Epigenetics and obesity

The role of genetic and epigenetic GNAS alterations in the development of early-onset obesity

BACKGROUND

GNAS (guanine nucleotide-binding protein, alpha stimulating) is an imprinted gene that encodes Gsα, the α subunit of the heterotrimeric stimulatory G protein. This subunit mediates the signalling of a diverse array of G protein-coupled receptors (GPCRs), including the melanocortin 4 receptor (MC4R) that serves a pivotal role in regulating food intake, energy homoeostasis, and body weight. Genetic or epigenetic alterations in GNAS are known to cause pseudohypoparathyroidism in its different subtypes and have been recently associated with isolated, early-onset, severe obesity. Given the diverse biological functions that Gsα serves, multiple molecular mechanisms involving various GPCRs, such as MC4R, β2- and β3-adrenoceptors, and corticotropin-releasing hormone receptor, have been implicated in the pathophysiology of severe, early-onset obesity that results from genetic or epigenetic GNAS changes.

SCOPE OF REVIEW

This review examines the structure and function of GNAS and provides an overview of the disorders that are caused by defects in this gene and may feature early-onset obesity. Moreover, it elucidates the potential molecular mechanisms underlying Gsα deficiency-induced early-onset obesity, highlighting some of their implications for the diagnosis, management, and treatment of this complex condition.

MAJOR CONCLUSIONS

Gsα deficiency is an underappreciated cause of early-onset, severe obesity. Therefore, screening children with unexplained, severe obesity for GNAS defects is recommended, to enhance the molecular diagnosis and management of this condition.

Racial Disparities in Methylation of NRF1, FTO, and LEPR Gene in Childhood Obesity

Childhood obesity has affected the health of millions of children around the world despite vigorous efforts by health experts. The obesity epidemic in the United States has disproportionately afflicted certain racial and ethnic minority groups. African American children are more likely than other children to have obesity-related risk factors such as hyperlipidemia, diabetes, cardiovascular disease, and coronavirus disease (COVID-19). For the reduction in obesity-related health inequalities to be successful, it is essential to identify the variables affecting various groups. A notable advancement in epigenetic biology has been made over the past decade. Epigenetic changes like DNA methylation impact on many genes associated with obesity. Here, we evaluated the DNA methylation levels of the genes NRF1, FTO, and LEPR from the saliva of children using real-time quantitative PCR-based multiplex MethyLight technology. ALU was used as a reference gene, and the Percent of Methylated Reference (PMR) was calculated for each sample. European American children showed a significant increase in PMR of NRF1 and FTO in overweight/obese participants compared to normal weight, but not in African American children. After adjusting for maternal education and annual family income by regression analysis, the PMR of NRF1 and FTO was significantly associated with BMI z-score only in European American children. While for the gene LEPR, African American children had higher methylation in normal weight participants as compared to overweight/obese and no methylation difference in European American children. The PMR of LEPR was significantly negative associated with the obesity measures only in African American children. These findings contribute to a race-specific link between NRF1, FTO, and LEPR gene methylation and childhood obesity.

Adipogenesis of ear mesenchymal stem cells (EMSCs): adipose biomarker-based assessment of genetic variation, adipocyte function, and brown/brite differentiation

Ear mesenchymal stem cells (EMSCs) have been investigated to differentiate into adipocytes, chondrocytes, and muscle cells in vitro. However, the factors controlling adipogenesis of this stem cell population in vitro, function, and type of adipocytes raised from them are still unclear. Here we found that genetics have a modest effect on adipogenic capacity of EMSCs. Adipocytes differentiated from EMSCs have a potential function in lipid metabolism as indicated by expression of lipogenic genes and this function of EMSC adipocytes is regulated by genetics. EMSCs failed to be differentiated into brite/brown adipocytes due to their lack of a thermogenic program, but adipocytes raised from EMSCs showed a fate of white adipocytes. Overall, our data suggest that EMSCs differentiate into functional white adipocytes in vitro and this is genetic-dependent.

Transcriptional characterization of subcutaneous adipose tissue in obesity affected women highlights metabolic dysfunction and implications for lncRNAs

Obesity is a complex disease with multifactorial causes, and its prevalence is becoming a serious health crisis. For this reason, there is a crucial need to identify novel targets and players. With this aim in mind, we analyzed via RNA-sequencing the subcutaneous adipose tissue of normal weight and obesity-affected women, highlighting the differential expression in the two tissues. We specifically focused on long non-coding RNAs, as 6 of these emerged as dysregulated in the diseased-tissue (COL4A2-AS2, RPS21-AS, PELATON, ITGB2-AS1, ACER2-AS and CTEPHA1). For each of them, we performed both a thorough in silico dissection and in vitro validation, to predict their function during adipogenesis. We report the lncRNAs expression during adipose derived stem cells differentiation to adipocytes as model of adipogenesis and their potential modulation by adipogenesis-related transcription factors (C/EBPs and PPARγ). Moreover, inhibiting CTEPHA1 expression we investigated its impact on adipogenesis-related transcription factors, showing its significative dysregulation of C/EBPα expression. Lastly, we dissected the subcellular localization, pathway involvement and disease-correlation for coding differentially expressed genes. Together, these findings highlight a transcriptional deregulation at the basis of obesity, impacted by both coding and long non-coding RNAs.

Adipose Tissue Hypoxia Correlates with Adipokine Hypomethylation and Vascular Dysfunction

Obesity is characterized by the accumulation of dysfunctional adipose tissues, which predisposes to cardiometabolic diseases. Our previous in vitro studies demonstrated a role of hypoxia in inducing adipokine hypomethylation in adipocytes. We sought to examine this mechanism in visceral adipose tissues (VATs) from obese individuals and its correlation with cardiometabolic risk factors. We propose an involvement of the hypoxia-inducible factor, HIF1α, and the DNA hydroxymethylase, TET1. Blood samples and VAT biopsies were obtained from obese and non-obese subjects (n = 60 each) having bariatric and elective surgeries, respectively. The analyses of VAT showed lower vascularity, and higher levels of HIF1α and TET1 proteins in the obese subjects than controls. Global hypomethylation and hydroxymethylation were observed in VAT from obese subjects along with promoter hypomethylation of several pro-inflammatory adipokines. TET1 protein was enriched near the promotor of the hypomethylated adipokines. The average levels of adipokine methylation correlated positively with vascularity and arteriolar vasoreactivity and negatively with protein levels of HIF1α and TET1 in corresponding VAT samples, serum and tissue inflammatory markers, and other cardiometabolic risk factors. These findings suggest a role for adipose tissue hypoxia in causing epigenetic alterations, which could explain the increased production of adipocytokines and ultimately, vascular dysfunction in obesity.

