Integrated Metagenomics and UPLC-Q-TOF-MS/MS to Explore the Mechanism of Dexamethasone on Pneumonia in Rats / 中山大学学报(医学科学版)

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.