Identification of immune cells by flow cytometry in vaginal lavages from women with vulvovaginitis and normal microflora

Bacterial vaginosis-driven changes in cervicovaginal immunity that expand the immunological hypothesis for increased HIV susceptibility

Bacterial vaginosis (BV) is a dysbiosis of the vaginal microbiome that is prevalent among reproductive-age females worldwide. Adverse health outcomes associated with BV include an increased risk of sexually-acquired HIV, yet the immunological mechanisms underlying this association are not well understood. To investigate BV-driven changes to cervicovaginal tract (CVT) and circulating T cell phenotypes, participants with or without BV provided vaginal tract (VT) and ectocervical (CX) tissue biopsies and PBMC samples. High-parameter flow cytometry revealed an increased frequency of cervical conventional CD4+ T cells (Tconv) expressing CCR5. However, we found no difference in number of CD3+CD4+CCR5+ cells in the CX or VT of BV+ vs BV- individuals, suggesting that BV-driven increased HIV susceptibility may not be solely attributed to increased CVT HIV target cell abundance. Flow cytometry also revealed that individuals with BV have an increased frequency of dysfunctional CX and VT CD39+ Tconv and CX tissue-resident CD69+CD103+ Tconv, reported to be implicated in HIV acquisition risk and replication. Many soluble immune factor differences in the CVT further support that BV elicits diverse and complex CVT immune alterations. Our comprehensive analysis expands on potential immunological mechanisms that may underlie the adverse health outcomes associated with BV including increased HIV susceptibility.

Detection and consistency of mucosal fluid T lymphocyte phenotypes and their relationship with blood, age and gender

Innate and adaptive immune responses at mucosal surfaces play a role in protection against most infectious diseases. However, the relative importance either of mucosal versus systemic, or of cellular versus humoral immunity in protection against such infections remains unclear. We aimed to determine the relative percentages and reproducibility of detection of five major T lymphocyte phenotypes in stimulated whole mouth fluid (SWMF); to compare matched mucosal and blood phenotypes; to evaluate the consistency of phenotypes in SWMF over time; and to determine any associations with age or gender. Peripheral blood and SWMF samples were collected from 194 participants and sequential concomitant samples were collected from 27 of those and from 12 subjects living with HIV. CD3, CD4, CD8, Th1 and Th2 T lymphocyte phenotypes were determined by FACS. All the five T lymphocyte phenotypes were detected consistently by FACS in PBMC and SWMF with experimental replicates (N = 10; PBMC CV: 3-30%; SWMF CV: 12-36%). In longitudinal samples detection rates were reproducible in both fluids but variations were higher in SWMF (CV: 23-79.6%) than PBMC (CV: 9.7-75%). Statistically significant correlations of the percentages of all the T lymphocyte phenotypes except CD8 was seen between the two fluids. In PBMCs a negative correlation with age was found with CD3, CD4 and CD8 phenotypes, whilst a positive correlation was found in both SWMF and PBMC with the Th2 phenotype. CD3, CD4 and CD8 phenotypes in SWMF and PBMCs from an HIV-positive cohort were not significantly correlated in contrast with the HIV-negative controls. Our study provides a robust FACS protocol for the detection of the five major T lymphocyte phenotypes in SWMF which should prove useful for research with other mucosal fluids.

The Role of Neutrophils in Pregnancy, Term and Preterm Labour

Neutrophils are surveillance cells, and the first to react and migrate to sites of inflammation and infection following a chemotactic gradient. Neutrophils play a key role in both sterile inflammation and infection, performing a wide variety of effector functions such as degranulation, phagocytosis, ROS production and release of neutrophil extracellular traps (NETs). Healthy term labour requires a sterile pro-inflammatory process, whereas one of the most common causes of spontaneous preterm birth is microbial driven. Peripheral neutrophilia has long been described during pregnancy, and evidence exists demonstrating neutrophils infiltrating the cervix, uterus and foetal membranes during both term and preterm deliveries. Their presence supports a role in tissue remodelling via their effector functions. In this review, we describe the effector functions of neutrophils. We summarise the evidence to support their role in healthy pregnancy and labour and describe their potential contribution to microbial driven preterm birth.

