title: Transcriptomic analysis of human polarized macrophages: more than one role of alternative activation?
abstract: BACKGROUND
  Macrophages are a heterogeneous cell population which in response to the cytokine milieu polarize in either classically activated macrophages (M1) or alternatively activated macrophages (M2). This plasticity makes macrophages essential in regulating inflammation, immune response and tissue remodeling and a novel therapeutic target in inflammatory diseases such as atherosclerosis. The aim of the study was to describe the transcriptomic profiles of differently polarized human macrophages to generate new hypotheses on the biological function of the different macrophage subtypes.
  
  
  RESULTS
  Polarization of circulating monocytes/macrophages of blood donors was induced in vitro by IFN-γ and LPS (M1), by IL-4 (M2a), and by IL-10 (M2c). Unstimulated cells (RM) served as time controls. Gene expression profile of M1, M2a, M2c and RM was assessed at 6, 12 and 24h after polarization with Whole Human Genome Agilent Microarray technique. When compared to RM, M1 significantly upregulated pathways involved in immunity and inflammation, whereas M2a did the opposite. Conversely, decreased and increased expression of mitochondrial metabolism, consistent with insulin resistant and insulin sensitive patterns, was seen in M1 and M2a, respectively. The time sequence in the expression of some pathways appeared to have some specific bearing on M1 function. Finally, canonical and non-canonical Wnt genes and gene groups, promoting inflammation and tissue remodeling, were upregulated in M2a compared to RM.
  
  
  CONCLUSIONS
  Our data in in vitro polarized human macrophages: 1. confirm and extend known inflammatory and anti-inflammatory gene expression patterns; 2. demonstrate changes in mitochondrial metabolism associated to insulin resistance and insulin sensitivity in M1 and M2a, respectively; 3. highlight the potential relevance of gene expression timing in M1 function; 4. unveil enhanced expression of Wnt pathways in M2a suggesting a potential dual (pro-inflammatory and anti-inflammatory) role of M2a in inflammatory diseases.
authors: Unit of Diabetes and Metabolism, Department of Clinical and Experimental Medicine, University of Parma and AOUI of Parma, Parma, Italy.
authors: Eleonora
authors: E
authors: Derlindati
authors: Division of Endocrinology, Department of Clinical and Experimental Medicine, University of Parma and AOUI of Parma, Parma, Italy.
authors: Alessandra
authors: A
authors: Dei Cas
authors: Laboratory of Functional Genomics and Protein Engineering, Biochemistry and Molecular Biology Unit, Department of Life Sciences, University of Parma, Parma, Italy.
authors: Barbara
authors: B
authors: Montanini
authors: Division of Endocrinology, Department of Clinical and Experimental Medicine, University of Parma and AOUI of Parma, Parma, Italy.
authors: Valentina
authors: V
authors: Spigoni
authors: Unit of Diabetes and Metabolism, Department of Clinical and Experimental Medicine, University of Parma and AOUI of Parma, Parma, Italy.
authors: Valentina
authors: V
authors: Curella
authors: Unit of Diabetes and Metabolism, Department of Clinical and Experimental Medicine, University of Parma and AOUI of Parma, Parma, Italy.
authors: Raffaella
authors: R
authors: Aldigeri
authors: Unit of Diabetes and Metabolism, Department of Clinical and Experimental Medicine, University of Parma and AOUI of Parma, Parma, Italy.
authors: Diego
authors: D
authors: Ardigò
authors: Unit of Diabetes and Metabolism, Department of Clinical and Experimental Medicine, University of Parma and AOUI of Parma, Parma, Italy.
authors: Ivana
authors: I
authors: Zavaroni
authors: Division of Endocrinology, Department of Clinical and Experimental Medicine, University of Parma and AOUI of Parma, Parma, Italy.
authors: Riccardo C
authors: RC
authors: Bonadonna
mesh_terms: D015415:Biomarkers / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D006801:Humans; D008262:Macrophage Activation; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis
chemical_list: D015415:Biomarkers; D016207:Cytokines