Genetics of metabolic syndrome

Current Data and New Insights into the Genetic Factors of Atherogenic Dyslipidemia Associated with Metabolic Syndrome

Atherogenic dyslipidemia plays a critical role in the development of metabolic syndrome (MetS), being one of its major components, along with central obesity, insulin resistance, and hypertension. In recent years, the development of molecular genetics techniques and extended analysis at the genome or exome level has led to important progress in the identification of genetic factors (heritability) involved in lipid metabolism disorders associated with MetS. In this review, we have proposed to present the current knowledge related to the genetic etiology of atherogenic dyslipidemia, but also possible challenges for future studies. Data from the literature provided by candidate gene-based association studies or extended studies, such as genome-wide association studies (GWAS) and whole exome sequencing (WES,) have revealed that atherogenic dyslipidemia presents a marked genetic heterogeneity (monogenic or complex, multifactorial). Despite sustained efforts, many of the genetic factors still remain unidentified (missing heritability). In the future, the identification of new genes and the molecular mechanisms by which they intervene in lipid disorders will allow the development of innovative therapies that act on specific targets. In addition, the use of polygenic risk scores (PRS) or specific biomarkers to identify individuals at increased risk of atherogenic dyslipidemia and/or other components of MetS will allow effective preventive measures and personalized therapy.

Prevalence of ApoB100 rs693 gene polymorphism in metabolic syndrome among female students at King Abdulaziz University

Apolipoprotein B100 (ApoB100) is a glycoprotein and a member of the adipokine family. It plays a central role in lipoprotein metabolism. Many research studies have revealed a strong relation between ApoB100 and metabolic syndrome (MetS) and insulin resistance.

In our research, we examined the relationship between ApoB100 rs693 gene polymorphism, body mass index (BMI) and the probability of MetS in young female students studying at King Abdulaziz University (KAU) in Saudi Arabia. The study group comprised 141 females whose ages ranged from 18 to 25 years. Anthropometric measurements and biochemical parameters were measured alongside a genetic analysis of ApoB100 rs693.

The BMI, glucose concentration and total cholesterol level were found to be significantly associated with the ApoB100 rs693 gene. The differences noted between control and MetS groups regarding glucose concentrations were statistically significant (P = 0.001).

A growing number of young females are being diagnosed with MetS in KAU because of unhealthy eating habits, in combination with the absence of physical exercise, causing increased body weight and the potential progression of chronic diseases. Our study showed that the allele associated with hypertensive individuals at ApoB100 rs693 and MetS may have a direct genetic influence. Further research on expanded sample sizes, however, is required in order to draw rigid conclusions.

Promoter Methylation Leads to Decreased ZFP36 Expression and Deregulated NLRP3 Inflammasome Activation in Psoriatic Fibroblasts

The mRNA-destabilizing protein tristetraprolin (TTP), encoded by the ZFP36 gene, is known to be able to end inflammatory responses by directly targeting and destabilizing mRNAs encoding pro-inflammatory cytokines. We analyzed its role in psoriasis, a disease characterized by chronic inflammation. We observed that TTP is downregulated in fibroblasts deriving from psoriasis patients compared to those deriving from healthy individuals and that psoriatic fibroblasts exhibit abnormal inflammasome activity compared to their physiological counterpart. This phenomenon depends on TTP downregulation. In fact, following restoration, TTP is capable of directly targeting for degradation NLRP3 mRNA, thereby drastically decreasing inflammasome activation. Moreover, we provide evidence that ZFP36 undergoes methylation in psoriasis, by virtue of the presence of long stretches of CpG dinucleotides both in the promoter and the coding region. Besides confirming that a perturbation of TTP expression might underlie the pathogenesis of psoriasis, we suggest that deregulated inflammasome activity might play a role in the disease alongside deregulated cytokine expression.

Intergenerational implications of alcohol intake: metabolic disorders in alcohol-naïve rat offspring

Alcohol drinking may be associated with an increased risk of various metabolic diseases. Rat lines selectively bred for alcohol preference and alcohol avoidance constitute an interesting model to study inherited factors related to alcohol drinking and metabolic disorders. The aim of the present study was to compare the levels of selected laboratory biomarkers of metabolic disorders in blood samples from naïve offspring of Warsaw alcohol high-preferring (WHP), Warsaw alcohol low-preferring (WLP), and wild Wistar rats. Blood samples were collected from 3-month old (300–350 g) alcohol-naïve, male offspring of WHP (n = 8) and WLP rats (n = 8), as well as alcohol-naïve, male, wild Wistar rats. Markers of metabolic, hepatic, and pancreatic disorders were analysed (levels of homocysteine, glucose, total cholesterol, triglycerides and γ-glutamyl transferase (GGT), aspartate (AST), alanine aminotransferase (ALT), and amylase serum activities). Alcohol-naïve offspring of WHP, WLP, and wild Wistar rats differed significantly in the levels of triglycerides, total cholesterol, homocysteine, as well as in the activity of GGT, ALT, AST, and amylase enzymes. Most markers in the alcohol-naïve offspring of WHP rats were altered even thought they were never exposed to alcohol pre- or postnatally. This may suggest that parental alcohol abuse can have a detrimental influence on offspring vulnerability to metabolic disorders.

A Slow-Digesting Carbohydrate Diet during Rat Pregnancy Protects Offspring from Non-Alcoholic Fatty Liver Disease Risk through the Modulation of the Carbohydrate-Response Element and Sterol Regulatory Element Binding Proteins

High-fat (HF) and rapid digestive (RD) carbohydrate diets during pregnancy promote excessive adipogenesis in offspring. This effect can be corrected by diets with similar glycemic loads, but low rates of carbohydrate digestion. However, the effects of these diets on metabolic programming in the livers of offspring, and the liver metabolism contributions to adipogenesis, remain to be addressed. In this study, pregnant insulin-resistant rats were fed high-fat diets with similar glycemic loads but different rates of carbohydrate digestion, High Fat-Rapid Digestive (HF–RD) diet or High Fat-Slow Digestive (HF–SD) diet. Offspring were fed a standard diet for 10 weeks, and the impact of these diets on the metabolic and signaling pathways involved in liver fat synthesis and storage of offspring were analyzed, including liver lipidomics, glycogen and carbohydrate and lipid metabolism key enzymes and signaling pathways. Livers from animals whose mothers were fed an HF–RD diet showed higher saturated triacylglycerol deposits with lower carbon numbers and double bond contents compared with the HF–SD group. Moreover, the HF–RD group exhibited enhanced glucose transporter 2, pyruvate kinase (PK), acetyl coenzyme A carboxylase (ACC) and fatty acid (FA) synthase expression, and a decrease in pyruvate carboxylase (PyC) expression leading to an altered liver lipid profile. These parameters were normalized in the HF–SD group. The changes in lipogenic enzyme expression were parallel to changes in AktPKB phosphorylation status and nuclear expression in carbohydrate-response element and sterol regulatory element binding proteins. In conclusion, an HF–RD diet during pregnancy translates to changes in liver signaling and metabolic pathways in offspring, enhancing liver lipid storage and synthesis, and therefore non-alcoholic fatty liver disease (NAFLD) risk. These changes can be corrected by feeding an HF–SD diet during pregnancy.

