Analysis of the microbiota composition in the genital tract of infertile patients with chronic endometritis or endometrial polyps

Abstract

BackgroundThe previous researches show that infertile patients have a higher incidence of endometritis and endometrial polyps, and the occurrence of these two diseases is related to changes in the microbiota of the genital tract. We aim to determine the composition and changing characteristics of the microbiota in the genital tract (especially the endometrium) of infertile patients with chronic endometritis or endometrial polyps, and find the correlation between it and the occurrence of diseases.MethodsThis is a prospective study. We collected genital tract biopsy samples from 134 asymptomatic infertile patients receiving assisted reproductive therapy before embryo transfer. Through pathological examination and 16S ribosomal RNA(16S rRNA) sequencing, we determined the distribution of chronic endometritis and endometrial polyps in these patients, as well as their distribution of reproductive tract microorganisms.ResultsCompared with the normal control group, the microbial group of reproductive tract in patients with chronic endometritis and endometrial polyps is changed, and there are significant species differences and relative abundance differences in the vagina, cervix and uterine cavity. Lactobacillus, the dominant flora of female genital tract, showed a change in abundance in patients with endometrial diseases. Endometrial microbiota composed of Staphylococcus, Gardnerella, Atopobium, Streptococcus, Peptostreptococcus, Chlamydia, Fusobacterium, Acinetobacter, etc. are related to chronic endometritis and endometrial polyps.ConclusionThe results showed that, compared with the normal control group, the endometrial microbiota of infertile patients with chronic endometritis or endometrial polyps did have significant changes in the relative abundance distribution of species, suggesting that changes in local microecology may be an important factor in the occurrence of disease, or even adverse pregnancy outcomes. The further study of endometrial microecology may provide a new opportunity to further improve the diagnosis and treatment strategy of chronic endometritis.

Comparison of microbial abundance and diversity in uterine and peritoneal fluid in infertile patients with or without endometriosis

“…Recent research is uncovering a link between infertility and the mix of microbes in the reproductive system [ 14 – 18 ]. Studies have found that infertile women tend to have more asymptomatic vaginal infections [ 15 ] and a different mix of uterine bacteria [ 16 ], including those often linked to conditions like bacterial vaginosis, chronic endometritis, and endometrial polyps [ 16 ]. Fertility dysfunction may be associated with the degradation of immune tolerance due to decreased Treg cells’ function and quantity [ 19 ].…”

Endometrial microbiota alteration in female patients with endometrial polyps based on 16S rRNA gene sequencing analysis

“…Conversely, Liang et al. found no significant differences in alpha and beta diversities between the two groups ( Liang et al., 2023 ). The disparities in these results could be attributed to variations in the selection of the control group.…”

“…Previous studies have extensively explored alterations in the uterine cavity microbiota of patients with EPs, including an elevated proportion of Firmicutes and a decreased proportion of Proteobacteria at the phylum level. Furthermore, enrichment of specific genera such as Lactobacillus , Staphylococcus , Bifidobacterium , Gardnerella , and Bacteroides was observed, along with a decreased level of Pseudomonas at genus levels ( Fang et al., 2016 ; Horban et al., 2019 ; Liang et al., 2023 ). Our study aligns with these previous findings and confirms significant abundance changes in the endometrial microbiota of patients with EPs, particularly in relation to Proteobacteria , Bifidobacterium , Staphylococcus , and Pseudomonas .…”

“…Although it is widely believed to have a low bacterial load in a highly diverse environment ( Chen et al., 2017 ; Laniewski et al., 2020 ), the dominant microbial population in the uterine cavity remains a topic of discussion. Most studies on endometrial diseases have shown that Lactobacillus is predominant in most patients ( Fang et al., 2016 ; Lozano et al., 2021 ; Chen et al., 2023 ; Liang et al., 2023 ). However, Winters found Acinetobacter and Pseudomonas were predominant in the uterine cavity, with low levels of Lactobacillus ( Winters et al., 2019 ).…”

“…The study revealed that patients with EP had a higher abundance of Lactobacillus , Bifidobacterium , Gardnerella , Streptococcus , Altermonas , and Prevotella , whereas the proportions of Fusobacterium , Pseudomonas , Escherichia coli , and Sphingomonas were lower than those in healthy women ( Fang et al., 2016 ). Subsequent studies have also reported that the microbiota of the endometrium in patients with EP primarily consisted of anaerobic bacteria, such as Bacteroides and Fusobacterium , as well as aerobic bacteria, such as Staphylococcus and Streptococcus ( Horban et al., 2019 ; Liang et al., 2023 ). However, further verification is required to ensure consistency in these results.…”