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...