Vaginal microbicides: detecting toxicities in vivo that paradoxically increase pathogen transmission

Vaginal irritation testing-prospects of human organotypic vaginal tissue culture models

Personal lubricants intended for local or systemic delivery via the vaginal route can induce vaginal irritation, damage the vaginal epithelial barrier which can enhance microbial entry, induce inflammation, and alter the microbiome of the vaginal ecosystem. Therefore, manufacturers of personal lubricants and medical devices are required to show biocompatibility and safety assessment data to support regulatory decision-making within a specified context of use. Furthermore, due to ethical concerns and the introduction of the 7th amendment of the European Council Directive which bans animal testing for cosmetic ingredients and products coupled with the Food and Drug Administration modernization Act 2.0 guidelines, there is a wave of drive to develop alternative test methods to predict human responses to chemical or formulation exposure. In this framework, there is a potential to use three-dimensional organotypic human vaginal-ectocervical tissue models as a screening tool to predict the vaginal irritation potential of personal lubricants and medicaments. To be physiologically relevant, the in vitro tissue models need to be reconstructed using primary epithelial cells of the specific organ or tissue and produce organ-like structure and functionality that recapitulate the in vivo-like responses. Through the years, progress has been made and vaginal tissue models are manufactured under controlled conditions with a specified performance criterion, which leads to a high level of reproducibility and reliability. The utility of vaginal tissue models has been accelerated in the last 20 years with an expanded portfolio of applications ranging from toxicity, inflammation, infection to drug safety, and efficacy studies. This article provides an overview of the state of the art of diversified applications of reconstructed vaginal tissue models and highlights their utility as a tool to predict vaginal irritation potential of feminine care products.

Safety of multiple administrations of spermicidal LL-37 antimicrobial peptide into the mouse female reproductive tract

We have previously demonstrated spermicidal activity of LL-37 antimicrobial peptide on mouse/human sperm and its contraceptive effects in female mice. With its microbicidal action against Neisseria gonorrhoeae, LL-37 warrants development into a multipurpose prevention technology (MPT) agent for administering into the female reproductive tract (FRT). However, it is important to verify that multiple administrations of LL-37 do not lead to damage of FRT tissues and/or irreversible loss of fecundity. Herein, we transcervically injected LL-37 (36 µM-10× spermicidal dose) into female mice in estrus in three consecutive estrous cycles. A set of mice were sacrificed for histological assessment of the vagina/cervix/uterus 24 h after the last injection, while the second set were artificially inseminated with sperm from fertile males 1 week afterwards, and then monitored for pregnancy. Mice injected with PBS in parallel were regarded as negative controls, whereas those injected with vaginal contraceptive foam (VCF, available over the counter), containing 12.5% nonoxynol-9, served as positive controls for vaginal epithelium disruption. We demonstrated that the vagina/cervix/uterus remained normal in both LL-37-injected and PBS-injected mice, which also showed 100% resumption of fecundity. In contrast, VCF-injected mice showed histological abnormalities in the vagina/cervix/uterus and only 50% of them resumed fecundity. Similarly, LL-37 multiply administered intravaginally caused no damage to FRT tissues. While our results indicate the safety of multiple treatments of LL-37 in the mouse model, similar studies have to be conducted in non-human primates and then humans. Regardless, our study provides an experimental model for studying in vivo safety of other vaginal MPT/spermicide candidates.

In vitro and ex vivo models for evaluating vaginal drug delivery systems

Vaginal drug delivery systems are often preferred for treating a variety of diseases and conditions of the female reproductive tract (FRT), as delivery can be more targeted with less systemic side effects. However, there are many anatomical and biological barriers to effective treatment via the vaginal route. Further, biocompatibility with the local tissue and microbial microenvironment is desired. A variety of in vitro and ex vivo models are described herein for evaluating the physicochemical properties and toxicity profile of vaginal drug delivery systems. Deciding whether to utilize organoids in vitro or fresh human cervicovaginal mucus ex vivo requires careful consideration of the intended use and the formulation characteristics. Optimally, in vitro and ex vivo experimentation will inform or predict in vivo performance, and examples are given that describe utilization of a range of methods from in vitro to in vivo. Lastly, we highlight more advanced model systems for other mucosa as inspiration for the future in model development for the FRT.

Considerations for Choosing Soluble Immune Markers to Determine Safety of Novel Vaginal Products

Several soluble cytokines have been associated with microbicide-induced cervicovaginal inflammation, non-optimal vaginal microbiota, and risk of HIV acquisition. Many of these biomarkers are used in preclinical assays to estimate the safety of vaginally applied products. However, there are currently no validated biomarkers to evaluate the safety of novel vaginal products in clinical trials. This hinders the rapid and rational selection of novel products being tested in first-in-human trials. We reviewed available literature to assess how best to select and measure soluble immune markers to determine product safety in first in human clinical trials of novel vaginal products.

Women's preferences and acceptance for different drug delivery routes and products

To use or not to use, that is the first decision to take regarding a drug product. This mandatory step for adherence dictates product efficacy. The determinants for such decision do not only rely on the priority of the therapeutic or preventive strategy, but are related to a complex network of perceptions, preferences, personal and cultural backgrounds, and results from previous experiences. Women's preferences for dosage forms and even for drug delivery routes have been mainly studied in the fields of contraception and HIV prevention (and their related multipurpose approaches). Much less attention has been devoted to other therapeutic or preventive strategies. In a time when patient-centred approaches and shared decisions are increasingly valued, considering women's preferences and their main determinants is essential for product development and selection. Such products will be more likely to be chosen and used as intended, increasing efficacy, and reducing the overall costs related with these treatments. This knowledge shall be integrated in early stages of product development. This article reviews the state of the art related with women's preferences and acceptance for different dosage forms and drug delivery routes involved in women's health. The methodologies used for collecting these data and their major drawbacks are discussed. Results obtained from acceptability studies and the main determinants for selection of preventive and treatment drug products are discussed as tools for new developments in the field.

Serine protease inhibitor disrupts sperm motility leading to reduced fertility in female mice†

Inhibition of the sperm transport process in the female reproductive tract could lead to infertility. We previously showed that a pan-serine protease inhibitor, 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF), blocked semen liquefaction in vivo and resulted in a drastic decrease in the number of sperm in the oviduct of female mice. In this study, we used a mouse model to test the efficacy of AEBSF as a reversible contraceptive, a sperm motility inhibitor, and a spermicide. Additionally, this study evaluated the toxicity of AEBSF on mouse vaginal tissues in vivo and human endocervical cells in vitro. We found that female mice treated with AEBSF had significantly less pups born per litter as well as fertilization rates in vivo compared to the vehicle control. We then showed that AEBSF reduced sperm motility and fertilization capability in vitro in a dose-dependent manner. Furthermore, AEBSF also exhibited spermicidal effects. Lastly, AEBSF treatment in female mice for 10 min or 3 consecutive days did not alter vaginal cell viability in vivo, similar to that of the vehicle and non-treated controls. However, AEBSF decreased cell viability of human ectocervical (ECT) cell line in vitro, suggesting that cells in the lower reproductive tract in mice and humans responded differently to AEBSF. In summary, our study showed that AEBSF can be used as a prototype compound for the further development of novel non-hormonal contraceptives for women by targeting sperm transport in the female reproductive tract.

dl-Mandelic acid exhibits high sperm-immobilizing activity and low vaginal irritation: A potential non-surfactant spermicide for contraception

dl-Mandelic acid (MA), an alpha-hydroxycarboxylic acid, has been widely used as an intermediate of pharmaceutical and fine chemicals. Here, we evaluated the sperm-immobilizing activity of MA and its safety profiles. Spermatozoon motility was assessed by computer-aided sperm analysis, the integrity of the plasma membrane and. mitochondrial potential was assessed using fluorescein isothiocyanate-pisum sativum agglutinin and JC-1, respectively. The local tolerance of the MA-containing gel formulation was evaluated using a rabbit vaginal irritation test. We found that MA inhibited sperm motility and movement patterns in a concentration-dependent manner. Within 20 s, MA-induced spermatozoa immobilization occurred with a minimum effective concentration and a median effective concentration of 0.86 and 0.54 mg/mL, respectively. Plasma membrane disruptions of MA-treated spermatozoa were relatively mild, but mitochondrial depolarization occurred. Histopathological examination showed that MA exposure did not exert obvious effects on the integrity of spermatozoa membrane structures and only caused slight irritation to the rabbit vaginal epithelium. The vaginal irritation scores of the vehicle control and the nonoxynol -9 gel control groups were 1.38 ± 0.65 and 7.88 ± 1.67, respectively (p < 0.01), whereas those of the MA gel groups at 10, 20, and 40 mg/mL were 1.69 ± 1.04, 2.98 ± 0.77, and 4.35 ± 1.04 with p values of >0.05, >0.05, and <0.05 (vs. vehicle control), respectively, which were within the clinically acceptable range (<8). Therefore, our results confirmed that MA exhibited significant sperm-immobilizing effects and caused mild plasma membrane injury, suggesting that it has potential for development as a future non-surfactant spermicide.

