The role of vaginal microecology in the cervical cancer

The Vaginal Microbiota, Human Papillomavirus Infection, and Cervical Carcinogenesis: A Systematic Review in the Latina Population

BACKGROUND

Latina women experience disproportionately higher rates of HPV infection, persistence, and progression to cervical dysplasia and cancer compared to other racial-ethnic groups. This systematic review explores the relationship between the cervicovaginal microbiome and human papillomavirus infection, cervical dysplasia, and cervical cancer in Latinas.

METHODS

The review abides by the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. PubMed, EMBASE, and Scopus databases were searched from January 2000 through November 11, 2022. The review included observational studies reporting on the cervicovaginal microbiota in premenopausal Latina women with human papillomavirus infection, cervical dysplasia, and cervical cancer.

RESULTS

Twenty-five articles were eligible for final inclusion (N = 131,183). Forty-two unique bacteria were reported in the cervicovaginal microbiome of Latinas. Seven bacteria: Lactobacillus crispatus, Lactobacillus iners, Chlamydia trachomatis, Prevotella spp., Prevotella amnii, Fusobacterium spp. and Sneathia spp. were enriched across multiple stages of cervical carcinogenesis in Latinas. Therefore, the total number of reported bacteria includes four bacteria associated with the healthy state, 16 bacteria enriched in human papillomavirus outcomes, 24 unique bacteria associated with abnormal cytology/dysplasia, and five bacteria associated with cervical cancer. Furthermore, three studies reported significantly higher alpha and beta diversity in Latinas with cervical dysplasia and cancer compared to controls. Lactobacillus depletion and an increased abundance of L. iners in Latinas compared to non-Latinas, regardless of human papillomavirus status or lesions, were observed.

CONCLUSIONS

The identification of 42 unique bacteria and their enrichment in cervical carcinogenesis can guide future cervicovaginal microbiome research to better inform cervical cancer prevention strategies in Latinas.

Cervicovaginal microbiota: a promising direction for prevention and treatment in cervical cancer

Cervical cancer is a common malignancy in women, with high incidence rate and mortality. Persistent infection of high-risk human papillomavirus (HPV) is the most important risk factor for cervical cancer and precancerous lesions. Cervicovaginal microbiota (CVM) plays an essential role in the defense of HPV infections and prevention of subsequent lesions. Dominance of Lactobacillus is the key of CVM homeostasis, which can be regulated by host, exogenous and endogenous factors. Dysbiosis of CVM, including altered microbial, metabolic, and immune signatures, can contribute to persist HPV infection, leading to cervical cancer. However, there is no evidence of the causality between CVM and cervical cancer, and the underlying mechanism remains unexplored. Considering the close correlation between CVM dysbiosis and persistent HPV infection, this review will overview CVM, its role in cervical cancer development and related mechanisms, and the prospects for therapeutic applications.

Understanding the Dynamics of Human Papillomavirus and Diagnostic Discrepancies in Cervical Pathology: A Single Center Experience

Cervical cancer (CC) is the most prevalent gynecological malignancy and a leading cause of death among women. It is primarily caused by human papillomavirus (HPV) infection, with 99.7% of cases showing high-risk HPV genotypes. This study sheds light on HPV dynamics as well as the discrepancies of different CC screening modalities results while highlighting factors that may have contributed to such a scenario. Moreover, we underscore the importance of the non-viral etiology of CC as well. We examined the current trends of HPV infection and its effects on cervical health in women treated at a tertiary care center in Belgrade, Serbia. Patients with abnormal colposcopy findings like dysplasia and re-epithelization were more likely to test negative for HPV (p < 0.001). Interestingly, women with a positive Pap smear tested HPV negative significantly more often (p = 0.041). Finally, HPV-positive individuals were more likely to have CIN I and II histologies (p < 0.001), while CIN III occurred equally in women with and without the virus. It may be inferred that inconsistencies in detecting HPV and the presence of cervical lesions may eventually result in adjustments to screening guidelines, as is crucial to adopt a meticulous approach to promote periodical CC screening, as initial samples may test negative for HPV.

Relationship between vaginal microecological changes and oncogene E6/E7 and high-risk human papillomavirus infection

High-risk (HR)-human papillomavirus (HPV) is the leading cause of precancerous cervical lesions in patients with chronic untreated infection. We investigated the relationships among several vaginal microbiological alterations, oncogene E6/E7 expression, and HR-HPV. A total of 1327 women who underwent HPV screening, vaginal microecology determination, and fluid-based thin-layer cytological test were enrolled and classified into the HPV-negative group, the low-risk (LR)-HPV-positive group, and the HR-HPV-positive group. The status of cervical HPV infection, vaginal microecology, and E6/E7 mRNA expression were examined sequentially. The effect of HR-HPV infection on cervical cancer (CC) was meticulously assessed, and associations between HR-HPV infection and vaginal microecology and E6/E7 mRNA were identified. In total 548/1327 patients were HPV positive, including LR-HPV infection (N = 132) and HR-HPV infection (N = 416). Patients in the HR-HPV positive group revealed higher detection rates of bacterial vaginosis (BV), trichomonal vaginitis (TV), and vulvovaginal candidiasis (VVC) relative to the HPV negative group. A higher E6/E7 mRNA expression was identified in HR-HPV patients compared to LR-HPV patients. BV and E6/E7 mRNA were classified as independent risk factors for HR-HPV infection. Patients with HR-HPV infection were more susceptible to CC development. Overall, BV and E6/E7 mRNA expression were identified as independent risk factors for HR-HPV infection.IMPACT STATEMENTWhat is already known on this subject? Through literature review, we found that vaginal ecological changes increase the risk of HPV infection, and HPV persistent infection is an important risk factor for cervical precancerous lesions and cervical cancer. In addition, HPV gene E6/E7 is expressed in HPV-positive cervical cancer cells, which is related to cell malignant transformation and even tumorigenesis.What do the results of this study add? This study further revealed that bacterial vaginosis (BV) and E6/E7 mRNA were independently correlated with HR-HPV infection, and HR-HPV infection increased the risk of cervical cancer.What are the implications of these findings for clinical practice and/or further research? E6/E7 mRNA detection may be used as a new auxiliary diagnostic index for HR-HPV infection. In addition, this study provides a reference for whether the restoration of vaginal microecological balance in patients with BV undergoing clinical treatment is conducive to HR-HPV regression, and provides theoretical support for the prevention and control of cervical cancer microecological approach and the occurrence and development of cervical cancer.

