Maternal Hypercholesterolemia in Pregnancy Associates With Umbilical Vein Endothelial Dysfunction

Excessive hypercholesterolaemia during pregnancy as a risk factor for endothelial dysfunction in pre-eclampsia

Pregnancy induces significant changes in the maternal cardiovascular system, and insufficient vascular endothelial adaptations to pregnancy contribute to the development of pregnancy complications such as pre-eclampsia. Pre-eclampsia is not only a major cause of maternal morbidity and mortality, but also a significant risk factor for the development of later-life cardiovascular disease. However, the specific mechanisms underlying the pathophysiology of pre-eclampsia, as well as the mechanisms for an increased susceptibility to cardiovascular disease later in life, are not fully characterized. In this review, we discuss the concept that excessive pregnancy-specific dyslipidaemia, particularly hypercholesterolaemia, is a significant risk factor for the development of pre-eclampsia. We further outline novel potential mechanisms (i.e. oxidized low-density lipoprotein receptor 1 and toll-like receptor 4) underlying endothelial dysfunction induced by excessively high cholesterol levels during pregnancy (in the context of pre-eclampsia), in addition to discussing the overall implications of having had a pregnancy complicated by pre-eclampsia on later-life maternal vascular health. Determining the mechanisms by which excessive, pregnancy-specific dyslipidaemia/hypercholesterolaemia impact maternal endothelial health in pregnancy, and later in life, will create a window of opportunity to diagnose and develop targeted therapy for a susceptible population of women, aiming to ultimately reduce the societal burden of cardiovascular disease.

Body mass index-dependent association between cholesteryl ester transfer protein variants and atherometabolic risk factors in gestational diabetes mellitus

OBJECTIVE

Gestational diabetes mellitus (GDM) is associated with metabolic abnormalities such as an altered serum lipid profile. This study investigated the influence of polymorphisms in the lipid metabolism-related cholesteryl ester transfer protein gene (CETP) on the metabolic parameters of pregnant women with GDM.

METHODS

This prospective case-control study included 665 women with GDM and 1,044 women with uncomplicated pregnancies. The PCR-restriction fragment length polymorphism method was used to genotype rs708272 and rs1800775 single nucleotide polymorphisms (SNPs). Lipid and glucose metabolic parameters were assessed. Genetic associations with related traits were analyzed.

RESULTS

Genotype distributions of rs708272 and rs1800775 in patients with GDM were similar to those in normal controls. However, the two CETP SNPs were associated with altered plasma total cholesterol (TC), high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol (LDL-C) concentrations in patients with GDM and in control pregnant women. Additional subgroup analysis demonstrated that the rs708272 polymorphism was associated with variations in triglyceride (TGs), TC, LDL-C, and apolipoprotein B (ApoB) levels in patients with overweight or obesity GDM, whereas both polymorphisms were associated with glucose metabolic traits (plasma insulin, glucose, or insulin) and the insulin resistance index in patients with GDM without obesity.

CONCLUSIONS

In patients with GDM, the rs708272 polymorphism was associated with atherogenic lipid levels (TG, TC, LDL-C, and ApoB), whereas the rs708272 and rs1800775 polymorphisms were associated with glucose metabolism and insulin resistance parameters, which were influenced by the body mass index. These results suggest that genetic associations with atherogenic metabolic factors may increase the risk of adverse outcomes in mothers with GDM and their offspring.

Gestational cholestyramine treatment protects adult offspring of ApoE-deficient mice against maternal-hypercholesterolemia-induced atherosclerosis

AIM

Perinatal hypercholesterolemia exacerbates the development of atherosclerotic plaques in adult offspring. Here, we aimed to study the effect of maternal treatment with cholestyramine, a lipid-lowering drug, on atherosclerosis development in adult offspring of hypercholesterolemic ApoE-deficient (ApoE-/-) mice.

METHODS

ApoE-/- mice were treated with 3% cholestyramine (CTY) during gestation (G). After weaning, offspring (CTY-G) were fed control diet until sacrificed at 25weeks of age. Atherosclerosis development in the aortic root of offspring was assessed after oil-red-o staining, along with some of predefined atherosclerosis regulators such as LDL and HDL by high-performance liquid chromatography (HPLC), and bile acids (BA) and trimethylamine N-oxide (TMAO) by liquid chromatography-mass spectrometry (LC-MS/MS).

RESULTS

In pregnant dams, cholestyramine treatment resulted in significantly lower plasma total- and LDL-cholesterol as well as gallbladder total BA levels. In offspring, both males and females born to treated dams displayed reduced atherosclerotic plaques areas along with less lipid deposition in the aortic root. No significant change in plasma total cholesterol or triglycerides was measured in offspring, but CTY-G males had increased HDL-cholesterol and decreased apolipoproteins B100 to A-I ratio. This latter group also showed reduced gallbladder total and specifically tauro-conjugated bile acid pools, whereas for CTY-G females, hydrophilic plasma tauro-conjugated BA pool was significantly higher. They also benefited from lower plasma TMAO.

CONCLUSION

Prenatal cholestyramine treatment reduces atherosclerosis development in adult offspring of ApoE-/- mice along with modulating the plaques' composition as well as some related biomarkers such as HDL-C, bile acids and TMAO.

Excessive hypercholesterolemia in pregnancy impairs rat uterine artery function via activation of Toll-like receptor 4

Hypercholesterolemia in pregnancy is a physiological process required for normal fetal development. In contrast, excessive pregnancy-specific hypercholesterolemia increases the risk of complications, such as preeclampsia. However, the underlying mechanisms are unclear. Toll-like receptor 4 (TLR4) is a membrane receptor modulated by high cholesterol levels, leading to endothelial dysfunction; but whether excessive hypercholesterolemia in pregnancy activates TLR4 is not known. We hypothesized that a high cholesterol diet (HCD) during pregnancy increases TLR4 activity in uterine arteries, leading to uterine artery dysfunction. Sprague Dawley rats were fed a control diet (n=12) or HCD (n=12) during pregnancy (gestational day 6-20). Vascular function was assessed in main uterine arteries using wire myography (vasodilation to methacholine and vasoconstriction to phenylephrine; with and without inhibitors for mechanistic pathways) and pressure myography (biomechanical properties). Exposure to a HCD during pregnancy increased maternal blood pressure, induced proteinuria, and reduced the fetal-to-placental weight ratio for both sexes. Excessive hypercholesterolemia in pregnancy also impaired vasodilation to methacholine in uterine arteries, whereby at higher doses, methacholine caused vasoconstriction instead of vasodilation in only the HCD group, which was prevented by inhibition of TLR4 or prostaglandin H synthase 1. Endothelial nitric oxide synthase expression and nitric oxide levels were reduced in HCD compared with control dams. Vasoconstriction to phenylephrine and biomechanical properties were similar between groups. In summary, excessive hypercholesterolemia in pregnancy impairs uterine artery function, with TLR4 activation as a key mechanism. Thus, TLR4 may be a target for therapy development to prevent adverse perinatal outcomes in complicated pregnancies.

