The regulation of hepatic Pon1 by a maternal high-fat diet is gender specific and may occur through promoter histone modifications in neonatal rats

Nutrigenetic and Epigenetic Mechanisms of Maternal Nutrition-Induced Glucolipid Metabolism Changes in the Offspring

Maternal nutrition during pregnancy regulates the offspring's metabolic homeostasis, including insulin sensitivity and the metabolism of glucose and lipids. The fetus undergoes a crucial period of plasticity in the uterus; metabolic changes in the fetus during pregnancy caused by maternal nutrition not only influence fetal growth and development but also have a long-term or even life-long impact for the offspring. Epigenetic modifications, such as DNA methylation, histone modification, and non-coding RNAs, play important roles in intergenerational and transgenerational effects. In this context, this narrative review comprehensively summarizes and analyzes the molecular mechanisms underlying how maternal nutrition, including a high-fat diet, polyunsaturated fatty acid diet, methyl donor nutrient supplementation, feed restriction, and protein restriction during pregnancy, impacts the genes involved in glucolipid metabolism in the liver, adipose tissue, hypothalamus, muscle, and oocytes of the offspring in terms of the epigenetic modifications. This will provide a foundation for the further exploration of nutrigenetic and epigenetic mechanisms for integrative mother-child nutrition and promotion of the offspring's health through the regulation of maternal nutrition during pregnancy. Note: This paper is part of the Nutrition Reviews Special Collection on Precision Nutrition.

High-fat diet in early life triggers both reversible and persistent epigenetic changes in the medaka fish (Oryzias latipes)

BACKGROUND

The nutritional status during early life can have enduring effects on an animal's metabolism, although the mechanisms underlying these long-term effects are still unclear. Epigenetic modifications are considered a prime candidate mechanism for encoding early-life nutritional memories during this critical developmental period. However, the extent to which these epigenetic changes occur and persist over time remains uncertain, in part due to challenges associated with directly stimulating the fetus with specific nutrients in viviparous mammalian systems.

RESULTS

In this study, we used medaka as an oviparous vertebrate model to establish an early-life high-fat diet (HFD) model. Larvae were fed with HFD from the hatching stages (one week after fertilization) for six weeks, followed by normal chow (NC) for eight weeks until the adult stage. We examined the changes in the transcriptomic and epigenetic state of the liver over this period. We found that HFD induces simple liver steatosis, accompanied by drastic changes in the hepatic transcriptome, chromatin accessibility, and histone modifications, especially in metabolic genes. These changes were largely reversed after the long-term NC, demonstrating the high plasticity of the epigenetic state in hepatocytes. However, we found a certain number of genomic loci showing non-reversible epigenetic changes, especially around genes related to cell signaling, liver fibrosis, and hepatocellular carcinoma, implying persistent changes in the cellular state of the liver triggered by early-life HFD feeding.

CONCLUSION

In summary, our data show that early-life HFD feeding triggers both reversible and persistent epigenetic changes in medaka hepatocytes. Our data provide novel insights into the epigenetic mechanism of nutritional programming and a comprehensive atlas of the long-term epigenetic state in an early-life HFD model of non-mammalian vertebrates.

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.

Dietary trends and the decline in male reproductive health

Over the twentieth century, male reproductive health has suffered a substantial decline, as evidenced by decreases in sperm counts and testosterone levels and increases in reproductive pathologies. At the same time, the prevalence of chronic diseases such as obesity, diabetes, and metabolic syndrome has risen dramatically. Metabolic and reproductive health are highly interconnected, suggesting that their respective trends are intertwined and, given the timeframe of such trends, environmental and not genetic factors are most likely to be the primary causes. Industrialization, which began in Europe in the mid-eighteenth century, has resulted in profound changes to our diet, lifestyle, and environment, many of which are causal factors in the rise in chronic diseases. Industrialization results in a nutrition transition from an agricultural unprocessed to a modern processed diet, incorporating increases in sugar, vegetable oils, ultra-processed foods, linoleic acid, trans-fats, and total energy. This dietary shift has incurred numerous adverse effects on metabolic and reproductive health, characterized by chronic inflammation, oxidative stress, and insulin resistance. Moreover, these effects appear to multiply across subsequent generations via epigenetic inheritance. Men's fertility is markedly affected by obesity and diabetes, with an increase in total energy via processed food intake arguably being the key factor driving the diabesity pandemic. In contrast, wholefoods rich in micronutrients and phytonutrients support male fertility and a healthy body weight. Therefore, men wanting to maximize their fertility should consider making positive dietary changes, such as replacing processed foods with unprocessed foods that support metabolic and reproductive health.

Exposure to maternal fuels during pregnancy and offspring hepatic fat in early childhood: The healthy start study

BACKGROUND

Intrauterine overnutrition has been associated with paediatric nonalcoholic fatty liver disease (NAFLD), but the exact mechanisms involved remain unclear.

OBJECTIVE

To examine whether maternal fuels and metabolic markers during pregnancy are associated with offspring hepatic fat in childhood.

