Leptin Receptor Gene Variation Predicts Weight Change in Subjects with Impaired Glucose Tolerance

Future Perspectives of Personalized Weight Loss Interventions Based on Nutrigenetic, Epigenetic, and Metagenomic Data

As obesity has become a major global public health challenge, a large number of studies have analyzed different strategies aimed at inducing a negative energy balance and, consequently, body weight loss. However, most existing weight loss programs are generally unsuccessful, so several interventions have been carried out to identify physiologic and behavioral factors concerning this variability in order to implement more personalized treatment. Nowadays, an individualized approach is being proposed through so-called personalized nutrition, whereby not only the phenotype but also the genotype is used for customized nutrition treatment. Regarding body weight regulation, ∼70 polymorphisms have been identified in or near genes related to energy expenditure, appetite, adipogenesis, insulin resistance, and lipid metabolism. Although personalized nutrition refers mainly to genetic makeup, recent advances in the investigation of the epigenome and the microbiome open the door to implement more personalized recommendations for body weight management. In this context, recent studies have demonstrated the existence of several epigenetic markers that may modify gene expression and could be involved in the outcome of weight loss interventions. Moreover, different studies have shown that dietary interventions could affect the composition of gut microbiota and have an impact on body weight. The integration of nutrigenetic, epigenetic, and metagenomic data may lead to the design of more personalized dietary treatments to prevent chronic diseases and to optimize the individual's response to dietary interventions.

Monosodium glutamate versus diet induced obesity in pregnant rats and their offspring

BACKGROUND

We aim at determining the role of monosodium glutamate (MSG) compared with high caloric chow(HCC) in development of obesity in pregnant rats and their offspring.

METHODS

Ninety pregnant rats were divided into 3 groups, control, MSG and HCC fed. We determined energy intake, body weight (BW), abdominal fat, fat to body weight ratio, serum glucose, insulin, leptin, lipid profile, ob and leptin receptor-b gene expressions in pregnant rats and ob and leptin receptor-b gene expressions, serum insulin,glucose, leptin, triacylglycerides (TAG), total lipids (TL) and BW in offspring.

RESULTS

Although daily energy intake and BW of MSG treated rats were lower than those of HCC fed rats, their abdominal fat and fat body weight ratio were higher. MSG or HCC increased Ob gene expression, leptin, insulin,LDL, cholesterol, total lipids (TL), glucose and decreased leptin receptor-b gene expression. In offspring of MSG treated rats, BW, serum glucose, insulin, leptin, TAG, TL and Ob gene expression increased and leptin receptor-b gene expression decreased whereas in offspring of HCC fed rats, serum insulin, leptin, Ob and leptin receptor-b gene expression increased but serum glucose, TAG, TL or BW did not change.

CONCLUSION

We conclude that in pregnant rats, MSG, in spite of mild hypophagia, caused severe increase in fat body weight ratio, via leptin resistance, whereas, HCC increased BW and fat body weight ratio, due to hyperphagia with consequent leptin resistance. Moreover, maternal obesity in pregnancy, caused by MSG, has greater impact on offspring metabolism and BW than that induced by HCC.

Association between the Gln223Arg polymorphism of the leptin receptor and metabolic syndrome in free-living community elderly

BACKGROUND

Metabolic syndrome is a cluster of cardiovascular risk factors. Aging and gene-environmental interactions are involved in the pathophysiology of metabolic syndrome. The LEPR gene Gln223Arg polymorphism has been associated with energy metabolism and body weight.

METHODS

The association of the Gln223Arg polymorphism with metabolic syndrome was evaluated in a case-control study with elderly subjects (> or = 60 years old). The case-control groups were: (1) healthy group (HG), individuals without any cardio-metabolic diseases (CMD) or previous cardiovascular events (n = 64); (2) metabolic disorder group (MD), subjects with at least one metabolic disorder (hypertension, obesity, dyslipidemia, and impaired glucose tolerance, n = 306); and (3) metabolic syndrome group (MS) (n = 98). The Gln223Arg polymorphism of the LEPR gene was determined by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) using Msp I endonuclease enzyme restriction.

RESULTS

The mean age of the HG subjects was 70.12 +/- 7.7, and the MD and MS subjects were 69.7 +/- 6.4 and 69.68 +/- 5.0 years old, respectively. The MS group showed higher body mass index (BMI), waist circumference, systolic and diastolic blood pressure, glucose, cholesterol, triglycerides, and low-density lipoprotein cholesterol (LDL-C) levels than did the HG individuals. The analysis showed differences in genotype frequencies: reduction in the Gln/Gln genotype and an excess of the Arg/Arg genotype in MD (chi(2) = 7.886, P = 0.019) and MS (chi(2) = 14.941, P = 0.001) when compared to the HG group.

CONCLUSIONS

This study provides evidence for a role of the LEPR gene Gln223Arg polymorphism in predisposition to metabolic syndrome in the elderly.

