Impact of Topical Interventions on the Vaginal Microbiota and Metabolome in Postmenopausal Women: A Secondary Analysis of a Randomized Clinical Trial

Assessment of the vaginal microbiota before and after use of hyperosmolal lubricant during transvaginal ultrasound

BACKGROUND

Vaginal lubricants are commonly used during sexual activity and clinical procedures such as transvaginal ultrasound. Epidemiologic and laboratory studies indicate hyperosmolal water-based lubricants may disrupt the vaginal microbiota, particularly the beneficial Lactobacillus spp. These bacteria play a critical role in protecting against sexually transmitted infection acquisition and other adverse gynecologic and obstetric outcomes.

OBJECTIVE

We sought to evaluate changes in the composition of the vaginal microbiota before and after a single exposure to lubricant over a 10-week period among pre-, peri-, and postmenopausal patients referred for transvaginal ultrasound.

STUDY DESIGN

One hundred four participants self-collected mid-vaginal swabs daily between baseline and transvaginal ultrasound (∼1 week), immediately before transvaginal ultrasound ("pre-transvaginal ultrasound"), and 6 to 12 hours after transvaginal ultrasound ("post-transvaginal ultrasound"). Participants attended a follow-up visit ∼2 to 5 days after transvaginal ultrasound ("post-transvaginal ultrasound follow-up"), continued to self-sample twice-weekly for 9 weeks, and attended a final clinical visit in week 10. Microbiota composition was characterized by 16S ribosomal RNA gene amplicon sequencing (V3-V4) and assigned to community state types (low-Lactobacillus vs Lactobacillus-dominated). Yue-Clayton theta indices defined similarity between daily successive samples between baseline and transvaginal ultrasound and overall stability of the vaginal microbiota before and after transvaginal ultrasound. Analysis of Compositions of Microbiomes II determined differentially abundant taxa in post-transvaginal ultrasound samples vs pre-transvaginal ultrasound samples. Generalized linear mixed models evaluated the odds of having a low-Lactobacillus microbiota after transvaginal ultrasound with samples before transvaginal ultrasound as the reference for each participant.

RESULTS

A majority of the cohort was premenopausal (85/104, 82%) and self-reported Black race (65/104, 62%). Over the short-term (1 week), there was no immediate changes in the composition of the microbiota of daily successive samples following transvaginal ultrasound. In contrast, over the longer-term (participants followed for 10 weeks), the vaginal microbiota was less stable within intervals after transvaginal ultrasound vs the interval before. There were no changes in the odds of a low-Lactobacillus microbiota after transvaginal ultrasound among all participants in this 10-week longitudinal study. However, in specific groups such as peri/postmenopausal participants (N=19, adjusted odds ratio: 3.22, 95% confidence interval:1.16-8.98) and those with a history of bacterial vaginosis (N=58, adjusted odds ratio: 1.73, 95% confidence interval:1.10-2.72), there was a higher likelihood of persisting in a low-Lactobacillus state throughout the follow-up period.

CONCLUSION

Peri- and postmenopausal individuals and those with a history of bacterial vaginosis show a sustained decrease in protective Lactobacillus spp. after a single exposure to hyperosmolal vaginal lubricant. Reformulating water-based lubricants to reduce osmolality and toxicity may be beneficial.

A Novel Insight into Postmenopausal Hypercholesterolemia: Carnitine as a Key Player

Background: Postmenopausal women (post-MW) are at a heightened risk of cardiovascular diseases, including hypercholesterolemia. This study aimed to investigate metabolomic variations to identify potential markers and targets for postmenopausal hypercholesterolemia. Methods: Sixty-two female volunteers aged 40-65 were recruited for this study. Metabolomic analysis using the Ultra-Performance Liquid Chromatography Quadrupole Orbitrap Mass Spectrometry (UPLC-Q-Orbitrap MS) platform was conducted to investigate changes in endogenous substances in premenopause (n = 25) and postmenopause (n = 37) women. Following ovariectomy surgery, menopausal mice were monitored for changes in their biomarker levels, and the integrity of the large artery walls in each treatment group was observed through hematoxylin and eosin staining. In vitro cellular models were utilized to assess variations in lipid metabolism, reactive oxygen species (ROS) levels, and changes in the levels of superoxide dismutase and glutathione peroxidase enzymes in different cell groups postintervention using Western blot analysis. Results: Treatment with carnitine in postmenopausal mouse models led to increased plasma cholesterol and carnitine levels, as well as indicators of arterial sclerosis. In HepG2 cells, carnitine treatment resulted in heightened lipid levels, elevated ROS production, and decreased antioxidant enzyme levels. Conclusions: The findings suggest that carnitine may serve as a potential risk marker or therapeutic target for postmenopausal hypercholesterolemia. This study provides valuable insights into cardiovascular conditions in post-MW and offers new avenues for therapeutic interventions. Continued research in this area is crucial to enhance our understanding of cardiovascular diseases in post-MW and to explore additional treatment options.

