Early life nutrition, epigenetics and programming of later life disease

Differential DNA methylation at conserved non-genic elements and evidence for transgenerational inheritance following developmental exposure to mono(2-ethylhexyl) phthalate and 5-azacytidine in zebrafish

BACKGROUND

Exposure to environmental stressors during development may lead to latent and transgenerational adverse health effects. To understand the role of DNA methylation in these effects, we used zebrafish as a vertebrate model to investigate heritable changes in DNA methylation following chemical-induced stress during early development. We exposed zebrafish embryos to non-embryotoxic concentrations of the biologically active phthalate metabolite mono(2-ethylhexyl) phthalate (MEHP, 30 µM) and the DNA methyltransferase 1 inhibitor 5-azacytidine (5AC, 10 µM). Direct, latent and transgenerational effects on DNA methylation were assessed using global, genome-wide and locus-specific DNA methylation analyses.

RESULTS

Following direct exposure in zebrafish embryos from 0 to 6 days post-fertilization, genome-wide analysis revealed a multitude of differentially methylated regions, strongly enriched at conserved non-genic elements for both compounds. Pathways involved in adipogenesis were enriched with the putative obesogenic compound MEHP. Exposure to 5AC resulted in enrichment of pathways involved in embryonic development and transgenerational effects on larval body length. Locus-specific methylation analysis of 10 differentially methylated sites revealed six of these loci differentially methylated in sperm sampled from adult zebrafish exposed during development to 5AC, and in first and second generation larvae. With MEHP, consistent changes were found at 2 specific loci in first and second generation larvae.

CONCLUSIONS

Our results suggest a functional role for DNA methylation on cis-regulatory conserved elements following developmental exposure to compounds. Effects on these regions are potentially transferred to subsequent generations.

High Fat Diets Sex-Specifically Affect the Renal Transcriptome and Program Obesity, Kidney Injury, and Hypertension in the Offspring

Obesity and related disorders have increased concurrently with an increased consumption of saturated fatty acids. We examined whether post-weaning high fat (HF) diet would exacerbate offspring vulnerability to maternal HF-induced programmed hypertension and kidney disease sex-specifically, with a focus on the kidney. Next, we aimed to elucidate the gene–diet interactions that contribute to maternal HF-induced renal programming using the next generation RNA sequencing (NGS) technology. Female Sprague-Dawley rats received either a normal diet (ND) or HF diet (D12331, Research Diets) for five weeks before the delivery. The offspring of both sexes were put on either the ND or HF diet from weaning to six months of age, resulting in four groups of each sex (maternal diet/post-weaning diet; n = 5–7/group): ND/ND, ND/HF, HF/ND, and HF/HF. Post-weaning HF diet increased bodyweights of both ND/HF and HF/HF animals from three to six months only in males. Post-weaning HF diet increased systolic blood pressure in male and female offspring, irrespective of whether they were exposed to maternal HF or not. Male HF/HF offspring showed greater degrees of glomerular and tubular injury compared to the ND/ND group. Our NGS data showed that maternal HF diet significantly altered renal transcriptome with female offspring being more HF-sensitive. HF diet induced hypertension and renal injury are associated with oxidative stress, activation of renin-angiotensin system, and dysregulated sodium transporters and circadian clock. Post-weaning HF diet sex-specifically exacerbates the development of obesity, kidney injury, but not hypertension programmed by maternal HF intake. Better understanding of the sex-dependent mechanisms that underlie HF-induced renal programming will help develop a novel personalized dietary intervention to prevent obesity and related disorders.

Diet and microbiota in inflammatory bowel disease: The gut in disharmony

Bacterial colonization of the gut shapes both the local and the systemic immune response and is implicated in the modulation of immunity in both healthy and disease states. Recently, quantitative and qualitative changes in the composition of the gut microbiota have been detected in Crohn's disease and ulcerative colitis, reinforcing the hypothesis of dysbiosis as a relevant mechanism underlying inflammatory bowel disease (IBD) pathogenesis. Humans and microbes have co-existed and co-evolved for a long time in a mutually beneficial symbiotic association essential for maintaining homeostasis. However, the microbiome is dynamic, changing with age and in response to environmental modifications. Among such environmental factors, food and alimentary habits, progressively altered in modern societies, appear to be critical modulators of the microbiota, contributing to or co-participating in dysbiosis. In addition, food constituents such as micronutrients are important regulators of mucosal immunity, with direct or indirect effects on the gut microbiota. Moreover, food constituents have recently been shown to modulate epigenetic mechanisms, which can result in increased risk for the development and progression of IBD. Therefore, it is likely that a better understanding of the role of different food components in intestinal homeostasis and the resident microbiota will be essential for unravelling the complex molecular basis of the epigenetic, genetic and environment interactions underlying IBD pathogenesis as well as for offering dietary interventions with minimal side effects.

Milk's Role as an Epigenetic Regulator in Health and Disease

It is the intention of this review to characterize milk's role as an epigenetic regulator in health and disease. Based on translational research, we identify milk as a major epigenetic modulator of gene expression of the milk recipient. Milk is presented as an epigenetic "doping system" of mammalian development. Milk exosome-derived micro-ribonucleic acids (miRNAs) that target DNA methyltransferases are implicated to play the key role in the upregulation of developmental genes such as FTO, INS, and IGF1. In contrast to miRNA-deficient infant formula, breastfeeding via physiological miRNA transfer provides the appropriate signals for adequate epigenetic programming of the newborn infant. Whereas breastfeeding is restricted to the lactation period, continued consumption of cow's milk results in persistent epigenetic upregulation of genes critically involved in the development of diseases of civilization such as diabesity, neurodegeneration, and cancer. We hypothesize that the same miRNAs that epigenetically increase lactation, upregulate gene expression of the milk recipient via milk-derived miRNAs. It is of critical concern that persistent consumption of pasteurized cow's milk contaminates the human food chain with bovine miRNAs, that are identical to their human analogs. Commercial interest to enhance dairy lactation performance may further increase the epigenetic miRNA burden for the milk consumer.

