Vaginal microbiome in obesity and its impact on reproduction

Navigating complexities of polymorphic microbiomes in endometrial cancer

The microbiome is key to understanding endometrial cancer (EC) etiology and prevention strategies, implicated in the regulation of estrogen in estrogen-driven cancers. Utilizing robust methodologies in the QIIME 2 platform, we examined 16S rRNA vaginal and rectal microbiome data from an EC cohort: 192 women with benign gynecologic conditions, endometrial hyperplasia, or endometrial cancer. Distinct microbial compositions and community networks specific to EC were identified and related to histological grade with adjustments for EC risk factors. Vaginal health-associated Lactobacillus and Limosilactobacillus, and rectal Prevotella and Peptoniphilus, were depleted in EC, while detrimental vaginal Anaerococcus, Porphyromonas, Prevotella, Peptoniphilus, and rectal Buttiaxella were enriched. Significant bacterial features were shared between rectal and vaginal sites in EC, such as Prevotella timonensis and Peptoniphilus A. Vaginal Lactobacillus abundance contributed to less feature sharing from the rectum. Putative microbial metabolic analysis identified dysregulation of amino acid, complex carbohydrate, and hormone metabolism amongst patients with EC.

Effects of cold environment exposure on female reproductive health and its regulatory mechanisms

Objective

To investigate the effects of cold environment exposure on female reproductive capacity and explore its potential regulatory mechanisms.

Methods

Female mice were subjected to cold water immersion to simulate cold environment exposure. Weight changes during cold exposure were recorded. Serum levels of anti-Müllerian hormone (AMH), estradiol (E2), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were measured using enzyme-linked immunosorbent assay (ELISA). Ovarian and uterine tissues were collected via surgical procedures, and transcriptomic sequencing was performed to explore potential regulatory mechanisms. ELISA was used to assess the levels of inflammatory cytokines, including interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-18 (IL-18), and tumor necrosis factor-alpha (TNF-α) in peritoneal fluid. Furthermore, immunohistochemistry was used to detect the expression levels of IL-1, IL-6, and IL-18 in ovarian tissues, as well as IL-6 and IL-18 in uterine tissues.

Results

Compared with the control group, female mice exposed to cold environments exhibited a significant increase in body weight and elevated serum levels of AMH, E2, FSH, and LH. Transcriptomic sequencing of ovarian and uterine tissues indicated that differentially expressed genes were primarily enriched in inflammation-related pathways, including the cAMP signaling pathway, cytokine-cytokine receptor interaction, and PI3K-Akt signaling pathway. Additionally, levels of inflammatory cytokines in the peritoneal fluid, including IL-1β, IL-6, IL-18, and TNF-α, were significantly elevated. Immunohistochemical analysis showed that the expression levels of IL-1, IL-6, and IL-18 were markedly increased in ovarian tissue, while IL-6 and IL-18 expression levels were significantly elevated in uterine tissue. These differences were statistically significant (P < 0.05).

Conclusion

Cold environment exposure may induce inflammatory responses in the uterus and ovaries, contributing to the formation of an inflammatory microenvironment in the reproductive system. This process may lead to disruptions in sex hormone levels and ultimately impair female reproductive capacity.

Microbiome-Maternal Tract Interactions in Women with Recurrent Implantation Failure

Microorganisms play an important role in regulating various biological processes in our bodies. In women, abnormal changes in the reproductive tract microbiome are associated with various gynecological diseases and infertility. Recent studies suggest that patients with recurrent implantation failure (RIF) have a reduced genus Lactobacillus population, a predominant bacterial species in the vagina and uterus that protects the reproductive tract from pathogenic bacterial growth via the production of various metabolites (e.g., lactic acid, bacteriocin, and H2O2). Moreover, a higher percentage of pathogenic bacteria genera, including Atopobium, Gardnerella, Prevotella, Pseudomonas, and Streptococcus, was found in the uterus of RIF patients. This review aimed to examine the role of pathogenic bacteria in RIF, determine the factors altering the endometrial microbiome, and assess the impact of the microbiome on embryo implantation in RIF. Several factors can influence microbial balance, including the impact of extrinsic elements such as semen and antibiotics, which can lead to dysbiosis in the female reproductive tract and affect implantation. Additionally, probiotics such as Lacticaseibacillus rhamnosus were reported to have clinical potential in RIF patients. Future studies are needed to develop targeted probiotic therapies to restore microbial balance and enhance fertility outcomes. Research should also focus on understanding the mechanisms by which microorganisms generate metabolites to suppress pathogenic bacteria for embryo implantation. Identifying these interactions may contribute to innovative microbiome-based interventions for reproductive health.

