Maternal diet supplemented with methyl-donors protects against atherosclerosis in F1 ApoE(-/-) mice

Metabolic syndrome: Nutri-epigenetic cause or consequence?

Metabolic syndrome is a cluster of conditions that results from the interplay of genetic and environmental factors, which increase the comorbidity risk of obesity, hyperglycemia, dyslipidemia, arterial hypertension, stroke, and cardiovascular disease. In this article, we review various high-impact studies which link epigenetics with metabolic syndrome by comparing each study population, methylation effects, and strengths and weaknesses of each research. We also discuss world statistical data on metabolic syndrome incidence in developing countries where the metabolic syndrome is common condition that has significant public health implications.

The impact of early-life environment on absence epilepsy and neuropsychiatric comorbidities

This review discusses the long-term effects of early-life environment on epileptogenesis, epilepsy, and neuropsychiatric comorbidities with an emphasis on the absence epilepsy. The WAG/Rij rat strain is a well-validated genetic model of absence epilepsy with mild depression-like (dysthymia) comorbidity. Although pathologic phenotype in WAG/Rij rats is genetically determined, convincing evidence presented in this review suggests that the absence epilepsy and depression-like comorbidity in WAG/Rij rats may be governed by early-life events, such as prenatal drug exposure, early-life stress, neonatal maternal separation, neonatal handling, maternal care, environmental enrichment, neonatal sensory impairments, neonatal tactile stimulation, and maternal diet. The data, as presented here, indicate that some early environmental events can promote and accelerate the development of absence seizures and their neuropsychiatric comorbidities, while others may exert anti-epileptogenic and disease-modifying effects. The early environment can lead to phenotypic alterations in offspring due to epigenetic modifications of gene expression, which may have maladaptive consequences or represent a therapeutic value. Targeting DNA methylation with a maternal methyl-enriched diet during the perinatal period appears to be a new preventive epigenetic anti-absence therapy. A number of caveats related to the maternal methyl-enriched diet and prospects for future research are discussed.

Pharmacological inhibition of EZH2 by GSK126 decreases atherosclerosis by modulating foam cell formation and monocyte adhesion in apolipoprotein E-deficient mice

Histone modifications play an important role in the occurrence and development of atherosclerosis in human and atherosclerosis-prone mice. Histone methylation in macrophages, monocytes and endothelial cells markedly influence the progression of atherosclerosis. However, it remains unclear whether treatment with a histone methyltransferase enhancer of zeste homolog 2 (EZH2) inhibitor may suppress atherosclerosis. The present study aimed to determine the effects of the EZH2 inhibitor, GSK126, on the suppression and regression of atherosclerosis in apolipoprotein E-deficient mouse models. In vitro, it was found that pharmacological inhibition of EZH2 by GSK126 markedly reduced lipid transportation and monocyte adhesion during atherogenesis, predominantly through increasing the expression levels of ATP-binding cassette transporter A1 and suppressing vascular cell adhesion molecule 1 in human THP-1 cells. In vivo, it was found that atherosclerotic plaques in GSK126-treated mice were significantly decreased when comparing with the vehicle-treated animals. These results indicated that the GSK126 has the ability to attenuate the progression of atherosclerosis by reducing macrophage foam cell formation and monocyte adhesion in cell and mouse models. In conclusion, the present study provided new insights into the molecular mechanism behind the action of GSK126 and suggested its therapeutic potential for the treatment of atherosclerosis.

Nutritional Supplements During Gestation and Autism Spectrum Disorder: What Do We Really Know and How Far Have We Gone?

