Reproductive tract microbiome in assisted reproductive technologies

Abstract

The human microbiome has gained much attention recently for its role in health and disease. This interest has come as we have begun to scratch the surface of the complexity of what has been deemed to be our "second genome" through initiatives such as the Human Microbiome Project. Microbes have been hypothesized to be involved in the physiology and pathophysiology of assisted reproduction since before the first success in IVF. Although the data supporting or refuting this hypothesis remain somewhat sparse, thanks to sequencing data from the 16S rRNA subunit, we have begun to characterize the microbiome in the male and female reproductive tracts and understand how this may play a role in reproductive competence. In this review, we discuss what is known about the microbiome of the reproductive tract as it pertains to assisted reproductive technologies.

Deciphering the effect of reproductive tract microbiota on human reproduction

“…The majority of studies on the female reproductive tract microbiome are focused on the vagina because of the ease of sampling; yet, several studies have demonstrated the existence of bacterial colonization beyond the vagina, showing that the upper reproductive tract is not sterile. For example, an active uterine microbiome has been characterized in healthy reproductive‐age women, but bacteria have also been found to inhabit the fallopian tubes and the ovaries, with Lactobacillus the most abundant genus throughout the female reproductive tract . Recently, a study surveying the female reproductive tract confirmed the existence of a microbiota continuum starting in the vagina and progressing to the deepest organs in the tract—cervix, uterus, tubes, ovaries, and even colonizing the pouch of Douglas—in women with non‐infectious conditions.…”

Investigating the effect of an abnormal cervico‐vaginal and endometrial microbiome on assisted reproductive technologies: A systematic review

“…The term microbiota refers to the collection of the microbes harbored by each organism, while the term microbiome refers to the catalog of genes and products of these microbes together with the host . Humans are colonized with more than 10 times as many microbes than human cells in the body, and as more knowledge regarding the human microbiome is acquired, the clearer it becomes that it has a significant affect on human physiology . The majority of bacterial communities co‐exist in synergistic relationships with the human host, and it is understood that the microbiome evolved together with the genome .…”

“…Historically, the uterine cavity was thought to be sterile with microbial colonization only as part of a pathological process, however this is now accepted to be inaccurate. Zervomanolakis et al performed an interesting study using hysterosalpongoscintigraphy by injecting radiolabelled aggregates of human albumin into the posterior fornix of the vagina .…”

16S Based Microbiome Analysis from Healthy Subjects’ Skin Swabs Stored for Different Storage Periods Reveal Phylum to Genus Level Changes

“…New cost efficient and high throughput next generation sequencing technologies have spurred this scientific development to add a new field with immense significance to medical research (Metzker, 2010). We know that the human microbiome and alterations in the bacterial composition are associated with a wide range of human diseases from neurological [multiple sclerosis (Miyake et al, 2015)], intestinal [Crohn’s disease (Raes, 2016)] and skin (Yu et al, 2015) disorders to infertility (Franasiak and Scott, 2015). Microbiota (the entity of all microorganisms living in and on the human body) may influence our physiology directly by stimulating our immune system, occupying and affecting habitats on the human body defending us against pathogens or influence us through their metabolites (Integrative Hmp (iHMP) Research Network Consortium, 2014).…”