[Alterations in gut microbiota and metabolites of sepsis patients with acute respiratory distress syndrome based on 16S rDNA and untargeted metabolomics sequencing analysis].

OBJECTIVE: To investigate the changes of gut microbiota and metabolites between sepsis patients with acute respiratory distress syndrome (ARDS) by using 16S rDNA and untargeted metabolomics sequencing analysis.

METHODS: Patients with sepsis admitted to general intensive care unit (ICU) of the First Affiliated Hospital of Zhengzhou University from January 2024 to May 2024 were enrolled. They were divided into ARDS group and non-ARDS group according to whether ARDS was present at admission. Clinical data were collected, and the fecal samples within 24 hours after diagnosis of sepsis were collected for 16S rDNA sequencing. The denoised sequences amplicon sequence variants were used for diversity analysis, species composition analysis and species difference analysis. The fecal samples were performed for untargeted metabolomics analysis by liquid chromatography-tandem mass spectrometry to screen for differential metabolites and related pathways. Finally, the joint analysis of differential gut microbiota and metabolites was conducted.

RESULTS: Finally, 38 sepsis patients were included, including 15 cases with concomitant ARDS. Compared with the non-ARDS group, the ARDS group had significantly higher sequential organ failure assessment (SOFA), acute physiology and chronic health evaluation II (APACHE II), and C-reactive protein level. The 16S rDNA sequencing results showed that at the phylum level, the ARDS group was mainly composed of Proteobacteria and Bacteroidota, while the non-ARDS group was mainly composed of Firmicutes and Verrucomicrobiota. At the genus level, the ARDS group was mainly composed of Klebsiella and Acinetobacter, while the non-ARDS group was mainly composed of Enterococcus, Akkermansia and Ligilactobacillus. Linear discriminant analysis effect size (LEfSe) showed that compared with the non-ARDS group, the abundance of Klebsiella and Anaerofilum in the ARDS group significantly increased, while the abundance of Enterococcus, Streptococcus, Akkermansia and Ruminococcus in the ARDS group significantly decreased. The untargeted metabolomics analysis showed that compared with the non-ARDS group, the levels of metabolites such as nicotinamide N-oxide, uridine and N-acetyl-arginine were significantly up-regulated in the ARDS group, while the levels of metabolites such as lysine, ornithine, N-acetylaspartic acid and alanylalanine were significantly down-regulated in the ARDS group. The metabolic pathway analysis showed that compared with the non-ARDS group, the differentially expressed metabolites in the ARDS group were mainly enriched in the pyrimidine metabolism, arginine and proline metabolism, lysine biosynthesis, lysinedegradation, aminoacyl-tRNA biosynthesis, glycine, serine and threonine metabolism. The joint analysis indicated that Klebsiella were positively correlated with metabolites such as nicotinamide N-oxide and N-acetyl-arginine. Enterococcus were positively correlated with metabolites such as lysine and ornithine, and negatively correlated with nicotinamide N-oxide.

CONCLUSIONS: The abundance of beneficial bacteria in the gut of sepsis patients with ARDS further decreased, while the abundance of opportunistic pathogens further increased, which in turn affected the levels of related metabolites.