Alcohol intake modulates the genetic association between HDL cholesterol and the PPARgamma2 Pro12Ala polymorphism

The peroxisome proliferator-activated receptor gamma (PPARgamma) Pro12Ala polymorphism affects plasma lipids, but to what extent alcohol intake interferes with this association remains unknown. We randomly recruited 251 nuclear families (433 parents and 493 offspring) in the framework of the European Project on Genes in Hypertension study and genotyped 926 participants in whom all serum lipid variables and information on alcohol consumption were available for PPARgamma2 Pro12Ala. Genotype-phenotype relations were assessed using generalized estimating equations (GEE) and a quantitative transmission disequilibrium test (QTDT). The Ala12 allele was more frequent in Novosibirsk (0.17) than in Cracow (0.12) and Mirano (0.11) (P < 0.01). Using GEE (P = 0.03) or QTDT (P = 0.007), Italian offspring carrying the Ala12 allele had higher serum HDL cholesterol than noncarriers. HDL cholesterol levels were on average 0.086 mmol/l (P = 0.001) higher in drinkers than in nondrinkers. Compared with Pro12 homozygotes, Ala12 allele carriers consuming alcohol had higher serum total and HDL cholesterol, with the opposite trend occurring in nondrinkers. This genotype-alcohol interaction was independent of the type of alcoholic beverage and more pronounced in moderate than in heavy drinkers. We conclude that alcohol intake modulates the relation between the PPARgamma2 Pro12Ala and HDL cholesterol level and that, therefore, the Pro12Ala polymorphism, pending confirmation of our findings, might affect cardiovascular prognosis.     

Evidence for greater oxidative substrate flexibility in male carriers of the Pro 12 Ala polymorphism in PPARgamma2.

The Pro12Ala polymorphism of the peroxisome proliferator-activated receptor gamma2 (PPARgamma2) gene is associated with reduced type 2 diabetes risk and increased insulin sensitivity. It is possible that the oxidative shift from lipid to glucose as a fuel is more efficient in Ala allele carriers. To test this hypothesis, we examined carbohydrate and lipid oxidation by indirect calorimetry in lean, glucose tolerant subjects with (X/Ala, n = 25) and without the Pro12Ala polymorphism (Pro/Pro, n = 73) basally and after insulin stimulation during a 2-hour eugylcaemic hyperinsulinaemic clamp. Insulin sensitivity was non-significantly greater in X/Ala (0.13 +/- 0.01 micromol/kg/min/pM) than in Pro/Pro (0.12 +/- 0.01 micromol/kg/min/pM, p = 0.27). Basally, there were no lipid nor carbohydrate oxidation differences between the groups. Interestingly, the decrease in lipid oxidation during insulin stimulation was significantly greater in male X/Ala (- 0.51 +/- 0.06 mg/kg/min) than in male Pro/Pro (- 0.35 +/- 0.04 mg/kg/min, p = 0.03). No difference was observed in females. Analogously, the change in carbohydrate oxidation in male X/Ala (1.34 +/- 0.2 mg/kg/min) was significantly greater than in male Pro/Pro (1.03 +/- 0.12 mg/kg/min, p = 0.05). The respiratory quotient increased more, but not significantly more, in male X/Ala (0.11 +/- 0.01) than in male Pro/Pro subjects (0.08 +/- 0.01, p = 0.08) but similarly in females. These results indicate that the mechanism by which the Ala allele improves insulin sensitivity might involve enhanced suppression of lipid oxidation permitting more efficient (predominantly non-oxidative) glucose disposal. It is unclear why this could be demonstrated only in males, although gender differences in substrate oxidation are well documented.     

