[Epigenetics and obesity]

Risk factors involved in adolescent obesity: an integrative review

The scope of this study was to examine the risk factors for the development of obesity in adolescence. The objective was to identify risk factors for adolescent obesity by means of an Integrative Review of the Literature. The PICO strategy was used to formulate the following central line of inquiry: What are the risk factors for the development of obesity during adolescence? The VHL and EBSCOhost research databases were consulted, resulting in a selection of 25 articles for in-depth study. The phenomenon of obesity was understood as the result of biological, social, psychological, and nutritional factors. The research revealed a lack of consensus on the risks and benefits, which makes evidence-based recommendations difficult. The study identified proposals that can be implemented, such as a change in eating habits, weight control and the practice of physical exercise. Such behavioral changes can be recommended within the context of the family, schools, and health services. The review recommends prevention strategies and the recognition of school as the ideal medium for health promotion through education. From a political and social standpoint, it is necessary to challenge the prevalence of publicity of the food industry that entices adolescents to consume processed foods with high fat and sugar content.

DNA methylation in genes of longevity-regulating pathways: association with obesity and metabolic complications

Aging is the main risk factor for most chronic diseases. Epigenetic mechanisms, such as DNA methylation (DNAm) plays a pivotal role in the regulation of physiological responses that can vary along lifespan. The aim of this research was to analyze the association between leukocyte DNAm in genes involved in longevity and the occurrence of obesity and related metabolic alterations in an adult population. Subjects from the MENA cohort (n=474) were categorized according to age (<45 vs 45>) and the presence of metabolic alterations: increased waist circumference, hypercholesterolemia, insulin resistance, and metabolic syndrome. The methylation levels of 58 CpG sites located at genes involved in longevity-regulating pathways were strongly correlated (FDR-adjusted< 0.0001) with BMI. Fifteen of them were differentially methylated (p<0.05) between younger and older subjects that exhibited at least one metabolic alteration. Six of these CpG sites, located at MTOR (cg08862778), ULK1 (cg07199894), ADCY6 (cg11658986), IGF1R (cg01284192), CREB5 (cg11301281), and RELA (cg08128650), were common to the metabolic traits, and CREB5, RELA, and ULK1 were statistically associated with age. In summary, leukocyte DNAm levels of several CpG sites located at genes involved in longevity-regulating pathways were associated with obesity and metabolic syndrome traits, suggesting a role of DNAm in aging-related metabolic alterations.

Cytokines and body adiposity in young female undergraduate students

Introduction

Objective: to identify cytokines and to associate them with several indexes of total and central adiposity in young female undergraduate students. Methods: 58 young female sophomore students, aged 18 to 25 years, from a Brazilian public university were evaluated. Both anthropometric measures (weight, height, waist circumference and hip circumference) and body composition were assessed through DXA, and the values of android, gynoid and truncal fat mass were obtained. Cytokines (IL-8, IL-1β, IL-6, IL-10 e TNF-α) were analyzed, and Body Mass Index (BMI), Body Adiposity Index (BAI), Visceral Adiposity Index (VAI), Conicity Index (CCI), Waist-Hip Index (WHR), Waist-to-Height Ratio (WHtR), Fat Mass Distribution Index 1 (FMI1) and Fat Mass Distribution Index 2 (FMI2) were calculated. Eventually, a linear regression was carried out to determine the regression coefficient and confidence interval (CI), having the predictor variables (cytokines) adjusted according to age and family history of obesity. The statistical significance of α = 5% was applied. Results: a correlation between adiposity indexes and cytokines (CCI, WHR and IL-12; CCI, WHR, FMI1, FMI2 and TNF-α) was identified. When it comes to the regression models, cytokines increase was related to CCI, WHR, FMI1 and FMI2 increase. Conclusion: pro-inflammatory cytokines were associated with an increase in adipose indexes. Therefore, these indexes became a feasible strategy for clinical practice in order to identify propensity to inflammatory disorders.

Amperometric Bioplatforms To Detect Regional DNA Methylation with Single-Base Sensitivity

This work reports the first bioplatform able to determine electrochemically 5-hydroxymethylcytosine (5-hmC) methylation events at localized sites and single-base sensitivity. The described bioplatform relies on a specific antibody (anti-5-hmC), further conjugated with commercial bioreagents loaded with multiple horseradish peroxidase (HRP) molecules, recognizing the epimark in a target DNA, captured through hybridization onto streptavidin-magnetic microbeads (Strep-MBs) modified with a complementary DNA capture probe. The electrochemical detection is performed by amperometry (-0.20 V vs Ag pseudoreference electrode) at disposable screen-printed carbon electrodes (SPCEs) in the presence of H₂O₂/hydroquinone (HQ) upon magnetic capture of the modified MBs onto the SPCE. The use of the commercial bioreagents ProtA-polyHRP₈₀ and Histostar, very scarcely explored so far in electrochemical biosensors, provides high sensitivities for a synthetic target DNA sequence with a unique 5-hmC in the promoter region of MGMT tumor suppressor gene. Amplification factors of 43.6 and 55.2 were achieved using ProtA-polyHRP₈₀ or Histostar, respectively, compared to the conventional secondary antibody labeling. This amplification was crucial to detect methylation events at single-nucleotide resolution achieving limits of detection (LODs) of 23.0 and 13.2 pM, respectively, without any target DNA amplification. The ProtA-polyHRP₈₀-based bioplatform, selected as a compromise between sensitivity and cost per determination, exhibited full discrimination toward the target 5-hmC against the closely related 5-mC. In addition, the bioplatform detected 5-hmC at the regional level (MGMT promoter region) in just 10 ng of genomic DNA (gDNA, ∼2700 genomes) extracted from cancer cells and tissues from colorectal cancer (CRC) patients within 60 min.

