Uteroplacental insufficiency induces site-specific changes in histone H3 covalent modifications and affects DNA-histone H3 positioning in day 0 IUGR rat liver

Epigenetics and the role of nutraceuticals in health and disease

In the post-genomic era, the data provided by complete genome sequencing could not answer several fundamental questions about the causes of many noninfectious diseases, diagnostic biomarkers, and novel therapeutic approaches. The rapidly expanding understanding of epigenetic mechanisms, as well as widespread acceptance of their hypothesized role in disease induction, facilitated the development of a number of novel diagnostic markers and therapeutic concepts. Epigenetic aberrations are reversible in nature, which enables the treatment of serious incurable diseases. Therefore, the interest in epigenetic modulatory effects has increased over the last decade, so about 60,000 publications discussing the expression of epigenetics could be detected in the PubMed database. Out of these, 58,442 were published alone in the last 10 years, including 17,672 reviews (69 historical articles), 314 clinical trials, 202 case reports, 197 meta-analyses, 156 letters to the editor, 108 randomized controlled trials, 87 observation studies, 40 book chapters, 22 published lectures, and 2 clinical trial protocols. The remaining publications are either miscellaneous or a mixture of the previously mentioned items. According to the species and gender, the publications included 44,589 human studies (17,106 females, 14,509 males, and the gender is not mentioned in the remaining papers) and 30,253 animal studies. In the present work, the role of epigenetic modulations in health and disease and the influencing factors in epigenetics are discussed.

Effect of maternal curcumin supplementation on intestinal damage and the gut microbiota in male mice offspring with intra-uterine growth retardation

PURPOSE

The present study investigated whether maternal curcumin supplementation might protect against intra-uterine growth retardation (IUGR) induced intestinal damage and modulate gut microbiota in male mice offspring.

METHODS

In total, 36 C57BL/6 mice (24 females and 12 males, 6-8 weeks old) were randomly divided into three groups based on the diet before and throughout pregnancy and lactation: (1) normal protein (19%), (2) low protein (8%), and (3) low protein (8%) + 600 mg kg-1 curcumin. Offspring were administered a control diet until postnatal day 35.

RESULTS

Maternal curcumin supplementation could normalize the maternal protein deficiency-induced decrease in jejunal SOD activity (NP = 200.40 ± 10.58 U/mg protein; LP = 153.30 ± 5.51 U/mg protein; LPC = 185.40 ± 9.52 U/mg protein; P < 0.05) and T-AOC content (NP = 138.90 ± 17.51 U/mg protein; LP = 84.53 ± 5.42 U/mg protein; LPC = 99.73 ± 12.88 U/mg protein; P < 0.05) in the mice offspring. Maternal curcumin supplementation increased the maternal low protein diet-induced decline in the ratio of villus height-to-crypt depth (NP = 2.23 ± 0.19; LP = 1.90 ± 0.06; LPC = 2.56 ± 0.20; P < 0.05), the number of goblet cells (NP = 12.72 ± 1.16; LP = 7.04 ± 0.53; LPC = 13.10 ± 1.17; P < 0.05), and the ratio of PCNA-positive cells (NP = 13.59 ± 1.13%; LP = 2.42 ± 0.74%; LPC = 6.90 ± 0.96%; P < 0.05). It also reversed the maternal protein deficiency-induced increase of the body weight (NP = 13.00 ± 0.48 g; LP = 16.49 ± 0.75 g; LPC = 10.65 ± 1.12 g; P < 0.05), the serum glucose levels (NP = 5.32 ± 0.28 mmol/L; LP = 6.82 ± 0.33 mmol/L; LPC = 4.69 ± 0.35 mmol/L; P < 0.05), and the jejunal apoptotic index (NP = 6.50 ± 1.58%; LP = 10.65 ± 0.75%; LPC = 5.24 ± 0.71%; P < 0.05). Additionally, maternal curcumin supplementation enhanced the gene expression level of Nrf2 (NP = 1.00 ± 0.12; LP = 0.73 ± 0.10; LPC = 1.34 ± 0.12; P < 0.05), Sod2 (NP = 1.00 ± 0.04; LP = 0.85 ± 0.04; LPC = 1.04 ± 0.04; P < 0.05) and Ocln (NP = 1.00 ± 0.09; LP = 0.94 ± 0.10; LPC = 1.47 ± 0.09; P < 0.05) in the jejunum. Furthermore, maternal curcumin supplementation normalized the relative abundance of Lactobacillus (NP = 31.56 ± 6.19%; LP = 7.60 ± 2.33%; LPC = 17.79 ± 2.41%; P < 0.05) and Desulfovibrio (NP = 3.63 ± 0.93%; LP = 20.73 ± 3.96%; LPC = 13.96 ± 4.23%; P < 0.05), and the ratio of Firmicutes/Bacteroidota (NP = 2.84 ± 0.64; LP = 1.21 ± 0.30; LPC = 1.79 ± 0.15; P < 0.05). Moreover, Lactobacillus was positively correlated with the SOD activity, and it was negatively correlated with Il - 1β expression (P < 0.05). Desulfovibrio was negatively correlated with the SOD activity and the jejunal expression of Sod1, Bcl - 2, Card11, and Zo - 1 (P < 0.05).

CONCLUSIONS

Maternal curcumin supplementation could improve intestinal integrity, oxidative status, and gut microbiota in male mice offspring with IUGR.

Nutritional Epigenetics: How Metabolism Epigenetically Controls Cellular Physiology, Gene Expression and Disease

The regulation of gene expression is a dynamic process that is influenced by both internal and external factors. Alteration in the epigenetic profile is a key mechanism in the regulation process. Epigenetic regulators, such as enzymes and proteins involved in posttranslational modification (PTM), use different cofactors and substrates derived from dietary sources. For example, glucose metabolism provides acetyl CoA, S-adenosylmethionine (SAM), α- ketoglutarate, uridine diphosphate (UDP)-glucose, adenosine triphosphate (ATP), nicotinamide adenine dinucleotide (NAD⁺), and fatty acid desaturase (FAD), which are utilized by chromatin-modifying enzymes in many intermediary metabolic pathways. Any alteration in the metabolic status of the cell results in the alteration of these metabolites, which causes dysregulation in the activity of chromatin regulators, resulting in the alteration of the epigenetic profile. Such long-term or repeated alteration of epigenetic profile can lead to several diseases, like cancer, insulin resistance and diabetes, cognitive impairment, neurodegenerative disease, and metabolic syndromes. Here we discuss the functions of key nutrients that contribute to epigenetic regulation and their role in pathophysiological conditions.

Novel type of references for weight aligned for onset of puberty - using the QEPS growth model

BACKGROUND

Growth references are traditionally constructed relative to chronological age, despite inter-individual variations in pubertal timing. A new type of height reference was recently developed allowing growth to be aligned based on onset of pubertal height growth. We here aim to develop a corresponding reference for pubertal weight.

METHODS

To model QEPS-weight, 3595 subjects (1779 girls) from GrowUp1974Gothenburg and GrowUp1990Gothenburg were used. The QEPS-height-model was transformed to a corresponding QEPS-weight-model; thereafter, QEPS-weight was modified by an individual, constitutional weight-height-factor. Longitudinal weight and length/height measurements from 1418 individuals (698 girls) from GrowUp1990Gothenburg were then used to create weight references aligned for height at pubertal onset (the age at 5% of P-function growth, AgeP5). GrowUp1974Gothenburg subgroups based on pubertal timing, stature at pubertal onset, and childhood body composition were assessed using the references.