Altered Innate Immunity and Damaged Epithelial Integrity in Vaginal Microbial Dysbiosis

The role of neutrophils relative to vaginal dysbiosis is unclear. We hypothesize that bacterial vaginosis (BV)-associated bacteria may induce the activation and accumulation of mucosal neutrophils within the female reproductive tract (FRT), resulting in epithelial barrier damage. We collected endocervical cytobrushes from women with and without BV and assessed bacteria community type and frequency/functional phenotypes of neutrophils. We performed in vitro whole blood co-cultures with BV-associated bacteria and healthy vaginal commensals and assessed their impact on epithelial integrity using transepithelial electrical resistance. We demonstrated increased neutrophil frequency (p < 0.0001), activation (p < 0.0001), and prolonged lifespan (p < 0.0001) in the cytobrushes from women with non-Lactobacillus dominant (nLD) communities. Our in vitro co-cultures confirmed these results and identified significant barrier damage in the presence of neutrophils and G. vaginalis. Here, we demonstrate that BV-associated bacteria induce neutrophil activation and increase lifespan, potentially causing accumulation in the FRT and epithelial barrier damage.

Genital Inflammation Is Not Associated With Decreased Vaginal Tenofovir Concentrations in Women Taking Oral PrEP

BACKGROUND

We evaluated the association of inflammation and dysbosis on cervicovaginal fluid (CVF) tenofovir (TFV) concentrations in women taking oral tenofovir disoproxil fumarate/emtricitable for HIV pre-exposure prophylaxis (PrEP) in the United States.

SETTING

Thirty-five women in a HIV PrEP implementation study attended their week 24 visit at a San Diego research clinic and provided CVF specimens.

METHODS

Women in the Adherence Enhancement Guided by Individualized Texting and Drug Levels study had their CVF specimens evaluated for (1) sexually transmitted bacterial (Neisseria gonorrhoeae, Chlamydia trachomatis, Gardnerella, and Trichomonas vaginalis), viral (human papillomavirus, cytomegalovirus and herpes simplex virus-1/2) and fungal (Candida) infections; (2) microbiome composition by 16 S sequencing (V3-V4 region); and (3) cytokine profiles by enzyme-linked immunoassay (Interleukin-8, macrophage Inflammatory protein-1a, macrophage Inflammatory Protein-1b and interferon-γ-inducible protein-10). Univariate statistical analysis was used to determine factors associated with CVF TFV concentrations. CVF TFV of 100-1000 ng/mL benchmarked typical genital concentrations and TFV-diphosphate in dried blood spots of 700 fmol/punch was considered adequate adherence.

RESULTS

Thirty-five women had CVF specimens collected. No factor was associated with CVF TFV concentrations or discordance of blood and vaginal concentrations. Among 27 participants assessed for vaginosis (Candida, Gardnerella or Trichomonas), women with Gardnerella (n = 11) were more likely to have high (>1000 ng/mL) CVF TFV concentrations (82% versus 33%, P = 0.02).

CONCLUSIONS

Presence of genital viruses, cytokines, or vaginal community state types were not associated with low CVF TFV concentrations in cisgender women taking oral tenofovir disoproxil fumarate/emtricitable for PrEP. The surprising association observed between presence of Gardnerella and higher vaginal TFV concentrations needs further evaluation.

Lactobacilli Strain Mixture Alleviates Bacterial Vaginosis through Antibacterial and Antagonistic Activity in Gardnerella vaginalis-Infected C57BL/6 Mice

The present study investigated the anti-bacterial vaginitis (BV) effects of a mixture of five lactobacilli strains (LM5), containing equal amounts of Ligilactobacillus salivarius MG242, Limosilactobacillus fermentum MG901, Lactiplantibacillus plantarum MG989, Lacticaseibacillus paracasei MG4272, and Lacticaseibacillus rhamnosus MG4288), in HeLa cells and Gardnerella vaginalis (GV)-infected BV mice. All strains produced lactic acid and hydrogen peroxide, and were resistant to nonoxynol-9. LM5 significantly inhibited GV growth by 80%, exhibited good adhesion to HeLa cells, and significantly inhibited GV adhesion to these cells. In GV-infected mice, LM5 administered orally at 5 × 109 CFU/mouse significantly inhibited GV proliferation in the vaginal tract and significantly reduced myeloperoxidase activity, pro-inflammatory cytokine (TNF-α, IL-1β, and IL-6) levels, and nitric oxide levels in vaginal tissue lysates. Histopathological analysis of vaginal tissues revealed that LM5 markedly suppressed the exfoliation of vaginal epithelial cells. Overall, these results suggest that LM5 might alleviate BV by direct antibacterial and antagonistic activity in vaginal tissues of GV-infected mice.

