Progestin-based contraception regimens modulate expression of putative HIV risk factors in the vaginal epithelium of pig-tailed Macaques.

PROBLEM: In women, the use of progestin-based contraception may increase the risk of vaginal HIV acquisition. We previously showed in macaques that there is a significantly higher simian-human immunodeficiency virus (SHIV) acquisition rate in the luteal phase of the menstrual cycle, which presents a naturally high-progesterone state, and this may be attributable to altered expression of innate immune factors. We hypothesized that progestin-based contraception, especially depot medroxyprogesterone acetate (DMPA), would, in a similar way, affect mucosal immune factors that influence HIV acquisition risk.

METHOD OF STUDY: We used a pig-tailed macaque model to evaluate the effects of two progestin-based contraceptives, DMPA, and levonorgestrel (LNG)/ethinyl estradiol (EE)-based combined oral contraceptives (COCs), on innate mucosal factors. We compared the vaginal epithelial thickness data from previous studies and used cytokine profiling and microarray analysis to evaluate contraception-induced molecular changes in the vagina.

RESULTS

The administration of DMPA caused a reduction in the thickness of the vaginal epithelium relative to that of the follicular or luteal phase. DMPA also induced a significant increase in vaginal levels of the anti-inflammatory cytokine IL-10. Both DMPA- and LNG-based contraception induced a signature of gene expression similar to that of the luteal phase, only more exacerbated, including widespread downregulation of antiviral genes.

CONCLUSION

The use of progestin-based contraception might engender a milieu that poses an increased risk of HIV acquisition as compared to both the luteal and follicular phases of the menstrual cycle.