Impact of nutrition on pollutant toxicity: an update with new insights into epigenetic regulation

Exposure to environmental pollutants is a global health problem and is associated with the development of many chronic diseases, including cardiovascular disease, diabetes and metabolic syndrome. There is a growing body of evidence that nutrition can both positively and negatively modulate the toxic effects of pollutant exposure. Diets high in proinflammatory fats, such as linoleic acid, can exacerbate pollutant toxicity, whereas diets rich in bioactive and anti-inflammatory food components, including omega-3 fatty acids and polyphenols, can attenuate toxicant-associated inflammation. Previously, researchers have elucidated direct mechanisms of nutritional modulation, including alteration of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling, but recently, increased focus has been given to the ways in which nutrition and pollutants affect epigenetics. Nutrition has been demonstrated to modulate epigenetic markers that have been linked either to increased disease risks or to protection against diseases. Overnutrition (i.e. obesity) and undernutrition (i.e. famine) have been observed to alter prenatal epigenetic tags that may increase the risk of offspring developing disease later in life. Conversely, bioactive food components, including curcumin, have been shown to alter epigenetic markers that suppress the activation of NF-κB, thus reducing inflammatory responses. Exposure to pollutants also alters epigenetic markers and may contribute to inflammation and disease. It has been demonstrated that pollutants, via epigenetic modulations, can increase the activation of NF-κB and upregulate microRNAs associated with inflammation, cardiac injury and oxidative damage. Importantly, recent evidence suggests that nutritional components, including epigallocatechin gallate (EGCG), can protect against pollutant-induced inflammation through epigenetic regulation of proinflammatory target genes of NF-κB. Further research is needed to better understand how nutrition can modulate pollutant toxicity through epigenetic regulation. Therefore, the objective of this review is to elucidate the current evidence linking epigenetic changes to pollutant-induced diseases and how this regulation may be modulated by nutrients allowing for the development of future personalized lifestyle interventions.

Transforming Cancer Epigenetics Using Nutritive Approaches and Noncoding RNAs

Cancer is considered one of the leading causes of death in the United States. Although preventive strategies, early detection, and improved treatment options have been developed, novel targets and therapeutics are still needed. Since concluding that cancer is mediated by genetic and epigenetic alterations of the cell, many research groups are now focusing on other means of prevention and therapy via nutrition, epigenetic mechanisms, and non-coding RNAs which have been shown to control gene expression and have many different functions at the cellular level. With the advent of high-throughput sequencing in human cancer, the potential to identify novel biomarkers and therapeutic targets of disease has increased tremendously and led to the identification of many non-coding RNAs that are dysregulated in various cancers. Gene expression and regulation is important in maintaining the homeostasis of normal tissues and cells. Not uncommonly, up- or down-regulation of particular genes are associated with cancer as a result of increased or decreased expression of transcriptional targets. This review focuses on the role of nutrition in cancer and the dysregulation of non-coding RNAs with particular emphasis on long non-coding RNAs and microRNAs in different cancer types.

Prevention of Lifestyle-related Diseases by Utilization of Newly Developed Health Record Booklet "My Karte" in Mitoyo and Kanonji Areas

In the Mitoyo and Kanonji areas, Kagawa Prefecture, Japan, we have newly developed a simple health record booklet for parents with children called "My Karte", which is an enlarged edition of the maternal and child health handbook. Our municipality borough gives this booklet together with the maternal and child handbook to all pregnant women without exception. In this booklet, care personnel or child by themselves write down the health condition and body development of the child, including medical examination records and vaccinations. From an overview of this simple record, healthcare practitioners, caretakers or school nurses can immediately grasp the child's body condition, for example, whether the child is overweight or underweight, and various health problems early and precisely. In addition, the child and care personnel can evaluate the health condition of the child through self-assessment. We hope that the self-assessment will promote health during the child's life. Moreover we are planning to collect and analyze the data from the distributed My Karte. The analyzed results will be released to the public, which will promote health consciousness in this area and give healthcare professionals basic and important data useful for daily medical practice.

Of mice and humans through the looking glass: "reflections" on epigenetics of lipid metabolism

Over the past decade, epigenetics has emerged as a new layer of regulation of gene expression. Several investigations demonstrated that nutrition and lifestyle regulate lipid metabolism by influencing epigenomic remodeling. Studies on animal models highlighted the role of epigenome modifiers in specific metabolic contexts and established clear links between dysregulation of epigenetic mechanisms and metabolic dysfunction. The relevance of findings in animal models has been translated to humans, as epigenome-wide association studies (EWAS) deeply investigated the relationship between lifestyle and epigenetics in human populations. In this review, we will provide an outlook of recent studies addressing the link between epigenetics and lipid metabolism, by comparing results obtained in animal models and in human subjects.

Maternal nutrition: opportunities in the prevention of gestational diabetes

Gestational diabetes mellitus (GDM) is currently defined as glucose intolerance that is of variable severity with onset or first recognition during pregnancy. The Hyperglycemia and Adverse Pregnancy Outcome Study, including 25 000 nondiabetic pregnant women in 15 centers across the world, reported that an average of 17.8% of pregnancies are affected by GDM and its frequency can be as high as 25.5% in some countries, based on the International Association of Diabetes and Pregnancy Study Groups criteria. Nevertheless, true global prevalence estimates of GDM are currently lacking due to the high level of heterogeneity in screening approaches, diagnostic criteria, and differences in the characteristics of the populations that were studied. The presence of systemic high blood glucose levels in pregnancy results in an adverse intrauterine environment, which has been shown to have a negative impact on short- and long-term health outcomes for both the mother and her offspring, including increased risks for the infant to develop obesity and for both mother and child to develop type 2 diabetes mellitus later in life. Epigenetic mechanisms that are directly influenced by environmental factors, including nutrition, may play a key role in shaping these future health risks and may be part of this vicious cycle. This article reviews the burden of GDM and the current evidence that supports maternal nutritional interventions as a promising strategy to break the cycle by addressing risk factors associated with GDM.

Corticotropin-Releasing Hormone As the Homeostatic Rheostat of Feto-Maternal Symbiosis and Developmental Programming In Utero and Neonatal Life

A balanced interaction between the homeostatic mechanisms of mother and the developing organism during pregnancy and in early neonatal life is essential in order to ensure optimal fetal development, ability to respond to various external and internal challenges, protection from adverse programming, and safeguard maternal care availability after parturition. In the majority of pregnancies, this relationship is highly effective resulting in successful outcomes. However, in a number of pathological settings, perturbations of the maternal homeostasis disrupt this symbiosis and initiate adaptive responses with unpredictable outcomes for the fetus or even the neonate. This may lead to development of pathological phenotypes arising from developmental reprogramming involving interaction of genetic, epigenetic, and environmental-driven pathways, sometimes with acute consequences (e.g., growth impairment) and sometimes delayed (e.g., enhanced susceptibility to disease) that last well into adulthood. Most of these adaptive mechanisms are activated and controlled by hormones of the hypothalamo-pituitary adrenal axis under the influence of placental steroid and peptide hormones. In particular, the hypothalamic peptide corticotropin-releasing hormone (CRH) plays a key role in feto-maternal communication by orchestrating and integrating a series of neuroendocrine, immune, metabolic, and behavioral responses. CRH also regulates neural networks involved in maternal behavior and this determines efficiency of maternal care and neonate interactions. This review will summarize our current understanding of CRH actions during the perinatal period, focusing on the physiological roles for both mother and offspring and also how external challenges can alter CRH actions and potentially impact on fetus/neonate health.

