Christy-Lynn M. Cooke

Excessive hypercholesterolemia in pregnancy is a risk factor for the development of preeclampsia, but its ensuing impact on offspring cardiovascular health remains not fully understood. In the present study, Sprague Dawley rats were fed a control or high cholesterol diet (HCD) from gestational days 6–20 (term=22 days). Female and male offspring were aged to adulthood (4 months old), and in vivo and ex vivo cardiovascular function were assessed. In female offspring, body weight gain was greater in the HCD group compared with controls after 2 months of age. Blood pressure, echocardiographic parameters, cardiac capacity to recover from an ischemic insult, and endothelium-dependent vasodilation were similar between the female groups. However, vasoconstriction to a thromboxane analog (U46619) was reduced in thoracic aortas, but not in mesenteric, coronary, or carotid arteries, from the HCD females compared with controls, and was associated with lower phosphorylated myosin phosphatase target subunit 1 (MYPT1Thr855) levels. In male offspring, body weight gain, blood pressure, and echocardiographic parameters were similar between the groups, and there was no impact of HCD on vasoconstriction to U46619 or vasodilation in mesenteric arteries, carotid arteries, or thoracic aortas. However, endothelium-dependent vasodilation was reduced in coronary arteries of HCD males compared with controls and was associated with increased reactive oxygen species levels. There was also reduced cardiac capacity of the HCD males to recover from an ischemic insult. In summary, excessive hypercholesterolemia in pregnancy impaired the cardiovascular health of adult female and male offspring, but the mechanisms and vascular beds affected were specific to each sex.

Adults of mothers with gestational diabetes mellitus (GDM) have increased risk of cardiovascular (CV) disease. This cross-sectional case-control study examines the role of prenatal GDM exposure and its possible association with altered CV health in childhood. Children of mothers with GDM (C-GDM) and age- and sex-matched controls (C-Controls), recruited from the Alberta pregnancy outcomes and nutrition birth cohort (mothers recruited 2009–2012), underwent echocardiographic and other CV assessments in 2022. Primary outcome measures included left ventricular mass, systemic blood pressure, carotid intima-media thickness, aortic and peripheral arterial stiffness (pulse wave velocity), and endothelial function (reactive hyperemia). Lifestyle measures (e.g., 24 h diet recall, accelerometer-based physical activity) of mothers and children were also considered. We assessed 25 C-GDM (20 females; 17 diet-controlled, 8 insulin-treated) and 27 C-Controls (20 females without GDM) (mean age 10.9 ± 0.7 years), with comparable birth and baseline characteristics. Aortic pulse wave velocity was higher in C-GDM versus C-Controls (6.2 ± 2.6 vs. 4.8 ± 1.6 m/s, p = 0.03), and higher in C-GDM whose mothers managed their diabetes with insulin versus diet (7.9 ± 2.6 vs. 5.5 ± 2.2 m/s, p = 0.03). No other outcomes differed statistically. Mothers with GDM, but not controls, had reduced intake of less healthy foods from second to third trimesters. Intrauterine exposure to GDM may contribute to increased aortic stiffness in childhood. This association may be worse for C-GDM whose mothers require insulin rather than diet alone for glycemic control of their pregnancy, and may occur despite dietary improvements in the third trimester. Given the small sample size, additional work is needed to confirm these findings.

BACKGROUND: Excessive hypercholesterolemia in pregnancy increases the risk of preeclampsia (HC-PE), though the mechanisms remain unclear. We recently showed that uterine artery function is impaired in HC-PE pregnancies via activation of the TLR4 (toll-like receptor 4)/PGHS1 (prostaglandin H synthase 1) pathway. Low-dose aspirin lowers preeclampsia risk in high-risk pregnancies by inhibiting PGHS1, but its effects in HC-PE pregnancies are not known. Moreover, oxidized low-density lipoprotein (oxLDL) levels rise in HC-PE, potentially activating TLR4 and LOX-1 (lectin-like oxLDL receptor-1; scavenger receptor linked to vascular dysfunction in preeclampsia). However, whether this occurs in HC-PE is not known. METHODS: Sprague Dawley rats received a control or high-cholesterol diet (to induce HC-PE) from gestational day 6 to 20, with placebo or low-dose aspirin (1.5 mg/kg daily) given from gestational day 10 to 20. On gestational day 20, pregnancy outcomes and uterine artery function were assessed. RESULTS: Uterine artery blood flow velocity and placental weights were higher in HC-PE placebo-treated dams versus controls, but these were reduced by low-dose aspirin. Endothelium-dependent vasodilation was impaired in the uterine arteries of the HC-PE placebo group versus controls and was corrected by low-dose aspirin. Ex vivo inhibition of TLR4, PGHS1, or LOX-1 also normalized endothelium-dependent vasodilation in the HC-PE placebo-treated dams. Exposure to oxLDL in the bath (modeling a secondary hit) further impaired endothelium-dependent vasodilation in the uterine arteries of the HC-PE placebo group, partially via TLR4 and LOX-1, which was prevented by low-dose aspirin. CONCLUSIONS: Low-dose aspirin improved uterine artery endothelial function in HC-PE pregnancies; likely by suppressing the TLR4/LOX-1/PGHS1 pathway.

