Practical prevention of vaginal and rectal transmission of HIV by adapting the oral defense: use of commercial lubricants

Repeated rectal application of a hyperosmolar lubricant is associated with microbiota shifts but does not affect PrEP drug concentrations: results from a randomized trial in men who have sex with men

INTRODUCTION

Oral pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) is highly effective in preventing HIV infection among men who have sex with men (MSM). The effects of consistent personal lubricant use in the rectum on tissue PrEP drug concentrations and the rectal microbiota are unknown. We investigated rectal PrEP drug concentrations and the microbiota in MSM before and after repeated rectal application of a hyperosmolar lubricant.

METHODS

We randomized 60 HIV-negative MSM to apply 4 mL of hyperosmolar rectal lubricant daily (n = 20), take daily oral TDF/FTC (n = 19), or both (n = 21) for seven days. Blood, rectal biopsies and rectal secretions were collected via rigid sigmoidoscopy before and on day 8 after product use. Tenofovir (TFV) and FTC as well as their intracellular metabolites tenofovir-diphosphate (TFV-DP), FTC-triphosphate (FTC-TP) were measured by HPLC-mass spectrometry. Rectal mucosal microbiota was sequenced with 16S rRNA sequencing using Illumina MiSeq.

RESULTS

Seven days of lubricant application was not associated with differences in PrEP drug concentrations in rectal tissue or secretions. Lubricant use was associated with a decrease in the relative abundance of the Bacteroides genus (p = 0.01) and a non-significant increase in the Prevotella genus (p = 0.09) in the rectum. PrEP drug concentrations in rectal tissue and secretions were not associated with microbiota composition or diversity either before or after lubricant use.

CONCLUSIONS

Repeated rectal application of a hyperosmolar lubricant does not affect mucosal PrEP drug concentrations but is associated with changes in the rectal microbiome.

Pathogenesis of oral FIV infection

Feline immunodeficiency virus (FIV) is the feline analogue of human immunodeficiency virus (HIV) and features many hallmarks of HIV infection and pathogenesis, including the development of concurrent oral lesions. While HIV is typically transmitted via parenteral transmucosal contact, recent studies prove that oral transmission can occur, and that saliva from infected individuals contains significant amounts of HIV RNA and DNA. While it is accepted that FIV is primarily transmitted by biting, few studies have evaluated FIV oral infection kinetics and transmission mechanisms over the last 20 years. Modern quantitative analyses applied to natural FIV oral infection could significantly further our understanding of lentiviral oral disease and transmission. We therefore characterized FIV salivary viral kinetics and antibody secretions to more fully document oral viral pathogenesis. Our results demonstrate that: (i) saliva of FIV-infected cats contains infectious virus particles, FIV viral RNA at levels equivalent to circulation, and lower but significant amounts of FIV proviral DNA; (ii) the ratio of FIV RNA to DNA is significantly higher in saliva than in circulation; (iii) FIV viral load in oral lymphoid tissues (tonsil, lymph nodes) is significantly higher than mucosal tissues (buccal mucosa, salivary gland, tongue); (iv) salivary IgG antibodies increase significantly over time in FIV-infected cats, while salivary IgA levels remain static; and, (v) saliva from naïve Specific Pathogen Free cats inhibits FIV growth in vitro. Collectively, these results suggest that oral lymphoid tissues serve as a site for enhanced FIV replication, resulting in accumulation of FIV particles and FIV-infected cells in saliva. Failure to induce a virus-specific oral mucosal antibody response, and/or viral capability to overcome inhibitory components in saliva may perpetuate chronic oral cavity infection. Based upon these findings, we propose a model of oral FIV pathogenesis and suggest alternative diagnostic modalities and translational approaches to study oral HIV infection.

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.

Identification of personal lubricants that can cause rectal epithelial cell damage and enhance HIV type 1 replication in vitro

Over-the-counter personal lubricants are used frequently during vaginal and anal intercourse, but they have not been extensively tested for biological effects that might influence HIV transmission. We evaluated the in vitro toxicity anti-HIV-1 activity and osmolality of popular lubricants. A total of 41 lubricants were examined and compared to Gynol II and Carraguard as positive and negative controls for toxicity, respectively. Cytotoxicity was assessed using the XTT assay. The MAGI assay with R5 and X4 HIV-1 laboratory strains was used to evaluate antiviral activity. The effect of the lubricants on differentiated Caco-2 cell monolayers (transepithelial electrical resistance, TEER) was also measured. None of the lubricants tested showed significant activity against HIV-1. Surprisingly, four of them, Astroglide Liquid, Astroglide Warming Liquid, Astroglide Glycerin & Paraben-Free Liquid, and Astroglide Silken Secret, significantly enhanced HIV-1 replication (p<0.0001). A common ingredient in three of these preparations is polyquaternium-15. In vitro testing of a chemically related compound (MADQUAT) confirmed that this similarly augmented HIV-1 replication. Most of the lubricants were found to be hyperosmolar and the TEER value dropped approximately 60% 2 h after exposure to all lubricants tested. Cells treated with Carraguard, saline, and cell controls maintained about 100% initial TEER value after 2-6 h. We have identified four lubricants that significantly increase HIV-1 replication in vitro. In addition, the epithelial damage caused by these and many other lubricants may have implications for enhancing HIV transmission in vivo. These data emphasize the importance of performing more rigorous safety testing on these products.

