Expression, regulation, and function of atypical chemerin receptor CCRL2 on endothelial cells

J Immunol. 2012 Jul 15;189(2):956-67. doi: 10.4049/jimmunol.1102871. Epub 2012 Jun 13.

Abstract

Chemokine (CC motif) receptor-like 2 (CCRL2) binds leukocyte chemoattractant chemerin and can regulate local levels of the attractant, but does not itself support cell migration. In this study, we show that CCRL2 and VCAM-1 are upregulated on cultured human and mouse vascular endothelial cells (EC) and cell lines by proinflammatory stimuli. CCRL2 induction is dependent on NF-κB and JAK/STAT signaling pathways, and activated endothelial cells specifically bind chemerin. In vivo, CCRL2 is constitutively expressed at high levels by lung endothelial cells and at lower levels by liver endothelium; and liver but not lung EC respond to systemic LPS injection by further upregulation of the receptor. Plasma levels of total chemerin are elevated in CCRL2(-/-) mice and are significantly enhanced after systemic LPS treatment in CCRL2(-/-) mice compared with wild-type mice. Following acute LPS-induced pulmonary inflammation in vivo, chemokine-like receptor 1 (CMKLR1)(+) NK cell recruitment to the airways is significantly impaired in CCRL2(-/-) mice compared with wild-type mice. In vitro, chemerin binding to CCRL2 on endothelial cells triggers robust adhesion of CMKLR1(+) lymphoid cells through an α(4)β(1) integrin/VCAM-1-dependent mechanism. In conclusion, CCRL2 is expressed by EC in a tissue- and activation-dependent fashion, regulates circulating chemerin levels and its bioactivity, and enhances chemerin- and CMKLR1-dependent lymphocyte/EC adhesion in vitro and recruitment to inflamed airways in vivo. Its expression and/or induction on EC by proinflammatory stimuli provide a novel and specific mechanism for the local enrichment of chemerin at inflammatory sites, regulating the recruitment of CMKLR1(+) cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • CHO Cells
  • Cell Movement / immunology
  • Chemokines
  • Chemotactic Factors / blood
  • Cricetinae
  • Endothelium, Vascular / immunology*
  • Endothelium, Vascular / metabolism*
  • Endothelium, Vascular / pathology
  • HEK293 Cells
  • Human Umbilical Vein Endothelial Cells
  • Humans
  • Inflammation / immunology
  • Inflammation / metabolism
  • Inflammation / pathology
  • Intercellular Signaling Peptides and Proteins / blood
  • Janus Kinases / physiology
  • Mice
  • Mice, Inbred BALB C
  • Mice, Knockout
  • NF-kappa B / physiology
  • Receptors, CCR / biosynthesis*
  • Receptors, CCR / deficiency
  • Receptors, CCR / physiology
  • STAT Transcription Factors / physiology
  • Signal Transduction / immunology
  • Up-Regulation / immunology
  • Vascular Cell Adhesion Molecule-1 / biosynthesis

Substances

  • CCRL2 protein, human
  • Chemokines
  • Chemotactic Factors
  • Intercellular Signaling Peptides and Proteins
  • NF-kappa B
  • Receptors, CCR
  • STAT Transcription Factors
  • Vascular Cell Adhesion Molecule-1
  • chemerin protein, mouse
  • Janus Kinases