Abstract: Objective To investigate the expression of microRNA125b in acute lung injury induced by sepsis, and its correlation with inflammatory factors. Methods The model rats of acute lung injury were induced by intraperitonealinjection of lipopolysaccharide (LPS) for 4, 8, 12 and 24 h (n=20). The control group was injected with the same amount of normal saline (n=20). The pathological changes of lung tissue were observed by HE staining. The changes of miR-125b,tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were detected by PCR in each group. Pearson correlation analysis was used to show the expression of miR-125b in lung tissue and its correlation with the levels of TNF-α and IL-6. NR8383 cells were cultured and subdivided into subgroups. The blank control group was not stimulated by LPS. The cells were collected after stimulation with LPS for 4 h, 8 h, 12 h and 24 h, and the levels of miR-125b, TNF-α and IL-6 were detected.NR8383 cells were set up into three groups, the negative control group was only transfected with the empty expression plasmid, and the miR-125b mimic group was transfected with the miR-125b mimic expression plasmid. The expression of miR-125b was detected by PCR in each group, and the expression of Notch1 was detected by Western blot assay. Results In the LPS treatment group, the lung tissue was severely hemorrhage, edema and a large amount of inflammatory cell after 24 hours of injection of LPS for 4, 8, and 12 hours in the experimental group, while the levels of TNF-α and IL-6 in thelung tissue were increased. The expression levels of TNF-α and IL-6 reached peak 4 h after LPS injection (P＜0.05).The expression of miR-125b in the lung tissue was negatively correlated with TNF-α and IL-6 in the experimental group (r=-0.599, -0.580, P＜0.05). The expression levels of miR-125b were lower in experiment group than those in the control group after LPS induction for 4 h, 8 h, 12 h and 24 h in the NR8383 cell line, while the expression levels of TNF-α and IL-6 were higher than those in the control group (P＜0.05). Compared with the negative control group, the relative expression level of miR-125b and the relative expression of Notch1 protein in miR-125b mimic group were decreased (P＜0.05), the relative expression of miR-125b in miR-125b inhibitor group was decreased, and the relative expression of Notch1 protein was decreased (P＜0.05). The amount of miR-125b decreased and the relative expression of Notch1 protein increased in miR-125b inhibitor group compared with those of miR-125b mimic group (P＜0.05). Conclusion In the acute lung injury induced by sepsis, microRNA-125b may regulate the expression of Notch1 protein, affect the expression of inflammatory factors TNF-α and IL-6, and participate in the process of immune inflammation regulation.

Key words: sepsis, acute lung injury, tumor necrosis factor-alpha, interleukin-6, microRNA-125b