Large-scale gene-centric meta-analysis across 39 studies identifies type 2 diabetes loci.

To identify genetic factors contributing to type 2 diabetes (T2D), we performed large-scale meta-analyses by using a custom ∼50,000 SNP genotyping array (the ITMAT-Broad-CARe array) with ∼2000 candidate genes in 39 multiethnic population-based studies, case-control studies, and clinical trials totaling 17,418 cases and 70,298 controls. First, meta-analysis of 25 studies comprising 14,073 cases and 57,489 controls of European descent confirmed eight established T2D loci at genome-wide significance. In silico follow-up analysis of putative association signals found in independent genome-wide association studies (including 8,130 cases and 38,987 controls) performed by the DIAGRAM consortium identified a T2D locus at genome-wide significance (GATAD2A/CILP2/PBX4; p = 5.7 × 10(-9)) and two loci exceeding study-wide significance (SREBF1, and TH/INS; p < 2.4 × 10(-6)). Second, meta-analyses of 1,986 cases and 7,695 controls from eight African-American studies identified study-wide-significant (p = 2.4 × 10(-7)) variants in HMGA2 and replicated variants in TCF7L2 (p = 5.1 × 10(-15)). Third, conditional analysis revealed multiple known and novel independent signals within five T2D-associated genes in samples of European ancestry and within HMGA2 in African-American samples. Fourth, a multiethnic meta-analysis of all 39 studies identified T2D-associated variants in BCL2 (p = 2.1 × 10(-8)). Finally, a composite genetic score of SNPs from new and established T2D signals was significantly associated with increased risk of diabetes in African-American, Hispanic, and Asian populations. In summary, large-scale meta-analysis involving a dense gene-centric approach has uncovered additional loci and variants that contribute to T2D risk and suggests substantial overlap of T2D association signals across multiple ethnic groups.

Genome-wide association study for circulating tissue plasminogen activator levels and functional follow-up implicates endothelial STXBP5 and STX2.

OBJECTIVE: Tissue plasminogen activator (tPA), a serine protease, catalyzes the conversion of plasminogen to plasmin, the major enzyme responsible for endogenous fibrinolysis. In some populations, elevated plasma levels of tPA have been associated with myocardial infarction and other cardiovascular diseases. We conducted a meta-analysis of genome-wide association studies to identify novel correlates of circulating levels of tPA. APPROACH AND RESULTS: Fourteen cohort studies with tPA measures (N=26 929) contributed to the meta-analysis. Three loci were significantly associated with circulating tPA levels (P<5.0×10(-8)). The first locus is on 6q24.3, with the lead single nucleotide polymorphism (SNP; rs9399599; P=2.9×10(-14)) within STXBP5. The second locus is on 8p11.21. The lead SNP (rs3136739; P=1.3×10(-9)) is intronic to POLB and <200 kb away from the tPA encoding the gene PLAT. We identified a nonsynonymous SNP (rs2020921) in modest linkage disequilibrium with rs3136739 (r(2)=0.50) within exon 5 of PLAT (P=2.0×10(-8)). The third locus is on 12q24.33, with the lead SNP (rs7301826; P=1.0×10(-9)) within intron 7 of STX2. We further found evidence for the association of lead SNPs in STXBP5 and STX2 with expression levels of the respective transcripts. In in vitro cell studies, silencing STXBP5 decreased the release of tPA from vascular endothelial cells, whereas silencing STX2 increased the tPA release. Through an in silico lookup, we found no associations of the 3 lead SNPs with coronary artery disease or stroke. CONCLUSIONS: We identified 3 loci associated with circulating tPA levels, the PLAT region, STXBP5, and STX2. Our functional studies implicate a novel role for STXBP5 and STX2 in regulating tPA release.

Association of 25-hydroxyvitamin D with type 2 diabetes among patients undergoing coronary angiography: cross-sectional findings from the LUdwigshafen Risk and Cardiovascular Health (LURIC) Study.

