Michael M. Hoffmann

Association of eGFR-Related Loci Identified by GWAS with Incident CKD and ESRD

Family studies suggest a genetic component to the etiology of chronic kidney disease (CKD) and end stage renal disease (ESRD). Previously, we identified 16 loci for eGFR in genome-wide association studies, but the associations of these single nucleotide polymorphisms (SNPs) for incident CKD or ESRD are unknown. We thus investigated the association of these loci with incident CKD in 26,308 individuals of European ancestry free of CKD at baseline drawn from eight population-based cohorts followed for a median of 7.2 years (including 2,122 incident CKD cases defined as eGFR <60ml/min/1.73m2 at follow-up) and with ESRD in four case-control studies in subjects of European ancestry (3,775 cases, 4,577 controls). SNPs at 11 of the 16 loci (UMOD, PRKAG2, ANXA9, DAB2, SHROOM3, DACH1, STC1, SLC34A1, ALMS1/NAT8, UBE2Q2, and GCKR) were associated with incident CKD; p-values ranged from pu200a=u200a4.1e-9 in UMOD to pu200a=u200a0.03 in GCKR. After adjusting for baseline eGFR, six of these loci remained significantly associated with incident CKD (UMOD, PRKAG2, ANXA9, DAB2, DACH1, and STC1). SNPs in UMOD (ORu200a=u200a0.92, pu200a=u200a0.04) and GCKR (ORu200a=u200a0.93, pu200a=u200a0.03) were nominally associated with ESRD. In summary, the majority of eGFR-related loci are either associated or show a strong trend towards association with incident CKD, but have modest associations with ESRD in individuals of European descent. Additional work is required to characterize the association of genetic determinants of CKD and ESRD at different stages of disease progression.

Plasma PCSK9 is increased by Fenofibrate and Atorvastatin in a non-additive fashion in diabetic patients

OBJECTIVEnProprotein convertase subtilisin kexin/type 9 (PCSK9) is an inhibitor of the low density (LDL) lipoprotein receptor. Plasma PCSK9 is increased by fenofibrate and statins. Here, we determined how standard dose of statin and combined therapy with fenofibrate modulate PCSK9.nnnMETHODSnRandomized, open-label cross-over study investigating the effect of fenofibrate (160 mg), atorvastatin (10 mg), and combination of both in patients with type 2 diabetes mellitus and atherogenic dyslipidemia. After the single administration of atorvastatin and fenofibrate for 6 weeks, patients received both for another 6 weeks. PCSK9, lipids and lipoproteins levels were determined at day 1, weeks 6, 9 and 12.nnnRESULTSnUpon 6 weeks of treatment, atorvastatin decreased LDL-cholesterol by 30% (p<0.001) and fenofibrate decreased triglyceride level by 31% (p<0.01) and increased HDL-cholesterol by 13% (p<0.05). Combination did not show further benefit. Atorvastatin increased PCSK9 by 24% at day 1 and by 14% at week 6 (p < or = 0.01). Fenofibrate increased PCSK9 by 26% at week 6 (p < or = 0.01), but had no effect at day 1. Three weeks of combination therapy increased PCSK9 by 42%, 6 weeks by 19% (p < or = 0.01). PCSK9 changes were not different between treatments over 6-week periods.nnnCONCLUSIONnFenofibrate and atorvastatin increased circulating PCSK9 in diabetic patients, with no additive effect after 6 weeks of combined therapy.

