Innate immunity in the vagina (part I): estradiol inhibits HBD2 and elafin secretion by human vaginal epithelial cells.

PROBLEM: Vaginal epithelial cells (VEC) are the first line of defense against incoming pathogens in the female reproductive tract. Their ability to produce the anti-HIV molecules elafin and HBD2 under hormonal stimulation is unknown. METHOD OF STUDY: Vaginal epithelial cells were recovered using a menstrual cup and cultured overnight prior to treatment with estradiol (E₂), progesterone (P₄) or a panel of selective estrogen response modulators (SERMs). Conditioned media were recovered and analyzed for protein concentration and anti-HIV activity.
RESULTS: E₂ significantly decreased the secretion of HBD2 and elafin by VEC over 48 hrs, while P4 and the SERMs (tamoxifen, PHTTP, ICI or Y134) had no effect. VEC conditioned media from E₂ -treated cells had no anti-HIV activity, while that from E₂ /P₄ -treated cells significantly inhibited HIV-BaL infection.
CONCLUSION: The menstrual cup allows for effective recovery of primary VEC. Their production of HBD2 and elafin is sensitive to E₂, suggesting that innate immune protection varies in the vagina across the menstrual cycle.