Nutritional interventions are gaining remarkable attention as complementary management options for autism. Our aim is to provide literature data about the impact of the administration of dietary supplements during pregnancy on the risk of autism spectrum disorder in the offspring. A comprehensive search was undertaken by 2 reviewers independently using PubMed as the medical database source. Prospective clinical and experimental studies were considered and no year-of-publication restriction was placed. We were able to identify 4 basic (conducted in rodents) and 3 clinical research papers fulfilling our selection criteria. Supplements studied included folic acid, iron, multivitamins, choline, vitamin D, and docosahexaenoic acid. Choline and folic acid had a significant impact on the expression of autism-related genes. However, from a clinical point of view, prenatal folate administration did not reduce the risk of autism. Similarly, iron had no significant impact, while the use of multivitamins in moderate frequency had a protective effect. The use of vitamin D and docosahexaenoic acid during gestation decreased the incidence of autism in animal models. In conclusion, available data are controversial and cannot change current routine practice. More large-scale prospective studies are needed to identify the real effect of nutritional supplements and also optimize their administration.Key teaching pointsMultivitamins use during pregnancy can exert a protective effect on the risk of autism, although depending on the frequency of use. Nevertheless, prenatal iron and folate were not shown to have any significant impact.Research based on animal models showed that choline and folic acid can have a significant impact on the expression of autism-related genes in a sex-specific manner.Furthermore, the use of vitamin D and docosahexaenoic acid during gestation seem to decrease the incidence of autism in animal offspring.In the future, more clinical, large-scale prospective and methodologically homogenous clinical studies are needed to further investigate the effect of the periconceptional use of nutritional supplements on autism risk.

Outbreak of Murine Infection with Clostridium difficile Associated with the Administration of a Pre- and Perinatal Methyl Donor Diet

Between October 2016 and June 2017, a C57BL/6J mouse colony that was undergoing a pre- and perinatal methyl donor supplementation diet intervention to study the impact of parental nutrition on offspring susceptibility to disease was found to suffer from an epizootic of unexpected deaths. Necropsy revealed the presence of severe colitis, and further investigation linked these outbreak deaths to a Clostridium difficile strain of ribotype 027 that we term 16N203. C. difficile infection (CDI) is associated with antibiotic use in humans. Current murine models of CDI rely on antibiotic pretreatment to establish clinical phenotypes. In this report, the C. difficile outbreak occurs in F1 mice linked to alterations in the parental diet. The diagnosis of CDI in the affected mice was confirmed by cecal/colonic histopathology, the presence of C. difficile bacteria in fecal/colonic culture, and detection of C. difficile toxins. F1 mice from parents fed the methyl supplementation diet also had significantly reduced survival (P < 0.0001) compared with F1 mice from parents fed the control diet. When we tested the 16N203 outbreak strain in an established mouse model of antibiotic-induced CDI, we confirmed that this strain is pathogenic. Our serendipitous observations from this spontaneous outbreak of C. difficile in association with a pre- and perinatal methyl donor diet suggest the important role that diet may play in host defense and CDI risk factors.IMPORTANCEClostridium difficile infection (CDI) has become the leading cause of infectious diarrhea in hospitals worldwide, owing its preeminence to the emergence of hyperendemic strains, such as ribotype 027 (RT027). A major CDI risk factor is antibiotic exposure, which alters gut microbiota, resulting in the loss of colonization resistance. Current murine models of CDI also depend on pretreatment of animals with antibiotics to establish disease. The outbreak that we report here is unique in that the CDI occurred in mice with no antibiotic exposure and is associated with a pre- and perinatal methyl supplementation donor diet intervention study. Our investigation subsequently reveals that the outbreak strain that we term 16N203 is an RT027 strain, and this isolated strain is also pathogenic in an established murine model of CDI (with antibiotics). Our report of this spontaneous outbreak offers additional insight into the importance of environmental factors, such as diet, and CDI susceptibility.

