Protection of Vaginal Epithelial Cells with Probiotic Lactobacilli and the Effect of Estrogen against Infection by Candida albicans

Abstract

Some probiotic strains of lactobacilli appear to be protective against vulvovaginal candidiasis. The vaginal epithelial cell line (VK2 E6/E7) was used as a model to assess the protective mechanisms of probiotic lactobacilli for cells chal- lenged with Candida albicans. Co-culture of VK2 cells with Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 prior to C. albicans challenge showed reduced adherence of C. albicans to the VK2 cells and inhibition of C. albicans growth. H2O2 concentrations of 0.3 μg/ml, produced by lactobacilli and estrogen-primed VK2 cells, were inhi-bitory to C. albicans growth. C. albicans growth was also inhibited by 10 μg/ml lactic acid. C. albicans infection was increased by 17β-estradiol through induction of hyphal germination. L. reuteri RC-14, but not L. rhamnosus GR-1, H2O2, or lactic acid inhibited estrogen-stimulated hyphal germination. The results of this study support a role for H2O2 and lactic acid from probiotic bacteria in vaginal epithelial protection from candidiasis and a role for 17β-estradiol in the disease by induction of C. albicans hyphal germination.