Abstract
Nuclear factor erythroid 2-related factor 2 (Nrf2) is an antioxidant-activated transcription factor that recently emerged as a critical regulator of cellular defense against oxidative and inflammatory lesions. Resveratrol (Res) is a natural phytoalexin that exhibits multiple therapeutic potentials, including antioxidative and anti-inflammatory effects in animals. Paraquat (PQ) is the second most widely used herbicide worldwide, but it selectively accumulates in human lungs to cause oxidative injury and fibrosis with high mortality. Here, we analyzed the molecular mechanism of the fibrogenic response to PQ and its inhibition by Res and Nrf2. PQ dose-dependently caused toxicity in normal human bronchial epithelial cells (BEAS-2B), resulting in mitochondrial damage, oxidative stress, and cell death. Res at 10 μM markedly inhibited PQ toxicity. PQ at 10 μM stimulated production of inflammatory and profibrogenic factors (tumor necrosis factor α, interleukin 6, and transforming growth factor β1) and induced the transformation of normal human lung fibroblasts (WI38-VA13) to myofibroblasts; both effects were inhibited by Res. Res strongly activated the Nrf2 signaling pathway and induced antioxidant response element-dependent cytoprotective genes. On the other hand, knockout or knockdown of Nrf2 markedly increased PQ-induced cytotoxicity, cytokine production, and myofibroblast transformation and abolished protection by Res. The findings demonstrate that Res attenuates PQ-induced reactive oxygen species production, inflammation, and fibrotic reactions by activating Nrf2 signaling. The study reveals a new pathway for molecular intervention against pulmonary oxidative injury and fibrosis.
Footnotes
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
ABBREVIATIONS:
- αSMA
- α smooth muscle actin
- ARE
- antioxidant response element
- DAPI
- 4,6-diamidino-2-phenylindole
- DHE
- dihydroethium
- FBS
- fetal bovine serum
- Ho1
- heme oxygenase 1
- IL
- interleukin
- KO
- knockout
- LPS
- lipopolysaccharide
- MEF
- mouse embryonic fibroblast
- MTDR
- MitoTracker deep red 633
- Nqo1
- NAD(P)H:quinone oxidoreductase
- Nrf2
- nuclear factor erythroid 2-related factor 2
- PCR
- polymerase chain reaction
- PQ
- paraquat
- Res
- resveratrol
- RFU
- relative fluorescence unit
- RLU
- relative light unit
- ROS
- reactive oxygen species
- siRNA
- small interfering RNA
- tBHQ
- tert-butylhydroquinone
- TGF
- transforming growth factor
- TMRE
- tetramethylrhodamine ethyl ester
- TNF
- tumor necrosis factor
- WT
- wild type.
- Received March 9, 2012.
- Accepted April 3, 2012.
- U.S. Government work not protected by U.S. copyright
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