METHODS

This analysis included 286 mother-child pairs from the Healthy Start Study, a longitudinal pre-birth cohort in Colorado. Fasting blood draws were collected in early pregnancy (~17 weeks) and mid-pregnancy (~27 weeks). Offspring hepatic fat was assessed by magnetic resonance imaging (MRI) at ~5 years.

RESULTS

In early pregnancy, maternal triglycerides (TGs) and free fatty acids (FFAs) were positively associated with offspring hepatic fat [Back-transformed β (95% CI): 1.15 (1.05, 1.27) per 1 standard deviation (SD) TGs; 1.14 (1.05, 1.23) per 1 SD FFAs]. Maternal total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were also associated with offspring hepatic fat, but only among boys [1.22 (1.08, 1.37) per 1 SD TC; 1.21 (1.07, 1.37) per 1 SD LDL-C]. In mid-pregnancy, only maternal TGs remained associated with offspring hepatic fat. Adjusting for potential confounders or mediators did not affect associations.

CONCLUSIONS

Maternal lipid concentrations, especially in early pregnancy, are associated with higher offspring hepatic fat, and may, therefore, be targeted in future interventions among pregnant women.

The Relationship between Cancer and Paraoxonase 1

Extensive research has been carried out to understand and elucidate the mechanisms of paraoxonase 1 (PON1) in the development of diseases including cancer, cardiovascular diseases, neurological diseases, and inflammatory diseases. This review focuses on the relationship between PON1 and cancer. The data suggest that PON1, oxidative stress, chronic inflammation, and cancer are closely linked. Certainly, the gene expression of PON1 will remain challenging to study. Therefore, targeting PON1, redox-sensitive pathways, and transcription factors promise prevention and therapy in the development of several diseases, including cancer.

Gestational exposure to high fat diets and bisphenol A alters metabolic outcomes in dams and offspring, but produces hepatic steatosis only in dams

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing worldwide. Perinatal development is a critical window for altered, lifelong health trajectory, and evidence supports the role of perinatal programming in chronic metabolic diseases. To examine the impact of diet and bisphenol A (BPA) on the developmental trajectory of NAFLD in offspring, we exposed dams from pre-gestation through lactation to a human-relevant dose of oral BPA coupled with intake of high fat Western or Mediterranean-style diets. We assessed hepatic steatosis by quantifying hepatic triglycerides (TGs) and metabolic health by measuring body weight, relative organ weights, and serum hormone levels in dams and offspring at postnatal day 10 (PND10) and 10-months of age. In dams, consumption of the Western or Mediterranean diet increased hepatic TGs 1.7-2.4-fold, independent of BPA intake. Among offspring, both perinatal diet and BPA exposure had a greater impact on metabolic outcomes than on hepatic steatosis. At PND10, serum leptin levels were elevated 2.6-4.8-fold in pups exposed to the Mediterranean diet, with a trend for sex-specific effects on body and organ weights. At 10-months, sex-specific increases in organ weight and hormone levels were observed in mice perinatally exposed to Western + BPA or Mediterranean + BPA. These findings suggest lifestage-specific interaction of perinatal exposures to experimental diets and BPA on offspring metabolic health without effects on NAFLD later in life. Importantly, alterations in dam phenotype by diet and BPA exposure appear to impact offspring health trajectory, emphasizing the need to define dam diet in assessing effects of environmental exposures on offspring health.

Integrated Analysis of Liver Transcriptome, miRNA, and Proteome of Chinese Indigenous Breed Ningxiang Pig in Three Developmental Stages Uncovers Significant miRNA-mRNA-Protein Networks in Lipid Metabolism

Liver is an important metabolic organ of mammals. During each transitional period of life, liver metabolism is programmed by a complex molecular regulatory system for multiple physiological functions, many pathways of which are regulated by hormones and cytokines, nuclear receptors, and transcription factors. To gain a comprehensive and unbiased molecular understanding of liver growth and development in Ningxiang pigs, we analyzed the mRNA, microRNA (miRNA), and proteomes of the livers of Ningxiang pigs during lactation, nursery, and fattening periods. A total of 22,411 genes (19,653 known mRNAs and 2758 novel mRNAs), 1122 miRNAs (384 known miRNAs and 738 novel miRNAs), and 1123 unique proteins with medium and high abundance were identified by high-throughput sequencing and mass spectrometry. We show that the differences in transcriptional, post-transcriptional, or protein levels were readily identified by comparing different time periods, providing evidence that functional changes that may occur during liver development are widespread. In addition, we found many overlapping differentially expressed genes (DEGs)/differentially expressed miRNAs (DEMs)/differentially expressed proteins (DEPs) related to glycolipid metabolism in any group comparison. These overlapping DEGs/DEMs/DGPs may play an important role in functional transformation during liver development. Short Time-series Expression Miner (STEM) analysis revealed multiple expression patterns of mRNA, miRNA, and protein in the liver. Furthermore, several diverse key Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including immune defense, glycolipid metabolism, protein transport and uptake, and cell proliferation and development, were identified by combined analysis of DEGs and DGPs. A number of predicted miRNA–mRNA–protein pairs were found and validated by qRT-PCR and parallel reaction monitoring (PRM) assays. The results provide new and important information about the genetic breeding of Ningxiang pigs, which represents a foundation for further understanding the molecular regulatory mechanisms of dynamic development of liver tissue, functional transformation, and lipid metabolism.