Background: Preeclampsia is a risk factor for the development of later‐life cardiovascular disease. However, the underlying mechanisms are poorly understood. Excessive hypercholesteremia in pregnancy induces a preeclampsia‐like phenotype, but whether this also impacts maternal vascular function later in life has not been fully characterized. Methods and Results: Sprague Dawley rats received a control diet (CD) or a high‐cholesterol (HCD) diet from gestational day 6 to 20, after which maternal vascular function was assessed 3 months postpartum. Exposure to an HCD in pregnancy reduced later‐life endothelium‐dependent vasodilation in carotid arteries (−15.24±3.27%), which was mediated via prostaglandin H synthase 2. There were no differences in vasodilation between CD and HCD postpartum rats in the mesenteric arteries, coronary arteries, or aortas. Vasoconstriction to phenylephrine increased in carotid arteries (61.02±21.48%) and reduced in aortas (−23.24±6.19%) of the HCD postpartum group versus CD dams, without differences in mesenteric and coronary arteries. The increased vasoconstriction in carotid arteries was due to lower nitric oxide modulation of constriction. Moreover, carotid artery myogenic response was reduced (−37.68±10.07%) and stiffness was increased (19.67±6.21%) in the HCD postpartum rats compared with CD along with decreased elastin density (−20.85±4.52%). The impact of the HCD on vascular function did not occur in age‐matched never‐pregnant female rats. Conclusions: Excessive hypercholesterolemia in pregnancy impairs later‐life maternal vascular function in rats with varying impacts across different vascular beds. Understanding mechanisms for pregnancy‐specific excessive hypercholesterolemia provides avenues for targeted intervention strategies to reduce the burden of cardiovascular disease in women who had a complicated pregnancy.

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.

BACKGROUND: Preeclampsia is a complex syndrome that includes maternal vascular dysfunction. Syncytiotrophoblast-derived extracellular vesicles from preeclampsia placentas (preeclampsia-STBEVs) were shown to induce endothelial dysfunction, but an endothelial transmembrane mediator is still unexplored. The LOX-1 (lectin-like oxidized low-density lipoprotein receptor-1) is a transmembrane scavenger receptor that can cause endothelial dysfunction, and its expression is increased in the endothelium of preeclampsia women. In this study, we hypothesized that LOX-1 mediates the effects of preeclampsia-STBEVs on endothelial function. METHODS: Preeclampsia-STBEVs were collected by perfusion of placentas from women with preeclampsia and in vitro and ex vivo endothelial cell function were assessed. RESULTS: In human umbilical vein endothelial cells, inhibition of LOX-1 with LOX-1 blocking antibody (TS20) reduced the uptake of preeclampsia-STBEVs (61.3±8.8%). TS20 prevented the activation of ERK (extracellular signal-regulated kinase, a kinase downstream of LOX-1) and reduced the activation of NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells; 21.1±8.0%) and nitrative stress (23.2±10.3%) that was induced by preeclampsia-STBEVs. Vascular function was assessed by wire myography in isolated mesenteric arteries from pregnant rats that were incubated overnight with preeclampsia-STBEVs±TS20. TS20 prevented endothelium-dependent vasodilation impairment induced by preeclampsia-STBEVs. Nitric oxide contribution to the relaxation was reduced by preeclampsia-STBEVs, which was prevented by TS20. Superoxide dismutase or apocynin, an inhibitor of NOX (nicotinamide adenine dinucleotide phosphate oxidase), restored the impaired endothelium-dependent vasodilation in arteries exposed to preeclampsia-STBEVs. CONCLUSIONS: Taken together, our findings demonstrate that LOX-1 mediates the endothelial dysfunction induced by preeclampsia-STBEVs. Our study further expands on the mechanisms that may lead to adverse outcomes in preeclampsia and proposes LOX-1 as a potential target for future interventions.

Advanced maternal age (≥35 years) is a risk factor for poor pregnancy outcomes. Pregnancy requires extensive maternal vascular adaptations, and with age, our blood vessels become stiffer and change in structure (collagen and elastin). However, the effect of advanced maternal age on the structure of human resistance arteries during pregnancy is unknown. As omental resistance arteries contribute to blood pressure regulation, assessing their structure in pregnancy may inform on the causal mechanisms underlying pregnancy complications in women of advanced maternal age. Omental fat biopsies were obtained from younger (<35 years) or advanced maternal age (≥35 years) women during caesarean delivery (n = 7–9/group). Arteries (200–300 µm) were isolated and passive mechanical properties (circumferential stress and strain) assessed with pressure myography. Collagen (Masson’s Trichrome) and elastin (Verhoff) were visualized histologically and % positively-stained area was assessed. Median maternal age was 32 years (range 25–34) for younger, and 38 years (range 35–42) for women of advanced maternal age. Circumferential strain was lower in arteries from advanced maternal age versus younger women but circumferential stress was not different. Omental artery collagen levels were similar, while elastin levels were lower with advanced maternal age versus younger pregnancies. The collagen:elastin ratio was greater in arteries from advanced maternal age versus younger women. In conclusion, omental arteries from women of advanced maternal age were less compliant with less elastin compared with arteries of younger controls, which may affect how vascular stressors are tolerated during pregnancy. Understanding how vascular aging affects pregnancy adaptations may contribute to better pregnancy outcomes.

