Amniotic fluid epidermal growth factor levels in normal and abnormal pregnancies

The Significance of Epidermal Growth Factor in Noninvasively Obtained Amniotic Fluid Predicting Respiratory Outcomes of Preterm Neonates

Preterm premature rupture of membranes (PPROM) interrupts normal lung development, resulting in neonatal respiratory morbidity. Although post-PPROM risks have been researched, only a few studies have investigated noninvasively obtained amniotic fluid (AF) to predict neonatal outcomes. In this study, we aimed to determine whether epidermal growth factor (EGF) in vaginally-collected AF is a significant predictor of neonatal respiratory outcomes after PPROM. We analyzed EGF in vaginally-obtained AF from 145 women with PPROM at 22−34 weeks of gestation. The following neonatal outcomes were included: respiratory distress syndrome, surfactant need, duration and type of respiratory support, and bronchopulmonary dysplasia. We found that EGF concentration was associated with gestational age, and its medians were lower in neonates with respiratory morbidities than unaffected ones. EGF concentrations gradually declined, the lowest being in the most clinically ill patients. EGF < 35 pg/mL significantly predicted the odds of severe respiratory outcomes. EGF in noninvasively collected AF may be a reliable predictor for respiratory outcomes of preterm neonates with PPROM before 34 weeks of gestation. The results of our study may have implications for further research both in noninvasive amniotic fluid analysis and the management of patients after PPROM.

Human Milk Growth Factors and Their Role in NEC Prevention: A Narrative Review

Growing evidence demonstrates human milk's protective effect against necrotizing enterocolitis (NEC). Human milk derives these properties from biologically active compounds that influence intestinal growth, barrier function, microvascular development, and immunological maturation. Among these protective compounds are growth factors that are secreted into milk with relatively high concentrations during the early postnatal period, when newborns are most susceptible to NEC. This paper reviews the current knowledge on human milk growth factors and their mechanisms of action relevant to NEC prevention. It will also discuss the stability of these growth factors with human milk pasteurization and their potential for use as supplements to infant formulas with the goal of preventing NEC.

Biomarkers for Macrosomia Prediction in Pregnancies Affected by Diabetes

Large birthweight, or macrosomia, is one of the commonest complications for pregnancies affected by diabetes. As macrosomia is associated with an increased risk of a number of adverse outcomes for both the mother and offspring, accurate antenatal prediction of fetal macrosomia could be beneficial in guiding appropriate models of care and interventions that may avoid or reduce these associated risks. However, current prediction strategies which include physical examination and ultrasound assessment, are imprecise. Biomarkers are proving useful in various specialties and may offer a new avenue for improved prediction of macrosomia. Prime biomarker candidates in pregnancies with diabetes include maternal glycaemic markers (glucose, 1,5-anhydroglucitol, glycosylated hemoglobin) and hormones proposed implicated in placental nutrient transfer (adiponectin and insulin-like growth factor-1). There is some support for an association of these biomarkers with birthweight and/or macrosomia, although current evidence in this emerging field is still limited. Thus, although biomarkers hold promise, further investigation is needed to elucidate the potential clinical utility of biomarkers for macrosomia prediction for pregnancies affected by diabetes.

Amniotic fluid: Source of trophic factors for the developing intestine

The gastrointestinal tract (GIT) is a complex system, which changes in response to requirements of the body. GIT represents a barrier to the external environment. To achieve this, epithelial cells must renew rapidly. This renewal of epithelial cells starts in the fetal life under the influence of many GIT peptides by swallowing amniotic fluid (AF). Development and maturation of GIT is a very complex cascade that begins long before birth and continues during infancy and childhood by breast-feeding. Many factors like genetic preprogramming, local and systemic endocrine secretions and many trophic factors (TF) from swallowed AF contribute and modulate the development and growth of the GIT. GIT morphogenesis, differentiation and functional development depend on the activity of various TF in the AF. This manuscript will review the role of AF borne TF in the development of GIT.

