Characterization of ovarian function in granulocyte-macrophage colony-stimulating factor-deficient mice

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.

Gland Macrophages: Reciprocal Control and Function within Their Niche

The human body contains dozens of endocrine and exocrine glands, which regulate physiological processes by secreting hormones and other factors. Glands can be subdivided into contiguous tissue modules, each consisting of an interdependent network of cells that together perform particular tissue functions. Among those cells are macrophages, a diverse type of immune cells endowed with trophic functions. In this review, we discuss recent findings on how resident macrophages support tissue modules within glands via the creation of mutually beneficial cell-cell circuits. A better comprehension of gland macrophage function and local control within their niche is essential to achieve a refined understanding of gland physiology in homeostasis and disease.

Progesterone inhibits cytokine/TNF-α production by porcine CL macrophages via the genomic progesterone receptor

In pigs, luteolytic sensitivity to PGF-2α (=LS) is delayed until d 13 of the estrous cycle. While the control of LS is unknown, it is temporally associated with macrophage (MAC; which secretes tumor necrosis factor [TNF]-α) infiltration into the corpora lutea (CL), and previous studies have shown that TNF-α induces LS in porcine luteal cells (LCs) in culture. This study was designed to explore the control of LS by CL macrophage (CL MAC)/TNF-α by progesterone (P4), and to examine the hypothesis that P4 acting via the genomic P4 receptor (PGR) inhibits CL MAC TNF-α and thus plays a key role in regulating LS during the pig estrous cycle. In experiment 1, the effects of LCs on CL MAC cytokine/TNF-α mRNA expression in co-culture were examined (MID cycle; ~d 7-12; no LS); results showed that LC was inhibitory to cytokine/TNF-α. In experiment 2, the effects of P4 or R5020 (PGR-agonist) on CL MAC cytokine/TNF-α mRNA expression were examined (MID cycle; ~d 7-12; no LS); results showed that both P4 and R5020 dose-dependently inhibited TNF-α. In experiment 3, CL MACs were isolated from CL at MID (~d 7-12; no LS) and LATE (~d 13-18; + LS) cycle, and TNF-α/PGR mRNA measured. Results indicated that while TNF-α mRNA was 4.2-fold greater in CL MACs from LATE vs MID cycle, PGR mRNA was 4.5-fold greater in CL MACs from MID vs LATE cycle. These data support our hypothesis and suggest that progesterone, acting via PGR, plays a critical physiological role in the control of TNF-α production by CL MACs and LS during the pig estrous cycle.

Gonadotrophin stimulation in IVF alters the immune cell profile in follicular fluid and the cytokine concentrations in follicular fluid and serum

Study question

Are the immune cell profiles and the cytokine concentrations in follicular fluid (FF) and serum at the preovulatory stage different in conventional exogenous gonadotrophin stimulated IVF (c-IVF) compared with natural cycle IVF (NC-IVF)?

Summary answer

The cell counts of CD45+ leucocytes and T cell subpopulations and the cytokine concentrations in FF and serum are different in c-IVF compared to NC-IVF.

What is known already

FF-derived cells are heterogeneous. Immune cells are involved in intra-ovarian processes and cytokines are required for normal follicular development. Gonadotrophins stimulate the regulatory intrafollicular system and influence the local distribution of immune cells and the intrafollicular release of cytokines. Administration of exogenous gonadotrophins may have a significant effect on this local regulatory system, which then in turn could influence oocyte quality.

Study design, size, duration

The study included 105 patients, 69 undergoing c-IVF and 36 undergoing NC-IVF. c-IVF was performed by exogenous ovarian stimulation with hMG and GnRH antagonists.

Participants/materials, setting, methods

FF samples were collected from the first dominant follicle in c-IVF without pooling and from single leading preovulatory follicles in NC-IVF. Three different approaches were used to analyze FF samples: (i) microscopic investigation of CD45+ leucocytes, (ii) fluorescence-activated cell sorting to determine CD19+ B cells and CD3+ T cells including T cell subpopulations (CD4+, CD8+), and (iii) evaluation of tumour necrosis factor-alpha (TNF-α), interferon-gamma (INF-γ), interleukins (IL)-2, -6, -8, -10 and vascular endothelial growth factor (VEGF) levels in matched FF and serum samples using the Bio-Plex® platform.

