Bacteria in the vaginal microbiome alter the innate immune response and barrier properties of the human vaginal epithelia in a species-specific manner

Changes to the cervicovaginal microbiota and cervical cytokine profile following surgery for cervical intraepithelial neoplasia

Persistent HPV infection associated with immune modulation may result in high-grade squamous intraepithelial lesions (CIN)2/3. Currently, there is little information on the cervicovaginal microbiome, local cytokine levels and HPV infection related to CIN. Follow-up of patients after local surgery provides an opportunity to monitor changes in the cervicovaginal environment. Accordingly, we undertook this longitudinal retrospective study to determine associations between HPV genotypes, cervicovaginal microbiome and local cytokine profiles in 41 Japanese patients with CIN. Cervicovaginal microbiota were identified using universal 16S rRNA gene (rDNA) bacterial primers for the V3/4 region by PCR of genomic DNA, followed by MiSeq sequencing. We found that Atopobium vaginae was significantly decreased (p < 0.047), whereas A. ureaplasma (p < 0.022) increased after surgery. Cytokine levels in cervical mucus were measured by multiplexed bead-based immunoassays, revealing that IL-1β (p < 0.006), TNF-α (p < 0.004), MIP-1α (p < 0.045) and eotaxin (p < 0.003) were significantly decreased after surgery. Notably, the level of eotaxin decreased in parallel with HPV clearance after surgery (p < 0.028). Thus, local surgery affected the cervicovaginal microbiome, status of HPV infection and immune response. Changes to the cervicovaginal microbiota and cervical cytokine profile following surgery for cervical intraepithelial neoplasia may be important for understanding the pathogenesis of CIN in future.

Functional impact of allelic variations/haplotypes of TNF-α on reproductive tract infections in Indian women

The aim of the present study is to investigate the functional role of TNF-α single-nucleotide polymorphisms/haplotypes in an association with reproductive tract infections (RTIs) in symptomatic and asymptomatic women. A total of 850 consecutive subjects consisting of 400 cases and 450 healthy controls, were screened for RTIs, along with their risk factors and associated symptoms. The propensity score matching was performed to reduce the confounding bias arise owing to covariates and to balance the data between two groups. A total of 211 pairs (1:1) have been created. Genotyping of rs1800629 (-308) and rs361525 (-238) SNPs of TNF-α was done by PCR–RFLP followed by sequencing. The functional implication of TNF-α SNPs in an association with RTIs was also checked by using ELISA. The frequency of -238A allele and -308A allele was found to be twofold (P < 0.0001) and threefold (P < 0.0001) higher in the presence of RTIs. AA haplotype emerged as a major player in an association with RTIs and elevated TNF-α expression. The present study revealed the functional role of rs1800629 (-308) and rs361525 (-238) of TNF-α in an association with RTIs. This information may be used to establish biomarkers for an inflammatory response during the persistence of RTIs.

Dysbiosis of the rat vagina is efficiently rescued by vaginal microbiota transplantation or probiotic combination

Vaginal dysbiosis is characterised by a disturbed vaginal microbiota and is associated with various gynaecological diseases. Owing to its high recurrence rate, there is an urgent need for the development of effective therapeutic agents. In the present study, a vaginal dysbiosis model was developed to study the effect of vaginal microbiota transplantation (VMT) or probiotic combination (containing Lactobacillus helveticus, Lactobacillus crispatus, Lactobacillus acidophilus, Lactobacillus gasseri and Lactobacillus salivarius) on vaginal dysbiosis. Our results indicated that VMT or probiotic combination significantly reduced bacterial-induced inflammation (infiltration of neutrophils, lymphocytes and monocytes) in the uterine wall and the enrichment of pro-inflammatory cytokines [interleukin-1β (IL-1β) and tumour necrosis factor-alpha (TNFα)] in vaginal tissue, and restored the disturbed vaginal microbiota to normal levels (increased numbers of Lactobacillus and decreased numbers of Enterobacter and Enterococcus), thus it should be beneficial for avoiding the recurrence of vaginal dysbiosis. Therefore, VMT or probiotic combination might be an effective agent for the treatment of bacterial-induced vaginosis.

Depiction of Vaginal Microbiota in Women With High-Risk Human Papillomavirus Infection

Persistent infection with the carcinogenic human papillomavirus (HPV) is a prerequisite for the progression of cervical lesions and cancer. A growing body of research has focused on the functional role of the vaginal microbiota in the persistence of HPV infection. Understanding the microbial composition and structure in women with high-risk (hr)-HPV infection may help reveal associations between the vaginal microbiota and HPV infection, and identify potential biomarkers. Our study investigated the vaginal microbial community in women with and without hr-HPV infection, by using 16s rRNA gene sequencing. We found that microbial perturbations occurred in the early phase of hr-HPV infection. Lactobacillus and Sporolactobacillus were decreased, while bacteria related to bacterial vaginosis (BV), such as Gardnerella, Prevotella, Dialister, Slackia, Actinomyces, Porphyromonas, Peptoniphilus, Anaerococcus, Peptostreptococcus, Streptococcus, Ureaplasma, Megasphaera, and Mycoplasma were increased. Our results could offer insights into the correlations between hr-HPV and the vaginal microbiota in the early infection period, and provide indications that the predominance of some BV-associated bacteria during hr-HPV infection may increase the risk for cervical neoplasia.

Effect of oral consumption of capsules containing Lactobacillus paracasei LPC-S01 on the vaginal microbiota of healthy adult women: a randomized, placebo-controlled, double-blind crossover study

Oral consumption of probiotics is practical and can be an effective solution to preserve vaginal eubiosis. Here, we studied the ability of orally administered Lactobacillus paracasei LPC-S01 (DSM 26760) to affect the composition of the vaginal microbiota and colonize the vaginal mucosa in nondiseased adult women. A total of 40 volunteers took oral probiotic (24 billion CFU) or placebo capsules daily for 4 weeks, and after a 4-week washout, they switched to placebo or probiotic capsules according to the crossover design. A total of 23 volunteers completed the study according to the protocol. Before and after capsule ingestion, vaginal swabs were collected for qPCR quantification to detect L. paracasei LPC-S01 and for 16S rRNA gene sequencing. Vaginal swabs were grouped according to their bacterial taxonomic structure into nine community state types (CSTs), four of which were dominated by lactobacilli. Lactobacillus paracasei LPC-S01 was detected in the vagina of two participants. Statistical modeling (including linear mixed-effects model analysis) demonstrated that daily intake of probiotic capsules reduced the relative abundance of Gardnerella spp. Quantitative PCR with Gardnerella vaginalis primers confirmed this result. Considering the pathogenic nature of G. vaginalis, these results suggest a potential positive effect of this probiotic capsule on the vaginal microbial ecosystem.

Members of Prevotella Genus Distinctively Modulate Innate Immune and Barrier Functions in a Human Three-Dimensional Endometrial Epithelial Cell Model

BACKGROUND

Prevotella species are commonly isolated from the reproductive tract of women with obstetric/gynecologic health complications. However, contributions of this genus to changes in local microenvironment are not well characterized. Our objective was to evaluate species-specific effects of Prevotella on the human endometrial epithelium.

METHODS

Thirteen Prevotella strains, originally isolated from the human oral cavity, amniotic fluid, endometrium, or vagina (including women with bacterial vaginosis), were obtained from BEI and ATCC resources. Bacteria were evaluated in silico and in vitro using human endometrial epithelial cells (EEC) grown as monolayers or a 3-dimensional (3D) model.

RESULTS

Genomic characterization illustrated metabolic and phylogenetic diversity of Prevotella genus. Among tested species, P. disiens exhibited cytotoxicity. Scanning electron microscopy analysis of the 3D EEC model revealed species-specific colonization patterns and alterations of ultracellular structures. Infection with sialidase-producing P. timonensis resulted in elongated microvilli, and increased MUC3 and MUC4 expression. Infections with Prevotella species, including P. bivia, did not result in significant proinflammatory activation of EEC.

CONCLUSIONS

Collectively, findings indicate that Prevotella species are metabolically diverse and overall not cytotoxic or overtly inflammatory in EEC; however, these bacteria can form biofilms, alter barrier properties of the endometrial epithelium, and ultimately impact colonization of secondary colonizers.