Lactobacillus plantarum Lp62 exerts probiotic effects against Gardnerella vaginalis ATCC 49154 in bacterial vaginosis

The severe side-effects elicited by conventional antibiotic therapy and the recurrence of Bacterial vaginosis-associated bacteria and bacterial resistance have led to the development of novel alternative therapies, among which genital probiotics are widely used. In this study, we aimed to evaluate the antimicrobial activities of Lactobacillus plantarum Lp62 and its supernatant against Gardnerella vaginalis, using both in vitro and in vivo approaches. In vitro assays were used to evaluate the viability of the strain and the antimicrobial activities of the supernatant in different pH ranges. An in vivo assay was performed on female BALB/c mice, wherein the animals were divided into eight groups: four control groups and four treated groups (for curative and preventive therapies). After infecting and treating the mice, the animals were killed to quantify the bacterial load using qPCR, evaluate leucocyte cellular response, determine vaginal cytokine levels and perform cytokine tissue gene expression. Our analyses revealed significant activity of the strain and its supernatant against G. vaginalis. Preliminary in vitro tests showed that the strain grew with equal efficiency in different pH ranges. Meanwhile, the presence of halo and inhibition of pathogen growth established the significant activity of the supernatant against G. vaginalis. We observed that both micro-organisms are resident bacteria of mouse microbiota and that the lactobacilli population growth was affected by G. vaginalis and vice versa. We also observed that the treated groups, with their low bacterial load, absence of leucocyte recruitment, reduced cytokine levels in the vaginal lavage and normalized cytokine gene expression, successfully controlled the infection.

The impact of the Fungus-Host-Microbiota interplay upon Candida albicans infections: current knowledge and new perspectives

Candida albicans is a major fungal pathogen of humans. It exists as a commensal in the oral cavity, gut or genital tract of most individuals, constrained by the local microbiota, epithelial barriers and immune defences. Their perturbation can lead to fungal outgrowth and the development of mucosal infections such as oropharyngeal or vulvovaginal candidiasis, and patients with compromised immunity are susceptible to life-threatening systemic infections. The importance of the interplay between fungus, host and microbiota in driving the transition from C. albicans commensalism to pathogenicity is widely appreciated. However, the complexity of these interactions, and the significant impact of fungal, host and microbiota variability upon disease severity and outcome, are less well understood. Therefore, we summarise the features of the fungus that promote infection, and how genetic variation between clinical isolates influences pathogenicity. We discuss antifungal immunity, how this differs between mucosae, and how individual variation influences a person's susceptibility to infection. Also, we describe factors that influence the composition of gut, oral and vaginal microbiotas, and how these affect fungal colonisation and antifungal immunity. We argue that a detailed understanding of these variables, which underlie fungal-host-microbiota interactions, will present opportunities for directed antifungal therapies that benefit vulnerable patients.

Gardnerella vaginalis as a Cause of Bacterial Vaginosis: Appraisal of the Evidence From in vivo Models