Asymptomatic Bacterial Vaginosis Is Associated With Depletion of Mature Superficial Cells Shed From the Vaginal Epithelium

Previous studies have described bacterial vaginosis (BV) as associated with increased cell-shedding from the cervicovaginal epithelium. Cell-shedding in excess of cell-proliferation is thought to decrease epithelial barrier function and increase susceptibility to infection. This study evaluated the number of shed cells in mid-vaginal smears from women with a diagnosis of symptomatic BV (sBV, n = 17), asymptomatic BV (aBV, n = 71), or no BV (n = 104) by Amsel criteria. The sBV smears contained significantly more shed cells (median 158/100X field) than no BV smears (median 91/100X field), p = 7.2e−9. However, we observed that aBV smears contained significantly fewer shed cells (median 35/100X field) than no BV smears, p = 22.0e−16. The sizes of cell-aggregates (cells shed in sometimes multilayered sections with intact cell-cell attachments) followed the same pattern. Cell-aggregates in sBV smears were significantly larger (median ~220,000 μm²) than those in no BV smears (median ~50,000 μm²), p = 1.8e−6, but cell-aggregates in aBV smears were significantly smaller (median ~7,000 μm²) than those in no BV smears, p = 0.0028. We also compared the superficial cell index (SCI), a measure of cervicovaginal epithelial cell maturity, in no BV and aBV smears with relatively low numbers of shed cells (≤50/100X field). The SCI of no BV smears was significantly higher (median 0.86) than that of aBV smears (median 0.35), p = 4.3e−98, suggesting a depletion of mature cells with exposure and shedding of underlying immature cells in aBV with low number of shed cells. These results indicate that aBV may contribute disproportionately to the increased susceptibility to reproductive tract infections associated with BV. Our findings remained true when considering only those smears in which the microbiota comprised a diverse set of strict and facultative anaerobic bacteria [Community State Type IV (n = 162)], thus excluding those dominated by Lactobacillus spp. This is consistent with our developing hypothesis that high-shedding sBV and low-shedding aBV could be temporally separated phases of the same condition, rather than two separate forms of BV. These findings might inform future work on clinical management of symptomatic and asymptomatic bacterial vaginosis.

Correlation between detergent activity and anti-herpes simplex virus-2 activity of commercially available vaginal gels

OBJECTIVE

Herpes simplex virus-2 (HSV-2) infections are almost exclusively sexually transmitted. The presence of vaginal gels during sexual activity may have a significant positive or negative impact on viral transmission. Therefore we investigated three off-the-shelf vaginal lubricants and one pH restoring gel to evaluate their impact on HSV-2 replication.

RESULTS

HeLa cells were infected with untreated virions and virions incubated with the particular gels. The accumulation of viral genomes was monitored by quantitative PCR (qPCR) method at 24 h post infection. Two of the tested gels had no significant effect on HSV-2 replication at the maximum applied concentration, while two had a strong inhibitory effect (~ 98% reduction of replication). The replication inhibitory effect was observed at various multiplicity of infection (MOI 0.4-6.4) and the two inhibitory gels were also capable of inhibiting the HSV-2 induced cytopathic effect on HeLa cells. The surface tension decreasing activity-an indication of detergent activity-was strongly correlated with the anti-HSV-2 activity of the gels (R²: 0.88). Our results indicate that off-the-shelf vaginal gels have a markedly different anti-HSV-2 activity that may influence HSV-2 transmission.

Effects of an over-the-counter lactic-acid containing intra-vaginal douching product on the vaginal microbiota

Background

Over-the-counter intra-vaginal lactic-acid containing douches are marketed as vaginal hygiene products that support optimal vaginal pH balance. We report the effect of a commercially available douche (Etos®) on the vaginal microbiota (VM) in a prospective study.

Results

Twenty-five healthy women were recruited through advertisements in 2015–2017 (ethical approval: METC-2014_413) and followed over three menstrual cycles. The participants had a median age of 24 years [IQR: 22–29], were mostly Dutch-Caucasian (88%), and 60% used combined oral contraceptives. All participants douched three times a week during the second cycle, starting on the first day of that cycle. Participants completed a questionnaire at baseline, kept a daily diary to report douching, menses, and sexual activity, self-collected vaginal swabs every other day during the first and third cycle and daily during the second cycle, and measured vaginal pH mid-cycle. A median of 44 vaginal swabs [inter-quartile range (IQR): 41–50] were assessed per participant by 16S rRNA gene (V3-V4 region) sequencing and a Candida albicans PCR was done at four time-points. At baseline, 21 participants (84%) had Lactobacillus-dominated VM (Lactobacillus crispatus (n = 14), L. iners (n = 6), or diverse Lactobacillus species (n = 1) and 4 participants (16%) had VM consisting of diverse anaerobes. In multinomial logistic regression models, a trend towards increased odds were observed for having diverse anaerobic VM in the second and third cycle, compared to the first cycle, after adjusting for menses [odds ratio (OR) = 1.4 (95% CI: 0.9–2.1) and OR = 1.7 (95% CI: 0.9–3.1), respectively] (p = 0.376). Douching did not affect vaginal pH. Menses increased the odds for having VM consisting of diverse anaerobes almost two-fold (OR = 1.7; 95% CI: 1.0–2.8), while douching during menses increased the odds 2.6 fold (OR = 2.6; 95% CI: 1.0–6.5), compared to not menstruating (p = 0.099). Participants were more likely to test positive for C. albicans after cycle 2, compared to cycle 1 [OR = 3.0 (95% CI: 1.2–7.2); p = 0.017].

Conclusion

The Etos® douche did not significantly affect the vaginal pH or VM composition, although increased odds for having diverse anaerobic VM was observed, especially when douching during menses. Furthermore, douching may promote C. albicans infections.

Electronic supplementary material

The online version of this article (10.1186/s12866-019-1545-0) contains supplementary material, which is available to authorized users.

An overview of properties of Amphora (Acidform) contraceptive vaginal gel

INTRODUCTION

Although only a minority of contracepting women rely solely on spermicides, they may soon be the only ongoing female method available without a prescription in the United States. Spermicides are also combined with other methods for additional pregnancy protection and/or lubrication. Nonoxynol-9 (N-9), the active ingredient in most spermicides, is cytotoxic and may increase risk of transmission of HIV and other sexually transmitted infections, especially in high-risk women. Amphora (previously called Acidform) is a noncytotoxic spermicide composed of a series of generally regarded as safe compounds, which maintains the acidity of the vagina following coitus to immobilize and kill sperm. Amphora is currently Food and Drug Administration-approved as a vaginal lubricant. Amphora is currently being tested in a multicenter Phase III contraceptive trial.

AREAS COVERED

This paper describes key properties of Amphora, including its acid-buffering abilities, viscosity, stability, bioadhesiveness, and tolerability.

EXPERT OPINION

Amphora is a nontoxic spermicide that maintains the pH within the vagina at levels less than 5.0 for hours, which immobilizes and kills sperm as well as many sexually transmitted pathogens. If the current clinical trial demonstrates safety, efficacy, and tolerability of Amphora as a contraceptive, it would represent a viable alternative to N-9. Its potential as a microbicide warrants further investigation.

