Gan Lixing, Li Chengye, Wang Jian, Guo Xuejun
Department of Respiratory Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai.
Department of Respiratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou.
Int J Chron Obstruct Pulmon Dis. 2016 Nov 7;11:2765-2773. doi: 10.2147/COPD.S113978. eCollection 2016.
Studies have suggested that histone modification has a positive impact on various aspects associated with the progression of COPD. Histone deacetylase 2 (HDAC2) suppresses proinflammatory gene expression through deacetylation of core histones.
To investigate the effect of histone modification on the expression of chemokines in type II alveolar epithelial cells (AEC II) in a rat COPD model and regulation of HDAC2 expression by curcumin in comparison with corticosteroid.
The rat COPD model was established by cigarette smoke exposure and confirmed by histology and pathophysioloy. AEC II were isolated and cultured in vitro from the COPD models and control animals. The cells were treated with curcumin, corticosteroid, or trichostatin A, and messenger RNA (mRNA) expression of interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-2α (MIP-2α) was assessed by quantitative real-time polymerase chain reaction (RT-PCR). The expression of HDAC2 was measured by Western blot. Chromatin immunoprecipitation was used to detect H3/H4 acetylation and H3K9 methylation in the promoter region of three kinds of chemokine genes (IL-8, MCP-1, and MIP-2α).
Compared to the control group, the mRNAs of MCP-1, IL-8, and MIP-2α were upregulated 4.48-fold, 3.14-fold, and 2.83-fold, respectively, in the AEC II from COPD model. The protein expression of HDAC2 in the AEC II from COPD model was significantly lower than from the control group (<0.05). The decreased expression of HDAC2 was negatively correlated with the increased expression of IL-8, MCP-1, and MIP-2α mRNAs (all <0.05). The level of H3/H4 acetylation was higher but H3K9 methylation in the promoter region of chemokine genes was lower in the cells from COPD model than from the control group (all <0.05). Curcumin downregulated the expression of MCP-1, IL-8, and MIP-2α, and the expression was further enhanced in the presence of corticosteroid. Moreover, curcumin restored HDAC2 expression, decreased the levels of H3/H4 acetylation, and increased H3K9 methylation in the promoter region of chemokine in the presence or absence of dexamethasone (all <0.05).
Curcumin may suppress chemokines and restore corticosteroid resistance in COPD through modulating HDAC2 expression and its effect on histone modification.
研究表明，组蛋白修饰对慢性阻塞性肺疾病（COPD）进展相关的各个方面具有积极影响。组蛋白去乙酰化酶2（HDAC2）通过核心组蛋白的去乙酰化抑制促炎基因表达。
在大鼠COPD模型中研究组蛋白修饰对II型肺泡上皮细胞（AEC II）中趋化因子表达的影响，以及与皮质类固醇相比，姜黄素对HDAC2表达的调节作用。
通过香烟烟雾暴露建立大鼠COPD模型，并通过组织学和病理生理学进行确认。从COPD模型和对照动物中分离并体外培养AEC II。用姜黄素、皮质类固醇或曲古抑菌素A处理细胞，通过定量实时聚合酶链反应（RT-PCR）评估白细胞介素-8（IL-8）、单核细胞趋化蛋白-1（MCP-1）和巨噬细胞炎性蛋白-2α（MIP-2α）的信使核糖核酸（mRNA）表达。通过蛋白质免疫印迹法检测HDAC2的表达。采用染色质免疫沉淀法检测三种趋化因子基因（IL-8、MCP-1和MIP-2α）启动子区域的H3/H4乙酰化和H3K9甲基化。
与对照组相比，COPD模型AEC II中MCP-1、IL-8和MIP-2α的mRNA分别上调了4.48倍、3.14倍和2.83倍。COPD模型AEC II中HDAC2的蛋白表达明显低于对照组（<0.05）。HDAC2表达的降低与IL-8、MCP-1和MIP-2α mRNA表达的增加呈负相关（均<0.05）。与对照组相比，COPD模型细胞中趋化因子基因启动子区域的H3/H4乙酰化水平较高，但H3K9甲基化水平较低（均<0.05）。姜黄素下调了MCP-1、IL-8和MIP-2α的表达，在存在皮质类固醇的情况下表达进一步增强。此外，无论是否存在地塞米松，姜黄素均可恢复HDAC2表达，降低H3/H4乙酰化水平，并增加趋化因子启动子区域的H3K9甲基化（均<0.05）。
姜黄素可能通过调节HDAC2表达及其对组蛋白修饰的作用来抑制COPD中的趋化因子并恢复皮质类固醇抵抗。
