Hypoxia induces dilated cardiomyopathy in the chick embryo: mechanism, intervention, and long-term consequences

Subclinical myocardial dysfunction among fetal growth restriction neonates: a case-control study

OBJECTIVES

To evaluate cardiac structural and functional changes in neonates with fetal growth restriction (FGR) compared to appropriate-for-gestational-age (AGA) neonates using conventional echocardiography, tissue Doppler imaging (TDI), and speckle tracking echocardiography.

METHOD

This case-control study included 85 FGR neonates and 75 non-FGR, weight adequate for gestational age neonates. Among these, 37 were symmetric FGR and 48 were asymmetric FGR. All the biophysical profiles of these newborns were assessed. An echocardiographic test was performed to evaluate cardiac dimension, Left ventricular ejection fraction (LV EF), Mitral valve Doppler flow velocities, myocardial performance index, tissue annular velocities, and LV global longitudinal strain (GLS).

RESULTS

Although LVEF was found to be within the normal range, mean EF was reduced among neonates with FGR than non-FGR controls (EF: 66.14 ± 3.85% vs 69.46 ± 3.58%; p < 0.001, in FGR and non-FGR, respectively). Furthermore, LV E/E' a measure of LV diastolic function was altered among both types of FGR neonates. Similarly, LV GLS was reduced among FGR neonates (LV GLS: -20.69 ± 2.7% vs -19.06 ± 2.9%; p < 0.001 in non-FGR and FGR, respectively).

CONCLUSION

FGR neonates exhibit significant alterations in cardiac geometry compared to AGA controls. FGR neonates also demonstrated a significant reduction in LV EF, FS, and LV global longitudinal strain, depicting failure to adapt to the increased cardiac workload after birth.

Developmental plasticity of the cardiovascular system in oviparous vertebrates: effects of chronic hypoxia and interactive stressors in the context of climate change

Animals at early life stages are generally more sensitive to environmental stress than adults. This is especially true of oviparous vertebrates that develop in variable environments with little or no parental care. These organisms regularly experience environmental fluctuations as part of their natural development, but climate change is increasing the frequency and intensity of these events. The developmental plasticity of oviparous vertebrates will therefore play a critical role in determining their future fitness and survival. In this Review, we discuss and compare the phenotypic consequences of chronic developmental hypoxia on the cardiovascular system of oviparous vertebrates. In particular, we focus on species-specific responses, critical windows, thresholds for responses and the interactive effects of other stressors, such as temperature and hypercapnia. Although important progress has been made, our Review identifies knowledge gaps that need to be addressed if we are to fully understand the impact of climate change on the developmental plasticity of the oviparous vertebrate cardiovascular system.

Integrated small RNA, mRNA and protein omics reveal a miRNA network orchestrating metabolic maturation of the developing human heart

BACKGROUND

As the fetal heart develops, cardiomyocyte proliferation potential decreases while fatty acid oxidative capacity increases in a highly regulated transition known as cardiac maturation. Small noncoding RNAs, such as microRNAs (miRNAs), contribute to the establishment and control of tissue-specific transcriptional programs. However, small RNA expression dynamics and genome-wide miRNA regulatory networks controlling maturation of the human fetal heart remain poorly understood.

RESULTS

Transcriptome profiling of small RNAs revealed the temporal expression patterns of miRNA, piRNA, circRNA, snoRNA, snRNA and tRNA in the developing human heart between 8 and 19 weeks of gestation. Our analysis demonstrated that miRNAs were the most dynamically expressed small RNA species throughout mid-gestation. Cross-referencing differentially expressed miRNAs and mRNAs predicted 6200 mRNA targets, 2134 of which were upregulated and 4066 downregulated as gestation progressed. Moreover, we found that downregulated targets of upregulated miRNAs, including hsa-let-7b, miR-1-3p, miR-133a-3p, miR-143-3p, miR-499a-5p, and miR-30a-5p predominantly control cell cycle progression. In contrast, upregulated targets of downregulated miRNAs, including hsa-miR-1276, miR-183-5p, miR-1229-3p, miR-615-3p, miR-421, miR-200b-3p and miR-18a-3p, are linked to energy sensing and oxidative metabolism. Furthermore, integrating miRNA and mRNA profiles with proteomes and reporter metabolites revealed that proteins encoded in mRNA targets and their associated metabolites mediate fatty acid oxidation and are enriched as the heart develops.

CONCLUSIONS

This study presents the first comprehensive analysis of the small RNAome of the maturing human fetal heart. Our findings suggest that coordinated activation and repression of miRNA expression throughout mid-gestation is essential to establish a dynamic miRNA-mRNA-protein network that decreases cardiomyocyte proliferation potential while increasing the oxidative capacity of the maturing human fetal heart. Our results provide novel insights into the molecular control of metabolic maturation of the human fetal heart.

Cardiovascular Risk in Pediatrics: A Dynamic Process during the First 1000 Days of Life

The early childhood period, encompassing prenatal and early stages, assumes a pivotal role in shaping cardiovascular risk factors. We conducted a narrative review, presenting a non-systematic summation and analysis of the available literature, focusing on cardiovascular risk from prenatal development to the first 1000 days of life. Elements such as maternal health, genetic predisposition, inadequate fetal nutrition, and rapid postnatal growth contribute to this risk. Specifically, maternal obesity and antibiotic use during pregnancy can influence transgenerational risk factors. Conditions at birth, such as fetal growth restriction and low birth weight, set the stage for potential cardiovascular challenges. To consider cardiovascular risk in early childhood as a dynamic process is useful when adopting a personalized prevention for future healthcare and providing recommendations for management throughout their journey from infancy to early adulthood. A comprehensive approach is paramount in addressing early childhood cardiovascular risks. By targeting critical periods and implementing preventive strategies, healthcare professionals and policymakers can pave the way for improved cardiovascular outcomes. Investing in children's health during their early years holds the key to alleviating the burden of cardiovascular diseases for future generations.

Myocardial perfusion and function dichotomy in growth restricted preterm infants

Compared to preterm appropriate for gestational age (AGA) fetuses, fetuses with fetal growth restriction (FGR) have earlier visualisation of coronary artery blood flow (CABF) but impaired cardiac function. This dichotomy remains uncharacterised during postnatal life. This study compared CABF and cardiac function in preterm FGR infants, against AGA infants during the postnatal period. FGR was defined as birthweight < 10^th centile for gestation and sex with absent/reversed antenatal umbilical artery Doppler. Diastolic CABF was measured in the left anterior descending coronary artery. Twenty-eight FGR infants were compared with 26 AGA infants (gestation and birthweight, 29.7 ± 1.3 vs 29.9 ± 1 weeks, P = 0.6 and 918 ± 174 vs 1398 ± 263g, P < 0.001, respectively). Echocardiography was performed in the second week of life. FGR infants had higher CABF (velocity time integral, 2.4 ± 0.9 vs 1.6 ± 0.8 cm, P = 0.002). Diastolic function was impaired (↑ trans-mitral E/A ratio in FGR infants; 0.84 ± 0.05 vs 0.79 ± 0.03, P = 0.0002) while the systolic function was also affected (mean velocity of circumferential fibre shortening [mVCFc], 1.9 ± 0.3 vs 2.7 ± 0.5 circ/s, P < 0.001). Indexing CABF to cardiac function noted significant differences between the groups (CABF: E/A [FGR vs AGA], 2.9 ± 1.1 vs 2.1 ± 1, P = 0.01 and CABF: mVCFc [FGR vs AGA], 1.3 ± 0.5 vs 0.6 ± 0.3, P < 0.001). Diastolic blood pressure (BP) was significantly higher, and CABF to diastolic BP ratio trended higher in FGR infants (30 ± 2 vs 25 ± 3 mmHg, P < 0.001 and 0.08 ± 0.03 vs 0.06 ± 0.03, P = 0.059, respectively). Greater CABF in FGR infants did not translate into better cardiac function. This dichotomy may be a persistent response to fetal hypoxaemia (fetal programming) and/or reflection of altered cardiac architecture.

Effects of Developmental Hypoxia on the Vertebrate Cardiovascular System

Developmental hypoxia has profound and persistent effects on the vertebrate cardiovascular system, but the nature, magnitude, and long-term outcome of the hypoxic consequences are species specific. Here we aim to identify common and novel cardiovascular responses among vertebrates that encounter developmental hypoxia, and we discuss the possible medical and ecological implications.

Cardiovascular Dysfunction in Intrauterine Growth Restriction

PURPOSE OF REVIEW

We highlight important new findings on cardiovascular dysfunction in intrauterine growth restriction.

