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 3A (DNMT3A), DNA methyltransferase 3B (DNMT3B), 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 protein expression 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 DNMT3A were found among the three groups (P>0.05), but the DNMT3A 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.
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