Evidence for hypoxia-induced dysregulated cholesterol homeostasis in preeclampsia: Insights into the mechanisms from human placental cells and tissues

Preeclampsia (PE) poses a considerable risk to the long-term cardiovascular health of both mothers and their offspring due to a hypoxic environment in the placenta leading to reduced fetal oxygen supply. Cholesterol is vital for fetal development by influencing placental function. Recent findings suggest an association between hypoxia, disturbed cholesterol homeostasis, and PE. This study investigates the influence of hypoxia on placental cholesterol homeostasis. Using primary human trophoblast cells and placentae from women with PE, various aspects of cholesterol homeostasis were examined under hypoxic and hypoxia/reoxygenation (H/R) conditions. Under hypoxia and H/R, intracellular total and non-esterified cholesterol levels were significantly increased. This coincided with an upregulation of HMG-CoA-reductase and HMG-CoA-synthase (key genes regulating cholesterol biosynthesis), and a decrease in acetyl-CoA-acetyltransferase-1 (ACAT1), which mediates cholesterol esterification. Hypoxia and H/R also increased the intracellular levels of reactive oxygen species and elevated the expression of hypoxia-inducible factor (HIF)-2α and sterol-regulatory-element-binding-protein (SREBP) transcription factors. Additionally, exposure of trophoblasts to hypoxia and H/R resulted in enhanced cholesterol efflux to maternal and fetal serum. This was accompanied by an increased expression of proteins involved in cholesterol transport such as the scavenger receptor class B type I (SR-BI) and the ATP-binding cassette transporter G1 (ABCG1). Despite these metabolic alterations, mitogen-activated-protein-kinase (MAPK) signaling, a key regulator of cholesterol homeostasis, was largely unaffected. Our findings indicate dysregulation of cholesterol homeostasis at multiple metabolic points in both the trophoblast hypoxia model and placentae from women with PE. The increased cholesterol efflux and intracellular accumulation of non-esterified cholesterol may have critical implications for both the mother and the fetus during pregnancy, potentially contributing to an elevated cardiovascular risk later in life.

Maternal Supraphysiological Hypercholesterolemia Is Accompanied by Shifts in the Composition and Anti-Atherogenic Functions of Maternal HDL along with Maternal Cardiovascular Risk Markers at Term of Pregnancy

BACKGROUND

Maternal physiological hypercholesterolemia (MPH) occurs in pregnancy for a proper fetal development. When cholesterol increases over the physiological range, maternal supraphysiological hypercholesterolemia (MSPH) is described, a condition underdiagnosed by a lack of evidence showing its biological and clinical relevance.

AIM

To determine if MSPH associates with maternal vascular dysfunction, along with changes in the composition and function of maternal HDL leading to increased cardiovascular risk.

METHODS

This study included 57 women at term of pregnancy in which a lipid profile was determined.

RESULTS

Maternal total cholesterol (TC) and LDL but not HDL were increased in MSPH women. The isolated HDL from a subgroup of MSPH women had a lower protein abundance and a reduced activity of the antioxidant enzyme PON1; however, an increased antioxidant capacity compared to MPH was observed, along with higher serum levels of α-tocopherol. Moreover, HDL from a subgroup of MSPH women had a lower capacity to induce NO synthesis in endothelial cells compared to MPH. In the circulation, we observed a reduced total antioxidant capacity and augmented levels of soluble VCAM, ApoB, ApoCII, ApoCIII, IL-10, and IL-12p70, as well as the cardiovascular risk ratio ApoB/ApoAI, compared to MPH women.

CONCLUSION

MSPH women present dysfunctional HDL and increased atherogenic cardiovascular risk factors.

Small extracellular vesicles from pregnant women with maternal supraphysiological hypercholesterolemia impair endothelial cell function in vitro

Maternal physiological hypercholesterolemia (MPH, maternal total cholesterol (TC) levels at term of pregnancy ≤280 mg/dl) occurs to assure fetal development. Maternal supraphysiological hypercholesterolemia (MSPH, TC levels >280 mg/dl) is a pathological condition associated with maternal, placental, and fetal endothelial dysfunction and early neonatal atherosclerosis development. Small extracellular vesicles (sEVs) are delivered to the extracellular space by different cells, where they modulate cell functions by transporting active signaling molecules, including proteins and miRNA.

AIM

To determine whether sEVs from MSPH women could alter the function of endothelial cells (angiogenesis, endothelial activation and nitric oxide synthesis capacity).

METHODS

This study included 24 Chilean women (12 MPH and 12 MSPH). sEVs were isolated from maternal plasma and characterized by sEV markers (CD9, Alix and HSP70), nanoparticle tracking analysis, transmission electron microscopy, and protein and cholesterol content. The endothelial cell line HMEC-1 was used to determine the uptake of labeled sEVs and the effects of sEVs on cell viability, endothelial tube formation, endothelial cell activation, and endothelial nitric oxide expression and function.

RESULTS

In MSPH women, the plasma concentration of sEVs was increased compared to that in MPH women. MSPH-sEVs were highly taken up by HMEC-1 cells and reduced angiogenic capacity and the expression and activity of eNOS without changing cell viability or endothelial activation.

CONCLUSION

sEVs from MSPH women impair angiogenesis and nitric oxide synthesis in endothelial cells, which could contribute to MSPH-associated endothelial dysfunction.

Variation in placental microRNA expression associates with maternal family history of cardiovascular disease

In the United States, cardiovascular disease is the leading cause of death and the rate of maternal mortality remains among the highest of any industrialized nation. Maternal cardiometabolic health throughout gestation and postpartum is representative of placental health and physiology. Both proper placental functionality and placental microRNA expression are essential to successful pregnancy outcomes, and both are highly sensitive to genetic and environmental sources of variation. Placental pathologies, such as preeclampsia, are associated with maternal cardiovascular health but may also contribute to the developmental programming of chronic disease in offspring. However, the role of more subtle alterations to placental function and microRNA expression in this developmental programming remains poorly understood. We performed small RNA sequencing to investigate microRNA in placentae from the Rhode Island Child Health Study (n = 230). MicroRNA counts were modeled on maternal family history of cardiovascular disease using negative binomial generalized linear models. MicroRNAs were considered to be differentially expressed at a false discovery rate (FDR) less than 0.10. Parallel mRNA sequencing data and bioinformatic target prediction software were then used to identify potential mRNA targets of differentially expressed microRNAs. Nine differentially expressed microRNAs were identified (FDR < 0.1). Bioinformatic target prediction revealed 66 potential mRNA targets of these microRNAs, many of which are implicated in TGFβ signaling pathway but also in pathways involving cellular metabolism and immunomodulation. A robust association exists between familial cardiovascular disease and placental microRNA expression which may be implicated in both placental insufficiencies and the developmental programming of chronic disease.

Lipid Metabolic Genes and Maternal Supraphysiological Hypercholesterolemia: An Analysis of Maternal-fetal Interaction

CONTEXT

The joint associations of maternal and fetal single nucleotide polymorphisms (SNPs) of lipid metabolic genes with the risk of maternal supraphysiological hypercholesterolemia (MSPH) are unclear.

OBJECTIVE

This study aims to investigate the associations of maternal/fetal SNPs of APOE, LPL, LDLR, PCSK9, and SCARB1 with the risk of MSPH and explore whether the maternal-fetal pairing pattern of the risk alleles can affect MSPH risk.

