Immuno-endocrinology of cyclic ovarian function

Role of chemokines in regulating luteal and uterine functions in pregnant cows

Pregnancy is intricately regulated by the interactions between various bioactive substances secreted by the conceptus, uterus, and corpus luteum (CL). Interferon-τ, synthesized and secreted by the conceptus, plays a central role in the interaction mechanism of maternal recognition in cows. Chemokines, chemotaxis mediators that are primarily secreted by immune cells, regulate various reproductive responses in various species. Although there are scattered reports on the potential roles of chemokines in the bovine CL and the uterus during the estrous cycle, there is little information on chemokines in these organs during pregnancy. Therefore, in this review, we discuss the possible physiological roles of chemokines in the CL and uterus of pregnant cows, focusing on our recent findings on chemokines and changes in their receptor expression in the CL and endometrium of cows at some stages of pregnancy.

Double Negative T Regulatory Cells: An Emerging Paradigm Shift in Reproductive Immune Tolerance?

Immune regulation of female reproductive function plays a crucial role in fertility, as alterations in the relationship between immune and reproductive processes result in autoimmune subfertility or infertility. The breakdown of immune tolerance leads to ovulation dysfunction, implantation failure, and pregnancy loss. In this regard, immune cells with regulatory activities are essential to restore self-tolerance. Apart from regulatory T cells, double negative T regulatory cells (DNTregs) characterized by TCRαβ+/γδ+CD3+CD4–CD8– (and negative for natural killer cell markers) are emerging as effector cells capable of mediating immune tolerance in the female reproductive system. DNTregs are present in the female reproductive tract of humans and murine models. However, their full potential as immune regulators is evolving, and studies so far indicate that DNTregs exhibit features that can also maintain tolerance in the female reproductive microenvironment. This review describes recent progress on the presence, role and mechanisms of DNTregs in the female reproductive system immune regulation and tolerance. In addition, we address how DNTregs can potentially provide a paradigm shift from the known roles of conventional regulatory T cells and immune tolerance by maintaining and restoring balance in the reproductive microenvironment of female fertility.

Potential roles of neutrophils in maintaining the health and productivity of dairy cows during various physiological and physiopathological conditions: a review

Neutrophils represent the first line of innate immunity and are the most prominent line of cellular defence against invading microorganisms. On stimulation, they can quickly move through the walls of veins and into the tissues of the body to immediately attack or monitor the foreign antigens. Neutrophils are highly versatile and sophisticated cells which are endowed with highly sensitive receptor-based perception systems. They were traditionally classified as short-lived phagocytes actively involved during infection and inflammation, but recently, it has been seen that neutrophils are capable of detecting the presence of sperms during insemination as well as an implanting embryo in the female reproductive tract. These specialised phagocytes play a major role in tissue remodelling and wound healing, and maintain homeostasis during parturition, expulsion of placenta, folliculogenesis, corpus luteum formation and luteolysis. Here, we review the role played by neutrophils in maintaining homeostasis during normal and inflammatory conditions of dairy cattle. We have summarised the alteration in the expression of some cell adhesion molecules and cytokines on bovine neutrophils during different physiological and physiopathological conditions. Some emerging issues in the field of neutrophil biology and the possible strategies to strengthen their activity during the period of immunosuppression have also been discussed.

Dynamics of Cytokine-like Activity in the Hyperplasic Ovary of Ex-fissiparous Planarians

The origin of infertility in the hyperplasic ovary of ex-fissiparous planarians remains poorly understood. In a previous study we demonstrated that a complex process of early autophagy, followed by apoptotic processes, occurs in the hyperplasic ovary of the freshwater planarian Dugesia arabica. The present study aimed to investigate whether the mRNA expression levels of selected mRNA-like genes are altered in the hyperplasic ovary of the ex-fissiparous freshwater planarian D. arabica compared to the normal ovary. Using human cytokine-specific primers including interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α), we have successfully amplified by real-time polymerase chain reaction some transcripts that could be similar to those amplified in human. The transcript levels of the human-like transcript (IL-1-like and TNF-α-like) were significantly higher, 4.89- and 3.41-fold, respectively, in the hyperplasic ovary compared to the normal ovary (P < 0.05). However, although IL-6-like levels were higher in the hyperplasic ovary than the normal ovary (2.57-fold), this difference was not significant (P > 0.05). Immunohistochemical labeling supported the quantitative real-time PCR, showing that, like their respective mRNA expression levels, IL-1, IL-6, and TNF-α-like proteins are more highly expressed in the hyperplasic ovary than in the normal ovary.

