Placental and fetal steroidogenesis

The association between newborn cord blood steroids and ambient prenatal exposure to air pollution: findings from the ENVIRONAGE birth cohort

Knowledge of whether prenatal exposure to ambient air pollution disrupts steroidogenesis is currently lacking. We investigated the association between prenatal ambient air pollution and highly accurate measurements of cord blood steroid hormones from the androgenic pathway.This study included 397 newborns born between the years 2010 and 2015 from the ENVIRONAGE cohort in Belgium of whom six cord blood steroid levels were measured: 17α-hydroxypregnenolone, 17α-hydroxyprogesterone, dehydroepiandrosterone, pregnenolone, androstenedione, and testosterone. Maternal ambient exposure to PM2.5 (particles with aerodynamic diameter ≤ 2.5 μm), NO2, and black carbon (BC) were estimated daily during the entire pregnancy using a high-resolution spatiotemporal model. The associations between the cord blood steroids and the air pollutants were tested and estimated by first fitting linear regression models and followed by fitting weekly prenatal exposures to distributed lag models (DLM). These analyses accounted for possible confounders, coexposures, and an interaction effect between sex and the exposure. We examined mixture effects and critical exposure windows of PM2.5, NO2 and BC on cord blood steroids via the Bayesian kernel machine regression distributed lag model (BKMR-DLM).An interquartile range (IQR) increment of 7.96 µg/m3 in PM2.5 exposure during pregnancy trimester 3 was associated with an increase of 23.01% (99% confidence interval: 3.26-46.54%) in cord blood levels of 17α-hydroxypregnenolone, and an IQR increment of 0.58 µg/m³ in BC exposure during trimester 1 was associated with a decrease of 11.00% (99% CI: -19.86 to -0.012%) in cord blood levels of androstenedione. For these two models, the DLM statistics identified sensitive gestational time windows for cord blood steroids and ambient air pollution exposures, in particular for 17α-hydroxypregnenolone and PM2.5 exposure during trimester 3 (weeks 28-36) and for androsterone and BC exposure during early pregnancy (weeks 2-13) as well as during mid-pregnancy (weeks 18-26). We identified interaction effects between pollutants, which has been suggested especially for NO2.Our results suggest that prenatal exposure to ambient air pollutants during pregnancy interferes with steroid levels in cord blood. Further studies should investigate potential early-life action mechanisms and possible later-in-life adverse effects of hormonal disturbances due to air pollution exposure.

Effects of Maternal Cigarette Smoking on Trace Element Levels and Steroidogenesis in the Maternal-Placental-Fetal Unit

This study evaluates the interaction of toxic elements cadmium (Cd) and lead (Pb) due to exposure from cigarette smoking, essential elements, and steroidogenesis in the maternal-placental-fetal unit. In a cohort of 155 healthy, postpartum women with vaginal term deliveries in clinical hospitals in Zagreb, Croatia, samples of maternal blood/serum and urine, placental tissue, and umbilical cord blood/serum were collected at childbirth. The biomarkers determined were concentrations of Cd, Pb, iron (Fe), zinc (Zn), copper (Cu), and selenium (Se), and steroid hormones progesterone and estradiol in maternal and umbilical cord blood and the placenta. Three study groups were designated based on self-reported data on cigarette smoking habits and confirmed by urine cotinine levels: never smokers (n = 71), former smokers (n = 48), and active smokers (n = 36). Metal(loid)s, steroid hormones, urine cotinine, and creatinine levels were analyzed by ICP-MS, ELISA, GC-MS, and spectrophotometry. Cigarette smoking during pregnancy was associated with increased Cd levels in maternal, placental, and fetal compartments, Pb in the placenta, and with decreased Fe in the placenta. In active smokers, decreased progesterone and estradiol concentrations in cord blood serum were found, while sex steroid hormones did not change in either maternal serum or placenta. This study provides further evidence regarding toxic and essential metal(loid) interactions during prenatal life, and new data on sex steroid disruption in cord serum related to cigarette smoking. The results indicate that umbilical cord sex steroid levels may be a putative early marker of developmental origins of the future burden of disease related to harmful prenatal exposure to cigarette smoke.

