Associations of Cervicovaginal Lactobacilli With High-Risk Human Papillomavirus Infection, Cervical Intraepithelial Neoplasia, and Cancer: A Systematic Review and Meta-Analysis

Risk factors for the development of cervical cancer: analysis of the evidence

Introduction

Cervical cancer (CC) is the fourth most prevalent female cancer globally. Understanding its epidemiology is crucial for devising practical strategies suited to geographic and social contexts to attain the global eradication of CC. Hence, this study examined the latest evidence of risk factors contributing to CC development.

Methods

An independent literature search was conducted on PubMed using MESH terms. The primary sources were meta-analyses published from 2010 to 2023, which detail updated evidence on risk factors associated with CC. Additionally, the quality of the evidence was evaluated using the GRADE system and recommendations were made accordingly.

Results

The main risk factors related to the cause of CC include co-infections with other sexually transmitted infections, genetic markers, cervicovaginal microbiota, nutritional factors, comorbidities that affect the immune response, smoking, and the use of hormonal contraceptives with a quality evidence based on the GRADE scale moderate.

Conclusions

Since the necessary cause for CC is persistent cervicovaginal HPV, all the risk factors implicated in the causality of CC act as non-independent cofactors that increase the risk of CC. Thus, changes in public policies aimed at addressing these risk factors are highly recommended and can substantially decrease the risk of CC.

Vaginal Microbiota and HPV in Latin America: A Narrative Review

With the expansion of human microbiome studies in the last 15 years, we have realized the immense implications of microbes in human health. The human holobiont is now accepted, given the commensal relationships with bacteria, fungi, parasites, viruses, and human cells. The cervicovaginal microbiota is a specific case within the human microbiome where diversity is lower to maintain a chemical barrier of protection against infections. This narrative review focuses on the vaginal microbiome. It summarizes key findings on how native bacteria protect women from disease or predispose them to damaging inflammatory processes with an emphasis on the role of HPV infections in Latin America, one of the world's regions with the highest cervical cancer prevalence.

Influence of connatural factors in shaping vaginal microflora and ensuring its health

Vaginal canal (VC) is exposed to the external environment affected by habitual factors like hygiene and sexual behaviour as well as physiological factors like puberty, menstrual cycle, pregnancy, child birth and menopause. Healthy VC harbours beneficial microflora supported by vaginal epithelium and cervical fluid. Connatural antimicrobial peptide (AMPs) of female reproductive tract (FRT) conjunctly with these beneficial microbes provide protection from a large number of infectious diseases. Such infections may either be caused by native microbes of the VC or transitory microbes like bacteria or virus which are not a part of VC microflora. This review highlight's the role of hormones, enzymes, innate immunological factors, epithelial cells and vaginal mucus that support beneficial microbes over infectious ones thus, helping to maintain homeostasis in VC and further protect the FRT. We also discuss the prospective use of vaginal probiotics and AMPs against pathogens which can serve as a potential cure for vaginal infections.

Human papillomavirus and cervical cancer in the microbial world: exploring the vaginal microecology

The vaginal microbiota plays a crucial role in female reproductive health and is considered a biomarker for predicting disease outcomes and personalized testing. However, its relationship with human papillomavirus (HPV) infection and cervical cancer is not yet clear. Therefore, this article provides a review of the association between the vaginal microbiota, HPV infection, and cervical cancer. We discuss the composition of the vaginal microbiota, its dysbiosis, and its relationship with HPV infection, as well as potential mechanisms in the development of cervical cancer. In addition, we assess the feasibility of treatment strategies such as probiotics and vaginal microbiota transplantation to modulate the vaginal microbiota for the prevention and treatment of diseases related to HPV infection and cervical cancer. In the future, extensive replication studies are still needed to gain a deeper understanding of the complex relationship between the vaginal microbiota, HPV infection, and cervical cancer, and to clarify the role of the vaginal microbiota as a potential biomarker for predicting disease outcomes, thus providing a theoretical basis for personalized testing.

Alterations in gut and genital microbiota associated with gynecological diseases: a systematic review and meta-analysis

BACKGROUND

Increasing number of studies have demonstrated certain patterns of microbial changes in gynecological diseases; however, the interaction between them remains unclear. To evaluate the consistency or specificity across multiple studies on different gynecological diseases and microbial alterations at different sites of the body (gut and genital tract), we conducted a systematic review and meta-analysis.

METHODS

We searched PubMed, Embase, Web of Science, and Cochrane Library up to December 5, 2022(PROSPERO: CRD42023400205). Eligible studies focused on gynecological diseases in adult women, applied next-generation sequencing on microbiome, and reported outcomes including alpha or beta diversity or relative abundance. The random-effects model on standardized mean difference (SMD) was conducted using the inverse-variance method for alpha diversity indices.

RESULTS

Of 3327 unique articles, 87 eligible studies were included. Significant decreases were found in gut microbiome of patients versus controls (observed species SMD=-0.35; 95%CI, -0.62 to -0.09; Shannon index SMD=-0.23; 95%CI, -0.40 to -0.06), whereas significant increases were observed in vaginal microbiome (Chao1 SMD = 1.15; 95%CI, 0.74 to 1.56; Shannon index SMD = 0.51; 95%CI, 0.16 to 0.86). Most studies of different diagnostic categories showed no significant differences in beta diversity. Disease specificity was observed, but almost all the changes were only replicated in three studies, except for the increased Aerococcus in bacterial vaginosis (BV). Patients with major gynecological diseases shared the enrichment of Prevotella and depletion of Lactobacillus, and an overlap in microbes was implied between BV, cervical intraepithelial neoplasia, and cervical cancer.

CONCLUSIONS

These findings demonstrated an association between alterations in gut and genital microbiota and gynecological diseases. The most observed results were shared alterations across diseases rather than disease-specific alterations. Therefore, further investigation is required to identify specific biomarkers for diagnosis and treatment in the future.

