Baogong decoction treats endometritis in mice by regulating uterine microbiota structure and metabolites

Abstract

Endometritis is persistent inflammation caused by bacteria, which can lead to infertility. Although traditional Chinese medicine (TCM) has been used to treat endometritis, the underlying mechanism is still unclear. Here, Baogong Decoction (BGD), a TCM compound, was used to treat mouse endometritis induced by Escherichia coli (E. coli), and then 16S rRNA sequencing and non-targeted metabolomics were used to investigate the change of uterine microbiota and metabolomes in serum and uterine after BGD treatment. Finally, the therapeutic effect of potential metabolites for treating mouse endometritis screened by combined omics analyses was verified using pathological model. The results showed that BGD treatment could effectively treat endometritis associated with the increasing relative abundance of Firmicutes, Bacteroides, Lactobacillus and Lactococcus, and the decreasing relative abundance of Cupriavidus and Proteobacteria. 133 and 130 metabolites were found to be potential biomarkers in serum and uterine tissue respectively. In serum and tissues, dehydroepiandrosterone (DHEA) and catechol were significantly increased in the BGD treatment versus the inflammation group. Results of combined omics analyses demonstrated that DHEA was positively correlated with changes in microbiota. Results of pathological model demonstrated that DHEA could cure endometritis effectively associated with the decreasing infiltration of inflammatory cells and expression of inflammatory factors in the uterus. In summary, our results demonstrated that BGD could cure endometritis in mice by modulating the structure of the uterine microbiota and its metabolites, in which DHEA may be one of the main components of the therapeutic effect of BGD.

FIGURE 1

Effects of Escherichia coli (E. coli) on the expression of uterine inflammation factors interleukin‐1β (IL‐1β), IL‐6 and tumour necrosis factor‐α (TNF‐α) in mice. (A, B) Effects of different concentrations of E. coli on the expression of IL‐1β, IL‐6 and TNF‐α mRNA and protein, n = 12. (C, D) Effects of 10¹⁰ cfu/mL E. coli on the expression of IL‐1β, IL‐6 and TNF‐α mRNA and protein within 7 days, n = 10. *p < 0.05, **p < 0.01, ***p < 0.001 compared with the control group.

FIGURE 2

Effect of Baogong Decoction treatment (traditional Chinese medicine) on endometritis in mice. Mouse uterine tissues were collected from control, E. coli and TCM groups. (A) Morphological changes to uterine tissue (left), and haematoxylin and eosin‐stained sections of uterine tissue (right, 100×), n = 8. Uterine expression of interleukin‐1β (IL‐1β), IL‐6 and tumour necrosis factor‐α (TNF‐α) mRNA (B) and protein (C), n = 10. **p < 0.05 and ***p < 0.001 compared with the control group (CTR). ^# p < 0.05, ^## p < 0.01 and ^### p < 0.001 compared with the E. coli group. TCM, traditional Chinese medicine; E. coli, Escherichia coli.

FIGURE 3

16S rRNA sequencing analysis of uterine microbiota in Escherichia coli (E)‐treated and traditional Chinese medicine (T)‐treated (using Baogong Decoction) mice. (A) Total operational taxonomic unit (OTU) analyses. (B) Weighted uniFrac distance PCoA analysis on mice uterine samples. (C) Grouped box plots of the alpha diversity index for the two groups. (D) Linear discriminant analysis (LDA) of effect size to investigate changes in uterine microbiota in different groups. Bacterial taxonomic profiling of uterine microbiota at the phylum (E) and genus (F) levels. Heatmap showing the phylum (G) and genus (H) types exhibiting significantly different relative abundances between the two groups of mice, n = 6.

FIGURE 4

Detection of metabolome differences in serum and uterus samples from mice treated with Escherichia coli (C) alone and Escherichia coli + TCM (TCM). OPLS‐DA score maps from LC–MS data of mouse serum (A) and uterus (B), left: Positive modes, right: Negative modes. Analysis of metabolite differences in mouse serum (C) and uterus (D) samples. Shared metabolites dehydroepiandrosterone (DHEA) and catechol were significantly up‐regulated. Analysis of metabolic pathways in mouse serum (E) and uterus (F) samples, n = 12.

FIGURE 5

The interaction between the uterine microbiota and metabolome. *p < 0.05 and **p < 0.01 indicate significant differences between the microbiota and metabolites. Blue represents positive correlations, red represents negative correlations.

FIGURE 6

Effects of dehydroepiandrosterone (DHEA) on mouse endometritis. Mouse uterine tissues were collected from control, E. coli and E. coli + DHEA (1 and 2 mg/kg) groups. (A) Morphological changes to uterine tissue (left), and haematoxylin and eosin‐stained sections of uterine tissue (right, 100×), n = 8. Uterine expression of interleukin‐1β (IL‐1β), IL‐6 and tumour necrosis factor‐α (TNF‐α) mRNA (B) and protein (C). **p < 0.05 and ***p < 0.001 compared with the control group, n = 10. ^# p < 0.05 and ^## p < 0.01 compared with the E. coli group.