Effects of RHD gene polymorphisms on distinguishing weak D or DEL from RhD- in blood donation in a Chinese population

BACKGROUND

Weak D or DEL red blood cell units may be mistyped as RhD- by current serology assays, which can lead to incompatible transfusion to RhD- recipients and further cause anti-D immunization. Molecular RHD blood group typing is a very effective method for overcoming current technical limits. The purpose of this study was to identify RHD single-nucleotide polymorphisms (SNPs) and compare the genotype prevalence among confirmed RhD- individuals in a Chinese population as well as explore effective biomarkers for current weak D or DEL detection before blood transfusion.

METHODS

In the present study, 125 weak D (1, 2, 3, and 4.1) or DEL and 185 RhD- blood samples from donors detected by current standard serology were collected. Genotyping system was used to analyze the SNPs of RHD in each sample.

RESULTS

Seven SNPs (rs592372, rs11485789, rs6669352, rs3118454, rs1053359, rs590787, and rs3927482) were detected in the RHD region. Rs3118454, rs1053359, rs590787, and rs3927482 showed significant differences between the weak D (1, 2, 3 and 4.1) or DEL and RhD- groups. Further combined analysis of the allelic distribution of these four SNPs revealed their higher frequencies in the RhD- group.

CONCLUSION

The SNPs rs3118454, rs1053359, rs590787, and rs3927482 in RHD showed a significantly higher frequency among an RhD- Chinese population and are potential biomarkers.

The association of vaspin rs2236242 and leptin rs7799039 polymorphism with metabolic syndrome in Egyptian women

BACKGROUND/AIM

Genetic predisposition is implicated in the etiology of metabolic syndrome. This study aimed to investigate the1397645907association of vaspin rs2236242 and leptin rs7799039 polymorphisms with their serum levels and with the risk of developing metabolic syndrome in Egyptian women.

MATERIALS AND METHODS

This case control study included 100 Egyptian women with metabolic syndrome and 100 without metabolic syndrome. The genotypes of vaspin rs2236242 and leptin rs7799039 were detected by a methodology based on PCR-RFLP. Serum vaspin and leptin levels were determined by ELISA.

RESULTS

The metabolic syndrome group was associated with higher serum vaspin and leptin levels when compared to the nonmetabolic syndrome group. The AA genotype of leptin rs7799039 was associated with metabolic syndrome and with higher serum leptin levels, while the different genotypes of vaspin rs2236242 were not associated with metabolic syndrome or different serum vaspin levels.

CONCLUSION

The AA genotype of leptin rs7799039 was associated with metabolic syndrome and higher serum leptin levels. Serum leptin and vaspin can be used as diagnostic markers of metabolic syndrome.

Cardiometabolic risk factors predict cerebrovascular health in older adults: results from the Brain in Motion study

Aging and physical inactivity are associated with an increased risk of developing metabolic syndrome (MetS). With the rising prevalence of MetS, it is important to determine the extent to which it affects cerebrovascular health. The primary purpose of this report is to examine the impact of MetS on cerebrovascular health (resting cerebral blood flow (CBF) peak velocity (V¯P), cerebrovascular conductance (CVC), and CBF responses to hypercapnia) in healthy older adults with normal cognition. A secondary goal was to examine the influence of apolipoprotein E (APOE) ε4 expression on these indices. In a sample of 258 healthy men and women older than 53 years, 29.1% met criteria for MetS. MetS, sex, and age were found to be significant predictors of CVC, and V¯P, MetS, and APOE status were significant predictors of V¯P-reactivity, and CVC-reactivity was best predicted by MetS status. After controlling for these factors, participants with MetS demonstrated lower cerebrovascular measures (CVC, V¯P, CVC-reactivity, and V¯P-reactivity) compared to participants without MetS. APOE ε4 carriers had higher V¯P-reactivity than noncarriers. These results provide evidence that cardiometabolic and vascular risk factors clustered together as the MetS predict measures of cerebrovascular health indices in older adults. Higher V¯P-reactivity in APOE ε4 carriers suggests vascular compensation for deleterious effects of this known risk allele for Alzheimer's disease and stroke.

Association of chemerin Rs17173608 and vaspin Rs2236242 gene polymorphisms with metabolic syndrome in Egyptian women

AIM

The metabolic syndrome is a complex of interrelated risk factors for cardiovascular disease and diabetes. The adipokines, chemerin and vaspin, are known to have metabolic regulatory roles. This study aimed to assess the relation of chemerin rs17173608 and vaspin rs2236242 polymorphisms with metabolic syndrome and its related phenotypes in Egyptian women.

SUBJECTS AND METHODS

The study included 100 healthy female subjects and 100 metabolic syndrome patients. The component traits of metabolic syndrome were determined and the genotypes of the polymorphisms were assessed using the tetra amplification refractory mutation system polymerase chain reaction procedure.

RESULTS

The minor G allele of the chemerin rs17173608 polymorphism had a significantly higher frequency in metabolic syndrome patients (p = 0.0001). The component traits of metabolic syndrome were significantly increased in the carriers of the GG and TG genotypes. In contrast, the rare A allele of vaspin rs2236242 polymorphism was significantly higher in the control subjects (p = 0.005). The carriers of the TA and AA genotypes showed significant relation with lower values of the phenotypes of metabolic syndrome.

CONCLUSION

Metabolic syndrome in Egyptian females is associated with the minor allele of chemerin rs17173608 polymorphism, whereas the minor allele of vaspin rs2236242 polymorphism plays a protective role against metabolic syndrome.