Main results and the role of chance

FF obtained from c-IVF contained proportionally more CD45+ leucocytes (P = 0.0384), but fewer CD8+ cytotoxic T cells than FF from NC-IVF. CD3+ T lymphocytes were the most common type of lymphocytes, and the number thereof was comparable in the two study groups. In c-IVF, serum VEGF levels were higher (P = 0.007) than in NC-IVF while FF contained marginally decreased concentrations of IL-8 in c-IVF in comparison to NC-IVF. The cytokine concentration gradient between FF and serum in c-IVF was 10-fold for IL-8 and 8-fold for VEGF and thereby markedly lower than in NC-IVF, where the differences were 32-fold and 30-fold, respectively. Strong positive correlations were determined between FF- IL-10 and FF- VEGF in c-IVF (r = 0.85, P < 0.0001) and in NC-IVF (r = 0.81, P < 0.0001).

Large scale data

N/A.

Limitations, reasons for caution

The ovulation of NC-IVF follicles was induced by the exogenous administration of hCG, which means that the environment did not fully correspond to the physiological situation.

Wider implications of the findings

The differences in the immune profile and the cytokine concentrations in c-IVF and NC-IVF follicles support the hypothesis that conventional ovarian stimulation affects indirectly and heterogeneously the intrafollicular milieu, and thereby possibly affects the oocyte quality and the IVF outcome. However, further studies are needed to confirm our findings and to refine stimulation protocols in the context of optimizing the intrafollicular environment during oocyte maturation.

Study funding/competing interest(s)

The study was supported by a research grant from IBSA Institut Biochimique SA and MSD Merck Sharp & Dohme GmbH. The authors are clinically involved in low dose mono-follicular stimulation and IVF-therapies, using gonadotrophins from all gonadotrophins distributors on the Swiss market, including Institut Biochimique SA and MSD Merck Sharp & Dohme GmbH.

Maternal expression of the JMJD2A/KDM4A histone demethylase is critical for pre-implantation development

Regulation of chromatin composition through post-translational modifications of histones contributes to transcriptional regulation and is essential for many cellular processes, including differentiation and development. JMJD2A/KDM4A is a lysine demethylase with specificity towards di- and tri-methylated lysine 9 and lysine 36 of histone H3 (H3K9me2/me3 and H3K36me2/me3). Here, we report that Kdm4a as a maternal factor plays a key role in embryo survival and is vital for female fertility. Kdm4a−/- female mice ovulate normally with comparable fertilization but poor implantation rates, and cannot support healthy transplanted embryos to term. This is due to a role for Kdm4a in uterine function, where its loss causes reduced expression of key genes involved in ion transport, nutrient supply and cytokine signalling, that impact embryo survival. In addition, a significant proportion of Kdm4a deficient oocytes displays a poor intrinsic ability to develop into blastocysts. These embryos cannot compete with healthy embryos for implantation in vivo, highlighting Kdm4a as a maternal effect gene. Thus, our study dissects an important dual role for maternal Kdm4a in determining faithful early embryonic development and the implantation process.

Modulation of embryonic development due to mating with immunised males

The modification of pre- and postnatal development conferred by immunogenic stimulation of mothers provides a population-level adaptation mechanism for non-genetic transfer of maternal experiences to progeny. However little is known about the transmission of paternal immune experiences to offspring. Here, we show that immune priming of males 3–9 days before mating affects the growth and humoral environment of developing embryos of outbred (ICR) and inbred (C57BL and BALB/c) mice. Antigenic stimulation of fathers caused a significant increase in embryonic bodyweight as measured on Day 16 of pregnancy and altered other gestation parameters, such as feto–placental ratio. Pregnant females mated with immunised males were also characterised by changes in humoral conditions as shown by measurements of blood and amniotic progesterone, testosterone and granulocyte–macrophage colony-stimulating factor (GM-CSF) cytokine concentrations. These results emphasise the role of paternal effects of immune priming on the in utero environment and fetal growth.