RESULTS

References (median, SDS) for total weight (QEPS-functions), weight specific to puberty (P-function), and weight gain in the absence of specific pubertal growth (basic weight, QES-functions), allowing alignment of individual growth based on age at pubertal onset. For both sexes, basic weight was greater than average for late maturing, tall and high-BMI subgroups. The P-function-related weight was greater than average in short and lower than average in tall children, in those with high BMI, and in girls but not boys with low BMI.

CONCLUSIONS

New pubertal weight references allow individual variations in pubertal timing to be taken into consideration when evaluating growth. When used together with the comparable pubertal height reference, this will improve growth monitoring in clinical practice for identifying abnormal growth and serve as a valuable research tool providing insight into human growth.

Hippocampal epigenetic and insulin-like growth factor alterations in noninvasive versus invasive mechanical ventilation in preterm lambs

BACKGROUND

The brain of chronically ventilated preterm human infants is vulnerable to collateral damage during invasive mechanical ventilation (IMV). Damage is manifest, in part, by learning and memory impairments, which are hippocampal functions. A molecular regulator of hippocampal development is insulin-like growth factor 1 (IGF1). A gentler ventilation strategy is noninvasive respiratory support (NRS). We tested the hypotheses that NRS leads to greater levels of IGF1 messenger RNA (mRNA) variants and distinct epigenetic profile along the IGF1 gene locus in the hippocampus compared to IMV.

METHODS

Preterm lambs were managed by NRS or IMV for 3 or 21 days. Isolated hippocampi were analyzed for IGF1 mRNA levels and splice variants for promoter 1 (P1), P2, and IGF1A and 1B, DNA methylation in P1 region, and histone covalent modifications along the gene locus.

RESULTS

NRS had significantly greater levels of IGF1 P1 (predominant transcript), and 1A and 1B mRNA variants compared to IMV at 3 or 21 days. NRS also led to more DNA methylation and greater occupancy of activating mark H3K4 trimethylation (H3K4me3), repressive mark H3K27me3, and elongation mark H3K36me3 compared to IMV.

CONCLUSIONS

NRS leads to distinct IGF1 mRNA variant levels and epigenetic profile in the hippocampus compared to IMV.

IMPACT

Our study shows that 3 or 21 days of NRS of preterm lambs leads to distinct IGF1 mRNA variant levels and epigenetic profile in the hippocampus compared to IMV. Preterm infant studies suggest that NRS leads to better neurodevelopmental outcomes later in life versus IMV. Also, duration of IMV is directly related to hippocampal damage; however, molecular players remain unknown. NRS, as a gentler mode of respiratory management of preterm neonates, may reduce damage to the immature hippocampus through an epigenetic mechanism.

Short- and Long-Term Implications of Small for Gestational Age

Fetal growth restriction (FGR) describes a fetus' inability to attain adequate weight gain based on genetic potential and gestational age and is the second most common cause of perinatal morbidity and mortality after prematurity. Infants who have suffered fetal growth restriction are at the greatest risks for short- and long-term complications. This article specifically details the neurologic and cardiometabolic sequalae associated with fetal growth restriction, as well as the purported mechanisms that underlie their pathogenesis. We end with a brief discussion about further work that is needed to gain a more complete understanding of fetal growth restriction.

Epigenetics and In Utero Acquired Predisposition to Metabolic Disease

Epidemiological evidence has shown an association between prenatal malnutrition and a higher risk of developing metabolic disease in adult life. An inadequate intrauterine milieu affects both growth and development, leading to a permanent programming of endocrine and metabolic functions. Programming may be due to the epigenetic modification of genes implicated in the regulation of key metabolic mechanisms, including DNA methylation, histone modifications, and microRNAs (miRNAs). The expression of miRNAs in organs that play a key role in metabolism is influenced by in utero programming, as demonstrated by both experimental and human studies. miRNAs modulate multiple pathways such as insulin signaling, immune responses, adipokine function, lipid metabolism, and food intake. Liver is one of the main target organs of programming, undergoing structural, functional, and epigenetic changes following the exposure to a suboptimal intrauterine environment. The focus of this review is to provide an overview of the effects of exposure to an adverse in utero milieu on epigenome with a focus on the molecular mechanisms involved in liver programming.

Transcription profiling in the liver of undernourished male rat offspring reveals altered lipid metabolism pathways and predisposition to hepatic steatosis

Clinical and animal studies have reported an association between low birth weight and the development of nonalcoholic fatty liver disease (NAFLD) in offspring. Using a model of prenatal maternal 70% food restriction diet (FR30) in the rat, we previously showed that maternal undernutrition predisposes offspring to altered lipid metabolism in adipose tissue, especially on a high-fat (HF) diet. Here, using microarray-based expression profiling combined with metabolic, endocrine, biochemical, histological, and lipidomic approaches, we assessed whether FR30 procedure sensitizes adult male offspring to impaired lipid metabolism in the liver. No obvious differences were noted in the concentrations of triglycerides, cholesterol, and bile acids in the liver of 4-mo-old FR30 rats whichever postweaning diet was used. However, several clues suggest that offspring's lipid metabolism and steatosis are modified by maternal undernutrition. First, lipid composition was changed (i.e., higher total saturated fatty acids and lower elaidic acid) in the liver, whereas larger triglyceride droplets were observed in hepatocytes of undernourished rats. Second, FR30 offspring exhibited long-term impact on hepatic gene expression and lipid metabolism pathways on a chow diet. Although the transcriptome profile was globally modified by maternal undernutrition, cholesterol and bile acid biosynthesis pathways appear to be key targets, indicating that FR30 animals were predisposed to impaired hepatic cholesterol metabolism. Third, the FR30 protocol markedly modifies hepatic gene transcription profiles in undernourished offspring in response to postweaning HF. Overall, FR30 offspring may exhibit impaired metabolic flexibility, which does not enable them to properly cope with postweaning nutritional challenges influencing the development of nonalcoholic fatty liver.

Developmental origins of type 2 diabetes: Focus on epigenetics

Traditionally, genetics and lifestyle are considered as main determinants of aging-associated pathological conditions. Accumulating evidence, however, suggests that risk of many age-related diseases is not only determined by genetic and adult lifestyle factors but also by factors acting during early development. Type 2 diabetes (T2D), an age-related disease generally manifested after the age of 40, is among such disorders. Since several age-related conditions, such as pro-inflammatory states, are characteristic of both T2D and aging, this disease is conceptualized by many authors as a kind of premature or accelerated aging. There is substantial evidence that intrauterine growth restriction (IUGR), induced by poor or unbalanced nutrient intake, exposure to xenobiotics, maternal substance abuse etc., may impair fetal development, thereby causing the fetal adipose tissue and pancreatic beta cell dysfunction. Consequently, persisting adaptive changes may occur in the glucose-insulin metabolism, including reduced capacity for insulin secretion and insulin resistance. These changes can lead to an improved ability to store fat, thus predisposing to T2D development in later life. The modulation of epigenetic regulation of gene expression likely plays a central role in linking the adverse environmental conditions early in life to the risk of T2D in adulthood. In animal models of IUGR, long-term persistent changes in both DNA methylation and expression of genes implicated in metabolic processes have been repeatedly reported. Findings from human studies confirming the role of epigenetic mechanisms in linking early-life adverse experiences to the risk for T2D in adult life are scarce compared to data from animal studies, mainly because of limited access to suitable biological samples. It is, however, convincing evidence that these mechanisms may also operate in human beings. In this review, theoretical models and research findings evidencing the role of developmental epigenetic variation in the pathogenesis of T2D are summarized and discussed.

