Leukocyte networks and ovulation

Roles of immune microenvironment in the female reproductive maintenance and regulation: novel insights into the crosstalk of immune cells

Female fertility decline is an accumulative consequence caused by complex factors, among them, the disruption of the immune profile in female reproduction stands out as a crucial contributor. Presently, the effects of immune microenvironment (IME) on the female reproductive process have attracted increasing attentions for their dynamic but precisive roles. Immunocytes including macrophages, dendritic cells, T cells, B cells and neutrophils, with diverse subpopulations as well as high plasticity functioned dynamically in the process of female reproduction through indirect intercellular communication via specific cytokine release transduced by molecular signal networks or direct cell-cell contact to maintain the stability of the reproductive process have been unveiled. The immune profile of female reproduction in each stage has also been meticulously unveiled. Especially, the application of single-cell sequencing (scRNA-seq) technology in this process reveals the distribution map of immune cells, which gives a novel insight for the homeostasis of IME and provides a research direction for better exploring the role of immune cells in female reproduction. Here, we provide an all-encompassing overview of the latest advancements in immune modulation within the context of the female reproductive process. Our approach involves structuring our summary in accordance with the physiological sequence encompassing gonadogenesis, folliculogenesis within the ovaries, ovulation through the fallopian tubes, and the subsequent stages of embryo implantation and development within the uterus. Our overarching objective is to construct a comprehensive portrayal of the immune microenvironment (IME), thereby accentuating the pivotal role played by immune cells in governing the intricate female reproductive journey. Additionally, we emphasize the pressing need for heightened attention directed towards strategies that focus on immune interventions within the female reproductive process, with the ultimate aim of enhancing female fertility.

ACTH impairs the migratory and secretory profile of mononuclear cells during proestrus in cattle

The aim was to evaluate the effect of ACTH on the mechanisms involved in peripheral blood mononuclear cells (PBMCs) infiltration into the ovary during dairy cattle proestrus. Regarding this, proper expression pattern of adhesion molecules must take place both in PBMCs and in endothelial cells. Argentinian Holstein cows (n = 12) were treated with 100 IU of ACTH every 12 h for 4 days before ovulation when ovariectomy was performed (day 18). Blood samples were taken on day 15 (0 h) and immediately before (72 h) and after (74 h) the last ACTH administration. In PBMCs, flow cytometry was performed to analyze CD44, CD11b and CD62-L expression along with gene expression of chemokines' receptors. Interleukin (IL)-4 and tumor necrosis factor-α (TNF-α) production was analyzed by flow cytometry after exposing PBMCs to autologous follicular fluid. In ovarian blood vessels, expression of the vascular endothelium cell adhesion-1 (VCAM-1) and the platelet endothelial cell adhesion molecule-1 was evaluated by immunohistochemistry. In T-lymphocytes, the expression of CD44 and CD11b was lower at 72 h in ACTH-treated cows (P < 0.05). In monocytes, the expression of CD11b and CD62-L was lower at 72 h in ACTH-treated cows (P < 0.05). Also, the percentage of IL-4+ cells was higher in ACTH-treated cows, meanwhile, the percentage TNF-α+ cells was lower in ACTH-treated cows (P < 0.05). Finally, in the vessels associated with the preovulatory follicle VCAM-1 immunoexpression was lower in ACTH-treated cows (P < 0.05). Here, we present novel insights into the effect of stress during the preovulatory period on the inflammatory pathway necessary for ovulation.

Identification of transcriptome characteristics of granulosa cells and the possible role of UBE2C in the pathogenesis of premature ovarian insufficiency

BACKGROUND

Premature ovarian insufficiency (POI) is an important cause of infertility characterized by the functional decline of the ovary. Granulosa cells (GCs) around oocytes are critical for folliculogenesis, and GC dysfunction is one of the important etiologies of POI. The aim of this study was to explore the potential biomarkers of POI by identifying hub genes and analyze the correlation of biomarkers with immune infiltration in POI using RNA profiling and bioinformatics analysis.

METHODS

RNA sequencing was performed on GCs from biochemical POI (bPOI) patients and controls. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were used to explore the candidate genes. qRT‒PCR was performed to verify the expression of hub genes. Western blot, Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine (EdU) assays, TUNEL (TdT-mediated dUTP Nick-End Labeling) and flow cytometry analysis were used to validate the possible role of ubiquitin-conjugating enzyme 2C (UBE2C) in POI. CIBERSORT was adopted to explore immune cell infiltration and the correlation between UBE2C and immune cells in bPOI.

RESULTS

Through analysis of differentially expressed genes (DEGs) and WGCNA, we obtained 143 candidate genes. After construction of the protein‒protein interaction (PPI) network and analysis with Cytoscape, 10 hub genes, including UBE2C, PBK, BUB1, CDC20, NUSAP1, CENPA, CCNB2, TOP2A, AURKB, and FOXM1, were identified and verified by qRT‒PCR. Subsequently, UBE2C was chosen as a possible biomarker of POI because knockdown of UBE2C could inhibit the proliferation and promote the apoptosis of GCs. Immune infiltration analysis indicated that monocytes and M1 macrophages may be associated with the pathogenesis of POI. In addition, UBE2C was negatively correlated with monocytes and M1 macrophages in POI.

CONCLUSIONS

This study identified a hub gene in GCs that might be important in the pathogenesis of POI and revealed the key role of UBE2C in driving POI. Immune infiltration may be highly related with the onset and etiology of POI.

Common mechanisms of physiological and pathological rupture events in biology: novel insights into mammalian ovulation and beyond

Ovulation is a cyclical biological rupture event fundamental to fertilisation and endocrine function. During this process, the somatic support cells that surround the germ cell undergo a remodelling process that culminates in breakdown of the follicle wall and release of a mature egg. Ovulation is driven by known proteolytic and inflammatory pathways as well as structural alterations to the follicle vasculature and the fluid-filled antral cavity. Ovulation is one of several types of systematic remodelling that occur in the human body that can be described as rupture. Although ovulation is a physiological form of rupture, other types of rupture occur in the human body which can be pathological, physiological, or both. In this review, we use intracranial aneurysms and chorioamniotic membrane rupture as examples of rupture events that are pathological or both pathological and physiological, respectively, and compare these to the rupture process central to ovulation. Specifically, we compared existing transcriptomic profiles, immune cell functions, vascular modifications, and biomechanical forces to identify common processes that are conserved between rupture events. In our transcriptomic analysis, we found 12 differentially expressed genes in common among two different ovulation data sets and one intracranial aneurysm data set. We also found three genes that were differentially expressed in common for both ovulation data sets and one chorioamniotic membrane rupture data set. Combining analysis of all three data sets identified two genes (Angptl4 and Pfkfb4) that were upregulated across rupture systems. Some of the identified genes, such as Rgs2, Adam8, and Lox, have been characterised in multiple rupture contexts, including ovulation. Others, such as Glul, Baz1a, and Ddx3x, have not yet been characterised in the context of ovulation and warrant further investigation as potential novel regulators. We also identified overlapping functions of mast cells, macrophages, and T cells in the process of rupture. Each of these rupture systems share local vasoconstriction around the rupture site, smooth muscle contractions away from the site of rupture, and fluid shear forces that initially increase and then decrease to predispose one specific region to rupture. Experimental techniques developed to study these structural and biomechanical changes that underlie rupture, such as patient-derived microfluidic models and spatiotemporal transcriptomic analyses, have not yet been comprehensively translated to the study of ovulation. Review of the existing knowledge, transcriptomic data, and experimental techniques from studies of rupture in other biological systems yields a better understanding of the physiology of ovulation and identifies avenues for novel studies of ovulation with techniques and targets from the study of vascular biology and parturition.

