Aspectos genéticos da obesidade

Irisin and Cardiometabolic Disorders in Obesity: A Systematic Review

Background

Overweight and obesity are global health issues, impacting a significant portion of young adults. Obesity is a complex condition influenced by genetics and environmental factors, leading to increased susceptibility to cardiovascular diseases (CVDs), hypertension, dyslipidemia, and insulin resistance. Irisin, a protein derived from the cleavage of fibronectin type III domain-containing protein 5, may have relationship with these cardiometabolic diseases.

Objective

This systematic review aims to examine the relationship between serum irisin levels and obesity, particularly in individuals predisposed to cardiovascular risk factors.

Methods

A thorough literature search was conducted in multiple databases, including "Science Direct," "Scopus," "PubMed," and "Lilacs," from July 2020. Inclusion criteria encompassed subjects with metabolic disorders (with or without obesity, BMI ≥30 kg/m2), clinical trials, and observational studies published between 2010 and June 2020. Exclusion criteria were animal studies, meta-analyses, systematic reviews, studies evaluating only healthy subjects, and those investigating disorders beyond cardiometabolic diseases.

Results

Out of 151 identified articles, 30 met the inclusion criteria. These studies, published between 2013 and 2020, assessed adults (≥21 years) and included 26 observational studies and 4 clinical trials (n = 7585 subjects). All studies examined irisin's role in obesity and CVDs, often including associated diseases such as type 2 diabetes and hypertension. Despite varying sample sizes, the samples within the articles were homogeneous. Observational studies exhibited a low risk of bias in at least 60% of the evaluated domains. Clinical trials demonstrated a low risk of bias in at least 50% of the domains. Limitations. Although the systematic review provides valuable insights, it is limited by the available literature and the varying methodologies used across studies.

Conclusion

The review suggests that irisin plays a significant role as both a preventive measure and a biomarker for comorbidities linked to obesity and cardiometabolic disorders. Future research should focus on standardized irisin measurement methods and diverse populations to further elucidate its mechanisms of action.

Association of the MC4R rs17782313 polymorphism with plasma ghrelin, leptin, IL6 and TNFα concentrations, food intake and eating behaviors in morbidly obese women

PURPOSE

The rs17782313 variant of the MC4R gene plays an important role in the obesity phenotype. Studies that evaluate environmental factors and genetic variants associated with obesity may represent a great advance in understanding the development of this disease. This work seeks to assess the association of the polymorphism of MC4R rs17782313 on plasma parameters, including leptin, ghrelin, tumor necrosis factor (TNFα) and interleukin 6 (IL6), and on the eating behaviors of morbidly obese women.

METHODS

70 adult women with BMI between 40 and 60 kg/m² were recruited. Laboratory and anthropometric data were recorded. Using a visual analog scale (VAS), the feelings of hunger and satiety were evaluated. The presence or absence of binge eating was evaluated through the Binge Eating Scale (BES) questionnaire. Habitual food intake was analyzed using 3-day dietary records. TaqMan^® assays were conducted using real-time PCR to assess genotype polymorphism variants from peripheral blood DNA.

RESULTS

This study found that female patients with the MC4R rs17782313 polymorphism had high levels of ghrelin and reduced levels of IL6 in the postprandial period. We observed a higher prevalence of severe binge eating in more than 50% of women with at least one risk allele.

CONCLUSION

Our hypothesis is that the MC4R rs17782313 polymorphism may influence the release of ghrelin, even without being associated with feelings of hunger and satiety. More than half of women with this polymorphism exhibited severe binge eating.

LEVEL OF EVIDENCE

Level III: case-control analytic study.

Environmental, Socioeconomic, Maternal, and Breastfeeding Factors Associated with Childhood Overweight and Obesity in Ceará, Brazil: A Population-Based Study

Childhood obesity is now an epidemic in many countries worldwide and is known to be a multifactorial condition. We aimed to examine the relationship of environmental, socioeconomic, and nutritional factors with childhood overweight and obesity. We conducted a population-based cross-sectional study of children from 2 to 6 years of age in Ceará, Brazil. Children’s nutritional status was assessed by body mass index (BMI) Z scores categorized as overweight and obesity. Ordinal logistic regression models were used to assess the relationship between the factors with overweight and obesity. A total of 2059 children participated, of which 50.4% were male. The mean age was 46 ± 17 months, with a prevalence of overweight and obesity of 12.0% (95% CI 10.7–13.6) and 8.0% (6.7–9.5), respectively. In multivariate analysis, the probability of childhood obesity increased as family income increased (adjusted hazard ratio (aHR) 0.6 (95% CI 0.37–0.95), p-value = 0.03). Moreover, families with fewer children had more than 30% fewer overweight children (aHR 0.68; 95% CI 0.48–0.96). Environmental, socioeconomic, and child nutritional factors were associated with overweight and obesity. The results provided could be used to design integrated interventions spanning from conception, or earlier, through the first years of life and may improve child nutritional outcomes.

