Influence of proinflammatory cytokine gene polymorphism on childhood obesity

Genetics, epigenetics and transgenerational transmission of obesity in children

Sedentary lifestyle and consumption of high-calorie foods have caused a relentless increase of overweight and obesity prevalence at all ages. Its presently epidemic proportion is disquieting due to the tight relationship of obesity with metabolic syndrome and several other comorbidities which do call for urgent workarounds. The usual ineffectiveness of present therapies and failure of prevention campaigns triggered overtime a number of research studies which have unveiled some relevant aspects of obesity genetic and epigenetic inheritable profiles. These findings are revealing extremely precious mainly to serve as a likely extra arrow to allow the clinician's bow to achieve still hitherto unmet preventive goals. Evidence now exists that maternal obesity/overnutrition during pregnancy and lactation convincingly appears associated with several disorders in the offspring independently of the transmission of a purely genetic predisposition. Even the pre-conception direct exposure of either father or mother gametes to environmental factors can reprogram the epigenetic architecture of cells. Such phenomena lie behind the transfer of the obesity susceptibility to future generations through a mechanism of epigenetic inheritance. Moreover, a growing number of studies suggests that several environmental factors such as maternal malnutrition, hypoxia, and exposure to excess hormones and endocrine disruptors during pregnancy and the early postnatal period may play critical roles in programming childhood adipose tissue and obesity. A deeper understanding of how inherited genetics and epigenetics may generate an obesogenic environment at pediatric age might strengthen our knowledge about pathogenetic mechanisms and improve the clinical management of patients. Therefore, in this narrative review, we attempt to provide a general overview of the contribution of heritable genetic and epigenetic patterns to the obesity susceptibility in children, placing a particular emphasis on the mother-child dyad.

The impact of TNF-α 308G>A gene polymorphism on children's overweight risk and an assessment of biochemical variables: A cross-sectional single-center experience

INTRODUCTION

The aim of this study was to assess the role of TNF-α 308 G>A gene polymorphism in children's overweight risk so as to correlate this polymorphism with anthropometric and biochemical variables.

MATERIALS AND METHOD

A cross-sectional study was carried out on 188 Romanian children ages 5-18 years, who were classified into controls (Group 1; n = 109) and overweight children (Group 2; n = 79).

RESULTS

Higher values of MUAC and TST (p < 0.001) were obtained in the overweight group. A significant association was found between TNF-α 308 G>A polymorphism and weight status in the studied population (p = 0.009). There was also a positive association between the variant genotypes (GA or AA) of TNF-α 308G>A gene polymorphism and weight status, which was more frequently found among normal weight than overweight children (74.5% versus 25.5%, respectively). The final logistic multivariable included five independent variables (TNF-α genotype, gender, cholesterol, ASAT, and ALAT), which were statistically significant predictors with negative/positive effects on children's overweight risk; this model explained 30% of the variance in the outcome variable.

CONCLUSION

The variant genotype of TNF-α 308G>A gene polymorphism was more frequent among normal weight children. In the presence of other covariates, such as age, gender, cholesterol, LDL cholesterol, ALAT, and glycemia, the TNF-α 308 G>A gene polymorphism remained an independent protective factor for children's overweight status.

Association between -174G>C polymorphism in the IL-6 promoter region and the risk of obesity: A meta-analysis

BACKGROUND

Many researchers have suggested that the -174G>C polymorphism in the interleukin-6 (IL-6) promoter region contributes to the risk of obesity; however, this hypothesis is still inconclusive. Therefore, we conducted a meta-analysis to combine the data from several studies to arrive at a conclusion regarding the association between -174G>C polymorphism and the risk of obesity.

METHODS

The PubMed and Embase databases were searched up to February 20, 2018. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using a random-effects model. Subgroup analysis and sensitivity were also performed.