Immunological and Metabolic Causes of Infertility in Polycystic Ovary Syndrome

Infertility has been recognized as a civilizational disease. One of the most common causes of infertility is polycystic ovary syndrome (PCOS). Closely interrelated immunometabolic mechanisms underlie the development of this complex syndrome and lead to infertility. The direct cause of infertility in PCOS is ovulation and implantation disorders caused by low-grade inflammation of ovarian tissue and endometrium which, in turn, result from immune and metabolic system disorders. The systemic immune response, in particular the inflammatory response, in conjunction with metabolic disorders, insulin resistance (IR), hyperadrenalism, insufficient secretion of progesterone, and oxidative stress lead not only to cardiovascular diseases, cancer, autoimmunity, and lipid metabolism disorders but also to infertility. Depending on the genetic and environmental conditions as well as certain cultural factors, some diseases may occur immediately, while others may become apparent years after an infertility diagnosis. Each of them alone can be a significant factor contributing to the development of PCOS and infertility. Further research will allow clinical management protocols to be established for PCOS patients experiencing infertility so that a targeted therapy approach can be applied to the factor underlying and driving the "vicious circle" alongside symptomatic treatment and ovulation stimulation. Hence, therapy of fertility for PCOS should be conducted by interdisciplinary teams of specialists as an in-depth understanding of the molecular relationships and clinical implications between the immunological and metabolic factors that trigger reproductive system disorders is necessary to restore the physiology and homeostasis of the body and, thus, fertility, among PCOS patients.

Identification of immune cell infiltration and effective biomarkers of polycystic ovary syndrome by bioinformatics analysis

BACKGROUND

Patients with polycystic ovary syndrome (PCOS) exhibit a chronic inflammatory state, which is often accompanied by immune, endocrine, and metabolic disorders. Clarification of the pathogenesis of PCOS and exploration of specific biomarkers from the perspective of immunology by evaluating the local infiltration of immune cells in the follicular microenvironment may provide critical insights into disease pathogenesis.

METHODS

In this study, we evaluated immune cell subsets and gene expression in patients with PCOS using data from the Gene Expression Omnibus database and single-sample gene set enrichment analysis.

RESULTS

In total, 325 differentially expressed genes were identified, among which TMEM54 and PLCG2 (area under the curve = 0.922) were identified as PCOS biomarkers. Immune cell infiltration analysis showed that central memory CD4⁺ T cells, central memory CD8⁺ T cells, effector memory CD4⁺ T cells, γδ T cells, and type 17 T helper cells may affect the occurrence of PCOS. In addition, PLCG2 was highly correlated with γδ T cells and central memory CD4⁺ T cells.

CONCLUSIONS

Overall, TMEM54 and PLCG2 were identified as potential PCOS biomarkers by bioinformatics analysis. These findings established a basis for further exploration of the immunological mechanisms of PCOS and the identification of therapeutic targets.

A single-cell gene expression atlas of human follicular aspirates: Identification of leukocyte subpopulations and their paracrine factors

Leukocytes are in situ regulators critical for ovarian function. However, little is known about leukocyte subpopulations and their interaction with follicular cells in ovulatory follicles, especially in humans. Single-cell RNA sequencing (scRNA-seq) was performed using follicular aspirates obtained from four IVF patients and identified 13 cell groups: one granulosa cell group, one thecal cell group, 10 subsets of leukocytes, and one group of RBC/platelet. RNA velocity analyses on five granulosa cell populations predicted developmental dynamics denoting two projections of differentiation states. The cell type-specific transcriptomic profiling analyses revealed the presence of a diverse array of leukocyte-derived factors that can directly impact granulosa cell function by activating their receptors (e.g., cytokines and secretory ligands) and are involved in tissue remodeling (e.g., MMPs, ADAMs, ADAMTSs, and TIMPs) and angiogenesis (e.g., VEGFs, PGF, FGF, IGF, and THBS1) in ovulatory follicles. Consistent with the findings from the scRNA-seq data, the leukocyte-specific expression of CD68, IL1B, and MMP9 was verified in follicle tissues collected before and at defined hours after hCG administration from regularly cycling women. Collectively, this study demonstrates that this data can be used as an invaluable resource for identifying important leukocyte-derived factors that promote follicular cell function, thereby facilitating ovulation and luteinization in women.

The role of macrophages phenotypes in the activation of resolution pathways within human granulosa cells

BACKGROUND

Inflammatory state within the ovaries can disrupt normal follicular dynamics, leading to reduced oocyte quality and infertility. How the production of inflammatory mediators generated by macrophages with different gene expression profile (M1 and M2) might activate inflammatory pathways, such as cyclooxygenase-2 (COX-2) and 5-, 12-, and 15-lipoxygenase (LOX), in human granulosa cells (hGCs) remains unclear.

METHODS

In this study, we evaluated how M1 and M2 macrophages found in the ovaries affect the functions of hGCs isolated from women undergoing assisted reproductive technology (ART) and human ovarian granulosa COV434 cells. For this purpose, a model of interaction between hGCs and COV434 cells and conditioned media (CMs) obtained from culture of M0, M1 and M2 macrophages was established. We used real-time PCR and western blotting to detect the expression of COX-2 and 5-, 12-, and 15-LOX as biomarkers of oocyte competence.

RESULTS

Our data showed that M2 macrophages with anti-inflammatory characteristics were able to significantly increase the expression of COX-2 in hGCs. We also demonstrated that M1 macrophages with pro-inflammatory characteristics were able to significantly increase the expression of 12-LOX in hGCs. However, there was no observed expression of 5-LOX and no significant alteration in the expression of 15-LOX in hGCs. Regarding COV434 cells, we found that CM from M2 macrophage resulted in an increase in COX-2, 5-LOX and 15-LOX mRNA and protein levels. No expression of 12-LOX by COV434 cells was observed when exposed to CMs from M1 and M2 macrophages.

CONCLUSIONS

Our research indicated that the production of pro-resolving mediators by hGCs can, at least in part, reverse the physiological inflammation present in the ovaries.

Impact of obesity on medically assisted reproductive treatments

Increasing evidence has demonstrated that obesity impairs female fertility and negatively affects human reproductive outcome following medically assisted reproduction (MAR) treatment. In the United States, 36.5% of women of reproductive age are obese. Obesity results not only in metabolic disorders including type II diabetes and cardiovascular disease, but might also be responsible for chronic inflammation and oxidative stress. Several studies have demonstrated that inflammation and reactive oxygen species (ROS) in the ovary modify steroidogenesis and might induce anovulation, as well as affecting oocyte meiotic maturation, leading to impaired oocyte quality and embryo developmental competence. Although the adverse effect of female obesity on human reproduction has been an object of debate in the past, there is growing evidence showing a link between female obesity and increased risk of infertility. However, further studies need to clarify some gaps in knowledge. We reviewed the recent evidence on the association between female obesity and infertility. In particular, we highlight the association between fat distribution and reproductive outcome, and how the inflammation and oxidative stress mechanisms might reduce ovarian function and oocyte quality. Finally, we evaluate the connection between female obesity and endometrial receptivity.

