The immune system in the female reproductive tract (FRT) does not mount an attack against HIV or other sexually transmitted infections (STI) with a single endogenously produced microbicide or with a single arm of the immune system. Instead, the body deploys dozens of innate antimicrobials to the secretions of the female reproductive tract. Working together, these antimicrobials along with mucosal antibodies attack many different viral, bacterial and fungal targets. Within the FRT, the unique challenges of protection against sexually transmitted pathogens coupled with the need to sustain the development of an allogeneic fetus have evolved in such a way that sex hormones precisely regulate immune function to accomplish both tasks. The studies presented in this review demonstrate that estradiol and progesterone secreted during the menstrual cycle act both directly and indirectly on epithelial cells and other immune cells in the reproductive tract to modify immune function in a way that is unique to specific sites throughout the FRT. As presented in this review, studies from our laboratory and others demonstrate that the innate immune response is under hormonal control, varies with the stage of the menstrual cycle, and as such is suppressed at mid-cycle to optimize conditions for successful fertilization and pregnancy. In doing so, a window of STI vulnerability is created during which potential pathogens including HIV enter the reproductive tract to infect host targets.

Summary Trappin‐2/Elafin is a serine protease inhibitor that plays a major role as an anti‐inflammatory mediator at mucosal surfaces. In addition, Trappin‐2/Elafin has antibacterial activity against Gram‐positive and Gram‐negative bacterial and fungal pathogens. In this study we examined the production of Trappin‐2/Elafin by epithelial cells from the human upper and lower female reproductive tract as well as its activity as an anti‐human immunodeficiency virus (HIV)‐1 molecule. We found that primary uterine, Fallopian tube, cervical and ectocervical epithelial cells produce Trappin‐2/Elafin constitutively and that production of Trappin‐2/Elafin is enhanced following stimulation with Poly(I:C), especially by the uterine cells. Given the presence of Trappin‐2/Elafin in the reproductive tract, we tested the ability of recombinant Trappin‐2/Elafin to inhibit HIV‐1, an important sexually transmitted pathogen. We found that recombinant Trappin‐2/Elafin was able to inhibit both T‐cell‐tropic X4/IIIB and macrophage‐tropic R5/BaL HIV‐1 in a dose‐dependent manner. The inhibitory activity was observed when virus was incubated with Trappin‐2/Elafin but not when Trappin‐2/Elafin was added to cells either before infection or after infection. This suggests that the mechanism of inhibition is likely to be a direct interaction between HIV‐1 and Trappin‐2/Elafin. Additionally, we measured the levels of secreted Trappin‐2/Elafin in cervico‐vaginal lavages (CVL) from both HIV‐positive and HIV‐negative women and found that average levels of secreted Trappin‐2/Elafin were higher in the CVL from HIV‐negative women, although the values did not reach statistical significance. We also found that women at the secretory phase of the menstrual cycle produced more Trappin‐2/Elafin in CVL relative to women at the proliferative phase of the menstrual cycle. Our data suggest that Trappin‐2/Elafin might be an important endogenous microbicide of the female reproductive tract that is protective against HIV‐1.

BackgroundWe investigated the impact of antimicrobials in cervicovaginal lavage (CVL) from HIV(+) and HIV(−) women on target cell infection with HIV. Since female reproductive tract (FRT) secretions contain a spectrum of antimicrobials, we hypothesized that CVL from healthy HIV(+) and (−) women inhibit HIV infection.Methodology/Principal FindingsCVL from 32 HIV(+) healthy women with high CD4 counts and 15 healthy HIV(−) women were collected by gently washing the cervicovaginal area with 10 ml of sterile normal saline. Following centrifugation, anti-HIV activity in CVL was determined by incubating CVL with HIV prior to addition to TZM-bl cells. Antimicrobials and anti-gp160 HIV IgG antibodies were measured by ELISA. When CXCR4 and CCR5 tropic HIV-1 were incubated with CVL from HIV(+) women prior to addition to TZM-bl cells, anti-HIV activity in CVL ranged from none to 100% inhibition depending on the viral strains used. CVL from HIV(−) controls showed comparable anti-HIV activity. Analysis of CH077.c (clone of an R5-tropic, mucosally-transmitted founder virus) viral inhibition by CVL was comparable to laboratory strains. Measurement of CVL for antimicrobials HBD2, trappin-2/elafin, SLPI and MIP3α indicated that each was present in CVL from HIV(+) and HIV(−) women. HBD2 and MIP3α correlated with anti-HIV activity as did anti-gp160 HIV IgG antibodies in CVL from HIV(+) women.Conclusions/SignificanceThese findings indicate that CVL from healthy HIV(+) and HIV(−) women contain innate and adaptive defense mechanisms that inhibit HIV infection. Our data suggest that innate endogenous antimicrobials and HIV-specific IgG in the FRT can act in concert to contribute toward the anti-HIV activity of the CVL and may play a role in inhibition of HIV transmission to women.

