Insights into the vaginal microbiome in a diverse group of women of African, Asian and European ancestries

The microbiome in endometrial cancer: vaginal milieu matters

Endometrial cancer remains one of the most common malignancies in women, and its incidence is particularly increasing in developed countries. Despite the well-known promotive role of excessive exposure to estrogen, many other details of the pathogenesis of endometrial cancer remain unknown. Recent studies have elucidated the emerging role of the resident microbiota in the progression of various diseases, including cancer. Next-generation sequencing demonstrated that the uterine cavity, previously considered sterile, contains a composition-rich microbiota. In this work, we determined the differences in the composition of the intrauterine microbiota between patients with endometrial cancer and its precursor-endometrial hyperplasia.

The Vaginal Microbiota, Human Papillomavirus, and Cervical Dysplasia-A Review

Background and Objectives: The relationship between the vaginal microbiota, human papillomavirus infection (HPV), and cervical precancerous lesions is a critical area of research, as it influences both the progression of HPV-related diseases and potential treatment strategies. New evidence suggests that Lactobacillus crispatus dominance in the microbiota may protect against HPV persistence and speed the elimination of HPV. This study aims to explore the relationship between the vaginal microbiota composition and HPV infection, focusing on the impact of these factors on the development of cervical precancerous lesions. Materials and Methods: A comprehensive literature review was conducted using the PubMed database, focusing on studies that analyzed the association between the vaginal microbiota and HPV infection in the context of cervical dysplasia. This study was primarily based on clinical data on HPV integration in women with low-grade squamous intraepithelial lesions (LSILs), high-grade squamous intraepithelial lesions (HSILs), and cervical cancer. Results: Different types of vaginal microbiota communities (CSTs) have different pathogenic or protective potential. Healthy women predominantly exhibited CST I, with Lactobacillus crispatus as the dominant microorganism. CST IV, associated with increased anaerobic bacteria, was most common in HSIL and cervical cancer patients. Statistical analysis revealed that bacterial vaginosis (BV) was significantly associated with HPV persistence, with studies reporting a 1.8-3.4-fold increased risk (p < 0.05) of persistent HR-HPV infection in BV-positive women. Conclusions: Our literature review suggests that the composition of the vaginal microbiota can modulate the local immune response, the expression of viral oncogenes, and the integrity of the epithelial barrier. Furthermore, certain bacterial genes or metabolic pathways can be associated with a favorable or unfavorable outcome of the disease. Analysis of the vaginal microbiota could serve as an additional risk assessment tool, helping to distinguish between regressing and progressive precancerous conditions.

Temporal dynamics changes in the vaginal fluid microbiome: Implications for body fluid identification and estimating time since deposition (TsD) for forensics

Vaginal fluid analysis plays a crucial role in sexual assault investigations. However, vaginal fluid found at crime scenes is usually subject to a certain duration of exposure. This study thus aimed to assess the influence of different durations of exposure to indoor environment on the vaginal microbiota. The 16S rDNA high-throughput sequencing was used on vaginal fluid samples exposed for short-term (30 days) and long-term (240 days), respectively. Despite potential contamination from environmental microorganisms, particularly following long-term exposure, the results indicated that the vaginal microbiota after exposure was still dominated by Lactobacillus. Both in short-term and long-term exposure involving vaginal fluid, there were clusters with time-dependent characteristics, wherein the relative abundances of associated microbial genera showed a trend of increasing or decreasing over time. In addition, each bodily fluid presented with a unique array of dominant bacterial genera, enabling the differentiation of exposed vaginal fluid samples from other bodily fluids (semen, skin, saliva, feces) with a remarkable 98.75 % accuracy rate. Furthermore, the mean absolute error achieved by the long-term deposition time prediction model was 13.54 days. The mean absolute error for the short-term deposition time prediction model was notably lower, reaching just 2.05 days. In summary, this study investigates the variations in microbial communities within vaginal fluid subjected to different indoor exposure durations and explores their potential in body fluid identification and estimating the time since deposition, thereby contributing valuable supporting evidence in forensic investigations.