Dual Positive Regulation of Embryo Implantation by Endocrine and Immune Systems--Step-by-Step Maternal Recognition of the Developing Embryo

In humans, HCG secreted from the implanting embryo stimulates progesterone production of the corpus luteum to maintain embryo implantation. Along with this endocrine system, current evidence suggests that the maternal immune system positively contributes to the embryo implantation. In mice, immune cells that have been sensitized with seminal fluid and then the developing embryo induce endometrial differentiation and promote embryo implantation. After hatching, HCG activates regulatory T and B cells through LH/HCG receptors and then stimulates uterine NK cells and monocytes through sugar chain receptors, to promote and maintain pregnancy. In accordance with the above, the intrauterine administration of HCG-treated PBMC was demonstrated to improve implantation rates in women with repeated implantation failures. These findings suggest that the maternal immune system undergoes functional changes by recognizing the developing embryos in a stepwise manner even from a pre-fertilization stage and facilitates embryo implantation in cooperation with the endocrine system.

Gene expression profiles in the bovine corpus luteum (CL) during the estrous cycle and pregnancy: possible roles of chemokines in regulating CL function during pregnancy

To determine functional differences between the corpus luteum (CL) of the estrous cycle and pregnancy in cows, gene expression profiles were compared using a 15 K bovine oligo DNA microarray. In the pregnant CL at days 20–25, 40–45 and 150–160, the expressions of 138, 265 and 455 genes differed by a factor of > 2-fold (P < 0.05) from their expressions in the cyclic CL (days 10–12 of the estrous cycle). Messenger RNA expressions of chemokines (eotaxin, lymphotactin and ENA-78) and their receptors (CCR3, XCR1 and CXCR2) were validated by quantitative real-time PCR. Transcripts of eotaxin were more abundant in the CL at days 40–45 and 150–160 of pregnancy than in the cyclic CL (P < 0.01). In contrast, the mRNA expressions of lymphotactin, ENA-78 and XCR1 were lower in the CL of pregnancy (P < 0.05). Messenger RNAs of CCR3 and CXCR2 were similarly detected both in the cyclic and pregnant CL. Tissue protein levels of eotaxin were significantly higher in the CL at days 150–160 of pregnancy than in the CL at other stages, whereas the lymphotactin protein levels in the CL at days 20–25 of pregnancy were lower (P < 0.05). Immunohistochemical staining showed that CCR3 was expressed in the luteal cells and that XCR1 was expressed in both the luteal cells and endothelial cells. Collectively, the different gene expression profiles may contribute to functional differences between the cyclic and pregnant CL, and chemokines including eotaxin and lymphotactin may regulate CL function during pregnancy in cows.

Morphogenesis of polycystic ovaries as assessed by pituitary-ovarian androgenic function

Despite polycystic ovaries (PCO) being a common morphology in women with polycystic ovary syndrome and regular menstruation, the regulatory principles in the morphogenesis of antral follicles have not yet been elucidated. In recognition of the complementary interaction between androgen-induced expression of the FSH receptor and FSH-augmented expression of the androgen receptor in granulose cells of antral follicles, a possible correlation of antral follicle count (AFC) and pituitary-ovarian androgenic function was investigated in 180 infertile women over days 3-5 of the menstrual cycle. Six discrete types of PCO with decreasing pituitary-ovarian androgenic function were identified: Type I (classical Stein-Leventhal syndrome), Type II (hyperandrogenemism), Type III (singular hyper-LH), Type IV (cryptic hyperandrogenism), Type V (relative LH dominancy) and Type VI (relative FSH dominancy), in parallel to a diminishing number of AFC from Type I to Type VI. Because during the early follicular phase of the cycle until the selection of the dominant follicle, antral follicles are composed of newly emerged healthy follicles plus atretic antral follicles that remain non-ovulated from previous cycles, it is proposed that the six types of PCO may represent the folliculogenetic spectra along which PCO morphogenesis proceeds.