Koch's postulates dictate the use of experimental models to illustrate features of human disease and provide evidence for a singular organism as the cause. The underlying cause(s) of bacterial vaginosis (BV) has been debated in the literature for over half a century. In 1955, it was first reported that a bacterium now known as Gardnerella vaginalis may be the cause of a condition (BV) resulting in higher vaginal pH, thin discharge, a fishy odor, and the presence of epithelial cells covered in bacteria. Here we review contemporary and historical studies on BV with a focus on reports of experimental infections in human or animal models using Gardnerella vaginalis. We evaluate experimental evidence for the hypothesis that G. vaginalis is sufficient to trigger clinical features of BV or relevant health complications associated with the condition. Additionally, we evaluate in vivo models of co-infection employing G. vaginalis together with other bacterial species to investigate evidence for the hypothesis that G. vaginalis may encourage colonization or virulence of other potential pathogens. Together, these studies paint a complex picture in which G. vaginalis has both direct and indirect roles in the features, health complications, and co-infections associated with BV. We briefly review the current taxonomic landscape and genetic diversity pertinent to Gardnerella and note the limitations of sequence-based studies using different marker genes and priming sites. Although much more study is needed to refine our understanding of how BV develops and persists within the human host, applications of the experimental aspects of Koch's postulates have provided an important glimpse into some of the causal relationships that may govern this condition in vivo.

Recurrent Vulvovaginal Candidiasis: An Immunological Perspective

Vulvovaginal candidiasis (VVC) is a widespread vaginal infection primarily caused by Candida albicans. VVC affects up to 75% of women of childbearing age once in their life, and up to 9% of women in different populations experience more than three episodes per year, which is defined as recurrent vulvovaginal candidiasis (RVVC). RVVC results in diminished quality of life as well as increased associated healthcare costs. For a long time, VVC has been considered the outcome of inadequate host defenses against Candida colonization, as in the case of primary immunodeficiencies associated with persistent fungal infections and insufficient clearance. Intensive research in recent decades has led to a new hypothesis that points toward a local mucosal overreaction of the immune system rather than a defective host response to Candida colonization. This review provides an overview of the current understanding of the host immune response in VVC pathogenesis and suggests that a tightly regulated fungus-host-microbiota interplay might exert a protective role against recurrent Candida infections.

Gardnerella vaginalis and Prevotella bivia Trigger Distinct and Overlapping Phenotypes in a Mouse Model of Bacterial Vaginosis

BACKGROUND

Bacterial vaginosis (BV) is a common imbalance of the vaginal microbiota characterized by overgrowth of diverse Actinobacteria, Firmicutes, and Gram-negative anaerobes. Women with BV are at increased risk of secondary reproductive tract infections and adverse pregnancy outcomes. However, which specific bacteria cause clinical features of BV is unclear.

METHODS

We previously demonstrated that Gardnerella vaginalis could elicit many BV features in mice. In this study, we established a BV model in which we coinfected mice with G. vaginalis and another species commonly found in women with BV: Prevotella bivia.

RESULTS

This coinfection model recapitulates several aspects of human BV, including vaginal sialidase activity (a diagnostic BV feature independently associated with adverse outcomes), epithelial exfoliation, and ascending infection. It is notable that G. vaginalis facilitated uterine infection by P. bivia.

CONCLUSIONS

Taken together, our model provides a framework for advancing our understanding of the role of individual or combinations of BV-associated bacteria in BV pathogenesis.

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.

Reactional changes in short-term levonorgestrel-releasing intrauterine system (lng-ius) use

SUMMARY OBJECTIVE: To evaluate endocervical and vaginal environment changes in women using a levonorgestrel-releasing intrauterine system (LNG-IUS). METHODS: A quasi-experimental study included sixty women who had an LNG-IUS inserted in the Family Planning Clinic of UNICAMP between April and November of 2016. Women in reproductive age, non-pregnant, without the use of antibiotics and contraceptives seeking for LNG-IUS insertion were selected for this study. All women were evaluated with regard to vaginal and endocervical pH, vaginal and endocervical Gram-stained bacterioscopy, and Pap-smear before and two months after LNG-IUS insertion. Clinical aspects such as cervical mucus, vaginal discharge, and cervical ectopy were also observed. RESULTS: After LNG-IUS insertion, there was an increase in the following parameters: endocervical pH>4.5 (p=0.02), endocervical neutrophil amount (p<0.0001), vaginal cytolysis (p=0.04). There was a decrease in vaginal discharge (p=0.01). No statistically significant changes were found in vaginal pH, neutrophils amount in the vaginal mucosa, vaginal discharge appearance, vaginal candidiasis, bacterial vaginosis, vaginal coccobacillary microbiota, cervical mucus appearance, or cervical ectopy size. CONCLUSIONS: Short-term LNG-IUS use did not increase vulvovaginal candidiasis or bacterial vaginosis, and led to diminished vaginal discharge. Notwithstanding, this device promoted reactional changes in the vaginal and endocervical environment, without modification on cervical ectopy size.

