Serum leptin and homeostasis model assessment-IR as novel predictors of early liver fibrosis in chronic hepatitis B virus infection.

BACKGROUND: The relationship between hepatitis B virus (HBV) infection, leptin and insulin resistance remains unclear. We hypothesised links between serum leptin and insulin resistance in non-diabetic patients with chronic viral hepatitis B infection and their relation to liver fibrosis. METHODS: We recruited 190 untreated patients with chronic HBV infection and 72 healthy controls. Serum leptin, fasting glucose, insulin, liver function tests (LFTs), C-peptide and Homeostasis model assessment-IR (HOMA-IR) were measured/calculated by ELISA and standard techniques. RESULTS: Serum leptin, C-peptide (both P < 0.001), HOMA-IR (P = 0.021) and several LFTs were increased in patients with chronic HBV-infection. In multivariate regression analysis, both HOMA-IR (P = 0.003) and leptin (P = 0.002) were significant independent predictors of HBV infection. There were significant positive correlations (P < 0.01) between leptin and HOMA-IR (r = 0.81), between serum leptin and METAVIR activity (r = 0.95), and between HOMA-IR and BMI (r = 0.75), fasting glucose (r = 0.005), and fasting insulin (r = 0.81). Several LFTs, glucose and insulin correlated modestly (r = 0.61-0.69, P < 0.05) with leptin. CONCLUSION: Serum leptin may be related to the rate of fibrosis progression in nondiabetic patients with chronic HBV infection. Follow-up by serial measurement of serum leptin and HOMA-IR in non diabetic HBV-infected patients may be used as a non-invasive marker of early liver fibrosis.

Assessment of Human Tribbles Homolog 3 Genetic Variation (rs2295490) Effects on Type 2 Diabetes Patients with Glucose Control and Blood Pressure Lowering Treatment.

Effects of human tribbles homolog 3 (TRIB3) genetic variation (c.251 A>G, Gln84Arg, rs2295490) on the clinical outcomes of vascular events has not been evaluated in patients with type 2 diabetes after blood pressure lowering and glucose controlling treatment. We did an analysis of a 2×2 factorial (glucose control axis and blood pressure lowering axis) randomized controlled clinical trial at 61 centers in China, with a follow-up period of 5years. The major vascular endpoints were the composites of death from cardio-cerebral vascular diseases, non-fatal stroke and myocardial infraction, new or worsening renal and diabetic eye disease. A total of 1884 participants were included in our research with a 4.8years median follow-up. For glucose lowering axis, patients with TRIB3 (rs2295490) AA (n=609) genotype exhibited significantly reduced risk of major vascular events compared with AG+GG (n=335) genotype carriers (Hazard ratio 0.72, 95% CI 0.55-0.94, p=0.016), Paradoxically, the risk of vascular events were significantly increased in patients with AA (n=621) compared to AG+GG (n=319) genotype for intensive glucose control (Hazard ratio 1.46, 95% CI, 1.06­2.17, p = 0.018) [corrected]. . For blood pressure lowering axis, marginally significant difference was found between TRIB3 variant and coronary events. Our findings suggest that good glucose and blood pressure control exhibited greater benefits on vascular outcomes in patients with TRIB3 (rs2295490) G allele.

Blood pressure interacts with APOE ε4 to predict memory performance in a midlife sample.

OBJECTIVE: Elevated blood pressure and the Apolipoprotein ε4 allele (APOE ε4) are independent risk factors for Alzheimer's disease. We sought to determine whether the combined presence of the APOE ε4 allele and elevated blood pressure is associated with lower cognitive performance in cognitively healthy middle-aged adults. METHODS: A total of 975 participants aged 30-54 (mean age = 44.47) were genotyped for APOE. Cardiometabolic risk factors including blood pressure, lipids, and glucose were assessed and cognitive function was measured using the Trail Making Test and the Visual Reproduction and Logical Memory subtests from the Wechsler Memory Scale. RESULTS: Multivariable regression analysis showed that the association between APOE ε4 and episodic memory performance varied as a function of systolic blood pressure (SBP), such that elevated SBP was predictive of poorer episodic memory performance only in APOE ε4 carriers (ß = -.092; t = -2.614; p = .009). Notably, this association was apparent at prehypertensive levels (≥130 mmHg), even after adjusting for physical activity, depression, smoking, and other cardiometabolic risk factors. CONCLUSIONS: The joint presence of APOE ε4 and elevated SBP, even at prehypertensive levels, is associated with lower cognitive performance in healthy, middle-aged adults. Results of this study suggest that the combination of APOE ε4 and elevated SBP may synergistically compromise memory function well before the appearance of clinically significant impairments. Interventions targeting blood pressure control in APOE ε4 carriers during midlife should be studied as a possible means to reduce the risk of cognitive decline in genetically susceptible samples.

Meta-analysis of genome-wide association study of homeostasis model assessment ß cell function and insulin resistance in an East Asian population and the European results.