Hepatic DPP4 DNA Methylation Associates With Fatty Liver

Hepatic DPP4 expression is elevated in subjects with ectopic fat accumulation in the liver. However, whether increased dipeptidyl peptidase 4 (DPP4) is involved in the pathogenesis or is rather a consequence of metabolic disease is not known. We therefore studied the transcriptional regulation of hepatic Dpp4 in young mice prone to diet-induced obesity. Already at 6 weeks of age, expression of hepatic Dpp4 was increased in mice with high weight gain, independent of liver fat content. In the same animals, methylation of four intronic CpG sites was decreased, amplifying glucose-induced transcription of hepatic Dpp4 In older mice, hepatic triglyceride content was increased only in animals with elevated Dpp4 expression. Expression and release of DPP4 were markedly higher in the liver compared with adipose depots. Analysis of human liver biopsy specimens revealed a correlation of DPP4 expression and DNA methylation to stages of hepatosteatosis and nonalcoholic steatohepatitis. In summary, our results indicate a crucial role of the liver in participation to systemic DPP4 levels. Furthermore, the data show that glucose-induced expression of Dpp4 in the liver is facilitated by demethylation of the Dpp4 gene early in life. This might contribute to early deteriorations in hepatic function, which in turn result in metabolic disease such as hepatosteatosis later in life.

Exposure of bovine oocytes and embryos to elevated non-esterified fatty acid concentrations: integration of epigenetic and transcriptomic signatures in resultant blastocysts

Background

Metabolic stress associated with negative energy balance in high producing dairy cattle and obesity in women is a risk factor for decreased fertility. Non-esterified fatty acids (NEFA) are involved in this pathogenesis as they jeopardize oocyte and embryo development. Growing evidence indicates that maternal metabolic disorders can disturb epigenetic programming, such as DNA methylation, in the offspring. Oocyte maturation and early embryo development coincide with methylation changes and both are sensitive to adverse environments. Therefore, we investigated whether elevated NEFA concentrations affect establishment and maintenance of DNA methylation in oocytes and embryos, subsequently altering transcriptomic profiles and developmental competence of resultant blastocysts.

Results

Bovine oocytes and embryos were exposed to different NEFA concentrations in separate experiments. In the first experiment, oocytes were matured in vitro for 24 h in medium containing: 1) physiological (“BASAL”) concentrations of oleic (OA), palmitic (PA) and stearic (SA) acid or 2) pathophysiological (“HIGH COMBI”) concentrations of OA, PA and SA. In the second experiment, zygotes were cultivated in vitro for 6.5 days under BASAL or HIGH COMBI conditions. Developmental competence was evaluated by assessing cleavage and blastocyst rate. Overall gene expression and DNA methylation of resultant blastocysts were analyzed using microarray. DNA methylation data were re-evaluated by pyrosequencing. HIGH COMBI-exposed oocytes and embryos displayed a lower competence to develop into blastocysts compared to BASAL-exposed counterparts (19.3% compared to 23.2% and 18.2% compared to 25.3%, respectively) (P < 0.05). HIGH COMBI-exposed oocytes and embryos resulted in blastocysts with altered DNA methylation and transcriptomic fingerprints, compared to BASAL-exposed counterparts. Differences in gene expression and methylation were more pronounced after exposure during culture compared to maturation suggesting that zygotes are more susceptible to adverse environments. Main gene networks affected were related to lipid and carbohydrate metabolism, cell death, immune response and metabolic disorders.

Conclusions

Overall, high variation in methylation between blastocysts made it difficult to draw conclusions concerning methylation of individual genes, although a clear overview of affected pathways was obtained. This may offer clues regarding the high rate of embryonic loss and metabolic diseases during later life observed in offspring from mothers displaying lipolytic disorders.

Ischemia/Reperfusion

Ischemic disorders, such as myocardial infarction, stroke, and peripheral vascular disease, are the most common causes of debilitating disease and death in westernized cultures. The extent of tissue injury relates directly to the extent of blood flow reduction and to the length of the ischemic period, which influence the levels to which cellular ATP and intracellular pH are reduced. By impairing ATPase-dependent ion transport, ischemia causes intracellular and mitochondrial calcium levels to increase (calcium overload). Cell volume regulatory mechanisms are also disrupted by the lack of ATP, which can induce lysis of organelle and plasma membranes. Reperfusion, although required to salvage oxygen-starved tissues, produces paradoxical tissue responses that fuel the production of reactive oxygen species (oxygen paradox), sequestration of proinflammatory immunocytes in ischemic tissues, endoplasmic reticulum stress, and development of postischemic capillary no-reflow, which amplify tissue injury. These pathologic events culminate in opening of mitochondrial permeability transition pores as a common end-effector of ischemia/reperfusion (I/R)-induced cell lysis and death. Emerging concepts include the influence of the intestinal microbiome, fetal programming, epigenetic changes, and microparticles in the pathogenesis of I/R. The overall goal of this review is to describe these and other mechanisms that contribute to I/R injury. Because so many different deleterious events participate in I/R, it is clear that therapeutic approaches will be effective only when multiple pathologic processes are targeted. In addition, the translational significance of I/R research will be enhanced by much wider use of animal models that incorporate the complicating effects of risk factors for cardiovascular disease. © 2017 American Physiological Society. Compr Physiol 7:113-170, 2017.

High sucrose intake during gestation increases angiotensin II type 1 receptor-mediated vascular contractility associated with epigenetic alterations in aged offspring rats

Accruing evidence have confirmed that the fetal programming in response to adverse environmental in utero factors plays essential roles in the pathogenesis of hypertension in later life. High sugar intake has been accepted worldwide in everyday life diet and becomes the critical public health issue. Our previous studies indicated that intake of high sucrose (HS) during pregnancy could change the vascular reactivity and dipsogenic behavior closely associated with abnormal renin-angiotensin system (RAS), to increase the risk of hypertension in adult offspring. In the present study, we tested the hypothesis that maternal HS intake in pregnancy may further deteriorate the Ang II-induced cardiovascular responses in the aged offspring. HS intake was provided to pregnant rats throughout the gestation. Blood pressure (BP) in conscious state and vascular contractility in vitro were measured in 22-month-old aged offspring rats. In addition, mRNA and protein expressions and epigenetic changes of Ang II type 1 receptor (AT₁R) gene in blood vessels were determined with the methods of real-time RT-PCR, Western blotting, and Chromatin Immunoprecipitation Assay (CHIP). Results showed that, in the aged offspring, maternal HS intake during gestation would cause the elevation of basal BP which could be diminished by losartan. Although the circulatory Ang II was not changed, levels of local Ang II were significantly increased in blood vessels. In addition, prenatal HS exposure would significantly enhance the AT₁R-mediated vasoconstrictions in both aorta and mesenteric arteries of the aged offspring. Moreover, in the aged offspring of prenatal HS exposure, mRNA and protein expressions of AT₁R gene in both large and small blood vessels were significantly increased, which should be closely associated with the changes of epigenetic mechanisms such as histone modifications. Collectively, we proposed that maternal HS intake during gestation would cause abnormal BP responses mediated via the enhancement of vascular RAS, together with the increased expression of AT₁R gene related to the its epigenetic changes, which would actually lead to the overt phenotype of hypertension in the aged offspring.

