Epigenetic Effects of n-3 LCPUFAs: A Role in Pediatric Metabolic Syndrome

Fish Oil Supplementation Mitigates High-Fat Diet-Induced Obesity: Exploring Epigenetic Modulation and Genes Associated with Adipose Tissue Dysfunction in Mice

This study investigated the effects of fish oil (FO) treatment, particularly enriched with eicosapentaenoic acid (EPA), on obesity induced by a high-fat diet (HFD) in mice. The investigation focused on elucidating the impact of FO on epigenetic modifications in white adipose tissue (WAT) and the involvement of adipose-derived stem cells (ASCs). C57BL/6j mice were divided into two groups: control diet and HFD for 16 weeks. In the last 8 weeks, the HFD group was subdivided into HFD and HFD + FO (treated with FO). WAT was removed for RNA and protein extraction, while ASCs were isolated, cultured, and treated with leptin. All samples were analyzed using functional genomics tools, including PCR-array, RT-PCR, and Western Blot assays. Mice receiving an HFD displayed increased body mass, fat accumulation, and altered gene expression associated with WAT inflammation and dysfunction. FO supplementation attenuated these effects, a potential protective role against HFD-induced obesity. Analysis of H3K27 revealed HFD-induced changes in histone, which were partially reversed by FO treatment. This study further explored leptin signaling in ASCs, suggesting a potential mechanism for ASC dysfunction in the obesity-rich leptin environment of WAT. Overall, FO supplementation demonstrated efficacy in mitigating HFD-induced obesity, influencing epigenetic and molecular pathways, and shedding light on the role of ASCs and leptin signaling in WAT dysfunction associated with obesity.

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.

Long-chain n-3 PUFA given before and throughout gestation and lactation in rats prevent high-fat diet-induced insulin resistance in male offspring in a tissue-specific manner

This study investigated whether long-chain n-3 PUFA (LC n-3 PUFA) given to pregnant rats fed a high-fat (HF) diet may prevent fetal programming in male offspring at adulthood. Six weeks before mating, and throughout gestation and lactation, female nulliparous Sprague-Dawley rats were given a chow (C) diet, HF (60·6 % fat from maize, rapeseed oils and lard) or HF in which one-third of fat was replaced by fish oil (HF n-3). At weaning, the three offspring groups were randomly separated in two groups fed C diet, or HF without LC n-3 PUFA, for 7 weeks until adulthood. Glucose tolerance and insulin sensitivity were assessed by an oral glucose tolerance test both at weaning and at adulthood. Insulin signalling was determined in liver, muscle and adipose tissue by quantification of the phosphorylation of Akt on Ser 473 at adulthood. At weaning, as at adulthood, offspring from HF-fed dams were obese and displayed glucose intolerance (GI) and insulin resistance (IR), but not those from HFn-3 fed dams. Following the post-weaning C diet, phosphorylation of Akt was strongly reduced in all tissues of offspring from HF dams, but to a lesser extent in liver and muscle of offspring from HFn-3 dams. However, it was abolished in all tissues of all offspring groups fed the HF post-weaning diet. Thus, LC n-3 PUFA introduced in a HF in dams partially prevented the transmission of GI and IR in adult offspring even though they were fed without LC n-3 PUFA from weaning.

Long-Chain Polyunsaturated Fatty Acids Effects on Cardiovascular Risk in Childhood: A Narrative Review

Long-chain polyunsaturated fatty acids (LCPUFAs) are semi-essential fatty acids widely studied in adult subjects for their healthy-heart effects, especially on secondary prevention in patients who already experienced a cardiac event. LCPUFAs consumption is safe, without adverse effects, and they are usually well-tolerated; they can be taken either in foods or as nutritional supplements. LCPUFAs' positive effect on global health has been worldwide recognized also for pediatric patients. In childhood and adolescence, research has mainly focused on LCPUFAs' effects on neurodevelopment, brain and visual functions and on maternal-fetal medicine, yet their cardiovascular effects in childhood are still understudied. Atherosclerosis is a multifactorial process that starts even before birth and progresses throughout life; thus, cardiovascular prevention is advisable and effective from the very first years of life. Nutritional and lifestyle interventions are the main factors that can interfere with atherosclerosis in childhood, and the consumption of specific nutrients, such as LCPUFAs, can enhance positive nutritional effects. The aim of our narrative review is to analyze the effect of LCPUFAs on cardiovascular risk factors and on cardiovascular risk prevention in developmental age, focusing on specific conditions such as weight excess and dyslipidemia.