Supplementing Genistein for Breeder Hens Alters the Fatty Acid Metabolism and Growth Performance of Offsprings by Epigenetic Modification

The experiment was designed to clarify the effect and molecular mechanism of maternal genistein (GEN) on the lipid metabolism and developmental growth of offspring chicks. Laying broiler breeder (LBB) hens were supplemented with 40 mg/kg genistein (GEN), while the control group was fed with the low-soybean meal diet. The offspring chicks were grouped according to the mother generation with 8 replicates each. Hepatic transcriptome data revealed 3915 differentially expressed genes (DEGs, P adjusted < 0.05, fold change > 1.5 or fold change < 0.67) between chicks in the two groups. Maternal GEN activated the GH-IGF1-PI3K/Akt signaling pathway, which promoted the developmental processes and cellular amino acid metabolic processes, as well as inhibited the apoptotic process. GEN treatment significantly increased the weight gain, breast muscle percentage, and liver index in chicks. PANTHER clustering analysis suggested that maternal GEN enhanced the antioxidant activity of chicks by the upregulation of gene (SOD3, MT1, and MT4) expression. Accordingly, the activities of T-AOC and T-SOD in the liver were increased after GEN treatment. The overrepresentation tests revealed that maternal GEN influenced the glycolysis, unsaturated fatty acid biosynthesis, acyl-coenzyme A metabolism, lipid transport, and cholesterol metabolism in the chick livers. Hepatic cholesterol and long-chain fatty acid were significantly decreased after GEN treatment. However, the level of arachidonic acid was higher in the livers of the GEN-treated group compared with the CON group. Moreover, GEN treatment enhanced fatty acid β-oxidation and upregulated PPARδ expression in the chick liver. ChIP-qPCR analysis indicated that maternal GEN might induce histone H3-K36 trimethylation in the promoter region of PPARδ gene (PPARD) through Iws1, methyltransferases. It also induced histone H4-K12 acetylation at the PPARD promoter through MYST2, which activated the PPAR signaling pathways in the chick livers. In summary, supplementing LBB hens with GEN can alter lipid metabolism in the offspring chicks through epigenetic modification and improve the antioxidative capability as well as growth performance.

Western diet consumption through early life induces microvesicular hepatic steatosis in association with an altered metabolome in low birth weight Guinea pigs

Uteroplacental insufficiency-induced low birth weight (LBW) and postnatal high saturated fat/high sucrose-fructose diet (Western Diet, WD) consumption have been independently associated with the development of hepatic steatosis, while their additive effect on fatty acid, acylcarnitine and amino acid profiles in early adulthood have not been widely reported. We employed LBW, generated via uterine artery ablation, and normal birth weight (NBW) male guinea pigs fed either a WD or control diet (CD) from weaning to postnatal day 150 (early adulthood). Hepatic steatosis was absent in CD-fed offspring, while NBW/WD offspring displayed macrovesicular steatosis and LBW/WD offspring exhibited microvesicular steatosis, both occurring in a lean phenotype. Life-long consumption of the WD, irrespective of birth weight, was associated with an increase in hepatic medium- and long-chain saturated fatty acids, monounsaturated fatty acids, acylcarnitines, reduced oxidative phosphorylation complex III activity and polyunsaturated fatty acids, and molecular evidence of disrupted hepatic insulin signaling. In NBW/WD, hepatic C15:1 and C16:1n-6 fatty acids in phospholipids, C16, C18 and C18:1 acylcarnitines, concentrations of aspartate, phenylalanine, tyrosine and tryptophan and expression of carnitine palmitoyltransferase 1 alpha (CPT1α) and uncoupling protein 2 (UCP2) genes were elevated compared to LBW/WD livers. Our results suggest that LBW and life-long WD combined are influential in promoting hepatic microvesicular steatosis in conjunction with a specific mitochondrial gene expression and metabolomic profile in early adulthood.

Moderate nutrient restriction of beef heifers alters expression of genes associated with tissue metabolism, accretion, and function in fetal liver, muscle, and cerebrum by day 50 of gestation

We hypothesized that a moderate maternal nutrient restriction during the first 50 d of gestation in beef heifers would affect transcript abundance of genes associated with tissue metabolism, accretion, and function in fetal liver, muscle, and cerebrum. Angus-cross heifers were estrus synchronized and assigned at breeding to one of two dietary treatments (CON- 100% of nutrient requirements to gain 0.45 kg/d; RES- 60% of CON). At day 50 of gestation, 14 heifers were ovariohysterectomized, and fetal liver, muscle, and cerebrum were collected. Transcriptome analysis via RNA-seq was conducted on the Illumina HiSeq 2500 platform using 50-bp paired-end reads at a depth of 2 × 10.4M reads/sample. Bioinformatic analysis was performed using the Tuxedo Suite and ontological analysis with DAVID 6.8. For fetal liver, muscle, and cerebrum, a total of 548, 317, and 151 genes, respectively (P < 0.01) were differentially expressed, of which 201, 144, and 28 genes, respectively were false discovery rate protected (FDR; q < 0.10). Differentially expressed genes were screened for fit into functional categories of pathways or ontologies associated with known impacts on tissue metabolism, accretion, and function. In fetal liver, five functional categories of interest (n = 125 genes) were affected by nutritional treatment: metabolic pathways, protein kinase, nucleosome core, mRNA splicing, and complement/coagulation cascades, of which 105 genes were upregulated in RES. In fetal muscle, three functional categories of interest (n = 106 genes) were affected by nutritional treatment: skeletal muscle, embryogenesis, and signaling cascades, of which 64 genes were upregulated in RES. In fetal cerebrum, three functional categories of interest (n = 60 genes) were affected by nutritional treatment: hippocampus and neurogenesis, metal-binding, and cytoskeleton, of which 58 genes were upregulated in RES. These results demonstrate that a moderate maternal nutrient restriction during the first 50 d of gestation in beef heifers alters transcript abundance of genes potentially impacting tissue metabolism, accretion, and function in fetal liver, muscle, and cerebrum. Furthermore, these results indicate that affected categories are tissue-specific and moderate maternal nutrient restriction generally increases expression of genes in fetuses from RES fed dams. Finally, these data lay the foundation upon which further research that identifies phenotypic responses to changes in these pathways may be elucidated.

Mother or Father: Who Is in the Front Line? Mechanisms Underlying the Non-Genomic Transmission of Obesity/Diabetes via the Maternal or the Paternal Line

Extensive epidemiological and experimental evidence have shown that exposure to an adverse intrauterine environment as observed in offspring of pregnancies complicated by obesity or diabetes, can program susceptibility to metabolic, endocrine and cardiovascular disorders later in life. Although most studies have concentrated on the maternal environment, it is also becoming evident that paternal exposure to obesity or diabetes can result in the later development of metabolic disorders in the offspring. Such programmed effects might not be limited to the first directly exposed generation, but could be transmitted to subsequent generations. This suggests the existence of mechanisms by which metabolic changes in parental phenotype are transmissible to offspring. The mechanisms which underpin the transmission of the programmed effects across generations are still unclear. However, epigenetic regulation of transcription has emerged as a strong candidate for mediating the heritability of metabolic diseases. Here, we review the most relevant evidence from human and animal studies showing transmission of programming effects of obesity or diabetes across generations, and the current mechanisms underlying either maternal or paternal influences on the metabolic status of offspring.

