Review: Transport of maternal cholesterol to the fetal circulation

Multiple functions of syncytiotrophoblast mitochondria

The human placenta plays a central role in pregnancy, and the syncytiotrophoblast cells are the main components of the placenta that support the relationship between the mother and fetus, in apart through the production of progesterone. In this review, the metabolic processes performed by syncytiotrophoblast mitochondria associated with placental steroidogenesis are described. The metabolism of cholesterol, specifically how this steroid hormone precursor reaches the mitochondria, and its transformation into progesterone are reviewed. The role of nucleotides in steroidogenesis, as well as the mechanisms associated with signal transduction through protein phosphorylation and dephosphorylation of proteins is discussed. Finally, topics that require further research are identified, including the need for new techniques to study the syncytiotrophoblast in situ using non-invasive methods.

A compendium of expression patterns of cholesterol biosynthetic enzymes in the mouse embryo

Cholesterol and its biosynthetic pathway intermediates and derivatives are required for many developmental processes including membrane biogenesis, transmembrane receptor signaling, steroid biogenesis, nuclear receptor activation, and posttranslational modification of hedgehog (Hh) proteins. To perform such multifaceted tasks depends on stringent regulation of expression of cholesterol biosynthetic enzymes (CBEs). We established for a whole organism, for the first time, the 3D expression pattern of all genes required for cholesterol biosynthesis (CBS), starting from acetyl-CoA and ending with cholesterol. This data was produced by high-throughput in situ hybridization on serial sections through the mouse fetus. The textually annotated image data were seamlessly integrated into the METscout and GenePaint public databases. This novel information helps in the understanding of why CBEs are expressed at particular locations within the fetus. For example, strong CBE expression is detected at sites of cell proliferation and also where cell growth increases membrane surface, such as in neurons sprouting axons and forming synapses. The CBE data also sheds light on the spatial relationship of cells and tissue that express sonic Hh (Shh) and produce cholesterol, respectively. We discovered that not all cells expressing Shh are capable of CBS. This finding suggests novel ways by which cholesterylation of Shh is regulated.

Early life lipid profile and metabolic programming in very young children

BACKGROUND AND AIMS

Lipid derangements during early postnatal life may induce stable epigenetic changes and alter metabolic programming. We investigated associations between serum lipid profiles in very young children and DNA methylation of tumor necrosis factor-alpha (TNFα) and leptin (LEP). Secondly, we explored if the maternal serum lipid profile modifies DNA methylation in the child.

METHODS AND RESULTS

In 120 healthy children at 17 months of age, DNA methylation of TNFα and LEP was measured in DNA derived from whole blood. Linear mixed models were used to calculate exposure-specific differences and associations. Total cholesterol in children was associated with decreased methylation of TNFα (-5.8%, p = 0.036), and HDL-cholesterol was associated with decreased methylation of both TNFα (-6.9%, p = 0.013) and LEP (-3.4%, p = 0.021). Additional adjustment for gestational age at birth, birth weight, sex, breastfeeding and educational level attenuated the effects, TNFα (-6.1%, p = 0.058) and LEP (-3.1%, p = 0.041). In mothers, HDL-cholesterol only was associated with decreased methylation of TNFα in the child (-8.7%, p = 0.001).

CONCLUSION

Our data support the developmental origin of health and disease hypothesis by showing that total cholesterol and HDL-cholesterol levels in very young children are associated with epigenetic metabolic programming, which may affect their vulnerability for developing cardiovascular diseases in later life.

Influence of altered maternal lipid profile on the lipid profile of the newborn

OBJECTIVE

To evaluate whether there is an association between altered maternal lipid profile and the lipid profile of the newborn in a maternity hospital.

SUBJECTS AND METHOD

Cross-sectional study with 435 parturients and their respective newborns. Blood samples from the newborns were collected during delivery by venipuncture of the umbilical cord close to the placenta. Blood samples from the parturients were collected in the pre-delivery room or right after delivery. The concentrations of total cholesterol, triglycerides and HDL-c were determined by an enzymatic colorimetric method and LDL-c was calculated by the Friedewald formula.

RESULTS

There was no significant difference in mean concentrations of total cholesterol, LDL-c, HDL-c and triglycerides in neonates according to altered or non-altered maternal total cholesterol, LDL-c, HDL-c and triglycerides.