Ovarian theca cells in follicular function

The role of theca cells in every aspect of ovarian follicular function is reviewed. A distinguishing feature of theca cells may be their ability to initiate follicle growth on differentiation from cortical stromal cells, stimulate follicle growth by granulosa cell mitosis through FSH-induced androgen receptor, and cause androgen-stimulated receptor formation of FSH. As LH not only stimulates androgen production by theca cells at tonic levels, but also induces morphological luteinization in addition to androgenesis at surge levels, the dual action concept of LH is proposed. Maturation of the selected dominant follicle and atresia of subordinate antral follicles is interpreted by this concept. Two-way signalling between oocytes and somatic theca cells with growth factors is shown to play a pivotal role in preantral folliculogenesis and atresia. Thus, theca cells have a more significant role in follicular function than previously thought.

Ovarian leukocyte distribution and cytokine/chemokine mRNA expression in follicular fluid cells in women with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) affects 5-10% of reproductive-aged women and is commonly associated with anovulatory infertility. Leukocytes, together with granulosa cells, may contribute to the pathogenesis of PCOS via their ability to secrete an array of cytokines implicated in follicle growth. The aim of this study was to examine leukocyte subtypes in follicular phase ovaries and to quantify cytokine and chemokine mRNA expression in follicular fluid cells obtained at the time of oocyte retrieval before IVF in women with and without PCOS.

METHODS

Ovaries were immunostained for various leukocyte markers [CD3, CD4, CD14, CD15, CD45, CD45RA, CD45RO, CD57 and major histocompatibility complex (MHC) class II]. In addition, follicular fluid cells were subjected to quantitative RT-PCR to evaluate colony-stimulating factor-1 (CSF-1), granulocyte-macrophage (GM)-CSF, interleukins (IL-1beta, IL-6, IL-8 and IL-10), monocyte chemotactic protein (MCP-1) and tumour necrosis factor (TNFalpha) mRNA expression relative to beta-actin.

RESULTS

CD45RO+ cells (activated/memory T lymphocytes) were reduced by 60% in the theca layer of follicles from PCOS women. The relative abundance of macrophages and neutrophils was unchanged. Cytokine and chemokine mRNA transcripts examined were not affected by PCOS status. There was an association between high BMI and high TNFalpha and low IL-6 mRNA expression in follicular cells. IL-6 expression was higher in women who subsequently achieved pregnancy.

CONCLUSIONS

T lymphocytes potentially play a role in the local pathological mechanisms of PCOS. Further studies are required to identify their contribution to the aetiology of this common condition.

Immune cells contribute to systemic cross-talk between the embryo and mother during early pregnancy in cooperation with the endocrine system

In early pregnancy, human chorionic gonadotropin (HCG) stimulates the corpus luteum to produce progesterone that in turn maintains human embryo implantation in the uterus. This inevitable communication through blood circulation can be called 'systemic cross-talk between the embryo and mother'. Despite considerable evidence suggesting that the human corpus luteum cannot be maintained by HCG alone, no other responsible soluble factors have been proposed. We found that peripheral blood mononuclear cells (PBMC) derived from pregnant women promoted progesterone production by human luteal cells and propose that both hormones and immune cells participate in this systemic cross-talk. This systemic cross-talk by immune cells is believed to operate in embryo implantation. Splenocytes derived from pregnant mice promoted endometrial differentiation and embryo implantation in vivo. Human PBMC derived from women early in pregnancy promoted invasion of murine embryos in vitro. In addition, recombinant HCG increased the effects of human PBMC on murine embryo invasion. Human chorionic gonadotropin also increased chemokine production by human PBMC through a lectin-glycan interaction, which is a primitive pathway in the immune system. Furthermore, chemokines were shown to induce human trophoblast invasion. These findings suggest that the immune system positively contributes to systemic cross-talk between the embryo and mother in cooperation with the endocrine system. (Reprod Med Biol 2006; 5: 19-29).

