Maternal nutrient restriction during pregnancy and lactation leads to impaired right ventricular function in young adult baboons

Late-gestation maternal undernutrition induces circulatory redistribution while preserving uteroplacental function independent of fetal glycaemic state

Programming effects of maternal undernutrition on fetal metabolic and cardiovascular systems are well elucidated, yet a detailed characterization of maternal haemodynamics is not available. This study used comprehensive cardiovascular magnetic resonance (CMR) imaging to quantify maternal haemodynamics after 29 days (111-140 days) of late-gestation undernutrition (LGUN) in pregnant sheep. Control ewes received 100% of metabolizable energy requirements (MERs, n = 15), whereas LGUN ewes were globally nutrient restricted to 50% MER (n = 18), with a subset of fetuses undergoing continuous glucose infusion (LGUN + G, n = 6/18). Ewes underwent CMR (138-140 days' gestation), and placental tissue was collected the next day. Ewes in both LGUN groups had reduced body weight and mean blood glucose concentration across gestation. Ventricular dimensions were lower in both LGUN groups. Uterine artery blood flow (QUtA) was elevated in the LGUN group compared with controls, whereas peripheral blood flow was reduced and further diminished in LGUN + G. Maternal weight change correlated with all haemodynamic parameters across all groups. Uteroplacental oxygen and glucose delivery were increased in LGUN compared to control ewes, whereas uteroplacental oxygen consumption was preserved. LGUN did not impact placental or fetal weight, and markers of brain-sparing physiology were absent. Placental expression of insulin-like growth factors (IGF-1 and IGF-2) and their receptors, glucose, fatty acid (FA) or amino acid transporters and markers of angiogenesis was not impacted. FA transporter expression was positively correlated with QUtA, and FA binding protein correlated negatively with maternal weight change. Maternal cardiovascular adaptations in response to LGUN manifest as preservation of placental growth and function, thereby preserving fetal growth. KEY POINTS: Maternal undernutrition during pregnancy alters fetal metabolic and cardiovascular physiology, but little is known about alterations in maternal haemodynamics. Late-gestation undernutrition (LGUN) and LGUN + G redirected maternal blood flow from the periphery to the uteroplacental unit, concomitantly increasing the delivery of glucose and oxygen to the uteroplacental unit. Substrate transporter expression and uteroplacental oxygen consumption were preserved in LGUN and LGUN + G, suggesting prioritization of the placenta. This study is the first to report detailed maternal haemodynamics in the setting of maternal undernutrition, where placental growth and function were maintained, ultimately preserving fetal oxygen metabolism and growth.

Cardiac Molecular Analysis Reveals Aging-Associated Metabolic Alterations Promoting Glycosaminoglycans Accumulation via Hexosamine Biosynthetic Pathway

Age is a prominent risk factor for cardiometabolic disease, often leading to heart structural and functional changes. However, precise molecular mechanisms underlying cardiac remodeling and dysfunction exclusively resulting from physiological aging remain elusive. Previous research demonstrated age-related functional alterations in baboons, analogous to humans. The goal of this study is to identify early cardiac molecular alterations preceding functional adaptations, shedding light on the regulation of age-associated changes. Unbiased transcriptomics of left ventricle samples are performed from female baboons aged 7.5-22.1 years (human equivalent ≈30-88 years). Weighted-gene correlation network and pathway enrichment analyses are performed, with histological validation. Modules of transcripts negatively correlated with age implicated declined metabolism-oxidative phosphorylation, tricarboxylic acid cycle, glycolysis, and fatty-acid β-oxidation. Transcripts positively correlated with age suggested a metabolic shift toward glucose-dependent anabolic pathways, including hexosamine biosynthetic pathway (HBP). This shift is associated with increased glycosaminoglycan synthesis, modification, precursor synthesis via HBP, and extracellular matrix accumulation, verified histologically. Upregulated extracellular matrix-induced signaling coincided with glycosaminoglycan accumulation, followed by cardiac hypertrophy-related pathways. Overall, these findings revealed a transcriptional shift in metabolism favoring glycosaminoglycan accumulation through HBP before cardiac hypertrophy. Unveiling this metabolic shift provides potential targets for age-related cardiac diseases, offering novel insights into early age-related mechanisms.

Early postnatal moderate catch‑up growth in rats with nutritional intrauterine growth restriction preserves pulmonary vascular and cognitive function in adulthood

Intrauterine growth restriction (IUGR) with rapid postnatal catch-up growth is strongly associated with pulmonary vascular dysfunction in adulthood, whereas IUGR with delayed growth in early postnatal life results in long-term brain deficits. In the present study, it was hypothesized that IUGR with early moderate catch-up growth may alleviate pulmonary vascular remodeling in adulthood without affecting memory function. An IUGR model was established by restricting maternal nutrition during pregnancy. Different growth patterns were achieved by adjusting the litter size in each group during lactation. Rats meeting the weight requirement at weaning were selected for subsequent studies at three time points (3, 9 and 13 weeks). Cognitive function was evaluated using a Y-maze. Invasive hemodynamic measurements were conducted to measure the mean pulmonary arterial pressure (mPAP). In addition, primary pulmonary artery smooth muscle cells (PASMCs) and pulmonary vascular endothelial cells (PVECs) were cultured to investigate their role in the increase in mPAP following rapid catch-up growth. The results showed that memory function deficits in the rats in the delayed growth group were associated with reduced proliferation of neural stem cells in the subgranular zone of the hippocampus. Furthermore, moderate catch-up growth at the three time points improved memory function while maintaining a normal mPAP. In adult IUGR rats experiencing rapid catch-up growth, although memory function improved, elevated mPAP and medial thickening of pulmonary arterioles were observed. Additionally, PASMCs exhibited excessive proliferation, migration and anti-apoptotic activity in the rapid catch-up group, and PVECs also displayed excessive proliferation. These results suggested that moderate catch-up growth after IUGR is a better strategy for optimal cognition and cardiovascular health in adulthood compared with rapid catch-up growth or delayed growth.