CONCLUSIONS

Change in maternal lipid profile is not significantly associated with the mean concentrations of total cholesterol, LDL-c, HDL-c and triglycerides in newborns.

Loss of inherited genomic imprints in mice leads to severe disruption in placental lipid metabolism

INTRODUCTION

Monoallelic expression of imprinted genes is necessary for placental development and normal fetal growth. Differentially methylated domains (DMDs) largely determine the parental-specific monoallelic expression of imprinted genes. Maternally derived DNA (cytosine-5-) -methyltransferase 1o (DNMT1o) maintains DMDs during the eight-cell stage of development. DNMT1o-deficient mouse placentas have a generalized disruption of genomic imprints. Previous studies have demonstrated that DNMT1o deficiency alters placental morphology and broadens the embryonic weight distribution in late gestation. Lipids are critical for fetal growth. Thus, we assessed the impact of disrupted imprinting on placental lipids.

METHODS

Lipids were quantified from DNMT1o-deficient mouse placentas and embryos at E17.5 using a modified Folch method. Expression of select genes critical for lipid metabolism was quantified with RT-qPCR. Mitochondrial morphology was assessed by TEM and mitochondrial aconitase and cytoplasmic citrate concentrations quantified. DMD methylation was determined by EpiTYPER.

RESULTS

We found that DNMT1o deficiency is associated with increased placental triacylglycerol levels. Neither fetal triacylglycerol concentrations nor expression of select genes that mediate placental lipid transport were different from wild type. Placental triacylglycerol accumulation was associated with impaired beta-oxidation and abnormal citrate metabolism with decreased mitochondrial aconitase activity and increased cytoplasmic citrate concentrations. Loss of methylation at the MEST DMD was strongly associated with placental triacylglycerol accumulation.

DISCUSSION

A generalized disruption of genomic imprints leads to triacylglycerol accumulation and abnormal mitochondrial function. This could stem directly from a loss of methylation at a given DMD, such as MEST, or represent a consequence of abnormal placental development.

Estrogen enhances secretion of apolipoprotein B-100 containing lipoproteins by BeWo cells

Although the early human embryo is capable of covering its cholesterol demand by endogenous synthesis, during later stages of development the fetus may become dependent on transplacental cholesterol transport. On one hand, this conclusion is based on the severe developmental abnormalities of embryos with mutations in the gene specifying the enzyme catalyzing the last step of cholesterol synthesis, 7-dehydrocholesterol reductase, causing Smith-Lemli-Opitz Syndrome. On the other hand, increased total maternal plasma cholesterol levels may reflect the requirement by the growing fetus and/or the placenta for cholesterol. Various molecules and complexes must cross the placental barrier consisting of trophoblasts and fetal endothelial cells to reach the fetal circulation. The de novo synthesis of apolipoprotein B (apoB)-containing lipoproteins coupled to secretion from trophoblasts towards the fetal side is one efficient pathway for cholesterol supply. ApoB and the microsomal triglyceride transfer protein (MTP) are essential components for the assembly of apoB-containing lipoproteins. The aim of this study was to evaluate functional properties of the human placental cell line BeWo as an in vitro model for placental synthesis of apoB-containing lipoproteins by focusing on components required for lipoprotein assembly and secretion. We demonstrate mRNA and protein production of apoB-100, MTP, and protein disulfide isomerase (PDI) in BeWo cells. In addition, metabolic radiolabeling and apoB-immunoprecipitation of cell extracts and media revealed that synthesis and secretion of apoB-containing lipoproteins are enhanced by estrogen. The expression of apoB-100, MTP, and PDI, and the estrogen-stimulated lipoprotein secretion by BeWo cells suggest that these cells are a useful system to study aspects of lipoprotein metabolism at the placental barrier.

