Maternal High-Fructose Corn Syrup consumption causes insulin resistance and hyperlipidemia in offspring via DNA methylation of the Pparα promoter region

Approaches to nutritional research using organoids; fructose treatment induces epigenetic changes in liver organoids

Nutritional researches have successfully used animal models to gain new insights into nutrient action. However, comprehensive descriptions of their molecular mechanisms of action remain elusive as appropriate in vitro evaluation systems are lacking. Organoid models can mimic physiological structures and reproduce in vivo functions, making them increasingly utilized in biomedical research for a better understand physiological and pathological phenomena. Therefore, organoid modeling can be a powerful approach for to understand the molecular mechanisms of nutrient action. The present study aims to demonstrate the utility of organoids in nutritional research by further investigating the molecular mechanisms responsible for the negative effects of fructose intake using liver organoids. Here, we treated liver organoids with fructose and analyzed their gene expression profiles and DNA methylation levels. Microarray analysis demonstrated that fructose-treated organoids exhibited increased selenoprotein p (Sepp1) gene expression, whereas pyrosequencing assays revealed reduced DNA methylation levels in the Sepp1 region. These results were consistent with observations using hepatic tissues from fructose-fed rats. Conversely, no differences in Sepp1 mRNA and DNA methylation levels were observed in two-dimensional cells. These results suggest that organoids serve as an ideal in vitro model to recapitulate in vivo tissue responses and help to validate the molecular mechanisms of nutrient action compared to conventional cellular models.

Dietary nutrients during gestation cause obesity and related metabolic changes by altering DNA methylation in the offspring

Growing evidence shows that maternal nutrition from preconception until lactation has an important effect on the development of non-communicable diseases in the offspring. Biological responses to environmental stress during pregnancy, including undernutrition or overnutrition of various nutrients, are transmitted in part by DNA methylation. The aim of the present narrative review is to summarize literature data on altered DNA methylation patterns caused by maternal macronutrient or vitamin intake and its association with offspring's phenotype (obesity and related metabolic changes). With our literature search, we found evidence for the association between alterations in DNA methylation pattern of different genes caused by maternal under- or overnutrition of several nutrients (protein, fructose, fat, vitamin D, methyl-group donor nutrients) during 3 critical periods of programming (preconception, pregnancy, lactation) and the development of obesity or related metabolic changes (glucose, insulin, lipid, leptin, adiponectin levels, blood pressure, non-alcoholic fatty liver disease) in offspring. The review highlights that maternal consumption of several nutrients could individually affect the development of offspring's obesity and related metabolic changes via alterations in DNA methylation.

Impact of maternal fructose intake on liver stem/progenitor cells in offspring: Insights into developmental origins of health and disease

AIMS

The developmental origin of health and disease (DOHaD) theory postulates that poor nutrition during fetal life increases the risk of disease later in life. Excessive fructose intake has been associated with obesity, diabetes, and nonalcoholic fatty liver disease, and maternal fructose intake during pregnancy has been shown to affect offspring health. In this study, we investigated the effects of high maternal fructose intake on the liver stem/progenitor cells of offspring.

MAIN METHOD

A fructose-based DOHaD model was established using Sprague-Dawley rats. Small hepatocytes (SHs), which play an important role in liver development and regeneration, were isolated from the offspring of dams that were fed a high-fructose corn syrup (HFCS) diet. The gene expression and DNA methylation patterns were analyzed on postnatal day (PD) 21 and 60.

KEY FINDINGS

Maternal HFCS intake did not affect body weight or caloric intake, but differences in gene expression and DNA methylation patterns were observed in the SHs of offspring. Functional analysis revealed an association between metabolic processes and ion transport.

SIGNIFICANCE

These results suggest that maternal fructose intake affects DNA methylation and gene expression in the liver stem/progenitor cells of offspring. Furthermore, the prolonged retention of these changes in gene expression and DNA methylation in adulthood (PD 60) suggests that maternal fructose intake may exert lifelong effects. These findings provide insights into the DOHaD for liver-related disorders and highlight the importance of maternal nutrition for the health of the next generation.