RESULTS

Ten eligible studies involving 7210 cases were performed to identify the association strength. The association strength was measured by the ORs and 95% CIs. By pooling the eligible studies, we found a significant association between the -174G>C polymorphism and obesity risk (C vs G: OR = 1.37; 95% CI, 1.08-1.74; Pheterogeneity < .01). Overall, individuals with the variant CC (OR = 1.58; 95% CI, 1.09-2.28; Pheterogeneity < 0.01) and GC/CC (OR = 1.61; 95% CI, 1.13-2.29; Pheterogeneity < .01) were associated with a significantly increased risk of obesity.

CONCLUSION

The meta-analysis results suggested that the polymorphism -174G>C in the IL-6 promoter region was associated with a significantly increased risk of obesity.

Genetic Contributions to Childhood Obesity: Association of Candidate Gene Polymorphisms and Overweight/Obesity in Korean Preschool Children

This study was aimed to investigate the association of candidate gene polymorphisms and obesity or overweight in young Korean children. A total of 190 Korean preschool children (96 control, 48 overweight, and 46 obese children) were genotyped for the angiotensin converting enzyme (ACE) insertion (I)/deletion (D), angiotensin II type 2 receptor (AT2) C3123A, transforming growth factor (TGF)-β1 T869C, vascular endothelial growth factor (VEGF) T460C, and tumor necrosis factor (TNF)-α G308A polymorphisms. No differences were found among the groups with respect to age, sex, birth weight, blood pressure levels, and serum concentrations of glucose and total cholesterol. Obese children showed a higher incidence of ACE DD genotype and D allelic frequency compared to the controls (odds ratio [OR], 2.7, 95% confidence interval [CI], 1.01-7.21; OR, 2.5, 95% CI, 1.49-4.19; all P < 0.05). The frequency of TC genotype and C allele in the TGF-β1 T869C polymorphism (OR, 2.08, 95% CI, 1.01-4.27; OR, 1.93, 95% CI, 1.15-3.21) and that in the VEGF T460C polymorphism (OR, 2.5, 95% CI, 1.19-5.28; OR, 2.15, 95% CI, 1.26-3.68) was also higher in obese children than in control subjects (all P < 0.05). Overweight children exhibited a higher frequency of the A allele in the AT2 C3123A polymorphism compared to the controls (OR, 1.72, 95% CI, 1.03-2.88, P < 0.05). There were no differences in the TNF-α G308A polymorphism among the groups. The ACE I/D, AT2 C3123A, TGF-β1 T869C, and VEGF T460C polymorphisms can affect susceptibility to obesity or overweight in Korean children.

Influence of Interleukin-6 (174G/C) Gene Polymorphism on Obesity in Egyptian Children

BACKGROUND:

Obesity is a multi-factorial chronic disorder. A considerable number of studies have been performed to figure out whether there is an association between obesity and polymorphisms of gene IL-6 (174G/C), but the results are equivocal.

AIM:

This study aimed to find out whether the IL-6 (174G/C) gene was associated with the risk of developing obesity in Egyptian children.

SUBJECTS AND METHODS:

The study included 149 children and adolescents with age ranged between 9.5 – 18 years. Eighty-five of them were obese which BMIZ-score is > 2, and sixty-four children with BMIZ-score ≤ 2 served as control group. Serum level of IL-6 and genetic analysis for IL-6 (174G/C) gene polymorphism were done.

RESULTS:

Obese children had significantly higher serum levels of IL-6 as compared to those of control children (P = 0.003). A high percentage of IL-6 polymorphism GC was found in obese subjects (93.7%), while the control group had a higher percentage of IL-6 polymorphism GG (70.6 %).

CONCLUSION:

Our study showed that carriers of the C allele for the IL-6 (174G/C) polymorphism have higher BMI. As the G174C polymorphism is likely to affect IL-6 expression and its physiological regulation; consequently this polymorphism may affect adiposity.