Compared with Western populations, Asians develop diabetes at younger ages, at lower degrees of obesity. Because diabetes and the related traits are influenced by the interplay between genetic and environmental factors, it is important to understand the genetic differences between Asian and Western populations. Recently, a large-scale meta-analysis of genome-wide association studies for beta cell function and insulin resistance in the European ancestry was reported by the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC). The MAGIC study reported 17 SNPs for homeostasis model assessments (HOMA-%B: beta cell function and HOMA-IR: insulin resistance). In this study, we tried to replicate the effects of reported SNPs by MAGIC study, which were influencing HOMAs in two Korean populations. HOMA-IR and HOMA-B were computed using two HOMA models (HOMA1 and HOMA2). The HOMA2 model has recently been updated with physiological adjustments into a computer version, providing a more accurate index. Dupuis et al. (Nat Genet 42: 105-116, 2010). In this study, we examined the reported SNPs in two Korean community-based cohorts (Ansung and Ansan). The Korean genotypes and glucose and insulin traits for 5,974 non-diabetic subjects were obtained from a previous genome-wide association study. Although we expected the HOMA2 to be suitable to replicate the results of different ethnics, our results revealed that the HOMA1 was more significantly replicated. As a result, 5 SNPs (rs10830963 in MTNR1B, rs4607517 in GCK, rs2191349 in DGKB/TMEM195, rs174550 in FADS1, rs7034200 in GLIS3) were significantly replicated with HOMA-%B, but no SNP was replicated with HOMA-IR. Two SNPs (rs560887 in G6PC, rs13266634 in SLC30A8) and one SNP (rs35767 in IGF1) showed the weak association p values (unadjusted p values lower than 0.05) for HOMA-%B and HOMA-IR, respectively. The replicated SNPs and the weakly associated SNPs were also significantly associated with the fasting glucose levels. They revealed the same direction of the effect sizes in both studies, but the effect sizes were stronger in Koreans than in MAGIC. Conclusively, our results indicated that SNPs from MTNR1B, GCK, DGKB, FADS1, and GLIS3 were consistently associated with HOMA-%B in both Korean and MAGIC populations.

Variants in glucose- and circadian rhythm-related genes affect the response of energy expenditure to weight-loss diets: the POUNDS LOST Trial.

BACKGROUND: Circadian rhythm has been shown to be related to glucose metabolism and risk of diabetes, probably through effects on energy balance. Recent genome-wide association studies identified variants in circadian rhythm-related genes (CRY2 and MTNR1B) associated with glucose homeostasis. OBJECTIVE: We tested whether CRY2 and MTNR1B genotypes affected changes in measures of energy expenditure in response to a weight-loss diet intervention in a 2-y randomized clinical trial, the POUNDS (Preventing Overweight Using Novel Dietary Strategies) LOST Trial. DESIGN: The variants CRY2 rs11605924 (n = 721) and MTNR1B rs10830963 (n = 722) were genotyped in overweight or obese adults who were randomly assigned to 1 of 4 weight-loss diets that differed in their proportions of macronutrients. Respiratory quotient (RQ) and resting metabolic rate (RMR) were measured. RESULTS: By 2 y of diet intervention, the A allele of CRY2 rs11605924 was significantly associated with a greater reduction in RQ (P = 0.03) and a greater increase in RMR and RMR/kg (both P = 0.04). The G allele of MTNR1B rs10830963 was significantly associated with a greater increase in RQ (P = 0.01) but was not related to changes in RMR and RMR/kg. In addition, we found significant gene-diet fat interactions for both CRY2 (P-interaction = 0.02) and MTNR1B (P-interaction < 0.001) in relation to 2-y changes in RQ. CONCLUSIONS: Our data indicate that variants in the circadian-related genes CRY2 and MTNR1B may affect long-term changes in energy expenditure, and dietary fat intake may modify the genetic effects. This trial was registered at www.clinicaltrials.gov as NCT00072995.

Genotype by energy expenditure interaction with metabolic syndrome traits: the Portuguese healthy family study.

Moderate-to-high levels of physical activity are established as preventive factors in metabolic syndrome development. However, there is variability in the phenotypic expression of metabolic syndrome under distinct physical activity conditions. In the present study we applied a Genotype X Environment interaction method to examine the presence of GxEE interaction in the phenotypic expression of metabolic syndrome. A total of 958 subjects, from 294 families of The Portuguese Healthy Family study, were included in the analysis. Total daily energy expenditure was assessed using a 3 day physical activity diary. Six metabolic syndrome related traits, including waist circumference, systolic blood pressure, glucose, HDL cholesterol, total cholesterol and triglycerides, were measured and adjusted for age and sex. GxEE examination was performed on SOLAR 4.3.1. All metabolic syndrome indicators were significantly heritable. The GxEE interaction model fitted the data better than the polygenic model (p<0.001) for waist circumference, systolic blood pressure, glucose, total cholesterol and triglycerides. For waist circumference, glucose, total cholesterol and triglycerides, the significant GxEE interaction was due to rejection of the variance homogeneity hypothesis. For waist circumference and glucose, GxEE was also significant by the rejection of the genetic correlation hypothesis. The results showed that metabolic syndrome traits expression is significantly influenced by the interaction established between total daily energy expenditure and genotypes. Physical activity may be considered an environmental variable that promotes metabolic differences between individuals that are distinctively active.

