ABSTRACT
OBJECTIVE To investigate the effect and mechanism of dihydroartemisinin(DHA)on lipo-polysaccharide(LPS)-induced acute lung injury(ALI)in mice using whole-genome sequencing.METHODS An ALI mouse model was established via intraperitoneal injection of 10 mg·kg-1 lipopolysaccharide.The mice were divided into normal control group(n=10),model group(n=10)and model+DHA group(n=10).The mice in the model+DHA group were injected intraperitoneally with 20 mg·kg-1 DHA,while those in the normal control group and LPS group were injected intraperitoneally with solvent of DHA,saline containing 1%Tween 80 and 10%Macrogol 400.The mice were executed 24 h after drug administration.The wet and dry weight ratio(W/D)of lung tissue was calculated.Hematoxylin-eosin(HE)staining was used to observe histopathological damage in the lung.Classified counts of inflamma-tory cells in alveolar lavage fluid were performed.Enzyme-linked immunosorbent assay(ELISA)was used to detect the levels of interleukin-1β(IL-1β),IL-6,and tumor necrosis factor-α(TNF-α)in alveolar lavage fluid.Real-time quantitative PCR(RT-qPCR)was used to detect mRNA levels of placenta-specific 8(Plac8),Toll-like receptor 7(TLR7),IL-1β,IL-6 and TNF-αin lung tissue.The whole gene transcriptome was sequenced by RNA transcriptome sequencing(RNA-seq)using the Illumina HiSeq high-throughput sequencing platform before the function and signal pathway of differentially expressed gene mRNA between the groups were enriched and analyzed using GO and KEGG enrichment analysis methods.RESULTS Compared with the model group,the lung W/D values of mice,the pathological damage,inflammatory cells in alveolar lavage fluid,expression levels of IL-1β,IL-6 and TNF-α in alveolar lavage fluid(P<0.01,P<0.01,P<0.01),and the mRNA expression levels of IL-1β,IL-6 and TNF-α were significantly reduced in lung tissues in the model+DHA group(P<0.01,P<0.05,P<0.05).Whole gene transcriptome sequencing revealed that immune-related Plac8 and TLR7 genes were significantly upregu-lated(P<0.01)in mouse lung tissue of the model group but significantly downregulated(P<0.05)in mouse lung tissue of the model+DHA group.The results of RT-qPCR of Plac8 and TLR7 verified the results of whole gene transcriptome sequencing.GO and KEGG analysis showed that Plac8 and TLR7 were mainly related to the regulation of cytokine production,T/B cell activation and signal transduction,chemo-kine signal transduction and NF-κB signal transduction.CONCLUSION DHA might reduce LPS-induced lung damage and ameliorate the inflammatory condition in lungs of ALI mice.The mechanism of action may be that DHA negatively regulates the signaling pathways involved in TLR7 and Plac8 by decreasing the expressions of TLR7 and Plac8 mRNA before regulating a series of immune responses such as secretion of inflammation-related cytokines and activation of immune cells,thereby reducing inflam-matory damage in lungs.