Preeclampsia (PE) is a pregnancy syndrome characterized by new-onset hypertension and end-organ dysfunction. The pathophysiology of PE remains undetermined, but it is thought that maternal vascular dysfunction plays a central role, potentially due, in part, to the release of syncytiotrophoblast-derived extracellular vesicles (STBEVs) into the maternal circulation by a dysfunctional placenta. STBEVs from normal pregnancies (NP) impair vascular function, but the effect of PE STBEVs (known to differ in composition with elevated circulating levels) on vascular function are not known. We hypothesized that PE STBEVs have more detrimental effects on vascular function compared with NP STBEVs. STBEVs were collected by perfusion of placentas from women with NP or PE. Mesenteric arteries from pregnant rats were incubated overnight with NP or PE STBEVs, and vascular function was assessed by wire myography. NP and PE STBEVs impaired endothelial function, partially by reducing nitric oxide (NO) bioavailability. Incubation of human umbilical vein endothelial cells with NP and PE STBEVs increased nuclear factor κ-light-chain-enhancer of activated B cell (NF-κB) activation, reactive oxygen species, nitrotyrosine levels, and reduced NO levels. However, PE STBEVs increased NF-κB activation and nitrotyrosine levels to a lesser extent than NP STBEVs. Taken together, no greater impact of PE STBEVs compared with NP STBEVs on endothelial function was found. However, the impaired vascular function by PE STBEVs and increased levels of STBEVs in PE suggest PE STBEVs may contribute to maternal vascular dysfunction in PE. Our study further expands on the potential mechanisms that lead to adverse outcomes in PE and provides potential targets for future interventions.

Prenatal hypoxia predisposes the offspring to the development of cardiovascular (CV) dysfunction in adult life. Using a rat model, we assessed the effect of prenatal hypoxia on vasoconstrictive and vasodilative mechanisms in left anterior descending coronary arteries of 4- and 9.5-month-old offspring. Endothelium-dependent relaxation to methylcholine and vasoconstriction responses to endothelin-1 (ET-1) were assessed by wire myography. Prenatal hypoxia impaired endothelium-dependent vasodilation in 4- and 9.5-month-old offspring. Inhibition of nitric oxide (NO) synthase prevented coronary artery relaxation in all groups. Inhibition of prostaglandin H synthase (PGHS) improved relaxation in prenatally hypoxic males and tended to improve vasorelaxation in females, suggesting that impaired vasodilation was mediated via increased PGHS-dependent vasoconstriction. An enhanced contribution of endothelium-dependent hyperpolarization to coronary artery vasodilation was observed in prenatally hypoxic males and females. No changes in endothelial NO synthase (eNOS) and PGHS-1 expressions were observed, while PGHS-2 expression was decreased in only prenatally hypoxic males. At 4 months, ET-1 responses were similar between groups, while ET_B inhibition (with BQ788) tended to decrease ET-1-mediated responses in only prenatally hypoxic females. At 9.5 months, ET-1-mediated responses were decreased in only prenatally hypoxic females. Our data suggest that prenatal hypoxia has long-term similar effects on the mechanisms of impaired endothelium-dependent vasodilation in coronary arteries from adult male and female offspring; however, coronary artery contractile capacity is impaired only in prenatally hypoxic females. Understanding the mechanistic pathways involved in the programming of CV disease may allow for the development of therapeutic interventions.

Advanced maternal age (≥35 years) is associated with pregnancy complications. Aging impairs vascular reactivity and increases vascular stiffness. We hypothesized that uterine artery adaptations to pregnancy are impaired with advanced age. Uterine arteries of nonpregnant and pregnant (gestational day 20) young (4 months) and aged (9 months; ~35 years in humans) Sprague-Dawley rats were isolated. Functional (myogenic tone, n = 6–10/group) and mechanical (circumferential stress-strain, n = 10–24/group) properties were assessed using pressure myography and further assessment of elastin and collagen (histology, n = 4–6/group), and matrix metalloproteinase-2 (MMP-2, zymography, n = 6/group). Aged dams had worse pregnancy outcomes, including smaller litters and fetal weights (both p < 0.0001). Only in arteries of pregnant young dams did higher pressures (>100 mmHg) cause forced vasodilation. Across the whole pressure range (4–160 mmHg), myogenic behavior was enhanced in aged vs. young pregnant dams (p = 0.0010). Circumferential stress and strain increased with pregnancy in young and aged dams (p < 0.0001), but strain remained lower in aged vs. young dams (p < 0.05). Arteries from young nonpregnant rats had greater collagen:elastin ratios than the other groups (p < 0.05). In aged rats only, pregnancy increased MMP-2 active capacity. Altered functional and structural vascular adaptations to pregnancy may impair fetal growth and development with advanced maternal age.