METHODS

A nested case-control study was conducted that included 182 pregnant women with MSPH and 182 with maternal physiological hypercholesterolemia. Maternal venous and umbilical venous blood were collected to detect the SNPs of genes. The primary outcome was MSPH. Logistic regression model was used to determine the associations of SNPs with risk of MSPH.

RESULTS

The C-allele in maternal APOE rs429358 T > C (adjusted odds ratio [OR] = 1.72, P = 0.033), G-allele in fetal APOE rs440446 C > G (adjusted OR = 1.62, P = 0.012) and T-allele in fetal LPL rs263 C > T (adjusted OR = 1.53, P = 0.011) increased the risk of MSPH. The A-allele in maternal LDLR rs7258950 G > A decreased the risk of MSPH (adjusted OR = 0.67, P = 0.028). For maternal-fetal pairing analysis, the variant concordance of PCSK9 rs2149041, rs7523141, rs7523242, rs7525649, and LDLR rs7258950 were associated with the decreased risk of MSPH under the dominant model. The variant concordance of other SNPs of PCSK9, APOE, LDLR, LPL, and SCARB1 were associated with the increased risk of MSPH.

CONCLUSION

This study supports the hypothesis that maternal and fetal genetic polymorphisms of lipid metabolic genes are associated with the risk of MSPH. The maternal-fetal variant concordance is also associated with this risk.

Increased Circulating Levels of PCSK9 and Pro-Atherogenic Lipoprotein Profile in Pregnant Women with Maternal Supraphysiological Hypercholesterolemia

Maternal physiological hypercholesterolemia (MPH) occurs during pregnancy to assure fetal development. Some pregnant women develop maternal supraphysiological hypercholesterolemia (MSPH) characterized by increased levels of low-density lipoprotein (LDL). We aim to determine if proprotein convertase subtilisin/kexin type 9 (PCSK9) levels (a protein that regulate the availability of LDL receptor in the cells surface), as well as the composition and function of LDL, are modulated in MSPH women. This study included 122 pregnant women. Maternal total cholesterol (TC), LDL, triglycerides and PCSK9 increased from first (T1) to third trimester (T3) in MPH women. At T3, maternal TC, LDL, PCSK9 and placental abundances of PCSK9 were significantly higher in MPSH compared to MPH. Circulating PCSK9 levels were correlated with LDL at T3. In MSPH women, the levels of lipid peroxidation and oxidized LDL were significantly higher compared to MPH. LDL isolated from MSPH women presented significantly higher triglycerides and ApoB but lower levels of ApoAI compared to MPH. The formation of conjugated dienes was earlier in LDL from MSPH and in endothelial cells incubated with these LDLs; the levels of reactive oxygen species were significantly higher compared to LDL from MPH. We conclude that increased maternal PCSK9 would contribute to the maternal elevated levels of pro-atherogenic LDL in MSPH, which could eventually be related to maternal vascular dysfunction.

Human Placental Intracellular Cholesterol Transport: A Focus on Lysosomal and Mitochondrial Dysfunction and Oxidative Stress

The placenta participates in cholesterol biosynthesis and metabolism and regulates exchange between the maternal and fetal compartments. The fetus has high cholesterol requirements, and it is taken up and synthesized at elevated rates during pregnancy. In placental cells, the major source of cholesterol is the internalization of lipoprotein particles from maternal circulation by mechanisms that are not fully understood. As in hepatocytes, syncytiotrophoblast uptake of lipoprotein cholesterol involves lipoprotein receptors such as low-density lipoprotein receptor (LDLR) and scavenger receptor class B type I (SR-BI). Efflux outside the cells requires proteins such as the ATP-binding cassette (ABC) transporters ABCA1 and ABCG1. However, mechanisms associated with intracellular traffic of cholesterol in syncytiotrophoblasts are mostly unknown. In hepatocytes, uptaken cholesterol is transported to acidic late endosomes (LE) and lysosomes (LY). Proteins such as Niemann–Pick type C 1 (NPC1), NPC2, and StAR related lipid transfer domain containing 3 (STARD3) are required for cholesterol exit from the LE/LY. These proteins transfer cholesterol from the lumen of the LE/LY into the LE/LY-limiting membrane and then export it to the endoplasmic reticulum, mitochondria, or plasma membrane. Although the production, metabolism, and transport of cholesterol in placental cells are well explored, there is little information on the role of proteins related to intracellular cholesterol traffic in placental cells during physiological or pathological pregnancies. Such studies would be relevant for understanding fetal and placental cholesterol management. Oxidative stress, induced by generating excess reactive oxygen species (ROS), plays a critical role in regulating various cellular and biological functions and has emerged as a critical common mechanism after lysosomal and mitochondrial dysfunction. This review discusses the role of cholesterol, lysosomal and mitochondrial dysfunction, and ROS in the development and progression of hypercholesterolemic pregnancies.

Increased Fetal Cardiovascular Disease Risk: Potential Synergy Between Gestational Diabetes Mellitus and Maternal Hypercholesterolemia

Cardiovascular diseases (CVD) remain a major cause of death worldwide. Evidence suggests that the risk for CVD can increase at the fetal stages due to maternal metabolic diseases, such as gestational diabetes mellitus (GDM) and maternal supraphysiological hypercholesterolemia (MSPH). GDM is a hyperglycemic, inflammatory, and insulin-resistant state that increases plasma levels of free fatty acids and triglycerides, impairs endothelial vascular tone regulation, and due to the increased nutrient transport, exposes the fetus to the altered metabolic conditions of the mother. MSPH involves increased levels of cholesterol (mainly as low-density lipoprotein cholesterol) which also causes endothelial dysfunction and alters nutrient transport to the fetus. Despite that an association has already been established between MSPH and increased CVD risk, however, little is known about the cellular processes underlying this relationship. Our knowledge is further obscured when the simultaneous presentation of MSPH and GDM takes place. In this context, GDM and MSPH may substantially increase fetal CVD risk due to synergistic impairment of placental nutrient transport and endothelial dysfunction. More studies on the separate and/or cumulative role of both processes are warranted to suggest specific treatment options.

High total cholesterol and triglycerides levels increase arginases metabolism, impairing nitric oxide signaling and worsening fetoplacental endothelial dysfunction in gestational diabetes mellitus pregnancies

During human pregnancy, maternal physiological dyslipidemia (MPD) supports fetal development. However, some women develop maternal supraphysiological dyslipidemia (MSPD: increased total cholesterol (TC) and triglycerides (TG) levels). MSPD is present in normal and pregnancies with gestational diabetes mellitus (GDM). Both pathologies associate with fetoplacental endothelial dysfunction, producing alterations in nitric oxide (NO)-L-arginine/arginase metabolism. Nevertheless, the effect of MSPD on GDM, and how this synergy alters fetoplacental endothelial function is unknown, which is the aim of this study. 123 women at term of pregnancy were classified as MPD (n=40), MSPD (n=35), GDM with normal lipids (GDM- MPD, n=23) and with increased lipids (GDM-MSPD, n=25). TC ≥291 mg/dL and TG ≥275 mg/dL were considered as MSPD. Endothelial NO synthase (eNOS), human cationic amino acid transporter 1 (hCat1), and arginase II protein abundance and activity, were assayed in umbilical vein endothelial cells. In MSPD and MSPD-GDM, TC and TG increased respect to MPD and MPD-GDM. eNOS activity was reduced in MSPD and MSPD-GDM, but increased in MPD-GDM compared with MPD. No changes were observed in eNOS protein. However, decreased tetrahydrobiopterin levels were observed in all groups compared with MPD. Increased hCat1 protein and L-arginine transport were observed in both GDM groups compared with MPD. However, the transport was higher in GDM-MSPD compared to GDM-MPD. Higher Arginase II protein and activity were observed in MSPD-GDM compared with MPD. Thus, MSPD in GDM pregnancies alters fetal endothelial function associated with NO metabolism.

