Song J, Heijink I H, Kistemaker L E M, Reinders-Luinge M, Kooistra W, Noordhoek J A, Gosens R, Brandsma C A, Timens W, Hiemstra P S, Rots M G, Hylkema M N
Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
GRIAC Research Institute, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Clin Epigenetics. 2017 Apr 24;9:42. doi: 10.1186/s13148-017-0341-7. eCollection 2017.
Goblet cell metaplasia, a common feature of chronic obstructive pulmonary disease (COPD), is associated with mucus hypersecretion which contributes to the morbidity and mortality among patients. Transcription factors SAM-pointed domain-containing Ets-like factor (SPDEF) and forkhead box protein A2 (FOXA2) regulate goblet cell differentiation. This study aimed to (1) investigate DNA methylation and expression of and during goblet cell differentiation and (2) compare this in airway epithelial cells from patients with COPD and controls during mucociliary differentiation.
To assess DNA methylation and expression of and during goblet cell differentiation, primary airway epithelial cells, isolated from trachea (non-COPD controls) and bronchial tissue (patients with COPD), were differentiated by culture at the air-liquid interface (ALI) in the presence of cytokine interleukin (IL)-13 to promote goblet cell differentiation.
We found that expression was induced during goblet cell differentiation, while expression was decreased. Importantly, CpG number 8 in the promoter was hypermethylated upon differentiation, whereas DNA methylation of promoter was not changed. In the absence of IL-13, COPD-derived ALI-cultured cells displayed higher expression than control-derived ALI cultures, whereas no difference was found for expression. This was accompanied with hypomethylation of CpG number 6 in the promoter and also hypomethylation of CpG numbers 10 and 11 in the promoter.
These findings suggest that aberrant DNA methylation of and is one of the factors underlying mucus hypersecretion in COPD, opening new avenues for epigenetic-based inhibition of mucus hypersecretion.
杯状细胞化生是慢性阻塞性肺疾病（COPD）的一个常见特征，与黏液分泌过多有关，而黏液分泌过多会导致患者的发病率和死亡率升高。转录因子含SAM结构域的Ets样因子（SPDEF）和叉头框蛋白A2（FOXA2）调节杯状细胞分化。本研究旨在：（1）研究杯状细胞分化过程中SPDEF和FOXA2的DNA甲基化及表达情况；（2）比较COPD患者和对照组气道上皮细胞在黏液纤毛分化过程中的上述情况。
为评估杯状细胞分化过程中SPDEF和FOXA2的DNA甲基化及表达情况，从气管（非COPD对照组）和支气管组织（COPD患者）分离出的原代气道上皮细胞，在细胞因子白细胞介素（IL）-13存在的情况下，通过气液界面（ALI）培养进行分化，以促进杯状细胞分化。
我们发现，杯状细胞分化过程中SPDEF表达被诱导，而FOXA2表达降低。重要的是，分化时SPDEF启动子中的第8个CpG位点发生高甲基化，而FOXA2启动子的DNA甲基化未发生变化。在没有IL-13的情况下，COPD来源的ALI培养细胞比对照组来源的ALI培养细胞显示出更高的SPDEF表达，而FOXA2表达未发现差异。这伴随着SPDEF启动子中第6个CpG位点的低甲基化，以及FOXA2启动子中第10和11个CpG位点的低甲基化。
这些发现表明，SPDEF和FOXA2的异常DNA甲基化是COPD中黏液分泌过多的潜在因素之一，为基于表观遗传学抑制黏液分泌过多开辟了新途径。