RECENT FINDINGS

Intrauterine growth restriction (IUGR) is a multifactorial condition which negatively impacts neonatal growth during pregnancy and is associated with health problems during the lifespan. It affects 5-15% of all pregnancies in the USA and Europe with varying percentages in developing countries. Epidemiological studies have reported that IUGR is associated with the pathogenesis of hypertension, activation of the renin-angiotensin system (RAS), disruption in placental-mTORC and TGFβ signaling cascades, and endothelial dysfunction in IUGR fetuses, children, adolescents, and adults resulting in the development of cardiovascular diseases (CVD). Experimental studies are needed to investigate therapeutic measures to treat increased blood pressure (BP) and long-term CVD problems in people affected by IUGR. We outline the mechanisms mediating fetal programming of hypertension in developing CVD. We have reviewed findings from different experimental models focusing on recent studies that demonstrate CVD in IUGR.

Developing chicken cardiac muscle mitochondria are resistant to variations in incubation oxygen levels

Background

Chronic exposure to hypoxia during vertebrate development can produce abnormal cardiovascular morphology and function. The aim of this study was to examine cardiac mitochondria function in an avian model, the chicken, in response to embryonic development under hypoxic (15% O₂), normoxic (21% O₂), or hyperoxic (40% O₂) incubation conditions.

Methods

Chicken embryos were incubated in hypoxia, normoxia, or hyperoxia beginning on day 5 of incubation through hatching. Cardiac mitochondria oxygen flux and reactive oxygen species production were measured in permeabilized cardiac fibers from externally pipped and 1-day post hatchlings.

Results

Altering oxygen during development had a large effect on body and heart masses of externally pipped embryos and 1-day old hatchlings. Hypoxic animals had smaller body masses and absolute heart masses, but proportionally similar sized hearts compared to normoxic animals during external pipping. Hyperoxic animals were larger with larger hearts than normoxic animals during external pipping. Mitochondrial oxygen flux in permeabilized cardiac muscle fibers revealed limited effects of developing under altered oxygen conditions, with only oxygen flux through cytochrome oxidase being lower in hypoxic hearts compared with hyperoxic hearts. Oxygen flux in leak and oxidative phosphorylation states were not affected by developmental oxygen levels. Mitochondrial reactive oxygen species production under leak and oxidative phosphorylation states studied did not differ between any developmental oxygen treatment.

Conclusions

These results suggest that cardiac mitochondria function of the developing chicken is not altered by developing in ovo under different oxygen levels.

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Chicken heart mass is influenced by oxygen availability during development.

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Cardiac mitochondria respiration was unchanged by developing under hypoxic or hyperoxic oxygen stress.

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Cardiac mitochondria ROS production was not altered by developmental oxygen stress.

Breath of Life: Heart Disease Link to Developmental Hypoxia

Heart disease remains one of the greatest killers. In addition to genetics and traditional lifestyle risk factors, we now understand that adverse conditions during pregnancy can also increase susceptibility to cardiovascular disease in the offspring. Therefore, the mechanisms by which this occurs and possible preventative therapies are of significant contemporary interest to the cardiovascular community. A common suboptimal pregnancy condition is a sustained reduction in fetal oxygenation. Chronic fetal hypoxia results from any pregnancy with increased placental vascular resistance, such as in preeclampsia, placental infection, or maternal obesity. Chronic fetal hypoxia may also arise during pregnancy at high altitude or because of maternal respiratory disease. This article reviews the short- and long-term effects of hypoxia on the fetal cardiovascular system, and the importance of chronic fetal hypoxia in triggering a developmental origin of future heart disease in the adult progeny. The work summarizes evidence derived from human studies as well as from rodent, avian, and ovine models. There is a focus on the discovery of the molecular link between prenatal hypoxia, oxidative stress, and increased cardiovascular risk in adult offspring. Discussion of mitochondria-targeted antioxidant therapy offers potential targets for clinical intervention in human pregnancy complicated by chronic fetal hypoxia.

Risk factors for left ventricular dysfunction in adulthood: role of low birth weight

Aims

This study aimed to determine the relationship of low birth weight (LBW) with adult cardiac structure and function and investigate potential causal pathways.

Methods and results

A population‐based sample of 925 Australians (41.3% male) were followed from childhood (aged 7–15 years) to young adulthood (aged 26–36 years) and mid‐adulthood (aged 36–50 years). Left ventricular (LV) global longitudinal strain (GLS, %), LV mass index (LVMi, g/m^2.7), LV filling pressure (E/e′), and left atrial volume index (g/m²) were measured by transthoracic echocardiography in mid‐adulthood. Birth weight category was self‐reported in young adulthood and classified as low (≤5 lb or ≤2270 g), normal (5–8 lb or 2271–3630 g), and high (>8 lb or >3630 g). Of the 925 participants, 7.5% (n = 69) were classified as LBW. Compared with participants with normal birth weight, those with LBW had 2.01‐fold (95% confidence interval: 1.19, 3.41, P = 0.009) higher risks of impaired GLS (GLS > −18%) and 2.63‐fold (95% confidence interval: 0.89, 7.81, P = 0.08) higher risks of LV hypertrophy (LVMi > 48 g/m^2.7 in men or >44 g/m^2.7 in women) in adulthood, independent of age, sex, and any socio‐economic factors. Participants with LBW significantly increased body fat from childhood to adulthood relative to their peers and had greater levels of triglycerides, fasting glucose, and arterial stiffness in adulthood. These risk factors were the strongest mediators and explained 54% of the LBW effect size on adult GLS and 33% of the LBW effect size on LVMi. The remaining of these associations was independent of any of the measured risk factors.

Conclusions

Low birth weight was associated with impaired cardiac structure and function in mid‐adulthood. This association was only partially explained by known risk factors.

Gene network analysis to determine the effect of hypoxia-associated genes on brain damages and tumorigenesis using an avian model

BACKGROUND

Hypoxia refers to the condition of low oxygen pressure in the atmosphere and characterization of response to hypoxia as a biological complex puzzle, is challenging. Previously, we carried out a comparative genomic study by whole genome resequencing of highland and lowland Iranian native chickens to identify genomic variants associated with hypoxia conditions. Based on our previous findings, we used chicken as a model and the identified hypoxia-associated genes were converted to human's orthologs genes to construct the informative gene network. The main goal of this study was to visualize the features of diseases due to hypoxia-associated genes by gene network analysis.

RESULTS

It was found that hypoxia-associated genes contained several gene networks of disorders such as Parkinson, Alzheimer, cardiomyopathy, drug toxicity, and cancers. We found that biological pathways are involved in mitochondrion dysfunctions including peroxynitrous acid production denoted in brain injuries. Lewy body and neuromelanin were reported as key symptoms in Parkinson disease. Furthermore, calmodulin, and amyloid precursor protein were detected as leader proteins in Alzheimer's diseases. Dexamethasone was reported as the candidate toxic drug under the hypoxia condition that implicates diabetes, osteoporosis, and neurotoxicity. Our results suggested DNA damages caused by the high doses of UV radiation in high-altitude conditions, were associated with breast cancer, ovarian cancer, and colorectal cancer.

CONCLUSIONS

Our results showed that hypoxia-associated genes were enriched in several gene networks of disorders including Parkinson, Alzheimer, cardiomyopathy, drug toxicity, and different types of cancers. Furthermore, we suggested, UV radiation and low oxygen conditions in high-altitude regions may be responsible for the variety of human diseases.

The Role of Cellular Stress in Intrauterine Growth Restriction and Postnatal Dysmetabolism

Disruption of the in utero environment can have dire consequences on fetal growth and development. Intrauterine growth restriction (IUGR) is a pathological condition by which the fetus deviates from its expected growth trajectory, resulting in low birth weight and impaired organ function. The developmental origins of health and disease (DOHaD) postulates that IUGR has lifelong consequences on offspring well-being, as human studies have established an inverse relationship between birth weight and long-term metabolic health. While these trends are apparent in epidemiological data, animal studies have been essential in defining the molecular mechanisms that contribute to this relationship. One such mechanism is cellular stress, a prominent underlying cause of the metabolic syndrome. As such, this review considers the role of oxidative stress, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and inflammation in the pathogenesis of metabolic disease in IUGR offspring. In addition, we summarize how uncontrolled cellular stress can lead to programmed cell death within the metabolic organs of IUGR offspring.

