Nonoxynol-9 causes rapid exfoliation of sheets of rectal epithelium

Potential of antiviral peptide-based SARS-CoV-2 inactivators to combat COVID-19

The appearance of new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the lack of effective antiviral therapeutics for coronavirus disease 2019 (COVID-19), a highly infectious disease caused by the virus, demands the search for alternative therapies. Most antiviral drugs known are passive defenders which must enter the cell to execute their function and suffer from concerns such as permeability and effectiveness, therefore in this current study, we aim to identify peptide inactivators that can act without entering the cells. SARS-CoV-2 spike protein is an essential protein that plays a major role in binding to the host receptor angiotensin-converting enzyme 2 and mediates the viral cell membrane fusion process. SARS vaccines and treatments have also been developed with the spike protein as a target. The virtual screening experiment revealed antiviral peptides which were found to be non-allergen, non-toxic and possess good water solubility. U-1, GST-removed-HR2 and HR2-18 exhibit binding energies of -47.8 kcal/mol, -43.01 kcal/mol, and -40.46 kcal/mol, respectively. The complexes between these peptides and spike protein were stabilized through hydrogen bonds as well as hydrophobic interactions. The stability of the top-ranked peptide with the drug-receptor is evidenced by 50-ns molecular dynamics (MD) simulations. The binding of U-1 induces conformational changes in the spike protein with alterations in its geometric properties such as increased flexibility, decreased compactness, the increased surface area exposed to solvent molecules, and an increase in the number of total hydrogen bonds leading to its probable inactivation. Thus, the identified antiviral peptides can be used as anti-SARS-CoV-2 candidates, inactivating the virus’s spike proteins and preventing it from infecting host cells.

Efficacy of a carrageenan gel in preventing anal human papillomavirus (HPV) infection: interim analysis of the Lubricant Investigation in Men to Inhibit Transmission of HPV Infection (LIMIT-HPV) randomised controlled trial

BACKGROUND

Carrageenan, a non-toxic gelling agent derived from red algae, has potent anti-human papillomavirus (HPV) activity in in vitro and animal studies. We assessed, in an interim analysis, the efficacy of a carrageenan-based gel in reducing the risk of new detections of anal HPV among gay, bisexual and other men who have sex with men (gbMSM).

METHODS

The LIMIT-HPV study (Lubricant Investigation in Men to Inhibit Transmission of HPV Infection) is a phase IIb, double-blind, placebo-controlled randomised controlled trial conducted in Montreal, Canada. gbMSM were randomly assigned (1:1) to receive a carrageenan-based or placebo gel. Participants were instructed to apply the gel to the anus, condom and/or partners' penis before and-as required-during receptive anal intercourse. Questionnaire data and anal samples were collected at 0, 1, 2, 3, 6, 9 and 12 months. We estimated new detections of anal HPV infection(s) detected via Linear Array using Cox proportional hazards models.

RESULTS

Participants recruited from February 2016 to December 2019 were randomly assigned to the carrageenan (n=127) or placebo (n=128) arm. The efficacy and safety analyses included 201 and 210 participants. The median follow-up time was 7.6 months (range: 0-28.5) in the carrageenan group and 9.3 months (range: 0-40.7) in the placebo group. The HR for new detections was 1.21 (95% CI 0.86 to 1.70): 69.4% and 65.1% new detections of HPV in the carrageenan and placebo arms, respectively. More adverse events were reported in the carrageenan (59.8%) compared with the placebo (39.8%) arm.

CONCLUSIONS

The interim analysis did not demonstrate a protective effect of carrageenan on the risk of new detections of anal HPV infection among gbMSM. Carrageenan gel use was associated with a higher proportion of adverse events. Given these findings and the (assumed) low probability that a beneficial effect would be found by the study's end, the trial was terminated as recommended by the Data Safety and Monitoring Board.

TRIAL REGISTRATION NUMBER

NCT02354144.

Protein- and Peptide-Based Virus Inactivators: Inactivating Viruses Before Their Entry Into Cells

Infectious diseases caused by human immunodeficiency virus (HIV) and other highly pathogenic enveloped viruses, have threatened the global public health. Most antiviral drugs act as passive defenders to inhibit viral replication inside the cell, while a few of them function as gate keepers to combat viruses outside the cell, including fusion inhibitors, e.g., enfuvirtide, and receptor antagonists, e.g., maraviroc, as well as virus inactivators (including attachment inhibitors). Different from fusion inhibitors and receptor antagonists that must act in the presence of target cells, virus inactivators can actively inactivate cell-free virions in the blood, through interaction with one or more sites in the envelope glycoproteins (Envs) on virions. Notably, a number of protein- and peptide-based virus inactivators (PPVIs) under development are expected to have a better utilization rate than the current antiviral drugs and be safer for in vivo human application than the chemical-based virus inactivators. Here we have highlighted recent progress in developing PPVIs against several important enveloped viruses, including HIV, influenza virus, Zika virus (ZIKV), dengue virus (DENV), and herpes simplex virus (HSV), and the potential use of PPVIs for urgent treatment of infection by newly emerging or re-emerging viruses.

Impact of Q-Griffithsin anti-HIV microbicide gel in non-human primates: In situ analyses of epithelial and immune cell markers in rectal mucosa

Natural-product derived lectins can function as potent viral inhibitors with minimal toxicity as shown in vitro and in small animal models. We here assessed the effect of rectal application of an anti-HIV lectin-based microbicide Q-Griffithsin (Q-GRFT) in rectal tissue samples from rhesus macaques. E-cadherin⁺ cells, CD4⁺ cells and total mucosal cells were assessed using in situ staining combined with a novel customized digital image analysis platform. Variations in cell numbers between baseline, placebo and Q-GRFT treated samples were analyzed using random intercept linear mixed effect models. The frequencies of rectal E-cadherin⁺ cells remained stable despite multiple tissue samplings and Q-GRFT gel (0.1%, 0.3% and 1%, respectively) treatment. Whereas single dose application of Q-GRFT did not affect the frequencies of rectal CD4⁺ cells, multi-dose Q-GRFT caused a small, but significant increase of the frequencies of intra-epithelial CD4⁺ cells (placebo: median 4%; 1% Q-GRFT: median 7%) and of the CD4⁺ lamina propria cells (placebo: median 30%; 0.1–1% Q-GRFT: median 36–39%). The resting time between sampling points were further associated with minor changes in the total and CD4⁺ rectal mucosal cell levels. The results add to general knowledge of in vivo evaluation of anti-HIV microbicide application concerning cellular effects in rectal mucosa.