HPV infection and vaginal microecological disorders in women with intrauterine adhesion: cross-sectional study in a Chinese population

BACKGROUND

The purpose of this study was to evaluate the vaginal microecology and the distribution of human papillomavirus (HPV) subtypes in patients with uterine adhesions and explore the correlation between HPV infection and vaginal microecology imbalance and the occurrence of intrauterine adhesion (IUA).

METHODS

A total of 479 women were enrolled in the study, including 259 in the normal group and 220 in the IUA group. Vaginal microecological and HPV analyses were performed on all participants. Significant differences between the two groups were analyzed, and Spearman correlation analysis was performed.

RESULTS

The incidence of IUA in patients between 31 and 40 years of age was high. The I-II degree of vaginal cleanliness in the IUA group was significantly lower than that in the normal group, and the number of III-IV degree was significantly higher than that in the normal group. Moreover, the incidences of VVC (vulvovaginal candidiasis) and vaginal disorders and infections with HPV 16 and HPV 52 subtypes were significantly higher in the IUA group than in the normal group. The incidence of high-risk HPV infection combined with vaginal disorders in the IUA group was higher than that in the normal group. Correlation analysis showed that the occurrence of IUAs was positively correlated with HPV infection and negatively correlated with PH and vaginal microecological imbalance.

CONCLUSION

The HPV infection rate and vaginal microecology disorders affect the occurrence of IUAs. For patients with IUAs, control of the HPV infection rate and the prevention of vaginal microecological disorders should be improved.

Unraveling the Dysbiosis of Vaginal Microbiome to Understand Cervical Cancer Disease Etiology-An Explainable AI Approach

Microbial Dysbiosis is associated with the etiology and pathogenesis of diseases. The studies on the vaginal microbiome in cervical cancer are essential to discern the cause and effect of the condition. The present study characterizes the microbial pathogenesis involved in developing cervical cancer. Relative species abundance assessment identified Firmicutes, Actinobacteria, and Proteobacteria dominating the phylum level. A significant increase in Lactobacillus iners and Prevotella timonensis at the species level revealed its pathogenic influence on cervical cancer progression. The diversity, richness, and dominance analysis divulges a substantial decline in cervical cancer compared to control samples. The β diversity index proves the homogeneity in the subgroups' microbial composition. The association between enriched Lactobacillus iners at the species level, Lactobacillus, Pseudomonas, and Enterococcus genera with cervical cancer is identified by Linear discriminant analysis Effect Size (LEfSe) prediction. The functional enrichment corroborates the microbial disease association with pathogenic infections such as aerobic vaginitis, bacterial vaginosis, and chlamydia. The dataset is trained and validated with repeated k-fold cross-validation technique using a random forest algorithm to determine the discriminative pattern from the samples. SHapley Additive exPlanations (SHAP), a game theoretic approach, is employed to analyze the results predicted by the model. Interestingly, SHAP identified that the increase in Ralstonia has a higher probability of predicting the sample as cervical cancer. New evidential microbiomes identified in the experiment confirm the presence of pathogenic microbiomes in cervical cancer vaginal samples and their mutuality with microbial imbalance.

Inhibitory effect and mechanism of Lactobacillus crispatus on cervical precancerous cells Ect1/E6E7 and screening of early warning factors

OBJECTIVE

To study the potential mechanism of Lactobacillus crispatus inhibiting cervical squamous intraepithelial lesion (SIL) and screen the early warning factors of SIL.

METHODS

The effects of Lactobacillus crispatus on the proliferation, apoptosis, cross pore migration and invasion and cytokines of cervical precancerous cells Ect1/E6E7 were detected respectively. The effect of Lactobacillus crispatus on the expression of differential proteins screened in Ect1/E6E7 cells were detected by Western blot.

RESULTS

Lactobacillus crispatus significantly inhibited the proliferation, induced apoptosis and inhibited cell migration of Ect1/E6E7 cells in a time-dependent manner (P < 0.05), but had no significant effect on cell invasion. Lactobacillus crispatus significantly promoted the secretion of Th1 cytokines and inhibited the secretion of Th2 cytokines by Ect1/E6E7 cells (P < 0.05). In addition, compared with SiHa cells in the control group, the expression of differential proteins PCNA, ATM, LIG1 and HMGB1 in Ect1/E6E7cells decreased significantly, while the expression of TDG and OGG1 proteins increased significantly (P < 0.05). ABCG2 protein in Ect1/E6E7 cells was slightly higher than that in SiHa cells, but the difference was not statistically significant. What is interesting is that Lactobacillus crispatus significantly inhibited the expression of ABCG2, PCNA, ATM, LIG1, OGG1 and HMGB1 proteins in Ect1/E6E7 cells, and promoted the expression of TDG protein.

CONCLUSIONS

Lactobacillus crispatus may inhibit the function of Ect1/E6E7 cells through multiple pathways and exert the potential to reverse the progression of SIL.