Maternal-fetal nutrient transport in pregnancy pathologies: the role of the placenta

Appropriate in utero growth is essential for offspring development and is a critical contributor to long-term health. Fetal growth is largely dictated by the availability of nutrients in maternal circulation and the ability of these nutrients to be transported into fetal circulation via the placenta. Substrate flux across placental gradients is dependent on the accessibility and activity of nutrient-specific transporters. Changes in the expression and activity of these transporters is implicated in cases of restricted and excessive fetal growth, and may represent a control mechanism by which fetal growth rate attempts to match availability of nutrients in maternal circulation. This review provides an overview of placenta nutrient transport with an emphasis on macro-nutrient transporters. It highlights the changes in expression and activity of these transporters associated with common pregnancy pathologies, including intrauterine growth restriction, macrosomia, diabetes and obesity, as well as the potential impact of maternal diet. Molecular signaling pathways linking maternal nutrient availability and placenta nutrient transport are discussed. How sexual dimorphism affects fetal growth strategies and the placenta’s response to an altered intrauterine environment is considered. Further knowledge in this area may be the first step in the development of targeted interventions to help optimize fetal growth.

Placental lipases in pregnancies complicated by gestational diabetes mellitus (GDM)

Infants of women with gestational diabetes mellitus (GDM) are more likely to be born large for gestational age with a higher percentage body fat. Elevated maternal lipids may contribute to this. Placental lipases such as lipoprotein lipase (LPL), endothelial lipase (EL) and hormone sensitive lipase (HSL) are involved in transferring lipids from mother to fetus. Previous studies of expression of these lipases in placentae in women with diabetes in pregnancy have reported divergent results. Intracellular lipases such as adipose triglyceride lipase (ATGL), and HSL are central to lipid droplet metabolism. The activities of these lipases are both influenced by Perilipin 1, and ATGL is also activated by a co-factor comparative gene identification-58 (CGI-58) and inhibited by G₀/G₁ switch gene 2 (GS02). None of these modifying factors or ATGL have been examined previously in placenta. The purpose of this study was therefore to examine the expression of ATGL, HSL, LPL, EL, as well as Perilipin 1, GS02 and CGI-58 in term pregnancies complicated by GDM. mRNA and protein expression of the lipases were measured in placentae from 17 women with GDM and 17 normoglycaemic pregnancies, matched for maternal BMI and gestational age of delivery. ATGL mRNA expression was increased and HSL mRNA expression reduced in placentae from GDM although there was no differences in protein expression of any of the lipases. All lipases were localised to trophoblasts and endothelial cells. The expression of Perilipin 1 and CGI-58 mRNA was increased and GS02 not altered in GDM. These results suggest that there is no difference in expression in these four lipases between GDM and normoglycaemic placentae, and therefore altered lipid transfer via these lipases does not contribute to large for gestational age in infants of women with GDM.

Normalizing metabolism in diabetic pregnancy: is it time to target lipids?

Outcomes in pregnancies complicated by preexisting diabetes (type 1 and type 2) and gestational diabetes mellitus have improved, but there is still excess morbidity compared with normal pregnancy. Management strategies appropriately focus on maternal glycemia, which demonstrably improves pregnancy outcomes for mother and infant. However, we may be reaching the boundaries of obtainable glycemic control for many women. It has been acknowledged that maternal lipids are important in pregnancies complicated by diabetes. Elevated maternal lipids are associated with preeclampsia, preterm delivery, and large-for-gestational-age infants. Despite this understanding, assessment of management strategies targeting maternal lipids has been neglected to date. Consideration needs to be given to whether normalizing maternal lipids would further improve pregnancy outcomes. This review examines the dyslipidemia associated with pregnancy complicated by diabetes, reviews possible therapies, and considers whether it is time to start actively managing this aspect of maternal metabolism.

Therapeutic potential of statins and the induction of heme oxygenase-1 in preeclampsia