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

Most of the widely used vaginal lubricants in the U.S. and Europe are strongly hyperosmolal, formulated with high concentrations of glycerol, propylene glycol, polyquaternary compounds or other ingredients that make these lubricants 4 to 30 times the osmolality of healthy vaginal fluid. Hyperosmolal formulations have been shown to cause marked toxicity to human colorectal epithelia in vivo, and significantly increase vaginal transmission of genital herpes infections in the mouse/HSV model. They also cause toxicity to explants of vaginal epithelia, to cultured vaginal epithelial cells, and increase susceptibility to HIV in target cells in cell cultures. Here, we report that the osmolality of healthy vaginal fluid is 370 ± 40 mOsm/Kg in women with Nugent scores 0–3, and that a well-characterized three-dimensional human vaginal epithelium tissue model demonstrated that vaginal lubricants with osmolality greater than 4 times that of vaginal fluid (>1500 mOsm/Kg) markedly reduce epithelial barrier properties and showed damage in tissue structure. Four out of four such lubricants caused disruption in the parabasal and basal layers of cells as observed by histological analysis and reduced barrier integrity as measured by trans-epithelial electrical resistance (TEER). No epithelial damage to these layers was observed for hypo- and iso-osmolal lubricants with osmolality of <400 mOsm/Kg. The results confirm extensive reports of safety concerns of hyperosmolal lubricants and suggest the usefulness of reconstructed in vitro vaginal tissue models for assessing safety of lubricants in the absence of direct clinical tests in humans.

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).

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.

Enema use among men who have sex with men: a behavioral epidemiologic study with implications for HIV/STI prevention

Enema use or douching is a risk factor for HIV/STI in men who have sex with men (MSM). However, few studies have explored enema use practices. We examined the frequency of enema use, type of products used, and reasons to use and not to use before and after receptive anal sex in a large sample of MSM (N = 4,992) recruited from 16 U.S. cities. Through online surveys, we examined personal, behavioral, and environmental factors associated with enema use. Most (52 %) participants reported having douched at least once and 35 % reported douching within the last 3 months. While most (88 %) reported enema use before receptive anal sex, 28 % douched after receptive anal sex. Most participants (65 %) used water to douche, 24 % added salt, soap, and/or antibacterial products to water, and 30 % reported using commercially available products. Being a man of color, HIV-positive, diagnosed with an STI, identifying as "versatile" in sex, and having more than two unprotected sex partners were significantly associated with recent enema use. Douching behavior appears closely associated with HIV/STI risk. Douching with water may be a concern since it may increase HIV/STI infection by damaging the epithelium. Development and promotion of a non-damaging, non-water based enema specifically for use in anal sex are recommended. In addition, the seemingly contradictory recommendations that water-based lubricant is recommended for anal sex but water-based enemas are dangerous need to be reconciled into a single consistent message.

Isoosmolar enemas demonstrate preferential gastrointestinal distribution, safety, and acceptability compared with hyperosmolar and hypoosmolar enemas as a potential delivery vehicle for rectal microbicides

Rectally applied antiretroviral microbicides for preexposure prophylaxis (PrEP) of HIV infection are currently in development. Since enemas (rectal douches) are commonly used by men who have sex with men prior to receptive anal intercourse, a microbicide enema could enhance PrEP adherence by fitting seamlessly within the usual sexual practices. We assessed the distribution, safety, and acceptability of three enema types-hyperosmolar (Fleet), hypoosmolar (distilled water), and isoosmolar (Normosol-R)-in a crossover design. Nine men received each enema type in random order. Enemas were radiolabeled [(99m)Tc-diethylene triamine pentaacetic acid (DTPA)] to assess enema distribution in the colon using single photon emission computed tomography/computed tomography (SPECT/CT) imaging. Plasma (99m)Tc-DTPA indicated mucosal permeability. Sigmoidoscopic colon tissue biopsies were taken to assess injury as well as tissue penetration of the (99m)Tc-DTPA. Acceptability was assessed after each product use and at the end of the study. SPECT/CT imaging showed that the isoosmolar enema had greater proximal colonic distribution (up to the splenic flexure) and greater luminal and colon tissue concentrations of (99m)Tc-DTPA when compared to the other enemas (p<0.01). Colon biopsies also showed that only the hyperosmolar enema caused sloughing of the colonic epithelium (p<0.05). In permeability testing, the hypoosmolar enema had higher plasma (99m)Tc-DTPA 24-h area under the concentration-time curve and peak concentration compared to the hyperosmolar and isoosmolar enemas, respectively. Acceptability was generally good with no clear preferences among the three enema types. The isoosmolar enema was superior or similar to the other enemas in all categories and is a good candidate for further development as a rectal microbicide vehicle.

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.

Quantitative assessment of altered rectal mucosal permeability due to rectally applied nonoxynol-9, biopsy, and simulated intercourse

BACKGROUND

Microbicide toxicity may reduce the efficacy of topical preexposure prophylaxis for human immunodeficiency virus (HIV) transmission. Noninvasive quantitative measures of microbicide toxicity would usefully inform microbicide development.

METHODS

Ten subjects received 3 one-time interventions: 5 mL of Normosol-R fluid alone (negative control), 5 mL of 2% nonoxynol-9 (N-9) gel, and 5 mL of Normosol-R with coital simulation and sigmoidoscopic biopsy (CS + BX). Each dose of N-9 and Normosol-R contained 500 µCi of (99m)technetium-diethylene triamine pentaacetic acid. Plasma and urine radioactivity was assessed over 24 hours.

RESULTS

The plasma radioisotope concentration peaked 1 hour after N-9 dosing. The mean maximum radioisotope concentration after N-9 receipt was 12.0 times (95% confidence interval [CI], 6.8-21.0) and 8.4 times (95% CI, 5.2-13.5) the mean concentration after Normosol-R control receipt and CS + BX receipt, respectively; paired differences persisted for 24 hours. After N-9 dosing, the urine isotope level was 3.6 times (95% CI, 1.1-11.4) the level observed 8 hours after Normosol-R control receipt and 4.0 times (95% CI, 1.4-11.4) the level observed 4 hours after CS + BX receipt. Permeability after CS + BX receipt was greater than that after Normosol-R control receipt in 0-2-hour urine specimens only (mean permeability, 2.4; 95% CI, 1.0-5.8) but was not greater in blood.

CONCLUSIONS

Plasma sampling after rectal radioisotope administration provided quantitative estimates of altered mucosal permeability after chemical and mechanical stresses. Permeability testing may provide a useful noninvasive adjunct to assess the mucosal effects of candidate microbicides. Clinical Trials Registration. NCT00389311.

A bivalent recombinant protein inactivates HIV-1 by targeting the gp41 prehairpin fusion intermediate induced by CD4 D1D2 domains

Background

Most currently approved anti-HIV drugs (e.g., reverse transcriptase inhibitors, protease inhibitors and fusion/entry inhibitors) must act inside or on surface of the target cell to inhibit HIV infection, but none can directly inactivate virions away from cells. Although soluble CD4 (sCD4) can inactivate laboratory-adapted HIV-1 strains, it fails to reduce the viral loads in clinical trials because of its low potency against primary isolates and tendency to enhance HIV-1 infection at low concentration. Thus, it is essential to design a better HIV inactivator with improved potency for developing new anti-HIV therapeutics that can actively attack the virus in the circulation before it attaches to and enter into the target cell.