A Decrease in Lactobacilli in the Vaginal Microbiota Is Independently Associated With HPV Persistence in Women With High-Risk HPV Infection

Background Vaginal dysbiosis, an imbalance between species, can initiate some local changes in immune and metabolic signaling causing chronic inflammation. The mechanism of the clearance or progression of the HPV infection has not been uncovered yet. We hypothesized that vaginal dysbiosis may contribute to the persistence of the cervical HPV infection. Therefore we aimed to determine the association of lactobacillus dominancy index with cervical HR-HPV persistence. Methods A total of 100 women who were followed up because of high-risk HPV infection were defined as the target study group. The patients were evaluated in two groups; HPV positive (group with HPV persistence, n=43) and HPV negative (group with HPV clearance, n=57). Cervicovaginal swab samples and blood samples were evaluated for Nugent score, lactobacillus dominance, and white blood cell count. Statistical tests were performed by the IBM Statistical Product and Service Solutions (version 22, IBM SPSS Statistics for Windows, Armonk, NY) program. The continuous variables were presented using the mean±standard deviation (SD), and the categorical variables were presented as the number of cases and their percentage. A p value less than 0.05 (<0.05) was set as statistically significant. Results HPV persistence was observed in 43 (43%) patients. Univariate analysis revealed that age, menopausal status, and lactobacillus reduction were associated with HPV persistence (p<0.05). The median value of the Nugent score was similar among groups. After logistic regression analysis, lactobacillus reduction continued to be associated with HPV persistence, independent of age and menopause (OR: 2.668, 96% CI: 1.069-6.662, p<0.05) Conclusions A decrease in lactobacilli in the cervicovaginal microbiota is associated with the persistence of HPV, regardless of age and menopausal status in this study.

Intravaginal estrogen management in postmenopausal patients with vaginal squamous intraepithelial lesions along with CO2 laser ablation: A retrospective study

This study aims to investigate the influence of topical estrogen management in postmenopausal patients who had undergone CO2 laser ablation for vaginal squamous intraepithelial lesions (SILs). The clinical data of 211 postmenopausal women with vaginal SILs were reviewed. Patients were divided into two groups by 2-month different management: Group 1 (intervention group): patients were treated with estrogen cream 0.5 g every other day and Group 2 (control group): no topical agent was used for the treatment of patients. In low-grade squamous intraepithelial lesions (LSILs), the response rates for patients in the intervention group and the control group were 49.1% (27/55) and 54.2% (16/48), respectively; human papillomavirus (HPV) status turned negative in 12 (12/38, 31.6%) patients of the intervention group and in 15 (15/35, 42.9%) patients of the control group. In high-grade squamous intraepithelial lesions (HSILs), the response rates for patients in the intervention group and the control group were 72.4% (42/58) and 78.0% (39/50), respectively, nearly 1.5 times higher than those of the LSIL patients; 22 (22/54, 40.7%) patients of the intervention groups and 12 (12/46, 26.1%) patients of the control group cleared the HPV infection. In postmenopausal patients, local use of estrogen cream improves the recognition of lesions and is conducive to precision medicine.

Dysbiotic Co-Factors in Cervical Cancer. How the Microbiome Influences the Development of Cervical Intraepithelial Neoplasia (CIN)

Human papillomavirus (HPV) infection is a necessary but not sufficient condition for the development of cervical cancer. The dysbiotic shift in the cervicovaginal microbiome appears to be a major co-factor in carcinogenesis. New analytical methods, such as next-generation sequencing (NGS), can be used to detect all of the vaginal microorganisms present and therefore identify individual therapeutic options. The relationship of bacterial vaginosis and carcinogenesis, as well as possible indications for the use of microbiome analysis, will be discussed.

Risk factors for human papillomavirus infection, cervical intraepithelial neoplasia and cervical cancer: an umbrella review and follow-up Mendelian randomisation studies

BACKGROUND

Persistent infection by oncogenic human papillomavirus (HPV) is necessary although not sufficient for development of cervical cancer. Behavioural, environmental, or comorbid exposures may promote or protect against malignant transformation. Randomised evidence is limited and the validity of observational studies describing these associations remains unclear.

METHODS

In this umbrella review, we searched electronic databases to identify meta-analyses of observational studies that evaluated risk or protective factors and the incidence of HPV infection, cervical intra-epithelial neoplasia (CIN), cervical cancer incidence and mortality. Following re-analysis, evidence was classified and graded based on a pre-defined set of statistical criteria. Quality was assessed with AMSTAR-2. For all associations graded as weak evidence or above, with available genetic instruments, we also performed Mendelian randomisation to examine the potential causal effect of modifiable exposures with risk of cervical cancer. The protocol for this study was registered on PROSPERO (CRD42020189995).

RESULTS

We included 171 meta-analyses of different exposure contrasts from 50 studies. Systemic immunosuppression including HIV infection (RR = 2.20 (95% CI = 1.89-2.54)) and immunosuppressive medications for inflammatory bowel disease (RR = 1.33 (95% CI = 1.27-1.39)), as well as an altered vaginal microbiome (RR = 1.59 (95% CI = 1.40-1.81)), were supported by strong and highly suggestive evidence for an association with HPV persistence, CIN or cervical cancer. Smoking, number of sexual partners and young age at first pregnancy were supported by highly suggestive evidence and confirmed by Mendelian randomisation.

CONCLUSIONS

Our main analysis supported the association of systemic (HIV infection, immunosuppressive medications) and local immunosuppression (altered vaginal microbiota) with increased risk for worse HPV and cervical disease outcomes. Mendelian randomisation confirmed the link for genetically predicted lifetime smoking index, and young age at first pregnancy with cervical cancer, highlighting also that observational evidence can hide different inherent biases. This evidence strengthens the need for more frequent HPV screening in people with immunosuppression, further investigation of the vaginal microbiome and access to sexual health services.

Successful Preventive Treatment of Oncogenic Transforming HPV Infections in Low-Grade Cytology (ASC-US/LSIL) Patients with an Adsorptive and Antioxidant Vaginal Gel

OBJECTIVE

This study aimed to investigate the preventive effect of a vaginal gel on p16/Ki-67-positive abnormal cytological cervical findings (ASC-US, LSIL) and hr-HPV in women.

METHODS

The study included 134 women with p16/Ki-67-positive ASC-US or LSIL. Participants were selected from a randomized controlled trial that focused on women with histological diagnoses of p16-positive CIN1 lesions or CIN2. In the treatment group (TG), 57 patients applied the vaginal gel daily for three months, while 77 patients in the "watchful wait" control group (CG) received no treatment. The study's endpoints were cytological development, p16/Ki-67 and hr-HPV clearances.