DNA methylation regulates pancreatic gene expression and links maternal high-fat diet to the offspring glucose metabolism

Maternal high-fat diet (HFD) is related to an increased risk of glucose metabolism disorders throughout the whole life of offspring. The pancreas is a glucose homeostasis regulator. Accumulating evidence has revealed that maternal HFD affects offspring pancreas structure and function. However, the potential mechanism remains unclear. In this study, the mouse dam was fed with HFD or control diet (CD) during prepregnancy, pregnancy and lactation. The pancreatic insulin secretion function and islet genome methylome of offspring were analyzed. Pancreatic islet specific gene methylation was detected by using MeDIP qPCR. The results showed that body weight, blood glucose after oral glucose loads, fasting serum insulin, and HOMA-IR index values were significantly higher in male 12-week-old offspring from HFD dams than in the offspring from CD dams. Maternal HFD induced insulin secretion defects in male offspring. Compared with that in maternal CD group, methylation of the Abcc8 and Kcnj11 genes was increased in maternal HFD group in male offspring pancreatic islets. Furthermore, the expression levels of Abcc8 and Kcnj11 were downregulated by intrauterine exposure to a maternal HFD. In summary, maternal HFD results in a long-term functional disorder of the pancreas that is involved in insulin secretion-related gene DNA hypermethylation.

Performance of triponderal mass index, body mass index z scores, and body mass index performance in the diagnosis of obesity in children and adolescents

OBJECTIVES

Childhood obesity is a global health problem that affects millions of children and causes obesity-related adverse health outcomes in both childhood and adulthood. Although body mass index (BMI) z scores and percentiles are used in the diagnosis of obesity in children, it has been emphasized in recent years that the triponderal mass index (TMI) may be more accurate for this purpose. We aimed to compare TMI with BMI in the diagnosis of obesity in Turkish children and adolescents.

METHODS

The records of 3540 children who applied to Gülhane Training and Research Hospital were retrospectively scanned and the data of 1161 children were included in the study. The body fat percentage (BF%) was calculated by a formula, and children with body fat in the ≥95th percentile were classified as obese. Receiver study characteristics analysis was performed to compare the effectiveness of TMI and BMI in the diagnosis of obesity.

RESULTS

TMI correlated more with BF% (r = 0.863) than fat mass (r = 0.664); BMI correlated more with fat mass (r = 0.957) than BF% (r = 0.714) (P < 0.001). TMI had the highest area under the curve (AUC) in boys at diagnosis of obesity (6-11 y = 0.981; 12-15 y = 0.994). Girls ages 6 to 11 y had the same AUC for all 3 indexes (AUC = 0.977), whereas girls ages 12 to 15 y had the highest AUC for TMI (AUC = 0.967). However, the AUC values between all indices were very close.

CONCLUSIONS

TMI can be used to diagnose obesity in Turkish children and adolescents in both boys and girls similarly and with good performance. The correlation with BF% and stability of TMI makes this index more advantageous. However, it should be noted that the performance of each of the 3 indices is very close to that of the others, and adjustments should be made according to age and sex.

Targeted DNA Demethylation: Vectors, Effectors and Perspectives

Aberrant DNA hypermethylation at regulatory cis-elements of particular genes is seen in a plethora of pathological conditions including cardiovascular, neurological, immunological, gastrointestinal and renal diseases, as well as in cancer, diabetes and others. Thus, approaches for experimental and therapeutic DNA demethylation have a great potential to demonstrate mechanistic importance, and even causality of epigenetic alterations, and may open novel avenues to epigenetic cures. However, existing methods based on DNA methyltransferase inhibitors that elicit genome-wide demethylation are not suitable for treatment of diseases with specific epimutations and provide a limited experimental value. Therefore, gene-specific epigenetic editing is a critical approach for epigenetic re-activation of silenced genes. Site-specific demethylation can be achieved by utilizing sequence-dependent DNA-binding molecules such as zinc finger protein array (ZFA), transcription activator-like effector (TALE) and clustered regularly interspaced short palindromic repeat-associated dead Cas9 (CRISPR/dCas9). Synthetic proteins, where these DNA-binding domains are fused with the DNA demethylases such as ten-eleven translocation (Tet) and thymine DNA glycosylase (TDG) enzymes, successfully induced or enhanced transcriptional responsiveness at targeted loci. However, a number of challenges, including the dependence on transgenesis for delivery of the fusion constructs, remain issues to be solved. In this review, we detail current and potential approaches to gene-specific DNA demethylation as a novel epigenetic editing-based therapeutic strategy.