Postnatal persistence of cardiac remodeling and dysfunction in late fetal growth restriction

Fetal growth restriction is one of the most common obstetric complications, affecting 7-10% of all pregnancies. Affected fetuses are exposed to an adverse environment in utero during a critical time of development and may face long-term health consequences such as increased cardiovascular risk in adulthood. Growth restricted fetuses develop remodeled hearts with signs of systolic and diastolic dysfunction. Cardiac adaptations are more evident in early severe cases, but also present in late onset fetal growth restriction. Cardiovascular remodeling persists into postnatal life, from the neonatal period to adolescence, encompassing an increased susceptibility to adult disease. In this review, we summarize the current evidence on cardiovascular programming associated to fetal growth restriction, its postnatal consequences and potential strategies to reduce their cardiovascular risk.

Hypertension Programmed in Adult Hens by Isolated Effects of Developmental Hypoxia In Ovo

In mammals, pregnancy complicated by chronic hypoxia can program hypertension in the adult offspring. However, mechanisms remain uncertain because the partial contributions of the challenge on the placenta, mother, and fetus are difficult to disentangle. Here, we used chronic hypoxia in the chicken embryo-an established model system that permits isolation of the direct effects of developmental hypoxia on the cardiovascular system of the offspring, independent of additional effects on the mother or the placenta. Fertilized chicken eggs were exposed to normoxia (N; 21% O₂) or hypoxia (H; 13.5%-14% O₂) from the start of incubation (day 0) until day 19 (hatching, ≈day 21). Following hatching, all birds were maintained under normoxic conditions until ≈6 months of adulthood. Hypoxic incubation increased hematocrit (+27%) in the chicken embryo and induced asymmetrical growth restriction (body weight, -8.6%; biparietal diameter/body weight ratio, +7.5%) in the hatchlings (all P<0.05). At adulthood (181±4 days), chickens from hypoxic incubations remained smaller (body weight, -7.5%) and showed reduced basal and stimulated in vivo NO bioavailability (pressor response to NG-nitro-L-arginine methyl ester, -43%; phenylephrine pressor response during NO blockade, -61%) with significant hypertension (mean arterial blood pressure, +18%), increased cardiac work (ejection fraction, +12%; fractional shortening, +25%; enhanced baroreflex gain, +456%), and left ventricular wall thickening (left ventricular wall volume, +36%; all P<0.05). Therefore, we show that chronic hypoxia can act directly on a developing embryo to program hypertension, cardiovascular dysfunction, and cardiac wall remodeling in adulthood in the absence of any maternal or placental effects.

Chicken embryos can maintain heart rate during hypoxia on day 4 of incubation

Acute exposure to hypoxic conditions is a frequent natural event during the development of bird eggs. However, little is known about the effect of such exposure on the ability of young embryos in which cardiovascular regulation is not yet developed to maintain a normal heart rate (HR). To address this question, we studied the effect of 10-20 min of exposure to moderate or severe acute hypoxia (10% or 5% O₂, respectively) on the HR of day 4 (D4) chicken embryos. In ovo, video recording of the beating embryo heart inside the egg revealed that severe, but not moderate, hypoxia resulted in significant HR changes. The HR response to severe hypoxia consisted of two phases: the first phase, consisting of an initial decrease in HR, was followed by a phase of partial HR recovery. Upon the restoration of normoxia, after an overshoot period of a few minutes, the HR completely recovered to its basal level. In vitro (isolated heart preparation), the first phase of the HR response to severe hypoxia was strengthened (nearly complete heart silencing) compared to that in ovo, and the HR recovery phase was greatly attenuated. Furthermore, neither an overshoot period nor complete HR recovery after hypoxia was observed. Thus, the D4 chicken embryo heart can partially maintain its rhythm during hypoxia in ovo, but not in vitro. Some factors from the egg, such as catecholamines, are likely to be critical for avian embryo responding to hypoxic condition and survival.

Fetal cardiac remodeling and dysfunction is associated with both preeclampsia and fetal growth restriction

BACKGROUND

Preeclampsia and fetal growth restriction share some pathophysiologic features and are both associated with placental insufficiency. Fetal cardiac remodeling has been described extensively in fetal growth restriction, whereas little is known about preeclampsia with a normally grown fetus.

OBJECTIVE

To describe fetal cardiac structure and function in pregnancies complicated by preeclampsia and/or fetal growth restriction as compared with uncomplicated pregnancies.

STUDY DESIGN

This was a prospective, observational study including pregnancies complicated by normotensive fetal growth restriction (n=36), preeclampsia with a normally grown fetus (n=35), preeclampsia with fetal growth restriction (preeclampsia with a normally grown fetus-fetal growth restriction, n=42), and 111 uncomplicated pregnancies matched by gestational age at ultrasound. Fetal echocardiography was performed at diagnosis for cases and recruitment for uncomplicated pregnancies. Cord blood concentrations of B-type natriuretic peptide and troponin I were measured at delivery. Univariate and multiple regression analysis were conducted.

RESULTS

Pregnancies complicated by preeclampsia and/or fetal growth restriction showed similar patterns of fetal cardiac remodeling with larger hearts (cardiothoracic ratio, median [interquartile range]: uncomplicated pregnancies 0.27 [0.23-0.29], fetal growth restriction 0.31 [0.26-0.34], preeclampsia with a normally grown fetus 0.31 [0.29-0.33), and preeclampsia with fetal growth restriction 0.28 [0.26-0.33]; P<.001) and more spherical right ventricles (right ventricular sphericity index: uncomplicated pregnancies 1.42 [1.25-1.72], fetal growth restriction 1.29 [1.22-1.72], preeclampsia with a normally grown fetus 1.30 [1.33-1.51], and preeclampsia with fetal growth restriction 1.35 [1.27-1.46]; P=.04) and hypertrophic ventricles (relative wall thickness: uncomplicated pregnancies 0.55 [0.48-0.61], fetal growth restriction 0.67 [0.58-0.8], preeclampsia with a normally grown fetus 0.68 [0.61-0.76], and preeclampsia with fetal growth restriction 0.66 [0.58-0.77]; P<.001). Signs of myocardial dysfunction also were observed, with increased myocardial performance index (uncomplicated pregnancies 0.78 z scores [0.32-1.41], fetal growth restriction 1.48 [0.97-2.08], preeclampsia with a normally grown fetus 1.15 [0.75-2.17], and preeclampsia with fetal growth restriction 0.45 [0.54-1.94]; P<.001) and greater cord blood B-type natriuretic peptide (uncomplicated pregnancies 14.2 [8.4-30.9] pg/mL, fetal growth restriction 20.8 [13.1-33.5] pg/mL, preeclampsia with a normally grown fetus 31.8 [16.4-45.8] pg/mL and preeclampsia with fetal growth restriction 37.9 [15.7-105.4] pg/mL; P<.001) and troponin I as compared with uncomplicated pregnancies.

CONCLUSION

Fetuses of preeclamptic mothers, independently of their growth patterns, presented cardiovascular remodeling and dysfunction in a similar fashion to what has been previously described for fetal growth restriction. Future research is warranted to better elucidate the mechanism(s) underlying fetal cardiac adaptation in these conditions.

Utility of the modified myocardial performance index in growth-restricted fetuses

OBJECTIVES

The modified myocardial performance index (Mod-MPI) can be used to assess myocardial function. Fetal growth restriction can affect fetal myocardial function, thereby altering the Mod-MPI. The results of previous studies on the utility of the Mod-MPI in growth-restricted fetuses are conflicting. The aim of this study was to calculate the left modified-MPI in growth-restricted fetuses and to compare the results with those of healthy fetuses.

METHODS

This was a prospective cross-sectional case-control study. In total, 40 women with growth-restricted fetuses and 40 women with fetuses of normal weight (controls) at 29-39 gestational weeks were enrolled in the study. An experienced obstetrician calculated the Mod-MPI for each fetus. Women with systemic diseases or fetuses with chromosomal/structural abnormalities were excluded from the study. The results of Mod-MPI measurements of the two groups were compared.

RESULTS

The mean single deepest vertical pocket (SDVP) of amniotic fluid, estimated fetal weight (EFW), and isovolumetric relaxation time (IRT) was significantly lower in the fetal growth restriction (FGR) group as compared with these parameters in the control group (P < .05). The uterine artery (UtA) pulsatility index (PI) was significantly higher in the FGR group as compared with that in the control group (P < .05). There were six cases of absent end-diastolic flow (AED) in the FGR group. There were no statistically significant between-group differences in the Mod-MPI, isovolumetric contraction time (ICT), and ejection time (ET) (P > .05). There was also no statistically significant correlation between the Mod-MPI in the fetuses with AED and the control group for Mod-MPI (P > .05).