Frequency of the Pro 12Ala polymorphism of PPARgamma2 gene in Ukrainian population and its possible role in development of metabolic syndrome

Frequency of the Pro 12Ala gene polymorphism PPARg2 has been studied in 39 healthy men and 42 men with metabolic syndrome (MS) of the age of 40-65 years in Ukrainian population. The frequencies were 27.9% for 12Ala allele, 32.6% for Pro12Ala, and 4.4% for Ala1Ala that is close to the results of estimation of Czech population. The frequency of 12Ala allele was significantly less--18.4% (p < 0.05) in the persons with MS that corresponds to the pre-established information concerning the patients with diabetes of the 2nd type. A tendency has been detected to the increase of the body mass index in patients with 12Ala allele in the metabolic syndrome group.     

Differential effects of the C1431T and Pro12Ala PPARgamma gene variants on plasma lipids and diabetes risk in an Asian population

We investigated the association of C1431T and Pro12Ala polymorphisms at the peroxisome proliferator-activated receptor gamma (PPARgamma) locus with plasma lipids and insulin resistance-related variables, according to diabetes status, in a large and representative Asian population from Singapore consisting of 2,730 Chinese, 740 Malays, and 568 Indians. Moreover, we estimated the diabetes risk and examined gene-nutrient interactions between these variants and the ratio of polyunsaturated fatty acid to saturated fat (SFA) in determining body mass index (BMI) and fasting insulin. We found differential effects of these gene variants. The Pro12Ala polymorphism was more associated with plasma lipids and fasting glucose concentrations, whereas the C1431T polymorphism was related to the risk of diabetes. Carriers of the 12Ala allele had higher HDL-cholesterol than did Pro12Pro homozygotes (P < 0.05), and the effect of the 12Ala allele on fasting glucose was modified by diabetes status (P < 0.001). After controlling for confounders, carriers of the T allele had decreased risk of diabetes compared with CC homozygotes [odds ratio (OR) 0.73, 95% confidence interval (CI) 0.58-0.93; P = 0.011]; this effect was stronger in Indians (OR 0.38, 95% CI 0.15-0.92; P = 0.032). For both polymorphisms, normal subjects carrying the less prevalent allele had higher BMI (P < 0.05). The PUFA/SFA did not modify the effect of these polymorphisms on BMI or insulin.     

Fatty liver in type 2 diabetes mellitus: relation to regional adiposity,fatty acids,and insulin resistance

The current study was undertaken to examine metabolic and body composition correlates of fatty liver in type 2 diabetes mellitus (DM). Eighty-three men and women with type 2 DM [mean body mass index (BMI): 34 +/- 0.5 kg/m2] and without clinical or laboratory evidence of liver dysfunction had body composition assessments of fat mass (FM), visceral adipose tissue (VAT), liver and spleen computed tomography (CT) attenuation (ratio of liver to spleen), muscle CT attenuation, and thigh adiposity; these assessments were also performed in 12 lean and 15 obese nondiabetic volunteers. Insulin sensitivity was measured with a euglycemic insulin infusion (40 mU. m-2. min-1) combined with systemic indirect calorimetry to assess glucose and lipid oxidation, and with infusions of [2H2]glucose for assessment of endogenous glucose production. A majority of those with type 2 DM (63%) met CT criteria for fatty liver, compared with 20% of obese and none of the lean nondiabetic volunteers. Fatty liver was most strongly correlated with VAT (r = -0.57, P < 0.0001) and less strongly but significantly associated with BMI (r = -0.42, P < 0.001) and FM (r = -0.37, P < 0.001), but only weakly associated with subcutaneous adiposity (r = -0.29; P < 0.01). Fatty liver was also correlated with subfascial adiposity of skeletal muscle (r = -0.44; P < 0.01). Volunteers with type 2 DM and fatty liver were substantially more insulin resistant those with type 2 DM but without fatty liver (P < 0.001) and had higher levels of plasma free fatty acids (P < 0.01) and more severe dyslipidemia (P < 0.01), a pattern observed in both genders. Plasma levels of cytokines were increased in relation to fatty liver (r = -0.34; P < 0.01). In summary, fatty liver is relatively common in overweight and obese volunteers with type 2 DM and is an aspect of body composition related to severity of insulin resistance, dyslipidemia, and inflammatory markers.     