Pathogenesis and Clinical Relevance of Candida Biofilms in Vulvovaginal Candidiasis

The ability of Candida spp. to form biofilms is crucial for its pathogenicity, and thus, it should be considered an important virulence factor in vulvovaginal candidiasis (VVC) and recurrent VVC (RVVC). Its ability to generate biofilms is multifactorial and is generally believed to depend on the site of infection, species and strain involved, and the microenvironment in which the infection develops. Therefore, both cell surface proteins, such as Hwp1, Als1, and Als2, and the cell wall-related protein, Sun41, play a critical role in the adhesion and virulence of the biofilm. Immunological and pharmacological approaches have identified the NLRP3 inflammasome as a crucial molecular factor contributing to host immunopathology. In this context, we have earlier shown that Candida albicans associated with hyphae-secreted aspartyl proteinases (specifically SAP4-6) contribute to the immunopathology of the disease. Transcriptome profiling has revealed that non-coding transcripts regulate protein synthesis post-transcriptionally, which is important for the growth of Candida spp. Other studies have employed RNA sequencing to identify differences in the 1,245 Candida genes involved in surface and invasive cellular metabolism regulation. In vitro systems allow the simultaneous processing of a large number of samples, making them an ideal screening technique for estimating various physicochemical parameters, testing the activity of antimicrobial agents, and analyzing genes involved in biofilm formation and regulation (in situ) in specific strains. Murine VVC models are used to study C. albicans infection, especially in trials of novel treatments and to understand the cause(s) for resistance to conventional therapeutics. This review on the clinical relevance of Candida biofilms in VVC focuses on important advances in its genomics, transcriptomics, and proteomics. Moreover, recent experiments on the influence of biofilm formation on VVC or RVVC pathogenesis in laboratory animals have been discussed. A clear elucidation of one of the pathogenesis mechanisms employed by Candida biofilms in vulvovaginal candidiasis and its applications in clinical practice represents the most significant contribution of this manuscript.

Vaginal microbiota diversity and paucity of Lactobacillus species are associated with persistent hrHPV infection in HIV negative but not in HIV positive women

The vaginal microbiota is thought to play a role in modulating risk of high-risk human papillomavirus (hrHPV) infection. We examined the relationship between the vaginal microbiota and persistent hrHPV infection in HIV-negative and HIV-positive women. We used 16S-rRNA sequencing to characterize the vaginal microbiota of two serial samples taken six months apart from 211 Nigerian women (67%, 142/211 HIV-positive and 33%, 69/211 HIV-negative) and evaluated the association between the vaginal microbiota and persistent hrHPV infection using generalized estimating equation logistic regression models and linear discriminant analysis effect size (LEfSe) algorithm to identify phylotypic biomarkers of persistent hrHPV infection. The high diversity microbiota, Community State Type IV-B, was the most prevalent in both HIV-negative (38% at baseline, 30% at the follow-up visit) and HIV-positive (27% at baseline, 35% at the follow-up visit) women. The relationship between the vaginal microbiota and persistent hrHPV was modified by HIV status. In HIV-negative women, women with Lactobacillus dominant microbiota had lower odds (OR: 0.35, 95% CI 0.14-0.89, p = 0.03) of persistent hrHPV compared to women with Lactobacillus deficient microbiota. While among HIV-positive women, the odds of being persistently infected with hrHPV was higher in women with Lactobacillus dominant microbiota (OR: 1.25, 95% CI 0.73-2.14 p = 0.41). This difference in effect estimates by HIV was statistically significant (p = 0.02). A high diversity vaginal microbial community with paucity of Lactobacillus species was associated with persistent hrHPV infection in HIV-negative women but not in HIV-positive women.

Elevation of cervical C-X-C motif chemokine ligand 10 levels is associated with HIV-1 acquisition in pregnant and postpartum women

OBJECTIVE

To evaluate the relationship between cervical cytokine/chemokine concentrations and HIV-1 acquisition in peripartum Kenyan women.

DESIGN

Nested case-control study.

METHODS

Women participating in a prospective study of peripartum HIV acquisition in Kenya (the Mama Salama Study), were tested for HIV-1 at 1-3 month intervals during pregnancy and through 9 months postpartum. Cases positive for HIV-1 RNA during follow-up (N = 14), were matched 3 : 1 with HIV-negative controls (N = 42) based on age, marital status, partner HIV-1 status, transactional sex, and timing of cervical swab collection. Concentrations of five cytokines (IL-1β, IL-6, IL-10, IFNγ, and TNFα) and four chemokines (IL-8, C-X-C motif chemokine ligand 10 (CXCL10), macrophage inflammatory protein-1 α, and macrophage inflammatory protein-1 β) were measured from cervical swabs collected at the visit prior to HIV-1 diagnosis (cases) or matched gestational/postpartum time (controls). Cytokine/chemokine concentrations were compared between cases and controls using Wilcoxon rank-sum tests. Principal component analysis was used to create a summary score for closely correlated cytokines/chemokines. Associations with HIV-1 acquisition were analyzed using conditional logistic regression. Path analysis was used to evaluate hypothesized relationships between CXCL10, vaginal washing, Nugent score, and HIV-1 acquisition.

RESULTS

Conditional logistic regression analysis demonstrated an association between increased concentrations of CXCL10 and HIV-1 acquisition (odds ratio = 1.74, 95% confidence interval 1.04, 2.93; P = 0.034). Path analysis confirmed a positive independent association between higher concentrations of CXCL10 and HIV-1 acquisition (path coefficient = 0.37, 95% confidence interval 0.15, 0.59; P < 0.001).

CONCLUSION

HIV-1 acquisition was associated with increased cervical concentrations of CXCL10 in pregnant and postpartum women.

Cervical-Vaginal Microbiome and Associated Cytokine Profiles in a Prospective Study of HPV 16 Acquisition, Persistence, and Clearance

Persistent human papillomavirus (HPV) infections is necessary for the development of cervical cancers. Consequently, understanding the biologic mechanisms resulting in clearance is key in cancer prevention. Similar to other mucosal sites, it is expected that the local microbiome plays a significant role in shaping the immune response responsible for HPV clearance. Using cervical wash repository samples from a prospective study of HPV in women, this study investigates the microbiome and its associated inflammatory milieu during HPV 16 pre-acquisition, persistence and clearance states. For comparison, samples from women with no history of HPV ever during the study period were selected. We showed that 9 of 13 inflammatory cytokines were found to be significantly increased in the immediate post-clearance visit compared to the pre-acquisition or infection visits. Gardnerella vaginalis was associated with higher levels of inflammatory cytokines. Women with no history of HPV infection had similar cytokine profiles as those with HPV 16 post-clearance. This in vivo study documented an immune response shortly after HPV 16 clearance. G. vaginalis appeared to be involved in shaping this immune response. The appearance of G. vaginalis may have resulted from a shift from anti-microbial to anti-viral immune response with loss of bacterial control. The similar high levels of cytokines seen in women with no history of HPV suggest that a certain level of inflammatory surveillance is required to maintain an HPV negative state. This data may inform therapies such as probiotics or pro-inflammatory agents for treatment of persistent HPV.

Co-infection with trichomonas vaginalis increases the risk of cervical intraepithelial neoplasia grade 2-3 among HPV16 positive female: a large population-based study

Background

Evidence suggested that vaginal microbiome played a functional role in the progression of cervical lesions in female infected by HPV. This study aimed at evaluating the influence of common vaginal infection on the carcinogenicity of high risk HPV (hr-HPV).

Methods

From January 15, 2017 to December 31, 2017, 310,545 female aged at least 30 years old had been recruited for cervical cancer screening from 9 clinical research centers in Central China. All the recruited participants received hr-HPV genotyping for cervical cancer screening and vaginal microenvironment test by a high vaginal swab. Colposcopy-directed biopsy was recommended for female who were infected with HPV 16 and HPV 18, and other positive hr-HPV types through test had undertaken triage using liquid-based cytology, cases with the results ≥ ASCUS among them were referred to colposcopy directly, and cervical tissues were taken for pathology examination to make clear the presence or absence of other cervical lesions.

Results

Among 310,545 female, 6067 (1.95%) were tested with positive HPV 16 and HPV 18, 18,297 (5.89%) were tested with other positive hr-HPV genotypes, cervical intraepithelial neoplasia (CIN) 1, CIN 2, CIN 3 and invasive cervical cancer (ICC) were detected in 861 cases, 377 cases, 423 cases, and 77 cases, respectively. Candida albicans and Gardnerella were not associated with the detection of cervical lesions. Positive trichomonas vaginitis (TV) was correlated with hr-HPV infection (p < 0.0001). Co-infection with TV increased the risk of CIN 1 among female infected with hr-HPV (OR 1.18, 95% CI: 1.42–2.31). Co-infection with TV increased the risk of CIN 2–3 among female infected with HPV 16 (OR 1.71, 95% CI: 1.16–2.53).

Conclusions

Co-infection of TV and HPV 16 is a significant factor for the detection of cervical lesions.

Differential Response of Gestational Tissues to TLR3 Viral Priming Prior to Exposure to Bacterial TLR2 and TLR2/6 Agonists

Background: Infection/inflammation is an important causal factor in spontaneous preterm birth (sPTB). Most mechanistic studies have concentrated on the role of bacteria, with limited focus on the role of viruses in sPTB. Murine studies support a potential multi-pathogen aetiology in which a double or sequential hit of both viral and bacterial pathogens leads to a higher risk preterm labour. This study aimed to determine the effect of viral priming on bacterial induced inflammation in human in vitro models of ascending and haematogenous infection.