RESULTS

At three months, cytopathological results improved in 74% (42/57) of patients in the TG, compared with 18% (14/77) in the CG. Progression occurred in 7% (4/57) of TG patients compared with 18% (14/77) of CG patients. The p16/Ki-67 status changed statistically significantly in favor of the TG (p < 0.001), with 83% (47/57) becoming negative, compared with 18% (14/77) in the CG. The prevalence of hr-HPV decreased significantly in the TG by 51%, and by 9% in the CG (p < 0.001).

CONCLUSIONS

Topical application of the gel resulted in statistically significant clearance of hr-HPV and p16/Ki-67 concomitant with amelioration of cytological findings, thus providing effective prevention and protection against oncogenic development.

TRIAL REGISTRATION

ISRCTN11009040, on 10 December 2019.

Bacterial Species from Vaginal Microbiota Differently Affect the Production of the E6 and E7 Oncoproteins and of p53 and p-Rb Oncosuppressors in HPV16-Infected Cells

Vaginal dysbiosis is characterized by a decrease in the relative abundance of Lactobacillus species in favor of other species. This condition facilitates infections by sexually transmitted pathogens including high risk (HR)-human papilloma viruses (HPVs) involved in the development of cervical cancer. Some vaginal dysbiosis bacteria contribute to the neoplastic progression by inducing chronic inflammation and directly activating molecular pathways involved in carcinogenesis. In this study, SiHa cells, an HPV-16-transformed epithelial cell line, were exposed to different representative vaginal microbial communities. The expression of the HPV oncogenes E6 and E7 and the production of relative oncoproteins was evaluated. The results showed that Lactobacillus crispatus and Lactobacillus gasseri modulated the basal expression of the E6 and E7 genes of SiHa cells and the production of the E6 and E7 oncoproteins. Vaginal dysbiosis bacteria had contrasting effects on E6/E7 gene expression and protein production. The expression of the E6 and E7 genes and the production of the relative oncoproteins was increased by strains of Gardnerella vaginalis and, to a lesser extent, by Megasphaera micronuciformis. In contrast, Prevotella bivia decreased the expression of oncogenes and the production of the E7 protein. A decreased amount of p53 and pRb was found in the cultures of SiHa cells with M. micronuciformis, and accordingly, in the same cultures, a higher percentage of cells progressed to the S-phase of the cell cycle compared to the untreated or Lactobacillus-stimulated cultures. These data confirm that L. crispatus represents the most protective component of the vaginal microbiota against neoplastic progression of HR-HPV infected cells, while M. micronuciformis and, to a lesser extent, G. vaginalis may directly interfere in the oncogenic process, inducing or maintaining the production of viral oncoproteins.

Non-Genetic Factors and Risk of Cervical Cancer: An Umbrella Review of Systematic Reviews and Meta-Analyses of Observational Studies

Objectives: The association between non-genetic risk factors and cervical cancer (CC) remains controversial and unclear. This umbrella review was conducted to evaluate and synthesize previously published systematic reviews and meta-analyses related to non-genetic factors and CC risk.

Methods: We searched PubMed, Web of Science, and EMBASE to identify studies investigating the association between extragenetic factors and CC risk. For each article, we calculated the summary effect size and the 95% confidence interval. Specific criteria were used to classify the association into four levels: strong, highly suggestive, suggestive, or weak.

Results: A total of 18 meta-analyses of different risk factors for CC were examined; these studies covered risk factors related to diet, lifestyle, reproduction, disease, viral infection, microorganisms, and parasites. Oral contraceptive use and Chlamydia trachomatis infection were shown to increase CC risk, and this was supported by strong evidence. Additionally, there were four risk factors supported by highly suggestive evidence and six risk factors supported by suggestive evidence.

Conclusion: In conclusion, there is a strong association between oral contraceptive use, Chlamydia trachomatis infection, and increased CC risk.

Immune-Onco-Microbiome: A New Revolution for Gynecological Cancers

Despite significant advances in understanding the pathogenetic mechanisms underlying gynaecological cancers, these cancers still remain widespread. Recent research points to a possible link between microbiota and cancer, and the most recent attention is focusing on the relationship between the microbiome, the immune system, and cancer. The microbiome diversity can affect carcinogenesis and the patient’s immune response, modulating the inflammatory cascade and the severity of adverse events. In this review, we presented the recent evidence regarding microbiome alterations in patients with gynaecological tumours to understand if the link that exists between microbiome, immunity, and cancer can guide the prophylactic, diagnostic, and therapeutic management of gynaecological cancers.

Risk Factors of Preterm Birth in Women After Local Treatment of Cervical Intraepithelial Neoplasia – a Retrospective Cohort Study

Purpose A previous cervical intraepithelial neoplasia is associated with an increased obstetrical risk. It was the aim of the study to identify risk factors of preterm birth in patients with cervical intraepithelial neoplasia in dependence of the treatment modality (excisional vs. ablative).

Methods Women with treated cervical intraepithelial neoplasia and subsequent pregnancy (n = 155) were included in this retrospective study. Methods of treatment were either conization by large loop excision of the transformation zone (LLETZ) or ablative laser vaporization.

Results Of the total population 60.6% (n = 94) had a conization and 39.4% (n = 61) a laser vaporization alone. The frequency of preterm birth < 37 weeks was 9.7% (n = 15) without differences between conization and laser (11.7 vs. 6.7%, p = 0.407) with an odds ratio (OR) of 1.9 (95% confidence interval [CI] 0.6–6.2). Preterm birth < 34 weeks was found in 2.6% (n = 4), of which all had a conization (4.3 vs. 0%, p = 0.157). Risk factors for preterm birth were repeated cervical intervention (OR 4.7 [95% CI 1.5–14.3]), especially a combination of conization and laser ablation (OR 14.9 [95% CI 4.0–55.6]), age at intervention < 30 years (OR 6.0 [95% CI 1.3–27.4]), a history of preterm birth (OR 4.7 [95% CI 1.3–17.6]) and age at delivery < 28 years (OR 4.7 [95% CI 1.5–14.3]).