Systemic and regional free fatty acid metabolism in type 2 diabetes

To determine whether type 2 diabetes mellitus alters systemic and regional free fatty acid ([3H]palmitate) metabolism, 14 nondiabetic (ND) and 14 type 2 diabetic (D) subjects underwent hyperinsulinemic-hyperglycemic (approximately 9.3 mM) clamps. The subjects were matched for age, body mass index, percent body fat, and fat-free mass. D subjects had more (P < 0.05) visceral fat than ND. During somatostatin, replacement growth hormone, and glucagon infusions, insulin was infused to achieve moderate (approximately 75 pmol/l) and high (approximately 150 pmol/l) physiological insulin levels. D subjects had greater (P < 0.02) systemic and regional (splanchnic and leg) palmitate release than ND subjects during both insulin infusion intervals. The relative contributions of splanchnic, leg, and nonsplanchnic upper body regions to systemic palmitate release did not differ between groups, although the last contributed the most (approximately 75%) to systemic palmitate release. Visceral fat area correlated with systemic palmitate flux (r = 0.45, P < 0.03) during both insulin infusions. We conclude that type 2 diabetes is associated with a generalized impairment in insulin suppression of lipolysis compared with equally obese ND individuals.     

Genetic and environmental components of family history in type 2 diabetes

Family history of diabetes is a major risk factor for type 2 diabetes (T2D), but whether this association derives from shared genetic or environmental factors is unclear. To address this question, we developed a statistical framework that models four components of variance, including known and unknown genetic and environmental factors, using a liability threshold model. Focusing on parental history, we simulated case–control studies with two first-degree relatives for each individual, assuming 50 % genetic similarity and a range of values of environmental similarity. By comparing the association of parental history with T2D in our simulations to case–control studies of T2D nested in the Nurses’ Health Study and Health Professionals Follow-up Study, we estimate that first-degree relatives have a correlation of 23 % (95 % CI 15–27 %) in their environmental contribution to T2D liability and that this shared environment is responsible for 32 % (95 % CI 24–36 %) of the association between parental history and T2D, with the remainder due to shared genetics. Estimates are robust to varying model parameter values and our framework can be extended to different definitions of family history. In conclusion, we find that the association between parental history and T2D derives from predominately genetic but also environmental effects.     

PPAR-gamma2 Pro12Ala polymorphism in the population of obese and non-obese men of the city of Wroclaw

INTRODUCTION: The aim of this study was to examine the association of Pro12Ala PPARgamma2 polymorphism with anthropometric and biochemical parameters defining the risk for the development of metabolic syndrome in a healthy population of men. MATERIAL AND METHODS: The study group consisted of 176 healthy men, aged 25-65 years (average 54.16 years). Polymorphisms of the PPAR-g gene (Pro12Ala, Ala12Ala, Pro12Pro) were explored using the PCR-RFLP method. Plasma glucose, insulin, total cholesterol, LDL, HDL and TG were measured using commercially available kits. RESULTS: The genotypic distribution of the Pro12Ala polymorphism was as follows: Pro/Ala 69.8% (n = 123), Ala/Ala 28.4% (n = 50) and Pro/Pro 1.8% (n = 3). The Pro12Ala and Ala12Ala subjects did not differ in any of the measured variables. The non-obese (BMI < 30 kg/m(2), n = 117) and obese subpopulations (BMI > 30 kg/m(2), n = 56) did not significantly differ in the distribution of the genotypes. In the nonobese subpopulation, the homozygous Ala12 carriers (n = 38, 32.4%) had higher systolic blood pressure, plasma triglycerides, insulin levels and HOMA-IR. CONCLUSIONS: We conclude that despite the high frequency of the Ala allele at the PPAR-gamma2 gene in our population of Polish men, the Ala12 allele does not appear to improve insulin sensitivity or have an influence on the occurrence of obesity. It remains to be explained by larger studies if this polymorphism carries any risk of the development of metabolic abnormalities in non-obese men.     