Methods: Vaginal epithelial cells, and primary amnion epithelial cells and myocytes were used to represent cell targets of ascending infection while interactions between peripheral blood mononuclear cells (PBMCs) and placental explants were used to model systemic infection. To model the effect of viral priming upon the subsequent response to bacterial stimuli, each cell type was stimulated first with a TLR3 viral agonist, and then with either a TLR2 or TLR2/6 agonist, and responses compared to those of each agonist alone. Immunoblotting was used to detect cellular NF-κB, AP-1, and IRF-3 activation. Cellular TLR3, TLR2, and TLR6 mRNA was quantified by RT-qPCR. Immunoassays were used to measure supernatant cytokine, chemokine and PGE2 concentrations.

Results: TLR3 (“viral”) priming prior to TLR2/6 agonist (“bacterial”) exposure augmented the pro-inflammatory, pro-labour response in VECs, AECs, myocytes and PBMCs when compared to the effects of agonists alone. In contrast, enhanced anti-inflammatory cytokine production (IL-10) was observed in placental explants. Culturing placental explants in conditioned media derived from PBMCs primed with a TLR3 agonist enhanced TLR2/6 agonist stimulated production of IL-6 and IL-8, suggesting a differential response by the placenta to systemic inflammation compared to direct infection as a result of haematogenous spread. TLR3 agonism generally caused increased mRNA expression of TLR3 and TLR2 but not TLR6.

Conclusion: This study provides human in vitro evidence that viral infection may increase the susceptibility of women to bacterial-induced sPTB. Improved understanding of interactions between viral and bacterial components of the maternal microbiome and host immune response may offer new therapeutic options, such as antivirals for the prevention of PTB.

The relationship between the presence of HPV infection and biofilm formation in cervicovaginal smears

PURPOSE

To demonstrate and understand the association of HPV infection and biofilm formation.

METHODS

The study consisted of cervicovaginal samples of 72 women who were evaluated at the colposcopy unit. Papanicolaou staining was used for cytological examination while "Crystal Violet Binding" assay was performed to detect biofilm formation.

RESULTS

HPV-DNA was positive in 55.5% (n = 40) of the patients. The biofilm formation rate was statistically significantly higher in the HPV-positive women (45%) compared to HPV-negative women (21.9%) (P < 0.05). There was a statistically significant relationship between the presence of single HPV and "high-risk HPV" types and biofilm formation (P < 0.05). Biofilm formation was found in 80% of women with abnormal smear demonstrating atypical epithelial cells (P < 0.05).

CONCLUSION

Biofilm formation is more frequent at the cervicovaginal microbiota of patients with HPV infection. This finding is especially important in cases with atypical epithelial cells at their cervicovaginal smears.

Characteristics of aerobic vaginitis among women in Xi'an district: a hospital-based study

BACKGROUND

Aerobic vaginitis (AV) is a reproductive tract infection that affects health of women. The objective of this study was to analyze the characteristics of simple and mixed AV patients in Xi'an district and provide reference data for the clinical treatment of AV.

METHODS

Patients were recruited from the outpatient Department of Obstetrics and Gynecology in the First Affiliated Hospital of Xi'an Jiaotong University from September 2014 to April 2019 in strict accordance with inclusion and exclusion criteria. The study principally examined the vaginal ecosystem, age distribution, levels of functional enzymes, and changes in pH levels in these women. Differences within groups were analyzed.

RESULTS

A total of 284 AV patients were enrolled to investigate the distribution of simple and mixed AV infection. AV infection was found to be mainly simple infection. Simple AV patients were generally aged 50-60 years, while mixed AV patients were mostly aged 30-40 years. In the present study, the density of vaginal bacteria (OR = 13.294, 95% CI = 5.869-30.115, P < 0.01), the type of predominant bacteria (OR = 3.962, 95% CI = 1.785-7.984, P < 0.01) and positive expression of coagulase (OR = 3.789, 95% CI = 1.798-7.984, P < 0.01) were considered risk factors for mixed AV infection.

CONCLUSIONS

The epidemiology of simple and mixed AV infection were found to be different, with density of vaginal bacteria (I or IV), species that are predominant and levels of coagulase being risk factors for mixed AV infection.

Inflammatory and antimicrobial properties differ between vaginal Lactobacillus isolates from South African women with non-optimal versus optimal microbiota

Female genital tract (FGT) inflammation increases HIV infection susceptibility. Non-optimal cervicovaginal microbiota, characterized by depletion of Lactobacillus species and increased bacterial diversity, is associated with increased FGT cytokine production. Lactobacillus species may protect against HIV partly by reducing FGT inflammation. We isolated 80 lactobacilli from South African women with non-optimal (Nugent 4–10; n = 18) and optimal microbiota (Nugent 0–3; n = 14). Cytokine production by vaginal epithelial cells in response to lactobacilli in the presence and absence of Gardnerella vaginalis was measured using Luminex. Adhesion to vaginal epithelial cells, pH, D/L-lactate production and lactate dehydrogenase relative abundance were assessed. Lactobacilli from women with non-optimal produced less lactic acid and induced greater inflammatory cytokine production than those from women with optimal microbiota, with IL-6, IL-8, IL-1α, IL-1β and MIP-1α/β production significantly elevated. Overall, lactobacilli suppressed IL-6 (adjusted p < 0.001) and IL-8 (adjusted p = 0.0170) responses to G. vaginalis. Cytokine responses to the lactobacilli were inversely associated with lactobacilli adhesion to epithelial cells and D-lactate dehydrogenase relative abundance. Thus, while cervicovaginal lactobacilli reduced the production of the majority of inflammatory cytokines in response to G. vaginalis, isolates from women with non-optimal microbiota were more inflammatory and produced less lactic acid than isolates from women with optimal microbiota.

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.

Analysis of Host Responses to Neisseria gonorrhoeae Using a Human Three-Dimensional Endometrial Epithelial Cell Model

Neisseria gonorrhoeae infections have been associated with complications including chronic endometritis and pelvic inflammatory disease. Robust in vitro models of the female reproductive tract are urgently needed to better understand the biological mechanisms leading to these pathophysiological changes. Our human three-dimensional (3D) endometrial epithelial cell (EEC) model, which is generated using the HEC-1A cell line and rotating wall vessel (RWV) bioreactor technology, replicates several hallmarks of endometrial tissue in vivo. Studying the interactions of N. gonorrhoeae with the host using this newly characterized human 3D EEC model allows for the investigation of unique mechanisms of gonococcal pathogenesis in the upper female reproductive tract. In this chapter, we describe methodologies that can be used to investigate the interactions of N. gonorrhoeae with the human 3D endometrial epithelium. Protocols for generating the human 3D EEC model using the RWV technology and assessing the host response (including morphological/ultrastructural changes to the epithelial cells; cytokine/chemokine secretion or gene expression changes) following infection with N. gonorrhoeae are presented.

Cholesterol-Dependent Cytolysins Produced by Vaginal Bacteria: Certainties and Controversies

Bacterial vaginosis (BV) is a vaginal anaerobic dysbiosis that affects women of reproductive age worldwide. BV is microbiologically characterized by the depletion of vaginal lactobacilli and the overgrowth of anaerobic bacterial species. Accumulated evidence suggests that Gardnerella spp. have a pivotal role among BV-associated bacteria in the initiation and development of BV. However, Gardnerella spp. often colonize healthy women. Lactobacillus iners is considered as a prevalent constituent of healthy vaginal microbiota, and is abundant in BV. Gardnerella spp. and L. iners secrete the toxins vaginolysin (VLY) and inerolysin (INY), which have structural and activity features attributed to cholesterol-dependent cytolysins (CDCs). CDCs are produced by many pathogenic bacteria as virulence factors that participate in various stages of disease progression by forming lytic and non-lytic pores in cell membranes or via pore-independent pathways. VLY is expressed in the majority of Gardnerella spp. isolates; less is known about the prevalence of the gene that encodes INY. INY is a classical CDC; membrane cholesterol acts a receptor for INY. VLY uses human CD59 as its receptor, although cholesterol remains indispensable for VLY pore-forming activity. INY-induced damage of artificial membranes is directly dependent on cholesterol concentration in the bilayer, whereas VLY-induced damage occurs with high levels of membrane cholesterol (>40 mol%). VLY primarily forms membrane-embedded complete rings in the synthetic bilayer, whereas INY forms arciform structures with smaller pore sizes. VLY activity is high at elevated pH, which is characteristic of BV, whereas INY activity is high at more acidic pH, which is specific for a healthy vagina. Increased VLY levels in vaginal mucosa in vivo were associated with clinical indicators of BV. However, experimental evidence is lacking for the specific roles of VLY and INY in BV. The interplay between vaginal bacterial species affects the expression of the gene encoding VLY, thereby modulating the virulence of Gardnerella spp. This review discusses the current evidence for VLY and INY cytolysins, including their structures and activities, factors affecting their expression, and their potential impacts on the progression of anaerobic dysbiosis.