Submicron Matrices Embedded in a Polymeric Caplet for Extended Intravaginal Delivery of Zidovudine

In this study, an intravaginal delivery system able to deliver an anti-HIV-1 agent for the purpose of potentially reducing HIV-1 transmission acting over an extended duration was successfully formulated. This delivery system was a composite polymeric caplet comprising zidovudine-loaded polyethylene glycol enclatherated pectin-mucin submicron matrices embedded within a poly (D,L-lactide), magnesium stearate, Kollidon® SR, and Carbopol® 974P NF-based polymeric caplet matrix. A three-factor and three-level Box-Behnken statistical design was utilized to optimize the polymeric caplet. The optimized directly compressed composite polymeric caplet hardness was 22.1 ± 0.3 N and the matrix resilience was 62.4 ± 0.6%. The swelling- and diffusion-controlled fractional zidovudine (AZT) release from the optimized caplet was 0.74 ± 0.01 in simulated vaginal fluid (SVF), which increased to 0.81 ± 0.21 in phosphate-buffered saline (PBS) simulating seminal fluid, over 30 days. Caplet matrix swelling was directly related to the percentage Carbopol 974P NF composition. An intravaginal system for AZT delivery was tested in the pig model over 28 days. X-ray analysis depicted delivery system swelling with matrix contrast fading over time as vaginal fluid permeated the matrix core. Plasma, vaginal fluid swab eluates, and tissue AZT concentrations were measured by gradient ultra-performance liquid chromatography (UPLC)-tandem photodiode array detection. Vaginal tissue and vaginal fluid swab eluate AZT concentrations remained above effective levels over 28 days and were higher than plasma AZT concentrations, availing a system with reduced systemic toxicity and more effective inhibition of viral replication at the site of entry.

Relationship between nugent score and vaginal epithelial exfoliation

Objective

Clue cells characteristic of bacterial vaginosis (BV) are thought to arise due to exfoliation of the vaginal epithelium; however, there is little published data connecting total numbers of epithelial cells to markers of BV. The purpose of this study was to enumerate exfoliated epithelial cells (independent of clue cells) and examine the relationship to Nugent score.

Study design

We conducted a cross-sectional sub-study of the Contraceptive CHOICE Project cohort. Vaginal swabs were used to create vaginal smears for Gram staining and these smears were later scored using the Nugent method, and then two blinded observers used microscopy to enumerate exfoliated epithelial cells. The degree of epithelial cell exfoliation was compared between women diagnosed as BV-negative (Nugent score 0–3), BV-intermediate (Nugent score 4–6), and BV-positive (Nugent score 7–10). BV specimens (Nugent 7–10) were randomly matched to specimens in the two other groups (Nugent low and Nugent-intermediate), in order to avoid comparing groups of women with potentially confounding baseline demographics.

Results

Exfoliated epithelial cell counts were higher in the vaginal smears from BV-positive women compared with BV-negative women. Higher levels of epithelial exfoliation were also evident in BV-intermediate women compared to those with low Nugent scores. After adjustment for clustering introduced by matching, the incidence ratio of increased epithelial cell counts was 2.09 (95% CI 1.50–2.90) for the BV-intermediate women and 1.71 (95% CI 1.23–2.38) for the BV positive women.

Conclusion

A vaginal epithelial exfoliation phenotype was measured in both Nugent-defined BV-positive and BV-intermediate women. Bacterial vaginosis and intermediate status (Nugent score >3) was associated with significantly more vaginal epithelial exfoliation compared to women with Lactobacillus-dominated microbiotas (Nugent 0–3).

Development and in vivo safety assessment of tenofovir-loaded nanoparticles-in-film as a novel vaginal microbicide delivery system

Topical pre-exposure prophylaxis (PrEP) with antiretroviral drugs holds promise in preventing vaginal transmission of HIV. However, significant biomedical and social issues found in multiple past clinical trials still need to be addressed in order to optimize protection and users' adherence. One approach may be the development of improved microbicide products. A novel delivery platform comprising drug-loaded nanoparticles (NPs) incorporated into a thin polymeric film base (NPs-in-film) was developed in order to allow the vaginal administration of the microbicide drug candidate tenofovir. The system was optimized for relevant physicochemical features and characterized for biological properties, namely cytotoxicity and safety in a mouse model. Tenofovir-loaded poly(lactic-co-glycolic acid) (PLGA)/stearylamine (SA) composite NPs with mean diameter of 127nm were obtained with drug association efficiency above 50%, and further incorporated into an approximately 115μm thick, hydroxypropyl methylcellulose/poly(vinyl alcohol)-based film. The system was shown to possess suitable mechanical properties for vaginal administration and to quickly disintegrate in approximately 9min upon contact with a simulated vaginal fluid (SVF). The original osmolarity and pH of SVF was not affected by the film. Tenofovir was also released in a biphasic fashion (around 30% of the drug in 15min, followed by sustained release up to 24h). The incorporation of NPs further improved the adhesive potential of the film to ex vivo pig vaginal mucosa. Cytotoxicity of NPs and film was significantly increased by the incorporation of SA, but remained at levels considered tolerable for vaginal delivery of tenofovir. Moreover, histological analysis of genital tissues and cytokine/chemokine levels in vaginal lavages upon 14days of daily vaginal administration to mice confirmed that tenofovir-loaded NPs-in-film was safe and did not induce any apparent histological changes or pro-inflammatory response. Overall, obtained data support that the proposed delivery system combining the use of polymeric NPs and a film base may constitute an exciting alternative for the vaginal administration of microbicide drugs in the context of topical PrEP.

STATEMENT OF SIGNIFICANCE

The development of nanotechnology-based microbicides is a recent but promising research field seeking for new strategies to circumvent HIV sexual transmission. Different reports detail on the multiple potential advantages of using drug nanocarriers for such purpose. However, one important issue being frequently neglected regards the development of vehicles for the administration of microbicide nanosystems. In this study, we propose and detail on the development of a nanoparticle-in-film system for the vaginal delivery of the microbicide drug candidate tenofovir. This is an innovative approach that, to our best knowledge, had never been tested for tenofovir. Results, including those from in vivo testing, sustain that the proposed system is safe and holds potential for further development as a vaginal microbicide product.

Nanoparticles-in-film for the combined vaginal delivery of anti-HIV microbicide drugs

Combining two or more antiretroviral drugs in one medical product is an interesting but challenging strategy for developing topical anti-HIV microbicides. We developed a new vaginal delivery system comprising the incorporation of nanoparticles (NPs) into a polymeric film base - NPs-in-film - and tested its ability to deliver tenofovir (TFV) and efavirenz (EFV). EFV-loaded poly(lactic-co-glycolic acid) NPs were incorporated alongside free TFV into fast dissolving films during film manufacturing. The delivery system was characterized for physicochemical properties, as well as genital distribution, local and systemic 24h pharmacokinetics (PK), and safety upon intravaginal administration to mice. NPs-in-film presented suitable technological, mechanical and cytotoxicity features for vaginal use. Retention of NPs in vivo was enhanced both in vaginal lavages and tissue when associated to film. PK data evidenced that vaginal drug levels rapidly decreased after administration but NPs-in-film were still able to enhance drug concentrations of EFV. Obtained values for area-under-the-curve for EFV were around one log10 higher than those for the free drugs in aqueous vehicle (phosphate buffered saline). Film alone also contributed to higher and more prolonged local drug levels as compared to the administration of TFV and EFV in aqueous vehicle. Systemic exposure to both drugs was low. NPs-in-film was found to be safe upon once daily vaginal administration to mice, with no significant genital histological changes or major alterations in cytokine/chemokine profiles being observed. Overall, the proposed NPs-in-film system seems to be an interesting delivery platform for developing combination vaginal anti-HIV microbicides.

In Vivo Rectal Mucosal Barrier Function Imaging in a Large-Animal Model by Using Confocal Endomicroscopy: Implications for Injury Assessment and Use in HIV Prevention Studies

Injury occurring on the surface of the rectal mucosal lining that causes defects in barrier function may result in increased risk for transmission of infection by HIV and other pathogens. Such injury could occur from microbicidal or other topical agents, mechanical trauma during consensual or nonconsensual intercourse, or inflammatory conditions. Tools for evaluation of rectal mucosal barrier function for assessing the mucosa under these conditions are lacking, particularly those that can provide in vivo structural and functional barrier integrity assessment and are adaptable to longitudinal imaging. We investigated confocal endomicroscopy (CE) as a means for in vivo imaging of the rectal epithelial barrier in the ovine model following spatially confined injury to the surface at a controlled site using a topical application of the microbicide test agent benzalkonium chloride. Topical and intravenous (i.v.) fluorescent probes were used with CE to provide subcellular resolution imaging of the mucosal surface and assessment of barrier function loss. A 3-point CE grading system based on cellular structure integrity and leakage of dye through the mucosa showed significant differences in score between untreated (1.19 ± 0.53) and treated (2.55 ± 0.75) tissue (P < 0.0001). Histological grading confirmed findings of barrier compromise. The results indicate that CE is an effective means for detecting epithelial injury and barrier loss following localized trauma in a large-animal model. CE is promising for real-time rectal mucosal evaluation after injury or trauma or topical application of emerging biomedical prevention strategies designed to combat HIV.

