Non-Lactobacillus-Dominant and Polymicrobial Vaginal Microbiomes Are More Common in Younger South African Women and Predictive of Increased Risk of Human Immunodeficiency Virus Acquisition.

BACKGROUND: Adolescent girls and young women aged 15‒24 years in sub-Saharan Africa are at disproportionate risk of human immunodeficiency virus (HIV) infection. Given the known association between vaginal microbial dysbiosis and HIV susceptibility, we performed an age-stratified analysis of the vaginal microbiome in South African women and compared this to their risk of HIV acquisition. METHODS: Vaginal microbiome data were generated by mass spectrometry-based proteomic analysis of cervicovaginal lavages collected from participants (n = 688) in the Centre for the AIDS Programme of Research in South Africa (CAPRISA) 004 trial. Participants were grouped by age (18-19 years, n = 93; 20-24 years, n = 326; 25-41 years, n = 269). RESULTS: Four microbiome types were identified based on predominant taxa, including Lactobacillus crispatus (CST-LC, 12.2%), Lactobacillus iners (CST-LI, 43.6%), Gardnerella vaginalis (CST-GV, 26.6%), or polymicrobial (CST-PM, 15.1%). Women aged 18-19 and 20-24 years had increased CST-PM and a non-Lactobacillus-dominant microbiome compared to those 25-41 years (odds ratio [OR], 3.14 [95% confidence interval {CI}, 1.12-7.87], P = .017; OR, 2.81 [95% CI, 1.07-7.09], P = .038, respectively; and OR, 1.65 [95% CI, 1.02-2.65], P = .028; OR, 1.40 [95% CI, 1.01-1.95], P = .030, respectively). The HIV incidence rate of women with CST-PM microbiome was 7.19-fold higher compared to women with CST-LC (hazard ratio [HR], 7.19 [95% CI, 2.11-24.5], P = .00162), which was also consistent in women aged 20-24 years (HR, 4.90 [95% CI, 1.10-21.9], P = .0375). CONCLUSIONS: Younger women were more likely to have a higher-risk polymicrobial microbiome suggesting that vaginal microbiota are contributing to increased HIV-1 susceptibility in this group. CLINICAL TRIALS REGISTRATION: NCT00441298.

Vaginal microbiome-hormonal contraceptive interactions associate with the mucosal proteome and HIV acquisition.

Alterations to the mucosal environment of the female genital tract, such as genital inflammation, have been associated with increased HIV acquisition in women. As the microbiome and hormonal contraceptives can affect vaginal mucosal immunity, we hypothesized these components may interact in the context of HIV susceptibility. Using previously published microbiome data from 685 women in the CAPRISA-004 trial, we compared relative risk of HIV acquisition in this cohort who were using injectable depot medroxyprogesterone acetate (DMPA), norethisterone enanthate (NET-EN), and combined oral contraceptives (COC). In women who were Lactobacillus-dominant, HIV acquisition was 3-fold higher in women using DMPA relative to women using NET-EN or COC (OR: 3.27; 95% CI: 1.24-11.24, P = 0.0305). This was not observed in non-Lactobacillus-dominant women (OR: 0.95, 95% CI: 0.44-2.15, P = 0.895) (interaction P = 0.0686). Higher serum MPA levels associated with increased molecular pathways of inflammation in the vaginal mucosal fluid of Lactobacillus-dominant women, but no differences were seen in non-Lactobacillus dominant women. This study provides data suggesting an interaction between the microbiome, hormonal contraceptives, and HIV susceptibility.

Increased genital mucosal cytokines in Canadian women associate with higher antigen-presenting cells, inflammatory metabolites, epithelial barrier disruption, and the depletion of L. crispatus.