The goal of this study was to examine the role of E 2 in regulating innate immune protection by human uterine epithelial cells (UECs). Recognizing that UECs produce cytokines and chemokines to recruit and activate immune cells as well as viral and bacterial antimicrobials, we sought to examine the effect of E 2 on constitutive and Toll-like receptor (TLR) agonist (lipopolysaccharide (LPS) and poly (I:C))-induced immune responses. The secretion by polarized UECs in culture of interleukin (IL)-6, macrophage inhibitory factor (MIF), and secretory leukocyte protease inhibitor (SLPI) was examined as well as the mRNA expression of human β-defensin-2 (HBD2), tumor necrosis factor (TNF)-α, IL-8, and nuclear factor (NF)-kB. When incubated with E 2 for 24-48 h, we found that E 2 stimulated UEC secretion of SLPI (fourfold) and mRNA expression of HBD2 (fivefold). Moreover, when antibacterial activity in UEC secretions was measured using Staphylococcus aureus, E 2 increased the secretion of soluble factor(s) with antibacterial activity. In contrast, E 2 had no effect on constitutive secretion of proinflammatory cytokines and chemokines by UECs but completely inhibited LPS-and poly (I:C)-induced secretion of MIF, IL-6, and IL-8. Estradiol also reversed the stimulatory effects of IL-1β on mRNA expression of TNF-α, IL-8, and NF-kB by 85, 95, and 70%, respectively. As SLPI is known to inhibit NF-kB expression, these findings suggest that E 2 inhibition of proinflammatory cytokines may be mediated through SLPI regulation of NF-kB. Overall, these findings indicate that the production of cytokines, chemokines, and antimicrobials by UECs are differentially regulated by E 2 . Further, it suggests that with E 2 regulation, epithelial cells that line the uterine cavity have evolved immunologically to be sensitive to viral and bacterial infections as well as the constraints of procreation.

Mucosal surfaces of the female reproductive tract (FRT) contain a spectrum of antimicrobials that provide the first line of defense against viruses, bacteria, and fungi that enter the lower FRT. Once thought to be a sterile compartment, the upper FRT is periodically exposed to pathogens throughout the menstrual cycle. More recently, secretions from the upper FRT have been shown to contribute to downstream protection in the lower FRT. In this review, we examine the antimicrobials in FRT secretions made by immune cells and epithelial cells in the upper and lower FRT that contribute to innate protection. Because each site is hormonally regulated to maintain fertility, this review focuses on the contributions of hormone balance during the menstrual cycle to innate immune protection. As presented in this review, studies from our laboratory and others demonstrate that sex hormones regulate antimicrobials produced by innate immune cells throughout the FRT. The goal of this review is to examine the spectrum of antimicrobials in the FRT and the ways in which they are regulated to provide protection against pathogens that compromise reproductive health and threaten the lives of women.

Problem CCL20/MIP3α is a chemokine for immature dendritic cells as well as an antibacterial against gram-positive and gram-negative bacteria. The role of CCL20/MIP3α as an antiviral is unknown. In this study, we have examined the production of CCL20/MIP3α by epithelial cells from the upper female reproductive tract as well as its activity as an antiviral molecule. Method of study Primary uterine and Fallopian tube epithelial cells were treated with Poly(I:C) and CCL20/MIP3α mRNA and protein was measured by Real-time RT-PCR and ELISA assays. Anti-HIV activity was determined using an indicator cell line TZM-bl and quantified by using a luminometer. Results Primary uterine and Fallopian tube epithelial cells produce CCL20/MIP3α constitutively and the production is enhanced following stimulation with viral double-stranded RNA mimic Poly(I:C). Recombinant CCL20/MIP3α was able to inhibit both T-cell-tropic X4/IIIB and macrophage-tropic R5/BaL HIV-1 when virus was directly incubated with CCL20/MIP3α but not when CCL20/MIP3α was added to cells either prior to infection or post-infection. This suggests that the mechanism of inhibition is likely to be a direct interaction between HIV-1 and CCL20/MIP3α. Conclusion This study demonstrates that CCL20/MIP3α is an important endogenous anti-HIV-1 microbicide of the female reproductive tract.

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 which 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), HIV-1, and Lactobacillus crispatus, prior to 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. Cytokines and chemokines analysis 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.

With aging, a general decline in immune function is observed leading to immune-senescence. Several of these changes are gender specific affecting postmenopausal women. Menopause is a normal part of a woman’s lifecycle and consists of a series of body changes that can last from one to ten years. It is known that loss of sex hormones due to aging results in a reduction of immune functions. However, there remains a major gap in our understanding regarding the loss of immune functions particularly in the female reproductive tract (FRT) following menopause and the role of menopausal hormone therapy (MHT) in protecting against immune senescence. The current review presents an overview of changes in the immune system due to aging, focusing on genital tract immunity in menopausal women and the risks and benefits of using MHT.