Impact of maternal obesity and mode of delivery on the newborn skin and oral microbiomes

Introduction. Previous studies have shown vast differences in the skin and oral microbiomes of newborns based on delivery method [Caesarean section (C-section) vs vaginal]. Exposure to or absence of certain bacteria during delivery can impact the neonate's future susceptibility to infections, allergies or autoimmunity by altering immune functions. Few studies have focused on the impact of maternal obesity on the variations of newborn skin and oral microbiomes. Obese pregnant women typically have a higher vaginal microbiome diversity, and their pregnancies are at higher risk for adverse outcomes and complications.Hypothesis. We hypothesized that the skin and oral microbiomes of newborns born to obese mothers would include more diverse, potentially pathogenic bacteria and that the skin and oral microbiome in C-section delivered newborns would be less diverse than vaginally delivered newborns.Aim. We aim to begin to establish maternal obesity and mode of delivery as factors contributing to increased risk for negative newborn outcomes through impacts on newborn bacterial dysbiosis.Methodology. A skin swab was collected immediately following delivery of 39 newborns from 13 healthy weight body mass index (BMI 18.50-24.99), 11 overweight (BMI 25.0-29.99) and 15 obese (BMI ≥30.00) pregnant participants. An oral swab was collected immediately following delivery for 38 of these newborns from 13 healthy weight, 10 overweight and 15 obese pregnant participants. Bacterial genera were identified via 16S rRNA amplicon sequencing.Results. The newborn skin microbiome was comprised of typical skin bacteria (i.e. Corynebacterium). Newborns of obese participants had a higher relative abundance of Peptoniphilus in their skin microbiome compared to newborns of healthy weight participants (P=0.007). Neonates born via C-section had a higher relative abundance of Ureaplasma in their oral microbiome compared to neonates delivered vaginally (P=0.046).Conclusion. We identified differences in the newborn skin and oral microbiomes based on pre-pregnancy BMI and method of delivery. These differences could be linked to an increased risk of allergies, autoimmune disease and infections. Future longitudinal studies will be crucial in determining the long-term impact of these specific genera on newborn outcomes. Understanding these connections could lead to targeted interventions that reduce the risk of adverse outcomes and improve overall health trajectory.

All Properties of Infertility Microbiome in a Review Article

BACKGROUND

The microbiome is crucial for many physiological processes, including immunity, metabolism, and reproduction.

AIMS

This review aims to contribute to a detailed understanding of the microbiome of the genital tract, which can lead to better management of dysbiosis and reproductive disorders.

METHODS

Data from the four international information databases Medline, Scopus, Embase, and Google Scholar. The search strategy was based on the combination of the following terms: "microbiota," "microbiome," "microfilm," "microflora," "fertility," or "infertility."

RESULT

The advent of next-generation sequencing-based technologies during the last decade has revealed the presence of microbial communities in nearly every part of the human body, including the reproductive system. Several studies have shown significant differences between the microbiota of the vagina and endometrium, as well as other parts of the upper genital tract.

DISCUSSION

The human microbiome plays a critical role in determining a person's health state, and the microbiome of the genital tract may impact fertility potential before and after assisted reproductive treatments (ARTs).

CONCLUSION

To completely understand the role of the microbiome, future research should focus not only on the description of microbiota but also on the interaction between bacteria, the production of biofilms, and the interaction of microorganisms with human cells.