Milk Polar Lipids Supplementation to Obese Rats During Pregnancy and Lactation Benefited Skeletal Outcomes of Male Offspring

SCOPE

Dietary intervention to obese dams during pregnancy and lactation period provides avenues for improving metabolic profiles of the offspring. In the current study, the effects of polar lipids-enriched milk fat globule membrane (MFGM-PL) supplementation to obese dams during pregnancy and lactation on the skeletal outcomes of male offspring are investigated.

METHODS AND RESULTS

MFGM-PL is supplemented to obese rats induced by high-fat diet during pregnancy and lactation at a dose of 400 mg kg-1 body weight. Results show that maternal MFGM-PL supplementation significantly ameliorates the stunted skeletal growth of male offspring at weaning. In adulthood offspring, maternal MFGM-PL supplementation protects against high-fat diet (HFD)-induced bone microstructure degeneration and bone marrow adipocyte accumulation. Further investigation shows that maternal supplementation of MFGM-PL significantly ameliorates insulin resistance and increases the mRNA expression of growth hormone releasing hormone (GHRH) in the hypothalamus of HFD offspring. The growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis is subsequently enhanced in MFGM-PL + HFD offspring, contributing to the beneficial skeletal outcomes.

CONCLUSION

The findings suggest that maternal MFGM-PL supplementation of HFD dam during pregnancy and lactation shows desirable effects on fetal skeletal development, with lasting beneficial programming impacts on skeletal outcomes of offspring.

Maternal high-fat diet activates hepatic interleukin-4 in rat male offspring accompanied by increased eosinophil infiltration

Interleukin-4 (IL-4) is activated as an immune response during infection or tissue injury. Epigenetic programming of maternal high-fat (HF) diet has long-term effects in the offspring. In the present study, we investigated the epigenetic regulation of IL-4 in a maternal HF diet model in the liver of adult offspring. Timed-pregnant Sprague-Dawley rats were fed either control (C) or HF diet throughout gestation and lactation. Offspring were placed on a control diet after weaning, generating C/C and HF/C groups. The liver was collected at 12 wk of age, followed by histological and molecular analysis to investigate the maternal programming effects on IL-4 by HF diet. Maternal HF diet significantly induced mRNA expression and protein level of IL-4 and promoted hypomethylation of Il4 compared with the control group. Methylation-selective PCR (MSP) confirmed that maternal HF diet increased RNA polymerase II, acetylation of histone H4, and dimethylation of histone 3 lysine 4 at the +6 kb region of Il4. Moreover, the rat eosinophil marker Siglec-F was increased and colocalized with IL-4 in the liver. In conclusion, our study indicated that IL-4 was increased in liver cells in response to maternal HF diet. This coincides with DNA hypomethylation in combination with chromatin remodeling at the +6 kb region of the 3' downstream region as well as an induced immune cell infiltration, especially eosinophil infiltration, in the liver of offspring.NEW & NOTEWORTHY The present study identifies that maternal high-fat-diet-induced IL-4 upregulation is associated with DNA hypomethylation at the +6 kb region of the 3' downstream region of the gene. Furthermore, our results confirm that the induced Il4 expression in the liver of male offspring corresponds to the induced immune cell, especially eosinophil, infiltration.

Epigenetics of paraoxonases

PURPOSE OF REVIEW

Studies have shown the three-member paraoxonase (PON) multigene family to be involved in the development of a large variety of diseases with an inflammatory component. Environmental factors such as lifestyle-related factors differ widely between populations and it is important to consider that their impacts may be exerted through the epigenetic mechanisms, which connect genes, the environment and disease development and are a potential therapeutic avenue.

RECENT FINDINGS

In the review period, very little was published on epigenetics of PON2 or PON3, mostly on their diagnostic value in cancer by measuring methylation levels of these genes. However, the picture is more promising with PON1. Here, several studies have linked the epigenetic regulation of PON1 to various metabolic processes and particularly to the development of several diseases, including stroke, heart disease, aortic valve stenosis and chronic obstructive pulmonary disease.

SUMMARY

Studies into the epigenetic regulation of the PON family are in their infancy. However, recent studies linking epigenetic regulation of PON1 to disease development will encourage further research and open up the possibility for new potential therapeutic interventions.

Epigenetics, Maternal Diet and Metabolic Programming

Background:

The maternal environment influences embryonic and fetal life. Nutritional deficits or excesses alter the trajectory of fetus/offspring’s development. The concept of “developmental programming” and “developmental origins of health and disease” consists of the idea that maternal diet may remodel the genome and lead to epigenetic changes. These changes are induced during early life, permanently altering the phenotype in the posterior adult stage, favoring the development of metabolic diseases such as obesity, dyslipidemia, hypertension, hyperinsulinemia, and metabolic syndrome. In this review, it is aimed to overview epigenetics, maternal diet and metabolic programming factors and determine which of these might affect future generations.