AACC Guidance Document on Laboratory Testing for the Assessment of Preterm Delivery

Identifying women with preterm labor who will go on to deliver prematurely is crucial to improving outcomes for mother and baby and for saving healthcare resources. Even among those with symptoms, the number of women who deliver preterm is low, and thus the low positive predictive value (PPV) and high negative predictive value (NPV) associated with available biomarkers does not substantially reduce the uncertainty of the clinical diagnosis. While there is some promise in the use of fetal fibronectin (fFN), interleukin 6 (IL-6), or placental alpha microglobulin 1 (PAMG-1) for predicting preterm birth (PTB), their use is unlikely to provide considerable clinical value in populations with a low prevalence. To provide real clinical benefit, a biomarker must demonstrate a high PPV to allow identification of the minority of symptomatic women who will deliver prematurely. As none of the currently available biomarkers exhibit this performance characteristic, we do not recommend their routine clinical use in populations with a pre-test probability of PTB of <5%. Limiting biomarker testing to only high-risk women identified on the basis of cervical length or other characteristics will increase the pre-testprobability in the tested population, thereby improving PPV. PAMG-1 is associated with a higher PPV than fFN and may show clinical utility in populations with a higher pre-test probability, but further work is required to conclusively demonstrate improved outcomes in this patient group.

The Release of Peripheral Immune Inflammatory Cytokines Promote an Inflammatory Cascade in PCOS Patients via Altering the Follicular Microenvironment

Background

Hormones and immune imbalance are critical factors in polycystic ovary syndrome (PCOS). The alternation of immune microenvironment of oocytes may play a significant role in infertility of PCOS patients.

Objective

This study explores the role of follicular fluid microenvironment change in inflammatory pathways activation of granulosa cells (GCs) in PCOS women infertility.

Methods

We enrolled 27 PCOS patients and 30 controls aged 22 to 38 years who underwent IVF and collected their luteinized granulosa cells (LGCs). Meanwhile, a granulosa-like tumor cell line (KGN) as a cell-model assisted this study. Key inflammatory markers in human ovarian GCs and follicular fluid were detected by RT-qPCR, Western blotting, or ELISA. The KGN cells were treated with follicle supernatant mixed with normal medium to simulate the microenvironment of GCs in PCOS patients, and the inflammation indicators were observed. The assembly of NLRP3 inflammasomes was detected by immunofluorescence techniques. Dihydroethidium assay and EdU proliferation assay were used to detect ROS and cell proliferation by flow cytometry.

Results

Compared with normal controls (n = 19), IL-1β (P = 0.0005) and IL-18 (P = 0.021) in the follicular fluid of PCOS patients (n = 20) were significantly increased. The NF-κB pathway was activated, and NLRP3 inflammasome was formatted in ovarian GCs of PCOS patients. We also found that inflammation of KGN cells was activated with LPS irritation or stimulated by follicular fluid from PCOS patients. Finally, we found that intracellular inflammation process damaged mitochondrial structure and function, which induced oxidative stress, affected cellular metabolism, and impaired cell proliferation.

Conclusion

Inflammatory microenvironment alteration in the follicular fluid of PCOS patients leads to activated inflammatory pathway in GCs, serving as a crucial factor that causes adverse symptoms in patients. This study provides a novel mechanism in the inflammatory process of PCOS.

Fetal-derived macrophages persist and sequentially maturate in ovaries after birth in mice

Macrophages, which are highly diverse in different tissues, play a complex and vital role in tissue development, homeostasis, and inflammation. The origin and heterogeneity of tissue-resident monocytes and macrophages in ovaries remains unknown. Here we identify three tissue-resident monocyte populations and five macrophage populations in the adult ovaries using high-dimensional single cell mass cytometry. Ontogenic analyses using cell fate mapping models and cell depletion experiments revealed the infiltration of ovaries by both yolk sac and fetal liver-derived macrophages already during the embryonic development. Moreover, we found that both embryonic and bone marrow-derived macrophages contribute to the distinct ovarian macrophage subpopulations in the adults. These assays also showed that fetal-derived MHC II-negative macrophages differentiate postnatally in the maturing ovary to MHC II-positive cells. Our analyses further unraveled that the developmentally distinct macrophage types share overlapping distribution and scavenging function in the ovaries under homeostatic conditions. In conclusion, we report here the first comprehensive analyses of ovarian monocytes and macrophages. In addition, we show that the mechanisms controlling monocyte immigration, the phenotype of different pools of interstitial macrophages, and the interconversion capacity of fetal-derived macrophages in ovaries are remarkably different from those seen in other tissue niches.

Patients who failed to conceive following an in vitro fertilization cycle can be clustered into different failure causes using gene expression hierarchical analysis†

The patient's response to an IVF stimulation protocol is highly variable and thus difficult to predict. When a cycle fails, there are often no apparent or obvious reasons to explain the failure. Having clues on what went wrong during stimulation could serve as a basis to improve and personalize the next protocol. This exploratory study aimed to investigate if it is possible to distinguish different failure causes or different follicular responses in a population of nonpregnant IVF patients. Using qRT-PCR, we analyzed a panel of genes indicative of different failure causes in patients who did not achieve pregnancy following an IVF cycle. For each patient, a pool of follicular cells from all aspirated follicles was used as a sample which gives a global picture of the patient's ovary and not a specific picture of each follicle. We performed hierarchical clustering analysis to split the patients according to the gene expression pattern. Hierarchical analysis showed that the population of nonpregnant IVF patients could be divided into three clusters. Gene expression was significantly different, and each cluster displayed a particular gene expression pattern. Follicular cells from patients in clusters 1, 2 and 3 displayed respectively a pattern of gene expression related to large incompetent follicles with a higher apoptosis (over matured), to follicles not ready to ovulate (under mature) and to an excess of inflammation with no visible symptoms. This study reinforces the idea that women often have different response to the same protocol and would benefit from more personalized treatments.

Contribution of the immune system to follicle differentiation, ovulation and early corpus luteum formation

Much of what we know about the involvement of the immune system in periovulatory follicle differentiation, ovulation and subsequent formation of the corpus luteum in cattle is drawn from the findings of studies in several mammalian livestock species. By integrating published histological data from cattle, sheep and pigs and referring back to the more comprehensive knowledge bank that exists for mouse and humans we can sketch out the key cells of the immune system and the cytokines and growth factors that they produce that are involved in follicle differentiation and luteinization, ovulation and early follicle development. These contributions are reviewed and the key findings, discussed.

S100a4-Cre-mediated deletion of Patched1 causes hypogonadotropic hypogonadism: role of pituitary hematopoietic cells in endocrine regulation

Hormones produced by the anterior pituitary gland regulate an array of important physiological functions, but pituitary hormone disorders are not fully understood. Herein we report that genetically-engineered mice with deletion of the hedgehog signaling receptor Patched1 by S100a4 promoter-driven Cre recombinase (S100a4-Cre;Ptch1fl/fl mutants) exhibit adult-onset hypogonadotropic hypogonadism and multiple pituitary hormone disorders. During the transition from puberty to adult, S100a4-Cre;Ptch1fl/fl mice of both sexes develop hypogonadism coupled with reduced gonadotropin levels. Their pituitary glands also display severe structural and functional abnormalities, as revealed by transmission electron microscopy and expression of key genes regulating pituitary endocrine functions. S100a4-Cre activity in the anterior pituitary gland is restricted to CD45+ cells of hematopoietic origin, including folliculo-stellate cells and other immune cell types, causing sex-specific changes in the expression of genes regulating the local microenvironment of the anterior pituitary. These findings provide in vivo evidence for the importance of pituitary hematopoietic cells in regulating fertility and endocrine function, in particular during sexual maturation and likely through sexually dimorphic mechanisms. These findings support a previously unrecognized role of hematopoietic cells in causing hypogonadotropic hypogonadism and provide inroads into the molecular and cellular basis for pituitary hormone disorders in humans.