The role of IL-6 572 C/G, 190 C/T, and 174 G/C gene polymorphisms in children's obesity

The aim of this study was to establish the correlations between the polymorphisms of the genes interleukin (IL)-6 572, 190, and 174 in obese children. We assessed 222 hospitalized children divided into two groups: group I (control) included 110 patients with normal nutritional status, and group II consisted of 102 obesity patients. The two groups underwent IL-6 572 C/G, 190 C/T, and 174 G/C polymorphism testing, measurement of anthropometric parameters (mid-upper arm circumference and tricipital skinfold thickness), and paraclinical evaluation (protein, albumin, leptin, adiponectin, and vascular endothelial growth factor (VEGF)). We observed that phenotype CC was more frequent in obese children for IL-6 572 (p = 0.0001), whereas CG heterozygotes were more frequent in the obese group for the IL-6 190 gene (62.7 %; p = 0.0001). Leptin was dependent on IL-6 572 and IL-6 174 gene polymorphisms and albumin, whereas adiponectin was dependent on the IL-6 174 gene polymorphism. Body mass index (BMI), mid-upper arm circumference (MUAC), and tricipital skinfold thickness (TST) serum albumin levels correlated with C allele carriers of the IL-6 572 and IL-6 190 genes in children with obesity, whereas the CC genotype of IL-6 174 was a protective factor for obesity.

CONCLUSION

Obesity is most frequently associated in children with IL-6 174 C allele carriers and with IL-6 190 C allele carriers.

Genetic polymorphisms in adipokine genes and the risk of obesity: a systematic review and meta-analysis

Polymorphisms in adipokine genes, such as leptin (LEP), leptin receptor (LEPR), resistin (RETN), adiponectin (ADIPOQ), interleukin-1β (IL-1β), IL-6 (IL-6), and tumor necrosis factor-α (TNF-α) may be involved in the development of obesity. We conducted a systematic review of published evidence on the association between different adipokine genes and the risk of obesity. Librarian-designed searches of PubMed and HuGeNet, review of reference lists from published reviews and content expert advice identified potentially eligible studies. The genotyping information and polymorphisms of different adipokine genes, numbers of genotyped cases and controls and frequencies of genotypes were extracted from 48 eligible studies included in this review. Twenty-one polymorphisms each associated with obesity in at least one study were identified. Polymorphisms in the adipokine genes, LEP, LEPR, and RETN were not associated with obesity susceptibility, whereas ADIPOQ G276T (T vs. G: odds ratio (OR), 1.59; 95% confidence interval (CI), 1.39-1.81), IL-1β C3953T (CC vs. CT+TT: OR, 1.61; 95% CI, 1.18-2.20), and TNF-α G308A (GG vs. GA+AA: OR, 1.19; 95% CI, 1.02-1.39) polymorphisms were associated with an increased risk of obesity. The IL-6 G174C polymorphism was also associated obesity when using allelic comparisons, the recessive genetic model and the dominant genetic model with OR (95% CI) of 1.95 (1.37-2.77), 1.44 (1.15-1.80), and 1.36 (1.16-1.59), respectively. No significant evidence of publication bias was present. However, these "null" results were underpowered due to a small pooled sample size, and analysis of additional case-control studies with larger sample sizes should provide further clarifications.

Influence of interleukin-6 and G174C polymorphism in IL-6 gene on obesity and energy balance

Obesity is a multifactor disease with a very complicated etiology. Genetic factors play an important role in the development of primary obesity. They may be responsible for up to 40% of causes leading to obesity. There are a great number of genes affecting food intake and energy expenditure. Serious consequences accompanying obesity, e.g., type 2 diabetes and lipid abnormalities may be caused by increased level of proinflammatory cytokines, such as IL-1, IL-6, and TNF. It is possible that polymorphisms located in cytokine genes affect the level of protein expression. It is known that IL-6 plays a role in lipid metabolism and energy expenditure. The polymorphism found in point 174 (G174C) of a promoter region of IL-6 gene affects the level of interleukin-6 expression and, consequently, may lead to obesity and correlated conditions.