Offspring neuroimmune consequences of maternal malnutrition: Potential mechanism for behavioral impairments that underlie metabolic and neurodevelopmental disorders

Maternal malnutrition significantly increases offspring risk for both metabolic and neurodevelopmental disorders. Animal models of maternal malnutrition have identified behavioral changes in the adult offspring related to executive function and reward processing. Together, these changes in executive and reward-based behaviors likely contribute to the etiology of both metabolic and neurodevelopmental disorders associated with maternal malnutrition. Concomitant with the behavioral effects, maternal malnutrition alters offspring expression of reward-related molecules and inflammatory signals in brain pathways that control executive function and reward. Neuroimmune pathways and microglial interactions in these specific brain circuits, either in early development or later in adulthood, could directly contribute to the maternal malnutrition-induced behavioral phenotypes. Understanding these mechanisms will help advance treatment strategies for metabolic and neurodevelopmental disorders, especially noninvasive dietary supplementation interventions.

Perinatal Hypercholesterolemia Exacerbates Atherosclerosis Lesions in Offspring by Altering Metabolism of Trimethylamine-N-Oxide and Bile Acids

OBJECTIVE

Experimental studies suggest that maternal hypercholesterolemia may be relevant for the early onset of cardiovascular disease in offspring. We investigated the effect of perinatal hypercholesterolemia on the atherosclerosis development in the offspring of apolipoprotein E-deficient mice and the underlying mechanism.

APPROACH AND RESULTS

Atherosclerosis and related parameters were studied in adult male or female apolipoprotein E-deficient mice offspring from either normocholesterolemic or hypercholesterolemic mothers and normocholesterolemic fathers. Female born to hypercholesterolemic mothers had more aortic root lesions than female born to normocholesterolemic mothers. Lesions in whole aorta did not differ between groups. Higher trimethylamine-N-oxide levels and Fmo3 hepatic gene expression were higher in female born to hypercholesterolemic mothers offspring compared with female born to normocholesterolemic mothers and male. Trimethylamine-N-oxide levels were correlated with the size of atherosclerotic root lesions. Levels of hepatic cholesterol and gallbladder bile acid were greater in male born to hypercholesterolemic mothers compared with male born to normocholesterolemic mothers. At 18 weeks of age, female born to hypercholesterolemic mothers showed lower hepatic Scarb1 and Cyp7a1 but higher Nr1h4 gene expression compared with female born to normocholesterolemic mothers. Male born to hypercholesterolemic mothers showed an increase in Scarb1 and Ldlr gene expression compared with male born to normocholesterolemic mothers. At 25 weeks of age, female born to hypercholesterolemic mothers had lower Cyp7a1 gene expression compared with female born to normocholesterolemic mothers. DNA methylation of Fmo3, Scarb1, and Ldlr promoter regions was slightly modified and may explain the mRNA expression modulation.

CONCLUSIONS

Our findings suggest that maternal hypercholesterolemia may exacerbate the development of atherosclerosis in female offspring by affecting metabolism of trimethylamine-N-oxide and bile acids. These data could be explained by epigenetic alterations.

Histone Methyltransferase Enhancer of Zeste Homolog 2-Mediated ABCA1 Promoter DNA Methylation Contributes to the Progression of Atherosclerosis

ATP-binding cassette transporter A1 (ABCA1) plays a critical role in maintaining cellular cholesterol homeostasis. The purpose of this study is to identify the molecular mechanism(s) underlying ABCA1 epigenetic modification and determine its potential impact on ABCA1 expression in macrophage-derived foam cell formation and atherosclerosis development. DNA methylation induced foam cell formation from macrophages and promoted atherosclerosis in apolipoprotein E-deficient (apoE^−/−) mice. Bioinformatics analyses revealed a large CpG island (CGI) located in the promoter region of ABCA1. Histone methyltransferase enhancer of zeste homolog 2 (EZH2) downregulated ABCA1 mRNA and protein expression in THP-1 and RAW264.7 macrophage-derived foam cells. Pharmacological inhibition of DNA methyltransferase 1 (DNMT1) with 5-Aza-dC or knockdown of DNMT1 prevented the downregulation of macrophage ABCA1 expression, suggesting a role of DNA methylation in ABCA1 expression. Polycomb protein EZH2 induced DNMT1 expression and methyl-CpG-binding protein-2 (MeCP2) recruitment, and stimulated the binding of DNMT1 and MeCP2 to ABCA1 promoter, thereby promoting ABCA1 gene DNA methylation and atherosclerosis. Knockdown of DNMT1 inhibited EZH2-induced downregulation of ABCA1 in macrophages. Conversely, EZH2 overexpression stimulated DNMT1-induced ABCA1 gene promoter methylation and atherosclerosis. EZH2-induced downregulation of ABCA1 gene expression promotes foam cell formation and the development of atherosclerosis by DNA methylation of ABCA1 gene promoter.