Heme oxygenase (Hmox) is an endogenous system that offers protection against placental cytotoxic damage associated with preeclampsia. The Hmox1/carbon monoxide (CO) pathway inhibits soluble Flt-1 (sFlt-1) and soluble Endoglin (sEng). More importantly, statins induce Hmox1 and suppress the release of sFlt-1 and sEng; thus, statins and Hmox1 activators are potential novel therapeutic agents for treating preeclampsia. The contribution of the Hmox system to the pathogenesis of preeclampsia has been further indicated by the incidence of preeclampsia being reduced by a third in smokers, who had reduced levels of circulating sFlt-1. Interestingly, preeclamptic women exhale less CO compared with women with healthy pregnancies. Hmox1 is reduced prior to the increase in sFlt-1 as Hmox1 mRNA expression in the trophoblast is decreased in the first trimester in women who go on to develop preeclampsia. Induction of Hmox1 or exposure to CO or bilirubin has been shown to inhibit the release of sFlt-1 and sEng in animal models of preeclampsia. The functional benefit of statins and Hmox1 induction in women with preeclampsia is valid not only because they inhibit sFlt-1 release, but also because statins and Hmox1 are associated with anti-apoptotic, anti-inflammatory, and anti-oxidant properties. The StAmP trial is the first randomized control trial (RCT) evaluating the use of pravastatin to ameliorate severe preeclampsia. This proof-of-concept study will pave the way for future global RCT, the success of which will greatly contribute to achieving the United Nations Millennium Development Goals (MDG4 and MDG5) and offering an affordable and easily accessible therapy for preeclampsia.

Polymorphisms of CYP51A1 from cholesterol synthesis: associations with birth weight and maternal lipid levels and impact on CYP51 protein structure

We investigated the housekeeping cytochrome P450 CYP51A1 encoding lanosterol 14α-demethylase from cholesterol synthesis that was so far not directly linked to human disorders. By direct sequencing of CYP51A1 in 188 women with spontaneous preterm delivery and 188 unrelated preterm infants (gestational age <37 weeks) we identified 22 variants where 10 are novel and rare. In infants there were two novel CYP51A1 variants where damaging effects of p.Tyr145Asp from the substrate recognition region, but not p.Asn193Asp, were predicted by PolyPhen2 and SIFT. This was confirmed by molecular modeling showing that Tyr145Asp substitution results in changed electrostatic potential of the CYP51 protein surface and lengthened distance to the heme which prevents hydrogen bonding. The CYP51 Tyr145Asp mutation is rare and thus very interesting for further structure/function relationship studies. From the 12 identified known variants rs6465348 was chosen for family based association studies due to its high minor allele frequency. Interestingly, this CYP51A1 common variant associates with small for gestational age weight in newborns (p = 0.028) and lower blood total cholesterol and low density lipoprotein cholesterol levels in mothers in 2nd trimester of pregnancy (p = 0.042 and p = 0.046 respectively). Our results indicate a new link between a cholesterol synthesis gene CYP51A1 and pregnancy pathologies.

BMI of the firstborn offspring at age 12 reflects maternal LDL and HDL cholesterol levels at term pregnancy and postpartum

OBJECTIVE

The aim of this study was to assess the relationship between the body mass index (BMI) of the firstborn offspring at age 12 and maternal lipid levels at term and at 6 months postpartum.

DESIGN AND METHODS

The study included children born in the 2nd Department of Obstetrics and Gynecology of the Medical University of Warsaw between 1 November 1991 and 31 May 1993. The end point was BMI in the upper quartile - considered high BMI of the firstborn offspring at age 12.

RESULTS

The risk of high BMI in the offspring at age 12 significantly increased with an increase in the LDL-C level at term (OR = 2.41 per SD increase, 95% CI: 1.01-5.80; p < 0.049), a decrease in the HDL-C% at term (OR = 0.35 per SD increase, 95% CI: 0.14-0.84; p < 0.019) and a decrease in the HDL-C level at 6 months postpartum (OR = 0.25 per SD increase, 95% CI: 0.08-0.82; p < 0.022), regardless of maternal weight status before pregnancy and at 6 months postpartum, gestational weight gain, the offspring's gender and birth weight.

CONCLUSION

LDL and HDL cholesterol levels at term are markers of maternal adaptation to a first pregnancy and predict the future growth of firstborn offspring.

