Diet-induced DNA methylation within the hypothalamic arcuate nucleus and dysregulated leptin and insulin signaling in the pathophysiology of obesity

Dietary intake of methyl donor nutrients in relation to metabolic health status, serum levels of brain-derived neurotrophic factor and adropin

BACKGROUND AND AIMS

There is a lack of evidence on dietary intake of methyl donor nutrients with metabolic health status and related biomarkers. Thus, this study aimed to assess the relation between methyl donor nutrients intake and metabolic health status with regarding the interactive roles of brain-derived neurotrophic factor (BDNF) and adropin in Iranian adults.

METHODS

This cross-sectional survey was conducted among 527 Iranian adults (45.7% female) selected by multistage cluster random-sampling method. A validated food frequency questionnaire was used to evaluate participants' dietary intake. Metabolic unhealthy status was defined by Wildman criteria as having ≥ 2 of hyperglycemia, hypertriglyceridemia, hypo-HDL-cholesterolemia, hypertension, chronic inflammation, and insulin resistance. Concentrations of metabolic parameters, BDNF and adropin were determined using fasting blood samples.

RESULTS

An inverse association was found between methyl donor nutrients intake and metabolically unhealthy status in multivariable-adjusted model (ORT3 vs. T1 = 0.30; 95%CI: 0.12-0.75). This association was especially significant among overweight/obese adults and was stronger in women. Additionally, consumption of vitamin B6 and choline was separately related to reduced odds of metabolically unhealthy status. Methyl donor intake was not significantly related to low BDNF (ORT3 vs. T1 = 0.93; 95%CI: 0.60-1.44) and adropin (ORT3 vs. T1 = 0.71; 95%CI: 0.44-1.15). However, the interaction between high methyl donor nutrients intake and high BDNF was related to lower odds of metabolically unhealthy status in multivariable-adjusted model (ORMDNS∗BDNF = 0.27; 95%CI: 0.11-0.67).

CONCLUSION

Higher intake of methyl donor nutrients, alone and in interaction with BDNF levels, was associated with decreased odds of metabolically unhealthy status in Iranian adults.

Dietary amino acid patterns and cardiometabolic risk factors among subjects with obesity; a cross-sectional study

BACKGROUND

The prevalence of obesity is a growing global public health concern. Certain dietary amino acids have been shown to have a potential therapeutic role in improving metabolic syndrome parameters and body composition in individuals with obesity. However, some amino acids have been linked to an increased risk of cardiometabolic disorders. This cross-sectional study aims to investigate the association between dietary amino acid patterns and cardiometabolic risk factors in individuals with obesity.

METHODS

This cross-sectional study included 335 participants with obesity (57.9% males and 41.5% females) from Tabriz and Tehran, Iran. The participants were between the ages of 20-50, with a body mass index (BMI) of 30 kg/m2 or higher, and free from certain medical conditions. The study examined participants' general characteristics, conducted anthropometric assessments, dietary assessments, and biochemical assessments. The study also used principal component analysis to identify amino acid intake patterns and determined the association between these patterns and cardiometabolic risk factors in individuals with obesity.

RESULTS

Upon adjusting for potential confounders, the study found that individuals in the third tertiles of pattern 1 and 2 were more likely to have lower LDL levels (OR = 0.99 and 95% CI (0.98-0.99)) for both. Additionally, a significant decrease in total cholesterol was observed in the third tertiles of pattern 2 in model II (OR = 0.99, 95% CI (0.98-0.99)). These findings suggest a potential cardioprotective effect of these amino acid patterns in managing cardiometabolic risk factors in individuals with obesity.

CONCLUSIONS

This study found that two identified amino acid patterns were associated with lower serum LDL and total cholesterol levels, while a third pattern was associated with higher serum triglycerides. The specific amino acids contributing to these patterns highlight the importance of targeted dietary interventions in managing cardiometabolic risk factors in individuals with obesity.