Scoping Review of Microbiota Dysbiosis and Risk of Preeclampsia

Limited studies have investigated the role of the microbiota in hypertensive disorders of pregnancy (HDP), particularly preeclampsia, which often results in preterm birth. We evaluated 23 studies that explored the relationship between gut, vaginal, oral, or placental microbiotas and HDP. Scopus, ProQuest Health Research Premium Collection, ProQuest Nursing & Allied Health Database, EBSCO, and Ovid were searched for relevant literature. Majority (18) of studies focused on the gut microbiota, and far fewer examined the oral cavity (3), vagina (3), and placenta (1). One study examined the gut, oral, and vaginal microbiotas. The consensus highlights a potential role for microbiota dysbiosis in preeclampsia and HDP. Especially in the third trimester, preeclampsia is associated with gut dysbiosis-deficient in beneficial species of Akkermansia, Bifidobacterium, and Coprococcus but enriched with pathogenic Campylobacterota and Candidatus Saccharibacteria, with low community α-diversity. Similarly, the preeclamptic vaginal and oral microbiotas are enriched with bacterial vaginosis and periodontal disease-associated species, respectively. The trend is also observed in the placenta, which is colonized by gastrointestinal, respiratory tract, and periodontitis-related pathogens. Consequently, a chronic proinflammatory state that adversely impacts placentation is implicated. These observations however require more mechanistic studies to establish the timing of the preceding immune dysfunction and any causality.

The impact of sex on HIV immunopathogenesis and therapeutic interventions

Globally, the majority of people living with HIV are women or girls, but they have been a minority of participants in clinical trials and observational studies of HIV. Despite this underrepresentation, differences in the pathogenesis of HIV have been observed between men and women, with contributions from both gender- and sex-based factors. These include differences in the risk of HIV acquisition, in viral load set point and immune activation in responses to viremia, and differences in HIV reservoir maintenance. These differences obligate adequate study in both males and females in order to optimize treatments, but also provide a powerful leverage point for delineating the mechanisms of HIV pathogenesis. The shifts in exposure to sex steroid hormones across a lifespan introduce additional complexity, which again can be used to focus on either genetic or hormonal influences as the driver of an outcome. In this Review, we discuss consistent and reproducible differences by sex across the spectrum of HIV, from acquisition through pathogenesis, treatment, and cure, and explore potential mechanisms and gaps in knowledge.

The role and challenges of regulating endometrial microbiome in uterine health and diseases

The uterine environment provides necessary conditions for the existence of endometrial microbiota, which in turn plays an important role in maintaining the homeostasis of the uterine environment. The endometrial microbiome is highly susceptible to external factors such as age, hormones, menstrual, pregnancy, etc. When the microbiota is imbalanced, it will further promote the occurrence of uterine diseases such as endometritis and endometrial cancer. Regulating the microbiome of the endometrium is of positive significance for promoting uterine health. Among them, antibiotics, probiotics, prebiotics, and microbial transplantation may be important pathways for regulating endometrial microbiota in the future. However, there is currently no unified plan for evaluating the endometrial microbiota. In addition, due to the small sample size, it is easy to be contaminated by exogenous bacterial DNA, which poses great challenges for studying the mechanism of microbial community regulating uterine health. Therefore, there are still many areas worth exploring for the future of endometrial microbiome.

Molecular characterization of vaginal microbiota using a new 22-species qRT-PCR test to achieve a relative-abundance and species-based diagnosis of bacterial vaginosis

Background

Numerous bacteria are involved in the etiology of bacterial vaginosis (BV). Yet, current tests only focus on a select few. We therefore designed a new test targeting 22 BV-relevant species.

Methods

Using 946 stored vaginal samples, a new qPCR test that quantitatively identifies 22 bacterial species was designed. The distribution and relative abundance of each species, α- and β-diversities, correlation, and species co-existence were determined per sample. A diagnostic index was modeled from the data, trained, and tested to classify samples into BV-positive, BV-negative, or transitional BV.

