Maternal malnourishment induced upregulation of fetuin-B blunts nephrogenesis in the low birth weight neonate.

Maternal undernutrition during pregnancy (MUN) often leads to low birth weight (LBW) neonates that have a reduced total nephron endowment, leaving these neonates susceptible to kidney disease throughout their lives. For reasons unknown, these LBW neonates have impaired kidney development due to a severe reduction in renal SIX2+ stem cells during nephrogenesis. Using a mouse model of MUN, we investigated SIX2+ stem cell reduction in the LBW neonate. Significant upregulation of the protein fetuin-B (measured by PCR and immunoblotting) in the MUN mother's placenta, organs and circulation yielded a 3-fold increase of this protein in the embryonic kidney. Recombinant fetuin-B, administered to healthy pregnant mothers at the concentration equivalent to that in the MUN mother, crossed the placenta and reduced both SIX2+ stem cells by 50% and nephron formation by 66% in embryonic kidneys (measured by immunofluorescence and the physical dissector/fractionator stereological method). Administration of fetuin-B to kidney explants yielded similar reductions in renal SIX2+ stem cells and nephron formation. Fetuin-B treatment of isolated embryonic renal SIX2+ stem cell primary cultures 1) increased NF-kB activity and apoptosis, 2) reduced cell proliferation due to upregulated p21 nuclear activity and subsequent cell cycle arrest, and 3) enhanced generation of reactive oxygen species (measured by fluorescence microscopy). In conclusion, MUN increases fetuin-B in the developing embryonic kidney. The increase in fetuin-B blunts nephrogenesis by reducing SIX2+ stem cells by promoting their apoptosis (via NF-kB upregulation), blunting their proliferative renewal (via p21 upregulation) and enhancing oxidative stress.

Fetal iron deficiency and genotype influence emotionality in infant rhesus monkeys.

BACKGROUND: Anemia during the third trimester of fetal development affects one-third of the pregnancies in the United States and has been associated with postnatal behavioral outcomes. This study examines how fetal iron deficiency (ID) interacts with the fetal monoamine oxidase A (MAOA) genotype. MAOA metabolizes monoamine neurotransmitters. MAOA polymorphisms in humans affect temperament and modify the influence of early adverse environments on later behavior. OBJECTIVE: The aim of the study was to advance translation of developmental ID research in animal models by taking into account genetic factors that influence outcomes in human populations. METHODS: Male infant rhesus monkeys 3-4 mo old born to mothers fed an ID (10 ppm iron) diet were compared with controls (100 ppm iron). Infant monkeys with high- or low-transcription rate MAOA polymorphisms were equally distributed between diet groups. Behavioral responses to a series of structured experiences were recorded during a 25-h separation of the infants from their mothers. RESULTS: Infant monkeys with low-transcription MAOA polymorphisms more clearly demonstrated the following ID effects suggested in earlier studies: a 4% smaller head circumference, a 39% lower cortisol response to social separation, a 129% longer engagement with novel visual stimuli, and 33% lesser withdrawal in response to a human intruder. The high MAOA genotype ID monkeys demonstrated other ID effects: less withdrawal and emotionality after social separation and lower "fearful" ratings. CONCLUSION: MAOA × ID interactions support the role of monoamine neurotransmitters in prenatal ID effects in rhesus monkeys and the potential involvement of common human polymorphisms in determining the pattern of neurobehavioral effects produced by inadequate prenatal nutrition.

Thrifty metabolic programming in rats is induced by both maternal undernutrition and postnatal leptin treatment, but masked in the presence of both: implications for models of developmental programming.