Vaginal microbiota, menopause, and the use of menopausal hormone therapy: a cross-sectional, pilot study in Chinese women

OBJECTIVE

To compare the vaginal microbiota of premenopausal and postmenopausal women and postmenopausal women undergoing menopausal hormone therapy (MHT) and examine the association between vaginal microbiota and genitourinary syndrome of menopause (GSM).

METHODS

This cross-sectional study classified 94 women aged 40 to 60 years into three groups: premenopausal (Pre, n = 32), postmenopausal (Post, n = 30), and postmenopausal women who received MHT orally (Post + MHT, n = 32). Neither the Pre nor the Post group received hormone therapy within the past 6 months. Postmenopausal women who received vaginal MHT were not included. Vaginal swabs were obtained, and microbial composition was characterized by 16S rRNA gene sequencing targeting the V3 to V4 region. Clinical data were collected and serum sex hormones were measured. The most bothersome symptom approach and vaginal health index were used to evaluate GSM. Mann-Whitney U or Kruskal-Wallis ANOVA followed by multiple comparison tests were performed for comparison between or across groups. The correlations between GSM symptom scores and vaginal microbiota were determined using Spearman's correlation analysis.

RESULTS

The vaginal community of postmenopausal women was characterized by a decreased abundance of Lactobacillus (Post 18% vs Pre 69%); an increased abundance of several anaerobic bacteria, including Prevotella , Escherichia-Shigella , and Bifidobacterium ; and a higher microbial diversity ( P < 0.001 for Shannon and Simpson indexes) than those of premenopausal women. The vaginal community of postmenopausal women who received MHT had an increased abundance of Lactobacillus (54%) and lower microbial diversity ( P < 0.001 for Shannon and Simpson indexes) than the postmenopausal women. The vaginal microbial community composition of the Pre group shared more similarity with that of the Post + MHT group (Adonis P = 0.051) than with that of the Post group (Adonis P < 0.001). A decreased abundance of Lactobacillus and high diversity in the vaginal community were found in women with moderate to severe GSM symptoms.

CONCLUSIONS

Among Chinese postmenopausal women, those receiving MHT had higher Lactobacillus abundance but lower abundance of diverse anaerobes and diversity of the vaginal microbial community compared to non-MHT women. MHT in postmenopausal women may potentially contribute to reestablishing vaginal microbiota homeostasis. Findings in this pilot study, however, need to be examined in larger, prospective studies.

Association between vaginal microbiota and vaginal inflammatory immune markers in postmenopausal women

OBJECTIVE

In premenopausal individuals, vaginal microbiota diversity and lack of Lactobacillus dominance are associated with greater mucosal inflammation, which is linked to a higher risk of cervical dysplasia and infections. It is not known if the association between the vaginal microbiota and inflammation is present after menopause, when the vaginal microbiota is generally higher-diversity and fewer people have Lactobacillus dominance.

METHODS

This is a post hoc analysis of a subset of postmenopausal individuals enrolled in a randomized trial for treatment of moderate-severe vulvovaginal discomfort that compared vaginal moisturizer, estradiol, or placebo. Vaginal fluid samples from 0, 4, and 12 weeks were characterized using 16S rRNA gene sequencing (microbiota) and MesoScale Discovery (vaginal fluid immune markers: IL-1b, IL-1a, IL-2, IL-6, IL-18, IL-10, IL-9, IL-13, IL-8, IP10, MIP1a, MIP1b, MIP3a). Global associations between cytokines and microbiota (assessed by relative abundance of individual taxa and Shannon index for alpha, or community, diversity) were explored, adjusting for treatment arm, using linear mixed models, principal component analysis, and Generalized Linear Mixed Model + Microbiome Regression-based Kernel Association Test (GLMM-MiRKAT).

RESULTS

A total of 119 individuals with mean age of 61 years were included. At baseline, 29.5% of participants had a Lactobacillus -dominant vaginal microbiota. Across all timepoints, alpha diversity (Shannon index, P = 0.003) was highly associated with immune markers. Individual markers that were associated with Lactobacillus dominance were similar to those observed in premenopausal people: IL-10, IL-1b, IL-6, IL-8 (false discovery rate [FDR] < 0.01), IL-13 (FDR = 0.02), and IL-2 (FDR = 0.09). Over 12 weeks, change in alpha diversity was associated with change in cytokine concentration (Shannon, P = 0.018), with decreased proinflammatory cytokine concentrations observed with decreasing alpha diversity.

