The Effect of Exogenous Sex Steroids on the Vaginal Microbiota: A Systematic Review

The microbiota in patients with interstitial cystitis/bladder pain syndrome: a systematic review

OBJECTIVE

To comprehensively review and critically assess the literature on microbiota differences between patients with interstitial cystitis (IC)/bladder pain syndrome (BPS) and normal controls and to provide clinical practice guidelines.

MATERIALS AND METHODS

In this systematic review, we evaluated previous research on microbiota disparities between IC/BPS and normal controls, as well as distinctions among IC/BPS subgroups. A comprehensive literature search was conducted across PubMed/MEDLINE, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials. Relevant studies were shortlisted based on predetermined inclusion and exclusion criteria, followed by quality assessment. The primary focus was identifying specific taxonomic variations among these cohorts.

RESULTS

A total of 12 studies met the selection criteria. Discrepancies were adjudicated by a third reviewer. The Newcastle-Ottawa Scale was used to assess study quality. Predominantly, the studies focused on disparities in urine microbiota between IC/BPS patients and normal controls, with one study examining gut microbiota differences between the groups, and two studies exploring vaginal microbiota distinctions. Unfortunately, analyses of discrepancies in other microbiota were limited. Our findings revealed evidence of distinct bacterial abundance variations, particularly involving Lactobacillus, alongside variations in specific metabolites among IC/BPS patients compared to controls.

CONCLUSIONS

Currently, there is evidence suggesting significant variations in the diversity and species composition of the urinary microbiota between individuals diagnosed with IC/BPS and control groups. In the foreseeable future, urologists should consider urine microbiota dysbiosis as a potential aetiology for IC, with potential clinical implications for diagnosis and treatment.

Distinct Gastrointestinal and Reproductive Microbial Patterns in Female Holobiont of Infertility

The microbiota is in symbiosis with the human body as a holobiont. Infertility conditions affect the female reproductive tract (FRT) and its resident microbiota. However, a disturbance in homeostasis could influence the FRT and other distal body sites, such as the gastrointestinal tract (GIT). We included 21 patients with endometriosis and other infertility-associated diseases with clinical profiles and biological samples from the FRT (endometrium, endometrial fluid, and vagina), and GIT samples (oral and feces). We performed a 16S rRNA analysis of site-specific microbial communities and estimated diversity metrics. The study found body site-specific microbial patterns in the FRT-GIT. In both study groups, Lactobacillus was the most shared Amplicon Sequence Variant (ASV), a precise identifier of microbial sequences, between endometrial and vagina samples. However, shared Gardnerella and Enterobacteriaceae ASVs were linked to other conditions but not endometriosis. Remarkably, Haemophilus was a specific GIT-shared taxon in endometriosis cases. In conclusion, infertility influences distinctly the FRT and GIT microbiomes, with endometriosis showing unique microbial characteristics. We proposed the concept of 'female holobiont' as a community that comprises the host and microbes that must maintain overall homeostasis across all body sites to ensure a woman's health. Insights into these microbial patterns not only advance our understanding of the pathophysiology of infertility but also open new avenues for developing microbe-based therapeutic interventions aimed at restoring microbial balance, thereby enhancing fertility prospects.

Recurrent Infectious Vaginitis: A Practical Approach for the Primary Care Clinician

Recurrent infectious vaginitis can lead to significant morbidity, patient frustration, and health care costs. The most common causes are bacterial vaginosis (BV) and vulvovaginal candidiasis (VVC); however, other infectious and noninfectious etiologies should be considered in patients with recurrent symptoms. A detailed history and physical examination with appropriate testing at the time of symptoms is critical to establishing a correct diagnosis. Management options for recurrent BV and VVC are limited. Complex cases including those with atypical symptoms, negative testing for common causes, refractory symptoms despite appropriate therapy or recurrences during suppressive therapy will require referral to specialist care.

Does the Vaginal Microbiome Operate Differently by Race to Influence Risk of Precervical Cancer?