Prevalence, associated factors and heritabilities of metabolic syndrome and its individual components in African Americans: the Jackson Heart Study

OBJECTIVE

Both environmental and genetic factors play important roles in the development of metabolic syndrome (MetS). Studies about its associated factors and genetic contribution in African Americans (AA) are sparse. Our aim was to report the prevalence, associated factors and heritability estimates of MetS and its components in AA men and women.

PARTICIPANTS AND SETTING

Data of this cross-sectional study come from a large community-based Jackson Heart Study (JHS). We analysed a total of 5227 participants, of whom 1636 from 281 families were part of a family study subset of JHS.

METHODS

Participants were classified as having MetS according to the Adult Treatment Panel III criteria. Multiple logistic regression analysis was performed to isolate independently associated factors of MetS (n=5227). Heritability was estimated from the family study subset using variance component methods (n=1636).

RESULTS

About 27% of men and 40% of women had MetS. For men, associated factors with having MetS were older age, lower physical activity, higher body mass index, and higher homocysteine and adiponectin levels (p<0.05 for all). For women, in addition to all these, lower education, current smoking and higher stress were also significant (p<0.05 for all). After adjusting for covariates, the heritability of MetS was 32% (p<0.001). Heritability ranged from 14 to 45% among its individual components. Relatively higher heritability was estimated for waist circumference (45%), high density lipoprotein-cholesterol (43%) and triglycerides (42%). Heritability of systolic blood pressure (BP), diastolic BP and fasting blood glucose was 16%, 15% and 14%, respectively.

CONCLUSIONS

Stress and low education were associated with having MetS in AA women, but not in men. Higher heritability estimates for lipids and waist circumference support the hypothesis of lipid metabolism playing a central role in the development of MetS and encourage additional efforts to identify the underlying susceptibility genes for this syndrome in AA.

Exaggerated Acute Lung Injury and Impaired Antibacterial Defenses During Staphylococcus aureus Infection in Rats with the Metabolic Syndrome

Rats with Metabolic Syndrome (MetaS) have a dysregulated immune response to the aseptic trauma of surgery. We hypothesized that rats with MetaS would have dysregulated inflammation, increased lung injury, and less effective antibacterial defenses during Staphylococcus (S.) aureus sepsis as compared to rats without MetaS. Low capacity runner (LCR; a model of MetaS) and high capacity runner (HCR) rats were challenged intravenously with S. aureus bacteria. After 48 h, inflammatory mediators and bacteria were quantified in the blood, bronchoalveolar lavage fluid (BALF), and lung homogenates. Lungs were analyzed histologically. BALF protein and lung wet-dry ratios were quantified to assess for vascular leak. Endpoints were compared in infected LCR vs HCR rats. LCR rats had higher blood and lung S. aureus counts, as well as higher levels of IL-6 in plasma, lungs and BALF, MIP-2 in plasma and lung, and IL-17A in lungs. Conversely, LCR rats had lower levels of IL-10 in plasma and lungs. Although lactate levels, and liver and renal function tests were similar between groups, LCR rats had higher BALF protein and lung wet-dry ratios, and more pronounced acute lung injury histologically. During S. aureus bacteremia, as compared with HCR rats, LCR (MetaS) rats have heightened pro-inflammatory responses, accompanied by increased acute lung injury and vascular leak. Notably, despite an augmented pro-inflammatory phenotype, LCR rats have higher bacterial levels in their blood and lungs. The MetaS state may exacerbate lung injury and vascular leak by attenuating the inflammation-resolving response, and by weakening antimicrobial defenses.

Insulin resistance and its consequences in chronic hepatitis C

Chronic hepatitis C (CHC) is generally a slowly progressive disease, but some factors associated with rapid progression have been identified. Hepatitis C virus (HCV) may contribute to a broad spectrum of metabolic disturbances - namely, steatosis, insulin resistance (IR), increased prevalence of impaired glucose tolerance, type 2 diabetes mellitus (T2DM), lipid metabolism abnormalities and atherosclerosis. HCV can directly or indirectly cause both IR and steatosis, but it is still not resolved whether this viral impact bears the same prognostic value as the metabolic counterparts. As the population exposed to HCV ages, the morbidity due to this disease is increasing. The rising epidemic of obesity contributes to higher prevalence of IR and T2DM. Our understanding of the mutual association between both disease states continues to grow, but is still far from complete. This review briefly discusses the most probable mechanisms involved in IR development in the course of CHC. Molecular mechanisms for the direct and indirect influence of HCV on intracellular insulin signaling are described. Subsequently, the consequences of IR/T2DM for disease progression and management are summarized.

Dietary patterns interact with APOA1/APOC3 polymorphisms to alter the risk of the metabolic syndrome: the Tehran Lipid and Glucose Study

The interaction of genetic and dietary factors, as an area of CVD research, has been explored poorly. The aim of the present study was to examine the interaction of dietary patterns and three genetic variants of APOA1 and APOC3, both independently and in combination, relative to the risk of the metabolic syndrome (MetS) in Tehranian adults. In the present matched, nested case–control study, 414 subjects with the MetS and 414 controls were selected from the participants of the Tehran Lipid and Glucose Study. Dietary patterns were determined by factor analysis. APOC3 (rs5128 3238C>G) and APOA1 (rs670, − 75G>A and rs5069,+83C>T) SNP were genotyped by the conventional PCR followed by the restriction fragment length polymorphism technique. Overall, three major dietary patterns were extracted: healthy dietary pattern (HDP); Western dietary pattern (WDP); fat–sweet dietary pattern (FSDP). The A and T allele carriers of the APOA1 SNP had a greater risk of developing the MetS in the highest quartile of WDP scores (OR 3·22, 95 % CI 1·21, 8·58, Pinteraction= 0·03). Compared with other genotype combinations, the combined effect of APOC3/APOA1 (CC/GA+AA/CT+TT) genotypes showed a further increase in the risk of the MetS in the highest quartile of WDP scores (OR 1, 2·49, 8·73, 6·32, Ptrend< 0·001, Pinteraction= 0·003). A significant interaction was found between the quartiles of FSDP scores and the APOA1 diplotype (GA+AA/CT+TT). OR for these genotype carriers were 1, 0·65, 0·57 and 0·22 (Ptrend= 0·006) in the lowest to the highest quartile of FSDP scores when compared with the other combined genotypes (Pinteraction= 0·03). Our findings suggest that the WDP and FSDP are associated with APOA1 and APOC3 SNP in relation to the risk of the MetS.