Diet reduction to requirements in obese/overfed ewes from early gestation prevents glucose/insulin dysregulation and returns fetal adiposity and organ development to control levels

Obesity at conception and excess gestational weight gain pose significant risks for adverse health consequences in human offspring. This study evaluated the effects of reducing dietary intake of obese/overfed ewes beginning in early gestation on fetal development. Sixty days prior to conception, ewes were assigned to a control diet [CON: 100% of National Research Council (NRC) recommendations], a diet inducing maternal obesity (MO: 150% of NRC recommendations), or a maternal obesity intervention diet (MOI: 150% of NRC recommendations to day 28 of gestation, then 100% NRC) until necropsy at midgestation (day 75) or late (day 135) gestation. Fetal size and weight, as well as fetal organ weights, were greater (P < 0.05) at midgestation in MO ewes than those of CON and MOI ewes. By late gestation, whereas fetal size and weight did not differ among dietary groups, cardiac ventricular weights and wall thicknesses as well as liver and perirenal fat weights remained elevated in fetuses from MO ewes compared with those from CON and MOI ewes. MO ewes and fetuses exhibited elevated (P < 0.05) plasma concentrations of triglycerides, cholesterol, insulin, glucose, and cortisol at midgestation compared with CON and MOI ewes and fetuses. In late gestation, whereas plasma triglycerides and cholesterol, insulin, and cortisol remained elevated in MO vs. CON and MOI ewes and fetuses, glucose concentrations were elevated in both MO and MOI fetuses compared with CON fetuses, which was associated with elevated placental GLUT3 expression in both groups. These data are consistent with the concept that reducing maternal diet of obese/overfed ewes to requirements from early gestation can prevent subsequent alterations in fetal growth, adiposity, and glucose/insulin dynamics.

Boots for Achilles: progesterone's reduction of cholesterol is a second-order adaptation

Progesterone and cholesterol are both vital to pregnancy. Among other functions, progesterone downregulates inflammatory responses, allowing for maternal immune tolerance of the fetal allograft. Cholesterol a key component of cell membranes, is important in intracellular transport, cell signaling, nerve conduction, and metabolism Despite the importance of each substance in pregnancy, one exercises an antagonistic effect on the other, as periods of peak progesterone correspond with reductions in cholesterol availability, a consequence of progesterone's negative effects on cholesterol biosynthesis. This arrangement is understandable in light of the threat posed by pathogens early in pregnancy. Progesterone-induced immunomodulation entails increased vulnerability to infection, an acute problem in the first trimester, when fetal development is highly susceptible to insult. Many pathogens rely on cholesterol for cell entry, egress, and replication. Progesterone's antagonistic effects on cholesterol thus partially compensate for the costs entailed by progesterone-induced immunomodulation. Among pathogens to which the host's vulnerability is increased by progesterone's effects, approximately 90% utilize cholesterol, and this is notably true of pathogens that pose a risk during pregnancy. In addition to having a number of possible clinical applications, our approach highlights the potential importance of second-order adaptations, themselves a consequence of the lack of teleology in evolutionary processes.

Sex and breed-dependent organ development and metabolic responses in foetuses from lean and obese/leptin resistant swine

The present study aimed to determine the effects of breed and sex on growth patterns and metabolic features of advanced-pregnancy foetuses exposed to the same environmental conditions. Thus, at Day 62 of pregnancy, swine foetuses from an obese breed with leptin resistance (Iberian breed) were compared to lean crossbred foetuses (25% Large White ×25% Landrace ×50% Pietrain). There were differential developmental patterns in foetuses with leptin resistance, mainly a higher relative weight of the brain resembling “brain-sparing effect”. Prioritization of brain growth may be protective for the adequate growth and postnatal survival of the Iberian individuals, an ancient breed reared in extensive semi-feral conditions for centuries. There were also clear sex-related differences in foetal development and metabolism in the Iberian breed. Female Iberian foetuses were similar in size and weight to male littermates but had a significantly higher relative liver to body weight ratio resembling “liver-sparing effect” and a trend for a higher relative intestine to body ratio. Moreover, the availability of triglycerides, cholesterol and IL-6 in female Iberian foetuses was similar to that of lean crossbred foetuses. Overall, these features may favour a better postnatal survival and development of females, the sex more critical for the species survival. These findings set the basis for future translational studies aimed at increasing the knowledge on the interaction between genetic and environmental factors in the early programming of the adult phenotype.

Placental ABCA1 and ABCG1 expression in gestational disease: Pre-eclampsia affects ABCA1 levels in syncytiotrophoblasts

INTRODUCTION

Transplacental feto-maternal lipid exchange through the ATP-binding cassette transporters ABCA1 and ABCG1 is important for normal fetal development. However, only scarce and conflicting data exist on the involvement of these transporters in gestational disease.