BACKGROUND: Maternal undernutrition leads to an increased risk of metabolic disorders in offspring including obesity and insulin resistance, thought to be due to a programmed thrifty phenotype which is inappropriate for a subsequent richer nutritional environment. In a rat model, both male and female offspring of undernourished mothers are programmed to become obese, however postnatal leptin treatment gives discordant results between males and females. Leptin treatment is able to rescue the adverse programming effects in the female offspring of undernourished mothers, but not in their male offspring. Additionally, in these rats, postnatal leptin treatment of offspring from normally-nourished mothers programmes their male offspring to develop obesity in later life, while there is no comparable effect in their female offspring. RESULTS: We show by microarray analysis of the female liver transcriptome that both maternal undernutrition and postnatal leptin treatment independently induce a similar thrifty transcriptional programme affecting carbohydrate metabolism, amino acid metabolism and oxidative stress genes. Paradoxically, however, the combination of both stimuli restores a more normal transcriptional environment. This demonstrates that "leptin reversal" is a global phenomenon affecting all genes involved in fetal programming by maternal undernourishment and leptin treatment. The thrifty transcriptional programme was associated with pro-inflammatory markers and downregulation of adaptive immune mediators, particularly MHC class I genes, suggesting a deficit in antigen presentation in these offspring. CONCLUSIONS: We propose a revised model of developmental programming reconciling the male and female observations, in which there are two competing programmes which collectively drive liver transcription. The first element is a thrifty metabolic phenotype induced by early life growth restriction independently of leptin levels. The second is a homeostatic set point calibrated in response to postnatal leptin surge, which is able to over-ride the metabolic programme. This "calibration model" for the postnatal leptin surge, if applicable in humans, may have implications for understanding responses to catch-up growth in infants. Additionally, the identification of an antigen presentation deficit associated with metabolic thriftiness may relate to a previously observed correlation between birth season (a proxy for gestational undernutrition) and infectious disease mortality in rural African communities.

Programming of osteoporosis and impact on osteoporosis risk.

Osteoporosis is a skeletal disorder characterized by reduced bone quantity and quality and an increased susceptibility to fracture, and seems to be one of many chronic conditions that might be influenced by events early in life. Specifically, there is growing evidence of an interaction between the genome and the environment in the expression of the disease.

Epigenetic mechanisms in fetal origins of health and disease.

Early life environment predicts future health. The initial precedents and research focus on this concept arose out of historical events. However, this concept continues to be relevant as evidenced by the recent Chinese famine and the evidence of racial disparities in the United States. The latter allows us to introduce the "life course model" and "weathering" as relevant epigenetic phenomena. We then review the molecular components of environmental epigenetics. We subsequently present glucocorticoid receptor biology as a paradigm that involves all of the components. Finally, we suggest that environmental epigenetics are a key component of the future of personalized medicine.

Thioredoxin binding protein-2 inhibits excessive fetal hypoglycemia during maternal starvation by suppressing insulin secretion in mice.

Glucose is a major fuel for fetal development. Fetal blood glucose level is mainly dependent on maternal blood glucose concentration, though it is also regulated by fetal insulin level. Thioredoxin binding protein-2 (TBP-2), which is identical to vitamin D3 up-regulated protein (VDUP1) and thioredoxin interacting protein (Txnip), was recently reported to be a key transcriptional factor controlling glucose metabolism. Here, we elucidated the functions of TBP-2 in maintaining blood glucose homeostasis during the fetal period. TBP-2(+/-) female mice were mated with TBP-2(+/-) male mice; beginning 16.5-d post coitum, pregnant mice were fed or fasted for 24 h. Under conditions of maternal starvation, the blood glucose levels of TBP-2(-/-) fetuses were significantly lower than those of TBP-2(+/+) fetuses, corresponding to the elevated plasma insulin levels of TBP-2(-/-) fetuses compared with those of TBP-2(+/+) fetuses. There was no difference between TBP-2(+/+) and TBP-2(-/-) fetuses in terms of their pancreatic beta-cell masses or the expression of placental glucose transporters under conditions of either maternal feeding or fasting. Thus, during maternal fasting, fetal TBP-2 suppresses excessive insulin secretion to maintain the fetus's glucose levels, implying that TBP-2 is a critical molecule in mediating fetal glucose homeostasis depending on nutrient availability.

Impact of diets and nutrients/drugs on early epigenetic programming.