Modulation of the leptin receptors expression in breast cancer cell lines exposed to leptin and tamoxifen

One of the factors that has increased the incidence and worse prognosis of breast cancer is obesity. In this condition, high amounts of leptin are secreted, which have proliferative, mitogenic, antiapoptotic, and proinflammatory activity that may be antagonistic to treatment with tamoxifen, considered the first choice. The modulation evaluation of leptin receptor expression in the presence of leptin and tamoxifen stimuli was performed in breast cancer cell lines MCF 7, MDA MB 231 and HCC 1937 as a model of initial approach for the study of breast cancer subtypes and their behavior to the action response of adipokines and their possible relationship with the mechanism of resistance to chemotherapeutics such as tamoxifen in ER positive cell lines and triple negative marker. It was determined that leptin increases the proliferation of the three breast cancer cell lines and tamoxifen is able to exert an antiproliferative effect on them, however, it was identified that the ability of tamoxifen to decrease the proliferation of cancer cells is diminished in the presence of leptin, in addition to changes in the modulation of the expression of its receptor. It was determined that tamoxifen induces a greater modulation of the expression of ObRb in cell lines, which may be related to the decrease of its antiproliferative activity, while leptin generates a proliferative effect in the three cell lines and could participate in the tamoxifen treatment resistance mechanism.

Dietary Folate Intake Is Negatively Associated with Excess Body Weight in Brazilian Graduates and Postgraduates (CUME Project)

Folate, vitamin B6, and vitamin B12 intake can be important regulators for obesity development. Thus, we investigated the possible association between the intake of these vitamins and the excess body weight or obesity prevalence in the participants of the Cohort of Universities in Minas Gerais (CUME project). This study analyzed cross-sectional data of 2695 graduates and postgraduates from universities in the state of Minas Gerais (801 men, 1894 women, ages 36.2 ± 9.4). The first step consisted of collecting data online, and the second step consisted of blood collecting in the subsample living in the city of Viçosa and its region (Minas Gerais). Excess body weight and obesity prevalence were 38.1% and 10.1%, respectively. Inadequate intake of folate, B6, and B12 were 12, 6.3, and 11.1%, respectively. Beans/lentils and French bread presented the highest contribution to folate intake (23.45% and 10.01%, respectively). Those individuals in the third tertile for folate intake (≥511.12 μg/d) had a lower excess body weight [prevalence ratio (PR): 0.79, confidence interval (CI): 0.71⁻0.8] and obesity prevalence (PR: 0.60, CI: 0.45⁻0.78). These associations were maintained when the sample was categorized by sex. In addition, serum folate was positively associated with dietary folate (p for trend = 0.032) and negatively associated with serum homocysteine (p for trend = 0.003) in the subsample. Dietary folate intake was negatively associated with excess body weight and obesity in CUME participants, indicating the relevance of this vitamin dietary assessment.

Obesity-Related Epigenetic Changes After Bariatric Surgery

Objective: In recent years, an increasing number of studies have begun focusing on epigenetics as a link between environmental factors and a greater predisposition to the development of obesity and its comorbidities. An important challenge in this field is the evaluation of the possibility of the reversal of obesity-related epigenetic marks by means of therapy to induce weight loss and if the beneficial effects of therapy in reducing obesity are mediated by epigenetic mechanisms. We aimed to offer an outline of the current results regarding to the impact of bariatric surgery on epigenetic regulation, as well as to show if the beneficial effect of this intervention could be mediated by epigenetic mechanisms. Methods: A review of the scientific publications in PubMed was performed by using key words related to obesity, epigenetics and bariatric surgery to provide an update of recent findings in this area of research. The most relevant and recently published articles and abstracts were selected to frame this review. Results: Previous studies have demonstrated the presence of differential DNA methylation after bariatric surgery and the differential expression of non-coding RNAs. Therefore, epigenetic regulation could mediate the benefit of bariatric surgery on body weight and the metabolic disturbances associated with excess body weight, such as insulin resistance, hypertension, and cardiovascular disease. This evidence is relatively new as epigenetic regulation was first evaluated in the obesity field only a few years ago. However, there is an urgent need to perform longitudinal studies to evaluate the capacity of epigenetic marks in the prediction of bariatric surgery response. Conclusions: Bariatric surgery appears to be capable of partially reversing the obesity-related epigenome. The identification of potential epigenetic biomarkers predictive for the success of bariatric surgery may open new doors to personalized therapy for severe obesity.