Distinct Immune Responses Elicited From Cervicovaginal Epithelial Cells by Lactic Acid and Short Chain Fatty Acids Associated With Optimal and Non-optimal Vaginal Microbiota

Non-optimal vaginal microbiota, as observed in bacterial vaginosis (BV), is typically characterized by a depletion of beneficial lactobacilli and an abundance of numerous anaerobes. These non-optimal conditions are associated with subclinical cervicovaginal inflammation and an increased risk of HIV infection compared to women colonized with optimal vaginal microbiota dominated by lactobacilli. Lactic acid (LA) is a major organic acid metabolite produced by vaginal lactobacilli that elicits anti-inflammatory effects from cervicovaginal epithelial cells and is dramatically depleted during BV. However, it is unclear if LA retains its anti-inflammatory activity in the presence of vaginal microbiota metabolites comprising short chain fatty acids (SCFAs) and succinic acid, which are also produced by an optimal vaginal microbiota. Furthermore, the immunomodulatory effect of SCFAs and succinic acid on cervicovaginal epithelial cells at higher concentrations present during BV is unknown. Here we report that in the presence of physiologically relevant concentrations of SCFAs and succinic acid at pH 3.9 (as found in women with lactobacillus-dominated microbiota) LA induced an anti-inflammatory state in cervicovaginal epithelial cells and inhibited inflammation elicited by the toll-like receptor (TLR) agonists polyinosinic:polycytidylic acid and Pam3CSK4. When cervicovaginal epithelial cells were treated with a vaginal microbiota metabolite mixture representative of BV, containing a lower concentration of LA but higher concentrations of SCFA/succinic acid at pH 7, no anti-inflammatory was observed. Rather, the vaginal microbiota metabolite mixture representative of BV dysregulated the immune response of cervicovaginal epithelial cells during prolonged and sustained treatments. This was evidenced by increased basal and TLR-induced production of pro-inflammatory cytokines including tumor necrosis factor-α, but decreased basal production of chemokines including RANTES and IP-10. Further characterization of individual components of the BV vaginal microbiota mixture suggested that acetic acid is an important vaginal microbiota metabolite capable of eliciting diverse immunomodulatory effects on a range of cervicovaginal epithelial cell targets. These findings indicate that elevated levels of SCFAs are a potential source of cervicovaginal inflammation in women experiencing BV, and support the unique anti-inflammatory properties of LA on cervicovaginal epithelial cells as well as a role for LA or LA-producing lactobacilli to reverse genital inflammation associated with increased HIV risk.

The Unique Microbiome and Innate Immunity During Pregnancy

A successful pregnancy depends on not only the tolerance of the fetal immune system by the mother but also resistance against the threat of hazardous microorganisms. Infection with pathogenic microorganisms during pregnancy may lead to premature delivery, miscarriage, growth restriction, neonatal morbidity, and other adverse outcomes. Moreover, the host also has an intact immune system to avoid these adverse outcomes. It is important to note the presence of normal bacteria in the maternal reproductive tract and the principal role of the maternal-placental-fetal interaction in antimicrobial immunity. Previous studies mainly focused on maternal infection during pregnancy. However, this review summarizes the new views on the study of the maternal microbiome and expounds the innate immune defense mechanism of the maternal vagina and decidua as well as how cytotrophoblasts and syncytiotrophoblasts recognize and kill bacteria in the placenta. Fetal immune systems, thought to be weak, also exhibit an immune defense function that is indispensable for maintaining the safety of the fetus. The skin, lungs, and intestines of the fetus during pregnancy constitute the main immune barriers. These findings will provide a new understanding of the effects of normal microbial flora and how the host resists harmful microbes during pregnancy. We believe that it may also contribute to the reference on the clinical prevention and treatment of gestational infection to avoid adverse pregnancy outcomes.

Lactobacillus iners Is Associated with Vaginal Dysbiosis in Healthy Pregnant Women: A Preliminary Study

Vaginal dysbiosis has been identified to be associated with adverse pregnancy outcomes, such as preterm delivery and premature rupture of membranes. However, the overall structure and composition of vaginal microbiota in different trimesters of the pregnant women has not been fully elucidated. In this study, the physiological changes of the vaginal microbiota in healthy pregnant women were investigated. A total of 83 healthy pregnant participants were enrolled, who are in the first, second, or third pregnancy trimester. Quantitative real-time PCR was used to explore the abundant bacteria in the vaginal microbiota. No significant difference in the abundance of Gardnerella, Atopobium, Megasphaera, Eggerthella, Leptotrichia/Sneathia, or Prevotella was found among different trimesters, except Lactobacillus. Compared with the first pregnancy trimester, the abundance of L. iners decreased in the second and third trimester while the abundance of L. crispatus was increased in the second trimester. Moreover, we also found that vaginal cleanliness is correlated with the present of Lactobacillus, Atopobium, and Prevotella and leukocyte esterase is associated with Lactobacillus, Atopobium, Gardnerella, Eggerthella, Leptotrichia/Sneathia, and Prevotella. For those whose vaginal cleanliness raised or leukocyte esterase became positive, the richness of L. iners increased, while that of L. crispatus decreased significantly. Our present data indicated that the altered vaginal microbiota, mainly Lactobacillus, could be observed among different trimesters of pregnancy and L. iners could be considered as a potential bacterial marker for evaluating vaginal cleanliness and leukocyte esterase.

Medroxyprogesterone acetate alters the vaginal microbiota and microenvironment in women and increases susceptibility to HIV-1 in humanized mice

The hormonal contraceptive medroxyprogesterone acetate (MPA) is associated with increased risk of human immunodeficiency virus (HIV), via incompletely understood mechanisms. Increased diversity in the vaginal microbiota modulates genital inflammation and is associated with increased HIV-1 acquisition. However, the effect of MPA on diversity of the vaginal microbiota is relatively unknown. In a cohort of female Kenyan sex workers, negative for sexually transmitted infections (STIs), with Nugent scores <7 (N=58 of 370 screened), MPA correlated with significantly increased diversity of the vaginal microbiota as assessed by 16S rRNA gene sequencing. MPA was also significantly associated with decreased levels of estrogen in the plasma, and low vaginal glycogen and α-amylase, factors implicated in vaginal colonization by lactobacilli, bacteria that are believed to protect against STIs. In a humanized mouse model, MPA treatment was associated with low serum estrogen, low glycogen and enhanced HIV-1 susceptibility. The mechanism by which the MPA-mediated changes in the vaginal microbiota may contribute to HIV-1 susceptibility in humans appears to be independent of inflammatory cytokines and/or activated T cells. Altogether, these results suggest MPA-induced hypo-estrogenism may alter key metabolic components that are necessary for vaginal colonization by certain bacterial species including lactobacilli, and allow for greater bacterial diversity in the vaginal microbiota.

This article has an associated First Person interview with the first author of the paper.

Summary: MPA may increase susceptibility to HIV-1 in sex workers through the suppression of endogenous estrogen, reducing vaginal glycogen and α-amylase levels, which increases bacterial diversity, potentially reducing protective bacterial species such as lactobacilli.

Protective Effect of Probiotic Bacteria and Estrogen in Preventing HIV-1-Mediated Impairment of Epithelial Barrier Integrity in Female Genital Tract

Approximately 40% of global HIV-1 transmission occurs in the female genital tract (FGT) through heterosexual transmission. Epithelial cells lining the FGT provide the first barrier to HIV-1 entry. Previous studies have suggested that certain hormonal contraceptives or a dysbiosis of the vaginal microbiota can enhance HIV-1 acquisition in the FGT. We examined the effects of lactobacilli and female sex hormones on the barrier functions and innate immune responses of primary endometrial genital epithelial cells (GECs). Two probiotic strains, Lactobacillus reuteri RC-14 and L. rhamnosus GR-1, were tested, as were sex hormones estrogen (E2), progesterone (P4), and the hormonal contraceptive medroxyprogesterone acetate (MPA). Our results demonstrate that probiotic lactobacilli enhance barrier function without affecting cytokines. Treatment of GECs with MPA resulted in reduced barrier function. In contrast, E2 treatment enhanced barrier function and reduced production of proinflammatory cytokines. Comparison of hormones plus lactobacilli as a pre-treatment prior to HIV exposure revealed a dominant effect of lactobacilli in preventing loss of barrier function by GECs. In summary, the combination of E2 and lactobacilli had the best protective effect against HIV-1 seen by enhancement of barrier function and reduction in proinflammatory cytokines. These studies provide insights into how probiotic lactobacilli in the female genital microenvironment can alter HIV-1-mediated barrier disruption and how the combination of E2 and lactobacilli may decrease susceptibility to primary HIV infection.

