High-mannose intercellular adhesion molecule-1 enhances CD16 + monocyte adhesion to the endothelium

Am J Physiol Heart Circ Physiol. 2019 Nov 1;317(5):H1028-H1038. doi: 10.1152/ajpheart.00306.2019. Epub 2019 Aug 9.

Abstract

Human monocytes have been classified into three distinct groups, classical (anti-inflammatory; CD14+/CD16-), nonclassical (patrolling; CD14+/CD16++), and intermediate (proinflammatory; CD14++/CD16+). Adhesion of nonclassical/intermediate monocytes with the endothelium is important for innate immunity, and also vascular inflammatory disease. However, there is an incomplete understanding of the mechanisms that regulate CD16+ versus CD16- monocyte adhesion to the inflamed endothelium. Here, we tested the hypothesis that a high-mannose (HM) N-glycoform of intercellular adhesion molecule-1 (ICAM-1) on the endothelium mediates the selective recruitment of CD16+ monocytes. Using TNF-α treatment of human umbilical vein endothelial cells (HUVECs), and using proximity ligation assay for detecting proximity of specific N-glycans and ICAM-1, we show that TNF-α induces HM-ICAM-1 formation on the endothelial surface in a time-dependent manner. We next measured CD16- or CD16+ monocyte rolling and adhesion to TNF-α-treated HUVECs in which HM- or hybrid ICAM-1 N-glycoforms were generated using the α-mannosidase class I and II inhibitors, kifunensine and swainsonine, respectively. Expression of HM-ICAM-1 selectively enhanced CD16+ monocyte adhesion under flow with no effect on CD16- monocytes noted. CD16+ monocyte adhesion was abrogated by blocking either HM epitopes or ICAM-1. A critical role for HM-ICAM-1 in mediating CD16+ monocyte rolling and adhesion was confirmed using COS-1 cells engineered to express HM or complex ICAM-1 N-glycoforms. These data suggest that HM-ICAM-1 selectively recruits nonclassical/intermediate CD16+ monocytes to the activated endothelium.NEW & NOTEWORTHY Monocyte subsets have been associated with cardiovascular disease, yet it is unknown how different subsets are recruited to the endothelium. This study demonstrates the formation of distinct ICAM-1 N-glycoforms in the activated endothelium and reveals a key role for high mannose ICAM-1 in mediating proinflammatory CD16+ monocyte adhesion. Presented data identify roles for endothelial N-glycans in recruiting specific monocyte subsets during inflammation.

Keywords: N-glycan; inflammation; mannosidase.

Publication types

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

MeSH terms

  • Animals
  • COS Cells
  • Cell Adhesion* / drug effects
  • Cell Communication* / drug effects
  • Chlorocebus aethiops
  • Coculture Techniques
  • GPI-Linked Proteins / metabolism
  • Glycosylation
  • Human Umbilical Vein Endothelial Cells / drug effects
  • Human Umbilical Vein Endothelial Cells / metabolism*
  • Humans
  • Intercellular Adhesion Molecule-1 / genetics
  • Intercellular Adhesion Molecule-1 / metabolism*
  • Leukocyte Rolling* / drug effects
  • Mannose / metabolism*
  • Monocytes / metabolism*
  • Receptors, IgG / metabolism*
  • Signal Transduction
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • FCGR3B protein, human
  • GPI-Linked Proteins
  • ICAM1 protein, human
  • Receptors, IgG
  • Tumor Necrosis Factor-alpha
  • Intercellular Adhesion Molecule-1
  • Mannose