Role of DNA methyltransferase in acute lung injury in septic mice / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of DNA methyltransferase in acute lung injury in septic mice.Methods:Forty-eight healthy male C57BL/6 mice, aged 6-8 weeks, weighing 20-25 g, were divided into 4 groups ( n=12 each) using a random number table method: sham operation group (group Sham), sham operation+ DNA methyltransferase inhibitor group (group Sham+ 5-Aza), sepsis group (group Sepsis) and sepsis+ DNA methyltransferase inhibitor group (group Sepsis+ 5-Aza). Sepsis model was developed by cecal ligation and puncture (CLP) in anesthetized mice.Mice were sacrificed at 24 h after CLP, and lung tissues were obtained, DNA was extracted to determine the global DNA methylation by colorimetry, and RNA was extracted to detect the expression of DNA methyltransferase (DNMTl, DNMT3a, DNMT3b) mRNA by real-time fluorescent quantitative polymerase chain reaction, the wet/dry lung weight ratio (W/D ratio) was measured, the histopathological changes of lung tissues were determined by HE staining, the contents of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), high-mobility group box 1 protein (HMGB1) and malondialdehyde (MDA) and activities of superoxide dismutase (SOD) and catalase were measured by enzyme-linked immunosorbent assay. Results:Compared with group Sham, the global DNA methylation was significantly increased, the expression of DNMT1 and DNMT3a mRNA was up-regulated, the lung injury score, W/D ratio, and contents of IL-6, TNF-α, HMGB1 and MDA were increased, and activities of SOD and CAT were decreased at 24 h after CLP in group Sepsis and group Sepsis+ 5-Aza ( P<0.05), and no significant change was found in the indexes mentioned above in group Sham+ 5-Aza ( P>0.05). Compared with group Sepsis, the global DNA methylation was significantly decreased, the expression of DNMT1 and DNMT3a mRNA was down-regulated, the lung injury score, W/D ratio, contents of IL-6, TNF-α, HMGB1 and MDA were decreased, and the activities of SOD and CAT were increased in group Sepsis+ 5-Aza ( P<0.05). Conclusions:DNA hypermethylation mediated by DNMT1 and DNMT3a is involved in the process of acute lung injury in septic mice.