The adipokine preadipocyte factor-1 is downregulated in preeclampsia and expressed in placenta

Low Maternal DLK1 Levels at 26 Weeks Is Associated With Small for Gestational Age at Birth

Detecting SGA (small for gestational age) during pregnancy improves the fetal and neonatal prognosis. To date, there is no valid antenatal biomarker of SGA used in clinical practice. Maternal circulating DLK1 (delta-like non-canonical notch ligand 1) levels have been shown to be significantly lower in pregnant women at 36 weeks of gestation (WG) who delivered a SGA newborn than in controls. Data in the literature are contradictory on the association between maternal circulating DLK1 levels and placental vascular dysfunction. The objective was to determine if maternal DLK1 levels in the second trimester of pregnancy are predictive of SGA, and to assess whether the measurement of DLK1 levels in maternal blood could be a means to distinguish SGA with placental vascular dysfunction from that due to other causes. We conducted a nested cased-control study within the EDEN mother-child cohort. 193 SGA (birth weight < 10^th percentile) and 370 mother-child control (birth weight between the 25^th and 75^th percentile) matched pairs were identified in the EDEN cohort. Maternal circulating DLK1 levels at 26 WG were significantly lower for children born SGA than for controls (27.7 ± 8.7 ng/mL vs 30.4 ± 10.6 ng/mL, p = 0.001). Maternal blood DLK1 levels in the first quartile (DLK1 < 22.85 ng/mL) were associated with an odds ratio for SGA of 1.98 [1.15 - 3.37]. DLK1 was less predictive of SGA than ultrasound, with an area under the curve of 0.578. Maternal circulating DLK1 levels were not significantly different in cases of SGA with signs of placental vascular dysfunction (n = 63, 27.1 ± 9.2 ng/mL) than in those without placental dysfunction (n = 129, 28.0 ± 8.5 ng/mL, p = 0.53). The level of circulating DLK1 is reduced in the second trimester of pregnancy in cases of SGA at birth, independently of signs of placental vascular dysfunction. However, DLK1 alone cannot predict the risk of SGA.

Adipose tissue development and lipid metabolism in the human fetus: The 2020 perspective focusing on maternal diabetes and obesity

During development, the human fetus accrues the highest proportion of fat of all mammals. Precursors of fat lobules can be found at week 14 of pregnancy. Thereafter, they expand, filling with triacylglycerols during pregnancy. The resultant mature lipid-filled adipocytes emerge from a developmental programme of embryonic stem cells, which is regulated differently than adult adipogenesis. Fetal triacylglycerol synthesis uses glycerol and fatty acids derived predominantly from glycolysis and lipogenesis in liver and adipocytes. The fatty acid composition of fetal adipose tissue at the end of pregnancy shows a preponderance of palmitic acid, and differs from the mother. Maternal diabetes mellitus does not influence this fatty acid profile. Glucose oxidation is the main source of energy for the fetus, but mitochondrial fatty acid oxidation also contributes. Indirect evidence suggests the presence of lipoprotein lipase in fetal adipose tissue. Its activity may be increased under hyperinsulinemic conditions as in maternal diabetes mellitus and obesity, thereby contributing to increased triacylglycerol deposition found in the newborns of such pregnancies. Fetal lipolysis is low. Changes in the expression of genes controlling metabolism in fetal adipose tissue appear to contribute actively to the increased neonatal fat mass found in diabetes and obesity. Many of these processes are under endocrine regulation, principally by insulin, and show sex-differences. Novel fatty acid derived signals such as oxylipins are present in cord blood with as yet undiscovered function. Despite many decades of research on fetal lipid deposition and metabolism, many key questions await answers.

The role of serum adipokine levels in preeclampsia: A systematic review

BACKGROUND

Preeclampsia represents a major pregnancy complication, associated with high rates of perinatal morbidity. The aim of this systematic review is to accumulate current literature evidence in order to examine the pattern of serum adipokine levels among preeclamptic women and asses their potential efficacy in the prediction of the disease.

METHODS

Medline, Scopus, CENTRAL, Clinicaltrials.gov and Google Scholar databases were systematically searched from inception. All observational studies reporting serum adipokine values among preeclamptic and healthy pregnant women were held eligible.

RESULTS

A total of 163 studies were included, comprising 23,482 women. Leptin was evaluated in 91 studies and its values were found to be significantly elevated in preeclamptic women during all pregnancy trimester, independently of disease onset and severity. Preeclampsia was also associated with increased serum fatty acid binding protein-4 and chemerin levels, when measured both during the 1st and 3rd trimester. Data concerning the rest adipokines were either conflicting or limited to reach firm conclusions. Quality of evidence was evaluated to be high for leptin, moderate for serum fatty acid binding protein-4 and chemerin and low for the other adipokines.