Epigenetic and SP1-mediated regulation is involved in the repression of galactokinase 1 gene in the liver of neonatal piglets born to betaine-supplemented sows

PURPOSE

In this study, we sought to investigate the effects of maternal betaine supplementation on the expression and regulation of GALK1 gene in the liver of neonatal piglets.

METHODS

Sixteen sows of two groups were fed control or betaine-supplemented diets (3 g/kg), respectively, throughout the pregnancy. Newborn piglets were individually weighed immediately after birth, and one male piglet close to mean body weight from the same litter was selected and killed before suckling. Serum samples of newborn piglets were analyzed for biochemical indexes, hormone and amino acid levels. Liver samples were analyzed for GALK1 expression by real-time PCR and western blotting, while GALK1 regulational mechanism was analyzed by methylated DNA immunoprecipitation, chromatin immunoprecipitation and microRNAs expression.

RESULTS

Betaine-exposed neonatal piglets had lower serum concentration of galactose, which was associated with significantly down-regulated hepatic GALK1 expression. The repression of GALK1 mRNA expression was associated with DNA hypermethylation and more enriched repression histone mark H3K27me3 on its promoter. Binding sites of SP1, GR and STAT3 were predicted on GALK1 promoter, and decreased SP1 protein content and lower SP1 binding to GALK1 promoter were detected in the liver of betaine-exposed piglets. Furthermore, the expression of miRNA-149 targeting GALK1 was up-regulated in the liver of betaine-exposed piglets, along with elevated miRNAs-processing enzymes Dicer and Ago2.

CONCLUSIONS

Our results suggest that maternal dietary betaine supplementation during gestation suppresses GALK1 expression in the liver of neonatal piglets, which involves complex gene regulation mechanisms including DNA methylation, histone modification, miRNAs expression and SP1-mediated transcriptional modulation.

Methyl donor supplementation in rats reverses the deleterious effect of maternal separation on depression-like behaviour

Adverse early life events are associated with altered stress responsiveness and metabolic disturbances in the adult life. Dietary methyl donor supplementation could be able to reverse the negative effects of maternal separation by affecting DNA methylation in the brain. In this study, maternal separation during lactation reduced body weight gain in the female adult offspring without affecting food intake, and altered total and HDL-cholesterol levels. Also, maternal separation induced a cognitive deficit as measured by NORT and an increase in the immobility time in the Porsolt forced swimming test, consistent with increased depression-like behaviour. An 18-week dietary supplementation with methyl donors (choline, betaine, folate and vitamin B12) from postnatal day 60 also reduced body weight without affecting food intake. Some of the deleterious effects induced by maternal separation, such as the abnormal levels of total and HDL-cholesterol, but especially the depression-like behaviour as measured by the Porsolt test, were reversed by methyl donor supplementation. Also, the administration of methyl donors increased total DNA methylation (measured by immunohistochemistry) and affected the expression of insulin receptor in the hippocampus of the adult offspring. However, no changes were observed in the DNA methylation status of insulin receptor and corticotropin-releasing hormone (CRH) promoter regions in the hypothalamus. In summary, methyl donor supplementation reversed some of the deleterious effects of an early life-induced model of depression in rats and altered the DNA methylation profile in the brain.