Maternal High-Fructose Corn Syrup Intake Impairs Corticosterone Clearance by Reducing Renal 11β-Hsd2 Activity via miR-27a-Mediated Mechanism in Rat Offspring

We previously reported that maternal fructose consumption increases blood corticosterone levels in rat offspring. However, the underlying mechanism of action remains unclear. In the present study, we aimed to elucidate the molecular mechanism by which maternal high-fructose corn syrup (HFCS) intake increases circulating GC levels in rat offspring (GC; corticosterone in rodents and cortisol in humans). Female Sprague Dawley rats received HFCS solution during gestation and lactation. The male offspring were fed distilled water from weaning to 60 days of age. We investigated the activities of GC-metabolizing enzymes (11β-Hsd1 and 11β-Hsd2) in various tissues (i.e., liver, kidney, adrenal glands, muscle, and white adipose tissue) and epigenetic modification. 11β-Hsd2 activity decreased in the kidney of the HFCS-fed dams. Moreover, the epigenetic analysis suggested that miR-27a reduced Hsd11b2 mRNA expression in the kidney of offspring. Maternal HFCS-induced elevation of circulating GC levels in offspring may be explained by a decrease in 11β-Hsd2 activity via renal miR-27a expression. The present study may allow us to determine one of the mechanisms of GC elevation in rat offspring that is often observed in the developmental origins of the health and disease (DOHaD) phenomenon.

Higher rates of autism and attention deficit/hyperactivity disorder in American children: Are food quality issues impacting epigenetic inheritance?

In the United States, schools offer special education services to children who are diagnosed with a learning or neurodevelopmental disorder and have difficulty meeting their learning goals. Pediatricians may play a key role in helping children access special education services. The number of children ages 6-21 in the United States receiving special education services increased 10.4% from 2006 to 2021. Children receiving special education services under the autism category increased 242% during the same period. The demand for special education services for children under the developmental delay and other health impaired categories increased by 184% and 83% respectively. Although student enrollment in American schools has remained stable since 2006, the percentage distribution of children receiving special education services nearly tripled for the autism category and quadrupled for the developmental delay category by 2021. Allowable heavy metal residues remain persistent in the American food supply due to food ingredient manufacturing processes. Numerous clinical trial data indicate heavy metal exposures and poor diet are the primary epigenetic factors responsible for the autism and attention deficit hyperactivity disorder epidemics. Dietary heavy metal exposures, especially inorganic mercury and lead may impact gene behavior across generations. In 2021, the United States Congress found heavy metal residues problematic in the American food supply but took no legislative action. Mandatory health warning labels on select foods may be the only way to reduce dietary heavy metal exposures and improve child learning across generations.

PPARα in the Epigenetic Driver Seat of NAFLD: New Therapeutic Opportunities for Epigenetic Drugs?

Nonalcoholic fatty liver disease (NAFLD) is a growing epidemic and the most common cause of chronic liver disease worldwide. It consists of a spectrum of liver disorders ranging from simple steatosis to NASH which predisposes patients to further fibrosis, cirrhosis and even hepatocarcinoma. Despite much research, an approved treatment is still lacking. Finding new therapeutic targets has therefore been a main priority. Known as a main regulator of the lipid metabolism and highly expressed in the liver, the nuclear receptor peroxisome proliferator-activated receptor-α (PPARα) has been identified as an attractive therapeutic target. Since its expression is silenced by DNA hypermethylation in NAFLD patients, many research strategies have aimed to restore the expression of PPARα and its target genes involved in lipid metabolism. Although previously tested PPARα agonists did not ameliorate the disease, current research has shown that PPARα also interacts and regulates epigenetic DNMT1, JMJD3, TET and SIRT1 enzymes. Moreover, there is a growing body of evidence suggesting the orchestrating role of epigenetics in the development and progression of NAFLD. Therefore, current therapeutic strategies are shifting more towards epigenetic drugs. This review provides a concise overview of the epigenetic regulation of NAFLD with a focus on PPARα regulation and highlights recently identified epigenetic interaction partners of PPARα.

Effects of High-Fructose Corn Syrup Intake on Glucocorticoid Metabolism in Rats During Childhood, Adolescence and Adulthood

The consumption of high-fructose corn syrup (HFCS) has been increasing in recent decades, especially among children. Some reports suggest that children and adolescents are more sensitive to the adverse effects of fructose intake than adults. However, the underlying mechanism of the difference in vulnerability between adolescence and adulthood have not yet been elucidated. In this study, we attempted to elucidate the different effects of HFCS intake at different growth stages in rats: childhood and adolescence (postnatal day (PD) 21–60), young adulthood (PD60–100), and adulthood (PD100–140). Since alterations in hepatic glucocorticoid (GC) metabolism can cause diseases including insulin resistance, we focused on GC metabolizing enzymes such as 11 beta-hydroxysteroid dehydrogenase 1 and 2 (Hsd11b1 and Hsd11b2) and steroid 5 alpha-reductase 1 (Srd5a1). Western blotting showed an increase in Hsd11b1 expression and a decrease in Hsd11b2 expression in childhood and adolescence but not in adulthood. We also observed changes in Hsd11b1 and Hsd11b2 activities only in childhood and adolescence, consistent with the results of mRNA and protein expression analysis. The effect of high-fructose intake with regards to GC metabolism may therefore vary with developmental stage. This study provides insight into the adverse effects of fructose on GC metabolism in children in the context of increasing rates of HFCS consumption.