Cardiac Molecular Analysis Reveals Aging-Associated Metabolic Alterations Promoting Glycosaminoglycans Accumulation Via Hexosamine Biosynthetic Pathway

Age is a prominent risk factor for cardiometabolic disease, and often leads to heart structural and functional changes. However, precise molecular mechanisms underlying cardiac remodeling and dysfunction resulting from physiological aging per se remain elusive. Understanding these mechanisms requires biological models with optimal translation to humans. Previous research demonstrated that baboons undergo age-related reduction in ejection fraction and increased heart sphericity, mirroring changes observed in humans. The goal of this study was to identify early cardiac molecular alterations that precede functional adaptations, shedding light on the regulation of age-associated changes. We performed unbiased transcriptomics of left ventricle (LV) samples from female baboons aged 7.5-22.1 years (human equivalent ~30-88 years). Weighted-gene correlation network and pathway enrichment analyses were performed to identify potential age-associated mechanisms in LV, with histological validation. Myocardial modules of transcripts negatively associated with age were primarily enriched for cardiac metabolism, including oxidative phosphorylation, tricarboxylic acid cycle, glycolysis, and fatty-acid β-oxidation. Transcripts positively correlated with age suggest upregulation of glucose uptake, pentose phosphate pathway, and hexosamine biosynthetic pathway (HBP), indicating a metabolic shift towards glucose-dependent anabolic pathways. Upregulation of HBP commonly results in increased glycosaminoglycan precursor synthesis. Transcripts involved in glycosaminoglycan synthesis, modification, and intermediate metabolism were also upregulated in older animals, while glycosaminoglycan degradation transcripts were downregulated with age. These alterations would promote glycosaminoglycan accumulation, which was verified histologically. Upregulation of extracellular matrix (ECM)-induced signaling pathways temporally coincided with glycosaminoglycan accumulation. We found a subsequent upregulation of cardiac hypertrophy-related pathways and an increase in cardiomyocyte width. Overall, our findings revealed a transcriptional shift in metabolism from catabolic to anabolic pathways that leads to ECM glycosaminoglycan accumulation through HBP prior to upregulation of transcripts of cardiac hypertrophy-related pathways. This study illuminates cellular mechanisms that precede development of cardiac hypertrophy, providing novel potential targets to remediate age-related cardiac diseases.

Interventions for placental insufficiency and fetal growth restriction

Pregnancy complications adversely impact both mother and/or fetus throughout the lifespan. Fetal growth restriction (FGR) occurs when a fetus fails to reach their intrauterine potential for growth, it is the second highest leading cause of infant mortality, and leads to increased risk of developing non-communicable diseases in later life due 'fetal programming'. Abnormal placental development, growth and/or function underlies approximately 75% of FGR cases and there is currently no treatment save delivery, often prematurely. We previously demonstrated in a murine model of FGR that nanoparticle mediated, intra-placental human IGF-1 gene therapy maintains normal fetal growth. Multiple models of FGR currently exist reflecting the etiologies of human FGR and have been used by us and others to investigate the development of in utero therapeutics as discussed here. In addition to the in vivo models discussed herein, utilizing human models including in vitro (Choriocarcinoma cell lines and primary trophoblasts) and ex vivo (term villous fragments and placenta cotyledon perfusion) we have demonstrated robust nanoparticle uptake, transgene expression, nutrient transporter regulation without transfer to the fetus. For translational gene therapy application in the human placenta, there are multiple avenues that require investigation including syncytial uptake from the maternal circulation, transgene expression, functionality and longevity of treatment, impact of treatment on the mother and developing fetus. The potential impact of treating the placenta during gestation is high, wide-ranging across pregnancy complications, and may offer reduced risk of developing associated cardio-metabolic diseases in later life impacting at both an individual and societal level.

Molecular Approaches for the Validation of the Baboon as a Nonhuman Primate Model for the Study of Zika Virus Infection

Nonhuman primates (NHP) are particularly important for modeling infections with viruses that do not naturally replicate in rodent cells. Zika virus (ZIKV) has been responsible for sporadic epidemics, but in 2015 a disseminated outbreak of ZIKV resulted in the World Health Organization declaring it a global health emergency. Since the advent of this last epidemic, several NHP species, including the baboon, have been utilized for modeling and understanding the complications of ZIKV infection in humans; several health issues related to the outcome of infection have not been resolved yet and require further investigation. This study was designed to validate, in baboons, the molecular signatures that have previously been identified in ZIKV-infected humans and macaque models. We performed a comprehensive molecular analysis of baboons during acute ZIKV infection, including flow cytometry, cytokine, immunological, and transcriptomic analyses. We show here that, similar to most human cases, ZIKV infection of male baboons tends to be subclinical, but is associated with a rapid and transient antiviral interferon-based response signature that induces a detectable humoral and cell-mediated immune response. This immunity against the virus protects animals from challenge with a divergent ZIKV strain, as evidenced by undetectable viremia but clear anamnestic responses. These results provide additional support for the use of baboons as an alternative animal model to macaques and validate omic techniques that could help identify the molecular basis of complications associated with ZIKV infections in humans.

