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HDAC8 Inhibition Ameliorates Pulmonary Fibrosis
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A4349 - HDAC8 Inhibition Ameliorates Pulmonary Fibrosis
Author Block: S. Saito, Y. Zhuang, J. A. Lasky; Medicine, Tulane University, New Orleans, LA, United States.
Purpose of Study: Idiopathic pulmonary fibrosis (IPF) is a deadly lung disease. Histone deacetylase 8 (HDAC8) associates with α-smooth muscle actin (α-SMA) and regulates cell contractility in vascular smooth muscle cells. This study investigates a role for HDAC8 in pulmonary fibrosis, with a particular focus on FMD (fibroblast-myofibroblast differentiation; a key event in the pathogenesis of IPF).
Methods Used: HDAC8 expression in IPF lung tissue was assessed using immunoblots. Localization of α-SMA and HDAC8 in TGF-β1-treated normal human lung fibroblasts (NHLFs) was assessed using immunofluorescent staining. To determine whether HDAC8 regulates TGF-β1-induced contraction, NHLFs were cultured in collagen gel, with or without TGF-β1 ± NCC170 (an HDAC8 selective inhibitor). To assess whether HDAC8 inhibition represses FMD, NHLFs were treated with HDAC8 siRNA or NCC-170 ± TGF-β1; protein and mRNA expression were assessed using immunoblots and qRT-PCR. Chromatin immunoprecipitation (ChIP)-PCR was performed using an antibody against H3K27ac (acetylated H3K27; a known HDAC8 substrate and a marker for active enhancers) on NHLFs treated with or without TGF-β1 ± NCC170. To investigate the effects of HDAC8 inhibition in pulmonary fibrosis in vivo, mice were treated with bleomycin ± NCC170, and lung collagen expression was measured using Masson trichrome staining, qRT-PCR, and immunoblots.
Summary of Results: In IPF lungs, HDAC8 expression was increased and correlated with the disease severity as measured by forced vital capacity. HDAC8 associated with α-SMA in TGF-β1-treated NHLFs. Inhibition of HDAC8 repressed TGF-β1-induced fibroblast contraction and α-SMA protein expression. HDAC8 inhibition also repressed TGF-β1-induced mRNA / protein expression of CTGF and PAI-1, and increased PPAR-γ mRNA / protein expression. ChIP-PCR suggested that TGF-β1-induced loss of H3K27ac at PPAR-γ gene enhancer was ameliorated by HDAC8 inhibition. NCC170 treatment significantly decreased type-1 collagen expression in bleomycin-treated mouse lungs.
Conclusions: HDAC8 expression is altered during lung fibrogenesis. HDAC8 inhibition represses some features of TGF-β1-induced FMD, and increases PPAR-γ mRNA transcription by increasing H3K27 acetylation at enhancer region. The data that an HDAC8 inhibitor ameliorates bleomycin-induced pulmonary fibrosis in mice suggest a therapeutic potential for HDAC8 inhibitors to treat IPF and possibly other fibrotic lung diseases.
Author Block: S. Saito, Y. Zhuang, J. A. Lasky; Medicine, Tulane University, New Orleans, LA, United States.
Purpose of Study: Idiopathic pulmonary fibrosis (IPF) is a deadly lung disease. Histone deacetylase 8 (HDAC8) associates with α-smooth muscle actin (α-SMA) and regulates cell contractility in vascular smooth muscle cells. This study investigates a role for HDAC8 in pulmonary fibrosis, with a particular focus on FMD (fibroblast-myofibroblast differentiation; a key event in the pathogenesis of IPF).
Methods Used: HDAC8 expression in IPF lung tissue was assessed using immunoblots. Localization of α-SMA and HDAC8 in TGF-β1-treated normal human lung fibroblasts (NHLFs) was assessed using immunofluorescent staining. To determine whether HDAC8 regulates TGF-β1-induced contraction, NHLFs were cultured in collagen gel, with or without TGF-β1 ± NCC170 (an HDAC8 selective inhibitor). To assess whether HDAC8 inhibition represses FMD, NHLFs were treated with HDAC8 siRNA or NCC-170 ± TGF-β1; protein and mRNA expression were assessed using immunoblots and qRT-PCR. Chromatin immunoprecipitation (ChIP)-PCR was performed using an antibody against H3K27ac (acetylated H3K27; a known HDAC8 substrate and a marker for active enhancers) on NHLFs treated with or without TGF-β1 ± NCC170. To investigate the effects of HDAC8 inhibition in pulmonary fibrosis in vivo, mice were treated with bleomycin ± NCC170, and lung collagen expression was measured using Masson trichrome staining, qRT-PCR, and immunoblots.
Summary of Results: In IPF lungs, HDAC8 expression was increased and correlated with the disease severity as measured by forced vital capacity. HDAC8 associated with α-SMA in TGF-β1-treated NHLFs. Inhibition of HDAC8 repressed TGF-β1-induced fibroblast contraction and α-SMA protein expression. HDAC8 inhibition also repressed TGF-β1-induced mRNA / protein expression of CTGF and PAI-1, and increased PPAR-γ mRNA / protein expression. ChIP-PCR suggested that TGF-β1-induced loss of H3K27ac at PPAR-γ gene enhancer was ameliorated by HDAC8 inhibition. NCC170 treatment significantly decreased type-1 collagen expression in bleomycin-treated mouse lungs.
Conclusions: HDAC8 expression is altered during lung fibrogenesis. HDAC8 inhibition represses some features of TGF-β1-induced FMD, and increases PPAR-γ mRNA transcription by increasing H3K27 acetylation at enhancer region. The data that an HDAC8 inhibitor ameliorates bleomycin-induced pulmonary fibrosis in mice suggest a therapeutic potential for HDAC8 inhibitors to treat IPF and possibly other fibrotic lung diseases.
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