Maternal cholesterol in fetal development: transport of cholesterol from the maternal to the fetal circulation

A Non-Coronary, Peripheral Arterial Atherosclerotic Disease (Carotid, Renal, Lower Limb) in Elderly Patients-A Review: Part I-Epidemiology, Risk Factors, and Atherosclerosis-Related Diversities in Elderly Patients

Atherosclerosis is a generalized and progressive disease. Ageing is a key risk factor for atherosclerosis progression that is associated with the increased incidence of ischemic events in supplied organs, including stroke, coronary events, limb ischemia, or renal failure. Cardiovascular disease is the leading cause of death and major disability in adults ≥ 75 years of age. Atherosclerotic occlusive disease affects everyday activity and quality of life, and it is associated with reduced life expectancy. Although there is evidence on coronary artery disease management in the elderly, there is insufficient data on the management in older patients presented with atherosclerotic lesions outside the coronary territory. Despite this, trials and observational studies systematically exclude older patients, particularly those with severe comorbidities, physical or cognitive dysfunctions, frailty, or residence in a nursing home. This results in serious critical gaps in knowledge and a lack of guidance on the appropriate medical treatment and referral for endovascular or surgical interventions. Therefore, we attempted to gather data on the prevalence, risk factors, and management strategies in patients with extra-coronary atherosclerotic lesions.

Role of paralogs in the sex-bias transcriptional and metabolic regulation of the brain-placental axis in mice

INTRODUCTION

Duplicated genes or paralogs play important roles in the adaptive function of eukaryotic genomes. Animal studies have shown evidence for the functional role of paralogs in pregnancy, but our knowledge about the role of paralogs in the fetoplacental regulation remains limited. In particular, if fetoplacental metabolic regulation is modulated by differential expression of paralogs remains unexamined.

METHODS

In this study, gene expression profiles of day-15 placenta and fetal brain were compared to identify families or groups of paralogous genes expressed in the placenta and brain of male versus female fetuses in mice. A Bayesian modeling was applied to infer directional relationship of transcriptional variation of the paralogs relative to the phylogenetic variation of the genes in each family. Gas chromatography-mass spectrometry (GC-MS) was used to perform untargeted metabolomics analysis of day-15 placenta and fetal brain of both sexes.

RESULTS

We identified paralog groups that were expressed in a sex and/or tissue biased manner between the placenta and fetal brain. Bayesian modeling showed evidence for directional relationship between expression and phylogeny of specific paralogs. These relationships were sex specific. GC-MS analysis identified metabolites that were expressed in a sex-bias manner between the placenta and fetal brain. By performing integrative analysis of the metabolomics and gene expression data, we showed that specific groups of metabolites and paralogous genes were expressed in a coordinated manner between the placenta and fetal brain.

DISCUSSION

The findings of this study collectively suggest that paralogs play an influential role in the regulation of the brain-placental axis in mice.

Feto-maternal cholesterol transport regulated by β-Klotho-FGF15 axis is essential for fetal growth

β-Klotho (β-KL) is indispensable to regulate lipid, glucose, and energy metabolism in adult animals. β-KL is highly expressed in the yolk sac, but its role in the developmental stages has not been established. We hypothesized that β-KL is required for metabolic regulation in the embryo and aimed to clarify the role of β-KL during development. Here, we show that β-KL regulates feto-maternal cholesterol transport through the yolk sac by mediating FGF 15 signaling, and also that impairment of the β-KL-FGF15 axis causes fetal growth restriction (FGR). Embryos of β- kl knockout (β-kl-/-) mice were morphologically normal but exhibited FGR before placental maturation. The body weight of β-kl-/- mice remained lower after birth. β-KL deletion reduced cholesterol supply from the maternal blood and led to lipid shortage in the embryos. These phenotypes were similar to those of embryos lacking FGF15, indicating that β-KL-FGF15 axis is essential for growth and lipid regulation in the embryonic stages. Our findings suggest that lipid abnormalities in early gestation provoke FGR, leading to reduced body size in later life.

Maternal triglyceride levels and neonatal outcomes: The Japan Environment and Children's Study

BACKGROUND

Although maternal triglyceride (TG) is important for fetal growth, there are few large cohort studies investigating the relationships between maternal TG during pregnancy and neonatal outcomes.

OBJECTIVES

The objective of this study was to investigate the associations between maternal TG during the second and third trimesters and neonatal outcomes including preterm birth (PTB), low birth weight (LBW), small for gestational age (SGA) and large for gestational age (LGA).

METHODS

This was a prospective birth cohort study using data of the Japan Environment and Children's Study included data of births from 2011-2014 in Japan including 79,519 pairs. Participants were divided into tertiles according to maternal TG in the second or third trimesters. Multiple logistic regression modeling was used to examine the risks of LBW, SGA, LGA and PTB in association with maternal TG levels in the second or third trimesters RESULTS: In the second trimester, compared with reference TG group (T2), women in higher TG group (T3) and lower TG group (T1) were also at increased risk of LGA (aOR 1.20, 95% CI 1.11-1.29) and SGA (aOR 1.25, 95% CI 1.10-1.41), respectively. In the third trimester, women in T3 and T1 were at increased risk of LGA (aOR 1.27, 95% CI 1.17-1.38) and SGA (aOR 1.17, 95% CI 1.02-1.34), respectively.

CONCLUSION

In this study, higher maternal TG levels in the second or third trimesters were associated with risks of LGA, however, lower maternal TG levels in the second or third trimesters were conversely associated with risks of SGA.

Maternal high cholesterol diet negatively programs offspring bone development and downregulates hedgehog signaling in osteoblasts

Cholesterol is one of the essential intrauterine factors required for fetal growth and development. Maternal high cholesterol levels are known to be detrimental for offspring health. However, its long-term effect on offspring skeletal development remains to be elucidated. We performed our studies in two strains of mice (C57BL6/J and Swiss Albino) and human subjects (65 mother–female newborn dyads) to understand the regulation of offspring skeletal growth by maternal high cholesterol. We found that mice offspring from high-cholesterol-fed dams had low birth weight, smaller body length, and delayed skeletal ossification at the E18.5 embryonic stage. Moreover, we observed that the offspring did not recover from the reduced skeletal mass and exhibited a low bone mass phenotype throughout their life. We attributed this effect to reduced osteoblast cell activity with a concomitant increase in the osteoclast cell population. Our investigation of the molecular mechanism revealed that offspring from high-cholesterol-fed dams had a decrease in the expression of ligands and proteins involved in hedgehog signaling. Further, our cross-sectional study of human subjects showed a significant inverse correlation between maternal blood cholesterol levels and cord blood bone formation markers. Moreover, the bone formation markers were significantly lower in the female newborns of hypercholesterolemic mothers compared with mothers with normal cholesterolemic levels. Together, our results suggest that maternal high cholesterol levels deleteriously program offspring bone mass and bone quality and downregulate the hedgehog signaling pathway in their osteoblasts.

Cholesterol in Brain Development and Perinatal Brain Injury: More than a Building Block

The central nervous system (CNS) is enriched with important classes of lipids, in which cholesterol is known to make up a major portion of myelin sheaths, besides being a structural and functional unit of CNS cell membranes. Unlike in the adult brain, where the cholesterol pool is relatively stable, cholesterol is synthesized and accumulated at the highest rate in the developing brain to meet the needs of rapid brain growth at this stage, which is also a critical period for neuroplasticity. In addition to its biophysical role in membrane organization, cholesterol is crucial for brain development due to its involvement in brain patterning, myelination, neuronal differentiation, and synaptogenesis. Thus any injuries to the immature brain that affect cholesterol homeostasis may have long-term adverse neurological consequences. In this review, we describe the unique features of brain cholesterol biosynthesis and metabolism, cholesterol trafficking between different cell types, and highlight cholesterol-dependent biological processes during brain maturation. We also discuss the association of impaired cholesterol homeostasis with several forms of perinatal brain disorders in term and preterm newborns, including hypoxic-ischemic encephalopathy. Strategies targeting the cholesterol pathways may open new avenues for the diagnosis and treatment of developmental brain injury.

Genetic regulation and variation of expression of miRNA and mRNA transcripts in fetal muscle tissue in the context of sex, dam and variable fetal weight

BACKGROUND

Impaired skeletal muscle growth in utero can result in reduced birth weight and pathogenesis of intrauterine growth restriction. Fetal and placental growth is influenced by many factors including genetic, epigenetic and environmental factors. In fact, the sex and genotype of the fetus itself, as well as the mother providing it with a suitable environment, influence the growth of the fetus. Hence, our goal was to decipher and elucidate the molecular pathways of developmental processes mediated by miRNAs and mRNAs in fetal muscle tissue in the context of sex, dam, and fetal weight. Therefore, we analyse the variation of miRNA and mRNA expression in relation to these factors. In addition, the coincidence of genetic regulation of these mRNAs and miRNAs, as revealed by expression quantitative trait loci (eQTL) analyses, with sex-, mother- and weight-associated expression was investigated.