Targeting Myadm to Intervene Pulmonary Hypertension on Rats Before Pregnancy Alleviates the Effect on Their Offspring's Cardiac-Cerebral Systems

Pregnancy with pulmonary hypertension (PH) seriously threatens the life and safety of mothers and infants. Here, the long-term effect of maternal PH on the postpartum growth of rat offspring was focused for the first time, as well as explored the role of Myadm in PH rats before pregnancy based upon the previous findings. Patients with PH are prone to hypoxemia, leading to insufficient placental structure and function, which affects the organ function of fetuses, followed by evidence that differently expressed genes (DEGs) existed in the heart of maternal PH newborn rats and enriched in pathways related to cardiac and nerve development on human infants with similar birth outcome: low birth weight (LBW). LBW was one of the possible birth outcomes of pregnancy with PH, especially severe PH, accompanied by evidence that offspring derived from mothers with PH presented lower birth weights and slower growth rates than those derived from normal control mothers in a rat model. Besides, maternal PH rat offspring showed cardiac remodeling and a significant elevation of the expression levels of hypoxia- and inflammation-related markers in the cerebral cortex at both 10 and 14 weeks of age, respectively. What is more, the previous studies found that the overexpression of Myadm could result in the remodeling of the pulmonary artery. And targeting Myadm to intervene PH before pregnancy could alleviate sustained low weight growth in maternal PH rat offspring, and the pathological changes of the cardiac–cerebral system caused by maternal PH, including enlarged right heart cavity, loss of cardiomyocytes, abnormal heart index, as well as cerebral cortex hypoxia and the inflammatory state as they grew up to a certain extent. The findings show the pathological significance of maternal PH on offspring growth and the cardiac–cerebral development in a rat model, as well as point out the potential treatment target, which may provide a further reference for pregnancy outcomes in women with PH and healthy development of offspring to some extent.

Summary and Assessment of Studies on Cardiac Aging in Nonhuman Primates

Nonhuman primates (NHP) are important translational models for cardiac aging. To assess progress in this research area and to provide a reference for other investigators, we identified papers indexed in PubMed to determine what species, ages, outcomes, treatments, and approaches have been studied. Since 1983, 33 studies of cardiac aging in NHP have been published. Of these, 27 used species of macaque, 6 baboon, 1 vervet, 1 orangutan, and 1 marmoset (some studies were multispecies). Common research approaches were echocardiography, ECG, and histology of the left ventricle. Only 10 studies performed sex-based analyses. The average age of the oldest macaque studied was 26 y. The reported mean lifespan of macaques in captivity is around 30 y. The age of the oldest baboon studied was 24 y. Baboons in captivity are reported to live on average to 21 y. Twelve studies took a "life course" approach, studying animals of a wide range of ages from less than or equal to 10 y through the late teens to thirties, and employing analyses designed to show change over time. Keeping NHP into old age is a major challenge for biomedical research. The ideal design is to start monitoring in early life and to track how cardiac structure and function change with age. Important issues for future research are an increased focus on life-course approaches, investment in existing life-course NHP cohorts, better reporting of study sample characteristics, more molecular studies to identify genetic risk factors and mechanisms, attention to sex as a biological variable, a move away from descriptive reports to mechanistic studies, development of biomarkers to predict disease risk, and exploration of interventions that are implemented early in life to prevent or delay age-related disease later in life. Reducing exposure to early life adversity, identifying early-life biomarkers of aging and age-related disease, and early treatment can contribute to longer health span.

Malnutrition, poor post-natal growth, intestinal dysbiosis and the developing lung

In extremely preterm infants, poor post-natal growth, intestinal dysbiosis and bronchopulmonary dysplasia are common, and each is associated with long-term complications. The central hypothesis that this review will address is that these three common conditions are interrelated. Challenges to studying this hypothesis include the understanding that malnutrition and poor post-natal growth are not synonymous and that there is not agreement on what constitutes a normal intestinal microbiota in this evolutionarily new population. If this hypothesis is supported, further study of whether "correcting" intestinal dysbiosis in extremely preterm infants reduces postnatal growth restriction and/or bronchopulmonary dysplasia is indicated.

Unravelling the impact of intrauterine growth restriction on heart development: insights into mitochondria and sexual dimorphism from a non-hominoid primate

Fetal exposure to an unfavorable intrauterine environment programs an individual to have a greater susceptibility later in life to non-communicable diseases, such as coronary heart disease, but the molecular processes are poorly understood. An article in Clinical Science recently reported novel details on the effects of maternal nutrient reduction (MNR) on fetal heart development using a primate model that is about 94% genetically similar to humans and is also mostly monotocous. MNR adversely impacted fetal left ventricular (LV) mitochondria in a sex-dependent fashion with a greater effect on male fetuses, although mitochondrial transcripts increased more so in females. Increased expression for several respiratory chain and adenosine triphosphate (ATP) synthase proteins were observed. However, fetal LV mitochondrial complex I and complex II/III activities were significantly decreased, likely contributing to a 73% decreased LV ATP content and increased LV lipid peroxidation. Moreover, MNR fetal LV mitochondria showed sparse and disarranged cristae. This study indicates that mitochondria are targets of the remodeling and imprinting processes in a sex-dependent manner. Mitochondrial ROS production and inadequate energy production add another layer of complexity. Altogether these observations raise the possibility that dysfunctional mitochondria in the fetus may contribute in turn to epigenetic memory of in utero stress in the adult. The role of mitoepigenetics and involvement of mitochondrial and genomic non-coding RNAs in mitochondrial functions and nuclei-mitochondria crosstalk with in utero stress awaits further investigation.

Placental insufficiency induces a sexually dimorphic response in the expression of cardiac growth and metabolic signalling molecules upon exposure to a postnatal western diet in guinea pigs

There is a strong relationship between low birth weight (LBW) and an increased risk of developing cardiovascular disease (CVD). In postnatal life, LBW offspring are becoming more commonly exposed to the additional independent CVD risk factors, such as an obesogenic diet. However, how an already detrimentally programmed LBW myocardium responds to a secondary insult, such as an obesogenic diet (western diet; WD), during postnatal life is ill defined. Herein, we aimed to determine in a pre-clinical guinea pig model of CVD, both the independent and interactive effects of LBW and a postnatal WD on the molecular pathways that regulate cardiac growth and metabolism. Uterine artery ablation was used to induce placental insufficiency (PI) in pregnant guinea pigs to generate LBW offspring. Normal birth weight (NBW) and LBW offspring were weaned onto either a Control diet or WD. At ˜145 days after birth (young adulthood), male and female offspring were humanely killed, the heart weighed and left ventricle tissue collected. The mRNA expression of signalling molecules involved in a pathological hypertrophic and fibrotic response was increased in the myocardium of LBW male, but not female offspring, fed a WD as was the mRNA expression of transcription factors involved in fatty acid oxidation. The mRNA expression of glucose transporters was downregulated by LBW and WD in male, but not female hearts. This study has highlighted a sexually dimorphic cardiac pathological hypertrophic and fibrotic response to the secondary insult of postnatal WD consumption in LBW offspring.