Role of long non-coding RNAs in adipogenesis: State of the art and implications in obesity and obesity-associated diseases

Obesity is an evolutionary, chronic, and relapsing disease that consists of a pathological accumulation of adipose tissue able to increase morbidity for high blood pressure, type 2 diabetes, metabolic syndrome, and obstructive sleep apnea in adults, children, and adolescents. Despite intense research over the last 20 years, obesity remains today a disease with a complex and multifactorial etiology. Recently, long non-coding RNAs (lncRNAs) are emerging as interesting new regulators as different lncRNAs have been found to play a role in early and late phases of adipogenesis and to be implicated in obesity-associated complications onset. In this review, we discuss the most recent advances on the role of lncRNAs in adipocyte biology and in obesity-associated complications. Indeed, more and more researchers are focusing on investigating the underlying roles that these molecular modulators could play. Even if a significant number of evidence is correlation-based, with lncRNAs being differentially expressed in a specific disease, recent works are now focused on deeply analyzing how lncRNAs can effectively modulate the disease pathogenesis onset and progression. LncRNAs possibly represent new molecular markers useful in the future for both the early diagnosis and a prompt clinical management of patients with obesity.

The dual nature of obesity in metabolic programming: quantity versus quality of adipose tissue

The global prevalence of obesity has been rising at an alarming rate, accompanied by an increase in both childhood and maternal obesity. The concept of metabolic programming is highly topical, and in this context, describes a predisposition of offspring of obese mothers to the development of obesity independent of environmental factors. Research published in this issue of Clinical Science conducted by Litzenburger and colleagues (Clin. Sci. (Lond.) (2020) 134, 921-939) have identified sex-dependent differences in metabolic programming and identify putative signaling pathways involved in the differential phenotype of adipose tissue between males and females. Delineating the distinction between metabolically healthy and unhealthy obesity is a topic of emerging interest, and the precise nature of adipocytes are key to pathogenesis, independent of adipose tissue volume.

Metabolic and Energy Imbalance in Dysglycemia-Based Chronic Disease

Metabolic flexibility is the ability to efficiently adapt metabolism based on nutrient availability and requirement that is essential to maintain homeostasis in times of either caloric excess or restriction and during the energy-demanding state. This regulation is orchestrated in multiple organ systems by the alliance of numerous metabolic pathways under the master control of the insulin-glucagon-sympathetic neuro-endocrine axis. This, in turn, regulates key metabolic enzymes and transcription factors, many of which interact closely with and culminate in the mitochondrial energy generation machinery. Metabolic flexibility is compromised due to the continuous mismatch between availability and intake of calorie-dense foods and reduced metabolic demand due to sedentary lifestyle and age-related metabolic slowdown. The resultant nutrient overload leads to mitochondrial trafficking of substrates manifesting as mitochondrial dysfunction characterized by ineffective substrate switching and incomplete substrate utilization. At the systemic level, the manifestation of metabolic inflexibility comprises reduced skeletal muscle glucose disposal rate, impaired suppression of hepatic gluconeogenesis and adipose tissue lipolysis manifesting as insulin resistance. This is compounded by impaired β-cell function and progressively reduced β-cell mass. A consequence of insulin resistance is the upregulation of the mitogen-activated protein kinase pathway leading to a pro-hypertensive, atherogenic, and thrombogenic environment. This is further aggravated by oxidative stress, advanced glycation end products, and inflammation, which potentiates the risk of micro- and macro-vascular complications. This review aims to elucidate underlying mechanisms mediating the onset of metabolic inflexibility operating at the main target organs and to understand the progression of metabolic diseases. This could potentially translate into a pharmacological tool that can manage multiple interlinked conditions of dysglycemia, hypertension, and dyslipidemia by restoring metabolic flexibility. We discuss the breadth and depth of metabolic flexibility and its impact on health and disease.

An Epigenetics-Based, Lifestyle Medicine-Driven Approach to Stress Management for Primary Patient Care: Implications for Medical Education

Over 75% of patients in the primary care setting present with stress-related complaints. Curiously, patients and health care providers all too often see stress as a relatively benign sequela of many common illnesses such as heart disease, cancer, lung disease, dementia, diabetes, and mental illness. Unfortunately, various day-to-day lifestyle choices and environmental factors, unrelated to the presence of any disease, can cause stress sufficient to contribute to the development of various diseases/disorders and suboptimal health. There is evidence suggesting that counseling in stress management-oriented therapeutic interventions (as offered by lifestyle medicine-oriented practitioners) may prevent or reduce the onset, severity, duration, and/or overall burden of stress-related illnesses. Such counseling often involves considerations such as the patient's nutrition, physical activity, interest in/capacity to meditate, drug abuse/cessation, and so on. Unfortunately, lifestyle medicine-oriented approaches to stress management are rarely offered in primary care-the patient care arena wherein such counseling would likely be best received by patients. Would health care outcomes improve if primary care providers offered counseling in both stress management and positive lifestyle choices? The purpose of this article is to provide both primary care practitioners and educators in health care training programs with an introductory overview of epigenetics. An emerging field of science offering insights into how factors such as stress and lifestyle choices interact with our genes in ways that can both positively and negatively impact the various micro (eg, cellular) through macro (eg, physiologic, pathophysiologic) processes that determine our tendencies toward illness or wellness. A deeper understanding of epigenetics, as provided herein, should enable primary care providers and medical educators to more confidently advocate for the primary benefits associated with counseling in both stress reduction and the pursuit of healthy lifestyle choices.

Weighing the Impact of Diet and Lifestyle on Female Reproductive Function

BACKGROUND

In the last years, several scientific societies and expert groups focused on the role played by nutritional factors, lifestyle and excess of body fat in interfering with female reproduction and fertility. In many studies a confounding factor is represented by polycystic ovary syndrome (PCOS) which is one of the major causes of infertility where genetic and family history are certainly playing a role, together with lifestyle and nutritional factors.

METHODS

In an attempt to define "the optimal fertility diet", we consider the role played by Mediterranean lifestyle and some macronutrients (animal and vegetable proteins) on ovulatory disorders and female fertility also considering some new visions derived from randomized trials of lifestyle programs in obese infertile women asking for in vitro fertilization or alternative assisted reproduction technologies.

RESULTS

Several reports are in favor of an increased consumption of either proteins or low-glycemic index carbohydrates to improve ovulatory disorders and female fertility. In studies concerning infertile women undergoing assisted reproduction, either structured exercise sessions and dietary intervention programs seem to be effective in improving menstrual cycles and fertility as demonstrated by the increased rate of natural conceptions.