Topical microbicides to prevent the transmission of HIV: formulation gaps and challenges

The efforts of the topical microbicide field to identify a safe and effective topical microbicide were realized in July of 2010 with the reporting of the results of the Centre for the AIDS Programme of Research in South Africa 004 trial. In this trial, a 1% tenofovir gel was found to reduce women's risk for HIV acquisition by 39% compared to placebo. To understand the impact of this trial on future microbicide development, we must view it from the historical perspective of previous phases 2 and 3 clinical trials with detergents and sulfated polyanions. This knowledge and emerging information must then be parlayed into the next steps needed to create a safe, effective, and acceptable topical microbicide. This review will look at the lessons learned from preclinical and clinical development of topical microbicides, focusing on two significant future challenges: (1) topical microbicide formulation safety and (2) the critical role that adherence to product use has in determining safety and efficacy in clinical trials and ultimately commercial viability of the licensed product. In addition to framing these issues within our current understanding of formulation and prevention of HIV acquisition, recent advances in our understanding of the mechanism of HIV transmission and how it informs on future formulation strategies will be briefly discussed.

Microbicidal spermicide or spermicidal microbicide?

Vaginal contraception, the oldest method of fertility regulation that remained virtually forgotten for a few decades has recently come under focal review due to an increase in STDs and HIV infections worldwide. Today it is being considered very strongly that a conceptual microbicidal spermicide can tender protection against pregnancy as well as STDs (including AIDS), simultaneously. However the two activities (spermicidal and microbicidal) need to be integrated in vaginal preparations, as many women across the world may be concerned more about the unwanted pregnancy rather than the STI during a coital act. A strong detergent like nonoxynol-9 (N-9) has been used as a spermicide in many local contraceptive preparations and studies have shown that it also exhibits significant microbicidal activity in vitro. However, recent clinical trials have shown that detergent spermicides do not provide any protection against STDs and AIDS but may in fact even promote their transmission. This anomaly has largely been attributed to their surfactant nature that irritates the vagina and kills the normal vaginal flora making it more susceptible to STD infections. An urgent need for a suitable non-detergent spermicide has thus emerged to replace N-9 in local contraceptive preparations. Anticipating the potential of spermicide-based vaginal contraceptives in the reproductive health of women, a large number of synthetic, non-detergent molecules were designed and evaluated at this Institute over recent years. Simultaneously, a number of natural products from terrestrial plants and marine flora/fauna were also evaluated for spermicidal activity. A local contraceptive preparation incorporating the active ingredient from the fruit pericarp of Sapindus mukorossi has successfully completed Phase III clinical trials in India and is ready for marketing. Recent studies have indicated that in comparison to N-9, this ingredient is much less toxic to Lactobacillus spp. and effectively inhibits the growth of Trichomonas vaginalis in vitro. Other candidate spermicides/microbicides under development worldwide have been reviewed briefly.

Oral transmission of HIV, reality or fiction? An update

Human immunodeficiency virus (HIV) and many other viruses can be isolated in blood and body fluids, including saliva, and can be transmitted by genital-genital and especially anal-genital sexual activity. The risk of transmission of HIV via oral sexual practices is very low. Unlike other mucosal areas of the body, the oral cavity appears to be an extremely uncommon transmission route for HIV. We present a review of available evidence on the oral-genital transmission of HIV and analyse the factors that act to protect oral tissues from infection, thereby reducing the risk of HIV transmission by oral sex. Among these factors we highlight the levels of HIV RNA in saliva, presence of fewer CD4+ target cells, presence of IgA antibodies in saliva, presence of other infections in the oral cavity and the endogenous salivary antiviral factors lysozyme, defensins, thrombospondin and secretory leucocyte protease inhibitor (SLPI).

In vitro and in vivo characterization of a potential universal placebo designed for use in vaginal microbicide clinical trials

The development of vaginal microbicides for the prevention of sexual transmission of HIV is becoming an increasingly important strategy in the battle against the AIDS epidemic. Several first generation microbicide candidates are entering Phase III efficacy trials, and several other candidates are in earlier stages of clinical development. The capacity to make accurate clinical assessments of the safety and efficacy of microbicide formulations is critical. Since microbicide trials will rely on a blinded, randomized, placebo-controlled design, it is important to employ a placebo formulation that does not distort either safety or efficacy assessments. Efficacy of the microbicide would be underestimated if the placebo itself provided a degree of protection. Conversely, a placebo with epithelial toxicity that increased susceptibility would cause an overestimation of microbicide efficacy. To address these issues, a hydroxyethylcellulose (HEC) placebo formulation has been developed and has been adopted for use in clinical evaluations of investigational microbicides as a "universal" placebo. In this report, the chemical and physical properties of this formulation are described, as well as its in vitro and in vivo effects on safety and efficacy. The results show that this "universal" placebo has adequate physical properties, is sufficiently stable as a vaginal gel formulation, and is safe and sufficiently inactive for use in the clinical study of investigational microbicides.