Discordant effects of a chronic physiological increase in plasma FFA on insulin signaling in healthy subjects with or without a family history of type 2 diabetes

Muscle insulin resistance develops when plasma free fatty acids (FFAs) are acutely increased to supraphysiological levels (approximately 1,500-4,000 micromol/l). However, plasma FFA levels >1,000 micromol/l are rarely observed in humans under usual living conditions, and it is unknown whether insulin action may be impaired during a sustained but physiological FFA increase to levels seen in obesity and type 2 diabetes mellitus (T2DM) (approximately 600-800 micromol/l). It is also unclear whether normal glucose-tolerant subjects with a strong family history of T2DM (FH+) would respond to a low-dose lipid infusion as individuals without any family history of T2DM (CON). To examine these questions, we studied 7 FH+ and 10 CON subjects in whom we infused saline (SAL) or low-dose Liposyn (LIP) for 4 days. On day 4, a euglycemic insulin clamp with [3-3H]glucose and indirect calorimetry was performed to assess glucose turnover, combined with vastus lateralis muscle biopsies to examine insulin signaling. LIP increased plasma FFA approximately 1.5-fold, to levels seen in T2DM. Compared with CON, FH+ were markedly insulin resistant and had severely impaired insulin signaling in response to insulin stimulation. LIP in CON reduced insulin-stimulated glucose disposal (Rd) by 25%, insulin-stimulated insulin receptor tyrosine phosphorylation by 17%, phosphatidylinositol 3-kinase activity associated with insulin receptor substrate-1 by 20%, and insulin-stimulated glycogen synthase fractional velocity over baseline (44 vs. 15%; all P < 0.05). In contrast to CON, a physiological elevation in plasma FFA in FH+ led to no further deterioration in Rd or to any additional impairment of insulin signaling. In conclusion, a 4-day physiological increase in plasma FFA to levels seen in obesity and T2DM impairs insulin action/insulin signaling in CON but does not worsen insulin resistance in FH+. Whether this lack of additional deterioration in insulin signaling in FH+ is due to already well-established lipotoxicity, or to other molecular mechanisms related to insulin resistance that are nearly maximally expressed early in life, remains to be determined.     

Plasma fatty acids of neonates born to mothers with and without gestational diabetes

Women with gestational diabetes mellitus (GDM) and their neonates have lower levels of arachidonic (AA) and docosahexaenoic (DHA) acids in red cell membranes. It is not clear if this abnormality is restricted to red cells or is a generalised problem. We have investigated plasma fatty acids of neonates (venous cord) of GDM (n=37), and non-diabetic (n=31) women. The GDMs had lower levels of dihomogamma-linolenic (20:3n-6, DHGLA) acid, summation operator n-6 metabolites, DHA and summation operator n-3 metabolites (p<0.05) in choline phosphoglycerides (CPG). They also had lower levels of AA (-4.5%), adrenic acid (22:4n-6, -13%), osbond acid (22:5n-6, -7%) and summation operator n-6 (-2.5%). There was a similar pattern in triglycerides (TG) and cholesterol esters (CE). Mead acid, a marker of generalised shortage of derived and parent essential fatty acids, was higher in CPG and TG of the GDM group by 73% and 76%. The adrenic/osbond acid (22:4n-6/22:5n-6) ratio, a biochemical marker of DHA insufficiency, was reduced in CPG (-4.5%), TG (-63%) and CE (-75%) of the GDM group. These findings, which are consistent with the previous red cell data, suggest that the neuro-visual and vascular development and function of the offspring of GDM women may be adversely affected if the levels of AA and DHA are compromised further by other factors, pre- or post-natally. Studies are required to elucidate the underlying mechanism for the reduction of the two fatty acids and to evaluate the developmental and health implications.     

