant phenotype depends upon the cytokine provided to support their differentiation. In murine macrophages, MCSF promotes differentiation to an M1 phenotype, GM-CSF promotes differentiation to an M2 phenotype and IL-3 promotes differentiation into a profoundly M2 skewed phenotype. A defining feature of the phenotype of murine M1 versus M2 macrophages is how they metabolize L-arginine. In response to an inflammatory stimulus like LPS, M1 macrophages produce inducible nitric oxide synthase (iNOS) which uses L-arginine as a substrate to produce nitric oxide (NO). M2 macrophages constitutively produce the enzyme arginase I (argI), which sequesters L-arginine from iNOS and results in the production of ornithine and downstream polyamines and L-proline. M1 macrophages also produce relatively higher levels of pro-inflammatory IL-12 and lower levels of anti-inflammatory IL-10 relative to M2 macrophages. In this chapter, we describe in vitro derivation of polarized bone marrow macrophages and methods to analyze the resulting phenotype including Q-PCR, Western blotting, and enzyme assays to determine argI and iNOS expression and activity, as well as production of IL-12p40 and IL-10 and determination of IL-12/IL-10 ratios. Production of iNOS, NO, IL-12p40, and IL-10 are measured after treatment with LPS.