CONCLUSIONS

The existing evidence suggests that preeclampsia is linked to increased levels of leptin, chemerin and fatty acid binding protein-4 in all pregnancy trimesters and forms of the disease. Inconsistent data currently exists concerning the role of the other adipokines. Large-scale prospective studies should longitudinally evaluate the serum concentration of novel adipokines and define the optimal threshold and timing of measurement to be widely applied in clinical practice.

Preadipocyte factor-1 in maternal, umbilical cord serum and breast milk: The impact of fetal growth

BACKGROUND/OBJECTIVE

To study the concentrations of preadipocyte factor-1 (Pref-1) -an inhibitor of adipocyte differentiation, implicated in adipose tissue metabolism, late metabolic disorders and fetal growth- in maternal and umbilical cord serum, as well as maternal milk and correlate above concentrations with intrauterine growth and other perinatal parameters.

MATERIAL AND METHODS

Pref-1 concentrations were determined by ELISA in antepartum maternal and umbilical cord serum, as well as day 3 to 4 postpartum breast milk, deriving from 80 women, who delivered 40 appropriate (AGA), 20 large for gestational age (LGA) and 20 intrauterine growth restricted (IUGR) neonates, classified by the use of customized birth-weight standards adjusted for significant determinants of fetal growth.

RESULTS

Umbilical cord serum Pref-1 concentrations were significantly higher than antepartum maternal ones (p < 0.001), while breast milk concentrations were the lowest (p < 0.001 concerning umbilical serum, p < 0.001 concerning maternal serum). Umbilical cord serum Pref-1 concentrations were significantly lower in the LGA group than in the AGA one (p = 0.044). Breast milk and maternal serum Pref-1 concentrations did not differ between the three intrauterine growth groups. Maternal serum and breast milk Pref-1 concentrations did not correlate with maternal age, body mass index before and after gestation, birth weight, body length, and customized centile. A positive weak correlation was recorded between maternal serum and milk Pref-1 concentrations (r = 0.238, p = 0.034).

CONCLUSIONS

Pref-1 concentrations in umbilical cord serum are higher than in antepartum maternal serum, probably pointing to its fetal origin and role in intrauterine growth. Breast milk concentrations, being extremely low, and possibly implying infant protection from metabolic disorders, positively correlate with maternal serum ones, conceivably suggesting a transfer of the substance from the circulation to the breast. Umbilical cord serum Pref-1 concentrations were lower in LGA fetuses/neonates, as compared to respective AGA ones.

Screening for fetal growth restriction using fetal biometry combined with maternal biomarkers

Fetal growth restriction is a major determinant of perinatal morbidity and mortality. Screening for fetal growth restriction is a key element of prenatal care but it is recognized to be problematic. Screening using clinical risk assessment and targeting ultrasound to high-risk women is the standard of care in the United States and United Kingdom, but the approach is known to have low sensitivity. Systematic reviews of randomized controlled trials do not demonstrate any benefit from universal ultrasound screening for fetal growth restriction in the third trimester, but the evidence base is not strong. Implementation of universal ultrasound screening in low-risk women in France failed to reduce the risk of complications among small-for-gestational-age infants but did appear to cause iatrogenic harm to false positives. One strategy to making progress is to improve screening by developing more sensitive and specific tests with the key goal of differentiating between healthy small fetuses and those that are small through fetal growth restriction. As abnormal placentation is thought to be the major cause of fetal growth restriction, one approach is to combine fetal biometry with an indicator of placental dysfunction. In the past, these indicators were generally ultrasonic measurements, such as Doppler flow velocimetry of the uteroplacental circulation. However, another promising approach is to combine ultrasonic suspicion of small-for-gestational-age infant with a blood test indicating placental dysfunction. Thus far, much of the research on maternal serum biomarkers for fetal growth restriction has involved the secondary analysis of tests performed for other indications, such as fetal aneuploidies. An exemplar of this is pregnancy-associated plasma protein A. This blood test is performed primarily to assess the risk of Down syndrome, but women with low first-trimester levels are now serially scanned in later pregnancy due to associations with placental causes of stillbirth, including fetal growth restriction. The development of "omic" technologies presents a huge opportunity to identify novel biomarkers for fetal growth restriction. The hope is that when such markers are measured alongside ultrasonic fetal biometry, the combination would have strong predictive power for fetal growth restriction and its related complications. However, a series of important methodological considerations in assessing the diagnostic effectiveness of new tests will have to be addressed. The challenge thereafter will be to identify novel disease-modifying interventions, which are the essential partner to an effective screening test to achieve clinically effective population-based screening.

