Safety study of nonoxynol-9 as a vaginal microbicide: evidence of adverse effects

Evaluation of the epinecidin-1 peptide as an active ingredient in cleaning solutions against pathogens

We tested the activity of epinecidin-1, a novel antimicrobial peptide structurally related to pleurocidin, in commercial cleaning solutions stored at 4 and 25 degrees C for 7 and 14 days. The peptide's activities against Enterococcus faecalis, Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa, Staphylococcus aureus, Propionibacterium acnes, and Candida albicans were measured in a minimum inhibitory concentration (MIC) determination, minimal bactericidal concentration (MBC) determination, disk diffusion test, and a count of the bacterial numbers. Exposure to epinecidn-1 in a cleaning solution following MIC value comparisons in the disk diffusion test and counts of bacterial numbers after 16, 24, 48, and 72 h suggested that bacterial numbers were much lower than those treated with only commercial cleaning solutions for all bacteria. The efficacy of the antimicrobial activities of inhibiting bacterial numbers by epinecidin-1 in cleaning solutions at a low pH and a low temperature was not affected. Given its simple structure and antimicrobial activity, epinecidin-1 may be a useful component of microbicides designed to prevent pathogen infections and/or remediate abnormal vaginal or skin flora.

Multivalent benzoboroxole functionalized polymers as gp120 glycan targeted microbicide entry inhibitors

Microbicides are women-controlled prophylactics for sexually transmitted infections. The most important class of microbicides target HIV-1 and contain antiviral agents formulated for topical vaginal delivery. Identification of new viral entry inhibitors that target the HIV-1 envelope is important because they can inactivate HIV-1 in the vaginal lumen before virions can come in contact with CD4+ cells in the vaginal mucosa. Carbohydrate binding agents (CBAs) demonstrate the ability to act as entry inhibitors due to their ability to bind to glycans and prevent gp120 binding to CD4+ cells. However, as proteins they present significant challenges in regard to economical production and formulation for resource-poor environments. We have synthesized water-soluble polymer CBAs that contain multiple benzoboroxole moieties. A benzoboroxole-functionalized monomer was synthesized and incorporated into linear oligomers with 2-hydroxypropylmethacrylamide (HPMAm) at different feed ratios using free radical polymerization. The benzoboroxole small molecule analogue demonstrated weak affinity for HIV-1BaL gp120 by SPR; however, the 25 mol % functionalized benzoboroxole oligomer demonstrated a 10-fold decrease in the K(D) for gp120, suggesting an increased avidity for the multivalent polymer construct. High molecular weight polymers functionalized with 25, 50, and 75 mol % benzoboroxole were synthesized and tested for their ability to neutralize HIV-1 entry for two HIV-1 clades and both R5 and X4 coreceptor tropism. All three polymers demonstrated activity against all viral strains tested with EC(50)s that decrease from 15000 nM (1500 microg mL(-1)) for the 25 mol % functionalized polymers to 11 nM (1 microg mL(-1)) for the 75 mol % benzoboroxole-functionalized polymers. These polymers exhibited minimal cytotoxicity after 24 h exposure to a human vaginal cell line.

Functional attenuation of human sperm by novel, non-surfactant spermicides: precise targeting of membrane physiology without affecting structure

BACKGROUND

We have attempted to identify structural, physiological and other targets on human sperm vulnerable to the spermicidal action of two novel series of non-detergent molecules, reported to irreversibly immobilize human sperm in <30 s, apparently without disrupting plasma membrane.

METHODS

Three sperm samples were studied. Scanning and transmission electron microscopy were used to assess structural aberrations of sperm membrane; plasma membrane potential and intracellular pH measurements (fluorometric) were used to detect changes in sperm physiology; reactive oxygen species (ROS, fluorometric) and superoxide dismutase activity (colorimetric) were indicators of oxidative stress; and sperm dynein ATPase activity demonstrated alterations in motor energy potential, in response to spermicide treatment. Post-ejaculation tyrosine phosphorylation of human sperm proteins (immunoblotting) was a marker for functional integrity.

RESULTS

Disulfide esters of carbothioic acid (DSE compounds) caused complete sperm attenuation at > or =0.002% concentration with hyper-polarization of sperm membrane potential (P < 0.001), intracellular alkalinization (P < 0.01), ROS generation (P < 0.05) and no apparent effect on sperm (n = 150) membrane structure. Isoxazolecarbaldehyde compounds required > or =0.03% for spermicidal action and caused disrupted outer acrosomal membrane structure, depolarization of membrane potential (P < 0.001), intracellular acidification (P < 0.01) and ROS generation (P < 0.01). Detergent [nonoxynol-9 (N-9)] action was sustainable at > or =0.05% and involved complete breakdown of structural and physiological membrane integrity with ROS generation (P < 0.001). All spermicides caused functional attenuation of sperm without inhibiting motor energetics. Unlike N-9, DSE-37 (vaginal dose, 200 microg) completely inhibited pregnancy in rats and vaginal epithelium was unchanged (24 h,10 mg).

CONCLUSIONS

The study reveals a unique mechanism of action for DSE spermicides. DSE-37 holds promise as a safe vaginal contraceptive. CDRI Communication No. 7545.

Dermaseptins and magainins: antimicrobial peptides from frogs' skin-new sources for a promising spermicides microbicides-a mini review

Sexually transmitted infections (STIs) and human immunodeficiency virus (HIV), the causative agents of acquired immunodeficiency syndrome (AIDS), are two great concerns in the reproductive health of women. Thus, the challenge is to find products with a double activity, on the one hand having antimicrobial/antiviral properties with a role in the reduction of STI, and on the other hand having spermicidal action to be used as a contraceptive. In the absence of an effective microbicide along with the disadvantages of the most commonly used spermicidal contraceptive worldwide, nonoxynol-9, new emphasis has been focused on the development of more potential intravaginal microbicidal agents. Topical microbicides spermicides would ideally provide a female-controlled method of self-protection against HIV as well as preventing pregnancies. Nonoxynol-9, the only recommended microbicide spermicide, damages cervicovaginal epithelium because of its membrane-disruptive properties. Clearly, there is an urgent need to identify new compounds with dual potential microbicidal properties; antimicrobial peptides should be candidates for such investigations. Dermaseptins and magainins are two classes of cationic, amphipathic alpha-helical peptides that have been identified in the skin extracts of frogs Phyllomedusa sauvagei and Xenopus laevis. Regarding their contraceptive activities and their effect against various STI-causing pathogens, we believe that these two peptides are appropriate candidates in the evaluation of newer and safer microbicides spermicides in the future.

Dual action microbicides: reappraisal of their roles in contraceptive research

Of the variety of contraceptive options available for women, very few provide dual protection against sexually transmitted diseases. Due to increased incidence of human immunodeficiency virus type 1 (HIV-1), genital herpes, hepatitis B and human papilloma virus, development of novel contraceptive strategies that incorporate antiviral activity has become the top priority in contraceptive research. Topical microbicides are now considered to be the last ray of hope, as they would ideally provide protection against unwanted pregnancy, proper lubrication during sexual activity, and preclude the vaginal/rectal transmission of sexually transmitted diseases. A large number of vaginal microbicides are in the preclinical or clinical stages of evaluation for their safety, efficacy and acceptability. However, a major bottleneck in the development of novel mechanism-based dual microbicides has been their detergent-like effects, along with debilitating action on the vaginal microflora. Hence the search is still on for the ideal dual microbicide/s that may obliterate these disadvantages and provide an invincible shield to women in their crusade against unintended pregnancy as well as sexually transmitted diseases. The present review highlights the current scenario towards the development of novel contraceptive strategies to counteract the rampant spread of sexually transmitted diseases, with special reference to HIV/AIDS.