CONCLUSION

The utility of the Mod-MPI in FGR remains unclear. Future studies with larger populations are needed to determine the utility of the Mod-MPI as a predictor of cardiac compromise in FGR.

Adverse maternal environment leads to cardiac fibrosis in adult male mice

BACKGROUND

Cardiac fibrosis is a cardinal feature of multiple types of cardiovascular disease, which lead to heart failure. Multiple studies connect adverse maternal environment (AME) with cardiac fibrosis. AME does not always result in fibrosis, though. An additional "insult", such as an adult Western diet (WD), is frequently necessary. The additive effects of AME and adult WD on cardiac fibrosis is not well-understood. AME can also alter DNA methylation. DNA methyltransferase (DNMT) and ten-eleven translocation (TET) are methylation modifying genes that regulate DNA methylation, but it is unknown if AME changes cardiac gene expression of DNMT and TET. We sought to use a model of AME and adult WD to investigate the development of cardiac fibrosis and cardiac mRNA expression of DNMT and TET genes.

METHODS

We exposed dams to WD or control diet (CD) 5 weeks before pregnancy and through lactation. We added environmental stressors during the last third of pregnancy to dams on WD to create AME. Dams on CD experienced no added stressors to create control maternal environment (CME). Male offspring were weaned at Postnatal Week 3 (W3) and placed on WD or CD to create four groups: CME-CD, CME-WD, AME-CD, and AME-WD.

RESULTS

AME-WD increased cardiac fibrosis in adulthood (p < .05), whereas AME-CD and CME-WD did not. TET1-3 and DNMT3a mRNA levels decreased in AME versus CME offspring (p < .01).

CONCLUSION

AME increases susceptibility to cardiac fibrosis in adult male mice. Early-life changes to TET expression may mediate susceptibility to fibrosis, but further testing is needed.

Insights into hypoxic adaptation in Tibetan chicken embryos from comparative proteomics

Tibetan chicken, an indigenous breed, is highly adapted to the extreme environment of the Qinghai-Tibet Plateau. It serves as a model organism to identify genetic differences between hypoxia-adapted and lowland breeds. However, the mechanisms underlying hypoxia adaptation are yet unclear. This study aimed to identify differently abundant proteins (DAPs) and elucidate the mechanisms involved in hypoxic adaptation in the Tibetan chicken. In this study, we obtained proteome data for the embryonic heart tissues of Tibetan and Chahua chickens incubated under hypoxia (TCH and CHH) and normoxia (TCN and CHN) using isobaric tags for relative and absolute quantitation (iTRAQ) technology. We identified 4210 proteins from 53,352 unique peptides in the heart tissue of chicken embryos. Pairwise TCH vs. CHH, TCH vs. TCN, CHH vs. CHN, and TCN vs. CHN comparisons revealed 118, 176, 103, and 162 differently abundant proteins, respectively. Several key proteins (EGLN1, MAP2K2, MYLK, QARS, NOTCH2, and MYH7) and pathways (glutathione metabolism, PPAR signaling pathway, and vascular smooth muscle contraction) were identified and considered important candidates for high-altitude adaptation in Tibetan chicken. This study provides novel insights into the chicken embryonic heart tissue and furthers the current understanding of the mechanisms of survival among animals in high-altitude environments.

Perinatal changes in cardiac geometry and function in growth-restricted fetuses at term

OBJECTIVE

To evaluate the effect of fetal growth restriction (FGR) at term on fetal and neonatal cardiac geometry and function.

METHODS

This was a prospective study of 87 pregnant women delivering at term, comprising 54 normally grown and 33 FGR pregnancies. Fetal and neonatal conventional and spectral tissue Doppler and two-dimensional speckle tracking echocardiography were performed a few days before and within hours after birth. Fetal cardiac geometry, global myocardial deformation and performance and systolic and diastolic function were compared between normal and FGR pregnancies before and after birth.

RESULTS

Compared with normally grown fetuses, FGR fetuses exhibited more globular ventricular geometry and poorer myocardial deformation and cardiac function (left ventricular (LV) sphericity index (SI), 0.54 vs 0.49; right ventricular (RV) SI, 0.60 vs 0.54; LV torsion, 1.2 °/cm vs 3.0 °/cm; LV isovolumetric contraction time normalized by cardiac cycle length, 121 ms vs 104 ms; interventricular septum early diastolic myocardial peak velocity/atrial contraction myocardial diastolic peak velocity ratio, 0.60 vs 0.71; P < 0.01 for all). The poorest perinatal outcomes occurred in FGR fetuses with the most impaired cardiac functional indices. When compared with normally grown neonates, FGR neonates showed persistent alteration in cardiac parameters (LV-SI, 0.53 vs 0.50; RV-SI, 0.54 vs 0.44; LV torsion, 1.1 °/cm vs 1.4 °/cm; LV myocardial performance index (MPI'), 0.52 vs 0.42; P < 0.01 for all). Paired comparison of fetal vs neonatal cardiac indices in FGR demonstrated that birth was associated with a significant improvement in some, but not all, cardiac indices (RV-SI, 0.60 vs 0.54; RV-MPI', 0.49 vs 0.39; P < 0.001 for all).

CONCLUSIONS

Compared with normal pregnancies, FGR fetuses and neonates at term exhibit altered cardiac indices indicative of myocardial impairment that reflect adaptation to placental hypoxemia and alterations in hemodynamic load around the time of birth. Elucidating potential mechanisms that contribute to the alterations in perinatal cardiac adaptation in FGR could improve management and aid the development of better therapeutic strategies to reduce the risk of adverse pregnancy outcome. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Preeclampsia link to gestational hypoxia

Complications of pregnancy remain key drivers of morbidity and mortality, affecting the health of both the mother and her offspring in the short and long term. There is lack of detailed understanding of the pathways involved in the pathology and pathogenesis of compromised pregnancy, as well as a shortfall of effective prognostic, diagnostic and treatment options. In many complications of pregnancy, such as in preeclampsia, there is an increase in uteroplacental vascular resistance. However, the cause and effect relationship between placental dysfunction and adverse outcomes in the mother and her offspring remains uncertain. In this review, we aim to highlight the value of gestational hypoxia-induced complications of pregnancy in elucidating underlying molecular pathways and in assessing candidate therapeutic options for these complex disorders. Chronic maternal hypoxia not only mimics the placental pathology associated with obstetric syndromes like gestational hypertension at morphological, molecular and functional levels, but also recapitulates key symptoms that occur as maternal and fetal clinical manifestations of these pregnancy disorders. We propose that gestational hypoxia provides a useful model to study the inter-relationship between placental dysfunction and adverse outcomes in the mother and her offspring in a wide array of examples of complicated pregnancy, such as in preeclampsia.

Effects of low oxygen during chorioallantoic membrane development on post-hatch growing performance of broiler chickens

The prenatal circulatory system is adaptive and capable of plasticity designed for the needs of the growing tissue. When a broiler embryo is faced with hypoxic stress, the process of angiogenesis in tissues begins. Exposure to hypoxic conditions of 17% oxygen during the chorioallantoic membrane (CAM) development (E5 to E12) affected the circulatory system and contributed to an increase in the blood oxygen carrying capacity. The present study aimed to evaluate the effects of hypoxic exposure during CAM development on post-hatch performance of broilers and to examine whether hypoxic exposure improved sustainability of birds exposed to acute heat stress.Two consecutive trials, with male broilers from each of the incubation treatments-optimal conditions and exposure to hypoxia of 15 or 17% oxygen, for 12 h/day, during CAM development-were conducted. In experiment 1, 60 male chicks from each group were raised in individual cages. In experiment 2, 160 male chicks from each group were raised in 40-chick pens until marketing. On d 35, 20 birds from each group were transferred to individual cages kept at a temperature of 23°C for 72 h, and then birds were exposed to 35°C for 5 hours. Body temperatures were measured at 0, 2, and 5 h of the heat exposure. In both experiments BW, feed intake, and FCR were recorded. At marketing, chicks were slaughtered, and relative weights of breast muscle, abdominal fat pad, heart, and liver were calculated.Hypoxia treatment resulted in a FCR advantage. Food intake was similar in all treatments, but groups exposed to hypoxia grew better than controls until the age of 35 days. Hypoxia-treated groups had higher relative breast, heart, and liver weights than controls. Body temperatures of hypoxia-treated chickens remained lower during heat stress exposure, and their mortality rate was lower as well. Intermittent exposure to moderate hypoxia during CAM development confers advantages to broilers in feed utilization efficiency and in coping with heat stress. It may be considered as a mitigating step in incubation to facilitate broilers in achieving their full growth potential.

