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

Abstract

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.

Microbiota in Uterine Cavity of Unexplained Recurrent Spontaneous Abortion (URSA) Patients in Early Pregnancy

“…A study showed that 40% of the endometrial samples obtained by abdominal hysterectomy detected no microbiome (25). This exciting phenomenon raises doubts whether uterine microbiome colonization in all early pregnant women or just in URSA women, whether the detected microbiota is in the uterus temporarily or permanently, or whether they are just contamination (26). Therefore, in the near future, we will concentrate on a series of related work to verify our assumption that there may be a "microbiota-containing time window" in the uterine cavity in the early pregnancy.…”

Approaches to Improve Endometrial Receptivity in Case of Repeated Implantation Failures

“…Despite the initiated enthusiasm, there are several issues regarding the procedure of sampling and evaluating endometrial microbiota. It has been reported that endometrial microbiome may fluctuate according to the circulating estrogen and progesterone ( Molina et al, 2020 ). Additionally, it may be altered by infectious agents, increasing age, physical activity, pregnancy and childbirth ( Molina et al, 2020 ).…”

“…It has been reported that endometrial microbiome may fluctuate according to the circulating estrogen and progesterone ( Molina et al, 2020 ). Additionally, it may be altered by infectious agents, increasing age, physical activity, pregnancy and childbirth ( Molina et al, 2020 ). More importantly, endometrial microbiome evaluation is under the influence of technical details that need standardization.…”

“…Several approaches have been proposed as potentially effective in restoring normal endometrial microbiome. However it must be taken under consideration the fact that to date there is no core endometrial microbiome, therefore restoring to normal could be a matter of question ( Molina et al, 2020 ). Microbiome restoration is initially approached by the administration of antibiotics, considering that most of the time dysbiotic microbiota may include pathogens well-controlled by standard anti-microbial agents ( Kyono et al, 2019 ).…”

“…Microbiome restoration is initially approached by the administration of antibiotics, considering that most of the time dysbiotic microbiota may include pathogens well-controlled by standard anti-microbial agents ( Kyono et al, 2019 ). Several routes of administration have been proposed so far including oral, vaginal and intrauterine ( Molina et al, 2020 ). Additionally, the administration of pro- and pre-biotics has been tested as auxiliary means of maintaining or amplifying the eubiotic bacteria.…”