Estradiol selectively regulates innate immune function by polarized human uterine epithelial cells in culture.

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 beta-defensin-2 (HBD2), tumor necrosis factor (TNF)-alpha, 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-1beta on mRNA expression of TNF-alpha, 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.

Antigen-presenting cells in the female reproductive tract: influence of estradiol on antigen presentation by vaginal cells.

The objective of the present study was to define the afferent arm of the mucosal immune system in the lower female reproductive tract. We report here that antigen presentation by vaginal cells is under hormonal control. When vaginal cells from ovariectomized rats treated with estradiol (0.01-10 microg) were incubated with ovalbumin-specific T cells and ovalbumin, a dose-dependent inhibition of antigen presentation was measured. In time course studies, estradiol given to ovariectomized rats inhibited vaginal cell antigen presentation within 24 h after a single injection, relative to that seen in saline controls. To determine whether changes in antigen presentation were attributable to the effect of estradiol on the number of antigen-presenting cells (APCs) in the vagina, tissues were analyzed by immunohistochemistry. Our findings indicate that estradiol inhibited antigen presentation without affecting the number of major histocompatibility complex class II positive cells and at a time when macrophage/dendritic cells/granulocytes in the vagina increase in response to estradiol treatment. Antibody neutralization studies indicated that antigen presentation by vaginal cells from ovariectomized rats is mediated through class II and involves the expression of transmembrane proteins B7.1 and B7.2. In other studies, vaginal APCs interact with thymus APCs to synergistically enhance antigen presentation under conditions in which vaginal antigen presentation is inhibited by estradiol. Analysis of conditioned media indicates that enhancement of thymus antigen presentation involves the release of a soluble factor(s) into the culture media of vaginal cells. When spleen cells were cocultured with vaginal cells from saline-treated rats, proliferation increased in the presence of concanavalin A and/or phytohemagglutinin and decreased with lipopolysaccharide, relative to spleen cells and mitogen alone. In contrast, when incubated with vaginal cells from estradiol-treated rats, spleen cell proliferation was not affected with concanavalin but was inhibited with phytohemagglutinin and lipopolysaccharide. These studies demonstrate that estradiol regulates antigen presentation by vaginal cells and that vaginal cells, in turn, influence antigen presentation, as well as B and T cell proliferation.

Influence of the estrous cycle on the presence and distribution of immune cells in the rat reproductive tract.

PROBLEM: Previous studies have shown that the uterus and vagina contain cells that can present antigen to ovalbumin-specific T-cells. The objective of the present study was to systematically characterize the immune cells [major histocompatibility complex (MHC) class-II+, macrophages, granulocytes, dendritic cells, and CD8+ cells] present in the uterus and vagina of the rat and to examine their distribution at various stages of the estrous cycle. METHOD OF STUDY: Uterine and vaginal tissues from female rats were selected at various stages of the estrous cycle and were examined by immunohistochemical analysis. MHC class-II (Ia)-positive cells were detected using the OX-6 monoclonal antibody; macrophages, granulocytes, and dendritic cells were detected by OX-41 monoclonal antibody and CD8-positive T-cells were identified by OX-8 monoclonal antibody. RESULTS: Immunohistochemical analysis showed cycle-dependent changes in the immune cell populations in the uterus and vagina. Ia+ cells, macrophages, granulocytes, and dendritic cells were present in large numbers in the stroma of the endometrium and around the glandular epithelium in the uterus at estrus, the stage of the reproductive cycle when estradiol levels are known to be high, relative to those seen at diestrus, when estrogen levels are low and progesterone is the predominant hormone. CD8+ cells were observed in the uterus interspersed between glandular epithelial cells at estrus. Immune cells were more numerous in the vagina, relative to the uterus. OX-6 and OX-41-positive cells were present in greater numbers in the subepithelial layers of the vagina at diestrus, in contrast to estrus. CONCLUSION: This study demonstrates that a variety of immune cells are present in the reproductive tract and that their number and distribution vary in a tissue-specific manner with the stage of the estrous cycle.