Results

We engineered a bivalent HIV-1 inactivator, designated 2DLT, by linking the D1D2 domain of CD4 to T1144, the next generation HIV fusion inhibitor, with a 35-mer linker. The D1D2 domain in this soluble 2DLT protein could bind to the CD4-binding site and induce the formation of the gp41 prehairpin fusion-intermediate (PFI), but showed no sCD4-mediated enhancement of HIV-1 infection. The T1144 domain in 2DLT then bound to the exposed PFI, resulting in rapid inactivation of HIV-1 virions in the absence of the target cell. Beside, 2DLT could also inhibit fusion of the virus with the target cell if the virion escapes the first attack of 2DLT.

Conclusion

This bivalent molecule can serve as a dual barrier against HIV infection by first inactivating HIV-1 virions away from cells and then blocking HIV-1 entry on the target cell surface, indicating its potential for development as a new class of anti-HIV drug.

Is wetter better? An evaluation of over-the-counter personal lubricants for safety and anti-HIV-1 activity

Because lubricants may decrease trauma during coitus, it is hypothesized that they could aid in the prevention of HIV acquisition. Therefore, safety and anti-HIV-1 activity of over-the-counter (OTC) aqueous- (n = 10), lipid- (n = 2), and silicone-based (n = 2) products were tested. The rheological properties of the lipid-based lubricants precluded testing with the exception of explant safety testing. Six aqueous-based gels were hyperosmolar, two were nearly iso-osmolar, and two were hypo-osmolar. Evaluation of the panel of products showed Gynol II (a spermicidal gel containing 2% nonoxynol-9), KY Jelly, and Replens were toxic to Lactobacillus. Two nearly iso-osmolar aqueous- and both silicone-based gels were not toxic toward epithelial cell lines or ectocervical or colorectal explant tissues. Hyperosmolar lubricants demonstrated reduction of tissue viability and epithelial fracture/sloughing while the nearly iso-osmolar and silicon-based lubricants showed no significant changes in tissue viability or epithelial modifications. While most of the lubricants had no measurable anti-HIV-1 activity, three lubricants which retained cell viability did demonstrate modest anti-HIV-1 activity in vitro. To determine if this would result in protection of mucosal tissue or conversely determine if the epithelial damage associated with the hyperosmolar lubricants increased HIV-1 infection ex vivo, ectocervical tissue was exposed to selected lubricants and then challenged with HIV-1. None of the lubricants that had a moderate to high therapeutic index protected the mucosal tissue. These results show hyperosmolar lubricant gels were associated with cellular toxicity and epithelial damage while showing no anti-viral activity. The two iso-osmolar lubricants, Good Clean Love and PRÉ, and both silicone-based lubricants, Female Condom 2 lubricant and Wet Platinum, were the safest in our testing algorithm.

Factors Important to the Prioritization and Development of Successful Topical Microbicides for HIV-1

Significant advancements in topical microbicide development have occurred since the prevention strategy was first described as a means to inhibit the sexual transmission of HIV-1. The lack of clinical efficacy of the first generation microbicide products has focused development attention on specific antiretroviral agents, and these agents have proven partially successful in human clinical trials. With greater understanding of vaginal and rectal virus infection, replication, and dissemination, better microbicide products and delivery strategies should result in products with enhanced potency. However, a variety of development gaps exist which relate to product dosing, formulation and delivery, and pharmacokinetics and pharmacodynamics which must be better understood in order to prioritize microbicide products for clinical development. In vitro, ex vivo, and in vivo models must be optimized with regard to these development gaps in order to put the right product at the right place, at the right time, and at the right concentration for effective inhibition of virus transmission. As the microbicide field continues to evolve, we must harness the knowledge gained from unsuccessful and successful clinical trials and development programs to continuously enhance our preclinical development algorithms.

First phase 1 double-blind, placebo-controlled, randomized rectal microbicide trial using UC781 gel with a novel index of ex vivo efficacy

OBJECTIVES

Successful control of the HIV/AIDS pandemic requires reduction of HIV-1 transmission at sexually-exposed mucosae. No prevention studies of the higher-risk rectal compartment exist. We report the first-in-field Phase 1 trial of a rectally-applied, vaginally-formulated microbicide gel with the RT-inhibitor UC781 measuring clinical and mucosal safety, acceptability and plasma drug levels. A first-in-Phase 1 assessment of preliminary pharmacodynamics was included by measuring changes in ex vivo HIV-1 suppression in rectal biopsy tissue after exposure to product in vivo.

METHODS

HIV-1 seronegative, sexually-abstinent men and women (N = 36) were randomized in a double-blind, placebo-controlled trial comparing UC781 gel at two concentrations (0.1%, 0.25%) with placebo gel (1∶1∶1). Baseline, single-dose exposure and a separate, 7-day at-home dosing were assessed. Safety and acceptability were primary endpoints. Changes in colorectal mucosal markers and UC781 plasma drug levels were secondary endpoints; ex vivo biopsy infectibility was an ancillary endpoint.

RESULTS

All 36 subjects enrolled completed the 7-14 week trial (100% retention) including 3 flexible sigmoidoscopies, each with 28 biopsies (14 at 10 cm; 14 at 30 cm). There were 81 Grade 1 adverse events (AEs) and 8 Grade 2; no Grade 3, 4 or procedure-related AEs were reported. Acceptability was high, including likelihood of future use. No changes in mucosal immunoinflammatory markers were identified. Plasma levels of UC781 were not detected. Ex vivo infection of biopsies using two titers of HIV-1(BaL) showed marked suppression of p24 in tissues exposed in vivo to 0.25% UC781; strong trends of suppression were seen with the lower 0.1% UC781 concentration.

CONCLUSIONS

Single and 7-day topical rectal exposure to both concentrations of UC781 were safe with no significant AEs, high acceptability, no detected plasma drug levels and no significant mucosal changes. Ex vivo biopsy infections demonstrated marked suppression of HIV infectibility, identifying a potential early biomarker of efficacy. (Registered at ClinicalTrials.gov; #NCT00408538).

In vitro surfactant structure-toxicity relationships: implications for surfactant use in sexually transmitted infection prophylaxis and contraception

BACKGROUND

The need for woman-controlled, cheap, safe, effective, easy-to-use and easy-to-store topical applications for prophylaxis against sexually transmitted infections (STIs) makes surfactant-containing formulations an interesting option that requires a more fundamental knowledge concerning surfactant toxicology and structure-activity relationships.