Conclusion The large loop excision of the transformation zone as a modern, less invasive ablative treatment did not obviously increase the risk of preterm birth compared to laser vaporization. The most important risk factor for preterm delivery was the need of a repeated intervention, especially at younger age. We assume that the persistence or recurrence of the cervical intraepithelial neoplasia following a high-risk human papillomavirus infection is mainly responsible for the observed effect.

The association of cervicovaginal Langerhans cells with clearance of human papillomavirus

Human papillomavirus (HPV) clearance is important in eliminating cervical cancer which contributes to high morbidity and mortality in women. Nevertheless, it remains largely unknown about key players in clearing pre-existing HPV infections. HPV antigens can be detected by the most important cervical antigen-presenting cells (Langerhans cells, LCs), of which the activities can be affected by cervicovaginal microbiota. In this review, we first introduce persistent HPV infections and then describe HPV-suppressed LCs activities, including but not limited to antigen uptake and presentation. Given specific transcriptional profiling of LCs in cervical epithelium, we also discuss the impact of cervicovaginal microbiota on LCs activation as well as the promise of exploring key microbial players in activating LCs and HPV-specific cellular immunity.

Cervicovaginal microbiota significantly changed for HPV-positive women with high-grade squamous intraepithelial lesion

Lower female genital tract is colonized by a variety of microbes (cervicovaginal microbiota, CVM) which associate with the risk of genital infection. This study characterized CVM for 149 Chinese women with different status of human papillomavirus (HPV) infection and squamous intraepithelial lesion (SIL): no HPV infection (HPV-), HPV infection without significant SIL (HPV+NoSIL), HPV infection with low-grade SIL (HPV+LSIL) and HPV infection with high-grade SIL (HPV+HSIL). Analysis results showed CVM has dramatically changed in HPV+HSIL group when compared to HPV+LSIL group, but it exhibited no significant differences between HPV- and HPV+NoSIL groups as well as between HPV+NoSIL and HPV+LSIL groups. In consistence, random forest analysis found more notable differences in HPV+HSIL vs HPV+LSIL comparison than in other comparisons. In addition, depletion of Lactobacillus in CVM was more to be frequently identified in SIL-positive women as compared to SIL-negative individuals. Our findings suggested that significant CVM differences occurred when SIL developed to HSIL which was caused by persistent HPV infection.

The role of probiotics in vaginal health

Probiotics have been widely used in the treatment of intestinal diseases, but the effect of probiotics on female reproductive tract health is still controversial. Lactobacillus is the most abundant microorganism in the vagina, which is related to the vaginal mucosal barrier. Lactobacillus adheres to the vaginal epithelium and can competitively antagonize the colonization of pathogens. The factors produced by Lactobacillus, such as bacteriocin and hydrogen peroxide (H₂O₂), can inhibit the growth of pathogenic microorganisms and maintain the low pH environment of the vagina. Probiotics play an important role in maintaining the stability of vaginal microenvironment, improving immune defense and blocking the progression of cervical cancer. We review the research progress of probiotics represented by Lactobacillus in gynecological diseases such as human papilloma virus (HPV) infection, bacterial vaginosis (BV) and Genitourinary Syndrome of Menopause (GSM), so as to provide basis for further exerting the role of probiotics in women’s health.

Changes in the cervicovaginal microbiota composition of HPV16-infected patients after clinical treatment

BACKGROUND

High-risk human papillomavirus (hrHPV) infection is a key factor that alters cervicovaginal microbiota patterns and causes cervical intraepithelial neoplasias (CINs) or even cervical cancer. Although local excisional treatment can clear hrHPV infection and restore the cervicovaginal microbiota, it is unclear which cervicovaginal microbiota represents recovery. Our objective was to describe the cervicovaginal microbiota before and after treatments and to assess the association between the microbiota and HPV persistence.

RESULTS

A cohort of 91 participants was classified into four groups (healthy control women and HPV16-infected women with CIN I, CIN II/III, and squamous cell carcinoma [SCC]). Endocervical swabs were collected 3 months prior to treatment and at 3 months post-treatment for bacterial 16S rRNA gene pyrosequencing and for HPV DNA testing. There was an increase in the number of Lactobacillus bacterial species present after the clinical treatments, and the community state type (CST) profiles were shifted from dysbiotic CSTs II and IV to Lactobacillus-dominated CSTs I and III. Specifically, the composition of Geobacter and Prevotella before treatment and Lactobacillus secaliphilus after treatment might have been related to CIN I, the composition of Burkholderia before treatment and Lactobacillus iners after treatment might have been related to CIN II/III, and the composition of Atopobium and Aerococcus before treatment and Bacilli after treatment might have been related to SCC. Further functional predictions revealed that the composition differences were linked to infectious disease- and cancer-related genes.

CONCLUSION

Our study provides an illustration of the changes in CSTs and the cervicovaginal microbiota before and after HPV16 clearance in each disease state.

Lactobacillus crispatus DSM25988 as novel bioactive agent to co-aggregate Streptococcus pyogenes and to exclude it by binding to human cells

Streptococcus pyogenes, a group A streptococcus, is the major bacterial pathogen responsible for acute bacterial infection of the human oropharynx and the causative agent of scarlet fever. Estimates of the global burden of S. pyogenes related diseases revealed 616 million cases of pharyngitis, and at least 517,000 deaths due to severe invasive diseases and sequelae. Here we describe Lactobacillus crispatus DSM25988 that was identified among hundreds of Lactobacillus strains (referring to all organisms that were classified as Lactobacillaceae until 2020) showing ability to prevent adhesion of S. pyogenes to Detroit 562 cells, and to exhibit a masking and co-aggregating effect on S. pyogenes in vitro. L. crispatus DSM25988 also inhibits invasion of cultured human epithelial pharyngeal cells by S. pyogenes. Competitive binding to fibronectin might be involved in the inhibition process. Antiviral activity of the L. crispatus DSM25988 cells were identified in an in vitro cell model demonstrating that L. crispatus effectively excludes viruses from epithelial cells using SARS-CoV2 proteins as a model. This finding points to the potential of DSM25988 to protect cells from virus infection. Biological activity is retained in heat treated cells. The heat-treated Lactobacillus strain was further developed into functional throat lozenges, wherein its biological activity is stably maintained in the formulation. Lozenges containing L. crispatus DSM25988 underwent testing in an uncontrolled, prospective user study in 44 subjects with symptoms of sore throat for a period of up to 14 days. The study data shows promising safety and efficacy of the medical device when used against symptoms of sore throat like scratchy feeling, hoarse voice and swallowing pain.

