Epithelial cell secretions from the human female reproductive tract inhibit sexually transmitted pathogens and Candida albicans but not Lactobacillus

Female reproductive tract (FRT) epithelial cells protect against potential pathogens and sexually transmitted infections. The purpose of this study was to determine if epithelial cells from the upper FRT secrete antimicrobials that inhibit reproductive tract pathogens that threaten women's health. Apical secretions from primary cultures of Fallopian tube, uterine, cervical, and ectocervical epithelial cells were incubated with Neisseria gonorrhoeae, Candida albicans (yeast and hyphal forms), human immunodeficiency virus 1 (HIV-1), and Lactobacillus crispatus before being tested for their ability to grow and/or infect target cells. Epithelial cell secretions from the upper FRT inhibit N. gonorrhoeae and both forms of Candida, as well as reduce HIV-1 (R5) infection of target cells. In contrast, none had an inhibitory effect on L. crispatus. An analysis of cytokines and chemokines in uterine secretions revealed several molecules that could account for pathogen inhibition. These findings provide definitive evidence for the critical role of epithelial cells in protecting the FRT from infections, without comprising the beneficial presence of L. crispatus, which is part of the normal vaginal microflora of humans.