Metabolic Biomarkers of Monochorionic Twins Complicated With Selective Intrauterine Growth Restriction in Cord Plasma and Placental Tissue

The selective intrauterine growth restriction (sIUGR) of monochorionic diamniotic (MCDC) twins causes phenotypic growth discordance, which is correlated with metabolomic pertubations. A global, untargeted identification of the metabolic fingerprint may help elucidate the etiology of sIUGR. Umbilical cord blood and placentas collected from 15 pairs of sIUGR monochorionic twins, 24 pairs of uncomplicated twins, and 14 singletons diagnosed with intrauterine growth restriction (IUGR) were subjected to gas chromatography-mass spectrometry based metabolomic analyses. Supervised multivariate regression analysis and pathway analysis were performed to compare control twins with sIUGR twins. A generalized estimating equation (GEE) model was utilized to explore metabolic differences within sIUGR co-twins. Linear logistic regression was applied to screen metabolites that significantly differed in concentration between control twins and sIUGR twins or IUGR singletons. Umbilical cord blood demonstrated better global metabolomic separation of sIUGR and control twins compared to the placenta. Disrupted amino acid and fatty acid metabolism as well as high levels of exposure to environmental xenobiotics were associated with sIUGR. The metabolic abnormalities in MCDA twins suggested that in utero growth discordance is caused by intrauterine and extrauterine environmental factors, rather than genetics. Thus, this study provides new therapeutic targets and strategies for sIUGR management and prevention.

Epigenetic Mechanisms Link Maternal Diets and Gut Microbiome to Obesity in the Offspring

Nutrition is the most important environmental factor that can influence early developmental processes through regulation of epigenetic mechanisms during pregnancy and neonatal periods. Maternal diets or nutritional compositions contribute to the establishment of the epigenetic profiles in the fetus that have a profound impact on individual susceptibility to certain diseases or disorders in the offspring later in life. Obesity is considered a global epidemic that impairs human life quality and also increases risk of development of many human diseases such as diabetes and cardiovascular diseases. Studies have shown that maternal nutrition status is closely associated with obesity in progenies indicating obesity has a developmental origin. Maternal diets may also impact the early establishment of the fetal and neonatal microbiome leading to specific epigenetic signatures that may potentially predispose to the development of late-life obesity. This article will review the association of different maternal dietary statuses including essential nutritional quantity and specific dietary components with gut microbiome in determining epigenetic impacts on offspring susceptibility to obesity.

Epigenetics and developmental origins of diabetes: correlation or causation?

The incidence of metabolic disorders like type 2 diabetes (T2D) and obesity continue to increase. Although it is evident that the increasing incidence of diabetes confers a global societal and economic burden, the mechanisms responsible for the increased incidence of T2D are not well understood. Extensive efforts to understand the association of early-life perturbations with later onset of metabolic diseases, the founding principle of developmental origins of health and disease, have been crucial in determining the mechanisms that may be driving the pathogenesis of T2D. As the programming of the epigenome occurs during critical periods of development, it has emerged as a potential molecular mechanism that could occur early in life and impact metabolic health decades later. In this review, we critically evaluate human and animal studies that illustrated an association of epigenetic processes with development of T2D as well as intervention strategies that have been employed to reverse the perturbed epigenetic modification or reprogram the naturally occurring epigenetic marks to favor improved metabolic outcome. We highlight that although our understanding of epigenetics and its contribution toward developmental origins of T2D continues to grow, whether epigenetics is a cause, consequence, or merely a correlation remains debatable due to the many limitations/challenges of the existing epigenetic studies. Finally, we discuss the potential of establishing collaborative research efforts between different disciplines, including physiology, epigenetics, and bioinformatics, to help advance the developmental origins field with great potential for understanding the pathogenesis of T2D and developing preventive strategies for T2D.

Transgenerational programming of nephron deficits and hypertension

Exposure to a sub-optimal environment in the womb can result in poor fetal growth and impair the normal development of organs. The kidney, specifically the process of nephrogenesis, has been shown to be impacted by many common pregnancy exposures including an inadequate diet, poor placental function, maternal stress as well as maternal smoking and alcohol consumption. This can result in offspring being born with a reduced nephron endowment, which places these individuals at increased risk of hypertension and chronic kidney disease (CKD). Of recent interest is whether this disease risk can be passed on to subsequent generations and, if so, what are the mechanisms and pathways involved. In this review, we highlight the growing body of evidence that a low birth weight and hypertension, which are both major risk factors for cardiovascular and CKD, can be transmitted across generations. However, as yet there is little data as to whether a low nephron endowment contributes to this disease transmission. The emerging data suggests transmission can occur both through both the maternal and paternal lines, which likely involves epigenetic mechanisms such chromatin remodelling (DNA methylation and histone modification) and non-coding RNA modifications. In addition, females who were born small and/or have a low nephron endowment are at an increased risk for pregnancy complications, which can influence the growth and development of the next generation. Future animal studies in this area should include examining nephron endowment across multiple generations and determining adult renal function. Clinically, long term follow-up studies of large birth cohorts need to be undertaken to more clearly determine the impact a sub-optimal environment in one generation has on the health outcomes in the second, and subsequent, generation.

Maternal Pregravid Obesity Remodels the DNA Methylation Landscape of Cord Blood Monocytes Disrupting Their Inflammatory Program

Prepregnancy maternal obesity is associated with adverse outcomes for the offspring, including increased incidence of neonatal bacterial sepsis and necrotizing enterocolitis. We recently reported that umbilical cord blood (UCB) monocytes from babies born to obese mothers generate a reduced IL-6/TNF-α response to TLR 1/2 and 4 ligands compared to those collected from lean mothers. These observations suggest altered development of the offspring's immune system, which in turn results in dysregulated function. We therefore investigated transcriptional and epigenetic differences within UCB monocytes stratified by prepregnancy maternal body mass index. We show that UCB monocytes from babies born to obese mothers generate a dampened response to LPS stimulation compared with those born to lean mothers, at the level of secreted immune mediators and transcription. Because gene expression profiles of resting UCB monocytes from both groups were comparable, we next investigated the role of epigenetic differences. Indeed, we detected stark differences in methylation levels within promoters and regulatory regions of genes involved in TLR signaling in resting UCB monocytes. Interestingly, the DNA methylation status of resting cells was highly predictive of transcriptional changes post-LPS stimulation, suggesting that cytosine methylation is one of the dominant mechanisms driving functional inadequacy in UCB monocytes obtained from babies born to obese mothers. These data highlight a potentially critical role of maternal pregravid obesity-associated epigenetic changes in influencing the function of an offspring's monocytes at birth. These findings further our understanding of mechanisms that explain the increased risk of infection in neonates born to mothers with high prepregnancy body mass index.

Late-gestation maternal dietary methyl donor and cofactor supplementation in sheep partially reverses protection against allergic sensitization by IUGR

Perinatal exposures are associated with altered risks of childhood allergy. Human studies and our previous work suggest that restricted growth in utero (IUGR) is protective against allergic disease. The mechanisms are not clearly defined, but reduced fetal abundance and altered metabolism of methyl donors are hypothesized as possible underlying mechanisms. Therefore, we examined whether late-gestation maternal dietary methyl donor and cofactor supplementation of the placentally restricted (PR) sheep pregnancy would reverse allergic protection in progeny. Allergic outcomes were compared between progeny from control pregnancies (CON; n = 49), from PR pregnancies without intervention (PR; n = 28), and from PR pregnancies where the dam was fed a methyl donor plus cofactor supplement from day 120 of pregnancy until delivery (PR + Methyl; n = 25). Both PR and PR + Methyl progeny were smaller than CON; supplementation did not alter birth size. PR was protective against cutaneous hypersensitivity responses to ovalbumin (OVA; P < 0.01 in singletons). Cutaneous hypersensitivity responses to OVA in PR + Methyl progeny were intermediate to and not different from the responses of CON and PR sheep. Cutaneous hypersensitivity responses to house dust mites did not differ between treatments. In singleton progeny, upper dermal mast cell density was greater in PR + Methyl than in PR or CON (each P < 0.05). The differences in the cutaneous allergic response were not explained by treatment effects on circulating immune cells or antibodies. Our results suggest that mechanisms underlying in utero programming of allergic susceptibility by IUGR and methyl donor availability may differ and imply that late-gestation methyl donor supplementation may increase allergy risk.

