Accumulation of colony-stimulating factor 1 in amniotic fluid during human pregnancy

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

Uterine growth factors appear to play a role in the regulation of pregnancy. One of these, colony stimulating factor-1 (CSF-1), synthesized by the uterine epithelium under the control of female sex steroids, has been shown to have important functions both before implantation and during the formation of the placenta. In the female reproductive tract the CSF-1 receptor, the product of the c-fms proto-oncogene, is expressed in decidual cells, trophoblasts and macrophages, indicating that these cells are the primary targets for CSF-1. This article reviews the biology of CSF-1 during gestation as well as the possible involvement of CSF-1 and its receptor in the aetiology of gynaecological tumours.

Endocrinology of labour

Preterm labour, defined as delivery before 37 weeks of completed pregnancy, continues to present a major problem in clinical obstetrics and remains the major contributory factor to the perinatal mortality and morbidity statistics. While it is now possible, with recent advances in neonatal care, to take infants delivered very prematurely and provide them with the lifelines that will ensure their ultimate discharge from the neonatal intensive care nursery, the cost of this form of management – in terms both of health care funds and of emotion – is extraordinarily high. Hence there remains a strong rationale for attempting to understand the underlying biochemistry and physiology of labour in order to develop methods of recognizing the patient in true preterm labour, and of developing better strategies to prevent or to manage this condition. In the best of our neonatal intensive care settings, survival of the infant born at 28–30 weeks’ gestation, or greater than 1500 grams, may be greater than 90%. Thus, the clinical management strategy may be directed more towards sustaining intrauterine life for 4–6 weeks in those patients presenting in preterm labour before this time in order to gain time for intrauterine maturation of these fetuses before they are delivered to the tertiary care NICU setting.

Effects of colony-stimulating factors on the secretion of platelet-activating factor acetylhydrolase by human decidual macrophages

OBJECTIVE

The aim is to clarify the role of platelet-activating factor and colony-stimulating factors in term and preterm parturition.

STUDY DESIGN

Decidual macrophage populations were obtained by an enzymic digestion, Ficoll-Paque centrifugation, or flow cytometric sorting. The effects of colony-stimulating factors on the platelet-activating factor acetylhydrolase secretion by these cells were examined.

RESULTS

Granulocyte-macrophage colony-stimulating factor inhibited the platelet-activating factor acetylhydrolase secretion by decidual macrophages. Granulocyte colony-stimulating factor also decreased the enzyme secretion but at higher concentrations than those required for granulocyte colony-stimulating factor. In contrast, macrophage colony-stimulating factor increased the enzyme secretion. These colony-stimulating factor-induced effects were specifically neutralized by the corresponding antibodies.

CONCLUSION

Colony-stimulating factors may modulate the local concentration of platelet-activating factor in the decidua via their inhibitory or stimulatory effect on the secretion of platelet-activating factor acetylhydrolase, contributing to the regulation of term and preterm parturition at the maternal-fetal interface.

Cytokines of the placenta and extra-placental membranes: biosynthesis, secretion and roles in establishment of pregnancy in women

Virtually all known cytokines have been demonstrated to be expressed in the placenta and associated fetal and maternal membranes during normal gestation. In addition to playing their traditional roles as modulators of immunological function, cytokines derived from the placenta and extraplacental membranes, together with other locally-derived growth factors, appear to be implicated in various aspects of implantation and placental development. Imbalances in the intrauterine cytokine milieu around the time of implantation and invasion may play a causative role in disorders associated with early pregnancy failure, and are also associated with the abnormal trophoblast development seen in gestational trophoblastic disease. Cytokines thus appear to be an important component of a paracrine/autocrine communication network operating within the feto-maternal interface to ensure the successful establishment of pregnancy.