Steroid profiling in the amniotic fluid: reference range for 12 steroids and interest in 21-hydroxylase deficiency

INTRODUCTION

Determination of steroid levels in the amniotic fluid gives some insight on foetal adrenal and gonadal functions. Our objectives were to establish reference ranges of 12 steroid levels throughout pregnancy and to compare them with steroid levels from pregnancies with foetuses presenting 21-hydroxylase deficiency (21OHD).

MATERIALS AND METHODS

Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was applied to 145 "control" amniotic fluid samples from gynaecology activity (12 + 6 to 32 + 4 Gestational Weeks, GW). The following steroids were analysed according to gestational age and compared to 23 amniotic fluid samples from foetuses with classic 21-hydroxylase deficiency confirmed by molecular studies: delta-4-androstenedione (D4), dehydroepiandrosterone (DHEA), 17-hydroxyprogesterone (17OHP), 11-deoxycortisol (11OH), 21-deoxycortisol (21OH), corticosterone, deoxycorticosterone (DOC), testosterone, pregnenolone, 17-hydroxypregnenolone (17Pregn), cortisol and cortisone. Chromosomal sex was determined by karyotype and gestational age by biometric measurements.

RESULTS

Analysis of "control" samples showed a statistically significant difference for D4 and testosterone levels according to foetal sex. Cortisol, corticosterone, and DOC had lower concentrations before 20 GW than after 20 GW, whereas 17Pregn and pregnenolone had higher concentrations before 20 GW. This allowed us to establish age- and sex-dependant reference values. We observed higher 21OH, 17Pregn, D4 and testosterone levels in females 21OHD than female controls. The ratios 17OHP/17Pregn, D4/DHEA and 11OH/17OHP appeared discriminant for the diagnosis of 21OHD.

CONCLUSION

Our study provides information on foetal steroidogenesis and suggests reference values for 12 steroids during pregnancy. This allows a prenatal diagnosis of 21-hydroxylase deficiency within 24 hours and might be useful in the diagnosis of other variations of sex development (VSD).

Rapid Quantification of Endogenous Steroids in Human Serum Using Leidenfrost Effect-Assisted Thermal Desorption Atmospheric Pressure Photoionization Orbitrap Mass Spectrometry

Unconjugated sex steroids in human serum play a crucial role in physiological and pathological studies and are frequently considered as biomarkers in clinical diagnosis. Because of their low polarity, poor volatility, and low concentration, the rapid and highly sensitive analysis of sex steroids in real serum matrix by ambient mass spectrometry is still challenging. Here, Leidenfrost effect-assisted thermal desorption atmospheric pressure photoionization orbitrap mass spectrometry (LETD-APPI-MS) was developed and applied to quantify free sex steroids in human serum without derivatization and chromatography separation within a few minutes. The concentration of target analyte could be increased by approximately two orders during the LETD process. The limit of quantifications and detections of endogenous sex steroids in human serum were measured at the ppt level. In contrast with commonly used immunoassays in clinical laboratories, LETD-APPI-MS enables the accurate measurements of multiple free sex steroids without the interference of cross-reactions. The endogenous sex steroids of 38 female serums at four physiological stages during pregnancy were rapidly tested by LETD-APPI-MS, whose results were highly consistent with that using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS), indicating LETD-APPI-MS has a strong clinical application potential in steroid analysis.

