Effect of simvastatin pretreatment on human metapneumovirus infection and its mechanism / 解放军医学杂志

ABSTRACT

Objective: To investigate the effect of simvastatin pretreatment on human metapneumovirus (hMPV) infection and the related mechanism. Methods: Human bronchial epithelial cells (16HBE) were used in vitro experiments and BALB/c mice were used in vivo experiments. They were randomly divided into control group, simvastatin group, hMPV group, hMPV+simvastatin group. After corresponding treatment, the fluorescence of hMPV was observed with microscopy; virus titer and the expressions of autophagy-related gene recombinant human autophagy-related protein 5 (ATG5), Beclin1, and microtubule-associated protein 1 light chain 3 (LC3) were detected by Fluorescence Quantitative Real-time PCR; Western blotting was performed to detect autophagy-related protein ATG5, Beclin1, LC3 and serine/threonine kinase/mammalian rapamycin target protein (AKT/mTOR) pathway proteins. Results: In vitro experiment, the direct and indirect fluorescence expressions of hMPV and the virus titer were lower in hMPV+simvastatin group (0.260 ± 0.018) than those in hMPV group (1.241 ± 0.030), while the mRNA expression levels of autophagy-related gene ATG5, Beclin1 and LC3 were higher in hMPV+simvastatin group [(7.31±0.15), (8.67±0.88) and (6.55±0.30), respectively] than those in control group [(1.00±0.06), (1.00±0.05) and (1.10±0.06), respectively]; the mRNA and protein levels of autophagy-genes were the highest in hMPV+simvastatin group and the differences were statistically significant (P<0.05). The AKT/mTOR pathway was inhibited in hMPV group and hMPV+simvastatin group. In vivo experiment, the virus titer of the lung tissue and of the lung tissue supernatant inoculated in Vero E6 were lower in hMPV+simvastatin group (0.75±0.26 and 0.42±0.17, respectively) than those in hMPV group (2.46±0.53 and 1.80±0.40, respectively). The mRNA and protein expression levels of autophagy-related genes ATG5, Beclin1 and LC3 were the highest in hMPV+simvastatin group (3.89±0.42, 3.13±0.26 and 3.56±0.22, respectively), higher than those in control group and hMPV group, the differences were statistically significant (P<0.05), and the AKT/mTOR pathway was inhibited in this group; HE staining of lung tissue showed an inflammatory response in the hMPV group, and pre-treatment with simvastatin could reduce the inflammation. Conclusion: Pretreatment with simvastatin may reduce human metapneumovirus infection, which is associated with autophagy and the AKT/mTOR pathway.