Adverse Effect of High-Fat Diet on Metabolic Programming in Offspring Born to a Murine Model of Maternal Hypertension

BACKGROUND

We previously reported that offspring heterozygous mice partially lacking endothelial nitric oxide synthase (eNOS) gene, and born to hypertensive eNOS-/- Knockout mother, are hypertensive. We hypothesized that those offspring when placed on high-fat diet (HFD) will undergo altered metabolic programming increasing their risk for developing metabolic syndrome.

METHODS

eNOS-/-KO and wild-type mice (eNOS+/+WT) were cross-bred to produce heterozygous offspring: maternal heterozygous (Mat, eNOS-/+), born from hypertensive eNOS-/-KO mothers; and paternal heterozygous (Pat, eNOS-/+), born from normotensive WT mothers. Mat, eNOS-/+ and Pat, eNOS-/+ female were allocated to HFD or control diet (CD) until 8 weeks of age. Then a metabolic profile was obtained: weight, glucose/insulin tolerance test (GTT, ITT), systolic blood pressure (SBP), serum fasting levels of insulin, adiponectin, leptin, and a lipid panel.

RESULTS

Weight was not different between all offspring within each diet. GTT curve was higher in Mat, eNOS-/+ vs. Pat, eNOS-/+ offspring on both diet (P < 0.001). In ITT, glucose level at 15 minutes was higher in Mat, eNOS-/+ on HFD. Insulin level was increased in Mat, eNOS-/+ vs. Pat, eNOS-/+ on either diet. SBP was elevated in Mat, eNOS-/+ vs. Pat, eNOS-/+ on CD and was further raised in Mat, eNOS-/+ offspring on HFD (P < 0.001). No other differences were seen except for lower high-density lipoprotein levels in Mat, eNOS-/+ fed HFD (P < 0.003).

CONCLUSIONS

Mat, eNOS-/+ offspring exposed in utero to maternal hypertension and fed HFD postnatally have increased susceptibility for metabolic abnormalities. Thus, maternal HTN is a risk factor for altered fetal metabolic programming.

Roles of MicroRNA across Prenatal and Postnatal Periods

Communication between mother and offspring in mammals starts at implantation via the maternal-placental-fetal axis, and continues postpartum via milk targeted to the intestinal mucosa. MicroRNAs (miRNAs), short, noncoding single-stranded RNAs, of about 22 nucleotides in length, are actively involved in many developmental and physiological processes. Here we highlight the role of miRNA in the dynamic signaling that guides infant development, starting from implantation of conceptus and persisting through the prenatal and postnatal periods. miRNAs in body fluids, particularly in amniotic fluid, umbilical cord blood, and breast milk may offer new opportunities to investigate physiological and/or pathological molecular mechanisms that portend to open novel research avenues for the identification of noninvasive biomarkers.

Epigenetics in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), a common hepatic disorder ranging from simple steatosis through steatohepatitis to fibrosis and cirrhosis, is an emerging health concern. NAFLD is a pathologic condition characterized by the buildup of extra fat in liver cells that is not caused by alcohol consumption. Excess hepatic fat accumulation results from increased delivery of triglycerides (TG) to the liver or conversion of surplus carbohydrates to TG. Importantly, a subgroup of NAFLD results in hepatocellular injury and inflammation, which is referred to as non-alcoholic steatohepatitis (NASH), and may progress to irreversible cirrhosis and hepatocellular carcinoma (HCC). NAFLD shares, in part, the common pathogenesis of metabolic syndrome including obesity, hyperlipidemia, insulin resistance, mitochondrial damage, oxidative stress response, and the release of inflammatory cytokines. Epigenetics, an inheritable phenomenon that affects gene expression without altering the DNA sequence, provides a new perspective on the pathogenesis of NAFLD. Reversible epigenetic changes take place at the transcriptional level and provide a phenotypic connection between the host and environment. An accumulating body of evidence suggests the importance of epigenetic roles in NAFLD, which in turn can be identified as potential therapeutic targets and non-invasive biomarkers of NAFLD. It is anticipated that the epigenetic modifiers in NAFLD may provide novel molecular indicators that can determine not only the initial risk but also the disease progression and prognosis. In the present review, we update the roles of epigenetics as pathologic mechanisms, therapeutic targets and biomarkers in NAFLD.

Epigenetic regulation of macrophage polarization and inflammation by DNA methylation in obesity

Obesity is associated with increased classically activated M1 adipose tissue macrophages (ATMs) and decreased alternatively activated M2 ATMs, both of which contribute to obesity-induced inflammation and insulin resistance. However, the underlying mechanism remains unclear. We find that inhibiting DNA methylation pharmacologically using 5-aza-2'-deoxycytidine or genetically by DNA methyltransferase 1 (DNMT1) deletion promotes alternative activation and suppresses inflammation in macrophages. Consistently, mice with myeloid DNMT1 deficiency exhibit enhanced macrophage alternative activation, suppressed macrophage inflammation, and are protected from obesity-induced inflammation and insulin resistance. The promoter and 5'-untranslated region of peroxisome proliferator-activated receptor γ1 (PPARγ1) are enriched with CpGs and are epigenetically regulated. The saturated fatty acids stearate and palmitate and the inflammatory cytokine TNF-α significantly increase, whereas the TH2 cytokine IL-4 significantly decreases PPARγ1 promoter DNA methylation. Accordingly, inhibiting PPARγ1 promoter DNA methylation pharmacologically using 5-aza-2'-deoxycytidine or genetically by DNMT1 deletion promotes macrophage alternative activation. Our data therefore establish DNA hypermethylation at the PPARγ1 promoter induced by obesity-related factors as a critical determinant of ATM proinflammatory activation and inflammation, which contributes to insulin resistance in obesity.

Differential effects of young maternal age on child growth

BACKGROUND

The association of early maternal birthing age with smaller children has been widely observed. However, it is unclear if this is due to confounding by factors such as socioeconomic status, or the age at which child growth restriction first occurs.

OBJECTIVE

To examine the effect of early maternal birthing age on the first-born child's height-for-age in a sample of developing countries in Africa, Asia, and Latin America.

