Hyperosmolal vaginal lubricants markedly reduce epithelial barrier properties in a three-dimensional vaginal epithelium model

Formulation development of dual-compartment topical inserts combining tenofovir alafenamide and elvitegravir for flexible on-demand HIV prevention

Pre-exposure prophylaxis (PrEP) has emerged as a prominent approach for the prevention of HIV infections. While the latest advances have resulted in effective oral and injectable product options, there are still gaps in on-demand, event-driven, topical products for HIV prevention that are safe and effective. Here we describe the formulation development of a dual-compartment topical insert containing tenofovir alafenamide fumarate (TAF) and elvitegravir (EVG) that may be administered when needed, vaginally or rectally, pre- or post-coitus, for flexible HIV prophylaxis. Specifically, we describe the lab-scale formulation development, preclinical mucosal safety and pharmacokinetics (PK) testing in rabbits, long-term stability, and scale-up clinical manufacturing of the lead TAF/EVG (20 mg/16 mg) inserts, which are currently in clinical stages of development. As designed, the inserts are small, discreet and portable, offering a number of promising attributes, such as simple and robust direct-compression manufacturing, fast initial disintegration/dissolution, and suitable mechanical strengths showing low hardness (<8 kg), friability (<1 %), and moisture content (<1 %). The inserts initiated disintegration quickly (∼ ≤ 15 min) providing full in vitro release (>90 %) of TAF and EVG within 60 min of dissolution. The lead insert was selected from formulation prototypes that met the evaluation criteria for manufacturability and characterization, along with a dose-ranging PK study in non-human primates. Successful technology transfer for clinical development of the lead TAF/EVG (20 mg/16 mg) insert was confirmed under current Good Manufacturing Practices (cGMP) conditions. Based on the 12 months (lab-scale) and 24 months (clinical batch) stability data, the TAF/EVG inserts are projected to have a long shelf life of over 2 years, if stored at or below 30 °C/65 % RH. Overall, these newly designed topical inserts have formulation properties that enable stable storage and fast release of the antiretroviral payload from a small, portable and discreet dosage form. They are safe and effective when applied vaginally or rectally, before or after coitus, providing the basis for a new method of flexible on-demand HIV prevention for cisgender and transgender women and men. The TAF/EVG inserts are currently the most clinically advanced on-demand topical product, as attested by their completed and ongoing clinical trials.

Assessment of the vaginal microbiota before and after use of hyperosmolal lubricant during transvaginal ultrasound

BACKGROUND

Vaginal lubricants are commonly used during sexual activity and clinical procedures such as transvaginal ultrasound. Epidemiologic and laboratory studies indicate hyperosmolal water-based lubricants may disrupt the vaginal microbiota, particularly the beneficial Lactobacillus spp. These bacteria play a critical role in protecting against sexually transmitted infection acquisition and other adverse gynecologic and obstetric outcomes.

OBJECTIVE

We sought to evaluate changes in the composition of the vaginal microbiota before and after a single exposure to lubricant over a 10-week period among pre-, peri-, and postmenopausal patients referred for transvaginal ultrasound.

STUDY DESIGN

One hundred four participants self-collected mid-vaginal swabs daily between baseline and transvaginal ultrasound (∼1 week), immediately before transvaginal ultrasound ("pre-transvaginal ultrasound"), and 6 to 12 hours after transvaginal ultrasound ("post-transvaginal ultrasound"). Participants attended a follow-up visit ∼2 to 5 days after transvaginal ultrasound ("post-transvaginal ultrasound follow-up"), continued to self-sample twice-weekly for 9 weeks, and attended a final clinical visit in week 10. Microbiota composition was characterized by 16S ribosomal RNA gene amplicon sequencing (V3-V4) and assigned to community state types (low-Lactobacillus vs Lactobacillus-dominated). Yue-Clayton theta indices defined similarity between daily successive samples between baseline and transvaginal ultrasound and overall stability of the vaginal microbiota before and after transvaginal ultrasound. Analysis of Compositions of Microbiomes II determined differentially abundant taxa in post-transvaginal ultrasound samples vs pre-transvaginal ultrasound samples. Generalized linear mixed models evaluated the odds of having a low-Lactobacillus microbiota after transvaginal ultrasound with samples before transvaginal ultrasound as the reference for each participant.

RESULTS

A majority of the cohort was premenopausal (85/104, 82%) and self-reported Black race (65/104, 62%). Over the short-term (1 week), there was no immediate changes in the composition of the microbiota of daily successive samples following transvaginal ultrasound. In contrast, over the longer-term (participants followed for 10 weeks), the vaginal microbiota was less stable within intervals after transvaginal ultrasound vs the interval before. There were no changes in the odds of a low-Lactobacillus microbiota after transvaginal ultrasound among all participants in this 10-week longitudinal study. However, in specific groups such as peri/postmenopausal participants (N=19, adjusted odds ratio: 3.22, 95% confidence interval:1.16-8.98) and those with a history of bacterial vaginosis (N=58, adjusted odds ratio: 1.73, 95% confidence interval:1.10-2.72), there was a higher likelihood of persisting in a low-Lactobacillus state throughout the follow-up period.

CONCLUSION

Peri- and postmenopausal individuals and those with a history of bacterial vaginosis show a sustained decrease in protective Lactobacillus spp. after a single exposure to hyperosmolal vaginal lubricant. Reformulating water-based lubricants to reduce osmolality and toxicity may be beneficial.

A simple and affordable open-source quantitative tribometric assay and the use thereof for the analysis of a commercial water-based lubricant

Quantitative assessment of biotribological properties requires expensive specialized equipment. The aim was to: i) adapt an open-source load cell-based platform (PASTA) for biotribometric analysis; ii) study the effects of oxidation on the water-based lubricant using PASTA. Water-based lubricant was treated with 2,2'-azobis(2-amidinopropane) dihydrochloride and/or glutathione. The samples were analyzed with the ORP-146S redox microsensor and PASTA using a modified HX711 integrated circuit bord, NodeMCU ESP-32S, and an open-source Python script. PASTA can be adapted for affordable and reliable quantitative biotribometric assessment. Glutathione can prevent the loss of lubrication capacity of a water-based lubricant upon exposure to air.