Scope and Approach:

Nutrients interfere with the epigenome by influencing the supply and use of methyl groups through DNA transmethylation and demethylation mechanisms. They also influence the remodeling of chromatin and arginine or lysine residues at the N-terminal tails of histone, thus altering miRNA expression. Fats, proteins, B vitamins and folates act as important cofactors in methylation processes. The metabolism of carbon in the methyl groups of choline, folic acid and methionine to S-Adenosyl Methionine (SAM), acts as methyl donors to methyl DNA, RNA, and proteins. B-complex vitamins are important since they act as coenzymes during this process.

Key Findings and Conclusion:

Nutrients, during pregnancy, potentially influence susceptibility to diseases in adulthood. Additionally, the deficit or excess of nutrients alter the epigenetic machinery, affecting genes and influencing the genome of the offspring and therefore, predisposing the development of chronic diseases in adults.

Maternal Obesity, Maternal Overnutrition and Fetal Programming: Effects of Epigenetic Mechanisms on the Development of Metabolic Disorders

BACKGROUND

Maternal obesity and maternal overnutrition, can lead to epigenetic alterations during pregnancy and these alterations can influence fetal and neonatal phenotype which increase the risk of metabolic disorders in later stages of life.

OBJECTIVE

The effects of maternal obesity on fetal programming and potential mechanisms of maternal epigenetic regulation of gene expression which have persistent effects on fetal health and development were investigated.

METHODS

Review of the literature was carried out in order to discuss the effects of maternal obesity and epigenetic mechanisms in fetal programming of metabolic disorders. All abstracts and full-text articles were examined and the most relevant articles were included in this review.

RESULTS

Maternal obesity and maternal overnutrition during fetal period has important overall effects on long-term health. Maternal metabolic alterations during early stages of fetal development can lead to permanent changes in organ structures, cell numbers and metabolism. Epigenetic modifications (DNA methylation, histone modifications, microRNAs) play an important role in disease susceptibility in the later stages of human life. Maternal nutrition alter expression of hypothalamic genes which can increase fetal and neonatal energy intake. Epigenetic modifications may affect the increasing rate of obesity and other metabolic disorders worldwide since the impact of these changes can be passed through generations.

CONCLUSION

Weight management before and during pregnancy, together with healthy nutritional intakes may improve the maternal metabolic environment, which can reduce the risks of fetal programming of metabolic diseases. Further evidence from long-term follow-up studies are needed in order to determine the role of maternal obesity on epigenetic mechanisms.

The epigenetic regulation of paraoxonase 1 (PON1) as an important enzyme in HDL function: The missing link between environmental and genetic regulation

BACKGROUND

Paraoxonase 1 (PON1) is an important antiatherogenic and antioxidant enzyme in the circulation that has been associated with adverse health outcomes particularly cardiovascular disease (CVD) and other metabolic disorders. PON1 is a highly promiscuous enzyme and can hydrolyse a large variety of substrates, however, detailed structure/function studies have concluded that the natural substrates for PON1 are lipophilic lactones. The interindividual variability in PON1 activity has been mainly attributed to genetic determinants; however, it appears that the contribution of epigenetics has been ignored as a result of the lack of adequate research.

CONTENT

Epigenetic processes, including the histone modifications in the PON1 gene, the methylation of CpG sites in the promoter region of the PON1 gene and the microRNA modulation of PON1 expression can be responsible for the under researched gap between the environmental and genetic regulation of PON1. Environmental factors, including diet, pollution and lifestyle-related factors widely differ between individuals and populations and can cause large differences in the distribution of PON1 and it is important to note that their effects may be exerted through the epigenetic processes. This review discusses and emphasizes the importance of the epigenetic regulation of PON1 as a less-studied subject to highlight future research landscapes.

SUMMARY

Epigenetic regulation is known as an important contributor to the pathogenesis of human diseases, particularly multifactorial diseases such as CVD, which is life-threatening. Due to the importance of PON1 in the functionality of high-density lipoprotein (HDL) and its association with CVD, further explorations of its epigenetic regulation using advanced methods such as Methyl-Seq may lead to the identification of new epigenetic contributors that in turn may lead to targeted therapies.

Histone Modifications as an Intersection Between Diet and Longevity

Histone modifications are key epigenetic regulators that control chromatin structure and gene transcription, thereby impacting on various important cellular phenotypes. Over the past decade, a growing number of studies have indicated that changes in various histone modifications have a significant influence on the aging process. Furthermore, it has been revealed that the abundance and localization of histone modifications are responsive to various environmental stimuli, such as diet, which can also affect gene expression and lifespan. This supports the notion that histone modifications can serve as a main cellular platform for signal integration. Hence, in this review we focus on the role of histone modifications during aging, report the data indicating that diet affects histone modification levels and explore the idea that histone modifications may function as an intersection through which diet regulates lifespan. A greater understanding of the epigenetic mechanisms that link environmental signals to longevity may provide new strategies for therapeutic intervention in age-related diseases and for promoting healthy aging.