METHODOLOGY/PRINCIPAL FINDINGS

We report in vitro effects of surfactant concentration, exposure time and structure on the viability of mammalian cell types typically encountered in the vagina, namely, fully polarized and confluent epithelial cells, confluent but non-polarized epithelial-like cells, dendritic cells, and human sperm. Representatives of the different families of commercially available surfactants--nonionic (Triton X-100 and monolaurin), zwitterionic (DDPS), anionic (SDS), and cationic (C(n)TAB (n = 10 to 16), C(12)PB, and C(12)BZK)--were examined. Triton X-100, monolaurin, DDPS and SDS were toxic to all cell types at concentrations around their critical micelle concentration (CMC) suggesting a non-selective mode of action involving cell membrane destabilization and/or destruction. All cationic surfactants were toxic at concentrations far below their CMC and showed significant differences in their toxicity toward polarized as compared with non-polarized cells. Their toxicity was also dependent on the chemical nature of the polar head group. Our results suggest an intracellular locus of action for cationic surfactants and show that their structure-activity relationships could be profitably exploited for STI prophylaxis in vaginal gel formulations. The therapeutic indices comparing polarized epithelial cell toxicity to sperm toxicity for all surfactants examined, except C(12)PB and C(12)BZK, does not justify their use as contraceptive agents. C(12)PB and C(12)BZK are shown to have a narrow therapeutic index recommending caution in their use in contraceptive formulations.

CONCLUSIONS/SIGNIFICANCE

Our results contribute to understanding the mechanisms involved in surfactant toxicity, have a predictive value with regard to their safety, and may be used to design more effective and less harmful surfactants for use in topical applications for STI prophylaxis.

HSV neutralization by the microbicidal candidate C5A

Genital herpes is a major risk factor in acquiring human immunodeficiency virus type-1 (HIV-1) infection and is caused by both Herpes Simplex virus type 1 (HSV-1) and HSV-2. The amphipathic peptide C5A, derived from the non-structural hepatitis C virus (HCV) protein 5A, was shown to prevent HIV-1 infection but neither influenza nor vesicular stomatitis virus infections. Here we investigated the antiviral function of C5A on HSV infections. C5A efficiently inhibited both HSV-1 and HSV-2 infection in epithelial cells in vitro as well as in an ex vivo epidermal infection model. C5A destabilized the integrity of the viral HSV membrane. Furthermore, drug resistant HSV strains were inhibited by this peptide. Notably, C5A-mediated neutralization of HSV-1 prevented HIV-1 transmission. An in vitro HIV-1 transmigration assay was developed using primary genital epithelial cells and HSV infection increased HIV-1 transmigration. Treatment with C5A abolished HIV-1 transmigration by preventing HSV infection and by preserving the integrity of the genital epithelium that was severely compromised by HSV infection. In conclusion, this study demonstrates that C5A represents a multipurpose microbicide candidate, which neutralizes both HIV-1 and HSV, and which may interfere with HIV-1 transmission through the genital epithelium.

The nonnucleoside reverse transcriptase inhibitor MIV-150 in carrageenan gel prevents rectal transmission of simian/human immunodeficiency virus infection in macaques

Development of a microbicide that prevents rectal transmission of human immunodeficiency virus (HIV) is a vital component in reducing HIV spread. We recently demonstrated that a formulation of the nonnucleoside reverse transcriptase inhibitor (NNRTI) MIV-150 in carrageenan reduced vaginal infection of macaques with simian immunodeficiency virus SIVmac239 with HIV-1(HxB2) reverse transcriptase (SHIV-RT). Herein, we performed the first testing of MIV-150-carrageenan against rectal infection. Rhesus macaques were treated rectally with MIV-150-carrageenan or methyl cellulose (MC) placebo gel up to 4 h prior to rectal challenge with 10³ or 10(4) 50% tissue culture infective doses (TCID₅₀) of SHIV-RT. Infection was assessed by measuring plasma virus RNA as well as T and B cell responses. MIV-150-carrageenan protected all animals challenged with 10³ TCID(₅₀ when gel was applied either 30 min or 4 h prior to challenge, while 100% of the MC-treated animals became infected (n = 4 each; P < 0.03). Partial protection (2 of 4 animals) by MIV-150-carrageenan was observed for rectal challenge with 10-fold more virus applied 4 h after the gel. Sequencing of the RT gene from plasma virus RNA isolated at peak viremia confirmed that both of these animals (like infected MC controls) were infected with wild-type virus. Infection correlated with the development of SIV-specific T and B cell responses. MIV-150 was detected in the rectal fluids and tissues 4 h after gel application but was not detected in the blood at any time (0.5 to 24 h). These data are promising for the development of NNRTI-containing gels to prevent rectal HIV transmission.

Rectal microbicides: clinically relevant approach to the design of rectal specific placebo formulations

BACKGROUND

The objective of this study is to identify the critical formulation parameters controlling distribution and function for the rectal administration of microbicides in humans. Four placebo formulations were designed with a wide range of hydrophilic characteristics (aqueous to lipid) and rheological properties (Newtonian, shear thinning, thermal sensitive and thixotropic). Aqueous formulations using typical polymers to control viscosity were iso-osmotic and buffered to pH 7. Lipid formulations were developed from lipid solvent/lipid gelling agent binary mixtures. Testing included pharmaceutical function and stability as well as in vitro and in vivo toxicity.

RESULTS

The aqueous fluid placebo, based on poloxamer, was fluid at room temperature, thickened and became shear thinning at 37°C. The aqueous gel placebo used carbopol as the gelling agent, was shear thinning at room temperature and showed a typical decrease in viscosity with an increase in temperature. The lipid fluid placebo, myristyl myristate in isopropyl myristate, was relatively thin and temperature independent. The lipid gel placebo, glyceryl stearate and PEG-75 stearate in caprylic/capric triglycerides, was also shear thinning at both room temperature and 37°C but with significant time dependency or thixotropy. All formulations showed no rectal irritation in rabbits and were non-toxic using an ex vivo rectal explant model.

CONCLUSIONS

Four placebo formulations ranging from fluid to gel in aqueous and lipid formats with a range of rheological properties were developed, tested, scaled-up, manufactured under cGMP conditions and enrolled in a formal stability program. Clinical testing of these formulations as placebos will serve as the basis for further microbicide formulation development with drug-containing products.

Development of an in vitro alternative assay method for vaginal irritation

The vaginal mucosa is commonly exposed to chemicals and therapeutic agents that may result in irritation and/or inflammation. In addition to acute effects, vaginal irritation and inflammation can make women more susceptible to infections such as HIV-1 and herpes simplex virus 2 (HSV-2). Hence, the vaginal irritation potential of feminine care formulations and vaginally administered therapeutic agents is a significant public health concern. Traditionally, testing of such materials has been performed using the rabbit vaginal irritation (RVI) assay. In the current study, we investigated whether the organotypic, highly differentiated EpiVaginal™ tissue could be used as a non-animal alternative to the RVI test. The EpiVaginal tissue was exposed to a single application of ingredients commonly found in feminine hygiene products and the effects on tissue viability (MTT assay), barrier disruption (measured by transepithelial electrical resistance, TEER and sodium fluorescein (NaFl) leakage), and inflammatory cytokine release (interleukin (IL)-1α, IL-1β, IL-6, and IL-8) patterns were examined. When compared to untreated controls, two irritating ingredients, nonoxynol 9 and benzalkonium chloride, reduced tissue viability to <40% and TEER to <60% while increasing NaFl leakage by 11-24% and IL-1α and IL-1β release by >100%. Four other non-irritating materials had minimal effects on these parameters. Assay reproducibility was confirmed by testing the chemicals using three different tissue production lots and by using tissues reconstructed from cells obtained from three different donors. Coefficients of variation between tissue lots reconstructed with cells obtained from the same donor or lots reconstructed with cells obtained from different donors were less than 10% and 12%, respectively. In conclusion, decreases in tissue viability and barrier function and increases in IL-1α and IL-1β release appear to be useful endpoints for preclinical screening of topically applied chemicals and formulations for their vaginal irritation potential.

