尘肺患者外周血胸腺细胞分化抗原-1 DNA甲基化的改变及意义

Change and significance of thymocyte differentiation antigen-1 DNA methylation in peripheral blood of patients with pneumoconiosis

[目的 ]尘肺是严重影响我国职业人群健康的一种发病率较高的职业病。通过检测尘肺患者外周血胸腺细胞分化抗原-1(Thy-1)DNA甲基化水平,旨在探讨其与尘肺发病的关系。[方法 ]对84例确诊为尘肺病的男性患者以及具有相同接尘史且同地点工作的75例健康男性工人进行调查。尘肺患者分为煤工尘肺组(40人)和矽肺组(44人),健康工人作为对照组。在知情同意的情况下收集血液样本进行研究。采用ELISA法检测人胶原蛋白Ⅰ(COL-Ⅰ)、胶原蛋白Ⅱ(ICOL-Ⅲ)、Smad蛋白2/3(Smad2/3)、转化生长因子-β1(TGF-β1)、肿瘤坏死因子-α(TNF-α)蛋白的表达,qRT-PCR法检测DNA甲基转移酶1(DNMT1)、DNA甲基转移酶3A(DNMT3A)、DNA甲基转移酶3B(DNMT3B)及甲基结合蛋白-2(MeCP2)基因mRNA的表达,巢式降落式甲基化特异性PCR法检测Thy-1 DNA甲基化水平。[结果 ]矽肺组工人COL-Ⅰ、COL-Ⅲ蛋白表达水平高于煤工尘肺组和对照组(P <0.05),后两者间差异无统计学意义(P> 0.05)。矽肺组工人Smad2/3、TGF-β1、TNF-α,煤工尘肺组工人TGF-β1、TNF-α蛋白表达水平均较对照组提高(P <0.05),且矽肺组Smad2/3、TGF-β1蛋白表达水平也高于煤工尘肺组(P <0.05)。甲基转移酶中:DNMT1、DNMT3A基因mRNA表达水平3组间未呈现差异(P> 0.05),但煤工尘肺组、矽肺组DNMT3B基因mRNA表达较对照组升高(P <0.05)。矽肺组MeCP2基因的mRNA表达也较对照组升高(P <0.05)。与对照组相比,煤工尘肺组、矽肺组工人Thy-1 DNA甲基化水平均升高(P <0.05)。Thy-1 DNA甲基化水平与TGF-β1、Smad2/3、TNF-α蛋白表达呈正相关关系(r=0.25、0.17、0.31,均P <0.05)。[结论]基于尘肺患者Thy-1 DNA甲基化的表达检测,本研究认为Thy-1 DNA甲基化水平发生变化,可能是调控尘肺病发展进程中表观遗传学机制之一。

[Objective] Pneumoconiosis seriously affects the occupational health of Chinese occupational population with a high incidence rate. By detecting the DNA methylation level of peripheral blood thymocyte differentiation antigen 1(Thy-1) in pneumoconiosis patients, this study explores its relationship with pneumoconiosis.[Methods] Male patients diagnosed with pneumoconiosis were selected as a coal worker’s pneumoconiosis group(40 cases) and a silicosis group(44 cases), and another 75 healthy male coal miners working in the same place with similar dust exposure history were selected as the control group. The protein expressions of collagen Ⅰ(COL-Ⅰ), collagen Ⅲ(COL-Ⅲ), Smad2/3,transforming growth factor β1(TGF-β1), tumor necrosis factor α(TNF-α) were detected by ELISA;the mRNA expressions of DNA methyltransferase 1(DNMT1), DNA methyltransferase 3 A(DNMT3 A), DNA methyltransferase 3 B(DNMT3 B), and methyl CpG binding protein 2(MeCP2)were detected by qRT-PCR;the methylation level of Thy-1 was detected by nested methylation specific PCR(nM-PCR).[Results] The expression levels of COL-Ⅰ and COL-Ⅲ protein in the silicosis group were higher than those in the coal workers’ pneumoconiosis group and the control group(P < 0.05), but the proteinexpression levels were not different between the coal workers’ pneumoconiosis group and the control group(P > 0.05). The silicosis group showed higher levels of Smad2/3, TGF-β1, and TNF-α and the coal workers’ pneumoconiosis group showed higher levels of TGF-β1 and TNF-α than the control group(P < 0.05);the silicosis group also showed higher levels of Smad2/3 and TGF-β1 than the coal workers’ pneumoconiosis group(P < 0.05). No differences in the mRNA expression levels of DNMT1 and DNMT3 A were found among the three groups(P > 0.05), but the DNMT3 A mRNA expression levels were higher in the coal workers’ pneumoconiosis group and the silicosis group than in the control group(P < 0.05). Compared with the control group, the silicosis group showed a higher MeCP2 mRNA expression level(P < 0.05), and both the coal workers’ pneumoconiosis group and the silicosis groupshowed a higher level of Thy-1 methylation level(P < 0.05). Thy-1 methylation level was positively correlated with TGF-β1, Smad2/3, and TNF-α protein expression levels(r=0.25, 0.17, and 0.31, respectively, Ps < 0.05).[Conclusion] Altered Thy-1 DNA methylation level in peripheral blood of patients with pneumoconiosis might be an important epigenetic mechanism during the development of pneumoconiosis.