The association of metabolic syndrome and urolithiasis

There has been an increasing prevalence of kidney stones over the last 2 decades worldwide. Many studies have indicated a possible association between metabolic syndrome and kidney stone disease, particularly in overweight and obese patients. Many different definitions of metabolic syndrome have been suggested by various organizations, although the definition by the International Diabetes Federation (IDF) is universally considered as the most acceptable definition. The IDF definition revolves around 4 core components: obesity, dyslipidemia, hypertension, and diabetes mellitus. Several hypotheses have been proposed to explain the pathophysiology of urolithiasis resulting from metabolic syndrome, amongst which are the insulin resistance and Randall's plaque hypothesis. Similarly the pathophysiology of calcium and uric acid stone formation has been investigated to determine a connection between the two conditions. Studies have found many factors contributing to urolithiasis in patients suffering from metabolic syndrome, out of which obesity, overweight, and sedentary lifestyles have been identified as major etiological factors. Primary and secondary prevention methods therefore tend to revolve mainly around lifestyle improvements, including dietary and other preventive measures.

Pathway Analysis of Metabolic Syndrome Using a Genome-Wide Association Study of Korea Associated Resource (KARE) Cohorts

Metabolic syndrome (MetS) is a complex disorder related to insulin resistance, obesity, and inflammation. Genetic and environmental factors also contribute to the development of MetS, and through genome-wide association studies (GWASs), important susceptibility loci have been identified. However, GWASs focus more on individual single-nucleotide polymorphisms (SNPs), explaining only a small portion of genetic heritability. To overcome this limitation, pathway analyses are being applied to GWAS datasets. The aim of this study is to elucidate the biological pathways involved in the pathogenesis of MetS through pathway analysis. Cohort data from the Korea Associated Resource (KARE) was used for analysis, which include 8,842 individuals (age, 52.2 ± 8.9 years; body mass index, 24.6 ± 3.2 kg/m(2)). A total of 312,121 autosomal SNPs were obtained after quality control. Pathway analysis was conducted using Meta-analysis Gene-Set Enrichment of Variant Associations (MAGENTA) to discover the biological pathways associated with MetS. In the discovery phase, SNPs from chromosome 12, including rs11066280, rs2074356, and rs12229654, were associated with MetS (p < 5 × 10(-6)), and rs11066280 satisfied the Bonferroni-corrected cutoff (unadjusted p < 1.38 × 10(-7), Bonferroni-adjusted p < 0.05). Through pathway analysis, biological pathways, including electron carrier activity, signaling by platelet-derived growth factor (PDGF), the mitogen-activated protein kinase kinase kinase cascade, PDGF binding, peroxisome proliferator-activated receptor (PPAR) signaling, and DNA repair, were associated with MetS. Through pathway analysis of MetS, pathways related with PDGF, mitogen-activated protein kinase, and PPAR signaling, as well as nucleic acid binding, protein secretion, and DNA repair, were identified. Further studies will be needed to clarify the genetic pathogenesis leading to MetS.

Parent-offspring association of metabolic syndrome in the Framingham Heart Study

BACKGROUND

Metabolic syndrome (MetS) is a clustering of five metabolic risk factors including abdominal obesity, elevated blood pressure, hypertriglyceridemia, low high-density lipoprotein cholesterol (HDL-C), and impaired fasting glucose. Few studies have fully reported the strength of clustering of these risk factors in a parent-offspring relationship. This analysis describes the associations between parents and their adult offspring in regard to MetS. It also estimates the association between each risk factor in parents and the presence of MetS in their offspring.

METHODS

We analyzed data for 1193 offspring (565 sons, and 628 daughters) from the Framingham Offspring Study who attended examinations 5, 6, and 7. Information about their parents was collected from examinations 13, 14 and 15 of the Framingham Original Cohort study. We used pedigree file to combine parental and offspring's data. Participants were classified as having the MetS according to the Adult Treatment Panel III criteria. Analyses were conducted separately for mothers and fathers. Logistic regression was used to estimate the associations.

RESULTS

After adjusting for age, education, smoking, alcohol consumption and physical activity level of offspring, no significant association was found between father's and their offspring's MetS. Mother's MetS was significantly and positively associated with their daughter's MetS (adjusted odds ratio or adj OR: 1.63; 95% confidence Interval, CI:1.02-2.61), but not with their sons' MetS. When analyzed by individual components, maternal impaired glucose (adj OR: 2.03; 95% CI: 1.02- 9.31), abdominal obesity (adj OR: 1.56; 95% CI: 0.98- 2.55) and low HDL-C (adj OR: 2.12; 95% CI: 1.36-3.32) were associated daughter's MetS. Maternal low HDL-C and raised total cholesterol showed marginal association with son's MetS. For fathers, only impaired glucose (adj OR: 4.91; 95% CI: 2.07- 11.68) was associated with their daughter's MetS.

CONCLUSIONS

Using the data from Framingham Heart Study, we demonstrate differential association of MetS and its components between parents and offspring. Mother's MetS was strongly related with daughter's MetS, but the association was inconsistent with son's MetS. No association was found between father's MetS and offspring's Mets. These results provide evidence that daughters with mother's MetS are in higher risk than daughters or sons with father's MetS.

Associations between the GNB3 C825T polymorphism and obesity-related metabolic risk factors in Korean obese women

PURPOSE

It is important to identify a 'metabolically unhealthy obese' subset with higher cardiovascular risk among obese individuals. We investigated the associations between the GNB3 C825T polymorphism and obesity-related metabolic risk factors among Korean obese women.

METHODS

This study was a sub-investigation of a double-blind randomized controlled trial that examined the additive effect of or list at on weight loss with sibutramine. A sample of 111 obese women were divided into T-carriers (CT/TT) or a homozygous CC group, according to the presence of the 825T allele at GNB3. These groups were compared to determine their associations with obesity-related metabolic risk factors, i.e., fasting plasma glucose, serum lipids, serum insulin/insulin resistance, and abdominal fat amounts.

RESULTS

The allele frequencies of the GNB3 polymorphism were C allele = 59.5% and T allele = 40.5%. The T allele was found to be significantly associated with greater visceral fat and higher serum lipids, and these significances remained robust after adjusting for potential covariates.