Maternal methyl donor and cofactor supplementation in late pregnancy increases β-cell numbers at 16 days of life in growth-restricted twin lambs

Restricted growth before birth (IUGR) increases adult risk of Type 2 diabetes by impairing insulin sensitivity and secretion. Altered fetal one-carbon metabolism is implicated in developmental programming of adult health and disease by IUGR. Therefore, we evaluated effects of maternal dietary supplementation with methyl donors and cofactors (MMDS), designed to increase fetal supply, on insulin action in the spontaneously IUGR twin lamb. In vivo glucose-stimulated insulin secretion and insulin sensitivity were measured at days 12-14 in singleton controls (CON, n = 7 lambs from 7 ewes), twins (IUGR, n = 8 lambs from 8 ewes), and twins from ewes that received MMDS (2 g rumen-protected methionine, 300 mg folic acid, 1.2 g sulfur, 0.7 mg cobalt) daily from 120 days after mating (~0.8 of term) until delivery (IUGR+MMDS, n = 8 lambs from 4 ewes). Body composition and pancreas morphometry were assessed in lambs at day 16 IUGR reduced size at birth and increased neonatal fractional growth rate. MMDS normalized long bone lengths but not other body dimensions of IUGR lambs at birth. IUGR did not impair glucose control or insulin action at days 12-14, compared with controls. MMDS increased metabolic clearance rate of insulin and increased β-cell numerical density and tended to improve insulin sensitivity, compared with untreated IUGR lambs. This demonstrates that effects of late-pregnancy methyl donor supplementation persist until at least the third week of life. Whether these effects of MMDS persist beyond early postnatal life and improve metabolic outcomes after IUGR in adults and the underlying mechanisms remain to be determined.

Epigenetic Matters: The Link between Early Nutrition, Microbiome, and Long-term Health Development

Epigenetic modifications are among the most important mechanisms by which environmental factors can influence early cellular differentiation and create new phenotypic traits during pregnancy and within the neonatal period without altering the deoxyribonucleic acid sequence. A number of antenatal and postnatal factors, such as maternal and neonatal nutrition, pollutant exposure, and the composition of microbiota, contribute to the establishment of epigenetic changes that can not only modulate the individual adaptation to the environment but also have an influence on lifelong health and disease by modifying inflammatory molecular pathways and the immune response. Postnatal intestinal colonization, in turn determined by maternal flora, mode of delivery, early skin-to-skin contact and neonatal diet, leads to specific epigenetic signatures that can affect the barrier properties of gut mucosa and their protective role against later insults, thus potentially predisposing to the development of late-onset inflammatory diseases. The aim of this review is to outline the epigenetic mechanisms of programming and development acting within early-life stages and to examine in detail the role of maternal and neonatal nutrition, microbiota composition, and other environmental factors in determining epigenetic changes and their short- and long-term effects.

Intrauterine growth restriction inhibits expression of eukaryotic elongation factor 2 kinase, a regulator of protein translation

Nutrient deprivation suppresses protein synthesis by blocking peptide elongation. Transcriptional upregulation and activation of eukaryotic elongation factor 2 kinase (eEF2K) blocks peptide elongation by phosphorylating eukaryotic elongation factor 2. Previous studies examining placentas from intrauterine growth restricted (IUGR) newborn infants show decreased eEF2K expression and activity despite chronic nutrient deprivation. However, the effect of IUGR on hepatic eEF2K expression in the fetus is unknown. We, therefore, examined the transcriptional regulation of hepatic eEF2K gene expression in a Sprague-Dawley rat model of IUGR. We found decreased hepatic eEF2K mRNA and protein levels in IUGR offspring at birth compared with control, consistent with previous placental observations. Furthermore, the CpG island within the eEF2K promoter demonstrated increased methylation at a critical USF 1/2 transcription factor binding site. In vitro methylation of this binding site caused near complete loss of eEF2K promoter activity, designating this promoter as methylation sensitive. The eEF2K promotor in IUGR offspring also lost the protective histone covalent modifications associated with unmethylated CGIs. In addition, the +1 nucleosome was displaced 3' and RNA polymerase loading was reduced at the IUGR eEF2K promoter. Our findings provide evidence to explain why IUGR-induced chronic nutrient deprivation does not result in the upregulation of eEF2K gene transcription.

Regulation of liver development: implications for liver biology across the lifespan

The liver serves a spectrum of essential metabolic and synthetic functions that are required for the transition from fetal to postnatal life. Processes essential to the attainment of adequate liver mass and function during fetal life include cell lineage specification early in development, enzymic and other functional modes of differentiation throughout gestation, and ongoing cell proliferation to achieve adequate liver mass. Available data in laboratory rodents indicate that the signaling networks governing these processes in the fetus differ from those that can sustain liver function and mass in the adult. More specifically, fetal hepatocytes may develop independent of key mitogenic signaling pathways, including those involving the Erk mitogen-activated protein kinases MAPK1/3 and the mechanistic target of rapamycin (mTOR). In addition, the fetal liver is subject to environmental influences that, through epigenetic mechanisms, can have sustained effects on function and, by extension, contribute to the developmental origin of adult metabolic disease. Finally, the mitogen-independent phenotype of rat fetal hepatocytes in late gestation makes these cells suitable for cell-based therapy of liver injury. In the aggregate, studies on the mechanisms governing fetal liver development have implications not only for the perinatal metabolic transition but also for the prevention and treatment of liver disorders throughout the lifespan.

Expression of epigenetic machinery genes is sensitive to maternal obesity and weight loss in relation to fetal growth in mice

BACKGROUND

Maternal obesity impacts fetal growth and pregnancy outcomes. To counteract the deleterious effects of obesity on fertility and pregnancy issue, preconceptional weight loss is recommended to obese women. Whether this weight loss is beneficial/detrimental for offspring remains poorly explored. Epigenetic mechanisms could be affected by maternal weight changes, perturbing expression of key developmental genes in the placenta or fetus. Our aim was to investigate the effects of chronic maternal obesity on feto-placental growth along with the underlying epigenetic mechanisms. We also tested whether preconceptional weight loss could alleviate these effects.

RESULTS

Female mice were fed either a control diet (CTRL group), a high-fat diet (obese (OB) group), or a high-fat diet switched to a control diet 2 months before conception (weight loss (WL) group). At mating, OB females presented an obese phenotype while WL females normalized metabolic parameters. At embryonic day 18.5 (E18.5), fetuses from OB females presented fetal growth restriction (FGR; -13 %) and 28 % of the fetuses were small for gestational age (SGA). Fetuses from WL females normalized this phenotype. The expression of 60 epigenetic machinery genes and 32 metabolic genes was measured in the fetal liver, placental labyrinth, and junctional zone. We revealed 23 genes altered by maternal weight trajectories in at least one of three tissues. The fetal liver and placental labyrinth were more responsive to maternal obesity than junctional zone. One third (18/60) of the epigenetic machinery genes were differentially expressed between at least two maternal groups. Interestingly, genes involved in the histone acetylation pathway were particularly altered (13/18). In OB group, lysine acetyltransferases and Bromodomain-containing protein 2 were upregulated, while most histone deacetylases were downregulated. In WL group, the expression of only a subset of these genes was normalized.

CONCLUSIONS

This study highlights the high sensitivity of the epigenetic machinery gene expression, and particularly the histone acetylation pathway, to maternal obesity. These obesity-induced transcriptional changes could alter the placental and the hepatic epigenome, leading to FGR. Preconceptional weight loss appears beneficial to fetal growth, but some effects of previous obesity were retained in offspring phenotype.

