Ellen Struwe

Microarray analysis of placental tissue in intrauterine growth restriction

Objective  Besides foetal or maternal disorders, placental dysfunction is a major cause of intrauterine growth restriction (IUGR). Although numerous macro‐ and histopathological changes have been described, little is known about the precise aetiology and the contribution of foetal/placental genes in this disorder.

Differences in gene expression dependent on sampling site in placental tissue of fetuses with intrauterine growth restriction

OBJECTIVE The human placenta as part of the feto-placental unit may influence fetal endocrine systems and may therefore represent a very important link between intrauterine growth restriction (IUGR) and metabolic disorders in later life. We aimed to analyze the effect of sample origin on gene expression of placental factors potentially involved in fetal programming in IUGR versus appropriate for gestational age growth (AGA) to standardize sample collection procedure for a multicenter approach. DESIGN Placental gene expression of insulin-like growth factor-binding protein (IGFBP)-1, prolactin, corticotropin releasing hormone (CRH) and leptin was measured and compared between proximal, intermediate and peripheral region of the placenta in 22 IUGR (proven by anomalous placental Doppler velocimetry) and 19 AGA neonates. RESULTS Whereas no difference in gene expression was seen in the proximal portion, in the intermediate placental region mRNA expression of IGFBP-1 (p = 0.01), prolactin (p = 0.04), CRH (p = 0.01) and leptin (p = 0.04) was increased in IUGR samples compared to controls. At the placental periphery, gene expression of these placental transcripts showed a higher expression level in IUGR placentas without statistical significance, except for leptin (p = 0.03). CONCLUSION Placental sampling site seems to be relevant for detecting differences in gene expression between IUGR and AGA neonates.

Intrauterine growth restriction (IUGR) is associated with increased leptin synthesis and binding capability in neonates.

Objective  Animal studies suggest pathological foetal programming of hypothalamic circuits regulating food intake in the setting of leptin deficiency and intrauterine growth restriction (IUGR). We aimed to compare placental leptin synthesis and leptin‐binding capability in venous cord blood between IUGR newborns and neonates born appropriate for gestational age (AGA).

Placental 11β-HSD2 Gene Expression at Birth Is Inversely Correlated With Growth Velocity in the First Year of Life After Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) is associated with an increased risk for short stature and diseases in adulthood thought to be inflicted by fetal programming. We hypothesized that placental endocrine systems involved in perinatal growth might also play a role in postnatal growth after IUGR. In a prospective controlled multicenter study, placental gene expression of IGF-binding protein-1 (IGFBP-1), leptin and 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) were measured in 14 IUGR infants and 15 children born appropriate for gestational age (AGA) proven by serial ultrasound examinations. Postnatally, IUGR infants experienced a significantly higher growth velocity than AGA neonates (at 1 y: p = 0.001). Gene expression of 11β-HSD2 at birth correlated positively with birth length (r = 0.55, p = 0.04) and inversely with growth velocity in the first year of life (r = −0.69, p = 0.01) in the IUGR, but not in the AGA group. There was no correlation between gene expression of placental IGFBP-1, leptin and birth weight, length and growth velocity during the first year of life. AGA infants showed significantly higher concentrations of cortisone in venous cord blood after birth (p = 0.02) as a surrogate of a higher 11β-HSD2 activity in the fetoplacental unit. In conclusion, placental 11β-HSD2 gene expression might predict postnatal growth in IUGR.

Gene expression of placental hormones regulating energy balance in small for gestational age neonates

OBJECTIVE Fetal growth restriction is associated with an increased risk for metabolic and cardiovascular disease in later life. To further elucidate mechanisms that might be involved in the process of prenatal programming, we measured the adipokines leptin, resistin, and adiponectin and the GH-releasing hormone ghrelin in the placenta of small for gestational age (SGA) neonates. STUDY DESIGN The control group included 24 placentas of appropriate for gestational age (AGA) newborns, in the study group were 16 placentas of SGA neonates. Gene expression of leptin, resistin, adiponectin, and ghrelin was examined. For hormones showing alterations in gene regulation placental protein expression was measured by Western blot. RESULTS Placental mRNA expression of leptin was significantly increased in SGA placentas (p=0.0035, related to beta-actin). Protein concentration was increased, as well. There were no differences in placental resistin, adiponectin, or ghrelin gene expressions between SGA neonates and controls. Leptin was the only hormone to demonstrate a significant inverse correlation with birth weight (r=-0.44, p=0.01). Adiponectin correlated significantly with leptin (r=0.53, p=0.0023) and ghrelin (r=0.50, p=0.0045). CONCLUSIONS Placental leptin gene expression and protein concentration showed the expected increase in the SGA group. Leptin was inversely correlated with birth weight. Positive correlation of adiponectin with leptin and ghrelin expression suggests an interaction between these hormones in the placenta. However, the unchanged expression of resistin, adiponectin, and ghrelin in SGA placentas and the absence of correlation with birth weight cast doubt whether these hormones produced in the placenta play a key role in fetal programming.