Hypotonic, gel-forming delivery system for vaginal drug administration

Vaginal drug delivery is often preferred over systemic delivery to reduce side effects and increase efficacy in treating diseases and conditions of the female reproductive tract (FRT). Current vaginal products have drawbacks, including spontaneous ejection of drug-eluting rings and unpleasant discharge from vaginal creams. Here, we describe the development and characterization of a hypotonic, gel-forming, Pluronic-based delivery system for vaginal drug administration. The rheological properties were characterized with and without common hydrogel polymers to demonstrate the versatility. Both qualitative and quantitative approaches were used to determine the Pluronic F127 concentration below the critical gel concentration (CGC) that was sufficient to achieve gelation when formulated to be hypotonic to the mouse vagina. The hypotonic, gel-forming formulation was found to form a thin, uniform gel layer along the vaginal epithelium in mice, in contrast to the rapidly forming conventional gelling formulation containing polymer above the CGC. When the hypotonic, gel-forming vehicle was formulated in combination with a progesterone nanosuspension (ProGel), equivalent efficacy was observed in the prevention of chemically-induced preterm birth (PTB) compared to commercial Crinone® vaginal cream. Further, ProGel showed marked benefits in reducing unpleasant discharge, reducing product-related toxicity, and improving compatibility with vaginal bacteria in vitro. A hypotonic, gel-forming delivery system may be a viable option for therapeutic delivery to the FRT.

Phase transforming in situ gels for sustained and controlled transmucosal drug delivery via the intravaginal route

Direct, reliable, controlled, and sustained drug delivery to female reproductive tract (FRT) remains elusive, with conventional dosage forms falling way short of the mark, leading to premature leakage, erratic drug delivery, and loss of compliance. Historically, the intravaginal route remains underserved by the pharmaceutical sector. To comprehensively address this, we turned our focus to phase-transforming sol-gels, using poloxamers, a thermosensitive polymer and, doxycycline (as hyclate salt, DOXH) as our model agent given its potential use in sexually transmitted infections (STIs). We further enhanced mucoadhesiveness through screening of differing viscosity grade hydroxypropyl methyl celluloses (HPMCs). The optimised sol-gels remained gelled at body temperature (<37 °C) and were prepared in buffer aligned to vaginal cavity pH and osmolality. Lead formulations were progressed based on their ability to retain key rheological properties, and acidic pH in the presence of simulated vaginal fluid (SVF). From a shelf-life perspective, DOXH stability, gelation temperature (Tsol-gel), and pH to three months (2-8 °C) was attained. In summary, the meticulously engineered, phase-transforming sol-gels provided sustained mucoretention despite dilution by vaginal fluid, paving the way for localised antimicrobial drug delivery at concentrations that potentially far exceed the minimum inhibitory concentration (MIC) for target STI-causing bacteria of the FRT.

Non Clinical Model to Assess the Mechanism of Action of a Combined Hyaluronic Acid, Chondroitin Sulfate and Calcium Chloride: HA+CS+CaCl2 Solution on a 3D Human Reconstructed Bladder Epithelium

Purpose

Medical Device Regulation (EU) 2017/745 requires the principal mode of action (MoA) to be demonstrated by experimental data. The MoA of Ialuril® Prefill (combined as HA+CS+CaCl2: sodium hyaluronate 1.6%, sodium chondroitin sulphate 2% w/v and calcium chloride 0.87%) Class III medical device, indicated for intravesical instillation to reduce urinary tract infections, has been evaluated on a 3D reconstructed human bladder epithelium (HBE).

Methods

Three experimental designs; i) E. coli strain selection (DSM 103538, DSM 1103) to investigate the HA+CS+CaCl2 properties in modifying bacterial growth in liquid broth (CFU 4h and 24h) at 80%, 50% and 25% concentrations; ii) evaluation of film forming properties on HBE after 15 min exposure by quantifying caffeine permeation across the epithelium; iii) capacity to counteract E. coli adhesion and biofilm formation on colonized HBE by viable counts and ultrastructural analysis by scanning electron microscopy (SEM) using ciprofloxacin as the reference antimicrobial molecule.

Results

No significant differences were observed in bacterial viability for both the E. coli strains. HA+CS+CaCl2 reduced caffeine permeation of 51.7% and 38.1% at 1h and 2h, respectively and determined a significant decrease in caffeine permeation rate at both timepoints supporting HA+CS+CaCl2 capacity to firmly adhere to the bladder epithelium creating a physical barrier on the surface. The viable counts in HBE treated tissues then infected with E. coli resulted not different from the negative control suggesting that the device did not inhibit E. coli growth. SEM images showed homogenous product distribution over the HBE surface and confirmed the capacity of HA+CS+CaCl2 to adhere to the bladder epithelium, counteracting biofilm formation.

Conclusion

The results support the capacity of HA+CS+CaCl2 to counteract bacterial invasion by using a physico-mechanical mode of action: this medical device represents a valid alternative to antibiotics in the treatment of recurrent UTIs.

Investigating the impact of condomless vaginal intercourse and lubricant use on the vaginal metabolome: a pre-post observational study

OBJECTIVE

The vaginal metabolome is a significant factor in the vaginal microenvironment, and data are emerging on its independent role in urogenital health. Condomless vaginal intercourse and personal lubricant use are common practices that may affect the vaginal metabolome. The aim of the present study is to describe the associations between condomless intercourse and lubricant use on the vaginal metabolome.

METHODS

This study used archived mid-vaginal swabs from a 10-week observational cohort of reproductive age women who self-collected samples and recorded behavioural diaries daily. Cases and controls were defined as participants who self-reported condomless vaginal intercourse with or without lubricant use, respectively. Samples were drawn prior to and following condomless vaginal intercourse. Twenty-two case participants were race/ethnicity matched to 22 control participants. Mid-vaginal swabs were subjected to 16S rRNA gene amplicon sequencing and untargeted ultrahigh performance liquid chromatography tandem mass spectroscopy metabolomics. Bayesian mixed-effects regression (unadjusted and adjusted for the vaginal microbiota) was used to evaluate differences in metabolite concentration associated with vaginal intercourse and lubricant use.