Seminal Fluid Signalling in the Female Reproductive Tract: Implications for Reproductive Success and Offspring Health

Carriage of sperm is not the only function of seminal fluid in mammals. Studies in mice show that at conception, seminal fluid interacts with the female reproductive tract to induce responses which influence whether or not pregnancy will occur, and to set in train effects that help shape subsequent fetal development. In particular, seminal fluid initiates female immune adaptation processes required to tolerate male transplantation antigens present in seminal fluid and inherited by the conceptus. A tolerogenic immune environment to facilitate pregnancy depends on regulatory T cells (Treg cells), which recognise male antigens and function to suppress inflammation and immune rejection responses. The female response to seminal fluid stimulates the generation of Treg cells that protect the conceptus from inflammatory damage, to support implantation and placental development. Seminal fluid also elicits molecular and cellular changes in the oviduct and endometrium that directly promote embryo development and implantation competence. The plasma fraction of seminal fluid plays a key role in this process with soluble factors, including TGFB, prostaglandin-E, and TLR4 ligands, demonstrated to contribute to the peri-conception immune environment. Recent studies show that conception in the absence of seminal plasma in mice impairs embryo development and alters fetal development to impact the phenotype of offspring, with adverse effects on adult metabolic function particularly in males. This review summarises our current understanding of the molecular responses to seminal fluid and how this contributes to the establishment of pregnancy, generation of an immune-regulatory environment and programming long-term offspring health.

Macrophages regulate corpus luteum development during embryo implantation in mice

Macrophages are prominent in the uterus and ovary at conception. Here we utilize the Cd11b-Dtr mouse model of acute macrophage depletion to define the essential role of macrophages in early pregnancy. Macrophage depletion after conception caused embryo implantation arrest associated with diminished plasma progesterone and poor uterine receptivity. Implantation failure was alleviated by administration of bone marrow-derived CD11b+F4/80+ monocytes/macrophages. In the ovaries of macrophage-depleted mice, corpora lutea were profoundly abnormal, with elevated Ptgs2, Hif1a, and other inflammation and apoptosis genes and with diminished expression of steroidogenesis genes Star, Cyp11a1, and Hsd3b1. Infertility was rescued by exogenous progesterone, which confirmed that uterine refractoriness was fully attributable to the underlying luteal defect. In normally developing corpora lutea, macrophages were intimately juxtaposed with endothelial cells and expressed the proangiogenic marker TIE2. After macrophage depletion, substantial disruption of the luteal microvascular network occurred and was associated with altered ovarian expression of genes that encode vascular endothelial growth factors. These data indicate a critical role for macrophages in supporting the extensive vascular network required for corpus luteum integrity and production of progesterone essential for establishing pregnancy. Our findings raise the prospect that disruption of macrophage-endothelial cell interactions underpinning corpus luteum development contributes to infertility in women in whom luteal insufficiency is implicated.

Pituitary-ovary-spleen axis in ovulation

Leukocytes are rapidly recruited to the preovulatory ovary and play a crucial role as facilitators of ovulation and luteal formation. In this article, recent findings on leukocyte trafficking to the ovary, as well as the physiological role of leukocytes in the ovary, will be summarized and discussed. We then explore the novel hypothesis that the hypothalamus-pituitary-ovary (HPO) axis might include the spleen as a reservoir of leukocytes by summarizing recent reports on this topic, both in the fields of immunology and reproductive biology.

GM-CSF is an essential regulator of T cell activation competence in uterine dendritic cells during early pregnancy in mice

Uterine dendritic cells (DCs) are critical for activating the T cell response mediating maternal immune tolerance of the semiallogeneic fetus. GM-CSF (CSF2), a known regulator of DCs, is synthesized by uterine epithelial cells during induction of tolerance in early pregnancy. To investigate the role of GM-CSF in regulating uterine DCs and macrophages, Csf2-null mutant and wild-type mice were evaluated at estrus, and in the periconceptual and peri-implantation periods. Immunohistochemistry showed no effect of GM-CSF deficiency on numbers of uterine CD11c(+) cells and F4/80(+) macrophages at estrus or on days 0.5 and 3.5 postcoitum, but MHC class II(+) and class A scavenger receptor(+) cells were fewer. Flow cytometry revealed reduced CD80 and CD86 expression by uterine CD11c(+) cells and reduced MHC class II in both CD11c(+) and F4/80(+) cells from GM-CSF-deficient mice. CD80 and CD86 were induced in Csf2(-/-) uterine CD11c(+) cells by culture with GM-CSF. Substantially reduced ability to activate both CD4(+) and CD8(+) T cells in vivo was evident after delivery of OVA Ag by mating with Act-mOVA males or transcervical administration of OVA peptides. This study shows that GM-CSF regulates the efficiency with which uterine DCs and macrophages activate T cells, and it is essential for optimal MHC class II- and class I-mediated indirect presentation of reproductive Ags. Insufficient GM-CSF may impair generation of T cell-mediated immune tolerance at the outset of pregnancy and may contribute to the altered DC profile and dysregulated T cell tolerance evident in infertility, miscarriage, and preeclampsia.