DNA Methylation in the Hypothalamic Feeding Center and Obesity

Obesity rates have been increasing worldwide for decades, mainly due to environmental factors, such as diet, nutrition, and exercise. However, the molecular mechanisms through which environmental factors induce obesity remain unclear. Several mechanisms underlie the body's response to environmental factors, and one of the main mechanisms involves epigenetic modifications, such as DNA methylation. The pattern of DNA methylation is influenced by environmental factors, and altered DNA methylation patterns can affect gene expression profiles and phenotypes. DNA methylation may mediate the development of obesity caused by environmental factors. Similar to the factors governing obesity, DNA methylation is influenced by nutrients and metabolites. Notably, DNA methylation is associated with body size and weight programming. The DNA methylation levels of proopiomelanocortin (Pomc) and neuropeptide Y (Npy) in the hypothalamic feeding center, a key region controlling systemic energy balance, are affected by diet. Conditional knockout mouse studies of epigenetic enzymes have shown that DNA methylation in the hypothalamic feeding center plays an indispensable role in energy homeostasis. In this review, we discuss the role of DNA methylation in the hypothalamic feeding center as a potential mechanism underlying the development of obesity induced by environmental factors.

Mediation effect of JAK2 methylation on the association between sitting time and abdominal obesity in rural adults

BACKGROUND

Sitting time may affect health by altering the methylation of certain genes. This research aimed to estimate the association of sitting time with abdominal obesity and the role of Janus kinase 2 (JAK2) methylation in the association among rural adults.

METHODS

A total of 1062 rural adults from the Henan Rural Cohort Study were included. Whole blood was used to extract genomic DNA. JAK2 DNA methylation level was assessed by MethylTargetTM. The logistic regression model was utilized to assess the association of sitting time with abdominal obesity, and the possible effect of JAK2 DNA methylation on the association were conducted by using mediation analyses.

RESULTS

Average time of sitting of participants was 7.28 ± 3.37 h/d. For per 1 h increment in sitting time, the odd ratio (OR) and 95% confidence interval (CI) of abdominal obesity was 1.153 (1.095, 1.214) after controlling potential risk factors. Simultaneously, the methylation levels of Chr9: 4985407 site and Chr9: 4985238-4985455 region were negatively correlated with abdominal obesity (OR: 0.549, 95% CI: 0.394, 0.765; OR: 0.189, 95% CI: 0.056, 0.640, respectively). Moreover, Chr9: 4985407 site and Chr9: 4985238-4985455 region methylation levels mediated the association of sitting time with abdominal obesity, and the indirect effects account for 6.78% and 4.24%, respectively.

CONCLUSIONS

Longer sitting time was positively correlated with abdominal obesity in the rural population, and methylation level of JAK2 may be an underlying mediation of the effect.

Hypothalamic DNA 5-hydroxymethylation levels are altered by diet-induced weight gain during the development of obesity in a sex-specific manner

Obesity is a major health concern that is associated with altered gene transcription in the hypothalamus. However, the mechanisms controlling this gene expression dysregulation remain largely unknown. DNA 5-hydroxymethylation (5-hmC) is a potent transcriptional activator that is expressed at 10 times higher levels in the brain than the periphery. Despite this, no study has examined if DNA 5-hmC is altered in the brain following exposure to obesogenic diets or contributes to abnormal weight gain over time. Here, we used a rodent diet-induced obesity model in combination with quantitative molecular assays and CRISPR-dCas9 manipulations to test the role of hypothalamic DNA 5-hmC in abnormal weight gain in male and female rats. We found that males, but not females, have decreased levels of DNA 5-hmC in the hypothalamus following exposure to a high fat diet, which directly correlate with increased body weight. Short-term exposure to a high fat diet, which does not result in significant weight gain, resulted in decreased hypothalamic DNA 5-hmC levels, suggesting these changes occur prior to obesity development. Moreover, decreases in DNA 5-hmC persist even after the high fat diet is removed, though the extent of this is diet-dependent. Importantly, CRISPR-dCas9-mediated upregulation of DNA 5-hmC enzymes in the male, but not female, ventromedial nucleus of the hypothalamus significantly reduced the percentage of weight gained on the high fat diet relative to controls. These results suggest that hypothalamic DNA 5-hmC is an important sex-specific regulator of abnormal weight gain following exposure to high fat diets.