Specific, often unbalanced diets are used to circumvent the metabolic defects of patients with monogenic inborn errors of metabolism. Human epidemiological studies and appropriately designed dietary interventions in animal models have provided considerable evidence to suggest that nutritional imbalance and metabolic disturbances, during critical time windows of developmental programming, may have a persistent effect on the health of the child and later in adulthood. Thus patients with monogenic inborn errors of metabolism may also suffer additional types of alterations due to the lack or excess of key nutrients. Interactions of nutrients with the epigenetic machinery lead to epigenetic changes associated with chromatin remodelling and regulation of gene expression that underlie the developmental programming of pathological consequences in adulthood. Today, with the explosion of new technologies, we can explore on a large scale the effects of nutrients on the level of expression of thousands of expressed genes (nutritional genomics and epigenomics), the corresponding protein products and their posttranslationally modified derivatives (proteomics), and the host of metabolites (metabolomics) generated from endogenous metabolic processes or exogenous dietary nutrients and can establish the relationship between these biological entities and diet, health or disease. The combination of these various lines of research on epigenetic programming processes should highlight new strategies for the prevention and treatment of inborn errors of metabolism.

Epigenetic changes caused by intrauterine malnutrition as potential disease mediator and early prevention in developmental stages.

Presently, the incidences of noncommunicable diseases (NCD) have been increasing in both low- and middle-income countries worldwidely. Effective long-term and multigeneration interventions to decrease the risk of NCD should be developed and introduced. The environment in utero alters phenotypes mainly through epigenetic mechanisms. The epigenetic changes induced in an unfavorable developmental environment have lifelong effects on cardiovascular and metabolic functions, susceptibility to cardiovascular disease, obesity, and other NCD. Although compared with animals, epigenetic analysis of human specimens is restricted except for peripheral blood, placental, or umbilical specimens, recently, important human studies have been reported concerning the epigenetic analysis of Line 1 gene from the umbilical blood, umbilical RXRα, or the peripheral nuclear cell IGF-2. The birth weight is an indirect marker of in-the-womb nutritional status. The incidence of low-birth-weight infants, weighing less than 2,500 g, has been increasing in Japan. Presently, it is higher than that in the latter half of the 20 s of the Showa era, and is the highest among the OECD countries. This trend suggests that in Japan the intrauterine nutritional status has been deteriorating. We have to change this trend and put much attention on the prepregnancy and pregnancy nutrition for the present and future generations.

In utero effects. In utero undernourishment perturbs the adult sperm methylome and intergenerational metabolism.

Adverse prenatal environments can promote metabolic disease in offspring and subsequent generations. Animal models and epidemiological data implicate epigenetic inheritance, but the mechanisms remain unknown. In an intergenerational developmental programming model affecting F2 mouse metabolism, we demonstrate that the in utero nutritional environment of F1 embryos alters the germline DNA methylome of F1 adult males in a locus-specific manner. Differentially methylated regions are hypomethylated and enriched in nucleosome-retaining regions. A substantial fraction is resistant to early embryo methylation reprogramming, which may have an impact on F2 development. Differential methylation is not maintained in F2 tissues, yet locus-specific expression is perturbed. Thus, in utero nutritional exposures during critical windows of germ cell development can impact the male germline methylome, associated with metabolic disease in offspring.

DNA methylation signatures link prenatal famine exposure to growth and metabolism.

Periconceptional diet may persistently influence DNA methylation levels with phenotypic consequences. However, a comprehensive assessment of the characteristics of prenatal malnutrition-associated differentially methylated regions (P-DMRs) is lacking in humans. Here we report on a genome-scale analysis of differential DNA methylation in whole blood after periconceptional exposure to famine during the Dutch Hunger Winter. We show that P-DMRs preferentially occur at regulatory regions, are characterized by intermediate levels of DNA methylation and map to genes enriched for differential expression during early development. Validation and further exploratory analysis of six P-DMRs highlight the critical role of gestational timing. Interestingly, differential methylation of the P-DMRs extends along pathways related to growth and metabolism. P-DMRs located in INSR and CPT1A have enhancer activity in vitro and differential methylation is associated with birth weight and serum LDL cholesterol. Epigenetic modulation of pathways by prenatal malnutrition may promote an adverse metabolic phenotype in later life.