METHODS

A three-generation pig F2 population (n = 118) based on reciprocal crossing of German Landrace (DL) and Pietrain (Pi) was used. Genotype information and transcriptomic data (mRNA and miRNA) from longissimus dorsi muscle (LDM) of pig fetuses sampled at 63 days post-conception (dpc) were used for eQTL analyses.

RESULTS

The transcript abundances of 13, 853, and 275 probe-sets were influenced by sex, dam and fetal weight at 63 dpc, respectively (FDR < 5%). Most of significant transcripts affected by sex were located on the sex chromosomes including KDM6A and ANOS1 or autosomes including ANKS1B, LOC100155138 and miR-153. The fetal muscle transcripts associated with fetal weight indicated clearer metabolic directions than maternally influenced fetal muscle transcripts. Moreover, coincidence of genetic regulation (eQTL) and variation in transcript abundance due to sex, dam and fetal weight were identified.

CONCLUSIONS

Integrating information on eQTL, sex-, dam- and weight-associated differential expression and QTL for fetal weight allowed us to identify molecular pathways and shed light on the basic biological processes associated with differential muscle development in males and females, with implications for adaptive fetal programming.

The Distinct Role of the HDL Receptor SR-BI in Cholesterol Homeostasis of Human Placental Arterial and Venous Endothelial Cells

As opposed to adults, high-density lipoprotein (HDL) is the main cholesterol carrying lipoprotein in fetal circulation. The major HDL receptor, scavenger receptor class B type I (SR-BI), contributes to local cholesterol homeostasis. Arterial endothelial cells (ECA) from human placenta are enriched with cholesterol compared to venous endothelial cells (ECV). Moreover, umbilical venous and arterial plasma cholesterol levels differ markedly. We tested the hypothesis that the uptake of HDL-cholesteryl esters differs between ECA and ECV because of the differential expression of SR-BI. We aimed to identify the key regulators underlying these differences and the functional consequences. Immunohistochemistry was used for visualization of SR-BI in situ. ECA and ECV were isolated from the chorionic plate of human placenta and used for RT-qPCR, Western Blot, and HDL uptake assays with ³H- and ¹²⁵I-labeled HDL. DNA was extracted for the methylation profiling of the SR-BI promoter. SR-BI regulation was studied by exposing ECA and ECV to differential oxygen concentrations or shear stress. Our results show elevated SR-BI expression and protein abundance in ECA compared to ECV in situ and in vitro. Immunohistochemistry demonstrated that SR-BI is mainly expressed on the apical side of placental endothelial cells in situ, allowing interaction with mature HDL circulating in the fetal blood. This was functionally linked to a higher increase of selective cholesterol ester uptake from fetal HDL in ECA than in ECV, and resulted in increased cholesterol availability in ECA. SR-BI expression on ECV tended to decrease with shear stress, which, together with heterogeneous immunostaining, suggests that SR-BI expression is locally regulated in the placental vasculature. In addition, hypomethylation of several CpG sites within the SR-BI promoter region might contribute to differential expression of SR-BI between chorionic arteries and veins. Therefore, SR-BI contributes to a local cholesterol homeostasis in ECA and ECV of the human feto-placental vasculature.

The Influence of Maternal Aerobic Exercise, Blood DHA and EPA Concentrations on Maternal Lipid Profiles

Exercise and polyunsaturated fatty acid (PUFA) supplementation independently improve lipid profiles. The influence of both exercise and PUFAs on lipids during pregnancy remains unknown. This study evaluated exercise, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) concentrations on lipids during pregnancy. Participants were randomized to aerobic exercise or control groups. From 16 weeks gestation until delivery, groups met 3x/week; exercisers performed moderate-intensity aerobic activity, controls performed low-intensity stretching and breathing. At 16 and 36 weeks’ gestation, maternal blood was analyzed for lipids (total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides (TG)), DHA and EPA. In intent-to-treat analysis, the aerobic group (n = 20), relative to controls (n = 10), exhibited a higher HDL change across gestation (p = 0.03). In a per protocol analysis, the aerobic group, relative to controls, exhibited 21.2% lower TG at 36 weeks (p = 0.04). After controlling for 36-week DHA and EPA, exercise dose predicts 36 weeks’ TG (F (1,36) = 6.977, p = 0.012, r² = 0.16). Aerobic exercise normalizes late pregnancy TG. During pregnancy, exercise dose controls the rise in TG, therefore maintaining normal levels. DHA and EPA do not have measurable effects on lipids. Regardless of PUFA levels, exercise at recommended levels maintains appropriate TG levels in pregnant women. Normal TG levels are critical for pregnancy outcomes, and further studies are warranted to investigate this association in broader populations.

The role of statins in the prevention of preeclampsia

Preeclampsia is a common hypertensive disorder of pregnancy associated with considerable neonatal and maternal morbidities and mortalities. However, the exact cause of preeclampsia remains unknown; it is generally accepted that abnormal placentation resulting in the release of soluble antiangiogenic factors, coupled with increased oxidative stress and inflammation, leads to systemic endothelial dysfunction and the clinical manifestations of the disease. Statins have been found to correct similar pathophysiological pathways that underlie the development of preeclampsia. Pravastatin, specifically, has been reported in various preclinical and clinical studies to reverse the pregnancy-specific angiogenic imbalance associated with preeclampsia, to restore global endothelial health, and to prevent oxidative and inflammatory injury. Human studies have found a favorable safety profile for pravastatin, and more recent evidence does not support the previous teratogenic concerns surrounding statins in pregnancy. With reassuring and positive findings from pilot studies and strong biological plausibility, statins should be investigated in large clinical randomized-controlled trials for the prevention of preeclampsia.

Association of Maternal Total Cholesterol With SGA or LGA Birth at Term: the Japan Environment and Children's Study

CONTEXT

Maternal cholesterol is important for fetal development. Whether maternal serum total cholesterol (maternal TC) levels in midpregnancy are associated with small (SGA) or large (LGA) for gestational age independent of prepregnancy body mass index (BMI) and weight gain during pregnancy is inconclusive.

OBJECTIVE

This work aimed to prospectively investigate the association between maternal TC in midpregnancy and SGA or LGA.

METHODS

The Japan Environment and Children's Study is a nationwide prospective birth cohort study in Japan. Participants in this study included 37 449 nondiabetic, nonhypertensive mothers with singleton birth at term without congenital abnormalities. Birth weight for gestational age less than the 10th percentile and greater than or equal to the 90th percentile were respectively defined as SGA and LGA by the Japanese neonatal anthropometric charts.

RESULTS

The mean gestational age at blood sampling was 22.7 ± 4.0 weeks. After adjustment for maternal age, sex of child, parity, weight gain during pregnancy, prepregnancy BMI, smoking, alcohol drinking, blood glucose levels, household income, and study areas, 1-SD decrement of maternal TC was linearly associated with SGA (odds ratio [OR]: 1.20; 95% CI, 1.15-1.25). In contrast, 1-SD increment of maternal TC was linearly associated with LGA (OR: 1.13; 95% CI, 1.09-1.16). Associations did not differ according to prepregnancy BMI and gestational weight gain (P for interaction > .20).

CONCLUSION

Maternal TC levels in midpregnancy were associated with SGA or LGA in a Japanese cohort. It may help to predict SGA and LGA. Favorable maternal lipid profiles for fetal development must be explored.

A wide range of triglyceride levels is sufficient for fetal growth at gestational weeks 12-16, but higher triglyceride levels are associated with gestational hypertension

OBJECTIVES

To learn whether and how lipid levels are associated with gestational hypertension and fetal growth in normal pregnancy.

STUDY DESIGN

In a case-control study course, 464 patients with gestational hypertension were pooled into a case group; a total of 1077 women with full-term pregnancies and no pregnancy complications were selected as controls. In a cross-sectional study, whether maternal lipid levels were associated with fetal growth were evaluated in 1077 healthy controls.

MAIN OUTCOME MEASURES

Maternal lipids and glucose levels and fetal measurements.

RESULTS

Maternal levels of triglyceride (TG) were significantly higher in the case group than in controls at gestational weeks 12-16. Levels of TG, total cholesterol (TC) and low-densitylipoprotein (LDL-C) in control mothers increased gradually and significantly with increasing gestational week, however, these lipid concentrations lost these steady elevating trends with gestational week increases in the cases. Binary logistic regression showed that TG is a risk factor associated with hypertension at gestational weeks 12-16 and independent to maternal blood levels of LDL-C and glucose. Of the healthy mothers at gestational weeks 12-16, quantile regression showed that TG levels were not associated with real-time fetal growth measurements or final birthweight. The reference standards for maternal TG levels were estimated via the 10th, 25th, 50th, 75th, and 90th percentiles by gestational week.