Maternal inflammatory, lipid and metabolic markers and associations with birth and breastfeeding outcomes

Background

Conditions in utero influence intrauterine and postnatal infant growth and a few studies indicate that maternal inflammation and insulin resistance might affect birth and breastfeeding outcomes. Furthermore, hormones in human milk (HM) may influence infant appetite-regulation and thereby milk intake, but the associations are less understood.

Objective

(1) To investigate associations between maternal inflammatory, lipid and metabolic markers and birth and breastfeeding outcomes, and (2) to assess predictors of maternal inflammatory, lipid and metabolic markers in pregnancy.

Methods

Seventy-one mother-infant dyads participating in the Mothers, Infants and Lactation Quality (MILQ) study were included in the present study. Fasting blood samples were collected around 28th gestational week, and HM samples at three time points from 1.0 to 8.5 months, where milk intake was assessed using 24-h test weighing. Maternal plasma inflammatory, lipid and metabolic markers included high-sensitive C-reactive protein (hs-CRP), tumor-necrosis factor-α (TNFα), interferon-γ (IFNγ), Interleukin (IL)-6, IL-8, high-, low-, and very-low-density lipoprotein (HDL, LDL, VLDL), total-cholesterol, triglycerides, leptin, adiponectin, insulin, C-peptide, the homeostasis model assessment of insulin resistance (HOMA-IR) and glucose concentration at t = 120 min following an oral glucose tolerance test. Of these, TNFα, IFNγ, IL-6, IL-8, leptin, adiponectin and insulin were also measured in HM samples.

Results

HDL in pregnancy was inversely associated with gestational age (GA) at birth and GA-adjusted birthweight z-score, whereas triglycerides and glucose (t = 120) were positively associated with GA-adjusted birthweight z-score. Higher hs-CRP, VLDL and triglycerides were associated with a higher placental weight. Furthermore, higher HDL, insulin, leptin and HOMA-IR were associated with longer duration of exclusive breastfeeding (EBF). Higher pre-pregnancy BMI was the main predictor of higher levels of hs-CRP, log-TNFα, leptin, insulin, C-peptide, and HOMA-IR.

Conclusion

Maternal lipid and metabolic markers influenced birthweight z-score and placental weight as well as duration of EBF. Furthermore, pre-pregnancy BMI and maternal age predicted levels of several inflammatory and metabolic markers during pregnancy. Our findings indicate that maternal lipid and metabolic profiles in pregnancy may influence fetal growth and breastfeeding, possibly explained by overweight and/or higher placental weight.

Clinical trial registration

https://clinicaltrials.gov/, identifier NCT03254329.

Association of the rs17782313, rs17773430 and rs34114122 Polymorphisms of/near MC4R Gene with Obesity-Related Biomarkers in a Spanish Pediatric Cohort

Obesity is a multifactorial disease whose onset and development are shaped by the individual genetic background. The melanocortin 4 receptor gene (MC4R) is involved in the regulation of food intake and energy expenditure. Some of the single nucleotide polymorphisms (SNPs) of this gene are related to obesity and metabolic risk factors. The present study was undertaken to assess the relationship between three polymorphism SNPs, namely, rs17782313, rs17773430 and rs34114122, and obesity and metabolic risk factors. One hundred seventy-eight children with obesity aged between 7 and 16 years were studied to determine anthropometric variables and biochemical and inflammatory parameters. Our results highlight that metabolic risk factors, especially alterations in carbohydrate metabolism, were related to rs17782313. The presence of the minor C allele in the three variants (C-C-C) was significantly associated with anthropometric measures indicative of obesity, such as the body mass and fat mass indexes, and increased the values of insulinemia to 21.91 µIU/mL with respect to the wild type values. Our study suggests that the C-C-C haplotype of the SNPs rs17782313, rs17773430 and rs34114122 of the MC4R gene potentiates metabolic risk factors at early ages in children with obesity.