RESULTS

Both condomless penile-vaginal intercourse and lubricant use were independently associated with higher (up to 8.3-fold) concentrations of metabolites indicative of epithelial damage (eg, sarcosine) and many host-produced antioxidants. Lubricant use was significantly associated with increases in lipids related to cellular damage, host-produced sphingolipids (antimicrobials), antioxidants and salicylate, a cooling agent common to lubricants, in a study design which controls for the independent effect of intercourse. Metabolites involved in oxidative stress and salicylate were strongly correlated with several molecular bacterial vaginosis-associated bacteria.

CONCLUSIONS

This study provides important foundational data on how condomless vaginal-penile intercourse and lubricant use affect the vaginal metabolome and may affect the protective mechanisms in the vaginal microenvironment.

Hydrogels for Mucosal Drug Delivery

Mucosal tissues are often a desirable site of drug action to treat disease and engage the immune system. However, systemically administered drugs suffer from limited bioavailability in mucosal tissues where technologies to enable direct, local delivery to these sites would prove useful. In this Spotlight on Applications article, we discuss hydrogels as an attractive means for local delivery of therapeutics to address a range of conditions affecting the eye, nose, oral cavity, gastrointestinal, urinary bladder, and vaginal tracts. Considering the barriers to effective mucosal delivery, we provide an overview of the key parameters in the use of hydrogels for these applications. Finally, we highlight recent work demonstrating their use for inflammatory and infectious diseases affecting these tissues.

Vaginal Sheets with Thymbra capitata Essential Oil for the Treatment of Bacterial Vaginosis: Design, Characterization and In Vitro Evaluation of Efficacy and Safety

We aimed to incorporate Thymbra capitata essential oil (TCEO), a potent antimicrobial natural product against bacterial vaginosis (BV)-related bacteria, in a suitable drug delivery system. We used vaginal sheets as dosage form to promote immediate relief of the typical abundant vaginal discharge with unpleasant odour. Excipients were selected to promote the healthy vaginal environment reestablishment and bioadhesion of formulations, while the TCEO acts directly on BV pathogens. We characterized vaginal sheets with TCEO in regard to technological characterization, predictable in vivo performance, in vitro efficacy and safety. Vaginal sheet D.O (acid lactic buffer, gelatine, glycerine, chitosan coated with TCEO 1% w/w) presented a higher buffer capacity and ability to absorb vaginal fluid simulant (VFS) among all vaginal sheets with EO, showing one of the most promising bioadhesive profiles, an excellent flexibility and structure that allow it to be easily rolled for application. Vaginal sheet D.O with 0.32 µL/mL TCEO was able to significantly reduce the bacterial load of all in vitro tested Gardnerella species. Although vaginal sheet D.O presented toxicity at some concentrations, this product was developed for a short time period of treatment, so this toxicity can probably be limited or even reversed when the treatment ends.

A randomized trial on the effectiveness and safety of 5 water-based personal lubricants

BACKGROUND

A range of personal lubricants with different formulations and subsequent properties are available for relief of discomfort associated with vaginal dryness; however, there are limited clinical data to support the efficacy and safety of many commercially available lubricants.

AIM

To determine the effectiveness and safety of 5 water-based personal lubricants for the relief of intimate discomfort associated with vaginal dryness in pre- and postmenopausal women: 4 that were formulated to meet the World Health Organization (WHO) guidelines for osmolality and pH and 1 preexisting lubricant of higher osmolality and pH.

METHODS

An open-label, parallel-design study was performed in women aged 18 to 65 years with mild-to-moderate vaginal dryness and dyspareunia. Participants were randomized to 1 of 5 lubricants (A-E) from 3 brands (Durex, KY, Queen V). They were instructed to use their allocated lubricants during vaginal intercourse at least once a week over a 4-week period. The Female Sexual Function Index (FSFI) measured sexual functioning after 4 weeks of use as an indicator of lubricant performance.

OUTCOMES

The primary outcome was change from baseline in total FSFI score after 4 weeks of product use.

RESULTS

A total of 174 women completed the study. The primary end point-a prespecified increase in FSFI ≥4 points from baseline after 4 weeks of use-was met by all 5 lubricants tested. A statistically significant improvement was observed across all 6 domains of the FSFI from baseline to 4 weeks of use with all 5 lubricants (P < .0001 for lubrication and pain reduction and P < .05 for all other domains). No serious adverse events occurred in the study, and the tolerance of all 5 lubricants was good/very good.

CLINICAL IMPLICATIONS

The efficacy and safety of the tested lubricants are not compromised when formulated to meet the WHO criterion of osmolality ≤1200 mOsm/kg. The lubricants tested in this investigation can be used not only to relieve symptomatology of vaginal dryness and dyspareunia but also to enhance overall sexual satisfaction.

STRENGTHS AND LIMITATIONS

This study provides clinical evidence for the efficacy and safety of 5 lubricants, including those formulated to meet WHO guidelines, in relieving symptoms of vaginal dryness and improving the overall sexual experience. The open-label design may have introduced bias into the study.

CONCLUSION

All 5 lubricants, including those formulated to be compliant with guidelines on pH and osmolality, can be considered effective and well tolerated for the relief of discomfort associated with vaginal dryness.

Characterization of an air-liquid interface primary human vaginal epithelium to study Ebola virus infection and testing of antivirals

Ebola virus (EBOV) is the causative agent of the often-fatal Ebola virus disease (EVD) characterized by hemorrhagic fever in humans and non-human primates. Sexual transmission from male survivors has been at the origin of multiple outbreak flare-ups between 2015 and 2021. However, this route is still poorly understood and the resulting EVD from it is also understudied. To support epidemiological studies documenting sexual transmission to women, and as a transition from previously using monolayer vaginal epithelial cells (VK2/E6E7), we first determined the biological relevance of two similar air-liquid interface models of the human vaginal epithelium (VEC and VLC Epivaginal™) and then characterized their susceptibility to EBOV and virus-induced inflammation. Finally, we evaluated toxicity of Polyphenylene Carboxymethylene (PPCM) microbicide in VLC and reassessed its antiviral effect. As expected, the VEC, but also VLC model showed stratified layers including a lamina propria under an epithelial structure similar to the full thickness of the human vaginal epithelium. However, we could not detect the immune cells featured in the most relevant model (VLC) of the vaginal epithelium using the dendritic cell CD1a and CD11c markers. Consistent with our previous work using the VK2/E6E7 cell line, infectious virus was detected from the apical side of both primary human cell systems, but only when using a high infective dose, with titers remaining at a constant level of 103-4 pfu/ml over 7 days suggesting lasting infectious virus shedding. In addition, infection caused disruption of the epithelium of both models and virus antigen was found from the apical superficial layers down to the lamina propria suggesting full virus penetration and overall confirming the susceptibility of the human vaginal tissue for EBOV. Just like previously seen in VK2/E6E7 cells, VLC infection also caused significant increase in inflammatory markers including IL-6, IL-8, and IP-10 suggesting vaginitis which is again consistent with tissue lesions seen in non-human primates. Finally, both virus infection and virus-induced inflammatory response in VLC could be prevented by a single 5-min PPCM microbicide treatment prior infection.