Maternal first antenatal care visit biometric indices as potential predictors of umbilical cord morphometric parameters

BACKGROUND

One key factor proven to increase quality of pregnancy outcome has been antenatal care (ANC) service. The perinatal triad of mother, placenta and fetus becomes functionally complete with a functional umbilical cord. The objective of the study was to establish mathematical models to predict the outcome of umbilical cord morphometric parameters using maternal first antenatal care visit biometric indices.

METHOD

This analytical descriptive cross-sectional study was conducted on 240 pregnant women who attended antenatal care for the first time in their first trimester at the Victory Maternity Home and Clinic in the Kumasi Metropolis, between April 2016 and October 2019. Umbilical cord length, diameter, area, volume and weight were measured after delivery. Maternal first antenatal care visit blood pressure was taken and their non-fasting blood samples were collected and lipid profile done.

RESULTS

Mean values for umbilical cord measurements were; cord length, 38.10±7.86 cm; diameter, 1.04±0.17 cm; area, 66.10±24.49 cm2 and volume was 34.02±11.16 cm3 respectively while mean cord weight was 65.01±21.35 g. The study found that a unit increase in total cholesterol led to an increase of 2.33 units in umbilical cord length, high-density lipoprotein also resulted in 0.06 units increase in cord diameter while low-density lipoprotein decreases cord length by 3.31 units. Also, a unit increase in maternal booking total cholesterol resulted in 2.33 units increase in umbilical cord length.

CONCLUSION

Maternal first antenatal care visit total cholesterol, high-density lipoprotein and low-density lipoprotein could influence the outcome of umbilical cord length, diameter and area.

Effects of lipoproteins on endothelial cells and macrophages function and its possible implications on fetal adverse outcomes associated to maternal hypercholesterolemia during pregnancy

Hypercholesterolemia is one of the main risk factors associated with atherosclerosis and cardiovascular disease, the leading cause of death worldwide. During pregnancy, maternal hypercholesterolemia develops, and it can occur in a physiological (MPH) or supraphysiological (MSPH) manner, where MSPH is associated with endothelial dysfunction and early atherosclerotic lesions in the fetoplacental vasculature. In the pathogenesis of atherosclerosis, endothelial activation and endothelial dysfunction, characterized by an imbalance in the bioavailability of nitric oxide, contribute to the early stages of this disease. Macrophages conversion to foam cells, cholesterol efflux from these cells and its differentiation into a pro- or anti-inflammatory phenotype are also important processes that contribute to atherosclerosis. In adults it has been reported that native and modified HDL and LDL play an important role in endothelial and macrophage function. In this review it is proposed that fetal lipoproteins could be also relevant factors involved in the detrimental vascular effects described in MSPH. Changes in the composition and function of neonatal lipoproteins compared to adults has been reported and, although in MSPH pregnancies the fetal lipid profile does not differ from MPH, differences in the lipidomic profiles of umbilical venous blood have been reported, which could have implications in the vascular function. In this review we summarize the available information regarding the effects of lipoproteins on endothelial and macrophage function, emphasizing its possible implications on fetal adverse outcomes associated to maternal hypercholesterolemia during pregnancy.

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 polarized localization of lipoprotein receptors and cholesterol transporters in the syncytiotrophoblast of the placenta is reproducible in a monolayer of primary human trophoblasts

INTRODUCTION

The uptake of low- and high-density lipoproteins (LDL and HDL) through the LDL receptor (LDLR) and the scavenger receptor class B type I (SR-BI) mediates maternal to fetal cholesterol transfer in syncytiotrophoblast (STB) cells. STB cells deliver cholesterol via cholesterol efflux through the ATP-binding cassette transporters A1 (ABCA1, to ApoA-I), G1 (ABCG1, to HDL), and SR-BI (to HDL). In the human placenta, these proteins are localized in the apical (LDLR, SR-BI, ABCA1) and basal (SR-BI, ABCA1, ABCG1) membrane of STB cells. However, whether these proteins in polarized primary culture models of STB show a similar localization to those in the human placenta is currently unknown.

METHODS

Primary human trophoblasts (PHT) were isolated from normal placentas and cultured in Transwells® with Matrigel to obtain a polarized STB monolayer, proteins were determined by immunofluorescence and cholesterol efflux determined to different acceptors.

RESULTS

At day 5, LDLR and ABCA1 localized mainly in the apical membrane, ABCG1 in the basal membrane, and SR-BI in both. Cholesterol efflux towards the apical compartment was higher to adult and neonatal HDL compared to ApoA-I. When acceptors were added in the basal compartment, cholesterol was retained in the Matrigel.

DISCUSSION

Polarized STB monolayers express LDLR, SR-BI, ABCA1 and ABCG1, and their apical/basal localization resembles the one described in human placental tissue. This study confirms the high physiological value and suitability of this model for use in functional studies. Our findings also suggest that ABCA1 and SR-BI participate in cholesterol efflux to the maternal side of the cells.

Associations of maternal metabolic profile with placental and fetal cerebral and cardiac hemodynamics

OBJECTIVE

Maternal obesity and metabolic health affect pregnancy outcomes. We examined whether maternal metabolic profiles are associated with placental and fetal hemodynamics.

STUDY DESIGN

In a population-based prospective cohort study among 1175 women we examined the associations of an adverse maternal metabolic profile in early pregnancy with placental, fetal cerebral and cardiac hemodynamic development. We obtained maternal pre-pregnancy BMI by questionnaire and measured blood pressure, cholesterol, triglycerides and glucose concentrations at a median gestational age of 12.6 (95 % range 9.6-17.1) weeks. An adverse maternal metabolic profile was defined as ≥4 risk factors. Placental and fetal hemodynamics were measured by pulsed-wave-Doppler at a median gestational age of 30.3 (95 % range 28.8-32.3) weeks.

RESULTS

An adverse maternal metabolic profile was associated with a 0.29 Z-score higher (95 %CI 0.08-0.50) fetal cerebral middle artery pulsatility index (PI), but not with placental or fetal cardiac hemodynamic patterns. When the individual components of an adverse maternal metabolic profile were assessed, we observed that higher maternal total cholesterol and triglyceride concentrations were associated with a higher cerebral middle artery PI (Z-score, 0.09 (95 %CI 0.02-0.15), 0.09 (95 %CI 0.03-0.15) per Z-score increase). Higher total and HDL maternal cholesterol concentrations were also associated with a higher aorta ascendens peak systolic velocity (PSV) Z-score, 0.08 (95 %CI 0.01-0.14)), and a larger left cardiac output (Z-score, 0.08 (95 %CI 0.00-0.15), respectively).