Periovulatory leukocyte infiltration in the rat ovary

Ovulation is preceded by intraovarian inflammatory reactions that occur in response to the preovulatory gonadotropin surge. As a main inflammatory event, leukocytes infiltrate the ovary and release proteolytic enzymes that degrade the extracellular matrix weakening the follicular wall, a required step for follicle rupture. This study aimed to quantitatively measure the infiltrating leukocytes, determine their cell types, and localize infiltration sites in the periovulatory rat ovary. Cycling adult and gonadotropin-stimulated immature rats were used as animal models. Ovaries were collected at five different stages of estrous cycle in the adult rats (diestrus, 1700 h; proestrus, 1500 h; proestrus, 2400 h; estrus, 0600 h; and metestrus, 1700 h) and at five different time points after superovulation induction in the immature rats (pregnant mare's serum gonadotrophin, 0 h; pregnant mare's serum gonadotrophin, 48 h; human chorionic gonadotropin, 6 h; human chorionic gonadotropin, 12 h; and human chorionic gonadotropin, 24 h). The ovaries were either dissociated into a single cell suspension for flow cytometric analysis or fixed for immunohistochemical localization of the leukocytes. Similar numbers of leukocytes were seen throughout the estrous cycle (approximately 500,000/ovary), except proestrus 2400 when 2-fold higher numbers of leukocytes were found (approximately 1.1 million/ovary). A similar trend of periovulatory rise of leukocyte numbers was seen in the superovulation-induced immature rat model, recapitulating a dramatic increase in leukocyte numbers upon gonadotropin stimulation. Both macrophage/granulocytes and lymphocytes were among the infiltrating leukocytes and were localized in the theca and interstitial tissues, where platelet-endothelial cell adhesion molecule-1 and intercellular adhesion molecule-1 may play roles in the transmigration of leukocytes, because their expressions correlates spatiotemporally with the infiltrating leukocytes. In addition, a strong inverse relationship between leukocyte numbers in the ovary and spleen, as well as significant reduction of leukocyte infiltration in the splenectomized rats, were seen, indicating that the spleen may serve as an immediate supplier of leukocytes to the periovulatory ovary.

The interface of the immune and reproductive systems in the ovary: lessons learned from the corpus luteum of domestic animal models

The dynamic changes that characterize the female reproductive system are regulated by hormones. However, local cell-to-cell interactions may mediate responsiveness of tissues to hormonal signals. The corpus luteum (CL) is an excellent model for understanding how immune cells are recruited into tissues and the role played by those cells in regulating tissue homeostasis or demise. Leukocytes are recruited into the CL throughout its lifespan, and leukocyte-derived cytokines have been found in corpora lutea of all species examined. The proinflammatory cytokines inhibit gonadotropin-stimulated steroidogenesis, profoundly stimulate prostaglandin synthesis by luteal cells, and promote apoptosis. However, there is mounting evidence that leukocytes and luteal cells communicate in different ways to maintain homeostasis within the functional CL. Domestic animals have provided important information regarding the presence and role of immune cells in the CL.