OBJECTIVE: Evidence suggests that vitamin D may protect against the onset of diabetes. However, the mechanisms underlying the role of vitamin D on glycaemic status are unclear and warrant further investigation. We sought to determine the relationship between serum 25-hydroxyvitamin D (25[OH]D) and glycaemic status among intermediate-to-high-risk patients scheduled for coronary angiography. METHODS: Participants were 3316 male and female patients (mean ± SD age, 62·7 ± 10·6 years). Four categories were formed according to serum 25[OH]D levels. The association between serum 25[OH]D and diabetes was assessed using multivariable logistic regression. RESULTS: Fasting and 2 h post-load glucose, HbA1c and the HOMA-IR indices diminished with increasing serum 25[OH]D levels (P < 0·001). However, no associations were observed between insulin, pro-insulin or C-peptide and serum 25[OH]D concentrations. The pro-inflammatory markers IL-6 and hs-CRP also decreased considerably with higher vitamin D levels (P < 0·001). After full adjustment, those with optimal serum 25[OH]D levels had a reduced odds for fasting diabetes (OR = 0·63; 95% CI, 0·46-0·86; Ptrend = 0·01), 2 h post-load diabetes (OR = 0·46; 95% CI, 0·29-0·74; Ptrend = 0·004), both fasting/2 h post-load diabetes (OR = 0·61; 95% CI, 0·42-0·87; Ptrend = 0·001) and all of the combined hyperglycaemic states (OR = 0·68; 95% CI, 0·52-0·80; Ptrend = 0·01). CONCLUSIONS: Higher serum 25[OH]D levels were associated with better glycaemic status and lower inflammation. Should these observations be confirmed in future studies, vitamin D supplementation may prove a useful adjunct in attenuating the onset of diabetes.

Homoarginine, cardiovascular risk, and mortality.

BACKGROUND: Homoarginine is an amino acid derivative that may increase nitric oxide availability and enhance endothelial function. The effect of the level of homoarginine on cardiovascular outcome and mortality is unknown. METHODS AND RESULTS: We assessed cardiovascular and all-cause mortality according to homoarginine levels in a cohort of 3,305 subjects referred for coronary angiography from the LUdwigshafen RIsk and Cardiovascular Health (LURIC) Study. After investigating the relation of homoarginine with kidney function and markers of endothelial dysfunction, we explored its effects on adverse outcomes in a second high-risk cohort of 1244 patients with type 2 diabetes mellitus receiving maintenance hemodialysis (4D study [Die Deutsche Diabetes Dialyse Studie]). In the LURIC study, mean serum homoarginine levels were 2.6+/-1.1 micromol/L. During a median follow-up of 7.7 years, 766 patients died. After adjustments for age and sex, patients in the lowest quartile (<1.85 micromol/L) had a >4-fold higher rate of dying of cardiovascular disease (hazard ratio 4.1, 95% confidence interval 3.0 to 5.7) than patients in the highest quartile (>3.1 micromol/L). Lower homoarginine levels were associated with lower estimated glomerular filtration rate and higher levels of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. Hemodialysed patients had lower mean homoarginine levels of 1.2+/-0.5 micromol/L and experienced a 5-fold increased mortality rate compared with LURIC patients (608 deaths during a median follow-up of 4 years). Homoarginine consistently affected mortality, which was 2-fold higher in 4D study patients in the lowest quartile (<0.87 micromol/L) than in patients in the highest quartile (>1.4 micromol/L). CONCLUSIONS: Homoarginine levels are independently associated with cardiovascular and all-cause mortality in patients referred for coronary angiography and in patients undergoing hemodialysis. Future studies are needed to elucidate the underlying pathomechanisms.

Low serum homoarginine is a novel risk factor for fatal strokes in patients undergoing coronary angiography.