Mechanical stretch increases brain natriuretic peptide production and secretion in the human fetal membranes

Brain natriuretic peptide (BNP) is synthesized by human fetal membranes, both the amnion and chorion. This locally produced BNP inhibits the contraction of the human myometrium, contributing to the maintenance of myometrial quiescence during pregnancy. We tested the hypothesis that BNP production is increased by fetal membrane stretching, which is predicted to occur in the expanding uterus, and inhibited by epidermal growth factor (EGF), whose production in the fetal membranes increases in late pregnancy. Term fetal membranes were obtained during elective cesarean delivery before labor. Sections of membranes were placed in an isolated chamber containing DMEM: F12 medium (37°C) and stretched with a 35 g weight. Medium and tissue samples were collected at 0, 3, 6, 18, and 24 hours for measurement of messenger RNA (mRNA) and BNP levels in the presence/absence of EGF (2 × 10(-9 )mol/L). Inducible nitric oxide synthase (iNOS) and β-actin were also evaluated to discard a nonspecific effect of mechanical stretch on protein expression. We found that amnion and chorion stretching increased the BNP mRNA (reverse transcription-polymerase chain reaction [RT-PCR]) and protein (radioimmunosorbent assay [RIA]) levels from 18 hours onward. The effect of stretching was inhibited by EGF (2 × 10(-9) mol/L). Stretch did not increase iNOS or β-actin protein levels. We concluded that chorion and amnion stretching may increase BNP expression in the fetal membranes during pregnancy, while increasing biological activity of EGF may decrease BNP production in the chorion and amnion late in pregnancy. We postulate BNP is an important regulator of myometrial contractility during pregnancy, and its production is modulated by both stretch and progressive increase in EGF levels during pregnancy.

Pallidal hyperdopaminergic innervation underlying D2 receptor-dependent behavioral deficits in the schizophrenia animal model established by EGF

Epidermal growth factor (EGF) is one of the ErbB receptor ligands implicated in schizophrenia neuropathology as well as in dopaminergic development. Based on the immune inflammatory hypothesis for schizophrenia, neonatal rats are exposed to this cytokine and later develop neurobehavioral abnormality such as prepulse inhibition (PPI) deficit. Here we found that the EGF-treated rats exhibited persistent increases in tyrosine hydroxylase levels and dopamine content in the globus pallidus. Furthermore, pallidal dopamine release was elevated in EGF-treated rats, but normalized by subchronic treatment with risperidone concomitant with amelioration of their PPI deficits. To evaluate pathophysiologic roles of the dopamine abnormality, we administered reserpine bilaterally to the globus pallidus to reduce the local dopamine pool. Reserpine infusion ameliorated PPI deficits of EGF-treated rats without apparent aversive effects on locomotor activity in these rats. We also administered dopamine D1-like and D2-like receptor antagonists (SCH23390 and raclopride) and a D2-like receptor agonist (quinpirole) to the globus pallidus and measured PPI and bar-hang latencies. Raclopride (0.5 and 2.0 µg/site) significantly elevated PPI levels of EGF-treated rats, but SCH23390 (0.5 and 2.0 µg/site) had no effect. The higher dose of raclopride induced catalepsy-like changes in control animals but not in EGF-treated rats. Conversely, local quinpirole administration to EGF-untreated control rats induced PPI deficits and anti-cataleptic behaviors, confirming the pathophysiologic role of the pallidal hyperdopaminergic state. These findings suggest that the pallidal dopaminergic innervation is vulnerable to circulating EGF at perinatal and/or neonatal stages and has strong impact on the D2-like receptor-dependent behavioral deficits relevant to schizophrenia.

Common behavioral influences of the ErbB1 ligands transforming growth factor alpha and epiregulin administered to mouse neonates

Ligands for epidermal growth factor (EGF) receptor (ErbB1), such as EGF, transforming growth factor alpha (TGFalpha), and epiregulin, are enriched in body fluids and blood and regulate development of various peripheral organs. It remains however how such circulating polypeptide growth factors influence brain development and function. Here, we performed peripheral injections of TGFalpha and epiregulin to mouse neonates and evaluated immediate physical and neurochemical development and later behavioral consequences. Subcutaneous administration of TGFalpha and epiregulin increased phosphorylation of brain ErbB1, suggesting their effects on brain development. Repeated their injections similarly enhanced physical development of eyelid opening and tooth eruption during early postnatal stage and resulted in abnormal behavioral traits in the adult stage. Acoustic startle responses of mice treated with these growth factors as neonates were enhanced and prepulse inhibition was decreased without an apparent correlation between prepulse inhibition level and startle intensity. Locomotor activity and fear-learning performance with tone and context cues were not altered, however. These results suggest that circulating ErbB1 ligands in the periphery of neonates have some common influences on later behavioral traits. Abnormal ErbB1 ligand production at neonatal and potentially prenatal stages might therefore associate with neurodevelopmental disorders such as schizophrenia.