DESIGN

Cross-sectional data from Demographic Health Surveys from 18 countries were used, to select the first-born child of mothers aged 15-24 years and a range of potential confounding factors, including maternal height. Child length/height-for-age z-scores (HAZs) was estimated in age bands of 0-11, 12-23, 24-35, 36-47, and 48-59 months; HAZ was first compared between maternal age groups of 15-17, 18-19, and 20-24 years.

RESULTS

1) There were significant bivariate associations between low child HAZ and young maternal age (71 of 180 possible cases; at p<0.10), but the majority of these did not persist when controlling for confounders (41 cases, 23% of the 180). 2) For children <12 months, when controlling for confounders, three out of seven Asian countries showed a significant association between lower infant HAZ and low maternal age, as did six out of nine African countries (15-17 or 15-19 years vs. the older group). 3) The association (adjusted) continued after 24 months in 12 of the 18 countries, in Africa, Asia, and Latin America. 4) The stunting differences for children between maternal age groups were around 9 percentage points (ppts) in Asia, 14 ppts in Africa, and 10 ppts in Latin America. These data do not show whether this is due to, for example, socioeconomic factors that were not included, an emerging effect of intrauterine growth restriction, or the child feeding or caring behaviors of young mothers. The latter is considered to be the most likely.

CONCLUSIONS

The effect of low maternal age on child height restriction from 0 to 11 months occurred in half the countries studied after adjusting for confounders. Poorer growth continuing after 24 months in children of younger mothers was observed in all regions, but needs further research to determine the causes. The effects were about double (in stunting prevalence terms) in Africa, where there was an increase in 10 ppts in stunting for children of young mothers.

Developmental plasticity of mitochondrial function in American alligators, Alligator mississippiensis

The effect of hypoxia on cellular metabolism is well documented in adult vertebrates, but information is entirely lacking for embryonic organisms. The effect of hypoxia on embryonic physiology is particularly interesting, as metabolic responses during development may have life-long consequences, due to developmental plasticity. To this end, we investigated the effects of chronic developmental hypoxia on cardiac mitochondrial function in embryonic and juvenile American alligators (Alligator mississippiensis). Alligator eggs were incubated in 21% or 10% oxygen from 20 to 90% of embryonic development. Embryos were either harvested at 90% development or allowed to hatch and then reared in 21% oxygen for 3 yr. Ventricular mitochondria were isolated from embryonic/juvenile alligator hearts. Mitochondrial respiration and enzymatic activities of electron transport chain complexes were measured with a microrespirometer and spectrophotometer, respectively. Developmental hypoxia induced growth restriction and increased relative heart mass, and this phenotype persisted into juvenile life. Embryonic mitochondrial function was not affected by developmental hypoxia, but at the juvenile life stage, animals from hypoxic incubations had lower levels of Leak respiration and higher respiratory control ratios, which is indicative of enhanced mitochondrial efficiency. Our results suggest developmental hypoxia can have life-long consequences for alligator morphology and metabolic function. Further investigations are necessary to reveal the adaptive significance of the enhanced mitochondrial efficiency in the hypoxic phenotype.

Exploring the association between maternal prenatal multivitamin use and early infant growth: The Healthy Start Study

BACKGROUND

Prenatal multivitamin supplementation is recommended to improve offspring outcomes, but effects on early infant growth are unknown.

OBJECTIVES

We examined whether multivitamin supplementation in the year before delivery predicts offspring mass, body composition and early infant growth.

METHODS

Multivitamin use was assessed longitudinally in 626 women from the Healthy Start Study. Offspring body size and composition was measured with air displacement plethysmography at birth (<3 days) and postnatally (median 5.2 months). Separate multiple linear regressions assessed the relationship of weeks of daily multivitamin use with offspring mass, body composition and postnatal growth, after adjustment for potential confounders (maternal age, race, pre-pregnant body mass index; offspring gestational age at birth, sex; breastfeeding exclusivity).

RESULTS

Maternal multivitamin use was not related to offspring mass or body composition at birth, or rate of change in total or fat-free mass in the first 5 months. Multivitamin use was inversely associated with average monthly growth in offspring percent fat mass (β = -0.009, p = 0.049) between birth and postnatal exam. Offspring of non-users had a monthly increase in percent fat mass of 3.45%, while offspring at the top quartile of multivitamin users had a monthly increase in percent fat mass of 3.06%. This association was not modified by exclusive breastfeeding.

CONCLUSIONS

Increased multivitamin use in the pre-conception and prenatal periods was associated with a slower rate of growth in offspring percent fat mass in the first 5 months of life. This study provides further evidence that in utero nutrient exposures may affect offspring adiposity beyond birth.

Functional AdoMet Isosteres Resistant to Classical AdoMet Degradation Pathways

S-adenosyl-l-methionine (AdoMet) is an essential enzyme cosubstrate in fundamental biology with an expanding range of biocatalytic and therapeutic applications. We report the design, synthesis, and evaluation of stable, functional AdoMet isosteres that are resistant to the primary contributors to AdoMet degradation (depurination, intramolecular cyclization, and sulfonium epimerization). Corresponding biochemical and structural studies demonstrate the AdoMet surrogates to serve as competent enzyme cosubstrates and to bind a prototypical class I model methyltransferase (DnrK) in a manner nearly identical to AdoMet. Given this conservation in function and molecular recognition, the isosteres presented are anticipated to serve as useful surrogates in other AdoMet-dependent processes and may also be resistant to, and/or potentially even inhibit, other therapeutically relevant AdoMet-dependent metabolic transformations (such as the validated drug target AdoMet decarboxylase). This work also highlights the ability of the prototypical class I model methyltransferase DnrK to accept non-native surrogate acceptors as an enabling feature of a new high-throughput methyltransferase assay.

Dietary glucose stimulus at larval stage modifies the carbohydrate metabolic pathway in gilthead seabream (Sparus aurata) juveniles: An in vivo approach using (14)C-starch

The concept of nutritional programming was investigated in order to enhance the use of dietary carbohydrates in gilthead seabream juveniles. We assessed the long-term effects of high-glucose stimuli, exerted at the larval stage, on the growth performance, nutrient digestibility and metabolic utilization and gene expression of seabream juveniles, challenged with a high-carbohydrate intake. During early development, a group of larvae (control, CTRL) were kept under a rich-protein-lipid feeding regime whereas another group (GLU) was subjected to high-glucose stimuli, delivered intermittently over time. At juvenile stage, triplicate groups (IBW: 2.5g) from each fish nutritional background were fed a high-protein (59.4%) low-carbohydrate (2.0%) diet before being subjected to a low-protein (43.0%) high-carbohydrate (33.0%) dietary challenge for 36-days. Fish from both treatments increased by 8-fold their initial body weight, but neither growth rate, feed intake, feed and protein efficiency, nutrient retention (except lipids) nor whole-body composition were affected (P˃0.05) by fish early nutritional history. Nutrient digestibility was also similar among both groups. The metabolic fate of (14)C-starch and (14)C-amino acids tracers was estimated; GLU juveniles showed higher absorption of starch-derived glucose in the gut, suggesting an enhanced digestion of carbohydrates, while amino acid use was not affected. Moreover, glucose was less used for de novo synthesis of hepatic proteins and muscle glycogen from GLU fish (P<0.05). Our metabolic data suggests that the early glucose stimuli may alter carbohydrate utilization in seabream juveniles.

