Objective  To explore the effect of miR-182-5p on lipopolysaccharide (LPS) induced acute lung injury (ALI) and its molecular mechanism through molecular biological methods.

  Methods  Fluorescence quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression of miR-182-5p and MAPK1 in the LPS-induced ALI model. Dual luciferase reporter gene was used to detect the relationship between miR-182-5p and MAPK1. ALI models were treated with Ad-MAPK1, Ad-miR-182-5p and Ad-MAPK1+Ad-miR-182-5p, respectively, and the changes of lung injury index and pulmonary fibrosis were detected by Hematoxylin-eosin staining (HE staining) and Masson staining. The levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and myeloperoxidase (MPO) in lung tissues of all treatment groups were detected by enzyme-linked immunosorbent assay (ELISA). The expressions of nuclear factor κB(NF-κB) and NF-κB inhibitor protein α (IκBα) were detected by western blot (WB).

  Results  This study showed that the expression level of miR-182-5p gradually increased at 0 to 12 hours after ALI, and then decreased at >12 to 24 hours; the expression level of MAPK1 gradually decreased at 0 to 12 hours and increased at >12 to 24 hours. Further genetic interference of ALI showed that the overexpression of miR-182-5p could significantly down-regulate the lung injury index, lung fibrosis and the levels of pro-inflammatory cytokines, while the overexpression of MAPK1 aggravated the levels of lung injury index, lung fibrosis and pro-inflammatory cytokines. Cell experiments in vitro showed that LPS stimulation significantly increased the protein expression of NF-κB and inhibited the expression of IκBα at the same time. The miR-182-5p was able to inhibit the expression of NF-κB and promote the expression of IκBα; on the contrary, the overexpression of MAPK1 reversed this phenomenon.

  Conclusion  MiR-182-5p plays a therapeutic role in ALI by inhibiting the MAPK/NF-κB signaling pathway, and the data of this study may contribute to an in-depth understanding of the potential molecular mechanism of ALI and the development of new therapeutic methods for ALI.