Effect of in ovo feeding of folic acid on the folate metabolism, immune function and epigenetic modification of immune effector molecules of broiler

This study was conducted to investigate the effect of in ovo feeding (IOF) of folic acid on the folate metabolism, immune function and the involved epigenetic modification of broilers. A total of 400 (Cobb) hatching eggs were randomly divided into four groups (0, 50, 100 and 150 µg injection of folic acid at embryonic age 11 d), and chicks hatched from each treatment were randomly divided into six replicates with 12 broilers/replicate after incubation. The results indicated that, in ovo, 100- and 150-µg folic acid injections improved the hatchability. The average daily gain and feed conversion ratio increased in the 150-µg group during the late growth stage. Simultaneously, in the 100- and 150-µg groups, an increase was observed in hepatic folate content and the expression of methylenetetrahydrofolate reductase (d1 and 42) and methionine synthase reductase (d21). IgG and IgM concentrations, as well as plasma lysozyme activity of broilers, showed a marked increase along with increasing folic acid levels. The splenic expression levels of IL-2 and IL-4 were up-regulated, whereas that of IL-6 was down-regulated, in the 100- and 150-µg folic acid treatment groups. In addition, histone methylation in IL-2 and IL-4 promoters exhibited an enrichment of H3K4m2 but a loss of H3K9me2 with the increased amount of folic acid additive. In contrast, a decrease in H3K4m2 and an increase in H3K9me2 were observed in the IL-6 promoter in folic acid treatments. Furthermore, in ovo, the 150-µg folic acid injection improved the chromatin tightness of the IL-2 and IL-4 promoter regions. Our findings suggest that IOF of 150 µg of folic acid can improve the growth performance and folate metabolism of broilers, and enhance the relationship between immune function and epigenetic regulation of immune genes, which are involved with the alterations in chromatin conformation and histone methylation in their promoters.

Potential of epigenetic therapies in non-cancerous conditions

There has been an explosion of knowledge in the epigenetics field in the past 20 years. The first epigenetic therapies have arrived in the clinic for cancer treatments. In contrast, much of the promise of epigenetic therapies for non-cancerous conditions remains in the laboratories. The current review will focus on the recent progress that has been made in understanding the pathogenic role of epigenetics in immune and inflammatory conditions, and how the knowledge may provide much needed new therapeutic targets for many autoimmune diseases. Dietary factors are increasingly recognized as potential modifiers of epigenetic marks that can influence health and diseases across generations. The current epigenomics revolution will almost certainly complement the explosion of personal genetics medicine to help guide treatment decisions and disease risk stratification.

Maternal methyl supplemented diets and effects on offspring health

Women seeking to become pregnant and pregnant women are currently advised to consume high amounts of folic acid and other methyl donors to prevent neural tube defects in their offspring. These diets can alter methylation patterns of several biomolecules, including nucleic acids, and histone proteins. Limited animal model data suggests that developmental exposure to these maternal methyl supplemented (MS) diets leads to beneficial epimutations. However, other rodent and humans studies have yielded opposing findings with such diets leading to promiscuous epimutations that are likely associated with negative health outcomes. Conflict exists to whether these maternal diets are preventative or exacerbate the risk for Autism Spectrum Disorders (ASD) in children. This review will discuss the findings to date on the potential beneficial and aversive effects of maternal MS diets. We will also consider how other factors might influence the effects of MS diets. Current data suggest that there is cause for concern as maternal MS diets may lead to epimutations that underpin various diseases, including neurobehavioral disorders. Further studies are needed to explore the comprehensive effects maternal MS diets have on the offspring epigenome and subsequent overall health.

Unraveling the DNA methylome of atherosclerosis

PURPOSE OF REVIEW

Epigenetic mechanisms of transcriptional regulation in atherosclerosis have gained an increasing interest in recent years. We focus on the relevance of DNA methylation, a well characterized epigenetic modification of the genome, as a biomarker and underlying mechanism of atherosclerosis.