Regulation of dendritic cell differentiation and function by estrogen receptor ligands

Estrogen receptor (ER) ligands can modulate innate and adaptive immunity and hematopoiesis, which may explain the clear sex differences in immune responses during autoimmunity, infection or trauma. Dendritic cells (DC) are antigen presenting cells important for initiation of innate and adaptive immunity, as well as immune tolerance. DC progenitors and terminally differentiated DC express ER, indicating the ER ligands may regulate DC at multiple developmental and functional stages. Although there are profound differences in innate immunity between males and females or upon systemic imposition of sex hormones, studies are just beginning to link these differences to DC. Our and others studies demonstrate that estradiol and other ER ligands regulate the homeostasis of bone marrow myeloid and lymphoid progenitors of DC, as well as DC differentiation mediated by GM-CSF and Flt3 Ligand. Since DC have a brief lifespan, these data suggest that relatively short exposures to ER ligands in vivo will alter DC numbers and intrinsic functional capacity related to their developmental state. Studies in diverse experimental models also show that agonist and antagonist ER ligands modulate DC activation and production of inflammatory mediators. These findings have implications for human health and disease since they suggest that both DC development and functional capacity will be responsive to the physiological, pharmacological and environmental ER ligands to which an individual is exposed in vivo.

Cytokine knockouts in reproduction: the use of gene ablation to dissect roles of cytokines in reproductive biology

Cytokines play many diverse and important roles in reproductive biology, and dissecting the complex interactions between these proteins and the different reproductive organs is a difficult task. One approach is to use gene ablation, or 'knockout', to analyse the effect of deletion of a single cytokine on mouse reproductive function. This review summarizes the essential roles of cytokines in reproductive biology that have been revealed by gene knockout studies, including development and regulation of the hypothalamo-pituitary-gondal axis, ovarian folliculogenesis, implantation and immune system modulation during pregnancy. However, successful utilization of this approach must consider the caveats associated with gene ablation studies, e.g. embryonic lethality, systemic effects of cytokine ablation on local reproductive processes and the limited exposure to pathogens in mice housed in laboratory conditions. New sophisticated technology that temporally or spatially regulates gene ablation can overcome some of these limitations. Discoveries on the roles of cytokines in reproductive function uncovered by gene ablation studies can now be applied to improve in vitro fertilization for infertile couples and in the development of contraceptive therapies.

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.

Ovarian follicle development and transgenic mouse models

Ovarian follicle development is a complex process that begins with the establishment of what is thought to be a finite pool of primordial follicles and culminates in either the atretic degradation of the follicle or the release of a mature oocyte for fertilization. This review highlights the many advances made in understanding these events using transgenic mouse models. Specifically, this review describes the ovarian phenotypes of mice with genetic mutations that affect ovarian differentiation, primordial follicle formation, follicular growth, atresia, ovulation and corpus luteum (CL) formation. In addition, this review describes the phenotypes of mice with mutations in a variety of genes, which affect the hormones that regulate folliculogenesis. Because studies using transgenic animals have revealed a variety of reproductive abnormalities that resemble many reproductive disorders in women, it is likely that studies using transgenic mouse models will impact our understanding of ovarian function and fertility in women.

Exogenous granulocyte-macrophage colony-stimulating factor promotes follicular development in the newborn rat in vivo

BACKGROUND

Expression and selective cellular localization of granulocyte-macrophage colony-stimulating factor (GM-CSF) and its receptor in ovarian tissue imply an autocrine/paracrine role in ovarian function. Evidence indicating a functional role for GM-CSF in ovarian follicular cell function has been provided by studies with GM-CSF knockout (GM-/-) mice, which suggest that GM-CSF influences events associated with murine follicular maturation.

METHODS

Immature female rats were treated with GM-CSF, FSH or saline for 5 or 10 days. Ovaries were collected for histologic examination and immunostaining determination of CYP17, a theca cell marker. In addition, ovarian section slides were evaluated by immunofluorescence for CD45, an ovarian leukocyte marker. To investigate the possible mechanism of GM-CSF action on follicular development, theca-interstitial cells (T-I) were separated and cultured. Cells were treated with increasing concentrations of GM-CSF, then evaluated for CYP17 mRNA and protein expression assays.

RESULTS

After 10 days of treatment with GM-CSF, the number of small preantral and large preantral follicles was significantly increased compared with the control group (P < 0.05). Similarly, treatment with FSH increased the number of small preantral and large preantral follicles (P < 0.05). CD45 expression measured by immunofluorescence was not different in the three groups, indicating that the distribution of leukocytes was unchanged. In addition, CYP17 was increased in the T-I cells both in vivo and in vitro after GM-CSF treatment.