CONCLUSIONS

The GNB3 825T polymorphism is significantly associated with greater visceral fat and higher serum lipids in Korean obese women and it suggests that the GNB3 C825T is a determinant of obesity-related metabolic traits in this population.

Thyroid function in adult Nigerians with metabolic syndrome

Introduction

Metabolic syndrome and thyroid dysfunction are two common disorders encountered in the metabolic clinic. Recently, there has been increased interest in the association between the two disorders because of the similarities between symptoms of hypothyroidism and components of the metabolic syndrome. While some reports suggest that metabolic syndrome is associated with subclinical hypothyroidism, this concept is largely under investigated in Nigerian adults with metabolic syndrome. The aim of this study is to determine the thyroid function status of adult Nigerians with metabolic syndrome and determine the association, if any, between metabolic syndrome and thyroid function.

Methods

This was a cross sectional study of one hundred and fifty adults, members of staff of the College of Medicine of the University of Lagos. The participants were recruited using a cluster random sampling method. The Ethical Research & Review Committee of the institution approved the study protocol and signed informed consent was obtained from the participants. The statistics was analysed using the IBM SPSS Software of version 19.0. The Student's t test, Chi square test and multivariate regression analysis were employed for the analysis. Statistical significance was set at p < 0.05.

Results

Thirty nine (twenty-six percent) of the study participants had metabolic syndrome and one hundred and eleven (seventy-four percent) of the study participants did not have metabolic syndrome, served as controls. Those who had metabolic syndrome group were significantly older (p = 0.03), metabolic syndrome was significantly associated with the female gender (p = 0.0002), higher systolic blood pressure (p = 0.0034), diastolic blood pressure (p = 0.0009), waist circumference (p < 0.0001), body mass index (p < 0.0001), waist-hip ratio (p = 0.003), fasting serum glucose (p = 0.0457) and free thyroxine (fT4) levels (p = 0.0496). Those with metabolic syndrome had significantly lower HDL (P = 0.004) and free triiodothyronine (fT3) levels (p = 0.037). There was no statistically significant difference in the thyroid stimulating hormone (TSH) levels between individuals with and without metabolic syndrome. Thirty-three percent of the metabolic syndrome cases had sick euthyroid syndrome (p= < 0.0001). In multivariate regression, waist circumference was significantly and inversely associated with the sick euthyroid syndrome (p = 0.011).

Conclusion

Metabolic syndrome is associated with the sick euthyroid syndrome in adult Nigerians. Abdominal obesity appears to be the link between metabolic syndrome and the sick euthyroid syndrome.

Dysfunction of inflammation-resolving pathways is associated with exaggerated postoperative cognitive decline in a rat model of the metabolic syndrome

The cholinergic antiinflammatory pathway (CAP), which terminates in the spleen, attenuates postoperative cognitive decline (PCD) in rodents. Surgical patients with metabolic syndrome exhibit exaggerated and persistent PCD that is reproduced in postoperative rats selectively bred for easy fatigability and that contain all features of metabolic syndrome (low-capacity runners [LCRs]). We compared the CAP and lipoxin A(4) (LXA(4)), another inflammation-resolving pathway in LCR, with its counterpart high-capacity runner (HCR) rats. Isoflurane-anesthetized LCR and HCR rats either underwent aseptic trauma involving tibial fracture (surgery) or not (sham). At postoperative d 3 (POD3), compared with HCR, LCR rats exhibited significantly exaggerated PCD (trace fear conditioning freezing time 43% versus 57%). Separate cohorts were killed at POD3 to collect plasma for LXA4 and to isolate splenic mononuclear cells (MNCs) to analyze CAP signaling, regulatory T cells (Tregs) and M2 macrophages (M2 Mφ). Under lipopolysaccharide (LPS) stimulation, tumor necrosis factor (TNF)-α produced by splenic MNCs was 117% higher in LCR sham and 52% higher in LCR surgery compared with HCR sham and surgery rats; LPS-stimulated TNF-α production could not be inhibited by an α7 nicotinic acetylcholine receptor agonist, whereas inhibition by the β(2) adrenergic agonist, salmeterol, was significantly less (-35%) than that obtained in HCR rats. Compared to HCR, sham and surgery LCR rats had reduced β(2) adrenergic receptor-expressing T lymphocytes (59%, 44%), Tregs (47%, 54%) and M2 Mφ (45%, 39%); surgical LCR rats' hippocampal M2 Mφ was 66% reduced, and plasma LXA4 was decreased by 120%. Rats with the metabolic syndrome have ineffective inflammation-resolving mechanisms that represent plausible reasons for the exaggerated and persistent PCD.

The interaction of metabolic factors with HCV infection: does it matter?

Given the pandemic spread of the hepatitis C virus (HCV) infection and the metabolic syndrome (MS), the burden of their interaction is a major public health issue, bound to increase in the near term. A better appreciation of the clinical consequences of the relationship between HCV and MS is needed, not only due to their potential synergism on liver disease severity, but also because of the multifaceted interactions between HCV and glucose and lipid metabolism. HCV infection per se does not carry an increased risk of MS, but is able to perturb glucose homeostasis through several direct and indirect mechanisms, leading to both hepatic and extrahepatic insulin resistance. This translates into accelerated liver disease progression (including the development of hepatocellular carcinoma), reduced response to antivirals and, in susceptible individuals, increased risk of developing full-blown type 2 diabetes. HCV may also cause hepatic steatosis, especially in patients infected with genotype 3, although the clinical impact of viral steatosis is debated. Possibly as a result of HCV-induced insulin resistance, and despite a paradoxically favourable lipid profile, the cardiovascular risk is moderately increased in chronic hepatitis C. In addition, the interaction with the MS further increases the risks of cirrhosis, hepatocellular carcinoma, diabetes, and cardiovascular events. Thus, targeted lifestyle and pharmacological measures are urgently warranted in chronic hepatitis C with metabolic alterations.

Influence of age on the association of GIRK4 with metabolic syndrome

BACKGROUND

G protein-coupled inward rectifier K+ channel 4 (GIRK4) gene expressions have been implicated in the development of obesity, a key feature of metabolic syndrome (MetS). We investigated whether sequence variants of GIRK4 may represent metabolic risk factors for the Uygur Chinese population.

METHODS

The entire GIRK4 gene, including all exons, the promoter and untranslated regions from 48 MetS individuals, was studied in order to identify genetic variations associated with the disorder. Targeted genotyping of four common single nucleotide polymorphisms (SNPs: rs11221497, rs6590357, rs4937391 and rs2604204) and one novel missense mutation (M210I) was performed using the TaqMan polymerase chain reaction method for 443 MetS and 786 non-MetS subjects.