Nutritional Treatment of Hypertriglyceridemia in Childhood: From Healthy-Heart Counselling to Life-Saving Diet

Hypertriglyceridemia is a lipid disorder with a varying prevalence; it is very common if we consider triglyceride plasma values slightly above the threshold, whereas it is extremely rare if only severely elevated triglyceride levels are considered. In most cases, severe forms of hypertriglyceridemia are caused by genetic mutations in the genes that regulate triglyceride metabolism, thus leading to extreme triglyceride plasma values and acute pancreatitis risk. Secondary forms of hypertriglyceridemia are usually less severe and are mainly associated with weight excess, but they can also be linked to liver, kidney, endocrinologic, or autoimmune diseases or to some class of drugs. Nutritional intervention is the milestone treatment for patients with hypertriglyceridemia and it has to be modulated on the underlying cause and on triglyceride plasma levels. In pediatric patients, nutritional intervention must be tailored according to specific age-related energy, growth and neurodevelopment requests. Nutritional intervention is extremely strict in case of severe hypertriglyceridemia, whereas it is similar to good healthy nutritional habits counselling for mild forms, mainly related to wrong habits and lifestyles, and to secondary causes. The aim of this narrative review is to define different nutritional intervention for various forms of hypertriglyceridemia in children and adolescents.

Associations between Dietary Intake, Blood Levels of Omega-3 and Omega-6 Fatty Acids and Reading Abilities in Children

Lower levels of omega-3 polyunsaturated fatty acids (PUFAs) have been described in individuals with reading difficulties, but the degree and the nature of such deficiencies as well as the role of nutrition are a matter of debate. The aim of the present study was to investigate the associations between PUFA blood levels, nutritional status, and reading/writing/phonological awareness performances in 42 school-age children with varying levels of reading ability. Significant correlations were found between PUFA levels (specific omega-6/omega-3 ratios), the ratio of omega-6-derived calories to the total amount of calories and reading scores. Mediation analysis showed a mediating effect of fatty acids on the association between reading speed scores and nutritional status. Moderation analysis, moreover, showed that the associations of omega-6/omega-3 ratios in the blood and Kcal omega-6/Kcal total in dietary intake were moderated by reading speed performances. Results of the mediation and moderation models confirm that the associations of dietary intake with PUFA levels in the blood vary depending on learning abilities. Reading skills appear to be sensitive to the effects of a complex set of favorable conditions related to the presence of higher omega-3 blood levels. These conditions may reflect the action of dietary as well as genetic and epigenetic mechanisms.

Maternal PUFAs, Placental Epigenetics, and Their Relevance to Fetal Growth and Brain Development

Dietary polyunsaturated fatty acids (PUFAs), especially omega-3 (n-3) and n-6 long-chain (LC) PUFAs, are indispensable for the fetus' brain supplied by the placenta. Despite being highly unsaturated, n-3 LCPUFA-docosahexaenoic acid (DHA) plays a protective role as an antioxidant in the brain. Deficiency of DHA during fetal development may cause irreversible damages in neurodevelopment programming. Dietary PUFAs can impact placental structure and functions by regulating early placentation processes, such as angiogenesis. They promote remodeling of uteroplacental architecture to facilitate increased blood flow and surface area for nutrient exchange. The placenta's fatty acid transfer depends on the uteroplacental vascular development, ensuring adequate maternal circulatory fatty acids transport to fulfill the fetus' rapid growth and development requirements. Maternal n-3 PUFA deficiency predominantly leads to placental epigenetic changes than other fetal developing organs. A global shift in DNA methylation possibly transmits epigenetic instability in developing fetuses due to n-3 PUFA deficiency. Thus, an optimal level of maternal omega-3 (n-3) PUFAs may protect the placenta's structural and functional integrity and allow fetal growth by controlling the aberrant placental epigenetic changes. This narrative review summarizes the recent advances and underpins the roles of maternal PUFAs on the structure and functions of the placenta and their relevance to fetal growth and brain development.