CONCLUSION

The findings of this review confirm the important impact of Mediterranean diet and lifestyle in preserving and improving fertility. However, epigenetic factors are very important in determining fertility rate, but genetic background and ethnicity are also playing crucial roles.

Epigenetic regulation of POMC; implications for nutritional programming, obesity and metabolic disease

Proopiomelanocortin (POMC) is a key mediator of satiety. Epigenetic marks such as DNA methylation may modulate POMC expression and provide a biological link between early life exposures and later phenotype. Animal studies suggest epigenetic marks at POMC are influenced by maternal energy excess and restriction, prenatal stress and Triclosan exposure. Postnatal factors including energy excess, folate, vitamin A, conjugated linoleic acid and leptin may also affect POMC methylation. Recent human studies suggest POMC DNA methylation is influenced by maternal nutrition in early pregnancy and associated with childhood and adult obesity. Studies in children propose a link between POMC DNA methylation and elevated lipids and insulin, independent of body habitus. This review brings together evidence from animal and human studies and suggests that POMC is sensitive to nutritional programming and is associated with a wide range of weight-related and metabolic outcomes.

Differential genome-wide DNA methylation patterns in childhood obesity

OBJECTIVE

Exposure to stress during pregnancy may program susceptibility to the development of obesity in offspring. Our goal was to determine whether prenatal maternal stress (PNMS) due to a natural disaster was associated with child obesity, and to compare the DNA methylation profiles in obese versus non-obese children at age 13½ years. Women and their children were involved in the longitudinal natural disaster study-Project Ice Strom, which served as a human model to study PNMS. Blood was collected from 31 children (including five obese children). Infinium HumanMethylation450 BeadChip Array was performed for genome-wide DNA methylation analyses.

RESULTS

Results demonstrated a well-defined obesity-associated genome-wide DNA methylation pattern. There were 277 CpGs, corresponding to 143 genes, were differentially-methylated. IPA analyses revealed 51 canonical pathways, and enrichment of pathways was involved in immune function. Although no significant association was found between PNMS and child obesity, the preliminary data in the study revealed obesity-associated methylation patterns on a genome-wide level in children.

Primers on nutrigenetics and nutri(epi)genomics: Origins and development of precision nutrition

Understanding the relationship between genotype and phenotype is a central goal not just for genetics but also for medicine and biological sciences. Despite outstanding technological progresses, genetics alone is not able to completely explain phenotypes, in particular for complex diseases. Given the existence of a "missing heritability", growing attention has been given to non-mendelian mechanisms of inheritance and to the role of the environment. The study of interaction between gene and environment represents a challenging but also a promising field with high potential for health prevention, and epigenetics has been suggested as one of the best candidate to mediate environmental effects on the genome. Among environmental factors able to interact with both genome and epigenome, nutrition is one of the most impacting. Not just our genome influences the responsiveness to food and nutrients, but vice versa, nutrition can also modify gene expression through epigenetic mechanisms. In this complex picture, nutrigenetics and nutrigenomics represent appealing disciplines aimed to define new prospectives of personalized nutrition. This review introduces to the study of gene-environment interactions and describes how nutrigenetics and nutrigenomics modulate health, promoting or affecting healthiness through life-style, thus playing a pivotal role in modulating the effect of genetic predispositions.

Associations of maternal gestational weight gain with the risk of offspring obesity and body mass index Z scores beyond the mean

PURPOSE

We examined the association of meeting the 2009 Institute of Medicine gestational weight gain (GWG) guidelines with offspring obesity and body mass index Z score (BMIZ) at age six overall and by maternal weight status.

METHODS

Data were from the Infant Feeding Practices Survey II Study (2005-2007) and their Year Six Follow-Up Study (2012). Logistic regression and quantile regression models were used.

RESULTS

Eleven percent of children were obese. Children born to mothers who gained excessive weight during pregnancy had an increased risk of obesity as compared with those born to mothers who gained adequate weight (adjusted odds ratio: 1.67). The association was stronger among normal-weight mothers (adjusted odds ratio: 3.50). Inadequate GWG was not associated with offspring obesity overall or in subsamples by maternal prepregnancy BMI. Children born to mothers who gained excessive weight had higher BMIZ. This distributional association was more pronounced among normal-weight mothers. Children born to obese mothers who gained inadequate weight had lower BMIZ at some percentiles of the BMIZ distribution.

CONCLUSIONS

Excessive GWG was associated with increased risk of offspring obesity and higher BMIZ at age six, whereas inadequate GWG was protective of high BMIZ among children born to obese mothers.

Obesity, body weight regulation and the brain: insights from fMRI

Obesity constitutes a major global health threat. Despite the success of bariatric surgery in delivering sustainable weight loss and improvement in obesity-related morbidity, effective non-surgical treatments are urgently needed, necessitating an increased understanding of body weight regulation. Neuroimaging studies undertaken in people with healthy weight, overweight, obesity and following bariatric surgery have contributed to identifying the neurophysiological changes seen in obesity and help increase our understanding of the mechanisms driving the favourable eating behaviour changes and sustained weight loss engendered by bariatric surgery. These studies have revealed a key interplay between peripheral metabolic signals, homeostatic and hedonic brain regions and genetics. Findings from brain functional magnetic resonance imaging (fMRI) studies have consistently associated obesity with an increased motivational drive to eat, increased reward responses to food cues and impaired food-related self-control processes. Interestingly, new data link these obesity-associated changes with structural and connectivity changes within the central nervous system. Moreover, emerging data suggest that bariatric surgery leads to neuroplastic recovery. A greater understanding of the interactions between peripheral signals of energy balance, the neural substrates that regulate eating behaviour, the environment and genetics will be key for the development of novel therapeutic strategies for obesity. This review provides an overview of our current understanding of the pathoaetiology of obesity with a focus upon the role that fMRI studies have played in enhancing our understanding of the central regulation of eating behaviour and energy homeostasis.

Epigenetic changes in mesenchymal stem cells differentiation

Epigenetic factors are known to play a major role in determining stem cell fate and differentiation. Mesenchymal stem cells are the most studied population of stem cells due to their important applications in experimental biology and regenerative medicine. After a brief overview on mesenchymal stem cells, this review aims to highlight the role of epigenetic changes on mesenchymal stem cells biology and differentiation protocols with a focus on osteocytic, chondrocytic and adipocytic differentiation. Chromatin remodeling, DNA methylation, histone modifications and miRNA expression will be investigated. The impact of epigenetics on transdifferentiation of mesenchymal stem cells will also be discussed. Indeed, epigenetic modulation appears to constitute a promising experimental target in stem cell basic and translational research.