Controlling hypothalamic DNA methylation at the Pomc promoter does not regulate weight gain during the development of obesity

Obesity is a complex medical condition that is linked to various health complications such as infertility, stroke, and osteoarthritis. Understanding the neurobiology of obesity is crucial for responding to the etiology of this disease. The hypothalamus coordinates many integral activities such as hormone regulation and feed intake and numerous studies have observed altered hypothalamic gene regulation in obesity models. Previously, it was reported that the promoter region of the satiety gene, Pomc, has increased DNA methylation in the hypothalamus following short-term exposure to a high fat diet, suggesting that epigenetic-mediated repression of hypothalamic Pomc might contribute to the development of obesity. However, due to technical limitations, this has never been directly tested. Here, we used the CRISPR-dCas9-TET1 and dCas9-DNMT3a systems to test the role of Pomc DNA methylation in the hypothalamus in abnormal weight gain following acute exposure to a high fat diet in male rats. We found that exposure to a high fat diet increases Pomc DNA methylation and reduces gene expression in the hypothalamus. Despite this, we found that CRISPR-dCas9-TET1-mediated demethylation of Pomc was not sufficient to prevent abnormal weight gain following exposure to a high fat diet. Furthermore, CRISPR-dCas9-DNMT3a-mediated methylation of Pomc did not alter weight gain following exposure to standard or high fat diets. Collectively, these results suggest that high fat diet induced changes in Pomc DNA methylation are a consequence of, but do not directly contribute to, abnormal weight gain during the development of obesity.

Association between methyl donor nutrients and metabolic health status in overweight and obese adolescents

Limited evidence is available regarding the association of methyl donor nutrients and adolescents' metabolic health. Therefore, we investigated the relation between a combination of methyl donor nutrients and metabolic health status of overweight and obese Iranian adolescents. In this cross-sectional study, 203 overweight/obese adolescents were included, using a multistage cluster random-sampling method. Dietary intakes were assessed by a validated food frequency questionnaire. Methyl donor nutrient score (MDNS) was constructed based on deciles of vitamins B2, B6, B9, B12, methionine, choline and betaine. Glycemic profile, lipid profile, blood pressure and anthropometric indices were collected. Participants were classified as metabolically healthy obese or unhealthy obese (MUO) based on International Diabetes Federation (IDF) and IDF/Homeostasis Model Assessment Insulin Resistance (HOMA-IR) definitions. Mean age of adolescents was 13.98 [Formula: see text] 1.61 y and 50.2% of them was girls. After controlling all of the confounders, individuals in the top tertile of MDNS, had lower odds of MUO (OR 0.36; 95% CI 0.13-0.95) according to IFD criteria. Considering IDF/HOMA-IR criteria, an inverse marginally significant association was observed between the highest tertile of MDNS and odds of MUO (OR 0.36; 95% CI 0.12-1.02) in the fully-adjusted model. Furthermore, significant inverse association was found between each unit increase in MDNS and odds of MUO based on IDF criteria, but not for IDF/HOMA-IR definition. We found that overweight/obese adolescents with higher dietary intakes of methyl donor nutrients were less likely to be metabolically unhealthy. Further studies are needed to confirm the findings.

Diaphragma juglandis extracts modifies the gut microbiota during prevention of type 2 diabetes in rats

ETHNOPHARMACOLOGICAL RELEVANCE

The diaphragma juglandis (DJ) comes from the wooden septum in the core of Juglans regia L, also known as the walnut septum. In Iranian traditional medicine, walnut distraction wood was widely used in the treatment of diabetes. However, there is a lack of research data on the mechanism of DJ against diabetes.

AIM OF THE STUDY

To explore the protective effect of diaphragma juglandis extract (DJE) on type 2 diabetic rats and the hypoglycemic mechanism of DJE.

MATERIAL AND METHODS

Supplemented DJE and fed a high-fat diet for five weeks, and then injected low-dose STZ, successfully induced type 2 diabetic rats. Collected rat serum, liver, pancreas and feces to determine the biochemical parameters of serum and liver, analyze the pathological damages of pancreas and liver, and measure the changes of gut microbes in feces.