The brown-fat-secreted adipokine neuregulin 4 is decreased in gestational diabetes mellitus

AIMS

Neuregulin 4 has recently been recognized as a novel adipokine secreted by brown adipose tissue (BAT), with beneficial effects on murine insulin resistance and hepatic steatosis. Yet, thus far, neither regulation of neuregulin 4 in gestational diabetes mellitus (GDM) nor its longitudinal changes in the peripartum period have been elucidated.

METHODS

Circulating neuregulin 4 levels were measured by ELISA in 74 women with GDM and 74 healthy, gestational-age-matched controls. Also, neuregulin 4 was quantified during pregnancy and compared with postpartum levels in a follow-up study of 25 women with previous GDM and 25 healthy control women.

RESULTS

Women with GDM had lower median serum levels of the novel BAT-secreted adipokine neuregulin 4 (3.0μg/L) compared with healthy (non-GDM) pregnant controls (3.5μg/L; P=0.020), and the area under the glucose curve (AUC_Glucose) was an independent and negative predictor of circulating neuregulin 4 (P=0.033). Also, median postpartum serum concentrations of neuregulin 4 (3.2μg/L) were not significantly different from prepartum levels (2.8μg/L; P=0.328). In addition, neuregulin 4 was positively and independently associated with irisin (P=0.009), but not other BAT-secreted adipokines.

CONCLUSION/INTERPRETATION

Women with GDM have significantly lower circulating neuregulin 4 levels compared with healthy pregnant controls, and the AUC_Glucose is negatively and independently associated with neuregulin 4 during pregnancy. Neuregulin 4 is positively correlated with irisin during pregnancy, as well as in a longitudinal fashion. Future studies are now needed to better elucidate the precise pathomechanisms of the regulation of BAT-secreted adipokines during pregnancy.

Regulation of the novel adipokines/ hepatokines fetuin A and fetuin B in gestational diabetes mellitus

OBJECTIVE

Fetuin B has recently been introduced as a novel adipokine/hepatokine which is significantly increased in hepatic steatosis and mediates impaired insulin action, as well as glucose intolerance. However, regulation of fetuin B in gestational diabetes mellitus (GDM), as well as its longitudinal changes in the peripartum period, have not been elucidated, so far.

DESIGN AND METHODS

Circulating fetuin A and fetuin B were quantified in 74 women with GDM and 74 healthy and gestational age-matched controls by enzyme-linked immunosorbent assay during pregnancy (median gestational age: 201days). Furthermore, fetuin B was quantified during pregnancy as compared to postpartum levels in a follow-up study (median time after delivery: 4years and 115days).

RESULTS

Median [interquartile range] serum fetuin B levels were significantly higher in women with GDM (4.8 [1.7] mg/l) as compared to non-diabetic pregnant controls (4.3 [1.2] mg/l) (p=0.013) during pregnancy. In multivariate analysis, GDM status, insulin resistance, and fetuin A were independent and positive predictors of circulating fetuin B. Furthermore, fetuin B serum concentrations significantly decreased after delivery from 4.6 [1.7] mg/l (prepartum) to 3.0 [2.2] mg/l (postpartum) in all women (p<0.001).

CONCLUSIONS

Women with GDM have significantly higher fetuin B levels as compared to healthy pregnant control women and GDM status, insulin resistance, and fetuin A positively predict circulating fetuin B. Postpartum fetuin B is decreased as compared to prepartum values suggesting a placental co-secretion of this novel adipokine/hepatokine. Further studies need to elucidate factors contributing to fetuin B regulation in humans, as well as the pathophysiological significance of fetuin B upregulation in GDM.

Fetus-derived DLK1 is required for maternal metabolic adaptations to pregnancy and is associated with fetal growth restriction

Pregnancy is a state of high metabolic demand. Fasting diverts metabolism to fatty acid oxidation, and the fasted response occurs much more rapidly in pregnant women than in non-pregnant women. The product of the imprinted DLK1 gene (delta-like homolog 1) is an endocrine signaling molecule that reaches a high concentration in the maternal circulation during late pregnancy. By using mouse models with deleted Dlk1, we show that the fetus is the source of maternal circulating DLK1. In the absence of fetally derived DLK1, the maternal fasting response is impaired. Furthermore, we found that maternal circulating DLK1 levels predict embryonic mass in mice and can differentiate healthy small-for-gestational-age (SGA) infants from pathologically small infants in a human cohort. Therefore, measurement of DLK1 concentration in maternal blood may be a valuable method for diagnosing human disorders associated with impaired DLK1 expression and to predict poor intrauterine growth and complications of pregnancy.