LDL accelerates monocyte to macrophage differentiation: Effects on adhesion and anoikis

Atherosclerosis. 2016 Mar:246:177-86. doi: 10.1016/j.atherosclerosis.2016.01.002. Epub 2016 Jan 5.

Abstract

Background and aims: High LDL triggers dyslipidemia and atherosclerosis, a chronic inflammatory disease with participation of the innate immunity system. Monocytes are recruited to areas of LDL-induced endothelial damage and initiate differentiation. This study was aimed to investigate the effects of LDL on the early transitional stages of monocyte differentiation into macrophages.

Methods: Blood monocytes, isolated from healthy donors by their adhesion properties, were exposed to native-LDL (1.80 mg/mL) for 48-h. Monocyte phenotype was assessed at transcript and miRNA levels by real-time PCR. Protein-expression was determined by western-blot and flow-cytometry.

Results: CD14 time-dependently decreased in adhered monocytes, reaching a >4 fold decrease at transcript- and protein-levels after 7-days in culture when cells were already differentiated into macrophages. At 4-days differentiation, monocytes exposed to LDL reduced CD14-transcrition >1.5 fold in mRNA (p = 0.002) and 34% CD14-protein (p = 0.039), whereas increased in CD16-expression (p = 0.019). Besides, LDL induced a significant increase in integrin CD49c (α3-subunit) at mRNA (>2 fold, p = 0.008) and protein (>3 fold, p = 0.045) level and a decrease in the apoptosis-effectors CASP8 and CASP3 (p = 0.002 and p = 0.035, respectively) as well as in the precursor form of the death-receptor DR5 (p = 0.045) without affecting its mRNA-expression level, suggesting a LDL-dependent post-transcriptional regulation of DR5. In silico prediction analysis indicated miR-126-3p as a candidate to regulate DR5-expression and miR-126-3p was shown affected by LDL reaching a significant increase (p = 0.033).

Conclusions: In differentiating human monocytes, LDL stimulates expression of cell-adhesion molecules and downregulates apoptosis-effectors, regulating anoikis and survival programs in the early stage macrophages.

Keywords: Anoikis; Atherosclerosis; Integrins; Monocyte; microRNAs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anoikis / drug effects*
  • Cell Adhesion / drug effects*
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / metabolism
  • Cell Transdifferentiation / drug effects*
  • Cells, Cultured
  • GPI-Linked Proteins / genetics
  • GPI-Linked Proteins / metabolism
  • Humans
  • Integrin alpha3 / genetics
  • Integrin alpha3 / metabolism
  • Lipopolysaccharide Receptors / genetics
  • Lipopolysaccharide Receptors / metabolism
  • Lipoproteins, LDL / pharmacology*
  • Macrophages / drug effects*
  • Macrophages / metabolism
  • Macrophages / pathology
  • MicroRNAs / genetics
  • MicroRNAs / metabolism
  • Monocytes / drug effects*
  • Monocytes / metabolism
  • Monocytes / pathology
  • Phenotype
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptors, IgG / genetics
  • Receptors, IgG / metabolism
  • Receptors, TNF-Related Apoptosis-Inducing Ligand / genetics
  • Receptors, TNF-Related Apoptosis-Inducing Ligand / metabolism
  • Time Factors
  • Transcription, Genetic / drug effects

Substances

  • Cell Adhesion Molecules
  • FCGR3B protein, human
  • GPI-Linked Proteins
  • Integrin alpha3
  • Lipopolysaccharide Receptors
  • Lipoproteins, LDL
  • MicroRNAs
  • RNA, Messenger
  • Receptors, IgG
  • Receptors, TNF-Related Apoptosis-Inducing Ligand
  • TNFRSF10B protein, human