CONCLUSION

An adverse maternal metabolic profile, especially higher cholesterol and triglycerides concentrations, are associated with increased fetal cerebral vascular resistance and larger fetal aorta ascendens diameter, PSV and left cardiac output, but not with placental vascular resistance indices. Further studies are needed to identify long-term consequences of the observed associations.

Dyslipemias and pregnancy, an update

During pregnancy there is a physiological increase in total cholesterol (TC) and triglycerides (TG) plasma concentrations, due to increased insulin resistance, oestrogens, progesterone, and placental lactogen, although their reference values are not exactly known, TG levels can increase up to 300mg/dL, and TC can go as high as 350mg/dL. When the cholesterol concentration exceeds the 95^th percentile (familial hypercholesterolaemia (FH) and transient maternal hypercholesterolaemia), there is a predisposition to oxidative stress in foetal vessels, exposing the newborn to a greater fatty streaks formation and a higher risk of atherosclerosis. However, the current treatment of pregnant women with hyperlipidaemia consists of a diet and suspension of lipid-lowering drugs. The most prevalent maternal hypertriglyceridaemia (HTG) is due to secondary causes, like diabetes, obesity, drugs, etc. The case of severe HTG due to genetic causes is less prevalent, and can be a higher risk of maternal-foetal complications, such as, acute pancreatitis (AP), pre-eclampsia, preterm labour, and gestational diabetes. Severe HTG-AP is a rare but potentially lethal pregnancy complication, for the mother and the foetus, usually occurs during the third trimester or in the immediate postpartum period, and there are no specific protocols for its diagnosis and treatment. In conclusion, it is crucial that dyslipidaemia during pregnancy must be carefully evaluated, not just because of the acute complications, but also because of the future cardiovascular morbidity and mortality of the newborn child. That is why the establishment of consensus protocols or guidelines is essential for its management.

Excessive early-life cholesterol exposure may have later-life consequences for nonalcoholic fatty liver disease

The in utero and immediate postnatal environments are recognized as critical windows of developmental plasticity where offspring are highly susceptible to changes in the maternal metabolic milieu. Maternal hypercholesterolemia (MHC) is a pathological condition characterized by an exaggerated rise in maternal serum cholesterol during pregnancy which can program metabolic dysfunction in offspring, including dysregulation of hepatic lipid metabolism. Although there is currently no established reference range MHC, a loosely defined cutoff point for total cholesterol >280 mg/dL in the third trimester has been suggested. There are several unanswered questions regarding this condition particularly with regard to how the timing of cholesterol exposure influences hepatic lipid dysfunction and the mechanisms through which these adaptations manifest in adulthood. Gestational hypercholesterolemia increased fetal hepatic lipid concentrations and altered lipid regulatory mRNA and protein content. These early changes in hepatic lipid metabolism are evident in the postweaning environment and persist into adulthood. Further, changes to hepatic epigenetic signatures including microRNA (miR) and DNA methylation are observed in utero, at weaning, and are evident in adult offspring. In conclusion, early exposure to cholesterol during critical developmental periods can predispose offspring to the early development of nonalcoholic fatty liver disease (NAFLD) which is characterized by altered regulatory function beginning in utero and persisting throughout the life cycle.

Cholesterol uptake and efflux are impaired in human trophoblast cells from pregnancies with maternal supraphysiological hypercholesterolemia

Maternal physiological (MPH) or supraphysiological hypercholesterolaemia (MSPH) occurs during pregnancy. Cholesterol trafficking from maternal to foetal circulation requires the uptake of maternal LDL and HDL by syncytiotrophoblast and cholesterol efflux from this multinucleated tissue to ApoA-I and HDL. We aimed to determine the effects of MSPH on placental cholesterol trafficking. Placental tissue and primary human trophoblast (PHT) were isolated from pregnant women with total cholesterol <280 md/dL (MPH, n = 27) or ≥280 md/dL (MSPH, n = 28). The lipid profile in umbilical cord blood from MPH and MSPH neonates was similar. The abundance of LDL receptor (LDLR) and HDL receptor (SR-BI) was comparable between MSPH and MPH placentas. However, LDLR was localized mainly in the syncytiotrophoblast surface and was associated with reduced placental levels of its ligand ApoB. In PHT from MSPH, the uptake of LDL and HDL was lower compared to MPH, without changes in LDLR and reduced levels of SR-BI. Regarding cholesterol efflux, in MSPH placentas, the abundance of cholesterol transporter ABCA1 was increased, while ABCG1 and SR-BI were reduced. In PHT from MSPH, the cholesterol efflux to ApoA-I was increased and to HDL was reduced, along with reduced levels of ABCG1, compared to MPH. Inhibition of SR-BI did not change cholesterol efflux in PHT. The TC content in PHT was comparable in MPH and MSPH cells. However, free cholesterol was increased in MSPH cells. We conclude that MSPH alters the trafficking and content of cholesterol in placental trophoblasts, which could be associated with changes in the placenta-mediated maternal-to-foetal cholesterol trafficking.

Gestational Diabetes Mellitus Treatment Schemes Modify Maternal Plasma Cholesterol Levels Dependent to Women´s Weight: Possible Impact on Feto-Placental Vascular Function

: Gestational diabetes mellitus (GDM) associates with fetal endothelial dysfunction (ED), which occurs independently of adequate glycemic control. Scarce information exists about the impact of different GDM therapeutic schemes on maternal dyslipidemia and obesity and their contribution to the development of fetal-ED. The aim of this study was to evaluate the effect of GDM-treatments on lipid levels in nonobese (N) and obese (O) pregnant women and the effect of maternal cholesterol levels in GDM-associated ED in the umbilical vein (UV). O-GDM women treated with diet showed decreased total cholesterol (TC) and low-density lipoproteins (LDL) levels with respect to N-GDM ones. Moreover, O-GDM women treated with diet in addition to insulin showed higher TC and LDL levels than N-GDM women. The maximum relaxation to calcitonin gene-related peptide of the UV rings was lower in the N-GDM group compared to the N one, and increased maternal levels of TC were associated with even lower dilation in the N-GDM group. We conclude that GDM-treatments modulate the TC and LDL levels depending on maternal weight. Additionally, increased TC levels worsen the GDM-associated ED of UV rings. This study suggests that it could be relevant to consider a specific GDM-treatment according to weight in order to prevent fetal-ED, as well as to consider the possible effects of maternal lipids during pregnancy.

Maternal lipid profiles vs. fetal growth and cord blood hematopoietic cells: weak associations in healthy Korean newborn-mother pairs

BACKGROUND

We aimed to define the maternal lipid profiles that are associated with fetal growth and cord blood (CB) hematopoietic cells in healthy Korean full-term newborns.

METHODS

A total of 608 fetal-maternal pairs were enrolled; mothers voluntarily donated CB with informed consent. We analyzed birth weight (BW) as a marker of fetal growth, and we examined total nucleated cells (TNCs) and CD34⁺ cell concentrations of CB as markers of hematopoietic progenitor cell (HPC) contents. We also analyzed maternal lipid levels and investigated their associations with BW, TNCs and CD34⁺ cells.