Topical injury evaluation of the murine colorectal mucosa using confocal endomicrosopy: a valuable method for assessing mucosal injuries associated with risk of pathogen transmission

BACKGROUND

Concern regarding the effect of epithelial damage to the colorectal surface and possible impact on sexually transmitted infection transmission prompts the need for methods to evaluate the mucosal microscopic surface in preclinical studies examining such injury. This includes determining the effect of topical HIV prevention products on mucosal barrier integrity. In vivo imaging with high-resolution endomicroscopy could reveal defects in the mucosal barrier resulting from injury/surface trauma.

METHODS

Confocal endomicroscopy was investigated to assess the ability to image surface injury resulting from topical application of a chemical used in lubricants and microbial products. Mice treated with a 50 μL rectal dose of 0.2% benzalkonium chloride solution, 1% benzalkonium chloride or phosphate-buffered saline control for 20 min were imaged in vivo using confocal endomicroscopy for assessment of epithelial disruption. Following imaging, mice were sacrificed and rectal tissue evaluated by histology. Confocal images were graded based on degree of disruption to crypt and epithelial microstructure. Histology was graded based on percent of epithelial disruption observed in stained sections. Confocal image features were confirmed by high-resolution two-photon microscopy.

RESULTS

Based on quantitative grading of in vivo confocal endomicroscopy images, disruption at the microscopic scale was observed following treatment with benzalkonium chloride, with increased injury occurring with higher dose. Epithelial disruption at the lumen surface, evident between crypts and alteration in crypt structure on the luminal side were observed in confocal endomicroscopy and confirmed by histology.

CONCLUSIONS

High-resolution imaging by confocal endomicroscopy can be used as a noninvasive tool for rapid visual assessment of rectal epithelial integrity following surface injury, potentially providing valuable indication of epithelial injury or trauma.

Treating vulvovaginal atrophy/genitourinary syndrome of menopause: how important is vaginal lubricant and moisturizer composition?

Vaginal dryness is a common condition that is particularly prevalent during and after the menopause, and is one of the symptoms of vulvovaginal atrophy/genitourinary syndrome of menopause. The impact of vaginal dryness on interpersonal relationships, quality of life, daily activities, and sexual function can be significant, but is frequently underestimated. Furthermore, barriers exist to treatment-seeking, and this condition is often underreported and undertreated. Greater education about vaginal dryness and the range of available treatments is essential to encourage more women to seek help for this condition.

Personal lubricants and moisturizers are effective at relieving discomfort and pain during sexual intercourse for women with mild to moderate vaginal dryness, particularly those who have a genuine contraindication to estrogen, or who choose not to use estrogen. However, there is a distinction between lubricants and moisturizers, and notable differences between commercially available products. Women should be advised to choose a product that is optimally balanced in terms of both osmolality and pH, and is physiologically most similar to natural vaginal secretions. A series of recommendations for the use of vaginal lubricants and moisturizers, either on their own or in combination with systemic or topical hormone replacement therapy, is presented.

Quaternary ammonium surfactant structure determines selective toxicity towards bacteria: mechanisms of action and clinical implications in antibacterial prophylaxis

OBJECTIVES

Broad-spectrum antimicrobial activity of quaternary ammonium surfactants (QAS) makes them attractive and cheap topical prophylactic options for sexually transmitted infections and perinatal vertically transmitted urogenital infections. Although attributed to their high affinity for biological membranes, the mechanisms behind QAS microbicidal activity are not fully understood. We evaluated how QAS structure affects antimicrobial activity and whether this can be exploited for use in prophylaxis of bacterial infections.

METHODS

Acute toxicity of QAS to in vitro models of human epithelial cells and bacteria were compared to identify selective and potent bactericidal agents. Bacterial cell viability, membrane integrity, cell cycle and metabolism were evaluated to establish the mechanisms involved in selective toxicity of QAS.

RESULTS

QAS toxicity normalized relative to surfactant critical micelle concentration showed n-dodecylpyridinium bromide (C12PB) to be the most effective, with a therapeutic index of ∼10 for an MDR strain of Escherichia coli and >20 for Neisseria gonorrhoeae after 1 h of exposure. Three modes of QAS antibacterial action were identified: impairment of bacterial energetics and cell division at low concentrations; membrane permeabilization and electron transport inhibition at intermediate doses; and disruption of bacterial membranes and cell lysis at concentrations close to the critical micelle concentration. In contrast, toxicity to mammalian cells occurs at higher concentrations and, as we previously reported, results primarily from mitochondrial dysfunction and apoptotic cell death.

CONCLUSIONS

Our data show that short chain (C12) n-alkyl pyridinium bromides have a sufficiently large therapeutic window to be good microbicide candidates.

A Pilot Study Measuring the Distribution and Permeability of a Vaginal HIV Microbicide Gel Vehicle Using Magnetic Resonance Imaging, Single Photon Emission Computed Tomography/Computed Tomography, and a Radiolabeled Small Molecule

Vaginal microbicide gels containing tenofovir have proven effective in HIV prevention, offering the advantage of reduced systemic toxicity. We studied the vaginal distribution and effect on mucosal permeability of a gel vehicle. Six premenopausal women were enrolled. In Phase 1, a spreading gel containing (99m)technetium-DTPA ((99m)Tc) radiolabel and gadolinium contrast for magnetic resonance imaging (MRI) was dosed intravaginally. MRI was obtained at 0.5, 4, and 24 h, and single photon emission computed tomography with conventional computed tomography (SPECT/CT) at 1.5, 5, and 25 h postdosing. Pads and tissues were measured for activity to determine gel loss. In Phase 2, nonoxynol-9 (N-9), containing (99m)Tc-DTPA, was dosed as a permeability control; permeability was measured in blood and urine for both phases. SPECT/CT showed the distribution of spreading gel throughout the vagina with the highest concentration of radiosignal in the fornices and ectocervix; signal intensity diminished over 25 h. MRI showed the greatest signal accumulation in the fornices, most notably 1-4 h postdosing. The median (interquartile range) isotope signal loss from the vagina through 6 h was 29.1% (15.8-39.9%). Mucosal permeability to (99m)Tc-DTPA following spreading gel was negligible, in contrast to N-9, with detectable radiosignal in plasma, peaking at 8 h (5-12). Following spreading gel dosing, 0.004% (0.001-2.04%) of the radiosignal accumulated in urine over 12 h compared to 8.31% (7.07-11.01%) with N-9, (p=0.043). Spreading gel distributed variably throughout the vagina, persisting for 24 h, with signal concentrating in the fornices and ectocervix. The spreading gel had no significant effect on vaginal mucosal permeability.

Gene Expression Profiling of Human Vaginal Cells In Vitro Discriminates Compounds with Pro-Inflammatory and Mucosa-Altering Properties: Novel Biomarkers for Preclinical Testing of HIV Microbicide Candidates

BACKGROUND

Inflammation and immune activation of the cervicovaginal mucosa are considered factors that increase susceptibility to HIV infection. Therefore, it is essential to screen candidate anti-HIV microbicides for potential mucosal immunomodulatory/inflammatory effects prior to further clinical development. The goal of this study was to develop an in vitro method for preclinical evaluation of the inflammatory potential of new candidate microbicides using a microarray gene expression profiling strategy.

METHODS

To this end, we compared transcriptomes of human vaginal cells (Vk2/E6E7) treated with well-characterized pro-inflammatory (PIC) and non-inflammatory (NIC) compounds. PICs included compounds with different mechanisms of action. Gene expression was analyzed using Affymetrix U133 Plus 2 arrays. Data processing was performed using GeneSpring 11.5 (Agilent Technologies, Santa Clara, CA).

RESULTS

Microarraray comparative analysis allowed us to generate a panel of 20 genes that were consistently deregulated by PICs compared to NICs, thus distinguishing between these two groups. Functional analysis mapped 14 of these genes to immune and inflammatory responses. This was confirmed by the fact that PICs induced NFkB pathway activation in Vk2 cells. By testing microbicide candidates previously characterized in clinical trials we demonstrated that the selected PIC-associated genes properly identified compounds with mucosa-altering effects. The discriminatory power of these genes was further demonstrated after culturing vaginal cells with vaginal bacteria. Prevotella bivia, prevalent bacteria in the disturbed microbiota of bacterial vaginosis, induced strong upregulation of seven selected PIC-associated genes, while a commensal Lactobacillus gasseri associated to vaginal health did not cause any changes.