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.

In vitro evaluation of the viability of vaginal cells (VK2/E6E7) and probiotic Lactobacillus species in lemon juice

BACKGROUND

Women, especially in developing countries, most often bear the brunt of HIV infections. The continued lack of viable vaccines and microbicides has made some women resort to using natural products such as lemon or lime juice to avoid infection. Few in vitro studies have been done on the effect of lemon juice on vaginal cells and lactobacilli that constitute the major microbiota in healthy women.

OBJECTIVE

The objective of the present study was to evaluate in vitro the effect of lemon juice on the viability of vaginal cells (VK2/E6E7) and vaginal Lactobacillus species.

METHODS

Vaginal cells were exposed to different concentrations (0-30%) of lemon juice at pH 2.3 and 4.5 for 10 min. Viability was determined by staining the cells with propidium iodide and analysing them by flow cytometry. Lactobacillus organisms were dispensed into microplates with vaginally defined medium + peptone (VDMP) containing different concentrations of lemon juice ranging from 0 to 100%.

RESULTS

Lemon juice at pH 2.3 had a significant (P = 0.03) toxic effect on the vaginal cell line used. At 30% concentration, the vaginal cells were practically non-viable, typified by a 95% loss of viability, whereas at pH 4.5 there was only 5% cell loss. Lemon juice had varying growth inhibitory effects on the Lactobacillus species tested. At pH 4.5 and using 10-30% lemon juice, there was a stimulatory growth effect on certain Lactobacillus species.

CONCLUSIONS

Lemon juice (20-30%) at pH 2.3 was highly toxic to VK2/E6E7 cells, and at pH 4.5 there was no significant effect on the viability of the cells within 10 min. Lemon juice above 10% at pH 2.3 was found to be detrimental to the growth of vaginal lactobacilli. Although lemon juice may be useful in other applications, its use in the vaginal region should be discouraged.

Toll-like receptors and cytokines as surrogate biomarkers for evaluating vaginal immune response following microbicide administration

Topical microbicides are intended for frequent use by women in reproductive age. Hence, it is essential to evaluate their impact on mucosal immune function in the vagina. In the present study, we evaluated nisin, a naturally occurring antimicrobial peptide (AMP), for its efficacy as an intravaginal microbicide. Its effect on the vaginal immune function was determined by localizing Toll-like receptors (TLRs-3, 9) and cytokines (IL-4, 6 , 10 and TNF-α) in the rabbit cervicovaginal epithelium following intravaginal administration of high dose of nisin gel for 14 consecutive days. The results revealed no alteration in the expression of TLRs and cytokines at both protein and mRNA levels. However, in SDS gel-treated group, the levels were significantly upregulated with the induction of NF-κB signalling cascade. Thus, TLRs and cytokines appear as sensitive indicators for screening immunotoxic potential of candidate microbicides.

Whither or wither microbicides?

After disappointing results from all efficacy trials conducted to date, the field of microbicides research now faces substantial challenges. Poor coordination among interested parties and the choice of nonvalidated scientific targets for phase III studies have hampered progress and created mistrust about the use of microbicides as a method to prevent HIV-1 sexual transmission. Although new promising strategies are available, there will need to be serious reappraisals of how decisions are made to advance the next generations of candidates into clinical trials, and the use of appropriate animal models in this process will be critical.

Evaluation of local tolerance of the antiretroviral spermicide (WHI-07)-loaded gel-microemulsion in the porcine female reproductive tract

The local tolerance of the antiretroviral spermicide, WHI-07 (5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxyalaninyl phosphate)-loaded gel-microemulsion was evaluated in a physiologically relevant and sensitive porcine model. Gilts (Duroc) in nonestrus stages of the reproductive cycle received either a single or a daily intravaginal application of 2.0% WHI-07 via a gel-microemulsion for 6 days. Cervicovaginal lavage (CVL) fluid was obtained for up to 72 h after a single exposure and the cellular profile and levels of inflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) were quantitated by flow cytometry and chemiluminescence-based multiplex immunoassay, respectively. The reproductive tract (vagina, cervix, uteri and Fallopian tubes) harvested on day 7 was scored histologically for evidence of mucosal irritation using a new scoring criterion for ten histological endpoints that reflect pathological changes in the epithelial/ subepithelial and vascular/perivascular compartments. When compared with irritant reactions caused by the detergent-type spermicide, benzalkonium chloride (BZK), the scatter profile of CVL immune cells and basal levels of proinflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) in CVL fluid were unaffected by intravaginal exposure to 2% WHI-07. Unlike BZK, endpoint histology of the proximal and distal regions of the reproductive tract from gilts treated with 2.0% WHI-07 via gel-microemulsion for 6 days did not result in mucosal irritation or alteration in the epithelium, subepithelium/lamina propria, vessels/perivascular tissues and underlying/surrounding muscles. Based on surrogate markers for inflammation, leukocyte profile and histologic data for local tolerance, repeated intravaginal administration of WHI-07 via gel-microemulsion as a prophylactic contraceptive is unlikely to cause vaginal irritation.

Safety study of an antimicrobial peptide lactocin 160, produced by the vaginal Lactobacillus rhamnosus

OBJECTIVE

To evaluate the safety of the antimicrobial peptide, lactocin 160.

METHODS

Lactocin 160, a product of vaginal probiotic Lactobacillus rhamnosus 160 was evaluated for toxicity and irritation. An in vitro human organotypic vaginal-ectocervical tissue model (EpiVaginal) was employed for the safety testing by determining the exposure time to reduce tissue viability to 50% (ET-50). Hemolytic activity of lactocin160 was tested using 8% of human erythrocyte suspension. Susceptibility of lactobacilli to lactocin160 was also studied. Rabbit vaginal irritation (RVI) model was used for an in vivo safety evaluation.

RESULTS

The ET-50 value was 17.5 hours for lactocin 160 (4.9 hours for nonoxynol 9, N9). Hemolytic activity of lactocin 160 was 8.2% (N9 caused total hemolysis). Lactobacilli resisted to high concentrations of peptide preparation. The RVI model revealed slight vaginal irritation. An average irritation index grade was evaluated as "none."

CONCLUSIONS

Lactocin 160 showed minimal irritation and has a good potential for intravaginal application.