Abnormal gene expression profiles in human ovaries from polycystic ovary syndrome patients

Polycystic ovary syndrome (PCOS) represents the most common cause of anovulatory infertility and affects 5-10% of women of reproductive age. The etiology of PCOS is still unknown. The current study is the first to describe consistent differences in gene expression profiles in human ovaries comparing PCOS patients vs. healthy normoovulatory individuals. The microarray analysis of PCOS vs. normal ovaries identifies dysregulated expression of genes encoding components of several biological pathways or systems such as Wnt signaling, extracellular matrix components, and immunological factors. Resulting data may provide novel clues for ovarian dysfunction in PCOS. Intriguingly, the gene expression profiles of ovaries from (long-term) androgen-treated female-to-male transsexuals (TSX) show considerable overlap with PCOS. This observation provides supportive evidence that androgens play a key role in the pathogenesis of PCOS. Presented data may contribute to a better understanding of dysregulated pathways in PCOS, which might ultimately reveal novel leads for therapeutic intervention.

Chemokines in the corpus luteum: implications of leukocyte chemotaxis

Chemokines are small molecular weight peptides responsible for adhesion, activation, and recruitment of leukocytes into tissues. Leukocytes are thought to influence follicular atresia, ovulation, and luteal function. Many studies in recent years have focused attention on the characterization of leukocyte populations within the ovary, the importance of leukocyte-ovarian cell interactions, and more recently, the mechanisms of ovarian leukocyte recruitment. Information about the role of chemokines and leukocyte trafficking (chemotaxis) during ovarian function is important to understanding paracrine-autocrine relationships shared between reproductive and immune systems. Recent advances regarding chemokine expression and leukocyte accumulation within the ovulatory follicle and the corpus luteum are the subject of this mini-review.

Chemoattractant properties of conditioned medium from equine corpora lutea collected at various stages of the oestrous cycle

This study investigated the chemotactic activity of equine CL at different stages of the oestrous cycle. The purpose of this was to ascertain whether luteal tissue itself contributes to the massive influx of leucocytes around the time of natural and induced luteal regression. Corpora lutea were collected at different stages of dioestrus and after treatment with PGF2alpha. Culture medium harvested after incubation of luteal tissue for 20 h was chemotactic for both polymorphonuclear and mononuclear cells in late dioestrus (before functional regression) as well as after natural and induced luteal regression. By contrast, midluteal tissue showed no chemotactic activity. This is the first report of the ability of equine luteal tissue actively to recruit inflammatory cells in vitro and supports our earlier findings that this infiltration starts prior to functional luteolysis. We hypothesise that this early influx of inflammatory cells may play an active role in luteal regression. Further research is needed to identify the specific chemotactic factor(s).

31P NMR studies of phosphate metabolism in the ovulatory process induced by gonadotropins in perfused rabbit ovary

The concentrations of phosphate metabolites were measured in perfused rabbit ovaries before, during and after ischemia, and during the ovulatory process induced by the administration of pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG) using 31P NMR spectroscopy. A decrease in adenosine triphosphate (ATP) and an increase in inorganic phosphate (Pi) during ischemia were observed. After reperfusion of the ovary, both ATP and Pi levels returned to their initial control levels. These results are in agreement with the results observed in other organ tissues. On the other hand, ATP levels rapidly decreased dose dependently with infusion of HCG during 10 h of perfusion. A decrease in ovarian ATP concentration after infusion of HCG was also confirmed by enzymatic analysis of the extracts from ovarian tissues. On the other hand, significant changes in Pi levels were not observed throughout the perfusion period. Furthermore, significant changes in phosphomonoester (PME) levels, adenosine diphosphate (ADP) levels and intracellular pH were not observed before and during the infusion of HCG. The concentration of cyclic adenosine 3',5'-monophosphate (cAMP) in the perfusate after the perfusion was also measured during the ovulatory period. Within 30 min cAMP significantly increased dose dependently and reached peak levels within 60 min. The concentration of cAMP then gradually decreased. Ovulatory efficacy during the infusion of HCG was also observed. These results suggest that the decreased ATP in the successive processes leading to ovulation probably reflects protein phosphorylation through the activation of the cAMP-dependent protein kinases prior to induction of various chemical reactions related to the initiation of ovulation.