Isolating the direct effects of adverse developmental conditions on in vivo cardiovascular function at adulthood: the avian model

It is now well accepted that exposure to adverse environmental conditions in utero can predispose a fetus to disease later in life. Using an avian model to study the programming of disease has a unique advantage as it allows isolation of the direct effects of adverse conditions on fetal physiology, without any confounding effects via the mother or placenta. However, experiments in avian models are limited by the lack of well-established surgical protocols for the adult bird, which we have established in this study. Surgery was performed on seven young adult Bovan Brown chickens (body weight 1617±214 g, mean±s.d.) in order to instrument them with femoral arterial and venous catheters and a femoral arterial flow probe. Isoflurane and lidocaine were both found to have depressive effects on chicken cardiovascular function. Optimised methods of anaesthesia, intraoperative monitoring, surgical approach, postoperative care, and experimentation are described. Chickens recovered rapidly from surgery without significant blood gas perturbation, and basal in vivo cardiovascular studies were performed following 5 days of recovery. These techniques allow detailed investigation of avian cardiometabolic function, permitting determination of the consequences in later life of direct environmental insults to fetal physiology, isolated from additional effects on maternal physiology and/or placental endocrinology.

At the heart of programming: the role of micro-RNAs

Epidemiological and experimental observations tend to prove that environment, lifestyle or nutritional challenges influence heart functions together with genetic factors. Furthermore, when occurring during sensitive windows of heart development, these environmental challenges can induce an 'altered programming' of heart development and shape the future heart disease risk. In the etiology of heart diseases driven by environmental challenges, epigenetics has been highlighted as an underlying mechanism, constituting a bridge between environment and heart health. In particular, micro-RNAs which are involved in each step of heart development and functions seem to play a crucial role in the unfavorable programming of heart diseases. This review describes the latest advances in micro-RNA research in heart diseases driven by early exposure to challenges and discusses the use of micro-RNAs as potential targets in the reversal of the pathophysiology.

Preterm growth restriction and bronchopulmonary dysplasia: the vascular hypothesis and related physiology

KEY POINTS

Approximately 5-10% pregnancies are affected by fetal growth restriction. Preterm infants affected by fetal growth restriction have a higher incidence of bronchopulmonary dysplasia. The present study is the first to measure pulmonary artery thickness and stiffness. The findings show that impaired vasculogenesis may be a contributory factor in the higher incidence of bronchopulmonary dysplasia in preterm growth restricted infants. The study addresses the mechanistic link between fetal programming and vascular architecture and mechanics.

ABSTRACT

Bronchopulmonary dysplasia is the most common respiratory sequelae of prematurity and histopathologically features fewer, dysmorphic pulmonary arteries. The present study aimed to characterize pulmonary artery mechanics and cardiac function in preterm infants with fetal growth restriction (FGR) compared to those appropriate for gestational age (AGA) in the early neonatal period. This prospective study reviewed 40 preterm infants between 28 to 32 weeks gestational age (GA). Twenty infants had a birthweight <10th centile and were compared with 20 preterm AGA infants. A single high resolution echocardiogram was performed to measure right pulmonary arterial and right ventricular (RV) indices. The GA and birthweight of FGR and AGA infants were 29.8 ± 1.3 vs. 30 ± 0.9 weeks (P = 0.78) and 923.4 g ± 168 vs. 1403 g ± 237 (P < 0.001), respectively. Assessments were made at 10.5 ± 1.3 days after birth. The FGR infants had significantly thicker right pulmonary artery inferior wall (843.5 ± 68 vs. 761 ± 40 μm, P < 0.001) with reduced pulsatility (51.6 ± 7.6 μm vs. 59.7 ± 7.5 μm, P = 0.001). The RV contractility [fractional area change (28.7 ± 3.8% vs 32.5 ± 3.1%, P = 0.001), tricuspid annular peak systolic excursion (TAPSE) (5.2 ± 0.3% vs. 5.9 ± 0.7%, P = 0.0002) and myocardial performance index (0.35 ± 0.03 vs. 0.28 ± 0.02, P < 0.001)] was significantly impaired in FGR infants. Significant correlation between RV longitudinal contractility (TAPSE) and time to peak velocity/RV ejection time (measure of RV afterload) was noted (r²  =  0.5, P < 0.001). Altered pulmonary vascular mechanics and cardiac performance reflect maladaptive changes in response to utero-placental insufficiency. Whether managing pulmonary vascular disease will alter clinical outcomes remains to be studied prospectively.

Progress in the understanding of the etiology and predictability of fetal growth restriction

Fetal growth restriction (FGR) is defined as the failure of fetus to reach its growth potential for various reasons, leading to multiple perinatal complications and adult diseases of fetal origins. Shallow extravillous trophoblast (EVT) invasion-induced placental insufficiency and placental dysfunction are considered the main reasons for idiopathic FGR. In this review, first we discuss the major characteristics of anti-angiogenic state and the pro-inflammatory bias in FGR. We then elaborate major abnormalities in placental insufficiency at molecular levels, including the interaction between decidual leukocytes and EVT, alteration of miRNA expression and imprinted gene expression pattern in FGR. Finally, we review current animal models used in FGR, an experimental intervention based on animal models and the progress of predictive biomarker studies in FGR.Free Chinese abstract: A Chinese translation of this abstract is freely available at http://www.reproduction-online.org/content/153/6/R215/suppl/DC1.

Effects of foetal growth restriction and preterm birth on cardiac morphology and function during infancy

AIM

To investigate the effects of foetal growth restriction (FGR) and prematurity on cardiac morphology and function in infancy. We hypothesised that FGR and prematurity would both alter cardiac development.

METHODS

Cardiac morphology and function were evaluated in 24 preterm FGR infants (p-FGR) and 23 preterm and 19 term appropriately grown for gestational age infants (p-AGA and t-AGA, respectively) by conventional echocardiography and Tissue Doppler Imaging. p-FGR and p-AGA infants were studied on postnatal day 1 and all groups were studied at one-and six-months post-term age.

RESULTS

p-FGR infants demonstrated increased cardiac sphericity compared to AGA peers on postnatal day 1 (p = 0.004) and at one-month post-term age (p = 0.004). Posterior and relative wall thickness increased overtime in the p-FGR group only (p < 0.05). Systolic function was not different between groups. E/e' ratio was higher in both preterm groups compared to the term group at one-month post-term age (p = 0.01). No statistically significant group differences were found at six-months post-term age.

CONCLUSION

Foetal growth restriction was associated with subtle cardiac morphological changes, whereas both prematurity and FGR were associated with subclinical alterations in diastolic function.

Long-term cardiovascular consequences of fetal growth restriction: biology, clinical implications, and opportunities for prevention of adult disease

In the modern world, cardiovascular disease is a leading cause of death for both men and women. Epidemiologic studies consistently have suggested an association between low birthweight and/or fetal growth restriction and increased rate of cardiovascular mortality in adulthood. Furthermore, experimental and clinical studies have demonstrated that sustained nutrient and oxygen restriction that are associated with fetal growth restriction activate adaptive cardiovascular changes that might explain this association. Fetal growth restriction results in metabolic programming that may increase the risk of metabolic syndrome and, consequently, of cardiovascular morbidity in the adult. In addition, fetal growth restriction is strongly associated with fetal cardiac and arterial remodeling and a subclinical state of cardiovascular dysfunction. The cardiovascular effects ocurring in fetal life, includes cardiac morphology changes, subclinical myocardial dysfunction, arterial remodeling, and impaired endothelial function, persist into childhood and adolescence. Importantly, these changes have been described in all clinical presentations of fetal growth restriction, from severe early- to milder late-onset forms. In this review we summarize the current evidence on the cardiovascular effects of fetal growth restriction, from subcellular to organ structure and function as well as from fetal to early postnatal life. Future research needs to elucidate whether and how early life cardiovascular remodeling persists into adulthood and determines the increased cardiovascular mortality rate described in epidemiologic studies.

