NADPH oxidase 4 regulates vascular inflammation in aging and atherosclerosis

J Mol Cell Cardiol. 2017 Jan:102:10-21. doi: 10.1016/j.yjmcc.2016.12.004. Epub 2016 Dec 14.

Abstract

We recently reported that increased NADPH oxidase 4 (NOX4) expression and activity during aging results in enhanced cellular and mitochondrial oxidative stress, vascular inflammation, dysfunction, and atherosclerosis. The goal of the present study was to elucidate the molecular mechanism(s) for these effects and determine the importance of NOX4 modulation of proinflammatory gene expression in mouse vascular smooth muscle cells (VSMCs). A novel peptide-mediated siRNA transfection approach was used to inhibit Nox4 expression with minimal cellular toxicity. Using melittin-derived peptide p5RHH, we achieved significantly higher transfection efficiency (92% vs. 85% with Lipofectamine) and decreased toxicity (p<0.001 vs. Lipofectamine in MTT and p<0.0001 vs. Lipofectamine in LDH assays) in VSMCs. TGFβ1 significantly upregulates Nox4 mRNA (p<0.01) and protein (p<0.01) expression in VSMCs. p5RHH-mediated Nox4 siRNA transfection greatly attenuated TGFβ1-induced upregulation of Nox4 mRNA (p<0.01) and protein (p<0.0001) levels and decreased hydrogen peroxide production (p<0.0001). Expression of pro-inflammatory genes Ccl2, Ccl5, Il6, and Vcam1 was significantly upregulated in VSMCs in several settings cells isolated from aged vs. young wild-type mice, in atherosclerotic arteries of Apoe-/- mice, and atherosclerotic human carotid arteries and correlated with NOX4 expression. p5RHH-mediated Nox4 siRNA transfection significantly attenuated the expression of these pro-inflammatory genes in TGFβ1-treated mouse VSMCs, with the highest degree of inhibition in the expression of Il6. p5RHH peptide-mediated knockdown of TGFβ-activated kinase 1 (TAK1, also known as Map3k7), Jun, and Rela, but not Nfkb2, downregulated TGFβ1-induced Nox4 expression in VSMCs. Together, these data demonstrate that increased expression and activation of NOX4, which might result from increased TGFβ1 levels seen during aging, induces a proinflammatory phenotype in VSMCs, enhancing atherosclerosis.

Keywords: Atherosclerosis; Cytokines; Inflammation; Nanoparticles; Reactive oxygen species.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aging / genetics*
  • Aging / metabolism
  • Animals
  • Atherosclerosis / genetics*
  • Atherosclerosis / metabolism
  • Atherosclerosis / pathology
  • Biomarkers
  • Carotid Arteries / metabolism
  • Carotid Arteries / pathology
  • Cell Survival / genetics
  • Cytokines / genetics
  • Cytokines / metabolism
  • Disease Models, Animal
  • Gene Knockdown Techniques
  • Humans
  • Hydrogen Peroxide / metabolism
  • Inflammation Mediators / metabolism
  • MAP Kinase Kinase Kinases / metabolism
  • Male
  • Mice
  • Mice, Knockout
  • Mitochondria / metabolism
  • Muscle, Smooth, Vascular / metabolism
  • Myocytes, Smooth Muscle / metabolism
  • NADPH Oxidase 4
  • NADPH Oxidases / genetics*
  • NADPH Oxidases / metabolism
  • NF-kappa B / metabolism
  • RNA Interference
  • RNA, Small Interfering / genetics
  • Reactive Oxygen Species / metabolism
  • Vasculitis / etiology*
  • Vasculitis / metabolism
  • Vasculitis / pathology

Substances

  • Biomarkers
  • Cytokines
  • Inflammation Mediators
  • NF-kappa B
  • RNA, Small Interfering
  • Reactive Oxygen Species
  • Hydrogen Peroxide
  • NADPH Oxidase 4
  • NADPH Oxidases
  • Nox4 protein, mouse
  • MAP Kinase Kinase Kinases
  • MAP kinase kinase kinase 7