Preclinical evaluation of a dual-acting microbicidal prodrug WHI-07 in combination with vanadocene dithiocarbamate in the female reproductive tract of rabbit, pig, and cat

The mucosal safety of the combination antiretroviral spermicide,WHI-07 [5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxy alaninyl phosphate] and vanadocene dithiocarbamate (VDDTC), was evaluated in 3 different animal models. Twenty-seven NZW rabbits in four subgroups were exposed intravaginally to a gel-microemulsion (GM) with and without three dose levels of WHI-07 plus VDDTC (0.5+0.06%, 1.0+0.12% and 2.0+0.25%) or 4% nonoxynol-9 (N-9; Conceptrol) for 14 consecutive days. Ten nonestrus gilts (Duroc) in three subgroups received either a single or daily intravaginal application of GM with and without 2.0% WHI-07 plus 0.25% VDDTC or 2.0% benzalkonium chloride (BZK)-containing gel for 6 and 4 consecutive days, respectively. Five cats received a single intravaginal application of GM incorporating 2.0% WHI-07 plus 0.25% VDDTC. Genital tract histopathology was performed in the pig and rabbit at the end of dosing period but after 18 weeks post-dosing in the cat. Porcine cervicovaginal lavage (CVL) fluid was obtained for up to 72 hours after a single exposure and changes in the levels of inflammatory cytokines (IL-1beta, IL-8, IFN-gamma, and TNF-alpha) were quantitated by a multiplexed chemiluminescence-based immunoassay. Rabbit vaginal tissues were evaluated for localized cellular inflammation and in situ apoptosis by immunohistochemical staining for CD45, nuclear factor (NF)-kappa B, and terminal deoxynucleotidyl transferase-mediated FITC-deoxyuridine triphosphate nick-end labeling (TUNEL) using confocal laser scanning microscopy (CLSM), respectively. Vanadium content in selected organs and body fluids from rabbits and pigs was determined by atomic absorption spectroscopy. When compared with 4% N-9 (total irritation score 13-14 out of a possible 16), none of the rabbits given WHI-07 plus VDDTC intravaginally, developed histological alterations such as epithelial erosion, edema, leukocyte influx or vascular congestion characteristic of inflammation (total irritation score 4-6). CD45 and NF-kappa B immunoreactivity was limited to cells within the vascular lumen of both control and WHI-07 plus VDDTC-treated vaginal tissues. TUNEL assay revealed lack of increased apoptotic cells in vaginal mucosa exposed to increasing concentrations of WHI-07 plus VDDTC. Basal levels of proinflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) in porcine CVL were unaffected by intravaginal exposure to WHI-07 plus VDDTC when compared with BZK used as a positive control. Endpoint histology of the reproductive tract from cats and pigs after a single or repeated intravaginal exposure to WHI-07 plus VDDTC, respectively, revealed lack of irritation/inflammation in the epithelium, subepithelium/lamina propria, vessels/perivascular tissues, and underlying/surrounding muscles. Vanadium was not preferentially incorporated into rabbit or porcine tissues and body fluids at levels above 1 microg/g. Based on comparative histologic data and surrogate markers for inflammation, repeated intravaginal administration of WHI-07 plus VDDTC via a gel-microemulsion did not result in vaginal irritation, mucosal toxicity, or systemic absorption of vanadium. Therefore, the combined use of WHI-07 and VDDTC via gel-microemulsion appears safe for topical use as a prophylactic anti-HIV microbicide.

Phase I safety trial of two vaginal microbicide gels (Acidform or BufferGel) used with a diaphragm compared to KY jelly used with a diaphragm

OBJECTIVES

To assess the safety and acceptability of 2 vaginal microbicide gels (Acidform and BufferGel) used with a diaphragm compared to KY Jelly used with a diaphragm among low-risk, sexually abstinent women.

STUDY DESIGN

Eighty-one women enrolled in a randomized, masked, phase I safety study using a diaphragm with Acidform, BufferGel, or KY Jelly for 6 to 10 hours nightly for 14 nights. Physical examination, colposcopy, and lab studies were performed after 1 and 2 weeks of use. Diaries and questionnaires were used to assess user acceptability.

RESULTS

Sixty-nine participants (85%) completed the study. Safety and acceptability appeared similar among the 3 study groups and no serious adverse events related to the study products were reported. Adverse events were mild and anticipated.

CONCLUSIONS

Acidform and BufferGel compared to KY Jelly, when used with diaphragm daily for 14 days, appeared to be safe and acceptable in a small study of low-risk abstinent women.

Cervicovaginal colposcopic lesions associated with 5 nonoxynol-9 vaginal spermicide formulations

OBJECTIVE

This study was undertaken to compare the colposcopic appearance of the cervicovaginal epithelium with spermicide use vs condom use in a low-risk population.

STUDY DESIGN

This was an ancillary study of a trial comparing the efficacy of 5 nonoxynol-9 spermicides. A cohort of women who used condoms without spermicide served as a control group. Colposcopic examinations were performed during product use to identify genital lesions.

RESULTS

One hundred fifty-one participants had 1 or more follow-up examinations. At baseline, study groups differed only by the prevalence of baseline lesions. New lesions were identified at 49% of follow-up visits. Controlling for the presence of a baseline lesion, compared with condom use none of the spermicides were associated with an increase in new lesions (overall odds ratio, 0.8; 95% CI, 0.4-1.6; P = .5); and lesions characterized by epithelial disruption were less frequent with spermicide use (overall odds ratio, 0.3; 95% CI, 0.1-0.6; P < .001).

CONCLUSION

In a low-risk population, women who used nonoxynol-9 spermicides were less likely to have lesions with epithelial disruption, and equally likely to have any new lesion compared with condom use.

Subchronic (26- and 52-week) toxicity and irritation studies of a novel microbicidal gel formulation containing sodium lauryl sulfate in animal models

The safety of an ethylene oxide/propylene oxide gel formulation containing sodium lauryl sulfate (2%, w/w), that could be a potent candidate as a topical microbicide, has been evaluated. More specifically, the subchronic (26- and 52-week) toxicity of the formulation when applied intravaginally as well as its irritating potential for the rectal, penile, eye, skin and buccal mucosa have been examined in animal models. The results showed that the vaginal administration of the gel formulation containing sodium lauryl sulfate once and twice daily (with doses 12 +/- 2 h apart) for 26 weeks to rats and for 52 weeks to rabbits induced slight to moderate histopathological alterations. When the formulation was applied intrarectally to male and female rabbits once and twice daily (with doses 12 +/- 2 h apart) for 14 days, no macroscopic or microscopic changes were reported. For both vaginal and rectal dosing, no effect was seen on the haematology, coagulation and serum chemistry parameters as well as on the body weight of animals and the relative organ weights. Other sporadic macroscopic and histopathological findings were incidental in origin and of no toxicological significance. The gel formulation containing sodium lauryl sulfate was considered as mildly irritating for the penile mucosa of rabbits, non-irritating for the eye of rabbits, mildly irritating for the skin in a rabbit model and non-irritating for the hamster cheek pouch. It is suggested that the gel formulation containing sodium lauryl sulfate is safe for most tissues that could be exposed to the product under normal use.