Epigenetic regulation of carnitine palmitoyltransferase 1 (Cpt1a) by high fat diet

Carnitine palmitoyltransferase 1 (Cpt1a) is a rate-limiting enzyme that mediates the transport of fatty acids into the mitochondria for subsequent beta-oxidation. The objective of this study was to uncover how diet mediates the transcriptional regulation of Cpt1a. Pregnant Sprague Dawley rats were exposed to either a high-fat (HF) or low-fat control diet during gestation and lactation. At weaning, male offspring received either a HF or control diet, creating 4 groups: lifelong control diet (C/C; n = 12), perinatal HF diet (HF/C; n = 9), post-weaning HF diet (C/HF; n = 10), and lifelong HF diet (HF/HF; n = 10). Only HF/HF animals had higher hepatic Cpt1a mRNA expression than C/C. Epigenetic analysis revealed reduced DNA methylation (DNAMe) and increased histone 3 lysine 4 dimethylation (H3K4Me2) upstream and within the promoter of Cpt1a in the HF/HF group. This was accompanied by increased peroxisome proliferator activated receptor alpha (PPARα) and CCAAT/enhancer binding protein beta (C/EBPβ) binding directly downstream of the Cpt1a transcription start site within the first intron. Findings were confirmed in rat hepatoma H4IIEC3 cells treated with non-esterified fatty acid (NEFA). After 12 h of NEFA treatment, there was an enrichment of SWI/SNF related matrix associated actin dependent regulator of chromatin subfamily D member 1 (BAF60a or SMARCD1) in the first intron of Cpt1a. We conclude that dietary fat elevates hepatic Cpt1a expression via a highly coordinated transcriptional mechanism involving increased H3K4Me2, reduced DNAMe, and recruitment of C/EBPβ, PPARα, PGC1α, and BAF60a to the gene.

Maternal obesity impairs skeletal development in adult offspring

Intrauterine or early postnatal high-fat diet (HFD) has substantial influences on adult offspring health; however, studies of HFD-induced maternal obesity on regulation of adult offspring bone formation are sparse. Here, we investigated the effects of HFD-induced maternal obesity on both fetal and adult offspring skeletal development. We found that HFD-induced maternal obesity significantly decreased fetal skeletal development, but enhanced fetal osteoblastic cell senescence signaling and significantly increased the expression of inflammatory factors of the senescence-associated secretory phenotype (SASP) in osteo-progenitors. It was found that p300/CBP activation led to H3K27 acetylation to increase the expression of senescence-related genes and PPARγ in embryonic mouse osteogenic calvarial cells from HFD obese dams. These results were recapitulated in human umbilical cord mesenchymal stem cells (UC MSCs) isolated from offspring of pregnant obese and lean mothers following delivery. Regardless of postnatal HFD challenge, adult offspring from HFD obese dams showed significantly suppressed bone formation. Such early involution of bone formation of adult offspring from HFD obese dams may at least in part due to histone acetylation, i.e., epigenetic regulation of genes involved in cell senescence signaling in pre-osteoblasts from prenatal development. These findings indicate fetal pre-osteoblastic cell senescence signaling is epigenetically regulated by maternal obesity to repress bone formation in adult offspring in rodents and suggest that at least some of these effects may also manifest in humans.

Epigenetic Regulation of Centromere Chromatin Stability by Dietary and Environmental Factors

The centromere is a genomic locus required for the segregation of the chromosomes during cell division. This chromosomal region together with pericentromeres has been found to be susceptible to damage, and thus the perturbation of the centromere could lead to the development of aneuploidic events. Metabolic abnormalities that underlie the generation of cancer include inflammation, oxidative stress, cell cycle deregulation, and numerous others. The micronucleus assay, an early clinical marker of cancer, has been shown to provide a reliable measure of genotoxic damage that may signal cancer initiation. In the current review, we will discuss the events that lead to micronucleus formation and centromeric and pericentromeric chromatin instability, as well transcripts emanating from these regions, which were previously thought to be inactive. Studies were selected in PubMed if they reported the effects of nutritional status (macro- and micronutrients) or environmental toxicant exposure on micronucleus frequency or any other chromosomal abnormality in humans, animals, or cell models. Mounting evidence from epidemiologic, environmental, and nutritional studies provides a novel perspective on the origination of aneuploidic events. Although substantial evidence exists describing the role that nutritional status and environmental toxicants have on the generation of micronuclei and other nuclear aberrations, limited information is available to describe the importance of macro- and micronutrients on centromeric and pericentromeric chromatin stability. Moving forward, studies that specifically address the direct link between nutritional status, excess, or deficiency and the epigenetic regulation of the centromere will provide much needed insight into the nutritional and environmental regulation of this chromosomal region and the initiation of aneuploidy.

Connecting the Dots Between Fatty Acids, Mitochondrial Function, and DNA Methylation in Atherosclerosis

PURPOSE OF REVIEW

The quest for factors and mechanisms responsible for aberrant DNA methylation in human disease-including atherosclerosis-is a promising area of research. This review focuses on the role of fatty acids (FAs) as modulators of DNA methylation-in particular the role of mitochondrial beta-oxidation in FA-induced changes in DNA methylation during the progression of atherosclerosis.