Immunopathology of Recurrent Vulvovaginal Infections: New Aspects and Research Directions

Recurrent vulvovaginal infections (RVVI), a devastating group of mucosal infection, are severely affecting women's quality of life. Our understanding of the vaginal defense mechanisms have broadened recently with studies uncovering the inflammatory nature of bacterial vaginosis, inflammatory responses against novel virulence factors, innate Type 17 cells/IL-17 axis, neutrophils mediated killing of pathogens by a novel mechanism, and oxidative stress during vaginal infections. However, the pathogens have fine mechanisms to subvert or manipulate the host immune responses, hijack them and use them for their own advantage. The odds of hijacking increases, due to impaired immune responses, the net magnitude of which is the result of numerous genetic variations, present in multiple host genes, detailed in this review. Thus, by underlining the role of the host immune responses in disease etiology, modern research has clarified a major hypothesis shift in the pathophilosophy of RVVI. This knowledge can further be used to develop efficient immune-based diagnosis and treatment strategies for this enigmatic disease conditions. As for instance, plasma-derived MBL replacement, adoptive T-cell, and antibody-based therapies have been reported to be safe and efficacious in infectious diseases. Therefore, these emerging immune-therapies could possibly be the future therapeutic options for RVVI.

The Host-Microbe Interplay in Human Papillomavirus-Induced Carcinogenesis

Every year nearly half a million new cases of cervix cancer are diagnosed worldwide, making this malignancy the fourth commonest cancer in women. In 2018, more than 270,000 women died of cervix cancer globally with 85% of them being from developing countries. The majority of these cancers are caused by the infection with carcinogenic strains of human papillomavirus (HPV), which is also causally implicated in the development of other malignancies, including cancer of the anus, penis cancer and head and neck cancer. HPV is by far the most common sexually transmitted infection worldwide, however, most infected people do not develop cancer and do not even have a persistent infection. The development of highly effective HPV vaccines against most common high-risk HPV strains is a great medical achievement of the 21st century that could prevent up to 90% of cervix cancers. In this article, we review the current understanding of the balanced virus-host interaction that can lead to either virus elimination or the establishment of persistent infection and ultimately malignant transformation. We also highlight the influence of certain factors inherent to the host, including the immune status, genetic variants and the coexistence of other microbe infections and microbiome composition in the dynamic of HPV infection induced carcinogenesis.

Associations between vaginal bacteria implicated in HIV acquisition risk and proinflammatory cytokines and chemokines

OBJECTIVES

Recent studies have identified vaginal bacterial taxa associated with increased HIV risk. A possible mechanism to explain these results is that individual taxa differentially promote cervicovaginal inflammation. This study aimed to explore relationships between concentrations of bacteria previously linked to HIV acquisition and vaginal concentrations of proinflammatory cytokines and chemokines.

METHODS

In this cross-sectional analysis, concentrations of 17 bacterial taxa and four proinflammatory cytokines (interleukin (IL)-1β, IL-6, IL-10 and tumour necrosis factor alpha (TNFα)) and two proinflammatory chemokines (IL-8 and interferon gamma-induced protein 10) were measured in vaginal swabs collected from 80 HIV-uninfected women. Cytokine and chemokine concentrations were compared between women with bacterial concentrations above or below the lower limit of detection as determined by quantitative PCR for each taxon. Principal component analysis was used to create a summary score for closely correlated bacteria, and linear regression analysis was used to evaluate associations between this score and increasing concentrations of TNFα and IL-1β.

RESULTS

Detection of Dialister micraerophilus (p=0.01), Eggerthella sp type 1 (p=0.05) or Mycoplasma hominis (p=0.03) was associated with higher TNFα concentrations, and detection of D. micraerophilus (p<0.01), Eggerthella sp type 1 (p=0.04), M. hominis (p=0.02) or Parvimonas sp type 2 (p=0.05) was associated with significantly higher IL-1β concentrations. Seven bacterial taxa (D. micraerophilus, Eggerthella sp type 1, Gemella asaccharolytica, Sneathia sp, Megasphaera sp, M. hominis and Parvimonas sp type 2) were found to be highly correlated by principal component analysis (eigenvalue 5.24, explaining 74.92% of variability). Linear regression analysis demonstrated associations between this principal component and concentrations of TNFα (β=0.55, 95% CI 0.01 to 1.08; p=0.048) and IL-1β (β=0.96, 95% CI 0.19 to 1.74; p=0.016).

CONCLUSIONS

This study provides evidence that several highly correlated vaginal bacterial taxa may influence vaginal cytokine and chemokine concentrations. These results suggest a mechanism where the presence of specific bacterial taxa could influence HIV susceptibility by increasing vaginal inflammation.

Deciphering the complex interplay between microbiota, HPV, inflammation and cancer through cervicovaginal metabolic profiling

BACKGROUND

Dysbiotic vaginal microbiota have been implicated as contributors to persistent HPV-mediated cervical carcinogenesis and genital inflammation with mechanisms unknown. Given that cancer is a metabolic disease, metabolic profiling of the cervicovaginal microenvironment has the potential to reveal the functional interplay between the host and microbes in HPV persistence and progression to cancer.

METHODS

Our study design included HPV-negative/positive controls, women with low-grade and high-grade cervical dysplasia, or cervical cancer (n = 78). Metabolic fingerprints were profiled using liquid chromatography-mass spectrometry. Vaginal microbiota and genital inflammation were analysed using 16S rRNA gene sequencing and immunoassays, respectively. We used an integrative bioinformatic pipeline to reveal host and microbe contributions to the metabolome and to comprehensively assess the link between HPV, microbiota, inflammation and cervical disease.

FINDINGS

Metabolic analysis yielded 475 metabolites with known identities. Unique metabolic fingerprints discriminated patient groups from healthy controls. Three-hydroxybutyrate, eicosenoate, and oleate/vaccenate discriminated (with excellent capacity) between cancer patients versus the healthy participants. Sphingolipids, plasmalogens, and linoleate positively correlated with genital inflammation. Non-Lactobacillus dominant communities, particularly in high-grade dysplasia, perturbed amino acid and nucleotide metabolisms. Adenosine and cytosine correlated positively with Lactobacillus abundance and negatively with genital inflammation. Glycochenodeoxycholate and carnitine metabolisms connected non-Lactobacillus dominance to genital inflammation.

INTERPRETATION

Cervicovaginal metabolic profiles were driven by cancer followed by genital inflammation, HPV infection, and vaginal microbiota. This study provides evidence for metabolite-driven complex host-microbe interactions as hallmarks of cervical cancer with future translational potential. FUND: Flinn Foundation (#1974), Banner Foundation Obstetrics/Gynecology, and NIH NCI (P30-CA023074).

Defining characteristics of genital health in South African adolescent girls and young women at high risk for HIV infection

The genital tract of African women has been shown to differ from what is currently accepted as ‘normal’, defined by a pH≤4.5 and lactobacilli-dominated microbiota. Adolescent girls and young women (AGYW) from sub-Saharan Africa are at high risk for HIV, and we hypothesized that specific biological factors are likely to be influential. This study aimed to compare characteristics of vaginal health in HIV-negative AGYW (16-22-years-old), from two South African communities, to international norms. We measured plasma hormones, vaginal pH, presence of BV (Nugent scoring), sexually transmitted infections (multiplex PCR for Chlamydia trachomatis, Neisseria gonorrhoea, Trichomonas vaginalis, Mycoplasma genitalium) and candidiasis (Gram stain) in AGYW (n = 298) from Cape Town and Soweto. Cervicovaginal microbiota was determined by 16S pyrosequencing; 44 genital cytokines were measured by Luminex; and cervical T-cell activation/proliferation (CCR5, HLA-DR, CD38, Ki67) was measured by multiparametric flow cytometry. 90/298 (30.2%) AGYW were negative for BV, candidiasis and bacterial STIs. L. crispatus and L. iners were the dominant bacteria in cervicovaginal swabs, and the median vaginal pH was 4.7. AGYW with L. crispatus-dominant microbiota (42.4%) generally had the lowest cytokine concentrations compared to women with more diverse microbiota (34/44 significantly upregulated cytokines). Frequencies of CCR5+CD4⁺ T-cells co-expressing CD38 and HLA-DR correlated positively with interleukin (IL)-6, TNF-α, GRO-α, macrophage inflammatory protein (MIP)-1α, and IL-9. While endogenous oestrogen had an immune-dampening effect on IL-6, TNF-related apoptosis-inducing ligand (TRAIL) and IL-16, injectable hormone contraceptives (DMPA and Net-EN) were associated with significantly lower endogenous hormone concentrations (p<0.0001 for oestrogen and progesterone) and upregulation of 34/44 cytokines. Since genital inflammation and the presence of activated CD4+ T cells in the genital tract have been implicated in increased HIV risk in South African women, the observed high levels of genital cellular activation and cytokines from AGYW may point towards biological factors increasing HIV risk in this region.

