Figures & data
Figure 1. Effect of mechanical ventilation on lung tissue injury from rats. (a) Rats were executed directly after tracheal intubation under anesthesia. (b–d) Rats were kept under anesthesia after tracheal intubation with spontaneous breathing for 1, 3, and 6 h. (e–g). rats were mechanically ventilated for 1, 3, and 6 h after tracheal intubation. (h) Lung tissue injury score. Data are representative of at least four different experiments. Results are mean ± S for four rats. *p < 0.05, **p < 0.01, ***p < 0.001, compared with control animals or between mechanical ventilation for six hours and spontaneous breathing for six hours.
Figure 2. Changes in the lower respiratory tract microbiota of rats during mechanical ventilation. (a) At the genus level, the main dominant genera were Acinetobacter, Lactobacillus, and Staphylococcus. (b) At the phylum level, the main dominant phyla were Proteobacteria, Firmicutes, Bacteroidetes, Cyanobacteria, and Actinobacteria. Tracheal intubation and mechanical ventilation caused changes in rats’ lower respiratory tract microbiota ratio.
Figure 3. The sample taxonomic analysis revealed the microbial community ranking map of 16S rDNA bacteria: a scatter plot and PCoA ranking based on phylogenetic distance (PCoA1 vs. PCoA2) (a). UniFrac unweighted non-metric multidimensional scale-metric multidimensional scaling (NMDS) (b).
Figure 4. Beta diversity analysis heatmap. Unweighted distance matrix (a): rats in the control group and each experimental group showed a clustering trend, suggesting that there were Specific differences in the species of lower respiratory tract microbiota between rats in the control group and each experimental group. Weighted distance matrix (b): the samples of the control group and each experimental group did not show an apparent clustering trend, suggesting that there was no significant difference in the diversity of bacterial microbiota among each group.
Figure 5. LEfSe Comparative analysis plot: categorical representation indicating statistical and biological agreement and differences in the identified biomarkers between the experimental groups. (a) control versus mechanical ventilation under intubation for one hour (C-MV1); (b) control versus spontaneous breathing under intubation for one hour (C-SV1); (c) control versus mechanical ventilation under intubation for three hours (C-MV3); (d) control versus spontaneous breathing under intubation for three hours (C-SV3); (e) control versus mechanical ventilation under intubation for six hours (C-MV6); (f) control versus spontaneous breathing under intubation for six hours (C-SV6). the colored part represents the significantly different taxonomic trends of the bacterial microbiota. Red or green shading depicts bacterial taxa significantly higher in each experimental group, while yellow represents species that did not differ significantly.
Table 1. Alpha diversity of rat lower respiratory tract microbiota.
Figure 6. Bugbase analysis of rat lower respiratory tract microbiota. (a,b) With the associated representative genera changes anaerobic activity is diminished at the beginning of mechanical ventilation. (c,d) Biofilm formation is enhanced at the beginning of mechanical ventilation, and the associated representative genera are altered. (e,f) Gram_negative formation did not vary much between groups; it slightly increased at the beginning of the experiment, and the proportion decreased with the prolongation of the experiment.