Recent progress in animal modeling of immune inflammatory processes in schizophrenia: implication of specific cytokines

Epidemiologic studies demonstrate significant environmental impact of maternal viral infection and obstetric complications on the risk of schizophrenia and indicate their detrimental influences on brain development in this disorder. Based on these findings, animal models for schizophrenia have been established using double stranded RNA, bacterial lipopolysaccharides, hippocampal lesion, or prenatal/perinatal ischemia. Key molecules regulating such immune/inflammatory reactions are cytokines, which are also involved in brain development, regulating dopaminergic and GABAergic differentiation, and synaptic maturation. Specific members of the cytokine family, such as interleukin-1, epidermal growth factor, and neuregulin-1, are induced after infection and brain injury; therefore, certain cytokines are postulated to have a central role in the neurodevelopmental defects of schizophrenia. Recently, to test this hypothesis, a variety of cytokines were administered to rodent pups. Cytokines administered in the periphery penetrated the immature blood-brain barrier and perturbed phenotypic neural development. Among the many cytokines examined, epidermal growth factor (or potentially other ErbB1 ligands) and interleukin-1 specifically induced the most severe and persistent behavioral and cognitive abnormalities, most of which were ameliorated by antipsychotics. These animal experiments illustrate that, during early development, these cytokine activities in the periphery perturbs normal brain development and impairs later psychobehavioral and/or cognitive traits. The neurodevelopmental and behavioral consequences of prenatal/perinatal cytokine activity are compared with those of other schizophrenia models and cytokine interactions with genes are also discussed in this review.

Epidermal growth factor prevents prepartum luteolysis in the rat

We have previously reported that intrauterine (i/u) administration of epidermal growth factor (EGF 500 ng) on day (d) 21 of pregnancy delayed 19.0 +/- 0.6 h the onset of labor. Progesterone (P) is secreted by ovarian corpora lutea (CL) throughout gestation in the rat. Prepartum CL regression due to increased uterine cyclooxygenase I and prostaglandin F(2alpha) results in P withdrawal followed by labor. The aims of the present work were (i) to study whether EGF delayed-onset of labor was mediated by a mechanism that prevented CL regression; (ii) to determine amniotic fluid (AF) EGF in pregnant rats. Rats on d21 of pregnancy received i/u EGF (500 ng) and were killed 0, 4, 8, 12, 24, and 48 h later. Control AF from rats on d13 and 18-22 of pregnancy was obtained. EGF decreased uterine prostaglandin F(2alpha) synthesis 8 h after treatment. Twelve hours after EGF injection, P reached its highest serum level and uterine cyclooxygenase I expression was undetectable. CL from rats killed 8 and 12 h after EGF were similar to those from rats on d13 of pregnancy, when serum P is maximum. EGF in AF increased throughout gestation, reached a maximum on d21, and decreased before the onset of labor. We suggest that the effect of EGF on the onset of labor was mediated by an early effect on the uterus that prevented prepartum CL regression.

Diabetic pregnancy associated with increased epidermal growth factor in cord serum at term

OBJECTIVE

Epidermal growth factor is a ubiquitous mitogen that also possesses insulin-like properties. Fetal mal-growth is associated with altered epidermal growth factor levels. Maternal diabetes is frequently complicated by macrosomia, but the effect of maternal diabetes on fetal epidermal growth factor levels is not known. We studied cord serum epidermal growth factor concentrations in pregnancies complicated by diabetes and in normal pregnancies.

METHODS

Cord serum epidermal growth factor concentrations were measured at birth by a sandwich-type time-resolved immunofluorometric assay in 63 pregnancies complicated by insulin-dependent diabetes mellitus, in 25 pregnancies complicated by insulin-treated gestational diabetes, and in 56 normal pregnancies.

RESULTS

Cord serum epidermal growth factor correlated positively with the duration of pregnancy in diabetic and normal pregnancies. In a subgroup of women at similar gestational ages (38-39 weeks), cord serum epidermal growth factor concentrations were higher in pregnancies complicated by insulin-dependent diabetes mellitus (962 +/- 211 ng/L, P =.047; n = 9) and in pregnancies complicated by gestational diabetes (1133 +/- 115 ng/L, P =.001; n = 9) than in controls (564 +/- 75 ng/L; n = 22). In multiple regression analysis, only umbilical artery hemoglobin in diabetic pregnancies and vaginal delivery in normal pregnancies were associated with cord serum epidermal growth factor.

CONCLUSION

Epidermal growth factor concentrations are higher than normal in fetuses of diabetic mothers at term. Pregnancy complications, such as hypertensive disorders, fetal hypoxia and fetal malgrowth, may not explain the rise in epidermal growth factor levels. We hypothesize that the rise in epidermal growth factor levels is a metabolic response of the fetoplacental unit to diabetes-related hyperglycemia.