Genetic and functional assessment of the role of the rs13431652-A and rs573225-A alleles in the G6PC2 promoter that are strongly associated with elevated fasting glucose levels.

OBJECTIVE: Genome-wide association studies have identified a single nucleotide polymorphism (SNP), rs560887, located in a G6PC2 intron that is highly correlated with variations in fasting plasma glucose (FPG). G6PC2 encodes an islet-specific glucose-6-phosphatase catalytic subunit. This study examines the contribution of two G6PC2 promoter SNPs, rs13431652 and rs573225, to the association signal. RESEARCH DESIGN AND METHODS: We genotyped 9,532 normal FPG participants (FPG <6.1 mmol/l) for three G6PC2 SNPs, rs13431652 (distal promoter), rs573225 (proximal promoter), rs560887 (3rd intron). We used regression analyses adjusted for age, sex, and BMI to assess the association with FPG and haplotype analyses to assess comparative SNP contributions. Fusion gene and gel retardation analyses characterized the effect of rs13431652 and rs573225 on G6PC2 promoter activity and transcription factor binding. RESULTS: Genetic analyses provide evidence for a strong contribution of the promoter SNPs to FPG variability at the G6PC2 locus (rs13431652: ß = 0.075, P = 3.6 × 10(-35); rs573225 ß = 0.073 P = 3.6 × 10(-34)), in addition to rs560887 (ß = 0.071, P = 1.2 × 10(-31)). The rs13431652-A and rs573225-A alleles promote increased NF-Y and Foxa2 binding, respectively. The rs13431652-A allele is associated with increased FPG and elevated promoter activity, consistent with the function of G6PC2 in pancreatic islets. In contrast, the rs573225-A allele is associated with elevated FPG but reduced promoter activity. CONCLUSIONS: Genetic and in situ functional data support a potential role for rs13431652, but not rs573225, as a causative SNP linking G6PC2 to variations in FPG, though a causative role for rs573225 in vivo cannot be ruled out.

Serum lipids, glucose and insulin levels in healthy schoolchildren aged 9 and 15 years from Central Sweden: reference values in relation to biological, social and lifestyle factors.

BACKGROUND: There is a shortage of reference values for cardiovascular risk factors such as serum lipids, glucose and insulin related to biological, social and lifestyle factors for Swedish children and adolescents. Such values are needed for planning and evaluation of public health activities, and for clinical use. DESIGN AND METHODS: Data for this cross-sectional, school-based study were collected during a school year (September to May). A random sample of 1137 girls and boys aged 9 and 15 years from two locations in central Sweden participated in the study, and blood samples were taken from 969 of them. METHODS: Fasting serum blood samples were analysed for triglycerides, total cholesterol, high-density lipoprotein cholesterol, glucose and insulin. Physical examination included measurement of height, weight and pubertal status. Questionnaires provided family background data. Total physical activity was measured by accelerometer registration. RESULTS: Serum levels differed significantly between age and gender groups and were correlated to pubertal status. Neither genetic nor socio-economic background nor smoking status influenced the serum levels. Insulin levels were elevated in subjects with a body mass index in the highest decentile, compared with the levels in the rest of the subjects. The insulin levels were inversely associated with total physical activity, and physical activity varied with season. CONCLUSIONS: Pubertal status (biological age) should to be considered in the interpretation of serum values in schoolchildren rather than chronological age. The interpretation of insulin values should include both body mass index and physical activity level, and perhaps also season. Previously described regional differences in serum lipid levels in Swedish adults seem to be present also in children.

A genome scan for fasting insulin and fasting glucose identifies a quantitative trait locus on chromosome 17p: the insulin resistance atherosclerosis study (IRAS) family study.

Plasma insulin and glucose concentrations are important quantitative phenotypes related to diabetes and the metabolic syndrome. Reports purporting to identify quantitative trait loci (QTLs) that contribute to the variation in fasting insulin and glucose concentrations are discrepant. As part of the Insulin Resistance Atherosclerosis Study (IRAS) Family Study, a genome scan was performed in African-American (n = 42) and Hispanic (n = 90) extended families to identify regions that may contain positional candidate genes for fasting insulin and fasting glucose (n = 1,604 subjects). There was significant evidence for linkage of fasting insulin to the short arm of chromosome 17 (logarithm of odds [LOD] = 3.30; 54 cM between D17S1294 and D17S1299, P = 1.0 x 10(-4)). The strongest evidence for linkage over all pedigrees for fasting glucose was also observed in this region (LOD = 1.44; 58 cM, P = 9.9 x 10(-3)). The results of this study provide impetus for future positional cloning of QTLs regulating insulin and glucose levels. Identifying genes in these regions should provide insight into the nature of genetic factors regulating plasma glucose and insulin concentrations.