Cardiac Development and Transcription Factors: Insulin Signalling, Insulin Resistance, and Intrauterine Nutritional Programming of Cardiovascular Disease

Programming with an insult or stimulus during critical developmental life stages shapes metabolic disease through divergent mechanisms. Cardiovascular disease increasingly contributes to global morbidity and mortality, and the heart as an insulin-sensitive organ may become insulin resistant, which manifests as micro- and/or macrovascular complications due to diabetic complications. Cardiogenesis is a sequential process during which the heart develops into a mature organ and is regulated by several cardiac-specific transcription factors. Disrupted cardiac insulin signalling contributes to cardiac insulin resistance. Intrauterine under- or overnutrition alters offspring cardiac structure and function, notably cardiac hypertrophy, systolic and diastolic dysfunction, and hypertension that precede the onset of cardiovascular disease. Optimal intrauterine nutrition and oxygen saturation are required for normal cardiac development in offspring and the maintenance of their cardiovascular physiology.

A prospective observational study comparing cardiac function of small for gestational age with appropriate for gestational age babies using serial echocardiographic studies

BACKGROUND

Approximately 30% of babies born in India are low birth weight (LBW) and about 70% of LBW babies are small for gestational age (SGA). Though there are several trials that have evaluated cardiac function of intrauterine growth restricted (IUGR) babies in utero, there is limited data about postnatal cardiac function in SGA babies during early neonatal period. This study was conducted to evaluate the cardiac functions of SGA babies by serial echocardiographic measurements and compare this with appropriate for gestational age (AGA) babies during the early postnatal period.

MATERIAL AND METHODS

Seventy babies were enrolled in this prospective observational study with 35 each in the SGA and AGA groups. Echocardiography was performed for all babies on days 1, 2, and 3 of life. Myocardial performance index (MPI) was used as the primary measure to compare cardiac function. MPI was calculated for both ventricles using pulse wave Doppler and tissue Doppler.

RESULTS

MPI of the left ventricle was significantly higher in the SGA group as compared to AGA babies during all the three measurement periods with SGA babies having significantly higher MPI of right ventricle on day 1 and day 2 but not on day 3. Left ventricular internal diameter index during diastole and systole (LVIDD index and LVIDS index), left atrium: aortic root ratio (LA:AO ratio) were significantly increased in SGA babies on all the occasions. Fractional shortening, ejection fraction, and area shortening were similar in two groups.

CONCLUSIONS

Myocardial performance index of left and right ventricle, which evaluates both systolic and diastolic function of ventricles, was significantly increased in SGA babies in comparison to AGA babies during the first 3 days of life except MPI of the right ventricle on day 3. Thus, SGA babies have compromised cardiac function through all phases of the cardiac cycle with the performance improving spontaneously over time.

The highs and lows of programmed cardiovascular disease by developmental hypoxia: studies in the chicken embryo

It is now established that adverse conditions during pregnancy can trigger a fetal origin of cardiovascular dysfunction and/or increase the risk of heart disease in later life. Suboptimal environmental conditions during early life that may promote the development of cardiovascular dysfunction in the offspring include alterations in fetal oxygenation and nutrition as well as fetal exposure to stress hormones, such as glucocorticoids. There has been growing interest in identifying the partial contributions of each of these stressors to programming of cardiovascular dysfunction. However, in humans and in many animal models this is difficult, as the challenges cannot be disentangled. By using the chicken embryo as an animal model, science has been able to circumvent a number of problems. In contrast to mammals, in the chicken embryo the effects on the developing cardiovascular system of changes in oxygenation, nutrition or stress hormones can be isolated and determined directly, independent of changes in the maternal or placental physiology. In this review, we summarise studies that have exploited the chicken embryo model to determine the effects on prenatal growth, cardiovascular development and pituitary-adrenal function of isolated chronic developmental hypoxia.

Sleep: A Window Into Autonomic Control in Children Born Preterm and Growth Restricted

Study Objectives

Preterm birth and fetal growth restriction (FGR) are both associated with risk of hypertension in adulthood. Mechanisms leading to this pathology are unclear. In children aged 5-12 years, who were born preterm and FGR, we used sleep as a tool to assess autonomic control with assessment of cardiovascular structure and function.

Methods

Eighteen children born preterm and FGR, 15 children born preterm with appropriate birth weights for gestational age (AGA), and 20 AGA term-born children were studied. Children underwent overnight polysomnography with the addition of continuous noninvasive blood pressure (Finometer™). Spectral measures of heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity were assessed and overnight urinary catecholamine levels measured. Echocardiographic studies (Vivid7, GE Healthcare) were performed and vascular compliance assessed (Miller Instruments™). Statistical comparisons were adjusted for age and body size.

Results

Compared to term children, preterm AGA children had increased high frequency HRV (p < .05) and BPV (p < .05) during sleep, reflecting increased parasympathetic activation and blood pressure changes related to respiration. Preterm FGR children had smaller left ventricular lengths, ascending aorta, and left ventricular outflow tract diameter (p < .05 for all) and vascular compliance was positively correlated with gestational age (r2 = 0.93, p < .05).

Conclusions

FGR combined with preterm birth did not alter autonomic control but altered heart structure in children. In contrast, preterm birth alone altered autonomic control but had no change in heart structure. These changes in children born preterm and FGR may contribute, in part, to increased risk of cardiovascular disease later in life but by different mechanisms.

Cardiac Morphology and Function in Preterm Growth Restricted Infants: Relevance for Clinical Sequelae

OBJECTIVES

To assess cardiac morphology and function in preterm infants with fetal growth restriction (FGR) compared with an appropriate for gestational age cohort, and to ascertain clinical correlation with neonatal sequelae.

STUDY DESIGN

With informed consent, 20 infants born between 28 and 32 weeks of gestational age and birthweight (BW) <10th percentile were compared using conventional and tissue Doppler echocardiography with 20 preterm appropriate for gestational age infants. Total duration of respiratory support was recorded.

RESULTS

The gestational age and BW of the infants with FGR and appropriate for gestational age infants were 29.8 ± 1.3 weeks vs 30 ± 0.9 weeks (P = .78) and 923.4 ± 168 g vs 1403 ± 237 g (P < .001), respectively. Preterm infants with FGR had significantly greater interventricular septal hypertrophy, greater free wall thickening, and lower sphericity indices (1.53 ± 0.15 vs 1.88 ± 0.2; P < .001), signifying globular and hypertrophied hearts. The transmitral E/A ratio and isovolumic relaxation time, markers of diastolic function, were significantly increased in the FGR cohort (0.84 ± 0.05 vs 0.78 ± 0.03 [P < .001] and 61.4 ± 4.1 ms vs 53.2 ± 3.2 ms [P < .001], respectively). Ejection fraction, as measured by the rate corrected mean velocity of circumferential fiber shortening was reduced (1.93 ± 0.4 circ/second vs 2.77 ± 0.5 circ/second; P < .001) in the FGR cohort. On follow-up, the total duration of respiratory support was significantly longer in the FGR cohort, and correlated with tissue Doppler E/E' (r = 0.65; P = .001), mean velocity of circumferential fiber shortening (r = -0.64; P = .001) and mitral annular peak systolic excursion (r = -0.57; P = .008).

CONCLUSIONS

Preterm infants with FGR have altered cardiac function evident within days after birth, which is associated with respiratory sequelae.

Functional implications of maternal intake of flaxseed and its by-products during pregnancy and lactation on offspring

Purpose

The purpose of this review of the literature is to provide data about flaxseed intake during pregnancy and/or lactation and its effects in the offspring from birth to adulthood.

Design/methodology/approach

This review includes up-to-date information from evidence-based sources on flaxseed intake and its by-products, during pregnancy and lactation and its effects on male and female offspring, from post-weaning until adulthood. Topics included are effects on body mass; glycaemic metabolism; lipid profile; blood pressure and aortic structure; reproductive system and brain tissue.

Findings

The main effects of flaxseed or its by-products were observed in the cardiovascular system, where a lipid profile improvement and minor aortic remodelling were noticed, and in the cerebral development, where greater n-3 PUFA incorporation in the brain was detected.

Originality/value

The research done in this study, to understand the offspring response that were early exposed to the flaxseed components during pregnancy and lactation, may be the first step toward guiding future strategies for recommending the use of this seed during the offspring’s perinatal period.