Pregnancy in Congenital Adrenal Hyperplasia

Fertility rates in classic congenital adrenal hyperplasia caused by 21-hydroxylase deficiency are substantially decreased for various reasons, including hormonal, anatomic, psychosocial, and psychosexual causes. However, fecundity is comparable with the general population. Under optimal hormone replacement, the course and outcome of pregnancies is also good. This article summarizes successful gestational management, including preconceptional considerations, adjustment of hormone replacement during pregnancy, delivery and lactation, as well as the prevention of adrenal crises. In nonclassic 21-hydroxylase deficiency, preconceptional low-dose hydrocortisone replacement normalizes the otherwise increased miscarriage rate. Pregnancy reports in rarer forms of congenital adrenal hyperplasia are summarized as well.

Steroidogenic Acute Regulatory Protein: Structure, Functioning, and Regulation

Steroidogenesis takes place mainly in adrenal and gonadal cells that produce a variety of structurally similar hormones regulating numerous body functions. The rate-limiting stage of steroidogenesis is cholesterol delivery to the inner mitochondrial membrane, where it is converted by cytochrome P450scc into pregnenolone, a common precursor of all steroid hormones. The major role of supplying mitochondria with cholesterol belongs to steroidogenic acute regulatory protein (STARD1). STARD1, which is synthesized de novo as a precursor containing mitochondrial localization sequence and sterol-binding domain, significantly accelerates cholesterol transport and production of pregnenolone. Despite a tremendous interest in STARD1 fueled by its involvement in hereditary diseases and extensive efforts of numerous laboratories worldwide, many aspects of STARD1 structure, functioning, and regulation remain obscure and debatable. This review presents current concepts on the structure of STARD1 and other lipid transfer proteins, the role of STARD1 in steroidogenesis, and the mechanism of its functioning, as well as identifies the most controversial and least studied questions related to the activity of this protein.

Aspectos generales del transporte de colesterol en la esteroidogénesis de la placenta humana

La placenta humana requiere de colesterol para sintetizar la progesterona que mantiene la relación entre el feto y la madre, lo que le permite concluir de manera exitosa el embarazo. La placenta incorpora el colesterol principalmente a través de las lipoproteínas de baja densidad (LDL) que se obtienen del torrente circulatorio materno por un mecanismo de endocitosis. A los endosomas que se generan en este proceso se les unen varias proteínas conformando los endosomas tardíos, que degradan las LDL y liberan el colesterol a las mitocondrias del sinciciotrofoblasto que lo transforman en pregnenolona y posteriormente en progesterona. Las proteínas de fusión de membranas denominados complejos SNARE participan en la liberación del colesterol en sitios de contacto específicos en donde se localizan las proteínas mitocondriales responsables de la esteroidogénesis.

Increasing fetal ovine number per gestation alters fetal plasma clinical chemistry values

Intrauterine growth restriction (IUGR) is interconnected with developmental programming of lifelong pathophysiology. IUGR is seen in human multifetal pregnancies, with stepwise rises in fetal numbers interfering with placental nutrient delivery. It remains unknown whether fetal blood analyses would reflect fetal nutrition, liver, and excretory function in the last trimester of human or ovine IUGR. In an ovine model, we hypothesized that fetal plasma biochemical values would reflect progressive placental, fetal liver, and fetal kidney dysfunction as the number of fetuses per gestation rose. To determine fetal plasma biochemical values in singleton, twin, triplet, and quadruplet/quintuplet ovine gestation, we investigated morphometric measures and comprehensive metabolic panels with nutritional measures, liver enzymes, and placental and fetal kidney excretory measures at gestational day (GD) 130 (90% gestation). As anticipated, placental dysfunction was supported by a stepwise fall in fetal weight, fetal plasma glucose, and triglyceride levels as fetal number per ewe rose. Fetal glucose and triglycerides were directly related to fetal weight. Plasma creatinine, reflecting fetal renal excretory function, and plasma cholesterol, reflecting placental excretory function, were inversely correlated with fetal weight. Progressive biochemical disturbances and growth restriction accompanied the rise in fetal number. Understanding the compensatory and adaptive responses of growth‐restricted fetuses at the biochemical level may help explain how metabolic pathways in growth restriction can be predetermined at birth. This physiological understanding is important for clinical care and generating interventional strategies to prevent altered developmental programming in multifetal gestation.