Background: The vaginal microbiome (VMB) plays an important role in the persistence of human papillomavirus (HPV) infection and differs by race and among women with cervical intraepithelial neoplasia (CIN). Materials and Methods: We explored these relationships using 16S rRNA VMB taxonomic profiles of 3050 predominantly Black women. VMB profiles were assigned to three subgroups based on taxonomic markers indicative of vaginal wellness: optimal (Lactobacillus crispatus, L. gasseri, and L. jensenii), moderate (L. iners), and suboptimal (Gardnerella vaginalis, Atopobium vaginae, Ca. Lachnocurva vaginae, and others). Multivariable Firth logistic regression models were adjusted for age, smoking, VMB, HPV, and pregnancy status. Results: VMB prevalence by subgroup was 18%, 30%, and 51% for the optimal, moderate, and suboptimal groups, respectively. In fully adjusted models, the risk of CIN grade 3 (CIN3) among non-Latina (nL) Blacks was twice that of nL Whites (odds ratio [OR] = 2.0, 95% confidence interval [CI]: 1.1, 3.9, p = 0.02). The VMB modified this association (p = 0.04) such that the risk of CIN3 was significantly higher for nL Blacks than for nL Whites only among women with optimal VMBs (OR = 7.8, 95% CI: 1.7, 74.5, p = 0.007). Within racial groups, the risk of CIN3 was only elevated among nL White women with suboptimal VMBs (OR = 6.0, 95% CI: 1.3, 56.9, p = 0.02) compared with their racial counterparts with optimal VMBs. Conclusions: Our findings suggest that race is a modifier of the VMB in HPV carcinogenesis. An optimal VMB does not appear to be protective for nL Black women compared with nL White women.

The effects of hormone replacement therapy on the microbiomes of postmenopausal women

The sex steroid hormone estrogen plays a number of regulatory roles in female development. During menopause, estrogen synthesis in the ovaries decreases, which results in adverse physiological remodeling and increased risk of disease. Reduced bone density, changes in the community composition profiles of the gut and vaginal microbiome, mood swings and changes in the vaginal environment are to be expected during this time. To alleviate these changes, postmenopausal women can be prescribed hormone replacement therapy (HRT) through the use of exogenous estradiol, often in conjunction with progestin treatment, which re-induces estrogenic action throughout the body. The microbiome and estrogen have a bidirectional, regulatory relationship in the gut, while in the vaginal environment estrogen works indirectly on the microbiome through restoring the vaginal tissue environment that leads to microbial homeostasis. This review discusses what is known about how the gut and vaginal microbiomes of postmenopausal women are responding to HRT, and the potential future of microbe-based therapeutics for symptoms of menopause.

Optimizing the vaginal microbiome as a potential strategy to reduce heterosexual HIV transmission

Bacterial vaginosis (BV) is a proinflammatory genital condition characterized by high vaginal bacterial diversity and a paucity of Lactobacillus species. BV has been linked to an elevated risk of HIV acquisition among HIV-negative women and of forward HIV transmission to male sex partners among women living with HIV (adjusted hazard ratios of 1.69 and 3.17, respectively), potentially by eliciting genital inflammation in women with BV and their male sex partners. BV is also highly prevalent among women in sub-Saharan Africa, suggesting that BV treatment may have potential as an HIV prevention strategy. BV is typically treated with antibiotics but recurrence rates are high, possibly because treatment does not directly promote Lactobacillus growth. More recently, BV treatment strategies incorporating live biotherapeutic lactobacilli have led to sustained optimization of the vaginal microbiome and a decrease in inflammatory biomarkers previously associated with HIV susceptibility. Future studies are urgently needed to evaluate BV treatment strategies that can optimize the vaginal microbiome in the long term through colonization with H₂ O₂ -producing vaginal lactobacilli and to assess whether vaginal microbiota optimization is able to reduce the risk of HIV transmission.

Menopausal Changes in the Microbiome-A Review Focused on the Genitourinary Microbiome

A balanced interaction between the host and its microbiome is crucial to health. Research regarding the significance of the gut and vaginal microbiomes in female health is substantial. However, less data regarding the urinary microbiome are available. Interactions between the gut, vaginal, and urinary microbiomes are also currently being researched. Hormone-induced dysbiosis after menopause is believed to have effects on physical changes and health consequences. Postmenopausal changes in the gut microbiome are associated with increased short-chain fatty acids and hydrogen sulfide levels. Increased vaginal pH caused by reduced estrogen alters the vaginal microbiome, resulting in reduced levels of Lactobacillus. Such changes influence the vaginal structure and functions, contributing to the onset of genitourinary syndrome of menopause. A dysbiosis of the urinary microbiome is associated with urgency and urinary incontinence and also related to interstitial cystitis/bladder pain syndrome and neuropathic bladder. As these diseases commonly affect postmenopausal women, hormone-induced changes in the microbiome may play a role. Menopause increases the alpha diversity of the urinary microbiome and lowers the percentage of Lactobacillus in urine, and such changes precede recurrent cystitis. More research regarding the effects of changes in the urinary microbiome due to menopause on urinary tract diseases is needed.