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.

The association between vaginal hygiene practices and spontaneous preterm birth: A case-control study

BACKGROUND

Spontaneous preterm birth (SPTB) is a major cause of neonatal morbidity and mortality worldwide and defining its risk factors is necessary to reduce its prevalence. Recent studies have pointed out that bacterial vaginosis, a disturbance in the vaginal microbiome, is associated with SPTB. It is hypothesized that vaginal hygiene practices can alter the vaginal microbiome and are therefore associated with SPTB, but there are no studies investigating this matter.

METHODS AND FINDINGS

A case-control study was conducted between August 2018 and July 2021 in two affiliated university medical centers in Amsterdam, the Netherlands. We included a total of 79 women with a SPTB and compared them with 156 women with a term birth. Women with uterine anomalies, a history of cervical surgery or major congenital anomalies of the fetus were excluded. All participants filled in a questionnaire about vaginal washing with water, soap or gel, the use of intravaginal douches and vaginal steaming, both before and during pregnancy. Most women washed vaginally with water, 144 (61.3%) women before pregnancy and 135 (57.4%) women during pregnancy. A total of 43 (18.3%) washed with soap before and 36 (15.3%) during pregnancy. Before pregnancy, 40 (17.0%) women washed with vaginal gel and 27 (11.5%) during pregnancy. We found that the use of vaginal gel before pregnancy (aOR 2.29, 95% CI: 1.08-4.84) and even more during pregnancy, was associated with SPTB (aOR 3.45, 95% CI: 1.37-8.67). No association was found between washing with water or soap, intravaginal douching, or vaginal steaming and SPTB.

CONCLUSIONS

Our findings suggest that the use of vaginal gel is associated with SPTB. Women should be informed that vaginal use of gels might not be safe.

The Impact of Over-The-Counter Lactic Acid Containing Vaginal Gels on the Integrity and Inflammatory State of the Vaginal Epithelium in vitro

The vaginal microbiome influences a wide range of health outcomes in women, where a microbiome dominated by Lactobacillus spp. is considered optimal and associated with reduced risk of pre-term birth and acquisition of sexually transmitted infections including HIV. Conversely, replacement of lactobacilli by non-optimal bacteria leads to the development of bacterial vaginosis, which is associated with increased risk of these outcomes. Lactobacilli produce the metabolite lactic acid (LA) which is a potent antibacterial and antiviral agent. The potential therapeutic benefits of LA have prompted the development of numerous over-the-counter LA-containing gels for use in the vagina, although a comprehensive analysis of the impact of these formulations on the cervicovaginal epithelium and pro-inflammatory cytokine/chemokine responses, has not been assessed. Here, we evaluated the properties of 11 over-the-counter gels, including 9 containing LA, marketed for use in the vagina. Ten of the 11 gels had an osmolality greater than vaginal fluid from women with Lactobacillus-dominated microbiota (370 ± 40 mOsmol/kg in women with Nugent score 0-3), with six gels that were hyperosmolal >2,000 mOsmol/kg. Using a reconstructed primary cell model of the vaginal epithelium, we found hyperosmolal gels had a detrimental impact on epithelial barrier integrity, resulting in substantial cellular toxicity (<10% viability as compared to untreated cells) and reduced epithelial barrier integrity [≈30% of untreated cells, assessed by transepithelial electrical resistance (TEER)]. Treatment of vaginal tissues with most of the gels elicited the production of pro-inflammatory factors including IL-1α (8 of 11) and IL-1β (10 of 11) which are associated with heightened risk of HIV acquisition in vivo. The majority of the OTC gels elicited moderate tissue damage as determined by histology. The detrimental effects of these gels on the human vaginal epithelium in vitro may predict compromised epithelial barrier integrity and genital inflammation in vivo, which has implications for sexual and reproductive health. This study highlights the importance of evaluating the impact of intravaginal products on the integrity and inflammatory status of the mucosal epithelium to avoid unfavorable off target effects.

Toxicity Assessment of Resveratrol Liposomes-in-Hydrogel Delivery System by EpiVaginalTM Tissue Model

The natural polyphenol resveratrol (RES) has shown great potential as an antimicrobial, including against microbes associated with vaginal infections. To fully exploit the activities of RES, an all-natural ingredients formulation for RES delivery at vaginal site has been developed, namely liposomes loaded with RES, incorporated into a chitosan hydrogel as secondary vehicle. Although considered non-toxic and safe on their own, the compatibility of the final formulation must be evaluated for its biocompatibility and non-irritancy to the vaginal mucosa. As a preclinical safety assessment, the impact of RES formulation on the tissue viability, the effect on barrier function and cell monolayer integrity, and cytotoxicity were evaluated using the cell-based vaginal tissue model, the EpiVaginal™ tissue. RES liposomes-in-hydrogel formulations neither affected the mitochondrial activity, nor the integrity of the cell monolayer in RES concentration up to 60 µg/mL. Moreover, the barrier function was maintained to a greater extent by RES in formulation, emphasizing the benefits of the delivery system. Additionally, none of the tested formulations expressed an increase in lactate dehydrogenase activity compared to the non-treated tissues. The evaluation of the RES delivery system suggests that it is non-irritant and biocompatible with vaginal tissue in vitro in the RES concentrations considered as therapeutic.