BACKGROUND: Cervicovaginal inflammation has been linked to negative reproductive health outcomes including the acquisition of HIV, other sexually transmitted infections, and cervical carcinogenesis. While changes to the vaginal microbiome have been linked to genital inflammation, the molecular relationships between the functional components of the microbiome with cervical immunology in the reproductive tract are understudied, limiting our understanding of mucosal biology that may be important for reproductive health. RESULTS: In this study, we used a multi'-omics approach to profile cervicovaginal samples collected from 43 Canadian women to characterize host, immune, functional microbiome, and metabolome features of cervicovaginal inflammation. We demonstrate that inflammation is associated with lower amounts of L. crispatus and higher levels of cervical antigen-presenting cells (APCs). Proteomic analysis showed an upregulation of pathways related to neutrophil degranulation, complement, and leukocyte migration, with lower levels of cornified envelope and cell-cell adherens junctions. Functional microbiome analysis showed reductions in carbohydrate metabolism and lactic acid, with increases in xanthine and other metabolites. Bayesian network analysis linked L. crispatus with glycolytic and nucleotide metabolism, succinate and xanthine, and epithelial proteins SCEL and IVL as major molecular features associated with pro-inflammatory cytokines and increased APCs. CONCLUSIONS: This study identified key molecular and immunological relationships with cervicovaginal inflammation, including higher APCs, bacterial metabolism, and proteome alterations that underlie inflammation. As APCs are involved in HIV transmission, parturition, and cervical cancer progression, further studies are needed to explore the interactions between these cells, bacterial metabolism, mucosal immunity, and their relationship to reproductive health. Video Abstract.

Vaginal epithelial dysfunction is mediated by the microbiome, metabolome, and mTOR signaling.

Bacterial vaginosis (BV) is characterized by depletion of Lactobacillus and overgrowth of anaerobic and facultative bacteria, leading to increased mucosal inflammation, epithelial disruption, and poor reproductive health outcomes. However, the molecular mediators contributing to vaginal epithelial dysfunction are poorly understood. Here we utilize proteomic, transcriptomic, and metabolomic analyses to characterize biological features underlying BV in 405 African women and explore functional mechanisms in vitro. We identify five major vaginal microbiome groups: L. crispatus (21%), L. iners (18%), Lactobacillus (9%), Gardnerella (30%), and polymicrobial (22%). Using multi-omics we show that BV-associated epithelial disruption and mucosal inflammation link to the mammalian target of rapamycin (mTOR) pathway and associate with Gardnerella, M. mulieris, and specific metabolites including imidazole propionate. Experiments in vitro confirm that type strain G. vaginalis and M. mulieris supernatants and imidazole propionate directly affect epithelial barrier function and activation of mTOR pathways. These results find that the microbiome-mTOR axis is a central feature of epithelial dysfunction in BV.

An updated review on the effects of depot medroxyprogesterone acetate on the mucosal biology of the female genital tract.

BACKGROUND: Access to safe, effective, and affordable contraception is important for women's health and essential to mitigate maternal and fetal mortality rates. The progestin-based contraceptive depot medroxyprogesterone acetate (DMPA) is a popular contraceptive choice with a low failure rate and convenient administration schedule. AIM: In this review, we compiled observational data from human cohorts that examine how DMPA influences the mucosal biology of the female genital tract (FGT) that are essential in maintaining vaginal health, including resident immune cells, pro-inflammatory cytokines, epithelial barrier function, and the vaginal microbiome MATERIALS AND METHODS: This review focused on the recent published literature published in 2019 and 2020. RESULTS: Recent longitudinal studies show that DMPA use associates with an immunosuppressive phenotype, increase in CD4+CCR5+ T cells, and alterations to growth factors. In agreement with previous meta-analyses, DMPA use is associated with minimal effects of the composition of the vaginal microbiome. Cross-sectional studies associate a more pro-inflammatory relationship with DMPA, but these studies are confounded by inherent weaknesses of cross-sectional studies, including differences in study group sizes, behaviors, and other variables that may affect genital inflammation. DISCUSSION & CONCLUSION: These recent results indicate that the interactions between DMPA and the vaginal mucosa are complex emphasizing the need for comprehensive longitudinal studies that take into consideration the measurement of multiple biological parameters.

Endocervical Regulatory T Cells Are Associated With Decreased Genital Inflammation and Lower HIV Target Cell Abundance.