Limited uptake of foreign materials by resident macrophages in murine ovarian tissues

In the present study, the distributions of exogenously administered horseradish peroxidase (HRP) and colloidal carbon in gonadal tissues were observed in both male and female mice using light microscopy. HRP was injected intravenously and colloidal carbon was directly injected into the gonadal parenchyma. Thereafter, the gonads were obtained for histological examination. The results showed that staining of HRP and carbon was detected in the ovaries at a low level. In contrast, much staining was observed in the interstitial cells of the testes for a long period. This suggests that ovarian tissues are less active in the uptake of exogenous materials than testicular tissues in vivo. However, immunohistochemical examination using anti-macrophage antibodies revealed that the ovaries contained a large number of macrophages, as did the testes, under normal conditions. Therefore, the results indicate that resident macrophages in the ovaries exhibit weak endocytic activity of foreign materials in vivo.

Immunohistochemical localization of transforming growth factor-beta 1 beta 2 during folliculogenesis in the quail ovary

Immunohistochemical methods were used to show the presence and distribution of transforming growth factor-beta 1 and beta 2 during folliculogenesis in quail ovarian tissues. The results indicated that both transforming growth factor-beta subtypes are present. Immunolabelling for transforming growth factor-beta 1 demonstrated that prelampbrush oocytes are immunoreactive in the Balbiani complex, and developing and pre-ovulatory oocytes in the zona radiata. Immunolabelling was also associated with granulosa cells. The number of stained granulosa cells decreased during folliculogenesis. In the pre-ovulatory follicles, immunolabelling was found predominantly in the theca interna. Immunolabelling for transforming growth factor-beta 2 was associated with the zona radiata of developing and pre-ovulatory follicles, and with stromal interstitial cells. Moderate immunoreactivity was found in the Balbiani complex of prelampbrush oocytes. Weak immunolabelling was localized in the granulosa cells of prelampbrush follicles, and in a few cells of the theca interna of pre-ovulatory follicles. The immunolocalization of transforming growth factor-beta 1 and -beta 2 in the quail ovary supports their autocrine and/or paracrine role in avian ovarian processes.

Cytokines in the ovary: pathophysiology and potential for pharmacological intervention

The ovary and testis are sites for interaction between the endocrine and immune system via leukocytes and their secreted products, the cytokines. There are convincing data available to show that the gonads are sites of cytokine action and production. In the ovary, cytokines and leukocytes are intimately involved in follicular development, ovulation, and luteal function. A variety of clinical situations may be due to cytokine action in the gonads, and therapeutic manipulation of the immune system may affect reproductive function.

Immunological aspects of ovarian function: role of the cytokines

Interaction between the immune system and reproduction is multiple. Either directly or indirectly through their products, immune cells are associated with the regulation of every level of the hypothalamus-pituitary-ovarian axis. Immune cells are present in the ovaries and their numbers increase during the cycle. During the follicular development cytokines assist granulosa cell growth while inhibiting their differentiation. During the LH peak, an influx of immune cells occurs and several cytokines are released. The rupture of the follicle is considered as an inflammatory reaction. IL-1, TNF-alpha are the main cytokines involved in this process. During the luteal phase, the installation of the corpus luteum needs the setting up of neovascularization. Cytokines are probable candidates for this function, but they also promote cellular differentiation resulting in steroid synthesis. In the absence of pregnancy T lymphocytes and eosinophils are involved in corpus luteum regression. Their products are directly cytotoxic for the luteal cells. They attract macrophages which are locally activated to phagocytose the damaged luteal cells. They can induce apoptosis of endothelial and luteal cells through gene expression. Cytokines are members of a larger regulatory network residing in the ovary and involving hormones and growth factors. The various stages of ovarian cycle will be shown from an immunological point of view. Understanding the role of the cytokines should enable us to go beyond a purely descriptive stage, and allow us to envisage new ovulation induction therapy and treatment in certain cases of premature menopause.