Pro12Ala substitution in the peroxisome proliferator-activated receptor-gamma is associated with increased leptin levels in women with type-2 diabetes mellitus

OBJECTIVE: To analyze the relationship between the peroxisome proliferator-activated receptor-gamma (PPARgamma2) Pro12Ala variant and type-2 diabetes mellitus and its correlation with some cytokine determinants of insulin resistance such as tumor necrosis factor (TNF)-alpha and leptin. METHODS: The PPARgamma2 Pro12Ala genetic polymorphism was studied in 167 type-2 diabetic patients and 63 healthy controls. Serum leptin and plasma-soluble TNF-R2 were measured. RESULTS: Women carriers of the Pro12Ala mutation exhibited higher leptin levels than women non-carriers (median 31.4 vs. 17.5 ng/ml; p < 0.005). sTNF-R2 levels did not show differences between the two genotypes. Analysis by the multiple linear regression model of leptin-body mass index controlled by the PPARgamma2 genotype showed that leptin levels were determined by the Pro12Ala mutation in type-2 diabetic women but not in men. CONCLUSIONS: PPARgamma2 seems to be implicated in leptin homeostasis in type-2 diabetic women.     

Influence of the PPAR-gamma2 Pro12Ala and ACE I/D polymorphisms on insulin sensitivity and training effects in healthy offspring of type 2 diabetic subjects.

Aerobic endurance training improves insulin sensitivity, and is of great importance in the prevention and treatment of type 2 diabetes. The improvement in insulin sensitivity and cardiovascular function through exercise is highly variable among individuals, and is probably partly determined by genetic components. This study evaluated the peroxisome proliferation-activated receptor-gamma2 ( PPAR-gamma2) Pro12Ala polymorphism and the angiotensin converting enzyme ( ACE) I/D polymorphism with respect to any potential influence that these highly prevalent polymorphisms may impose on changes in insulin sensitivity and maximal aerobic capacity induced by exercise. Seventy-nine healthy first-degree relatives of type 2 diabetic patients were compared to a control group consisting of 54 subjects without any family history of type 2 diabetes. All subjects had a normal OGTT. The groups were comparable with respect to age (34 +/- 7 vs. 33 +/- 7 years), gender ((m/f) 43/36 vs. 30/24) and BMI (25.7 +/- 2.6 vs. 25.3 +/- 2.5 kg/m (2)); p (all) = NS. Furthermore, a subgroup of 29 offspring and 17 control subjects were engaged in a standardized training program lasting ten weeks. Insulin sensitivity (hyperinsulinemic euglycemic clamp technique) and VO (2)max (exhaustive exercise test) was assessed before and after the training period. We will demonstrate the allelic frequency of the Ala-allele of the Pro12Ala polymorphism to be lower in offspring to type 2 diabetic patients (13.3 %) compared to control subjects (21.3 %); p < 0.05. In offspring only, the Pro12Ala polymorphism of the PPAR-gamma2 gene appeared to enhance weight changes brought about by exercise (Deltaweight = - 0.3 +/- 1.4 kg vs. - 1.8 +/- 1.8 kg; p < 0.05; (Pro/Pro vs. Pro/Ala + Ala/Ala) - suggesting possible gene-environment or gene-gene interactions. The ACE I/D polymorphism was not of significant importance in determining the capability of responding to exercise in terms of improvement in insulin sensitivity or maximal aerobic capacity.     

Changes in lipoprotein subfraction concentration and composition in healthy individuals treated with the CETP inhibitor anacetrapib

We investigated the effects of the cholesteryl ester (CE) transfer protein inhibitor anacetrapib (ANA) on plasma lipids, lipoprotein subfraction concentrations, and lipoprotein composition in 30 healthy individuals. Participants (n = 30) were randomized to ANA 20 mg/day, 150 mg/day, or placebo for 2 weeks. Changes in concentration of lipoprotein subfractions were assessed using ion mobility, and compositional analyses were performed on fractions separated by density gradient ultracentrifugation. ANA 150 mg/day versus placebo resulted in significant decreases in LDL-cholesterol (26%) and apo B (29%) and increases in HDL-cholesterol (82%). Concentrations of medium and small VLDL, large intermediate density lipoprotein (IDL), and medium and small LDL (LDL2a, 2b, and 3a) decreased whereas levels of very small and dense LDL4b were increased. There was enrichment of triglycerides and reduction of CE in VLDL, IDL, and the densest LDL fraction. Levels of large buoyant HDL particles were substantially increased, and there was enrichment of CE, apo AI, and apoCIII, but not apoAII or apoE, in the mid-HDL density range. Changes in lipoprotein subfraction concentrations and composition with ANA 20 mg/day were similar to those for ANA 150 mg/day but were generally smaller in magnitude. The impact of these changes on cardiovascular risk remains to be determined.     