RESULTS

When all MetS cases were compared against all non-MetS controls, no significant association was found between the three SNPs (rs2604204, rs4937391 and rs6590357) and MetS status or metabolic traits. After adjustment, rs11221497 was associated with MetS (odds ratio (OR) [95% CI]=0.731 [0.551-0.968], P=0.029). Interestingly, when the MetS group was stratified into subclasses by age, an association was found for the three SNPs (rs2604204, rs4937391 and rs6590357) having estimated false discovery rates<0.001 and age of <50 y. After adjustment, the SNPs rs2604204, rs4937391 and rs6590357 were also associated with MetS in younger subjects: ORs [95% CI]: 1.678 [1.149-2.450], 1.839 [1.204-2.809] and 0.602 [0.379-0.958], respectively. All of the four SNPs showed a trend towards lower or higher metabolic traits (P<0.05) in younger subjects. In addition, a newly identified missense mutation (M210I) was not specifically related with MetS.

CONCLUSIONS

GIRK4 sequence variants appear to associate with MetS in the Uygurian population, and this association may be influenced by age.

Genome-wide screen for metabolic syndrome susceptibility Loci reveals strong lipid gene contribution but no evidence for common genetic basis for clustering of metabolic syndrome traits

BACKGROUND

Genome-wide association (GWA) studies have identified several susceptibility loci for metabolic syndrome (MetS) component traits, but have had variable success in identifying susceptibility loci to the syndrome as an entity. We conducted a GWA study on MetS and its component traits in 4 Finnish cohorts consisting of 2637 MetS cases and 7927 controls, both free of diabetes, and followed the top loci in an independent sample with transcriptome and nuclear magnetic resonance-based metabonomics data. Furthermore, we tested for loci associated with multiple MetS component traits using factor analysis, and built a genetic risk score for MetS.

METHODS AND RESULTS

A previously known lipid locus, APOA1/C3/A4/A5 gene cluster region (SNP rs964184), was associated with MetS in all 4 study samples (P=7.23×10(-9) in meta-analysis). The association was further supported by serum metabolite analysis, where rs964184 was associated with various very low density lipoprotein, triglyceride, and high-density lipoprotein metabolites (P=0.024-1.88×10(-5)). Twenty-two previously identified susceptibility loci for individual MetS component traits were replicated in our GWA and factor analysis. Most of these were associated with lipid phenotypes, and none with 2 or more uncorrelated MetS components. A genetic risk score, calculated as the number of risk alleles in loci associated with individual MetS traits, was strongly associated with MetS status.

CONCLUSIONS

Our findings suggest that genes from lipid metabolism pathways have the key role in the genetic background of MetS. We found little evidence for pleiotropy linking dyslipidemia and obesity to the other MetS component traits, such as hypertension and glucose intolerance.

Non-alcoholic fatty liver disease and metabolic syndrome in adolescents: pathogenetic role of genetic background and intrauterine environment

In the last three decades the incidence of metabolic syndrome (MetS) has been growing worldwide along with an increase of obesity, type 2 diabetes mellitus, and non-alcoholic fatty liver disease (NAFLD). In children and adolescents such epidemics are particularly worrisome, since the metabolic consequences in adulthood will significantly burden the health care system. Although the definition of MetS in childhood is still controversial, there is agreement with respect to NAFLD being the hepatic manifestation of MetS. However, the molecular pathogenesis of MetS and its contribution to NAFLD is complex and closely related to the pre- and postnatal environment as well as to genetic predisposing factors. The analysis of the possible relationships between NAFLD and MetS is particularly interesting, not only from an epidemiological point of view, but also to better understand the genetic and environmental factors contributing to the development of both diseases. We here summarize the most recent epidemiological data on the incidence of both diseases in adolescents, and several aspects linking MetS with NAFLD, discussing the possible role played by genetics and intrauterine environment.

Impact of perinatal prebiotic consumption on gestating mice and their offspring: a preliminary report

To assess the impact of prebiotic supplementation during gestation and fetal and early neonatal life, gestating BALB/cj dam mice were fed either a control or a prebiotic (galacto-oligosaccharides-inulin, 9:1 ratio)-enriched diet throughout pregnancy and lactation, and allowed to nurse their pups until weaning. At the time of weaning, male offspring mice were separated from their mothers, weaned to the same solid diet as their dam and their growth was monitored until killed 48 d after weaning. Prebiotic treatment affected neither the body-weight gain nor the food intake of pregnant mice. In contrast, at the time of weaning, pups that had been nursed by prebiotic-fed dams had a higher body weight (11.0 (se 1.2) g) than pups born from control dams (9.8 (se 0.9) g). At 48 d after weaning, significantly higher values were observed for colon length and muscle mass in the offspring of prebiotic-fed dams (1.2 (se 0.1) cm/cm and 5.7 (se 1.8) mg/g, respectively), compared with control offspring (1.1 (se 0.1) cm/cm and 2.9 (se 0.9) mg/g, respectively), without any difference in spleen and stomach weight, or serum leptin concentration. The present preliminary study suggests that altering the fibre content of the maternal diet during both pregnancy and lactation enhances offspring growth, through an effect on intestinal and muscle mass rather than fat mass accretion.

The genetics of obesity and the metabolic syndrome

In this review, we discuss the genetic architecture of obesity and the metabolic syndrome, highlighting recent advances in identifying genetic variants and loci responsible for a portion of the variation in components of the metabolic syndrome, namely, adiposity traits, serum HDL and triglycerides, blood pressure, and glycemic traits. We focus particularly on recent progress from large-scale genome-wide association studies (GWAS), by detailing their successes and how lessons learned can pave the way for future discovery. Results from recent GWAS coalesce with earlier work suggesting numerous interconnections between obesity and the metabolic syndrome, developed through several potentially pleiotropic effects. We detail recent work by way of a case study on the cadherin 13 gene and its relation with adiponectin in the HyperGEN and the Framingham Heart Studies, and its association with obesity and the metabolic syndrome. We provide also a gene network analysis of recent variants related to obesity and metabolic syndrome discovered through genome-wide association studies, and 4 gene networks based on searching the NCBI database.