Sex-dependent vulnerability of fetal nonhuman primate cardiac mitochondria to moderate maternal nutrient reduction

Poor maternal nutrition in pregnancy affects fetal development, predisposing offspring to cardiometabolic diseases. The role of mitochondria during fetal development on later-life cardiac dysfunction caused by maternal nutrient reduction (MNR) remains unexplored. We hypothesized that MNR during gestation causes fetal cardiac bioenergetic deficits, compromising cardiac mitochondrial metabolism and reserve capacity. To enable human translation, we developed a primate baboon model (Papio spp.) of moderate MNR in which mothers receive 70% of control nutrition during pregnancy, resulting in intrauterine growth restriction (IUGR) offspring and later exhibiting myocardial remodeling and heart failure at human equivalent ∼25 years. Term control and MNR baboon offspring were necropsied following cesarean-section, and left ventricle (LV) samples were collected. MNR adversely impacted fetal cardiac LV mitochondria in a sex-dependent fashion. Increased maternal plasma aspartate aminotransferase, creatine phosphokinase (CPK), and elevated cortisol levels in MNR concomitant with decreased blood insulin in male fetal MNR were measured. MNR resulted in a two-fold increase in fetal LV mitochondrial DNA (mtDNA). MNR resulted in increased transcripts for several respiratory chain (NDUFB8, UQCRC1, and cytochrome c) and adenosine triphosphate (ATP) synthase proteins. However, MNR fetal LV mitochondrial complex I and complex II/III activities were significantly decreased, possibly contributing to the 73% decreased ATP content and increased lipid peroxidation. MNR fetal LV showed mitochondria with sparse and disarranged cristae dysmorphology. Conclusion: MNR disruption of fetal cardiac mitochondrial fitness likely contributes to the documented developmental programming of adult cardiac dysfunction, indicating a programmed mitochondrial inability to deliver sufficient energy to cardiac tissues as a chronic mechanism for later-life heart failure.

Cardiac magnetic resonance imaging: insights into developmental programming and its consequences for aging

Cardiovascular diseases (CVD) are important consequences of adverse perinatal conditions such as fetal hypoxia and maternal malnutrition. Cardiac magnetic resonance imaging (CMR) can produce a wealth of physiological information related to the development of the heart. This review outlines the current state of CMR technologies and describes the physiological biomarkers that can be measured. These phenotypes include impaired ventricular and atrial function, maladaptive ventricular remodeling, and the proliferation of myocardial steatosis and fibrosis. The discussion outlines the applications of CMR to understanding the developmental pathways leading to impaired cardiac function. The use of CMR, both in animal models of developmental programming and in human studies, is described. Specific examples are given in a baboon model of intrauterine growth restriction (IUGR). CMR offers great potential as a tool for understanding the sequence of dysfunctional adaptations of developmental origin that can affect the human cardiovascular system.

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.

Perinatal maternal undernutrition does not result in offspring capillary rarefaction in the middle-aged male baboon at rest

Microvascular health is a main determinant of coronary blood flow reserve and myocardial vascular resistance. Extracardiac capillary abnormality has been reported in subjects at increased coronary heart disease risk, such as prehypertension, hypertension, diabetes, hyperlipidemia, and atherosclerosis. We have reported cardiovascular dysfunction in a cohort of maternal nutrient reduction (MNR)-induced intrauterine growth restriction (IUGR) baboon offspring. Here we test the hypothesis that there is oral capillary rarefaction associated with MNR-induced IUGR. Capillary density was quantified using in vivo high-power capillaroscopy on seven middle-aged (~10.7 yr; human equivalent ~40 yr) male IUGR baboons and seven male age-matched controls in the lateral buccal and inferior labial mucosa. While no difference was found between groups in either area by fraction area or optical density for these vascular beds derived from fetal preductal vessels, further studies are needed on post-ductal vascular beds, retina, and function.

Strength of nonhuman primate studies of developmental programming: review of sample sizes, challenges, and steps for future work

Nonhuman primate (NHP) studies are crucial to biomedical research. NHPs are the species most similar to humans in lifespan, body size, and hormonal profiles. Planning research requires statistical power evaluation, which is difficult to perform when lacking directly relevant preliminary data. This is especially true for NHP developmental programming studies, which are scarce. We review the sample sizes reported, challenges, areas needing further work, and goals of NHP maternal nutritional programming studies. The literature search included 27 keywords, for example, maternal obesity, intrauterine growth restriction, maternal high-fat diet, and maternal nutrient reduction. Only fetal and postnatal offspring studies involving tissue collection or imaging were included. Twenty-eight studies investigated maternal over-nutrition and 33 under-nutrition; 23 involved macaques and 38 baboons. Analysis by sex was performed in 19; minimum group size ranged from 1 to 8 (mean 4.7 ± 0.52, median 4, mode 3) and maximum group size from 3 to 16 (8.3 ± 0.93, 8, 8). Sexes were pooled in 42 studies; minimum group size ranged from 2 to 16 (mean 5.3 ± 0.35, median 6, mode 6) and maximum group size from 4 to 26 (10.2 ± 0.92, 8, 8). A typical study with sex-based analyses had group size minimum 4 and maximum 8 per sex. Among studies with sexes pooled, minimum group size averaged 6 and maximum 8. All studies reported some significant differences between groups. Therefore, studies with group sizes 3-8 can detect significance between groups. To address deficiencies in the literature, goals include increasing age range, more frequently considering sex as a biological variable, expanding topics, replicating studies, exploring intergenerational effects, and examining interventions.