Benefits of Fish Oil Consumption over Other Sources of Lipids on Metabolic Parameters in Obese Rats

This study evaluated the effect of the consumption of different levels and sources of lipids on metabolic parameters of Wistar rats. Animals were fed with high-fat diet (HFD) containing 20% of lard for 12 weeks to cause metabolic obesity. Subsequently, the animals were divided into six groups and were fed diets with lipid concentrations of 5% or 20% of lard (LD), soybean oil (SO) or fish oil (FO), for 4 weeks. Data were submitted to analysis of variance (two-way) followed by Tukey post hoc test (p < 0.05). The groups that consumed FO showed less weight gain and lower serum levels of triacylglycerol (TAG), total cholesterol and fractions, aspartate aminotransferase (AST) activity, atherogenic index, less amount of fat in the carcass, decreased Lee index and lower total leukocyte counting (p < 0.05). These same parameters were higher in LD treatment (p < 0.05). In the concentration of 20%, carcass fat content, blood glucose levels, as well as alanine aminotransferase (ALT) and gamma glutamyl transferase (GGT) decreased in FO groups (p < 0.05). The SO group had intermediate results regarding the other two treatments (FO and LD). We concluded that fish oil intake was able to modulate positively the metabolic changes resulting from HFD.

Obesity-induced diet leads to weight gain, systemic metabolic alterations, adipose tissue inflammation, hepatic steatosis, and oxidative stress in gerbils (Meriones unguiculatus)

BACKGROUND

Nowadays, the number of obese people in the world has reached alarming proportions. During the expansion of adipose tissue, a number of functions such as activation and release of cytokines and hormones may be affected. This leads the body to a pro-inflammatory pattern, which may affect the proper functioning of many tissues. Thus, studying the mechanisms by which obesity induces physiological disorders is necessary, and may be facilitated by the use of animal models, in particular rodents. We sought to characterize the metabolic and adipose tissue changes resulting from a diet rich in fats and simple sugars in gerbils.

METHODS

We divided 14 gerbils into two experimental groups that received a diet rich in simple carbohydrates and fats with 5,86 kcal/g (OB, n = 7) or a standard diet with 4.15 kcal/g (CT; n = 7) for 11 weeks. The animals had free access to water and food. The animal weight and food consumption were measured weekly. Blood, adipose tissue and liver of each animal were collected at the end of experiment. The following parameters were determined: cholesterol (COL), triglycerides (TGL) and glycemia (GLI) in the plasma; cytokines (IL-6, IL-10 and TNF-α) and hormones (adiponectin and leptin) in adipose tissue; activity of superoxide dismutase (SOD) and catalase (CAT), extraction and differentiation of fat and histology in liver.

RESULTS

The consumption of a diet rich in simple carbohydrates and fats led to increased total body weight and increased relative weights of liver and adipose tissue. In addition, we observed increased fasting glucose levels and circulating triglycerides, along with high TNF-α production in adipose tissue and increased total fat, cholesterol and triglyceride contents in the liver, contributing to higher intensity of hepatic steatosis. On the other hand, the animals of this group showed depletion in the enzyme activity of SOD and CAT in the liver, as well as reduction of IL-10 and adiponectin levels in adipose tissue.

DISCUSSION

High intake of saturated fat and simple carbohydrates establish the gerbil as an experimental model for the study of metabolic and hepatic abnormalities resulting from obesity.

Maternal obesity, environmental factors, cesarean delivery and breastfeeding as determinants of overweight and obesity in children: results from a cohort

BACKGROUND

Overweight and obesity are a public health problem with a multifactorial aetiology. The objective of this study was to evaluate risk factors for overweight and obesity in children at 6 years of age, including type of delivery and breastfeeding.

METHODS

This study relates to a cohort of 672 mother-baby pairs who have been followed from birth up to 6 years of age. The sample included mothers and infants seen at all ten maternity units in a large Brazilian city. Genetic, socioeconomic, demographic variables and postnatal characteristics were analyzed. The outcome analyzed was overweight and/or obesity defined as a body mass index greater than or equal to +1 z-score. The sample was stratified by breastfeeding duration, and a descriptive analysis was performed using a hierarchical logistic regression. P-values of <0.05 were considered significant.