METHODS

Placenta samples (n = 72) derived from common gestational diseases, including pre-eclampsia (PE), HELLP, intrauterine growth restriction (IUGR), intrahepatic cholestasis of pregnancy and gestational diabetes, were assessed for their ABCA1 and ABCG1 expression levels and compared to age-matched control placentas with qRT-PCR and immunohistochemistry. ABCA1 expression was additionally investigated with immunoblot in placental membrane vesicles. Furthermore, placental cholesterol and phospholipid contents were assessed.

RESULTS

ABCA1 mRNA levels differed significantly between preterm and term control placentas (p = 0.0013). They were down-regulated in isolated PE and PE with IUGR (p = 0.0006 and p = 0.0012, respectively), but unchanged in isolated IUGR, isolated HELLP and other gestational diseases compared to gestational age-matched controls. Correspondingly, in PE, ABCA1 protein expression was significantly reduced in the apical membrane of the villous syncytiotrophoblast (p = 0.011) and in villous fetal endothelial cells (p = 0.036). Furthermore, in PE there was a significant increase in the placental content of total and individual classes of phospholipids which were partially correlated with diminished ABCA1 expression. Conversely, ABCG1 mRNA and protein levels were stable in the investigated conditions.

CONCLUSIONS

In gestational disease, there is a specific down-regulation of placental ABCA1 expression at sites of feto-maternal lipid exchange in PE. At a functional level, the increase in placental lipid concentrations provides indirect evidence of an impaired transport capacity of ABCA1 in this disease.

Emerging roles for LXRs and LRH-1 in female reproduction

Nutritional status is known to control female reproductive physiology. Many reproductive pathologies such as anorexia nervosa, dystocia and preeclampsia, have been linked to body mass index and to metabolic syndrome. Lipid metabolism has also been associated with ovarian, uterine and placental functions. Among the regulators of lipid homeostasis, the Liver X Receptors (LXRs) and the Liver Receptor Homolog-1 (LRH-1), two members of the nuclear receptor superfamily, play a central role. LXRs are sensitive to intracellular cholesterol concentration and decrease plasma cholesterol, allowing to considering them as "cholesterol sensors". LRH-1 shares many target-genes with LXRs and has been considered for a long time as a real orphan nuclear receptor, but recent findings showed that phospholipids are ligands for this nuclear receptor. Acting in concert, LXRs and LRH-1 could thus be sensitive to slight modifications in cellular lipid balance, tightly maintaining their cellular concentrations. These last years, the use of transgenic mice clarified the roles of these nuclear receptors in many physiological functions. This review will be focused on the roles of LXRs and LRH-1 on female reproduction. Their contribution to ovarian endocrine and exocrine functions, as well as uterine and placental physiology will be discussed. The future challenge will thus be to target these nuclear receptors to prevent lipid-associated reproductive diseases in women.

Maternal lipid profile during early pregnancy and pregnancy complications and outcomes: the ABCD study

CONTEXT

Elevated lipid levels during late pregnancy are associated with complications and adverse outcome for both mother and newborn. However, it is inconclusive whether a disturbed lipid profile during early pregnancy has similar negative associations.

OBJECTIVE

Our objective was to investigate whether nonfasting maternal total cholesterol and triglyceride levels during early pregnancy are associated with six major adverse pregnancy outcomes.

METHODS

Data were derived from the Amsterdam Born Children and Their Development (ABCD) cohort study. Random blood samples of nonfasting total cholesterol and triglyceride levels were determined during early gestation (median = 13, interquartile range = 12-14 wk). Outcome measures were pregnancy-induced hypertension (PIH), preeclampsia, preterm birth, small/large for gestational age (SGA/LGA), and child loss. Only nondiabetic women with singleton deliveries were included; the baseline sample consisted of 4008 women. Analysis for PIH and preeclampsia were performed in nulliparous women only (n = 2037).