Ecological dynamics of the vaginal microbiome in relation to health and disease

The bacterial composition of the vaginal microbiome is thought to be related to health and disease states of women. This microbiome is particularly dynamic, with compositional changes related to pregnancy, menstruation, and disease states such as bacterial vaginosis. In order to understand these dynamics and their impact on health and disease, ecological theories have been introduced to study the complex interactions between the many taxa in the vaginal bacterial ecosystem. The goal of this review is to introduce the ecological principles that are used in the study of the vaginal microbiome and its dynamics, and to review the application of ecology to vaginal microbial communities with respect to health and disease. Although applications of vaginal microbiome analysis and modulation have not yet been introduced into the routine clinical setting, a deeper understanding of its dynamics has the potential to facilitate development of future practices, for example in the context of postmenopausal vaginal symptoms, stratifying risk for obstetric complications, and controlling sexually transmitted infections.

Interaction of Gardnerella vaginalis and Vaginolysin with the Apical versus Basolateral Face of a Three-Dimensional Model of Vaginal Epithelium

Studies have implicated Gardnerella vaginalis as an important etiological agent in bacterial vaginosis (BV). It produces a cholesterol-dependent cytolysin, vaginolysin (VLY). In this study, we sought to characterize the interaction between vaginal epithelium, G. vaginalis, and VLY using EpiVaginal tissues from MatTek. These tissues are three-dimensional and have distinct apical and basolateral sides, enabling comparison of the effects of G. vaginalis and VLY following exposure to either side. We measured cytotoxicity, cytokine production, and bacterial growth, following apical versus basolateral exposure. G. vaginalis exhibited more-rapid growth in coculture with the tissue model when it was exposed to the apical side. VLY permeabilized cells on the basolateral side of the tissues but failed to permeabilize apical epithelial cells. Cytokine secretion in response to VLY and G. vaginalis also depended on the polarity of exposure. VLY did not cause significant changes in cytokine levels when exposed apically. Apical tissue challenge by G. vaginalis appeared to dampen the inflammatory response, as decreases in granulocyte-macrophage colony-stimulating factor (GM-CSF) (6.6-fold), RANTES (14.8-fold), and interferon gamma inducible protein 10 kDa (IP-10) (53-fold) and an increase in interleukin-1 receptor antagonist (IL-1ra) (5-fold) were observed. In vivo, G. vaginalis normally colonizes the apical face of the vaginal epithelium. Results from this study suggest that while G. vaginalis may grow on the apical face of the vaginal epithelium, its VLY toxin does not target these cells in this model. This phenomenon could have important implications regarding colonization of the vagina by G. vaginalis and may suggest an explanation for the lack of an overt immune response to this organism.

Diversity of vaginal microbiota in sub-Saharan Africa and its effects on HIV transmission and prevention

The vaginal microbial community ("microbiota") is a key component of the reproductive health of women, providing protection against urogenital infections. In sub-Saharan Africa, there is a high prevalence of bacterial vaginosis, a condition defined by bacterial overgrowth and a shift away from a Lactobacillus-dominated profile toward increased percentages of strict anaerobic species. Bacterial vaginosis is associated with an increased risk of HIV acquisition and transmission, as well as an increased risk of acquiring other sexually transmitted infections, preterm births, and pelvic inflammatory disease. Vaginal microbiota, rich in taxa of strict anaerobic species, disrupts the mucosal epithelial barrier through secretion of metabolites and enzymes that mediate inflammation. Advancements in next-generation sequencing technologies such as whole-genome sequencing have led to deeper profiling of the vaginal microbiome and further study of its potential role in HIV pathogenesis and treatment. Until recently data on the composition of the vaginal microbiome in sub-Saharan Africa have been limited; however, a number of studies have been published that highlight the critical role of vaginal microbiota in disease and health in African women. This article reviews these recent findings and identifies gaps in knowledge about variations in female genital commensal bacteria that could provide vital information to improve the effectiveness of interventions to prevent HIV and other sexually transmitted infections. In addition, we review the effects of pregnancy, contraception, and sexual practices on vaginal microbiome and the potential of vaginal microbiota on HIV transmission and prevention. A better understanding of the role of vaginal microbiota in host susceptibility to HIV infection and its prevention among African women could inform the development of novel local and systemic interventions to minimize new HIV infections among high-risk women.

The role of the microbiota in infectious diseases

The human body is colonized by a diverse community of microorganisms collectively referred to as the microbiota. Here, we describe how the human microbiota influences susceptibility to infectious diseases using examples from the respiratory, gastrointestinal and female reproductive tract. We will discuss how interactions between the host, the indigenous microbiota and non-native microorganisms, including bacteria, viruses and fungi, can alter the outcome of infections. This Review Article will highlight the complex mechanisms by which the microbiota mediates colonization resistance, both directly and indirectly, against infectious agents. Strategies for the therapeutic modulation of the microbiota to prevent or treat infectious diseases will be discussed, and we will review potential therapies that directly target the microbiota, including prebiotics, probiotics, synbiotics and faecal microbiota transplantation.

Innate immune components affect growth and virulence traits of bacterial-vaginosis-associated and non-bacterial-vaginosis-associated Gardnerella vaginalis strains similarly

Mucosal surfaces of the female reproductive tract contain a variety of antimicrobial components that provide the first line of defense against bacteria involved in the development of bacterial vaginosis (BV). Microbiological analysis of BV has shown Gardnerella vaginalis to be a prominent species in BV development. However, G. vaginalis colonization does not always lead to BV. Over the last decade, phenotypic and genotypic studies have demonstrated the existence of strain variants. Therefore, this study aimed to investigate if the major components of the vaginal immune response, specifically lysozyme, lactoferrin and β-defensin 2, differently affected virulence traits of G. vaginalis strains isolated from healthy women or from women with BV. Gardnerella vaginalis strains were first genotyped by the clade classification system and then phenotypically characterized. Our results revealed that key differences in initial adhesion existed among the isolates but that these differences could not be predicted using the clade-genotyping approach. Importantly, we found that growth, initial adhesion and biofilm formation were strongly affected by lysozymes, but at similar levels in both groups, suggesting that the response to host immune components is not a distinguishing characteristic of isolates from women with BV versus those from healthy women.

Modeling Host-Pathogen Interactions in the Context of the Microenvironment: Three-Dimensional Cell Culture Comes of Age

Tissues and organs provide the structural and biochemical landscapes upon which microbial pathogens and commensals function to regulate health and disease. While flat two-dimensional (2-D) monolayers composed of a single cell type have provided important insight into understanding host-pathogen interactions and infectious disease mechanisms, these reductionist models lack many essential features present in the native host microenvironment that are known to regulate infection, including three-dimensional (3-D) architecture, multicellular complexity, commensal microbiota, gas exchange and nutrient gradients, and physiologically relevant biomechanical forces (e.g., fluid shear, stretch, compression). A major challenge in tissue engineering for infectious disease research is recreating this dynamic 3-D microenvironment (biological, chemical, and physical/mechanical) to more accurately model the initiation and progression of host-pathogen interactions in the laboratory. Here we review selected 3-D models of human intestinal mucosa, which represent a major portal of entry for infectious pathogens and an important niche for commensal microbiota. We highlight seminal studies that have used these models to interrogate host-pathogen interactions and infectious disease mechanisms, and we present this literature in the appropriate historical context. Models discussed include 3-D organotypic cultures engineered in the rotating wall vessel (RWV) bioreactor, extracellular matrix (ECM)-embedded/organoid models, and organ-on-a-chip (OAC) models. Collectively, these technologies provide a more physiologically relevant and predictive framework for investigating infectious disease mechanisms and antimicrobial therapies at the intersection of the host, microbe, and their local microenvironments.