An Analysis of the Digestive and Reproductive Tract Microbiota in Infertile Women with Obesity

Previous studies have linked the microbiome of distinct body habitats to obesity and infertility; however, the often-divergent results observed have left the role of the so-called "second genome" in obese infertile patients incompletely explored. Here, we present a prospective observational multicenter study of oral, gut, endometrial, and vaginal microbiota of infertile patients classified according to BMI. Patients collected saliva/fecal samples, while vaginal/endometrial fluid samples were collected in the clinic. Total bacterial DNA was extracted, and microbiota profiles were analyzed by 16S rRNA gene sequencing. Our results showed no differences in the Bacteroidetes/Firmicutes ratio (proposed obesity hallmark) in the gut microbiota between patients with obesity and normal weight; however, a tendency for higher levels of genera such as Escherichia-Shigella in normal-weight patients was observed; in comparison, patients with obesity possessed increased numbers of Parasutterella and Roseburia. In the reproductive tract, vaginal samples possessed a similar microbiota to endometrial fluid, both largely colonised by Lactobacillus, Gardnerella, and Streptococcus, supporting the hypothesis that uterine colonisation proceeds from vaginal bacteria ascension. Additionally, higher prevalence of a Streptococcus-dominated (>50%) endometrial microbiota was observed among patients with obesity. This first description of the human digestive and reproductive tract microbiota in infertile women with obesity may explain their poor reproductive outcomes.

Viewing Native American Cervical Cancer Disparities through the Lens of the Vaginal Microbiome: A Pilot Study

Vaginal dysbiosis is implicated in persistent human papillomavirus (HPV) infection and cervical cancer. Yet, there is a paucity of data on the vaginal microbiome in Native American communities. Here, we aimed to elucidate the relationships between microbiome, HPV, sociodemographic, and behavioral risk factors to better understand an increased cervical cancer risk in Native American women. In this pilot study, we recruited 31 participants (16 Native American and 15 non-Native women) in Northern Arizona and examined vaginal microbiota composition, HPV status, and immune mediators. We also assessed individuals' sociodemographic information and physical, mental, sexual, and reproductive health. Overall, microbiota profiles were dominated by common Lactobacillus species (associated with vaginal health) or a mixture of bacterial vaginosis-associated bacteria. Only 44% of Native women exhibited Lactobacillus dominance, compared with 58% of non-Native women. Women with vaginal dysbiosis also had elevated vaginal pH and were more frequently infected with high-risk HPV. Furthermore, we observed associations of multiple people in a household, lower level of education, and high parity with vaginal dysbiosis and abundance of specific bacterial species. Finally, women with dysbiotic microbiota presented with elevated vaginal levels of proinflammatory cytokines. Altogether, these findings indicate an interplay between HPV, vaginal microbiota, and host defense, which may play a role in the cervical cancer disparity among Native American women. Future longitudinal studies are needed to determine the mechanistic role of vaginal microbiota in HPV persistence in the context of social determinants of health toward the long-term goal of reducing health disparities between non-Hispanic White and Native American populations. Prevention Relevance: Cervical cancer disproportionally affects Native American women. Sociodemographic and behavioral factors might contribute to this disparity via alteration of vaginal microbiota. Here, we show the association between these factors and vaginal dysbiosis and immune activation, which can be implicated in high-risk HPV infection among Native American and other racial/ethnic populations.