Evaluation of developmental toxicity of microbicide Nisin in rats

In the present study, we have investigated the developmental toxicity of a naturally occurring peptide, Nisin in rats in order to determine its suitability as a safe vaginal microbicide. Our earlier studies indicated that, Nisin is a dual function microbicide having contraceptive and antibacterial activities. However, as part of the safety evaluation of any vaginal microbicide, it is essential to determine its teratogenic potential in a suitable animal model before it is found suitable to enter clinical trials. Sixty pregnant rats allocated into four groups were orally administered with 10, 25 and 50 mg Nisin/kg/day from day 6 to day 15 of gestation. Individual food/water consumption and body weight changes were measured daily. Nisin did not cause maternal mortality nor did the treated animals show any clinical signs of toxicity when compared to the control animals. There were no biologically significant differences in maternal liver, kidney, thymus, ovary, gravid and empty uterine weights. Mean number of corpora lutea and implantation sites also did not differ in the treated groups when compared to their respective controls. All the fetuses were weighed, sexed and examined carefully for externally visible malformations. No gross external fetal alterations were observed at any dose tested. When stained by the double staining method, no skeletal malformations and visceral defects were observed in the fetuses. The growth and reproductive performance of the F1 progeny was also unaffected. In conclusion, Nisin shows unique clinical potential as a safe prophylactic microbicide to curb the transmission of STIs/HIV and unintended pregnancies.

Differential in vitro inhibitory activity against HIV-1 of alpha-(1-3)- and alpha-(1-6)-D-mannose specific plant lectins: implication for microbicide development

BACKGROUND

Plant lectins such as Galanthus nivalis agglutinin (GNA) and Hippeastrum hybrid agglutinin (HHA) are natural proteins able to link mannose residues, and therefore inhibit HIV-target cell interactions. Plant lectins are candidate for microbicide development.

OBJECTIVE

To evaluate the activity against HIV of the mannose-specific plant lectins HHA and GNA at the cellular membrane level of epithelial cells and monocyte-derived dendritic cells (MDDC), two potential target cells of HIV at the genital mucosal level.

METHODS

The inhibitory effects of HHA and GNA were evaluated on HIV adsorption to genital epithelial HEC-1A cell line, on HIV transcytosis throughout a monolayer of polarized epithelial HEC-1A cells, on HIV adsorption to MDDC and on transfer of HIV from MDDC to autologous T lymphocytes.

RESULTS

HHA faintly inhibited attachment to HEC-1A cells of the R5-tropic HIV-1Ba-L strain, in a dose-dependent manner, whereas GNA moderately inhibited HIV adsorption in the same context, but only at high drug doses. Only HHA, but not GNA, inhibited HIV-1JR-CSF transcytosis in a dose-dependent manner. By confocal microscopy, HHA, but not GNA, was adsorbed at the epithelial cell surface, suggesting that HHA interacts specifically with receptors mediating HIV-1 transcytosis. Both plant lectins partially inhibited HIV attachment to MDDC. HHA inhibited more efficiently the transfer of HIV from MDDC to T cell, than GNA. Both HHA and GNA lacked toxicity below 200 microg/ml irrespective the cellular system used and do not disturb the monolayer integrity of epithelial cells.

CONCLUSION

These observations demonstrate higher inhibitory activities of the lectin plant HHA by comparison to GNA, on HIV adsorption to HEC-1A cell line, HIV transcytosis through HEC-1A cell line monolayer, HIV adsorption to MDDC and HIV transfer from MDDC to T cells, highlighting the potential interest of HHA as effective microbicide against HIV.

Reversible female contraception: current options and new developments

Uncontrolled fertility results in significant infant and maternal mortality and morbidity. Contraception has the potential to reduce this disease burden. Although a rich array of reversible contraceptive methods exists, the need for more effective and user-friendly methods remains. Access to methods and affordability are major barriers in many parts of the world. However, in other areas, successful utilization is limited by convenience factors or a lack of appreciation of fertility risk. To address these issues, new products that require little user effort have been developed. To encourage correct and consistent use of other methods, noncontraceptive benefits are being popularized and new protocols to initiate contraceptive use immediately are being introduced. This review briefly discusses existing contraceptive methods and new developments that are under investigation.

Impact of microbicides and sexually transmitted infections on mucosal immunity in the female genital tract

Human immunodeficiency virus, genital herpes, and other sexually transmitted infections are a critical national and global health priority requiring the rapid development of safe and effective control methods. Topical microbicides, self-administered agents designed for vaginal use, that block transmission at the mucosal surface may provide a realistic method of intervention that could be distributed worldwide. An optimal microbicide should protect against infection but must also be safe, without adversely affecting the mucosal environment, including mediators of host defense. Thus, a critical component in microbicides development is to identify optimal assays that could serve as surrogate markers to predict safety of microbicides prior to embarking on large-scale clinical trials. This will require a greater understanding of the mediators of mucosal immunity in the female genital tract.

Temperature and pH Sensitive Hydrogels: An Approach Towards Smart Semen-Triggered Vaginal Microbicidal Vehicles

Microbicides are drug delivery systems (DDSs) for the prevention of sexual transmission of HIV and other STDs. A topically applied vaginal microbicidal gel should provide uniform coating of vaginal tissue, retention of this gel layer prior to intercourse, and controlled release kinetics of antivirals to inactivate the viral load potentially introduced during sexual activity. Here, we describe the microbicide-oriented characterization of a DDS made with a dual pH sensitive and thermosensitive smart polymer gel composed of a random terpolymer of N-isopropyl acrylamide, butyl methacrylate, and acrylic acid. The system was engineered to coat vaginal tissue with a stable gel layer and to release entrapped model agents in a burst release profile in response to the presence of the infecting agent: semen. The gel rheology, layer erosion properties, model drug release kinetics, and cytocompatibility of the terpolymer system were studied. Negligible erosion of the gel in the presence of vaginal fluid simulant suggests prolonged retention. Burst release of molecular and macromolecular model compounds was observed when the system's pH changed from the vaginal pH to the pH of semen, and cytotoxicity studies showed that the terpolymer is equally cytocompatible as a commonly used polymeric vaginal carrier.

Differential modulation of human lactoferrin activity against both R5 and X4-HIV-1 adsorption on epithelial cells and dendritic cells by natural antibodies

Human lactoferrin (Lf) is an iron binding glycoprotein that is present in several mucosal secretions. Many biological functions have been ascribed to Lf. In the present study, we showed that Lf limited specifically adsorption of R5- and X4-HIV-1-free particles on endometrial epithelial HEC-1A cells, by inhibiting virus adsorption on heparan-sulfated proteoglycans. But, Lf did not interfere with both R5 and X4-HIV transcytosis. We showed also the efficacy of Lf in preventing R5 and X4-HIV capture by dendritic cells. Conversely, we demonstrated that Lf-reacting natural Abs (NAbs) present within i.v. Ig-enhanced HIV attachment on dendritic cells by forming HIV-Lf-NAbs. HIV particles were able to directly interact with Lf following its interaction with NAbs. We also found Lf-reacting natural Abs within cervicovaginal secretions, suggesting the existence of Lf-NAbs complexes in women genital tract in vivo. In conclusion, this study highlights Lf as a potent microbicides and reports new function for NAbs within the genital compartment that may compartment that may abolish the inhibitory activity of microbicide compounds. Thus, we proposed a model in which Lf would appear as a double-edged sword that could have beneficial or detrimental effects depending on both cellular and molecular environments. This study highlights the use of Lf derivates as microbicide candidates to limit such interferences.