The relationship between amniotic fluid macrophage colony-stimulating factor and fetal growth

The aim of this study was to clarify whether amniotic fluid macrophage colony-stimulating factor (M-CSF) is related to placental development and fetal growth. Maternal serum and amniotic fluid M-CSF levels were analyzed in 22 pregnant women (seven intrauterine growth retardation (IUGR) complicated and 15 normal pregnancies) at 33-40 weeks' gestation. Amniotic fluid was obtained by transabdominal amniocentesis performed under ultrasonographic guidance. The mean amniotic fluid M-CSF level of the IUGR-complicated pregnancy group (5.0 +/- 1.4 ng/ml) was significantly lower (P < 0.05) than that of the normal pregnancy group (7.4 +/- 1.6 ng/ml). All the IUGR-complicated pregnant women subsequently delivered small-for-gestational-age (SGA) infants with significantly lower placental weights than those of the normal infants. There was no significant correlation between amniotic fluid M-CSF levels and gestational age in the normal pregnancy group. The same scattergram showed the amniotic fluid M-CSF levels of the IUGR-complicated pregnancy group tended to be lower than those of the normal pregnancy group at 33-40 weeks' gestation. The results suggested that amniotic fluid M-CSF was one of the regulators of human placental development and was related to fetal growth.

IL-6 and G-CSF levels in amniotic fluid during the second trimester in normal and abnormal pregnancies

Activity levels of cytokines were measured by stimulation of the cell lines NFS-60, 7TD1, and TF-1. In 39 samples of amniotic fluid, levels of Granulocyte-Stimulating Factor (G-CSF) were 1434 +/- 2063 (mean +/- SD) and of Interleukin (IL-6) 546 +/- 1071 pg/ml; Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) was not detectable. IL-6 was correlated to G-CSF (r = 0.3; p = 0.003). G-CSF (p = 0.0002) and IL-6 (p = 0.006) were influenced by Alpha-Fetoprotein (AFP) and G-CSF by rhesus-incompatibility (p = 0.0004). These findings suggest that cytokines such as IL-6 and G-CSF play some role in physiological and pathological pregnancy.

Changes in maternal plasma macrophage-colony stimulating factor levels during normal pregnancy

An enzyme-like immunosorbent assay and a blood autoanalyser were used to determine macrophage-colony stimulating factor (M-CSF) levels and the absolute number and percentage of circulating monocytes in 80 normal women with singleton pregnancies at 12-40 weeks' gestation, and ten healthy non-pregnant volunteers. The mean values of M-CSF and absolute number and percentage of circulating monocytes of the control group were 367 U/ml (SD 43) and 389 x 10(6)/l (SD 180) and 5.3% (SD 1.7) respectively. In pregnancy, M-CSF was significantly higher than non-pregnant controls only after 28 weeks' gestation. The absolute number and the percentage of circulating monocytes increased significantly with gestation after 16 weeks. There was no significant association between the concentration of M-CSF and the number or percentage of circulating monocytes. These data suggest that during pregnancy there is an up-regulation of M-CSF and monocytes.

Human trophoblast invasion. Autocrine control and paracrine modulation

Development of the human placenta involves rapid invasion of the uterine wall by fetal trophoblasts, a process with certain similarities to tumor cell invasion. Unlike tumor invasion, however, this unique interaction between genetically dissimilar trophoblast and uterine cells is closely regulated and limited both temporally and spatially by mechanisms that are largely unknown. We have used a combination of two experimental approaches to study this process: immunolocalization using tissue sections to investigate trophoblast invasion in vivo, and a cell culture model that allows manipulation of the invasion process in vitro. The results show that invading trophoblasts express activated forms of metalloproteinases, adhesion molecules and the novel class I histocompatibility antigen, HLA-G, in a highly regulated manner during invasion. The behavior of cytotrophoblasts in vitro, removed from the influences of uterine cells, closely parallels their behavior in vivo, suggesting the existence of autocrine control mechanisms. However, studies examining the effect of growth factors and cytokines on trophoblast invasion suggest that molecules of uterine origin can modify this process. Thus, we hypothesize that the intrinsic invasiveness of these cells is controlled, at least in part, by the specialized environment of the uterus. Future studies will concentrate on identifying these factors and the specific trophoblast functions they modify.

