The influence of serum selenium in differential epigenetic and transcriptional regulation of CPT1B gene in women with obesity.

INTRODUCTION: The increasing prevalence of obesity has become a major health problem worldwide. The causes of obesity are multifactorial and could be influenced by dietary patterns and genetic factors. Obesity has been associated with a decrease in micronutrient intake and consequently decreased blood concentrations. Selenium is an essential micronutrient for human health, and its metabolism could be affected by obesity, especially severe obesity. This study aimed to identify differential methylation genes associated with serum selenium concentration in women with and without obesity. METHODOLOGY: Thirty-four patients were enrolled in the study and divided into two groups: Obese (Ob) n = 20 and Non-Obese (NOb) n = 14, according to the Body Mass Index (BMI). Anthropometry, body composition, serum selenium, selenium intake, and biochemical parameters were evaluated. DNA extraction and bisulfite conversion were performed to hybridize the samples on the 450k Methylation Chip Infinium Beadchip (Illumina). Bioinformatics analysis was performed using the R program and the Champ package. The differentially methylated regions (DMRs) were identified using the Bumphunter method. In addition, logarithmic conversion was performed for the analysis of serum selenium and methylation. RESULTS: In the Ob group, the body weight, BMI, fat mass, and free fat mass were higher than in the NOb group, as expected. Interestingly, the serum selenium was lower in the Ob than in the NOb group without differences in selenium intake. One DMR corresponding to the CPT1B gene, involved in lipid oxidation, was related to selenium levels. This region was hypermethylated in the Ob group, indicating that the intersection between selenium deficiency and hypermethylation could influence the expression of the CPT1B gene. The transcriptional analysis confirmed the lower expression of the CPT1B gene in the Ob group. CONCLUSION: Studies connecting epigenetics to environmental factors could offer insights into the mechanisms involving the expression of genes related to obesity and its comorbidities. Here we demonstrated that the mineral selenium might play an essential role in lipid oxidation via epigenetic and transcriptional regulation of the CPT1B gene in obesity.

The Impact of Gastric Bypass on Telomere Length and Shelterin Complex Gene Expression: 6 Months Prospective Study.

BACKGROUND: Telomeres are structures located at the ends of chromosomes associated with a protein complex, known as the shelterin complex. In individuals with obesity, excess adipose tissue plays a key role in inducing a chronic and systemic inflammatory state, which can cause TL shortening. In this context, bariatric surgery is one of the most effective treatment modalities in improving metabolic control. AIM: Therefore, the present study aimed to evaluate how a short postoperative period of gastric bypass affects TL and expression of POT1, TRF1 and TRF2 genes. METHODS: Forty-eight women submitted to RYGB were evaluated before and after 6 months of the surgical procedure. Anthropometric measures of body weight and height (BMI), abdominal circumference (AC), body composition, food intake and blood collection for biochemical evaluation, TL analysis (DNA), and gene expression (RNA) were collected at each moment. RESULTS: There was a reduction of weight, BMI, AC, FM and FFM as well as of glycemia, total cholesterol, LDL-cholesterol, and triglycerides after gastric bypass. No difference in energy intake and macronutrients consumption was observed. There was no significant change in TL, but there was a significant increase of POT1 and TRF1 gene expression after surgery, while TRF2 expression did not change. CONCLUSIONS: Despite bariatric surgery is not capable of increasing telomere length in a short-term period, no reduction is observed; additionally, we found a correlation between serum triglycerides concentration and TL. The increase of POT1 and TRF1 gene expression may explain the maintenance of the TL after 6 months postoperative period.

A new resting metabolic rate equation for women with class III obesity.

OBJECTIVE: Resting metabolic rate (RMR) is an important parameter to guide the nutritional therapy of class III obese patients. The aims of the present study were to develop a predictive equation for RMR estimation in class III obese women using anthropometric indicators and to compare indirect calorimetry with other predictive equations. METHODS: This was a cross-sectional study on women with class III obesity (body mass index >40 kg/m2). Weight, height, fat-free mass, fat mass, and RMR of all individuals were measured. Multiple linear regression was used to determine the new RMR equation and the Bland-Altman plot was used to analyze the agreement between indirect calorimetry and the results of predictive equations. RESULTS: We evaluated 101 women with obesity class III and a mean age of 36.3 ± 10 y. The anthropometric and body composition variables used in the new equation had a coefficient of determination of 0.80, and a significant influence on RMR (P = 0.01). Harris-Benedict and World Health Organization equations showed similar bias and limits (181.6, +2 SD = 765.5, -2 SD = -402.2; 156.4, +2 SD = 799.4, -2 SD = -486.6, respectively). The Mifflin-St Jeor and Owen equations showed large clinical bias (mean, 239.2 and 463.9, respectively), and a tendency to overestimate RMR. CONCLUSION: The prediction equations tested in the study had low accuracy in estimating RMR of women with class III obesity. However, our equation was developed specifically for this population, using variables known to influence their energy expenditure.

UCP2 and PLIN1 Expression Affects the Resting Metabolic Rate and Weight Loss on Obese Patients.

BACKGROUND: Analysis of the expression of genes related to the energy metabolism can elucidate the understanding of physiological and genetic factors that contribute to obesity. This study aimed to evaluate the expression of genes and its influence on resting metabolic rate and weight loss in obese patients before and after bariatric surgery. METHODS: This study was conducted on 23 women, who were divided into two groups: bariatric surgery (preoperative and 6 months after surgery) and control. Abdominal subcutaneous adipose tissue samples were collected to analyze the gene expression, and the resting metabolic rate (RMR) was measured by indirect calorimetry. RESULTS: Significant differences were observed in weight reduction (22 %, p = 0.01), BMI (22.5 %, p = 0.01), and RMR values (10.5 %, p = 0.01) after the bariatric surgery, while the weight-adjusted RMR increased (15.8 %, p = 0.01). Increased UCP2 expression after 6 months of Roux-en-Y gastric bypass (RYGB) as compared to preoperative period (0.764 to 1.268, p = 0.01) was observed. Analysis with weight-adjusted RMR as dependent variable revealed that UCP2 (r 2 = 0.517, p = 0.01) and PLIN1 (r 2 = 0.420, p = 0.04) expression determine the RMR values in preoperative period. Moreover, UCP2 and PLIN1 expression in preoperative period influenced the percentage of weight loss, even when adjusted for age and BMI. CONCLUSIONS: We have demonstrated that after 6 months of bariatric surgery, there is significant increase in the UCP2 expression. Additionally, the expression of UCP2 and PLIN1 genes influences the resting metabolic rate in obese individuals and could predict the weight loss after bariatric surgery.