Influence of Hormonal Contraceptive Use and HIV on Cervicovaginal Cytokines and Microbiota in Malawi

Important questions remain on how hormonal contraceptives alter the local immune environment and the microbiota in the female genital tract and how such effects may impact susceptibility to HIV infection. We leveraged samples from a previously conducted clinical trial of Malawian women with (n = 73) and without (n = 24) HIV infection randomized to depot medroxyprogesterone acetate (DMPA) or the levonogestrel implant in equal numbers within each group and determined the effects of these hormonal contraceptives (HCs) on the vaginal immune milieu and the composition of the vaginal microbiota. Longitudinal data for soluble immune mediators, measured by multiplex bead arrays and enzyme-linked immunosorbent assays (ELISAs), and vaginal microbiota, assessed by 16S rRNA gene amplicon, were collected prior to and over a period of 180 days post-HC initiation. DMPA and levonogestrel had only minimal effects on the vaginal immune milieu and microbiota. In women with HIV, with the caveat of a small sample size, there was an association between the median log₁₀ change in the interleukin-12 (IL-12)/IL-10 ratio in vaginal fluid at day 180 post-HC compared to baseline when these women were classified as having a community state type (CST) IV vaginal microbiota and were randomized to DMPA. Long-lasting alterations in soluble immune markers or shifts in microbiota composition were not observed. Furthermore, women with HIV did not exhibit increased viral shedding in the genital tract after HC initiation. Consistent with the results of the ECHO (Evidence for Contraceptive Options and HIV Outcomes) trial, our data imply that the progestin-based HC DMPA and levonorgestrel are associated with minimal risk for women with HIV. (This study has been registered at ClinicalTrials.gov under registration no. NCT02103660). IMPORTANCE The results of the Evidence for Contraceptive Options and HIV Outcomes (ECHO) trial, the first large randomized controlled clinical trial comparing the HIV acquisition risk of women receiving DMPA, the levonorgestrel (LNG) implant, or the copper intrauterine device (IUD), did not reveal an increased risk of HIV acquisition for women on any of these three contraceptives. Our study results confirm that the two different progestin-based hormonal contraceptives DMPA and levonogestrel will not increase the risk for HIV infection. Furthermore, DMPA and levonogestrel have only minimal effects on the immune milieu and the microbiota in the vaginal tract, attesting to the safety of these hormonal contraceptives.

Lactobacillus-dominance and rapid stabilization of vaginal microbiota in combined oral contraceptive pill users examined through a longitudinal cohort study with frequent vaginal sampling over two years

BACKGROUND

Bacterial vaginosis (BV), a condition in which vaginal Lactobacillus spp. are in low abundance, is associated with vulvovaginal symptoms, obstetric outcomes and urogenital infections. Recurrent BV is difficult to manage, and emerging data indicate a reduced risk of BV with the use of hormonal contraception (HC). Despite widespread use, little longitudinal data is available on whether, and in what timeframe, combined oral contraceptive pills (COCs) may act to affect vaginal microbiota stability and Lactobacillus dominance.

METHODS

We compared the vaginal microbiota of reproductive-age cisgender women during intervals on combined estrogen and progestin COCs with non-use intervals in a 2-year observational study. Vaginal microbiota were characterized by 16S rRNA gene amplicon sequencing.

FINDINGS

COC users were more likely to have Lactobacillus-dominated microbiota and more stable microbiota over time. Stability increased and then plateaued four weeks after COC initiation. The associations between COCs and Lactobacillus spp. dominance, and microbiota stability, were statistically significant for White, but not African American women; however sample size was limited for African American participants. Findings were similar for other forms of HC and when excluding samples collected during menses.

INTERPRETATION

Our study provides a methodologic framework to evaluate observational longitudinal microbiota data with exposure crossovers. We found COCs are associated with vaginal microbiota stability and a Lactobacillus-dominated state. COCs appear to impact stability within a month of initiation. Our findings have clinical implications for how soon benefits can be expected in (at least White) patients initiating COCs, and support the need for larger prospective trials to verify our results in ethnically diverse populations.

FUNDING

R01-AI089878.

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.

Roles of the Microbiota of the Female Reproductive Tract in Gynecological and Reproductive Health

The microbiome of the female reproductive tract defies the convention that high biodiversity is a hallmark of an optimal ecosystem. Although not universally true, a homogeneous vaginal microbiome composed of species of Lactobacillus is generally associated with health, whereas vaginal microbiomes consisting of other taxa are generally associated with dysbiosis and a higher risk of disease. The past decade has seen a rapid advancement in our understanding of these unique biosystems. Of particular interest, substantial effort has been devoted to deciphering how members of the microbiome of the female reproductive tract impact pregnancy, with a focus on adverse outcomes, including but not limited to preterm birth. Herein, we review recent research efforts that are revealing the mechanisms by which these microorganisms of the female reproductive tract influence gynecologic and reproductive health of the female reproductive tract.