Postnatal delayed growth impacts cognition but rescues programmed impaired pulmonary vascular development in an IUGR rat model

BACKGROUND AND AIMS

Intrauterine growth restriction (IUGR) is a state of slower fetal growth usually followed by a catch-up growth. Postnatal catch-up growth in IUGR models increases the incidence of pulmonary arterial hypertension in adulthood. Here, we hypothesize that the adverse pulmonary vascular consequences of IUGR may be improved by slowing down postnatal growth velocity. Meanwhile, cognitive function was also studied.

METHODS AND RESULTS

We established an IUGR rat model by restricting maternal food throughout gestation. After birth, pups were fed a regular or restricted diet during lactation by changing litter size. Thus, there were three experimental groups according to the dam/offspring diet: C/C (gold standard), IUGR with catch-up growth (R/C) and IUGR with delayed growth (R/D). In adulthood (14 weeks of age), we assessed pulmonary vascular development by hemodynamic measurement and immunohistochemistry. Our results showed that adult R/C offspring developed an elevated mean pulmonary arterial pressure (mPAP) and pulmonary arteriolar remodeling accompanied with decreased eNOS mRNA and protein expressions compared to C/C or R/D offspring. This suggested that delayed postnatal growth improved pulmonary circulation compared to postnatal catch-up growth. Conversely, adult R/D offspring performed poorly in cognition. Behavior test and electrophysiology results exhibited a reduced synaptic plasticity. Furthermore, decreased mRNA expression levels of the memory-related gene zif268 and transcription factor recruitment factor p300 in the hippocampus region were also observed in R/D group.

CONCLUSION

These findings indicate that delayed postnatal growth results in cognitive impairment, but it reverses elevations in mPAP induced by postnatal catch-up growth following IUGR.

Small-for-gestational-age birth is linked to cardiovascular dysfunction in early childhood

BACKGROUND

The aim of this study was to assess clinical and echographic markers of cardiovascular dysfunction in infants born small for gestational age (SGA) compared to a control group of subjects born adequate for gestational age (AGA).

METHODS

This was a single-center cross-sectional case-control study. We recruited 20 SGA and 20 gestational age-matched AGA subjects at 24 months of age. The study population underwent anthropometric and Doppler 2-dimensional echocardiographic assessments, and carotid artery intima-media thickness (cIMT) and endothelium-dependent vasodilation evaluation (FMD). The pressure-volume curve during diastole was calculated using the algorithm for the elastance calculation on 1 single beat.

RESULTS

SGA children showed lower stroke volume, lower left ventricle (LV) dimensions and volume, and greater LV thickness. Diastolic function was impaired in SGA with lower capacitance and higher elastance. Birth weight standard deviation score was positively associated with capacitance and negatively associated with E/E' ratio and elastance, and in SGA infants, the end-diastolic pressure-related volume curve was shifted to the left compared to AGA. cIMT and systemic vascular resistance were significantly higher, while FMD was lower, in SGA compared to AGA; birth weight standard deviation score was directly correlated with FMD and inversely correlated with cIMT. Finally, a longer breastfeeding duration was associated to a lower cIMT even after correction for confounding factors.

CONCLUSIONS

This study shows that infants born SGA present an early and subtle cardiovascular dysfunction compared to AGA controls. These alterations are strongly related to weight at birth. Finally, breastfeeding exerts an important protective and beneficial cardiovascular effect.

Epigenetic Modulation in the Initiation and Progression of Pulmonary Hypertension

Pulmonary hypertension (PH) is a severe disease with multiple etiologies. In addition to genetics, recent studies have revealed the epigenetic modulation in the initiation and progression of PH. In this review, we summarize the epigenetic mechanisms in the pathogenesis of PH, specifically, DNA methylation, histone modifications, and microRNAs. We further emphasize the diagnostic and therapeutic potential of these epigenetic hallmarks in PH. Finally, we highlight the developmental reprogramming in adult-onset PH because of adverse perinatal exposures such as intrauterine growth restriction and extrauterine growth restriction. Therefore, epigenetic modifications provide promise for the therapy and prevention of PH.

Effect of maternal baboon (Papio sp.) dietary mismatch in pregnancy and lactation on post-natal offspring early life phenotype

BACKGROUND

Non-human primate models of developmental programing by maternal mismatch between pregnancy and lactation diets are needed for translation to human programing outcomes. We present baboon offspring morphometry from birth to 3 years, and blood cortisol and adrenocorticotropin (ACTH) from 2 to 24 months.

METHODS

Control mothers ate chow; mismatch mothers ate 30% less than controls during pregnancy and high-fat high-energy diet through lactation.

RESULTS

Mismatch mothers lost weight during pregnancy. At birth, there were trends toward lower weight in mismatch offspring of both sexes (P = 0.06). From 0-3 years, catch-up growth occurred. Mismatch offspring male and female body weight increased faster than controls (P < 0.001). Mismatch female offspring showed greater increase in BMI (P < 0.001) and abdominal circumference (P = 0.008) vs controls. ACTH and cortisol slopes from 2 to 24 months of age were similar between groups in both sexes. Cortisol and ACTH increased after weaning in all groups.

CONCLUSIONS

Mismatch produces sexually dimorphic post-natal growth phenotypes.

Antenatal Synthetic Glucocorticoid Exposure at Human Therapeutic Equivalent Doses Predisposes Middle-Age Male Offspring Baboons to an Obese Phenotype That Emerges With Aging

INTRODUCTION

Women threatening premature delivery receive synthetic glucocorticoids (sGC) to accelerate fetal lung maturation, reducing neonatal mortality and morbidity. Few investigations have explored potential long-term offspring side effects. We previously reported increased pericardial fat and liver lipids in 10-year-old (human equivalent 40 years) male baboons exposed to 3 antenatal sGC courses. We hypothesized middle-aged sGC male offspring show obesity-related morphometric changes.