Acceptability of UC781 gel as a rectal microbicide among HIV-uninfected women and men

We studied the overall acceptability of UC781 gel formulation when applied rectally. Ten women and twenty-six men, all HIV-uninfected, were enrolled in a Phase 1, randomized, blinded, placebo-controlled safety and acceptability study of the vaginal microbicide gel UC781 applied rectally. Participants were randomized to three groups: 0.1% UC781 gel, 0.25% UC781 gel, or a placebo gel. Acceptability was assessed using structured questionnaires and qualitative in-depth interviews. After using UC781 gel rectally for seven consecutive days, participants’ reports suggest that a UC781 gel formulation is highly acceptable and comparable to a placebo gel. The gels received favorable ratings overall and on attributes such as color, smell and consistency. All of the participants reported high intentions to use a gel like the one they used in this study. Acceptability research is essential in early phases of microbicide development to identify potential problems, understand user preferences, and introduce changes if needed.

In vitro and ex vivo testing of tenofovir shows it is effective as an HIV-1 microbicide

BACKGROUND

Tenofovir gel has entered into clinical trials for use as a topical microbicide to prevent HIV-1 infection but has no published data regarding pre-clinical testing using in vitro and ex vivo models. To validate our findings with on-going clinical trial results, we evaluated topical tenofovir gel for safety and efficacy. We also modeled systemic application of tenofovir for efficacy.

METHODS AND FINDINGS

Formulation assessment of tenofovir gel included osmolality, viscosity, in vitro release, and permeability testing. Safety was evaluated by measuring the effect on the viability of vaginal flora, PBMCs, epithelial cells, and ectocervical and colorectal explant tissues. For efficacy testing, PBMCs were cultured with tenofovir or vehicle control gels and HIV-1 representing subtypes A, B, and C. Additionally, polarized ectocervical and colorectal explant cultures were treated apically with either gel. Tenofovir was added basolaterally to simulate systemic application. All tissues were challenged with HIV-1 applied apically. Infection was assessed by measuring p24 by ELISA on collected supernatants and immunohistochemistry for ectocervical explants. Formulation testing showed the tenofovir and vehicle control gels were >10 times isosmolar. Permeability through ectocervical tissue was variable but in all cases the receptor compartment drug concentration reached levels that inhibit HIV-1 infection in vitro. The gels were non-toxic toward vaginal flora, PBMCs, or epithelial cells. A transient reduction in epithelial monolayer integrity and epithelial fracture for ectocervical and colorectal explants was noted and likely due to the hyperosmolar nature of the formulation. Tenofovir gel prevented HIV-1 infection of PBMCs regardless of HIV-1 subtype. Topical and systemic tenofovir were effective at preventing HIV-1 infection of explant cultures.

CONCLUSIONS

These studies provide a mechanism for pre-clinical prediction of safety and efficacy of formulated microbicides. Tenofovir was effective against HIV-1 infection in our algorithm. These data support the use of tenofovir for pre-exposure prophylaxis.

A summary of preclinical topical microbicide rectal safety and efficacy evaluations in a pigtailed macaque model

BACKGROUND

There is widespread recognition of the potential promise of vaginal microbicides as a tool to combat global human immunodeficiency virus/acquired immunodeficiency syndrome and sexually transmitted infections epidemics, and candidate product development has maintained a rapid pace in recent years; however, rectal microbicide development has received less attention. As it is likely that commercial products developed for vaginal use will also be used rectally, there is a clear need to assess the safety and efficacy of candidate microbicide products specifically in the rectal compartment.

METHODS

We have developed a standardized protocol for preclinical rectal safety and (chlamydial) efficacy assessment of topical microbicide candidates in a nonhuman primate model. We evaluated a total of 12 test compounds for rectal safety (via rectal pH, microflora, and rectal lavage) and 1 compound for efficacy against rectal chlamydial infection.

RESULTS

In this article, we describe our methods in detail and summarize our results, particularly noting the ability of our model to distinguish products with deleterious effects on the rectal environment. We also outline the specific criteria used to recommend products move into preclinical rectal efficacy trials or be recommended for reformulation to the product developer. In summary, we observed significant adverse effects in 2 products. The single product that underwent efficacy evaluation was not observed to be protective against rectal chlamydial infection.

CONCLUSIONS

A preclinical safety and efficacy model is critical to promoting rectal microbicide development, which will ultimately offer a significant opportunity for intervention in the global HIV/AIDS epidemic.

Topical microbicides to prevent HIV: clinical drug development challenges

Microbicides, substances applied topically to prevent sexual HIV infection, are needed to empower receptive sexual partners with effective prevention methods. Several large microbicide trials, however, failed to demonstrate efficacy, thus motivating a reevaluation of the current microbicide development paradigm, which has been largely empirically based. Microbicide use occurs in a highly complex environment involving multi-level interactions, behavioral and biochemical, among host, virus, and drug, yet many details of these interactions remain unknown. Fundamental information regarding virus and drug distribution over time in sexually receptive body compartments that is necessary to design a microbicide able to outdistance and outlast the virus is largely absent. Recent efforts have been made to establish a simple conceptual framework for obtaining the knowledge that is likely to inform a more mechanistic, model-based development paradigm. These efforts have also advanced the development of numerous methodological approaches to obtain the knowledge needed to improve microbicide development.

The use of rectal douches among HIV-uninfected and infected men who have unprotected receptive anal intercourse: implications for rectal microbicides

Although some rectal douches result in surface epithelium loss and potential increase of HIV transmission, men who have sex with men (MSM) continue to use them. We describe the prevalence of this practice among MSM engaging in unprotected receptive anal intercourse (URAI) in risky circumstances. A multiethnic sample with overrepresentation of HIV-negative MSM who had URAI in the previous year was recruited exclusively through the Internet. Participants were 105 MSM (78 HIV-negative, 27 HIV-positive). A total of 53% of HIV-negative and 96% of HIV-positive men douched in preparation for sex, most of them frequently or always, mainly for hygienic purposes. 27% of HIV-negative and 44% of HIV-positive douched after sex, partly believing douching protected from infections. Douching practices started around age 25. Regression analyses found the association between HIV status and douching occasions persisted after controlling for demographic characteristics and number of URAI occasions. Rectal douching in preparation for sex is common among men who practice URAI. This population could benefit from alternatives to condoms, such as rectal microbicides. Given the popularity of pre-coital douching and its frequency, a harmless rectal douche that could deliver a rectal microbicide could have great acceptability.