CONCLUSION

The present results suggest that GM-CSF may play a significant role in follicular development.

Ovarian Monocyte Progenitor Cells: Phenotypic and Functional Characterization

Leukocytes of the macrophage lineage are abundant in the ovarian tissues and have an important function in both follicular development and regression of postovulatory follicles. In this study, we tested the hypothesis that continuous production of macrophages in the ovarian stroma is maintained by a resident population of progenitors. We established a long-term culture of ovarian follicular stromal cells from BALB/c and green fluorescent protein-transgenic (GFP-TG) C57BL/6 mice. Nonadherent cells were collected and tested for hematopoietic function in vitro and in vivo. Histological and ultrastructural analyses revealed a homogenous population of monocyte-like rounded cells. Nonadherent cells continued to proliferate in culture for several months without senescence. When plated at very low density in methylcellulose, these cells formed colonies consisting of monocyte-like cells. Ovarian monocyte-like cells reacted with CD45, CD11b, CD11c, and Ly6-Gr-1 cell surface markers. A distinct CD45low population within these cells reacted with CD117 (C-kit) surface marker, suggestive of a primitive hematopoietic progenitor. Fifty thousand nonadherent cells failed to provide radioprotection to lethally irradiated mice and thus were not considered to be equivalent to pluripotent hematopoietic stem cells. Ovarian nonadherent stromal cells were positive for alkaline phosphatase but lacked embryonic cell antigens stage-specific embryonic antigen (SSEA-1) and Oct-4. We conclude that in the ovaries, a higher requirement for macrophages is provided by a resident stromal population of progenitors whose progeny is restricted to the production of cells of the monocyte-macrophage lineage.

Molecular cloning and expression analysis of a macrophage-colony stimulating factor receptor-like gene from rainbow trout, Oncorhynchus mykiss

The M-CSF and its receptor (M-CSFR, CSF-1R or c-fms proto-oncogene) system were initially implicated as essential in mammals for normal monocyte development as well as for pregnancy. To allow a comparison with the M-CSF and M-CSFR system of an oviparous animal, we cloned a M-CSFR-like gene from rainbow trout (Oncorhynchus mykiss). The gene was cloned from a cDNA library of head kidney. It contained an open reading frame encoding 967 amino acids with a predicted size of 109 kDa. The putative amino acid sequence of rainbow trout M-CSFR showed 54% amino acid identity to fugu (Takifugu rubripes) M-CSFR, 52% to zebrafish (Danio rerio) M-CSFR and 40% to mouse (Mus musculus) and human (Homo sapiens) M-CSFR. The M-CSFR-like gene was constitutively expressed in head kidney, kidney, intestine, spleen and blood. The gene was detected especially in the ovary of immature female rainbow trout. These results suggest that a M-CSFR-like receptor may be involved in female reproductive tracts even in an oviparous animal like fish.

Seminal plasma regulates corpora lutea macrophage populations during early pregnancy in mice

In mice, exposure of the uterus to seminal plasma at mating initiates an inflammatory response within the endometrium, which is characterized by production of cytokines that recruit and activate leukocytes. We hypothesized that this seminal plasma-induced inflammatory response would extend to the ovary, increasing leukocyte abundance within corpora lutea and potentially enhancing progesterone synthesis. Female mice mated to males with their seminal vesicles surgically removed exhibited fewer macrophages within corpora lutea on the day after mating, compared with females mated to vasectomized or normal, intact males. The mean number of F4/80-positive macrophages and major histocompatibility complex (MHC) class II-positive activated macrophages was approximately 2-fold fewer in the absence of seminal vesicle fluid. The effects of seminal plasma on macrophage abundance subsided by Day 4 and were not accompanied by a change in serum progesterone levels during luteinization (Days 1, 2, or 4 after mating) or luteolysis (Days 6 or 9). In vitro secretion of progesterone from corpora lutea cultured with or without LH also did not differ between treatment groups. There was no effect of seminal plasma deficiency in males on the number of ovulated ova or corpora lutea in females. These results imply that seminal plasma exposure of the female reproductive tract at mating augments the macrophage population of newly formed corpora lutea, although these additional macrophages seem not to play a role in steroidogenesis and may instead be involved in tissue remodeling within corpora lutea.