Gonadotropin releasing hormone (GnRH) agonist induces down-regulation of the CD3+CD25+ lymphocyte subpopulation in peripheral blood

PROBLEM

To test whether GnRH agonist could alter in vivo human immune cells and whether the alteration is related to the success of pregnancy in an in vitro fertilization-embryo transfer (IVF-ET) program.

METHODS

Thirty-six infertile patients were enrolled under the long protocol of GnRH agonist (buserelin acetate) and superovulation with gonadotropin from our IVF-ET program. Peripheral B cells, NK cells, CD4+ and CD8+ T cells, and the expression of CD69, CD25, HLA-DR, and CD71 antigens on the T cells were serially examined by dual-color flow cytometry.

RESULTS

B cells, NK cells, CD8+ T cells, and CD71+ T lymphocyte subpopulations were not changed throughout the whole course of treatment. CD4+ T cell and CD25+ T cell subpopulations were significantly down-regulated when the GnRH agonist was used for approximately 2 wk. CD3+CD69+, CD3+CD25+, and CD3+DR+ lymphocyte subpopulations were increased at 7 days (during implantation) and at 14 days after embryo transfer in pregnant patients, but not in patients who failed to get pregnant.

CONCLUSIONS

The GnRH agonist had a transiently immunosuppressive effect on CD4+ and CD25+ T cells, but CD69+, CD25+, and HLA-DR+ T cells were activated during and after successful implantation.

Localization of stress protein-70 in ovine corpora lutea during prostaglandin-induced luteolysis

Accumulation of heat shock (stress) protein-70 (HSP-70) was assessed in corpora lutea of sheep obtained after in vivo administration of a luteolytic dose of prostaglandin (PG) F2 alpha. A quantitative immunofluorescence technique was used to localize inducible HSP-70 production to specific cell-types. The number and intensity of immunostained large luteal cells increased within 2 h of injection of PGF2 alpha. A drop in luteal progesterone concentrations (functional regression) was not manifested until 4 h post-treatment. A dramatic increase in intensely-stained mononuclear leukocytes was observed in luteal tissues at 16 h, when glandular weights had begun to diminish (structural regression). Stress proteins could mediate intracellular protein processing and cell-surface autoimmune mechanisms underlying luteal regression.

Alterations in thymic and bone marrow lymphocyte subpopulations in GnRH agonist treated prepubertal female mice

Complex endocrine relationships exist among the hypothalamus, pituitary, ovaries and thymus. There is also considerable evidence showing gonadotropin releasing hormone (GnRH) involvement in modulating immune system functions. The present study investigated the sequential changes in functional lymphocyte subsets in primary lymphoid tissues of prepubertal female mice in vivo following GnRH agonist treatment in slow release microcapsule formulation. A direct two color immunofluorescence staining followed by flow cytometry was employed. Single i.m injection of agonist significantly decreased both absolute and relative thymic weights and absolute thymocyte counts. No differences, however, were observed in the percentage of thymocytes expressing Thy 1.2, CD4 and CD8. Absolute levels of thymic T cells, CD8 positive cells, immature cells expressing both CD4 and CD8, and immature subsets differentiating toward CD4 were significantly reduced two weeks after agonist treatment. The percentage of bone marrow B cells was also significantly decreased at the second and third weeks following agonist administration. Functional studies to determine in vivo cell-mediated immune function also indicated a significant suppression following agonist administration. These data, together with our earlier observations on secondary lymphoid tissues, suggest a general suppression of lymphocyte maturation at an early stem cell stage of development in prepubertal female mice in vivo.