CONCLUSIONS

In vitro evaluation of the immunoinflammatory potential of microbicides using the PIC-associated genes defined in this study could help in the initial screening of candidates prior to entering clinical trials. Additional characterization of these genes can provide further insight into the cervicovaginal immunoinflammatory and mucosal-altering processes that facilitate or limit HIV transmission with implications for the design of prevention strategies.

Herpes simplex virus 2 infection: molecular association with HIV and novel microbicides to prevent disease

Infection with herpes simplex viruses is one of the most ancient diseases described to affect humans. Infection with these viruses produces vexing effects to the host, which frequently recur. Infection with herpes simplex viruses is lifelong, and currently there is no vaccine or drug to prevent or cure infection. Prevalence of herpes simplex virus 2 (HSV-2) infection varies significantly depending on the geographical region and nears 20% worldwide. Importantly, HSV-2 is the first cause of genital ulcers in the planet. HSV-2 affects approximately 500 million people around the globe and significantly increases the likelihood of acquiring the human immunodeficiency virus (HIV), as well as its shedding. Thus, controlling HSV-2 infection and spread is of public health concern. Here, we review the diseases produced by herpes simplex viruses, the factors that modulate HSV-2 infection, the relationship between HSV-2 and HIV and novel therapeutic and prophylactic microbicides/antivirals under development to prevent infection and pathological outcomes produced by this virus. We also review mutations associated with HSV-2 resistance to common antivirals.

Pretreatment of human cervicovaginal mucus with pluronic F127 enhances nanoparticle penetration without compromising mucus barrier properties to herpes simplex virus

Mucosal drug delivery nanotechnologies are limited by the mucus barrier that protects nearly all epithelial surfaces not covered with skin. Most polymeric nanoparticles, including polystyrene nanoparticles (PS), strongly adhere to mucus, thereby limiting penetration and facilitating rapid clearance from the body. Here, we demonstrate that PS rapidly penetrate human cervicovaginal mucus (CVM), if the CVM has been pretreated with sufficient concentrations of Pluronic F127. Importantly, the diffusion rate of large polyethylene glycol (PEG)-coated, nonmucoadhesive nanoparticles (PS-PEG) did not change in F127-pretreated CVM, implying that F127 did not significantly alter the native pore structure of CVM. Additionally, herpes simplex virus type 1 (HSV-1) remains adherent in F127-pretreated CVM, indicating that the presence of F127 did not reduce adhesive interactions between CVM and the virions. In contrast to treatment with a surfactant that has been approved for vaginal use as a spermicide (nonoxynol-9 or N9), there was no increase in inflammatory cytokine release in the vaginal tract of mice after daily application of 1% F127 for 1 week. Pluronic F127 pretreatment holds potential as a method to safely improve the distribution, retention, and efficacy of nanoparticle formulations without compromising CVM barrier properties to pathogens.

New candidate biomarkers in the female genital tract to evaluate microbicide toxicity

Vaginal microbicides hold great promise for the prevention of viral diseases like HIV, but the failure of several microbicide candidates in clinical trials has raised important questions regarding the parameters to be evaluated to determine in vivo efficacy in humans. Clinical trials of the candidate microbicides nonoxynol-9 (N9) and cellulose sulfate revealed an increase in HIV infection, vaginal inflammation, and recruitment of HIV susceptible lymphocytes, highlighting the need to identify biomarkers that can accurately predict microbicide toxicity early in preclinical development and in human trials. We used quantitative proteomics and RT-PCR approaches in mice and rabbits to identify protein changes in vaginal fluid and tissue in response to treatment with N9 or benzalkonium chloride (BZK). We compared changes generated with N9 and BZK treatment to the changes generated in response to tenofovir gel, a candidate microbicide that holds promise as a safe and effective microbicide. Both compounds down regulated mucin 5 subtype B, and peptidoglycan recognition protein 1 in vaginal tissue; however, mucosal brush samples also showed upregulation of plasma proteins fibrinogen, plasminogen, apolipoprotein A-1, and apolipoprotein C-1, which may be a response to the erosive nature of N9 and BZK. Additional proteins down-regulated in vaginal tissue by N9 or BZK treatment include CD166 antigen, olfactomedin-4, and anterior gradient protein 2 homolog. We also observed increases in the expression of C-C chemokines CCL3, CCL5, and CCL7 in response to treatment. There was concordance in expression level changes for several of these proteins using both the mouse and rabbit models. Using a human vaginal epithelial cell line, the expression of mucin 5 subtype B and olfactomedin-4 were down-regulated in response to N9, suggesting these markers could apply to humans. These data identifies new proteins that after further validation could become part of a panel of biomarkers to effectively evaluate microbicide toxicity.

Poly(ethylene glycol) (PEG)-lactic acid nanocarrier-based degradable hydrogels for restoring the vaginal microenvironment

Women with bacterial vaginosis (BV) display reduced vaginal acidity, which make them susceptible to associated infections such as HIV. In the current study, poly(ethylene glycol) (PEG) nanocarrier-based degradable hydrogels were developed for the controlled release of lactic acid in the vagina of BV-infected women. PEG-lactic acid (PEG-LA) nanocarriers were prepared by covalently attaching lactic acid to 8-arm PEG-SH via cleavable thioester bonds. PEG-LA nanocarriers with 4 copies of lactic acid per molecule provided controlled release of lactic acid with a maximum release of 23% and 47% bound lactic acid in phosphate buffered saline (PBS, pH7.4) and acetate buffer (AB, pH4.3), respectively. The PEG nanocarrier-based hydrogels were formed by cross-linking the PEG-LA nanocarriers with 4-arm PEG-NHS via degradable thioester bonds. The nanocarrier-based hydrogels formed within 20 min under ambient conditions and exhibited an elastic modulus that was 100-fold higher than the viscous modulus. The nanocarrier-based degradable hydrogels provided controlled release of lactic acid for several hours; however, a maximum release of only 10%-14% bound lactic acid was observed possibly due to steric hindrance of the polymer chains in the cross-linked hydrogel. In contrast, hydrogels with passively entrapped lactic acid showed burst release with complete release within 30 min. Lactic acid showed antimicrobial activity against the primary BV pathogen Gardnerella vaginalis with a minimum inhibitory concentration (MIC) of 3.6 mg/ml. In addition, the hydrogels with passively entrapped lactic acid showed retained antimicrobial activity with complete inhibition G. vaginalis growth within 48 h. The results of the current study collectively demonstrate the potential of PEG nanocarrier-based hydrogels for vaginal administration of lactic acid for preventing and treating BV.

IgG in cervicovaginal mucus traps HSV and prevents vaginal herpes infections

IgG is the predominant immunoglobulin in cervicovaginal mucus (CVM), yet how immunoglobulin G (IgG) in mucus can protect against infections is not fully understood. IgG diffuses rapidly through cervical mucus, slowed only slightly by transient adhesive interactions with mucins. We hypothesize that this almost unhindered diffusion allows IgG to accumulate rapidly on pathogen surfaces, and the resulting IgG array forms multiple weak adhesive crosslinks to mucus gel that effectively trap (immobilize) pathogens, preventing them from initiating infections. Here, we report that herpes simplex virus serotype 1 (HSV-1) readily penetrated fresh, pH-neutralized ex vivo samples of CVM with low or no detectable levels of anti-HSV-1 IgG but was trapped in samples with even modest levels of anti-HSV-1 IgG. In samples with little or no endogenous anti-HSV-1 IgG, addition of exogenous anti-HSV-1 IgG, affinity-purified from intravenous immunoglobulin, trapped virions at concentrations below those needed for neutralization and with similar potency as endogenous IgG. Deglycosylating purified anti-HSV-1 IgG, or removing its Fc component, markedly reduced trapping potency. Finally, a non-neutralizing IgG against HSV-gG significantly protected mice against vaginal infection, and removing vaginal mucus by gentle lavage abolished protection. These observations suggest that IgG-Fc has a glycan-dependent "muco-trapping" effector function that may provide exceptionally potent protection at mucosal surfaces.