RESULTS

Mean (sd) triglyceride and total cholesterol levels were 1.33 (0.55) and 4.98 (0.87) mmol/liter, respectively. The incidence of pregnancy complications and perinatal outcomes were as follows: PIH, 4.9%; preeclampsia, 3.7%; preterm birth, 5.3%; SGA, 9.3%; LGA, 9.3%; and child loss, 1.4%. After adjustments, every unit increase in triglycerides was linearly associated with an increased risk of PIH [odds ratio (OR) = 1.60, P = 0.021], preeclampsia (OR = 1.69, P = 0.018), LGA (OR = 1.48, P < 0.001), and induced preterm delivery (OR = 1.69, P = 0.006). No associations were found for SGA or child loss. Total cholesterol was not associated with any of the outcome measures.

CONCLUSIONS

Elevated maternal triglyceride levels measured during early pregnancy are associated with pregnancy complications and adverse pregnancy outcomes. These results suggest that future lifestyle programs in women of reproductive age with a focus on lowering triglyceride levels (i.e. diet, weight reduction, and physical activity) may help to prevent hypertensive complications during pregnancy and adverse birth outcomes.

Treatment of Smith-Lemli-Opitz syndrome and other sterol disorders

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive genetic condition with a broad phenotype that results from deficiency of the final enzyme of the cholesterol synthesis pathway. This defect causes low or low-normal plasma cholesterol levels and increased 7- and 8-dehydrocholesterol (DHC) levels. Many therapies for SLOS and other disorders of sterol metabolism have been proposed, and a few of them have been undertaken in selected patients, but robust prospective clinical trials with validated outcome measures are lacking. We review the current literature and expert opinion on treatments for SLOS and other selected sterol disorders, including dietary cholesterol therapy, statin treatment, bile acid supplementation, medical therapies, and surgical interventions, as well as directions for future therapies and treatment research.

The origin of fetal sterols in second-trimester amniotic fluid: endogenous synthesis or maternal-fetal transport?

OBJECTIVE

Cholesterol is crucial for fetal development. To gain more insight into the origin of the fetal cholesterol pool in early human pregnancy, we determined cholesterol and its precursors in the amniotic fluid of uncomplicated, singleton human pregnancies.

STUDY DESIGN

Total sterols were characterized by gas chromatography-mass spectrometry in the second-trimester amniotic fluid of 126 healthy fetuses from week 15 until week 22.

RESULTS

The markers of cholesterol biosynthesis, lanosterol, dihydrolanosterol, and lathosterol, were present in low levels until the 19th week of gestation, after which their levels increased strongly. β-sitosterol, a marker for maternal-fetal cholesterol transport, was detectable in the amniotic fluid. The total cholesterol levels increased slightly between weeks 15 and 22.

CONCLUSION

Our results support the hypothesis that during early life the fetus depends on maternal cholesterol supply because endogenous synthesis is relatively low. Therefore, maternal cholesterol can play a crucial role in fetal development.

β-Carotene supplementation decreases placental transcription of LDL receptor-related protein 1 in wild-type mice and stimulates placental β-carotene uptake in marginally vitamin A-deficient mice

The human diet contains β-carotene as the most abundant precursor of vitamin A, an essential nutrient for embryogenesis. Our laboratory previously showed the importance of β-carotene metabolism via β-carotene-15,15'-oxygenase (CMOI) to support mouse embryonic development. However, the mechanisms regulating embryonic acquisition and utilization of β-carotene from the maternal circulation via placenta remain unknown. We used wild-type (WT) and Lrat(-/-)Rbp(-/-) (L(-/-)R(-/-)) mice, the latter being a model of marginal vitamin A deficiency. Pregnant dams, fed a nonpurified diet sufficient in vitamin A throughout life, were i.p. supplemented with β-carotene or vehicle at 13.5 d postcoitum (dpc). Effects of this acute maternal supplementation on retinoid and β-carotene metabolism in maternal (serum, liver) and developing tissues (placenta, yolk sac, embryo) were investigated at 14.5 dpc. We showed that, upon supplementation, placental β-carotene concentrations were greater in L(-/-)R(-/-) than in WT mice. However, the retinoid (retinol and retinyl ester) concentrations remained unchanged in placenta (and in all other tissues analyzed) of both genotypes upon β-carotene administration. We also showed that upon a single i.p. β-carotene supplementation, placental LDL receptor-related protein (Lrp1) mRNA expression was lower in WT mice, and embryonic CmoI mRNA expression was greater in L(-/-)R(-/-) mice. Together, these data suggest a potential role of LRP1 in mediating the uptake of β-carotene across the placenta and that even a marginally impaired maternal vitamin A status may influence uptake and utilization of β-carotene by the placenta and the embryo.