Genetic variants of the promoter of the heme oxygenase-1 gene and their influence on cardiovascular disease (The Ludwigshafen Risk and Cardiovascular Health Study)

BackgroundHeme oxygenase-1 is an inducible cytoprotective enzyme which handles oxidative stress by generating anti-oxidant bilirubin and vasodilating carbon monoxide. A (GT)n dinucleotide repeat and a -413A>T single nucleotide polymorphism have been reported in the promoter region of HMOX1 to both influence the occurrence of coronary artery disease and myocardial infarction. We sought to validate these observations in persons scheduled for coronary angiography.MethodsWe included 3219 subjects in the current analysis, 2526 with CAD including a subgroup of CAD and MI (n = 1339) and 693 controls. Coronary status was determined by coronary angiography. Risk factors and biochemical parameters (bilirubin, iron, LDL-C, HDL-C, and triglycerides) were determined by standard procedures. The dinucleotide repeat was analysed by PCR and subsequent sizing by capillary electrophoresis, the -413A>T polymorphism by PCR and RFLP.ResultsIn the LURIC study the allele frequency for the -413A>T polymorphism is A = 0,589 and T = 0,411. The (GT)n repeats spread between 14 and 39 repeats with 22 (19.9%) and 29 (47.1%) as the two most common alleles. We found neither an association of the genotypes or allelic frequencies with any of the biochemical parameters nor with CAD or previous MI.ConclusionAlthough an association of these polymorphisms with the appearance of CAD and MI have been published before, our results strongly argue against a relevant role of the (GT)n repeat or the -413A>T SNP in the HMOX1 promoter in CAD or MI.

Vitamin D and Mortality: A Mendelian Randomization Study

BACKGROUNDnDecreased circulating 25-hydroxy-vitamin D (25-OH-vitamin D) concentrations have been associated with mortality rates, but it is unclear whether this association is causal. We performed a Mendelian randomization study and analyzed whether 3 common single-nucleotide polymorphisms (SNPs) associated with 25-OH-vitamin D concentrations are causal for mortality rates.nnnMETHODSnGenotypes of SNPs in the group-specific component gene (GC, rs2282679), 7-dehydrocholesterol reductase gene (DHCR7, rs12785878), and cytochrome P450 IIR-1 gene (CYP2R1, rs10741657) were determined in a prospective cohort study of 3316 male and female participants [mean age 62.6 (10.6) years] scheduled for coronary angiography between 1997 and 2000. 25-OH-vitamin D concentrations were determined by RIA. The main outcome measures were all-cause deaths, cardiovascular deaths, and noncardiovascular deaths.nnnRESULTSnIn a linear regression model adjusting for month of blood sampling, age, and sex, vitamin D concentrations were predicted by GC genotype (P < 0.001), CYP2R1 genotype (P = 0.068), and DHCR7 genotype (P < 0.001), with a coefficient of determination (r(2)) of 0.175. During a median follow-up time of 9.9 years, 955 persons (30.0%) died, including 619 deaths from cardiovascular causes. In a multivariate Cox regression adjusted for classical risk factors, GC, CYP2R1, and DHCR7 genotypes were not associated with all-cause mortality, cardiovascular mortality, or noncardiovascular mortality.nnnCONCLUSIONSnGenetic variants associated with 25-OH-vitamin D concentrations do not predict mortality. This suggests that low 25-OH-vitamin D concentrations are associated with, but unlikely to be causal for, higher mortality rates.

Genetic variants and haplotypes of lipoprotein associated phospholipase A2 and their influence on cardiovascular disease (The Ludwigshafen Risk and Cardiovascular Health Study)

Summary.u2002 Background:u2002 There is increasing evidence that lipoprotein‐associated phospholipase A2 (LpPLA2) is associated with cardiovascular disease. However, it is still unclear whether LpPLA2 is simply a marker or has a causal role as either a pro‐ or anti‐atherogenic factor. Methods:u2002 We analyzed the association of five polymorphisms (−1357G>A, −403T>C, Arg92His, Ile198Thr, Ala379Val) and related haplotypes at the PLA2G7 locus with angiographic coronary artery disease (CAD), plasma LpPLA2 activity, and long‐term survival in 3234 patients scheduled for coronary angiography. Results:u2002 The promoter variant −403C and His92 were associated with a decrease and Val379 with an increase in plasma LpPLA2 activity. Both coding variants revealed a clear gene‐dose effect. Interestingly, the rare Thr198 allele, which was not associated with any change in plasma LpPLA2 activity, was more frequent in subjects without CAD (Pu2003=u20030.009), with an adjusted odds ratio for CAD of 0.69 (95% CI: 0.49–0.96; Pu2003=u20030.029). None of the analyzed variants showed any robust association with all‐cause or cardiovascular mortality. Conclusion:u2002 Irrespective of the significant association between some variants with plasma LpPLA2 activity, it is still unclear whether these polymorphisms or haplotypes are associated with the risk and outcome of cardiovascular disease in Caucasians.