CONCLUSIONS

Maternal TG levels are associated with gestational hypertension, and a wide range of TG levels is sufficient for fetal growth within a given gestational week.

A randomized pilot clinical trial of pravastatin versus placebo in pregnant patients at high risk of preeclampsia

BACKGROUND

Preeclampsia remains a major cause of maternal and neonatal morbidity and mortality. Biologic plausibility, compelling preliminary data, and a pilot clinical trial support the safety and utility of pravastatin for the prevention of preeclampsia.

OBJECTIVE

We previously reported the results of a phase I clinical trial using a low dose (10 mg) of pravastatin in high-risk pregnant women. Here, we report a follow-up, randomized trial of 20 mg pravastatin versus placebo among pregnant women with previous preeclampsia who required delivery before 34+6 weeks' gestation with the objective of evaluating the safety and pharmacokinetic parameters of pravastatin.

STUDY DESIGN

This was a pilot, multicenter, blinded, placebo-controlled, randomized trial of women with singleton, nonanomalous pregnancies at high risk for preeclampsia. Women between 12+0 and 16+6 weeks of gestation were assigned to receive a daily pravastatin dose of 20 mg or placebo orally until delivery. In addition, steady-state pravastatin pharmacokinetic studies were conducted in the second and third trimesters of pregnancy and at 4 to 6 months postpartum. Primary outcomes included maternal-fetal safety and pharmacokinetic parameters of pravastatin during pregnancy. Secondary outcomes included maternal and umbilical cord blood chemistries and maternal and neonatal outcomes, including rates of preeclampsia and preterm delivery, gestational age at delivery, and birthweight.

RESULTS

Of note, 10 women assigned to receive pravastatin and 10 assigned to receive the placebo completed the trial. No significant differences were observed between the 2 groups in the rates of adverse or serious adverse events, congenital anomalies, or maternal and umbilical cord blood chemistries. Headache followed by heartburn and musculoskeletal pain were the most common side effects. We report the pravastatin pharmacokinetic parameters including pravastatin area under the curve (total drug exposure over a dosing interval), apparent oral clearance, half-life, and others during pregnancy and compare it with those values measured during the postpartum period. In the majority of the umbilical cord and maternal samples at the time of delivery, pravastatin concentrations were below the limit of quantification of the assay. The pregnancy and neonatal outcomes were more favorable in the pravastatin group. All newborns passed their brainstem auditory evoked response potential or similar hearing screening tests. The average maximum concentration and area under the curve values were more than 2-fold higher following a daily 20 mg dose compared with a 10 mg daily pravastatin dose, but the apparent oral clearance, half-life, and time to reach maximum concentration were similar, which is consistent with the previously reported linear, dose-independent pharmacokinetics of pravastatin in nonpregnant subjects.

CONCLUSION

This study confirmed the overall safety and favorable pregnancy outcomes for pravastatin in women at high risk for preeclampsia. This favorable risk-benefit analysis justifies a larger clinical trial to evaluate the efficacy of pravastatin for the prevention of preeclampsia. Until then, pravastatin use during pregnancy remains investigational.

Effects of maternal dietary energy restriction on laying performance, embryonic development, and lipid Metabolism in broilers

Objective

The objective of this study was to investigate the effects of different degrees of maternal dietary energy restriction on lipid deposition in embryonic tissues during the medium laying period (37 to 39 weeks) in Arbor Acres (AA) broiler breeders.

Methods

A single factor design was adopted, and 400 AA broiler breeders (20 weeks of age) with a similar weight were randomly allocated into four groups. The birds in the control group were fed a corn-soybean meal based diet, and those in trial groups were fed diets with 80%, 70%, and 50% energy levels of the basal diet. Incubated eggs from the medium laying period were collected. Samples of developing embryos at various stages were prepared for composition analysis.

Results

The embryo weight in the 80% energy group was higher than those of the other groups on embryonic day (E) 13, but at 21 E, they were significantly decreased with decreasing energy intake of the broiler breeders (p<0.05). Additionally, the levels of crude fat in tissues in the restriction groups were significantly decreased (p<0.05). The long axis and area of adipocytes in breast muscle, thigh muscle and the liver were significantly decreased (p<0.05) at 21 E in the 80%, 70%, and 50% energy groups.

Conclusion

The effects of the 80% maternal dietary energy restriction energy affects egg production performance, egg quality, and nutrient deposition in egg weights, which then directly impacts on the developmental process of embryos, especially on fat utilization and deposition.

Dysregulated Autophagy Leads to Oxidative Stress and Aberrant Expression of ABC Transporters in Women with Early Miscarriage

Early miscarriage (EMC) is a devastating obstetrical complication. ATP-binding cassette (ABC) transporters mediate cholesterol transfer across the placenta and enhance cell survival by effluxing substrates from target cells in the presence of stressors. Recent evidence reports an intricate interplay between autophagy and ABC transporters. We hypothesized that dysregulated autophagy and oxidative stress (OS) in the placenta leads to abnormal expression of membrane transporters contributing to poor pregnancy survival in EMC. We determined mRNA and protein expression of autophagy genes (Beclin-1/Bcl-2/LC3I/LC3II/p62) and ABC transporters (ABCA1/ABCG1/ABCG2) in placentae from EMC patients (n = 20), term controls (n = 19), first trimester (n = 6), and term controls (n = 5) controls. Oxidative/antioxidant status and biomarkers of oxidative damage were evaluated in maternal serum and placentae from EMC and healthy controls. In EMC, placental expression of LC3II/LC3I as well as of the key autophagy regulatory proteins Beclin-1 and Bcl-2 were reduced, whereas p62 was increased. Both in the serum and placentae of EMC patients, total OS was elevated reflected by increased oxidative damage markers (8-OHdG/malondialdehyde/carbonyl formation) accompanied by diminished levels of total antioxidant status, catalase, and total glutathione. Furthermore, we found reduced ABCG1 and increased ABCG2 expression. These findings suggest that a decreased autophagy status triggers Bcl-2-dependent OS leading to macromolecule damage in EMC placentae. The decreased expression of ABCG1 contributes to reduced cholesterol export to the growing fetus. Increasing ABCG2 expression could represent a protective feedback mechanism under inhibited autophagy conditions. In conclusion, dysregulated autophagy combined with increased oxidative toxicity and aberrant expression of placental ABC transporters affects materno-fetal health in EMC.

Defective Lysosomal Lipolysis Causes Prenatal Lipid Accumulation and Exacerbates Immediately after Birth

Cholesterol and fatty acids are essential lipids that are critical for membrane biosynthesis and fetal organ development. Cholesteryl esters (CE) are degraded by hormone-sensitive lipase (HSL) in the cytosol and by lysosomal acid lipase (LAL) in the lysosome. Impaired LAL or HSL activity causes rare pathologies in humans, with HSL deficiency presenting less severe clinical manifestations. The infantile form of LAL deficiency, a lysosomal lipid storage disorder, leads to premature death. However, the importance of defective lysosomal CE degradation and its consequences during early life are incompletely understood. We therefore investigated how defective CE catabolism affects fetus and infant maturation using Lal and Hsl knockout (-/-) mouse models. This study demonstrates that defective lysosomal but not neutral lipolysis alters placental and fetal cholesterol homeostasis and exhibits an initial disease pathology already in utero as Lal-/- fetuses accumulate hepatic lysosomal lipids. Immediately after birth, LAL deficiency exacerbates with massive hepatic lysosomal lipid accumulation, which continues to worsen into young adulthood. Our data highlight the crucial role of LAL during early development, with the first weeks after birth being critical for aggravating LAL deficiency.

High cholesterol-supplemented diet during gestation and lactation alters liver glycosaminoglycans and associated lipoprotein receptors and results in fat accumulation in adulthood

In utero insults to growing fetus impact its health in adulthood. Glycosaminoglycans (GAGs) are involved in lipoprotein metabolism in the liver and vary both quantitively and qualitatively on feeding adult rats a diet rich in cholesterol. However, no reports are available to show the modulation of GAGs when the offspring are subjected to a high cholesterol diet in gestation and lactation stages. Hypercholesterolemia in pregnant rats was induced by feeding an AIN-93 diet supplemented with 0.5% cholesterol. The pups born to mothers fed with high cholesterol diet showed a significant increase in cholesterol and triglycerides accumulation in the liver. Quantitative changes in sulfated glycosaminoglycans (sGAGs), in particular of heparan sulfate, were observed across the developmental stages. Other players involved in lipoprotein metabolism, namely low-density lipoprotein receptor-related protein 1, apolipoprotein E, and low-density lipoprotein receptor expression levels, also showed differential changes across developmental stages. Interestingly, when pups from hypercholesterolemic mothers were fed a normal diet after weaning until adulthood, a considerable amount of fat accumulation in the liver was observed, implicating fetal exposure to early high cholesterol exposure on long term health.