Common Cervicovaginal Microbial Supernatants Alter Cervical Epithelial Function: Mechanisms by Which Lactobacillus crispatus Contributes to Cervical Health

Cervicovaginal (CV) microbiota is associated with vaginal health and disease in non-pregnant women. Recent studies in pregnant women suggest that specific CV microbes are associated with preterm birth (PTB). While the associations between CV microbiota and adverse outcomes have been demonstrated, the mechanisms regulating the associations remain unclear. As the CV space contains an epithelial barrier, we postulate that CV microbiota can alter the epithelial barrier function. We investigated the biological, molecular, and epigenetic effects of Lactobacillus crispatus, Lactobacillus iners, and Gardnerella vaginalis on the cervical epithelial barrier function and determined whether L. crispatus mitigates the effects of lipopolysaccharide (LPS) and G. vaginalis on the cervical epithelial barrier as a possible mechanism by which CV microbiota mitigates disease risk. Ectocervical and endocervical cells treated with L. crispatus, L. iners, and G. vaginalis bacteria-free supernatants alone or combined were used to measure cell permeability, adherens junction proteins, inflammatory mediators, and miRNAs. Ectocervical and endocervical permeability increased after L. iners and G. vaginalis exposure. Soluble epithelial cadherin increased after exposure to L. iners but not G. vaginalis or L. crispatus. A Luminex cytokine/chemokine panel revealed increased proinflammatory mediators in all three bacteria-free supernatants with L. iners and G. vaginalis having more diverse inflammatory effects. L. iners and G. vaginalis altered the expression of cervical-, microbial-, and inflammatory-associated miRNAs. L. crispatus mitigated the LPS or G. vaginalis-induced disruption of the cervical epithelial barrier and reversed the G. vaginalis-mediated increase in miRNA expression. G. vaginalis colonization of the CV space of a pregnant C57/B6 mouse resulted in 100% PTB. These findings demonstrate that L. iners and G. vaginalis alter the cervical epithelial barrier by regulating adherens junction proteins, cervical immune responses, and miRNA expressions. These results provide evidence that L. crispatus confers protection to the cervical epithelial barrier by mitigating LPS- or G. vaginalis-induced miRNAs associated with cervical remodeling, inflammation, and PTB. This study provides further evidence that the CV microbiota plays a role in cervical function by altering the cervical epithelial barrier and initiating PTB. Thus, targeting the CV microbiota and/or its effects on the cervical epithelium may be a potential therapeutic strategy to prevent PTB.

The relationship between sex hormones, the vaginal microbiome and immunity in HIV-1 susceptibility in women

The role of sex hormones in regulating immune responses in the female genital tract has been recognized for decades. More recently, it has become increasingly clear that sex hormones regulate susceptibility to sexually transmitted infections through direct and indirect mechanisms involving inflammation and immune responses. The reproductive cycle can influence simian/human immunodeficiency virus (SHIV) infections in primates and HIV-1 infection in ex vivo cervical tissues from women. Exogenous hormones, such as those found in hormonal contraceptives, have come under intense scrutiny because of the increased susceptibility to sexually transmitted infections seen in women using medroxyprogesterone acetate, a synthetic progestin-based contraceptive. Recent meta-analyses concluded that medroxyprogesterone acetate enhanced HIV-1 susceptibility in women by 40%. In contrast, estradiol-containing hormonal contraceptives were not associated with increased susceptibility and some studies reported a protective effect of estrogen on HIV/SIV infection, although the underlying mechanisms remain incompletely understood. Recent studies describe a key role for the vaginal microbiota in determining susceptibility to sexually transmitted infections, including HIV-1. While Lactobacillus spp.-dominated vaginal microbiota is associated with decreased susceptibility, complex microbiota, such as those seen in bacterial vaginosis, correlates with increased susceptibility to HIV-1. Interestingly, sex hormones are inherently linked to microbiota regulation in the vaginal tract. Estrogen has been postulated to play a key role in establishing a Lactobacillus-dominated microenvironment, whereas medroxyprogesterone acetate is linked to hypo-estrogenic effects. The aim of this Review is to contribute to a better understanding of the sex-hormone-microbiome-immunity axis, which can provide key information on the determinants of HIV-1 susceptibility in the female genital tract and, consequently, inform HIV-1 prevention strategies.

Assessment of microbiota:host interactions at the vaginal mucosa interface

There is increasing appreciation of the role that vaginal microbiota play in health and disease throughout a woman's lifespan. This has been driven partly by molecular techniques that enable detailed identification and characterisation of microbial community structures. However, these methods do not enable assessment of the biochemical and immunological interactions between host and vaginal microbiota involved in pathophysiology. This review examines our current knowledge of the relationships that exist between vaginal microbiota and the host at the level of the vaginal mucosal interface. We also consider methodological approaches to microbiomic, immunologic and metabolic profiling that permit assessment of these interactions. Integration of information derived from these platforms brings the potential for biomarker discovery, disease risk stratification and improved understanding of the mechanisms regulating vaginal microbial community dynamics in health and disease.

Uterine Microbiota: Residents, Tourists, or Invaders?

Uterine microbiota have been reported under various conditions and populations; however, it is uncertain the level to which these bacteria are residents that maintain homeostasis, tourists that are readily eliminated or invaders that contribute to human disease. This review provides a historical timeline and summarizes the current status of this topic with the aim of promoting research priorities and discussion on this controversial topic. Discrepancies exist in current reports of uterine microbiota and are critically reviewed and examined. Established and putative routes of bacterial seeding of the human uterus and interactions with distal mucosal sites are discussed. Based upon the current literature, we highlight the need for additional robust clinical and translational studies in this area. In addition, we discuss the necessity for investigating host–microbiota interactions and the physiologic and functional impact of these microbiota on the local endometrial microenvironment as these mechanisms may influence poor reproductive, obstetric, and gynecologic health outcomes and sequelae.

Lipopolysaccharide and cAMP modify placental calcitriol biosynthesis reducing antimicrobial peptides gene expression

PROBLEM

Calcitriol, the hormonal form of vitamin D₃ (VD), stimulates placental antimicrobial peptides expression; nonetheless, the regulation of calcitriol biosynthesis in the presence of bacterial products and its consequence on placental innate immunity have scarcely been addressed.

METHOD OF STUDY

We investigated how some bacterial products modify placental VD metabolism and its ability to induce antimicrobial peptides gene expression.

RESULTS

Cultured human trophoblasts biosynthesized calcitriol only in the presence of its precursor calcidiol, a process that was inhibited by cyclic-AMP but stimulated by lipopolysaccharide (LPS). Intracrine calcitriol upregulated cathelicidin, S100A9, and β-defensins (HBDs) gene expression, while LPS further stimulated HBD2 and S100A9. Unexpectedly, LPS significantly repressed cathelicidin basal mRNA levels and drastically diminished calcidiol ability to induce it. Meanwhile, cyclic-AMP, which is used by many microbes to avoid host defenses, suppressed calcitriol biosynthesis, resulting in significant inhibition of most VD-dependent microbicidal peptides gene expression.

CONCLUSION

While LPS stimulated calcitriol biosynthesis, cyclic-AMP inhibited it. LPS downregulated cathelicidin mRNA expression, whereas cyclic-AMP antagonized VD-dependent-upregulation of most antimicrobial peptides. These findings reveal LPS and cyclic-AMP involvement in dampening placental innate immunity, highlighting the importance of cyclic-AMP in the context of placental infection and suggesting its participation to facilitate bacterial survival.

Alterations in the gut microbiota of patients with acquired immune deficiency syndrome

Acquired immune deficiency syndrome (AIDS), caused by infection with human immunodeficiency virus (HIV), is associated with gastrointestinal disease, systemic immune activation and changes in the gut microbiota. Here, we aim to investigate the gut microbiota patterns of HIV‐infected individuals and HIV‐uninfected individuals in populations from South China. We enrolled 33 patients with HIV (14 participants treated with highly active antiretroviral therapy [HAART] for more than 3 months; the remaining 19 individuals had not received treatment) and 35 healthy controls (HC) for a cross‐sectional comparison of gut microbiota using stool samples. Gut microbial communities were profiled by sequencing the bacterial 16S rRNA genes. Dysbiosis was more common among patients with AIDS compared with healthy individuals. Dysbiosis was characterized by decreased α‐diversity, low mean counts of Bacteroidetes, Faecalibacterium, Prevotella, Bacteroides vulgatus, Dialister and Roseburia inulnivorans, and high mean counts of Proteobacteria, Enterococcus, Streptococcus, Lactobacillus, Lachnociostridium, Ruminococcus gnavus and Streptococcus vestibularis. Increased abundance of Bacilli was observed in homosexual patients. Proteobacteria were higher among heterosexual patients with HIV infections. Tenericutes were higher among patients with history of intravenous drug abuse. Restoration of gut microbiota diversity and a significant increase in abundance of Faecalibacterium, Blautia and Bacteroides were found in patients receiving HAART compared to those who did not receive. HIV infection‐associated dysbiosis is characterized by decreased levels of α‐diversity and Bacteroidetes, increased levels of Proteobacteria and the alterations of gut microbiota correlate with the route of HIV transmission. The imbalanced faecal microbiota of HIV infection is partially restored after therapy.