RESULTS

Prevalence rates (PR) of overweight and obesity among the children were 15.6% and 12.9%, respectively. Among the subset of breastfed children, factors associated with the outcome were maternal overweight and/or obesity (PR 1.92; 95% confidence interval "95% CI" 1.15-3.24) and lower income (PR 0.50; 95% CI 0.29-0.85). Among children who had not been breastfed or had been breastfed for shorter periods (less than 12 months), predictors were mothers with lower levels of education (PR 0.39; 95% CI 0.19-0.78), working mothers (PR 1.83; 95% CI 1.05-3.21), caesarean delivery (PR 1.98; 95% CI 1.14 - 3.50) and maternal obesity (PR 3.05; 95% CI 1.81 - 5.25).

CONCLUSIONS

Maternal obesity and caesarean delivery were strongly associated with childhood overweight and/or obesity. Lower family income and lower levels of education were identified as protective factors. Breastfeeding duration appeared to modify the association between overweight/obesity and the other predictors studied.

LEP -2548G>A Polymorphism of the Leptin Gene and Its Influence on the Lipid Profile in Obese Individuals

BACKGROUND/AIM

We studied the molecular pathogenesis of obesity, involving complex interactions between environmental and genetic factors, with a focus on the leptin gene. It was our aim to characterize the LEP -2548G>A leptin polymorphism and lipid profile in obese and normal-weight individuals.

METHODS

A total of 212 individuals were divided into the study group including 136 obese patients (body mass index, BMI≥30) and the control group with 76 normal-weight individuals (BMI>18.5 and ≤24.9). DNA was amplified by polymerase chain reaction and restriction fragment length polymorphism. The lipid profile was analyzed by enzymatic colorimetric methods. The level of significance was set at p<0.05.

RESULTS

There was a prevalence of the GA genotype in both groups. However, comparative group analysis showed an association of the recessive model (AA+GA) with increased triglycerides (TG) and decreased high-density lipoprotein cholesterol (HDL-C) levels in the study group.

CONCLUSION

This study did not confirm an association between obesity and the LEP -2548G>A polymorphism. However, AA+GA genotypes, in the presence of obesity, seem to contribute to a reduction in HDL-C and an increase in TG compared with normal-weight individuals. This should be confirmed in further studies.

[Temporal evolution of overweight and obesity among Brazilian male adolescents, 1980-2005]

Analysis of the temporal trend in obesity shows the increasing risk posed by this condition worldwide. This article aims to verify and compare the prevalence rates for overweight and obesity in male adolescents in all States of Brazil, from 1980 to 2005. We used the Brazilian Army's database, with 8,989,508 males 17-19 years of age. We defined overweight as body mass index (BMI) from 25 kg/m2 to 29.9 kg/m2 and obesity as BMI>or=30 kg/m2. The analysis showed an increasing trend in the prevalence of overweight and obesity in all States of Brazil for the period studied. There was a three-fold increase in adolescents with overweight and a six-fold increase in obesity. The absolute numbers for overweight were higher than for obesity, but the rate of increase over the period was greater for obesity. Analyzing the trend in prevalence rates by five-year period, we observed that from 1980 to 2005, as the prevalence of overweight decreased, that of obesity increased in all States of Brazil.

Dieta hiperlipídica com farinha de soja como fonte proteica: utilização na seleção de ratos propensos e resistentes à obesidade

OBJETIVO: Desenvolver uma dieta hiperlipídica de baixo custo, tendo farinha de soja como fonte proteica, que seja eficiente na seleção de ratos propensos e resistentes à obesidade e que permita alcançar fenótipo obeso nos animais propensos. Além desses requisitos, a dieta deve ser palatável e não rejeitada a curto prazo pelo animal. MÉTODOS: A dieta proposta foi obtida misturando-se leite condensado (15,5%), amendoim (18,5%), farinha de soja (20,0%), óleo de milho (6,0%), ração Bio Tec (30,0%) e bolacha wafer de chocolate (10,0%). A mistura foi peletizada e submetida à análise bromatológica. A dieta foi ofertada a ratos Wistar durante uma semana; posteriormente, os animais foram divididos em três grupos, de acordo com o ganho de peso. O terço superior foi considerado propenso à obesidade e o terço inferior, resistente à obesidade. Após 80 dias de oferta da dieta, os animais foram sacrificados e foram quantificados o peso corpóreo, consumo alimentar, gorduras retroperitoneal, periepididimal, de carcaça e gorduras totais. RESULTADOS: Verificou-se que a dieta apresentava 5,31kcal/g, com a seguinte composição: 22,3% de gordura, 22,2% de proteína, 15,9% de fibra, estimando-se 35,7% de carboidrato. Ratos propensos à obesidade, alimentados por 87 dias com a dieta hipercalórica, apresentaram peso corpóreo, gorduras retroperitoneal, periepididimal e totais significativamente maiores do que animais resistentes à obesidade (p<0,05). O consumo de alimentos também foi maior em animais propensos (p<0,05). Verificou-se também que a substituição da caseína pela farinha de soja, como componente proteico da ração, levou à diminuição de 96,0% no custo do estudo. CONCLUSÃO: A dieta formulada com farinha de soja apresentou custo reduzido e foi capaz de desenvolver o fenótipo obeso em ratos propensos, à semelhança do observado na literatura com outras dietas.