BACKGROUND AND PURPOSE: Low serum concentrations of the amino acid homoarginine have been associated with endothelial dysfunction and an increased risk of all-cause and cardiovascular mortality. We aimed to investigate whether homoarginine levels are also associated with fatal strokes and a history of nonfatal cerebrovascular disease. METHODS: Serum homoarginine was measured in 3305 participants of the Ludwigshafen Risk and Cardiovascular Health (LURIC) study who were referred to coronary angiography at baseline (1997 to 2000) and were followed up with respect to mortality. RESULTS: During a median follow-up time of 9.9 years, 991 patients died including 61 fatal (ischemic and hemorrhagic) strokes. In a binary logistic regression analysis, the odds ratio (with 95% CI) for fatal stroke per SD of homoarginine was 0.52 (0.37 to 0.73; P<0.001) and remained significant after multivariable adjustments (0.62 [0.42 to 0.91]; P=0.014). For previous cerebrovascular disease events, the multivariable adjusted OR per SD of homoarginine was 0.82 (0.70 to 0.96; P=0.014). CONCLUSIONS: Low homoarginine levels are a novel risk factor for fatal strokes and are reduced in patients with a history of cerebrovascular disease. Further studies are needed to explore the significance of homoarginine to risk stratification and therapeutic approaches in the prevention of strokes.

C-reactive protein genotypes associated with circulating C-reactive protein but not with angiographic coronary artery disease: the LURIC study.

AIMS: Circulating C-reactive protein is associated with future cardiovascular events. The causal role of C-reactive protein in the development of atherosclerosis remains controversial. METHODS AND RESULTS: We analysed the association between three genetic polymorphisms (PM) (-717C>T, rs2794521; +1059G>C, rs1800947; +1444C>T, rs1130864) at the C-reactive protein locus and related haplotypes with both circulating C-reactive protein and angiographic coronary artery disease (CAD). The concentration of C-reactive protein was similar in patients with stable CAD and in controls, but increased in patients presenting with acute coronary syndromes. In models adjusting for the main confounding variables, the minor alleles of the +1059G>C (rs1800947) and the +1444C>T PM (rs1130864) were associated with decreased and increased concentrations of C-reactive protein, respectively. Haplotypes 1 and 4 decreased, and haplotype 2 increased C-reactive protein, whereas haplotype 3 had no appreciable effect. None of the genetic variants affecting circulating C-reactive protein was consistently associated with the prevalence of angiographic CAD. CONCLUSION: A causal role of C-reactive protein in the development of CAD would require that genetic PM resulting in long-term modulation of the concentration of C-reactive protein be themselves associated with CAD. We were not able to detect such a relationship, which can be attributed to either a very small genetic effect size or the relationship between C-reactive protein and cardiovascular events may reflect confounding and reverse causation.

Genetic variation in Fc gamma receptor IIa and risk of coronary heart disease: negative results from two large independent populations.

BACKGROUND: The role of the Fc gamma receptor IIa (Fc gamma RIIa), a receptor for C-reactive protein (CRP), the classical acute phase protein, in atherosclerosis is not yet clear. We sought to investigate the association of Fc gamma RIIa genotype with risk of coronary heart disease (CHD) in two large population-based samples. METHODS: Fc gamma RIIa-R/H131 polymorphisms were determined in a population of 527 patients with a history of myocardial infarction and 527 age and gender matched controls drawn from a population-based MONICA- Augsburg survey. In the LURIC population, 2227 patients with angiographically proven CHD, defined as having at least one stenosis >or= 50%, were compared with 1032 individuals with stenosis <50%. RESULTS: In both populations genotype frequencies of the Fc gamma RIIa gene did not show a significant departure from the Hardy-Weinberg equilibrium. Fc gamma RIIa R(-131) --> H genotype was not independently associated with lower risk of CHD after multivariable adjustments, neither in the MONICA population (odds ratio (OR) 1.08; 95% confidence interval (CI) 0.81 to 1.44), nor in LURIC (OR 0.96; 95% CI 0.81 to 1.14). CONCLUSION: Our results do not confirm an independent relationship between Fc gamma RIIa genotypes and risk of CHD in these populations.

Regulation of cyclin D1 expression by autocrine IGF-I in human BON neuroendocrine tumour cells.