Sexual diversity among black men who have sex with men in an inner-city community

Dramatic increases in HIV-incidence rates have been documented for Black men who have sex with men (MSM). Moreover, MSM has become a more visible HIV-transmission route in the Black community, in part due to public interest in the "down low" (i.e., "straight" men who also have sex with men). Interviews were conducted with 21 Black MSM in central Brooklyn, New York City, in efforts to understand the diversity of MSM experience in a low income, high HIV-prevalence community. Two thirds of the men identified as either heterosexual (43%) or bisexual (24%) and 15 (71%) MSM reported recent sex with women. Conformity to masculine social role expectations made it difficult to identify sex partners in the community; therefore, men relied on private sex clubs and the Internet. The findings suggest that stigma surrounding both HIV and homosexuality may effectively insure that nonheterosexual preferences and practices remain hidden in the Black community. A focus on sexual orientation and bisexuality has obscured the issue of race in the HIV/AIDS epidemic among Black MSM. In the long term, public health promotion and HIV prevention will require greater tolerance and acceptance of sexual diversity in the Black community.

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.

Measurement of anti-HIV activity of marketed vaginal products and excipients using a PBMC-based in vitro assay

BACKGROUND AND OBJECTIVE

Because microbicides will be applied topically in the vagina, the active agent must be formulated as a gel or cream by combining the active agent with suitable excipients. Although a number of in vitro methods have been developed for testing anti-HIV activity of microbicides, most of these methods have not been used for testing microbicides as a gel or cream.

GOAL

The goal of this study was to measure anti-HIV activity of marketed vaginal gel or cream products and excipients.

STUDY DESIGN

A PBMC-based in vitro method has been developed for the evaluation of anti-HIV activity of gel or cream marketed products and formulated drug delivery systems. This method includes viral exposure to test compounds followed by differential centrifugation and filtration.

RESULTS

Using this methodology, a number of marketed vaginal products showed 83% to 100% inactivation of a variety of X4 and R5 HIV of different clades. Cell viability as determined by the MTT assay for all marketed products was greater than 90%. Some of the excipients also showed anti-HIV activity (20-90%) of their own.

CONCLUSION

This knowledge of baseline anti-HIV activity of vaginal products (cream/gel) and excipients is useful for the final formulation and development of anti-HIV microbicides.

Effect of spermicides on Lactobacillus acidophilus in vitro-nonoxynol-9 vs. Sapindus saponins

Saponins extracted from the fruit pericarp of Sapindus mukorosii were tested for their bactericidal/bacteriostatic property against Lactobacillus acidophilus. Nonoxynol-9 was used as a reference compound for the comparison of activity. Lactobacillus colonies were grown on specific medium (Rogosa SL agar) containing different concentrations of saponins and nonoxynol-9 in an atmosphere of 5% CO2/95% air at 37 degrees C for 72 h. The number and size of colonies were recorded at the end of the experiment and compared with controls. Results indicated that nearly 90% of Lactobacillus colonies with minor reduction in size thrived at 0.05% concentration of saponins whereas only 18% of colonies with approximately 75% reduction in size grew in dishes containing 0.05% nonoxynol-9. At higher concentrations of saponins, there was a gradual, dose-dependent reduction in the number and size of colonies and at 2.5% concentration there was an approximately 55% reduction in the number and 60% reduction in the size of surviving colonies. No lactobacillus colonies, however, grew in dishes containing 0.1% and higher concentrations of nonoxynol-9. The studies indicate that Sapindus saponins as compared to nonoxynol-9 are far less toxic to lactobacillus species and therefore saponins containing spermicidal preparations are likely to be more vaginal-friendly than equivalent nonoxynol-9 preparations.

Considerations and development of topical microbicides to inhibit the sexual transmission of HIV

The increased incidence of HIV/AIDS disease in women aged 15 - 49 years has identified the urgent need for a female-controlled, efficacious and safe vaginal topical microbicide. To meet this challenge, new topical microbicide candidates consisting of molecules or formulations that modify the genital environment (BufferGel, engineered Lactobacillus, over-the-counter lubricants), surfactants (C31D/Savvy, sodium dodecyl sulfate, sodium lauryl sulfate), polyanionic polymers (PRO 2000, beta-cyclodextrin, Carraguard, CAP, D2S, SPL-7013), proteins (cyanovirin-N, monoclonal antibodies, thromspondin-1 peptides, Pokeweed antiviral protein and others), reverse transcription inhibitors (PMPA [Tenofovir ]), UC-781, SJ-3366, DABO and thiourea) and other molecules (NCp7-specific virucides, chemokine receptor agonists/antagonists, WHI-05 and WHI-07) are currently being investigated for activity, safety and efficacy. This review will assess the development of these molecules in the context of cervicovaginal defences and the clinical failure of nonoxynol-9.