LEVEL OF EVIDENCE

III

Activation of the mitogen-activated protein kinase cascade is necessary but not sufficient for basic fibroblast growth factor- and epidermal growth factor-stimulated expression of endothelial nitric oxide synthase in ovine fetoplacental artery endothelial cells

Basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF) may play important roles in the placental vasculature, not only by controlling cell growth and differentiation, but also by mediating production of local vasodilators such as nitric oxide. As the mitogen-activated protein kinase (MAPK) signal cascade has been widely associated with cell growth in response to growth factors, herein we investigate whether bFGF, EGF, and VEGF also stimulate expression of endothelial nitric oxide synthase (eNOS) via activation of the MAPK cascade in ovine fetoplacental artery endothelial cells. The presence of the receptors for all three growth factors was confirmed by both immunocytochemistry and a functional cell proliferation assay. All three growth factors at 10 ng/ml rapidly (<10 min) activated MAPK. This activation was inhibited by PD 98059, a specific MAPK kinase inhibitor. bFGF and EGF, but not VEGF, dose- and time-dependently increased eNOS protein levels. Maximal stimulatory effects of bFGF and EGF on eNOS protein expression were observed at 10 ng/ml for 24 h of treatment and were associated with elevated eNOS messenger RNA. PD 98059 also significantly inhibited bFGF- and EGF-induced increases in eNOS protein expression. Because treatment with all three growth factors resulted in activation of the MAPK cascade, while bFGF and EGF, but not VEGF, increased eNOS expression, we conclude that activation of the MAPK cascade is necessary, but not sufficient, for bFGF- and EGF-induced increases in eNOS protein expression in ovine fetoplacental artery endothelial cells. Thus, additional signaling pathways are implicated in the different controls of eNOS expression and mitogenesis by growth factors.

Effects of angiogenic growth factors on endothelium-derived prostacyclin production by ovine uterine and placental arteries

Uteroplacental and fetoplacental arteries produce substantial amounts of prostacyclin (PGI2). Because angiogenic growth factors such as basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF) are increased in pregnancy, we hypothesized that treatment of uterine and fetoplacental arteries with bFGF, VEGF, and EGF would further enhance the pregnancy-induced increase in PGI2 production. Duplicate uterine (UA) and fetoplacental (PA) artery (primary branch off of the umbilical cord = pPA; cotyledonary or tertiary = tPA) explants from seven late gestation sheep were placed in tissue culture (RPMI; 37 degrees C) for 24 h alone or with (1-100 ng/mL) bFGF, VEGF, or EGF. To evaluate the endothelial contribution to basal and stimulated PGI2 production and to determine whether it is de novo, arteries with and without endothelium from three additional late gestation ewes, tissues were incubated in the absence or presence of growth factors with or without meclofenamate (1 microM). The stable metabolite of PGI2, 6-keto-PGF1 alpha, was measured in culture media and expressed as ng/mg wet wt 24 h. PGI2 production by UA increased (p < 0.05) from 5.43 +/- 0.26 at control to 8.93 +/- 0.99 with 100 ng/mL bFGF. Although VEGF produced a similar response, EGF did not increase PGI2 production in UA. In pPA, 100 ng/mL bFGF induced a 2.2-fold increase (p < 0.01) in PGI2 production from 1.94 +/- 0.14 to 4.20 +/- 0.31; VEGF and EGF were without effect. In tPA, 50 and 100 ng/mL bFGF increased PGI2 production from 1.98 +/- 0.14 to 3.5 +/- 1.05 and 3.96 +/- 0.46 (p < 0.02). In tPA, VEGF did not increase PGI2 production; however, 10, 50, and 100 ng/mL EGF, enhanced (p < 0.03) PGI2 production from 1.98 +/- 0.14 to 3.39 +/- 0.62, 3.62 +/- 0.26, and 2.93 +/- 0.20. Endothelium removal and meclofenamate treatment caused a 90% and 100% decrease, respectively, in basal PGI2 production, with no recovery after treatment with growth factors. We conclude that PGI2 production is augmented by bFGF in UA, pPA and tPA, by VEGF in UA, and by EGF in tPA during ovine pregnancy. Basal and stimulated PGI2 secretion is endothelium-derived via de novo synthesis. bFGF, VEGF, and EGF, in addition to angiogenesis, may modulate PGI2 production, further enhancing blood flow to the growing uteroplacental bed.