Ezetimibe alone and in combination lowers the concentration of small, dense low-density lipoproteins in type 2 diabetes mellitus

OBJECTIVEnThe effectiveness of the cholesterol absorption inhibitor ezetimibe on LDL subfractions and ultimately on the atherosclerotic risk profile remains controversial. We thus determined the concentration of atherogenic small, dense LDL (sdLDL) in patients with type 2 diabetes and an elevated cardiovascular risk profile.nnnRESEARCH DESIGN AND METHODSnMulticenter, randomized, open-label 6-week study investigating the effect of ezetimibe 10mg (E), simvastatin 20mg (S) and the combination of ezetimibe-/simvastatin 10/20mg (C) on the concentration of sdLDL separated from fresh plasma by gradient ultracentrifugation in patients with type 2 diabetes (NCT01384058).nnnRESULTSnFifty-six patients were screened for sdLDL, 41 were randomized, and 40 patients (12 E, 14 S and 14 C) completed the study. Total and LDL cholesterol fell by 14% (p=0.004) and 15% (p=0.006) with E, 22% (p<0.001) and 32% (p<0.001) with S, and 32% (p<0.001) and 44% (p<0.001) with C, respectively. E reduced the concentration of sdLDL by 20% (p=0.043) whereas S and C reduced sdLDL by 24% (p=0.020) and 33% (p=0.003), respectively, and non-sdLDL by 28% (p=0.004) and 42% (p<0.001), respectively. However, the further drop in sdLDL by adding E to S was not significant.nnnCONCLUSIONnEzetimibe alone and in combination with simvastatin reduced the concentration of atherogenic sdLDL in patients with type 2 diabetes.

CYP4A11 polymorphism correlates with coronary endothelial dysfunction in patients with coronary artery disease—The ENCORE Trials

BACKGROUNDnCytochrome P450 (CYP) is expressed in the human endothelium and metabolizes arachidonic acid into vasoactive epoxyeicosatrienoic and 20-hydroxyeicosatetraenoic acids. CYP enzymes have been linked to hypertension and generation of reactive oxygen species. Thus, we investigated the impact of several CYP polymorphisms on coronary endothelial function in patients with coronary artery disease (CAD).nnnMETHODS AND RESULTSnWe determined CYP4A11 F434S, CYP2C9 I359L, CYP2C9 G144C and CYP 2J2 promotor -50G>T polymorphisms in 734 patients with CAD undergoing percutaneous coronary intervention. Increasing concentrations of acetylcholine were infused in a coronary segment without angiographically significant CAD and the coronary artery vasomotor response was measured by quantitative angiography. Patients with substitution of phenylalanine 434 by serine (434SS, n=15, 2.04%) in CYP4A11 F434 demonstrated significantly augmented endothelium-dependent vasoconstriction (p=0.044 after Bonferroni correction) compared to patients with the 434FS (n=193, 26.29%) and 434FF genotype (n=526, 71.66%) before and after adjustment for blood pressure and HDL-cholesterol. In addition, patients with the 434SS genotype had higher systolic blood pressure levels (p=0.039) compared to the two other groups. The CYP 2C9 and CYP 2J2 polymorphisms did not show any correlation with coronary vasoconstriction, hypertension, diabetes mellitus, blood pressure or cholesterol.nnnCONCLUSIONnIn patients with established and stable coronary artery disease the 434SS variant of CYP4A11 F434 is associated with pronounced coronary vasoconstriction.

