Development of a Vaginal Fast-Dissolving Insert Combining Griffithsin and Carrageenan for Potential Use Against Sexually Transmitted Infections

Precoital, on-demand topical microbicides to reduce a woman's risk of sexually transmitted infections have been in development for nearly 3 decades, but no product has been approved due to acceptability issues and poor adherence in clinical trials. We set out to develop a self-administered vaginal fast-dissolving insert (FDI) produced by freeze-drying that would deliver safe and effective amounts of the antiviral agents griffithsin (GRFT) and carrageenan (CG) and would have properties women and their partners find acceptable. We evaluated FDI physical criteria, attributes of the gel produced upon dissolving, and GRFT stability. The lead formulation, FDI-024, was selected from 13 candidates and contains 4 mg of GRFT, 15 mg of CG, and excipients (the cryoprotectant sucrose and bulking agents dextran 40 and mannitol). The FDI exhibits good friability and hardness and is stable for at least 6 months at up to 40°C/75% relative humidity. It disintegrates in less than 60 s in a physiologically relevant volume (∼1 mL) of simulated vaginal fluid, forming a viscous semi-solid gel with favorable mucoadhesive and spreading properties. The formulation retains the antiviral activity of GRFT and CG against HIV type 1 and human papillomavirus, respectively, in cell-based assays.

A Small Molecule, Which Competes with MAdCAM-1, Activates Integrin α4β7 and Fails to Prevent Mucosal Transmission of SHIV-SF162P3

Mucosal HIV-1 transmission is inefficient. However, certain viral and host characteristics may play a role in facilitating HIV acquisition and systemic expansion. Cells expressing high levels of integrin α₄β₇ have been implicated in favoring the transmission process and the infusion of an anti-α₄β₇ mAb (RM-Act-1) prior to, and during a repeated low-dose vaginal challenge (RLDC) regimen with SIVmac251 reduced SIV acquisition and protected the gut-associated lymphoid tissues (GALT) in the macaques that acquired SIV. α₄β₇ expression is required for lymphocyte trafficking to the gut lamina propria and gut inductive sites. Several therapeutic strategies that target α₄β₇ have been shown to be effective in treating inflammatory conditions of the intestine, such as inflammatory bowel disease (IBD). To determine if blocking α₄β₇ with ELN, an orally available anti-α₄ small molecule, would inhibit SHIV-SF162P3 acquisition, we tested its ability to block MAdCAM-1 (α₄β₇ natural ligand) and HIV-gp120 binding in vitro. We studied the pharmacokinetic profile of ELN after oral and vaginal delivery in macaques. Twenty-six macaques were divided into 3 groups: 9 animals were treated with ELN orally, 9 orally and vaginally and 8 were used as controls. All animals were challenged intra-vaginally with SHIV-SF162P3 using the RLDC regimen. We found that ELN did not protect macaques from SHIV acquisition although it reduced the SHIV-induced inflammatory status during the acute phase of infection. Notably, integrins can exist in different activation states and, comparing the effect of ELN and the anti-α₄β₇ mAb RM-Act-1 that reduced susceptibility to SIV infection, we determined that ELN induces the active conformation of α₄β₇, while RM-Act-1 inhibits its activation through an allosteric mechanism. These results suggest that inhibition of α₄β₇ activation may be necessary to reduce susceptibility to SIV/SHIV infection and highlight the complexity of anti-integrins therapeutic approach in HIV as well as in IBD and other autoimmune diseases.

To successfully infect a new host through the sexual route, HIV needs to travel to anatomical sites distant from the mucosal site of exposure reaching draining lymph nodes and the gut, where it can expand and disseminate. The characteristics of the vaginal mucosal microenvironment that facilitate HIV acquisition are still unclear. Several lines of evidence suggest that the ability of HIV to infect cells expressing integrin α₄β₇, a receptor that normally guides immune cells to the gut, may constitute an advantage during transmission and blocking α₄β₇ with a laboratory-engineered antibody (mAb) was shown to reduce susceptibility to vaginal SIV infection. However, α₄β₇ can exist in different conformational states that can affect cell function and susceptibility to infection. Herein we show that while the anti-α₄β₇ mAb that reduced susceptibility to infection inhibits α₄β₇ activation, a drug that also binds to α₄β₇, but induces its activation does not decrease susceptibility to SHIV infection. Thus, our results suggest that not only α₄β₇ expression, but also its activation state may play a role in facilitating or inhibiting infection. Our study contributes to the understanding of mechanisms that facilitate HIV transmission, suggesting innovative ways to prevent it.

In vitro and in vivo evaluation of two carrageenan-based formulations to prevent HPV acquisition

Commercial vaccines against human papillomavirus (HPV) have low uptake due to parental autonomy, dosing regimen, cost, and cold chain storage requirements. Carrageenan (CG)-based formulations prevent HPV infection in vitro and in vivo but data are needed on the durability of anti-HPV activity and the effect of seminal plasma (SP). The Population Council's PC-515 gel and the lubricant Divine 9 were tested for their physicochemical properties and anti-HPV activity against HPV16, 18, and 45 pseudoviruses (PsVs). Anti-PsV activity was estimated using the luciferase assay in HeLa cells and the HPV PsV luciferase mouse model. Formulations were applied intravaginally either 2h pre/2h post (-2h/+2h) or 24h pre (-24h) relative to challenge with HPV16 or 45 PsV in PBS or SP/PBS. Both formulations showed broad-spectrum anti-HPV activity in vitro (IC50: 1-20ng/ml), significantly decreasing HPV PsV infection in the mouse model (-2h/+2h, p<0.0001). PC-515 protected better than Divine 9 in the -24h dosing regimen (p<0.0001) and comparable to Divine 9 in the -2h/+2h regimen (p=0.9841). PC-515 retained full activity in the murine model when PsV solutions contained human SP. The durable, potential broad-spectrum anti-HPV activity of CG formulations in the presence of SP supports their further development to prevent HPV acquisition.

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.