Commentary: Uterine Microbiota: Residents, Tourists, or Invaders?

Altmäe, Signe

doi:10.3389/fimmu.2018.01874

Cited by 28 publications

(24 citation statements)

References 23 publications

(29 reference statements)

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“…Some authors have criticized the hypothesis that endometrial microbiota plays a role in IVF outcome [25] and a recently published review [26] even questioned the existence of an active endometrial microbiota. The conclusions of the review have been challenged and critical issues raised [27], particularly as regards the variations in endometrial microbiota composition in relation to hormonal changes and compared with the vaginal microbiota. The present study provides evidence in this direction: the Shannon biodiversity index of the vaginal and the endometrial samples differed before and after COS and the biodiversity of the endometrial microbiota appeared to be greater than the vaginal microbiota.…”

Section: Discussionmentioning

confidence: 99%

Controlled ovarian stimulation and progesterone supplementation affect vaginal and endometrial microbiota in IVF cycles: a pilot study

Carosso¹,

Revelli²,

Gennarelli³

et al. 2020

J Assist Reprod Genet

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Purpose Does controlled ovarian stimulation (COS) and progesterone (P) luteal supplementation modify the vaginal and endometrial microbiota of women undergoing in vitro fertilization? Methods Fifteen women underwent microbiota analysis at two time points: during a mock transfer performed in the luteal phase of the cycle preceding COS, and at the time of fresh embryo transfer (ET). A vaginal swab and the distal extremity of the ET catheter tip were analyzed using next-generation 16SrRNA gene sequencing. Heterogeneity of the bacterial microbiota was assessed according to both the Bray-Curtis similarity index and the Shannon diversity index. Results Lactobacillus was the most prevalent genus in the vaginal samples, although its relative proportion was reduced by COS plus P supplementation (71.5 ± 40.6% vs. 61.1 ± 44.2%). In the vagina, an increase in pathogenic species was observed, involving Prevotella (3.5 ± 8.9% vs. 12.0 ± 19.4%), and Escherichia coli-Shigella spp. (1.4 ± 5.6% vs. 2.0 ± 7.8%). In the endometrium, the proportion of Lactobacilli slightly decreased (27.4 ± 34.5% vs. 25.0 ± 29.9%); differently, both Prevotella and Atopobium increased (3.4 ± 9.5% vs. 4.7 ± 7.4% and 0.7 ± 1.5% vs. 5.8 ± 12.0%). In both sites, biodiversity was greater after COS (p < 0.05), particularly in the endometrial microbiota, as confirmed by Bray-Curtis analysis of the phylogenetic distance among bacteria genera. Bray-Curtis analysis confirmed significant differences also for the paired endometrium-vagina samples at each time point. Conclusions Our findings suggest that COS and P supplementation significantly change the composition of vaginal and endometrial microbiota. The greater instability could affect both endometrial receptivity and placentation. If our findings are confirmed, they may provide a further reason to encourage the freeze-all strategy.

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Section: Discussionmentioning

confidence: 99%

Controlled ovarian stimulation and progesterone supplementation affect vaginal and endometrial microbiota in IVF cycles: a pilot study

Carosso¹,

Revelli²,

Gennarelli³

et al. 2020

J Assist Reprod Genet

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“…Furthermore, uterine microbial transmission is not clearly established, whereas different routes were proposed, including ascension of bacteria through the cervix, retrograde spread through fallopian tubes, haematogenous spread of oral and/or gut bacteria, through gynaecological procedures (e.g., assisted reproductive technology-related procedures; insertion/removal of the intrauterine devices), sexual habits, and/or with sperm [27][28][29][30][31]. Ascension of radioactively labelled macrospheres from vagina to the uterus by a 'uterine peristaltic pump' activity was shown [32,33], highlighting the most probable way for bacterial route into the uterus.…”

Section: Introductionmentioning

confidence: 99%

New Opportunities for Endometrial Health by Modifying Uterine Microbial Composition: Present or Future?

et al. 2020

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Current knowledge suggests that the uterus harbours its own microbiota, where the microbes could influence the uterine functions in health and disease; however, the core uterine microbial composition and the host-microbial relationships remain to be fully elucidated. Different studies are indicating, based on next-generation sequencing techniques, that microbial dysbiosis could be associated with several gynaecological disorders, such as endometriosis, chronic endometritis, dysfunctional menstrual bleeding, endometrial cancer, and infertility. Treatments using antibiotics and probiotics and/or prebiotics for endometrial microbial dysbiosis are being applied. Nevertheless there is no unified protocol for assessing the endometrial dysbiosis and no optimal treatment protocol for the established dysbiosis. With this review we outline the microbes (mostly bacteria) identified in the endometrial microbiome studies, the current treatments offered for bacterial dysbiosis in the clinical setting, and the future possibilities such as pro- and prebiotics and microbial transplants for modifying uterine microbial composition.

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“…Nowadays, evidence from NGS investigations strongly supports the existence of a uterine microbiota and metagenomic approaches are gaining momentum in the analyses of the human endometrial microbiota under different conditions. Several reviews and commentary articles are already available on this specific topic [5][6][7][8][9][10][11][12]. Besides advances in the knowledge of the microbiota composition and its origin, these studies can also help to establish possible correlations between microbiota composition and uterus specific physiologic or pathologic conditions, including pregnancy, sterility, and conditions in which assisted reproductive technologies (ART) are adopted.…”

Section: Introductionmentioning

confidence: 99%

Human Endometrial Microbiota at Term of Normal Pregnancies

Leoni

Ceci

Manzari

et al. 2019

Genes

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The endometrium is a challenging site for metagenomic analysis due to difficulties in obtaining uncontaminated samples and the limited abundance of the bacterial population. Indeed, solid correlations between endometrial physio-pathologic conditions and bacteria compositions have not yet been firmly established. Nevertheless, the study of the endometrial microbiota is of great interest due to the close correlations between microbiota profiles, women’s health, and successful pregnancies. In this study, we decided to tackle the study of the endometrial microbiota through analysis of bacterial population in women subjected to elective caesarean delivery. As a pilot study, a cohort of 19 Caucasian women at full term of normal pregnancy and with a prospection of elective caesarean delivery was enrolled for endometrium sampling at the time of caesarean section. Sampling was carried out by endometrial biopsy soon after the delivery of the newborn and the discharge of the placenta and fetal membranes from the uterus. Bacterial composition was established by a deep metabarcoding next generation sequencing (NGS) procedure addressing the V5–V6 hypervariable region of the 16S rRNA gene. Amplicon sequences were analysed by bioinformatic procedures for denoising and taxonomic classification. The RDP database was used as 16S rRNA reference collection. Metabarcoding analysis showed the presence of a common bacterial composition, including six genera classifiable within the human microbiota (Cutibacterium, Escherichia, Staphylococcus, Acinetobacter, Streptococcus, Corynebacterium), that could be part of the core endometrial microbiota under the specific conditions examined. These results can provide useful information for future studies on the correlations between bacteria and successful pregnancies.

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Commentary: Uterine Microbiota: Residents, Tourists, or Invaders?

Cited by 28 publications

References 23 publications

Controlled ovarian stimulation and progesterone supplementation affect vaginal and endometrial microbiota in IVF cycles: a pilot study

Controlled ovarian stimulation and progesterone supplementation affect vaginal and endometrial microbiota in IVF cycles: a pilot study

New Opportunities for Endometrial Health by Modifying Uterine Microbial Composition: Present or Future?

Human Endometrial Microbiota at Term of Normal Pregnancies

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