Immunologically mediated abortion (IMA)

Roughly 20% of all clinical pregnancies evolve into "spontaneous abortions". The causes of spontaneous abortion have been determined in under 60% of the total and comprise genetic, infectious, hormonal and immunological factors. In some cases the immune tolerance mechanism may be impaired and the foetus immunologically rejected (IMA, immunologically mediated abortion). The immunological mechanism implicated depends on the time in which pregnancy loss takes place. During preimplantation and up to the end of implantation (13th day) the cell-mediated immune mechanism (potential alloimmune etiologies) is responsible for early abortion. This mechanism involves immunocompetent decidual cells (eGL, endometrial granulated lymphocytes) already present during pre-decidualization (late luteal phase) and their production of soluble factors or cytokines. Once the implantation process is over, after blastocyst penetration of the stroma and the decidual reaction of uterine tissue, IMA could be caused by cell-mediated and humoral mechanism (anti-paternal cytotoxic antibodies or autoantibody etiology), by the production of paternal anti major histocompatibility complex antibodies, or even by an autoimmune disorder leading to the production of autoantibodies (antiphospholipid antibodies, antinuclear antibodies or polyclonal B cell activation). The diagnostic work-up adopted to select IMA patients is crucial and includes primary (karyotype of both partners, toxo-test, hysterosalpingography, endometrial biopsy, thyroid function tests, serum hprolactin, luteal phase dating) and secondary (full hemochromocytometric test, search for LE cells, lupus anticoagulant, anticardiolipin, antinuclear antibodies, Rheumatoid factor, blood complement VDRL) investigations. Therapeutical approaches vary. If autoimmune disorders are demonstrated therapies with different combinations of corticosteroids, aspirin and heparin or intravenous immunoglobulin are administered. Otherwise, therapy with paternal or donor peripheral blood mononuclear cells should be instituted.

Origin of macrophage colony-stimulating factor (M-CSF) and granulocyte colony-stimulating factor (G-CSF) in amniotic fluid

A large amount of M-CSF and G-CSF exists in human amniotic fluid and both are considered to have some physiological affect on maintaining pregnancy. We therefore examined the source of M-CSF and G-CSF found in the amniotic fluid. The average level of M-CSF in the amniotic fluid of patients without complications was 17.3 +/- 8.5 ng/ml and that of G-CSF 1.85 +/- 1.72 ng/ml, both being high values. In neonatal urine, the average level of M-CSF was also very high, 144.3 +/- 97.0 ng/ml, but that of G-CSF was below the determination limit of 60 pg/ml. Immunohistochemical staining indicated that production of M-CSF and G-CSF was localized in the epithelial cells of fetal membrane. On the basis of the above observations, M-CSF was found to derive from neonatal urine and the epithelial cells of fetal membrane, and G-CSF from the epithelial cells of fetal membrane.

Gene expression of macrophage colony-stimulating factor and its receptor in human placenta and decidua

Macrophage colony-stimulating factor (M-CSF) induces proliferation of monocyte/macrophage progenitor cells and can also activate some functions of mature cells including fetally derived placental cells. To study the role of M-CSF in the pregnant female reproductive tract, the expression of M-CSF mRNA and its receptor, c-fms proto-oncogene, in human placenta and decidua was identified. M-CSF and c-fms mRNAs, 4.7Kb and 3.9Kb respectively, were detected by Northern blotting in the early stage placenta and subsequently increased during pregnancy. These mRNAs were not detected in the nonpregnant endometrium but were strongly induced in maternal decidua with the same mRNA size as in the placenta. Northern blot hybridization on the endometrium of a pseudopregnant uterus revealed that the expression of endometrial M-CSF and c-fms mRNAs is regulated by synergistic action of female sex steroid hormones. These findings indicate that, in an autocrine and/or paracrine manner, M-CSF is deeply involved in the local proliferation and differentiation of cells at the materno-fetal interface, and support the placental immunotrophism hypothesis.