METHODS

Pregnant baboons received courses of 2 betamethasone injections (175 μg·kg-1·d-1 intramuscular) at 0.6, 0.64, and 0.68 gestation. At 10 to 12.5 years, we measured morphometrics and serum lipids in 5 sGC-exposed males and 10 age-matched controls. We determined whether morphometric parameters predicted amount of pericardial fat or lipids. Life-course serum lipids were measured in 25 males (7-23 years) providing normal regression formulas to compare sGC baboons' lipid biological and chronological age.

RESULTS

Birth weights were similar. When studied, sGC-exposed males showed a steeper weight increase from 8 to 12 years and had increased waist and hip circumferences, neck and triceps skinfolds, and total and low-density lipoprotein cholesterol. Triceps skinfold correlated with apical and midventricular pericardial fat thickness, hip and waist circumferences with insulin.

CONCLUSIONS

Triceps skinfold and waist and hip circumferences are useful biomarkers for identifying individuals at risk for obesity and metabolic dysregulation following fetal sGC exposure. Prenatal sGC exposure predisposes male offspring to internal adiposity, greater body size, and increased serum lipids. Results provide further evidence for developmental programming by fetal sGC exposure and call attention to potential emergence of adverse life-course effects.

Rapid Communication: Reduced maternal nutrition during early- to mid-gestation elevates newborn lamb plasma cortisol concentrations and eliminates the neonatal leptin surge

Human epidemiological and animal studies show that maternal nutrient reduction (MNR) and maternal overnutrition/obesity (MO) alter fetal growth and development, predisposing offspring (F1) to endocrine and appetite dysregulation. Compared to F1 of control-fed ewes, F1 of MO ewes display hypercortisolemia at birth and fail to exhibit the neonatal leptin surge implicated in lifelong appetite regulation. Here, we determined if MNR also elevates newborn lamb plasma cortisol and eliminates the neonatal leptin surge. Starting 30 d prior to conception, nulliparous control (CON, n = 6) ewes ate 100% NRC recommendations through parturition. Nutrient-reduced (NR, n = 6) ewes ate a CON diet through day 27 of gestation. From gestational days 28 to 78, NR ewes ate 50% of the CON diet before realimentation to 100% NRC recommendations. Jugular blood was collected daily from lambs from birth (day 0) through postnatal day 10, to determine plasma cortisol and leptin. Newborn NR plasma cortisol concentrations were increased (P < 0.0001) vs. CON and were similar to concentrations in MO lambs. Plasma leptin concentrations were similar between groups through postnatal day 7. The leptin surge, seen in CON lambs on postnatal days 8 to 10 was not present in NR lambs. These data show that, similar to MO lambs, early pregnancy MNR elevates newborn lamb plasma cortisol and eliminates the neonatal leptin surge. In the light of the similar elevation of neonatal cortisol in MNR and MO lambs, we conclude that cortisol plays a central role in regulating the neonatal lamb leptin surge.

Intrauterine growth restriction results in persistent vascular mismatch in adulthood

KEY POINTS

Intrauterine growth restriction (IUGR) increases offspring risk of chronic diseases later in life, including cardiovascular dysfunction. Our prior studies suggest biventricular cardiac dysfunction and vascular impairment in baboons who were IUGR at birth because of moderate maternal nutrient reduction. The current study reveals changes in artery sizes, distensibility, and blood flow pattern in young adult IUGR baboons, which may contribute to cardiac stress. The pattern of abnormality observed suggests that vascular redistribution seen with IUGR in fetal life may continue into adulthood.

ABSTRACT

Maternal nutrient reduction induces intrauterine growth restriction (IUGR), increasing risks of chronic diseases later in life, including cardiovascular dysfunction. Using ultrasound, we determined regional blood flow, blood vessel sizes, and distensibility in IUGR baboons (8 males, 8 females, 8.8 years, similar to 35 human years) and controls (12 males, 12 females, 9.5 years). The measured blood vessels were larger in size in the males compared to females before but not after normalization to body surface area. Smaller IUGR normalized blood vessel sizes were observed in the femoral and external iliac arteries but not the brachial or common carotid arteries and not correlated significantly with birth weight. Mild decrease in distensibility in the IUGR group was seen in the iliac but not the carotid arteries without between-sex differences. In IUGR baboons there was increased carotid arterial blood flow velocity during late systole and diastole. Overall, our findings support the conclusion that region specific vascular and haemodynamic changes occur with IUGR, which may contribute to the occurrence of later life cardiac dysfunction. The pattern of alteration observed suggests vascular redistribution efforts in response to challenges in the perinatal period may persist into adulthood. Further studies are needed to determine the life course progression of these changes.

Reproductive cycling in adult baboons (Papio species) that were intrauterine growth restricted at birth implies normal fertility but increased psychosocial stress

We investigated menstrual cycles in intrauterine growth restricted (IUGR, 7-10 years, n = 8) and age-matched control (n = 10) baboons. Cycle duration and plasma anti-Mullerian hormone were similar. IUGR spent more days per cycle swollen and had elevated early morning fasted serum cortisol, suggesting normal fertility in the presence of increased psychosocial stress.

Nonhuman Primates and Translational Research-Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the United States. Human epidemiological studies provide challenges for understanding mechanisms that regulate initiation and progression of CVD due to variation in lifestyle, diet, and other environmental factors. Studies describing metabolic and physiologic aspects of CVD, and those investigating genetic and epigenetic mechanisms influencing CVD initiation and progression, have been conducted in multiple Old World nonhuman primate (NHP) species. Major advantages of NHPs as models for understanding CVD are their genetic, metabolic, and physiologic similarities with humans, and the ability to control diet, environment, and breeding. These NHP species are also genetically and phenotypically heterogeneous, providing opportunities to study gene by environment interactions that are not feasible in inbred animal models. Each Old World NHP species included in this review brings unique strengths as models to better understand human CVD. All develop CVD without genetic manipulation providing multiple models to discover genetic variants that influence CVD risk. In addition, as each of these NHP species age, their age-related comorbidities such as dyslipidemia and diabetes are accelerated proportionally 3 to 4 times faster than in humans.In this review, we discuss current CVD-related research in NHPs focusing on selected aspects of CVD for which nonprimate model organism studies have left gaps in our understanding of human disease. We include studies on current knowledge of genetics, epigenetics, calorie restriction, maternal calorie restriction and offspring health, maternal obesity and offspring health, nonalcoholic steatohepatitis and steatosis, Chagas disease, microbiome, stem cells, and prevention of CVD.