Human granulosa cells function as innate immune cells executing an inflammatory reaction during ovulation: a microarray analysis

Ovulation has been compared to a local inflammatory reaction. We performed an in silico study on a unique, PCR validated, transcriptome microarray study to evaluate if known inflammatory mechanisms operate during ovulation. The granulosa cells were obtained in paired samples at two different time points during ovulation (just before and 36 hours after ovulation induction) from nine women receiving fertility treatment. A total of 259 genes related to inflammation became significantly upregulated during ovulation (2-80 fold, p<0.05), while specific leukocyte markers were absent. The genes and pathway analysis indicated NF-KB-, MAPK- and JAK/STAT signalling (p<1.0E-10) as the major pathways involved in danger recognition and cytokine signalling to initiate inflammation. Upregulated genes further encoded enzymes in eicosanoid production, chemo-attractants, coagulation factors, cell proliferation factors involved in tissue repair, and anti-inflammatory factors to resolve the inflammation again. We conclude that granulosa cells, without involvement from the innate immune system, can orchestrate ovulation as a complete sterile inflammatory reaction.

The estrogen-macrophage interplay in the homeostasis of the female reproductive tract

BACKGROUND

Estrogens are known to orchestrate reproductive events and to regulate the immune system during infections and following tissue damage. Recent findings suggest that, in the absence of any danger signal, estrogens trigger the physiological expansion and functional specialization of macrophages, which are immune cells that populate the female reproductive tract (FRT) and are increasingly being recognized to participate in tissue homeostasis beyond their immune activity against infections. Although estrogens are the only female gonadal hormones that directly target macrophages, a comprehensive view of this endocrine-immune communication and its involvement in the FRT is still missing.

OBJECTIVE AND RATIONALE

Recent accomplishments encourage a revision of the literature on the ability of macrophages to respond to estrogens and induce tissue-specific functions required for reproductive events, with the aim to envision macrophages as key players in FRT homeostasis and mediators of the regenerative and trophic actions of estrogens.

SEARCH METHODS

We conducted a systematic search using PubMed and Ovid for human, animal (rodents) and cellular studies published until 2018 on estrogen action in macrophages and the activity of these cells in the FRT.

OUTCOMES

Our search identified the remarkable ability of macrophages to activate biochemical processes in response to estrogens in cell culture experiments. The distribution at specific locations, interaction with selected cells and acquisition of distinct phenotypes of macrophages in the FRT, as well as the cyclic renewal of these properties at each ovarian cycle, demonstrate the involvement of these cells in the homeostasis of reproductive events. Moreover, current evidence suggests an association between estrogen-macrophage signaling and the generation of a tolerant and regenerative environment in the FRT, although a causative link is still missing.

WIDER IMPLICATIONS

Dysregulation of the functions and estrogen responsiveness of FRT macrophages may be involved in infertility and estrogen- and macrophage-dependent gynecological diseases, such as ovarian cancer and endometriosis. Thus, more research is needed on the physiology and pharmacological control of this endocrine-immune interplay.

Ovulation: Parallels With Inflammatory Processes

The midcycle surge of LH sets in motion interconnected networks of signaling cascades to bring about rupture of the follicle and release of the oocyte during ovulation. Many mediators of these LH-induced signaling cascades are associated with inflammation, leading to the postulate that ovulation is similar to an inflammatory response. First responders to the LH surge are granulosa and theca cells, which produce steroids, prostaglandins, chemokines, and cytokines, which are also mediators of inflammatory processes. These mediators, in turn, activate both nonimmune ovarian cells as well as resident immune cells within the ovary; additional immune cells are also attracted to the ovary. Collectively, these cells regulate proteolytic pathways to reorganize the follicular stroma, disrupt the granulosa cell basal lamina, and facilitate invasion of vascular endothelial cells. LH-induced mediators initiate cumulus expansion and cumulus oocyte complex detachment, whereas the follicular apex undergoes extensive extracellular matrix remodeling and a loss of the surface epithelium. The remainder of the follicle undergoes rapid angiogenesis and functional differentiation of granulosa and theca cells. Ultimately, these functional and structural changes culminate in follicular rupture and oocyte release. Throughout the ovulatory process, the importance of inflammatory responses is highlighted by the commonalities and similarities between many of these events associated with ovulation and inflammation. However, ovulation includes processes that are distinct from inflammation, such as regulation of steroid action, oocyte maturation, and the eventual release of the oocyte. This review focuses on the commonalities between inflammatory responses and the process of ovulation.

The expression of CXCR4 is induced by the luteinizing hormone surge and mediated by progesterone receptors in human preovulatory granulosa cells

The chemokine CXC motif ligand 12 (CXCL12) and its cognate receptor, CXCR4, have been implicated in the ovulatory process in various animal models. However, little is known about the expression and regulation of CXCL12 and CXCR4 and their functions during the ovulatory period in the human ovary. In this study, we characterized the expression patterns of CXCL12 and CXCR4 in preovulatory follicles collected before the luteinizing hormone (LH) surge and at defined hours after hCG administration in women with the regular menstrual cycle. The levels of mRNA and protein for CXCR4 were increased in granulosa cells of late ovulatory follicles, whereas CXCL12 expression was constant in follicles throughout the ovulatory period. Both CXCR4 and CXCL12 were localized to a subset of leukocytes around and inside the vasculature of human preovulatory follicles. Using a human granulosa cell culture model, the regulatory mechanisms and functions of CXCL12 and CXCR4 expression were investigated. Human chorionic gonadotropin (hCG) stimulated CXCR4 expression, whereas CXCL12 expression was not affected, mimicking in vivo expression patterns. Both RU486 (progesterone receptor antagonist) and CoCl2 (HIFs activator) blocked the hCG-induced increase in CXCR4 expression, whereas AG1478 (EGFR inhibitor) had no effect. The treatment with CXCL12 had no effect on granulosa cell viability but decreased hCG-stimulated CXCR4 expression.

Expression of cytokine-induced neutrophil chemoattractant suppresses tumor necrosis factor alpha expression and thereby prevents the follicles from undergoing atresia and apoptosis

Aim

Cytokine-induced neutrophil chemoattractant (CINC/gro) is a CXC family chemokine, similar to interleukin-8 in rats, and is one of the factors that regulates ovulation. However, the mechanism that regulates atresia of the ovaries postovulation is not clearly defined.

Methods

Whether antibody-blocking of CINC/gro can alter the number of ovulated oocytes and modulate neutrophil infiltration was investigated. The effect of the antibody on the level of inflammatory cytokine production and follicular atresia was examined. Apoptosis was measured by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method and via analysis of the messenger RNA expression of Bcl-2 and Bcl2-associated X (Bax).

Results

The anti-CINC/gro antibody treatment decreased the number of ovulated oocytes. The messenger RNA levels of cyclooxygenase-2 and interleukin-1 beta were decreased by the antibody treatment, whereas that of tumor necrosis factor (TNF) alpha was increased. The TUNEL analysis revealed a larger number of apoptotic cells in the antibody group, compared with those in the control group, as well as a significant increase in the Bax/Bcl-2 ratio 24 hours after human chorionic gonadotropin administration.

Conclusion

These findings suggest that ovulation is accelerated by neutrophil infiltration into the theca layer. The CINC/gro appears to synergize with interleukin-1 beta for ovulation. By contrast, the data suggest that CINC/gro expression suppresses TNF alpha expression and that CINC/gro expression therefore prevents the follicles from undergoing atresia and apoptosis.

Myeloperoxidase in blood neutrophils during normal and abnormal menstrual cycles in women of reproductive age

INTRODUCTION

We previously reported that granulocyte colony-stimulating factor (G-CSF) plays a critical role in ovulation, suggesting that neutrophils may maintain ovulation. We assessed myeloperoxidase (MPO), a major and specific enzyme of neutrophils, in women with abnormal and normal menstrual cycles to clarify the relationship between MPO and ovulation.