Constitutive expression of cyclin D1 is a frequent abnormality in human cancer and sustains the transformed phenotype. We have previously demonstrated that cyclin D1 is constitutively expressed in human BON neuroendocrine tumour cells due to an autocrine insulin-like growth factor-I (IGF-I) loop. Here we examine the regulation of cyclin D1 expression by endogenously released IGF-I in BON cells. Cyclin D1 expression in these cells was found to be dependent on phosphatidylinositol 3-kinase (PI3-K), but independent of the extracellular signal-regulated kinase cascade. Ras- and Rac-GTPases were found to be upstream activators of cyclin D1 expression, whereas protein kinase B/AKT and nuclear factor kappa B (NFkappaB) could be established as downstream mediators of cyclin D1 transcription in response to endogenously released IGF-I in these cells. In addition, the Ras/PI3-K/AKT/Rac/NFkappaB/cyclin D1 signaling cascade triggered by endogenously released IGF-I is sufficient to sustain Rb phosphorylation and cdk4 kinase activity in BON cells. In conclusion, our data provide the first comprehensive map of the signaling events elicited by endogenously released IGF-I leading to constitutive cyclin D1 expression in human neuroendocrine tumour cells.

Platelet-activating factor acetylhydrolase activity indicates angiographic coronary artery disease independently of systemic inflammation and other risk factors: the Ludwigshafen Risk and Cardiovascular Health Study.

BACKGROUND: Platelet-activating factor acetylhydrolase (PAF-AH), also denoted as lipoprotein-associated phospholipase A2, is a lipoprotein-bound enzyme that is possibly involved in inflammation and atherosclerosis. This study investigates the relationship of PAF-AH activity to angiographic coronary artery disease (CAD), the use of cardiovascular drugs, and other established risk factors. METHODS AND RESULTS: PAF-AH activity, lipoproteins, sensitive C-reactive protein (sCRP), fibrinogen, serum amyloid A, and white blood cell count were determined in 2454 subjects with angiographically confirmed CAD and in 694 control subjects. PAF-AH activity was highly correlated with LDL cholesterol (r=0.517), apolipoprotein B (r=0.644), and non-HDL cholesterol (r=0.648) but not with sCRP or fibrinogen. PAF-AH activity was lower in women than in men and was affected by the intake of lipid-lowering drugs (-12%; P<0.001), aspirin (-6%; P<0.001), beta-blockers (-6%; P<0.001), and digitalis (+7%; P<0.001). Unlike sCRP, fibrinogen, and serum amyloid A, PAF-AH activity was not elevated in unstable angina, non-ST-elevation myocardial infarction, or ST-elevation myocardial infarction. When nonusers of lipid-lowering drugs were examined, PAF-AH activity was associated with the severity of CAD and the number of coronary vessels with significant stenoses. In individuals not taking lipid-lowering drugs and after adjustment for use of aspirin, beta-blocker, and digitalis, the odds ratio for CAD associated with increasing PAF-AH activity was 1.39 (95% CI 1.26 to 1.54, P<0.001), a finding that was robust against further adjustments. CONCLUSIONS: PAF-AH activity is not an indicator of the systemic inflammation that accompanies acute coronary syndromes. PAF-AH activity is affected by a number of cardiovascular drugs; however, after such medication use was accounted for, PAF-AH activity was associated with angiographic CAD, complementary to sCRP and independently of established risk factors such as LDL cholesterol.

The interleukin-6 G(-174)C promoter polymorphism in the LURIC cohort: no association with plasma interleukin-6, coronary artery disease, and myocardial infarction.

IL-6 plasma levels are predictive of major cardiovascular events. Recently a G/C polymorphism at position -174 in the promoter of the IL-6 gene has been associated with differences in both the IL-6 transcription rate in vitro and IL-6 levels in vivo. We examined the association of this polymorphism with coronary artery disease (CAD) and previous myocardial infarction (MI) in 2559 patients with angiographically documented CAD with ( n=1365) and without ( n=1194) MI and in a control group of 729 individuals in whom CAD had been ruled out angiographically. Assuming dominant or recessive modes of inheritance, carriers of the G allele had odds ratios of 0.98 (95% CI 0.79 - 1.20) and 0.96 (95% CI 0.80 - 1.14), respectively, for CAD, and almost identical ones for previous MI. In subgroups stratified for low cardiovascular risk, the IL-6 promoter polymorphism was also not related to the risk of CAD or MI. In addition, the plasma concentration of IL-6 did not differ between groups with different IL-6 genotypes in 942 randomly selected individuals. We conclude that the IL-6 G(-174)C polymorphism is not associated with the risk of CAD or MI and does not contribute to cardiovascular risk stratification.