Association of 25(OH)D and PTH with metabolic syndrome and its traditional and nontraditional components

CONTEXT

Emerging evidence suggests that 25-hydroxy vitamin D [25(OH)D] and PTH may play a role in the etiology of the metabolic syndrome (MetS). However, evidence to date is limited and inconsistent, and few studies have examined associations with nontraditional MetS components.

OBJECTIVE

The objective of the study was to examine the association of vitamin D and PTH with MetS and its traditional and nontraditional components in a large multiethnic sample.

DESIGN, SETTING, AND PARTICIPANTS

In this cross-sectional study, we examined 654 participants from London and Toronto, Ontario, Canada, aged 30 yr and older with risk factors for type 2 diabetes.

MAIN OUTCOME MEASURES

Presence of MetS and its traditional and nontraditional components was measured.

RESULTS

Approximately 43% of the study participants were classified as having MetS. Higher 25(OH)D was significantly associated with a reduced presence of MetS after adjustment for age, sex, season, ethnicity, supplement use, physical activity, and PTH (odds ratio 0.76, 95% confidence interval 0.62-0.93). PTH was not associated with the presence of MetS after multivariate adjustment. Multivariate linear regression analyses indicated significant adjusted inverse associations of 25(OH)D with waist circumference, triglyceride level, fasting insulin, and alanine transaminase (P < 0.041). Elevated PTH was positively associated with waist circumference and high-density lipoprotein cholesterol (P < 0.04). Other associations between PTH and MetS components were attenuated after adjustment for adiposity.

CONCLUSIONS

Serum 25(OH)D, but not PTH, was significantly associated with MetS as well as a number of MetS components after multivariate adjustment. These results suggest that low 25(OH)D may play a role in the etiology of the MetS.

Maternal consumption of high-prebiotic fibre or -protein diets during pregnancy and lactation differentially influences satiety hormones and expression of genes involved in glucose and lipid metabolism in offspring in rats

Risk of developing the metabolic syndrome may be influenced by nutritional environment early in life. We examined the effects of high-fibre (HF) and high-protein (HP) diets consumed during pregnancy and lactation on satiety hormones and expression of genes involved in glucose and lipid metabolism in offspring. Wistar dams were fed a control (C), HF or HP diets during pregnancy and lactation. At parturition, litters were culled to ten pups. At 21 d, all pups were weaned onto C diet. At 7, 14, 21, 28 and 35 d after birth, blood was analysed for satiety hormones and tissues for mRNA expression in offspring. No differences were observed in litter size or birth weight. At 21 d, offspring of HF dams had greater adjusted intestinal mass and lower liver weight than those of C but not of HP dams. Plasma glucose at 28 d and amylin at 7, 14 and 28 d were lower in HF v. C and HP offspring. Glucagon-like peptide-1 was higher in HP offspring than in HF offspring at 7 d but was higher in HF v. C offspring at 21 d. Offspring of HF dams had higher glucose transporter (GLUT2 and Na+-dependent glucose/galactose transporter) mRNA expression at 21 d v. C and HP offspring. In brown adipose tissue, HF and HP up-regulated uncoupling protein-1 and PPAR-γ coactivator. HP was associated with increased resistin and IL-6 mRNA expression. The present study demonstrates that maternal diet composition differentially regulates circulating satiety hormones and genes involved in glucose transport and energy metabolism in offspring. These early changes could have long-term consequences for obesity risk.

Interrelationship between exposure to PCDD/Fs and hypertension in metabolic syndrome in Taiwanese living near a highly contaminated area

Metabolic syndrome (MetS) consists of a constellation of metabolic abnormalities that confer increased risk of cardiovascular disease. There is a positive correlation between exposure to persistent organic pollutants and MetS. We examine the association between PCDD/Fs and MetS components in 1490 non-diabetic persons living near a highly dioxin-contaminated area. We used factor analysis, with a set of core variables considered central features of MetS and PCDD/Fs, to group similar risk factors. Serum PCDD/Fs were positively and significantly correlated with the number of MetS components. Four risk factors-lipidemia, blood pressure, body size, and glycemia-accounted for 72.6% of the variance in the 10 core factors, and PCDD/Fs were linked to MetS through shared correlations with high blood pressure. After adjusting for confounding factors, we found that diastolic blood pressure (β=0.018; p=0.006), glucose (β=0.013; p=0.046), and waist circumference (β=0.721; p=0.042) significantly increased with increasing serum PCDD/F levels. We found significant trends for associations between metabolic syndrome and serum low-chlorinated PCDD/Fs. The highest quintiles of 2,3,4,7,8-PeCDF, 1,2,3,6,7,8-HxCDF and 2,3,7,8-TCDD had the top three adjusted ORs (95% CI) of 3.5 (1.9-6.3), 2.9 (1.7-4.9) and 2.8 (1.6-4.9), respectively. We also found a slight monotonic relationship between serum PCDD/Fs and the prevalence of MetS, especially when the serum dioxin level was higher than 25.4pg WHO(98)-TEQ(DF)g(-1) lipid (the fourth Quintile). We hypothesize that high-dose exposure to PCDD/Fs is a blood pressure-related factor that raises MetS risk.

A genome-wide association study of the metabolic syndrome in Indian Asian men

We conducted a two-stage genome-wide association study to identify common genetic variation altering risk of the metabolic syndrome and related phenotypes in Indian Asian men, who have a high prevalence of these conditions. In Stage 1, approximately 317,000 single nucleotide polymorphisms were genotyped in 2700 individuals, from which 1500 SNPs were selected to be genotyped in a further 2300 individuals. Selection for inclusion in Stage 1 was based on four metabolic syndrome component traits: HDL-cholesterol, plasma glucose and Type 2 diabetes, abdominal obesity measured by waist to hip ratio, and diastolic blood pressure. Association was tested with these four traits and a composite metabolic syndrome phenotype. Four SNPs reaching significance level p<5×10⁻⁷ and with posterior probability of association >0.8 were found in genes CETP and LPL, associated with HDL-cholesterol. These associations have already been reported in Indian Asians and in Europeans. Five additional loci harboured SNPs significant at p<10⁻⁶ and posterior probability >0.5 for HDL-cholesterol, type 2 diabetes or diastolic blood pressure. Our results suggest that the primary genetic determinants of metabolic syndrome are the same in Indian Asians as in other populations, despite the higher prevalence. Further, we found little evidence of a common genetic basis for metabolic syndrome traits in our sample of Indian Asian men.