Cholesterol Contributes to Male Sex Differentiation Through Its Developmental Role in Androgen Synthesis and Hedgehog Signaling

Two specialized functions of cholesterol during fetal development include serving as a precursor to androgen synthesis and supporting hedgehog (HH) signaling activity. Androgens are produced by the testes to facilitate masculinization of the fetus. Recent evidence shows that intricate interactions between the HH and androgen signaling pathways are required for optimal male sex differentiation and defects of either can cause birth anomalies indicative of 46,XY male variations of sex development (VSD). Further, perturbations in cholesterol synthesis can cause developmental defects, including VSD, that phenocopy those caused by disrupted androgen or HH signaling, highlighting the functional role of cholesterol in promoting male sex differentiation. In this review, we focus on the role of cholesterol in systemic androgen and local HH signaling events during fetal masculinization and their collective contributions to pediatric VSD.

Genes and pathways associated with pregnancy loss in dairy cattle

Pregnancy loss directly impairs reproductive performance in dairy cattle. Here, we investigated genetic factors associated with pregnancy loss following detection of a viable embryo around 42 days of gestation. The objectives of this study were to perform whole-genome scans and subsequent gene-set analyses for identifying candidate genes, functional gene-sets and gene signaling pathways implicated in pregnancy loss in US Holstein cows. Data consisted of about 58,000 pregnancy/abortion records distributed over nulliparous, primiparous, and multiparous cows. Threshold models were used to assess the binary response of pregnancy loss. Whole‐genome scans identified at least seven genomic regions on BTA2, BTA10, BTA14, BTA16, BTA21, BTA24 and BTA29 associated with pregnancy loss in heifers and lactating cows. These regions harbor several candidate genes that are directly implicated in pregnancy maintenance and fetal growth, such as CHST14, IGF1R, IGF2, PSEN2, SLC2A5 and WNT4. Moreover, the enrichment analysis revealed at least seven significantly enriched processes, containing genes associated with pregnancy loss, including calcium signaling, cell–cell attachment, cellular proliferation, fetal development, immunity, membrane permeability, and steroid metabolism. Additionally, the pathway analysis revealed a number of significant gene signaling pathways that regulate placental development and fetal growth, including Wnt, Hedgehog, Notch, MAPK, Hippo, mTOR and TGFβ pathways. Overall, our findings contribute to a better understanding of the genetic and biological basis of pregnancy loss in dairy cattle and points out novel strategies for improving pregnancy maintenance via marker‐assisted breeding.

Maternal exposure to air pollutants, PCSK9 levels, fetal growth and gestational age - An Italian cohort

OBJECTIVE

Exposure to airborne pollutants during pregnancy appears to be associated with uterine growth restriction and adverse neonatal outcome. Proprotein convertase subtilisin/kexin type (PCSK9), the key modulator of low-density lipoprotein (LDL) metabolism, increases following particulate matter (PM₁₀) exposure. Because maternal cholesterol is required for fetal growth, PCSK9 levels could be used to evaluate the potential impact of airborne pollutants on fetal growth.

DESIGN

A cohort of 134 healthy women during early pregnancy (11-12 weeks of gestational age) was studied.

RESULTS

A significant association between circulating PCSK9 levels and three tested air pollutants (PM₁₀, PM_2.5, nitric oxide (NO₂)) was found. Of importance, gestational age at birth was reduced by approximately 1 week for each 100 ng/mL rise in circulating PCSK9 levels, an effect that became more significant at the highest quartile of PM_2.5 (with a 1.8 week advance in delivery date for every 100 ng/mL rise in circulating PCSK9; p for interaction = 0.026). This finding was supported by an elevation of the odds ratio for urgent cesarean delivery for each 100 ng/mL rise in PCSK9 (2.99, 95% CI, 1.22-6.57), similar trends being obtained for PM₁₀ and NO₂.

CONCLUSIONS

The association between exposure to air pollutants during pregnancy and elevation in PCSK9 advances our understanding of the unforeseen influences of environmental exposure in terms of pregnancy associated disorders.

Fetal High-Density Lipoproteins: Current Knowledge on Particle Metabolism, Composition and Function in Health and Disease

Cholesterol and other lipids carried by lipoproteins play an indispensable role in fetal development. Recent evidence suggests that maternally derived high-density lipoprotein (HDL) differs from fetal HDL with respect to its proteome, size, and function. Compared to the HDL of adults, fetal HDL is the major carrier of cholesterol and has a unique composition that implies other physiological functions. Fetal HDL is enriched in apolipoprotein E, which binds with high affinity to the low-density lipoprotein receptor. Thus, it appears that a primary function of fetal HDL is the transport of cholesterol to tissues as is accomplished by low-density lipoproteins in adults. The fetal HDL-associated bioactive sphingolipid sphingosine-1-phosphate shows strong vasoprotective effects at the fetoplacental vasculature. Moreover, lipoprotein-associated phospholipase A2 carried by fetal-HDL exerts anti-oxidative and athero-protective functions on the fetoplacental endothelium. Notably, the mass and activity of HDL-associated paraoxonase 1 are about 5-fold lower in the fetus, accompanied by an attenuation of anti-oxidative activity of fetal HDL. Cholesteryl ester transfer protein activity is reduced in fetal circulation despite similar amounts of the enzyme in maternal and fetal serum. This review summarizes the current knowledge on fetal HDL as a potential vasoprotective lipoprotein during fetal development. We also provide an overview of whether and how the protective functionalities of HDL are impaired in pregnancy-related syndromes such as pre-eclampsia or gestational diabetes mellitus.

Materno-fetal cholesterol transport during pregnancy

Cholesterol is a major nutrient required for fetal growth. It is also a precursor for the synthesis of steroid hormones and essential for the development and maturation of fetal organs. During pregnancy, the placenta controls the transport of cholesterol from the mother to the fetus and vice versa. Cholesterol originating from the maternal circulation has to cross two main membrane barriers to reach the fetal circulation: Firstly, cholesterol is acquired by the apical side of the syncytiotrophoblast (STB) from the maternal circulation as high-density lipoprotein (HDL)-, low-density lipoprotein (LDL)- or very-low-density lipoprotein (VLDL)-cholesterol and secreted at the basal side facing the villous stroma. Secondly, from the villous stroma cholesterol is taken up by the endothelium of the fetal vasculature and transported to the fetal vessels. The proteins involved in the uptake of HDL-, LDL-, VLDL- or unesterified-cholesterol are scavenger receptor type B class 1 (SR-B1), cubulin, megalin, LDL receptor (LDLR) or Niemann-Pick-C1 (NPC1) which are localized at the apical and/or basal side of the STB or at the fetal endothelium. Through interaction with apolipoproteins (e.g. apoA1) cholesterol is effluxed either to the maternal or fetal circulation via the ATP-binding-cassette (ABC)-transporter A1 and ABCG1 localized at the apical/basal side of the STB or the endothelium. In this mini-review, we summarize the transport mechanisms of cholesterol across the human placenta, the expression and localization of proteins involved in the uptake and efflux of cholesterol, and the expression pattern of cholesterol transport proteins in pregnancy pathologies such as pre-eclampsia, gestational diabetes mellitus and intrauterine growth retardation.

The association between perfluoroalkyl substances and lipid profile in exposed pregnant women in the Veneto region, Italy

BACKGROUND

Residents of a large area of North-Eastern Italy were exposed for decades to high concentrations of perfluoroalkyl and polyfluoroalkyl substances (PFAS) via drinking water. Serum PFAS levels have been consistently associated with elevated serum lipids, but few studies have been conducted among pregnant women, and none has stratified analyses by trimester of gestation. Elevated serum lipid levels during pregnancy can have both immediate and long-lasting effects on pregnant women and the developing fetus. We evaluated the association between perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluoro-hexanesulfonate (PFHxS) levels in relation to lipid profiles in highly-exposed pregnant women.

METHODS

A cross-sectional analysis was conducted in 319 pregnant women (age 14-48 years) enrolled in the Regional health surveillance program. Non-fasting blood samples were obtained in any trimester of pregnancy and analyzed for PFOA, PFOS and PFHxS, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C). Low-density lipoprotein cholesterol (LDL-C) was calculated. The associations between ln-transformed PFAS (and categorized into quartiles) and lipids were assessed using generalized additive models. Analyses were adjusted for potential confounders and stratified according to pregnancy trimester.