METHODS

We analyzed MPO activity in blood neutrophils of women with abnormal menstrual cycles (indicative of anovulation, n = 12) and age- and body mass index-matched normal menstrual cycles (indicative of ovulation, n = 24) using two parameters as a marker of MPO, Neut X and mean peroxidase index (MPXI).

RESULTS

MPO of women with abnormal menstrual cycles was significantly lower than that of women with normal menstrual cycles [Neut X: 62.6 ± 1.1 (mean ± standard error of the mean) vs. 66.2 ± 0.3, P = 0.009; MPXI: -0.54 ± 1.66 vs. 4.91 ± 0.53, P = 0.008]. Among women with normal menstrual cycles, MPO was highest in the follicular phase (Neut X: 67.0 ± 0.3; P = 0.033).

CONCLUSION

The difference in MPO between women with abnormal and normal menstrual cycles and the upregulation of MPO before ovulation suggest that neutrophils and MPO are closely related to ovulation.

Myeloperoxidase as a Potential Target in Women With Endometriosis Undergoing IVF

As infertility is intimately associated with endometriosis, the levels of myeloperoxidase (MPO), a leukocyte enzyme and an oxidative stress marker, were determined in a case-control prospective study of 68 women with and without endometriosis undergoing in vitro fertilization in the outpatient fertility center within a tertiary care academic medical center. Measured values included plasma and follicular fluid (FF) concentrations of MPO, plasma estradiol, as well as oocyte quality, fertilization, implantation, and pregnancy rates in these women. In FF (mean ± standard error of mean [SEM]), the MPO concentrations (ng/mL) for controls were 4.3 ± 0.37, mild endometriosis (stages I-II) 3.9 ± 0.17, and moderate/severe endometriosis (stages III-IV) 16.6 ± 12.5 ( P < 0.0143). In FF, among patients supplemented with vitamins E and C, the MPO levels decreased significantly only in moderate/severe endometriosis from 25.3 ± 22.0 ng/mL to 4.9 ± 1.61 ng/mL, respectively. Plasma levels of MPO between groups did not change. Outcome data revealed a trend toward decreased percentage of mature oocytes, implantation rate, and clinical pregnancy rate with severity of endometriosis and MPO levels. Myeloperoxidase may be a potential oxidative stress target for endometriosis-associated infertility.

Intracellular lipid dysregulation interferes with leukocyte function in the ovaries of meat-type hens under unrestricted feed intake

Meat-type Red-feather country hens fed ad libitum (AD-hens) exhibit obesity-associated morbidities and a number of ovarian irregularities. Leukocyte participations in ovarian activities are unstudied in AD-hens. In contrast to feed-restricted hens (R-hens), ovulatory process of the F1 follicle appeared delayed in AD-hens in association with reduced F1 follicle progesterone content, gelatinase A (MMP-2) and collagenase-3 (MMP-13) activities coincident with elevated IL-1β and no production (P<0.05), and increased leukocyte infiltration of inflamed necrotic follicle walls. Extracts of AD-hen F1 follicle walls induced greater leukocyte migration than extracts from F1 follicle wall extracts of R-hens (P<0.05). Co-cultures of granulosa cells with increasing numbers of leukocytes from either AD-hens or R-hens exhibited dose dependent reductions in progesterone production and increases in cell death. AD-hen leukocytes were less proapoptotic than their R counterparts (P<0.05). Granulosa MMP-13 and MMP-2 activities were also suppressed in the co-cultures with heterophils or monocytes in a dose-dependent manner (P<0.05). AD heterophils and R monocytes had a greater inhibitory effect on MMP activities in the co-cultures than their respective counterparts (P<0.05). Both basal and LPS-induced IL-1β secretion and MMP-22 or MMP-2 activities in freshly isolated AD-hen leukocytes were reduced (P<0.05). Exposure of AD or R leukocytes to 0.5mM palmitate impaired IL-1β secretion and MMP-22 or MMP-2 activity. Inhibition of ceramide synthesis with FB1 and ROS production with n-MPG scavenging rescued MMP activity and IL-1β production in palmitate treated heterophils, but exacerbated monocyte suppression. These latter findings suggest that intracellular lipid dysregulation in leukocytes contributes to ovarian dysfunction in AD-hens.

Female mice with loss-of-function ITCH display an altered reproductive phenotype

Major progress in deciphering the role of the E3 ligase, ITCH, in animal physiology has come from the generation and identification of Itch loss-of-function mutant mice (itchy). Mutant mice display an autoimmune-like phenotype characterized by chronic dermatitis, which has been attributed to increased levels of ITCH target proteins (e.g. transcription factors JUNB and CJUN) in T cells. Autoimmune disorders also exist in humans with Itch frameshift mutations resulting in loss of functional ITCH protein. Recent phenotypic analysis of male itchy mice revealed reduced sperm production, although cross breeding experiments showed no difference in litter size when male itchy mice were bred to wild type females. However, a reduction in litter sizes did occur when itchy females were bred to wild type males. Based on these results, characterization of female reproductive function in itchy mice was performed. Developmental analysis of fetuses at gestational day 18.5, cytological evaluation of estrous cyclicity, histopathological analysis of ovaries, and protein analysis were used to investigate the itchy reproductive phenotype. Gross skeletal and soft tissue analysis of gestational day 18.5 itchy fetuses indicated no gross developmental deformities. Itchy females had reduced implantation sites, decreased corpora lutea, and increased estrous cycle length due to increased number of days in estrus compared to controls. Alterations in the expression of prototypical ITCH targets in the ovaries were not indicated, suggesting that an alteration in an as yet defined ovary-specific ITCH substrate or interaction with the altered immune system likely accounts for the disruption of female reproduction. This report indicates the importance of the E3 ligase, ITCH, in female reproduction.

Chemokine Ligand 20: A Signal for Leukocyte Recruitment During Human Ovulation?

Ovulation is one of the cornerstones of female fertility. Disruption of the ovulatory process results in infertility, which affects approximately 10% of couples. Using a unique model in which the dominant follicle is collected across the periovulatory period in women, we have identified a leukocyte chemoattractant, chemokine ligand 20 (CCL20), in the human ovary. CCL20 mRNA is massively induced after an in vivo human chorionic gonadotropin (hCG) stimulus in granulosa (>10 000-fold) and theca (>4000-fold) cells collected during the early ovulatory (12-18 h) and late ovulatory (18-34 h) periods after hCG administration. Because the LH surge sets in motion an inflammatory reaction characterized by an influx of leukocytes and CCL20 is known to recruit leukocytes in other systems, the composition of ovarian leukocytes (CD45+) containing the CCL20 receptor CCR6 was determined immediately prior to ovulation. CD45+/CCR6+ cells were primarily natural killer cells (41%) along with B cells (12%), T cells (11%), neutrophils (10%), and monocytes (9%). Importantly, exogenous CCL20 stimulated ovarian leukocyte migration 59% within 90 minutes. Due to the difficulties in obtaining human follicles, an in vitro model was developed using granulosa-lutein cells to explore CCL20 regulation. CCL20 expression increased 40-fold within 6 hours after hCG, was regulated partially by the epithelial growth factor pathway, and was positively correlated with progesterone production. These results demonstrate that hCG dramatically increases CCL20 expression in the human ovary, that ovarian leukocytes contain the CCL20 receptor, and that CCL20 stimulates leukocyte migration. Our findings raise the prospect that CCL20 may aid in the final ovulatory events and contribute to fertility in women.

