Respiratory Cell and Molecular Biology, Woolcock Institute of Medical Research, Glebe, New South Wales, Australia
School of Life Sciences, University of Technology Sydney, Ultimo, New South Wales, Australia.
Thorax. 2021 Jul;76(7):647-655. doi: 10.1136/thoraxjnl-2020-215092. Epub 2021 Jan 27.
In COPD, small airway fibrosis occurs due to increased extracellular matrix (ECM) deposition in and around the airway smooth muscle (ASM) layer. Studies of immune cells and peripheral lung tissue have shown that epigenetic changes occur in COPD but it is unknown whether airway mesenchymal cells are reprogrammed.
Determine if COPD ASM cells have a unique epigenetic response to profibrotic cytokine transforming growth factor β1 (TGF-β1).
Primary human ASM cells from COPD and non-COPD smoking patients were stimulated with TGF-β1. Gene array analysis performed to identify differences in ECM expression. Airway accumulation of collagen 15α1 and tenascin-C proteins was assessed. Aforementioned ASM cells were stimulated with TGF-β1 ± epigenetic inhibitors with qPCR quantification of and . Global histone acetyltransferase (HAT) and histone deacetylase (HDAC) activity were assessed. chromatin immunoprecipitation (ChIP)-qPCR for histone H3 and H4 acetylation at and promoters was carried out. Effects of bromoterminal and extraterminal domain (BET) inhibitor JQ1(+) on expression and acetylation of ECM target genes were assessed.
COPD ASM show significantly higher and expression in vitro and the same trend for higher levels of collagen 15α1 and tenascin-c deposited in COPD airways in vivo. Epigenetic screening indicated differential response to HDAC inhibition. ChIP-qPCR revealed histone H4 acetylation at and promoters in COPD ASM only. ChIP-qPCR found JQ1(+) pretreatment significantly abrogated TGF-β1 induced histone H4 acetylation at and .
BET protein binding to acetylated histones is important in TGF-β1 induced expression of and and maintenance of TGF-β1 induced histone H4 acetylation in cell progeny.
在 COPD 中，由于气道平滑肌（ASM）层内外细胞外基质（ECM）的沉积增加，小气道发生纤维化。对免疫细胞和外周肺组织的研究表明，COPD 中存在表观遗传改变，但尚不清楚气道间充质细胞是否被重新编程。
确定 COPD ASM 细胞对致纤维化细胞因子转化生长因子-β1（TGF-β1）是否存在独特的表观遗传反应。
用 TGF-β1 刺激 COPD 和非 COPD 吸烟患者的原代人 ASM 细胞。进行基因阵列分析以鉴定 ECM 表达的差异。评估胶原蛋白 15α1 和 tenascin-C 蛋白在气道中的积累。用 TGF-β1 ± 表观遗传抑制剂刺激上述 ASM 细胞，并用 qPCR 定量 和 。评估全局组蛋白乙酰转移酶（HAT）和组蛋白去乙酰化酶（HDAC）活性。进行染色质免疫沉淀（ChIP）-qPCR，检测 和 启动子处组蛋白 H3 和 H4 的乙酰化。评估溴端和末端外结构域（BET）抑制剂 JQ1(+)对 ECM 靶基因表达和乙酰化的影响。
COPD ASM 在体外表现出明显更高的 和 表达，并且在体内 COPD 气道中沉积的胶原蛋白 15α1 和 tenascin-c 也有相同的趋势。表观遗传筛选表明对 HDAC 抑制有不同的反应。ChIP-qPCR 仅在 COPD ASM 中显示 和 启动子处的组蛋白 H4 乙酰化。ChIP-qPCR 发现 JQ1(+)预处理显著阻断了 TGF-β1 诱导的 和 启动子处组蛋白 H4 乙酰化。
BET 蛋白与乙酰化组蛋白的结合在 TGF-β1 诱导的 和 表达以及 TGF-β1 诱导的细胞后代中组蛋白 H4 乙酰化的维持中很重要。