Regulatory T cells (Tregs) play important roles in tissue homeostasis, but few studies have investigated tissue Tregs in the context of genital inflammation, HIV target cell density, and vaginal microbiota in humans. In women from Nairobi (n=64), the proportion of CD4+ CD25+ CD127low Tregs in the endocervix correlated with those in blood (r=0.31, p=0.01), with a higher Treg frequency observed in the endocervix (median 3.8 vs 2.0%, p<0.0001). Most Tregs expressed FOXP3 in both compartments, and CTLA-4 expression was higher on endocervical Tregs compared to blood (median 50.8 vs 6.0%, p<0.0001). More than half (34/62, 55%) of participants displayed a non-Lactobacillus dominant vaginal microbiota, which was not associated with endocervical Tregs or CD4+ T cell abundance. In a multivariable linear regression, endocervical Treg proportions were inversely associated with the number of elevated pro-inflammatory cytokines (p=0.03). Inverse Treg associations were also observed for specific cytokines including IL-1ß, G-CSF, Eotaxin, IL-1RA, IL-8, and MIP-1 ß. Higher endocervical Treg proportions were associated with lower abundance of endocervical CD4+ T cells (0.30 log10 CD4+ T cells per log10 Treg, p=0.00028), with a similar trend for Th17 cells (p=0.09). Selectively increasing endocervical Tregs may represent a pathway to reduce genital tract inflammation in women.

Plasma concentration of injectable contraceptive correlates with reduced cervicovaginal growth factor expression in South African women.

Long-acting injectable contraceptives have been associated with mucosal immune changes and increased HIV acquisition, but studies have often been hampered by the inaccuracy of self-reported data, unknown timing of injection, and interactions with mucosal transmission co-factors. We used mass spectrometry to quantify the plasma concentrations of injectable contraceptives in women from the CAPRISA004 study (n = 664), with parallel quantification of 48 cytokines and >500 host proteins in cervicovaginal lavage. Higher DMPA levels were associated with reduced CVL concentrations of GCSF, MCSF, IL-16, CTACK, LIF, IL-1α, and SCGF-ß in adjusted linear mixed models. Dose-dependent relationships between DMPA concentration and genital cytokines were frequently observed. Unsupervised clustering of host proteins by DMPA concentration suggest that women with low DMPA had increases in proteins associated with mucosal fluid function, growth factors, and keratinization. Although DMPA was not broadly pro-inflammatory, DMPA was associated with increased IP-10 in HSV-2 seropositive and older women. DMPA-cytokine associations frequently differed by vaginal microbiome; in non-Lactobacillus-dominant women, DMPA was associated with elevated IL-8, MCP-1, and IP-10 concentrations. These data confirm a direct, concentration-dependant effect of DMPA on functionally important immune factors within the vaginal compartment. The biological effects of DMPA may vary depending on age, HSV-2 status, and vaginal microbiome composition.

Understanding mucosal and microbial functionality of the female reproductive tract by metaproteomics: Implications for HIV transmission.

The mucosal surface of the female genital tract contains physiological, immunological, and microbial components that collectively comprise a functioning "mucosal system" that is critical for reproductive health. Alterations or imbalances to any of these components can have significant consequences for susceptibility to sexually transmitted infections, such as HIV. In recent years the advent of advanced systems biology technologies, such as metaproteomics, has provided new toolsets to studying mucosal systems. Studies have linked an altered mucosal proteome to many HIV risk factors including mucosal inflammation, bacterial vaginosis, hormonal contraceptives, and reduced efficacy of antiretroviral drugs for HIV prevention. Herein we will discuss how metaproteomics has been used to study mucosal system components, including epithelial barriers, inflammation, and the microbiome, with a focus on what alterations may contribute to increased HIV transmission risk in women.

Vaginal bacteria modify HIV tenofovir microbicide efficacy in African women.

Antiretroviral-based strategies for HIV prevention have shown inconsistent results in women. We investigated whether vaginal microbiota modulated tenofovir gel microbicide efficacy in the CAPRISA (Centre for the AIDS Program of Research in South Africa) 004 trial. Two major vaginal bacterial community types-one dominated by Lactobacillus (59.2%) and the other where Gardnerella vaginalis predominated with other anaerobic bacteria (40.8%)-were identified in 688 women profiled. Tenofovir reduced HIV incidence by 61% (P = 0.013) in Lactobacillus-dominant women but only 18% (P = 0.644) in women with non-Lactobacillus bacteria, a threefold difference in efficacy. Detectible mucosal tenofovir was lower in non-Lactobacillus women, negatively correlating with G. vaginalis and other anaerobic bacteria, which depleted tenofovir by metabolism more rapidly than target cells convert to pharmacologically active drug. This study provides evidence linking vaginal bacteria to microbicide efficacy through tenofovir depletion via bacterial metabolism.