Evidence that complement and coagulation proteins are mediating the clinical response to omega-3 fatty acids: A mass spectrometry-based investigation in subjects at clinical high-risk for psychosis

Preliminary evidence indicates beneficial effects of omega-3 polyunsaturated fatty acids (PUFAs) in early psychosis. The present study investigates the molecular mechanism of omega-3 PUFA-associated therapeutic effects in clinical high-risk (CHR) participants. Plasma samples of 126 CHR psychosis participants at baseline and 6-months follow-up were included. Plasma protein levels were quantified using mass spectrometry and erythrocyte omega-3 PUFA levels were quantified using gas chromatography. We examined the relationship between change in polyunsaturated PUFAs (between baseline and 6-month follow-up) and follow-up plasma proteins. Using mediation analysis, we investigated whether plasma proteins mediated the relationship between change in omega-3 PUFAs and clinical outcomes. A 6-months change in omega-3 PUFAs was associated with 24 plasma proteins at follow-up. Pathway analysis revealed the complement and coagulation pathway as the main biological pathway to be associated with change in omega-3 PUFAs. Moreover, complement and coagulation pathway proteins significantly mediated the relationship between change in omega-3 PUFAs and clinical outcome at follow-up. The inflammatory protein complement C5 and protein S100A9 negatively mediated the relationship between change in omega-3 PUFAs and positive symptom severity, while C5 positively mediated the relationship between change in omega-3 and functional outcome. The relationship between change in omega-3 PUFAs and cognition was positively mediated through coagulation factor V and complement protein C1QB. Our findings provide evidence for a longitudinal association of omega-3 PUFAs with complement and coagulation protein changes in the blood. Further, the results suggest that an increase in omega-3 PUFAs decreases symptom severity and improves cognition in the CHR state through modulating effects of complement and coagulation proteins.

DHA alleviates diet-induced skeletal muscle fiber remodeling via FTO/m6A/DDIT4/PGC1α signaling

Background

Obesity leads to a decline in the exercise capacity of skeletal muscle, thereby reducing mobility and promoting obesity-associated health risks. Dietary intervention has been shown to be an important measure to regulate skeletal muscle function, and previous studies have demonstrated the beneficial effects of docosahexaenoic acid (DHA; 22:6 ω-3) on skeletal muscle function. At the molecular level, DHA and its metabolites were shown to be extensively involved in regulating epigenetic modifications, including DNA methylation, histone modifications, and small non-coding microRNAs. However, whether and how epigenetic modification of mRNA such as N6-methyladenosine (m6A) mediates DHA regulation of skeletal muscle function remains unknown. Here, we analyze the regulatory effect of DHA on skeletal muscle function and explore the involvement of m⁶A mRNA modifications in mediating such regulation.

Results

DHA supplement prevented HFD-induced decline in exercise capacity and conversion of muscle fiber types from slow to fast in mice. DHA-treated myoblasts display increased mitochondrial biogenesis, while slow muscle fiber formation was promoted through DHA-induced expression of PGC1α. Further analysis of the associated molecular mechanism revealed that DHA enhanced expression of the fat mass and obesity-associated gene (FTO), leading to reduced m6A levels of DNA damage-induced transcript 4 (Ddit4). Ddit4 mRNA with lower m6A marks could not be recognized and bound by the cytoplasmic m6A reader YTH domain family 2 (YTHDF2), thereby blocking the decay of Ddit4 mRNA. Accumulated Ddit4 mRNA levels accelerated its protein translation, and the consequential increased DDIT4 protein abundance promoted the expression of PGC1α, which finally elevated mitochondria biogenesis and slow muscle fiber formation.