RESULTS

Maternal triglycerides (TG) showed a significant positive association with BW and CD34⁺ cells, and low-density lipoprotein (LDL) showed a negative association with BW and CD34⁺ cells. Though not statistically significant, higher maternal TG showed a tendency toward higher levels of TNCs. Maternal TG was independently and positively correlated with BW, and maternal LDL was independently and negatively correlated with CD34⁺ cells, although the impacts were not as strong, as indicated by small beta coefficients (0.157 and -0.226, respectively).

CONCLUSIONS

We were able to investigate the association of maternal lipid profiles with BW and CB HPCs in healthy Korean newborn-mother pairs in this study. Both BW and the HPC contents showed independent associations with maternal TG and LDL, although the effect of maternal lipid levels on fetal growth and HPCs was not strong in the normal healthy population. Because maternal lipid levels were assessed once in the healthy fetal-maternal pairs, we could not investigate those associations across pregnancy.

Malprogramming of Hepatic Lipid Metabolism due to Excessive Early Cholesterol Exposure in Adult Progeny

SCOPE

The programming of hepatic lipid dysfunction in response to early cholesterol exposure and the influencing effects of postnatal diet is evaluated in apoE^-/- mice.

METHODS AND RESULTS

In two separate studies, female mice are assigned to a standard chow (S) or a cholesterol-enriched chow (C) diet during gestation and lactation. Male offspring from each dam are weaned on a postnatal S or a hypercaloric western (W) diet resulting in four experimental groups: S-S and C-S (Experiment 1) and S-W and C-W (Experiment 2). At weaning, litters from hypercholesterolemic mothers weighed less (p < 0.05) and pups had higher blood lipids, glucose, and hepatic cholesterol compared with pups from S-fed mothers. Adult C-S offspring demonstrate an atherogenic lipid profile and increased (p < 0.05) hepatic cholesterol and triglyceride content with altered lipid regulatory mRNA expression and protein content compared with S-S offspring. Alternatively, no difference (p > 0.05) is observed between S-W and C-W in serum and hepatic lipid profiles; however, serum AST and ALT are higher (p < 0.05) in C-W versus S-W offspring.

CONCLUSION

The degree of hepatic lipid deposition observed in adult offspring exposed to excessive early cholesterol is influenced by the postnatal diet.

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.

Pre-pregnancy maternal obesity associates with endoplasmic reticulum stress in human umbilical vein endothelium

Obesity associates with the endoplasmic reticulum (ER) stress-induced endothelial dysfunction. Pregnant women with pre-pregnancy maternal obesity (PGMO) may transfer this potential risk to their offspring; however, whether ER stress occurs and associates with foetoplacental endothelial dysfunction in PGMO is unknown. We studied the l-arginine transport and nitric oxide (NO) synthesis in human umbilical vein endothelial cells (HUVECs) from women with PGMO or with a normal pre-pregnancy weight. We analysed the expression and activation of the ER stress sensors protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1α (IRE1α), and activating transcription factor 6 (ATF6). PGMO associated with lower endothelial NO synthase activity due to increased Thr⁴⁹⁵-inhibitor and decreased Ser¹¹⁷⁷-stimulator phosphorylation. However, higher expression and activity of the human cationic amino acid transporter 1 was found. PGMO caused activation of PERK and its downstream targets eukaryotic initiation factor 2 (eIF2α), C/EBP homologous protein 10 (CHOP), and tribbles-like protein 3 (TRB3). Increased IRE1α protein abundance (but not its phosphorylation or X-box binding protein 1-mRNA splicing) and increased c-Jun N-terminal kinase 1 phosphorylation was seen in PGMO. A preferential nuclear location of the activating transcription factor 6 (ATF6) was found in HUVECs from PGMO. All the changes seen in PGMO were blocked by TUDCA but unaltered by tunicamycin. Thus, PGMO may determine a state of ER stress via upregulation of the PERK-eIF2α-CHOP-TRB3 axis signalling in HUVECs. This phenomenon results in foetoplacental vascular endothelial dysfunction at birth.

Maternal supraphysiological hypercholesterolemia associates with endothelial dysfunction of the placental microvasculature

Maternal physiological or supraphysiological hypercholesterolemia (MPH, MSPH) occurs during pregnancy. MSPH is associated with foetal endothelial dysfunction and atherosclerosis. However, the potential effects of MSPH on placental microvasculature are unknown. The aim of this study was to determine whether MSPH alters endothelial function in the placental microvasculature both ex vivo in venules and arterioles from the placental villi and in vitro in primary cultures of placental microvascular endothelial cells (hPMEC). Total cholesterol < 280 mg/dL indicated MPH, and total cholesterol ≥280 mg/dL indicated MSPH. The maximal relaxation to histamine, calcitonin gene-related peptide and adenosine was reduced in MSPH venule and arteriole rings. In hPMEC from MSPH placentas, nitric oxide synthase (NOS) activity and L-arginine transport were reduced without changes in arginase activity or the protein levels of endothelial NOS (eNOS), human cationic amino acid 1 (hCAT-1), hCAT-2A/B or arginase II compared with hPMEC from MPH placentas. In addition, it was shown that adenosine acts as a vasodilator of the placental microvasculature and that NOS is active in hPMEC. We conclude that MSPH alters placental microvascular endothelial function via a NOS/L-arginine imbalance. This work also reinforces the concept that placental endothelial cells from the macro- and microvasculature respond differentially to the same pathological condition.

Foetoplacental epigenetic changes associated with maternal metabolic dysfunction

Metabolic-related diseases are attributed to a sedentary lifestyle and eating habits, and there is now an increased awareness regarding pregnancy as a preponderant window in the programming of adulthood health and disease. The developing foetus is susceptible to the maternal environment; hence, any unfavourable condition will result in foetal physiological adaptations that could have a permanent impact on its health. Some of these alterations are maintained via epigenetic modifications capable of modifying gene expression in metabolism-related genes. Children born to mothers with dyslipidaemia, pregestational or gestational obesity, and gestational diabetes mellitus, have a predisposition to develop metabolic alterations during adulthood. CpG methylation-associated alterations to the expression of several genes in the human placenta play a crucial role in the mother-to-foetus transfer of nutrients and macromolecules. Identification of epigenetic modifications in metabolism-related tissues of offspring from metabolic-altered pregnancies is essential to obtain insights into foetal programming controlling newborn, childhood, and adult metabolism. This review points out the importance of the foetal milieu in the programming and development of human disease and provides evidence of this being the underlying mechanism for the development of adulthood metabolic disorders in maternal dyslipidaemia, pregestational or gestational obesity, and gestational diabetes mellitus.

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.

Transcriptional control of enterohepatic lipid regulatory targets in response to early cholesterol and phytosterol exposure in apoE-/- mice

OBJECTIVE

An excessive rise in blood lipids during pregnancy may promote metabolic dysfunction in adult progeny. We characterized how maternal phytosterol (PS) supplementation affected serum lipids and the expression of lipid-regulatory genes in the intestine and liver of newly-weaned apo-E deficient offspring from dams fed a chow diet supplemented with cholesterol (0.15%, CH) or cholesterol and PS (2%) (CH/PS) throughout pregnancy and lactation.