Azuki bean polyphenols intake during lactation upregulate AMPK in male rat offspring exposed to fetal malnutrition.

OBJECTIVE: Fetal malnutrition is an early-life inducer of dyslipidemia and glucose intolerance. The aim of this study was to examine whether maternal azuki bean (Vigna angularis) polyphenol (AP) intake during lactation affects the adenosine monophosphate-activated protein kinase (AMPK) pathway and lipid metabolism in offspring exposed to fetal malnutrition. METHODS: Pregnant Wistar rats were divided into three groups: a control diet offered during gestation and lactation (CC), a low-protein diet during gestation and a control diet during lactation (LPC); and a low-protein diet during gestation and a 1.0% AP-containing control diet during lactation (LPAP). Male pups were randomly selected for the study; half the pups were sacrificed at 3 wk of age and the other half were fed a standard diet and sacrificed at 23 wk. Hepatic triacylglycerol levels, phosphorylation levels of AMPK and acetyl-coenzyme A carboxylase (ACC), and mRNA levels of sterol regulatory element-binding protein-1c (SREBP-1c) were evaluated. RESULTS: Significant decreases in body weights and hepatic triacylglycerol levels were found in the LPAP compared with the LPC group. Plasma adiponectin levels in the LPAP group were higher than those in the LPC group. AMPK phosphorylation was upregulated in the livers and skeletal muscles in young and adult LPAP compared with LPC rats. ACC phosphorylation was upregulated in skeletal muscles of LPAP rats. SREBP-1c mRNA expression was decreased in the livers of LPAP rats. CONCLUSION: Our results suggest that maternal AP intake during lactation upregulates AMPK phosphorylation not only in young but also in adult offspring exposed to fetal malnutrition and may lead to decreased hepatic lipid accumulation by ACC phosphorylation and downregulation of SREBP-1c expression.

Environmental and genetical aspects of the link between pregnancy, birth size, and type 2 diabetes.

Exposure of the fetus to the intrauterine milieu can have profound effects on the health of the offspring in adulthood. These observations are highly reproducible in many populations worldwide although the mechanisms behind them remain elusive. The 'thrifty phenotype' hypothesis proposes that poor fetal nutrition leads to programming of metabolism and an adult phenotype that is adapted to poor but not plentiful nutrition. Results of a series of studies demonstrate the powerful influence of the mother's metabolic state on whether the emerging adult develops obesity and hyperinsulinemia. Importantly, these attributes can be passed on to the next generation non-genetically and can be reversed and prevented. Such hypothesis has been expanded on by the "Developmental Origins of Health and Disease" (DOHaD) hypothesis which describes the origin of adult disease in terms of fetal developmental 'plasticity' or the ability of the fetus to respond to poor in-utero conditions. A wealth of epidemiological evidence has provided a convincing link between a sub-optimal gestational environment and an increased propensity to develop adult onset metabolic disease. In this paper the factors that participate in the programming of the fetus and infants that lead to endocrine dysfunction in postnatal life are reviewed.

Genetic selection of embryos that later develop the metabolic syndrome.

