RESUMO
Aim To investigate the effect of forkhead transcription factors of O classl (FoxO1) on lipopolysaccharide (LPS) -induced acute lung injury and its regulatory mechanism. Methods The model of acute lung injury (ALI) was simulated by LPS. HE staining was used to observe the pathological changes of lung tissues. The contents of tumor necrosis factor a (TNF-a) and interleukin-6 (IL-6) in lung tissues were determined by ELISA. The expression of FoxOl in mouse lung tissues was observed by immunohistochemical staining. The phosphorylation levels of FoxOl, DNA methyltransferase and p38 MAPK were detected by Western blot. The mRNA levels of FoxOl, IL-6, TNF-a and DNA methyltransferase were detected by qRT-PCR. DNA methylation in FoxOl promoter region in lung tissues was detected by nested methylation specific PCR (nMS-PCR). Pulmonary vascular endothelial cells (PVECs) were cultured and transfected with FoxOl siRNA, and the phosphorylation of p38 MAPK was detected by Western blot. The correlation between FoxOl methylation level and inflammatory factors was analyzed by Pearson method. Results Compared with control group, alveolar inflammatory cells increased significantly in LPS group, and pulmonary edema and hyperemia were obvious. TNF-α and IL-6 levels increased by 52. 2% and 150. 4% (P < 0. 05), respectively. The phosphorylation level of p38 MAPK and FoxOl expression increased by 134. 1% and 61. 8% (P < 0. 05), respectively, while the DNA methylation level of Fox0l promoter region decreased by 17. 2% (P < 0. 05). After transfection of FoxOl siRNA in vitro, the phosphorylation level of p38 decreased. Pearson analysis showed that FoxOl methylation level was negatively correlated with inflammatory factors. Conclusion The regulation of FoxOl/p3 8 MAPK signaling pathway by hypomethylation of FoxOl promoter is an important mechanism of LPS-induced acute lung injury.