Anti-OxLDL IgG blocks OxLDL interaction with CD36, but promotes FcgammaR, CD32A-dependent inflammatory cell adhesion

Immunol Lett. 2007 Jan 15;108(1):52-61. doi: 10.1016/j.imlet.2006.09.008. Epub 2006 Oct 23.

Abstract

Generation of antibodies against oxidized-low-density lipoproteins (oxLDL) during atherosclerosis could result in the formation and deposition of oxLDL immune complexes (oxLDL-IC) on the vascular endothelial cells. Inflammatory cells express scavenger receptor (SR such as CD36) and Fcgamma receptor (FcgammaR: CD32A and CD64) that can bind to oxLDL and oxLDL-IC, respectively. Hence, depending on anti-oxLDL IgG titer, circulating monocytes could adhere to endothelium to oxLDL-IC-coated vascular bed via either FcgammaR and/or CD36. In this study, we determined the relative contribution of SR and FcgammaR in mediating monocyte interaction with oxLDL-IC deposited on vascular bed. At saturating levels of anti-oxLDL IgG concentration, monocytic cells adhered to oxLDL-IC and this adhesion is completely blocked by anti-CD32A mAb. Using CHOK1-CD32A-CD36 cells expressing equal levels of CD32A and CD36, it was observed that at lower concentrations of anti-oxLDL IgG, CD32A and CD36 contribute about 75% and 25% of cell adhesion, respectively, while at higher concentrations of anti-oxLDL IgG the adhesion is completely CD32A-dependent. CD32A-dependent adhesion was further confirmed with peripheral blood monocytes and platelets that express 2- to 5-fold higher levels of CD36 compared to CD32A. Further, PBMC adhesion to oxLDL-IC-deposited endothelial cells induced secretion of pro-inflammatory chemokines, MCP-1 and IL-8. Our results demonstrate that anti-oxLDL IgG blocks oxLDL interaction with SR such as CD36, whereas oxLDL-IC formation promotes monocyte adhesion and subsequent chemokine release through FcgammaR. These findings suggest a role for FcgammaR-mediated inflammatory cell activation in the progression of atherosclerosis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Antigen-Antibody Complex / metabolism
  • Antigens, CD / metabolism*
  • CD36 Antigens / metabolism*
  • Cell Adhesion / immunology
  • Cell Line
  • Cell Line, Tumor
  • Chemokines / metabolism
  • Endothelial Cells / immunology
  • Endothelial Cells / metabolism
  • Humans
  • Immunoglobulins / metabolism*
  • Immunoglobulins / pharmacology
  • Inflammation / immunology*
  • Lipoproteins, LDL / immunology
  • Lipoproteins, LDL / metabolism*
  • Monocytes / immunology*
  • Receptors, IgG / metabolism*
  • Up-Regulation / drug effects
  • Up-Regulation / immunology

Substances

  • Antigen-Antibody Complex
  • Antigens, CD
  • CD36 Antigens
  • Chemokines
  • Fc gamma receptor IIA
  • Immunoglobulins
  • Lipoproteins, LDL
  • Receptors, IgG
  • oxidized low density lipoprotein