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The mechanism(s) by which bacterial communities impact susceptibility to infectious diseases, such as HIV, and maintain female genital tract (FGT) health are poorly understood. Evaluation of FGT bacteria has predominantly been limited to studies of species abundance, but not bacterial function. We therefore sought to examine the relationship of bacterial community composition and function with mucosal epithelial barrier health in the context of bacterial vaginosis (BV) using metaproteomic, metagenomic, and in vitro approaches. We found highly diverse bacterial communities dominated by Gardnerella vaginalis associated with host epithelial barrier disruption and enhanced immune activation, and low diversity communities dominated by Lactobacillus species that associated with lower Nugent scores, reduced pH, and expression of host mucosal proteins important for maintaining epithelial integrity. Importantly, proteomic signatures of disrupted epithelial integrity associated with G. vaginalis-dominated communities in the absence of clinical BV diagnosis. Because traditional clinical assessments did not capture this, it likely represents a larger underrepresented phenomenon in populations with high prevalence of G. vaginalis. We finally demonstrated that soluble products derived from G. vaginalis inhibited wound healing, while those derived from L. iners did not, providing insight into functional mechanisms by which FGT bacterial communities affect epithelial barrier integrity.

The cervicovaginal microbiome is a key biological determinant of human immunodeficiency virus (HIV) susceptibility, but its underlying impact on the ectocervical transcriptional landscape is unclear. Ectocervical tissue samples from Kenyan female sex workers were categorized into pre-defined cervicovaginal microbiome groups based on dominant compositions: Lactobacillus crispatus/acidophilus , Lactobacillus iners , Gardnerella , and ‘highly diverse’. The tissue samples (n = 21) were assessed using spatial transcriptomics, revealing three epithelial, one mixed border, and nine submucosal gene clusters. Differential gene expression analysis across the microbiome groups and gene clusters identified 3,771 unique genes. The highly diverse microbiome group associated with the largest differences, mostly located near the epithelial basal membrane, encompassing genes involved in epithelial maintenance, submucosal extracellular matrix structures, and immune function. The L. crispatus/acidophilus -dominated group was identified by genes involved in active immune engagement, supporting mucosal barrier integrity. Weighted gene co-expression analysis confirmed tissue-wide altered gene expression associated with all microbiome groups and with individual bacterial taxa. Despite the assumption that microbiome colonization is restricted to the luminal surface, the transcriptional landscape was affected throughout the mucosa, with the most pronounced effect near both sides of the basal membrane. This broad association with the mucosal barrier integrity could affect susceptibility to HIV acquisition.

The injectable contraceptive, depot medroxyprogesterone acetate (DMPA), is associated with compromised cervical mucosal barriers. High-resolution spatial transcriptomics is applied here to reveal the spatial localization of these altered molecular markers. Ectocervical tissue samples from Kenyan sex workers using DMPA, or non-hormonal contraceptives, underwent spatial transcriptomics and gene set enrichment analyses. Integrated systemic estradiol levels and bulk tissue gene expression data from a larger cohort enhanced the study’s scope. Unsupervised clustering unveiled four epithelial and seven submucosal layers, showcasing spatially restricted and diverse functional epithelial responses, and a less structured submucosal spatial ordering. DMPA associated with mucosal-wide immunoglobulin gene upregulation, verified by CD20 + B-cell immunostaining, and upregulated immune markers adjacent to the basal membrane. Downregulated genes represented spatially restricted disrupted epithelial barrier integrity and submucosal extracellular matrix dysfunction. The transcriptional profile was associated with markers of estrogen regulation. Collectively, our findings reveal estrogen-modulated distinct ectocervical transcriptional profiles associated with DMPA usage. While upregulation of immunoglobulin genes occurs throughout the mucosa, activation of innate immune responses and dysregulation of barrier integrity markers are spatially restricted. These results extend previous analyses using bulk transcriptomics and provide insights into the molecular landscape influenced by DMPA, shedding light on contraceptive effects and health implications.