RESULTS

Serum lipid concentrations and lipoprotein particle numbers were exacerbated in offspring from cholesterol-supplemented mothers but normalized to chow-fed levels in pups exposed to PS through the maternal diet during gestation and lactation. Compared with the CH pups, pups from PS-supplemented mothers demonstrated higher (p < 0.05) expression of the primary intestinal cholesterol transport protein (Niemann-Pick C1-like 1) and the rate-limiting enzyme in hepatic cholesterol synthesis (HMG-CoAr), suggestive of a compensatory response to restore cholesterol balance. Furthermore, pups from PS-supplemented mothers exhibited a coordinated downregulation (p < 0.05) of several genes regulating fatty acid synthesis including PGC1β, SREBP1c, FAS, and ACC compared with the CH group. These results suggest that maternal PS supplementation during hypercholesterolemic pregnancies protects against aberrant lipid responses in newly-weaned offspring and results in differential regulation of cholesterol and lipid regulatory targets within the enterohepatic loop.

Maternal hypercholesterolemia enhances oxysterol concentration in mothers and newly weaned offspring but is attenuated by maternal phytosterol supplementation

In hypercholesterolemic pregnancies, the maternal environment is characterized by excessive levels of atherogenic lipids that may increase cardiovascular disease risk in mothers and their offspring. We examined the influence of maternal hypercholesterolemia and phytosterol (PS) intervention on the concentration and metabolism of oxysterols, bioactive oxygenated cholesterol derivatives that regulate arterial health and lesion progression, in mothers and their newly weaned offspring. Twenty-one female apoE^-/- mice were randomly assigned to three different diets throughout gestation and lactation: (1) chow, (2) high cholesterol (CH; 0.15%) and (3) CH with added PS (2%, CH/PS). At the end of the lactation period, mothers and pups were euthanized for serum and hepatic oxysterol analyses, hepatic transcriptional profiling of hepatic sterol regulatory targets and atherosclerosis. Hypercholesterolemic dams and their pups demonstrated increased (P˂.05) serum oxysterols [including 24 hydroxycholesterol (HC), 25HC, 27HC, 7αHC, 7βHC and 7 ketocholesterol)] compared with the chow group that were normalized by maternal PS supplementation. Hepatic oxysterol concentrations followed a similar pattern of response in mothers but were not altered in newly weaned pups. Hepatic mRNA expression suggested a pattern of enhanced abca1/g1 high-density-lipoprotein-mediated efflux but a reduction in biliary abcg5/g8 export in both dams and their pups. Although arterial lesions were not apparent in newly weaned pups, CH dams demonstrated enhanced atherosclerosis that was reduced upon PS intervention. These results demonstrate that offspring from hypercholesterolemic pregnancies have enhanced circulating oxysterol concentrations and highlight the potential utility of PS as a lipid-lowering option during hypercholesterolemic pregnancies for which there are currently limited options.

Arginase inhibition improves endothelial function in patients with familial hypercholesterolaemia irrespective of their cholesterol levels

BACKGROUND

Elevated LDL cholesterol is an important risk factor for atherosclerosis. Endothelial dysfunction, an early event in the development of atherosclerosis, is characterized by a reduction in nitric oxide (NO) bioavailability. Arginase has emerged as a key regulator of endothelial function through competition with NO synthase for the common substrate l-arginine. Arginase in endothelial cells is activated by oxidized LDL. The study aim was to investigate the importance of arginase for endothelial dysfunction in patients with familial hypercholesterolaemia (FH).

METHODS AND RESULTS

Endothelial function was evaluated in 12 patients with heterozygous FH and 12 age-matched healthy normocholesterolaemic subjects using forearm venous occlusion plethysmography. The evaluations in FH patients occurred when they were on lipid-lowering therapy and 4 weeks after withdrawal of treatment. Endothelium-dependent vasodilatation (EDV) was assessed by intrabrachial artery infusion of serotonin, and endothelium-independent dilatation was assessed by infusion of nitroprusside before and after 120 min administration of the arginase inhibitor N (ω) -hydroxy-nor-l-arginine (nor-NOHA; 0.1 mg min(-1)). In FH patients LDL cholesterol increased from 4.3 ± 0.9 mmol L(-1) at baseline to 7.6 ± 1.9 mmol L(-1) at follow-up (P < 0.001). Arginase inhibition enhanced EDV in FH patients by a similar degree independent of lipid-lowering therapy. The improvement in EDV by arginase inhibition was significantly greater in FH patients than in the control group.

CONCLUSION

Arginase inhibition results in greater improvement in endothelial function in patients with FH compared to healthy controls irrespective of their cholesterol levels. Arginase may be a promising therapeutic target for improving endothelial function in patients with hypercholesterolaemia.

Role for Tetrahydrobiopterin in the Fetoplacental Endothelial Dysfunction in Maternal Supraphysiological Hypercholesterolemia

Maternal physiological hypercholesterolemia occurs during pregnancy, ensuring normal fetal development. In some cases, the maternal plasma cholesterol level increases to above this physiological range, leading to maternal supraphysiological hypercholesterolemia (MSPH). This condition results in endothelial dysfunction and atherosclerosis in the fetal and placental vasculature. The fetal and placental endothelial dysfunction is related to alterations in the L-arginine/nitric oxide (NO) pathway and the arginase/urea pathway and results in reduced NO production. The level of tetrahydrobiopterin (BH4), a cofactor for endothelial NO synthase (eNOS), is reduced in nonpregnant women who have hypercholesterolemia, which favors the generation of the superoxide anion rather than NO (from eNOS), causing endothelial dysfunction. However, it is unknown whether MSPH is associated with changes in the level or metabolism of BH4; as a result, eNOS function is not well understood. This review summarizes the available information on the potential link between MSPH and BH4 in causing human fetoplacental vascular endothelial dysfunction, which may be crucial for understanding the deleterious effects of MSPH on fetal growth and development.

Immune Mechanisms Linking Obesity and Preeclampsia

Preeclampsia (PE) is characterized by hypertension occurring after the twentieth week of pregnancy. It is a significant contributor to maternal and perinatal morbidity and mortality in developing countries and its pervasiveness is increasing within developed countries including the USA. However, the mechanisms mediating the pathogenesis of this maternal disorder and its rising prevalence are far from clear. A major theory with strong experimental evidence is that placental ischemia, resulting from inappropriate remodeling and widening of the maternal spiral arteries, stimulates the release of soluble factors from the ischemic placenta causing maternal endothelial dysfunction and hypertension. Aberrant maternal immune responses and inflammation have been implicated in each of these stages in the cascade leading to PE. Regarding the increased prevalence of this disease, it is becoming increasingly evident from epidemiological data that obesity, which is a state of chronic inflammation in itself, increases the risk for PE. Although the specific mechanisms whereby obesity increases the rate of PE are unclear, there are strong candidates including activated macrophages and natural killer cells within the uterus and placenta and activation in the periphery of T helper cells producing cytokines including TNF-α, IL-6 and IL-17 and the anti-angiogenic factor sFlt-1 and B cells producing the agonistic autoantibodies to the angiotensin type 1 receptor (AT1-aa). This review will focus on the immune mechanisms that have been implicated in the pathogenesis of hypertension in PE with an emphasis on the potential importance of inflammatory factors in the increased risk of developing PE in obese pregnancies.