RESULTS

The geometric means of PFOA, PFOS and PFHxS were 14.78 ng/mL, 2.67 ng/mL and 1.89 ng/mL, respectively. The plasma levels of TC, HDL-C and LDL-C increased steadily throughout the trimesters. In the 1st trimester, PFOS was positively associated with TC and PFHxS with HDL-C. In the 3rd trimester, instead, an inverse relationship was seen between PFOA and PFHxS and both TC and LDL-C.

CONCLUSIONS

Results suggest the associations between PFAS concentrations and lipid profiles in pregnant women might differ by trimesters of pregnancy. In the first trimester, patterns are similar to those of non-pregnant women, while they differ late in pregnancy. Different independent behavior of PFAS and lipid levels throughout the pregnancy might explain our observations. These findings support the ubiquitous exposure to PFAS and possible influence on lipid metabolisms during pregnancy and suggest a careful evaluation of the timing of PFAS measurement, when examining effects of PFAS during pregnancy on gestational outcomes related to serum lipids amounts.

Maternally inherited hypercholesterolemia does not modify the cardiovascular phenotype in familial hypercholesterolemia

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is a codominant autosomal disease characterized by a high risk of cardiovascular disease when not in lipid-lowering treatment. However, there is a large variability in the clinical presentation in heterozygous subjects (HeFH). Maternal hypercholesterolemia has been proposed as a cardiometabolic risk factor later in life. Whether this phenotype variability depends on the mother or father origin of hypercholesterolemia is unknown. The objective of this study was to analyze potential differences in anthropometry, superficial lipid deposits, comorbidities, and lipid concentrations depending on the parental origin of hypercholesterolemia within a large group of HeFH.

METHODS

This is a cross-sectional observational, multicenter, nation-wide study in Spain. We recruited adults with HeFH to study clinical differences according to the parental origin. Data on HeFH patients were obtained from the Dyslipidemia Registry of the Spanish Atherosclerosis Society.

RESULTS

HeFH patients were grouped in 1231 HeFH-mother-offspring aged 45.7 (16.3) years and 1174 HeFH-father-offspring aged 44.8 (16.7) years. We did not find any difference in lipid parameters (total cholesterol, triglycerides, LDLc, HDLc, and Lp(a)), nor in the comorbidities studied (cardiovascular disease prevalence, age of onset of cardiovascular disease, obesity, diabetes, and hypertension) between groups. Lipid-lowering treatment did not differ between groups. The prevalence of comorbidities did not show differences when they were studied by age groups.

CONCLUSIONS

Our research with a large group of subjects with HeFH shows that a potential maternal effect is not relevant in FH. However, due to the size of our sample, potential differences between genders cannot be completely ruled out. This implies that severe maternal hypercholesterolemia during pregnancy is not associated with additional risk in the FH affected offspring.

Cholesterol metabolism and brain injury in neonatal encephalopathy

Neonatal encephalopathy (NE) results from impaired cerebral blood flow and oxygen delivery to the brain. The pathophysiology of NE is complex and our understanding of its underlying pathways continues to evolve. There is considerable evidence that cholesterol dysregulation is involved in several adult diseases, including traumatic brain injury, stroke, Huntington's disease, and Parkinson's disease. Although the research is less robust in pediatrics, there is emerging evidence that aberrations in cholesterol metabolism may also be involved in the pathophysiology of neonatal NE. This narrative review provides an overview of cholesterol metabolism in the brain along with several examples from the adult literature where pathologic alterations in cholesterol metabolism have been associated with inflammatory and ischemic brain injury. Using those data as a background, the review then discusses the current preclinical data supporting the involvement of cholesterol in the pathogenesis of NE as well as how brain-specific cholesterol metabolites may serve as serum biomarkers for brain injury. Lastly, we review the potential for using the cholesterol metabolic pathways as therapeutic targets. Further investigation of the shifts in cholesterol synthesis and metabolism after hypoxia-ischemia may prove vital in understanding NE pathophysiology as well as providing opportunities for rapid diagnosis and therapeutic interventions. IMPACT: This review summarizes emerging evidence that aberrations in cholesterol metabolism may be involved in the pathophysiology of NE. Using data from NE as well as analogous adult disease states, this article reviews the potential for using cholesterol pathways as targets for developing novel therapeutic interventions and using cholesterol metabolites as biomarkers for injury. When possible, gaps in the current literature were identified to aid in the development of future studies to further investigate the interactions between cholesterol pathways and NE.

Maternal exposure to soy diet reduces atheroma in hyperlipidemic F1 offspring mice by promoting macrophage and T cell anti-inflammatory responses

BACKGROUND AND AIMS

Maternal hypercholesterolemia has been implicated in earlier onset of atherosclerotic lesions in neonatal offspring. In this study, we investigated whether maternal exposure to soy protein isolate (SPI) diet attenuated the progression of atherosclerosis in F1 offspring.

METHOD

Pregnant apolipoprotein E knockout (Apoe^-/-) female mice were fed SPI diet until postnatal day 21 (PND21) of the offspring (SPI-offspring). SPI-offspring were switched at PND21 to casein (CAS) diet until PND140. Mice fed CAS throughout their lifetime (gestation to adulthood) were used as controls (CAS-offspring).

RESULTS

Atherosclerotic lesions in the aortic sinuses were reduced in SPI-offspring compared with CAS-offspring. Total serum cholesterol levels in CAS-offspring or dams were comparable to levels in their SPI-counterparts, suggesting that alternative mechanisms contributed to the athero-protective effect of maternal SPI diet. Aortic VCAM-1, MCP-1, and TNF-α mRNA and protein expression, and expression of macrophage pro-inflammatory cytokines was reduced in SPI-offspring. Interestingly, CD4⁺ T cells from SPI-offspring showed reduced IFN-γ expression (Th1), while the expression of IL-10 (Th2/Treg), and IL-13 (Th2) was increased. DNA methylation analyses revealed that anti-inflammatory T cell-associated Gata3 and Il13 promoter regions were hypomethylated in SPI-offspring. These findings suggest that anti-inflammatory macrophage and T cell response may have contributed to the athero-protective effect in SPI-offspring.

CONCLUSIONS

Our findings demonstrate that gestational and lactational soy diet exposure inhibits susceptibility to atherosclerotic lesion formation by promoting anti-inflammatory responses by macrophages and T cells.

The relationship between total cholesterol and postpartum impaired glucose tolerance in women with gestational diabetes mellitus

Background

History of gestational diabetes mellitus (GDM) and serum lipid abnormalities were associated with postpartum impaired glucose tolerance. To investigate the association between concentration of total cholesterol (TC), at the time of GDM diagnosis, and risk of postpartum glucose intolerance.

Methods

Women who were diagnosed GDM with a live singleton delivery between January 1, 2013 and December 31, 2017 were included. Women were grouped based on the TC quartiles at the time of GDM diagnosis and had an OGTT at 6–12 weeks after delivery. The relationship between TC and the risk of postpartum glucose intolerance was assessed by COX regression.

Results

A total of 845 women were in the final analysis. Higher TC quartile at diagnosis of GDM was associated with a decreased risk of postpartum glucose intolerance. Women in the highest TC quartile (>7.0 mmol L^− 1) had approximately only half-risk of any postpartum glucose intolerance, compared with women in the lowest TC quartile (<5.5 mmol L^− 1).

Conclusions

The decreased concentration of TC, at the time of GDM diagnosis, was related to an increased risk of postpartum abnormal glucose regulation in GDM women. Therefore, because both excessively increased and decreased TC were associated with pregnancy and postpartum complications, the optimal concentration of maternal TC throughout pregnancy remained to be further researched.

Lipidomic profiles of maternal blood at the earlier stage of gestation and umbilical venous blood in response to supraphysiological hypercholesterolemia versus physiological hypercholesterolemia: An evidence of potential biomarkers and early intervention

BACKGROUND

To our knowledge, we lack a complete understanding of the lipidomes alterations caused by maternal supraphysiological hypercholesterolemia (MSPH) at the third trimester.

OBJECTIVES

The aim of this study was to investigate lipidomes alterations in maternal and umbilical venous (UV) serum and explore the association between these alterations and MSPH.

METHODS

We conducted a nest case-control study between maternal physiological hypercholesterolemia (MPH) and MSPH subjects during pregnancy. Lipidomic profiling of maternal serum at the first trimester of gestation and UV serum was performed by ultra-high-performance liquid chromatography system connected to a quadrupole time-of-light/mass spectrometer.