Multi-omics data integration reveals metabolome as the top predictor of the cervicovaginal microenvironment

Emerging evidence suggests that host-microbe interaction in the cervicovaginal microenvironment contributes to cervical carcinogenesis, yet dissecting these complex interactions is challenging. Herein, we performed an integrated analysis of multiple "omics" datasets to develop predictive models of the cervicovaginal microenvironment and identify characteristic features of vaginal microbiome, genital inflammation and disease status. Microbiomes, vaginal pH, immunoproteomes and metabolomes were measured in cervicovaginal specimens collected from a cohort (n = 72) of Arizonan women with or without cervical neoplasm. Multi-omics integration methods, including neural networks (mmvec) and Random Forest supervised learning, were utilized to explore potential interactions and develop predictive models. Our integrated analyses revealed that immune and cancer biomarker concentrations were reliably predicted by Random Forest regressors trained on microbial and metabolic features, suggesting close correspondence between the vaginal microbiome, metabolome, and genital inflammation involved in cervical carcinogenesis. Furthermore, we show that features of the microbiome and host microenvironment, including metabolites, microbial taxa, and immune biomarkers are predictive of genital inflammation status, but only weakly to moderately predictive of cervical neoplastic disease status. Different feature classes were important for prediction of different phenotypes. Lipids (e.g. sphingolipids and long-chain unsaturated fatty acids) were strong predictors of genital inflammation, whereas predictions of vaginal microbiota and vaginal pH relied mostly on alterations in amino acid metabolism. Finally, we identified key immune biomarkers associated with the vaginal microbiota composition and vaginal pH (MIF), as well as genital inflammation (IL-6, IL-10, MIP-1α).

The Vaginal Microbiome: IV. The Role of Vaginal Microbiome in Reproduction and in Gynecologic Cancers

OBJECTIVE

This series of articles, titled The Vaginal Microbiome (VMB), written on behalf of the International Society for the Study of Vulvovaginal Disease, aims to summarize the recent findings and understanding of the vaginal bacterial microbiota, mainly regarding areas relevant to clinicians specializing in vulvovaginal disorders.

MATERIALS AND METHODS

A search of PubMed database was performed, using the search terms "vaginal microbiome" with "reproduction," "infertility," "fertility," "miscarriages," "pregnancy" "cervical cancer," "endometrial cancer," and "ovarian cancer." Full article texts were reviewed. Reference lists were screened for additional articles.

RESULTS

The fourth article of this series focuses on 2 distinct areas: the role of VMB in various aspects of human reproduction and, in sharp contrast, the association between the VMB and gynecologic malignancies. Several of the negative pregnancy outcomes have been associated with an altered VMB. Dysbiosis is remarkably linked with poor pregnancy outcomes from preconception to delivery. The associations between the microbiome and gynecologic cancers are described.

CONCLUSIONS

The development of the microbiome research, enabled by molecular-based techniques, has dramatically increased the detection of microorganisms and the understanding of bacterial communities that are relevant to maternal-fetal medicine in health and disease, as well as in gynecological malignancies. Proving causation in cancer is difficult because of the complex interactive nature of potential causative factors. Certain elements of the microbiota have been shown to provoke inflammatory reactions, whereas others produce anti-inflammatory reactions; this balance might be impaired with a change in microbial variety.

The Human Vulvar Microbiome: A Systematic Review

The link between cancer and the microbiome is a fast-moving field in research. There is little knowledge on the microbiome in ((pre)malignant) conditions of the vulvar skin. This systematic review aims to provide an overview of the literature regarding the microbiome composition of the healthy vulvar skin and in (pre)malignant vulvar disease. This study was performed according to the PRISMA guidelines. A comprehensive, electronic search strategy was used to identify original research articles (updated September 2021). The inclusion criteria were articles using culture-independent methods for microbiome profiling of the vulvar region. Ten articles were included. The bacterial composition of the vulva consists of several genera including Lactobacillus, Corynebacterium, Staphylococcus and Prevotella, suggesting that the vulvar microbiome composition shows similarities with the corresponding vaginal milieu. However, the vulvar microbiome generally displayed higher diversity with commensals of cutaneous and fecal origin. This is the first systematic review that investigates the relationship between microbiome and vulvar (pre)malignant disease. There are limited data and the level of evidence is low with limitations in study size, population diversity and methodology. Nevertheless, the vulvar microbiome represents a promising field for exploring potential links for disease etiology and targets for therapy.

Vaginal microbiome components as correlates of cervical human papillomavirus infection

BACKGROUND

The interplay between vaginal microbiome and human papillomavirus (HPV) remains unclear, partly due to heterogeneity of the microbiota.

METHODS

We used data from 546 women enrolled in a cross-sectional study conducted in five Brazilian regions. We genotyped vaginal samples for HPV and sequenced V3-V4 region of 16S rRNA gene for vaginal microbiome analysis. We used stepwise logistic regression to construct two linear scores to predict high-risk HPV (hrHPV) positivity: one based exclusively on presence of individual bacterial taxa (microbiome-based [MB] score) and the other exclusively on participants' sociodemographic, behavioral and clinical (SBC) characteristics. The MB score combined coefficients of 30 (out of 116) species. The SBC score retained six out of 25 candidate variables. We constructed receiver operating characteristic curves for the scores as hrHPV correlates and compared areas under the curve (AUC) and 95% confidence intervals (CI).

RESULTS

Overall, prevalence of hrHPV was 15.8%, and 26.2% had a Lactobacillus-depleted microbiome. The AUCs were 0.8022 (CI:0.7517-0.8527) for MB score and 0.7027 (CI:0.6419-0.7636) for SBC score (P=0.0163).

