Nuclear factor erythroid 2-related factor 2 nuclear translocation induces myofibroblastic dedifferentiation in idiopathic pulmonary fibrosis

Antioxid Redox Signal. 2013 Jan 1;18(1):66-79. doi: 10.1089/ars.2011.4240. Epub 2012 Aug 6.

Abstract

Aims: Oxidants have been implicated in the pathophysiology of idiopathic pulmonary fibrosis (IPF), especially in myofibroblastic differentiation. We aimed at testing the hypothesis that nuclear factor erythroid 2-related factor 2 (Nrf2), the main regulator of endogenous antioxidant enzymes, is involved in fibrogenesis via myofibroblastic differentiation. Fibroblasts were cultured from the lungs of eight controls and eight IPF patients. Oxidants-antioxidants balance, nuclear Nrf2 expression, and fibroblast phenotype (α-smooth muscle actin and collagen I expression, proliferation, migration, and contraction) were studied under basal conditions and after Nrf2 knockdown or activation by Nrf2 or Keap1 siRNA transfection. The effects of sulforaphane (SFN), an Nrf2 activator, on the fibroblast phenotype were tested under basal and pro-fibrosis conditions (transforming growth factor β [TGF-β]).

Results: Decreased Nrf2 expression was associated with a myofibroblast phenotype in IPF compared with control fibroblasts. Nrf2 knockdown induced oxidative stress and myofibroblastic differentiation in control fibroblasts. Conversely, Nrf2 activation increased antioxidant defences and myofibroblastic dedifferentation in IPF fibroblasts. SFN treatment decreased oxidants, and induced Nrf2 expression, antioxidants, and myofibroblastic dedifferentiation in IPF fibroblasts. SFN inhibited TGF-β profibrotic deleterious effects in IPF and control fibroblasts and restored antioxidant defences. Nrf2 knockdown abolished SFN antifibrosis effects, suggesting that they were Nrf2 mediated.

Innovation and conclusion: Our findings confirm that decreased nuclear Nrf2 plays a role in myofibroblastic differentiation and that SFN induces human pulmonary fibroblast dedifferentiation in vitro via Nrf2 activation. Thus, Nrf2 could be a novel therapeutic target in IPF.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Aldehydes / metabolism
  • Animals
  • Becaplermin
  • Cell Dedifferentiation*
  • Cell Nucleus / metabolism*
  • Cells, Cultured
  • Collagen Type I / metabolism
  • Epoxide Hydrolases / metabolism
  • Gene Knockdown Techniques
  • Heme Oxygenase-1 / metabolism
  • Humans
  • Idiopathic Pulmonary Fibrosis / metabolism
  • Idiopathic Pulmonary Fibrosis / pathology*
  • Isothiocyanates
  • Lipid Peroxidation
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Myofibroblasts / metabolism*
  • Myofibroblasts / physiology
  • NAD(P)H Dehydrogenase (Quinone) / metabolism
  • NF-E2-Related Factor 2 / genetics
  • NF-E2-Related Factor 2 / metabolism*
  • NF-E2-Related Factor 2 / physiology
  • Oxidative Stress
  • Phenotype
  • Proto-Oncogene Proteins c-sis / physiology
  • RNA, Small Interfering / genetics
  • Thiocyanates / pharmacology
  • Transforming Growth Factor beta / physiology

Substances

  • Aldehydes
  • Collagen Type I
  • Isothiocyanates
  • NF-E2-Related Factor 2
  • NFE2L2 protein, human
  • Proto-Oncogene Proteins c-sis
  • RNA, Small Interfering
  • Thiocyanates
  • Transforming Growth Factor beta
  • Becaplermin
  • HMOX1 protein, human
  • Heme Oxygenase-1
  • NAD(P)H Dehydrogenase (Quinone)
  • NQO1 protein, human
  • Epoxide Hydrolases
  • sulforaphane
  • 4-hydroxy-2-nonenal