The role of eicosanoids in 17α, 20β-dihydroxy-4-pregnen-3-one-induced ovulation and spawning in Danio rerio

This study employed a hormone bioassay to characterize the eicosanoids involved in zebrafish ovulation and spawning, in particular the prostaglandin (PG) products of cyclooxygenase (COX) metabolism and the leukotriene (LT) products of lipoxygenase (LOX) metabolism. Exposure to the teleost progestogen 17α, 20β-dihydroxy-4-pregnen-3-one (17,20βP) induced ovulation, but not spawning, in solitary females and both ovulation and spawning in male-female pairs. Transcription of the eicosanoid-synthesizing enzymes cytosolic phospholipase A2 (cPLA(2)) and COX-2 increased and LTC(4) synthase decreased in peri-ovulatory ovaries of 17,20βP-exposed fish. Ovarian PGF(2α) levels increased post-spawning in 17,20βP-exposed fish, but there was no difference in LTB(4) or LTC(4). Pre-exposure to cPLA(2) or LOX inhibitors reduced 17,20βP-induced ovulation rates, while a COX inhibitor had no effect on ovulation or spawning. Collectively, these findings suggest that eicosanoids, in particular LOX metabolites, mediate 17,20βP-induced ovulation in zebrafish. COX metabolites also appear to be involved in ovulation and spawning but their role remains undefined.

The contribution of the maternal immune system to the establishment of pregnancy in cattle

Immune cells play an integral role in affecting successful reproductive function. Indeed, disturbed or aberrant immune function has been identified as primary mechanisms behind infertility. In contrast to the extensive body of literature that exists for human and mouse, studies detailing the immunological interaction between the embryo and the maternal endometrium are quite few in cattle. Nevertheless, by reviewing the existing studies and extrapolating from sheep, pig, mouse, and human data, we can draw a reasonably comprehensive picture. Key contributions of immune cell populations include granulocyte involvement in follicle differentiation and gamete transfer, monocyte invasion of the peri-ovulatory follicle and their subsequent role in corpus luteum formation and the pivotal roles of maternal macrophage and dendritic cells in key steps of the establishment of pregnancy, particularly, the maternal immune response to the embryo. These contributions are reviewed in detail below and key findings are discussed.

Doppler velocimetry of the ovarian artery as a tool to detect LH surge in stimulated cycles

Our aim was to assess the velocimetric pattern of the ovarian artery as a possible marker of LH surge in stimulated cycles. A total of 130 women undergoing ovarian stimulation for intrauterine insemination were randomized in two groups. Each woman was stimulated with 75 IU of recombinant FSH starting from the third day of the cycle. Velocimetric indices of the dominant ovarian artery were compared between patients with spontaneous LH surge and those needing HCG administration to trigger dominant follicle rupture. The pulsatility index and the ratio between peak systolic flow and lowest diastolic flow were significantly higher in women that had a spontaneous triggering of ovulation. These parameters had a high and very significant positive correlation with the dosage of luteinizing hormone. Threshold values of 2.60 for PI and 7.68 for S/D had a high sensitivity and specificity to predict LH surge. These velocimetric results demonstrated that an increased resistance in the dominant ovarian artery is correlated to LH surge in stimulated cycles. It may represent a sign of relevant clinical utility in timing of intrauterine insemination and/or natural intercourse.

Differential Evolution between Monotocous and Polytocous Species

One of the most important traits for both animal science and livestock production is the number of offspring for a species. This study was performed to identify differentially evolved genes and their distinct functions that influence the number of offspring at birth by comparative analysis of eight monotocous mammals and seven polytocous mammals in a number of scopes: specific amino acid substitution with site-wise adaptive evolution, gene expansion and specific orthologous group. The mutually exclusive amino acid substitution among the 16 mammalian species identified five candidate genes. These genes were both directly and indirectly related to ovulation. Furthermore, in monotocous mammals, the EPH gene family was found to have undergone expansion. Previously, the EPHA4 gene was found to positively affect litter size in pigs and supports the possibility of the EPH gene playing a role in determining the number of offspring per birth. The identified genes in this study offer a basis from which the differences between monotocous and polytocous species can be studied. Furthermore, these genes may harbor some clues to the underlying mechanism, which determines litter size and may prove useful for livestock breeding strategies.

Melatonin and the circadian system: contributions to successful female reproduction

OBJECTIVE

To summarize the role of melatonin and circadian rhythms in determining optimal female reproductive physiology, especially at the peripheral level.

DESIGN

Databases were searched for the related English-language literature published up to March 1, 2014. Only papers in peer-reviewed journals are cited.

SETTING

Not applicable.

PATIENT(S)

Not applicable.

INTERVENTION(S)

Melatonin treatment, alterations of the normal light:dark cycle and light exposure at night.

MAIN OUTCOME MEASURE(S)

Melatonin levels in the blood and in the ovarian follicular fluid and melatonin synthesis, oxidative damage and circadian rhythm disturbances in peripheral reproductive organs.

RESULT(S)

The central circadian regulatory system is located in the suprachiasmatic nucleus (SCN). The output of this master clock is synchronized to 24 hours by the prevailing light-dark cycle. The SCN regulates rhythms in peripheral cells via the autonomic nervous system and it sends a neural message to the pineal gland where it controls the cyclic production of melatonin; after its release, the melatonin rhythm strengthens peripheral oscillators. Melatonin is also produced in the peripheral reproductive organs, including granulosa cells, the cumulus oophorus, and the oocyte. These cells, along with the blood, may contribute melatonin to the follicular fluid, which has melatonin levels higher than those in the blood. Melatonin is a powerful free radical scavenger and protects the oocyte from oxidative stress, especially at the time of ovulation. The cyclic levels of melatonin in the blood pass through the placenta and aid in the organization of the fetal SCN. In the absence of this synchronizing effect, the offspring may exhibit neurobehavioral deficits. Also, melatonin protects the developing fetus from oxidative stress. Melatonin produced in the placenta likewise may preserve the optimal function of this organ.

CONCLUSION(S)

Both stable circadian rhythms and cyclic melatonin availability are critical for optimal ovarian physiology and placental function. Because light exposure after darkness onset at night disrupts the master circadian clock and suppresses elevated nocturnal melatonin levels, light at night should be avoided.

Expression and regulation of stromal cell-derived factor-1 (SDF1) and chemokine CXC motif receptor 4 (CXCR4) in equine and bovine preovulatory follicles

The interaction between stromal cell-derived factor-1 (SDF1) and chemokine CXC motif receptor 4 (CXCR4) has been implicated in leukocyte attraction, tissue remodeling and angiogenesis. The objective of the present study was to characterize the expression and regulation of SDF1 and CXCR4 in equine follicles during the ovulatory process. Equine preovulatory follicles were isolated during estrus 0-39h after hCG treatment. Follicle wall preparations (theca interna with attached granulosa cells) and isolated preparations of granulosa cells and theca interna were obtained, and total RNA extracts were analyzed by RT-PCR/Southern blot. Results showed that levels of CXCR4 transcripts were induced by hCG in follicles at 36 h post-hCG (P<0.05 vs 0 h), with the induction observed in both granulosa and theca cells. Immunoblotting and immunohistochemical analyses confirmed an increase in CXCR4 protein in follicles after hCG treatment. In contrast, levels of SDF1 transcripts were very low in granulosa cells but high in theca interna cells throughout most of the ovulatory period. Studies in vivo performed with bovine preovulatory follicles collected 0-24h post-hCG revealed a marked and significant up-regulation of CXCR4 transcripts after hCG (P<0.05), as observed in equine follicles. A similar pattern of CXCR4 mRNA up-regulation was observed in cultures of bovine granulosa cells treated with forskolin (P<0.05). This forskolin-dependent induction of CXCR4 mRNA was suppressed by co-treatment with inhibitors of PKA, ERK1/2 and EGFR, and by the progesterone receptor antagonist RU486 (P<0.05), underscoring the contribution of multiple signaling pathways. In complementary studies, treatment of bovine granulosa cells with EGF or the hypoxia mimetic cobalt chloride significantly increased CXCR4 transcript levels, whereas co-treatment with forskolin and a CXCR4 antagonist repressed the expression of several ovulation-related genes. Collectively, this study describes for the first time the gonadotropin-dependent up-regulation of CXCR4 transcript in ovarian follicles of large monoovulatory species, provides some insights into the regulation of CXCR4 gene expression in granulosa cells, and identifies a potential link between follicular SDF1/CXCR4 activation and the regulation of ovulation-related genes.

