ABSTRACT
ObjectiveUsing multi-omics technology， we conducted the present study to determine whether dexamethasone has therapeutic effect on pneumonia rats through the regulation of intestinal flora and metabolites. MethodsTotally 18 Sprague-Dawley rats were randomly divided into 3 groups （n = 6 each）： Control group， Model group and Dexamethasone （Dex） group. Lipopolysaccharide （LPS） was continuously injected intraperitoneally into rats at a dose of 4 mg/kg for 7 days to induce pneumonia except the Control group. Then the Dex group was given Dex at a dose of 2 mg/kg via oral gavage for 12 days， and both the other two groups received continuously equal volume of sterile PBS buffer for 12 days. On the 19th day， lung， plasma， feces and intestinal contents of rat were collected. Hematoxylin-eosin （H&E） staining and Bio-plex suspension chip system were applied to evaluate the effect of Dex on pneumonia. Furthermore， metagenomic sequencing and UPLC-Q-TOF-MS/MS technology were employed to determine the intestinal flora and metabolites of rats， respectively. ResultsH&E staining results showed that the lung tissue of the Model group was infiltrated with inflammatory cells， the alveolar septum was increased， alveolar hemorrhage， and histological lesions were less severe in Dex group than in the model group. The levels of 3 inflammatory cytokines including TNF-α （P < 0.000 1）， IL-1α （P = 0.009 6） and IL-6 （P < 0.000 1） in the Model group were increased compared with the Control group， while Dex treatment reduced the levels of the three inflammatory factors. Taken together， Dex treatment effectively reversed the features of pneumonia in rats. Metagenomic analysis revealed that the intestinal flora structure of the three groups of rats was changed. In contrast with the Model group， an increasing level of the Firmicutes and an elevated proportion of Firmicutes/Bacteroidetes were observed after Dex treatment. Dex-treated rats possessed notably enrichment of Bifidobacterium， Lachnospiraceae and Lactobacillus. Multivariate statistical analysis showed a great separation between Model group and Dex group， indicating metabolic profile changes. In addition， 69 metabolites （P < 0.05） were screened， including 38 up-regulated in the Model group and 31 elevated in the Dex group， all of which were mainly involved in 3 metabolic pathways： linoleic acid metabolism， tryptophan metabolism and primary bile acid biosynthesis. ConclusionsIn summary， we demonstrate the beneficial effects of Dex on the symptoms of pneumonia. Meanwhile， integrated microbiome-metabolome analysis reveals that Dex improves LPS-induced pneumonia in rats through regulating intestinal flora and host metabolites. This study may provide new insights into the mechanism of Dex treatment of pneumonia in rats.
ABSTRACT
In this research,we explored the effect of three groups of water treatments,including severe drought(the corresponding water content of cultivated substrate 5%-10%),moderate drought(45%-50%) and control(85%-90%),and different drought stress time(15,30,45 d) on the glandular trichome density(TD),stomatal density(SD) and volatile exudates of Schizonepeta tenuifolia.The results showed that there were two kinds of glandular trichomes on the surface of S. tenuifolia leaves: peltate and capitate glandular trichomes. The density of capitate glandular trichomes(CTD) was higher than that of peltate glandular trichomes(PTD). Both CTD and PTD on the abaxial surface of leaf were higher than those on the adaxial surface. Under severe drought stress,the CTD and SD were higher than the other two treatments. Under the same stress time,the biomass and leaf surface area of S. tenuifolia decreased with the deepening of stress degree. As the stress time prolonged,the surface area of leaves and biomass gradually increased,and the TD and SD decreased. The most abundant compound in volatile exudates of S. tenuifolia was pulegone. Under drought stress,the relative content of pulegone decreased,and the relative content of other monoterpenoids such as D-limonene and menthone increased. The n-hexadeconic acid and 2-methyl-1-hexadecanol were detected only at the stress of 15 d,while menthone was detected at the stress of 30 d and45 d. Drought stress affected the leaf growth and secondary metabolism of S. tenuifolia.