Vaginal delivery of paclitaxel via nanoparticles with non-mucoadhesive surfaces suppresses cervical tumor growth

Local delivery of chemotherapeutics in the cervicovaginal tract using nanoparticles may reduce adverse side effects associated with systemic chemotherapy, while improving outcomes for early-stage cervical cancer. It is hypothesized here that drug-loaded nanoparticles that rapidly penetrate cervicovaginal mucus (CVM) lining the female reproductive tract will more effectively deliver their payload to underlying diseased tissues in a uniform and sustained manner compared with nanoparticles that do not efficiently penetrate CVM. Paclitaxel-loaded nanoparticles are developed, composed entirely of polymers used in FDA-approved products, which rapidly penetrate human CVM and provide sustained drug release with minimal burst effect. A mouse model is further employed with aggressive cervical tumors established in the cervicovaginal tract to compare paclitaxel-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (conventional particles, or CP) and similar particles coated with Pluronic F127 (mucus-penetrating particles, or MPP). CP are mucoadhesive and, thus, aggregated in mucus, while MPP achieve more uniform distribution and close proximity to cervical tumors. Paclitaxel-MPP suppress tumor growth more effectively and prolong median survival of mice compared with unencapsulated paclitaxel or paclitaxel-CP. Histopathological studies demonstrate minimal toxicity to the cervicovaginal epithelia, suggesting paclitaxel-MPP may be safe for intravaginal use. These results demonstrate the in vivo advantages of polymer-based MPP for treatment of tumors localized to a mucosal surface.

Image-based noninvasive evaluation of colorectal mucosal injury in sheep after topical application of microbicides

BACKGROUND

Successful development of topical rectal microbicides requires preclinical evaluation in suitable large animal models. Our previous studies have demonstrated the benefits of high-resolution optical coherence tomography (OCT) to visualize subclinical microbicide toxicity in the sheep vagina. In the current study, we evaluated the potential application of colonoscopy and OCT to visualize and quantify the effects of topical products on sheep colorectal tissue, as assessed by advanced imaging techniques.

METHODS

Yearling virginal female sheep were treated rectally with a single 8-mL dose of 0.2% benzalkonium chloride (BZK) solution or phosphate-buffered saline control. Imaging was performed before and 30 minutes after treatment. Colonoscopy findings were evaluated based on mucosal disruption. Optical coherence tomography images were graded based on the integrity of the mucosal layer. Biopsies collected after treatment were evaluated by histology for validation of OCT scoring.

RESULTS

Mucosal disruption was observed by colonoscopy in BZK-treated animals, whereas none was present in controls. In contrast to colonoscopy, high-resolution in-depth OCT imaging provided visualization of the morphology of the mucosal layer and underlying muscularis, thus enabling detection of microscopic abnormalities. Noninvasive quantification of drug-induced injury after validation of the scoring system (categories 1, 2, 3) showed increased scores after treatment with BZK (P < 0.001), indicating mucosal injury.

CONCLUSIONS

High-resolution OCT can be used as highly sensitive tool to evaluate rectal microbicide effects. Because the sheep rectum has both gross and microscopic similarities to the human, this model is a useful addition to current methods of rectal product toxicity.

Nanoparticle-based drug delivery to the vagina: a review

Vaginal drug administration can improve prophylaxis and treatment of many conditions affecting the female reproductive tract, including sexually transmitted diseases, fungal and bacterial infections, and cancer. However, achieving sustained local drug concentrations in the vagina can be challenging, due to the high permeability of the vaginal epithelium and expulsion of conventional soluble drug dosage forms. Nanoparticle-based drug delivery platforms have received considerable attention for vaginal drug delivery, as nanoparticles can provide sustained release, cellular targeting, and even intrinsic antimicrobial or adjuvant properties that can improve the potency and/or efficacy of prophylactic and therapeutic modalities. Here, we review the use of polymeric nanoparticles, liposomes, dendrimers, and inorganic nanoparticles for vaginal drug delivery. Although most of the work toward nanoparticle-based drug delivery in the vagina has been focused on HIV prevention, strategies for treatment and prevention of other sexually transmitted infections, treatment for reproductive tract cancer, and treatment of fungal and bacterial infections are also highlighted.

Role of semen in altering the balance between inflammation and tolerance in the female genital tract: does it contribute to HIV risk?

While the main reproduction aim of semen is the transport of spermatozoa to the female genital tract, seminal plasma is a complex fluid that also carries a broad array of immunologically active molecules. Seminal plasma has been shown to contain a diverse array of anti-inflammatory and pro-inflammatory soluble mediators that regulate immune responses within the female reproductive tract than can facilitate fertilization. Since the natural inflammatory response to semen deposition in the female genital tract may result in recruitment of activated HIV target cells into the female genital mucosa, we discuss the constituents of semen that may increase the risk for HIV infection in women.

Cultivated vaginal microbiomes alter HIV-1 infection and antiretroviral efficacy in colonized epithelial multilayer cultures

There is a pressing need for modeling of the symbiotic and at times dysbiotic relationship established between bacterial microbiomes and human mucosal surfaces. In particular clinical studies have indicated that the complex vaginal microbiome (VMB) contributes to the protection against sexually-transmitted pathogens including the life-threatening human immunodeficiency virus (HIV-1). The human microbiome project has substantially increased our understanding of the complex bacterial communities in the vagina however, as is the case for most microbiomes, very few of the community member species have been successfully cultivated in the laboratory limiting the types of studies that can be completed. A genetically controlled ex vivo model system is critically needed to study the complex interactions and associated molecular dialog. We present the first vaginal mucosal culture model that supports colonization by both healthy and dysbiotic VMB from vaginal swabs collected from routine gynecological patients. The immortalized vaginal epithelial cells used in the model and VMB cryopreservation methods provide the opportunity to reproducibly create replicates for lab-based evaluations of this important mucosal/bacterial community interface. The culture system also contains HIV-1 susceptible cells allowing us to study the impact of representative microbiomes on replication. Our results show that our culture system supports stable and reproducible colonization by VMB representing distinct community state types and that the selected representatives have significantly different effects on the replication of HIV-1. Further, we show the utility of the system to predict unwanted alterations in efficacy or bacterial community profiles following topical application of a front line antiretroviral.

Animal models for microbicide safety and efficacy testing

PURPOSE OF REVIEW

Early studies have cast doubt on the utility of animal models for predicting success or failure of HIV-prevention strategies, but results of multiple human phase 3 microbicide trials, and interrogations into the discrepancies between human and animal model trials, indicate that animal models were, and are, predictive of safety and efficacy of microbicide candidates.

RECENT FINDINGS

Recent studies have shown that topically applied vaginal gels, and oral prophylaxis using single or combination antiretrovirals are indeed effective in preventing sexual HIV transmission in humans, and all of these successes were predicted in animal models. Further, prior discrepancies between animal and human results are finally being deciphered as inadequacies in study design in the model, or quite often, noncompliance in human trials, the latter being increasingly recognized as a major problem in human microbicide trials.

SUMMARY

Successful microbicide studies in humans have validated results in animal models, and several ongoing studies are further investigating questions of tissue distribution, duration of efficacy, and continued safety with repeated application of these, and other promising microbicide candidates in both murine and nonhuman primate models. Now that we finally have positive correlations with prevention strategies and protection from HIV transmission, we can retrospectively validate animal models for their ability to predict these results, and more importantly, prospectively use these models to select and advance even safer, more effective, and importantly, more durable microbicide candidates into human trials.

BLT humanized mice as model to study HIV vaginal transmission

The majority of human immunodeficiency virus type 1 (HIV-1) infections occur by sexual exposure, and vaginal transmission accounts for more than half of all newly acquired infections. Studies of vaginal transmission of simian immunodeficiency virus to nonhuman primates (NHPs) have suggested an important role for immune cell trafficking in the establishment of infection as well is in the process of viral dissemination. However, NHP models do not permit the study of HIV transmission and dissemination. The improvement of humanized mouse models with robust human immune cell reconstitution of the female genital tract renders these mice susceptible to intravaginal HIV infection. Thus humanized mouse models of HIV vaginal infection will allow the study of the mechanisms involved in HIV transmission and dissemination in vivo.