RESULTS

Several glycerophospholipids and sphingolipids (C18 sphingoid base) species were distinctly altered in maternal serum and/or UV serum with MSPH versus MPH. Glycerophospholipid metabolism, sphingolipid metabolism and propanoate metabolism were the main pathways that involved the most of discriminate metabolites. Higher HDL-c and phosphatidylcholine (16:0/0:0) (PC (16:0/0:0)) during pregnancy, higher PC (16:0/0:0) and lower cholesterol ester 20:4(8Z,11Z,14Z,17Z) (CE (20:4(8Z,11Z,14Z,17Z))) in the UV serum may be the risk factors for the increased placental circulation resistance. The total cholesterol levels of maternal serum both at the first trimester and at the third trimester were significantly correlated with some lipid species of UV serum.

CONCLUSION

This study clarifies the differential lipid profiles to distinguish MSPH from MPH and the pathway which is influenced under the condition of MSPH. Also, it provides a resource to look for potential therapeutic targets for MSPH.

Decreased H3K9 acetylation level of LXRα mediated dexamethasone-induced placental cholesterol transport dysfunction

Due to the insufficient fetal cholesterol synthesis, maternal cholesterol transport through the placenta becomes an important source of fetal cholesterol pool, which is essential for fetal growth and development. This study aimed to investigate the effects of dexamethasone on fetal cholesterol levels, and explore its placental mechanism. Pregnant Wistar rats were injected subcutaneously with dexamethasone (0.8 mg/kg·d) from gestational day 9 to 20. Results showed that dexamethasone increased maternal serum total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C) levels, as well as placental cholesterol synthesis and TC concentration, while reduced fetal birth weight, and serum TC, HDL-C and LDL-C levels. Meanwhile, the expression of placental cholesterol transporters, including low-density lipoprotein receptor (LDLR), scavenger receptor class B type I (SR-B1) and ATP-binding cassette transporter A1 and G1 (ABCA1 and ABCG1) were decreased by dexamethasone. Furthermore, the expression of glucocorticoid receptor (GR) and histone deacetylase 3 (HDAC3) were increased, while the H3K9ac and expression levels of liver X receptor α (LXRα) promoter were reduced. In human trophoblast cell line (BeWo), dexamethasone concentration-dependently decreased the expression levels of LDLR, SR-B1, ABCA1, ABCG1 as well as LXRα. Dexamethasone (2500 nM) induced GR translocation into nucleus and recruited HDAC3. Furthermore, LXRα agonist and GR inhibitor reversed respectively dexamethasone-induced the expression inhibitions of cholesterol transporter and LXRα, and HDAC3 siRNA reversed the H3K9ac level of LXRα promoter and its expression. Together, dexamethasone impaired placental cholesterol transport and eventually decreased fetal cholesterol levels, which is related to the down-regulation of LXRα mediated by GR/HDAC3/H3K9ac signaling.

Maternal dyslipidemia during early pregnancy and epigenetic ageing of the placenta

Disruption of physiological ageing of the placenta is associated with obstetric complications. Altered lipid metabolism is a known trigger of tissue ageing, but the effect of maternal dyslipidemia on placental ageing is not clearly understood. We examined the relationship between maternal dyslipidemia and placental age acceleration (PAA), an epigenetic ageing measure derived from the difference between DNA methylation age and chronological gestational age. We also assessed whether the association varies by maternal pre-pregnancy obesity status and fetal sex. Placental data were obtained as part of the NICHD Fetal Growth Studies that involved participants from four race/ethnic groups. Placental DNA methylation age was estimated using 62 CpGs that have previously been found to have high placental age prediction accuracy. We used multivariable linear regression to test associations between maternal dyslipidemia during early gestation (i.e., high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc), total cholesterol (TChol), and triglycerides) and PAA adjusting for fetal sex and socio-demographic factors. Among normal-weight women, low HDLc, compared to high HDLc, was associated with 0.82 (95% CI: 0.00, 1.64) weeks higher PAA. Among women with female neonates, low HDLc, compared to high HDLc, was associated with 1.20 (95% CI: 0.17, 2.24) weeks higher PAA. High TChol was associated with 1.28 (95% CI: 0.12, 2.45) weeks higher PAA among Whites. In all, the study found that maternal dyslipidemia due to low HDLc was associated with accelerated epigenetic ageing of the placenta among mothers with normal pre-pregnancy weight and a female fetus.

The Association between Dyslipidemia and Preterm Birth: A Prospective Cohort Study in The North of Iran

BACKGROUND

Dyslipidemia is recognized as an important factor in the incidence of Preterm Birth (PTB). The early diagnosis of factors affecting PTB is important in the reduction of maternalneonatal complications; therefore, we aimed to evaluate the association between dyslipidemia and PTB in women from the Guilan province of Iran.

METHODS

The current investigation was a prospective cohort study on 378 pregnant women in Rasht city (Guilan province), during 2018-2019. Samples were randomly selected among pregnant women who referred to Al-Zahra hospital. Association of the lipid profiles: Total Cholesterol (TC), High- Density Lipoprotein (HDLC), Low-Density Lipoprotein (LDLC), and Triglycerides (TG) with PTB was assessed using the Chi-square, Fisher tests and logistic regression analysis.

RESULTS

Our findings showed that of the evaluated lipid profiles, TG and TC had the highest predictive power with AUC =0.833 (95٪, CI: 0.736-0.930) and 0.772 (95%, CI: 0.676-0.867), respectively; also, their sensitivity and specificity were 83.3%, 70.2% and 83.3%, 66.1%, respectively. Moreover, abnormal LDL concentrations increase the risk of PTB by two folds (P < 0.05).

CONCLUSION

It seems that by controlling the lipid profiles of pregnant women, the risk of PTB could be reduced.

Dyslipidemia in pregnancy and maternal-fetal outcome

Hyperlipidemia is a known cause of atherosclerosis and directly contributes to the current epidemic in cardio-vascular disease. Pregnancy is typified by an increase in serum levels of total cholesterol and triglycerides pushed by the rise in estrogen, progesterone and lactogen. Mobilization of stored fat depots in late pregnancy may provide a reservoir of fatty acids for fetal growth and placental tissue steroid synthesis. This physiologic increase in lipids performs an essential role during pregnancy; however, elevated levels of lipids in predisposed women or with familiar forms of hyperlipidemia can carry increased risk for maternal-fetal complications. The present treatment of pregnant women with hyperlipidemia is the suspension of medications. However, hyperlipidemia during pregnancy is associated with preeclampsia, preterm birth and gestational diabetes and offspring of these mothers show a propensity to enhanced fatty streak formation and an increased risk of progressive atherosclerosis. This current evidence may motivate the further study on the potential benefits of treatment of hyperlipidemia in pregnancy and its effects on maternal-fetal outcomes.

Physiology and Pathophysiology of Steroid Biosynthesis, Transport and Metabolism in the Human Placenta

The steroid hormones progestagens, estrogens, androgens, and glucocorticoids as well as their precursor cholesterol are required for successful establishment and maintenance of pregnancy and proper development of the fetus. The human placenta forms at the interface of maternal and fetal circulation. It participates in biosynthesis and metabolism of steroids as well as their regulated exchange between maternal and fetal compartment. This review outlines the mechanisms of human placental handling of steroid compounds. Cholesterol is transported from mother to offspring involving lipoprotein receptors such as low-density lipoprotein receptor (LDLR) and scavenger receptor class B type I (SRB1) as well as ATP-binding cassette (ABC)-transporters, ABCA1 and ABCG1. Additionally, cholesterol is also a precursor for placental progesterone and estrogen synthesis. Hormone synthesis is predominantly performed by members of the cytochrome P-450 (CYP) enzyme family including CYP11A1 or CYP19A1 and hydroxysteroid dehydrogenases (HSDs) such as 3β-HSD and 17β-HSD. Placental estrogen synthesis requires delivery of sulfate-conjugated precursor molecules from fetal and maternal serum. Placental uptake of these precursors is mediated by members of the solute carrier (SLC) family including sodium-dependent organic anion transporter (SOAT), organic anion transporter 4 (OAT4), and organic anion transporting polypeptide 2B1 (OATP2B1). Maternal-fetal glucocorticoid transport has to be tightly regulated in order to ensure healthy fetal growth and development. For that purpose, the placenta expresses the enzymes 11β-HSD 1 and 2 as well as the transporter ABCB1. This article also summarizes the impact of diverse compounds and diseases on the expression level and activity of the involved transporters, receptors, and metabolizing enzymes and concludes that the regulatory mechanisms changing the physiological to a pathophysiological state are barely explored. The structure and the cellular composition of the human placental barrier are introduced. While steroid production, metabolism and transport in the placental syncytiotrophoblast have been explored for decades, few information is available for the role of placental-fetal endothelial cells in these processes. With regard to placental structure and function, significant differences exist between species. To further decipher physiologic pathways and their pathologic alterations in placental steroid handling, proper model systems are mandatory.

