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

Carrageenans effect on neutrophils alone and in combination with LPS in vitro

Influence of sulfated red algal polysaccharides (κ-, λ-, and κ/β-carrageenans) and degraded derivative of κ/β-carrageenan on neutrophils/monocytes activation alone and in combination with lipopolysaccharide was investigated by means of determination of reactive oxygen species production, latex microparticles engulfment, total and extracellular myeloperoxidase induction and the analysis of silhouette and contour two-dimensional images of flattened cells. Carrageenans alone can activate neutrophils with much less potency than lipopolysaccharide (LPS) and the sulfation degree of carrageenans stipulates high activity in this role. On the other hand, carrageenans especially with low contents of sulfate groups are able to interfere with LPS in vitro resulting in reducing inter- and intracellular activation of neutrophils killing mechanisms. Further research is necessary to relate these findings to actions on the whole animal or human in vivo. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1603-1609, 2016.

Benzalkonium chloride causes colposcopic changes and increased susceptibility to genital herpes infection in mice

BACKGROUND

Colposcopy is widely used in clinical microbicide safety testing but not in preclinical small animal studies. Endoscopic colposcopy could be employed in small animals allowing colposcopy to be used as one component in a multifactorial safety testing paradigm.

STUDY DESIGN

We conducted dose-response studies in mice using 2%, 0.2%, or 0.02% benzalkonium chloride (BZK) as the test compound, and using multiple safety end points that included endoscopic colposcopy, susceptibility to vaginal HSV-2 infection, histology, and entry of inflammatory cells into the vagina.

RESULTS

Animals treated with 0.2% or higher BZK experienced vaginal toxicities detectable by all tests used including colposcopy. In contrast, 0.02% BZK produced no significant changes except by histology in which a significant thinning of the vaginal epithelium was seen.

CONCLUSION

Endoscopic colposcopy detected microbicide-elicited changes in the mouse vagina with similar sensitivity to the other endpoints used in these studies and would appear to be useful as part of a multifactorial microbicide safety testing paradigm in mice.

[Application studies of animal models in evaluating safety and efficacy of HIV-1 microbicides]

As the HIV/AIDS pandemic continues unabated, novel prophylactic strategy for the spread of HIV are urgently needed. Topical microbicides are designed to prevent transmission of HIV when applied vaginally or rectally. Although there are many microbicide candidates in the pipeline, animal models for evaluating their safety and efficacy are urgently needed. On the basis of comparing the non-primate small animal models and the non-human primate animal models in evaluating safety and efficacy of HIV microbicides, this review summarizes the major advantages and disadvantages of the relevant animal models. The suggested direction of research that would benefit the development of microbicides is also reviewed.

Increased CCL2 expression and macrophage/monocyte migration during microbicide-induced vaginal irritation

Despite availability of successful prevention strategies, HIV continues to spread at alarming rates, especially among women in developing countries. Vaginal microbicides offer a promising approach for blocking transmission of HIV when condom use cannot be negotiated with male partners. A major problem in the development of vaginal microbicides is chemically induced vaginal irritation, which can enhance the risk of HIV transmission. Evaluation of vaginal irritation prior to clinical trials typically uses an expensive and animal-intensive rabbit vaginal irritation model, which could be supplemented by measuring additional inflammatory biomarkers. We studied several immunological parameters as potential biomarkers of vaginal irritation, using the spermicides nonoxynol-9 and benzalkonium chloride as test microbicides. We measured amounts of cytokines, as well as inflammatory cells, in vaginal tissue lysates and on the vaginal surface. We observed that treatment with the selected microbicides increases quantities of the inflammatory cytokines interleukin-1beta, CXCL8, and CCL2 in the vaginal tissue parenchyma, and of CCL2 on the vaginal surface. This observation was correlated with increases in macrophages in the vaginal parenchyma. We suggest that measurements of CCL2 and macrophages can serve as new inflammatory biomarkers to evaluate the safety of promising novel microbicides for prevention of HIV.