Vaginally delivered tenofovir disoproxil fumarate provides greater protection than tenofovir against genital herpes in a murine model of efficacy and safety

Increased susceptibility to genital herpes in medroxyprogesterone-treated mice may provide a surrogate of increased HIV risk and a preclinical biomarker of topical preexposure prophylaxis safety. We evaluated tenofovir disoproxil fumarate (TDF) in this murine model because an intravaginal ring eluting this drug is being advanced into clinical trials. To avoid the complications of surgically inserting a ring, hydroxyethylcellulose (HEC)-stable formulations of TDF were prepared. One week of twice-daily 0.3% TDF gel was well tolerated and did not result in any increase in HSV-2 susceptibility but protected mice from herpes simplex virus 2 (HSV-2) disease compared to mice treated with the HEC placebo gel. No significant increase in inflammatory cytokines or chemokines in vaginal washes or change in cytokine, chemokine, or mitochondrial gene expression in RNA extracted from genital tract tissue was detected. To further evaluate efficacy, mice were treated with gel once daily beginning 12 h prior to high-dose HSV-2 challenge or 2 h before and after viral challenge (BAT24 dosing). The 0.3% TDF gel provided significant protection compared to the HEC gel following either daily (in 9/10 versus 1/10 mice, P < 0.01) or BAT24 (in 14/20 versus 4/20 mice, P < 0.01) dosing. In contrast, 1% tenofovir (TFV) gel protected only 4/10 mice treated with either regimen. Significant protection was also observed with daily 0.03% TDF compared to HEC. Protection was associated with greater murine cellular permeability of radiolabeled TDF than of TFV. Together, these findings suggest that TDF is safe, may provide substantially greater protection against HSV than TFV, and support the further clinical development of a TDF ring.

HIV-1 infection of female genital tract tissue for use in prevention studies

OBJECTIVE

Ex vivo HIV-1 challenge has been proposed as a bioindicator of microbicide product effectiveness. The objective of this study was to establish optimal parameters for use of female genital tract tissue in this model.

DESIGN

Ex vivo challenge involves in vivo product use, followed by tissue biopsy, and exposure of the tissue to HIV-1 in the laboratory.

METHODS

Paired ectocervical and vaginal biopsies were collected from 42 women, and 28 women had additional biopsies from each site collected after 5% lidocaine (n = 14) or chlorhexidine (n = 14) treatment. Tissues were transported immediately to the laboratory and exposed to HIV-1. HIV-1 infection was followed by p24 enzyme-linked immunosorbent assay on culture supernatants and at study end after weighing and fixing the tissue for immunohistochemistry to detect p24 expressing cells.

RESULTS

Although both tissue types were equally infected with HIV-1 based on the immunohistochemistry results, ectocervical tissues had significantly higher HIV-1 replication than vaginal tissues (P < 0.005). Lidocaine and chlorhexidine had minimal impact on HIV-1 infection and replication. Point estimates for p24 levels were defined for 95% probability of p24-positive tissues and were 3.43 log10 for ectocervical tissue and 2.50 log10 for vaginal tissue based on the weight-adjusted cumulative p24 end points.

CONCLUSIONS

Although similar proportions of ectocervical and vaginal tissues support HIV-1 infection, higher levels of HIV-1 replication were observed in ectocervical tissues. Defining point estimates for HIV-1 infection in fresh ectocervical and vaginal tissues provides valuable information for the evaluation of HIV-1 preventative treatments during early clinical studies.

Convective diffusion of nanoparticles from the epithelial barrier toward regional lymph nodes

Drug delivery using nanoparticles as drug carriers has recently attracted the attention of many investigators. Targeted delivery of nanoparticles to the lymph nodes is especially important to prevent cancer metastasis or infection, and to diagnose disease stage. However, systemic injection of nanoparticles often results in organ toxicity because they reach and accumulate in all the lymph nodes in the body. An attractive strategy would be to deliver the drug-loaded nanoparticles to a subset of draining lymph nodes corresponding to a specific site or organ to minimize systemic toxicity. In this respect, mucosal delivery of nanoparticles to regional draining lymph nodes of a selected site creates a new opportunity to accomplish this task with minimal toxicity. One example is the delivery of nanoparticles from the vaginal lumen to draining lymph nodes to prevent the transmission of HIV in women. Other known examples include mucosal delivery of vaccines to induce immunity. In all cases, molecular and particle transport by means of diffusion and convective diffusion play a major role. The corresponding transport processes have common inherent regularities and are addressed in this review. Here we use nanoparticle delivery from the vaginal lumen to the lymph nodes as an example to address the many aspects of associated transport processes. In this case, nanoparticles penetrate the epithelial barrier and move through the interstitium (tissue) to the initial lymphatics until they finally reach the lymph nodes. Since the movement of interstitial liquid near the epithelial barrier is retarded, nanoparticle transport was found to take place through special foci present in the epithelium. Immediately after nanoparticles emerge from the foci, they move through the interstitium due to diffusion affected by convection (convective diffusion). Specifically, the convective transport of nanoparticles occurs due to their convection together with interstitial fluid through the interstitium toward the initial lymph capillaries. Afterwards, nanoparticles move together with the lymph flow along the initial lymph capillaries and then enter the afferent lymphatics and ultimately reach the lymph node. As the liquid moves through the interstitium toward the initial lymph capillaries due to the axial movement of lymph along the lymphatics, the theory for coupling between lymph flow and concomitant flow through the interstitium is developed to describe this general case. The developed theory is applied to interpret the large uptake of Qdots by lymph nodes during inflammation, which is induced by pre-treating mouse vagina with the surfactant Nonoxynol-9 prior to instilling the Qdots. Inflammation is viewed here to cause broadening of the pores within the interstitium with the concomitant formation of transport channels which function as conduits to transport the nanoparticles to the initial lymph capillaries. We introduced the term "effective channels" to denote those channels which interconnect with foci present in the epithelial barrier and which function to transport nanoparticles to initial lymph capillaries. The time of transport toward the lymph node, predicated by the theory, increases rapidly with increasing the distance y0 between the epithelial barrier and the initial lymph capillaries. Transport time is only a few hours, when y0 is small, about some R (where R is the initial lymph capillary radius), due to the predomination of a rather rapid convection in this case. This transport time to the lymph nodes may be tens of hours (or longer) when y0 is essentially larger and the slow diffusion controls the transport rate in a zone not far from the epithelial barrier, where convection is weak at large y0. Accounting for transport by diffusion only, which is mainly considered in many relevant publications, is not sufficient to explain our nanoparticle uptake kinetics because the possibility of fast transport due to convection is overlooked. Our systematic investigations have revealed that the information about the main transport conditions, namely, y0 and the pore broadening up to the dimension of the interstitial transport channels, is necessary to create the quantitative model of enhanced transport during inflammation with the use of the proposed model as a prerequisite. The modeling for convective diffusion of nanoparticles from the epithelial barrier to the lymph node has been mainly accomplished here, while the diffusion only scenario is accounted for in other studies. This first modeling is a semi-quantitative one. A more rigorous mathematical approach is almost impossible at this stage because the transport properties of the model are introduced here for the first time. These properties include: discovery of foci in the epithelium, formation of transport channels, definition of channels interconnecting with foci (effective foci and channels), generation of flow in the interstitium toward the initial lymph capillaries due to axial flow within afferent lymphatics, deformation of this flow due to hydrodynamic impermeability of the squamous layer with the formation of the hydrodynamic stagnation zone near the epithelial barrier, predomination of slow diffusion transport within the above zone, and predomination of fast convection of nanoparticles near the initial lymph capillaries.

Drug-induced reactivation of apoptosis abrogates HIV-1 infection

HIV-1 blocks apoptosis, programmed cell death, an innate defense of cells against viral invasion. However, apoptosis can be selectively reactivated in HIV-infected cells by chemical agents that interfere with HIV-1 gene expression. We studied two globally used medicines, the topical antifungal ciclopirox and the iron chelator deferiprone, for their effect on apoptosis in HIV-infected H9 cells and in peripheral blood mononuclear cells infected with clinical HIV-1 isolates. Both medicines activated apoptosis preferentially in HIV-infected cells, suggesting that the drugs mediate escape from the viral suppression of defensive apoptosis. In infected H9 cells, ciclopirox and deferiprone enhanced mitochondrial membrane depolarization, initiating the intrinsic pathway of apoptosis to execution, as evidenced by caspase-3 activation, poly(ADP-ribose) polymerase proteolysis, DNA degradation, and apoptotic cell morphology. In isolate-infected peripheral blood mononuclear cells, ciclopirox collapsed HIV-1 production to the limit of viral protein and RNA detection. Despite prolonged monotherapy, ciclopirox did not elicit breakthrough. No viral re-emergence was observed even 12 weeks after drug cessation, suggesting elimination of the proviral reservoir. Tests in mice predictive for cytotoxicity to human epithelia did not detect tissue damage or activation of apoptosis at a ciclopirox concentration that exceeded by orders of magnitude the concentration causing death of infected cells. We infer that ciclopirox and deferiprone act via therapeutic reclamation of apoptotic proficiency (TRAP) in HIV-infected cells and trigger their preferential elimination. Perturbations in viral protein expression suggest that the antiretroviral activity of both drugs stems from their ability to inhibit hydroxylation of cellular proteins essential for apoptosis and for viral infection, exemplified by eIF5A. Our findings identify ciclopirox and deferiprone as prototypes of selectively cytocidal antivirals that eliminate viral infection by destroying infected cells. A drug-based drug discovery program, based on these compounds, is warranted to determine the potential of such agents in clinical trials of HIV-infected patients.