Leptin-receptor polymorphisms relate to obesity through blunted leptin-mediated sympathetic nerve activation in a Caucasian male population

Leptin plays a key role in the regulation of body weight through the sympathetic nervous system; however, the contributions of leptin-receptor polymorphisms to obesity and sympathetic nerve activity have not been fully clarified. In the present study, we examined the relationships between leptin-receptor polymorphisms, plasma leptin and whole-body norepinephrine (NE) spillover as an index of sympathetic nerve activity in a Caucasian male cohort. In 129 young healthy normotensive men with a wide range of body mass index (BMI) (19.4-39.5 kg/m(2)), we measured leptin-receptor polymorphisms (Gln223Arg, Lys656Asn, and Lys109Arg), plasma leptin levels, whole-body NE spillover, whole-body NE clearance, BMI and blood pressure (BP) levels in the supine position after overnight fasting. Overweight-obese (BMI>or=25 kg/m(2)) subjects had significantly greater BMI, BP levels, plasma leptin and whole-body NE spillover compared to lean (BMI<25 kg/m(2)) subjects, but the NE clearance was similar. Overweight-obese subjects had significantly higher frequencies of the Arg223 allele and the Arg223 homozygous allele of Gln223Arg and the Asn656 allele of Lys656Asn compared to lean subjects. Subjects carrying the Arg223 homozygous or the Asn656 allele had higher levels of plasma leptin, BMI, waist circumference, and waist-to-hip ratio, but significantly less whole-body NE spillover, especially when they were also overweight-obese. BP levels and whole-body NE clearance were similar between subjects with and without the Arg223 homozygous or Asn656 allele. No differences were found in the distributions of the Arg109 allele of Lys109Arg polymorphism between nonobese and overweight-obese subjects. In addition, BMI, BP, plasma leptin levels, whole-body NE spillover and whole-body NE clearance were similar between those with and without the Arg109 allele. Together, these findings demonstrate that leptin-receptor polymorphisms were related to the incidence of obesity in a Caucasian male population. These polymorphisms were accompanied by high plasma leptin levels (leptin resistance) and lower whole-body plasma NE spillover (blunted sympathetic nerve activity). We therefore hypothesize that leptin-receptor play a role in the development of obesity through leptin resistance and blunted leptin-mediated sympathetic nerve activity.

Genotype-specific weight loss treatment advice: how close are we?

Obesity, whose prevalence is continually rising, is one of the world’s greatest health care burdens. This multifactorial condition is associated with many obesity-related conditions, such as type 2 diabetes, dyslipidemia, and cardiovascular disease. Weight loss is a significant challenge facing those wishing to reduce their disease risk. Of course, like obesity itself, weight loss is a complex phenomenon dependent on many environmental and genetic influences, and thus individual responses to weight loss interventions are incredibly variable. Currently, there are 3 major interventions used to reduce weight: diet, exercise, and pharmacotherapy. The findings from studies examining gene–diet (nutrigenetic), gene–exercise (actigenetic), and gene–pharmaceutical (pharmacogenetic) interactions, although not clinically applicable at this time, are gaining awareness. This review article summarizes the current evidence to support the contribution of DNA sequence variation in genes related to energy balance (expenditure and intake) in the response to weight loss intervention. There is no doubt that replication using more rigorous study designs that include the study of interactions between multiple genes and interventions is required to move towards the development of genotype-specific weight loss treatment strategies.

Effect of genotype on success of lifestyle intervention in subjects at risk for type 2 diabetes

Lifestyle intervention programs including increased physical activity and healthy nutrition have been proven to delay the onset of type 2 diabetes. This is achieved mainly by reducing body weight and improving insulin sensitivity. However, response to lifestyle or dietary interventions does differ between individuals, and the genetic or environmental factors that may account for these differences are not yet precisely characterized. Identification of these factors would be desirable in order to provide an individually tailored preventive strategy for patients at risk of developing diabetes. This review summarizes the so far known genetic variations, which determine responders and nonresponders to a lifestyle intervention. In addition, general methodological approaches to study gene-lifestyle interactions are described.

Effect of genetic variation in the leptin gene promoter and the leptin receptor gene on obesity risk in a population-based case-control study in Spain

There are no good genetic markers for incorporating the study of genetic susceptibility to obesity in epidemiological studies. In animal models, the leptin (LEP) and the leptin receptor (LEPR) genes have been shown to be very important in obesity because leptin functions as a negative feedback signal in regulating body-weight through reducing food intake and stimulating energy expenditure. In humans, several polymorphisms in these genes have been described. However, their association with obesity is still very controversial because there are no good case-control studies designed to specifically test this association. Our objective has been to conduct a population-based case-control study to estimate the risk of obesity arising from the -2548G > A and Q223R polymorphisms in the LEP and LEPR genes, respectively. 303 obese cases (101 men and 202 women) and 606 controls (202 men and 404 women) were selected from a Spanish Mediterranean population. Genetic, clinical and life-style characteristics were analyzed. No association was found between the -2548G > A polymorphism and obesity. However, the Q223R variant was significantly associated with obesity in a recessive model, the RR genotype being more prevalent in controls than in obese subjects. The inverse association between the Q223R polymorphism and obesity (OR = 0.62; 95% CI: 0.39-0.99) remained significant even after additional adjustment for education, tobacco smoking, alcohol, physical activity, origin of the obese patient, and the -2548G > A polymorphism in the LEP gene (OR = 0.54; 95% CI: 0.32-0.89). In conclusion, the -2548G > A polymorphism is not a relevant obesity marker in this Mediterranean population, although Q223R does seen to be so.

The human obesity gene map: the 2005 update

This paper presents the 12th update of the human obesity gene map, which incorporates published results up to the end of October 2005. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTL) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2005, 176 human obesity cases due to single-gene mutations in 11 different genes have been reported, 50 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 244 genes that, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 408. The number of human obesity QTLs derived from genome scans continues to grow, and we now have 253 QTLs for obesity-related phenotypes from 61 genome-wide scans. A total of 52 genomic regions harbor QTLs supported by two or more studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably, with 426 findings of positive associations with 127 candidate genes. A promising observation is that 22 genes are each supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. The electronic version of the map with links to useful publications and relevant sites can be found at http://obesitygene.pbrc.edu.