Conclusions

DHA promotes mitochondrial biogenesis and skeletal muscle fiber remodeling via FTO/m⁶A/DDIT4/PGC1α signaling, protecting against obesity-induced decline in skeletal muscle function.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01239-w.

Perspectives and challenges of epigenetic determinants of childhood obesity: A systematic review

The tremendous increase in childhood obesity prevalence over the last few decades cannot merely be explained by genetics and evolutionary changes in the genome, implying that gene-environment interactions, such as epigenetic modifications, likely play a major role. This systematic review aims to summarize the evidence of the association between epigenetics and childhood obesity. A literature search was performed via PubMed and Scopus engines using a combination of terms related to epigenetics and pediatric obesity. Articles studying the association between epigenetic mechanisms (including DNA methylation and hydroxymethylation, non-coding RNAs, and chromatin and histones modification) and obesity and/or overweight (or any related anthropometric parameters) in children (0-18 years) were included. The risk of bias was assessed with a modified Newcastle-Ottawa scale for non-randomized studies. One hundred twenty-one studies explored epigenetic changes related to childhood obesity. DNA methylation was the most widely investigated mechanism (N = 101 studies), followed by non-coding RNAs (N = 19 studies) with evidence suggestive of an association with childhood obesity for DNA methylation of specific genes and microRNAs (miRNAs). One study, focusing on histones modification, was identified. Heterogeneity of findings may have hindered more insights into the epigenetic changes related to childhood obesity. Gaps and challenges that future research should face are herein described.

Epigenetic Reprogramming Mediated by Maternal Diet Rich in Omega-3 Fatty Acids Protects From Breast Cancer Development in F1 Offspring

Diets rich in omega-3 fatty acids (FA) have been associated with lowered risks of developing certain types of cancers. We earlier reported that in transgenic mice prone to develop breast cancer (BCa), a diet supplemented with canola oil, rich in omega-3-rich FA (as opposed to an omega-6-rich diet containing corn oil), reduced the risk of developing BCa, and also significantly reduced the incidence of BCa in F1 offspring. To investigate the underlying mechanisms of the cancer protective effect of canola oil in the F1 generation, we designed and performed the present study with the same diets using BALB/c mice to remove any possible effect of the transgene. First, we observed epigenetic changes at the genome-wide scale in F1 offspring of mothers fed diets containing omega-3 FAs, including a significant increase in acetylation of H3K18 histone mark and a decrease in H3K4me2 mark on nucleosomes around transcription start sites. These epigenetic modifications contribute to differential gene expressions associated with various pathways and molecular mechanisms involved in preventing cancer development, including p53 pathway, G2M checkpoint, DNA repair, inflammatory response, and apoptosis. When offspring mice were exposed to 7,12-Dimethylbenz(a)anthracene (DMBA), the group of mice exposed to a canola oil (with omega 3 FAs)-rich maternal diet showed delayed mortality, increased survival, reduced lateral tumor growth, and smaller tumor size. Remarkably, various genes, including BRCA genes, appear to be epigenetically re-programmed to poise genes to be ready for a rapid transcriptional activation due to the canola oil-rich maternal diet. This ability to respond rapidly due to epigenetic potentiation appeared to contribute to and promote protection against breast cancer after carcinogen exposure.

Polycystic Ovary Syndrome in Insulin-Resistant Adolescents with Obesity: The Role of Nutrition Therapy and Food Supplements as a Strategy to Protect Fertility

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in young reproductive-aged women. PCOS is often associated with obesity and impairs reproductive health. Even though several theories have been proposed to explain the pathogenic mechanism of PCOS, the role of insulin resistance (IR) as a key etiological component, independently of (but amplified by) obesity, is well recognized. The consequent hyperinsulinemia activates excessive ovarian androgen production, leading to PCOS. Additionally, the state of chronic inflammation related to obesity impacts ovarian physiology due to insulin sensitivity impairment. The first-line treatment for adolescents with obesity and PCOS includes lifestyle changes; personalized dietary interventions; and, when needed, weight loss. Medical nutrition therapy (MNT) and the use of specific food supplements in these patients aim at improving symptoms and signs, including insulin resistance and metabolic and reproductive functions. The purpose of this narrative review is to present and discuss PCOS in adolescents with obesity, its relationship with IR and the role of MNT and food supplements in treatment. Appropriate early dietary intervention for the management of adolescents with obesity and PCOS should be considered as the recommended approach to restore ovulation and to protect fertility.