From genetics and epigenetics to the future of precision treatment for obesity

Obesity has become a major global health problem, epitomized by excess accumulation of body fat resulting from an imbalance between energy intake and expenditure. The treatments for obesity range from modified nutrition and additional physical activity, to drugs or surgery. But the curative effect of each method seems to vary between individuals. With progress in the genetics and epigenetics of obesity, personalization of the clinical management of obesity may be at our doorstep. This review presents an overview of our current understanding of the genetics and epigenetics of obesity and how these findings influence responses to treatments. As bariatric surgery is the most effective long-term treatment for morbid obesity, we pay special attention to the association between genetic factors and clinical outcomes of bariatric surgery. Finally, we discuss the prospects for precision obesity treatment.

Mechanisms Regulating Stemness and Differentiation in Embryonal Carcinoma Cells

Just over ten years have passed since the seminal Takahashi-Yamanaka paper, and while most attention nowadays is on induced, embryonic, and cancer stem cells, much of the pioneering work arose from studies with embryonal carcinoma cells (ECCs) derived from teratocarcinomas. This original work was broad in scope, but eventually led the way for us to focus on the components involved in the gene regulation of stemness and differentiation. As the name implies, ECCs are malignant in nature, yet maintain the ability to differentiate into the 3 germ layers and extraembryonic tissues, as well as behave normally when reintroduced into a healthy blastocyst. Retinoic acid signaling has been thoroughly interrogated in ECCs, especially in the F9 and P19 murine cell models, and while we have touched on this aspect, this review purposely highlights how some key transcription factors regulate pluripotency and cell stemness prior to this signaling. Another major focus is on the epigenetic regulation of ECCs and stem cells, and, towards that end, this review closes on what we see as a new frontier in combating aging and human disease, namely, how cellular metabolism shapes the epigenetic landscape and hence the pluripotency of all stem cells.

Obesity: epigenetic aspects

Epigenetics, defined as inheritable and reversible phenomena that affect gene expression without altering the underlying base pair sequence has been shown to play an important role in the etiopathogenesis of obesity. Obesity is associated with extensive gene expression changes in tissues throughout the body. Epigenetics is emerging as perhaps the most important mechanism through which the lifestyle-choices we make can directly influence the genome. Considerable epidemiological, experimental and clinical data have been amassed showing that the risk of developing disease in later life is dependent on early life conditions, mainly operating within the normative range of developmental exposures. In addition to the 'maternal' interactions, there has been increasing interest in the epigenetic mechanisms through which 'paternal' influences on offspring development can be achieved. Nutrition, among many other environmental factors, is a key player that can induce epigenetic changes not only in the directly exposed organisms but also in subsequent generations through the transgenerational inheritance of epigenetic traits. Overall, significant progress has been made in the field of epigenetics and obesity and the first potential epigenetic markers for obesity that could be detected at birth have been identified. Fortunately, epigenetic phenomena are dynamic and rather quickly reversible with intensive lifestyle changes. This is a very promising and sustainable resolution to the obesity pandemic.

The Impact of Epigenetics on Mesenchymal Stem Cell Biology

Changes in epigenetic marks are known to be important regulatory factors in stem cell fate determination and differentiation. In the past years, the investigation of the epigenetic regulation of stem cell biology has largely focused on embryonic stem cells (ESCs). Contrarily, less is known about the epigenetic control of gene expression during differentiation of adult stem cells (AdSCs). Among AdSCs, mesenchymal stem cells (MSCs) are the most investigated stem cell population because of their enormous potential for therapeutic applications in regenerative medicine and tissue engineering. In this review, we analyze the main studies addressing the epigenetic changes in MSC landscape during in vitro cultivation and replicative senescence, as well as follow osteocyte, chondrocyte, and adipocyte differentiation. In these studies, histone acetylation, DNA methylation, and miRNA expression are among the most investigated phenomena. We describe also epigenetic changes that are associated with in vitro MSC trans-differentiation. Although at the at initial stage, the epigenetics of MSCs promise to have profound implications for stem cell basic and applied research. J. Cell. Physiol. 231: 2393-2401, 2016. © 2016 Wiley Periodicals, Inc.

Epigenomic elements analyses for promoters identify ESRRG as a new susceptibility gene for obesity-related traits

OBJECTIVES

With ENCODE epigenomic data and results from published genome-wide association studies (GWASs), we aimed to find regulatory signatures of obesity genes and discover novel susceptibility genes.

METHODS

Obesity genes were obtained from public GWAS databases and their promoters were annotated based on the regulatory element information. Significantly enriched or depleted epigenomic elements in the promoters of obesity genes were evaluated and all human genes were then prioritized according to the existence of the selected elements to predict new candidate genes. Top-ranked genes were subsequently applied to validate their associations with obesity-related traits in three independent in-house GWAS samples.

RESULTS

We identified RAD21 and EZH2 as over-represented, and STAT2 (signal transducer and activator of transcription 2) and IRF3 (interferon regulatory transcription factor 3) as depleted transcription factors. Histone modification of H3K9me3 and chromatin state segmentation of 'poised promoter' and 'repressed' were over-represented. All genes were prioritized and we selected the top five genes for validation at the population level. Combining results from the three GWAS samples, rs7522101 in ESRRG (estrogen-related receptor-γ) remained significantly associated with body mass index after multiple testing corrections (P=7.25 × 10(-5)). It was also associated with β-cell function (P=1.99 × 10(-3)) and fasting glucose level (P<0.05) in the meta-analyses of glucose and insulin-related traits consortium (MAGIC) data set.Cnoclusions:In summary, we identified epigenomic characteristics for obesity genes and suggested ESRRG as a novel obesity-susceptibility gene.

The dangerous link between childhood and adulthood predictors of obesity and metabolic syndrome

The purpose of this review is to evaluate whether some risk factors in childhood work as significant predictors of the development of obesity and the metabolic syndrome in adulthood. These factors include exposures to risk factors in the prenatal period, infancy and early childhood, as well as other socio-demographic variables. We searched articles of interest in PubMed using the following terms: 'predictors AND obesity OR Metabolic syndrome AND (children OR adolescents) AND (dyslipidemia OR type 2 diabetes OR atherosclerosis OR hypertension OR hypercholesterolemia OR cardiovascular disease)' AND genetic OR epigenetic. Maternal age, smoking and weight gain during pregnancy, parental body mass index, birth weight, childhood growth patterns (early rapid growth and early adiposity rebound), childhood obesity and the parents' employment have a role in early life. Furthermore, urbanization, unhealthy diets, increasingly sedentary lifestyles and genetic/epigenetic variants play a role in the persistence of obesity in adulthood. Health promotion programs/agencies should consider these factors as reasonable targets to reduce the risk of adult obesity. Moreover, it should be a clinical priority to correctly identify obese children who are already affected by metabolic comorbidities.