THE BARKER HYPOTHESIS: Is an excellent explanation of the process where human and animal foetuses exposed to malnutrition, either by maternal malnutrition or placental insufficiency, are metabolically programmed, with selective stunting of cell differentiation and organ growth. With the postnatal excess of nutrition observed in developed countries, this irreversible programming causes metabolic syndrome, including obesity, type 2 diabetes, and hypertension. Metabolic programming involves epigenetic changes including imprinting which might be transmitted through more than one generation rather than being completely re-set or erased during reproduction. The Barker hypothesis was supported by epidemiological data that recognised no excess fetal or postnatal mortality when pregnant women were starved during the Dutch famine in World War II. This argued against the "thrifty genotype" theory introduced in 1962, which proposed that starvation selected against members of the population with less "thrifty" genes, but the survivors who had "thrifty" genes developed metabolic syndrome if they were subsequently over-nourished. EMBRYONIC/FETAL SELECTION: Embryos or early foetuses could be selected very early in pregnancy on the basis of their genotype, by maternal malnutrition, hypertension, obesity or other causes of placental insufficiency. The genotype that allows embryos, or cells within them, to survive a less hospitable environment in the decidua after implantation might contribute to the later development of metabolic syndrome. This article hypothesises that an adverse intrauterine environment, caused by maternal malnutrition or placental insufficiency, kills a proportion of embryos and selects a surviving population of early embryos whose growth in utero is retarded by their genotype, their environment or a combination of both. The metabolic syndrome follows if the offspring is over-nourished later in life. The embryonic selection hypothesis presented here could be tested by using single nucleotide polymorphism (SNP) microarrays to study adults who had a history of intrauterine growth retardation (IUGR) and subsequent metabolic syndrome. Their SNP array could be compared with their parents and unaffected unrelated or related controls. If there were no selection based on a "thrifty genotype", all parental sequences would be expected to appear in their surviving children, whether or not they had IUGR or developed metabolic syndrome. SNP sequences present in parents or controls but missing from adult offspring with metabolic syndrome who had IUGR, could be associated with or linked to genes that influence susceptibility to metabolic syndrome. This hypothesis proposes that missing genotypes would be lost if the embryos that inherited them died very early in pregnancy.

Influence of prenatal iron deficiency and MAOA genotype on response to social challenge in rhesus monkey infants.

Social and emotional behaviors are known to be sensitive to both developmental iron deficiency (ID) and monoamine oxidase A (MAOA) gene polymorphisms. In this study, male rhesus monkey infants deprived of dietary iron in utero were compared with iron sufficient (IS) controls (n = 10/group). Half of each group had low MAOA activity genotypes and half had high MAOA activity genotypes. A series of social response tests were conducted at 3-14 months of age. MAOA genotype influenced attention to a video of aggressive behavior, emotional expression (fear, grimace and sniff) in the social intruder test, social actions (displacement, grooming) in the social dyad test, and aggressive responses to a threatening picture. Interactions between MAOA and prenatal ID were seen in response to the aggressive video, in temperament ratings, in affiliative behavior in the social dyad test, in cortisol response in the social buffering test and in response to a social intruder and to pictures with social and nonsocial themes. In general, the effects of ID were dependent on MAOA genotype in terms of both direction and size of the effect. Nutrition/genotype interactions may shed new light on behavioral consequences of nutritional deprivation during brain development.

Seeking gene candidates responsible for developmental origins of health and disease.

Human epidemiological evidence has led scientists to theorize that undernutrition during gestation is an important early origin of adult diseases. Animal models have successfully demonstrated that maternal diet could contribute to some adult diseases. Undernutrition is perceived harmful in pregnant women, whereas calorie restriction is a strategy proven to extend healthy and maximum lifespan in adult. This diagrammatically opposite effect of nutritional condition might provide us with hints to search for genes underlying health conditions. Here, we have initiated a study examining the effect of undernutrition on maternal and fetal livers, utilizing high-throughput DNA microarray analysis for screening genome-wide changes in their transcriptomes. Briefly, pregnant mice were exposed to food deprivation (FD) on gestation day (GD) 17, and cesarean section was performed on GD18. Control mice were supplied with chow ad libitum until sacrifice. Total RNA extracted from mother and fetal livers for each control and treatment (FD) was analyzed with an Agilent mouse whole genome DNA chip. A total of 3058 and 3126 up- (>1.5-fold) and down- (<0.75-fold) regulated genes, and 1475 and 1225 up- (>1.5-fold) and down- (<0.75-fold) regulated genes showed differential expression at the mRNA level, in the maternal and fetal livers, respectively. Interestingly, 103 genes up-regulated in the mother were down-regulated in the fetus, whereas 108 down-regulated maternal genes were up-regulated in the fetus; these 211 genes are potential candidates related to longevity or health. The role of some of these genes, in context of the proposed mechanisms for developmental origins of health and disease is discussed.