RECENT FINDINGS

Recent publications have advanced the knowledge in all areas touched by this review: the causal role of lipids in shaping the DNA methylome, the associations between chronic degenerative disease and mitochondrial function, the lipid composition of the atheroma, and the relevance of DNA hypermethylation in atherosclerosis. Evidence is beginning to emerge, linking the dynamics of FA type abundance, mitochondrial function, and DNA methylation in the atheroma and systemically. In particular, this review highlights mitochondrial beta-oxidation as an important regulator of DNA methylation in metabolic disease. Despite the many questions still unanswered, this area of research promises to identify mechanisms and molecular factors that establish a pathological gene expression pattern in atherosclerosis.

Persistent DNA methylation changes associated with prenatal mercury exposure and cognitive performance during childhood

Prenatal exposure to mercury, a known neurotoxic metal, is associated with lower cognitive performance during childhood. Disruption of fetal epigenetic programming could explain mercury’s neurodevelopmental effects. We screened for epigenome-wide methylation differences associated with maternal prenatal blood mercury levels in 321 cord blood DNA samples and examined the persistence of these alterations during early (n = 75; 2.9–4.9 years) and mid-childhood (n = 291; 6.7–10.5 years). Among males, prenatal mercury levels were associated with lower regional cord blood DNA methylation at the Paraoxonase 1 gene (PON1) that persisted in early childhood and was attenuated in mid-childhood blood. Cord blood methylation at the PON1 locus predicted lower cognitive test scores measured during early childhood. Methylation at the PON1 locus was associated with PON1 expression in an independent set of cord blood samples. The observed persistent epigenetic disruption of the PON1 gene may modulate mercury toxicity in humans and might serve as a biomarker of exposure and disease susceptibility.

Traffic-derived particulate matter exposure and histone H3 modification: A repeated measures study

BACKGROUND

Airborne particulate matter (PM) may induce epigenetic changes that potentially lead to chronic diseases. Histone modifications regulate gene expression by influencing chromatin structure that can change gene expression status. We evaluated whether traffic-derived PM exposure is associated with four types of environmentally inducible global histone H3 modifications.

METHODS

The Beijing Truck Driver Air Pollution Study included 60 truck drivers and 60 office workers examined twice, 1-2 weeks apart, for ambient PM₁₀ (both day-of and 14-day average exposures), personal PM_2.5, black carbon (BC), and elemental components (potassium, sulfur, iron, silicon, aluminum, zinc, calcium, and titanium). For both PM₁₀ measures, we obtained hourly ambient PM₁₀ data for the study period from the Beijing Municipal Environmental Bureau's 27 representatively distributed monitoring stations. We then calculated a 24h average for each examination day and a moving average of ambient PM₁₀ measured in the 14 days prior to each examination. Examinations measured global levels of H3 lysine 9 acetylation (H3K9ac), H3 lysine 9 tri-methylation (H3K9me3), H3 lysine 27 tri-methylation (H3K27me3), and H3 lysine 36 tri-methylation (H3K36me3) in blood leukocytes collected after work. We used adjusted linear mixed-effect models to examine percent changes in histone modifications per each μg/m³ increase in PM exposure.

RESULTS

In all participants each μg/m³ increase in 14-day average ambient PM₁₀ exposure was associated with lower H3K27me3 (β=-1.1%, 95% CI: -1.6, -0.6) and H3K36me3 levels (β=-0.8%, 95% CI: -1.4, -0.1). Occupation-stratified analyses showed associations between BC and both H3K9ac and H3K36me3 that were stronger in office workers (β=4.6%, 95% CI: 0.9, 8.4; and β=4.1%, 95% CI: 1.3; 7.0 respectively) than in truck drivers (β=0.1%, 95% CI: -1.3, 1.5; and β=0.9%, 95% CI: -0.9, 2.7, respectively; both p_interaction <0.05). Sex-stratified analyses showed associations between examination-day PM₁₀ and H3K9ac, and between BC and H3K9me3, were stronger in women (β=10.7%, 95% CI: 5.4, 16.2; and β=7.5%, 95% CI: 1.2, 14.2, respectively) than in men (β=1.4%, 95% CI: -0.9, 3.7; and β=0.9%, 95% CI: -0.9, 2.7, respectively; both p_interaction <0.05). We observed no associations between personal PM_2.5 or elemental components and histone modifications.

CONCLUSIONS

Our results suggest a possible role of global histone H3 modifications in effects of traffic-derived PM exposures, particularly BC exposure. Future studies should assess the roles of these modifications in human diseases and as potential mediators of air pollution-induced disease, in particular BC exposure.

