Overexpression of miR-145-5p alleviated LPS-induced acute lung injury.

Acute lung injury (ALI) is a disease with high incidence and no effective therapeutic treatments. miR- 145-5p has been reported to be aberrantly expressed in lung injury tissues, suggesting a potential role in the progression and development of ALI. To validate this hypothesis and explore the underlying mechanism, a mouse model of ALI was established using lipopolysaccharide (LPS). Hematoxylin and eosin (Hand E) staining verified the successful establishment of mouse model with ALI. Levels of interleukin (IL)-1β, IL- 6, tumor necrosis factor α (TNF-α) and myeloperoxidase (MPO) were detected by both enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. Mouse type II alveolar epithelial cells (AT II) were isolated and treated with LPS. miR-145-5p was significantly down-regulated both in mice with acute lung injury and LPS-induced AT II cells. Dual luciferase assays confirmed miR-145-5p could target and regulate Toll Like Receptor 4 (TLR4). Further analysis showed that miR-145-5p overexpression decreased the expression levels of IL-1β, IL-6 and TNF-α in LPS-induced AT II cells. miR-145-5p overexpression also blocked the LPS-induced activation of nuclear factor kappa B (NF-κB) pathway and reactive oxygen species (ROS) accumulation in AT II cells. Finally, in ALI mouse model, miR-145-5p overexpression alleviated lung tissue injury, decreased the expression levels of IL-1β, IL-6 and TNF-α and reduced MPO activity. In conclusion, miR-145-5p participated in the progression and development of ALI by decreasing the production of pro-inflammatory cytokines, inhibiting NF-κB pathway and suppressing ROS accumulation, shedding light on miR-145-5p as a potential therapeutic target for the treatment of ALI.