Ageing changes in biventricular cardiac function in male and female baboons (Papio spp.)

KEY POINTS

Life course changes in cardiovascular function in a non-human primate have been comprehensively characterized. Age-related declines in normalized left ventricular stroke volume and cardiac output were found with corresponding decreases in biventricular ejection fractions and filling rates. There were age-related decreases in male and female baboon normalized left ventricular myocardial mass index, which declined at similar rates. Systolic functional declines in right ventricular function were observed with age, similar to the left ventricle. Sex differences were found in the rates and directions of right ventricular volume changes along with decreased end-systolic right ventricular sphericity. The results validate the baboon as an appropriate model for translational studies of cardiovascular functional decline with ageing.

ABSTRACT

Previous studies reported cardiac function declines with ageing. This study determined changes in biventricular cardiac function in a well-characterized baboon model. Cardiac magnetic resonance imaging measured key biventricular parameters in 47 baboons (22 female, age 4-23 years). ANCOVA assessed sex and age changes with P < 0.05 deemed significant. Stroke volume, cardiac output and other cardiac functional parameters were normalized to body surface area. There were similar, age-related rates of decrease in male (M) and female (F) normalized left ventricular (LV) myocardial mass index (M: -1.2 g m-2  year-1 , F: -0.9 g m-2  year-1 ). LV ejection fraction declined at -0.96% year-1 (r = -0.43, P = 0.002) and right ventricular (RV) ejection fraction decreased at -1.2% year-1 (r = -0.58, P < 0.001). Normalized LV stroke volume fell at -1.1 ml m-2  year-1 (r = -0.47, P = 0.001), normalized LV ejection rate at -3.8 ml s-1  m-2  year-1 (r = -0.43, P < 0.005) and normalized LV filling rate at -4.1 ml s-1  m-2  year-1 (r = -0.44, P < 0.005). Also, RV wall thickening fraction decreased with age (slope = -1% year-1 , P = 0.008). RV ejection rate decreased at -3.6 ml s-1  m-2  year-1 (P = 0.002) and the normalized average RV filling rate dropped at -3.7 ml s-1  m-2  year-1 (P < 0.0001). End-systolic RV sphericity index also dropped with age (r = -0.33, P = 0.02). Many observed changes parallel previously reported data in human and animal studies. These measured biventricular functional declines in hearts with ageing from the closest experimental primate species to man underscore the utility of the baboon model for investigating mechanisms related to heart ageing.

Sex-dimorphic acceleration of pericardial, subcutaneous, and plasma lipid increase in offspring of poorly nourished baboons

Developmental programming by reduced maternal nutrition alters function in multiple offspring physiological systems, including lipid metabolism. We have shown that intrauterine growth restriction (IUGR) leads to offspring cardiovascular dysfunction with an accelerated aging phenotype in our nonhuman primate, baboon model. We hypothesized age-advanced pericardial fat and blood lipid changes. In pregnancy and lactation, pregnant baboons ate ad lib (control) or 70% ad lib diet (IUGR). We studied baboon offspring pericardial lipid deposition with magnetic resonance imaging at 5-6 years (human equivalent 20-24 years), skinfold thickness, and serum lipid profile at 8-9 years (human equivalent 32-36 years), comparing values with a normative life-course baboon cohort, 4-23 years. Increased pericardial fat deposition occurred in IUGR males but not females. Female but not male total cholesterol, low-density lipoprotein, and subcutaneous fat were increased with a trend of triglycerides increase. When comparing IUGR changes to values in normal older baboons, the increase in male apical pericardial fat was equivalent to advancing age by 6 years and the increase in female low-density lipoprotein to an increase of 3 years. We conclude that reduced maternal diet accelerates offspring lipid changes in a sex-dimorphic manner. The interaction between programming and accelerated lipogenesis warrants further investigation.

Maternal nutrient restriction in baboon programs later-life cellular growth and respiration of cultured skin fibroblasts: a potential model for the study of aging-programming interactions

Compelling data exist for programming of chronic later-life diseases and longevity by perinatal developmental programming challenges. Understanding mechanisms by which life course health trajectory and longevity are set is fundamental to understanding aging. Appropriate approaches are needed to determine programming effects on cellular function. We have developed a baboon model in which control mothers eat ad libitum while a second group eat 70% of the global diet fed controls, leading to male and female offspring intrauterine growth restriction (IUGR). We have shown that IUGR suffer from acceleration of several age-related physiological declines. Here, we report on a skin-derived fibroblast model with potential relevance for mechanistic studies on how IUGR impacts aging. Fibroblasts were cultured from the skin biopsies taken from adult baboons from control and IUGR cohorts. IUGR-derived fibroblasts grew in culture less well than controls and those derived from male, but not female, IUGR baboons had a significant reduction in maximum respiration rate compared to control-derived fibroblasts. We also show that relative levels of several mitochondrial protein subunits, including NDUFB8 and cytochrome c oxidase subunit IV, were reduced in IUGR-derived fibroblasts even after serial passaging in culture. The lower levels of electron transport system components provide potential mechanisms for accelerated life course aging in the setting of programmed IUGR. This observation fits with the greater sensitivity of males compared with females to many, but not all, outcomes in response to programming challenges. These approaches will be powerful in the determination of programming-aging interactions.

Obstetric outcomes in pregnancy with pulmonary hypertension: A retrospective study of 78 cases at one center

OBJECTIVE

To identify the vary of obstetric outcomes by the severity of pulmonary hypertension (PH).