CONCLUSIONS

In this cohort of postmenopausal individuals, Lactobacillus dominance and lower alpha diversity were associated with lower concentrations of inflammatory immune markers, as has been reported in premenopausal people. This suggests that after menopause lactobacilli continue to have beneficial effects on vaginal immune homeostasis, despite lower prevalence.

Longitudinal profiles of the vaginal microbiota of pre-, peri-, and postmenopausal women: preliminary insights from a secondary data analysis

OBJECTIVE

Menopause is often accompanied by lowered Lactobacillus spp. relative abundance and increased abundance of diverse anaerobic/aerobic bacteria in the vaginal microbiota due in part to declines in estrogen. These microbiota are associated with urogenital symptoms and infections. In premenopause, vaginal microbiota can fluctuate rapidly, particularly with menstrual cycles and sexual activity; however, the longitudinal dynamics of vaginal microbiota are understudied in peri- and postmenopause. We described vaginal community stability across reproductive stages.

METHODS

Pre- (n = 83), peri- (n = 8), and postmenopausal (n = 11) participants provided twice-weekly mid-vaginal samples (total, 1,556; average, 15 per participant) over 8 weeks in an observational study. Composition of the vaginal microbiota was characterized by 16S rRNA gene amplicon sequencing, and a community state type (CST) was assigned to each sample. Clustering of longitudinal CST profiles, CST transition rates, duration of low-Lactobacillus/high bacterial diversity CSTs, and other metrics of bacterial community dynamics were assessed across reproductive stages.

RESULTS

The proportion of participants with longitudinal CST profiles characterized by low-Lactobacillus CSTs was similar among pre- (38.6%), peri- (37.5%), and postmenopausal (36.4%) participants (P = 0.69). CST transition rates between consecutive samples were 21.1%, 16.7%, and 14.6% for pre-, peri-, and postmenopausal participants, respectively (P = 0.49). Low-Lactobacillus CST tended to persist for at least 4 weeks, irrespective of reproductive stage.

CONCLUSIONS

Findings from this small yet frequently sampled cohort revealed vaginal bacterial fluctuations over 8 weeks that were similar across reproductive stages. Larger and longer-term studies based on these preliminary data could provide insights into the influence of microbiota dynamics on urogenital outcomes during menopause.

Change in microbiota profile after vaginal estriol cream in postmenopausal women with stress incontinence

Introduction

Vaginal estrogen is a treatment for genitourinary symptoms of menopause (GSM), which comprises vaginal atrophy and urinary dysfunction, including incontinence. Previous studies show that estrogen therapy promotes lactobacilli abundance and is associated with reduced GSM symptoms, including reduction of stress incontinence. However, detailed longitudinal studies that characterize how the microbiome changes in response to estrogen are scarce. We aimed to compare the vaginal microbiota of postmenopausal women, before and 12 weeks after vaginal estrogen cream.

Methods

A total of 44 paired samples from 22 postmenopausal women with vaginal atrophy and stress incontinence were collected pre-vaginal estrogens and were compared to 12 weeks post-vaginal estrogen. Microbiota was characterized by 16S rRNA amplicon sequencing and biodiversity was investigated by comparing the alpha- and beta-diversity and potential markers were identified using differential abundance analysis.

Results

Vaginal estrogen treatment was associated with a reduction in vaginal pH and corresponded with a significant reduction in alpha diversity of the microbiota. Healthy vaginal community state type was associated with lower mean pH 4.89 (SD = 0.6), in contrast to dysbiotic state which had a higher mean pH 6.4 (SD = 0.74). Women with lactobacilli dominant community pre-treatment, showed stable microbiota and minimal change in their pH. Women with lactobacilli deficient microbiome pre-treatment improved markedly (p = 0.004) with decrease in pH -1.31 and change to heathier community state types.

Conclusion

In postmenopausal women with stress incontinence, vaginal estrogen promotes Lactobacillus and Bifidobacterium growth and lowers vaginal pH. Maximum response is seen in those with a dysbiotic vaginal microbiota pre-treatment.