Family experiences of infant and young child feeding in lower-income countries: protocol for a systematic review of qualitative studies

BACKGROUND

Infant and young child feeding practices, including breastfeeding and complementary feeding of children under 2 years old, are crucially influenced by parent and family perceptions and experiences. Given the urgent need to improve nutrition of young children in low- and low-middle-income countries, both for reduction of morbidity and mortality in childhood and for future health outcomes, we propose to systematically review and synthesize available qualitative data specifically related to infant and young child feeding practices of parents and families in these settings, which may provide greater insights into barriers and facilitators to recommended feeding practices.

METHODS/DESIGN

The proposed study will systematically review existing qualitative research reporting infant and young child feeding practices from low- and low-middle-income settings. The Enhancing Transparency in Reporting the Synthesis of Qualitative Research (ENTREQ) statement will be used for reporting the stages of the review and dissemination. The search period will include all studies published from 2006 to 2016. The study selection process will follow established and recommended guidelines for reviews, and quality assessment will be conducted in two phases using critical appraisal and subsequently a confidence in findings approach derived from Grading of Recommendations, Assessment, Development and Evaluation-Confidence in the Evidence from Reviews of Qualitative (GRADE-CERQual). A full synthesis of the studies identified by the review will begin with thematic analysis and be followed by an interpretive approach to provide actionable information on the topic.

DISCUSSION

The findings will provide insight into the barriers and facilitators related to behavior that may hinder or enable implementation of interventions aimed at improving infant and young child feeding practices in lower-income settings.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016035677.

Adverse maternal exposures, methylation of glucocorticoid-related genes and perinatal outcomes: a systematic review

Aim: Maternal environmental exposures affect perinatal outcomes through epigenetic placental changes. We examine the literature addressing associations between adverse maternal exposures, perinatal outcomes and methylation of key genes regulating placental cortisol metabolism. Methods: We searched three databases for studies that examined NR3C1 and HSD11β1/HSD11 β 2 methylation with maternal exposures or perinatal outcomes. Nineteen studies remained after screening. We followed Cochrane's PRISMA reporting guidelines (2009). Results: NR3C1 and HSD11 β methylation were associated with adverse infant neurobehavior, stress response, blood pressure and physical development. In utero exposure to maternal stress, nutrition, preeclampsia, smoking and diabetes were associated with altered NR3C1 and HSD11 β methylation. Conclusion: NR3C1 and HSD11 β methylation are useful biomarkers of specific environmental stressors associated with important perinatal outcomes that determine pediatric and adult disease risk.

Developmental cigarette smoke exposure II: Hepatic proteome profiles in 6 month old adult offspring

Utilizing a mouse model of 'active' developmental cigarette smoke exposure (CSE) [gestational day (GD) 1 through postnatal day (PD) 21] characterized by offspring low birth weight, the impact of developmental CSE on liver proteome profiles of adult offspring at 6 months of age was determined. Liver tissue was collected from Sham- and CSE-offspring for 2D-SDS-PAGE based proteome analysis with Partial Least Squares-Discriminant Analysis (PLS-DA). A similar study conducted at the cessation of exposure to cigarette smoke documented decreased gluconeogenesis coupled to oxidative stress in weanling offspring. In the current study, exposure throughout development to cigarette smoke resulted in impaired hepatic carbohydrate metabolism, decreased serum glucose levels, and increased gluconeogenic regulatory enzyme abundances during the fed-state coupled to decreased expression of SIRT1 as well as increased PEPCK and PGC1α expression. Together these findings indicate inappropriately timed gluconeogenesis that may reflect impaired insulin signaling in mature offspring exposed to 'active' developmental CSE.

Development of immune organs and functioning in humans and test animals: Implications for immune intervention studies

A healthy immune status is mostly determined during early life stages and many immune-related diseases may find their origin in utero and the first years of life. Therefore, immune health optimization may be most effective during early life. This review is an inventory of immune organ maturation events in relation to developmental timeframes in minipig, rat, mouse and human. It is concluded that time windows of immune organ development in rodents can be translated to human, but minipig reflects the human timeframes better; however the lack of prenatal maternal-fetal immune interaction in minipig may cause less responsiveness to prenatal intervention. It is too early to conclude which immune parameters are most appropriate, because there are not enough comparative immune parameters. Filling these gaps will increase the predictability of results observed in experimental animals, and guide future intervention studies by assessing relevant parameters in the right corresponding developmental time frames.

Critical review evaluating the pig as a model for human nutritional physiology

The present review examines the pig as a model for physiological studies in human subjects related to nutrient sensing, appetite regulation, gut barrier function, intestinal microbiota and nutritional neuroscience. The nutrient-sensing mechanisms regarding acids (sour), carbohydrates (sweet), glutamic acid (umami) and fatty acids are conserved between humans and pigs. In contrast, pigs show limited perception of high-intensity sweeteners and NaCl and sense a wider array of amino acids than humans. Differences on bitter taste may reflect the adaptation to ecosystems. In relation to appetite regulation, plasma concentrations of cholecystokinin and glucagon-like peptide-1 are similar in pigs and humans, while peptide YY in pigs is ten to twenty times higher and ghrelin two to five times lower than in humans. Pigs are an excellent model for human studies for vagal nerve function related to the hormonal regulation of food intake. Similarly, the study of gut barrier functions reveals conserved defence mechanisms between the two species particularly in functional permeability. However, human data are scant for some of the defence systems and nutritional programming. The pig model has been valuable for studying the changes in human microbiota following nutritional interventions. In particular, the use of human flora-associated pigs is a useful model for infants, but the long-term stability of the implanted human microbiota in pigs remains to be investigated. The similarity of the pig and human brain anatomy and development is paradigmatic. Brain explorations and therapies described in pig, when compared with available human data, highlight their value in nutritional neuroscience, particularly regarding functional neuroimaging techniques.