Antiretroviral Drug–Based Microbicides to Prevent HIV-1 Sexual Transmission

The development of a vaginal (and perhaps a rectal) microbicide would be of major benefit for slowing the global spread of human immunodeficiency virus type 1 (HIV-1). A microbicide is a gel or related device that, when inserted vaginally or rectally, acts to prevent infection of a woman or a man by HIV-1 during sexual intercourse. A practical microbicide must be not only effective, safe, and user-friendly but also economically affordable in the developing world. To date, the performance of microbicide candidates in efficacy trials has been disappointing, but next-generation concepts now in or approaching clinical trials offer improved prospects for efficacy. The most plausible approaches involve topical application of antiretroviral agents with specific activity against HIV-1, compounds similar to drugs used to treat HIV-1 infection. How these inhibitors are applied may also be critical, with sustained-release formulations and vaginal ring delivery systems now becoming a high priority.

Characterization of baseline intestinal mucosal indices of injury and inflammation in men for use in rectal microbicide trials (HIV Prevention Trials Network-056)

OBJECTIVES

The purpose of this study was to evaluate the biologic stability of mucosal parameters that might be used as endpoints in phase 1 rectal safety studies.

METHODS

Sixteen male participants were enrolled into 4 groups defined by HIV status, viral load, and sexual activity. Each participant underwent 3 flexible sigmoidoscopies at 2-week intervals with collection of blood, intestinal biopsies, and rectal secretions. Intestinal histology, phenotypic characterization of mucosal mononuclear cells, cytokine messenger RNA (mRNA) profiles (RANTES, interferon-gamma [IFNgamma], and interleukin-10), and immunoglobulin secretion were assessed. Intraclass correlation (ICC) was calculated to assess endpoint stability.

RESULTS

Qualitative histology demonstrated minimal inflammation in >95% of biopsies and remained stable throughout the study period. ICC for the tissue cytokine mRNA measurements and several T-cell phenotypic markers was >0.7, indicating stability over time. Mucosal CD4 lymphopenia was seen in the HIV-positive participants and was more pronounced in those with higher viral loads. Modest differences were observed for cytokine expression (IFNgamma) and T-cell phenotype (CD3, CD4, CD8, CD19, CD4/CCR5, and CD4/CD38) between the tissue samples collected at 10 and 30 cm.

CONCLUSIONS

These data help to provide a rationale for the selection of endpoints for future phase 1 rectal safety studies.

Preclinical testing of candidate topical microbicides for anti-human immunodeficiency virus type 1 activity and tissue toxicity in a human cervical explant culture

A human cervical explant culture was utilized for the preclinical assessment of anti-human immunodeficiency virus type 1 (HIV-1) activity and tissue toxicity of formulated, candidate topical microbicides. Products tested included cellulose acetate 1,2-benzene dicarboxylate (CAP), a carrageenan-based product (PC-515), a naphthalene sulfonate polymer (PRO 2000), a lysine dendrimer (SPL7013), a nonnucleoside reverse transcriptase inhibitor (UC781), and an antimicrobial peptide (D2A21), along with their placebos. Cervical explants were cultured overnight with HIV-1 with or without product, washed, and monitored for signs of HIV-1 infection. HIV-1 infection was determined by p24gag levels in the basolateral medium and by immunohistochemical analysis of the explant. Product toxicity was measured by the MTT [1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan] assay and histology. CAP, PRO 2000, SPL7013, and UC781 consistently prevented HIV-1 infection in all explants tested. PC-515 and D2A21 prevented HIV-1 infection in 50% or fewer of the explants tested. Placebos did not prevent infection in any of the explants tested. With the exception of PRO 2000 (4%), the MTT assay and histological analysis of the other products and placebos showed minimal toxicity to the epithelium and submucosa. Collectively, these data suggest that this culture system can be used for evaluating the safety and efficacy of topical microbicides designed for vaginal use.

Microbicides: a new frontier in HIV prevention

Microbicides are products that can be applied to vaginal or rectal mucosal surfaces with the goal of preventing, or at least significantly reducing, the transmission of sexually transmitted infections (STIs) including HIV-1. Despite more than two decades of HIV-1 vaccine research, there is still no efficacious HIV-1 vaccine, and the scientific community appears skeptical about the short or long-term feasibility of developing a vaccine that has the ability to induce sterilizing immunity against HIV-1. In this setting, microbicide research has gathered momentum. Currently, 16 candidate microbicides are in clinical development and five products are being evaluated in large-scale Phase 2B/3 effectiveness studies. Initial data from these trials will be available within the next 2-3 years, and it is feasible that there could be one or more licensed microbicides by the end of the decade. The first generation of surfactant microbicides had a non-specific mechanism of action. However, subsequent candidate microbicides have been developed to target specific steps in the process of viral transmission. The purpose of this article is to provide an overview of microbicide development and an update on the candidate pipeline.

Microbicides 2006 conference

Current HIV/AIDS statistics show that women account for almost 60% of HIV infections in Sub-Saharan Africa. HIV prevention tools such as male and female condoms, abstinence and monogamy are not always feasible options for women due to various socio-economic and cultural factors. Microbicides are products designed to be inserted in the vagina or rectum prior to sex to prevent HIV acquisition.

The biannual Microbicides conference took place in Cape Town, South Africa from 23–26 April 2006. The conference was held for the first time on the African continent, the region worst affected by the HIV/AIDS pandemic. The conference brought together a record number of 1,300 scientists, researchers, policy makers, healthcare workers, communities and advocates. The conference provided an opportunity for an update on microbicide research and development as well as discussions around key issues such as ethics, acceptability, access and community involvement.

This report discusses the current status of microbicide research and development, encompassing basic and clinical science, social and behavioural science, and community mobilisation and advocacy activities.

Which topical microbicides for blocking HIV-1 transmission will work in the real world?

Klasse and colleagues discuss key research on the four crucial issues in developing a microbicide: safety, acceptability, efficacy, and affordability.

Greater risk for HIV infection of black men who have sex with men: a critical literature review

HIV rates are disproportionately higher for Black men who have sex with men (MSM) than for other MSM. We reviewed the literature to examine 12 hypotheses that might explain this disparity. We found that high rates of HIV infection for Black MSM were partly attributable to a high prevalence of sexually transmitted diseases that facilitate HIV transmission and to undetected or late diagnosis of HIV infection; they were not attributable to a higher frequency of risky sexual behavior, nongay identity, or sexual nondisclosure, or to reported use of alcohol or illicit substances. Evidence was insufficient to evaluate the remaining hypotheses.Future studies must address these hypotheses to provide additional explanations for the greater prevalence of HIV infection among Black MSM.

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

BACKGROUND

Microbicides must protect against STD pathogens without causing unacceptable toxic effects. Microbicides based on nonoxynol-9 (N9) and other detergents disrupt sperm, HSV and HIV membranes, and these agents are effective contraceptives. But paradoxically N9 fails to protect women against HIV and other STD pathogens, most likely because it causes toxic effects that increase susceptibility. The mouse HSV-2 vaginal transmission model reported here: (a) Directly tests for toxic effects that increase susceptibility to HSV-2, (b) Determines in vivo whether a microbicide can protect against HSV-2 transmission without causing toxicities that increase susceptibility, and (c) Identifies those toxic effects that best correlate with the increased HSV susceptibility.