Miniature Swine for Preclinical Modeling of Complexities of Human Disease for Translational Scientific Discovery and Accelerated Development of Therapies and Medical Devices

Noncommunicable diseases, including cardiovascular disease, diabetes, chronic respiratory disease, and cancer, are the leading cause of death in the world. The cost, both monetary and time, of developing therapies to prevent, treat, or manage these diseases has become unsustainable. A contributing factor is inefficient and ineffective preclinical research, in which the animal models utilized do not replicate the complex physiology that influences disease. An ideal preclinical animal model is one that responds similarly to intrinsic and extrinsic influences, providing high translatability and concordance of preclinical findings to humans. The overwhelming genetic, anatomical, physiological, and pathophysiological similarities to humans make miniature swine an ideal model for preclinical studies of human disease. Additionally, recent development of precision gene-editing tools for creation of novel genetic swine models allows the modeling of highly complex pathophysiology and comorbidities. As such, the utilization of swine models in early research allows for the evaluation of novel drug and technology efficacy while encouraging redesign and refinement before committing to clinical testing. This review highlights the appropriateness of the miniature swine for modeling complex physiologic systems, presenting it as a highly translational preclinical platform to validate efficacy and safety of therapies and devices.

The effect of polyunsaturated fatty acids on obesity through epigenetic modifications

BACKGROUND AND PURPOSE

In recent years it has been demonstrated that polyunsaturated fatty acids (PUFA) have anti-inflammatory and as regulators of lipid metabolism. However, the epigenomic mechanisms involved in these processes are not known in depth. The aim of this review was to describe the scientific evidence supports that regular consumption of PUFA may reduce obesity and overweight by altering epigenetic marks.

MATERIAL AND METHODS

A search of recent publications was carried out in human clinical trials, as well as animal model and in vitro experiments.

RESULTS

Exist a possible therapeutic effect of PUFAs on the prevention and development of obesity due to their ability to reversively modify the methylation of the promoters of genes associated with lipid metabolism and to modulate the activity of certain microRNAs.

CONCLUSIONS

A better knowledge and understanding of the PUFAs role in epigenetic regulation of obesity is possible with the current published results. The PUFAs may modulate the promotor epigenetic marks in several adipogenic genes and regulate the expression of several miRNAs.

Multiple conditions: exploring literature from the consumer perspective in Australia

BACKGROUND

Following a workshop with people with multiple conditions, the Chronic Illness Alliance undertook a literature review to explore current literature about multiple conditions.

METHODS

The literature search was performed using Medline, CINAHL, Google Scholar and Cochrane Library employing an extensive list of search terms and limited to English language journals between 1999 and 2009. Inclusion criteria for articles were those articles focussing on issues identified by consumers with more than one chronic illness and the health services working with them.

RESULTS

The results reported in this article are definitions of multiple conditions, safety and quality of services, risks and benefits of treatments for multiple and rare conditions and coordination of services.

DISCUSSION

The impact of multiple conditions or multimorbidities on health services has been researched internationally and identifies the barriers to good health care when multiple conditions are not recognized. While the issues for consumers with more than one condition are not well recognized, the barriers identified by the literature are of great importance to consumers.

CONCLUSIONS

This review demonstrates that services and policies in Australia require specific reforms to better meet the needs of people with multiple conditions.

Genetic & epigenetic approach to human obesity

Obesity is an important clinical and public health challenge, epitomized by excess adipose tissue accumulation resulting from an imbalance in energy intake and energy expenditure. It is a forerunner for a variety of other diseases such as type-2-diabetes (T2D), cardiovascular diseases, some types of cancer, stroke, hyperlipidaemia and can be fatal leading to premature death. Obesity is highly heritable and arises from the interplay of multiple genes and environmental factors. Recent advancements in Genome-wide association studies (GWAS) have shown important steps towards identifying genetic risks and identification of genetic markers for lifestyle diseases, especially for a metabolic disorder like obesity. According to the 12th Update of Human Obesity Gene Map there are 253 quantity trait loci (QTL) for obesity related phenotypes from 61 genome wide scan studies. Contribution of genetic propensity of individual ethnic and racial variations in obesity is an active area of research. Further, understanding its complexity as to how these variations could influence ones susceptibility to become or remain obese will lead us to a greater understanding of how obesity occurs and hopefully, how to prevent and treat this condition. In this review, various strategies adapted for such an analysis based on the recent advances in genome wide and functional variations in human obesity are discussed.

Intraindividual somatic variations in MTHFR gene polymorphisms in relation to colon cancer

AIM

MTHFR mediates the one carbon metabolism pathway. Two common genetic variants, C677T and A1298C, of MTHFR are associated with number of human diseases, including cancer, as well as being involved in the modulation of therapy outcome to antifolate drugs. To understand the distribution pattern of SNPs among different tissues of an individual, we examined MTHFR polymorphisms in normal and colon cancer tissues and compared the genotype frequencies in peripheral blood samples.

MATERIALS & METHODS

DNA was isolated from tumor tissue and matched normal tissues from 155 colon cancer patients. These samples as well as DNA from blood samples of the control group (n = 294) were analyzed for MTHFR polymorphisms by PCR-RFLP and confirmed by a direct DNA sequencing method.

RESULTS

Our data suggest that the allele and genotype frequencies of C677T and A1298C were significantly different between tumor tissues and both types of normal tissues. We have established that MTHFR variants that exist in tumor and matched normal tissues of colon cancer patients differ suggesting somatic variation in MTHFR polymorphisms among different tissues of an individual. The MTHFR A1298C polymorphism was associated with risk of colon cancer.

CONCLUSION

Different MTHFR variants may exist in different tissues to maintain physiological functions and may have implications for disease susceptibility and pharmacogenomics based therapies. Original submitted 21 January 2013; Revision submitted 3 January 2014.