Developmental origins of NAFLD: a womb with a clue

Changes in the maternal environment leading to an altered intrauterine milieu can result in subtle insults to the fetus, promoting increased lifetime disease risk and/or disease acceleration in childhood and later in life. Particularly worrisome is that the prevalence of NAFLD is rapidly increasing among children and adults, and is being diagnosed at increasingly younger ages, pointing towards an early-life origin. A wealth of evidence, in humans and non-human primates, suggests that maternal nutrition affects the placenta and fetal tissues, leading to persistent changes in hepatic metabolism, mitochondrial function, the intestinal microbiota, liver macrophage activation and susceptibility to NASH postnatally. Deleterious exposures in utero include fetal hypoxia, increased nutrient supply, inflammation and altered gut microbiota that might produce metabolic clues, including fatty acids, metabolites, endotoxins, bile acids and cytokines, which prime the infant liver for NAFLD in a persistent manner and increase susceptibility to NASH. Mechanistic links to early disease pathways might involve shifts in lipid metabolism, mitochondrial dysfunction, pioneering gut microorganisms, macrophage programming and epigenetic changes that alter the liver microenvironment, favouring liver injury. In this Review, we discuss how maternal, fetal, neonatal and infant exposures provide developmental clues and mechanisms to help explain NAFLD acceleration and increased disease prevalence. Mechanisms identified in clinical and preclinical models suggest important opportunities for prevention and intervention that could slow down the growing epidemic of NAFLD in the next generation.

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.

Experimental Models of Maternal Obesity and Neuroendocrine Programming of Metabolic Disorders in Offspring

Evidence from epidemiological, clinical, and experimental studies have clearly shown that disease risk in later life is increased following a poor early life environment, a process preferentially termed developmental programming. In particular, this work clearly highlights the importance of the nutritional environment during early development with alterations in maternal nutrition, including both under- and overnutrition, increasing the risk for a range of cardiometabolic and neurobehavioral disorders in adult offspring characterized by both adipokine resistance and obesity. Although the mechanistic basis for such developmental programming is not yet fully defined, a common feature derived from experimental animal models is that of alterations in the wiring of the neuroendocrine pathways that control energy balance and appetite regulation during early stages of developmental plasticity. The adipokine leptin has also received significant attention with clear experimental evidence that normal regulation of leptin levels during the early life period is critical for the normal development of tissues and related signaling pathways that are involved in metabolic and cardiovascular homeostasis. There is also increasing evidence that alterations in the epigenome and other underlying mechanisms including an altered gut-brain axis may contribute to lasting cardiometabolic dysfunction in offspring. Ongoing studies that further define the mechanisms between these associations will allow for identification of early risk markers and implementation of strategies around interventions that will have obvious beneficial implications in breaking a programmed transgenerational cycle of metabolic disorders.

Maternal Obesity Programs Senescence Signaling and Glucose Metabolism in Osteo-Progenitors From Rat and Human

Nutritional status during intrauterine and early postnatal life impacts the risk of chronic diseases, presumably via epigenetic mechanisms. However, evidence on the impact of gestational events on regulation of embryonic bone cell fate is sparse. We investigated the effects of maternal obesity on fetal osteoblast development in both rodents and humans. Female rats were fed control or an obesogenic high-fat diet (HFD) for 12 weeks and mated with male rats fed control diets, and respective maternal diets were continued during pregnancy. Embryonic rat osteogenic calvarial cells (EOCCs) were taken from gestational day 18.5 fetuses from control and HFD dams. EOCCs from HFD obese dams showed increases in p53/p21-mediated cell senescence signaling but decreased glucose metabolism. Decreased aerobic glycolysis in HFD-EOCCs was associated with decreased osteoblastic cell differentiation and proliferation. Umbilical cord human mesenchymal stem cells (MSCs) from 24 pregnant women (12 obese and 12 lean) along with placentas were collected upon delivery. The umbilical cord MSCs of obese mothers displayed less potential toward osteoblastogenesis and more towards adipogenesis. Human MSCs and placenta from obese mothers also exhibited increased cell senescence signaling, whereas MSCs showed decreased glucose metabolism and insulin resistance. Finally, we showed that overexpression of p53 linked increased cell senescence signaling and decreased glucose metabolism in fetal osteo-progenitors from obese rats and humans. These findings suggest programming of fetal preosteoblastic cell senescence signaling and glucose metabolism by maternal obesity.

Transgenerational effects of maternal diet on metabolic and reproductive ageing

The early-life environment, in particular maternal diet during pregnancy, influences a wide range of organs and systems in adult offspring. Mounting evidence suggests that developmental programming can also influence health and disease in grand-offspring. Transgenerational effects can be defined as those persisting into an F2 generation, where the F0 mother experiences suboptimal diet during her pregnancy. In this review, we critically examine evidence for transgenerational developmental programming effects in human populations, focusing on metabolic and reproductive outcomes. We discuss evidence from historical cohorts suggesting that grandchildren of women exposed to famine and other dietary alterations during pregnancy may experience increased rates of later health complications than their control counterparts. The methodological difficulties with transgenerational studies in human cohorts are explored. In particular, the problems with assessing reproductive outcomes in human populations are discussed. In light of the relative paucity of evidence available from human cohorts, we consider key insights from transgenerational experimental animal models of developmental programming by maternal diet; data are drawn from a range of rodent models, as well as the guinea-pig and the sheep. The evidence for different potential mechanisms of transgenerational inheritance or re-propagation of developmental programming effects is evaluated. Transgenerational effects could be transmitted through methylation of the gametes via the paternal and maternal lineage, as well as other possible mechanisms via the maternal lineage. Finally, future directions for exploring these underlying mechanisms further are proposed, including utilizing large, well-characterized, prospective pregnancy cohorts that include biobanks, which have been established in various populations during the last few decades.