Effects of benzalkonium chloride on THP-1 differentiated macrophages in vitro

Purpose

To characterize the effects of benzalkonium chloride (BAK) in THP-1 differentiated cells in vitro.

Methods

Macrophages were obtained after differentiation of THP-1 cells, a human monocytic leukemia cell line. Macrophages were exposed for 24 h to 33 nM (10⁻⁵%) benzalkonium chloride (BAK), 10 nM dinitrochlorobenzene (DNCB), 100 ng/mL lipopolysaccharide (LPS), 5 ng/mL tumor necrosis factor alpha (TNF-α) or phosphate buffered saline (PBS) as controls. The expression of CD11b, CD11c, CD33 and CD54 was evaluated using immunohistochemistry and flow cytometry (FCM). Phagocytosis function was analyzed using carboxylate-modified fluorescent microspheres and quantified by FCM. Migration was evaluated in cocultures with conjunctival epithelial cells. Cytokine production was detected and quantified in culture supernatants using a human cytokine array.

Results

Stimulation of THP-1-derived macrophages with a low concentration of BAK increased CD11b and CD11c expression and decreased CD33. Macrophages exposed to BAK, LPS and TNF-α had increased phagocytosis. In contrast to LPS, BAK and TNF-α increased macrophage migration. Cytokines in supernatants of macrophages exposed to BAK revealed an increased release of CCL1, CCL4/MIP-1β, TNF-α, soluble CD54/ICAM-1 and IL-1β.

Conclusion

In vitro, BAK has a direct stimulating effect on macrophages, increasing phagocytosis, cytokine release, migration and expression of CD11b and CD11c. Long-term exposure to low concentrations of BAK should be considered as a stimulating factor responsible for inflammation through macrophage activation.

Enhanced vaginal drug delivery through the use of hypotonic formulations that induce fluid uptake

Mucosal epithelia use osmotic gradients for fluid absorption and secretion. We hypothesized that administration of hypotonic solutions would induce fluid uptake that could be advantageous for rapidly delivering drugs through mucus to the vaginal epithelium. We found that hypotonic formulations markedly increased the rate at which small molecule drugs and mucoinert nanoparticles (mucus-penetrating particles, or MPP), but not conventional mucoadhesive nanoparticles (CP), reached the vaginal epithelial surface in vivo in mice. Additionally, hypotonic formulations greatly enhanced drug and MPP delivery to the entire epithelial surface, including deep into the vaginal folds (rugae) that drugs or MPP in isotonic formulations failed to reach efficiently. However, hypotonic formulations caused unencapsulated "free" drugs to be drawn through the epithelium, reducing vaginal retention. In contrast, hypotonic formulations caused MPP to accumulate rapidly and uniformly on vaginal surfaces, ideally positioned for localized sustained drug delivery. Using a mouse model of vaginal genital herpes (HSV-2) infection, we found that hypotonic delivery of free drug led to improved immediate protection, but diminished longer-term protection. In contrast, as we previously demonstrated, hypotonic delivery of drug via MPP led to better long-term retention and protection in the vagina. Importantly, we demonstrate that slightly hypotonic formulations provided rapid and uniform delivery of MPP to the entire vaginal surface, thus enabling formulations with minimal risk of epithelial toxicity. Hypotonic formulations for vaginal drug delivery via MPP may significantly improve prevention and treatment of reproductive tract diseases and disorders.

Antibody and antiretroviral preexposure prophylaxis prevent cervicovaginal HIV-1 infection in a transgenic mouse model

The development of an effective vaccine preventing HIV-1 infection remains elusive. Thus, the development of novel approaches capable of preventing HIV-1 transmission is of paramount importance. However, this is partly hindered by the lack of an easily accessible small-animal model to rapidly measure viral entry. Here, we report the generation of a human CD4- and human CCR5-expressing transgenic luciferase reporter mouse that facilitates measurement of peritoneal and genitomucosal HIV-1 pseudovirus entry in vivo. We show that antibodies and antiretrovirals mediate preexposure protection in this mouse model and that the serum antibody concentration required for protection from cervicovaginal infection is comparable to that required to protect macaques. Our results suggest that this system represents a model for the preclinical evaluation of prophylactic or vaccine candidates. It further supports the idea that broadly neutralizing antibodies should be evaluated for use as preexposure prophylaxis in clinical trials.

Optical coherence tomography for assessment of microbicide safety in a small animal model

Sensitive imaging techniques for small animals are needed to assess drug toxicity in preclinical studies. Optical coherence tomography (OCT) provides a noninvasive tool for high-resolution, depth-resolved visualization of drug-induced changes in tissue morphology. In a mouse model, we utilize OCT to assess vaginal tissue integrity following the application of topical microbicides (drugs used to prevent infection). Mice are challenged with herpes simplex virus-2 (HSV-2) to determine the correlation of tissue damage as quantified by OCT to increased susceptibility. The microbicide benzalkonium chloride (BZK) (0.02, 0.2, or 2%) or phosphate buffered saline control is administered intravaginally. In vivo OCT imaging and collection of tissue samples are performed after treatment. A quantitative OCT scoring system is applied to assess epithelial damage, and the results are compared with those of histology. A separate group of mice are treated similarly then challenged with HSV-2. Epithelial morphology quantified noninvasively by OCT and histology are dose-dependent (p<0.0001). The OCT scoring system detected a significant increase in epithelial damage with increasing BZK concentration (p<0.0001). These results paralleled an increase in HSV-2 susceptibility (p<0.005). OCT can be used as a noninvasive tool to assess topical drug toxicity in a small animal model with potential to predict increased susceptibility to vaginal infection.

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.

Innate and adaptive anti-HIV immune responses in the female reproductive tract

The mucosal surface of the female reproductive tract (FRT) is the primary site of transmission for a plethora of sexually transmitted infections, including human immunodeficiency virus (HIV), that represent a significant burden upon womens' health worldwide. However, fundamental aspects of innate and adaptive immune protection against HIV infection in the FRT are poorly understood. The FRT immune system is regulated by the cyclical changes of the sex hormones estradiol and progesterone across the menstrual cycle, which as we have hypothesized, leads to the creation of a window of vulnerability during the secretory stage of the menstrual cycle, when the risk of HIV transmission is increased. The goal of this review is to summarize the multiple levels of protection against HIV infection in the FRT, the contribution of different cell types including epithelial cells, macrophages, T cells, and dendritic cells to this, and their regulation by estradiol and progesterone. Understanding the unique immune environment in the FRT will allow for the potential development of novel therapeutic interventions such as vaccines and microbicides that may reduce or prevent HIV transmission in women.

Nanoparticle transport from mouse vagina to adjacent lymph nodes

To test the feasibility of localized intravaginal therapy directed to neighboring lymph nodes, the transport of quantum dots across the vaginal wall was investigated. Quantum dots instilled into the mouse vagina were transported across the vaginal mucosa into draining lymph nodes, but not into distant nodes. Most of the particles were transported to the lumbar nodes; far fewer were transported to the inguinal nodes. A low level of transport was evident at 4 hr after intravaginal instillation, and transport peaked at about 36 hr after instillation. Transport was greatly enhanced by prior vaginal instillation of Nonoxynol-9. Hundreds of micrograms of nanoparticles/kg tissue (ppb) were found in the lumbar lymph nodes at 36 hr post-instillation. Our results imply that targeted transport of microbicides or immunogens from the vagina to local lymph organs is feasible. They also offer an in vivo model for assessing the toxicity of compounds intended for intravaginal use.