GnRH agonist induces suppression of lymphocyte subpopulations in secondary lymphoid tissues of prepubertal female mice

PROBLEM

Gonadotropin-releasing hormone (GnRH) agonists are playing an increasing role in the medical management of a variety of diseases. Recent evidence also indicates GnRH immune system interactions.

METHOD

The present study investigated the sequential changes in lymphocyte subpopulations in secondary lymphoid tissues of prepubertal female mice in vivo following Lupron depot administration. A direct two-color immunofluorescence staining followed by flow cytometric analysis was employed.

RESULTS

Following agonist administration, white blood cell counts decreased significantly with decreases in both granulocyte and lymphocyte counts. Blood T-cell and B-cell subsets were also reduced although B cells decreased more markedly. In the spleen, B cells were again reduced more than T cells. There was no selective loss of either CD4 or CD8 subpopulations at any time point, in both spleen and blood. There were no differences in the percentage of lymph node subsets except that B cells decreased in the second week.

CONCLUSIONS

These data indicate that GnRH agonist alters specific lymphocyte subpopulations and, therefore, have the potential for affecting immune system function in vivo.

[Immunity and physiology]

Immune system is described as a physiological system in its function and relations with the other organs (nervous, endocrine, nutritional and reproductive systems). Communications are mediated by common receptors and cytokines. Physiological reality of these interrelations has been discussed in function of stress and age.

The effect of peritoneal macrophage-derived factor(s) on ovarian progesterone secretion and LH receptors: the role of calcium

Macrophages and their secretory products, cytokines, play an integral role in many reproductive processes. In this study we examined the effect of conditioned media from cultured human peritoneal macrophages on progesterone production by granulosa cells and the role of calcium in this process. Macrophages were pretreated with various concentrations of a calcium channel blocker (verapamil) or a calcium ionophore (A23187). Macrophage-conditioned media (MCM) or cell-free media that contained calcium channel modifiers were added at three dose levels to cultured porcine granulosa cells. Progesterone production and LH receptor content were determined. Macrophage-conditioned media alone elevated basal progesterone production, but significantly attenuated granulosa cell LH receptor content. These effects were neither potentiated nor suppressed by pretreating macrophages with verapamil. However, production of the LH receptor lowering factor(s) appeared to be suppressed by calcium ionophore. We conclude that (1) one or more factors produced by macrophages have a net stimulatory effect on basal progesterone production and these factor(s) may not be calcium-dependent and (2) macrophage-derived secretory products reduce granulosa cell LH receptor content. The production of these factor(s) may be calcium-dependent.

New concepts in ovarian regulation: an immune insight

The purpose of the ovary is to produce eggs. In the human, oocyte production occurs cyclically at monthly intervals. The control of egg production is provided by both the endocrine and immune systems. Successful oocyte production is the result of sophisticated communication between the two systems. These interactions allow adaptive processes necessary for continuation of the species.

Immunology of ovarian failure

Ovarian failure is the result of depletion of ovarian follicles. Naturally occurring ovarian failure usually takes place around 50 years of age in the human. Premature ovarian failure occurs in 1% of women and is the result of acceleration of rate of ovarian follicular depletion in the majority of cases. Cytokines are involved in the mechanisms of ovarian follicular atresia, whether it occurs at a normal or accelerated rate. It is the balance between the actions of TGF alpha and TGF beta upon the granulosa cell that determines the fate of a nonluteinized follicle and between LH and INF gamma that determines destiny of a luteinized follicle. When granulosa cells express MHC antigens in response to IFN gamma or genetic stimulus, an autoimmune reaction ensures resulting in follicular atresia. If the immune processes proceed continuously rather than cyclically, premature ovarian failure occurs. Thus, not only do the immunologic and endocrinologic systems need to communicate to allow normal ovarian function, evidence exists to support the concept that they interact in the pathophysiology of ovarian failure.