The vaginal microbiota of healthy female cats

The vaginal microbiota of the queen (i.e., female cat) has never been described using culture independent methods. The objectives of the present research were to describe the vaginal microbiota of healthy domestic shorthair queens using both 16S rRNA sequencing and culture, and to assess the effects of age, living environment, and reproductive season on its composition. Thirty queens undergoing elective ovariectomy were included in the study. The vaginal samples were collected just before surgery, from animals under general anaesthesia. Two consecutive mini-swabs were introduced in the queens' vaginal tract. A preliminary study with 10 healthy queens aimed to negate sampling order's effect. Two consecutive samples for sequencing (5 queens, 10 swabs) and culture (5 queens, 10 swabs) were collected, confirming a match (100 % in culture, Bray-Curtis P = 0.96 in sequencing). The experiment included 20 queens that were prospectively grouped based on age (prepubertal N = 10, adult N = 10), living environment (indoor N = 10, outdoor N = 10), and time of the year, whether during the reproductive season (N = 10) or during seasonal anoestrous (N = 10). Bacteria were identified through metataxonomic analysis, amplifying the V1-V2 regions of 16S rRNA gene, and through standard culture followed by MALDI-TOF MS. The feline vaginal microbiota is dominated by Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteria. Escherichia-Shigella, Streptococcus, and Pasteurella were the most abundant genera. Although culture underestimated bacterial richness and diversity compared to sequencing, Escherichia and Streptococcus were the most isolated bacteria. No bacterial growth was observed in 15 % of samples (N = 3/20), whereas growth of one or two bacterial species was observed in 64.7 % (N = 11/17) and 35.3 % (N = 6/17) of cases, respectively. No differences in terms of alpha (Kruskal-Wallis rank sum test P = 0.65) and beta diversity (Bray-Curtis, Unweighted and Weighted UniFrac analyses P > 0.5) were observed. Although a difference in alpha diversity based on phylogenetic tree (P = 0.02) was detected between indoor and outdoor queens. In conclusion, mixed and monoculture of Escherichia coli, Streptococcus canis, Staphylococcus felis, and Enterococcus spp. are normal findings within the cat vagina. Age and reproductive season do not influence the feline vaginal microbiota, whereas further research is needed to elucidate the role of the living environment.

Testing on bacterial vaginosis in a subfertile population and time to pregnancy: a prospective cohort study

PURPOSE

This study aimed to investigate the influence of bacterial vaginosis on time to pregnancy in subfertile couples.

METHODS

Couples attending a teaching hospital in the Netherlands having an initial fertility assessment (IFA) between July 2019 and June 2022 were included in this prospective study, with follow-up of pregnancies until June 2023. Vaginal samples at IFA were analyzed on pH, qPCR BV, and 16S rRNA gene microbiome analysis of V1-V2 region. Main outcome measures were time from initial fertility assessment to ongoing pregnancy at 12 weeks and live birth, analyzed by Kaplan-Meier and Cox regression with adjustment for potential confounders.

RESULTS

At IFA, 27% of 163 included participants tested positive for BV. BV status had no influence on time to ongoing pregnancy (HR 0.98, 0.60-1.61, aHR 0.97, 0.58-1.62). In persons with unexplained subfertility, positive BV status had a tendency of longer time to pregnancy. When persons had an indication for fertility treatment, positive BV status (HR 0.21, 0.05-0.88, aHR 0.19, 0.04-0.85) and microbiome community state type III and type IV had significant longer time to pregnancy.

CONCLUSION

This study indicates that BV may have a potential negative impact on time to live birth pregnancy in subfertile persons with an indication for fertility treatment. This study did not find an association between BV and time to live birth pregnancy in a general group of subfertile couples or in unexplained subfertility. More research should be done in persons with unexplained subfertility and if treatment improves time to pregnancy.

Obesity and sexual health: focus on postmenopausal women

Menopause is a cardiometabolic transition with many women experiencing weight gain and redistribution of body fat. Hormonal changes may affect also several dimensions of well-being, including sexual function, with a high rate of female sexual dysfunction (FSD), which displays a multifactorial etiology. The most important biological factors range from chronic low-grade inflammation, associated with hypertrophic adipocytes that may translate into endothelial dysfunction and compromised blood flow through the genitourinary system, to insulin resistance and other neuroendocrine mechanisms targeting the sexual response. Psychosocial factors include poor body image, mood disorders, low self-esteem and life satisfaction, as well as partner's health and quality of relationship, and social stigma. Even unhealthy lifestyle, chronic conditions and putative weight-promoting medications may play a role. The aim of the present narrative review is to update and summarize the state of the art on the link between obesity and FSD in postmenopausal women, pointing to the paucity of high-quality studies and the need for further research with validated end points to assess both biomarkers of obesity and FSD. In addition, we provide general information on the diagnosis and treatment of FSD at menopause with a focus on dietary interventions, physical activity, anti-obesity drugs and bariatric surgery.