METHODS

Susceptibility was evaluated in progestin-treated mice by delivering a low-dose viral inoculum (0.1 ID50) at various times after delivering the candidate microbicide to detect whether the candidate increased the fraction of mice infected. Ten agents were tested - five detergents: nonionic (N9), cationic (benzalkonium chloride, BZK), anionic (sodium dodecylsulfate, SDS), the pair of detergents in C31G (C14AO and C16B); one surface active agent (chlorhexidine); two non-detergents (BufferGel, and sulfonated polystyrene, SPS); and HEC placebo gel (hydroxyethylcellulose). Toxic effects were evaluated by histology, uptake of a 'dead cell' dye, colposcopy, enumeration of vaginal macrophages, and measurement of inflammatory cytokines.

RESULTS

A single dose of N9 protected against HSV-2 for a few minutes but then rapidly increased susceptibility, which reached maximum at 12 hours. When applied at the minimal concentration needed for brief partial protection, all five detergents caused a subsequent increase in susceptibility at 12 hours of approximately 20-30-fold. Surprisingly, colposcopy failed to detect visible signs of the N9 toxic effect that increased susceptibility at 12 hours. Toxic effects that occurred contemporaneously with increased susceptibility were rapid exfoliation and re-growth of epithelial cell layers, entry of macrophages into the vaginal lumen, and release of one or more inflammatory cytokines (Il-1beta, KC, MIP 1alpha, RANTES). The non-detergent microbicides and HEC placebo caused no significant increase in susceptibility or toxic effects.

CONCLUSION

This mouse HSV-2 model provides a sensitive method to detect microbicide-induced toxicities that increase susceptibility to infection. In this model, there was no concentration at which detergents provided protection without significantly increasing susceptibility.

Safety and distribution of cellulose acetate 1,2-benzenedicarboxylate (CAP), a candidate anti-HIV microbicide in rhesus macaques

OBJECTIVES

To assess the safety and distribution of a cellulose acetate 1,2-benzenedicarboxylate (CAP) gel formulation in rhesus macaques as part of the development process for its use as a vaginally administered product in humans.

DESIGN

The similarities between the reproductive physiology, anatomy and vaginal microflora of human and non-human primates makes non-human primates a relevant animal model to assess the safety and distribution of candidate anti-HIV microbicides.

METHODS

CAP gel was instilled once or once daily for 4 days into the vaginal vault of rhesus macaques. Colposcopy and magnetic resonance imaging were performed to detect adverse effects and spread of CAP, respectively. Additionally, vaginal pH and composition of the vaginal micorflora in macaques before, during and after CAP instillations were determined, and vaginal biopsies obtained following repeated CAP exposures were examined to further document its safety.

RESULTS

CAP is safe for repeated use and exhibits a favorable distribution profile, showing no evidence of penetration into cells that line the vaginal epithelium. Further, the presence of CAP has no adverse effect on vaginal pH or the composition of the vaginal microflora, and does not induce vaginal epithelial thinning or inflammation.

CONCLUSIONS

CAP gel shows minimal toxicity in vivo, supporting its use as a candidate vaginal microbicide in humans.

Condom Use Assessment of Persons in Drug Abuse Treatment

The purpose of this study was to objectively and quantitatively assess individual skill level of male condom use. This study developed a reliable and face valid assessment of correct male condom use based on Centers for Disease Control and Prevention criteria. Participants (N= 163) were recruited from persons in treatment for cocaine addiction. Condom use was assessed on the basis of correct completion of eight discrete steps. An overall score of 40% correct condom use indicated the need for training in this sample. Assessment showed training needs especially related to steps involving reduction of ejaculate leakage and steps related to potential hazards of nonoxynol-9 use. Frequency of condom use was also assessed; there was no correlation between frequency of condom use and condom use skill. Drug addiction treatment programs are encouraged to incorporate HIV risk reduction programs that teach condom use skills and use the CUDOS as an empirical measure of condom skill acquisition.

In vitro comparison of topical microbicides for prevention of human immunodeficiency virus type 1 transmission

A standardized protocol was used to compare cellular toxicities and anti-human immunodeficiency virus type 1 (HIV-1) activities of candidate microbicides formulated for human use. The microbicides evaluated were cellulose acetate phthalate (CAP), Carraguard, K-Y plus nonoxynol-9 (KY-N9), PRO 2000 (0.5 and 4%), SPL7013 (5%), UC781 (0.1 and 1%), and Vena Gel, along with their accompanying placebos. Products were evaluated for toxicity on cervical and colorectal epithelial cell lines, peripheral blood mononuclear cells (PBMCs), and macrophages (MPhi) by using an ATP release assay, and they were tested for their effect on transepithelial resistance (TER) of polarized epithelial monolayers. Anti-HIV-1 activity was evaluated in assays for transfer of infectious HIV-1 from epithelial cells to activated PBMCs and for PBMC and MPhi infection. CAP, Carraguard, PRO 2000, SPL7013, and UC781 along with their placebos were 20- to 50-fold less toxic than KY-N9 and Vena Gel. None of the nontoxic product concentrations disrupted the TER. Transfer of HIV-1(Ba-L) from epithelial cells to PBMCs and PBMC and MPhi infection with laboratory-adapted HIV-1(Ba-L) and HIV-1(LAI) isolates were inhibited by all products except Carraguard, KY-N9, and Vena Gel. KY-N9, Vena Gel, and Carraguard were not effective in blocking PBMC infection with primary HIV-1(A), HIV-1(C), and HIV-1(CRF01-AE) isolates. The concordance of these toxicity results with those previously reported indicates that our protocol may be useful for predicting toxicity in vivo. Moreover, our systematic anti-HIV-1 testing provides a rational basis for making better informed decisions about which products to consider for clinical trials.

Lubricants containing N-9 may enhance rectal transmission of HIV and other STIs

It has been shown that men who have sex with men actively seek lubricants that contain nonoxynol-9 (N-9) because they believe that N-9 may help to prevent infection by HIV. However, indirect evidence suggests that N-9 may actually enhance infection. Microscopic examination of rectal lavage and biopsy specimens collected at different time points following rectal application of a lubricant containing 2% N-9 showed rapid exfoliation of the rectal epithelium. Because the rectal epithelium protects target cells in the submucosa from HIV, we conclude that lubricants containing N-9 should be avoided during rectal sex.

Relative Safety of Sexual Lubricants for Rectal Intercourse

OBJECTIVE

The current study was conducted to determine the relative safety of sexual lubricants for rectal use.

GOAL

Our goal was to identify a sexual lubricant that would not damage the rectal epithelium.

STUDY DESIGN

We describe a mouse assay to determine the degree to which lubricants cause rectal sloughing. We also tested lubricants for cytotoxicity and their effect on Herpes simplex virus (HSV-2) infection after rectal challenge.