Metabolites: a converging node of host and microbe to explain meta-organism

Meta-organisms encompassing the host and resident microbiota play a significant role in combatting diseases and responding to stress. Hence, there is growing traction to build a knowledge base about this ecosystem, particularly to characterize the bidirectional relationship between the host and microbiota. In this context, metabolomics has emerged as the major converging node of this entire ecosystem. Systematic comprehension of this resourceful omics component can elucidate the organism-specific response trajectory and the communication grid across the ecosystem embodying meta-organisms. Translating this knowledge into designing nutraceuticals and next-generation therapy are ongoing. Its major hindrance is a significant knowledge gap about the underlying mechanisms maintaining a delicate balance within this ecosystem. To bridge this knowledge gap, a holistic picture of the available information has been presented with a primary focus on the microbiota-metabolite relationship dynamics. The central theme of this article is the gut-brain axis and the participating microbial metabolites that impact cerebral functions.

The Postmenopausal Vaginal Microbiome and Genitourinary Syndrome of Menopause

This review summarizes our current understanding of associations of the postmenopausal vaginal microbiome with genitourinary syndrome of menopause. We review the normal postmenopausal microbiota, examine the association of the microbiome with vulvovaginal symptoms, describe microbial communities associated with physical and laboratory findings, and report the impact of different treatments for genitourinary syndrome of menopause on microbiota and symptom improvement. Postmenopausal vaginal symptoms have an underlying pathophysiology that has not been fully elucidated. Estrogen treatment may not be sufficient to relieve symptoms of vaginal discomfort in all postmenopausal individuals. In addition, other interventions targeted at changing the microbiota or pH do not consistently improve symptom severity.

Changes in the Vaginal Microbiome During Pregnancy and the Postpartum Period in South African Women: a Longitudinal Study

Pregnant women in sub-Saharan Africa have high rates of maternal morbidity. There is interest in the impact of the vaginal microbiome on maternal health, including HIV and sexually transmitted infection (STI) acquisition. We characterized the vaginal microbiota of South African women ≥ 18 years with and without HIV in a longitudinal cohort over two visits during pregnancy and one visit postpartum. At each visit, we obtained HIV testing and self-collected vaginal swabs for point-of-care testing for STIs and microbiota sequencing. We categorized microbial communities and evaluated changes over pregnancy and associations with HIV status and STI diagnosis. Across 242 women (mean age 29, 44% living with HIV, 33% diagnosed with STIs), we identified four main community state types (CSTs): two lactobacillus-dominant CSTs (dominated by Lactobacillus crispatus and Lactobacillus iners respectively) and two diverse, non-lactobacillus-dominant CSTs (one dominated by Gardnerella vaginalis and one by diverse facultative anaerobes). From the first antenatal visit to the third trimester (24-36 weeks gestation), 60% of women in the Gardnerella-dominant CST shifted to lactobacillus-dominant CSTs. From the third trimester to postpartum (mean 17 days post-delivery), 80% of women in lactobacillus-dominant CSTs shifted to non-lactobacillus-dominant CSTs with a large proportion in the facultative anaerobe-dominant CST. Microbial composition differed by STI diagnosis (PERMANOVA R2 = 0.002, p = 0.004), and women diagnosed with an STI were more likely to be categorized as L. iners-dominant or Gardnerella-dominant CSTs. Overall, we found a shift toward lactobacillus dominance during pregnancy and the emergence of a distinct, highly diverse anaerobe-dominant microbiota profile in the postpartum period.

The role of microbiota in the management of genitourinary syndrome of menopause

It is estimated that the 25-50% of women who are reaching menopause every year report symptoms related to the genitourinary syndrome of menopause (GSM). The symptoms are not due simply to lack of estrogen. One possible contributing cause of symptoms is the vaginal microbiota. The vaginal microbiota is a dynamic entity and plays a critical role in the pathogenic interplay of postmenopausal changes. Treatment of this syndrome depends on the severity and type of the symptoms and on the preferences and expectations of women. As there are many treatment options, therapy should be individualized. While new evidence on the role of Lactobacilli in premenopause is emerging, the role of Lactobacilli is still unclear in GSM and the impact of microbiota on vaginal health remains conflictual. However, some reports show promising data on the effect of probiotic therapy in menopause. In the literature there are few studies and small population samples on the role of an exclusive therapy with Lactobacilli and further data will be mandatory. Studies involving large numbers of patients and different intervention periods will be necessary to obtain evidence of the preventive and curative role of vaginal probiotics.