Effects of statins on C-reactive protein and interleukin-6 (the Ludwigshafen Risk and Cardiovascular Health study).

This report provides preliminary evidence that statins may lower C-reactive protein levels by interfering with the generation and/or release of C-reactive protein in the liver rather than by modulating inflammatory processes in the vessel wall.

Glucose substitution prolongs maintenance of energy homeostasis and lifespan of telomere dysfunctional mice.

DNA damage and telomere dysfunction shorten organismal lifespan. Here we show that oral glucose administration at advanced age increases health and lifespan of telomere dysfunctional mice. The study reveals that energy consumption increases in telomere dysfunctional cells resulting in enhanced glucose metabolism both in glycolysis and in the tricarboxylic acid cycle at organismal level. In ageing telomere dysfunctional mice, normal diet provides insufficient amounts of glucose thus leading to impaired energy homeostasis, catabolism, suppression of IGF-1/mTOR signalling, suppression of mitochondrial biogenesis and tissue atrophy. A glucose-enriched diet reverts these defects by activating glycolysis, mitochondrial biogenesis and oxidative glucose metabolism. The beneficial effects of glucose substitution on mitochondrial function and glucose metabolism are blocked by mTOR inhibition but mimicked by IGF-1 application. Together, these results provide the first experimental evidence that telomere dysfunction enhances the requirement of glucose substitution for the maintenance of energy homeostasis and IGF-1/mTOR-dependent mitochondrial biogenesis in ageing tissues.

Low serum zinc levels in patients undergoing coronary angiography correlate with immune activation and inflammation.

INTRODUCTION: Low serum zinc concentrations are associated with adverse outcomes. To explain this phenomenon we aimed to investigate whether low zinc levels are related to immune activation, renal function and coronary artery disease (CAD). METHODS: Serum concentrations of zinc and the immune activation markers neopterin and C-reactive protein (CRP) were measured in 2048 patients derived from the LUdwigshafen RIsk and Cardiovascular Health (LURIC) study, a cohort study among patients referred for coronary angiography. RESULTS: Zinc concentrations did not differ between patients with CAD (mean±SD: 13.3±2.4 µmol/L) and controls (13.3±2.2 µmol/L; Welch's t test: p=n.s.) but CAD patients had higher neopterin (8.6±7.4 nmol/L) and CRP (9.7±19.6 mg/L) concentrations compared to controls (neopterin: 7.5±4.8 nmol/L, p=0.0005; CRP: 5.5±10.0 mg/L, p<0.0001). There was an inverse correlation between serum zinc concentrations and neopterin (Spearman's rank correlation: r(s)=-0.222) and CRP (r(s)=-0.166; both p<0.0001) concentrations. CONCLUSIONS: Our results indicate increased inflammatory processes in patients with low zinc levels. Further studies should clarify whether inflammation related processes such as renal wasting contribute to zinc deficiency and underlie the adverse health consequences of low serum zinc levels.

Vitamin D levels predict all-cause and cardiovascular disease mortality in subjects with the metabolic syndrome: the Ludwigshafen Risk and Cardiovascular Health (LURIC) Study.

OBJECTIVE: Optimal vitamin D levels are associated with reduced cardiovascular and all-cause mortality. We investigated whether optimal 25-hydroxyvitamin D (25[OH]D) is protective in individuals with the metabolic syndrome. RESEARCH DESIGN AND METHODS: The Ludwigshafen Risk and Cardiovascular Health (LURIC) study is a cohort study of subjects referred for coronary angiography between 1997 and 2000, from which 1,801 with the metabolic syndrome were investigated. Mortality was tracked for a median of 7.7 years. Multivariable survival analysis was used to estimate the association between 25(OH)D levels and mortality. RESULTS: Most subjects (92%) had suboptimal levels of 25(OH)D (<75 nmol/L), with 22.2% being severely deficient (<25 nmol/L). During follow-up, 462 deaths were recorded, 267 (57.8%) of which were cardiovascular in origin. After full adjustment, including the metabolic syndrome components, those with optimal 25(OH)D levels showed a substantial reduction in all-cause (hazard ratio [HR] 0.25 [95% CI 0.13-0.46]) and cardiovascular disease mortality (0.33 [0.16-0.66]) compared with those with severe vitamin D deficiency. For specific cardiovascular disease mortality, there was a strong reduction for sudden death (0.15 [0.04-0.63]) and congestive heart failure (0.24 [0.06-1.04]), but not for myocardial infarction. The reduction in mortality was dose-dependent for each of these causes. CONCLUSIONS: Optimal 25(OH)D levels substantially lowered all-cause and cardiovascular disease mortality in subjects with the metabolic syndrome. These observations call for interventional studies that test whether vitamin D supplementation provides a useful adjunct in reducing mortality in these subjects.