Results

The qPCR test identified all 22 targeted species with 95 - 100% sensitivity and specificity within 8 hours (from sample reception). Across most samples, Lactobacillus iners, Lactobacillus crispatus, Lactobacillus jensenii, Gardnerella vaginalis, Fannyhessea (Atopobium) vaginae, Prevotella bivia, and Megasphaera sp. type 1 were relatively abundant. BVAB-1 was more abundant and distributed than BVAB-2 and BVAB-3. No Mycoplasma genitalium was found. The inter-sample similarity was very low, and correlations existed between key species, which were used to model, train, and test a diagnostic index: MDL-BV index. The MDL-BV index, using both species and relative abundance markers, classified samples into three vaginal microbiome states. Testing this index on our samples, 491 were BV-positive, 318 were BV-negative, and 137 were transitional BV. Although important differences in BV status were observed between different age groups, races, and pregnancy status, they were statistically insignificant.

Conclusion

Using a diverse and large number of vaginal samples from different races and age groups, including pregnant women, the new qRT-PCR test and MDL-BV index efficiently diagnosed BV within 8 hours (from sample reception), using 22 BV-associated species.

Vaginal microbiota molecular profiling and diagnostic performance of artificial intelligence-assisted multiplex PCR testing in women with bacterial vaginosis: a single-center experience

Background

Bacterial vaginosis (BV) is a most common microbiological syndrome. The use of molecular methods, such as multiplex real-time PCR (mPCR) and next-generation sequencing, has revolutionized our understanding of microbial communities. Here, we aimed to use a novel multiplex PCR test to evaluate the microbial composition and dominant lactobacilli in non-pregnant women with BV, and combined with machine learning algorithms to determine its diagnostic significance.

Methods

Residual material of 288 samples of vaginal secretions derived from the vagina from healthy women and BV patients that were sent for routine diagnostics was collected and subjected to the mPCR test. Subsequently, Decision tree (DT), random forest (RF), and support vector machine (SVM) hybrid diagnostic models were constructed and validated in a cohort of 99 women that included 74 BV patients and 25 healthy controls, and a separate cohort of 189 women comprising 75 BV patients, 30 intermediate vaginal microbiota subjects and 84 healthy controls, respectively.

Results

The rate or abundance of Lactobacillus crispatus and Lactobacillus jensenii were significantly reduced in BV-affected patients when compared with healthy women, while Lactobacillus iners, Gardnerella vaginalis, Atopobium vaginae, BVAB2, Megasphaera type 2, Prevotella bivia, and Mycoplasma hominis were significantly increased. Then the hybrid diagnostic models were constructed and validated by an independent cohort. The model constructed with support vector machine algorithm achieved excellent prediction performance (Area under curve: 0.969, sensitivity: 90.4%, specificity: 96.1%). Moreover, for subjects with a Nugent score of 4 to 6, the SVM-BV model might be more robust and sensitive than the Nugent scoring method.

Conclusion

The application of this mPCR test can be effectively used in key vaginal microbiota evaluation in women with BV, intermediate vaginal microbiota, and healthy women. In addition, this test may be used as an alternative to the clinical examination and Nugent scoring method in diagnosing BV.

Lactobacillus as probiotics: opportunities and challenges for potential benefits in female reproductive health

The growing interest of the scientific community in the study of probiotics has gathered valuable data about its beneficial effects for multiple clinical conditions. This data also provides evidence for the functions and properties of probiotics and how they contribute to health benefits by influencing normal microbiota. Lactobacillus is an important genus which has long been utilized in the food industry and is also found as normal oral, intestinal and vaginal microbiota. Lactobacillus has shown multiple health benefits but its relative importance as a probiotic is majorly explored for gastrointestinal health. Healthy vaginal microbiota typically harbors Lactobacillus spp. providing several health benefits for female reproductive health, but there is more data required in order to compare the relative benefits with probiotic Lactobacillus added through either natural food sources or with standard probiotics supplements. The present article discusses the current status of knowledge about vaginal Lactobacillus as a probiotic and also compares the potential of probiotics from natural sources and through supplements along with recent approaches in this area.