CONCLUSIONS

The proposed MB score is strongly correlated with hrHPV positivity - exceeding the predictive value of behavioral variables - suggesting its potential as an indicator of infection and possible value for clinical risk stratification.

Cervicovaginal Microbiome Factors in Clearance of Human Papillomavirus Infection

Persistent high-risk human papillomavirus (hrHPV) infection is the highest risk to cervical cancer which is the fourth most common cancer in women worldwide. A growing body of literatures demonstrate the role of cervicovaginal microbiome (CVM) in hrHPV susceptibility and clearance, suggesting the promise of CVM-targeted interventions in protecting against or eliminating HPV infection. Nevertheless, the CVM-HPV-host interactions are largely unknown. In this review, we summarize imbalanced CVM in HPV-positive women, with or without cervical diseases, and the progress of exploring CVM resources in HPV clearance. In addition, microbe- and host-microbe interactions in HPV infection and elimination are reviewed to understand the role of CVM in remission of HPV infection. Lastly, the feasibility of CVM-modulated and -derived products in promoting HPV clearance is discussed. Information in this article will provide valuable reference for researchers interested in cervical cancer prevention and therapy.

A Framework for Cervical Cancer Elimination in Low-and-Middle-Income Countries: A Scoping Review and Roadmap for Interventions and Research Priorities

The World Health Organization announced an ambitious call for cervical cancer elimination worldwide. With existing prevention and treatment modalities, cervical cancer elimination is now within reach for high-income countries. Despite limited financing and capacity constraints in low-and-middle-income countries (LMICs), prevention and control efforts can be supported through integrated services and new technologies. We conducted this scoping review to outline a roadmap toward cervical cancer elimination in LMICs and highlight evidence-based interventions and research priorities to accelerate cervical cancer elimination. We reviewed and synthesized literature from 2010 to 2020 on primary and secondary cervical cancer prevention strategies. In addition, we conducted expert interviews with gynecologic and infectious disease providers, researchers, and LMIC health officials. Using these data, we developed a logic model to summarize the current state of science and identified evidence gaps and priority research questions for each prevention strategy. The logic model for cervical cancer elimination maps the needs for improved collaboration between policy makers, production and supply, healthcare systems, providers, health workers, and communities. The model articulates responsibilities for stakeholders and visualizes processes to increase access to and coverage of prevention methods. We discuss the challenges of contextual factors and highlight innovation needs. Effective prevention methods include HPV vaccination, screening using visual inspection and HPV testing, and thermocoagulation. However, vaccine coverage remains low in LMICs. New strategies, including single-dose vaccination could enhance impact. Loss to follow-up and treatment delays could be addressed by improved same-day screen-and-treat technologies. We provide a practical framework to guide cervical cancer elimination in LMICs. The scoping review highlights existing and innovative strategies, unmet needs, and collaborations required to achieve elimination across implementation contexts.

The interplay between the vaginal microbiome and innate immunity in the focus of predictive, preventive, and personalized medical approach to combat HPV-induced cervical cancer

HPVs representing the most common sexually transmitted disease are a group of carcinogenic viruses with different oncogenic potential. The immune system and the vaginal microbiome represent the modifiable and important risk factors in HPV-induced carcinogenesis. HPV infection significantly increases vaginal microbiome diversity, leading to gradual increases in the abundance of anaerobic bacteria and consequently the severity of cervical dysplasia. Delineation of the exact composition of the vaginal microbiome and immune environment before HPV acquisition, during persistent/progressive infections and after clearance, provides insights into the complex mechanisms of cervical carcinogenesis. It gives hints regarding the prediction of malignant potential. Relative high HPV prevalence in the general population is a challenge for modern and personalized diagnostics and therapeutic guidelines. Identifying the dominant microbial biomarkers of high-grade and low-grade dysplasia could help us to triage the patients with marked chances of lesion regression or progression. Any unnecessary surgical treatment of cervical dysplasia could negatively affect obstetrical outcomes and sexual life. Therefore, understanding the effect and role of microbiome-based therapies is a breaking point in the conservative management of HPV-associated precanceroses. The detailed evaluation of HPV capabilities to evade immune mechanisms from various biofluids (vaginal swabs, cervicovaginal lavage/secretions, or blood) could promote the identification of new immunological targets for novel individualized diagnostics and therapy. Qualitative and quantitative assessment of local immune and microbial environment and associated risk factors constitutes the critical background for preventive, predictive, and personalized medicine that is essential for improving state-of-the-art medical care in patients with cervical precanceroses and cervical cancer. The review article focuses on the influence and potential diagnostic and therapeutic applications of the local innate immune system and the microbial markers in HPV-related cancers in the context of 3P medicine.

An Adsorptive and Antioxidant Vaginal Gel Clears High-Risk HPV- and p16/Ki-67-Associated Abnormal Cytological Cervical Findings: A post-hoc Subgroup Analysis of a Prospective Randomized Controlled Trial on CIN2 and p16 Positive CIN1

Objective: To analyze the course of p16/Ki-67-positive abnormal cytological cervical findings and high risk (hr)-HPV- and p16/Ki-67-clearances in women treated with a vaginal gel.

Methods: 172 women with a histological diagnosis of CIN2 or p16-positive CIN1 lesions were selected based on a positive cytological p16/Ki-67 test. For 3 months, 75 patients in the active arm (AA) daily administered 5 ml of a vaginal gel. Ninety seven patients in the control arm (CA) underwent no treatment (“watchful waiting”). Endpoints were cytological evolution, p16/Ki-67- and hr-HPV-clearances.

Results: At 3 months, cytological regression was observed in 76% (57/75) of patients in the AA compared with 25% (24/97) in the CA. Progression occurred in 5% (4/75) of the AA compared with 15% (15/97) of the CA. The p16/Ki-67 status change was statistically significantly (p < 0.001) in favor of the AA: 77% (58/75) became negative compared to 21% (20/97) in the CA. hr-HPV prevalence decreased significantly (p < 0.001) in the AA from 87 to 44%, while increasing in the CA from 78 to 84%. Cytological regression and p16/Ki-67 changes persisted in the AA at 6 months.

Conclusions: The vaginal gel significantly cleared hr-HPV and p16/Ki-67 and was associated with improved cytological findings, thereby potentially offering an effective option against oncogenic risk.