Inhaled antibodies: Quality and performance considerations

The use of antibodies in the treatment of lung diseases is of increasing interest especially as the search for COVID-19 therapies has unfolded. Historically, the use of antibody therapy was based on multiple targets including receptors involved in local hyper-reactivity in asthma, viruses and micro-organisms involved in a variety of pulmonary infectious disease. Generally, protein therapeutics pose challenges with respect to formulation and delivery to retain activity and assure therapy. The specificity of antibodies amplifies the need for attention to molecular integrity not only in formulation but also during aerosol delivery for pulmonary administration. Drug product development can be viewed from considerations of route of administration, dosage form, quality, and performance measures. Nebulizers and dry powder inhalers have been used to deliver protein therapeutics and each has its advantages that should be matched to the needs of the drug and the disease. This review offers insight into quality and performance barriers and the opportunities that arise from meeting them effectively.

Development and Preclinical Investigation of Physically Cross-Linked and pH-Sensitive Polymeric Gels as Potential Vaginal Contraceptives

This study explored the development of cross-linked gels to potentially provide a physical barrier to vaginal sperm transport for contraception. Two types of gels were formulated, a physically cross-linked iota-carrageenan (Ci) phenylboronic acid functionalized hydroxylpropylmethyacrylate copolymer (PBA)-based (Ci-PBA) gel, designed to block vaginal sperm transport. The second gel was pH-shifting cross-linked Ci-polyvinyl alcohol-boric acid (Ci-PVA-BA) gel, designed to modulate its properties in forming a viscoelastic, weakly cross-linked transient network (due to Ci gelling properties) on vaginal application (at acidic pH of ~3.5-4.5) to a more elastic, densely cross-linked (due to borate-diol cross-linking) gel network at basic pH of 7-8 of seminal fluid, thereby acting as a physical barrier to motile sperm. The gels were characterized for dynamic rheology, physicochemical properties, and impact on sperm functionality (motility, viability, penetration). The rheology data confirmed that the Ci-PBA gel was formed by ionic interactions whereas Ci-PVA-BA gel was chemically cross-linked and became more elastic at basic pH. Based on the screening data, lead gels were selected for in vitro sperm functionality testing. The in vitro results confirmed that the Ci-PBA and Ci-PVA-BA gels created a barrier at the sperm-gel interface, providing sperm blocking properties. For preclinical proof-of-concept, the Ci-PBA gels were applied vaginally and tested for contraceptive efficacy in rabbits, demonstrating only partial efficacy (40-60%). Overall, the in vitro and in vivo results support the development and further optimization of cross-linked gels using commercially available materials as vaginal contraceptives.

Synergistic effects of carvacrol, α-terpinene, γ-terpinene, ρ-cymene and linalool against Gardnerella species

Bacterial vaginosis (BV) is the most common vaginal infection affecting women worldwide. This infection is characterized by the loss of the dominant Lactobacillus community in the vaginal microbiota and an increase of anaerobic bacteria, that leads to the formation of a polymicrobial biofilm, mostly composed of Gardnerella spp. Treatment of BV is normally performed using broad-spectrum antibiotics, such as metronidazole and clindamycin. However, the high levels of recurrence of infection after treatment cessation have led to a demand for new therapeutic alternatives. Thymbra capitata essential oils (EOs) are known to have a wide spectrum of biological properties, including antibacterial activity. Thus, herein, we characterized two EOs of T. capitata and tested their antimicrobial activity as well as some of their main components, aiming to assess possible synergistic effects. Our findings showed that carvacrol and ρ-cymene established a strong synergistic antimicrobial effect against planktonic cultures of Gardnerella spp. On biofilm, carvacrol and linalool at sub-MIC concentrations proved more efficient in eliminating biofilm cells, while showing no cytotoxicity observed in a reconstituted human vaginal epithelium. The antibiofilm potential of the EOs and compounds was highlighted by the fact cells were not able to recover culturability after exposure to fresh medium.

Vaginal cytokine profile and microbiota before and after lubricant use compared with condomless vaginal sex: a preliminary observational study

BACKGROUND

Limited data suggest that personal lubricants may damage the vaginal mucosal epithelium, alter the vaginal microbiota, and increase inflammation. We compared vaginal cytokine profiles and microbiota before and after vaginal lubricant use and condomless vaginal sex.

METHODS

Reproductive-age women were recruited to a 10-week observational cohort study and were asked to self-collect vaginal samples and behavioral diaries daily. This nested case-control analysis utilized samples collected before and after self-reported condomless sexual activity with lubricants (22 case participants) and without lubricants (22 control participants). Controls were matched to cases on race/ethnicity. Microbiota composition was characterized by sequencing amplicons of the 16S rRNA gene V3-V4 regions. Cytokine concentrations were quantified using a magnetic bead 41-plex panel assay and read using a Bio-Plex 200 array reader. Wilcoxon signed-rank tests were used to assess baseline differences in vaginal cytokines between cases and controls as well as differences pre- and post-exposure. Linear mixed effects models were used to examine differences in relative post-to-pre change in each individual cytokine between matched cases and controls. Similar analyses were conducted for the microbiota data.

RESULTS

Mean age was 29.8 years (SD 6.8), and 63.6% were African American. There were few statistically significant changes in cytokines or microbiota before and after exposure in cases or controls. In mixed-effects modeling, the mean relative post-to-pre change of cytokines was higher in cases vs. controls for macrophage derived chemokine (MDC) (p = 0.03). The microbiota data revealed no significant changes when measured by similarity scores, diversity indexes and descriptive community state types (CST) transition analyses. However, post sexual activity, the mean relative abundance of L. crispatus decreased for those who used lubricants (particularly those who were L. iners-dominated prior to exposure).

CONCLUSIONS

Although there were overall few differences in the vaginal microbiota and cytokine profiles of lubricant users and controls before and after condomless vaginal sex, there was a trend toward decreases in relative abundance of L. crispatus following use of lubricant. Future larger studies that take into account osmolarity and composition of lubricants may provide additional insights.

Genitourinary Syndrome of Menopause

Genitourinary syndrome of menopause (GSM) occurs in approximately 50% of menopausal women but is both underrecognized and undertreated despite numerous treatment options. Vaginal dryness, irritation, dyspareunia, urinary frequency, and urinary urgency are some of the more common symptoms that can have a negative effect on women's lives and relationships. Treatment options can include over-the-counter moisturizers and lubricants that can be composed of water or silicone or have an oil base. However, women and health care providers need be aware of the effects of excipients in these products so that the therapy does not cause vaginal irritation. US Food and Drug Administration (FDA)-approved treatment options include vaginally administered estrogen products as well as dehydroepiandrosterone (prasterone) and the selective estrogen receptor modulator ospemifene. The prescription options have proven efficacy and safety and can be considered for use by women with a history of cancer following collaboration with the oncologist. Despite the FDA warning that recommends vaginal lasers not be used for vaginal rejuvenation, vaginal lasers have also been used as a treatment for GSM, but studies on their safety are limited. This article reviews GSM, including its impact, diagnosis, and treatment.