Structural elucidation and immunostimulatory activity of a new polysaccharide from Cordyceps militaris

The chemical structure of new polysaccharide (CMPB90-1) obtained from Cordyceps militaris was elucidated, and its strengthening effects on immunostimulatory activities of lymphocytes and inducing effects on M1 polarization of macrophages were evaluated.

Inflammatory cells in liquid-based cytology smears classified as bacterial vaginosis

BACKGROUND

Bacterial vaginosis (BV) remains an enigmatic question. The term "osis" instead of "itis" is used because commonly, there are no inflammatory process associated with BV. However, leukocytes are often observed in it.

METHODS

In a transversal study, we evaluated 1178 cases with diagnosis of BV by liquid-based cytology (more than 20% of clue cells), attended in general gynecologic private clinic. Depending of the presence of more than five leukocytes on average per field in immersion objective (1000×), the cases were divided in two groups: few or no leukocytes (< 5 leukocytes per field) (BV) and with leukocytes (≥ 5 leukocytes per field) (BV-L). The Fisher exact and Student t tests was applied to a confidence interval of 95%. The project was approved by the Ethic Committee of Federal University of Ceará, Brazil.

RESULTS

The age between the groups was the only different socio-demographic variable. The assessment of vaginal discharge aspect had no characteristic aspect. Colposcopy findings suggesting colpitis and ectopy were more frequent in the group of BV-L, 7.1% and 6.9%, respectively. The study of the microbiology demonstrated in the BV-L group, more frequently co-occurrence of Candida sp (15.1%) than in BV group (1.5%) (P < .0001). The cellular atypia was present more frequently in the BV-L (9.6%) than in BV (5.7%) (P = .0116).

CONCLUSION

The presence of leukocytes in BV (or BV-L) may suggest a mixed infection, ectopy influencing the vaginal milieu and even epithelial atypia.

The Human Microbiome during Bacterial Vaginosis

Bacterial vaginosis (BV) is the most commonly reported microbiological syndrome among women of childbearing age. BV is characterized by a shift in the vaginal flora from the dominant Lactobacillus to a polymicrobial flora. BV has been associated with a wide array of health issues, including preterm births, pelvic inflammatory disease, increased susceptibility to HIV infection, and other chronic health problems. A number of potential microbial pathogens, singly and in combinations, have been implicated in the disease process. The list of possible agents continues to expand and includes members of a number of genera, including Gardnerella, Atopobium, Prevotella, Peptostreptococcus, Mobiluncus, Sneathia, Leptotrichia, Mycoplasma, and BV-associated bacterium 1 (BVAB1) to BVAB3. Efforts to characterize BV using epidemiological, microscopic, microbiological culture, and sequenced-based methods have all failed to reveal an etiology that can be consistently documented in all women with BV. A careful analysis of the available data suggests that what we term BV is, in fact, a set of common clinical signs and symptoms that can be provoked by a plethora of bacterial species with proinflammatory characteristics, coupled to an immune response driven by variability in host immune function.

Bacterial vaginosis: a critical analysis of current knowledge

Bacterial vaginosis (BV), the change from a Lactobacillus-dominant vaginal microbiota to an anaerobic and facultative bacterial dominance, is associated with pathological sequelae. In many BV-positive women their microbiota is in fact normal and unrelated to pathology. Whether or not the dominance of BV-associated bacteria persists depends upon interactions between host and bacterial factors. Inconsistencies in diagnosis and erroneous associations with pathology may be due to a failure to differentiate between sub-populations of women. It is only in those women with a BV diagnosis in which the identified bacteria are atypical and persist that BV may be a clinical problem requiring intervention.

TWEETABLE ABSTRACT

Improved diagnosis of bacterial vaginosis is needed to accurately determine its role in pathology.