Respiratory immunotoxicity: An in vitro assessment

As yet, in vitro assessment of the immunotoxic potency of respiratory agents is not possible. The complexity of the endpoint and the respiratory tract, and the limited availability of well-documented respiratory agents are the main reasons. The evidence that epithelial cells (ECs) are triggered by compounds to express in vitro surface proteins and soluble mediators, has stimulated their use for developing tests for respiratory immunotoxicity. A variety of airway ECs and EC-lines have been assessed, but the available information seems to point at human alveolar cells (e.g., A549) as the most convenient cell type. EC-based test formats with various degrees of complexity have been assessed. Sofar, promising results were obtained using a 3D model using the human A549 lung cell line. Dendritic cells (DCs) have been subjected to intensive research. However, currently available tests are not well suited to discern among the potency of sensitizers. Potential explanations include the lack of standardised protocols for the generation of DCs, no good standards for estimating the quality of in vitro derived DC-cultures, and limited dynamics of the currently used end-points. Alveolar macrophages (AMs) have so far received less attention. This may proof unjustified as macrophages may link innate responses to adaptive immunity. The observation that ECs, DCs and AMs affect each other, suggests that test formats are required combining at least two of these cell types if ranking of compounds according to their sensitising potency is the aim. In addition, the capacity of compounds to cross a cellular membrane is an important property of an immunotoxic compound, which can be assessed only in 3D reconstituted human tissue models. While promising data have been reported for the skin, immunocompetent 3D reconstituted human lung remains to be evaluated for respiratory immunotoxicity. Obviously, the success of any of these simplified test (as compared to the complexity of the immune response) is highly dependent on the availability of early stage biomarkers (expressed at mucosal barrier level) that are predictive for relevant immunotoxicity mechanisms occurring down-stream of the immune response. As yet, such biomarkers are not yet available.

Safety and Acceptability of the Candidate Microbicide Carraguard in Thai Women

OBJECTIVE

To determine the safety and acceptability of vaginal application of Carraguard, a carrageenan-derived candidate microbicide gel.

DESIGN

A randomized, placebo-controlled, triple-blinded clinical trial was conducted in Chiang Rai, northern Thailand.

METHODS

Women were asked to insert one applicator of study gel vaginally at least three times per week (with or without sex) and to use gel with condoms every time they had sex. Safety was assessed by visual inspection of the vagina and cervix, changes in vaginal flora and self-reported symptoms at day 14, month 1 and then monthly for up to 1 year. Acceptability was assessed through reported use of the gel, return of used and unused applicators, and quarterly interviews.

RESULTS

One hundred sixty-five women were randomized: 83 to Carraguard and 82 to the placebo (methylcellulose gel) group. Study gel use was similarly high in both groups throughout the trial with an average of four applicators per week. Carraguard use was not associated with abnormal genital clinical findings, abnormal vaginal flora, Pap smear abnormalities or other abnormal clinical signs or symptoms. Adverse events were mostly mild, not attributed to gel use, and similarly distributed between groups. Participants in both groups reported high acceptability.

CONCLUSIONS

Carraguard can safely be used an average of four times per week with or without sex and is acceptable to Thai women. A Phase III efficacy trial of Carraguard is warranted and is currently ongoing in South Africa.

Mucosal innate immune factors in the female genital tract are associated with vaginal HIV-1 shedding independent of plasma viral load

Recent studies indicate that mucosal innate immune factors modulate HIV-1 infection in vitro. Our interest was to examine the levels of innate mucosal factors for their potential association with HIV-1 shedding in the female genital tract. Vaginal lavages were collected from HIV-1-infected women who had vaginal viral loads (VVL) that were below, within, or above the 90% confidence interval (CI) predicted by their matched plasma viral loads. Innate immune factors [cathepsin D, lactoferrin (Lf), myeloid related protein (MRP)-8, MRP-8/14, secretory leukocyte protease inhibitor, and gp340], cytokines (IL-1beta and TNF-alpha), and chemokines (MIP-1alpha, MIP-1beta, RANTES, and SDF-1alpha) were quantified by ELISA. Leukocyte levels were determined using a leukocyte reagent strip for urinalysis. Lf, MRP-8/14, gp340, and IL-1beta levels were significantly higher in vaginal lavages above the 90% CI and generally correlated with each other and with VVL. Leukocyte levels were significantly higher in the lavages that had virus shedding above the 90% CI and correlated strongly with Lf levels and VVL. In this group of women, these results suggest that the levels of certain innate immune factors are more closely associated with HIV-1 shedding in the genital mucosa than plasma virus concentrations.

Preclinical evaluation of synthetic -2 RANTES as a candidate vaginal microbicide to target CCR5

A potential strategy that can be used to combat the worldwide AIDS epidemic is the development of a vaginal microbicide that prevents the sexual transmission of human immunodeficiency virus type 1 (HIV-1). Certain CC chemokines, including RANTES, MIP-1alpha, and MIP-1beta, might facilitate the development of such microbicides since they potently suppress HIV-1 infection by binding to CCR5, the viral coreceptor used by most sexually transmitted strains of HIV-1 to enter host cells. In this study, we evaluated whether a CCR5-specific fragment of RANTES that lacks two N-terminal residues (-2 RANTES) and possesses especially potent HIV-1 suppressive activity has toxicity profiles conducive to the advancement of testing in candidate microbicide formulations. Analyses were carried out with a synthetic version of the chemokine, which was formulated with either Novasomes 7474, a nonphospholipid liposome, or methylcellulose gel. Dialysis studies demonstrated that the formulated -2 RANTES was released from both vehicles and retained anti-HIV-1 activity. Preclinical toxicity studies carried out with Swiss Webster mouse and New Zealand White rabbit vaginal irritation models demonstrated minimal inflammation and minimal adverse changes in cervicovaginal tissue integrity after short-term (10 min) and long-term (24 h) exposure to formulations containing up to 1 mg/ml of -2 RANTES. Similarly, no toxicity was observed with formulations of bioactive murine RANTES in the Swiss Webster mouse vaginal irritation model. Overall, these preclinical studies suggest that -2 RANTES is suitable for further testing as a candidate anti-HIV-1 microbicide.

Vaginal safety after use of a bioadhesive, acid-buffering, microbicidal contraceptive gel (ACIDFORM) and a 2% nonoxynol-9 product

BACKGROUND

ACIDFORM is a microbicidal and contraceptive candidate with strong buffering capacity.

METHODS

This was a Phase I blinded, randomized and crossover clinical study on two products, ACIDFORM and a commercial nonoxynol-9 (N-9) product (2%), evaluating their vaginal safety in 20 couples aged between 19 and 45 years. The women had regular menses, underwent previous tubal ligation, were not breast-feeding, had no vaginal sign and symptom and were in a stable partnership; both partners had no previous STI. Colposcopy, vaginal microbiology, inflammation markers and subject complaints were studied after coitus. Women were randomly assigned sequentially to receive ACIDFORM 0-30 min (0-30 min before intercourse), ACIDFORM 8-10 h (8-10 h before intercourse) or N-9 0-30 min after a control cycle.

RESULTS

Mild/moderate vulvar irritation was observed in five postcoital test colposcopies, burning and pruritus were reported in six treated cycles and non-irritation-related symptoms were found in five cycles with different treatments. No difference in vaginal pH, Nugent scores, H2O2-producing lactobacillus or leukocytes and interleukin 6 in the cervicovaginal lavage was found between the treatment and control cycles.