Lifestyle, pregnancy and epigenetic effects

Rapidly growing evidences link maternal lifestyle and prenatal factors with serious health consequences and diseases later in life. Extensive epidemiological studies have identified a number of factors such as diet, stress, gestational diabetes, exposure to tobacco and alcohol during gestation as influencing normal fetal development. In light of recent discoveries, epigenetic mechanisms such as alteration of DNA methylation, chromatin modifications and modulation of gene expression during gestation are believed to possibly account for various types of plasticity such as neural tube defects, autism spectrum disorder, congenital heart defects, oral clefts, allergies and cancer. The purpose of this article is to review a number of published studies to fill the gap in our understanding of how maternal lifestyle and intrauterine environment influence molecular modifications in the offspring, with an emphasis on epigenetic alterations. To support these associations, we highlighted laboratory studies of rodents and epidemiological studies of human based on sampling population cohorts.

Developmental Programming of Nonalcoholic Fatty Liver Disease: The Effect of Early Life Nutrition on Susceptibility and Disease Severity in Later Life

Nonalcoholic fatty liver disease (NAFLD) is fast becoming the most common liver disease globally and parallels rising obesity rates. The developmental origins of health and disease hypothesis have linked alterations in the early life environment to an increased risk of metabolic disorders in later life. Altered early life nutrition, in addition to increasing risk for the development of obesity, type 2 diabetes, and cardiovascular disease in offspring, is now associated with an increased risk for the development of NAFLD. This review summarizes emerging research on the developmental programming of NAFLD by both maternal obesity and undernutrition with a particular focus on the possible mechanisms underlying the development of hepatic dysfunction and potential strategies for intervention.

Developmental bisphenol A (BPA) exposure leads to sex-specific modification of hepatic gene expression and epigenome at birth that may exacerbate high-fat diet-induced hepatic steatosis

Developmental bisphenol A (BPA) exposure increases adulthood hepatic steatosis with reduced mitochondrial function. To investigate the potential epigenetic mechanisms behind developmental BPA-induced hepatic steatosis, pregnant Sprague-Dawley rats were dosed with vehicle (oil) or BPA (100μg/kg/day) from gestational day 6 until postnatal day (PND) 21. After weaning, offspring were either challenged with a high-fat (HF; 45% fat) or remained on a control (C) diet until PND110. From PND60 to 90, both BPA and HF diet increased the fat/lean ratio in males only, and the combination of BPA and HF diet appeared to cause the highest ratio. On PND110, Oil-HF, BPA-C, and BPA-HF males had higher hepatic lipid accumulation than Oil-C, with microvesicular steatosis being marked in the BPA-HF group. Furthermore, on PND1, BPA increased and modified hepatic triglyceride (TG) and free fatty acid (FFA) compositions in males only. In PND1 males, BPA increased hepatic expression of FFA uptake gene Fat/Cd36, and decreased the expression of TG synthesis- and β-oxidation-related genes (Dgat, Agpat6, Cebpα, Cebpβ, Pck1, Acox1, Cpt1a, Cybb). BPA altered DNA methylation and histone marks (H3Ac, H4Ac, H3Me2K4, H3Me3K36), and decreased the binding of several transcription factors (Pol II, C/EBPβ, SREBP1) within the male Cpt1a gene, the key β-oxidation enzyme. In PND1 females, BPA only increased the expression of genes involved in FFA uptake and TG synthesis (Lpl, Fasn, and Dgat). These data suggest that developmental BPA exposure alters and reprograms hepatic β-oxidation capacity in males, potentially through the epigenetic regulation of genes, and further alters the response to a HF diet.

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.

Epigenetics and nutritional environmental signals

All terrestrial life is influenced by multi-directional flows of information about its environment, enabling malleable phenotypic change through signals, chemical processes, or various forms of energy that facilitate acclimatization. Billions of biological co-inhabitants of the earth, including all plants and animals, collectively make up a genetic/epigenetic ecosystem by which adaptation/survival (inputs and outputs) are highly interdependent on one another. As an ecosystem, the solar system, rotation of the planets, changes in sunlight, and gravitational pull influence cyclic epigenetic transitions and chromatin remodeling that constitute biological circadian rhythms controlling senescence. In humans, adverse environmental conditions such as poverty, stress, alcohol, malnutrition, exposure to pollutants generated from industrialization, man-made chemicals, and use of synthetic drugs can lead to maladaptive epigenetic-related illnesses with disease-specific genes being atypically activated or silenced. Nutrition and dietary practices are one of the largest facets in epigenetic-related metabolism, where specific "epi-nutrients" can stabilize the genome, given established roles in DNA methylation, histone modification, and chromatin remodeling. Moreover, food-based "epi-bioactive" constituents may reverse maladaptive epigenetic patterns, not only prior to conception and during fetal/early postnatal development but also through adulthood. In summary, in contrast to a static genomic DNA structure, epigenetic changes are potentially reversible, raising the hope for therapeutic and/or dietary interventions that can reverse deleterious epigenetic programing as a means to prevent or treat major illnesses.