METHODS

A retrospective study involved pregnancies with PH in one certain academic institution. Total 78 pregnancies with PH were classified into three groups according the mean pulmonary arterial systolic pressure: mean pulmonary arterial systolic pressure 30-49 mm Hg (mild-PH group), mean pulmonary arterial systolic pressure 50-69 mm Hg (moderate-PH group) and mean pulmonary arterial systolic pressure ≥ 70 mm Hg (severe-PH group). The clinical features and obstetric outcomes were described and compared among three groups.

RESULTS

The incidence of PH was 0.23%, including 57 cases in mild-PH group, 10 cases in moderate-PH group and 11 cases in severe-PH group. Meanwhile, pregnancies with mild PH present NYHA class I/II (P < 0.001). General anesthesia (P < 0.001) and advanced intensive care (P = 0.011) were supplied for pregnancies with severe PH. There was no significant difference in rate of caesarean delivery. Furthermore, severity of PH increased the risk of neonatal death (P = 0.040).

CONCLUSION

The severity of PH seems to be a poor prognosis of neonatal death. Intensive care should be provided for pregnancies with severe PH.

Maternal undernutrition in late gestation increases IGF2 signalling molecules and collagen deposition in the right ventricle of the fetal sheep heart

KEY POINTS

This study investigates the impact of decreased fetal plasma glucose concentrations on the developing heart in late gestation, by subjecting pregnant ewes to a 50% global nutrient restriction. Late gestation undernutrition (LGUN) decreased fetal plasma glucose concentrations whilst maintaining a normoxemic blood gas status. LGUN increased the mRNA expression of IGF2 and IGF2R. Fetal plasma glucose concentrations, but not fetal blood pressure, were significantly correlated with IGF2 expression and the activation of CAMKII in the fetal right ventricle. LGUN increased interstitial collagen deposition and altered the protein abundance of phospho-PLB and phospho-troponin I, regulators of cardiac contractility and relaxation. This study shows that a decrease in fetal plasma glucose concentrations may play a role in the development of detrimental changes in the right ventricle in early life, highlighting CAMKII as a potential target for the development of intervention strategies.

ABSTRACT

Exposure of the fetus to a range of environmental stressors, including maternal undernutrition, is associated with an increased risk of death from cardiovascular disease in adult life. This study aimed to determine the effect of maternal nutrient restriction in late gestation on the molecular mechanisms that regulate cardiac growth and development of the fetal heart. Maternal undernutrition resulted in a decrease in fetal glucose concentrations across late gestation, whilst fetal arterial PO2 remained unchanged between the control and late gestation undernutrition (LGUN) groups. There was evidence of an up-regulation of IGF2/IGF2R signalling through the CAMKII pathway in the fetal right ventricle in the LGUN group, suggesting an increase in hypertrophic signalling. LGUN also resulted in an increased mRNA expression of COL1A, TIMP1 and TIMP3 in the right ventricle of the fetal heart. In addition, there was an inverse relationship between fetal glucose concentrations and COL1A expression. The presence of interstitial fibrosis in the heart of the LGUN group was confirmed through the quantification of picrosirius red-stained sections of the right ventricle. We have therefore shown that maternal undernutrition in late gestation may drive the onset of myocardial remodelling in the fetal right ventricle and thus has negative implications for right ventricle function and cardiac health in later life.

Nonhuman primate breath volatile organic compounds associate with developmental programming and cardio-metabolic status

Rodent and nonhuman primate studies indicate that developmental programming by reduced perinatal nutrition negatively impacts life course cardio-metabolic health. We have developed a baboon model in which we feed control mothers (CON) ad libitum while nutrient restricted mothers are fed 70% of ad libitum global feed in pregnancy and lactation. Offspring of nutrient restricted mothers are intrauterine growth restricted (IUGR) at term. By 3.5 years IUGR baboons showed signs of insulin resistance, indicating a pre-diabetic phenotype, in contrast to healthy CON offspring. We hypothesized that a novel breath analysis approach would provide markers of the altered cardio-metabolic state in a non-invasive manner. Here we assess whether exhaled breath volatile organic compounds (VOCs) collected from this unique cohort of juvenile baboons with documented cardio-metabolic dysfunction resulting from in utero programming can be detected from their breath signatures. Breath was collected from male and female CON and IUGR baboons at 4.8 ± 0.2 years (human equivalent ~13 years). Breath VOCs were quantified using a two-dimensional gas chromatography mass spectrometer. Two-way ANOVA, on 76 biologically relevant VOCs identified 27 VOCs (p < 0.05) with altered abundances between groups (sex, birthweight, and sex x birthweight). The 27 VOCs included 2-pentanone, 2-octanone, 2,2,7,7-tetramethyloctane and 3-methyl-1-heptene, which have not previously been associated with cardio-metabolic disease. Unsupervised principal component analysis of these VOCs could discriminate the four clusters defining males, females, CON and IUGR. This study, which is the first to assess quantifiable breath signatures associated with cardio-metabolic programing for any model of IUGR, demonstrates the translational value of this unique model to identify metabolites of programmed cardio-metabolic dysfunction in breath signatures. Future studies are required to validate the translatability of these findings to humans.

Maternal activity, anxiety, and protectiveness during moderate nutrient restriction in captive baboons (Papio sp.)

BACKGROUND

We hypothesized that maternal nutrient restriction (NR) would increase activity and behavioral indicators of anxiety (self-directed behaviors, SDBs) in captive baboons (Papio sp.) and result in more protective maternal styles.

METHODS

Our study included 19 adult female baboons. Seven females ate ad libitum (control group), and eight females ate 30% less (NR group) and were observed through pregnancy and lactation.

RESULTS

Control females engage in higher rates of SDB than NR females overall (P ≤ .018) and during the prenatal period (P ≤ .001) and engage in more aggressive behavior (P ≤ .033). Control females retrieved infants more than NR females during weeks 5-8 postpartum (P ≤ .019).

CONCLUSIONS

Lower SDB rates among prenatal NR females reduce energy expenditure and increase available resources for fetal development when nutritionally restricted. Higher infant retrieval rates by controls may indicate more infant independence rather than maternal style differences.

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.