CONCLUSIONS

ACIDFORM appears to be safe for clinical use once a day. There is a potential spermicidal-microbicidal role for ACIDFORM as a vaginal flora helper or as a vehicle for products, except N-9.

In vitro preclinical testing of nonoxynol-9 as potential anti-human immunodeficiency virus microbicide: a retrospective analysis of results from five laboratories

The first product to be clinically evaluated as a microbicide contained the nonionic surfactant nonoxynol-9 (nonylphenoxypolyethoxyethanol; N-9). Many laboratories have used N-9 as a control compound for microbicide assays. However, no published comparisons of the results among laboratories or attempts to establish standardized protocols for preclinical testing of microbicides have been performed. In this study, we compared results from 127 N-9 toxicity and 72 efficacy assays that were generated in five different laboratories over the last six years and were performed with 14 different cell lines or tissues. Intra-assay reproducibility was measured at two-, three-, and fivefold differences using standard deviations. Interassay reproducibility was assessed using general linear models, and interaction between variables was studied using step-wise regression. The intra-assay reproducibility within the same N-9 concentration, cell type, assay duration, and laboratory was consistent at the twofold level of standard deviations. For interassay reproducibility, cell line, duration of assay, and N-9 concentration were all significant sources of variability (P < 0.01). Half-maximal toxicity concentrations for N-9 were similar between laboratories for assays of similar exposure durations, but these similarities decreased with lower test concentrations of N-9. Results for both long (>24 h) and short (<2 h) exposures of cells to N-9 showed variability, while assays with 4 to 8 h of N-9 exposure gave results that were not significantly different. This is the first analysis to compare preclinical N-9 toxicity levels that were obtained by different laboratories using various protocols. This comparative work can be used to develop standardized microbicide testing protocols that will help advance potential microbicides to clinical trials.

Polybiguanides, particularly polyethylene hexamethylene biguanide, have activity against human immunodeficiency virus type 1

Polyhexamethylene biguanide (PHMB) is a polybiguanide (PBG) oligomer with antimicrobial activity that is used extensively and safely as a disinfectant. The reported mechanism of PHMB antimicrobial activity, which involves interactions with cell membrane components, suggested that PHMB or other PBG-based compounds might also have antiviral or virucidal activity against the human immunodeficiency virus type 1 (HIV-1). PHMB had modest in vitro activity against both cell-free and cell-associated HIV-1, as well as the ability to interfere with viral binding and entry. However, PHMB was comparable in cytotoxicity to the spermicidal agent nonoxynol-9 (N-9), a compound that has been characterized in previous studies as generally cytotoxic and detrimental to cervicovaginal epithelial integrity. To identify structural variants of PHMB with greater anti-HIV-1 activity and/or less cytotoxicity, modified versions of PHMB incorporating length changes in the hydrocarbon linker units were synthesized and evaluated for in vitro cytotoxicity and inhibition of HIV-1 infectivity. These experiments demonstrated that the PHMB variant polyethylene hexamethylene biguanide (PEHMB) was just as active against HIV-1 as PHMB, yet was much less cytotoxic than either N-9 or PHMB, resulting in an in vitro therapeutic index (TI) approximately 114-fold greater than the TI of N-9. PEHMB, which has been identified in these studies as a promising microbicidal candidate in this family of compounds, will be the focus of further in vitro and in vivo evaluations of anti-HIV-1 activity, toxicity, and mechanisms of action.

Prolonged exposure to the candidate microbicide C31G differentially reduces cellular sensitivity to agent re-exposure

Comparative assays of in vitro cytotoxicity using nonoxynol-9 (N-9) and the candidate microbicides C31G and sodium dodecyl sulfate (SDS) demonstrated that these agents, which are, respectively, characterized as nonionic, amphoteric, and anionic surfactants, differed in their concentration-dependent effects on cell viability, especially after prolonged exposure. We hypothesized that differences in cellular sensitivity may have been due, in part, to cellular changes induced by long-term exposure to each agent. To examine this possibility, HeLa cells were exposed to N-9, C31G, or SDS for extended periods of time and subsequently reassessed for sensitivity to each of these agents. Following 10 continuous days of C31G exposure, HeLa cells were less sensitive to a subsequent C31G exposure compared to cells that had not undergone long-term C31G treatment. Interestingly, long-term C31G exposure also changed subsequent sensitivity to N-9 but not SDS. In contrast, prolonged exposure to either N-9 or SDS did not reduce sensitivity to re-exposure. The effect of long-term C31G exposure was both concentration-dependent and transient, as treated cells reverted to pre-exposure sensitivity in a time-dependent manner following the cessation of C31G exposure. Lipid analyses of cells exposed to C31G for extended durations revealed altered phospholipid profiles relative to C31G-naïve cells. Experiments examining the individual components of C31G demonstrated the involvement of the amine oxide moiety in reductions in cellular sensitivity. These studies, which provide new information concerning the cytotoxicity of surfactant microbicides, suggest that cervicovaginal epithelial cells may have greater in vivo tolerance for products containing C31G through unique interactions between C31G and components of the cellular membranes.

Dawn of non-nucleoside inhibitor-based anti-HIV microbicides

The emergence of HIV/AIDS as a disease spread through sexual intercourse has prompted the search for safe and effective vaginal and rectal microbicides for curbing mucosal viral transmission via semen. Since endogenous reverse transcription is implicated in augmenting the sexual transmission of HIV-1 infection, potential microbicides should have the inherent ability to optimally inhibit both wild-type and drug-escape mutants. The non-nucleoside reverse transcriptase inhibitors (NNRTIs), which bind to an allosteric site on RT, are an important arsenal of drugs against HIV-1. The clinical success of NNRTI-based HIV/AIDS therapies has led to extensive structural and molecular modelling studies of enzyme complexes and chemical synthesis of second- and third-generation NNRTIs. Rationally designed NNRTIs deduced from changes in binding pocket size, shape and residue character that result from clinically observed NNRTI resistance-associated mutations exhibit high binding affinity for HIV-1 RT and robust anti-HIV activity against the wild-type and drug-escape mutants without cytotoxicity. Notably, membrane permeable tight binding NNRTIs have the ability to inactivate cell-free as well as cell-associated HIV-1 in semen without metabolic activation. Consequently, NNRTIs currently under development as experimental microbicides include thiourea-PETT (where PETT stands for phenethylthiazolylthiourea) derivatives (PHI-236, PHI-346 and PHI-443), urea-PETT derivatives (MIV-150), oxypyrimidines (S-DABOs), thiocarboxanilides (UC-781) and diarylpyrimidines (TMC-120). Mucoadhesive formulations of these NNRTIs have been studied for safety and efficacy in animal models and some have entered Phase I safety testing in humans. This review focuses on the structural, biological and preclinical studies relevant to the clinical development of these NNRTIs as molecular virucides intended to prevent the sexual transmission of HIV-1.

Effects of long-term use of nonoxynol-9 on vaginal flora

OBJECTIVE

Products containing nonoxynol-9 have been used as spermicidal contraceptives for many years, but limited data have been published describing the long-term effects of nonoxynol-9 use on the vaginal microbial ecosystem. This longitudinal study was conducted to examine the effects of nonoxynol-9 on the vaginal ecology.