Ingestão do cálcio na obesidade de mulheres atendidas pelo Sistema Único de Saúde

OBJETIVOS: Verificar a associação entre consumo de cálcio e obesidade em uma amostra de mulheres obesas ou eutróficas. MÉTODOS: Por meio de inquéritos alimentares, estimou-se a ingestão de cálcio de 177 mulheres hipertensas e/ou diabéticas mediante recordatórios de 24h e frequência de consumo alimentar. Estudo caso-controle teve o grupo-estudo composto por 102 mulheres obesas e o grupo-controle por 75 mulheres eutróficas. Os dados de ingestão foram comparados às recomendações dietéticas e às porções de alimentos de origem animal, recomendados pela pirâmide alimentar brasileira, que são fontes de cálcio. Na análise estatística dos dois grupos segundo faixa etária, utilizou-se o coeficiente de correlação linear simples de Pearson com nível de significância de até 5% de probabilidade de erro experimental. RESULTADOS: A ingestão quantitativa de cálcio foi semelhante entre os grupos e igualmente insuficiente para atingir as recomendações nutricionais. A análise da frequência de consumo de fontes de cálcio revelou que os dois grupos apresentavam consumo inferior a três porções/dia, merecendo destaque o grande número que referiu "raramente" consumir tais alimentos. CONCLUSÃO: Não foi observada nessa população a associação entre obesidade e ingestão de cálcio. Seu consumo foi insuficiente para atingir as quantidades recomendadas, um achado relevante. Considerando a idade das mulheres estudadas e o diagnóstico de hipertensão e diabetes, é evidente a necessidade de atividades de educação nutricional para estimular o consumo de fontes alimentares de cálcio com o intuito de auxiliar no controle da hipertensão e de prevenir agravos importantes, como a obesidade e a osteoporose.

Ingestão de lipídios na dieta e indicadores antropométricos de adiposidade em policiais militares

OBJETIVO: Investigar se há relação entre a ingestão de lipídios e os indicadores antropométricos de adiposidade em policiais militares do Município de Cascavel, (PR). MÉTODOS: A amostra constituiu-se de 183 policiais militares do sexo masculino do 6º Batalhão da Polícia Militar de Cascavel (PR), com idade entre 21 e 50 anos. Avaliou-se o peso, a estatura, o índice de massa corporal, a circunferência abdominal e a ingestão alimentar, por meio do recordatório de 24horas. Relacionaram-se os resultados de ingestão de lipídios da dieta com os indicadores antropométricos índice de massa corporal, circunferência abdominal e percentual de gordura corporal. RESULTADOS: O diagnóstico nutricional mais freqüente em 117 (63,9%) dos policiais, segundo o índice de massa corporal, foi de sobrepeso e obesidade; 22 (12,0%) apresentaram risco elevado para complicações metabólicas associadas à obesidade pelo indicador circunferência abdominal e 26 (18,6%) elevado percentual de gordura corporal. A ingestão de lipídios se mostrou aumentada em 53 (70,7%) dos 75 inquéritos validados, no entanto apenas 24 (32,0%) ingeriam lipídios saturados acima da recomendação. Houve correlação positiva apenas entre a ingestão de lipídios totais e o indicador antropométrico de adiposidade circunferência abdominal (p=0,03). CONCLUSÃO: Este estudo sugere que a ingestão de lipídios acima das recomendações pode ser um fator relacionado à adiposidade abdominal na população estudada.

[Experimental model to induce obesity in rats]

The etiology of obesity is multifactorial and is becoming a problem of public health, due to its increased prevalence and the consequent repercussion of its comorbidities on the health of the population. The great similarity and homology between the genomes of rodents and humans make these animal models a major tool to study conditions affecting humans, which can be simulated in rats. Obesity can be induced in animals by neuroendocrine, dietary or genetic changes. The most widely used models to induce obesity in rats are a lesion of the ventromedial hypothalamic nucleus (VMH) by administering monosodium glutamate or a direct electrical lesion, ovariectomy, feeding on hypercaloric diets and genetic manipulation for obesity.