Bacterial Vaginosis and Subclinical Markers of Genital Tract Inflammation and Mucosal Immunity

Bacterial vaginosis (BV) has been linked to an increased risk of human immunodeficiency virus (HIV) acquisition and transmission in observational studies, but the underlying biological mechanisms are unknown. We measured biomarkers of subclinical vaginal inflammation, endogenous antimicrobial activity, and vaginal flora in women with BV and repeated sampling 1 week and 1 month after completion of metronidazole therapy. We also compared this cohort of women with BV to a healthy control cohort without BV. A longitudinal, open label study of 33 women with a Nugent score of 4 or higher was conducted. All women had genital swabs, cervicovaginal lavage (CVL) fluid, and cervicovaginal biopsies obtained at enrollment and received 7 days of metronidazole treatment. Repeat sampling was performed approximately 1 week and 1 month after completion of therapy. Participant's baseline samples were compared to a healthy, racially matched control group (n=13) without BV. The CVL from women with resolved BV (Nugent 0-3) had significantly higher anti-HIV activity, secretory leukocyte protease inhibitor (SLPI), and growth-related oncogene alpha (GRO-α) levels and their ectocervical tissues had significantly more CD8 cells in the epithelium. Women with persistent BV after treatment had significantly higher levels of interleukin-1β, tumor necrosis factor alpha (TNF-α), and intercellular adhesion molecule 1 (ICAM-1) in the CVL. At study entry, participants had significantly greater numbers of CCR5(+) immune cells and a higher CD4/CD8 ratio in ectocervical tissues prior to metronidazole treatment, compared to a racially matched cohort of women with a Nugent score of 0-3. These data indicate that BV is associated with changes in select soluble immune mediators, an increase in HIV target cells, and a reduction in endogenous antimicrobial activity, which may contribute to the increased risk of HIV acquisition.

Bacterial vaginosis and the cervicovaginal immune response

Bacterial vaginosis (BV) is a common cause of vaginal discharge in reproductive age women around the world and is associated with several poor reproductive health outcomes, including HIV-1 acquisition. One possible mechanism for this association is the inflammatory immune response induced by BV in the cervical and vaginal mucosae. There is significant heterogeneity in reports of markers of cervicovaginal inflammation in women with BV, likely due to microbial and host diversity, as well as differences in study design. In this article, we review the characteristics of the mucosal immune response in BV, the potential role of lactobacilli in modulating that response, and the impact of individual BV-associated bacterial species on mucosal immunity. We focus on inflammatory markers that are proposed to increase the risk of HIV-1 acquisition.

Activation effects of polysaccharides of Flammulina velutipes mycorrhizae on the T lymphocyte immune function

Flammulina velutipes mycorrhizae have increasingly been produced with increasing of F. velutipes production. A mouse model was thus used to examine potential effect of F. velutipes mycorrhizae on the immune function. Fifty female Wistar mice (5-weeks-old) weighed 15–20 g were randomly allocated into five groups. Polysaccharide of F. velutipes mycorrhizae were treated with mice and mice spleen lymphocytes. The levels of CD3⁺, CD4⁺, and CD8⁺ T lymphocyte, interleukin-2 (IL-2), and tumor necrosis factor-a (TNF-α) were determined. The results showed that the proportions of CD3⁺, and CD4⁺ T lymphocyte, the ratio of CD4⁺/CD8⁺, and the levels of IL-2 and TNF-a were significantly increased in polysaccharide of F. velutipes mycorrhizae, while the proportion of CD8⁺ T lymphocyte was decreased in polysaccharide of F. velutipes mycorrhizae-dose dependent manner. Our findings indicated that a long term exposure of polysaccharide of F. velutipes mycorrhizae could activate the T lymphocyte immune function. Polysaccharide of F. velutipes mycorrhizae was expected to develop into the immune health products.

