CRP enhances soluble LOX-1 release from macrophages by activating TNF-α converting enzyme

J Lipid Res. 2011 May;52(5):923-33. doi: 10.1194/jlr.M015156. Epub 2011 Mar 1.

Abstract

Circulating levels of soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) play an important role in the development and progression of atherosclerosis. We hypothesized that the inflammatory marker C-reactive protein (CRP) might stimulate sLOX-1 release by activating tumor necrosis factor-α converting enzyme (TACE). Macrophages differentiated from THP-1 cells were stimulated with TNF-α and further treated with CRP in the absence or presence of specific inhibitors or small interfering RNA (siRNA). Our results showed that CRP increased sLOX-1 release from activated macrophages in a dose-dependent manner and that these effects were regulated by Fc γ receptor II (FcγRII)-mediated p47(phox) phosphorylation, reactive oxygen species (ROS) production, and TACE activation. CRP also enhanced sLOX-1 release from macrophages derived from peripheral blood mononuclear cells (PBMC) of patients with acute coronary syndrome (ACS). Pretreatment with antibody against FcγRII or with CD32 siRNA, p47(phox) siRNA, apocynin, N-acetylcysteine, tumor necrosis factor-α protease inhibitor 1 (TAPI-1) or TACE siRNA attenuated sLOX-1 release induced by CRP. CRP also elevated serum sLOX-1 levels in a rabbit model of atherosclerosis. Thus, CRP might stimulate sLOX-1 release, and the underlying mechanisms possibly involved FcγRII-mediated p47(phox) phosphorylation, ROS production, and TACE activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADAM Proteins / metabolism*
  • ADAM17 Protein
  • Animals
  • Blotting, Western
  • C-Reactive Protein / pharmacology*
  • Cell Line, Tumor
  • Enzyme Activation / drug effects
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Macrophages / drug effects*
  • Macrophages / metabolism*
  • Polymerase Chain Reaction
  • RNA Interference
  • Rabbits
  • Reactive Oxygen Species
  • Scavenger Receptors, Class E / metabolism*
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • OLR1 protein, human
  • Reactive Oxygen Species
  • Scavenger Receptors, Class E
  • Tumor Necrosis Factor-alpha
  • C-Reactive Protein
  • ADAM Proteins
  • ADAM17 Protein
  • ADAM17 protein, human