Comparative transcriptomic and proteomic analyses provide insights into the key genes involved in high-altitude adaptation in the Tibetan pig

Tibetan pigs that inhabit the Tibetan Plateau exhibit striking phenotypic and physiological differences from lowland pigs, and have adapted well to extreme conditions. However, the mechanisms involved in regulating gene expression at high altitude in these animals are not fully understood. In this study, we obtained transcriptomic and proteomic data from the heart tissues of Tibetan and Yorkshire pigs raised in the highlands (TH and YH) and lowlands (TL and YL) via RNA-seq and iTRAQ (isobaric tags for relative and absolute quantitation) analyses, respectively. Comparative analyses of TH vs. YH, TH vs.TL, TL vs. YL, and YH vs. YL yielded 299, 169, 242, and 368 differentially expressed genes (DEGs), and 473, 297, 394, and 297 differentially expressed proteins (DEPs), respectively. By functional annotation of these DEGs and DEPs, genes that were enriched in the HIF-1 signaling pathway (NPPA, ERK2, ENO3, and EGLN3), VEGF signaling pathway (ERK2, A2M, FGF1, CTGF, and DPP4), and hypoxia-related processes (CRYAB, EGLN3, TGFB2, DPP4, and ACE) were identified as important candidate genes for high-altitude adaptation in the Tibetan pig. This study enhances our understanding of the molecular mechanisms involved in hypoxic adaptation in pigs, and furthers our understanding of human hypoxic diseases.

Fetal origins of adult cardiac disease: a novel approach to prevent fetal growth restriction induced cardiac dysfunction using insulin like growth factor

BACKGROUND

Fetal growth restriction (FGR) is a risk factor for adult cardiovascular disease. Intraplacental gene transfer of human insulin-like growth factor-1 (IGF-1) corrects birth weight in our mouse model of FGR. This study addresses long term effects of FGR on cardiac function and the potential preventive effect of IGF-1.

STUDY DESIGN

Laparotomy was performed on pregnant C57BL/6J mice at embryonic day 18 and pups were divided into three groups: Sham operated; FGR (induced by mesenteric uterine artery ligation); treatment (intraplacental injection of IGF-1 after uterine artery ligation). Pups were followed until 32 wk of life. Transthoracic echocardiography was performed starting at 12 wk.

RESULTS

Systolic cardiac function was significantly impaired in the FGR group with reduced fractional shortening compared with sham and treatment group starting at week 12 of life (20 ± 4 vs. 31 ± 5 vs. 32 ± 5, respectively, n = 12 for each group; P < 0.001) with no difference between the sham and treatment groups.

CONCLUSION

Intraplacental gene transfer of IGF-1 prevents FGR induced cardiac dysfunction. This suggests that in utero therapy may positively impact cardiac remodeling and prevent adult cardiovascular disease.

Persistence of Cardiac Remodeling in Preadolescents With Fetal Growth Restriction

BACKGROUND

Fetal growth restriction (FGR) affects 5% to 10% of newborns and is associated with increased cardiovascular mortality in adulthood. We evaluated whether prenatal cardiovascular changes previously demonstrated in FGR persist into preadolescence.

METHODS AND RESULTS

A cohort study of 58 FGR (defined as birth weight below 10th centile) and 94 normally grown fetuses identified in utero and followed-up into preadolescence (8-12 years of age) by echocardiography and 3-dimensional shape computational analysis. Compared with controls, FGR preadolescents had a different cardiac shape, with more spherical and smaller hearts. Left ventricular ejection fraction was similar among groups, whereas FGR had decreased longitudinal motion (decreased mitral annular systolic peak velocities: control median, 0.11 m/s [interquartile range, 0.09-0.12] versus FGR median 0.09 m/s [interquartile range, 0.09-0.10]; P<0.01) and impaired relaxation (isovolumic relaxation time: control, 0.21 ms [interquartile range, 0.12-0.35] versus FGR, 0.35 ms [interquartile range, 0.20-0.46]; P=0.04). Global longitudinal strain was decreased (control mean, -22.4% [SD, 1.37] versus FGR mean, -21.5% [SD, 1.16]; P<0.001) compensated by an increased circumferential strain and with a higher prevalence of postsystolic shortening in FGR as compared with controls. These differences persisted after adjustment for parental ethnicity and smoking, prenatal glucocorticoid administration, preeclampsia, gestational age at delivery, days in intensive care unit, sex, age, and body surface area at evaluation.

CONCLUSIONS

This study provides evidence that cardiac remodeling induced by FGR persists until preadolescence with findings similar to those reported in their prenatal life and childhood. The findings support the hypothesis of primary cardiac programming in FGR for explaining the association between low birth weight and cardiovascular risk in adulthood.

Increased regurgitant flow causes endocardial cushion defects in an avian embryonic model of congenital heart disease

BACKGROUND

The relationship between changes in endocardial cushion and resultant congenital heart diseases (CHD) has yet to be established. It has been shown that increased regurgitant flow early in embryonic heart development leads to endocardial cushion defects, but it remains unclear how abnormal endocardial cushions during the looping stages might affect the fully septated heart. The goal of this study was to reproducibly alter blood flow in vivo and then quantify the resultant effects on morphology of endocardial cushions in the looping heart and on CHDs in the septated heart.

METHODS

Optical pacing was applied to create regurgitant flow in embryonic hearts, and optical coherence tomography (OCT) was utilized to quantify regurgitation and morphology. Embryonic quail hearts were optically paced at 3 Hz (180 bpm, well above intrinsic rate 60-110 bpm) at stage 13 of development (3-4 weeks human) for 5 min. Pacing fatigued the heart and led to at least 1 h of increased regurgitant flow. Resultant morphological changes were quantified with OCT imaging at stage 19 (cardiac looping-4-5 weeks human) or stage 35 (4 chambered heart-8 weeks human).

RESULTS

All paced embryos imaged at stage 19 displayed structural changes in cardiac cushions. The amount of regurgitant flow immediately after pacing was inversely correlated with cardiac cushion size 24-h post pacing (P value < .01). The embryos with the most regurgitant flow and smallest cushions after pacing had a decreased survival rate at 8 days (P < .05), indicating that those most severe endocardial cushion defects were lethal. Of the embryos that survived to stage 35, 17/18 exhibited CHDs including valve defects, ventricular septal defects, hypoplastic ventricles, and common AV canal.

CONCLUSION

The data illustrate a strong inverse relationship in which regurgitant flow precedes abnormal and smaller cardiac cushions, resulting in the development of CHDs.

Early onset fetal growth restriction

Fetal growth restriction (FGR) diagnosed before 32 weeks is identified by fetal smallness associated with Doppler abnormalities and is associated with significant perinatal morbidity and mortality and maternal complications. Recent studies have provided new insights into pathophysiology, management options and postnatal outcomes of FGR. In this paper we review the available evidence regarding diagnosis, management and prognosis of fetuses diagnosed with FGR before 32 weeks of gestation.

Fetal in vivo continuous cardiovascular function during chronic hypoxia

Although the fetal cardiovascular defence to acute hypoxia and the physiology underlying it have been established for decades, how the fetal cardiovascular system responds to chronic hypoxia has been comparatively understudied. We designed and created isobaric hypoxic chambers able to maintain pregnant sheep for prolonged periods of gestation under controlled significant (10% O2) hypoxia, yielding fetal mean P(aO2) levels (11.5 ± 0.6 mmHg) similar to those measured in human fetuses of hypoxic pregnancy. We also created a wireless data acquisition system able to record fetal blood flow signals in addition to fetal blood pressure and heart rate from free moving ewes as the hypoxic pregnancy is developing. We determined in vivo longitudinal changes in fetal cardiovascular function including parallel measurement of fetal carotid and femoral blood flow and oxygen and glucose delivery during the last third of gestation. The ratio of oxygen (from 2.7 ± 0.2 to 3.8 ± 0.8; P < 0.05) and of glucose (from 2.3 ± 0.1 to 3.3 ± 0.6; P < 0.05) delivery to the fetal carotid, relative to the fetal femoral circulation, increased during and shortly after the period of chronic hypoxia. In contrast, oxygen and glucose delivery remained unchanged from baseline in normoxic fetuses. Fetal plasma urate concentration increased significantly during chronic hypoxia but not during normoxia (Δ: 4.8 ± 1.6 vs. 0.5 ± 1.4 μmol l(-1), P<0.05). The data support the hypotheses tested and show persisting redistribution of substrate delivery away from peripheral and towards essential circulations in the chronically hypoxic fetus, associated with increases in xanthine oxidase-derived reactive oxygen species.

Fetal cardiovascular remodeling persists at 6 months in infants with intrauterine growth restriction

OBJECTIVES

Intrauterine growth restriction is associated with increased cardiovascular risk later in life but the link between fetal disease and postnatal risk is not well-documented. We evaluated longitudinally the association between cardiovascular remodeling in small-for-gestational-age (SGA) fetuses and at 6 months of age.