Transgenerational programming of longevity and reproduction by post-eclosion dietary manipulation in Drosophila

Accumulating evidence suggests that early-life diet may program one's health status by causing permanent alternations in specific organs, tissues, or metabolic or homeostatic pathways, and such programming effects may propagate across generations through heritable epigenetic modifications. However, it remains uninvestigated whether postnatal dietary changes may program longevity across generations. To address this question of important biological and public health implications, newly-born flies (F0) were collected and subjected to various post-eclosion dietary manipulations (PDMs) with different protein-carbohydrate (i.e., LP, IP or HP for low-, intermediate- or high-protein) contents or a control diet (CD). Longevity and fecundity analyses were performed with these treated F0 flies and their F1, F2 and F3 offspring, while maintained on CD at all times. The LP and HP PDMs shortened longevity, while the IP PDM extended longevity significantly up to the F3 generation. Furthermore, the LP reduced while the IP PDM increased lifetime fecundity across the F0-F2 generations. Our observations establish the first animal model for studying transgenerational inheritance of nutritional programming of longevity, making it possible to investigate the underlying epigenetic mechanisms and identify gene targets for drug discovery in future studies.

Application of spectroscopy (1HMRS) to assess liver metabolite concentrations in rats with intrauterine growth restriction

OBJECTIVE

Proton magnetic resonance spectroscopy (¹H-MRS) measurement of liver metabolism in intrauterine growth restriction rats has seldom been reported. This study investigated the application of ¹H-MRS in assessing liver metabolism in newborn pups that experienced intrauterine growth restriction.

METHODS

Intra-uterine growth restriction was established by feeding rats low-protein diets during pregnancy. Newborn pups received conventional magnetic resonance imaging and ¹H-MRS using a 3.0T whole body MR scanner at 3, 8 and 12 weeks post birth.

RESULTS

The success rate of ¹H-MRS was 83.33%. Significantly lower body weight, BMI and body length at 3 weeks as well as significantly lower body weight, BMI and waist circumference at 8 and 12 weeks were observed in newborn pups of IUGR rats compared with pups of control rats. Significant differences in ACho/H₂O, ACr/H₂O, AGlx/H₂O and ALipid/H₂O at 3 and 8 weeks as well as significant differences in ACr/H₂O, ALipid/H₂O and AGlx/H₂O at 12 weeks were observed between pups of control rats and pups of IUGR rats.

CONCLUSION

¹H-MRS allows noninvasive assessment of liver metabolism in the rat and demonstrated the poor liver development of rats that experienced IUGR.

Epigenetics in Paediatric Gastroenterology, Hepatology, and Nutrition: Present Trends and Future Perspectives

Epigenetics can be defined as stable, potentially heritable changes in the cellular phenotype caused by mechanisms other than alterations to the underlying DNA sequence. As such, any observed phenotypic changes including organ development, aging, and the occurrence of disease could be driven by epigenetic mechanisms in the presence of stable cellular DNA sequences. Indeed, with the exception of rare mutations, the human genome-sequence has remained remarkably stable over the past centuries. In contrast, substantial changes to our environment as part of our modern life style have not only led to a significant reduction of certain infectious diseases but also seen the exponential increase in complex traits including obesity and multifactorial diseases such as autoimmune disorders. It is becoming increasingly clear that epigenetic mechanisms operate at the interface between the genetic code and our environment, and a large body of existing evidence supports the importance of environmental factors such as diet and nutrition, infections, and exposure to toxins on human health. This seems to be particularly the case during vulnerable periods of human development such as pregnancy and early life. Importantly, as the first point of contact for many of such environmental factors including nutrition, the digestive system is being increasingly linked to a number of "modern" pathologies. In this review article, we aim to give a brief introduction to the basic molecular principals of epigenetics and provide a concise summary of the existing evidence for the role of epigenetic mechanisms in gastrointestinal health and disease, hepatology, and nutrition.

Maternal protein restriction during gestation impairs female offspring pancreas development in the rat

A maternal low-protein (LP) diet programs fetal pancreatic islet β-cell development and function and predisposes offspring to metabolic dysfunction later in life. We hypothesized that maternal protein restriction during pregnancy differentially alters β- and α-cell populations in offspring by modifying islet ontogeny and function throughout life. We aimed to investigate the effect of an LP maternal diet on pancreatic islet morphology and cellular composition in female offspring on postnatal days (PNDs) 7, 14, 21, 36, and 110. Mothers were divided into 2 groups: during pregnancy, the control group (C) was fed a diet containing 20% casein, and the LP group was fed an isocaloric diet with 10% casein. Offspring pancreases were obtained at each PND and then processed. β and α cells were detected by immunohistochemistry, and cellular area and islet size were quantified. Islet cytoarchitecture and total area were similar in C and LP offspring at all ages studied. At the early ages (PNDs 7-21), the proportion of β cells was lower in LP than C offspring. The proportion of α cells was lower in LP than C offspring on PND 14 and higher on PND 21. The β/α-cell ratio was lower in LP compared with C offspring on PNDs 7 and 21 and higher on PND 36 (being similar on PNDs 14 and 110). We concluded that maternal protein restriction during pregnancy modifies offspring islet cell ontogeny by altering the proportions of islet sizes and by reducing the number of β cells postnatally, which may impact pancreatic function in adult life.

Is there A Role for Alpha-Linolenic Acid in the Fetal Programming of Health?

The role of ω3 alpha linolenic acid (ALA) in the maternal diet during pregnancy and lactation, and its effect on the prevention of disease and programming of health in offspring, is largely unknown. Compared to ALA, ω3 docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids have been more widely researched due to their direct implication in fetal neural development. In this literature search we found that ALA, the essential ω3 fatty acid and metabolic precursor of DHA and EPA has been, paradoxically, almost unexplored. In light of new and evolving findings, this review proposes that ALA may have an intrinsic role, beyond the role as metabolic parent of DHA and EPA, during fetal development as a regulator of gene programming for the prevention of metabolic disease and promotion of health in offspring.

Fructose consumption induces hypomethylation of hepatic mitochondrial DNA in rats

AIMS

Fructose may play a crucial role in the pathogenesis of metabolic syndrome (MetS). However, the pathogenic mechanism of the fructose-induced MetS has not yet been investigated fully. Recently, several reports have investigated the association between mitochondrial DNA (mtDNA) and MetS. We examined the effect of fructose-rich diets on mtDNA content, transcription, and epigenetic changes.

MAIN METHODS

Four-week-old male Sprague-Dawley rats were offered a 20% fructose solution for 14weeks. We quantified mRNAs for hepatic mitochondrial genes and analyzed the mtDNA methylation (5-mC and 5-hmC) levels using ELISA kits.

KEY FINDINGS

Histological analysis revealed non-alcoholic fatty liver disease (NAFLD) in fructose-fed rats. Hepatic mtDNA content and transcription were higher in fructose-fed rats than in the control group. Global hypomethylation of mtDNA was also observed in fructose-fed rats.