Antigen-presenting cells in the female reproductive tract: influence of the estrous cycle on antigen presentation by uterine epithelial and stromal cells.

The objective of the present study was to define the afferent arm of the mucosal immune system in the female reproductive tract. When uterine cells were incubated with ovalbumin-specific T cells and ovalbumin, antigen presentation by purified luminal epithelial cells and stromal cells was measured. Analysis of uterine cells from intact rats throughout the reproductive cycle indicated that antigen presentation is controlled by the female sex hormones. Antigen presentation by epithelial cells was high at diestrus (day 3), when estradiol levels are elevated, and low at estrus and diestrus (days 1 and 2). In contrast, antigen presentation by stromal cells was low at diestrus (day 3) and high at estrus and diestrus (days 1 and 2). Estradiol given to ovariectomized rats stimulated epithelial cell and inhibited stromal cell antigen presentation compared with saline controls. To determine whether uterine cells interact with other cells to facilitate antigen presentation, thymus dendritic-like cells were incubated with uterine epithelial cells. Our findings indicated that antigen presentation is enhanced synergistically, suggesting that epithelial cells can interact with stromal antigen-presenting cells. Antibody neutralization studies indicated that both epithelial and stromal cell antigen presentation is mediated through class II, intercellular adhesion molecule-1 and lymphocyte function-associated molecules-1 alpha and -1 beta, which function as accessory molecules. These studies demonstrate that uterine epithelial and stromal cells are responsive to antigenic challenge and that sex hormones play a central role in regulating antigen presentation by uterine cells.

Antigen-presenting cells in the female reproductive tract: influence of sex hormones on antigen presentation in the vagina.

We report here that the stage of the reproductive cycle and the administration of physiological amounts of oestradiol to ovariectomized rats influences antigen presentation by macrophage/dendritic cells in the vagina. Antigen presentation is elevated when oestradiol levels in blood are low, and reduced just prior to ovulation. Of those hormones tested, only oestradiol lowered vaginal antigen presentation. When progesterone was given along with oestradiol, the inhibitory effect of oestradiol on vaginal antigen presentation was reversed. These studies demonstrate that the vagina is an inductive site and that antigen presentation is under hormonal control. Our results suggest that immunization studies designed to enhance mucosal immunity in the female reproductive tract should take into account the stage of the reproductive cycle when antigen is deposited.

Glucocorticoid regulation of the humoral immune system. Dexamethasone stimulation of secretory component in serum, saliva, and bile.

Dexamethasone, a potent synthetic glucocorticoid, has been shown to increase polymeric immunoglobulin A (IgA) and antigen-specific IgA antibody levels in serum. This response coincided with a decline in IgA and IgG levels in saliva and vaginal secretions after dexamethasone treatment. To investigate the mechanism(s) of glucocorticoid action responsible for the accumulation of polymeric IgA in serum, we undertook in the present study to determine whether dexamethasone alters the production of secretory component (SC). SC is the receptor responsible for transporting IgA from blood and tissues into bile and external secretions. Dexamethasone administered in vivo increased SC levels in serum in a dose- and time-dependent manner. When bile and saliva samples were analyzed, dexamethasone treatment increased saliva SC levels and the production rate of SC by the liver, but had a pronounced inhibitory effect on both bile and salivary levels of IgA. As judged by HPLC, the majority of SC in blood was associated with polymeric IgA and not with monomeric IgA. Immunoblots showed the presence of a 29/27K doublet band of SC in serum from control- and dexamethasone-stimulated rats. These findings indicate that the elevation of polymeric IgA levels in serum after dexamethasone treatment may be due to decreased clearance of IgA into bile. Further, it demonstrates that liver production rate of SC as well as saliva and serum SC levels increase with glucocorticoid treatment. This findings suggests that glucocorticoids, which are known to stimulate hepatocyte SC synthesis in vitro, increase SC levels in blood, possibly as SC fragments that are capable of binding polymeric IgA and retarding its clearance from blood to bile.