RESULTS

DJE could inhibit the metabolic abnormalities of T2DM by improving insulin resistance, abnormal lipid metabolism, liver damage, oxidative stress, and reducing inflammation. DJE significantly held fasting blood glucose, glycosylated serum protein, serum low density lipoprotein, high density lipoprotein, oral glucose tolerance test, nitric oxide, superoxide dismutase and catalase, serum and liver triglycerides, total cholesterol, aspartate aminotransferase, alanine aminotransferase, malondialdehyde, lipopolysaccharide, fasting insulin and tumor necrosis factor-α and prevented the pathological damage of pancreas and liver. The 16SrRNA gene sequencing results showed that DJE intercepted the disorders of the fecal gut microbes, mainly including Lactobacillaceae, Rikenella, Pygmaiobacter, Oscillospiraceae and Klebsiella. Spearman correlation analysis showed that the changes of gut microbes were closely relative with biochemical parameters.

CONCLUSION

DJE might prevent type 2 diabetes and its complications and hold up the disorders of gut microbes.

Time-of-Day-Dependent Effects of Bromocriptine to Ameliorate Vascular Pathology and Metabolic Syndrome in SHR Rats Held on High Fat Diet

The treatment of type 2 diabetes patients with bromocriptine-QR, a unique, quick release micronized formulation of bromocriptine, improves glycemic control and reduces adverse cardiovascular events. While the improvement of glycemic control is largely the result of improved postprandial hepatic glucose metabolism and insulin action, the mechanisms underlying the drug's cardioprotective effects are less well defined. Bromocriptine is a sympatholytic dopamine agonist and reduces the elevated sympathetic tone, characteristic of metabolic syndrome and type 2 diabetes, which potentiates elevations of vascular oxidative/nitrosative stress, known to precipitate cardiovascular disease. Therefore, this study investigated the impact of bromocriptine treatment upon biomarkers of vascular oxidative/nitrosative stress (including the pro-oxidative/nitrosative stress enzymes of NADPH oxidase 4, inducible nitric oxide (iNOS), uncoupled endothelial nitric oxide synthase (eNOS), the pro-inflammatory/pro-oxidative marker GTP cyclohydrolase 1 (GTPCH 1), and the pro-vascular health enzyme, soluble guanylate cyclase (sGC) as well as the plasma level of thiobarbituric acid reactive substances (TBARS), a circulating marker of systemic oxidative stress), in hypertensive SHR rats held on a high fat diet to induce metabolic syndrome. Inasmuch as the central nervous system (CNS) dopaminergic activities both regulate and are regulated by CNS circadian pacemaker circuitry, this study also investigated the time-of-day-dependent effects of bromocriptine treatment (10 mg/kg/day at either 13 or 19 h after the onset of light (at the natural waking time or late during the activity period, respectively) among animals held on 14 h daily photoperiods for 16 days upon such vascular biomarkers of vascular redox state, several metabolic syndrome parameters, and mediobasal hypothalamic (MBH) mRNA expression levels of neuropeptides neuropeptide Y (NPY) and agouti-related protein (AgRP) which regulate the peripheral fuel metabolism and of mRNA expression of other MBH glial and neuronal cell genes that support such metabolism regulating neurons in this model system. Such bromocriptine treatment at ZT 13 improved (reduced) biomarkers of vascular oxidative/nitrosative stress including plasma TBARS level, aortic NADPH oxidase 4, iNOS and GTPCH 1 levels, and improved other markers of coupled eNOS function, including increased sGC protein level, relative to controls. However, bromocriptine treatment at ZT 19 produced no improvement in either coupled eNOS function or sGC protein level. Moreover, such ZT 13 bromocriptine treatment reduced several metabolic syndrome parameters including fasting insulin and leptin levels, as well as elevated systolic and diastolic blood pressure, insulin resistance, body fat store levels and liver fat content, however, such effects of ZT 19 bromocriptine treatment were largely absent versus control. Finally, ZT 13 bromocriptine treatment reduced MBH NPY and AgRP mRNA levels and mRNA levels of several MBH glial cell/neuronal genes that code for neuronal support/plasticity proteins (suggesting a shift in neuronal structure/function to a new metabolic control state) while ZT 19 treatment reduced only AgRP, not NPY, and was with very little effect on such MBH glial cell genes expression. These findings indicate that circadian-timed bromocriptine administration at the natural circadian peak of CNS dopaminergic activity (that is diminished in insulin resistant states), but not outside this daily time window when such CNS dopaminergic activity is naturally low, produces widespread improvements in biomarkers of vascular oxidative stress that are associated with the amelioration of metabolic syndrome and reductions in MBH neuropeptides and gene expressions known to facilitate metabolic syndrome. These results of such circadian-timed bromocriptine treatment upon vascular pathology provide potential mechanisms for the observed marked reductions in adverse cardiovascular events with circadian-timed bromocriptine-QR therapy (similarly timed to the onset of daily waking as in this study) of type 2 diabetes subjects and warrant further investigations into related mechanisms and the potential application of such intervention to prediabetes and metabolic syndrome patients as well.