METHODS

Vaginal swabs were obtained from 235 women enrolled in a randomized clinical trial before initiation of use of 1 of 5 different formulations of nonoxynol-9 for contraception, and up to 3 more samples were gathered over 7 months of use. The swab samples were evaluated in a single laboratory. The prevalence of several constituents of the normal vaginal flora was evaluated. The associations between nonoxynol-9 dosage, formulation, average product use per week, and number of sex acts per week were calculated.

RESULTS

The changes in prevalence of vaginal microbes after nonoxynol-9 use were minimal for each of the different nonoxynol-9 formulations. However, when both nonoxynol-9 concentration and number of product uses are taken into account, nonoxynol-9 did have dose-dependant effects on the increased prevalence of anaerobic gram-negative rods (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.1-5.3), H2O2-negative lactobacilli (OR 2.0, 95% CI 1.0-4.1), and bacterial vaginosis (OR 2.3, 95% CI 1.1-4.7).

CONCLUSION

This study demonstrated that most nonoxynol-9 users experienced minimal disruptions in their vaginal ecology. There were no differences between the different formulations evaluated with respect to changes in vaginal microflora. However, independent of the nonoxynol-9 formulation, there was a dose-dependent effect with increased exposure to nonoxynol-9 on the risk of bacterial vaginosis and its associated flora.

LEVEL OF EVIDENCE

II-2.

Anogenitaldermatosen - allergische und irritative Auslosefaktoren Analyse von Daten des IVDK1 und Literaturubersicht. Anogenital dermatoses - allergic and irritative causative factors Analysis of IVDK2 data and review of the literature

BACKGROUND

Anogenital dermatoses (AGD) are common and often very distressing. Clinically it is often unclear if allergic contact dermatitis or irritant dermatitis is involved. In order to optimize therapy and prophylaxis, it is essential to identify relevant allergens or irritants.

PATIENTS AND METHODS

Data of the Information Network of Departments of Dermatology (IVDK, data center in Göttingen) collected between 1999 and 2003 were analyzed. The anogenital area was involved in 1 168 patients with suspected allergic contact dermatitis. Clinical variables and patch test results were statistically compared with the remaining IVDK patch test population, the latter standardized for age and sex.

RESULTS

Allergic contact dermatitis had been suspected prior to patch testing in 39.5 %, while in 24.6 % this diagnosis was eventually confirmed. Irritant contact dermatitis was diagnosed in 11.8 %. Other diagnoses, included balanitis, lichen sclerosus et atrophicus and herpes genitalis. Positive reactions to cinchocaine (6.6 %), bufexamac (3.5 %) and benzocaine (2.4 %) were observed significantly more often among patients with anogenital dermatitis. Among those in whom co-factors were considered important (n = 422), wetness (38.4 %), occlusion (30.3 %), mechanical strain (4.7 %) and heat (3.6 %) were mentioned as irritation factors.

CONCLUSION

Because of the significantly higher frequency of sensitization to cinchocaine, benzocaine and bufexamac in patients with anogenital dermatitis, these ingredients should be used only with caution. According to the literature, ingredients of toiletries, cosmetics and contraceptives of any kind seem to cause allergic contact dermatitis rarely although there are several case reports. Comprehensive patch test including the standard series plus major sensitizers such as cinchocaine, benzocaine and bufexamac, and in particular patients' own skin care products, is recommended.

Spermicidal activity of dermaseptins

OBJECTIVE

The present study was undertaken to elucidate the spermicidal efficacy of two synthetic antimicrobial peptides, dermaseptin (DS1 and DS4).

METHODS

Twenty samples of fresh semen were obtained from patients aged between 23 and 35 years. The ability of DS to kill sperm was evaluated by the Sander-Cramer test under in vitro conditions.

RESULTS

The data showed that sperm motility was inhibited with various concentrations of DS at different intervals ranging from 2 to 240 min. The effective 100% inhibitory concentration (EC(100)) of DS4 in 2 min during the sperm immobilization assay was 100 microg/mL whereas the sperm immobilization of EC(100) of DS1 was 200 microg/mL. The presence of 0.1% chelating agent ethylenediaminetetraacetic acid (EDTA) reduced the EC(100) of DS4 to 10 microg/mL whereas less than a two-time enhancement in DS1 activity was observed upon combination with EDTA. The action of DSs on sperm motility was observed to be dose dependent. Supplementation with pentoxifylline and that with calcium are known to enhance the motility of sperm but they did not prevent the spermicidal action of DSs.

CONCLUSION

This present study indicates that DS is an effective agent to kill sperm. In view of this fact, it is suggested that DS4 has antibacterial, antiviral, antifungal and potentially spermicidal activities and could be a potent vaginal contraceptive.

Intravaginal practices, bacterial vaginosis, and women's susceptibility to HIV infection: epidemiological evidence and biological mechanisms

Intravaginal practices such as "dry sex" and douching have been suggested as a risk factor that may increase women's susceptibility to HIV infection. These behaviours appear common in different populations across sub-Saharan Africa, where practices include the use of antiseptic preparations, traditional medicines, or the insertion of fingers or cloths into the vagina. We systematically review the evidence for the association between women's intravaginal practices and HIV infection. Although a number of cross-sectional studies have shown that prevalent HIV infection is more common among women reporting intravaginal practices, the temporal nature of this association is unclear. Current evidence suggests that bacterial vaginosis, which is a likely risk factor for HIV infection, may be a mediator of the association between intravaginal practices and HIV. Although biologically plausible mechanisms exist, there is currently little epidemiological evidence suggesting that intravaginal practices increase women's susceptibility to HIV infection. Further research into factors that increase women's susceptibility to HIV will help to inform the design of vaginal microbicides and other HIV prevention interventions.

Organotypic human vaginal-ectocervical tissue model for irritation studies of spermicides, microbicides, and feminine-care products

A three-dimensional organotypic vaginal-ectocervical (VEC) tissue model has been developed to test the irritation of topically applied spermicides, microbicides, and vaginal-care products. The in vitro tissue model was reconstructed using normal VEC epithelial cells and is well stratified, containing differentiated basal, suprabasal, intermediate, and superficial cell layers similar to in vivo tissue. The intermediate and superficial cell layers contain glycogen, and the expression of cytokeratins 13 and 14 in the tissue also parallels that of native tissue. The MTT viability assay and histological assessment were used to test inter-lot and intra-lot reproducibility. The MTT average intra-lot coefficient of variation (CV) was less than 10% and the time required to reduce tissue viability by 50% (ET-50) following application of 1% Triton X-100 averaged 1.25+/-0.24h (n=23) upon completion of the 11-day culture period and 1.30 h+/- 0.19 for the same tissues stored overnight at 4 degrees C on agarose gels. The utility of the VEC model for irritation studies was examined by testing commercially available products using the MTT assay and histological assessment. The average ET-50 values ranged between 1.8 and 2.7h for feminine washes, 3.9-6.7 h for spermicides, 6.8-18 h for anti-itch creams, and >18 h for douches, lubricants, and anti-fungal creams. Studies of cytokines released from VEC cultures following product application showed that elevated concentrations of IL-1alpha and IL-1beta were associated with toxicity of test materials. In conclusion, the VEC tissue model is a highly reproducible, non-animal means to assess the irritation of contraceptives, microbicides, and vaginal-care products.