Changes in the vaginal microbiome during pregnancy and the postpartum period in South African women: a longitudinal study

African women have more diverse vaginal microbiota than women of European descent, and there is interest in the impact of this diversity on maternal health, including HIV and STI acquisition. We characterized the vaginal microbiota in a cohort of women ≥ 18 years with and without HIV in a longitudinal cohort over two visits during pregnancy and one visit postpartum. At each visit we obtained HIV testing and self-collected vaginal swabs for point of care testing for STIs and microbiome sequencing. We categorized microbial communities and evaluated changes over pregnancy and associations with HIV status and STI diagnosis. Across 242 women (mean age 29, 44% living with HIV, 33% diagnosed with STIs), we identified four main community state types (CSTs): two lactobacillus-dominant CSTs (dominated by Lactobacillus crispatus and Lactobacillus iners respectively) and two diverse, non-lactobacillus-dominant CSTs (one dominated by Gardnerella vaginalis and one by other facultative anaerobes). From first antenatal visit to third trimester (24-36 weeks gestation), 60% of women in the Gardnerella -dominant CST shifted to L actobacillus -dominant CSTs. From third trimester to postpartum (mean 17 days post-delivery), 80% of women in Lactobacillus -dominant CSTs shifted to non-lactobacillus-dominant CSTs with a large proportion in the facultative anaerobe-dominant CST. Microbial composition differed by STI diagnosis (PERMANOVA R 2  = 0.002, p = 0.004), and women diagnosed with an STI were more likely to be categorized with L. iners -dominant or Gardnerella -dominant CSTs. Overall we found a shift toward lactobacillus dominance during pregnancy, and the emergence of a distinct, highly diverse anaerobe-dominant microbiome population in the postpartum period.

Bacterial Vaginosis in Postmenopausal Women

Purpose of Review

Bacterial vaginosis (BV) is the most common vaginal infection worldwide, but most research has been conducted in premenopausal women. After menopause, endogenous estrogen production decreases, often leading to the genitourinary syndrome of menopause (GSM), characterized by vulvovaginal dryness and irritation. The estrogen-deficient postmenopausal state results in an elevated vaginal pH and depletion of vaginal lactobacilli. Use of traditional BV diagnostics (Amsel criteria, Nugent score) is difficult in post-menopausal women, especially those not on estrogen replacement therapy, as these methods were originally developed in premenopausal women. In this review, we discuss recent clinical data on BV in postmenopausal women, difficulties in diagnosis using traditional methods, the role of BV molecular diagnostics, and our current expert opinion for managing BV in this population.

Recent Findings

BV prevalence has been found to range between 2%-57% among postmenopausal women per Amsel and Nugent criteria. This is likely an over-estimate of the true prevalence due to limitations in these criteria which were only validated in pre-menopausal women. Despite increasing diagnostic options for BV in recent years, including highly sensitive and specific BV nucleic acid amplification tests (NAATs), the physiologic changes of menopause and limited inclusion of postmenopausal women in clinical studies, diagnosis is difficult in this population. Recent studies utilizing 16s rRNA gene sequencing suggest that the vaginal microbiota of premenopausal and postmenopausal women is quite different, even if BV is not present. Data also suggest that obese postmenopausal women have significantly lower rates of BV compared to non-obese postmenopausal women, although further research is needed in this area. Multiple treatment options exist for vaginal atrophy and BV in this population.

Summary

Data are limited regarding optimal diagnostic approaches for BV in postmenopausal women; BV NAATs and 16s rRNA gene sequencing may have a role for diagnosing BV in symptomatic women although further studies are needed. Menopausal women with characteristic vaginal symptoms and an elevated vaginal pH should be initially treated for estrogen deficiency prior to considering a diagnosis of BV; subsequent treatment for BV should be driven by symptoms.

Bringing pharmacomicrobiomics to the clinic through well-designed studies

Pharmacomicrobiomic studies investigate drug-microbiome interactions, such as the effect of microbial variation on drug response and disposition. Studying and understanding the interactions between the gut microbiome and drugs is becoming increasingly relevant to clinical practice due to its potential for avoiding adverse drug reactions or predicting variability in drug response. The highly variable nature of the human microbiome presents significant challenges to assessing microbes' influence. Studies aiming to explore drug-microbiome interactions should be well-designed to account for variation in the microbiome over time and collect data on confounders such as diet, disease, concomitant drugs, and other environmental factors. Here, we assemble a set of important considerations and recommendations for the methodological features required for performing a pharmacomicrobiomic study in humans with a focus on the gut microbiome. Consideration of these factors enable discovery, reproducibility, and more accurate characterization of the relationships between a given drug and the microbiome. Furthermore, appropriate interpretation and dissemination of results from well-designed studies will push the field closer to clinical relevance and implementation.