Effect of melatonin on lung injury in a mouse model of influenza virus infection through regulating MEG3/miR-223/NLRP3 axis / 中国免疫学杂志

ABSTRACT

Objective:To investigate the regulation of melatonin(MT)against lung injury in a mouse model of influenza virus infection by regulating the maternally expressed gene 3(MEG3)/microRNA-223(miR-223)/nucleotide-binding oligomerization do-main-like receptor protein 3(NLRP3)axis.Methods:Fifty mice were randomly divided into control group,model group,and MT(low,medium,and high)dose groups,with 10 mice in each group.Except for the control group,the other groups were given H7N9 virus suspension nasal drops at a dose of 5×105 EID50,and the control group was given an equal volume of phosphate buffer nasal drops.The MT(low,medium,and high)dose groups were injected intraperitoneally with(15,30,60)mg/kg MT on the day after modeling,the control group and model group were intraperitoneally injected with equal volume of normal saline.The mice were sacri-ficed 24 h after the last administration for experiment.All mice were tested for the lung index;Hematoxylin-Eosin(HE)staining was used to observe the lung tissue morphology;ELISA was used to detect the levels of interleukin IL-1β,IL-18,IL-6,TNF-α and IFN-β in lung tissues;real-time fluorescent quantitative PCR(RT-qPCR)was used to detect the levels of MEG3 mRNA and miR-223 in mouse lung tissues;Western blot was used to detect the protein levels of NLRP3,apoptosis-related dot-like protein(ASC),cysteine aspartate proteolytic enzyme 1(caspase-1),and pro-caspase-1 in lung tissues.Bioinformatics prediction and dual luciferase experi-ments were used to detect the targeting relationship between MEG3 and miR-223,miR-223 and NLRP3.Results:The pathological re-sults showed that the alveolar wall of the lung tissue of the model group was obviously congested,and there was obvious inflammatory exudation and inflammatory cell infiltration in the cavity;with the increase of the MT dose,the hyperemia of the alveolar wall of the mouse lung tissue,the inflammatory exudation in the cavity and the infiltration of inflammatory cells in the MT(low,medium,and high)dose group were all improved.Compared with control group,the lung index,chemokines,inflammatory factors,antiviral fac-tors,MEG3 levels in lung tissues,NLRP3 pathway protein level in the model group were increased(P<0.05),and the miR-223 level was decreased(P<0.05);after the addition of MT,the antiviral factors increased significantly,and other indicators were improved.miR-223 had targeted regulatory relationships with MEG3 and NLRP3.Conclusion:MT can alleviate the lung injury of H7N9 influen-za virus-infected mice,which may be related to the regulation of MEG3/miR-223/NLRP3 axis to relieve inflammation.