Maternal Hypercholesterolemia in Pregnancy Associates With Umbilical Vein Endothelial Dysfunction

Abstract

Objective-Human pregnancy that courses with maternal supraphysiological hypercholesterolemia (MSPH) correlates with atherosclerotic lesions in fetal arteries. It is known that hypercholesterolemia associates with endothelial dysfunction in adults, a phenomenon where nitric oxide (NO) and arginase are involved. However, nothing is reported on potential alterations in the fetoplacental endothelial function in MSPH. The aim of this study was to determine whether MSPH alters fetal vascular reactivity via endothelial arginase/urea and l-arginine transport/NO signaling pathways. Approach and Results-Total cholesterol <280 mg/dL was considered as maternal physiological hypercholesterolemia (n=46 women) and ≥280 mg/dL as MSPH (n=28 women). Maternal but not fetal total cholesterol and low-density lipoprotein-cholesterol levels were elevated in MSPH. Umbilical veins were used for vascular reactivity assays (wire myography), and primary cultures of umbilical vein endothelial cells to determine arginase, endothelial NO synthase (eNOS), and human cationic amino acid transporter 1 and human cationic amino acid transporter 2A/B expression and activity. MSPH reduced calcitonine gene-related peptide-umbilical vein relaxation and increased intima/media ratio (histochemistry), as well as reduced eNOS activity (l-citrulline synthesis from l-arginine, eNOS phosphorylation/dephosphorylation), but increased arginase activity and arginase II protein abundance. Arginase inhibition increased eNOS activity and l-arginine transport capacity without altering human cationic amino acid transporter 1 or human cationic amino acid transporter 2A/B protein abundance in maternal physiological hypercholesterolemia and MSPH. Conclusions-MSPH is a pathophysiological condition altering umbilical vein reactivity because of fetal endothelial dysfunction associated with arginase and eNOS signaling imbalance. We speculate that elevated maternal circulating cholesterol is a factor leading to fetal endothelial dysfunction, which could have serious consequences to the growing fetus. Maternal Hypercholesterolemia in Pregnancy AssociatesWith Umbilical Vein Endothelial Dysfunction Leiva et al MSPH and Umbilical Vein Endothelial Dysfunction 2445NO synthases. Because NO synthesis depends on l-arginine uptake in human placenta endothelium, 10-17 MSPH could result in altered l-arginine transport and NO synthesis, that is, the l-arginine/NO pathway, in fetal endothelium.l-Arginine uptake occurs predominantly via the human cationic amino acid transporters (hCATs) family.13 hCATs family includes ≥5 members, that is, hCAT-1, hCAT-2A, hCAT-2B, hCAT-3, and hCAT-4, 12,13 of which the high-affinity, lowcapacity hCAT-1 is the main isoform expressed in human umbilical vein endothelial cells (HUVEC), 15,16 a cell type exposed to oxygen-and nutrient-enriched blood (ie, arteriallike blood, reaching fetal circulation).18 Interestingly, altered hCAT-1 activity could result in abnormal NO synthesis in HUVEC. 10,11,15,17 Hypercholesterolemia also associates with reduced endotheli...

Cross-sectional and longitudinal lipid determination studies in pregnant women reveal an association between increased maternal LDL cholesterol concentrations and reduced human umbilical vein relaxation

“…TCh, HDL and triglycerides were determined via standard enzymatic-colorimetric assays (Cobas Integra Cholesterol (CHOLL), Cobas Integra HDL cholesterol (HDL_C), and Cobas Integra Triglycerides (TRICL) kits, Roche Diagnostic Corporation, Indianapolis, IN, USA) in a Cobas ® 8000 modular analyser series (Roche Diagnostic Corporation) at the Clinical Laboratory of the Hospital Clínico Universidad Cat olica. LDL and vLDL cholesterol were calculated from TCh, HDL and triglyceride concentrations by applying the Friedewald's equation [11] as described [4].…”

“…Because TCh results primarily from LDL plus HDL concentrations, we analyzed the vascular reactivity response in samples from pregnant women either with TCh in the >75th percentile or in subgroups from these women with LDL or HDL in the >75th percentile. The umbilical vein rings were mounted in a myograph (610M Multiwire Myograph System, Danish Myo Technology A/S, Denmark) for isometric force measurements as described [4,12]. The optimal diameter for each vein ring was adjusted by determining the active maximal response evoked by 65 mmol/L KCl [4,12].…”

“…The umbilical vein rings were mounted in a myograph (610M Multiwire Myograph System, Danish Myo Technology A/S, Denmark) for isometric force measurements as described [4,12]. The optimal diameter for each vein ring was adjusted by determining the active maximal response evoked by 65 mmol/L KCl [4,12]. Endothelium-dependent relaxation was evaluated as the concentration-dependent response to calcitonin gene-related peptide (0.1e1000 nmol/L, 5 min) in vessels precontracted with KCl.…”

“…However, pregnancy-associated hypercholesterolemia over this physiological increase is regarded as maternal supraphysiological hypercholesterolemia (MSPH) [2e4]. MSPH is associated with human fetoplacental endothelial dysfunction [4], increased fetal aortic fatty streak formation [5] and atherosclerosis in childhood [6]. Thus, the control Abbreviations: TCh, total cholesterol; LDL, low density lipoprotein; HDL, high density lipoprotein; vLDL, very low density lipoprotein; CLDS, cross-sectional lipids determination study; LLDS, longitudinal lipids determination study; MPH, maternal physiological hypercholesterolemia; MSPH, maternal supraphysiological hypercholesterolemia; D max , maximal dilation; EC 50 , half-maximal effective concentration.…”

“…However, the effect of the increased maternal triglyceride concentration on the fetal vasculature function as well as an established cut-off value for maternal TCh concentration in MSPH or hypertriglyceridemia during pregnancy are not available [2,10]. Interestingly, few studies show the variation in maternal blood TCh and triglyceride concentrations between the first, second and third trimesters; however, these studies did not determine a cut-off value for MSPH or hypertriglyceridemia in pregnancy [2,4].…”