Colony stimulating factor-1 (CSF-1) in pregnancy

The Role of CSF-1 in Normal Physiology of Mammary Gland and Breast Cancer: An Update

Colony stimulating factor (CSF-1) and its receptor (CSF-1R, product of c-fms proto-oncogene) were initially implicated as essential for normal monocyte development as well as for trophoblastic implantation. However, studies have demonstrated that CSF-1 and CSF-1R have additional roles in mammary gland development during pregnancy and lactation. This apparent role for CSF-1/CSF-1R in normal mammary gland development is very intriguing because this receptor/ligand pair has also been found to be important in the biology of breast cancer in which abnormal expression of CSF-1 and its receptor correlates with tumor cell invasiveness and adverse clinical prognosis. Recent findings also implicate tumor-produced CSF-1 in promotion of bone metastasis in breast cancer, and a certain membrane-associated form of CSF-1 appears to induce immunity against tumors. This review aims to summarize recent findings on the role of CSF-1 and its receptor in normal and neoplastic mammary development that may elucidate potential relationships of growth factor–induced biological changes in the breast during pregnancy and tumor progression.

Female tract cytokines and developmental programming in embryos

In the physiological situation, cytokines are pivotal mediators of communication between the maternal tract and the embryo. Compelling evidence shows that cytokines emanating from the oviduct and uterus confer a sophisticated mechanism for 'fine-tuning' of embryo development, influencing a range of cellular events from cell survival and metabolism, through division and differentiation, and potentially exerting long-term impact through epigenetic remodelling. The balance between survival agents, including GM-CSF, CSF1, LIF, HB-EGF and IGFII, against apoptosis-inducing factors such as TNFα, TRAIL and IFNg, influence the course of preimplantation development, causing embryos to develop normally, adapt to varying maternal environments, or in some cases to arrest and undergo demise. Maternal cytokine-mediated pathways help mediate the biological effects of embryo programming, embryo plasticity and adaptation, and maternal tract quality control. Thus maternal cytokines exert influence not only on fertility and pregnancy progression but on the developmental trajectory and health of offspring. Defining a clear understanding of the biology of cytokine networks influencing the embryo is essential to support optimal outcomes in natural and assisted conception.

Cytokines and embryo/endometrial interactions

Experimental animal models have shown that the in vitro embryo culture involved in many treatments for infertility results in a dramatic reduction in embryo viability. Recent advances in methodology such as RT-PCR for localization and quantitation of cytokines and their receptors, are revealing the role that this group of growth factors plays in the basic physiology of embryo development and the process of implantation itself. These studies offer the likelihood of dramatically improving in vitro embryo culture in humans and other species by supplementation of culture medium with growth factors or antagonists to improve embryo viability and hence implantation rates.

Role of cytokines in endometrium and at the fetomaternal interface

Cytokines were first recognized as factors involved in the immune responses. However, emerging evidence suggests that cytokines serve as the unanimous language through which cells in organ systems as diverse as hypothalamus to endometrium communicate. Evidence for the participation of these factors in the normal function of the endometrium and uteroplacental unit and development of the embryo is being recognized. This review will highlight the significant insight gained over the past several years for the role of cytokines in the field of reproductive biology. Major emphasis will be placed on interleukins, tumour necrosis factor-α, transforming growth factors, colony stimulating factors and interferon-gamma.

Expression of mRNA and protein of macrophage colony-stimulating factor and its receptor in human follicular luteinized granulosa cells

OBJECTIVE

To evaluate the concentration of macrophage colony-stimulating factor (M-CSF) in serum and follicular fluid (FF) at the time of oocyte retrieval and to detect expression of M-CSF and its receptor by luteinized granulosa cells (GCs).

DESIGN

Collection of serum and FF at the time of oocyte retrieval.

SETTING

A university IVF- intracytoplasmic sperm injection (ICSI) program.

PATIENT(S)

Serum and FF were obtained from 85 women undergoing oocyte retrieval.

INTERVENTION(S)

Serum and FF were obtained from 85 women. The GCs were pooled from 15 (3 x 5) patients (3-14 oocytes each).

MAIN OUTCOME MEASURE(S)

The M-CSF concentration was determined by ELISA, the expression of M-CSF and its receptor by the immunocytochemical technique and reverse transcription polymerase chain reaction analysis. In addition, M-CSF expression was investigated by cell culture time course studies.

RESULTS

The median M-CSF concentration in FF (2,409.2 pg/mL) was significantly higher than that in serum (242.5 pg/mL). The M-CSF and its receptor were expressed by GCs.

CONCLUSION(S)

The significantly higher level of M-CSF in FF than in serum and the expression of M-CSF and its receptor in FF by GCs suggest an important role for this growth factor in ovarian function.

Increased levels of macrophage colony-stimulating factor in the placenta and blood in preeclampsia

PROBLEM

Macrophage colony-stimulating factor (M-CSF) is considered an essential cytokine for placental growth and maintenance. We evaluated whether M-CSF levels in the placenta and blood in preeclampsia differed from those in normal pregnancies.