Lichen sclerosus is a chronic inflammatory condition of unknown etiology that affects the genital and extragenital skin, which can lead to sexual dysfunction and has been associated with vulvar cancer. The vaginal microbiome has a critical role in gynecologic health, but little is known about the microbiome in lichen sclerosus. This study investigated the vaginal and vulvar microbiomes of 27 post-menopausal women with lichen sclerosus. The most abundant genera detected in the vaginal microbiome were Lactobacillus , Gardnerella , and Anaerococcus , while Lactobacillus, Anaerococcus , and Staphylococcus were the most abundant in the vulvar microbiome . The vaginal samples clustered into two main groups, Lactobacillus dominant (n = 6, > 50% microbiome Lactobacillus ) and polymicrobial (n = 21) with no dominant genus. The vulvar samples were mainly polymicrobial (n = 25). Actinomyces, Anaerococcus , and Ezakiella in the vaginal microbiome and Actinomyces and Ezakiella in the vulvar microbiome were significantly associated with lichen sclerosus symptoms (adjusted p  < 0.05). In this population of post-menopausal women with lichen sclerosus the majority have diverse, non- Lactobacillus dominant microbiomes, which is considered less optimal for gynecologic health based on studies of pre-menopausal women. Actinomyces, Ezakiella , and Anaerococcus were associated with lichen sclerosus symptoms. Understanding the role of these bacteria in lichen sclerosus pathogenesis will be an essential future investigation.

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.

Background Women with a cervicovaginal microbiota dominated by Lactobacillus spp. are at reduced risk of acquiring sexually transmitted infections including HIV, but the biological mechanisms involved remain poorly defined. Here, we performed metaproteomics on vaginal swab samples from young South African women ( n = 113) and transcriptomics analysis of cervicovaginal epithelial cell cultures to examine the ability of lactic acid, a metabolite produced by cervicovaginal lactobacilli, to modulate genital epithelial barrier function. Results Compared to women with Lactobacillus -depleted microbiota, women dominated by vaginal lactobacilli exhibit higher abundance of bacterial lactate dehydrogenase, a key enzyme responsible for lactic acid production, which is independently associated with an increased abundance of epithelial barrier proteins. Physiological concentrations of lactic acid enhance epithelial cell culture barrier integrity and increase intercellular junctional molecule expression. Conclusions These findings reveal a novel ability of vaginal lactic acid to enhance genital epithelial barrier integrity that may help prevent invasion by sexually transmitted pathogens. -WPkVA_hjFNVzj1jBU-6oS Video abstract

Doxycycline pre-exposure prophylaxis (doxyPrEP) has shown potential in preventing bacterial sexually transmitted infections, but the impact on the microbiome is unknown. This study assessed rectal microbiome changes over 48 weeks in 41 participants on HIV PrEP (tenofovir disoproxil fumarate/emtricitabine) enrolled in an open-label, randomized pilot trial comparing immediate (100 mg PO daily started immediately and continued to week 48) versus deferred doxyPrEP (100 mg PO daily starting at week 24, continued to week 48) in HIV-negative gay and bisexual men (Clinical Trial #: NCT02844634). Primary study outcomes included feasibility, adherence, and tolerability of the dual PrEP regimen, while exploratory outcomes included rectal microbiome changes. We performed 16S rRNA sequencing from participants that collected baseline, week 24, and week 48 samples. Microbial composition did not significantly change over time in either study arm as measured by individual taxa levels, or alpha and beta diversity at the genus level. A slight decrease ( < 10%) in alpha diversity was observed at the phylum level in the immediate arm, but not the deferred arm. This study shows doxyPrEP use results in minimal compositional changes in the microbiome over 12 months. Further research is needed to explore the impact of doxycycline for STI prevention on microbiome function and antimicrobial resistance. Here, the authors study the impact of doxycycline pre-exposure prophylaxis (doxyPrEP) on the microbiome of men who have sex with men on HIV PrEP, showing that doxyPrEP use results in minimal compositional changes in the microbiome over 12 months.

