Inhibitory effect and mechanism of total flavonoids of Dracocephalum Moldavica L.on bleomycin-induced pulmonary fibrosis in rats
Objective To observe the effect of total flavonoids of Dracocephalum Moldavica L.on bleomycin-in-duced pulmonary fibrosis(PF)in rats and to explore the possible mechanism based on intestinal flora and serum metabolo-mics approaches.Methods Thirty-two male SD rats were randomly divided into the control group,model group,high-dose total flavonoids of Dracocephalum Moldavica L.group and low-dose total flavonoids of Dracocephalum Moldavica L.group,with 8 rats in each group.In addition to the control group,the model was established by intratracheal drip of bleo-mycin in each group;400 mg/kg and 100 mg/kg of total flavonoids of Dracocephalum Moldavica L.were given by gavage in the high-and low-dose groups,respectively,and an equal volume of normal saline was given by gavage in the control group and the model group,respectively,once a day for 21 d.The lung histopathology was observed by HE and Masson staining.The collagen Ⅲ(COLⅢ)and α-smooth muscle actin(α-SMA)mRNA expression levels in the lung tissues were detected by real-time fluorescence quantitative PCR.16S rRNA sequencing technology was used to detect the diversity and relative abundance of intestinal flora,and ultra-high-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)was used to analyse and screen for the key differential metabolites in serum,which were then imported into the Kyoto Encyclopedia of Genes and Genomes(KEGG)for the metabolic pathway enrichment analysis.Results Com-pared with the control group,the alveolar structure of rats in the model group was destroyed,the alveolar intervals were widened,the inflammatory cell infiltration was obvious,the alveolar wall was thickened,the distance between the alveoli was widened,and the deposition of collagen fibres in blue stripes was seen;compared with the model group,the above pathological changes were reduced in rats in the high-and low-dose total flavonoids of Dracocephalum Moldavica L.groups.Compared with the control group,the relative expression levels of COLⅢ and α-SMA mRNA in the lung tissues of rats in the model group increased(all P<0.05);compared with the model group,the relative expression levels of COLⅢand α-SMA mRNA in the lung tissues of rats in the high-and low-dose total flavonoids of Dracocephalum Moldavica L.groups decreased(all P<0.05).Analysis of α-diversity showed that,compared with the control group,the model group,the intestinal flora Chao1 and Ace increased in the high-dose and low-dose total flavonoids of Dracocephalum Moldavica L.groups(all P<0.05).The β-diversity analysis showed that the composition of the intestinal flora of the rats in the control group,the high-dose and low-dose total flavonoids of Dracocephalum Moldavica L.groups were close to each other,and that was different from the composition of the intestinal flora of the rats in the model group.At the phylum level,compared with the control group,the relative abundance of Bacteroidota decreased,while the abundances of Firmicutes/Bacteroidota increased in rats of the model group(all P<0.05);compared with the model group,the relative abundance of Bacteroidota in rats in the high-and low-dose total flavonoids of Dracocephalum Moldavica L.groups increased,while the relative abun-dances of Firmicutes/Bacteroidota decreased(all P<0.05).At the genus level,compared with the control group,the rela-tive abundances of Ligilactobacillus decreased in the remaining three groups(all P<0.05);compared with the control and model groups,the relative abundances of Lactobacillus increased in the high-and low-dose total flavonoids of Dracoceph-alum Moldavica L.groups(all P<0.05).Compared with the control group,the key differential flora of rats in the model group was Escherichia coli species;compared with the model group,the key differential floras of rats in the high-dose total flavonoids of Dracocephalum Moldavica L.group were Bifidobacterium pseudo-longum,Bifidobacterium bifidum,and Ru-minococcus;compared with the model group,the key differential floras of rats in the low-dose total flavonoids of Draco-cephalum Moldavica L.group were Lactobacillus johannesiensis and Akkermansia muciniphila.Thirty and forty-nine se-rum differential metabolites were screened out between the model group and the high-and low-dose total flavonoids of Dracocephalum Moldavica L.groups,all of which were mainly enriched in the AMP-activated protein kinase(AMPK)sig-naling pathway,etc.Conclusion Total flavonoids of Dracocephalum Moldavica L.attenuate bleomycin-induced PF in rats,and the mechanism of action may be related to regulating the composition of intestinal flora and AMPK-related meta-bolic pathways,etc.
Total flavonoids of Dracocephalum Moldavica L.pulmonary fibrosisintestinal florametabolomicsAMP-activated protein kinase
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