Comparison of the metabolic parameters and androgen level of umbilical cord blood in newborns of mothers with polycystic ovary syndrome and controls

BACKGROUND

This study aimed to assess the metabolic parameters and androgen concentration in the cord blood of newborns of mothers with polycystic ovary syndrome (PCOS) in comparison with controls.

MATERIALS AND METHODS

This cross-sectional study was conducted in 2010-2011 in Isfahan, Iran. Biochemical tests were conducted on 40 infants, born from singleton pregnancies in women with PCOS and an equal number of controls.

RESULTS

The mean weight gain during pregnancy was higher in women with PCOS than in controls (16.02 ± 4.39 vs. 9.10 ± 2.20 kg, respectively, P < 0.0001). The mean birth weight was lower in newborns of mothers with PCOS than in controls (2905.25 ± 415.59 vs. 3223.25 ± 425.02 vs. grams, respectively, P = 0.001). The mean testosterone was higher in cord blood of newborns of PCOS women than in controls (5.58 ± 3.20 vs. 2.28 ± 0.62 pg/ml, P < 0.0001). Triglycerides and LDL-C were lower in cord blood of newborns, born from PCOS women than in controls (P = 0.001). The birth weight of the newborns of PCOS mothers was negatively correlated to free testosterone of cord blood (R = -0. 26, P = 0.04).

CONCLUSION

The metabolic aberration in PCOS might influence fetal birth weight and cord blood lipid profile. These disorders may be caused by an exposure to elevated testosterone level during fetal life. The offspring of PCOS women may be at higher risk for chronic diseases in later life. The clinical impact of our findings should be confirmed in future longitudinal studies.

Fetoplacental vascular endothelial dysfunction as an early phenomenon in the programming of human adult diseases in subjects born from gestational diabetes mellitus or obesity in pregnancy

Gestational diabetes mellitus (GDM) and obesity in pregnancy (OP) are pathological conditions associated with placenta vascular dysfunction coursing with metabolic changes at the fetoplacental microvascular and macrovascular endothelium. These alterations are seen as abnormal expression and activity of the cationic amino acid transporters and endothelial nitric oxide synthase isoform, that is, the "endothelial L-arginine/nitric oxide signalling pathway." Several studies suggest that the endogenous nucleoside adenosine along with insulin, and potentially arginases, are factors involved in GDM-, but much less information regards their role in OP-associated placental vascular alterations. There is convincing evidence that GDM and OP prone placental endothelium to an "altered metabolic state" leading to fetal programming evidenced at birth, a phenomenon associated with future development of chronic diseases. In this paper it is suggested that this pathological state could be considered as a metabolic marker that could predict occurrence of diseases in adulthood, such as cardiovascular disease, obesity, diabetes mellitus (including gestational diabetes), and metabolic syndrome.

Effects of pravastatin on mediators of vascular function in a mouse model of soluble Fms-like tyrosine kinase-1-induced preeclampsia

OBJECTIVE

We sought to investigate the mechanisms of action by which pravastatin improves vascular reactivity in a mouse model of preeclampsia induced by overexpression of soluble Fms-like tyrosine kinase-1 (sFlt)-1.

STUDY DESIGN

Pregnant CD-1 mice were randomly allocated to tail vein injection with adenovirus carrying sFlt-1 or murine immunoglobulin G2 Fc (control), and thereafter to receive pravastatin (5 mg/kg/d) or water. Mice were sacrificed at gestational day 18. Protein expression of endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor receptor-1, and hemeoxygenase-1 were assayed by Western blot in aorta, liver, and kidneys. Serum total cholesterol concentrations were measured.

RESULTS

Pravastatin up-regulated eNOS expression in the aorta of sFlt-1 mice by nearly 2-fold (P = .005) to levels similar to control mice. Total cholesterol levels, vascular endothelial growth factor receptor-1, and hemeoxygenase-1 protein expression were similar across groups.

CONCLUSION

Pravastatin prevents vascular dysfunction in part by up-regulation of eNOS in the vasculature. Our data support a role for statins in preeclampsia prevention.