METHODS

A cohort of 80 SGA fetuses (defined by estimated fetal and birth weights < 10(th) centile) delivered > 34 weeks' gestation was compared with 80 normally grown age-matched control fetuses, with follow-up at 6 months of corrected age (i.e. 6 months from estimated date of delivery according to first-trimester crown-rump length). Cardiovascular evaluation included a comprehensive echocardiographic assessment in both fetuses and infants and blood pressure and aortic intima-media thickness (aIMT) measurement in infants. Parameters were adjusted by linear regression analysis for gender, gestational age at delivery, pre-eclampsia, prenatal glucocorticoid exposure, Cesarean delivery, admission to neonatal intensive care unit and body surface area.

RESULTS

Both pre- and postnatally, when compared with controls, the SGA group showed a more globular cardiac shape (left sphericity index: controls 2.06 vs SGA 1.87 (P = 0.022) prenatally and 1.92 vs 1.67 (P = 0.007) postnatally), as well as signs of systolic longitudinal dysfunction (systolic annular peak velocity (S'): 7.2 vs 6.3 cm/s (P = 0.003) prenatally and 7.9 vs 6.4 cm/s (P < 0.001) postnatally; tricuspid annular plane systolic excursion: 7.2 vs 6.8 mm (P = 0.015) prenatally and 16.0 vs 14.2 mm (P < 0.001) postnatally) and diastolic dysfunction (left isovolumetric relaxation time: 46 vs 52 ms (P < 0.001) prenatally and 50 vs 57 ms (P = 0.034) postnatally). In addition, infants in the SGA group had increased mean blood pressure (mean: 61 vs 70 mmHg, P < 0.001) and maximum aIMT (0.57 vs 0.66 mm; P < 0.001).

CONCLUSIONS

Primary cardiovascular changes are already present in the SGA fetus and persist at 6 months of age. These data support prenatal cardiovascular remodeling as a mechanistic pathway of increased risk later in life in cases of SGA, regardless of Doppler abnormalities. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Cardiovascular Remodeling and Dysfunction Across a Range of Growth Restriction Severity in Small for Gestational Age Infants - Implications for Fetal Programming

BACKGROUND

The purpose of this study was to clarify cardiovascular structure and function in small for gestational age (SGA) infants across a range of intrauterine growth restriction (IUGR) severity.

METHODS AND RESULTS

This prospective study included 38 SGA infants and 30 appropriate for gestational age (AGA) infants. SGA infants were subclassified into severe and mild SGA according to the degree of IUGR. Cardiovascular structure and function were evaluated using echocardiography at 1 week of age. Compared with the AGA infants, both the severe and mild SGA infants showed increased left ventricular diastolic dimensions (severe SGA 10.2±2.4, mild SGA 8.2±1.3, and AGA 7.3±0.7 mm/kg, P<0.05 for all) and decreased global longitudinal strain (severe -21.1±1.6, mild -22.5±1.8, and AGA -23.8±1.8%, P<0.05 for all). Severe SGA infants showed a decreased mitral annular early diastolic velocity (severe 5.6±1.4 vs. AGA 7.0±1.3 cm/s, P<0.01) and increased isovolumic relaxation time (severe 51.3±9.2 vs. AGA 42.7±8.2 ms, P<0.01). Weight-adjusted aortic intima-media thickness and arterial wall stiffness were significantly greater in both SGA infant groups. These cardiovascular parameters tended to deteriorate with increasing IUGR severity.

CONCLUSIONS

SGA infants, including those with mild SGA, showed cardiovascular remodeling and dysfunction, which increased with IUGR severity. (Circ J 2016; 80: 2212-2220).

Human fetal growth restriction: a cardiovascular journey through to adolescence

Intrauterine growth restriction has been noted to adversely impact morbidity and mortality in the neonatal period as well as cardiovascular well-being in adolescence and adulthood. Recent data based on a wide range of ultrasound parameters during fetal and neonatal life has noted early and persistent involvement of the cardiovascular system. Some of these measures are predictive of long-term morbidities. Assessment of vascular mechanics is a new and novel concept in this population, and opens up avenues for diagnosis, monitoring and evaluation of the likely effectiveness of interventions. Prevention of these adverse vascular and cardiac outcomes secondary to fetal growth restriction may be feasible and of clinical relevance. This review focuses on growth restriction in humans with respect to cardiovascular remodeling and dysfunction during fetal life, persistence of functional cardiac impairment during early childhood and adolescence, and possible preventive strategies.

Intrauterine growth restriction: impact on cardiovascular development and function throughout infancy

Intrauterine growth restriction (IUGR) refers to the situation where a fetus does not grow according to its genetic growth potential. One of the main causes of IUGR is uteroplacental vascular insufficiency. Under these circumstances of chronic oxygen and nutrient deprivation, the growth-restricted fetus often displays typical circulatory changes, which in part represent adaptations to the suboptimal intrauterine environment. These fetal adaptations aim to preserve oxygen and nutrient supply to vital organs such as the brain, the heart, and the adrenals. These prenatal circulatory adaptations are thought to lead to an altered development of the cardiovascular system and "program" the fetus for life long cardiovascular morbidities. In this review, we discuss the alterations to cardiovascular structure, function, and control that have been observed in growth-restricted fetuses, neonates, and infants following uteroplacental vascular insufficiency. We also discuss the current knowledge on early life surveillance and interventions to prevent progression into chronic disease.

Melatonin rescues cardiovascular dysfunction during hypoxic development in the chick embryo

There is a search for rescue therapy against fetal origins of cardiovascular disease in pregnancy complicated by chronic fetal hypoxia, particularly following clinical diagnosis of fetal growth restriction (FGR). Melatonin protects the placenta in adverse pregnancy; however, whether melatonin protects the fetal heart and vasculature in hypoxic pregnancy independent of effects on the placenta is unknown. Whether melatonin can rescue fetal cardiovascular dysfunction when treatment commences following FGR diagnosis is also unknown. We isolated the effects of melatonin on the developing cardiovascular system of the chick embryo during hypoxic incubation. We tested the hypothesis that melatonin directly protects the fetal cardiovascular system in adverse development and that it can rescue dysfunction following FGR diagnosis. Chick embryos were incubated under normoxia or hypoxia (14% O2) from day 1 ± melatonin treatment (1 mg/kg/day) from day 13 of incubation (term ~21 days). Melatonin in hypoxic chick embryos rescued cardiac systolic dysfunction, impaired cardiac contractility and relaxability, increased cardiac sympathetic dominance, and endothelial dysfunction in peripheral circulations. The mechanisms involved included reduced oxidative stress, enhanced antioxidant capacity and restored vascular endothelial growth factor expression, and NO bioavailability. Melatonin treatment of the chick embryo starting at day 13 of incubation, equivalent to ca. 25 wk of gestation in human pregnancy, rescues early origins of cardiovascular dysfunction during hypoxic development. Melatonin may be a suitable antioxidant candidate for translation to human therapy to protect the fetal cardiovascular system in adverse pregnancy.

Prenatal hypoxia promotes atherosclerosis via vascular inflammation in the offspring rats

BACKGROUND

Hypoxia is a critical contributor to increased risks of cardiovascular diseases, including atherosclerosis, but the detailed mechanism that hypoxia leads to atherosclerosis remains unknown.

METHODS

Pregnant rats were treated with hypoxia (10.5% oxygen) during pregnancy, and HUVEC cells treated with 1% of oxygen. Blood lipids were tested at fetal stage and adult stage of offspring rats; the level of pro-inflammatory cytokines of HUVEC and offspring rats were investigated, and HIF-1α and NFκB mRNA level were also measured by Q-PCR and Elisa.

RESULTS

We found that TC, LDL-C, ox-LDL-C, and the receptors of ox-LDL-C (lox-1) of the adult offspring were significantly higher than that of the control, while HDL-C was significantly reduced in hypoxia group. The internal elastic lamina was blocked by smooth muscle cells; and the migration of smooth muscle cells into the intima were observed in hypoxia offspring. Luciferase reporter gene experiment showed that HIF-1α activated NFκB transcription at four discrete binding sites of NFκBp65 promoter, although there was no obvious difference among the four discrete binding sites. Using transfection of pCDNA3.1-HIF-1α on HUVEC cells, HIF-1α significantly activated NFκB transcription at hypoxic conditions (1% O2), and concurrent with increased expression of IL-1β and TNF-α.

CONCLUSION

Hypoxia during pregnancy activated NFκB transcription to induce pro-inflammatory cytokines, leading to the early stage of atherosclerosis.