Maternal Phytosterol Supplementation during Pregnancy and Lactation Modulates Lipid and Lipoprotein Response in Offspring of apoE-Deficient Mice

BACKGROUND

In utero exposure to excessive cholesterol has been shown to increase fetal plasma cholesterol concentration and predispose adult offspring to cardiovascular disease (CVD) risk. Because lipid-lowering drugs are contraindicated during pregnancy, natural cholesterol-lowering compounds may be a safe and effective alternative to reduce CVD risk in offspring born to hypercholesterolemic mothers.

OBJECTIVE

This study used the hypercholesterolemic apolipoprotein E-deficient (apoE(-/-)) mouse model to test the hypothesis that mothers supplemented with phytosterols during gestation and lactation would produce offspring with a more favorable lipid profile than offspring from unsupplemented mothers, despite having a genetic predisposition toward hypercholesterolemia.

METHODS

Sixteen female apoE(-/-) mice were randomly assigned to 2 diets fed throughout the gestation and lactation periods: a cholesterol-enriched diet (CH) (0.15%) or the cholesterol-enriched diet supplemented with phytosterols (CH/PS) (2%). Serum lipids and lipoproteins were measured by enzyme assay and nuclear magnetic resonance spectroscopy, respectively, and liver cholesterol was analyzed by GC.

RESULTS

Compared with the CH-fed dams at the end of lactation, phytosterol-supplemented dams displayed lower (P < 0.05) serum total cholesterol (-55%), non-HDL cholesterol (-56%), and LDL cholesterol (-47%), but no change (P > 0.05) in HDL cholesterol and triacylglycerol (TG) concentrations. Pups from phytosterol-fed dams demonstrated lower (P < 0.05) total cholesterol (-25%), non-HDL cholesterol (-25%), LDL cholesterol (-47%), and TGs (-41%), without any change (P > 0.05) in HDL cholesterol compared with pups from CH-fed dams. Furthermore, compared with pups from CH-fed dams, pups from phytosterol-supplemented dams displayed a lower (P < 0.05) number of total LDL particles (-34%), VLDL particles (-31%), and HDL particles (-30%).

CONCLUSION

Our results in apoE(-/-) mice suggest that even under strong genetic predisposition to hypercholesterolemia, pups born to mothers supplemented with phytosterols during gestation and lactation exhibit favorable liver and serum lipid responses compared with pups from unsupplemented mothers.

Arginase as a Critical Prooxidant Mediator in the Binomial Endothelial Dysfunction-Atherosclerosis

Arginase is a metalloenzyme which hydrolyzes L-arginine to L-ornithine and urea. Since its discovery, in the early 1900s, this enzyme has gained increasing attention, as literature reports have progressively pointed to its critical participation in regulating nitric oxide bioavailability. Indeed, accumulating evidence in the following years would picture arginase as a key player in vascular health. Recent studies have highlighted the arginase regulatory role in the progression of atherosclerosis, the latter an essentially prooxidant state. Apart from the fact that arginase has been proven to impair different metabolic pathways, and also as a consequence of this, the repercussions of the actions of such enzyme go further than first thought. In fact, such metalloenzyme exhibits direct implications in multiple cardiometabolic diseases, among which are hypertension, type 2 diabetes, and hypercholesterolemia. Considering the epidemiological repercussions of these clinical conditions, arginase is currently seen under the spotlights of the search for developing specific inhibitors, in order to mitigate its deleterious effects. That said, the present review focuses on the role of arginase in endothelial function and its participation in the establishment of atherosclerotic lesions, discussing the main regulatory mechanisms of the enzyme, also highlighting the potential development of pharmacological strategies in related cardiovascular diseases.

Human supraphysiological gestational weight gain and fetoplacental vascular dysfunction

OBJECTIVE

Human foetal development and growth in an environment of maternal obesity associates with high risk of cardiovascular disease and adverse neonatal outcome. We studied whether supraphysiological gestational weight gain results in human fetoplacental endothelial dysfunction and altered fetoplacental vascular reactivity.

METHODS

Primary cultures of human umbilical vein endothelial cells (HUVECs) and umbilical vein rings were obtained from pregnant women (112 total of patients recruited, 7 patients dropped out) exhibiting prepregnancy normal weight that ended with a physiological (pGWG (n=67), total weight gain 11.5-16 kg, rates of weight gain ≤0.42 kg per week) or supraphysiological (spGWG (n=38), total weight gain >16 kg, rates of weight gain >0.42 kg per week) gestational weight gain (reference values from US Institute of Medicine guidelines). Vascular reactivity to insulin (0.1-1000 nmol l(-1), 5 min) in KCl-preconstricted vein rings was measured using a wire myograph. Protein levels of human equilibrative nucleoside transporter 1 (hENT1), total and Ser(1177)- or Thr(495)-phosphorylated endothelial nitric oxide synthase (eNOS) were detected by western blot or immunofluorescence, and adenosine transport (0-250 μmol l(-1) adenosine, 2 μCi ml(-1) [(3)H]adenosine, 20 s, 25 °C) was measured in the presence or absence of 1 μmol l(-1) nitrobenzylthioinosine (hENT1 inhibitor) or 10 μmol l(-1) chlorpromazine (CPZ, endocytosis inhibitor) in HUVECs.

RESULTS

spGWG associates with reduced NOS activity-dependent dilation of vein rings (P=0.001), lower eNOS expression and higher Thr(495) (P=0.044), but unaltered Ser(1177)eNOS phosphorylation. hENT1-adenosine maximal transport activity was reduced (P=0.041), but the expression was increased (P=0.001) in HUVECs from this group. CPZ increased hENT1-adenosine transport (P=0.040) and hENT1 plasma membrane accumulation only in cells from pGWG.

CONCLUSION

spGWG in women with a normal prepregnancy weight causes lower fetoplacental vascular reactivity owing to the downregulation of eNOS activity and adenosine transport in HUVECs. Maternal spGWG is a detrimental condition for human fetoplacental endothelial function and reducing these alterations could result in a better neonate outcome.

Early onset intrauterine growth restriction in a mouse model of gestational hypercholesterolemia and atherosclerosis

The susceptibility to develop atherosclerosis is increased by intrauterine growth restriction and prenatal exposure to maternal hypercholesterolemia. Here, we studied whether mouse gestational hypercholesterolemia and atherosclerosis affected fetal development and growth at different stages of gestation. Female LDLR KO mice fed a proatherogenic, high cholesterol (HC) diet for 3 weeks before conception and during pregnancy exhibited a significant increase in non-HDL cholesterol and developed atherosclerosis. At embryonic days 12.5 (E12.5), E15.5, and E18.5, maternal gestational hypercholesterolemia and atherosclerosis were associated to a 22-24% reduction in male and female fetal weight without alterations in fetal number/litter or morphology nor placental weight or structure. Feeding the HC diet exclusively at the periconceptional period did not alter fetal growth, suggesting that maternal hypercholesterolemia affected fetal weight only after implantation. Vitamin E supplementation (1,000 UI of α-tocopherol/kg) of HC-fed females did not change the mean weight of E18.5 fetuses but reduced the percentage of fetuses exhibiting body weights below the 10th percentile of weight (HC: 90% vs. HC/VitE: 68%). In conclusion, our results showed that maternal gestational hypercholesterolemia and atherosclerosis in mice were associated to early onset fetal growth restriction and that dietary vitamin E supplementation had a beneficial impact on this condition.