Abstract: Objective To investigate the effects of miR-27a on lung pathology, inflammatory factors, oxidative stress indices and peroxisome proliferator activated receptor γ(PPAR-γ) protein expression in septic lung injury rats. Methods Rats were randomly divided into sham group, sepsis rat model group (sepsis group), miR-27a NC plasmid intervention group (NC group) and miR-27a inhibitor plasmid intervention group (miR-27a group), with 10 rats in each. Inflammatory factors and oxidative stress indexes were assessed by ELISA; Wet/dry mass ratio of lung tissue was compared; Pathological changes of lung tissue were microscoped with HE staining; miR-27a and PPAR-γ expression in lung tissue were detected by Western blot. Results Serum level of TNF-α, IL-6 and MDA in the sepsis group was higher than that in the sham group, while the superoxide dismutase(SOD) activity significantly decreased (P＜0.05). The contents of TNF-α, IL-6, and MDA in miR-27a group were significantly less than those in the sepsis group, while the SOD activity was significantly higher(P＜0.05). Compared with the sham group, the wet/dry weight ratios of lung tissues in the sepsis group were increased (P＜0.05). Compared with the sepsis group, the wet/dry weight ratio of lung tissues in the miR-27a group was significantly decreased (P＜0.05). A large number of vascular endothelial cells, alveolar epithelial cells, and macrophages with positive expression of PPAR-γ were found in the lung tissues from sham group. The expression of PPAR-γ in the sepsis group was decreased compared with that in the sham group, and the expression of PPAR-γ in the lung tissues of the miR-27a group was significantly increased(P＜0.05). The expression of miR-27a in lung tissues of rats from sepsis group was significantly higher than those in the sham group, and the concentration of PPAR-γ protein was lower than that in the sham group (P＜0.05). Conclusions Down-regulation of miR-27a may reduce lung injury in septic rats.

Key words: miR-27a, sepsis, lung injury, inflammatory factors, peroxisome proliferator activated receptor γ(PPAR-γ)