Identification of polarized macrophage subsets in zebrafish

Elife. 2015 Jul 8;4:e07288. doi: 10.7554/eLife.07288.

Abstract

While the mammalian macrophage phenotypes have been intensively studied in vitro, the dynamic of their phenotypic polarization has never been investigated in live vertebrates. We used the zebrafish as a live model to identify and trail macrophage subtypes. We generated a transgenic line whose macrophages expressing tumour necrosis factor alpha (tnfa), a key feature of classically activated (M1) macrophages, express fluorescent proteins Tg(mpeg1:mCherryF/tnfa:eGFP-F). Using 4D-confocal microscopy, we showed that both aseptic wounding and Escherichia coli inoculation triggered macrophage recruitment, some of which started to express tnfa. RT-qPCR on Fluorescence Activated Cell Sorting (FACS)-sorted tnfa(+) and tnfa(-) macrophages showed that they, respectively, expressed M1 and alternatively activated (M2) mammalian markers. Fate tracing of tnfa(+) macrophages during the time-course of inflammation demonstrated that pro-inflammatory macrophages converted into M2-like phenotype during the resolution step. Our results reveal the diversity and plasticity of zebrafish macrophage subsets and underline the similarities with mammalian macrophages proposing a new system to study macrophage functional dynamic.

Keywords: developmental biology; immunology; live imaging; macrophages; stem cells; zebrafish.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Escherichia coli Infections / immunology
  • Flow Cytometry
  • Gene Expression Profiling
  • Genes, Reporter
  • Macrophages / classification*
  • Macrophages / immunology*
  • Microscopy, Confocal
  • Molecular Sequence Data
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Analysis, DNA
  • Tumor Necrosis Factor-alpha / biosynthesis
  • Wounds and Injuries / immunology
  • Zebrafish / immunology*

Substances

  • Tumor Necrosis Factor-alpha

Grant support

Conseil Régional Languedoc-Roussillon: supported Farida Djouad's work by covering the expenses for reagent, imaging and animal facilities as well as the salary for an engineer. Agence Nationale de la Recherche: supported Jean-Pierre Levraud's work by covering animal facility expenses and expenses for reagent and Georges Lutfalla's work by covering animal facility expenses and some expenses for reagents. The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.