Cholesterol metabolism in rabbit blastocysts under maternal diabetes

In the rabbit reproductive model, maternal experimentally induced insulin-dependent diabetes mellitus (expIDD) leads to accumulation of lipid droplets in blastocysts. Cholesterol metabolism is a likely candidate to explain such metabolic changes. Therefore, in the present study we analysed maternal and embryonic cholesterol concentrations and expression of related genes in vivo (diabetic model) and in vitro (embryo culture in hyperglycaemic medium). In pregnant expIDD rabbits, the serum composition of lipoprotein subfractions was changed, with a decrease in high-density lipoprotein cholesterol and an increase in very low-density lipoprotein cholesterol; in uterine fluid, total cholesterol concentrations were elevated. Expression of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), very low-density lipoprotein receptor (VLDLR), sterol regulatory element binding transcription factor 2 (SREBF2), insulin-induced gene-1 (INSIG1) and cholesterol 7α-hydroxylase (CYP7A1) mRNA was decreased in the liver and low-density lipoprotein receptor (LDLR) mRNA expression was decreased in the adipose tissue of diabetic rabbits. In embryos from diabetic rabbits, the mean (±s.e.m.) ratio of cholesterol concentrations in trophoblasts to embryoblasts was changed from 1.27±2.34 (control) to 0.88±3.85 (expIDD). Rabbit blastocysts expressed HMGCR, LDLR, VLDLR, SREBF2 and INSIG1 but not CYP7A1, without any impairment of expression as a result of maternal diabetes. In vitro hyperglycaemia decreased embryonic HMGCR and SREBF2 transcription in rabbit blastocysts. The findings of the present study show that a diabetic pregnancy leads to distinct changes in maternal cholesterol metabolism with a minor effect on embryo cholesterol metabolism.

In Utero Exposure of Hyperlipidemic Mice to Diesel Exhaust: Lack of Effects on Atherosclerosis in Adult Offspring Fed a Regular Chow Diet

Uterine stress is associated with an increased risk of later life metabolic diseases. In this study, we investigated the effect of diesel exhaust (DE) exposure in utero on adult susceptibility to atherosclerosis in genetically hyperlipidemic mice. Pregnant apolipoprotein E-deficient mice received either DE exposure (~250–300 μg/m³ PM_2.5 for 6 h/day, 5 days/week) or filtered air (FA) throughout gestation. Treatment effects on litter size and gender distribution were recorded. Plasma cholesterol and triglycerides were measured at 8, 12 and 16 weeks of age. Urinary 8-isoprostane and liver 8-hydroxy-deoxyguanosine levels were measured at killing at 16 weeks of age. Expression of the antioxidant genes heme oxygenase-1 and the glutamate-cysteine ligase modifier and catalytic subunits were measured in the lung, liver and aorta. The average area and frequency of atherosclerotic lesions were measured in the aortic sinus and innominate arteries. There were significantly smaller litters and higher postnatal mortality in the DE-exposed mice. There were no significant differences in plasma lipids or lipoprotein profiles, expression of antioxidant genes or markers of oxidative stress between treatment groups. There were also no significant differences in average atherosclerotic lesion area in the aortic sinus or innominate arteries of the DE and FA groups although there was a higher frequency of lesions in the DE-exposed group. Our study indicates that in utero DE exposure does not influence later life lipoprotein metabolism, redox homeostasis or the risk of developing larger atherosclerotic lesions.

Endocytosis of lipoproteins

During their metabolism, all lipoproteins undergo endocytosis, either to be degraded intracellularly, for example in hepatocytes or macrophages, or to be re-secreted, for example in the course of transcytosis by endothelial cells. Moreover, there are several examples of internalized lipoproteins sequestered intracellularly, possibly to exert intracellular functions, for example the cytolysis of trypanosoma. Endocytosis and the subsequent intracellular itinerary of lipoproteins hence are key areas for understanding the regulation of plasma lipid levels as well as the biological functions of lipoproteins. Indeed, the identification of the low-density lipoprotein (LDL)-receptor and the unraveling of its transcriptional regulation led to the elucidation of familial hypercholesterolemia as well as to the development of statins, the most successful therapeutics for lowering of cholesterol levels and risk of atherosclerotic cardiovascular diseases. Novel limiting factors of intracellular trafficking of LDL and the LDL receptor continue to be discovered and to provide drug targets such as PCSK9. Surprisingly, the receptors mediating endocytosis of high-density lipoproteins or lipoprotein(a) are still a matter of controversy or even new discovery. Finally, the receptors and mechanisms, which mediate the uptake of lipoproteins into non-degrading intracellular itineraries for re-secretion (transcytosis, retroendocytosis), storage, or execution of intracellular functions, are largely unknown.

Association of Maternal Prepregnancy Dyslipidemia With Adult Offspring Dyslipidemia in Excess of Anthropometric, Lifestyle, and Genetic Factors in the Framingham Heart Study

IMPORTANCE

Dyslipidemia in young adults in the United States during their childbearing years is common, and the consequences for the next generation are poorly understood. Further understanding of the harmful consequences of elevated low-density lipoprotein cholesterol (LDL-C) levels in young adults may help to inform population screening and management strategies.

OBJECTIVE

To examine whether adult levels of serum LDL-C are associated with maternal prepregnancy LDL-C levels beyond that attributable to inherited genetic sequence polymorphisms, diet, physical activity, and body mass index.

DESIGN, SETTING, AND PARTICIPANTS

The Framingham Heart Study is a multigenerational, population-based inception cohort initiated in 1948 in Framingham, Massachusetts. In this study of families, the analyses included 538 parent-offspring pairs with parental LDL-C levels measured in the study prior to the offspring's birth. Parental prebirth, parental concurrent, and adult offspring assessments occurred in 1971-1983, 1998-2001, and 2002-2005, respectively. Data analyses were conducted between March 1, 2013, and May 30, 2015.

EXPOSURES

Maternal prepregnancy LDL-C levels compared with paternal prepregnancy and parental concurrent LDL-C levels in association with adult offspring LDL-C levels.

MAIN OUTCOMES AND MEASURES

Adult offspring LDL-C levels were examined as both a continuous and dichotomous outcome (using a threshold of 130 mg/dL).

RESULTS

Among the 538 parent-offspring pairs, there were 241 mother-offspring and 297 father-offspring pairs with a mean (SD) offspring age of 26 (3) years. Adult offspring LDL-C levels were associated with maternal prepregnancy LDL-C levels after adjustment for family relatedness and offspring lifestyle, anthropometric factors, and inherited genetic variants (β = 0.32 [SE, 0.05] mg/dL; P < .001). After multivariable adjustment, adults who had been exposed to elevated maternal prepregnancy LDL-C levels were at a 3.8 (95% CI, 1.5-9.8) times higher odds of having elevated LDL-C levels (P = .005) and had an adjusted LDL-C level of 18 mg/dL (95% CI, 9-27 mg/dL) higher than did those without such exposure. Maternal prepregnancy LDL-C levels explained 13% of the variation in adult offspring LDL-C levels beyond common genetic variants and classic risk factors for elevated LDL-C levels.

CONCLUSIONS AND RELEVANCE

Adult offspring dyslipidemia is associated with maternal prepregnancy dyslipidemia in excess of measured lifestyle, anthropometric, and inherited genetic factors. The findings support the possibility of a maternal epigenetic contribution to cardiovascular disease risk in the general population. Further research is warranted to determine whether ongoing public health efforts to identify and reduce dyslipidemia in young adults prior to their childbearing years may have additional potential health benefits for the subsequent generation.

Placental mitochondrial biogenesis and function was slightly changed by gestational hypercholesterolemia in full-term pregnant women

It was reported that high blood cholesterol levels increased the susceptibility to mitochondrial dysfunction. This study hypothesized that the gestational hypercholesterolemia (HC) could induce the mitochondrial dysfunction in term human placenta. The eligible pregnant women were recruited from Xuanwu Hospital in Beijing during their first prenatal visit (before their 10th week of pregnancy). In total, 19 pregnant women whose serum total cholesterol levels were higher than 7.25 mm at third trimester (measured at 36–38 weeks) were selected as gestational HC. Other 19 pregnant women with normal cholesterol level matched with age, pre-gestational body mass index, and the neonatal gender were included as the control group. Full-term placenta samples were collected. The mitochondrial DNA (mtDNA) copy number, messenger RNA (mRNA) expression of cytochrome c oxidase subunit I, adenosine triphosphate monophosphatase 6 (ATP6ase), citrate synthase, peroxisome proliferator-activated receptor-γ (PPARγ) co-activator 1α, PPARγ co-activator 1β and estrogen-related receptor-α, and the activity of mitochondrial respiratory chain enzyme complex were measured. Pregnancy outcomes were obtained by extraction from medical records and the labor ward register. The results showed that only placental mtDNA copy number and mRNA expression of ATP6ase were significantly decreased in HC group. No significant differences were detected of other measurements between the two groups. These findings indicated that gestational HC might not induce the damage of placental function seriously.