Association of telomere length and telomerase methylation with n-3 fatty acids in preschool children with obesity

BACKGROUND

Telomeres play a crucial role in cellular survival and its length is a predictor for onset of chronic non-communicable diseases. Studies on association between telomeres and obesity in children have brought discrepant results and the underlying mechanisms and influential factors are to be elucidated. This study aimed to investigate changes in telomere length and telomerase reverse transcriptase (TERT) DNA methylation, and further to determine their correlation with n-3 polyunsaturated fatty acids (PUFAs) in preschool children with obesity.

METHODS

Forty-six preschool children with obesity aged 3 to 4 years were included in the study, with equal numbers of age- and gender-matched children with normal weight as control. Leukocyte telomere length was determined by the ratio of telomeric product and single copy gene obtained using real-time qPCR. DNA methylation of TERT promoter was analyzed by bisulfite sequencing. Fatty acids in erythrocytes were measured by gas chromatography with a total of 15 fatty acids analyzed. The total saturated fatty acids (SFAs), total n-6 PUFAs, total n-3 PUFAs, and the ratio of arachidonic acid (AA) to docosahexaenoic acid (DHA) were calculated. Then the correlation between leukocyte telomere length, TERT promoter methylation and fatty acids was determined.

RESULTS

In preschool children with obesity, leukocyte telomeres were shortened and had a negative association with the body mass index. The methylated fractions in 13 of 25 CpG sites in the TERT promoter were increased by approximately 3 to 35% in the children with obesity compared to the normal weight children. Erythrocyte lauric acid and total SFAs, lenoleic acid and total n-6 PUFAs were higher, and DHA was lower in the children with obesity than those in the children with normal weight. Correlative analysis showed that leukocyte telomere length had a positive association with total SFAs and DHA, and a negative association with the AA/DHA ratio. However, no association between erythrocyte DHA and the TERT promoter methylation was found.

CONCLUSION

These data indicate that the reduced body DHA content and increased AA/DHA ratio may be associated with shortened leukocyte telomeres in child obesity, which is probably not involved in the TERT promoter methylation.

MiR-130a-3p Has Protective Effects in Alzheimer's Disease via Targeting DAPK1

The present study investigated the role and potential mechanisms of miR-130a-3p in AD. SH-SY5Y cells were treated with Aβ 1-42 to construct AD cell models. APP/PS1 mice were used for the animal experiments.  MiR-130a-3p was downregulated in Aβ-induced SH-SY5Y cells. Overexpression of miR-130a-3p attenuates Aβ induced SH-SY5Y cell apoptosis. Low miR-130a-3p expression was detected in the hippocampus tissues of AD mice. The Morris water maze (MWM) results indicated that miR-130a-3p upregulation reduced the escape latency time and increased the time of AD mice spent in the target quadrant. DAPK1 was the target gene of miR-130a-3p. High DAPK1 mRNA level was detected in Aβ treated PC 12 cells and in the hippocampus tissues of AD mice. It was concluded that overexpression of miR-130a-3p may attenuate Aβ-induced neurotoxicity and improve the cognitive function of AD mice via targeting DAPK1.