Astragalus polysaccharides affect insulin resistance by regulating the hepatic SIRT1-PGC-1α/PPARα-FGF21 signaling pathway in male Sprague Dawley rats undergoing catch-up growth

The present study investigated the effects of Astragalus polysaccharides (APS) on insulin resistance by modulation of hepatic sirtuin 1 (SIRT1)-peroxisome proliferator-activated receptor (PPAR)-γ coactivator (PGC)-1α/PPARα-fibroblast growth factor (FGF)21, and glucose and lipid metabolism. Thirty male Sprague Dawley rats were divided into three groups: A normal control group, a catch-up growth group and an APS-treated (APS-G) group. The latter two groups underwent food restriction for 4 weeks, prior to being provided with a high fat diet, which was available ad libitum. The APS-G group was orally treated with APS for 8 weeks, whereas the other groups were administered saline. Body weight was measured and an oral glucose tolerance test (OGTT) was conducted after 8 weeks. The plasma glucose and insulin levels obtained from the OGTT were assayed, and hepatic morphology was observed by light and transmission electron microscopy. In addition, the mRNA expression levels of PGC-1α/PPARα, and the protein expression levels of SIRT1, FGF21 and nuclear factor-κB were quantified in the liver and serum. APS treatment suppressed abnormal glycolipid metabolism and insulin resistance following 8 weeks of catch-up growth by improving hepatic SIRT1-PPARα-FGF21 intracellular signaling and reducing chronic inflammation, and by partially attenuating hepatic steatosis. The suppressive effects of APS on liver acetylation and glycolipid metabolism-associated molecules contributed to the observed suppression of insulin resistance. However, the mechanism underlying the effects of APS on insulin resistance requires further research in order to be elucidated. Rapid and long-term treatment with APS may provide a novel, safe and effective therapeutic strategy for type 2 diabetes.

Epigenetic contributions to the developmental origins of adult lung disease

Perinatal insults, including intrauterine growth restriction, preterm birth, maternal exposure to toxins, or dietary deficiencies produce deviations in the epigenome of lung cells. Occurrence of perinatal insults often coincides with the final stages of lung development. The result of epigenome disruptions in response to perinatal insults during lung development may be long-term structural and functional impairment of the lung and development of lung disease. Understanding the contribution of epigenetic mechanisms to life-long lung disease following perinatal insults is the focus of the developmental origins of adult lung disease field. DNA methylation, histone modifications, and microRNA changes are all observed in various forms of lung disease. However, the perinatal contribution to such epigenetic mechanisms is poorly understood. Here we discuss the developmental origins of adult lung disease, the interplay between perinatal events, lung development and disease, and the role that epigenetic mechanisms play in connecting these events.

I'm eating for two: parental dietary effects on offspring metabolism

It has long been understood that the pathogenesis of complex diseases such as diabetes includes both genetic and environmental components. More recently, it has become clear that not only does an individual's environment influence their own metabolism, but in some cases, the environment experienced by their parents may also contribute to their risk of metabolic disease. Here, we review the evidence that parental diet influences metabolic phenotype in offspring in mammals and provide a current survey of our mechanistic understanding of these effects.

Prenatal nicotine exposure-induced intrauterine programming alteration increases the susceptibility of high-fat diet-induced non-alcoholic simple fatty liver in female adult offspring rats

“Two intrauterine programming”, involved in the intrauterine origin of high-fat diet-induced NAFL in female offspring rats, induced by prenatal nicotine exposure.

Essential nutrient supplementation prevents heritable metabolic disease in multigenerational intrauterine growth-restricted rats

Intrauterine growth restriction (IUGR) confers heritable alterations in DNA methylation, rendering risk of adult metabolic syndrome (MetS). Because CpG methylation is coupled to intake of essential nutrients along the one-carbon pathway, we reasoned that essential nutrient supplementation (ENS) may abrogate IUGR-conferred multigenerational MetS. Pregnant Sprague-Dawley rats underwent bilateral uterine artery ligation causing IUGR in F1. Among the F2 generation, IUGR lineage rats were underweight at birth (6.7 vs. 8.0 g, P < 0.0001) and obese by adulthood (p160: 613 vs. 510 g; P < 0.0001). Dual energy X-ray absorptiometry studies revealed increased central fat mass (Δ+40 g), accompanied by dyslipidemic (>30% elevated, P < 0.05) serum triglycerides (139 mg/dl), very-LDLs (27.8 mg/dl), and fatty acids (632 µM). Hyperglycemic-euglycemic clamp studies and glucose tolerance testing revealed insulin resistance. Conversely, IUGR lineage ENS-fed rats did not manifest MetS, with significantly lower body weight (p160: 410 g), >5-fold less central fat mass, normal hepatic glucose efflux, and >70% reduced circulating triglycerides and very-LDLs compared with IUGR control-fed F2 offspring (P < 0.01). Moreover, increased methylation of the IGF-1 P2 transcriptional start site among IUGR lineage F2 offspring was reversed in ENS (P < 0.04). This is an initial demonstration that supplementation along the one-carbon pathway abrogates adult morbidity and associated epigenomic modifications of IGF-1 in a rodent model of multigenerational MetS.

Altered expression and chromatin structure of the hippocampal IGF1r gene is associated with impaired hippocampal function in the adult IUGR male rat

Exposure to intrauterine growth restriction (IUGR) is an important risk factor for impaired learning and memory, particularly in males. Although the basis of IUGR-associated learning and memory dysfunction is unknown, potential molecular participants may be insulin-like growth factor 1 (Igf1) and its receptor, IGF1r. We hypothesized that transcript levels and protein abundance of Igf1 and IGF1r in the hippocampus, a brain region critical for learning and memory, would be lower in IUGR male rats than in age-matched male controls at birth (postnatal day 0, P0), at weaning (P21) and adulthood (P120). We also hypothesized that changes in messenger Ribonucleic acid (mRNA) transcript levels and protein abundance would be associated with specific histone marks in IUGR male rats. Lastly, we hypothesized that IUGR male rats would perform poorer on tests of hippocampal function at P120. IUGR was induced by bilateral ligation of the uterine arteries in pregnant dams at embryonic day 19 (term is 21 days). Hippocampal Igf1 mRNA transcript levels and protein abundance were unchanged in IUGR male rats at P0, P21 or P120. At P0 and P120, IGF1r expression was increased in IUGR male rats. At P21, IGF1r expression was decreased in IUGR male rats. Increased IGF1r expression was associated with more histone 3 lysine 4 dimethylation (H3K4Me2) in the promoter region. In addition, IUGR male rats performed poorer on intermediate-term spatial working memory testing at P120. We speculate that altered IGF1r expression in the hippocampus of IUGR male rats may play a role in learning and memory dysfunction later in life.

Early life nutrition, epigenetics and programming of later life disease

The global pandemic of obesity and type 2 diabetes is often causally linked to marked changes in diet and lifestyle; namely marked increases in dietary intakes of high energy diets and concomitant reductions in physical activity levels. However, less attention has been paid to the role of developmental plasticity and alterations in phenotypic outcomes resulting from altered environmental conditions during the early life period. Human and experimental animal studies have highlighted the link between alterations in the early life environment and increased risk of obesity and metabolic disorders in later life. This link is conceptualised as the developmental programming hypothesis whereby environmental influences during critical periods of developmental plasticity can elicit lifelong effects on the health and well-being of the offspring. In particular, the nutritional environment in which the fetus or infant develops influences the risk of metabolic disorders in offspring. The late onset of such diseases in response to earlier transient experiences has led to the suggestion that developmental programming may have an epigenetic component, as epigenetic marks such as DNA methylation or histone tail modifications could provide a persistent memory of earlier nutritional states. Moreover, evidence exists, at least from animal models, that such epigenetic programming should be viewed as a transgenerational phenomenon. However, the mechanisms by which early environmental insults can have long-term effects on offspring are relatively unclear. Thus far, these mechanisms include permanent structural changes to the organ caused by suboptimal levels of an important factor during a critical developmental period, changes in gene expression caused by epigenetic modifications (including DNA methylation, histone modification, and microRNA) and permanent changes in cellular ageing. A better understanding of the epigenetic basis of developmental programming and how these effects may be transmitted across generations is essential for the implementation of initiatives aimed at curbing the current obesity and diabetes crisis.