Epigenetic changes in the hypothalamic proopiomelanocortin and glucocorticoid receptor genes in the ovine fetus after periconceptional undernutrition.

Maternal food restriction is associated with the development of obesity in offspring. This study examined how maternal undernutrition in sheep affects the fetal hypothalamic glucocorticoid receptor (GR) and the appetite-regulating neuropeptides, proopiomelanocortin (POMC) and neuropeptide Y, which it regulates. In fetuses from ewes undernourished from -60 to +30 d around conception, there was increased histone H3K9 acetylation (1.63-fold) and marked hypomethylation (62% decrease) of the POMC gene promoter but no change in POMC expression. In the same group, acetylation of histone H3K9 associated with the hypothalamic GR gene was increased 1.60-fold and the GR promoter region was hypomethylated (53% decrease). In addition, there was a 4.7-fold increase in hypothalamic GR expression but no change in methylation of GR gene expression in the anterior pituitary or hippocampus. Interestingly, hypomethylation of both POMC and GR promoter markers in fetal hypothalami was also identified after maternal undernutrition from -60 to 0 d and -2 to +30 d. In comparison, the Oct4 gene, was hypermethylated in both control and underfed groups. Periconceptional undernutrition is therefore associated with marked epigenetic changes in hypothalamic genes. Increase in GR expression in the undernourished group may contribute to fetal programming of a predisposition to obesity, via altered GR regulation of POMC and neuropeptide Y. These epigenetic changes in GR and POMC in the hypothalamus may also predispose the offspring to altered regulation of food intake, energy expenditure, and glucose homeostasis later in life.

Animal models of epigenetic inheritance.

Although genomic DNA is the template of our heredity, it is the coordination and regulation of its expression that results in the wide complexity and diversity seen among organisms. In recent years, an emerging body of evidence has focused on the role of epigenetics as one mechanism by which gene expression can be maintained and modulated throughout the lifetime of an individual. Epigenetics refers to heritable alterations in gene expression that are not mediated by changes in primary DNA sequence and includes mitotic and/or meiotic events. In essence, epigenetic modulation results in functional adaptations of the genomic response to the environment and is believed to play a fundamental role in early developmental plasticity. This article focuses on several animal models that have been developed over the past decade to study epigenetic inheritance, many of which have arisen from the developmental origins of adult health and disease fields.

Developmental origins of health and disease: brief history of the approach and current focus on epigenetic mechanisms.

"Barker's hypothesis" emerged almost 25 years ago from epidemiological studies of birth and death records that revealed a high geographic correlation between rates of infant mortality and certain classes of later adult deaths as well as an association between birthweight and rates of adult death from ischemic heart disease. These observations led to a theory that undernutrition during gestation was an important early origin of adult cardiac and metabolic disorders due to fetal programming that permanently shaped the body's structure, function, and metabolism and contributed to adult disease. This theory stimulated interest in the fetal origins of adult disorders, which expanded and coalesced approximately 5 years ago with the formation of an international society for developmental origins of health and disease (DOHaD). Here we review a few examples of the many emergent themes of the DOHaD approach, including theoretical advances related to predictive adaptive responses of the fetus to a broad range of environmental cues, empirical observations of effects of overnutrition and stress during pregnancy on outcomes in childhood and adulthood, and potential epigenetic mechanisms that may underlie these observations and theory. Next, we discuss the relevance of the DOHaD approach to reproductive medicine. Finally, we consider the next steps that might be taken to apply, evaluate, and extend the DOHaD approach.

Environmental influences on epigenetic profiles.

Studies of environmental challenges, such as hazardous air pollutants, nonmutagenic toxins, diet choice, and maternal behavioral patterns, reveal changes in gene expression patterns, DNA methylation, and histone modifications that are in causal association with exogenous exposures. In this article we summarize some of the recent advances in the field of environmental epigenetics and highlight seminal studies that implicate in utero exposures as causative agents in altering not only the epigenome of the exposed gestation, but that of subsequent generations. Current studies of the effects of maternal behavior, exposure to environmental toxins, and exposure to maternal diet and an altered gestational milieu are summarized.