Effect of 17β-estradiol on a Human Vaginal Lactobacillus Crispatus Strain

Lactobacillis and estrogens are essential in vaginal homeostasis. In the present study, we investigated the potential direct effect of 17β-estradiol on a vaginal strain of Lactobacillus cristapus , the major bacterial species of the vaginal microbiota. 17β-estradiol (10 − 6 to 10 − 10 M) has no effect on the growth of L. crispatus but markedly affects its membrane dynamic. This effect appears adaptative and coherent with a signal transduction process. The surface polarity and aggregation potential of the bacteria remains unchanged after exposure to 17β-estradiol but its mean size is significantly reduced. 17β-estradiol also promotes biosurfactant production by L. crispatus and adhesion to vaginal VK2/E6E7 cells. Conversely, the biofilm formation activity of the bacterium is marginally affected. A potential 17β-estradiol binding site was identified by bioinformatics in L. crispatus as the membrane lipid rafts associated SPFH domain containing protein. Taken together, this study reveals that 17β-estradiol can exert direct effects on L. crispatus . This process might be of importance in the vaginal environment physiology by promoting adhesion of Lactobacilli to the mucosa and providing protection against pathogens.