Effect of n-3 and n-6 polyunsaturated fatty acids on lymphocyte proliferation, interleukin production and phospholipid fatty acids composition in type 2 diabetic and healthy subjects in Jordan people

Dietary lipid manipulation may affect a great number of immune parameters, such as lymphocyte proliferation, cytokine synthesis. In this study, lymphocytes of diabetic type 2 were incubated with different polyunsaturated fatty acid (docosahexaenoic, eicosapentaenoic, arachidonic acid) for investigated their effect on lymphoproliferation response, the concentration of interleukin 2 produced in each essay and phospholipid fatty acid composition of lymphocyte membrane. Our results found that the concanavalin A and insulin increase significantly the proliferative response while eicosapentaenoic, arachidonic and docosahexaenoic acid inhibited that by different degrees: 47%, 37% and 19%, respectively, for healthy subjects and 39%, 29% and 13% for diabetes. However, the concentration of IL-2 produced in presence of either docosahexaenoic, eicosapentaenoic or arachidonic acid was significantly reduced by 36%, 32% and 39%, respectively, in controls while 16%, 15% and 23%, respectively, in diabetics. On the other hand, the tested fatty acids demonstrated a major impact on the fatty acid composition of different phospholipid fractions of lymphocyte membrane but these fractions were different in their response to each fatty acid examined. For instance, the addition of docosahexaenoic acid to culture media was accompanied with a predominant composition of docosahexaenoic acid in phospholipid fractions. Also, our results showed a notable increased proportion of arachidonic, eicosapentaenoic and docosahexaenoic acids in control phospholipid fractions than those of diabetic.     

Ala45Thr variation in neuroD1 gene is associated with early-onset type 2 diabetes with or without diabetic pedigree in Chinese

Objective: Based on onset-age stratified analysis may be useful to determine the association of NeuroD1-Ala45Thr variation with susceptibility to genetic heterogeneous type 2 diabetes mellitus (T2DM), we investigated the Ala45Thr variation in unrelated early-onset and late-onset T2DM with or without diabetic pedigree and unrelated non-diabetic control subjects in Chinese. Methods: 175 early-onset and 194 late-onset type 2 diabetic patients were further divided into two subgroups according to with or without diabetic pedigree respectively. This NeuroD1-Ala45Thr variation were screened by PCR-direct sequencing in above 369 type 2 diabetic patients and 87 unrelated non-diabetic control subjects. We then compared the distribution of the Ala45Thr variation among the groups, searching for the predictive trends. Results: Frequencies of the variant (AA + GA genotype) in early-onset T2DM are obviously elevated, especially among diabetic pedigree subjects when compared to non-diabetic controls (p= 0.003) and late-onset T2DM subjects (p = 0.014). However, no significant differences were observed between late-onset T2DM with or without diabetic pedigree and non-diabetic control subjects. Conclusions: Our results suggest that 1) the NeuroD1-Ala45Thr variation may itself have an important role in susceptibility to or be in disequilibrium with early-onset T2DM in Chinese; 2) the Ala45Thr may affect the onset pattern of T2DM, i.e., early-onset but not late-onset T2DM in Chinese; and 3) onset-age stratified analysis may be useful to determine the association of NeuroD1-Ala45Thr variation with susceptibility to genetic heterogeneous T2DM in Chinese.     

Carnosinase concentration,activity, and CNDP1 genotype in patients with type 2 diabetes with and without nephropathy

Amino Acids - This study assessed if serum carnosinase (CNDP1) activity and concentration in patients with type 2 diabetes mellitus (T2D) with diabetic nephropathy (DN) differs from those without...