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.

Interleukin-5 transgene expression and eosinophilia are associated with retarded mammary gland development in mice

Eosinophils are prevalent in the female reproductive tract, where they may contribute to regulation of development and maintenance of epithelial integrity. The present study examined the effects of constitutive interleukin-5 (IL-5) expression and overabundance of eosinophils on the development and function of the mammary gland, uterus, and ovary in mice. Eosinophils were up to 13-fold and 4-fold more abundant in the uterus and mammary gland, respectively, in female IL-5 transgenic (IL-5Tg) mice than in wild-type (Wt) animals. Eosinophils were present in large numbers in regressing corpora lutea in IL-5Tg mice but not in ovaries from Wt mice. Postpubertal mammary gland development was retarded in IL-5Tg mice, with impaired terminal end bud formation and an altered pattern of epithelial cell proliferation across the mammary fat pad coincident with disrupted ductal branching and extension. By 10 wk of age, the ductal tree was complete in both genotypes. Onset of first estrus was also delayed in IL-5Tg mice, but once IL-5Tg mice reached puberty, serum estrogen content across the cycle and estrous cycle duration were normal. The histology of uterine tissue and epithelial cell turnover were unchanged. Capacity to mate and achieve pregnancy was not affected by maternal IL-5 transgene expression, although at Day 18 of gestation, a modest decrease in the fetal:placental weight ratio was observed. Furthermore, parturition and ability to lactate and nurture postnatal pup development were not compromised. These data demonstrate an effect of IL-5 overexpression on ductal morphogenesis during postpubertal mammary gland development that is consistent with a direct regulatory role for eosinophils in these events, but these data also show that eosinophil excess does not have long-term consequences for adult reproductive function.

Pulmonary alveolar proteinosis: progress in the first 44 years

Pulmonary alveolar proteinosis is a rare clinical syndrome that was first described in 1958. Subsequently, over 240 case reports and small series have described at least 410 cases in the literature. Characterized by the alveolar accumulation of surfactant components with minimal interstitial inflammation or fibrosis, pulmonary alveolar proteinosis has a variable clinical course ranging from spontaneous resolution to death with pneumonia or respiratory failure. The most effective proven treatment--whole lung lavage--was described soon after the first recognition of this disease. In the last 8 years, there has been rapid progress toward elucidation of the molecular mechanisms underlying both the congenital and acquired forms of pulmonary alveolar proteinosis, following serendipitous discoveries in gene-targeted mice lacking granulocyte-macrophage colony-stimulating factor (GM-CSF). Impairment of surfactant clearance by alveolar macrophages as a result of inhibition of the action of GM-CSF by blocking autoantibodies may underlie many acquired cases, whereas congenital disease is most commonly attributable to mutations in surfactant protein genes but may also be caused by GM-CSF receptor defects. Therapy with GM-CSF has shown promise in approximately half of those acquired cases treated, but it is unsuccessful in congenital forms of the disease, consistent with the known differences in disease pathogenesis.

Interleukin 2 receptor gamma chain (gamma(c)) knockout mice show less regularity in estrous cycle but achieve normal pregnancy without fetal compromise

PROBLEM

Implication of cytokines in pregnancy suggested but remains to be established. We studied the effect of cytokines on reproductive functions such as ovulation and pregnancy, with mutant mice lacking interleukin 2 receptor gamma (IL-2Rgamma), the so-called common gamma chain (gamma(c)), which is shared among receptors for multiple cytokines such as IL-2, IL-4, IL-7, IL-9 and IL-15.

METHOD OF STUDY

Regularities of estrous cycles were observed by vaginal smear. Ovaries stimulated with postmenopausal serum gonadotropin (PMSG) were examined for the ovarian capacities. The uteri at 13 days of gestation were used for histological analysis of the maternal-fetal interface.

RESULTS

The estrous cycles in gamma(c) knockout (gamma(c) KO) mice were irregular compared with wild-type mice, although, the mutants could become pregnant. No uterine natural killer (uNK) cell was found in the uterus at 13 days of pregnancy, and poor decidual formation and thickness of blood vessel walls were observed. Apparent differences were not seen in the numbers and weight of the fetuses between wild type and mutant animals, and fetuses were not compromised throughout pregnancy.