Feed intake alters immune cell functions and ovarian infiltration in broiler hens: implications for reproductive performance

Leukocytes are known to participate in ovarian activities in several species, but there is a surprising lack of information for the common chicken. Broiler hens consuming feed ad libitum (AL) exhibit a number of ovarian irregularities, but leukocyte functions are unstudied. In contrast to feed-restricted (R) hens, AL feeding for 7 wk significantly reduced egg production and clutch length while increasing pause length and atretic follicle numbers (P < 0.05). Granulosa cells from F1 follicles of AL hens contained less progesterone, and follicle walls were thicker with loose fibrous morphology and had less collagenase-3-like gelatinolytic activity but more IL-1beta (P < 0.05) production, suggestive of slower maturation in ovulatory process and inflamed necrosis. Interestingly, while highly infiltrated with immune cells, particularly heterophils, IL-1beta, MMP-22-like, and gelatinase A activities were reduced in AL hen peripheral heterophils and monocytes (P < 0.05); however, AL monocytes showed an increase in phagocytosis rate (P < 0.05). Generation of reactive oxygen intermediates was also suppressed in AL heterophils but increased in AL monocytes (P < 0.05). In contrast to leukocyte-free control, both AL and R heterophils and monocytes suppressed progesterone production and increased cell death in a dose-dependent manner when coincubated with granulosa cells at different ratios (P < 0.05). AL monocytes suppressed progesterone production more, but AL heterophils were less proapoptotic when compared to their R counterparts (P < 0.05). Alterations of cellular ceramide content (P < 0.05) corresponded to the discrepancy between heterophil and monocyte functionality. In conclusion, leukocyte dysfunction contributes to impaired ovarian activities of overfed broiler hens.

Ovarian dendritic cells act as a double-edged pro-ovulatory and anti-inflammatory sword

Ovulation and inflammation share common attributes, including immune cell invasion into the ovary. The present study aims at deciphering the role of dendritic cells (DCs) in ovulation and corpus luteum formation. Using a CD11c-EYFP transgenic mouse model, ovarian transplantation experiments, and fluorescence-activated cell sorting analyses, we demonstrate that CD11c-positive, F4/80-negative cells, representing DCs, are recruited to the ovary under gonadotropin regulation. By conditional ablation of these cells in CD11c-DTR transgenic mice, we revealed that they are essential for expansion of the cumulus-oocyte complex, release of the ovum from the ovarian follicle, formation of a functional corpus luteum, and enhanced lymphangiogenesis. These experiments were complemented by allogeneic DC transplantation after conditional ablation of CD11c-positive cells that rescued ovulation. The pro-ovulatory effects of these cells were mediated by up-regulation of ovulation-essential genes. Interestingly, we detected a remarkable anti-inflammatory capacity of ovarian DCs, which seemingly serves to restrict the ovulatory-associated inflammation. In addition to discovering the role of DCs in ovulation, this study implies the extended capabilities of these cells, beyond their classic immunologic role, which is relevant also to other biological systems.

Urinary cytokine and chemokine profiles across the menstrual cycle in healthy reproductive-aged women

OBJECTIVE

To assess the utility of urinary cytokines for monitoring reproductive function by considering detection, variation across the menstrual cycle, and relations with hormones.

DESIGN

Longitudinal cohort study.

SETTING

Academic institution.

PATIENT(S)

Healthy, reproductive-aged women with self-reported regular menstrual cycles and at least one observed ovulatory cycle (n = 248).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Urinary cytokines measured by 30-plex immunoassays in 3,550 biospecimens, and nested random-effects analysis of variance (ANOVA) and marginal structural models used to evaluate variability and relations with hormones.

RESULT(S)

For 24 of 30 evaluated factors, detectable levels were observed in at least 50% of urine samples. Interleukin-6 (IL-6), IL-8, IL-10, IL-15, granulocyte colony stimulating factor (G-CSF), hepatocyte growth factor (HGF), interferon-α (IFN-α), and RANTES (regulated upon activation normal T-cell expressed and secreted) levels varied significantly across the menstrual cycle. The proinflammatory factors IL-1β, IL-6, IL-8, and HGF were 1.5-3 times higher during menses than the late follicular phase. In marginal structural models, IL-1β, IL-6, IL-8 were associated with lower estradiol and progesterone concentrations.

CONCLUSION(S)

Variability during the menstrual cycle and correlations with reproductive hormone levels support a role of cytokines in the menstrual cycle; however, because of the limited variability for most cytokines considered, the utility of urine as a matrix for assessment of inflammation in menstrual cycle function appears limited for clinical purposes.

Clinical relevance of melatonin in ovarian and placental physiology: a review

Within the last decade, the synthesis of melatonin in and its functions at the level of the peripheral reproductive organs has come into better focus. Melatonin is produced at several reproductive organ sites, e.g., the oocyte, ovarian follicular cells and the placental cytotrophoblasts. Moreover, these cells also contain membrane receptors for this indoleamine. In addition, via the free radical scavenging activity of melatonin and its metabolites, oxidative stress is reduced in all reproductive organ cells ensuring their optimal function. Enhancement of oocyte maturation and preservation of oocyte quality may be major functions of melatonin. Oocyte damage reduces successful fertilization and the development of a healthy fetus. The findings that melatonin protects the oocyte from toxic oxygen species have implications for improving the outcome of in vitro fertilization-embryo transfer procedures, as already shown in two published reports. Some actions of melatonin in the placenta may be context specific. Thus, melatonin is believed to function in the maintenance of optimal placental homeostasis by deferring apoptosis of villous cytotrophoblasts, while protecting syncytiotrophoblasts from oxidative damage. Melatonin reduces oxidative damage in the placenta and may improve hemodynamics and nutrient transfer at the placental-uterine interface. The use of melatonin to treat preeclampsia should also be considered.

The role of bone morphogenetic protein 6 in accumulation and regulation of neutrophils in the human ovary

Bone morphogenetic protein (BMP) cytokine is known to regulate ovulation, as BMP-6 null mice exhibit a decrease in the number of ovulatory follicles without effect on either the morphology or the dynamics of follicular development. In the present study, the role of BMP-6 in ovulatory process was investigated using human granulosa-lutein cells (GCs). Granulosa-lutein cells, obtained from in vitro fertilization patients, were cultured with BMP-6 followed by RNA extraction. The neutrophil-chemotactic activity of the supernatant of cultured GC was investigated. Bone morphogenetic protein 6 significantly increased growth-regulated oncogene α (GRO-α) messenger RNA (mRNA) and protein expression in GC. In the neutrophil-chemotaxis assay, the GC supernatant cultured with BMP-6 attracted more neutrophils than control samples, which was negated with anti-GRO-α neutralizing antibody. Bone morphogenetic protein 6 also suppressed the relative expression of the protease inhibitors, secretory leukocyte peptidase inhibitor, and whey acid protein 14 mRNA in GC. Bone morphogenetic protein 6 might play a role in ovulation by increasing the accumulation of neutrophils in the ovulatory follicle and suppressing the effect of protease inhibitors.

