Differential expression of the fractalkine chemokine receptor (CX3CR1) in human monocytes during differentiation

Cell Mol Immunol. 2015 Nov;12(6):669-80. doi: 10.1038/cmi.2014.116. Epub 2014 Dec 15.

Abstract

Circulating monocytes (Mos) may continuously repopulate macrophage (MAC) or dendritic cell (DC) populations to maintain homeostasis. MACs and DCs are specialized cells that play different and complementary immunological functions. Accordingly, they present distinct migratory properties. Specifically, whereas MACs largely remain in tissues, DCs are capable of migrating from peripheral tissues to lymphoid organs. The aim of this work was to analyze the expression of the fractalkine receptor (CX3CR1) during the monocytic differentiation process. Freshly isolated Mos express high levels of both CX3CR1 mRNA and protein. During the Mo differentiation process, CX3CR1 is downregulated in both DCs and MACs. However, MACs showed significantly higher CX3CR1 expression levels than did DC. We also observed an antagonistic CX3CR1 regulation by interferon (IFN)-γ and interleukin (IL)-4 during MAC activation through the classical and alternative MAC pathways, respectively. IFN-γ inhibited the loss of CX3CR1, but IL-4 induced it. Additionally, we demonstrated an association between CX3CR1 expression and apoptosis prevention by soluble fractalkine (sCX3CL1) in Mos, DCs and MACs. This is the first report demonstrating sequential and differential CX3CR1 modulation during Mo differentiation. Most importantly, we demonstrated a functional link between CX3CR1 expression and cell survival in the presence of sCX3CL1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • CX3C Chemokine Receptor 1
  • Cell Differentiation / drug effects
  • Cell Movement / drug effects
  • Cell Survival / drug effects
  • Dendritic Cells / cytology*
  • Dendritic Cells / drug effects
  • Dendritic Cells / immunology
  • Gene Expression Regulation
  • Humans
  • Interferon-gamma / genetics
  • Interferon-gamma / immunology
  • Interferon-gamma / pharmacology
  • Interleukin-4 / genetics
  • Interleukin-4 / immunology
  • Interleukin-4 / pharmacology
  • Macrophages / cytology*
  • Macrophages / drug effects
  • Macrophages / immunology
  • Monocytes / cytology*
  • Monocytes / drug effects
  • Monocytes / immunology
  • Organ Specificity
  • Primary Cell Culture
  • Receptors, Chemokine / genetics*
  • Receptors, Chemokine / immunology
  • Signal Transduction

Substances

  • CX3C Chemokine Receptor 1
  • CX3CR1 protein, human
  • IL4 protein, human
  • Receptors, Chemokine
  • Interleukin-4
  • Interferon-gamma