Early origins of adult disease: approaches for investigating the programmable epigenome in humans, nonhuman primates, and rodents

According to the developmental origins of health and disease hypothesis, in utero experiences reprogram an individual for immediate adaptation to gestational perturbations, with the sequelae of later-in-life risk of metabolic disease. An altered gestational milieu with resultant adult metabolic disease has been observed in instances of both in utero constraint (e.g., from famine or uteroplacental insufficiency) and overt caloric abundance (e.g., from a maternal high-fat, caloric-dense diet). The commonality of the adult metabolic phenotype begs the question of how diverse in utero experiences (i.e., reprogramming events) converge on common metabolic pathways and how the memory of these events is maintained across the lifespan. We and others have investigated the molecular mechanisms underlying fetal programming and observed that epigenetic modifications to the fetal and placental epigenome accompany these reprogramming events. Based on several lines of emerging data in human and nonhuman primates, it is now felt that modified epigenetic signature--and the histone code in particular--underlies alterations in postnatal gene expression and metabolic pathways central to accurate functioning and maintenance of health. Because of the tissue lineage specificity of many of these modifications, nonhuman primates serve as an apt model system for the capacity to recapitulate human gene expression and regulation during development. This review summarizes recent epigenetic advances using rodent and primate (both human and nonhuman) models during in utero development and contributing to adult diseases later in life.

Variation in ultraviolet radiation and diabetes: evidence of an epigenetic effect that modulates diabetics' lifespan

Background

Published research has shown that month-of-birth variations modulate the incidence of adult human diseases. This article explores diabetes type 2 as one of those diseases. This study uses the death records of approximately 829,000 diabetics (approximately 90% were type-2) born before the year 1945 (and dying between 1979 and 2005) to show that variations in adult lifespan vary with ultraviolet radiation (UVR) at solar cycle peaks (MAX, approximately a three-year period) with less at non-peaks (MIN, approximately an eight-year period). The MAX minus MIN (in years) was our measure of sensitivity (for example, responsiveness) to long-term variations in UVR.

Results

Diabetics were less sensitive than non-diabetics, and ethnic minorities were more sensitive than whites. Diabetic males gained 6.1 years, and females 2.3 years over non-diabetics, with diabetic males gaining an average of 3.8 years over diabetic females. Most variation in lifespan occurred in those conceived around the seasonal equinoxes, suggesting that the human epigenome at conception is especially influenced by rapid variation in UVR. With rapidly decreasing UVR at conception, lifespan decreased in the better-nourished, white, female diabetic population.

Conclusions

Rapidly changing UVR at the equinoxes modulates the expression of an epigenome involving the conservation of energy, a mechanism especially canalized in women. Decreasing UVR at conception and early gestation stimulates energy conservation in persons we consider ‘diabetic’ in today’s environment of caloric surfeit. In the late 19th and early 20th centuries ethnic minorities had poorer nutrition, laborious work, and leaner bodies, and in that environment a calorie-conserving epigenome was a survival advantage. Ethnic minorities with a similar epigenome lived long enough to express diabetes as we define it today and exceeded the lifespan of their non-diabetic contemporaries, while that epigenome in diabetics in the nutritional environment of today is detrimental to lifespan.

Impact of diabetes on cardiovascular disease: an update

Cardiovascular diseases are the most prevalent cause of morbidity and mortality among patients with type 1 or type 2 diabetes. The proposed mechanisms that can link accelerated atherosclerosis and increased cardiovascular risk in this population are poorly understood. It has been suggested that an association between hyperglycemia and intracellular metabolic changes can result in oxidative stress, low-grade inflammation, and endothelial dysfunction. Recently, epigenetic factors by different types of reactions are known to be responsible for the interaction between genes and environment and for this reason can also account for the association between diabetes and cardiovascular disease. The impact of clinical factors that may coexist with diabetes such as obesity, dyslipidemia, and hypertension are also discussed. Furthermore, evidence that justify screening for subclinical atherosclerosis in asymptomatic patients is controversial and is also matter of this review. The purpose of this paper is to describe the association between poor glycemic control, oxidative stress, markers of insulin resistance, and of low-grade inflammation that have been suggested as putative factors linking diabetes and cardiovascular disease.

Microvesicles/exosomes as potential novel biomarkers of metabolic diseases

Biomarkers are of tremendous importance for the prediction, diagnosis, and observation of the therapeutic success of common complex multifactorial metabolic diseases, such as type II diabetes and obesity. However, the predictive power of the traditional biomarkers used (eg, plasma metabolites and cytokines, body parameters) is apparently not sufficient for reliable monitoring of stage-dependent pathogenesis starting with the healthy state via its initiation and development to the established disease and further progression to late clinical outcomes. Moreover, the elucidation of putative considerable differences in the underlying pathogenetic pathways (eg, related to cellular/tissue origin, epigenetic and environmental effects) within the patient population and, consequently, the differentiation between individual options for disease prevention and therapy - hallmarks of personalized medicine - plays only a minor role in the traditional biomarker concept of metabolic diseases. In contrast, multidimensional and interdependent patterns of genetic, epigenetic, and phenotypic markers presumably will add a novel quality to predictive values, provided they can be followed routinely along the complete individual disease pathway with sufficient precision. These requirements may be fulfilled by small membrane vesicles, which are so-called exosomes and microvesicles (EMVs) that are released via two distinct molecular mechanisms from a wide variety of tissue and blood cells into the circulation in response to normal and stress/pathogenic conditions and are equipped with a multitude of transmembrane, soluble and glycosylphosphatidylinositol-anchored proteins, mRNAs, and microRNAs. Based on the currently available data, EMVs seem to reflect the diverse functional and dysfunctional states of the releasing cells and tissues along the complete individual pathogenetic pathways underlying metabolic diseases. A critical step in further validation of EMVs as biomarkers will rely on the identification of unequivocal correlations between critical disease states and specific EMV signatures, which in future may be determined in rapid and convenient fashion using nanoparticle-driven biosensors.

Global DNA methylation is associated with insulin resistance: a monozygotic twin study

Insulin resistance (IR), the hallmark of type 2 diabetes, may be under epigenetic control. This study examines the association between global DNA methylation and IR using 84 monozygotic twin pairs. IR was estimated using homeostasis model assessment (HOMA). Global DNA methylation of Alu repeats in peripheral blood leukocytes was quantified by bisulfite pyrosequencing. The association between global DNA methylation and IR was examined using generalized estimating equation (GEE) and within-twin pair analyses, adjusting for potential confounders. Results show that methylation levels at all four CpG sites were individually associated with IR by GEE (all false discovery rate-adjusted P values≤0.026). A 10% increase in mean Alu methylation was associated with an increase of 4.55 units (95% CI 2.38-6.73) in HOMA. Intrapair difference in IR was significantly associated with intrapair difference in global methylation level. A 10% increase in the difference in mean Alu methylation was associated with an increase of 4.54 units (0.34-8.71; P=0.036) in the difference in HOMA. Confirmation of the results by intrapair analyses suggests that genetic factors do not confound the association between global DNA methylation and IR. Exclusion of twins taking diabetes medication (n=17) did not change our results.

