C‑reactive protein/oxidized low density lipoprotein/β2‑glycoprotein i complexes induce lipid accumulation and inflammatory reaction in macrophages via p38/mitogen‑activated protein kinase and nuclear factor‑κB signaling pathways

Mol Med Rep. 2016 Oct;14(4):3490-8. doi: 10.3892/mmr.2016.5622. Epub 2016 Aug 11.

Abstract

Oxidized low-density lipoprotein (oxLDL) can bind to β2-glycoprotein I (β2GPI) and C-reactive protein (CRP) to form stable complexes, which exert certain effects in diabetic cardiovascular disease. A previous study by our group has confirmed that the resulting complexes promote atherosclerosis in diabetic BALB/c mice. The present study was designed to investigate the effects and potential mechanisms of oxLDL complexes on lipid accumulation and inflammatory reactions in RAW264.7 macrophages cultured in a hyperglycemic environment. Cultured cells were divided into seven groups, which were treated with phosphate‑buffered saline (control), CRP, β2GPI, oxLDL, CRP/oxLDL, oxLDL/β2GPI or CRP/oxLDL/β2GPI. The results revealed the formation of foam cells in the oxLDL, CRP/oxLDL, oxLDL/β2GPI as well as CRP/oxLDL/β2GPI groups. Compared with oxLDL, the three complexes induced less lipid accumulation (P<0.05) through inhibiting the expression of CD36 mRNA and promoting the expression of and ABCG1 mRNA (P<0.05 vs. oxLDL). Furthermore, the levels of inflammatory factors interleukin (IL)‑1β, IL‑6 and tumor necrosis factor‑α were elevated in the CRP/oxLDL and CRP/oxLDL/β2GPI groups (P>0.05 vs. oxLDL), and obvious effects on p38/mitogen‑activated protein kinase and nuclear factor (NF)‑κB phosphorylation were also observed in these groups (P<0.05 vs. oxLDL). These results suggested that CRP/oxLDL/βG2P1 complexes may induce lipid accumulation and inflammation in macrophages via the p38/MAPK and NF‑κB signaling pathways. However, some differences were observed between the complexes, which may be attributed to the property of each constituent; therefore, further studies are required.

MeSH terms

  • Animals
  • C-Reactive Protein / immunology*
  • Cholesterol / analysis
  • Cholesterol / immunology
  • Inflammation / immunology*
  • Lipids / analysis
  • Lipids / immunology*
  • Lipoproteins, LDL / immunology*
  • MAP Kinase Signaling System
  • Macrophages / immunology*
  • Mice
  • Mitogen-Activated Protein Kinases / immunology
  • NF-kappa B / immunology*
  • RAW 264.7 Cells
  • Signal Transduction
  • beta 2-Glycoprotein I / immunology*

Substances

  • Lipids
  • Lipoproteins, LDL
  • NF-kappa B
  • beta 2-Glycoprotein I
  • oxidized low density lipoprotein
  • C-Reactive Protein
  • Cholesterol
  • Mitogen-Activated Protein Kinases