Obesity-induced dysfunctions in female reproduction: lessons from birds and mammals

Follicle wall rupture and ovum release, i.e., ovulation, has been described as a controlled inflammatory event. The process involves tissue remodeling achieved through leukocyte-mediated proteolysis. In birds, ovulation is the first step in the energy-intensive process of egg formation, yet hens that consume energy in excess of productive requirements experience impaired egg-laying ability. Broiler chickens, selected for rapid lean muscle gain, and coincidentally hyperphagia, develop adult obesity when given free access to feed. Obese broiler hens experience elevated circulating concentrations of insulin and leptin, changes in lipid and lipoprotein metabolism similar to those of human metabolic syndrome, as well as increased systemic inflammation. Overall, the manifestations in poultry are similar to those of women with polycystic ovary syndrome. It was shown recently that, in hens, as in mammals, changes in lipid synthesis and metabolism cause granulosa cell apoptosis and altered immune function and hormone production, further compromising ovarian function. To date, there is insufficient information on the means used by the ovary to direct leukocyte function toward successful ovulation. More information is needed regarding the control of proteolytic actions by leukocytes with regards to the roles of specific enzymes in both ovulation and atresia. The broiler hen has provided unique insight into the interrelations of energy intake, obesity, leukocyte function, and reproduction. Additional work with this model can serve the dual purposes of improving avian reproduction and providing novel insights into polycystic ovary syndrome in women.

The rat oocyte synthesises melatonin

Melatonin (N-acetyl-5-methoxytryptamine) is an indoleamine originally identified in the pineal gland, where it is synthesised enzymatically from serotonin (5-hydroxytryptamine) by the sequential action of arylalkylamine N-acetyltransferase (AANAT) and acetylserotonin O-methyltransferase (ASMT; also known as hydroxyindole O-methyltransferase). Melatonin directly affects ovarian functions and previous studies have suggested that melatonin is synthesised in the ovary. In the present study, we examined whether AANAT and ASMT are expressed in the adult rat ovary. Reverse transcription-polymerase chain reaction analyses demonstrated that both AANAT and ASMT mRNAs are expressed in the ovary. Western blotting for AANAT protein showed that the ovary, like the pineal gland, contains this enzymatic protein with a molecular mass of 24kDa. Immunohistochemistry revealed that the AANAT protein is localised to the oocyte, corpus luteum and medulla, including mast cells. AANAT protein was found in oocytes at all stages of follicular development, and its levels in oocytes increased progressively throughout follicular development. Furthermore, isolated oocytes metabolised exogenous serotonin to melatonin. These findings demonstrate that melatonin is synthesised from serotonin in oocytes. Melatonin synthesised in the oocyte may be implicated in its own growth or maturation, for example, by acting as a calmodulin antagonist or an antioxidant.

Expression, regulation, and promoter activation of vanin-2 (VNN2) in bovine follicles prior to ovulation

Vanin-2 (VNN2) is known to be involved in inflammation and leukocyte migration, but its regulation in follicles remains unknown. The objectives of this work were to study the regulation of VNN2 transcripts in bovine follicles prior to ovulation and to characterize the control of its expression in bovine granulosa cells. VNN2 expression was studied using total RNA extracted from granulosa cells of small follicles (2-4 mm in diameter), dominant follicles obtained on Day 5 of the estrous cycle, ovulatory follicles obtained 0-24 h after human chorionic gonadotropin (hCG), and corpora lutea on Day 5 of the cycle. The results from RT-PCR analyses showed that levels of VNN2 mRNA were high in ovulatory follicles 24 h post-hCG but low in the other tissues. In ovulatory follicles, levels of VNN2 mRNA were low at 0 h but significantly up-regulated 12-24 h post-hCG. To determine factors controlling VNN2 gene expression, established primary cultures of granulosa cells isolated from bovine dominant follicles were used. Treatment with forskolin elevated VNN2 mRNA expression as observed in vivo. Mutation studies identified the minimal region conferring basal and forskolin-stimulated VNN2 promoter activities, which were dependent on chicken ovalbumin upstream promoter-transcription factor (COUP-TF), GATA, and Ebox cis-elements. Electrophoretic mobility shift assays identified COUP-TF, GATA4, and upstream stimulating factor proteins as key factors interacting with these elements. Chromatin immunoprecipitation assays confirmed basal and forskolin-induced interactions between these proteins and the VNN2 promoter in bovine granulosa cell cultures. VNN2 promoter activity and mRNA expression were markedly stimulated by forskolin and overexpression of the catalytic subunit of PKA, but inhibited by PKA and ERK1/2 inhibitors. Collectively, the findings from this study describe for the first time the gonadotropin/forskolin-dependent up-regulation of VNN2 transcripts in granulosa cells of preovulatory follicles and provide insights into some of the molecular bases of VNN2 gene expression in follicular cells.

Peripheral reproductive organ health and melatonin: ready for prime time

Melatonin has a wide variety of beneficial actions at the level of the gonads and their adnexa. Some actions are mediated via its classic membrane melatonin receptors while others seem to be receptor-independent. This review summarizes many of the published reports which confirm that melatonin, which is produced in the ovary, aids in advancing follicular maturation and preserving the integrity of the ovum prior to and at the time of ovulation. Likewise, when ova are collected for in vitro fertilization-embryo transfer, treating them with melatonin improves implantation and pregnancy rates. Melatonin synthesis as well as its receptors have also been identified in the placenta. In this organ, melatonin seems to be of particular importance for the maintenance of the optimal turnover of cells in the villous trophoblast via its ability to regulate apoptosis. For male gametes, melatonin has also proven useful in protecting them from oxidative damage and preserving their viability. Incubation of ejaculated animal sperm improves their motility and prolongs their viability. For human sperm as well, melatonin is also a valuable agent for protecting them from free radical damage. In general, the direct actions of melatonin on the gonads and adnexa of mammals indicate it is an important agent for maintaining optimal reproductive physiology.

Melatonin as a free radical scavenger in the ovarian follicle

This review summarizes new findings related to beneficial effects of melatonin (N-acetyl-5-methoxytryptamine) on reproductive physiology. Recently many researchers have begun to study the local role of melatonin as an antioxidant. We focused on intra-follicular role of melatonin in the ovary. Melatonin, secreted by the pineal gland, is taken up into the follicular fluid from the blood. Reactive oxygen species (ROS) are produced within the follicles, during the ovulatory process. Melatonin reduces oxidative stress as an antioxidant, and contribute to oocyte maturation, embryo development and luteinization of granulosa cells. Our clinical study demonstrated that melatonin treatment for infertile women increases intra-follicular melatonin concentrations, reduces intra-follicular oxidative damage, and elevates fertilization and pregnancy rates. Melatonin treatment also improves progesterone production by corpus luteum in infertile women with luteal phase defect. Melatonin treatment could become a new cure for improving oocyte quality and luteal function in infertile women.

Interleukin-8 stimulates progesterone production via the MEK pathway in ovarian theca cells

Interleukin 8 (IL-8) is a chemoattractant associated with ovulation in the mammalian ovary. This chemokine is also involved in the recruitment and activation of neutrophils. Using bovine tissue, we examined the possible role of IL-8 in steroid production by theca cells of the large ovarian follicles. IL-8 promoted progesterone production and stimulated StAR expression in cultured theca cells. The inhibitor of p38 did not disturb the P4 production and StAR expression in IL-8-treated theca cells. On the other hand, the inhibitor of MEK disturbed the P4 production and expression of StAR in theca cells treated with IL-8. These results suggest that IL-8 is associated with progesterone production in bovine theca cells via the MEK pathway.