Apolipoprotein E genotypes, circulating C-reactive protein and angiographic coronary artery disease: the Ludwigshafen Risk and Cardiovascular Health Study.

C-reactive protein (CRP) has been implicated in the development of atherosclerosis. The genetic polymorphism of apolipoprotein (apo) E is associated with the concentration of CRP. We analyzed the association between the apo E genotype, CRP and angiographic coronary artery disease (CAD). The concentration of CRP was similar in patients with stable CAD and in controls, but increased in patients presenting with acute coronary syndromes. In models adjusting for the main confounding variables, the alleles ɛ4 and ɛ2 were associated with decreased and increased concentrations of CRP, respectively, compared to the wild-type allele ɛ3. In spite of this, the ɛ2 allele was associated with a lower prevalence of angiographic CAD, while the slight over-representation of the ɛ4 allele was statistically not significant. We conclude that the apo E genotype is associated with circulating CRP. A causal role of CRP in the development of CAD would be supported if genotypes that raise CRP in the long-term were themselves associated with CAD. As we found the opposite, we suggest that the association between CRP and cardiovascular events reflects confounding and reverse causation.

Inflammation, regeneration, and transformation in the pancreas: results of the Collaborative Research Center 518 (SFB 518) at the University of Ulm.

The primary diseases of the pancreas include diabetes mellitus, acute and chronic pancreatitis, as well as pancreatic carcinoma. This review presents findings and emerging questions on the diseases of the pancreas obtained by the consortium of the Collaborative Research Center 518 (SFB 518), "Inflammation, Regeneration, and Transformation in the Pancreas" at the University of Ulm. During the last 12 years, the SFB 518 contributed considerably to the understanding of the cellular and molecular basis of pancreatic diseases and established the basis for the development of new strategies for prevention and causal therapy for diabetes, pancreatitis, and pancreatic cancer.

Inverse association between serum concentrations of neopterin and antioxidants in patients with and without angiographic coronary artery disease.

Neopterin is released from human monocyte-derived macrophages upon stimulation with interferon-gamma and is a sensitive indicator for cellular immune activation. Furthermore, reactive oxygen species (ROS) are produced in case of immune activation and inflammation. In a cross-sectional approach, plasma concentrations of neopterin and of antioxidant compounds and vitamins were compared in 1463 patients investigated by coronary angiography, which were recruited within the LUdwigshafen RIsk and Cardiovascular Health (LURIC) study. Serum neopterin concentrations were higher in patients with coronary artery disease (CAD; mean+/-S.D.: 8.7+/-7.3 nmol/L) compared to controls (7.4+/-5.0 nmol/L; Welch's t-test: p<0.001). Mean concentrations of ascorbic acid (p<0.0001), gamma-tocopherol (p<0.05), lycopene (p<0.001), lutein+zeaxanthin (p<0.05), alpha-carotene (p<0.05) and beta-carotene (p<0.05) were lower in CAD than in controls. Neopterin concentrations correlated with CAD-score (r(s)=0.156; p<0.0001) and inversely with antioxidants lycopene (r(s)=-0.277; p<0.0001) and lutein+zeaxanthin (r(s)=-0.175; p<0.0001) levels and with vitamins ascorbic acid (r(s)=-0.207; p<0.0001) and alpha-tocopherol (r(s)=-0.105; p<0.0001). The study demonstrates that higher neopterin production is associated with lower concentrations of antioxidant compounds in patients at risk for atherosclerosis. Results suggest that lower concentrations of antioxidant compounds may relate to higher grade of chronic immune activation in patients.