Clinical features of bacterial vaginosis in a murine model of vaginal infection with Gardnerella vaginalis

Bacterial vaginosis (BV) is a dysbiosis of the vaginal flora characterized by a shift from a Lactobacillus-dominant environment to a polymicrobial mixture including Actinobacteria and Gram-negative bacilli. BV is a common vaginal condition in women and is associated with increased risk of sexually transmitted infection and adverse pregnancy outcomes such as preterm birth. Gardnerella vaginalis is one of the most frequently isolated bacterial species in BV. However, there has been much debate in the literature concerning the contribution of G. vaginalis to the etiology of BV, since it is also present in a significant proportion of healthy women. Here we present a new murine vaginal infection model with a clinical isolate of G. vaginalis. Our data demonstrate that this model displays key features used clinically to diagnose BV, including the presence of sialidase activity and exfoliated epithelial cells with adherent bacteria (reminiscent of clue cells). G. vaginalis was capable of ascending uterine infection, which correlated with the degree of vaginal infection and level of vaginal sialidase activity. The host response to G. vaginalis infection was characterized by robust vaginal epithelial cell exfoliation in the absence of histological inflammation. Our analyses of clinical specimens from women with BV revealed a measureable epithelial exfoliation response compared to women with normal flora, a phenotype that, to our knowledge, is measured here for the first time. The results of this study demonstrate that G. vaginalis is sufficient to cause BV phenotypes and suggest that this organism may contribute to BV etiology and associated complications. This is the first time vaginal infection by a BV associated bacterium in an animal has been shown to parallel the human disease with regard to clinical diagnostic features. Future studies with this model should facilitate investigation of important questions regarding BV etiology, pathogenesis and associated complications.

The immune response to papillomavirus during infection persistence and regression

Human papillomavirus (HPV) infections cause a significant global health burden, predominantly due to HPV-associated cancers. HPV infects only the epidermal cells of cutaneous and mucosal skin, without penetration into the dermal tissues. Infections may persist for months or years, contributed by an array of viral immune evasion mechanisms. However in the majority of cases immunity-based regression of HPV lesions does eventually occur. The role of the innate immune response to HPV in persistence and regression of HPV infection is not well understood. Although an initial inflammatory infiltrate may contribute to disease regression, sustained inflammation at the HPV-induced lesions, characterized by macrophage and neutrophil infiltration, has been observed in persistence. Pathogen-associated molecular patterns (PAMPs) are important in innate recognition. The double stranded DNA and an L1 and L2 capsid components of the HPV virion are potential PAMPs that can trigger signaling through cellular pattern recognition receptors, including toll-like receptors (TLR). TLR expression is increased in regressing HPV disease but is reduced in persistent lesions, suggesting a role for TLR in HPV regression. With regard to the adaptive immune response, a key indicator of regression in humans is infiltration of the lesion with both CD4 and CD8 T cells. In individuals with persistent lesions, CD8 T cell and immune suppressive regulatory T cells (Tregs) infiltrate the infection site. There is no association between persistence or regression and the presence of serum antibodies to the viral capsid antigens of HPV. There is still much to be learned about the immunological events that trigger regression of HPV disease. Understanding the viral and host factors that influence persistence and regression is important for the development of better immunotherapeutic treatments for HPV-associated disease.

Identification and characterization of bacterial vaginosis-associated pathogens using a comprehensive cervical-vaginal epithelial coculture assay

Bacterial vaginosis (BV) is the most commonly treated female reproductive tract affliction, characterized by the displacement of healthy lactobacilli by an overgrowth of pathogenic bacteria. BV can contribute to pathogenic inflammation, preterm birth, and susceptibility to sexually transmitted infections. As the bacteria responsible for BV pathogenicity and their interactions with host immunity are not understood, we sought to evaluate the effects of BV-associated bacteria on reproductive epithelia. Here we have characterized the interaction between BV-associated bacteria and the female reproductive tract by measuring cytokine and defensin induction in three types of FRT epithelial cells following bacterial inoculation. Four BV-associated bacteria were evaluated alongside six lactobacilli for a comparative assessment. While responses differed between epithelial cell types, our model showed good agreement with clinical BV trends. We observed a distinct cytokine and human β-defensin 2 response to BV-associated bacteria, especially Atopobium vaginae, compared to most lactobacilli. One lactobacillus species, Lactobacillus vaginalis, induced an immune response similar to that elicited by BV-associated bacteria, stimulating significantly higher levels of cytokines and human β-defensin 2 than other lactobacilli. These data provide an important prioritization of BV-associated bacteria and support further characterization of reproductive bacteria and their interactions with host epithelia. Additionally, they demonstrate the distinct immune response potentials of epithelial cells from different locations along the female reproductive tract.