Mitochondrial cholesterol import

All animal subcellular membranes require cholesterol, which influences membrane fluidity and permeability, fission and fusion processes, and membrane protein function. The distribution of cholesterol among subcellular membranes is highly heterogeneous and the cholesterol content of each membrane must be carefully regulated. Compared to other subcellular membranes, mitochondrial membranes are cholesterol-poor, particularly the inner mitochondrial membrane (IMM). As a result, steroidogenesis can be controlled through the delivery of cholesterol to the IMM, where it is converted to pregnenolone. The low basal levels of cholesterol also make mitochondria sensitive to changes in cholesterol content, which can have a relatively large impact on the biophysical and functional characteristics of mitochondrial membranes. Increased mitochondrial cholesterol levels have been observed in diverse pathological conditions including cancer, steatohepatitis, Alzheimer disease and Niemann-Pick Type C1-deficiency, and are associated with increased oxidative stress, impaired oxidative phosphorylation, and changes in the susceptibility to apoptosis, among other alterations in mitochondrial function. Mitochondria are not included in the vesicular trafficking network; therefore, cholesterol transport to mitochondria is mostly achieved through the activity of lipid transfer proteins at membrane contact sites or by cytosolic, diffusible lipid transfer proteins. Here we will give an overview of the main mechanisms involved in mitochondrial cholesterol import, focusing on the steroidogenic acute regulatory protein StAR/STARD1 and other members of the StAR-related lipid transfer (START) domain protein family, and we will discuss how changes in mitochondrial cholesterol levels can arise and affect mitochondrial function. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.

Sex-Specific Placental Responses in Fetal Development

The placenta is an ephemeral but critical organ for the survival of all eutherian mammals and marsupials. It is the primary messenger system between the mother and fetus, where communicational signals, nutrients, waste, gases, and extrinsic factors are exchanged. Although the placenta may buffer the fetus from various environmental insults, placental dysfunction might also contribute to detrimental developmental origins of adult health and disease effects. The placenta of one sex over the other might possess greater ability to respond and buffer against environmental insults. Given the potential role of the placenta in effecting the lifetime health of the offspring, it is not surprising that there has been a resurging interest in this organ, including the Human Placental Project launched by the National Institutes of Child Health and Human Development. In this review, we will compare embryological development of the laboratory mouse and human chorioallantoic placentae. Next, evidence that various species, including humans, exhibit normal sex-dependent structural and functional placental differences will be examined followed by how in utero environmental changes (nutritional state, stress, and exposure to environmental chemicals) might interact with fetal sex to affect this organ. Recent data also suggest that paternal state impacts placental function in a sex-dependent manner. The research to date linking placental maladaptive responses and later developmental origins of adult health and disease effects will be explored. Finally, we will focus on how sex chromosomes and epimutations may contribute to sex-dependent differences in placental function, the unanswered questions, and future directions that warrant further consideration.

Maternal vitamin C deficiency during pregnancy results in transient fetal and placental growth retardation in guinea pigs

PURPOSE

Recently, we reported that preferential maternal-fetal vitamin C (vitC) transport across the placenta is likely to be impaired by prolonged maternal vitC deficiency. Maintenance of a basal maternal vitC supply at the expense of the fetus may impair fetal development; however, the knowledge of vitC's impact on intrauterine development is sparse. The aim of this study was to explore the effect of maternal vitC status on fetal and placental development in guinea pigs.

METHODS

Twenty pregnant Dunkin Hartley guinea pigs were randomized into four groups to receive diets either sufficient (918 mg/kg CTRL) or deficient (100 mg/kg DEF) in vitC. Cesarean sections at gestational day (GD) 45 or 56 allowed for fetal and placental measurements.