The vaginal microbiome: A complex milieu affecting risk of human papillomavirus persistence and cervical cancer

The purpose of this review is to describe the existing literature regarding the relationship between the vaginal microbiome, human papillomavirus persistence, and cervical cancer risk, as well as to discuss factors that mediate these relationships. Data suggest that alterations in the vaginal microbiome affect the risk of human papillomavirus infection and persistence, which has downstream effects on cervical dysplasia and cancer risk. The homeostatic Lactobillus species L. crispatus, L. gasseri, L. jensenii act to promote a healthy vaginal environment, while L. iners and pathogens causing bacterial vaginosis are associated with increased inflammation, human papillomavirus infection, cervical dysplasia, and potentially cancer. There are, however, still several large gaps in the literature, particularly related to the modifiable and non-modifiable factors that affect the vaginal microbiome and ensuing risk of pre-cancerous and cancerous lesions. Evidence currently suggests that endogenous and exogenous hormones, tobacco products, and sexual practices influence vaginal microbiome composition, but the nuances of these relationships and how changes in these factors affect dysplasia risk are yet to be delineated. Other studies examining how diet, exercise, race, socioeconomic status, and genetic factors influence the vaginal microbiome are difficult to interpret in the setting of multiple confounders. Future studies should focus on how changes in these modulatory factors might promote a healthy vaginal microbiome to prevent or treat dysplasia in the lower female genital tract.

Effects of Depot Medroxyprogesterone Acetate Intramuscular Injection, Copper Intrauterine Device and Levonorgestrel Implant Contraception on Estradiol Levels: An Ancillary Study of the ECHO Randomized Trial

Introduction

Hormonal contraception affects endogenous sex steroid levels. Robust evidence from randomized trials of the relative effects of different contraceptive methods is scarce. We compared the effects of three contraceptive methods on serum estradiol levels using data from women (18–35 years) requesting contraception in the Evidence for Contraceptive Options and HIV Outcomes (ECHO) randomized trial.

Methods

Women were randomly allocated to the depot medroxyprogesterone acetate intramuscular (DMPA-IM) injection, copper intrauterine device (IUD) or levonorgestrel (LNG) implant. In this sub-study, stored baseline and 6-month serum samples were analyzed in 401 participants from East London, South Africa (DMPA-IM: 131, IUD: 135 and LNG: 135).

Results

Baseline median (interquartile range, IQR) estradiol levels were similar between the three groups [DMPA-IM 229 (152–455), IUD 235 (168–426) and LNG 216 (153–419 pmol/L)]. At 6-months, median estradiol in the IUD group was unchanged (298 (163–467) pmol/L), whilst levels in the DMPA-IM and implant groups were significantly reduced from baseline. The median estradiol level in the DMPA-IM group [139 (97–193) pmol/L] was significantly lower than in both IUD (p < 0.0001) and implant (p = 0.005) groups; and level in the implant group [156 (112–250) pmol/L] was significantly lower than in the IUD group (p = 0.004).

Conclusions

At 6-months (DMPA-IM nadir), median estradiol with DMPA-IM was 53% lower and with the LNG implant, 48% lower than with the IUD. The greater reduction in estradiol levels with the DMPA-IM injection compared to the LNG implant and IUD has implications for the relative psychological, sexual as well as physiological side-effects of these contraceptive methods.

ECHO Study Registration

ClinicalTrials.gov, identifier: NCT02550067.

Like Brothers in Arms: How Hormonal Stimuli and Changes in the Metabolism Signaling Cooperate, Leading HPV Infection to Drive the Onset of Cervical Cancer

Despite all precautionary actions and the possibility of using vaccinations to counteract infections caused by human papillomaviruses (HPVs), HPV-related cancers still account for approximately 5% of all carcinomas. Worldwide, many women are still excluded from adequate health care due to their social position and origin. Therefore, immense efforts in research and therapy are still required to counteract the challenges that this disease entails. The special thing about an HPV infection is that it is not only able to trick the immune system in a sophisticated way, but also, through genetic integration into the host genome, to use all the resources available to the host cells to complete the replication cycle of the virus without activating the alarm mechanisms of immune recognition and elimination. The mechanisms utilized by the virus are the metabolic, immune, and hormonal signaling pathways that it manipulates. Since the virus is dependent on replication enzymes of the host cells, it also intervenes in the cell cycle of the differentiating keratinocytes and shifts their terminal differentiation to the uppermost layers of the squamocolumnar transformation zone (TZ) of the cervix. The individual signaling pathways are closely related and equally important not only for the successful replication of the virus but also for the onset of cervical cancer. We will therefore analyze the effects of HPV infection on metabolic signaling, as well as changes in hormonal and immune signaling in the tumor and its microenvironment to understand how each level of signaling interacts to promote tumorigenesis of cervical cancer.