The role of maternal DNA methylation in pregnancies complicated by gestational diabetes

Diabetes in pregnancy is associated with adverse pregnancy outcomes and poses a serious threat to the health of mother and child. Although the pathophysiological mechanisms that underlie the association between maternal diabetes and pregnancy complications have not yet been elucidated, it has been suggested that the frequency and severity of pregnancy complications are linked to the degree of hyperglycemia. Epigenetic mechanisms reflect gene-environment interactions and have emerged as key players in metabolic adaptation to pregnancy and the development of complications. DNA methylation, the best characterized epigenetic mechanism, has been reported to be dysregulated during various pregnancy complications, including pre-eclampsia, hypertension, diabetes, early pregnancy loss and preterm birth. The identification of altered DNA methylation patterns may serve to elucidate the pathophysiological mechanisms that underlie the different types of maternal diabetes during pregnancy. This review aims to provide a summary of existing knowledge on DNA methylation patterns in pregnancies complicated by pregestational type 1 (T1DM) and type 2 diabetes mellitus (T2DM), and gestational diabetes mellitus (GDM). Four databases, CINAHL, Scopus, PubMed and Google Scholar, were searched for studies on DNA methylation profiling in pregnancies complicated with diabetes. A total of 1985 articles were identified, of which 32 met the inclusion criteria and are included in this review. All studies profiled DNA methylation during GDM or impaired glucose tolerance (IGT), while no studies investigated T1DM or T2DM. We highlight the increased methylation of two genes, Hypoxia‐inducible Factor‐3α (HIF3α) and Peroxisome Proliferator-activated Receptor Gamma-coactivator-Alpha (PGC1-α), and the decreased methylation of one gene, Peroxisome Proliferator Activated Receptor Alpha (PPARα), in women with GDM compared to pregnant women with normoglycemia that were consistently methylated across diverse populations with varying pregnancy durations, and using different diagnostic criteria, methodologies and biological sources. These findings support the candidacy of these three differentially methylated genes as biomarkers for GDM. Furthermore, these genes may provide insight into the pathways that are epigenetically influenced during maternal diabetes and which should be prioritized and replicated in longitudinal studies and in larger populations to ensure their clinical applicability. Finally, we discuss the challenges and limitations of DNA methylation analysis, and the need for DNA methylation profiling to be conducted in different types of maternal diabetes in pregnancy.

High-fructose corn syrup intake has stronger effects on the transcription level of hepatic lipid metabolism-related genes, via DNA methylation modification, in childhood and adolescence than in other generations

AIMS

This study aimed to analyze differences in sensitivity to hepatic lipid metabolism at different ages, through DNA methylation, using an experimental rat model of high-fructose corn syrup (HFCS) intake.

MAIN METHODS

The experimental was divided into three periods: childhood and adolescence (postnatal day (PD) 21-60), young adulthood (PD61-100), and adulthood (PD101-140). Rats in the different age groups were assigned to receive either water (C: control group) or 20% HFCS solution (H: HFCS-fed group). We measured hepatic mRNA levels of peroxisome proliferator-activated receptor alpha (Ppara), carnitine palmitoyltransferase 1A (Cpt1a), fatty acid synthase (Fasn), and peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (Pgc1a) using real-time PCR. Additionally, we examined the DNA methylation levels of Ppara, Cpt1a, Fasn, and Pgc1a using pyrosequencing.

KEY FINDINGS

Gene expressions of Cpt1a and Ppara in childhood and adolescence were significantly lower in the H group than in the C group. Conversely, Fasn and Pgc1a expressions were significantly higher in the H group than in the C group. Additionally, there was hypermethylation of Cpt1a and Ppara and hypomethylation of Fasn and Pgc1a in the H groups of childhood and adolescence. However, only one gene expression and methylation change was observed in young adulthood and adulthood groups. We found that HFCS intake in rats had stronger lipid metabolic effects in childhood and adolescence than in other generations, and that its mechanism involved epigenetic regulation.

SIGNIFICANCE

We anticipate that these research findings will be a breakthrough for elucidating the varying effects of growth stage in the future.