RESULTS

At GD45, body, brain and placental weights were significantly reduced in DEF pups compared with CTRL (p < 0.05, p < 0.001 and p < 0.05, respectively). DEF plasma vitC levels were ~6% of those of CTRL (p < 0.0001), and the fetal/maternal plasma vitC ratio was significantly reduced at GD56 in the DEF animals compared with controls (p = 0.035). Placental vitC levels were reduced in DEF animals (p < 0.0001) and the ascorbate oxidation ratio and glutathione elevated compared with controls (p < 0.0001).

CONCLUSIONS

Although no clinical differences between CTRL and DEF pups were observed at GD56, the present data suggest that vitC plays a role in early fetal development. Although no clinical differences between CTRL and DEF pups were observed at GD56, the present data suggest that vitC plays a role in early fetal development. Low maternal vitC intake during pregnancy may compromise maternal weight gain, placental function and intrauterine development.

Placental steroidogenesis in pregnant women with polycystic ovary syndrome

OBJECTIVE

To evaluate the placental activity of steroid sulfatase (STS), 3β-hydroxysteroid dehydrogenase type 1 (3β-HSD-1) and P450 aromatase (P450arom) in polycystic ovarian syndrome (PCOS) compared to normal pregnant women.

DESIGN

Twenty pregnant women with PCOS and 30 control pregnant women who delivered at term were studied. Samples of placental tissue and cord blood were obtained after delivery. A maternal blood sample was obtained during the 34th week of gestation. In placental tissue, the activities of STS, 3β-HSD-1 and P450arom were evaluated. In the blood samples, progesterone, DHEAS, DHEA, androstenedione, testosterone, estrone, estradiol and total estriol were determined.

RESULT

In placental tissue from women with PCOS, higher 3β-HSD-1 and lower P450 aromatase activities were observed compared to control women. Moreover, women with PCOS showed higher androstenedione and testosterone concentrations compared to normal pregnant women (p=0.016 and p=0.025, respectively). In cord blood, female newborns of women with PCOS exhibited lower androstenedione and higher estriol concentrations compared to daughters of control women (p=0.038; p=0.031, respectively).

CONCLUSION

These data suggest that placental tissue from women with PCOS shows changes in the activities of two important enzymes for steroid synthesis, higher 3β-HSD-1 and lower P450, which could increase androgen production during pregnancy.

Drosophila CYP6g1 and its human homolog CYP3A4 confer tolerance to methylmercury during development

Methylmercury (MeHg) is a persistent environmental toxicant that is commonly encountered through dietary fish and seafood. While the fetal nervous system is a well-known primary target for MeHg toxicity, the risks of MeHg exposures that are commonly experienced today through diet and environmental exposure remain uncertain. Despite knowledge of numerous cellular processes that are affected by MeHg, the mechanisms that ultimately influence tolerance or susceptibility to MeHg in the developing fetus are not well understood. Using transcriptomic analyses of developing brains of MeHg tolerant and susceptible strains of Drosophila, we previously identified members of the cytochrome p450 (CYP) family of monooxygenases/oxidoreductases as candidate MeHg tolerance genes. While CYP genes encode Phase I enzymes best known for xenobiotic metabolism in the liver, several classes of CYPs are required for synthesis or degradation of essential endobiotics, such as hormones and fatty acids, that are critical to normal development. We now demonstrate that variation in expression CYP genes can strongly influence MeHg tolerance in the developing fly. Importantly, modulating expression of a single CYP, CYP6g1, specifically in neurons or the fat body (liver equivalent) is sufficient to rescue development in the presence of MeHg. We also demonstrate a conserved function for CYP3A4, a human homolog of CYP6g1, in conferring MeHg tolerance to flies. Finally, we show that pharmacological induction of CYPs with caffeine parallels an increase in tolerance to MeHg in developing flies. These findings establish a previously unidentified role for CYPs in MeHg toxicity and point to a potentially conserved role of CYP genes to influence susceptibility to MeHg toxicity across species.