CONCLUSIONS

The gamma(c) KO mice showed irregular estrous cycle but they could carry out normal pregnancy despite lacking uNK and cytokines actions of IL-2, 4, 7, 9 and 15.

Granulocyte-macrophage colony-stimulating factor promotes glucose transport and blastomere viability in murine preimplantation embryos

Granulocyte-macrophage colony-stimulating factor (GM-CSF) secretion from epithelial cells lining the female reproductive tract is induced during early pregnancy by ovarian steroid hormones and constituents of seminal plasma. In this study we have investigated the influence of GM-CSF on development of preimplantation mouse embryos. Blastocyst-stage embryos were found to specifically bind (125)I-GM-CSF and analysis of GM-CSF mRNA receptor expression by reverse transcriptase-polymerase chain reaction indicated expression of the low-affinity alpha subunit of the GM-CSF receptor, but not the affinity-converting beta subunit (beta(c)), or GM-CSF ligand. GM-CSF receptor mRNA was present in the fertilized oocyte and all subsequent stages of development, and in blastocysts it was expressed in both inner cell mass and trophectoderm cells. In vitro culture of eight-cell embryos in recombinant GM-CSF accelerated development of blastocysts to hatching and implantation stages, with a maximum response at a concentration of 2 ng/ml (77 pM). Blastocysts recovered from GM-CSF-null mutant (GM-/-) mice on Day 4 of natural pregnancy or after superovulation showed retarded development, with the total cell number reduced by 14% and 18%, respectively, compared with GM+/+ embryos. Blastocysts generated in vitro from two-cell GM-/- and GM+/+ embryos were larger when recombinant GM-CSF was added to the culture medium (20% and 24% increases in total cell numbers in GM+/+ and GM-/- blastocysts, respectively). Incubation of blastocysts with recombinant GM-CSF elicited a 50% increase in the uptake of the nonmetabolizable glucose analogue, 3-O-methyl glucose. In conclusion, these data indicate that GM-CSF signaling through the low-affinity GM-CSF receptor in blastocysts is associated with increased glucose uptake and enhanced proliferation and/or viability of blastomeres. Together, the findings implicate a physiological role for maternal tract-derived GM-CSF in targeting the preimplantation embryo, and suggest that defective blastocyst development contributes to compromised pregnancy outcome in GM-CSF-null mutant mice.

The testicular germ-cell protease PC4 is also expressed in macrophage-like cells of the ovary

PC4 is a serine protease primarily expressed in spermatids. We have produced PC4-deficient mice carrying an insertion of the bacterial gene for beta galactosidase under the PC4 gene promoter. Male mice lacking PC4 (-/-) exhibit severely reduced fertility. Surprisingly, the fertility of female mice is also significantly diminished in these mutants (Mbikay et al., 1997. Proc. Natl. Acad. Sci. USA 94, 6842-6846). The aim of this study was to determine the site of PC4 expression in mouse ovaries. Using a histoenzymatic assay for beta-galactosidase, we show that the PC4 promoter can drive strong expression of this enzyme in the theca-interstitium and in degenerating corpora lutea of +/- ovaries. We also demonstrate that PC4 transcripts can be detected by RT-PCR in the ovaries of +/- and +/+ mice, but not in those of -/- mice. The cells expressing PC4 were macrophage-like, since they expressed the macrophage markers CD11b and F4/80, as well as interleukin 1beta and tumor necrosis factor alpha (TNFalpha). Expression of PC4 was also detected in the mouse macrophage RAW264.7 cell line. Interestingly, TNFalpha transcripts were 3-fold more abundant in ovarian macrophage-like cells from -/- mice than in those from +/+ mice, suggesting a constitutive state of activation of the mutant cells. An inverse relationship between PC4 expression and macrophage activation was also observed in RAW264.7 cells. When these cells were activated using bacterial lipopolysaccharide, the level of PC4 transcripts decreased, while that of TNFalpha increased. These observations identify PC4 as an enzyme that could influence ovarian physiology by affecting macrophage functions.