Omega-3 polyunsaturated fatty acids prevent obesity by improving tricarboxylic acid cycle homeostasis

The beneficial effects of omega-3 polyunsaturated fatty acids (n-3 PUFAs) on preventing obesity are well known; however, the underlying mechanism by which n-3 PUFAs influence tricarboxylic acid (TCA) cycle under obesity remains unclear. We randomly divided male C57BL/6 mice into 5 groups (n=10) and fed for 12 weeks as follows: mice fed a normal diet (Con, 10% kcal); mice fed a high-fat diet (HFD, lard, 60% kcal); and mice fed a high-fat diet (60% kcal) substituting half the lard with safflower oil (SO), safflower oil and fish oil (SF) and fish oil (FO), respectively. Then we treated HepG2 cells with palmitic acid and DHA for 24 h. We found that body weight in FO group was significantly lower than it in HFD and SO groups. N-3 PUFAs reduced the transcription and translation of TCA cycle enzymes, including IDH1, IDH2, SDHA, FH and MDH2, to enhance mitochondrial function in vivo and vitro. DHA significantly inhibited protein expression of the mTORC1 signaling pathway, increased p-AKT protein expression to alleviate insulin resistance and improved mitochondrial oxygen consumption rate and glycolysis ability in HepG2 cells. In addition, the expressions of IDH2 and SDHB were reduced by rapamycin. N-3 PUFAs could prevent obesity by improving TCA cycle homeostasis and mTORC1 signaling pathway may be upstream.

Maternal dietary deficiency of n-3 fatty acids affects metabolic and epigenetic phenotypes of the developing fetus

Polyunsaturated fatty acids (PUFAs) play multiple physiological roles. They regulate the structure and function of cell membranes and cell growth and proliferation, and apoptosis. In addition, PUFAs are involved in cellular signaling, gene expression and serve as precursors to second messengers such as eicosanoids, docosanoids etc. and regulate several physiological processes including placentation, inflammation, immunity, angiogenesis, platelet function, synaptic plasticity, neurogenesis, bone formation, energy homeostasis, pain sensitivity, stress, and cognitive functions. Linoleic acid, 18:2n-6 (LA) and alpha-linolenic acid, 18:3n-3 (ALA) are the two essential fatty acids obtained from the diets and subsequently their long-chain polyunsaturated fatty acids (LCPUFAs) are accumulated in the body. The maternal plasma LCPUFAs especially accumulated in larger amounts in the brain during the third trimester of pregnancy via the placenta and postnatally from mother's breast milk. Various studies, including ours, suggest PUFA's important role in placentation, as well as in growth and development of the offspring. However, intakes of maternal n-3 PUFAs during pregnancy and lactation are much lower in India compared with the Western population. In India, n-3 fatty acid status is further reduced by higher intake of n-6 PUFA rich oils and trans fats. More data on the impacts of long term maternal n-3 PUFA deficiency on placental structure and function, gene expression, epigenetic changes and resultant cognitive function of fetus & infants are emerging. This review summarizes the impacts of n-3 PUFA deficiency in utero on fetal growth and development, adiposity, energy metabolism, musculoskeletal development, and epigenetic changes in feto-placental axis from the recently available pre-clinical and clinical data.

Lipid-Induced Mechanisms of Metabolic Syndrome

Metabolic syndrome (MetS) has a worldwide tendency to increase and depends on many components, which explains the complexity of diagnosis, approaches to the prevention, and treatment of this pathology. Insulin resistance (IR) is the crucial cause of the MetS pathogenesis, which develops against the background of abdominal obesity. In light of recent evidence, it has been shown that lipids, especially fatty acids (FAs), are important signaling molecules that regulate the signaling pathways of insulin and inflammatory mediators. On the one hand, the lack of n-3 polyunsaturated fatty acids (PUFAs) in the body leads to impaired molecular mechanisms of glucose transport, the formation of unresolved inflammation. On the other hand, excessive formation of free fatty acids (FFAs) underlies the development of oxidative stress and mitochondrial dysfunction in MetS. Understanding the molecular mechanisms of the participation of FAs and their metabolites in the pathogenesis of MetS will contribute to the development of new diagnostic methods and targeted therapy for this disease. The purpose of this review is to highlight recent advances in the study of the effect of fatty acids as modulators of insulin response and inflammatory process in the pathogenesis and treatment for MetS.