Hormonal Contraception and HIV-1 Acquisition: Biological Mechanisms

Access to effective affordable contraception is critical for individual and public health. A wide range of hormonal contraceptives (HCs), which differ in composition, concentration of the progestin component, frequency of dosage, and method of administration, is currently available globally. However, the options are rather limited in settings with restricted economic resources that frequently overlap with areas of high HIV-1 prevalence. The predominant contraceptive used in sub-Saharan Africa is the progestin-only three-monthly injectable depot medroxyprogesterone acetate. Determination of whether HCs affect HIV-1 acquisition has been hampered by behavioral differences potentially confounding clinical observational data. Meta-analysis of these studies shows a significant association between depot medroxyprogesterone acetate use and increased risk of HIV-1 acquisition, raising important concerns. No association was found for combined oral contraceptives containing levonorgestrel, nor for the two-monthly injectable contraceptive norethisterone enanthate, although data for norethisterone enanthate are limited. Susceptibility to HIV-1 and other sexually transmitted infections may, however, be dependent on the type of progestin present in the formulation. Several underlying biological mechanisms that may mediate the effect of HCs on HIV-1 and other sexually transmitted infection acquisition have been identified in clinical, animal, and ex vivo studies. A substantial gap exists in the translation of basic research into clinical practice and public health policy. To bridge this gap, we review the current knowledge of underlying mechanisms and biological effects of commonly used progestins. The review sheds light on issues critical for an informed choice of progestins for the identification of safe, effective, acceptable, and affordable contraceptive methods.

Toll-like receptor variants and cervical Atopobium vaginae infection in women with pelvic inflammatory disease

PROBLEM

Toll-like (TLR) receptor genetic variants have been implicated in bacterial vaginosis (BV). We determined whether TLR variants are associated with fastidious BV-associated microbes that are linked with infertility following pelvic inflammatory disease (PID).

METHOD OF STUDY

Sneathia spp., Atopobium vaginae, BVAB1, and Ureaplasma urealyticum were measured in 250 women from the PID Evaluation and Clinical Health (PEACH) study. Relative risk (RR) and 95% confidence intervals (CI) were calculated adjusting for chlamydia and gonorrhea. Principal component analysis was used to adjust for population stratification. A false discovery rate q-value of 0.05 was significant.

RESULTS

TLR2-1733C>A (P = .003) and TLR2-616A>G (P = .004) were associated with cervical A. vaginae. TLR2-1733C>A and TLR6-438C>T were associated with A. vaginae detection in the endometrium, but this was not significant after adjustment for multiple comparisons (FDR q-value = 0.06).

CONCLUSION

Host gene variants in TLR2 signaling pathways were modestly associated with cervical A. vaginae in women with clinical PID.

The Role of Skin and Orogenital Microbiota in Protective Immunity and Chronic Immune-Mediated Inflammatory Disease

The skin and orogenital mucosae, which constitute complex protective barriers against infection and injuries, are not only the first to come into contact with pathogens but are also colonized by a set of microorganisms that are essential to maintain a healthy physiological environment. Using 16S ribosomal RNA metagenomic sequencing, scientists recognized that the microorganism colonization has greater diversity and variability than previously assumed. These microorganisms, such as commensal bacteria, affect the host’s immune response against pathogens and modulate chronic inflammatory responses. Previously, a single pathogen was thought to cause a single disease, but current evidence suggests that dysbiosis of the tissue microbiota may underlie the disease status. Dysbiosis results in aberrant immune responses at the surface and furthermore, affects the systemic immune response. Hence, understanding the initial interaction between the barrier surface immune system and local microorganisms is important for understanding the overall systemic effects of the immune response. In this review, we describe current evidence for the basis of the interactions between pathogens, microbiota, and immune cells on surface barriers and offer explanations for how these interactions may lead to chronic inflammatory disorders.

The human female urogenital microbiome: complexity in normality

Microbial communities of the urogenital tract have long been recognised to play an important role in disease states. A revolution in methodological approaches is permitting the assessment of complex urogenital tract microbiota-host interactions and the metabolic and protein milieu of the mucosal interface. There is now great potential for significant advances in biomarker discovery and disease risk stratification, and for the elucidation of mechanisms underpinning the microbial community dynamics involved in urogenital tract pathology. Microbiota-host interactions in the female genital tract have a particular significance, because unlike in the male, there is direct communication between the external genitalia, the uterus and the peritoneal cavity. This review examines the microbial community composition at differing sites of the female urogenital tract and its relationship with health and disease. Key factors involved in the modulation of vaginal microbiome stability and structure, such as endocrine, immune and inflammatory pathways, are considered in the context of a woman's life cycle and disease pathogenesis.

Association of high-risk sexual behaviour with diversity of the vaginal microbiota and abundance of Lactobacillus

Objective

To compare the vaginal microbiota of women engaged in high-risk sexual behaviour (sex work) with women who are not engaged in high-risk sexual behaviour. Diverse vaginal microbiota, low in Lactobacillus species, like those in bacterial vaginosis (BV), are associated with increased prevalence of sexually transmitted infections (STIs) and human immunodeficiency virus (HIV) acquisition. Although high-risk sexual behaviour increases risk for STIs, the vaginal microbiota of sex workers is understudied.

Methods

A retrospective cross-sectional study was conducted comparing vaginal microbiota of women who are not engaged in sex work (non-sex worker controls, NSW, N = 19) and women engaged in sex work (female sex workers, FSW, N = 48), using Illumina sequencing (16S rRNA, V3 region).

Results

Bacterial richness and diversity were significantly less in controls, than FSW. Controls were more likely to have Lactobacillus as the most abundant genus (58% vs. 17%; P = 0.002) and composition of their vaginal microbiota differed from FSW (PERMANOVA, P = 0.001). Six microbiota clusters were detected, including a high diversity cluster with three sub-clusters, and 55% of women with low Nugent Scores fell within this cluster. High diversity was observed by 16S sequencing in FSW, regardless of Nugent Scores, suggesting that Nugent Score may not be capable of capturing the diversity present in the FSW vaginal microbiota.

Conclusions

High-risk sexual behaviour is associated with diversity of the vaginal microbiota and lack of Lactobacillus. These factors could contribute to increased risk of STIs and HIV in women engaged in high-risk sexual behaviour.

Vaginal lactic acid elicits an anti-inflammatory response from human cervicovaginal epithelial cells and inhibits production of pro-inflammatory mediators associated with HIV acquisition

Inflammation in the female reproductive tract (FRT) is associated with increased HIV transmission. Lactobacillus spp. dominate the vaginal microbiota of many women and their presence is associated with reduced HIV acquisition. Here we demonstrate that lactic acid (LA), a major organic acid metabolite produced by lactobacilli, mediates anti-inflammatory effects on human cervicovaginal epithelial cells. Treatment of human vaginal and cervical epithelial cell lines with LA (pH 3.9) elicited significant increases in the production of the anti-inflammatory cytokine IL-1RA. When added simultaneously or prior to stimulation, LA inhibited the Toll-like receptor agonist-elicited production of inflammatory mediators IL-6, IL-8, TNFα, RANTES, and MIP3α from epithelial cell lines and prevented IL-6 and IL-8 production by seminal plasma. The anti-inflammatory effect of LA was mediated by the protonated form present at pH≤3.86 and was observed with both L- and D-isomers. A similar anti-inflammatory effect of LA was observed in primary cervicovaginal cells and in an organotypic epithelial tissue model. These findings identify a novel property of LA that acts directly on epithelial cells to inhibit FRT inflammation and highlights the potential use of LA-containing agents in the lower FRT as adjuncts to female-initiated strategies to reduce HIV acquisition.

Social Influences on Prevotella and the Gut Microbiome of Young Monkeys

OBJECTIVE

Our aim was to evaluate the bacterial profiles of young monkeys as they were weaned into peer groups with a particular focus on Prevotella, an important taxon in both human and nonhuman primates. The weaning of infants and increased social contact with peers is a developmental stage that is likely to affect the gut microbiome.

METHODS

Gut bacteria were assessed in 63 rhesus monkeys living in social groups comprised of 4 to 7 individuals. Two groups were assessed prospectively on day 1 and 2 weeks after rehousing away from the mother and group formation. Ten additional groups were assessed at 2 weeks after group establishment. Fecal genomic DNA was extracted and 16S ribosomal RNA sequenced by Illumina MiSeq (5 social groups) and 454-amplicon pyrosequencing (7 social groups).

RESULTS

Combining weaned infants into small social groups led to a microbial convergence by 2 weeks (p < .001). Diversity analyses indicated more similar community structure within peer groups than across groups (p < .01). Prevotella was the predominant taxon, and its abundance differed markedly across individuals. Indices of richness, microbial profiles, and less abundant taxa were all associated with the Prevotella levels. Functional Kyoto Encyclopedia of Genes and Genomes analyses suggested corresponding shifts in metabolic pathways.

CONCLUSIONS

The formation of small groups of young rhesus monkeys was associated with significant shifts in the gut microbiota. The profiles were closely associated with the abundance of Prevotella, a predominant taxon in the rhesus monkey gut. Changes in the structure of the gut microbiome are likely to induce differences in metabolic and physiologic functioning.