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.

Antimicrobial peptides as microbicidal contraceptives: prophecies for prophylactics--a mini review

The global increase in human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) and sexually transmitted infections (STIs) has led to the introduction of barrier methods, such as condoms. However, drawbacks associated with condoms, such as men being reluctant to use them and women being unable to negotiate their use, have led to the search for better and acceptable alternatives, namely the microbicides. These are gel formulations that, when used prior to sexual intercourse, protect against the transmission of HIV and other STIs. However, after observing the side-effects of nonoxynol-9, a component of the microbicidal formulations available on the market, the focus has shifted to natural available compounds demonstrating the preferred protective effects. Antimicrobial peptides (AMPs) are one such group of compounds present in a wide range of organisms from bacteria to humans. The existing 750 or so, low-molecular-weight, cationic charged peptides are classified into five major groups based on their three-dimensional structure obtained by nuclear magnetic resonance studies. The hypothesized mode of action seems to be the interaction of the positively charged peptides with the negatively charged phospholipids present on the surface of the cell membrane. Various studies have demonstrated the effect of several AMPs, namely, defensins, protegrins, cathelicidins, cecropins, polyphemusins, magainins and melittins, against various STI-causing pathogens and HIV/herpes simplex virus, both in vitro and in vivo. The contraceptive efficacies of magainin and nisin in vitro and in vivo are worth mentioning. We believe these peptides are suitable candidates in the development of newer mechanism-based microbicides in future.

Effects of candidate vaginally-applied microbicide compounds on innate immune cells

Ideally, a vaginally-applied microbicide would be effective against a broad range of pathogens but would have minimal effects on the female genital tract. The aim of this study was to determine if representative candidate detergent-type and sulfated/sulfonated polymer-type microbicides altered the composition or function of innate immune cells normally found in the vaginal mucosa. The effect of microbicide on the composition of vaginal leukocytes was tested using a flow cytometric approach. Application of the detergent cholic acid, but not the sulfated polysaccharide lambda carrageenan, resulted in a significant increase in macrophages at the vaginal epithelial surface compared to control treatment (19.3% macrophages compared to 2.8%; p<0.0004). Phagocytosis of fluorochrome-labeled bacteria by macrophages was inhibited greater than 50% in the presence of 1.0mg/ml of the sulfonated polymer PRO 2000 but was not inhibited by the same concentration of lambda carrageenan. PRO 2000-pulsed macrophages regained phagocytic function after being washed free of the compound. Culture of macrophages with PRO 2000 also resulted in diminished detection of the surface proteins CD11b and CD18. After treated cells were washed free of PRO 2000, these proteins were detected at levels similar to control treated cells. In conclusion, application of a detergent-type microbicide, but not a sulfated polymer, resulted in the infiltration of inflammatory cells at the vaginal epithelial surface. Phagocytic function of macrophages was lost in the presence of 1mg/ml PRO 2000 which may have reflected masking of important cell surface proteins by the microbicide; however, there was no evidence of permanent loss of function upon removal of the compound.

In vitro and in vivo: the story of nonoxynol 9

There is an urgent need to expand the range of interventions to prevent HIV transmission and acquisition, especially those that can be controlled by women. Microbicides, defined as antimicrobial products that can be applied topically for the prevention of HIV and other sexually transmitted infections, may offer one of the most promising preventive interventions, because they could be inexpensive, readily available, and widely acceptable. The first microbial product to be clinically evaluated contained Nonoxynol-9 (nonylpenoxypolyethoxyethanol [N-9]), a nonionic surfactant, as the active agent. This article presents a review of the in vitro, ex vivo, and animal model data on the safety of N-9 and a critical analysis of their predictive power based on the results of multiple safety and efficacy trials.

Discovery of substituted isoxazolecarbaldehydes as potent spermicides, acrosin inhibitors and mild anti-fungal agents

BACKGROUND

The continued endeavour to design novel, non-detergent molecules that can be useful as topical, prophylactic contraceptives has led to the discovery of substituted isoxazolecarbaldehydes as a new class of compounds exhibiting both spermicidal and acrosin inhibitory activities simultaneously.

METHODS

Normal human semen samples were used to detect the spermicidal and acrosin inhibitory activities of the new compounds. Lactobacillus, HeLa and Candida cultures were used to determine the safety of compounds towards normal vaginal flora, their cytotoxicity and anti-fungal activity. Supravital staining and the hypo-osmotic swelling test (HOST) were used to detect the effect on sperm membrane integrity. Nonoxynol-9 (N-9) was used as a reference standard.

RESULTS

The 5- and 3-substituted isoxazolecarbaldehydes showed significant spermicidal [minimum effective concentration (MEC)=0.005-2.5%] and acrosin inhibitory (IC50=3.9-58 x 10(-4) mol/l) activities in several molecules along with weak fungicidal activity against Candida albicans. Lineweaver-Burk and Dixon plot analysis of a representative structure showed non-competitive inhibition of human acrosin enzyme, and the most potent acrosin inhibitors also considerably diminished the induction of the acrosome reaction by Ca2+ ionophore. Some compounds were found to be significantly safer than N-9 towards Lactobacillus acidophilus in vitro at their respective spermicidal MECs. In the cytotoxicity assay, the IC50 of these compounds towards the HeLa cell line was of the same order as N-9 (0.9-0.1 mmol/l); however, in contrast, the compounds exhibited only a moderate effect on sperm membrane integrity.

CONCLUSIONS

This study indicates that 5- and 3-substituted isoxazolecarbaldehydes are 'first generation' multifunctional, spermicidal molecules that hold promise for development as topical contraceptives with useful associated activities that can add considerably to their effectiveness, safety and prophylaxis.

Comparative safety evaluation of the candidate vaginal microbicide C31G

C31G is currently the focus of clinical trials designed to evaluate this agent as a microbicidal and spermicidal agent. In the following studies, the in vivo safety of C31G was assessed with a Swiss Webster mouse model of cervicovaginal toxicity and correlated with results from in vitro cytotoxicity experiments and published clinical observations. A single exposure of unformulated 1% C31G resulted in mild-to-moderate epithelial disruption and inflammation at 2 and 4 h postapplication. The columnar epithelium of the cervix was the primary site of damage, while no perturbation of the vaginal mucosa was observed. In contrast, application of unformulated 1.7% C31G resulted in greater levels of inflammation in the cervical epithelium at 2 h postapplication and severe epithelial disruption that persisted to 8 h postapplication. Application of a nonionic aqueous gel formulation containing 1% C31G resulted in no apparent cervicovaginal toxicity at any time point evaluated. However, formulation of 1.7% C31G did not substantially reduce the toxicity associated with unformulated C31G at that concentration. These observations correlate with findings gathered during a recent clinical trial, in which once-daily applications resulted in no adverse events in women receiving the formulation containing 1% C31G, compared to moderate-to-severe adverse events in 30% of women receiving the 1.7% C31G formulation. The Swiss Webster mouse model was able to effectively discriminate between concentrations and formulations of C31G that produced distinct clinical effects in human trials. The Swiss Webster animal model may be a highly valuable tool for preclinical evaluation of candidate vaginal microbicides.