Metabolic syndrome: links to social stress and socioeconomic status

Socioeconomic stress associated with financial and psychosocial stress is widespread in society. A comprehensive body of research indicates that low socioeconomic status and social stress is associated with a broad spectrum of health risks. This paper reviews epidemiological evidence demonstrating the association between chronic social stress and development of obesity and symptoms leading to metabolic syndrome. The cumulative effects of socioeconomic stress on health and well being are evident throughout the lifespan, affecting children, adolescents, and adults. While the links between stress and metabolic disease are documented, the mechanisms remain less well understood. Animal models are well established and have provided opportunities to systematically investigate contributing mechanisms that may be targeted to develop treatment and prevention strategies against metabolic disorders arising from exposure to chronic social stress.

DNA methylation variability at growth-related imprints does not contribute to overweight in monozygotic twins discordant for BMI

Defective genomic imprinting is often associated with syndromes that include abnormal growth as a clinical phenotype. However, whether differential methylation at imprinted loci also contributes to nonsyndromic abnormal body weight regulation is yet unknown. In this study, we investigated a potential contribution of aberrant DNA methylation at nine differentially methylated regions (DMRs) to the development of nonsyndromic overweight. Sixteen monozygotic (MZ) twins discordant for BMI (BMI difference ranging from 2.9-9.5 kg/m(2)) were recruited from the East Flanders Prospective Twin Survey. DNA extracted from saliva samples was bisulfite-treated followed by PCR amplification of target regions in DMRs most representative for abnormal growth syndromes: KvDMR1, H19 CTCF4, H19 CTCF6, IGF2 DMR0, IGF2 DMR2, GRB10, MEST, SNRPN, GNAS XL-α-s and GNAS Exon1A. At the DMRs analyzed, methylation-dependent primer extension experiments revealed only small intrapair differences in methylation indexes (MI) between the heavy and lean co-twins. In addition, no significant correlations between intrapair BMI differences and intrapair differences in MI were observed. In conclusion, DNA methylation variability at the nine DMRs analyzed does not seem to contribute to the discordancy in BMI observed in these MZ twins.

Central dopaminergic circuitry controlling food intake and reward: implications for the regulation of obesity

Prevalence of obesity in the general population has increased in the past 15 years from 15% to 35%. With increasing obesity, the coincident medical and social consequences are becoming more alarming. Control over food intake is crucial for the maintenance of body weight and represents an important target for the treatment of obesity. Central nervous system mechanisms responsible for control of food intake have evolved to sense the nutrient and energy levels in the organism and to coordinate appropriate responses to adjust energy intake and expenditure. This homeostatic system is crucial for maintenance of stable body weight over long periods of time of uneven energy availability. However, not only the caloric and nutritional value of food but also hedonic and emotional aspects of feeding affect food intake. In modern society, the increased availability of highly palatable and rewarding (fat, sweet) food can significantly affect homeostatic balance, resulting in dysregulated food intake. This review will focus on the role of hypothalamic and mesolimbic/mesocortical dopaminergic (DA) circuitry in coding homeostatic and hedonic signals for the regulation of food intake and maintenance of caloric balance. The interaction of dopamine with peripheral and central indices of nutritional status (e.g., leptin, ghrelin, neuropeptide Y), and the susceptibility of the dopamine system to prenatal insults will be discussed. Additionally, the importance of alterations in dopamine signaling that occur coincidently with obesity will be addressed.

DNA sequence polymorphisms within the bovine guanine nucleotide-binding protein Gs subunit alpha (Gsα)-encoding (GNAS) genomic imprinting domain are associated with performance traits

BACKGROUND

Genes which are epigenetically regulated via genomic imprinting can be potential targets for artificial selection during animal breeding. Indeed, imprinted loci have been shown to underlie some important quantitative traits in domestic mammals, most notably muscle mass and fat deposition. In this candidate gene study, we have identified novel associations between six validated single nucleotide polymorphisms (SNPs) spanning a 97.6 kb region within the bovine guanine nucleotide-binding protein Gs subunit alpha gene (GNAS) domain on bovine chromosome 13 and genetic merit for a range of performance traits in 848 progeny-tested Holstein-Friesian sires. The mammalian GNAS domain consists of a number of reciprocally-imprinted, alternatively-spliced genes which can play a major role in growth, development and disease in mice and humans. Based on the current annotation of the bovine GNAS domain, four of the SNPs analysed (rs43101491, rs43101493, rs43101485 and rs43101486) were located upstream of the GNAS gene, while one SNP (rs41694646) was located in the second intron of the GNAS gene. The final SNP (rs41694656) was located in the first exon of transcripts encoding the putative bovine neuroendocrine-specific protein NESP55, resulting in an aspartic acid-to-asparagine amino acid substitution at amino acid position 192.

RESULTS

SNP genotype-phenotype association analyses indicate that the single intronic GNAS SNP (rs41694646) is associated (P ≤ 0.05) with a range of performance traits including milk yield, milk protein yield, the content of fat and protein in milk, culled cow carcass weight and progeny carcass conformation, measures of animal body size, direct calving difficulty (i.e. difficulty in calving due to the size of the calf) and gestation length. Association (P ≤ 0.01) with direct calving difficulty (i.e. due to calf size) and maternal calving difficulty (i.e. due to the maternal pelvic width size) was also observed at the rs43101491 SNP. Following adjustment for multiple-testing, significant association (q ≤ 0.05) remained between the rs41694646 SNP and four traits (animal stature, body depth, direct calving difficulty and milk yield) only. Notably, the single SNP in the bovine NESP55 gene (rs41694656) was associated (P ≤ 0.01) with somatic cell count--an often-cited indicator of resistance to mastitis and overall health status of the mammary system--and previous studies have demonstrated that the chromosomal region to where the GNAS domain maps underlies an important quantitative trait locus for this trait. This association, however, was not significant after adjustment for multiple testing. The three remaining SNPs assayed were not associated with any of the performance traits analysed in this study. Analysis of all pairwise linkage disequilibrium (r2) values suggests that most allele substitution effects for the assayed SNPs observed are independent. Finally, the polymorphic coding SNP in the putative bovine NESP55 gene was used to test the imprinting status of this gene across a range of foetal bovine tissues.