Cholesterol Transport Revisited: A New Turbo Mechanism to Drive Cholesterol Excretion

A fine-tuned balance between cholesterol uptake and excretion by the body is pivotal to maintain health and to remain free from the deleterious consequences of cholesterol accumulation such as cardiovascular disease. The pathways involved in intracellular and extracellular cholesterol transport are a subject of intense investigation and are being unraveled in increasing detail. In addition, insight into the complex interactions between cholesterol and bile acid metabolism has increased considerably in the last couple of years. This review provides an overview of the mechanisms involved in cholesterol uptake and excretion, with a particular emphasis on the most recent progress in this field. Special attention is given to the transintestinal cholesterol excretion (TICE) pathway, which was recently demonstrated to have a remarkably high transport capacity and to be sensitive to pharmacological modulation.

Assessment of squalene eligibility in bettering some maternal and fetal disorders instigated by gamma irradiation of rats at mid gestation

PURPOSE

Squalene is an eminent vital part of the synthesis of steroid hormones in the body as well as the first specific intermediate in cholesterol biosynthesis that plays an essential role in normal embryogenesis. The present work was designed to test the maternal and embryonic response to the modulating capacity of squalene (0.4 ml/kg/d), when supplemented to rats from days 1 to 18 of pregnancy, against the damaging consequences induced by maternal subjection to 3 Gy gamma irradiation on day 10 post-conception.

MATERIALS AND METHODS

The experimental protocol comprised of four different pregnant groups, namely: (1) control, (2) squalene supplemented, (3) irradiated and (4) squalene supplemented + irradiated.

RESULTS

It has been detected that radiation has increased the maternal blood lactate dehydrogenase (as a marker of tissue injury), cholesterol, triglycerides, estradiol and progesterone and has also provoked the oxidative stress that has been demonstrated by the increased malondialdehyde (MDA) and the decreased glutathione (GSH) and superoxide dismutase (SOD). These maternal changes were associated with high embryonic lethality, growth retardation, severe developmental abnormalities and defective neural tube closure expressed by exencephaly. However, squalene treatment has significantly improved the radiation imposed maternal variations and reduced the embryonic mortality, although it has not been able to attenuate the embryonic neural tube defects.

CONCLUSIONS

It has been presumed that the maternal mid-gestational irradiation (day 10) has affected the fetal nervous system development with concomitant maternal oxidative stress, hyperlipidemia, and increased progesterone and estradiol levels. Squalene uptake has improved the maternal variations and reduced the embryonic mortality while could not stop or improve the embryonic neural tube defects imposed by radiation at this exact radiation timing.

A Prospective Birth Cohort Study on Maternal Cholesterol Levels and Offspring Attention Deficit Hyperactivity Disorder: New Insight on Sex Differences

Growing evidence suggests that maternal cholesterol levels are important in the offspring’s brain growth and development. Previous studies on cholesterols and brain functions were mostly in adults. We sought to examine the prospective association between maternal cholesterol levels and the risk of attention deficit hyperactivity disorder (ADHD) in the offspring. We analyzed data from the Boston Birth Cohort, enrolled at birth and followed from birth up to age 15 years. The final analyses included 1479 mother-infant pairs: 303 children with ADHD, and 1176 neurotypical children without clinician-diagnosed neurodevelopmental disorders. The median age of the first diagnosis of ADHD was seven years. The multiple logistic regression results showed that a low maternal high-density lipoprotein level (≤60 mg/dL) was associated with an increased risk of ADHD, compared to a higher maternal high-density lipoprotein level, after adjusting for pertinent covariables. A “J” shaped relationship was observed between triglycerides and ADHD risk. The associations with ADHD for maternal high-density lipoprotein and triglycerides were more pronounced among boys. The findings based on this predominantly urban low-income minority birth cohort raise a new mechanistic perspective for understanding the origins of ADHD and the gender differences and future targets in the prevention of ADHD.

Maternal-fetal cholesterol transport in the second half of mouse pregnancy does not involve LDL receptor-related protein 2

AIM

LDL receptor-related protein type 2 (LRP2) is highly expressed on both yolk sac and placenta. Mutations in the corresponding gene are associated with severe birth defects in humans, known as Donnai-Barrow syndrome. We here characterized the contribution of LRP2 and maternal plasma cholesterol availability to maternal-fetal cholesterol transport and fetal cholesterol levels in utero in mice.

METHODS

Lrp2^+/- mice were mated heterozygously to yield fetuses of all three genotypes. Half of the dams received a 0.5% probucol-enriched diet during gestation to decrease maternal HDL cholesterol. At E13.5, the dams received an injection of D7-labelled cholesterol and were provided with 1-¹³ C acetate-supplemented drinking water. At E16.5, fetal tissues were collected and maternal cholesterol transport and fetal synthesis quantified by isotope enrichments in fetal tissues by GC-MS.

RESULTS

The Lrp2 genotype did not influence maternal-fetal cholesterol transport and fetal cholesterol. However, lowering of maternal plasma cholesterol levels by probucol significantly reduced maternal-fetal cholesterol transport. In the fetal liver, this was associated with increased cholesterol synthesis rates. No indications were found for an interaction between the Lrp2 genotype and maternal probucol treatment.

CONCLUSION

Maternal-fetal cholesterol transport and endogenous fetal cholesterol synthesis depend on maternal cholesterol concentrations but do not involve LRP2 in the second half of murine pregnancy. Our results suggest that the mouse fetus can compensate for decreased maternal cholesterol levels. It remains a relevant question how the delicate system of cholesterol transport and synthesis is regulated in the human fetus and placenta.

Prenatal betaine exposure alleviates corticosterone-induced inhibition of CYP27A1 expression in the liver of juvenile chickens associated with its promoter DNA methylation

Sterol 27-hydroxylase (CYP27A1) plays an important role in cholesterol homeostasis by degrading cholesterol to bile acids. Betaine can alleviate high-fat diet-induced hepatic cholesterol accumulation and maternal betaine treatment programs the hepatic expression of CYP27A1 in offspring. Excessive corticosterone (CORT) exposure causes hepatic cholesterol deposition in chickens, yet it remains unknown whether prenatal betaine modulates CORT-induced cholesterol accumulation in chicken liver later in life and whether it involves epigenetic gene regulation of CYP27A1. In this study, fertilized eggs were injected with saline or betaine at 2.5mg/egg before incubation, and the hatchlings were raised under the same condition till 56days of age followed by 7days of subcutaneous CORT injection. Plasma concentrations of total cholesterol (Tch), HDL- and LDL-cholesterol were significantly increased (P<0.05), after CORT challenge, in both control and betaine groups. However, prenatal betaine exposure prevented CORT-induced increase (P<0.05) in hepatic Tch content. Hepatic expression of cholesterol biosynthesis genes and ACAT1 protein that esterifies cholesterol for storage, were activated in both control and betaine groups upon CORT challenge. However, betaine-treated chickens were protected from CORT-induced repression (P<0.05) in LXR and CYP27A1 expression in the liver. CORT-induced down-regulation of LXR and CYP27A1 coincided with significantly increased (P<0.05) CpG methylation on their promoters, which was significantly ameliorated in betaine-treated chickens. These results suggest that in ovo betaine injection alleviates CORT-induced hepatic cholesterol deposition most probably through epigenetic regulation of CYP27A1 and LXR genes in juvenile chickens.

Modulation of cholesterol transport by maternal hypercholesterolemia in human full-term placenta

The significance of maternal cholesterol transporting to the fetus under normal as well as pathological circumstances is less understood. The objective of this study was to observe the effects of maternal hypercholesterolemia on placental cholesterol transportation. Human full-time placenta, maternal and venous cord blood were sampled at delivery from the pregnant women with serum total cholesterol (TC) concentrations at third trimester higher than 7.25 mM (n = 19) and the pregnant women with normal TC concentrations (n = 19). Serum lipids and expression of genes related to cholesterol transportation were measured by western blot or real-time PCR. The results indicated that serum TC, high density lipoprotein cholesterol (HDL-C), and low density lipoprotein cholesterol (LDL-C) levels were significantly increased, in pregnancies, but decreased in cord blood in hypercholesterolemic group compared to the matched control group. All the subjects were no-drinking, non-smoker, and gestational disease free. The mRNA expression of lipoprotein receptors, including LDLR and VLDLR were significantly increased, while the protein expression of PCSK9 was significantly increased in hypercholesterolemic placenta. In conclusion, maternal hypercholesterolemia might decrease the transportation of cholesterol from mother to fetus because of the high levels of PCSK9 protein expression.