Elevated atherosclerosis-related gene expression, monocyte activation and microparticle-release are related to increased lipoprotein-associated oxidative stress in familial hypercholesterolemia

PLoS One. 2015 Apr 13;10(4):e0121516. doi: 10.1371/journal.pone.0121516. eCollection 2015.

Abstract

Objective: Animal and in vitro studies have suggested that hypercholesterolemia and increased oxidative stress predisposes to monocyte activation and enhanced accumulation of oxidized LDL cholesterol (oxLDL-C) through a CD36-dependent mechanism. The aim of this study was to investigate the hypothesis that elevated oxLDL-C induce proinflammatory monocytes and increased release of monocyte-derived microparticles (MMPs), as well as up-regulation of CD36, chemokine receptors and proinflammatory factors through CD36-dependent pathways and that this is associated with accelerated atherosclerosis in subjects with heterozygous familial hypercholesterolemia (FH), in particular in the presence of Achilles tendon xanthomas (ATX).

Approach and results: We studied thirty FH subjects with and without ATX and twenty-three healthy control subjects. Intima-media thickness (IMT) and Achilles tendon (AT) thickness were measured by ultrasonography. Monocyte classification and MMP analysis were performed by flow cytometry. Monocyte expression of genes involved in atherosclerosis was determined by quantitative PCR. IMT and oxLDL-C were increased in FH subjects, especially in the presence of ATX. In addition, FH subjects had elevated proportions of intermediate CD14++CD16+ monocytes and higher circulating MMP levels. Stepwise linear regression identified oxLDL-C, gender and intermediate monocytes as predictors of MMPs. Monocyte expression of pro-atherogenic and pro-inflammatory genes regulated by oxLDL-C-CD36 interaction was increased in FH, especially in ATX+ subjects. Monocyte chemokine receptor CX3CR1 was identified as an independent contributor to IMT.

Conclusions: Our data support that lipoprotein-associated oxidative stress is involved in accelerated atherosclerosis in FH, particularly in the presence of ATX, by inducing pro-inflammatory monocytes and increased release of MMPs along with elevated monocyte expression of oxLDL-C-induced atherosclerosis-related genes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Atherosclerosis / complications*
  • Atherosclerosis / genetics
  • Atherosclerosis / immunology*
  • Atherosclerosis / pathology
  • CD36 Antigens / genetics
  • CD36 Antigens / immunology
  • Carotid Intima-Media Thickness
  • Cell-Derived Microparticles / immunology
  • Cell-Derived Microparticles / pathology
  • Cholesterol, LDL / immunology*
  • Female
  • Gene Expression Regulation
  • Humans
  • Hypercholesterolemia / complications*
  • Hypercholesterolemia / genetics
  • Hypercholesterolemia / immunology*
  • Hypercholesterolemia / pathology
  • Lipoproteins, LDL / immunology*
  • Male
  • Middle Aged
  • Monocytes / immunology*
  • Monocytes / pathology
  • Oxidative Stress
  • Receptors, Chemokine / genetics
  • Receptors, Chemokine / immunology

Substances

  • CD36 Antigens
  • Cholesterol, LDL
  • Lipoproteins, LDL
  • Receptors, Chemokine
  • oxidized low density lipoprotein

Grants and funding

This work was supported by The Danish Heart Association and the Novo Nordisk Foundation via Danish PhD School of Molecular Metabolism. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.