METHOD OF STUDY

The subjects were 37 pregnant women carrying single fetuses, of whom 19 were women with normal pregnancies and 18 were women with preeclampsia. Their average gestational age at entry was 38 weeks of gestation. Blood was collected before the onset of labor, and separated serum was obtained after centrifugation. A tissue segment of the placenta was cut immediately after delivery. The frozen placental tissue was placed in a plastic tube containing phosphate-buffered saline. The tissue was fully homogenized and then centrifuged. Separated supernatant was used for subsequent determination. M-CSF levels in separated serum were measured, and M-CSF and total protein (TP) levels in separated supernatant were also measured.

RESULTS

Both M-CSF/TP levels in the placenta and M-CSF levels in blood were significantly higher (P < 0.05-0.01) in preeclampsia than in normal pregnancies.

CONCLUSIONS

This is the first report concerning high placenta levels of M-CSF/ TP in preeclampsia. Increased M-CSF in the placenta supports the hypothesis that immunological abnormalities contribute to the etiology of preeclampsia.

Colony-stimulating factor-1 and its receptor do not have a role in the pathogenesis of uterine sarcomas

OBJECTIVE

Several studies have demonstrated overexpression of the mononuclear phagocytic growth factor colony-stimulating factor-1 (CSF-1) and its receptor (CSF-1R) in breast, ovarian, and endometrial adenocarcinomas, and their expression in each of these cancers is strongly correlated with poor prognosis. In addition to adenocarcinomas, sarcomas that are highly malignant arise at much lower frequency in the uterus. Given the common organ of origin and hormonal environment of the adenocarcinomas, we evaluated the potential role of CSF-1 and CSF-1R in the genesis of these tumors using immunohistochemical methods.

RESULTS

Immunohistochemical analysis was performed on 19 archival uterine sarcoma samples. Affinity-purified rabbit anti-CSF-1 antiserum (R52) and human cross-reactive murine anti-c-fms antibody were used. In the 19 cases evaluated for CSF-1 immunoreactivity, 42.1% had staining in less than 25% of the tumor, 36.9% had staining in 25-50% of the tumor, and only 21% had staining in greater than 50% of the tumor. When present, the majority of the CSF-1 immunostaining was associated with the extracellular matrix. There was variable intensity in CSF-1 expression: 52.6% had negative to mild staining, and 47.4% had moderate to strong staining. Immunostaining for the CSF-1R revealed that 52.6% of tumors had expression in less than 25% of cells, 21.0% had expression in 25-50% of the tumor, and 26.4% had staining in greater than 50% of the tumor. There was variable intensity of CSF-1R staining. Slight staining was found in 31.6% of the cases, moderate staining was found in 47.4% of the tumors, and 21.0% of the cases had strong expression. There was no statistically significant correlation between CSF-1 and CSF-1R expression and stage, estrogen/progesterone receptor status, number of mitoses per 10 high-power fields, or disease outcome. In addition, overall expression and intensity of CSF-1 and CSF-1R did not predict tumor virulence or disease outcome.

CONCLUSION

In contradistinction to endometrial adenocarcinomas, in which CSF-1/CSF-1R is strongly correlated with tumor progression, CSF-1 and CSF-1R overexpression does not appear to play a role in the growth and differentiation of uterine sarcomas.

Blood macrophage colony-stimulating factor and thrombin-antithrombin III complex concentrations in pregnancy and preeclampsia

Macrophage colony-stimulating factor (M-CSF) is a characteristic cytokine that plays an essential role in placenta maintenance, and thrombin-antithrombin III complex (TAT) is a hemostatic marker that is remarkably altered both in normal pregnancy and in preeclampsia. The present study was designed in order to show various levels of M-CSF and TAT in pregnancies. Peripheral blood was collected from 49 subjects, of whom 31 were normal pregnant women consisting of the four groups (namely 10th, 20th, 30th, and 38th weeks of gestation), 13 were preeclamptic pregnant women (37th week of gestation; mean blood pressure, 158/99 mm Hg), and 5 were nonpregnant controls. We compared blood M-CSF and TAT levels among them. Results showed that blood M-CSF and TAT levels increased significantly with gestational age. Furthermore, the ratio of increase in M-CSF was significantly lower than that in TAT in normal pregnant women compared with controls. In contrast, the ratio of increase in M-CSF was significantly higher than that in TAT in preeclamptic women compared with normal pregnant women. These results concerning the ratio of increase in M-CSF and TAT have not been reported. These findings show that M-CSF level increases significantly in preeclampsia even in its earlier stage, exhibiting a systolic blood pressure of less than 160 mm Hg.

Colony stimulating factor-1 in human follicular fluid

OBJECTIVE

To evaluate colony stimulating factor-1 (CSF-1) concentrations in serum and follicular fluid (FF) at the time of oocyte retrieval and to test for presence of messenger RNA (mRNA) for CSF-1 and its receptor, c-fms, in FF cells.

DESIGN

Collection of serum and FF at the time of oocyte retrieval.

SETTING

A university IVF program.