Gestational diabetes mellitus: genetic factors, epigenetic alterations, and microbial composition

Gestational diabetes mellitus (GDM) is a common metabolic disorder, usually diagnosed during the third trimester of pregnancy that usually disappears after delivery. In GDM, the excess of glucose, fatty acids, and amino acids results in foetuses large for gestational age. Hyperglycaemia and insulin resistance accelerate the metabolism, raising the oxygen demand, and creating chronic hypoxia and inflammation. Women who experienced GDM and their offspring are at risk of developing type-2 diabetes, obesity, and other metabolic or cardiovascular conditions later in life. Genetic factors may predispose the development of GDM; however, they do not account for all GDM cases; lifestyle and diet also play important roles in GDM development by modulating epigenetic signatures and the body's microbial composition; therefore, this is a condition with a complex, multifactorial aetiology. In this context, we revised published reports describing GDM-associated single-nucleotide polymorphisms (SNPs), DNA methylation and microRNA expression in different tissues (such as placenta, umbilical cord, adipose tissue, and peripheral blood), and microbial composition in the gut, oral cavity, and vagina from pregnant women with GDM, as well as the bacterial composition of the offspring. Altogether, these reports indicate that a number of SNPs are associated to GDM phenotypes and may predispose the development of the disease. However, extrinsic factors (lifestyle, nutrition) modulate, through epigenetic mechanisms, the risk of developing the disease, and some association exists between the microbial composition with GDM in an organ-specific manner. Genes, epigenetic signatures, and microbiota could be transferred to the offspring, increasing the possibility of developing chronic degenerative conditions through postnatal life.

Microbiota dynamics, metabolic and immune interactions in the cervicovaginal environment and their role in spontaneous preterm birth

Differences in the cervicovaginal microbiota are associated with spontaneous preterm birth (sPTB), a significant cause of infant morbidity and mortality. Although establishing a direct causal link between cervicovaginal microbiota and sPTB remains challenging, recent advancements in sequencing technologies have facilitated the identification of microbial markers potentially linked to sPTB. Despite variations in findings, a recurring observation suggests that sPTB is associated with a more diverse and less stable vaginal microbiota across pregnancy trimesters. It is hypothesized that sPTB risk is likely to be modified via an intricate host-microbe interactions rather than due to the presence of a single microbial taxon or broad community state. Nonetheless, lactobacilli dominance is generally associated with term outcomes and contributes to a healthy vaginal environment through the production of lactic acid/maintenance of a low pH that excludes other pathogenic microorganisms. Additionally, the innate immunity of the host and metabolic interactions between cervicovaginal microbiota, such as the production of bacteriocins and the use of proteolytic enzymes, exerts a profound influence on microbial populations, activities, and host immune responses. These interplays collectively impact pregnancy outcomes. This review aims to summarize the complexity of cervicovaginal environment and microbiota dynamics, and associations with bacterial vaginosis and sPTB. There is also consideration on how probiotics may mitigate the risk of sPTB and bacterial vaginosis.

The analysis of Lactobacillus spp. distribution in the vaginal microbiota of Polish women with abnormal Pap smear result

Introduction

A healthy vaginal microbiota is represented mainly by Lactobacillus spp. and plays a vital role in maintaining the functional balance in the vaginal environment. Scientists have drawn attention to possible correlations between the vaginal microbiome and gynecological neoplasms. Several recent studies have shown a potential link between the vaginal microbiome and the risk of developing cervical cancer from human papillomavirus (HPV) infection. This study aimed to compare the prevalence and abundance of various lactic acid bacteria species (LABs) in vaginal swabs from healthy controls and patients with abnormal Pap smear results.

Methods

The study included 100 women (79 patients with abnormal cervical Pap smear results and 21 controls) from whom vaginal swabs were collected. Real-time quantitative PCR was used to determine seven lactic acid bacteria (LAB) species and their quantities.

Results

Most patients were colonized by two Lactobacillus species, primarily Lactobacillus gasseri (93%) and L. crispatus (83%). Patient age and place of residence were associated with the diversity of LAB in the vaginal microbiota. The abundance of L. delbrueckii in the vaginal microbiota increased, whereas the abundance of L. gasseri abundance decreased, with patient age. Lactobacillus acidophilus and Limosilactobacillus fermentum were significantly more often detected in patients living in rural versus urban areas. Statistical analysis did not show any significant differences in LAB between groups of patients with various changes on smear tests.

Discussion

The degree of dysplastic changes in the endothelium or the presence of a group of atypical cervical stratified epithelial cells was not associated with significant changes in the studied vaginal bacteria.