Dexamethasone stimulates the expression of leptin and 11β-HSD2 in primary human placental trophoblastic cells

OBJECTIVES Fetal glucocorticoid excess is thought to play an important role in early-life programming, promoting growth restriction and contributing to adult metabolic, cardiovascular and neuroendocrine disease. We hypothesized that dexamethasone incubation of primary trophoblastic cells from human healthy placentas at term might induce altered gene and protein expression of several endocrine placental regulators. STUDY DESIGN Primary villous trophoblastic cells were incubated with 10 μM dexamethasone for 6, 12, 24, 48 and 72 h. Non-incubated trophoblastic cells served as vehicle control. Gene expression of leptin, 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) and insulin-like growth factor-binding protein-1 (IGFBP-1) was measured. Moreover, leptin, β-human chorionic gonadotropine (β-hCG) and lactate dehydrogenase (LDH) release into the culture medium was determined. RESULTS Leptin gene expression was significantly increased in dexamethasone-incubated trophoblastic cells after 24, 48 and 72 h. There was a significant increase in leptin concentration in the medium of the cell culture after 48 h. Gene expression of 11β-HSD2 was significantly higher in dexamethasone-stimulated trophoblastic cells compared to vehicle controls after 72 h. The expression rate of IGFBP-1 mRNA was basal throughout the incubation period. The concentration of β-HCG in the supernatant increased significantly after 72 h of dexamethasone incubation, while LDH concentrations remained stable. CONCLUSION Our findings suggest that dexamethasone incubation stimulates leptin and 11β-HSD2 gene expression in primary villous trophoblastic cells of healthy human placentas, while enhancing cytotrophoblast differentiation.

Differential effects of low birthweight and intrauterine growth restriction on umbilical cord blood insulin-like growth factor concentrations.

Alterations in the growth hormone–insulin‐like growth factor (IGF) axis have been considered as a causal factor for intrauterine growth restriction (IUGR) and for the increased risk of metabolic disease in later life. We compared members of the IGF axis in umbilical cord blood between IUGR neonates, small for gestational age without foetal restriction (SGA) and appropriate for gestational age (AGA) neonates.

DNA methylation of the p66Shc promoter is decreased in placental tissue from women delivering intrauterine growth restricted neonates

The adaptor protein p66Shc generates mitochondrial reactive oxygen species and translates oxidative signals into apoptosis. We aimed to analyze potential alterations in total methylation and in p66Shc activation in placental tissues from women delivering intrauterine growth restricted neonates (IUGR) versus appropriate for gestational age (AGA) and small for gestational age (SGA) neonates.

Intrauterine Growth Restriction (IUGR) Induces Signs of Subclinical Atherosclerosis in 6-Year-Old Infants Despite Absence Of Excessive Growth

Background Postnatal catch-up growth and rapid weight gain after intrauterine growth restriction (IUGR) seem to increase the risk for later disease. This study aimed to compare features of the metabolic syndrome early in life between IUGR and appropriate for gestational age (AGA) infants. Patients Data for 9 infants with IUGR defined by a birth weight<10th percentile and ultrasound-proven placental insufficiency and 11 AGA children were available. Method Postnatal growth, auxological, cardiovascular, and metabolic parameters up to a chronological age of 6 years were assessed: Fasting serum concentrations of LDL-cholesterol, insulin, leptin, IGF-I, DHEAS, skinfold thicknesses, blood pressure, and mean carotid intima-media thickness (cIMT). Results All IUGR infants showed catch-up growth, although mean BMI SDS and total subcutaneous fat mass at the age of 6 years were still slightly lower compared to the AGA cohort. Reduced serum leptin concentrations were observed in IUGR infants (p=0.02), whereas no significant difference was found for IGF-I, insulin, LDL-cholesterol and DHEAS concentrations. Mean cIMT was significantly higher in IUGR infants (p<0.05). Mean arterial pressure did no differ. Discussion and Conclusion In 6-year-old IUGR infants with catch-up growth, who still had a slightly reduced BMI SDS compared to the AGA group, signs of subclinical atherosclerosis were detectable suggesting that cardiovascular risk in IUGR may be present even in the absence of excessive growth.

Placental and Fetal Endocrine Systems Depend on the Cause of Low Birth Weight

Introduction: Low birth weight is caused by a huge number of different conditions ranging from constitutional shortness in a healthy newborn to severe fetal and maternal disease interfering with the growth of the fetus. In many studies examining the effect of low birth weight on later morbidity these different causes are not accounted for. It is therefore the objective of the present study to examine the impact of different causes of low birth weight in rats and humans. Animal studies: Two rat models used for experimental research of IUGR were examined: The isocaloric low protein model and the bilateral uterine artery ligation model. The offspring was delivered at day 22 of gestation and placenta and liver were immediately snap frozen. Using real time PCR, the gene expression of leptin and IGF-I was examined in the two tissues. In placental tissue, there was an inverse pattern of leptin and IGF-I gene expression with an upregulation in the low protein model and a downregulation in the ligation model. In liver, IGF-I expression was decreased in the ligation but not in the low protein model. Human studies: In a multicenter study placental tissue and umbilical blood of neonates with IUGR (birth weight < 10 percentile and pathological placental Doppler velocimetry), SGA (birth weight < 10 percentile, no pathological Doppler), and controls were obtained. Umbilical leptin concentration was similar in all groups. However, the concentration of the soluble leptin receptor, decreasing bioavailability of leptin, was significantly increased in IUGR infants only. For IGF-I, there was a decrease of cord blood concentration from control neonates via SGA to IUGR infants, while IGFBP-1 was not altered. Placental expression of leptin was increased in IUGR compared to AGA and SGA. Conclusions: Studies in rats and humans indicate that the underlying cause of low birth weight appears to be essential for the availability of leptin and IGF-I. Since both hormones have been closely related to perinatal programming, it may be concluded that different causes of low birth weight lead to a distinct programming of the leptin and IGF-I pathways. As a consequence, various phenotypes of adult onset disease will have to be expected in low birth weight infants.