Naringenin decreases progression of atherosclerosis by improving dyslipidemia in high-fat-fed low-density lipoprotein receptor-null mice

OBJECTIVE

Naringenin is a citrus flavonoid that potently inhibits the assembly and secretion of apolipoprotein B100-containing lipoproteins in cultured hepatocytes and improves the dyslipidemia and insulin resistance in a mouse model of the metabolic syndrome. In the present study, we used low-density lipoprotein receptor-null mice fed a high-fat diet (Western, TD96125) to test the hypothesis that naringenin prevents atherosclerosis.

METHODS AND RESULTS

Three groups (chow, Western, and Western plus naringenin) were fed ad libitum for 6 months. The Western diet increased fasting plasma triglyceride (TG) (5-fold) and cholesterol (8-fold) levels compared with chow, whereas the addition of naringenin significantly decreased both lipids by 50%. The Western-fed mice developed extensive atherosclerosis in the aortic sinus because plaque area was increased by 10-fold compared with chow-fed animals. Quantitation of fat-soluble dye (Sudan IV)-stained aortas, prepared en face, revealed that Western-fed mice also had a 10-fold increase in plaque deposits throughout the arch and in the abdominal sections of the aorta, compared with chow. Atherosclerosis in both areas was significantly decreased by more than 70% in naringenin-treated mice. Consistent with quantitation of aortic lesions, the Western-fed mice had a significant 6-fold increase in cholesterol and a 4-fold increase in TG deposition in the aorta compared with chow-fed mice. Both were reduced more than 50% by naringenin. The Western diet induced extensive hepatic steatosis, with a 10-fold increase in both TG and cholesteryl ester mass compared with chow. The addition of naringenin decreased both liver TG and cholesteryl ester mass by 80%. The hyperinsulinemia and obesity that developed in Western-fed mice was normalized by naringenin to levels observed in chow-fed mice.

CONCLUSIONS

These in vivo studies demonstrate that the citrus flavonoid naringenin ameliorates the dyslipidemia in Western-fed low-density lipoprotein receptor-null mice, leading to decreased atherosclerosis; and suggests a potential therapeutic strategy for the hyperlipidemia and increased risk of atherosclerosis associated with insulin resistance.

Type 2 diabetes, cardiovascular disease, and the evolutionary paradox of the polycystic ovary syndrome: a fertility first hypothesis

Worldwide, the high prevalence of the Polycystic Ovary Syndrome (PCOS), a heritable cause of ovarian infertility, is an evolutionary paradox, which provides insight into the susceptibility of well-fed human populations to cardiovascular disease and diabetes. We propose that PCOS, Type 2 diabetes (T2D) and the Metabolic Syndrome are modern phenotypic expressions of a metabolic genotype attuned to the dietary and energetic conditions of the Pleistocene. This metabolic "Fertility First" rather than "Thrifty" genotype persisted at high prevalence throughout the entire agrarian period-from around 12,000 years ago until 1800 AD-primarily, we contend, because it conferred a fertility advantage in an environment defined by chronic and often severe seasonal food shortage. Conversely, we argue that genetic adaptations to a high carbohydrate, low protein agrarian diet, with increased sensitivity to insulin action, were constrained because these adaptations compromised fertility by raising the lower bound of body weight and energy intake optimal for ovulation and reproduction. After 1800, the progressive attainment of dietary energy sufficiency released human populations from this constraint. This release, through the powerful mechanism of fertility selection, increased, in decades rather than centuries, the prevalence of a genotype better suited to carbohydrate metabolism. This putative mechanism for rapid and recent human evolution can explain the lower susceptibility to T2D of today's Europid populations. This hypothesis predicts that the increasing rates of diabetes and cardiovascular disease, which typically accompany economic development, will be tempered by natural, but particularly fertility, selection against the conserved ancestral genotypes that currently underpin them.

Associations between lactase persistence and the metabolic syndrome in a cross-sectional study in the Canary Islands

BACKGROUND

The single nucleotide polymorphism (SNP) LCT -13910 C>T, associated with genetically determined phenotypes of lactase persistence (LP) or non-persistence (LNP), was studied in relation to the metabolic syndrome (MS).

AIM OF THE STUDY

The aim was to determine if milk intake and MS are associated. We applied Mendelian randomization (MR). The SNP, LCT -13910 C>T, with the genotypes LP (TT/CT) and LNP (CC), was taken as a proxy for milk consumption.

METHODS

A representative sample of adults belonging to the Canary Islands Nutrition Survey (ENCA) in Spain aged 18-75 years (n = 551) was genotyped for the LCT -13910 C>T polymorphism. We used the International Diabetes Federation (IDF) criteria to define MS.

RESULTS

60% of the population was LP and 40% LNP. One hundred seven LP subjects (35.0%) and 53 LNP subjects (25.6%) showed MS (chi (2) = 5.04, p = 0.025). LP subjects showed a significantly higher odds ratio (OR) for MS than LNP subjects computed for the whole population: both the crude OR (1.56; 95% CI 1.06-2.31) and adjusted OR for sex, age, daily energy intake, physical activity and educational level (1.57; 95% CI 1.02-2.43). Adjusted OR for women with LP was 1.93; 95% CI 1.06-3.52.

CONCLUSIONS

The T allele of the SNP might constitute a nutrigenetic factor increasing the susceptibility of LP subjects, especially women, to develop MS in the Canary Islands.

The TaqMan method for SNP genotyping

Single nucleotide polymorphisms (SNPs) are common DNA sequence variations that occur at single bases within the genome. SNPs have been instrumental in elucidating the genetic basis of common, complex diseases using genome-wide association studies, candidate gene case-control association studies, and genome-wide linkage analyses. A key to these studies is genotyping of SNPs. Various methods for SNP genotyping have been developed. For a particular genotyping project, the choice of method is dependent on the number of SNPs (n) and the number of DNA samples (m) to be genotyped. For a genome-wide or large-scale project with very high n and small m, the Affymetrix SNP GeneChip and Illumina GoldenGate BeadChips assays are the ideal methods. For a project involving a small number of SNPs (small n) and a large population (high m), the TaqMan assay is the preferred technology as it has high throughput and is highly accurate, precise, time-efficient, and cost-effective. Here, we describe the detailed procedures for TaqMan SNP genotyping assay, including preparation of high-quality DNA samples, the operating protocol, clarification of technical issues, and discussion of several cautionary notes.