CONCLUSIONS

Previous studies in other mammalian species have shown that DNA sequence variation within the imprinted GNAS gene cluster contributes to several physiological and metabolic disorders, including obesity in humans and mice. Similarly, the results presented here indicate an important role for the imprinted GNAS cluster in underlying complex performance traits in cattle such as animal growth, calving, fertility and health. These findings suggest that GNAS domain-associated polymorphisms may serve as important genetic markers for future livestock breeding programs and support previous studies that candidate imprinted loci may act as molecular targets for the genetic improvement of agricultural populations. In addition, we present new evidence that the bovine NESP55 gene is epigenetically regulated as a maternally expressed imprinted gene in placental and intestinal tissues from 8-10 week old bovine foetuses.

The genetics of obesity

Obesity is a result of excess body fat accumulation. This excess is associated with adverse health effects such as CVD, type 2 diabetes, and cancer. The development of obesity has an evident environmental contribution, but as shown by heritability estimates of 40% to 70%, a genetic susceptibility component is also needed. Progress in understanding the etiology has been slow, with findings largely restricted to monogenic, severe forms of obesity. However, technological and analytical advances have enabled detection of more than 20 obesity susceptibility loci. These contain genes suggested to be involved in the regulation of food intake through action in the central nervous system as well as in adipocyte function. These results provide plausible biological pathways that may, in the future, be targeted as part of treatment or prevention strategies. Although the proportion of heritability explained by these genes is small, their detection heralds a new phase in understanding the etiology of common obesity.

Heritability of body weight: moving beyond genetics

Obesity is a complex disease, arising from the interaction between several genetic and environmental factors. Until recently, the genetic basis of complex diseases in general, and of obesity in particular, were poorly characterized. While the relatively rare monogenic and syndromic forms of obesity clearly recognize a genetic origin, the actual worldwide epidemics of obesity represent a challenge for the identification of the genetic factors involved, being likely the effect of several loci each having a subtle influence on the phenotypic expression. Progress in DNA analysis techniques and in computational tools, and the increasing level of characterization of the variability of the human genome has recently allowed to study comprehensively the association between genetic variants and obesity. To date, well-conducted and powered genome-wide association studies allowed to consistently identify genomic regions - lying on different chromosomes and affecting different metabolic pathways - influencing the predisposition to the accumulation of body fat, ultimately leading to overweight and obesity. However, the population attributable risk for obesity linked to the most statistically significant loci, like FTO and MC4R, remains discouragingly low, explaining only small fractions of the overall variance of body weight. In the last few years, the role of the complex interaction between genetic determinants and environmental factors in the rapid global increase of obesity has been further challenged by the entry of new players, that is the transcriptional and post-transcriptional regulation, summarized under the emerging discipline of epigenetics. The key challenge now is to move from the identification of causal genes and variants to the integration of different "omics" disciplines, finally allowing the molecular understanding of obesity and related conditions.

Epigenetics and cardiovascular disease

Despite advances in the prevention and management of cardiovascular disease (CVD), this group of multifactorial disorders remains a leading cause of mortality worldwide. CVD is associated with multiple genetic and modifiable risk factors; however, known environmental and genetic influences can only explain a small part of the variability in CVD risk, which is a major obstacle for its prevention and treatment. A more thorough understanding of the factors that contribute to CVD is, therefore, needed to develop more efficacious and cost-effective therapy. Application of the 'omics' technologies will hopefully make these advances a reality. Epigenomics has emerged as one of the most promising areas that will address some of the gaps in our current knowledge of the interaction between nature and nurture in the development of CVD. Epigenetic mechanisms include DNA methylation, histone modification, and microRNA alterations, which collectively enable the cell to respond quickly to environmental changes. A number of CVD risk factors, such as nutrition, smoking, pollution, stress, and the circadian rhythm, have been associated with modification of epigenetic marks. Further examination of these mechanisms may lead to earlier prevention and novel therapy for CVD.

Genomic imprinting in diabetes

Genomic imprinting refers to a class of transmissible genetic effects in which the expression of the phenotype in the offspring depends on the parental origin of the transmitted allele. The DNA from one parent may be epigenetically modified so that only a single allele of the imprinted gene is expressed in the offspring. Although imprinting has an important role in the regulation of growth and development through its role in regulating gene expression, its contribution to susceptibility to common complex disorders is not well understood. We summarize current views on the role of imprinting in diabetes and in particular chromosome 6q24-related transient neonatal diabetes mellitus, the best known example of an imprinted genetic disorder that leads to diabetes.

Perinatal environment and its influences on metabolic programming of offspring

The intrauterine environment supports the development and health of offspring. Perturbations to this environment can have detrimental effects on the fetus that have persistent pathological consequences through adolescence and adulthood. The developmental origins of the health and disease concept, also known as the "Barker Hypothesis", has been put forth to describe the increased incidence of chronic disease such as cardiovascular disease and diabetes in humans and animals exposed to a less than ideal intrauterine environment. Maternal infection, poor or excess nutrition, and stressful events can negatively influence the development of different cell types, tissues and organ systems ultimately predisposing the organism to pathological conditions. Although there are a variety of conditions associated to exposure to altered intrauterine environments, the focus of this review will be on the consequences of stress and high fat diet during the pre- and perinatal periods and associated outcomes related to obesity and other metabolic conditions. We further discuss possible neuroendocrine and epigenetic mechanisms responsible for the metabolic programming of offspring. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009.

Early postnatal BMI adaptation is regulated during a fixed time period and mainly depends on maternal BMI

In the present study, we investigated whether there are critical time periods which influence the course of BMI during the first 6 years of life. From 5,433 children who participated in preschool examinations those 212 children were selected who crossed the BMI percentiles as a result of an extreme postnatal BMI rise (from <10th to 90th percentile) or fall (from >90th to <10th percentile) or who have persistently low or high BMI both at birth and at the age of 6 years. Forty children with a BMI close to the 50th percentile both at birth and age 6 years were selected to serve as controls. The courses of weight and height during the first 6 years of age were assessed and BMI was calculated. To identify influences connected with BMI development, we investigated genetic, social, nutritional, and other factors proceeding from the mother during pregnancy. Finally completed data sets of 57 children were available. Our study shows that during two critical time periods a significant move toward low or high BMI takes place among the groups: in early infancy from ~0.5 to 1.5 years and again from 5 to 6 years. At the age of 1.5 years the final state of BMI is already fixed in all study groups. Mothers of overweight 6-year-old children are overweight, whereas mothers of underweight 6-year-old children have a below-normal BMI. All other investigated factors only had a minor influence on postnatal BMI development. We conclude that postnatal BMI development follows a fixed genetic program and is mainly programmed by maternal metabolism.