Association of the single nucleotide polymorphism rs599839 in the vicinity of the sortilin 1 gene with LDL and triglyceride metabolism, coronary heart disease and myocardial infarction. The Ludwigshafen Risk and Cardiovascular Health Study.

OBJECTIVEnThe rs599839 polymorphism A/G in the vicinity of the sortilin 1 gene has been reported to be associated with low density lipoprotein cholesterol (LDL-C) and coronary artery disease (CAD). The objective of this study was to further characterize the protective effect of the minor allele by analyzing the association with a variety of quantitative traits.nnnMETHODSnAssociation of rs599839 with plasma levels of different parameters of LDL and triglyceride (TRIG) metabolism as well as the risk of CAD was tested in the LURIC study cohort.nnnRESULTSnCompared to AA homozygotes, the levels of LDL-C, low density lipoprotein triglycerides (LDL-TRIG) and apolipoprotein B were decreased in carriers of at least one G-allele. The G-allele was also associated with an increasing radius of the LDL particles. Regarding TRIG metabolism we observed a significant decrease in the level of triglycerides for homozygous carriers of the G-allele as well as decreased levels of free fatty acids (FFA), free glycerol and free cholesterol. With each G-allele the prevalence of CAD (multivariate OR 0.806; 95% CI: 0.692-0.940, P=0.006) decreased significantly whereas we observed only a marginal decrease for MI which did not reach significance. For GG homozygotes, the OR for CAD was 0.588 (95% CI: 0.394-0.877; P=0.009) and the OR for previous myocardial infarction (MI) was 0.693 (95% CI: 0.490-0.980; P=0.038). These associations were independent of cardiovascular risk factors.nnnCONCLUSIONnIn the LURIC Study the G-allele of rs599839 is associated with LDL and TRIG metabolism and the risk of coronary artery disease and myocardial infarction.

Fluvastatin/fenofibrate vs. simvastatin/ezetimibe in patients with metabolic syndrome : different effects on LDL-profiles

Backgroundu2002 Patients with metabolic syndrome (MS) and type 2 diabetes (T2DM) show increased risk for coronary artery disease. Lipoprotein metabolism is characterized by elevated triglycerides (TG), low high‐density lipoprotein cholesterol (HDL‐C) and predominance of atherogenic small, dense low‐density lipoprotein (sdLDL), while low‐density lipoprotein (LDL) cholesterol is only slightly elevated.

CRP and CD14 polymorphisms correlate with coronary plaque volume in patients with coronary artery disease – IVUS substudy of the ENCORE trials

BACKGROUNDnSeveral proinflammatory single-nucleotide polymorphisms (SNPs) have been linked to the progression of atherosclerosis and coronary artery disease (CAD). Plaque size and its destabilization by inflammatory processes are major determinants of ischemia and acute coronary syndromes. Intravascular ultrasound (IVUS) allows for quantification of plaque size in vivo. We therefore investigated the relation of plaque size with mutations of proinflammatory genes in patients with CAD.nnnMETHODSnIn 196 patients with stable CAD enrolled in the ENCORE trials coronary plaque and vessel volume was assessed by IVUS. 173 patients were successfully genotyped for polymorphisms of proinflammatory genes CD14 C(-260)T and CRP C(+1444)T using the single-nucleotide polymorphism polymerase chain reaction (SNP PCR) approach.nnnRESULTSnBaseline characteristics were comparable for all genotype groups. Higher ratios of plaque volume/vessel volume were observed in patients with the CRP 1444TT (n=11) and CD14 260TT (n=33) genotypes (p=0.016 and p=0.026, respectively).nnnCONCLUSIONnIn patients with stable coronary artery disease the CRP 1444TT and CD14 260TT variants are associated with larger coronary plaque volume independently of concomitant cardiovascular risk factors.