Clinical Trial Registration: Identifier: [ISRCTN11009040].

Oral administration of Lactobacillus crispatus M247 to papillomavirus-infected women: results of a preliminary, uncontrolled, open trial

BACKGROUND

Vaginal microbiotas can be clustered into five different possible categories (CST I to V), according to their bacterial dominance. In CST I, the dominance of Lactobacillus crispatus seems to correlate with better vaginal health and with a lower incidence of sine causa infertility, preterm delivery, bacterial vaginosis, and viral (including human papillomavirus; HPV) infection. According to the same method of classifying the vaginal microbiome, CST IV (non-Lactobacillusdominated) demonstrates a higher incidence of disorders.

METHODS

In an open, non-controlled study, we enrolled 35 HPV-positive women who mostly (N=24) demonstrated CST IV status, with the other individuals categorized as having either CST III (N=10) or CST II (N=1) microbiotas.

RESULTS

After 90 days of oral treatment with a probiotic (L. crispatus M247) we observed a reduction of approximately 70% in HPV positivity and a significant change in CST status with 94% of women now classified as CST I.

CONCLUSIONS

Despite the limitations of our study, it is the first demonstration that it is possible to intervene orally with an L. crispatus probiotic to bring about a change in CST status and, in parallel, increased HPV clearance.

Microbiome diversity predicts surgical success in patients with rectovaginal fistula

INTRODUCTION AND HYPOTHESIS

Growing literature details the critical importance of the microbiome in the modulation of human health and disease including both the gastrointestinal and genitourinary systems. Rectovaginal fistulae (RVF) are notoriously difficult to manage, many requiring multiple attempts at repair before correction is achieved. RVF involves two distinct microbiome communities whose characteristics and potential interplay have not been previously characterized and may influence surgical success.

METHODS

In this pilot study, rectal and vaginal samples were collected from 14 patients with RVF. Samples were collected preoperatively, immediately following surgery, 6-8 weeks postoperatively and at the time of any fistula recurrence. Amplification of the 16S rDNA V3-V5 gene region was done to identify microbiota. Data were summarized using both α-diversity to describe species richness and evenness and β-diversity to characterize the shared variation between communities. Differential abundance analysis was performed to identify microbial taxa associated with recurrence.

RESULTS

The rectal and vaginal microbiome in patients undergoing successful fistula repair was different than in those with recurrence (β-diversity, p = 0.005 and 0.018, respectively) and was characterized by higher species diversity (α-diversity, p = 0.07 and p = 0.006, respectively). Thirty-one taxa were enriched in patients undergoing successful repair to include Bacteroidetes, Alistipes and Rikenellaceae as well as Firmicutes, Subdoligranulum, Ruminococcaceae UCG-010 and NK4A214 group.

CONCLUSIONS

Microbiome characteristics associated with fistula recurrence have been identified. The association of higher vaginal diversity with a favorable outcome has not been previously described. Expansion of this pilot project is needed to confirm findings. Taxa associated with successful repair could be targeted for subsequent therapeutic intervention.

Changes of vaginal microbiota during cervical carcinogenesis in women with human papillomavirus infection

Objective

To evaluate the changes of vaginal microbiota during cervical carcinogenesis in women with high-risk human papillomavirus infection.

Materials and methods

Vaginal microbiota was analyzed using next-generation sequencing in women with normal, cervical intraepithelial neoplasia (CIN), or cervical cancer.

Results

A marked decrease of Lactobacillus crispatus was found in the CIN/cancer groups compared with that in the normal group. The diversity of microorganisms increased in patients with CIN or cervical cancer with HPV infection. Atopobium vaginae (OR 4.33, 95% CI 1.15–16.32), Dialister invisus (OR 4.89, 95% CI 1.20–19.94), Finegoldia magna (OR 6.00, 95% CI 1.08–33.27), Gardnerella vaginalis (OR 7.43, 95% CI 1.78–31.04), Prevotella buccalis (OR 11.00, 95% CI 2.00–60.57), and Prevotella timonensis (OR 6.00, 95% CI 1.46–24.69) were significantly associated with the risk of CIN 2/3 or cervical cancer.

Conclusion

Women with the CIN and cervical cancer showed a high diversity in vaginal microbiota. Depletion of Lactobacillus crispatus and increased abundance of anaerobic bacteria were detected in women with cervical disease.

[Ten questions about bacterial vaginosis]

The physiopathology of bacterial vaginosis (BV), the ultimate stage of vaginal dysbiosis, has benefited from recent advances in molecular biology, highlighting, among others, the important role of A. vaginae. Certain immunological specificities (variants of TLR4, elevation of IL-1β, for example) explain the variations in the prevalence of this infection, the poor clinical and cellular inflammatory response and the promoting influence of BV on the acquisition and progression of some sexually transmitted infections. These advances do not fully elucidate the causes of the high rate of recurrences. Some risk factors for relapses of BV have been identified such as tobacco use, stress or hygienic errors have been associated to relapses of BV. However, other paths are beginning to be explored such as the role of sexual transmission, the resistance of certain bacteria associated to BV to nitroimidazoles or the lack of efficacy of conventional treatments on dysbiosis itself. Taking into acount this vaginal dysbiosis appears to be important or even essential to better control the natural history of HPV-hr infection or improve the success rate of IVF, for example. Despite heterogeneous results, the use of probiotics as a complement to conventional treatments (nitroimidazoles, dequalinium chloride) has demonstrated a preventive effect on BV recurrences. Further studies are needed to customize the contribution of probiotics (or synbiotics) according to the individual specificities of the vaginal microbiome.

Association of high-risk human papillomavirus infection duration and cervical lesions with vaginal microbiota composition

Background

Cervical cancer is reportedly caused by the synergistic effects of persistent high-risk human papillomavirus (HPV) infection. Cervical microbiota represent a unique and dynamically changing microecological system that is directly exposed to the vagina. The relationship between HPV and the composition of the cervical microbiome has long been a primary focus of research.

Methods

To determine the specific differential florae throughout the process of cervical cancer development, in the present study, 16S rRNA sequencing was combined with KEGG pathway enrichment analysis to analyse five groups of cervical scraping samples with increasing durations of HPV infection and cervical intraepithelial neoplasia pathological classification.

