title: Transcriptome profiling of primary murine monocytes, lung macrophages and lung dendritic cells reveals a distinct expression of genes involved in cell trafficking.
abstract: BACKGROUND
  Peripheral blood monocytes (PBMo) originate from the bone marrow, circulate in the blood and emigrate into various organs where they differentiate into tissue resident cellular phenotypes of the mononuclear phagocyte system, including macrophages (Mphi) and dendritic cells (DC). Like in other organs, this emigration and differentiation process is essential to replenish the mononuclear phagocyte pool in the lung under both inflammatory and non-inflammatory steady-state conditions. While many studies have addressed inflammation-driven monocyte trafficking to the lung, the emigration and pulmonary differentiation of PBMo under non-inflammatory conditions is much less understood.
  
  
  METHODS
  In order to assess the transcriptional profile of circulating and lung resident mononuclear phagocyte phenotypes, PBMo, lung Mphi and lung DC from naïve mice were flow-sorted to high purity, and their gene expression was compared by DNA microarrays on a genome-wide scale. Differential regulation of selected genes was validated by quantitative PCR and on protein level by flow cytometry.
  
  
  RESULTS
  Differentially-expressed genes related to cell traffic were selected and grouped into the clusters (i) matrix metallopeptidases, (ii) chemokines/chemokine receptors, and (iii) integrins. Expression profiles of clustered genes were further assessed at the mRNA and protein levels in subsets of circulating PBMo (GR1- vs GR1+) and lung resident macrophages (alveolar vs interstitial Mphi). Our data identify differentially activated genetic programs in circulating monocytes and their lung descendents. Lung DC activate an extremely diverse set of gene families but largely preserve a mobile cell profile with high expression levels of integrin and chemokine/chemokine receptors. In contrast, interstitial and even more pronounced alveolar Mphi, stepwise downregulate gene expression of these traffic relevant communication molecules, but strongly upregulate a distinct set of matrix metallopetidases potentially involved in tissue invasion and remodeling.
  
  
  CONCLUSIONS
  Our data provide new insight in the changes of the genetic profiles of PBMo and their lung descendents, namely DC and Mphi under non-inflammatory, steady-state conditions. These findings will help to better understand the complex relations within the mononuclear phagocyte pool of the lung.
authors.affiliation: Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of Giessen Lung Center, Giessen, Germany. zbigniew.zaslona@innere.med.uni-giessen.de
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Zasłona
authors.forename: Jochen
authors.initials: J
authors.lastname: Wilhelm
authors.forename: Lidija
authors.initials: L
authors.lastname: Cakarova
authors.forename: Leigh M
authors.initials: LM
authors.lastname: Marsh
authors.forename: Werner
authors.initials: W
authors.lastname: Seeger
authors.forename: Jürgen
authors.initials: J
authors.lastname: Lohmeyer
authors.forename: Werner
authors.initials: W
authors.lastname: von Wulffen
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000235:genetics*; D002469:Cell Separation; D018925:Chemokines / Q000235:genetics; D003713:Dendritic Cells / Q000737:chemistry* / Q000276:immunology; D020869:Gene Expression Profiling / Q000379:methods; D016130:Immunophenotyping; D016023:Integrins / Q000235:genetics; D007378:Interleukins / Q000235:genetics; D008168:Lung / Q000737:chemistry* / Q000166:cytology / Q000276:immunology; D016676:Macrophages, Alveolar / Q000737:chemistry* / Q000276:immunology; D045726:Metalloproteases / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000737:chemistry* / Q000276:immunology; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000032:analysis*; D019707:Receptors, Chemokine / Q000235:genetics; D018123:Receptors, Interleukin / Q000235:genetics; D015203:Reproducibility of Results
chemical_list: D018925:Chemokines; D016023:Integrins; D007378:Interleukins; D012333:RNA, Messenger; D019707:Receptors, Chemokine; D018123:Receptors, Interleukin; D045726:Metalloproteases