The Role of Fatty Acid Metabolites in Vaginal Health and Disease: Application to Candidiasis

Although the vast majority of women encounters at least one vaginal infection during their life, the amount of microbiome-related research performed in this area lags behind compared to alternative niches such as the intestinal tract. As a result, effective means of diagnosis and treatment, especially of recurrent infections, are limited. The role of the metabolome in vaginal health is largely elusive. It has been shown that lactate produced by the numerous lactobacilli present promotes health by limiting the chance of infection. Short chain fatty acids (SCFA) have been mainly linked to dysbiosis, although the causality of this relationship is still under debate. In this review, we aim to bring together information on the role of the vaginal metabolome and microbiome in infections caused by Candida. Vulvovaginal candidiasis affects near to 70% of all women at least once in their life with a significant proportion of women suffering from the recurrent variant. We assess the role of fatty acid metabolites, mainly SCFA and lactate, in onset of infection and virulence of the fungal pathogen. In addition, we pinpoint where lack of research limits our understanding of the molecular processes involved and restricts the possibility of developing novel treatment strategies.

An Open, Uncontrolled Pilot Study on 12-Week Use of VagiVital for Treatment of Vulvovaginal Atrophy in Breast Cancer Patients Undergoing Adjuvant Aromatase-Inhibitor Therapy

Purpose

This pilot study assessed the efficacy of 12 weeks of daily treatment with a vaginal gel based on a water-based cellulose gel in reducing the severity of moderate-severe symptoms of vulvovaginal atrophy (VVA) and followed adverse events in female breast cancer patients undergoing treatment with adjuvant aromatase- inhibitor therapy.

Methods

In this open, uncontrolled pilot study, the efficacy and safety of the gel during a treatment period of 12 weeks (daily 1×1 mL) were evaluated (n=28). The gel is made of water and hypromellose, a hydropropylmetyl cellulose, which works by coating the vagina, and was developed to treat moderate-severe symptoms of VVA. The primary efficacy variable was the most bothersome symptom (MBS; among vulvovaginal irritation and itching, vaginal dryness, dysuria, or dyspareunia) self-identified at baseline on a four-point scale.

Results

A total of 28 patients fulfilled all entry criteria and had data available after the start of treatment. Treatment with the gel reduced MBS scores from baseline (n=28, mean 2.71) to week 12 (n=27, mean 1.33, mean reduction 1.37; p=0), and reduced the overall total scores for VVA symptoms from a mean of 5.39 at baseline to 2.25 at week 12 (p=0). Eleven subjects (39%) reported 19 AEs.

Conclusion

A 12-week treatment with the gel significantly reduced the severity of MBSs and VVA symptoms, improved quality of life, and was safe to use in women with breast cancer undergoing adjuvant aromatase-inhibitor therapy. In view of the beneficial effects of nonhormonal treatments, for cancer patients in particular, the water-based cellulose gel VagiVital is a suitable candidate for first-choice treatment of VVA symptoms in breast cancer patients and in women predisposed to cancer.

Observational cohort study of the effect of a single lubricant exposure during transvaginal ultrasound on cell-shedding from the vaginal epithelium

The outer layers of the vaginal epithelium (VE) are important because they accumulate glycogen which, under optimal conditions, Lactobacillus spp. consume to grow and acidify the vaginal microenvironment with lactic acid. We hypothesized that exposure to lubricant, for example in the conduct of a transvaginal ultrasound (TVUS), may contribute to the shedding of mature epithelial cells, exposing immature cells. Cervicovaginal fluid (CVF) was sampled at four time points by menstrual cup (Softdisc™) from 50 women referred for TVUS, during which a controlled volume of lubricant was applied to the TVUS wand. Samples were collected (1) immediately before TVUS and (2) 6-12 hours, (3) within one week, and (4) two weeks after TVUS. Clinical vaginal lubricants are similar to commercial lubricants, and often have a high osmolality or pH, and contain bactericides such as methylparaben and propylparaben. The number and maturity of epithelial cells in each CVF sample were measured by quantitative and differential fluorimetry (maturity index, MI). Comparisons of cell-counts and maturity were made by paired Wilcoxon signed-rank tests. Among women with a high pre-TVUS MI (> 3), there was a decrease in median cell-count and mean MI in the sample collected 6-12 hours after TVUS (p<0.001, n = 26 and p < 0.001, n = 26, respectively). For these women, cell-count and MI remained lower in the sample collected within the subsequent week (p<0.001, n = 29 and p<0.01, n = 29, respectively), and MI remained lower in the sample collected within two weeks of TVUS (p<0.01, n = 25), compared to the pre-TVUS sample. Among participants with a low pre-TVUS MI (< 3), cell-count was higher in the sample collected within two weeks of TVUS compared to the pre-TVUS sample (p = 0.03, n = 15), but no significant changes in MI were observed. Results were similar when restricted to reproductive-age women. This preliminary data indicates hypertonic vaginal lubricants may increase vaginal epithelial cell shedding.

Lactic acid-containing products for bacterial vaginosis and their impact on the vaginal microbiota: A systematic review

Objective

The vaginal microbiota in bacterial vaginosis (BV) typically has low abundance of lactic acid producing lactobacilli. Lactic acid has properties that may make it effective for treating BV and/or restoring an optimal lactobacillus-dominated vaginal microbiota. We conducted a systematic review to describe the effect of intravaginal lactic acid-containing products on BV cure, and their impact on vaginal microbiota composition (PROSPERO registration: CRD42018115982).

Methods

PubMed, Embase and OVID were searched from inception to November 2019 to identify eligible studies. Included studies evaluated an intravaginal lactic acid-containing product and reported BV cure using established diagnostic methods, and/or vaginal microbiota composition using molecular methods. Studies were independently screened and assessed, and the proportion of women cured post-treatment was calculated. Study results were described in a qualitative manner.

