[Protective effect of microRNA-155 antisense oligonucleotid on lipopolysaccharide-induced acute lung injury in mice]

To investigate the protective effect of microRNA-155 (miR-155) antisense oligonucleotid (ASO) on acute lung injury (ALI) mice by establishing a lentiviral expression vector of ASO of miRNA.

miR-155 antisense oligonucleotides amplified by polymerase chain reaction (PCR) from genomic, using BamH I and Nhe I double digestion, ligated into lentiviral expression vector. Sequence and virus titer were measured. According to the random number table method, 54 male BALB/c mice of 4-6 weeks old were divided into three groups. ALI animal models were prepared by intraperitoneal injection of 10 mg/kg lipopolysaccharide (LPS). The three groups were injected with 200 μL phosphate buffered saline (PBS) containing 1×108/mL pmiR-155-ASO virus (pmiR-155-ASO group) or 200 μL PBS containing 1×108/mL pSMPUW-miR-GFP empty virus (pmiR-cont group) or the same amount of PBS (PBS group) at 24 hours before the molding. Ten mice in each group were used to observe the 7-day survival rate. Blood samples and lung tissues of the remaining 8 mice were harvested after the model was established, and the levels of serum inflammatory cytokines were determined by enzyme linked immunosorbent assay (ELISA); the expression of miR-155 in lung tissue was detected by real-time reverse transcription-polymerase chain reaction (RT-PCR); histopathological changes of lung and distribution of macrophages were observed under microscope.

There was no significant difference in each index between pmiR-cont group and PBS group. The mature miR-155 expression in lung tissue in pmiR-155-ASO group was significantly lower than that in pmiR-cont group (2-ΔΔCt: 4.92±0.72 vs. 15.38±0.60, P < 0.05). Compared with pmiR-cont group, the injury degree of ALI mice after pretreatment with miR-155 ASO was significantly improved, and the 7-day survival rate was significantly increased (72.1% vs. 61.9%, P < 0.05 ); gross lung observation showed that congestion in lung tissue was significantly reduced, and the ratio of wet/dry weight (W/D) of lung was significantly decreased (4.50±0.13 vs. 5.64±0.61, P < 0.05); hematoxylin-eosin (HE) staining showed that inflammatory cell infiltration in lung tissue was decreased, while immunofluorescence assay showed that macrophage infiltration in lung tissue was significant decreased; the levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in serum were significantly decreased [TNF-α (ng/L): 379.8±48.9 vs. 495.9±33.3, IL-6 (ng/L): 262.3±61.8 vs. 355.4±22.6, both P < 0.05], but the level of IL-10 did not change significantly (ng/L: 143.6±32.5 vs. 140.4±22.3, P > 0.05).

miR-155 ASO has the effect of inhibiting LPS-induced inflammatory response and improving prognosis in ALI mice.