SIGNIFICANCE

We showed that fructose consumption stimulates hepatic mtDNA-encoded gene expression. This phenomenon might be due to epigenetic changes in mtDNA. Fructose-induced mitochondrial epigenetic changes appear to be a novel mechanism underlying the pathology of MetS and NAFLD.

Influence of grand-mother diet on offspring performances through the male line in Muscovy duck

Background

In mammals, multigenerational environmental effects have been documented by either epidemiological studies in human or animal experiments in rodents. Whether such phenomena also occur in birds for more than one generation is still an open question. The objective of this study was to investigate if a methionine deficiency experienced by a mother (G0) could affect her grand-offspring phenotypes (G2 hybrid mule ducks and G2 purebred Muscovy ducks), through their Muscovy sons (G1). Muscovy drakes are used for the production of mule ducks, which are sterile offspring of female common duck (Anas platyrhynchos) and Muscovy drakes (Cairina moschata). In France, mule ducks are bred mainly for the production of “foie gras”, which stems from hepatic steatosis under two weeks of force-feeding (FF). Two groups of female Muscovy ducks received either a methionine deficient diet or a control diet. Their sons were mated to Muscovy or to common duck females to produce Muscovy or Mule ducks, respectively. Several traits were measured in the G2 progenies, concerning growth, feed efficiency during FF, body composition after FF, and quality of foie gras and magret.

Results

In the G2 mule duck progeny, grand-maternal methionine deficiency (GMMD) decreased 4, 8, and 12 week body weights but increased weight gain and feed efficiency during FF, and abdominal fat weight. The plasmatic glucose and triglyceride contents at the end of FF were higher in the methionine deficient group. In the G2 purebred Muscovy progeny, GMMD tended to decrease 4 week body weight in both sexes, and decreased weight gain between the ages of 4 and 12 weeks, 12 week body weight, and body weight at the end of FF in male offspring only. GMMD tended to increase liver weight and increased the carcass proportion of liver in both sexes.

Conclusion

Altogether, these results show that the mother’s diet is able to affect traits linked to growth and to lipid metabolism in the offspring of her sons, in Muscovy ducks. Whether this transmission through the father of information induced in the grand-mother by the environment is epigenetic remains to be demonstrated.

Electronic supplementary material

The online version of this article (doi:10.1186/s12863-015-0303-z) contains supplementary material, which is available to authorized users.

MicroRNAs in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) has become the most common liver disorder. Strongly linked to obesity and diabetes, NAFLD has the characteristics of complex diseases with substantial heterogeneity. Accordingly, our ability to predict the risk of advanced NAFLD and provide efficient treatment may improve by a better understanding of the relationship between genotype and phenotype. MicroRNAs (miRNAs) play a major role in the fine-tuning of gene expression and they have recently emerged as novel biomarkers and therapeutic tools in the management of NAFLD. These short non-coding RNA sequences act by partial repression or degradation of targeted mRNAs. Deregulation of miRNAs has been associated with different stages of NAFLD, while their biological role in the pathogenesis remains to be fully understood. Systems biology analyses based on predicted target genes have associated hepatic miRNAs with molecular pathways involved in NAFLD progression such as cholesterol and lipid metabolism, insulin signaling, oxidative stress, inflammation, and pathways of cell survival and proliferation. Moreover, circulating miRNAs have been identified as promising noninvasive biomarkers of NAFLD and linked to disease severity. This rapidly growing field is likely to result in major advances in the pathomechanism, prognostication, and treatment of NAFLD.

Impact of Maternal Diet on the Epigenome during In Utero Life and the Developmental Programming of Diseases in Childhood and Adulthood

Exposure to environmental factors in early life can influence developmental processes and long-term health in humans. Early life nutrition and maternal diet are well-known examples of conditions shown to influence the risk of developing metabolic diseases, including type 2 diabetes mellitus and cardiovascular diseases, in adulthood. It is increasingly accepted that environmental compounds, including nutrients, can produce changes in the genome activity that, in spite of not altering the DNA sequence, can produce important, stable and, in some instances, transgenerational alterations in the phenotype. Epigenetics refers to changes in gene function that cannot be explained by changes in the DNA sequence, with DNA methylation patterns/histone modifications that can make important contributions to epigenetic memory. The epigenome can be considered as an interface between the genome and the environment that is central to the generation of phenotypes and their stability throughout the life course. To better understand the role of maternal health and nutrition in the initiation and progression of diseases in childhood and adulthood, it is necessary to identify the physiological and/or pathological roles of specific nutrients on the epigenome and how dietary interventions in utero and early life could modulate disease risk through epigenomic alteration.

The effects of long-term daily folic acid and vitamin B12 supplementation on genome-wide DNA methylation in elderly subjects

BACKGROUND

Folate and its synthetic form folic acid function as donor of one-carbon units and have been, together with other B-vitamins, implicated in programming of epigenetic processes such as DNA methylation during early development. To what extent regulation of DNA methylation can be altered via B-vitamins later in life, and how this relates to health and disease, is not exactly known. The aim of this study was to identify effects of long-term supplementation with folic acid and vitamin B12 on genome-wide DNA methylation in elderly subjects. This project was part of a randomized, placebo-controlled trial on effects of supplemental intake of folic acid and vitamin B12 on bone fracture incidence (B-vitamins for the PRevention Of Osteoporotic Fractures (B-PROOF) study). Participants with mildly elevated homocysteine levels, aged 65-75 years, were randomly assigned to take 400 μg folic acid and 500 μg vitamin B12 per day or a placebo during an intervention period of 2 years. DNA was isolated from buffy coats, collected before and after intervention, and genome-wide DNA methylation was determined in 87 participants (n = 44 folic acid/vitamin B12, n = 43 placebo) using the Infinium HumanMethylation450 BeadChip.

RESULTS

After intervention with folic acid and vitamin B12, 162 (versus 14 in the placebo group) of the 431,312 positions were differentially methylated as compared to baseline. Comparisons of the DNA methylation changes in the participants receiving folic acid and vitamin B12 versus placebo revealed one single differentially methylated position (cg19380919) with a borderline statistical significance. However, based on the analyses of differentially methylated regions (DMRs) consisting of multiple positions, we identified 6 regions that differed statistically significantly between the intervention and placebo group. Pronounced changes were found for regions in the DIRAS3, ARMC8, and NODAL genes, implicated in carcinogenesis and early embryonic development. Furthermore, serum levels of folate and vitamin B12 or plasma homocysteine were related to DNA methylation of 173, 425, and 11 regions, respectively. Interestingly, for several members of the developmental HOX genes, DNA methylation was related to serum levels of folate.

CONCLUSIONS

Long-term supplementation with folic acid and vitamin B12 in elderly subjects resulted in effects on DNA methylation of several genes, among which genes implicated in developmental processes.