Results

We identified 1,883 articles and assessed 57 full-texts for eligibility. Seven different lactic acid-containing products were evaluated and differed with respect to excipients, lactic acid concentration and pH. Most studies had medium or high risk of bias. Three trials compared the efficacy of a lactic acid-containing product to metronidazole for BV cure. One study found lactic acid to be equivalent to metronidazole and two studies found lactic acid to be significantly inferior to metronidazole. Two studies included a control group receiving a placebo or no treatment. One reported lactic acid to be superior than no treatment and the other reported lactic acid to be equivalent to placebo. Lactic acid-containing products did not significantly impact the vaginal microbiota composition.

Conclusion

There is a lack of high-quality evidence to support the use of lactic acid-containing products for BV cure or vaginal microbiota modulation. However, adequately powered and rigorous randomised trials with accompanying vaginal microbiota data are needed to evaluate the efficacy of lactic acid as a BV treatment strategy.

Sodium bicarbonate gels: a new promising strategy for the treatment of vulvovaginal candidosis

Vulvovaginal candidosis (VVC), caused mainly by the yeast Candida albicans, is the second most prevalent vaginal infection. It has been found to have a large impact on women's quality of life, self-esteem and routines. The prevalence of recurrent vulvovaginal candidosis (RVVC) remains high so the development of alternative treatments is needed. The main objective of this study was to develop and characterize sodium bicarbonate gels to treat VVC. We described key formulation characteristics and analyzed their influence on in vitro performance evaluations. The potential to inhibit Candida albicans's growth, the pH, osmolality, viscosity and rheological performance in contact with vaginal fluid simulant and the bioadhesion's profile (using a vaginal ex vivo porcine model) were studied for all formulations. Among the formulations, formulation C (5% sodium bicarbonate, 1% carbomer and 94% water) was the most effective in inhibiting the C. albicans' growth. This gel presented the same potential (the same MIC 2.5%) to inhibit other etiological agents of VVC (C. glabrata, C. krusei, C. tropicalis and C. parapsilosis) for all species tested. Additionally, sensorial characteristics of gel C were in accord with users' preferences. This gel exhibited physicochemical characteristics acceptable for short term treatments, suggesting good overall performance for the treatment of VVC. Furthermore, Gel C was biocompatible with the HeLa cell line (MTT assay) and was classified as a non-severe irritant in the HET-CAM assay (irritation score 4 ± 1). Overall, gel C was deemed the best performing of the set tested, and suitable for further development.

Clinical and Personal Lubricants Impact the Growth of Vaginal Lactobacillus Species and Colonization of Vaginal Epithelial Cells: An in Vitro Study

BACKGROUND

Vaginal lubricants are commonly used during gynecological examinations, during sexual activities, or to alleviate vaginal dryness. Many lubricants contain potentially bacteriostatic or bactericidal agents (parabens, chlorhexidine gluconate, nonoxynol-9). Our objective was to evaluate the impact of lubricants that vary in formulation on the growth and viability of vaginal Lactobacillus species and vaginal epithelial cell (VEC) colonization in an in vitro model.

METHODS

Growth curve, disk diffusion, and minimal inhibitory assays were used to determine the impact of lubricants or excipients on the growth of Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus jensenii, and Lactobacillus iners. L. crispatus strain was used in VEC colonization assays. Statistical differences were determined by analysis of variance.

RESULTS

Lubricants containing chlorhexidine gluconate or nonoxynol-9 (N-9; Conceptrol, K-Y Jelly, and Surgilube) significantly inhibited Lactobacillus species growth (P < 0.05). In contrast, other clinical lubricants (E-Z Lubricating Jelly, McKesson Lubricating) and personal lubricants (Astroglide Liquid, Good Clean Love Almost Naked, K-Y Warming Jelly) did not exhibit this effect. Chlorhexidine gluconate had a detrimental effect on Lactobacillus growth and exhibited stronger antimicrobial activity compared with methylparaben and propylparaben (P < 0.0001). There were lubricants that did not induce cytotoxicity in VEC (Good Clean Love Almost Naked, E-Z Lubricating Jelly, McKesson Lubricating Jelly), but these products did substantially decrease the attachment of L. crispatus to VEC, particularly when VEC were preexposed to lubricants before inoculation with bacteria (P < 0.0001).

CONCLUSIONS

This in vitro model indicates that select vaginal lubricants, particularly those with chlorhexidine gluconate, have potentially adverse effects on women's health by reducing growth and recolonization of vaginal Lactobacillus species.

Safety and Efficacy of an Oxytocin Gel and an Equivalent Gel but Without Hormonal Ingredients (Vagivital® Gel) in Postmenopausal Women with Symptoms of Vulvovaginal Atrophy: A Randomized, Double-Blind Controlled Study

Purpose

The primary objective was to compare the efficacy of 12 weeks of daily treatment with Aqueous Hypromellose-based vaginal (Vagivital^®) gel versus Aqueous Hypromellose-based vaginal gel plus 400 IU oxytocin gel in reducing the severity of the most bothersome vulvovaginal atrophy symptoms (MBS: itching, dysuria, bleeding, and pain/discomfort during vaginal sexual activity) observed at baseline. The secondary objectives were to evaluate the other vulvovaginal atrophy symptoms, vaginal pH, superficial squamous cells, and the safety and tolerability of both gels.

Patients and Methods

This double-blind, randomized study evaluated the safety and efficacy of subjects randomly assigned to 12 weeks of daily intravaginal oxytocin gel (n=79) or Aqueous Hypromellose-based vaginal gel (n=78). The efficacy evaluation was performed using data from all included subjects who fulfilled entry criteria.

Results

Both treatments induced statistically significant reductions in the severity of the MBS from baseline until 4 weeks (Vagivital mean reduction 0.90, p=0.0000; Oxytocin mean reduction 0.82, p=0.0000) and 12 weeks post baseline (Vagivital mean reduction 1.28, p=0.0000; Oxytocin mean reduction 1.16, p=0.0000), but the reduction of MBS severity was not significantly different between the treatment groups at either time point. No serious adverse events were reported in the Aqueous Hypromellose-based vaginal gel group during the treatment period, but one (breast cancer) was reported in the oxytocin gel group (assessed as unlikely related to the study compound).