Metabolic thrift and the genetic basis of human obesity

Evolution has molded metabolic thrift within humans, a genetic heritage that, when thrust into our modern "obesogenic" environment, creates the current obesity crisis. Modern genetic analysis has identified genetic and epigenetic contributors to obesity, an understanding of which will guide the development of environmental, pharmacologic, and genetic therapeutic interventions.

Prenatal ethanol exposure programs an increased susceptibility of non-alcoholic fatty liver disease in female adult offspring rats

Prenatal ethanol exposure (PEE) induces dyslipidemia and hyperglycemia in fetus and adult offspring. However, whether PEE increases the susceptibility to non-alcoholic fatty liver disease (NAFLD) in offspring and its underlying mechanism remain unknown. This study aimed to demonstrate an increased susceptibility to high-fat diet (HFD)-induced NAFLD and its intrauterine programming mechanisms in female rat offspring with PEE. Rat model of intrauterine growth retardation (IUGR) was established by PEE, the female fetus and adult offspring that fed normal diet (ND) or HFD were sacrificed. The results showed that, in PEE+ND group, serum corticosterone (CORT) slightly decreased and insulin-like growth factor-1 (IGF-1) and glucose increased with partial catch-up growth; In PEE+HFD group, serum CORT decreased, while serum IGF-1, glucose and triglyceride (TG) increased, with notable catch-up growth, higher metabolic status and NAFLD formation. Enhanced liver expression of the IGF-1 pathway, gluconeogenesis, and lipid synthesis as well as reduced expression of lipid output were accompanied in PEE+HFD group. In PEE fetus, serum CORT increased while IGF-1 decreased, with low body weight, hyperglycemia, and hepatocyte ultrastructural changes. Hepatic IGF-1 expression as well as lipid output was down-regulated, while lipid synthesis significantly increased. Based on these findings, we propose a "two-programming" hypothesis for an increased susceptibility to HFD-induced NAFLD in female offspring of PEE. That is, the intrauterine programming of liver glucose and lipid metabolic function is "the first programming", and postnatal adaptive catch-up growth triggered by intrauterine programming of GC-IGF1 axis acts as "the second programming".

What is the evidence in humans that DNA methylation changes link events in utero and later life disease?

Development in utero is now recognized as crucial to determining later life disease susceptibility. Whilst mechanisms are poorly understood, there has been considerable interest in the potential role of epigenetic processes in intra-uterine programming of disease. Epigenetic modifications include various mechanisms that influence chromatin structure and gene expression. Here, we review emerging data from human studies that altered DNA methylation links intra-uterine events with later life disease. Further research in this field is needed to determine whether altered DNA methylation in target tissues can be used as a biomarker for the early identification of and intervention in individuals most at risk of later life disease.

Epigenetic basis for fetal origins of age-related disease

The current concept of fetal origins of adult diseases describes in utero programming, or adaptation to a spectrum of adverse environmental conditions that ultimately leads to increased susceptibility to age-related diseases (e.g., type 2 diabetes and cardiovascular disease) later in life. Although the precise mechanism of this biological memory remains unclear, mounting evidence suggests an epigenetic basis. The increased susceptibility to chronic disease and involvement of multiple organ systems that is observed is analogous to the decline in resistance to disease that is typical of normal aging. Although the cumulative environment over the course of a lifetime can induce increasing epigenetic dysregulation, we propose that adverse events that occur during early development can induce significant additional dysregulation of the epigenome. Here, we describe the current evidence for fetal origins of adult disease and the associated role of epigenetic dysregulation. In addition, we present a new perspective on the induction of epigenetic alterations in utero, which subsequently lead to an aging phenotype marked by increased susceptibility to age-related diseases.

Maternal micronutrient restriction programs the body adiposity, adipocyte function and lipid metabolism in offspring: a review

Fetal growth is a complex process which depends both on the genetic makeup and intrauterine environment. Maternal nutrition during pregnancy is an important determinant of fetal growth. Adequate nutrient supply is required during pregnancy and lactation for the support of fetal/infant growth and development. Macro- and micronutrients are both important to sustain pregnancy and for appropriate growth of the fetus. While macronutrients provide energy and proteins for fetal growth, micronutrients play a major role in the metabolism of macronutrients, structural and cellular metabolism of the fetus. Discrepancies in maternal diet at different stages of foetal growth / offspring development can have pronounced influences on the health and well-being of the offspring. Indeed intrauterine growth restriction induced by nutrient insult can irreversibly modulate the endocrine/metabolic status of the fetus that leads to the development of adiposity and insulin resistance in its later life. Understanding the role of micronutrients during the development of fetus will provide insights into the probable underlying / associated mechanisms in the metabolic pathways of endocrine related complications. Keeping in view the modernized lifestyle and food habits that lead to the development of adiposity and world burden of obesity, this review focuses mainly on the role of maternal micronutrients in the foetal origins of adiposity.

Effect of intrauterine growth retardation on liver and long-term metabolic risk

Intrauterine growth retardation predisposes toward long-term morbidity from type 2 diabetes and cardiovascular disease. To explain this association, the concept of programming was introduced to indicate a process whereby a stimulus or insult at a critical period of development has lasting or lifelong consequences on key endocrine and metabolic pathways. Subtle changes in cell composition of tissues, induced by suboptimal conditions in utero, can influence postnatal physiological functions. There is increasing evidence, suggesting that liver may represent one of the candidate organs targeted by programming, undergoing structural, functional and epigenetic changes following exposure to an unfavorable intrauterine environment. The aim of this review is to provide insights into the molecular mechanisms underlying liver programming that contribute to increase the cardiometabolic risk in subjects with intrauterine growth restriction.

Maternal adaptations and inheritance in the transgenerational programming of adult disease

Adverse exposures in utero have long been linked with an increased susceptibility to adult cardio-renal and metabolic diseases. Clear gender differences exist, whereby growth-restricted females, although exhibiting some phenotypic modifications, are often protected from overt disease outcomes. One of the greatest physiological challenges facing the female gender, however, is that of pregnancy; yet little research has focused on the outcomes associated with this, as a potential 'second-hit' for those who were small at birth. We review the limited evidence suggesting that pregnancy may unmask cardio-renal and metabolic disease states and the consequences for long-term maternal health in females who were born small. Additionally, a growing area of research in this programming field is in the transgenerational transmission of low birth weight and disease susceptibility. Pathways for transmission might include an abnormal adaptation to pregnancy by the growth-restricted mother and/or inheritance via the parental germline. Strategies to optimise the pregnancy environment and/or prevent the consequences of inheritance of programmed deficits and dysfunction are of critical importance for future generations.