RECENT FINDINGS

A growing number of loci have been identified, which are good candidate biomarkers for atherosclerosis and provide novel insights into the molecular changes taking place in the diseased vessel. Understanding the global change in DNA methylation during atherosclerosis remains a challenge. Novel unfolding research avenues include the interplay between genetic variants and DNA methylation patterns, and the role of long noncoding RNAs as epigenetic regulators.

SUMMARY

Epigenetics continues to represent a promising area of research in atherosclerosis. The full exploitation of cutting edge epigenomics will be decisive to define whether epigenetics will contribute to lower the burden of cardiovascular diseases.

Changes in adipose tissue macrophages and T cells during aging

Adipose tissue historically was believed to be an inert tissue, functioning primarily in the storage of energy and thermal homeostasis. However, recent discoveries point toward a critical role for adipocytes in endocrine function as well as immune regulation. Excess body fat, accumulated through aging and/or a calorie-rich diet, is associated with many chronic metabolic and inflammatory diseases. Within the stromal vascular fraction of adipose tissue, macrophages and T cells accumulate with increasing tissue mass, secreting pro- or anti-inflammatory cytokines. In this review we discuss the current understanding of immune cell function in both diet-induced and age-related obesity. In both models of obesity, the classically activated, pro-inflammatory (M1) subtype takes precedence over the alternatively activated, anti-inflammatory (M2) macrophages, causing tissue necrosis and releasing pro-inflammatory cytokines like interleukin-6. Other distinct adipose tissue macrophage subtypes have been identified by surface marker expression and their functions characterized. Adipose tissue T cell recruitment to adipose tissue is also different between aging- and diet-induced obesity. Under both conditions, T cells exhibit restricted T-cell receptor diversity and produce higher levels of pro-inflammatory signals like interferon-γ and granzyme B relative to young or healthy mice. However, numbers of regulatory T cells are dramatically different between the 2 models of obesity. Taken together, these findings suggest models of age- and diet-induced obesity may be more distinct than previously thought, with many questions yet to be resolved in this multidimensional disease.

Genetic and epigenetic control of metabolic health

Obesity is characterized as an excess accumulation of body fat resulting from a positive energy balance. It is the major risk factor for type 2 diabetes (T2D). The evidence for familial aggregation of obesity and its associated metabolic diseases is substantial. To date, about 150 genetic loci identified in genome-wide association studies (GWAS) are linked with obesity and T2D, each accounting for only a small proportion of the predicted heritability. However, the percentage of overall trait variance explained by these associated loci is modest (~5-10% for T2D, ~2% for BMI). The lack of powerful genetic associations suggests that heritability is not entirely attributable to gene variations. Some of the familial aggregation as well as many of the effects of environmental exposures, may reflect epigenetic processes. This review summarizes our current knowledge on the genetic basis to individual risk of obesity and T2D, and explores the potential role of epigenetic contribution.

Epigenetic regulation in obesity

PURPOSE OF REVIEW

Research suggests that 65% of variation in obesity is genetic. However, much of the known genetic associations have little known function and their effect size small, thus the gene-environment interaction, including epigenetic influences on gene expression, is suggested to be an important factor in the susceptibilty to obesity. This review will explore the potential of epigenetic markers to influence expression of genes associated with obesity.

RECENT FINDINGS

Epigenetic changes in utero are known to have direct implications on the phenotype of the offspring. More recently work has focused on how such epigenetic changes continue to regulate risk of obesity from infancy through to adulthood. Work has shown that, for example, hypomethylation of the MC4 gene causes an increase in expression, and has a direct impact on appetite and intake, and thus influences risk of obesity. Similar influences are also seen in other aspects of obesity including inflammation and adiposity.

SUMMARY

Maternal diet during foetal development has many epigenetic implications, which affect the offspring's risk factors for obesity during childhood and adulthood, and even in subsequent generations. Genes associated with risk of obesity, are susceptible to epigenetic mutations, which have subsequent effects on disease mechanisms, such as appetite and impaired glucose and insulin tolerance.