Results

The findings revealed that decreasing levels of probiotics, including Shuttleworthia, Prevotella, Lactobacillus, and Sneathia, and increasing levels of pathogenic bacteria, including Dispar, Streptococcus, and Faecalibacterium prausnitzii, could be the direct result of early HPV infection. Other pathogenic bacteria, such as Bifidobacteriaceae, might represent key factors in cancer progression. Additionally, KEGG pathway enrichment analysis indicated that HPV infection directly inhibits multiple pathways, including those of sporulation, porphyrin and chlorophyll metabolism, arginine and proline metabolism, isoquinoline alkaloid biosynthesis, and ansamycin biosynthesis, which may lead to the development of early symptoms of cervical cancer. Biomarkers were predicted based on operational taxonomic unit (OTU) abundance data, and OTU851726 and OTU715913 were undoubtedly the best potential indicators of cervical cancer.

Conclusions

The findings of the present study could assist with the development of a guideline for screening new clinical drugs for cervical cancer.

Human papillomavirus infection and cervical intraepithelial neoplasia progression are associated with increased vaginal microbiome diversity in a Chinese cohort

BACKGROUND

In this study, the association between human papillomavirus (HPV) infection and related cervical intraepithelial neoplasia (CIN) or cervical cancer and vaginal microbiome was evaluated in Chinese cohorts.

METHODS

The vaginal bacterial composition of five groups, HPV-infected women without CINs (HPV, n = 78), women with low-grade squamous intraepithelial lesions (LSIL, n = 51), women with high-grade squamous intraepithelial lesions (HSIL, n = 23), women with invasive cervical cancer (Cancer, n = 9) and healthy women without HPV infection (Normal, n = 68), was characterized by deep sequencing of barcoded 16S rRNA gene fragments (V3-4) using Illumina MiSeq.

RESULTS

HPV infection increased vaginal bacterial richness and diversity regardless of the status of CINs. The vaginal bacterial richness and diversity were further augmented in women with cervical cancer. Lactobacillus was the most abundant genus in all groups. HPV infection had a negative influence on the abundances of Lactobacillus, Gardnerella and Atopobium. Accordingly, HPV infection increased the relative abundance of Prevotella, Bacillus, Anaerococcus, Sneathia, Megasphaera, Streptococcus and Anaerococcus. The increased proportions of Bacillus, Anaerococcus and the reduced abundance of Gradnerella vaginalis were probably related with the progression of CINs severity. HPV infection without CINs or cancerous lesions was strongly associated with Megasphaera. The most abundant bacterium in the LSIL group was Prevotella amnii. However, Prevotella timonensis, Shuttleworthia and Streptococcaceae at the family level were three taxa related to HSIL. Furthermore, more taxa were associated with the Cancer group including Bacillus, Sneathia, Acidovorax, Oceanobacillus profundus, Fusobacterium, Veillonellaceae at the family level, Anaerococcus and Porphyromonas uenonis. Samples in the Normal group were mostly assigned to CST III. HPV infection converted the vaginal bacterial community structure from CST III to CST IV. Furthermore, the proportions of CST IV were gradually augmented with the progression of the severity of CINs.

CONCLUSIONS

This work interpreted the differential vaginal bacteria under HPV infection and various precancerous or cancerous lesions in a Chinese cohort. We distinguished the specific microbes and the vaginal bacterial structure that were related with the progression of CINs severity in Chinese women.

Vaginal microbiota, genital inflammation, and neoplasia impact immune checkpoint protein profiles in the cervicovaginal microenvironment

Emerging evidence suggests that the vaginal microbiota play a role in HPV persistence and cervical neoplasia development and progression. Here we examine a broad range of immune checkpoint proteins in the cervicovaginal microenvironment across cervical carcinogenesis and explore relationships among these key immunoregulatory proteins, the microbiota composition, and genital inflammation. First, we demonstrate that immune checkpoint molecules can be measured in cervicovaginal lavages. Secondly, we identify CD40, CD27, and TIM-3 to specifically discriminate cervical cancer from other groups and CD40, CD28, and TLR2 to positively correlate to genital inflammation. Finally, PD-L1 and LAG-3 levels negatively, whereas TLR2 positively correlate to health-associated Lactobacillus dominance. Overall, our study identifies immune checkpoint signatures associated with cervical neoplasm and illuminates the multifaceted microbiota-host immunity network in the local microenvironment. This study provides a foundation for future mechanistic studies and highlights the utility of cervicovaginal lavage profiling for predicting and monitoring response to cancer therapy.

The microbiome and gynaecological cancer development, prevention and therapy

The female reproductive tract (FRT), similar to other mucosal sites, harbours a site-specific microbiome, which has an essential role in maintaining health and homeostasis. In the majority of women of reproductive age, the microbiota of the lower FRT (vagina and cervix) microenvironment is dominated by Lactobacillus species, which benefit the host through symbiotic relationships. By contrast, the upper FRT (uterus, Fallopian tubes and ovaries) might be sterile in healthy individuals or contain a low-biomass microbiome with a diverse mixture of microorganisms. When dysbiosis occurs, altered immune and metabolic signalling can affect hallmarks of cancer, including chronic inflammation, epithelial barrier breach, changes in cellular proliferation and apoptosis, genome instability, angiogenesis and metabolic dysregulation. These pathophysiological changes might lead to gynaecological cancer. Emerging evidence shows that genital dysbiosis and/or specific bacteria might have an active role in the development and/or progression and metastasis of gynaecological malignancies, such as cervical, endometrial and ovarian cancers, through direct and indirect mechanisms, including modulation of oestrogen metabolism. Cancer therapies might also alter microbiota at sites throughout the body. Reciprocally, microbiota composition can influence the efficacy and toxic effects of cancer therapies, as well as quality of life following cancer treatment. Modulation of the microbiome via probiotics or microbiota transplant might prove useful in improving responsiveness to cancer treatment and quality of life. Elucidating these complex host-microbiome interactions, including the crosstalk between distal and local sites, will translate into interventions for prevention, therapeutic efficacy and toxic effects to enhance health outcomes for women with gynaecological cancers.