Dietary diversity modifies the association between FTO polymorphisms and obesity phenotypes

The current study aimed to evaluate the interaction of the dietary diversity score (DDS) and FTO polymorphisms concerning obesity phenotypes. The 4480 subjects of this cohort study were selected. The polymorphisms rs1121980, rs14211085 and rs8050136 were selected and genotyped. The weighted method was used to calculate the genetic risk score (GRS). Obesity marker changes were calculated. Those with minor allele carriers of rs1121980 had lower body mass index changes (Q1: 1.58 ± 0.60 vs. Q4: 0.13 ± 0.59) and visceral adiposity index (VAI) (Q1: -0.00 ± 0.02 vs. Q4: -0.04 ± 0.02) when they had higher DDS (P interaction = 0.05). Carriers of the minor allele of rs8050136 had significant VAI change across DDS quartiles (Q1: -0.01 ± 0.02 vs. Q4: -0.02 ± 0.02, P interaction = 0.05). No significant interaction was found between the GRS and DDS on general obesity. The pattern of dietary diversity may have a mediatory role in improving obesity markers in subjects with a more genetic predisposition to adiposity.

Anti-inflammatory and antidiabetic effects of grape-derived stilbene concentrate in the experimental metabolic syndrome

AIMS

This study aimed to investigate the carbohydrate and lipid dynamics, associated inflammation markers and the effectiveness of a grape-derived stilbene concentrate (GDSC) treatment in experimental metabolic syndrome (MetS).

METHODS

The study was carried out on 40 male 12-weeks of age Wistar rats. The MetS was induced using the fructose model (feeding with 60%-solid fructose diet for 24 weeks). Rats with induced MetS were treated with polyphenolic GDSC, which was obtained by water-alcohol extraction of Vitis vinifera grapevine (Ressfood LLC, Russia).

RESULTS

The experimentally induced MetS development leads to classic MetS signs, including abdominal obesity, hyperglycemia, high lipid levels and heart damage. The expression of glucose transporter type 4 (GLUT4) and peroxisome proliferator-activated receptor-γ (PPAR-γ) had greater dynamics than biochemical measurements. The development of the associated inflammatory reactions was confirmed by the increased level of Toll-like receptor type 4 (TLR4) and C-reactive protein (CRP) compared to control levels. The use of the GDSC had positive dynamics in carbohydrate and lipid levels, inflammatory marker, also prevented associated inflammation and heart damage.

Diet-induced DNA methylation within the hypothalamic arcuate nucleus and dysregulated leptin and insulin signaling in the pathophysiology of obesity

Obesity rates continue to rise in an unprecedented manner in what could be the most rapid population‐scale shift in human phenotype ever to occur. Increased consumption of unhealthy, calorie‐dense foods, coupled with sedentary lifestyles, is the main factor contributing to a positive energy balance and the development of obesity. Leptin and insulin are key hormones implicated in pathogenesis of this disorder and are crucial for controlling whole‐body energy homeostasis. Their respective function is mediated by the counterbalance of anorexigenic and orexigenic neurons located within the hypothalamic arcuate nucleus. Dysregulation of leptin and insulin signaling pathways within this brain region may contribute not only to the development of obesity, but also systemically affect the peripheral organs, thereby manifesting as metabolic diseases. Although the exact mechanisms detailing how these hypothalamic nuclei contribute to disease pathology are still unclear, increasing evidence suggests that altered DNA methylation may be involved. This review evaluates animal studies that have demonstrated diet‐induced DNA methylation changes in genes that regulate energy homeostasis within the arcuate nucleus, and elucidates possible mechanisms causing hypothalamic leptin and insulin resistance leading to the development of obesity and metabolic diseases.