Despite the efficacy of antiretroviral-based pre-exposure prophylactics (PrEP) in men who have sex with men, studies in women have produced widely varying outcomes. Recent evidence demonstrates that vaginal microbial communities are associated with increased HIV acquisition risk and may impact PrEP efficacy. Here, we investigate the mechanisms underlying how vaginal bacteria alter PrEP drug levels and impact HIV infection rates ex vivo . Using cervicovaginal lavages (CVLs) from women with or without bacterial vaginosis (BV), we identified microbial metabolism of PrEP drugs in BV samples through LC-MS/MS analysis of soluble drug levels and metabolite formation in dual T-cell cultures. CVL samples were assessed for microbiome analysis using sequencing of bacterial 16S rRNA genes. We also observed non- Lactobacillus bacteria that are associated with BV may potentially impact PrEP efficacy through increased HIV infection rates in co-cultures containing Lactobacillus or BV bacteria, PrEP drugs, CEM-GFP cells, and HIV-1 LAI virus. Finally, we used these data to develop a novel predictive mathematical simulation modeling system to predict these drug interactions for future trials. These studies demonstrate how dysbiotic vaginal microbiota may impact PrEP drugs and provides evidence linking vaginal bacteria to PrEP efficacy in women.

Gastrointestinal (GI) mucosal dysfunction predicts and likely contributes to non-infectious comorbidities and mortality in HIV infection and persists despite antiretroviral therapy. However, the mechanisms underlying this dysfunction remain incompletely understood. Neutrophils are important for containment of pathogens but can also contribute to tissue damage due to their release of reactive oxygen species and other potentially harmful effector molecules. Here we used a flow cytometry approach to investigate increased neutrophil lifespan as a mechanism for GI neutrophil accumulation in chronic, treated HIV infection and a potential role for gastrointestinal dysbiosis. We report that increased neutrophil survival contributes to neutrophil accumulation in colorectal biopsy tissue, thus implicating neutrophil lifespan as a new therapeutic target for mucosal inflammation in HIV infection. Additionally, we characterized the intestinal microbiome of colorectal biopsies using 16S rRNA sequencing. We found that a reduced Lactobacillus: Prevotella ratio associated with neutrophil survival, suggesting that intestinal bacteria may contribute to GI neutrophil accumulation in treated HIV infection. Finally, we provide evidence that Lactobacillus species uniquely decrease neutrophil survival and neutrophil frequency in vitro, which could have important therapeutic implications for reducing neutrophil-driven inflammation in HIV and other chronic inflammatory conditions.

HIV infection damages the gut mucosa leading to chronic immune activation, increased morbidities and mortality, and antiretroviral therapies, do not completely ameliorate mucosal dysfunction. Understanding early molecular changes in acute infection may identify new biomarkers underlying gut dysfunction. Here we utilized a proteomics approach, coupled with flow cytometry, to characterize early molecular and immunological alterations during acute SIV infection in gut tissue of rhesus macaques. Gut tissue biopsies were obtained at 2 times pre-infection and 4 times post-infection from 6 macaques. The tissue proteome was analyzed by mass spectrometry, and immune cell populations in tissue and blood by flow cytometry. Significant proteome changes ( p  < 0.05) occurred at 3 days post-infection (dpi) (13.0%), 14 dpi (13.7%), 28 dpi (16.9%) and 63 dpi (14.8%). At 3 dpi, proteome changes included cellular structural activity, barrier integrity, and activation of epithelial to mesenchymal transition (EMT) (FDR < 0.0001) prior to the antiviral response at 14 dpi (IFNa/g pathways, p  < 0.001). Novel EMT proteomic biomarkers (keratins 2, 6A and 20, collagen 12A1, desmoplakin) and inflammatory biomarkers (PSMB9, FGL2) were associated with early infection and barrier dysfunction. These findings identify new biomarkers preceding inflammation in SIV infection involved with EMT activation. This warrants further investigation of the role of these biomarkers in chronic infection, mucosal inflammation, and disease pathogenesis of HIV.