RESULTS

Of the products tested, Delube and KY-Plus are most likely to damage the rectal epithelium, whereas Viamor, Vagisil, and Astroglide would cause some degree of rectal damage. PBS, Carraguard, and methylcellulose were not toxic in any of the assays.

CONCLUSION

We have developed a quantitative method to assay the degree of sloughing of the rectal epithelium. Using this and other techniques, we are able to predict the degree to which lubricants could be safe for rectal use.

Safety and Efficacy Evaluations for Vaginal and Rectal Use of BufferGel in the Macaque Model

BACKGROUND

The nonhuman primate model allows for safety and efficacy testing of topical microbicide products.

GOAL

The goal of this study was to evaluate the safety and efficacy of vaginal and rectal applications of BufferGel (ReProtect, Inc.).

STUDY DESIGN

The safety of repeated product applications was evaluated by microflora, pH, vaginal colposcopy, and rectal lavage. To test efficacy in preventing chlamydia, infection was documented by culture and nucleic acid amplification tests.

RESULTS

Repeated vaginal or rectal applications of BufferGel were not associated with significant changes in microflora. BufferGel use had a transient acidifying effect on vaginal and rectal pH. Colposcopic observations remained relatively normal in all test animals. A slightly increased incidence of epithelial desquamation was noted after rectal product use compared with the control group. BufferGel did not prevent cervical or rectal chlamydial infection.

CONCLUSION

BufferGel has an acceptable safety profile after repeated vaginal and rectal use, but does not prevent chlamydial infection in the macaque models.

Coprecipitation of nonoxynol-9 with polyvinylpyrrolidone to decrease vaginal irritation potential while maintaining spermicidal potency

The aim of this study was to test the hypothesis that polyvinylpyrrolidone (PVP) would increase the critical micelle concentration (CMC) of nonoxynol-9 (N-9), providing a reduction in its irritation potential, while maintaining essential spermicidal activity. Solid coprecipitates of N-9 with PVP were manufactured with the use of a modified lyophilization process. The irritation potential of N-9 was estimated by an in vitro assay, monitoring the extent of hemolysis of red blood cells. CMCs of N-9 were measured in the presence of various concentrations of PVP. A modified Sander-Cramer assay was implemented to measure the spermicidal activity of N-9 and the N-9/PVP coprecipitates. With the use of the lyophilization process and more suitable solvents, solid coprecipitates of N-9/PVP were manufactured with no residual organic solvents. The irritation potential of N-9 was reduced when in the presence of PVP-50% hemolysis values increased from 0.054 mM to more than 0.2mM. N-9 CMC values increased in the presence of PVP from 0.085 mM (0% PVP) to 0.110 mM (3.5% PVP) and 0.16 6mM (10% PVP). However, spermicidal activities ranged from 0.213 mM to 0.238 mM, N-9 remaining steady regardless of the amount of PVP. By use of N-9/PVP coprecipitates, the self-association properties and irritation potentials of N-9 were altered. This result suggests a process to produce a spermicidal product that reduces the detrimental implications to the vaginal epithelium while maintaining the essential spermicidal activity.

Poly(sodium 4-styrene sulfonate): evaluation of a topical microbicide gel against herpes simplex virus type 2 and Chlamydia trachomatis infections in mice

OBJECTIVE

To investigate the in vivo activity of poly(sodium 4-styrene sulfonate) (T-PSS) gel formulations as topical microbicides.

METHODS

The ability of the gel formulations to reduce the incidence of infection when applied prior to pathogen challenge was examined in mouse models of vaginal herpes simplex type 2 (HSV-2) and Chlamydia trachomatis infection, and rectal HSV-2 infection.

RESULTS

In the vaginal HSV-2 challenge studies, 10% T-PSS gel provided significant protection against infection, even when administered 60 min prior to virus challenge (P < 0.0001). Both 5% and 10% T-PSS gel formulations significantly reduced the incidence of upper genital tract C. trachomatis infection in animals treated up to 5 min before challenge (P < 0.001). However, no protection against C. trachomatis infection was seen in animals treated 30 min before challenge. In mice challenged rectally with HSV-2, both the 5% and 10% T-PSS gels significantly reduced infection at 20 s (P < 0.01 for both). However, only the 10% gel provided significant protection when administered 5 min before challenge (P < 0.01).

CONCLUSIONS

T-PSS gel formulations have promising in vivo activity as topical microbicides.

Development of topical microbicides for prevention of human immunodeficiency virus and herpes simplex virus

Topical microbicides, designed for vaginal or rectal administration, are needed to prevent human immunodeficiency virus (HIV) and other sexually transmitted infections (STI). Presently marketed topical microbicides are cytotoxic and damage the vaginal epithelium with frequent use. Rational development of new candidate compounds should build on knowledge of the pathways of microbial invasion. The establishment of assays and models that predict efficacy and safety is critical. Comprehensive pre-clinical evaluation of promising microbicides should include rigorous assessment of the effects of repeated application of topical agents on mucosal inflammatory cells, cytokines, and the genital tract virus population. These studies will lay the groundwork for future clinical trials.

Rectal use of nonoxynol-9 among men who have sex with men

OBJECTIVES

To assess recent rectal use of nonoxynol-9 (N-9), intent to use the product, and factors associated with N-9 use among men who have sex with men (MSM).

DESIGN

Cross-sectional survey of a diverse sample of MSM in the San Francisco Bay Area.

METHODS

Recruitment conducted at multiple street locations on various days/times or through referral during the Fall of 2001.

RESULTS

Sixty-one percent (349/573) had heard of N-9, of which 55% (192/349) reported hearing in the prior year that N-9 may not be protective against HIV. Of men aware of N-9, 83% (289/349) knowingly used it in their lifetime, of which 67% (193/289) used it during anal intercourse in the previous year. Forty-one percent (79/193) of those who used N-9 during anal intercourse in the past year did so without a condom because they thought it may protect against HIV. Older men were more likely than younger men to have used N-9 for protection. Men who heard that N-9 may not protect were less likely, and African-Americans (versus Caucasians) were more likely, to say they would definitely use N-9 during anal intercourse in the future. Latinos (versus Caucasians), those with unknown HIV serostatus (versus HIV-negative), and those with lower education were less likely to know about N-9 at all, and thus were at risk for unknowingly using N-9.

CONCLUSIONS

Many MSM used N-9 during or following public health warnings about the product. Actions (e.g., information campaigns, warning labels specific to rectal use) should be considered by communities to reduce rectal use of N-9.

Microbicides: a new approach to preventing HIV and other sexually transmitted infections

Many chemical agents can block human immunodeficiency virus (HIV) infection in the laboratory. Scientists are investigating which of these, used intravaginally by women, will safely prevent the sexual transmission of HIV in humans. Several such products - microbicides - will soon be tested in populations at high risk for HIV, and others are waiting in the wings. Microbicides will provide a low-cost method, controlled by women, for protection against HIV, other sexually transmitted pathogens and unwanted pregnancy, and will therefore have global public-health benefits.