Effects of prenatal stress on hypothalamic-pituitary-adrenal (HPA) axis function over two generations of guinea pigs (Cavia aperea f. porcellus)

Prenatal stress can alter hypothalamic-pituitary-adrenal axis function with potential consequences for later life. The aim of our study was to examine in guinea pigs (Cavia aperea f. porcellus) the effects of stress experienced during F0 pregnancy on glucocorticoid levels in plasma and feces, as well as challenge performance, in F1 offspring (n=44) and fecal glucocorticoid levels in F2 offspring (n=67). F1 animals were either born to F0 dams that had been stressed with strobe light during early to mid pregnancy, resulting in a short term increase but long-term down-regulation of maternal glucocorticoid levels, or to undisturbed F0 dams. The same stressor was used as a challenge for F1 offspring at age 26 days and around 100 days. Basal plasma cortisol concentrations during early F1 development, as well as overall glucocorticoid levels at challenge tests, were lower in F1 animals that were prenatally stressed than in control animals. Fecal cortisol metabolites were initially at lower levels in prenatally stressed F1 animals, relative to control animals, but shifted to higher levels around day 68, with an additional sex difference. Effects were also seen in the F2 generation, as male but not female offspring of prenatally stressed F1 animals had significantly higher levels of cortisol metabolites in feces after weaning. We conclude that stress exposure of F0 dams resulted in lower basal glucocorticoid levels in F1 offspring during the pre-pubertal phase and during stress exposure, but higher glucocorticoid levels in post-adolescent F1 animals. Also in males of F2 generation effects of stress exposure of F0 dams were detected.

Metabolic programming, epigenetics, and gestational diabetes mellitus

The link between an adverse intrauterine environment and the development of disease later in life has been observed in offspring of pregnancies complicated by obesity and diabetes, but the molecular mechanisms underlying this phenomenon are unknown. In this review, we highlight recent publications exploring the role of gestational diabetes mellitus in the programming of disease in the offspring. We also review recent publications aiming to identify mechanisms responsible for the "programming effect" that results from exposure to diabetes in utero. Finally, we highlight research on the role of epigenetic regulation of gene expression in an animal model of uteroplacental insufficiency where the offspring develop diabetes as a model by which an exposure to the mother can alter epigenetic modifications that affect expression of key genes and ultimately lead to the development of diabetes in the offspring.

Early onset of fatty liver in growth-restricted rat fetuses and newborns

Intrauterine growth-restricted (IUGR) newborns have increased risk of adult metabolic syndrome, including fatty liver. However, it is unclear whether the fatty liver development is "programmed" or secondary to the accompanying obesity. In this study, we examined hepatic lipid accumulation and lipid-regulatory factors (sterol regulatory element-binding protein-1c and fatty acid synthase) in IUGR and Control fetal (embryonic day 20; e20) and newborn (postnatal day 1; p1) rat pups. Notably, despite of in utero undernutrition state, IUGR fetuses demonstrated "fatty liver" with upregulation of these lipogenic indices at as early as e20. Both IUGR and Control newborns exhibited the same extent of massive increase in hepatic lipid content, whereas IUGR newborns continued to exhibit upregulated lipogenic indices. The persistent upregulation of the lipogenic indices in fetal and newborn IUGR suggests that fatty liver is gestationally programmed. Our study suggested that IUGR offspring were born with an altered metabolic life strategy of increased fuel/lipid storage which could be a distinct metabolic pathway of the thrifty phenotype.

Early-life origins of type 2 diabetes: fetal programming of the beta-cell mass

A substantial body of evidence suggests that an abnormal intrauterine milieu elicited by maternal metabolic disturbances as diverse as undernutrition, placental insufficiency, diabetes or obesity, may program susceptibility in the fetus to later develop chronic degenerative diseases, such as obesity, hypertension, cardiovascular diseases and diabetes. This paper examines the developmental programming of glucose intolerance/diabetes by disturbed intrauterine metabolic condition experimentally obtained in various rodent models of maternal protein restriction, caloric restriction, overnutrition or diabetes, with a focus on the alteration of the developing beta-cell mass. In most of the cases, whatever the type of initial maternal metabolic stress, the beta-cell adaptive growth which normally occurs during gestation, does not take place in the pregnant offspring and this results in the development of gestational diabetes. Therefore gestational diabetes turns to be the ultimate insult targeting the offspring beta-cell mass and propagates diabetes risk to the next generation again. The aetiology and the transmission of spontaneous diabetes as encountered in the GK/Par rat model of type 2 diabetes, are discussed in such a perspective. This review also discusses the non-genomic mechanisms involved in the installation of the programmed effect as well as in its intergenerational transmission.

The intrauterine growth restriction phenotype: fetal adaptations and potential implications for later life insulin resistance and diabetes

The intrauterine growth restricted (IUGR) fetus develops unique metabolic adaptations in response to exposure to reduced nutrient supply. These adaptations provide survival value for the fetus by enhancing the capacity of the fetus to take up and use nutrients, thereby reducing the need for nutrient supply. Each organ and tissue in the fetus adapts differently, with the brain showing the greatest capacity for maintaining nutrient supply and growth. Such adaptations, if persistent, also have the potential in later life to promote nutrient uptake and storage, which directly lead to complications of obesity, insulin resistance, reduced insulin production, and type 2 diabetes.

Epigenetic regulation of the endothelial nitric oxide synthase gene in persistent pulmonary hypertension of the newborn rat

OBJECTIVE

Persistent pulmonary hypertension of the newborn (PPHN) is a major clinical problem. Nitric oxide produced by endothelial nitric oxide synthase (eNOS) in endothelial cells plays an important role in the pathogenesis of PPHN. The eNOS expression in endothelial cells is controlled by epigenetic regulation. The aim of this study was to investigate the epigenetic regulatory mechanisms of the eNOS gene in PPHN.

METHODS

The rat model of PPHN was induced by hypoxia and indomethacin. Pulmonary vascular endothelial cells were isolated from the fetal rat lungs by magnetic-activated cell sorting. Chromatin immunoprecipitation and bisulfite sequencing methods were used to analyze epigenetic regulation.

RESULTS

The levels of acetylated histone H3 and acetylated histone H4 at the proximal promoter of the eNOS gene in pulmonary vascular endothelial cells from PPHN were significantly higher than those from the control group (P < 0.01, respectively). Total methylation percentage of the eNOS gene promoter in PPHN rat was slightly lower than that of control, but there was no statistically significant difference between the two groups (24.7 ± 2.0 vs. 27.3 ± 2.3%, P = 0.408). These changes of epigenetic modifications at the eNOS gene promoter were consistent with increased levels of eNOS mRNA and protein in PPHN.

CONCLUSION

The increased expression of eNOS in PPHN was associated with epigenetic regulation.

Intrauterine growth restriction alters hippocampal expression and chromatin structure of Cyp19a1 variants

We evaluated the impact of uteroplacental insufficiency (UPI), and subsequent intrauterine growth restriction (IUGR), on serum testosterone and hippocampal expression of Cyp19a1 variants and aromatase in rats. Additionally, we determined UPI induced histone modification of the promoter regions of Cyp19a1 variants using chromatin immunoprecipitation. Cyp19a1 is the gene encoding the protein aromatase, that catalyzes the biosynthesis of estrogens from androgens and is necessary for masculinization of the brain. IUGR was induced via bilateral uterine artery. UPI increased serum testosterone in day of life 0 (D(0)) and day of life 21 (D(21)) IUGR males to 224% and 299% of control values, respectively. While there was no significant impact of UPI on testosterone in D(0) females, testosterone in D(21) IUGR females was 187% of controls. Cyp19a1 variant 1.f and variant II are expressed in the rat hippocampus at D(0) and D(21). UPI significantly reduced expression of Cyp19a1 variant 1.f in D(0) males, with no impact in females. Similarly at D(0), UPI reduced expression of aromatase, the protein encoded by Cyp19a1, in males. Dimethylation of H3K4 was increased in the promoter region of variant 1.f (P1.f) and trimethylation of H3K4 was decreased in the promoter region of variant II (PII). At D(21), dimethylation of H3K4 is significantly reduced in PII of IUGR males. We conclude that UPI increases serum testosterone and reduces Cyp19a1 variant 1.f expression in the hippocampus of D(0) IUGR males. Additionally, UPI alters the chromatin structure of CYP19a1 at both D(0) and D(21).