PATIENT(S)

Forty-five women undergoing oocyte retrieval for IVF.

INTERVENTION(S)

Serum and FF were obtained from 24 women, and FF only was obtained from 21 women.

MAIN OUTCOME MEASURE(S)

Colony-stimulating factor-1 concentrations were determined by RIA, and the presence of mRNA for CSF-1 and c-fms was determined by reverse transcriptase-polymerase chain reaction.

RESULT(S)

Mean FF concentrations of CSF-1 were significantly higher than mean serum levels (10.0 +/- 1.3 and 3.6 +/- 0.3 (+/-SE) ng/mL, respectively). Colony-stimulating factor-1 and c-fms message were detected in FF cells, and alternatively spliced forms of CSF-1 message were present.

CONCLUSION(S)

The presence of CSF-1, a primary regulator of tissue macrophages, in FF, and the presence of mRNA for CSF-1 and its receptor c-fms in FF-derived cells, suggest a role for this growth factor in ovarian function.

Expression of c-kit and kit ligand at the human maternofetal interface

Kit ligand, or stem cell factor, is a recently identified growth factor, which binds to and activates the c-kit proto-oncogene, and which has been shown to act synergistically with other haematopoietic growth factors in the bone marrow. We have previously shown that several isoforms of kit ligand, which arise due to alternative splicing, are expressed in human placenta. In order to elucidate the role of c-kit and its ligand during human placental development we have investigated the expression of c-kit and kit ligand in human first trimester and term placenta as well as in pregnant and non-pregnant endometrium, by immunocytochemistry and flow cytometric analysis. In non-pregnant endometrium no expression of kit ligand was seen. By contrast, in first trimester decidua, kit ligand was strongly expressed by the arterial media of maternal blood vessels. Kit ligand was also expressed throughout pregnancy by invasive fetal extravillous trophoblast, and by fetal fibroblasts within the placental villi. c-kit was found to be expressed on Hofbauer cells within the chorionic villi, and by decidual macrophages at all stages in pregnancy. c-kit was also detected on the small CD56dim subset of uterine large granular lymphocytes which form the major leukocyte population in human first trimester decidua. Our results suggest that kit ligand may be involved in the regulation of fetal macrophages, and in particular in signalling between invading extravillous trophoblast which expresses kit ligand, and maternal leukocytes bearing the c-kit receptor.

Constitutive expression of TNF-alpha and -beta genes in mouse embryo: roles of cytokines as regulator and effector on development

1. Using the RT/PCR method, we examined mRNA expression of several inflammatory factors in mouse embryos during mid-late embryonal development. mRNAs of tumor necrosis factor (TNF)-alpha, TNF-beta, their receptors (TNF-RI, TNF-RII), transforming growth factor (TGF)-beta, were expressed constitutively in most of the embryonic tissues. 2. While mRNAs of other factors, interleukin (IL)-1 alpha, IL-1 beta, IL-3, IL-6, granurocyte-colony stimulating factor (G-CSF), leukaemia inhibitory factor (LIF), and interferon (IFN)-gamma were only limitedly expressed. 3. The mRNAs of several complement components (C2, C3, C4, C5) and receptors (CR1, CR2) were also detected. Among them, the expression of C3 and CR1 were prominent. These results strongly support our idea that inflammation-like system play an important role to regulate embryogenesis.

The trophoblast as an integral component of a macrophage-cytokine network

The trophoblast, an epithelial cell of fetal origin that forms the physical barrier between the mother and developing conceptus, becomes a component of the host immune system during pregnancy. Of the classical immune cells, it most closely resembles the macrophage, also present in high numbers in the pregnant uterus. The macrophage and trophoblast, as cell classes, share characteristics such as phagocytosis, syncytialization, invasiveness, expression of the proteins CD4, CD14, IgG receptor (FcR), non-specific esterase, granulocyte macrophage-CSF (GM-CSF), colony stimulating factor 1 (CSF-1), interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor (TNF-alpha), transforming growth factors (TGF), platelet-alpha derived growth factor (PDGF) and receptors for these cytokines. In the uterus both cell types appear regulated by a common element, the uterine epithelium, that secretes cytokines such as CSF-1, GM-CSF, TNF alpha, TGF beta, IL-6, and leukaemia inhibitory factor (LIF) that target both macrophages and trophoblasts. The common characteristics and regulation that make teleological sense in terms of co-ordinating local uterine immunity during pregnancy may also be important in transmission of congenital diseases such as AIDS. The production by the uterine epithelium of a number of cytokines previously only associated with mononuclear phagocyte production and function predicts the existence of a similar, but broader, shared cytokine network encompassing trophoblast and the principal immune regulatory cell, the T lymphocyte.

Cytokines in rodent reproduction and the cytokine-endocrine interaction

Insights derived from recent studies employing rodent models demonstrate that the synthesis of pluripotent cytokines is an important function of resident cells in the female reproductive tract. Through steroid hormone regulated secretion of these mediators, resident cells appear to coordinate the recruitment and action of leukocytes that are centrally implicated in the dramatic remodelling processes characteristic of reproductive events.