Conclusion

Significant reductions in the severity of the MBS were seen in both the Aqueous Hypromellose-based vaginal gel and the oxytocin gel groups, but with no significant differences in severity reduction seen between the groups. Both gels were safe and well tolerated. Given the benefits of avoiding the use of hormones, Aqueous Hypromellose-based vaginal gel is an attractive first choice in the treatment of postmenopausal women with vulvovaginal atrophy symptoms.

Development of multipurpose technologies products for pregnancy and STI prevention: update on polyphenylene carboxymethylene MPT gel development†

Current modern contraceptives rely heavily on the use of hormones. These birth control drug products, including pills, patches, injections, and IUDS, have been extremely beneficial to millions of women and their families over the past 50 years. But a surprisingly high number of women abandon such modern methods, many because they cannot tolerate the side effects and others because they have medical issues for which hormonal methods are contraindicated. In addition, modern hormonal methods are simply not available to many women. The extent of this problem is steadily becoming more apparent. We present the case for developing simple nonhormonal vaginal products that women can use when needed, ideal products that are multipurpose and offer both contraception and sexually transmitted disease protection. Gel-based vaginal products are particularly well suited for this purpose. Gels are easy to use, highly acceptable to many women, and can be safely formulated to enhance natural vaginal defenses against infection. However, the development of a new chemical entity for this application faces significant technical and regulatory hurdles. These challenges and our solutions are described for polyphenylene carboxymethylene (PPCM), a novel topical drug in a vaginal gel nearing human clinical trials. We have advanced PPCM from benchtop to IND-enabling studies and provide a brief description of the complex development process. We also describe a simple lab assay which can be used as a biomarker for contraceptive activity to enable pharmacodynamic studies in vaginal contraceptive development, both preclinically and in early human clinical trials.

Personal and Clinical Vaginal Lubricants: Impact on Local Vaginal Microenvironment and Implications for Epithelial Cell Host Response and Barrier Function

BACKGROUND

A majority of US women report past use of vaginal lubricants to enhance the ease and comfort of intimate sexual activities. Lubricants are also administered frequently in clinical practice. We sought to investigate if hyperosmolar lubricants are toxic to the vaginal mucosal epithelia.

METHODS

We tested a panel of commercially available lubricants across a range of osmolalities in human monolayer vaginal epithelial cell (VEC) culture and a robust 3-dimensional (3-D) VEC model. The impact of each lubricant on cellular morphology, cytotoxicity, barrier targets, and the induction of inflammatory mediators was examined. Conceptrol, containing nonoxynol-9, was used as a cytotoxicity control.

RESULTS

We observed a loss of intercellular connections, and condensation of chromatin, with increasing lubricant osmolality. EZ Jelly, K-Y Jelly, Astroglide, and Conceptrol induced cytotoxicity in both models at 24 hours. There was a strong positive correlation (r = 0.7326) between lubricant osmolality and cytotoxicity in monolayer VECs, and cell viability was reduced in VECs exposed to all the lubricants tested for 24 hours, except McKesson. Notably, select lubricants altered cell viability, barrier targets, and inflammatory mediators in 3-D VECs.

CONCLUSIONS

These findings indicate that hyperosmolar lubricants alter VEC morphology and are selectively cytotoxic, inflammatory, and barrier disrupting in the 3-D VEC model.

The Effect of Hormonal Contraception on Cervicovaginal Mucosal End Points Associated with HIV Acquisition

Reproductive age women may choose to concurrently use topical antiretrovirals and hormonal contraceptives (HCs) to simultaneously prevent HIV-1 infection and unintended/mistimed pregnancy. There are conflicting data on the effect of HCs on mucosal susceptibility to HIV-1. The objective of this study was to evaluate cervicovaginal (CV) mucosal data from healthy women before and after initiation of either oral contraceptive pills (OCPs) or depot medroxyprogesterone acetate (DMPA) injection. CONRAD A10-114 was a prospective, open-label, parallel cohort study. We enrolled 74 women and 62 completed the visits (32 and 30 who selected OCPs and DMPA, respectively). Participants provided CV lavage, vaginal biopsies, and CV swabs at baseline in the luteal phase and then ∼6 weeks after initiating HCs. After contraceptive initiation, there were significant increases in vaginal immune cell density among both DMPA and OCP users. Changes for OCP users were concentrated in the subepithelial lamina propria, whereas for DMPA users, they were distributed throughout the vaginal tissue, including the epithelium (CD45⁺, CD3⁺, CD4⁺, and CD1a⁺). Contraceptive use altered concentrations of soluble CV inflammatory and immune mediators, with significant reductions in some proinflammatory cytokines and secretory leukoprotease inhibitor. Compared with baseline, p24 antigen production after ex vivo HIV-1 infection of vaginal biopsies doubled after DMPA use, but all p-values were >.05. HIV-1 replication was significantly higher in DMPA-exposed tissues compared with those from the OCP group at the end of the tissue culture (p = .01). Although not statistically significant, median in vitro inhibition of HIV-1 by CV fluid (innate antiviral activity), was reduced by ∼50% with HCs (p > .21). Exposure to exogenous contraceptive hormones significantly increased vaginal immune cells and reduced CV proinflammatory cytokines and antimicrobial peptides. DMPA users showed higher susceptibility to HIV-1 ex vivo infection.

The Dual Role of the Immune Response in Reproductive Organs During Zika Virus Infection

Zika virus is a mosquito-borne viral disease that emerged as a significant health problem in the Americas after an epidemic in 2015. Especially concerning are cases where Zika is linked to the development of brain abnormalities in newborns. Unlike other flaviviruses, Zika can be transmitted sexually, increasing the potential for intraspecies infection. Several reports show that the virus can persist for months in the testis of males after clearance of viremia, and that females are highly susceptible to infection via sexual transmission. The most common route of sexual transmission is male-to-female, which suggests that the mechanism driving persistence of Zika in the testis is essential for dissemination. The immune system plays an essential role in Zika infection. In females, a robust response inhibits the virus to control the infection. In males, however, the immunological response to Zika infection correlates with viral persistence. Thus, the immune system may have a dual role in sexually transmitted pathogenesis. The mechanism by which the immune system allows the virus to enter an immune-privileged site while continuing to disseminate is unclear. In this mini-review, we highlight advances in our knowledge of sexually transmitted Zika virus pathogenesis and the possible mechanisms mounted by the immune system that control or exacerbate the infection.